1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/workgroup.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "interpreter/linkResolver.hpp"
41 #include "interpreter/oopMapCache.hpp"
42 #include "jvmtifiles/jvmtiEnv.hpp"
43 #include "logging/log.hpp"
44 #include "logging/logConfiguration.hpp"
45 #include "logging/logStream.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/handshake.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/prefetch.inline.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/safepointMechanism.inline.hpp"
82 #include "runtime/sharedRuntime.hpp"
83 #include "runtime/statSampler.hpp"
84 #include "runtime/stubRoutines.hpp"
85 #include "runtime/sweeper.hpp"
86 #include "runtime/task.hpp"
87 #include "runtime/thread.inline.hpp"
88 #include "runtime/threadCritical.hpp"
89 #include "runtime/threadSMR.inline.hpp"
90 #include "runtime/timer.hpp"
91 #include "runtime/timerTrace.hpp"
92 #include "runtime/vframe.hpp"
93 #include "runtime/vframeArray.hpp"
94 #include "runtime/vframe_hp.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "runtime/vm_operations.hpp"
97 #include "runtime/vm_version.hpp"
98 #include "services/attachListener.hpp"
99 #include "services/management.hpp"
100 #include "services/memTracker.hpp"
101 #include "services/threadService.hpp"
102 #include "trace/traceMacros.hpp"
103 #include "trace/tracing.hpp"
104 #include "utilities/align.hpp"
105 #include "utilities/defaultStream.hpp"
106 #include "utilities/dtrace.hpp"
107 #include "utilities/events.hpp"
108 #include "utilities/macros.hpp"
109 #include "utilities/preserveException.hpp"
110 #include "utilities/resourceHash.hpp"
111 #include "utilities/vmError.hpp"
112 #if INCLUDE_ALL_GCS
113 #include "gc/cms/concurrentMarkSweepThread.hpp"
114 #include "gc/g1/concurrentMarkThread.inline.hpp"
115 #include "gc/parallel/pcTasks.hpp"
116 #endif // INCLUDE_ALL_GCS
117 #if INCLUDE_JVMCI
118 #include "jvmci/jvmciCompiler.hpp"
119 #include "jvmci/jvmciRuntime.hpp"
120 #include "logging/logHandle.hpp"
121 #endif
122 #ifdef COMPILER1
123 #include "c1/c1_Compiler.hpp"
124 #endif
125 #ifdef COMPILER2
126 #include "opto/c2compiler.hpp"
127 #include "opto/idealGraphPrinter.hpp"
128 #endif
129 #if INCLUDE_RTM_OPT
130 #include "runtime/rtmLocking.hpp"
131 #endif
132
133 // Initialization after module runtime initialization
134 void universe_post_module_init(); // must happen after call_initPhase2
135
136 #ifdef DTRACE_ENABLED
137
138 // Only bother with this argument setup if dtrace is available
139
140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
142
143 #define DTRACE_THREAD_PROBE(probe, javathread) \
144 { \
145 ResourceMark rm(this); \
146 int len = 0; \
147 const char* name = (javathread)->get_thread_name(); \
148 len = strlen(name); \
149 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
150 (char *) name, len, \
151 java_lang_Thread::thread_id((javathread)->threadObj()), \
152 (uintptr_t) (javathread)->osthread()->thread_id(), \
153 java_lang_Thread::is_daemon((javathread)->threadObj())); \
154 }
155
156 #else // ndef DTRACE_ENABLED
157
158 #define DTRACE_THREAD_PROBE(probe, javathread)
159
160 #endif // ndef DTRACE_ENABLED
161
162 #ifndef USE_LIBRARY_BASED_TLS_ONLY
163 // Current thread is maintained as a thread-local variable
164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
165 #endif
166 // Class hierarchy
167 // - Thread
168 // - VMThread
169 // - WatcherThread
170 // - ConcurrentMarkSweepThread
171 // - JavaThread
172 // - CompilerThread
173
174 // ======= Thread ========
175 // Support for forcing alignment of thread objects for biased locking
176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
177 if (UseBiasedLocking) {
178 const int alignment = markOopDesc::biased_lock_alignment;
179 size_t aligned_size = size + (alignment - sizeof(intptr_t));
180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
181 : AllocateHeap(aligned_size, flags, CURRENT_PC,
182 AllocFailStrategy::RETURN_NULL);
183 void* aligned_addr = align_up(real_malloc_addr, alignment);
184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
186 "JavaThread alignment code overflowed allocated storage");
187 if (aligned_addr != real_malloc_addr) {
188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
189 p2i(real_malloc_addr),
190 p2i(aligned_addr));
191 }
192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
193 return aligned_addr;
194 } else {
195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
197 }
198 }
199
200 void Thread::operator delete(void* p) {
201 if (UseBiasedLocking) {
202 FreeHeap(((Thread*) p)->_real_malloc_address);
203 } else {
204 FreeHeap(p);
205 }
206 }
207
208 void JavaThread::smr_delete() {
209 if (_on_thread_list) {
210 Threads::smr_delete(this);
211 } else {
212 delete this;
213 }
214 }
215
216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
217 // JavaThread
218
219
220 Thread::Thread() {
221 // stack and get_thread
222 set_stack_base(NULL);
223 set_stack_size(0);
224 set_self_raw_id(0);
225 set_lgrp_id(-1);
226 DEBUG_ONLY(clear_suspendible_thread();)
227
228 // allocated data structures
229 set_osthread(NULL);
230 set_resource_area(new (mtThread)ResourceArea());
231 DEBUG_ONLY(_current_resource_mark = NULL;)
232 set_handle_area(new (mtThread) HandleArea(NULL));
233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
234 set_active_handles(NULL);
235 set_free_handle_block(NULL);
236 set_last_handle_mark(NULL);
237
238 // This initial value ==> never claimed.
239 _oops_do_parity = 0;
240 _threads_hazard_ptr = NULL;
241 _nested_threads_hazard_ptr = NULL;
242 _nested_threads_hazard_ptr_cnt = 0;
243
244 // the handle mark links itself to last_handle_mark
245 new HandleMark(this);
246
247 // plain initialization
248 debug_only(_owned_locks = NULL;)
249 debug_only(_allow_allocation_count = 0;)
250 NOT_PRODUCT(_allow_safepoint_count = 0;)
251 NOT_PRODUCT(_skip_gcalot = false;)
252 _jvmti_env_iteration_count = 0;
253 set_allocated_bytes(0);
254 _vm_operation_started_count = 0;
255 _vm_operation_completed_count = 0;
256 _current_pending_monitor = NULL;
257 _current_pending_monitor_is_from_java = true;
258 _current_waiting_monitor = NULL;
259 _num_nested_signal = 0;
260 omFreeList = NULL;
261 omFreeCount = 0;
262 omFreeProvision = 32;
263 omInUseList = NULL;
264 omInUseCount = 0;
265
266 #ifdef ASSERT
267 _visited_for_critical_count = false;
268 #endif
269
270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
271 Monitor::_safepoint_check_sometimes);
272 _suspend_flags = 0;
273
274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
275 _hashStateX = os::random();
276 _hashStateY = 842502087;
277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
278 _hashStateW = 273326509;
279
280 _OnTrap = 0;
281 _schedctl = NULL;
282 _Stalled = 0;
283 _TypeTag = 0x2BAD;
284
285 // Many of the following fields are effectively final - immutable
286 // Note that nascent threads can't use the Native Monitor-Mutex
287 // construct until the _MutexEvent is initialized ...
288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
289 // we might instead use a stack of ParkEvents that we could provision on-demand.
290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
291 // and ::Release()
292 _ParkEvent = ParkEvent::Allocate(this);
293 _SleepEvent = ParkEvent::Allocate(this);
294 _MutexEvent = ParkEvent::Allocate(this);
295 _MuxEvent = ParkEvent::Allocate(this);
296
297 #ifdef CHECK_UNHANDLED_OOPS
298 if (CheckUnhandledOops) {
299 _unhandled_oops = new UnhandledOops(this);
300 }
301 #endif // CHECK_UNHANDLED_OOPS
302 #ifdef ASSERT
303 if (UseBiasedLocking) {
304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
307 "bug in forced alignment of thread objects");
308 }
309 #endif // ASSERT
310 }
311
312 void Thread::initialize_thread_current() {
313 #ifndef USE_LIBRARY_BASED_TLS_ONLY
314 assert(_thr_current == NULL, "Thread::current already initialized");
315 _thr_current = this;
316 #endif
317 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
318 ThreadLocalStorage::set_thread(this);
319 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
320 }
321
322 void Thread::clear_thread_current() {
323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
324 #ifndef USE_LIBRARY_BASED_TLS_ONLY
325 _thr_current = NULL;
326 #endif
327 ThreadLocalStorage::set_thread(NULL);
328 }
329
330 void Thread::record_stack_base_and_size() {
331 set_stack_base(os::current_stack_base());
332 set_stack_size(os::current_stack_size());
333 // CR 7190089: on Solaris, primordial thread's stack is adjusted
334 // in initialize_thread(). Without the adjustment, stack size is
335 // incorrect if stack is set to unlimited (ulimit -s unlimited).
336 // So far, only Solaris has real implementation of initialize_thread().
337 //
338 // set up any platform-specific state.
339 os::initialize_thread(this);
340
341 // Set stack limits after thread is initialized.
342 if (is_Java_thread()) {
343 ((JavaThread*) this)->set_stack_overflow_limit();
344 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
345 }
346 #if INCLUDE_NMT
347 // record thread's native stack, stack grows downward
348 MemTracker::record_thread_stack(stack_end(), stack_size());
349 #endif // INCLUDE_NMT
350 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
351 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
352 os::current_thread_id(), p2i(stack_base() - stack_size()),
353 p2i(stack_base()), stack_size()/1024);
354 }
355
356
357 Thread::~Thread() {
358 EVENT_THREAD_DESTRUCT(this);
359
360 // stack_base can be NULL if the thread is never started or exited before
361 // record_stack_base_and_size called. Although, we would like to ensure
362 // that all started threads do call record_stack_base_and_size(), there is
363 // not proper way to enforce that.
364 #if INCLUDE_NMT
365 if (_stack_base != NULL) {
366 MemTracker::release_thread_stack(stack_end(), stack_size());
367 #ifdef ASSERT
368 set_stack_base(NULL);
369 #endif
370 }
371 #endif // INCLUDE_NMT
372
373 // deallocate data structures
374 delete resource_area();
375 // since the handle marks are using the handle area, we have to deallocated the root
376 // handle mark before deallocating the thread's handle area,
377 assert(last_handle_mark() != NULL, "check we have an element");
378 delete last_handle_mark();
379 assert(last_handle_mark() == NULL, "check we have reached the end");
380
381 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
382 // We NULL out the fields for good hygiene.
383 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
384 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
385 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
386 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
387
388 delete handle_area();
389 delete metadata_handles();
390
391 // SR_handler uses this as a termination indicator -
392 // needs to happen before os::free_thread()
393 delete _SR_lock;
394 _SR_lock = NULL;
395
396 // osthread() can be NULL, if creation of thread failed.
397 if (osthread() != NULL) os::free_thread(osthread());
398
399 // clear Thread::current if thread is deleting itself.
400 // Needed to ensure JNI correctly detects non-attached threads.
401 if (this == Thread::current()) {
402 clear_thread_current();
403 }
404
405 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
406 }
407
408 // NOTE: dummy function for assertion purpose.
409 void Thread::run() {
410 ShouldNotReachHere();
411 }
412
413 #ifdef ASSERT
414 // A JavaThread is considered "dangling" if it is not the current
415 // thread, has been added the Threads list, the system is not at a
416 // safepoint and the Thread is not "protected".
417 //
418 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
419 assert(!thread->is_Java_thread() || Thread::current() == thread ||
420 !((JavaThread *) thread)->on_thread_list() ||
421 SafepointSynchronize::is_at_safepoint() ||
422 Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
423 "possibility of dangling Thread pointer");
424 }
425 #endif
426
427 ThreadPriority Thread::get_priority(const Thread* const thread) {
428 ThreadPriority priority;
429 // Can return an error!
430 (void)os::get_priority(thread, priority);
431 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
432 return priority;
433 }
434
435 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
436 debug_only(check_for_dangling_thread_pointer(thread);)
437 // Can return an error!
438 (void)os::set_priority(thread, priority);
439 }
440
441
442 void Thread::start(Thread* thread) {
443 // Start is different from resume in that its safety is guaranteed by context or
444 // being called from a Java method synchronized on the Thread object.
445 if (!DisableStartThread) {
446 if (thread->is_Java_thread()) {
447 // Initialize the thread state to RUNNABLE before starting this thread.
448 // Can not set it after the thread started because we do not know the
449 // exact thread state at that time. It could be in MONITOR_WAIT or
450 // in SLEEPING or some other state.
451 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
452 java_lang_Thread::RUNNABLE);
453 }
454 os::start_thread(thread);
455 }
456 }
457
458 // Enqueue a VM_Operation to do the job for us - sometime later
459 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
460 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
461 VMThread::execute(vm_stop);
462 }
463
464
465 // Check if an external suspend request has completed (or has been
466 // cancelled). Returns true if the thread is externally suspended and
467 // false otherwise.
468 //
469 // The bits parameter returns information about the code path through
470 // the routine. Useful for debugging:
471 //
472 // set in is_ext_suspend_completed():
473 // 0x00000001 - routine was entered
474 // 0x00000010 - routine return false at end
475 // 0x00000100 - thread exited (return false)
476 // 0x00000200 - suspend request cancelled (return false)
477 // 0x00000400 - thread suspended (return true)
478 // 0x00001000 - thread is in a suspend equivalent state (return true)
479 // 0x00002000 - thread is native and walkable (return true)
480 // 0x00004000 - thread is native_trans and walkable (needed retry)
481 //
482 // set in wait_for_ext_suspend_completion():
483 // 0x00010000 - routine was entered
484 // 0x00020000 - suspend request cancelled before loop (return false)
485 // 0x00040000 - thread suspended before loop (return true)
486 // 0x00080000 - suspend request cancelled in loop (return false)
487 // 0x00100000 - thread suspended in loop (return true)
488 // 0x00200000 - suspend not completed during retry loop (return false)
489
490 // Helper class for tracing suspend wait debug bits.
491 //
492 // 0x00000100 indicates that the target thread exited before it could
493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
494 // 0x00080000 each indicate a cancelled suspend request so they don't
495 // count as wait failures either.
496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
497
498 class TraceSuspendDebugBits : public StackObj {
499 private:
500 JavaThread * jt;
501 bool is_wait;
502 bool called_by_wait; // meaningful when !is_wait
503 uint32_t * bits;
504
505 public:
506 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
507 uint32_t *_bits) {
508 jt = _jt;
509 is_wait = _is_wait;
510 called_by_wait = _called_by_wait;
511 bits = _bits;
512 }
513
514 ~TraceSuspendDebugBits() {
515 if (!is_wait) {
516 #if 1
517 // By default, don't trace bits for is_ext_suspend_completed() calls.
518 // That trace is very chatty.
519 return;
520 #else
521 if (!called_by_wait) {
522 // If tracing for is_ext_suspend_completed() is enabled, then only
523 // trace calls to it from wait_for_ext_suspend_completion()
524 return;
525 }
526 #endif
527 }
528
529 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
530 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
531 MutexLocker ml(Threads_lock); // needed for get_thread_name()
532 ResourceMark rm;
533
534 tty->print_cr(
535 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
536 jt->get_thread_name(), *bits);
537
538 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
539 }
540 }
541 }
542 };
543 #undef DEBUG_FALSE_BITS
544
545
546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
547 uint32_t *bits) {
548 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
549
550 bool did_trans_retry = false; // only do thread_in_native_trans retry once
551 bool do_trans_retry; // flag to force the retry
552
553 *bits |= 0x00000001;
554
555 do {
556 do_trans_retry = false;
557
558 if (is_exiting()) {
559 // Thread is in the process of exiting. This is always checked
560 // first to reduce the risk of dereferencing a freed JavaThread.
561 *bits |= 0x00000100;
562 return false;
563 }
564
565 if (!is_external_suspend()) {
566 // Suspend request is cancelled. This is always checked before
567 // is_ext_suspended() to reduce the risk of a rogue resume
568 // confusing the thread that made the suspend request.
569 *bits |= 0x00000200;
570 return false;
571 }
572
573 if (is_ext_suspended()) {
574 // thread is suspended
575 *bits |= 0x00000400;
576 return true;
577 }
578
579 // Now that we no longer do hard suspends of threads running
580 // native code, the target thread can be changing thread state
581 // while we are in this routine:
582 //
583 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
584 //
585 // We save a copy of the thread state as observed at this moment
586 // and make our decision about suspend completeness based on the
587 // copy. This closes the race where the thread state is seen as
588 // _thread_in_native_trans in the if-thread_blocked check, but is
589 // seen as _thread_blocked in if-thread_in_native_trans check.
590 JavaThreadState save_state = thread_state();
591
592 if (save_state == _thread_blocked && is_suspend_equivalent()) {
593 // If the thread's state is _thread_blocked and this blocking
594 // condition is known to be equivalent to a suspend, then we can
595 // consider the thread to be externally suspended. This means that
596 // the code that sets _thread_blocked has been modified to do
597 // self-suspension if the blocking condition releases. We also
598 // used to check for CONDVAR_WAIT here, but that is now covered by
599 // the _thread_blocked with self-suspension check.
600 //
601 // Return true since we wouldn't be here unless there was still an
602 // external suspend request.
603 *bits |= 0x00001000;
604 return true;
605 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
606 // Threads running native code will self-suspend on native==>VM/Java
607 // transitions. If its stack is walkable (should always be the case
608 // unless this function is called before the actual java_suspend()
609 // call), then the wait is done.
610 *bits |= 0x00002000;
611 return true;
612 } else if (!called_by_wait && !did_trans_retry &&
613 save_state == _thread_in_native_trans &&
614 frame_anchor()->walkable()) {
615 // The thread is transitioning from thread_in_native to another
616 // thread state. check_safepoint_and_suspend_for_native_trans()
617 // will force the thread to self-suspend. If it hasn't gotten
618 // there yet we may have caught the thread in-between the native
619 // code check above and the self-suspend. Lucky us. If we were
620 // called by wait_for_ext_suspend_completion(), then it
621 // will be doing the retries so we don't have to.
622 //
623 // Since we use the saved thread state in the if-statement above,
624 // there is a chance that the thread has already transitioned to
625 // _thread_blocked by the time we get here. In that case, we will
626 // make a single unnecessary pass through the logic below. This
627 // doesn't hurt anything since we still do the trans retry.
628
629 *bits |= 0x00004000;
630
631 // Once the thread leaves thread_in_native_trans for another
632 // thread state, we break out of this retry loop. We shouldn't
633 // need this flag to prevent us from getting back here, but
634 // sometimes paranoia is good.
635 did_trans_retry = true;
636
637 // We wait for the thread to transition to a more usable state.
638 for (int i = 1; i <= SuspendRetryCount; i++) {
639 // We used to do an "os::yield_all(i)" call here with the intention
640 // that yielding would increase on each retry. However, the parameter
641 // is ignored on Linux which means the yield didn't scale up. Waiting
642 // on the SR_lock below provides a much more predictable scale up for
643 // the delay. It also provides a simple/direct point to check for any
644 // safepoint requests from the VMThread
645
646 // temporarily drops SR_lock while doing wait with safepoint check
647 // (if we're a JavaThread - the WatcherThread can also call this)
648 // and increase delay with each retry
649 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
650
651 // check the actual thread state instead of what we saved above
652 if (thread_state() != _thread_in_native_trans) {
653 // the thread has transitioned to another thread state so
654 // try all the checks (except this one) one more time.
655 do_trans_retry = true;
656 break;
657 }
658 } // end retry loop
659
660
661 }
662 } while (do_trans_retry);
663
664 *bits |= 0x00000010;
665 return false;
666 }
667
668 // Wait for an external suspend request to complete (or be cancelled).
669 // Returns true if the thread is externally suspended and false otherwise.
670 //
671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
672 uint32_t *bits) {
673 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
674 false /* !called_by_wait */, bits);
675
676 // local flag copies to minimize SR_lock hold time
677 bool is_suspended;
678 bool pending;
679 uint32_t reset_bits;
680
681 // set a marker so is_ext_suspend_completed() knows we are the caller
682 *bits |= 0x00010000;
683
684 // We use reset_bits to reinitialize the bits value at the top of
685 // each retry loop. This allows the caller to make use of any
686 // unused bits for their own marking purposes.
687 reset_bits = *bits;
688
689 {
690 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
691 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
692 delay, bits);
693 pending = is_external_suspend();
694 }
695 // must release SR_lock to allow suspension to complete
696
697 if (!pending) {
698 // A cancelled suspend request is the only false return from
699 // is_ext_suspend_completed() that keeps us from entering the
700 // retry loop.
701 *bits |= 0x00020000;
702 return false;
703 }
704
705 if (is_suspended) {
706 *bits |= 0x00040000;
707 return true;
708 }
709
710 for (int i = 1; i <= retries; i++) {
711 *bits = reset_bits; // reinit to only track last retry
712
713 // We used to do an "os::yield_all(i)" call here with the intention
714 // that yielding would increase on each retry. However, the parameter
715 // is ignored on Linux which means the yield didn't scale up. Waiting
716 // on the SR_lock below provides a much more predictable scale up for
717 // the delay. It also provides a simple/direct point to check for any
718 // safepoint requests from the VMThread
719
720 {
721 MutexLocker ml(SR_lock());
722 // wait with safepoint check (if we're a JavaThread - the WatcherThread
723 // can also call this) and increase delay with each retry
724 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
725
726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
727 delay, bits);
728
729 // It is possible for the external suspend request to be cancelled
730 // (by a resume) before the actual suspend operation is completed.
731 // Refresh our local copy to see if we still need to wait.
732 pending = is_external_suspend();
733 }
734
735 if (!pending) {
736 // A cancelled suspend request is the only false return from
737 // is_ext_suspend_completed() that keeps us from staying in the
738 // retry loop.
739 *bits |= 0x00080000;
740 return false;
741 }
742
743 if (is_suspended) {
744 *bits |= 0x00100000;
745 return true;
746 }
747 } // end retry loop
748
749 // thread did not suspend after all our retries
750 *bits |= 0x00200000;
751 return false;
752 }
753
754 // Called from API entry points which perform stack walking. If the
755 // associated JavaThread is the current thread, then wait_for_suspend
756 // is not used. Otherwise, it determines if we should wait for the
757 // "other" thread to complete external suspension. (NOTE: in future
758 // releases the suspension mechanism should be reimplemented so this
759 // is not necessary.)
760 //
761 bool
762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
763 if (this != JavaThread::current()) {
764 // "other" threads require special handling.
765 if (wait_for_suspend) {
766 // We are allowed to wait for the external suspend to complete
767 // so give the other thread a chance to get suspended.
768 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
769 SuspendRetryDelay, bits)) {
770 // Didn't make it so let the caller know.
771 return false;
772 }
773 }
774 // We aren't allowed to wait for the external suspend to complete
775 // so if the other thread isn't externally suspended we need to
776 // let the caller know.
777 else if (!is_ext_suspend_completed_with_lock(bits)) {
778 return false;
779 }
780 }
781
782 return true;
783 }
784
785 #ifndef PRODUCT
786 void JavaThread::record_jump(address target, address instr, const char* file,
787 int line) {
788
789 // This should not need to be atomic as the only way for simultaneous
790 // updates is via interrupts. Even then this should be rare or non-existent
791 // and we don't care that much anyway.
792
793 int index = _jmp_ring_index;
794 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
795 _jmp_ring[index]._target = (intptr_t) target;
796 _jmp_ring[index]._instruction = (intptr_t) instr;
797 _jmp_ring[index]._file = file;
798 _jmp_ring[index]._line = line;
799 }
800 #endif // PRODUCT
801
802 void Thread::interrupt(Thread* thread) {
803 debug_only(check_for_dangling_thread_pointer(thread);)
804 os::interrupt(thread);
805 }
806
807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
808 debug_only(check_for_dangling_thread_pointer(thread);)
809 // Note: If clear_interrupted==false, this simply fetches and
810 // returns the value of the field osthread()->interrupted().
811 return os::is_interrupted(thread, clear_interrupted);
812 }
813
814
815 // GC Support
816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
817 int thread_parity = _oops_do_parity;
818 if (thread_parity != strong_roots_parity) {
819 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
820 if (res == thread_parity) {
821 return true;
822 } else {
823 guarantee(res == strong_roots_parity, "Or else what?");
824 return false;
825 }
826 }
827 return false;
828 }
829
830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
831 active_handles()->oops_do(f);
832 // Do oop for ThreadShadow
833 f->do_oop((oop*)&_pending_exception);
834 handle_area()->oops_do(f);
835
836 if (MonitorInUseLists) {
837 // When using thread local monitor lists, we scan them here,
838 // and the remaining global monitors in ObjectSynchronizer::oops_do().
839 ObjectSynchronizer::thread_local_used_oops_do(this, f);
840 }
841 }
842
843 void Thread::metadata_handles_do(void f(Metadata*)) {
844 // Only walk the Handles in Thread.
845 if (metadata_handles() != NULL) {
846 for (int i = 0; i< metadata_handles()->length(); i++) {
847 f(metadata_handles()->at(i));
848 }
849 }
850 }
851
852 void Thread::print_on(outputStream* st) const {
853 // get_priority assumes osthread initialized
854 if (osthread() != NULL) {
855 int os_prio;
856 if (os::get_native_priority(this, &os_prio) == OS_OK) {
857 st->print("os_prio=%d ", os_prio);
858 }
859 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
860 ext().print_on(st);
861 osthread()->print_on(st);
862 }
863 if (_threads_hazard_ptr != NULL) {
864 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
865 }
866 if (_nested_threads_hazard_ptr != NULL) {
867 print_nested_threads_hazard_ptrs_on(st);
868 }
869 st->print(" ");
870 debug_only(if (WizardMode) print_owned_locks_on(st);)
871 }
872
873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
874 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
875
876 if (EnableThreadSMRStatistics) {
877 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
878 }
879 st->print(", _nested_threads_hazard_ptrs=");
880 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
881 node = node->next()) {
882 if (node != _nested_threads_hazard_ptr) {
883 // First node does not need a comma-space separator.
884 st->print(", ");
885 }
886 st->print(INTPTR_FORMAT, p2i(node->t_list()));
887 }
888 }
889
890 // Thread::print_on_error() is called by fatal error handler. Don't use
891 // any lock or allocate memory.
892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
893 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
894
895 if (is_VM_thread()) { st->print("VMThread"); }
896 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
897 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
898 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
899 else { st->print("Thread"); }
900
901 if (is_Named_thread()) {
902 st->print(" \"%s\"", name());
903 }
904
905 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
906 p2i(stack_end()), p2i(stack_base()));
907
908 if (osthread()) {
909 st->print(" [id=%d]", osthread()->thread_id());
910 }
911
912 if (_threads_hazard_ptr != NULL) {
913 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
914 }
915 if (_nested_threads_hazard_ptr != NULL) {
916 print_nested_threads_hazard_ptrs_on(st);
917 }
918 }
919
920 void Thread::print_value_on(outputStream* st) const {
921 if (is_Named_thread()) {
922 st->print(" \"%s\" ", name());
923 }
924 st->print(INTPTR_FORMAT, p2i(this)); // print address
925 }
926
927 #ifdef ASSERT
928 void Thread::print_owned_locks_on(outputStream* st) const {
929 Monitor *cur = _owned_locks;
930 if (cur == NULL) {
931 st->print(" (no locks) ");
932 } else {
933 st->print_cr(" Locks owned:");
934 while (cur) {
935 cur->print_on(st);
936 cur = cur->next();
937 }
938 }
939 }
940
941 static int ref_use_count = 0;
942
943 bool Thread::owns_locks_but_compiled_lock() const {
944 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
945 if (cur != Compile_lock) return true;
946 }
947 return false;
948 }
949
950
951 #endif
952
953 #ifndef PRODUCT
954
955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
957 // no threads which allow_vm_block's are held
958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
959 // Check if current thread is allowed to block at a safepoint
960 if (!(_allow_safepoint_count == 0)) {
961 fatal("Possible safepoint reached by thread that does not allow it");
962 }
963 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
964 fatal("LEAF method calling lock?");
965 }
966
967 #ifdef ASSERT
968 if (potential_vm_operation && is_Java_thread()
969 && !Universe::is_bootstrapping()) {
970 // Make sure we do not hold any locks that the VM thread also uses.
971 // This could potentially lead to deadlocks
972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
973 // Threads_lock is special, since the safepoint synchronization will not start before this is
974 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
975 // since it is used to transfer control between JavaThreads and the VMThread
976 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
977 if ((cur->allow_vm_block() &&
978 cur != Threads_lock &&
979 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
980 cur != VMOperationRequest_lock &&
981 cur != VMOperationQueue_lock) ||
982 cur->rank() == Mutex::special) {
983 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
984 }
985 }
986 }
987
988 if (GCALotAtAllSafepoints) {
989 // We could enter a safepoint here and thus have a gc
990 InterfaceSupport::check_gc_alot();
991 }
992 #endif
993 }
994 #endif
995
996 bool Thread::is_in_stack(address adr) const {
997 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
998 address end = os::current_stack_pointer();
999 // Allow non Java threads to call this without stack_base
1000 if (_stack_base == NULL) return true;
1001 if (stack_base() >= adr && adr >= end) return true;
1002
1003 return false;
1004 }
1005
1006 bool Thread::is_in_usable_stack(address adr) const {
1007 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1008 size_t usable_stack_size = _stack_size - stack_guard_size;
1009
1010 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1011 }
1012
1013
1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1016 // used for compilation in the future. If that change is made, the need for these methods
1017 // should be revisited, and they should be removed if possible.
1018
1019 bool Thread::is_lock_owned(address adr) const {
1020 return on_local_stack(adr);
1021 }
1022
1023 bool Thread::set_as_starting_thread() {
1024 // NOTE: this must be called inside the main thread.
1025 return os::create_main_thread((JavaThread*)this);
1026 }
1027
1028 static void initialize_class(Symbol* class_name, TRAPS) {
1029 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1030 InstanceKlass::cast(klass)->initialize(CHECK);
1031 }
1032
1033
1034 // Creates the initial ThreadGroup
1035 static Handle create_initial_thread_group(TRAPS) {
1036 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1037 InstanceKlass* ik = InstanceKlass::cast(k);
1038
1039 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1040 {
1041 JavaValue result(T_VOID);
1042 JavaCalls::call_special(&result,
1043 system_instance,
1044 ik,
1045 vmSymbols::object_initializer_name(),
1046 vmSymbols::void_method_signature(),
1047 CHECK_NH);
1048 }
1049 Universe::set_system_thread_group(system_instance());
1050
1051 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1052 {
1053 JavaValue result(T_VOID);
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 JavaCalls::call_special(&result,
1056 main_instance,
1057 ik,
1058 vmSymbols::object_initializer_name(),
1059 vmSymbols::threadgroup_string_void_signature(),
1060 system_instance,
1061 string,
1062 CHECK_NH);
1063 }
1064 return main_instance;
1065 }
1066
1067 // Creates the initial Thread
1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1069 TRAPS) {
1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1071 InstanceKlass* ik = InstanceKlass::cast(k);
1072 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1073
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093
1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1095 static const char* get_java_runtime_name(TRAPS) {
1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1098 fieldDescriptor fd;
1099 bool found = k != NULL &&
1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1101 vmSymbols::string_signature(), &fd);
1102 if (found) {
1103 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1104 if (name_oop == NULL) {
1105 return NULL;
1106 }
1107 const char* name = java_lang_String::as_utf8_string(name_oop,
1108 java_runtime_name,
1109 sizeof(java_runtime_name));
1110 return name;
1111 } else {
1112 return NULL;
1113 }
1114 }
1115
1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1117 static const char* get_java_runtime_version(TRAPS) {
1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1120 fieldDescriptor fd;
1121 bool found = k != NULL &&
1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1123 vmSymbols::string_signature(), &fd);
1124 if (found) {
1125 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1126 if (name_oop == NULL) {
1127 return NULL;
1128 }
1129 const char* name = java_lang_String::as_utf8_string(name_oop,
1130 java_runtime_version,
1131 sizeof(java_runtime_version));
1132 return name;
1133 } else {
1134 return NULL;
1135 }
1136 }
1137
1138 // General purpose hook into Java code, run once when the VM is initialized.
1139 // The Java library method itself may be changed independently from the VM.
1140 static void call_postVMInitHook(TRAPS) {
1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1142 if (klass != NULL) {
1143 JavaValue result(T_VOID);
1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1145 vmSymbols::void_method_signature(),
1146 CHECK);
1147 }
1148 }
1149
1150 static void reset_vm_info_property(TRAPS) {
1151 // the vm info string
1152 ResourceMark rm(THREAD);
1153 const char *vm_info = VM_Version::vm_info_string();
1154
1155 // java.lang.System class
1156 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1157
1158 // setProperty arguments
1159 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1160 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1161
1162 // return value
1163 JavaValue r(T_OBJECT);
1164
1165 // public static String setProperty(String key, String value);
1166 JavaCalls::call_static(&r,
1167 klass,
1168 vmSymbols::setProperty_name(),
1169 vmSymbols::string_string_string_signature(),
1170 key_str,
1171 value_str,
1172 CHECK);
1173 }
1174
1175
1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1177 bool daemon, TRAPS) {
1178 assert(thread_group.not_null(), "thread group should be specified");
1179 assert(threadObj() == NULL, "should only create Java thread object once");
1180
1181 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1182 InstanceKlass* ik = InstanceKlass::cast(k);
1183 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1184
1185 java_lang_Thread::set_thread(thread_oop(), this);
1186 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1187 set_threadObj(thread_oop());
1188
1189 JavaValue result(T_VOID);
1190 if (thread_name != NULL) {
1191 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1192 // Thread gets assigned specified name and null target
1193 JavaCalls::call_special(&result,
1194 thread_oop,
1195 ik,
1196 vmSymbols::object_initializer_name(),
1197 vmSymbols::threadgroup_string_void_signature(),
1198 thread_group, // Argument 1
1199 name, // Argument 2
1200 THREAD);
1201 } else {
1202 // Thread gets assigned name "Thread-nnn" and null target
1203 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1204 JavaCalls::call_special(&result,
1205 thread_oop,
1206 ik,
1207 vmSymbols::object_initializer_name(),
1208 vmSymbols::threadgroup_runnable_void_signature(),
1209 thread_group, // Argument 1
1210 Handle(), // Argument 2
1211 THREAD);
1212 }
1213
1214
1215 if (daemon) {
1216 java_lang_Thread::set_daemon(thread_oop());
1217 }
1218
1219 if (HAS_PENDING_EXCEPTION) {
1220 return;
1221 }
1222
1223 Klass* group = SystemDictionary::ThreadGroup_klass();
1224 Handle threadObj(THREAD, this->threadObj());
1225
1226 JavaCalls::call_special(&result,
1227 thread_group,
1228 group,
1229 vmSymbols::add_method_name(),
1230 vmSymbols::thread_void_signature(),
1231 threadObj, // Arg 1
1232 THREAD);
1233 }
1234
1235 // NamedThread -- non-JavaThread subclasses with multiple
1236 // uniquely named instances should derive from this.
1237 NamedThread::NamedThread() : Thread() {
1238 _name = NULL;
1239 _processed_thread = NULL;
1240 _gc_id = GCId::undefined();
1241 }
1242
1243 NamedThread::~NamedThread() {
1244 if (_name != NULL) {
1245 FREE_C_HEAP_ARRAY(char, _name);
1246 _name = NULL;
1247 }
1248 }
1249
1250 void NamedThread::set_name(const char* format, ...) {
1251 guarantee(_name == NULL, "Only get to set name once.");
1252 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1253 guarantee(_name != NULL, "alloc failure");
1254 va_list ap;
1255 va_start(ap, format);
1256 jio_vsnprintf(_name, max_name_len, format, ap);
1257 va_end(ap);
1258 }
1259
1260 void NamedThread::initialize_named_thread() {
1261 set_native_thread_name(name());
1262 }
1263
1264 void NamedThread::print_on(outputStream* st) const {
1265 st->print("\"%s\" ", name());
1266 Thread::print_on(st);
1267 st->cr();
1268 }
1269
1270
1271 // ======= WatcherThread ========
1272
1273 // The watcher thread exists to simulate timer interrupts. It should
1274 // be replaced by an abstraction over whatever native support for
1275 // timer interrupts exists on the platform.
1276
1277 WatcherThread* WatcherThread::_watcher_thread = NULL;
1278 bool WatcherThread::_startable = false;
1279 volatile bool WatcherThread::_should_terminate = false;
1280
1281 WatcherThread::WatcherThread() : Thread() {
1282 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1283 if (os::create_thread(this, os::watcher_thread)) {
1284 _watcher_thread = this;
1285
1286 // Set the watcher thread to the highest OS priority which should not be
1287 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1288 // is created. The only normal thread using this priority is the reference
1289 // handler thread, which runs for very short intervals only.
1290 // If the VMThread's priority is not lower than the WatcherThread profiling
1291 // will be inaccurate.
1292 os::set_priority(this, MaxPriority);
1293 if (!DisableStartThread) {
1294 os::start_thread(this);
1295 }
1296 }
1297 }
1298
1299 int WatcherThread::sleep() const {
1300 // The WatcherThread does not participate in the safepoint protocol
1301 // for the PeriodicTask_lock because it is not a JavaThread.
1302 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1303
1304 if (_should_terminate) {
1305 // check for termination before we do any housekeeping or wait
1306 return 0; // we did not sleep.
1307 }
1308
1309 // remaining will be zero if there are no tasks,
1310 // causing the WatcherThread to sleep until a task is
1311 // enrolled
1312 int remaining = PeriodicTask::time_to_wait();
1313 int time_slept = 0;
1314
1315 // we expect this to timeout - we only ever get unparked when
1316 // we should terminate or when a new task has been enrolled
1317 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1318
1319 jlong time_before_loop = os::javaTimeNanos();
1320
1321 while (true) {
1322 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1323 remaining);
1324 jlong now = os::javaTimeNanos();
1325
1326 if (remaining == 0) {
1327 // if we didn't have any tasks we could have waited for a long time
1328 // consider the time_slept zero and reset time_before_loop
1329 time_slept = 0;
1330 time_before_loop = now;
1331 } else {
1332 // need to recalculate since we might have new tasks in _tasks
1333 time_slept = (int) ((now - time_before_loop) / 1000000);
1334 }
1335
1336 // Change to task list or spurious wakeup of some kind
1337 if (timedout || _should_terminate) {
1338 break;
1339 }
1340
1341 remaining = PeriodicTask::time_to_wait();
1342 if (remaining == 0) {
1343 // Last task was just disenrolled so loop around and wait until
1344 // another task gets enrolled
1345 continue;
1346 }
1347
1348 remaining -= time_slept;
1349 if (remaining <= 0) {
1350 break;
1351 }
1352 }
1353
1354 return time_slept;
1355 }
1356
1357 void WatcherThread::run() {
1358 assert(this == watcher_thread(), "just checking");
1359
1360 this->record_stack_base_and_size();
1361 this->set_native_thread_name(this->name());
1362 this->set_active_handles(JNIHandleBlock::allocate_block());
1363 while (true) {
1364 assert(watcher_thread() == Thread::current(), "thread consistency check");
1365 assert(watcher_thread() == this, "thread consistency check");
1366
1367 // Calculate how long it'll be until the next PeriodicTask work
1368 // should be done, and sleep that amount of time.
1369 int time_waited = sleep();
1370
1371 if (VMError::is_error_reported()) {
1372 // A fatal error has happened, the error handler(VMError::report_and_die)
1373 // should abort JVM after creating an error log file. However in some
1374 // rare cases, the error handler itself might deadlock. Here periodically
1375 // check for error reporting timeouts, and if it happens, just proceed to
1376 // abort the VM.
1377
1378 // This code is in WatcherThread because WatcherThread wakes up
1379 // periodically so the fatal error handler doesn't need to do anything;
1380 // also because the WatcherThread is less likely to crash than other
1381 // threads.
1382
1383 for (;;) {
1384 // Note: we use naked sleep in this loop because we want to avoid using
1385 // any kind of VM infrastructure which may be broken at this point.
1386 if (VMError::check_timeout()) {
1387 // We hit error reporting timeout. Error reporting was interrupted and
1388 // will be wrapping things up now (closing files etc). Give it some more
1389 // time, then quit the VM.
1390 os::naked_short_sleep(200);
1391 // Print a message to stderr.
1392 fdStream err(defaultStream::output_fd());
1393 err.print_raw_cr("# [ timer expired, abort... ]");
1394 // skip atexit/vm_exit/vm_abort hooks
1395 os::die();
1396 }
1397
1398 // Wait a second, then recheck for timeout.
1399 os::naked_short_sleep(999);
1400 }
1401 }
1402
1403 if (_should_terminate) {
1404 // check for termination before posting the next tick
1405 break;
1406 }
1407
1408 PeriodicTask::real_time_tick(time_waited);
1409 }
1410
1411 // Signal that it is terminated
1412 {
1413 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1414 _watcher_thread = NULL;
1415 Terminator_lock->notify();
1416 }
1417 }
1418
1419 void WatcherThread::start() {
1420 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1421
1422 if (watcher_thread() == NULL && _startable) {
1423 _should_terminate = false;
1424 // Create the single instance of WatcherThread
1425 new WatcherThread();
1426 }
1427 }
1428
1429 void WatcherThread::make_startable() {
1430 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1431 _startable = true;
1432 }
1433
1434 void WatcherThread::stop() {
1435 {
1436 // Follow normal safepoint aware lock enter protocol since the
1437 // WatcherThread is stopped by another JavaThread.
1438 MutexLocker ml(PeriodicTask_lock);
1439 _should_terminate = true;
1440
1441 WatcherThread* watcher = watcher_thread();
1442 if (watcher != NULL) {
1443 // unpark the WatcherThread so it can see that it should terminate
1444 watcher->unpark();
1445 }
1446 }
1447
1448 MutexLocker mu(Terminator_lock);
1449
1450 while (watcher_thread() != NULL) {
1451 // This wait should make safepoint checks, wait without a timeout,
1452 // and wait as a suspend-equivalent condition.
1453 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1454 Mutex::_as_suspend_equivalent_flag);
1455 }
1456 }
1457
1458 void WatcherThread::unpark() {
1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1460 PeriodicTask_lock->notify();
1461 }
1462
1463 void WatcherThread::print_on(outputStream* st) const {
1464 st->print("\"%s\" ", name());
1465 Thread::print_on(st);
1466 st->cr();
1467 }
1468
1469 // ======= JavaThread ========
1470
1471 #if INCLUDE_JVMCI
1472
1473 jlong* JavaThread::_jvmci_old_thread_counters;
1474
1475 bool jvmci_counters_include(JavaThread* thread) {
1476 oop threadObj = thread->threadObj();
1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1478 }
1479
1480 void JavaThread::collect_counters(typeArrayOop array) {
1481 if (JVMCICounterSize > 0) {
1482 // dcubed - Looks like the Threads_lock is for stable access
1483 // to _jvmci_old_thread_counters and _jvmci_counters.
1484 MutexLocker tl(Threads_lock);
1485 JavaThreadIteratorWithHandle jtiwh;
1486 for (int i = 0; i < array->length(); i++) {
1487 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1488 }
1489 for (; JavaThread *tp = jtiwh.next(); ) {
1490 if (jvmci_counters_include(tp)) {
1491 for (int i = 0; i < array->length(); i++) {
1492 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1493 }
1494 }
1495 }
1496 }
1497 }
1498
1499 #endif // INCLUDE_JVMCI
1500
1501 // A JavaThread is a normal Java thread
1502
1503 void JavaThread::initialize() {
1504 // Initialize fields
1505
1506 set_saved_exception_pc(NULL);
1507 set_threadObj(NULL);
1508 _anchor.clear();
1509 set_entry_point(NULL);
1510 set_jni_functions(jni_functions());
1511 set_callee_target(NULL);
1512 set_vm_result(NULL);
1513 set_vm_result_2(NULL);
1514 set_vframe_array_head(NULL);
1515 set_vframe_array_last(NULL);
1516 set_deferred_locals(NULL);
1517 set_deopt_mark(NULL);
1518 set_deopt_compiled_method(NULL);
1519 clear_must_deopt_id();
1520 set_monitor_chunks(NULL);
1521 set_next(NULL);
1522 _on_thread_list = false;
1523 set_thread_state(_thread_new);
1524 _terminated = _not_terminated;
1525 _privileged_stack_top = NULL;
1526 _array_for_gc = NULL;
1527 _suspend_equivalent = false;
1528 _in_deopt_handler = 0;
1529 _doing_unsafe_access = false;
1530 _stack_guard_state = stack_guard_unused;
1531 #if INCLUDE_JVMCI
1532 _pending_monitorenter = false;
1533 _pending_deoptimization = -1;
1534 _pending_failed_speculation = NULL;
1535 _pending_transfer_to_interpreter = false;
1536 _adjusting_comp_level = false;
1537 _jvmci._alternate_call_target = NULL;
1538 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1539 if (JVMCICounterSize > 0) {
1540 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1541 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1542 } else {
1543 _jvmci_counters = NULL;
1544 }
1545 #endif // INCLUDE_JVMCI
1546 _reserved_stack_activation = NULL; // stack base not known yet
1547 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1548 _exception_pc = 0;
1549 _exception_handler_pc = 0;
1550 _is_method_handle_return = 0;
1551 _jvmti_thread_state= NULL;
1552 _should_post_on_exceptions_flag = JNI_FALSE;
1553 _jvmti_get_loaded_classes_closure = NULL;
1554 _interp_only_mode = 0;
1555 _special_runtime_exit_condition = _no_async_condition;
1556 _pending_async_exception = NULL;
1557 _thread_stat = NULL;
1558 _thread_stat = new ThreadStatistics();
1559 _blocked_on_compilation = false;
1560 _jni_active_critical = 0;
1561 _pending_jni_exception_check_fn = NULL;
1562 _do_not_unlock_if_synchronized = false;
1563 _cached_monitor_info = NULL;
1564 _parker = Parker::Allocate(this);
1565
1566 #ifndef PRODUCT
1567 _jmp_ring_index = 0;
1568 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1569 record_jump(NULL, NULL, NULL, 0);
1570 }
1571 #endif // PRODUCT
1572
1573 // Setup safepoint state info for this thread
1574 ThreadSafepointState::create(this);
1575
1576 debug_only(_java_call_counter = 0);
1577
1578 // JVMTI PopFrame support
1579 _popframe_condition = popframe_inactive;
1580 _popframe_preserved_args = NULL;
1581 _popframe_preserved_args_size = 0;
1582 _frames_to_pop_failed_realloc = 0;
1583
1584 if (SafepointMechanism::uses_thread_local_poll()) {
1585 SafepointMechanism::initialize_header(this);
1586 }
1587
1588 pd_initialize();
1589 }
1590
1591 #if INCLUDE_ALL_GCS
1592 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1593 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1594 #endif // INCLUDE_ALL_GCS
1595
1596 JavaThread::JavaThread(bool is_attaching_via_jni) :
1597 Thread()
1598 #if INCLUDE_ALL_GCS
1599 , _satb_mark_queue(&_satb_mark_queue_set),
1600 _dirty_card_queue(&_dirty_card_queue_set)
1601 #endif // INCLUDE_ALL_GCS
1602 {
1603 initialize();
1604 if (is_attaching_via_jni) {
1605 _jni_attach_state = _attaching_via_jni;
1606 } else {
1607 _jni_attach_state = _not_attaching_via_jni;
1608 }
1609 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1610 }
1611
1612 bool JavaThread::reguard_stack(address cur_sp) {
1613 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1614 && _stack_guard_state != stack_guard_reserved_disabled) {
1615 return true; // Stack already guarded or guard pages not needed.
1616 }
1617
1618 if (register_stack_overflow()) {
1619 // For those architectures which have separate register and
1620 // memory stacks, we must check the register stack to see if
1621 // it has overflowed.
1622 return false;
1623 }
1624
1625 // Java code never executes within the yellow zone: the latter is only
1626 // there to provoke an exception during stack banging. If java code
1627 // is executing there, either StackShadowPages should be larger, or
1628 // some exception code in c1, c2 or the interpreter isn't unwinding
1629 // when it should.
1630 guarantee(cur_sp > stack_reserved_zone_base(),
1631 "not enough space to reguard - increase StackShadowPages");
1632 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1633 enable_stack_yellow_reserved_zone();
1634 if (reserved_stack_activation() != stack_base()) {
1635 set_reserved_stack_activation(stack_base());
1636 }
1637 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1638 set_reserved_stack_activation(stack_base());
1639 enable_stack_reserved_zone();
1640 }
1641 return true;
1642 }
1643
1644 bool JavaThread::reguard_stack(void) {
1645 return reguard_stack(os::current_stack_pointer());
1646 }
1647
1648
1649 void JavaThread::block_if_vm_exited() {
1650 if (_terminated == _vm_exited) {
1651 // _vm_exited is set at safepoint, and Threads_lock is never released
1652 // we will block here forever
1653 Threads_lock->lock_without_safepoint_check();
1654 ShouldNotReachHere();
1655 }
1656 }
1657
1658
1659 // Remove this ifdef when C1 is ported to the compiler interface.
1660 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1661 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1662
1663 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1664 Thread()
1665 #if INCLUDE_ALL_GCS
1666 , _satb_mark_queue(&_satb_mark_queue_set),
1667 _dirty_card_queue(&_dirty_card_queue_set)
1668 #endif // INCLUDE_ALL_GCS
1669 {
1670 initialize();
1671 _jni_attach_state = _not_attaching_via_jni;
1672 set_entry_point(entry_point);
1673 // Create the native thread itself.
1674 // %note runtime_23
1675 os::ThreadType thr_type = os::java_thread;
1676 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1677 os::java_thread;
1678 os::create_thread(this, thr_type, stack_sz);
1679 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1680 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1681 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1682 // the exception consists of creating the exception object & initializing it, initialization
1683 // will leave the VM via a JavaCall and then all locks must be unlocked).
1684 //
1685 // The thread is still suspended when we reach here. Thread must be explicit started
1686 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1687 // by calling Threads:add. The reason why this is not done here, is because the thread
1688 // object must be fully initialized (take a look at JVM_Start)
1689 }
1690
1691 JavaThread::~JavaThread() {
1692
1693 // JSR166 -- return the parker to the free list
1694 Parker::Release(_parker);
1695 _parker = NULL;
1696
1697 // Free any remaining previous UnrollBlock
1698 vframeArray* old_array = vframe_array_last();
1699
1700 if (old_array != NULL) {
1701 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1702 old_array->set_unroll_block(NULL);
1703 delete old_info;
1704 delete old_array;
1705 }
1706
1707 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1708 if (deferred != NULL) {
1709 // This can only happen if thread is destroyed before deoptimization occurs.
1710 assert(deferred->length() != 0, "empty array!");
1711 do {
1712 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1713 deferred->remove_at(0);
1714 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1715 delete dlv;
1716 } while (deferred->length() != 0);
1717 delete deferred;
1718 }
1719
1720 // All Java related clean up happens in exit
1721 ThreadSafepointState::destroy(this);
1722 if (_thread_stat != NULL) delete _thread_stat;
1723
1724 #if INCLUDE_JVMCI
1725 if (JVMCICounterSize > 0) {
1726 if (jvmci_counters_include(this)) {
1727 for (int i = 0; i < JVMCICounterSize; i++) {
1728 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1729 }
1730 }
1731 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1732 }
1733 #endif // INCLUDE_JVMCI
1734 }
1735
1736
1737 // The first routine called by a new Java thread
1738 void JavaThread::run() {
1739 // initialize thread-local alloc buffer related fields
1740 this->initialize_tlab();
1741
1742 // used to test validity of stack trace backs
1743 this->record_base_of_stack_pointer();
1744
1745 // Record real stack base and size.
1746 this->record_stack_base_and_size();
1747
1748 this->create_stack_guard_pages();
1749
1750 this->cache_global_variables();
1751
1752 // Thread is now sufficient initialized to be handled by the safepoint code as being
1753 // in the VM. Change thread state from _thread_new to _thread_in_vm
1754 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1755
1756 assert(JavaThread::current() == this, "sanity check");
1757 assert(!Thread::current()->owns_locks(), "sanity check");
1758
1759 DTRACE_THREAD_PROBE(start, this);
1760
1761 // This operation might block. We call that after all safepoint checks for a new thread has
1762 // been completed.
1763 this->set_active_handles(JNIHandleBlock::allocate_block());
1764
1765 if (JvmtiExport::should_post_thread_life()) {
1766 JvmtiExport::post_thread_start(this);
1767 }
1768
1769 EventThreadStart event;
1770 if (event.should_commit()) {
1771 event.set_thread(THREAD_TRACE_ID(this));
1772 event.commit();
1773 }
1774
1775 // We call another function to do the rest so we are sure that the stack addresses used
1776 // from there will be lower than the stack base just computed
1777 thread_main_inner();
1778
1779 // Note, thread is no longer valid at this point!
1780 }
1781
1782
1783 void JavaThread::thread_main_inner() {
1784 assert(JavaThread::current() == this, "sanity check");
1785 assert(this->threadObj() != NULL, "just checking");
1786
1787 // Execute thread entry point unless this thread has a pending exception
1788 // or has been stopped before starting.
1789 // Note: Due to JVM_StopThread we can have pending exceptions already!
1790 if (!this->has_pending_exception() &&
1791 !java_lang_Thread::is_stillborn(this->threadObj())) {
1792 {
1793 ResourceMark rm(this);
1794 this->set_native_thread_name(this->get_thread_name());
1795 }
1796 HandleMark hm(this);
1797 this->entry_point()(this, this);
1798 }
1799
1800 DTRACE_THREAD_PROBE(stop, this);
1801
1802 this->exit(false);
1803 this->smr_delete();
1804 }
1805
1806
1807 static void ensure_join(JavaThread* thread) {
1808 // We do not need to grab the Threads_lock, since we are operating on ourself.
1809 Handle threadObj(thread, thread->threadObj());
1810 assert(threadObj.not_null(), "java thread object must exist");
1811 ObjectLocker lock(threadObj, thread);
1812 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1813 thread->clear_pending_exception();
1814 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1815 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1816 // Clear the native thread instance - this makes isAlive return false and allows the join()
1817 // to complete once we've done the notify_all below
1818 java_lang_Thread::set_thread(threadObj(), NULL);
1819 lock.notify_all(thread);
1820 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1821 thread->clear_pending_exception();
1822 }
1823
1824
1825 // For any new cleanup additions, please check to see if they need to be applied to
1826 // cleanup_failed_attach_current_thread as well.
1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1828 assert(this == JavaThread::current(), "thread consistency check");
1829
1830 elapsedTimer _timer_exit_phase1;
1831 elapsedTimer _timer_exit_phase2;
1832 elapsedTimer _timer_exit_phase3;
1833 elapsedTimer _timer_exit_phase4;
1834
1835 if (log_is_enabled(Debug, os, thread, timer)) {
1836 _timer_exit_phase1.start();
1837 }
1838
1839 HandleMark hm(this);
1840 Handle uncaught_exception(this, this->pending_exception());
1841 this->clear_pending_exception();
1842 Handle threadObj(this, this->threadObj());
1843 assert(threadObj.not_null(), "Java thread object should be created");
1844
1845 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1846 {
1847 EXCEPTION_MARK;
1848
1849 CLEAR_PENDING_EXCEPTION;
1850 }
1851 if (!destroy_vm) {
1852 if (uncaught_exception.not_null()) {
1853 EXCEPTION_MARK;
1854 // Call method Thread.dispatchUncaughtException().
1855 Klass* thread_klass = SystemDictionary::Thread_klass();
1856 JavaValue result(T_VOID);
1857 JavaCalls::call_virtual(&result,
1858 threadObj, thread_klass,
1859 vmSymbols::dispatchUncaughtException_name(),
1860 vmSymbols::throwable_void_signature(),
1861 uncaught_exception,
1862 THREAD);
1863 if (HAS_PENDING_EXCEPTION) {
1864 ResourceMark rm(this);
1865 jio_fprintf(defaultStream::error_stream(),
1866 "\nException: %s thrown from the UncaughtExceptionHandler"
1867 " in thread \"%s\"\n",
1868 pending_exception()->klass()->external_name(),
1869 get_thread_name());
1870 CLEAR_PENDING_EXCEPTION;
1871 }
1872 }
1873
1874 // Called before the java thread exit since we want to read info
1875 // from java_lang_Thread object
1876 EventThreadEnd event;
1877 if (event.should_commit()) {
1878 event.set_thread(THREAD_TRACE_ID(this));
1879 event.commit();
1880 }
1881
1882 // Call after last event on thread
1883 EVENT_THREAD_EXIT(this);
1884
1885 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1886 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1887 // is deprecated anyhow.
1888 if (!is_Compiler_thread()) {
1889 int count = 3;
1890 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1891 EXCEPTION_MARK;
1892 JavaValue result(T_VOID);
1893 Klass* thread_klass = SystemDictionary::Thread_klass();
1894 JavaCalls::call_virtual(&result,
1895 threadObj, thread_klass,
1896 vmSymbols::exit_method_name(),
1897 vmSymbols::void_method_signature(),
1898 THREAD);
1899 CLEAR_PENDING_EXCEPTION;
1900 }
1901 }
1902 // notify JVMTI
1903 if (JvmtiExport::should_post_thread_life()) {
1904 JvmtiExport::post_thread_end(this);
1905 }
1906
1907 // We have notified the agents that we are exiting, before we go on,
1908 // we must check for a pending external suspend request and honor it
1909 // in order to not surprise the thread that made the suspend request.
1910 while (true) {
1911 {
1912 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1913 if (!is_external_suspend()) {
1914 set_terminated(_thread_exiting);
1915 ThreadService::current_thread_exiting(this);
1916 break;
1917 }
1918 // Implied else:
1919 // Things get a little tricky here. We have a pending external
1920 // suspend request, but we are holding the SR_lock so we
1921 // can't just self-suspend. So we temporarily drop the lock
1922 // and then self-suspend.
1923 }
1924
1925 ThreadBlockInVM tbivm(this);
1926 java_suspend_self();
1927
1928 // We're done with this suspend request, but we have to loop around
1929 // and check again. Eventually we will get SR_lock without a pending
1930 // external suspend request and will be able to mark ourselves as
1931 // exiting.
1932 }
1933 // no more external suspends are allowed at this point
1934 } else {
1935 // before_exit() has already posted JVMTI THREAD_END events
1936 }
1937
1938 if (log_is_enabled(Debug, os, thread, timer)) {
1939 _timer_exit_phase1.stop();
1940 _timer_exit_phase2.start();
1941 }
1942 // Notify waiters on thread object. This has to be done after exit() is called
1943 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1944 // group should have the destroyed bit set before waiters are notified).
1945 ensure_join(this);
1946 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1947
1948 if (log_is_enabled(Debug, os, thread, timer)) {
1949 _timer_exit_phase2.stop();
1950 _timer_exit_phase3.start();
1951 }
1952 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1953 // held by this thread must be released. The spec does not distinguish
1954 // between JNI-acquired and regular Java monitors. We can only see
1955 // regular Java monitors here if monitor enter-exit matching is broken.
1956 //
1957 // Optionally release any monitors for regular JavaThread exits. This
1958 // is provided as a work around for any bugs in monitor enter-exit
1959 // matching. This can be expensive so it is not enabled by default.
1960 //
1961 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1962 // ObjectSynchronizer::release_monitors_owned_by_thread().
1963 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1964 // Sanity check even though JNI DetachCurrentThread() would have
1965 // returned JNI_ERR if there was a Java frame. JavaThread exit
1966 // should be done executing Java code by the time we get here.
1967 assert(!this->has_last_Java_frame(),
1968 "should not have a Java frame when detaching or exiting");
1969 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1970 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1971 }
1972
1973 // These things needs to be done while we are still a Java Thread. Make sure that thread
1974 // is in a consistent state, in case GC happens
1975 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1976
1977 if (active_handles() != NULL) {
1978 JNIHandleBlock* block = active_handles();
1979 set_active_handles(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 if (free_handle_block() != NULL) {
1984 JNIHandleBlock* block = free_handle_block();
1985 set_free_handle_block(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 // These have to be removed while this is still a valid thread.
1990 remove_stack_guard_pages();
1991
1992 if (UseTLAB) {
1993 tlab().make_parsable(true); // retire TLAB
1994 }
1995
1996 if (JvmtiEnv::environments_might_exist()) {
1997 JvmtiExport::cleanup_thread(this);
1998 }
1999
2000 // We must flush any deferred card marks before removing a thread from
2001 // the list of active threads.
2002 Universe::heap()->flush_deferred_store_barrier(this);
2003 assert(deferred_card_mark().is_empty(), "Should have been flushed");
2004
2005 #if INCLUDE_ALL_GCS
2006 // We must flush the G1-related buffers before removing a thread
2007 // from the list of active threads. We must do this after any deferred
2008 // card marks have been flushed (above) so that any entries that are
2009 // added to the thread's dirty card queue as a result are not lost.
2010 if (UseG1GC) {
2011 flush_barrier_queues();
2012 }
2013 #endif // INCLUDE_ALL_GCS
2014
2015 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2016 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2017 os::current_thread_id());
2018
2019 if (log_is_enabled(Debug, os, thread, timer)) {
2020 _timer_exit_phase3.stop();
2021 _timer_exit_phase4.start();
2022 }
2023 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2024 Threads::remove(this);
2025
2026 if (log_is_enabled(Debug, os, thread, timer)) {
2027 _timer_exit_phase4.stop();
2028 ResourceMark rm(this);
2029 log_debug(os, thread, timer)("name='%s'"
2030 ", exit-phase1=" JLONG_FORMAT
2031 ", exit-phase2=" JLONG_FORMAT
2032 ", exit-phase3=" JLONG_FORMAT
2033 ", exit-phase4=" JLONG_FORMAT,
2034 get_thread_name(),
2035 _timer_exit_phase1.milliseconds(),
2036 _timer_exit_phase2.milliseconds(),
2037 _timer_exit_phase3.milliseconds(),
2038 _timer_exit_phase4.milliseconds());
2039 }
2040 }
2041
2042 #if INCLUDE_ALL_GCS
2043 // Flush G1-related queues.
2044 void JavaThread::flush_barrier_queues() {
2045 satb_mark_queue().flush();
2046 dirty_card_queue().flush();
2047 }
2048
2049 void JavaThread::initialize_queues() {
2050 assert(!SafepointSynchronize::is_at_safepoint(),
2051 "we should not be at a safepoint");
2052
2053 SATBMarkQueue& satb_queue = satb_mark_queue();
2054 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2055 // The SATB queue should have been constructed with its active
2056 // field set to false.
2057 assert(!satb_queue.is_active(), "SATB queue should not be active");
2058 assert(satb_queue.is_empty(), "SATB queue should be empty");
2059 // If we are creating the thread during a marking cycle, we should
2060 // set the active field of the SATB queue to true.
2061 if (satb_queue_set.is_active()) {
2062 satb_queue.set_active(true);
2063 }
2064
2065 DirtyCardQueue& dirty_queue = dirty_card_queue();
2066 // The dirty card queue should have been constructed with its
2067 // active field set to true.
2068 assert(dirty_queue.is_active(), "dirty card queue should be active");
2069 }
2070 #endif // INCLUDE_ALL_GCS
2071
2072 void JavaThread::cleanup_failed_attach_current_thread() {
2073 if (active_handles() != NULL) {
2074 JNIHandleBlock* block = active_handles();
2075 set_active_handles(NULL);
2076 JNIHandleBlock::release_block(block);
2077 }
2078
2079 if (free_handle_block() != NULL) {
2080 JNIHandleBlock* block = free_handle_block();
2081 set_free_handle_block(NULL);
2082 JNIHandleBlock::release_block(block);
2083 }
2084
2085 // These have to be removed while this is still a valid thread.
2086 remove_stack_guard_pages();
2087
2088 if (UseTLAB) {
2089 tlab().make_parsable(true); // retire TLAB, if any
2090 }
2091
2092 #if INCLUDE_ALL_GCS
2093 if (UseG1GC) {
2094 flush_barrier_queues();
2095 }
2096 #endif // INCLUDE_ALL_GCS
2097
2098 Threads::remove(this);
2099 this->smr_delete();
2100 }
2101
2102
2103
2104
2105 JavaThread* JavaThread::active() {
2106 Thread* thread = Thread::current();
2107 if (thread->is_Java_thread()) {
2108 return (JavaThread*) thread;
2109 } else {
2110 assert(thread->is_VM_thread(), "this must be a vm thread");
2111 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2112 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2113 assert(ret->is_Java_thread(), "must be a Java thread");
2114 return ret;
2115 }
2116 }
2117
2118 bool JavaThread::is_lock_owned(address adr) const {
2119 if (Thread::is_lock_owned(adr)) return true;
2120
2121 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2122 if (chunk->contains(adr)) return true;
2123 }
2124
2125 return false;
2126 }
2127
2128
2129 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2130 chunk->set_next(monitor_chunks());
2131 set_monitor_chunks(chunk);
2132 }
2133
2134 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2135 guarantee(monitor_chunks() != NULL, "must be non empty");
2136 if (monitor_chunks() == chunk) {
2137 set_monitor_chunks(chunk->next());
2138 } else {
2139 MonitorChunk* prev = monitor_chunks();
2140 while (prev->next() != chunk) prev = prev->next();
2141 prev->set_next(chunk->next());
2142 }
2143 }
2144
2145 // JVM support.
2146
2147 // Note: this function shouldn't block if it's called in
2148 // _thread_in_native_trans state (such as from
2149 // check_special_condition_for_native_trans()).
2150 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2151
2152 if (has_last_Java_frame() && has_async_condition()) {
2153 // If we are at a polling page safepoint (not a poll return)
2154 // then we must defer async exception because live registers
2155 // will be clobbered by the exception path. Poll return is
2156 // ok because the call we a returning from already collides
2157 // with exception handling registers and so there is no issue.
2158 // (The exception handling path kills call result registers but
2159 // this is ok since the exception kills the result anyway).
2160
2161 if (is_at_poll_safepoint()) {
2162 // if the code we are returning to has deoptimized we must defer
2163 // the exception otherwise live registers get clobbered on the
2164 // exception path before deoptimization is able to retrieve them.
2165 //
2166 RegisterMap map(this, false);
2167 frame caller_fr = last_frame().sender(&map);
2168 assert(caller_fr.is_compiled_frame(), "what?");
2169 if (caller_fr.is_deoptimized_frame()) {
2170 log_info(exceptions)("deferred async exception at compiled safepoint");
2171 return;
2172 }
2173 }
2174 }
2175
2176 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2177 if (condition == _no_async_condition) {
2178 // Conditions have changed since has_special_runtime_exit_condition()
2179 // was called:
2180 // - if we were here only because of an external suspend request,
2181 // then that was taken care of above (or cancelled) so we are done
2182 // - if we were here because of another async request, then it has
2183 // been cleared between the has_special_runtime_exit_condition()
2184 // and now so again we are done
2185 return;
2186 }
2187
2188 // Check for pending async. exception
2189 if (_pending_async_exception != NULL) {
2190 // Only overwrite an already pending exception, if it is not a threadDeath.
2191 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2192
2193 // We cannot call Exceptions::_throw(...) here because we cannot block
2194 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2195
2196 LogTarget(Info, exceptions) lt;
2197 if (lt.is_enabled()) {
2198 ResourceMark rm;
2199 LogStream ls(lt);
2200 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2201 if (has_last_Java_frame()) {
2202 frame f = last_frame();
2203 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2204 }
2205 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2206 }
2207 _pending_async_exception = NULL;
2208 clear_has_async_exception();
2209 }
2210 }
2211
2212 if (check_unsafe_error &&
2213 condition == _async_unsafe_access_error && !has_pending_exception()) {
2214 condition = _no_async_condition; // done
2215 switch (thread_state()) {
2216 case _thread_in_vm: {
2217 JavaThread* THREAD = this;
2218 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2219 }
2220 case _thread_in_native: {
2221 ThreadInVMfromNative tiv(this);
2222 JavaThread* THREAD = this;
2223 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2224 }
2225 case _thread_in_Java: {
2226 ThreadInVMfromJava tiv(this);
2227 JavaThread* THREAD = this;
2228 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2229 }
2230 default:
2231 ShouldNotReachHere();
2232 }
2233 }
2234
2235 assert(condition == _no_async_condition || has_pending_exception() ||
2236 (!check_unsafe_error && condition == _async_unsafe_access_error),
2237 "must have handled the async condition, if no exception");
2238 }
2239
2240 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2241 //
2242 // Check for pending external suspend. Internal suspend requests do
2243 // not use handle_special_runtime_exit_condition().
2244 // If JNIEnv proxies are allowed, don't self-suspend if the target
2245 // thread is not the current thread. In older versions of jdbx, jdbx
2246 // threads could call into the VM with another thread's JNIEnv so we
2247 // can be here operating on behalf of a suspended thread (4432884).
2248 bool do_self_suspend = is_external_suspend_with_lock();
2249 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2250 //
2251 // Because thread is external suspended the safepoint code will count
2252 // thread as at a safepoint. This can be odd because we can be here
2253 // as _thread_in_Java which would normally transition to _thread_blocked
2254 // at a safepoint. We would like to mark the thread as _thread_blocked
2255 // before calling java_suspend_self like all other callers of it but
2256 // we must then observe proper safepoint protocol. (We can't leave
2257 // _thread_blocked with a safepoint in progress). However we can be
2258 // here as _thread_in_native_trans so we can't use a normal transition
2259 // constructor/destructor pair because they assert on that type of
2260 // transition. We could do something like:
2261 //
2262 // JavaThreadState state = thread_state();
2263 // set_thread_state(_thread_in_vm);
2264 // {
2265 // ThreadBlockInVM tbivm(this);
2266 // java_suspend_self()
2267 // }
2268 // set_thread_state(_thread_in_vm_trans);
2269 // if (safepoint) block;
2270 // set_thread_state(state);
2271 //
2272 // but that is pretty messy. Instead we just go with the way the
2273 // code has worked before and note that this is the only path to
2274 // java_suspend_self that doesn't put the thread in _thread_blocked
2275 // mode.
2276
2277 frame_anchor()->make_walkable(this);
2278 java_suspend_self();
2279
2280 // We might be here for reasons in addition to the self-suspend request
2281 // so check for other async requests.
2282 }
2283
2284 if (check_asyncs) {
2285 check_and_handle_async_exceptions();
2286 }
2287 #if INCLUDE_TRACE
2288 if (is_trace_suspend()) {
2289 TRACE_SUSPEND_THREAD(this);
2290 }
2291 #endif
2292 }
2293
2294 void JavaThread::send_thread_stop(oop java_throwable) {
2295 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2296 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2297 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2298
2299 // Do not throw asynchronous exceptions against the compiler thread
2300 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2301 if (!can_call_java()) return;
2302
2303 {
2304 // Actually throw the Throwable against the target Thread - however
2305 // only if there is no thread death exception installed already.
2306 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2307 // If the topmost frame is a runtime stub, then we are calling into
2308 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2309 // must deoptimize the caller before continuing, as the compiled exception handler table
2310 // may not be valid
2311 if (has_last_Java_frame()) {
2312 frame f = last_frame();
2313 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2314 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2315 RegisterMap reg_map(this, UseBiasedLocking);
2316 frame compiled_frame = f.sender(®_map);
2317 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2318 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2319 }
2320 }
2321 }
2322
2323 // Set async. pending exception in thread.
2324 set_pending_async_exception(java_throwable);
2325
2326 if (log_is_enabled(Info, exceptions)) {
2327 ResourceMark rm;
2328 log_info(exceptions)("Pending Async. exception installed of type: %s",
2329 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2330 }
2331 // for AbortVMOnException flag
2332 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2333 }
2334 }
2335
2336
2337 // Interrupt thread so it will wake up from a potential wait()
2338 Thread::interrupt(this);
2339 }
2340
2341 // External suspension mechanism.
2342 //
2343 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2344 // to any VM_locks and it is at a transition
2345 // Self-suspension will happen on the transition out of the vm.
2346 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2347 //
2348 // Guarantees on return:
2349 // + Target thread will not execute any new bytecode (that's why we need to
2350 // force a safepoint)
2351 // + Target thread will not enter any new monitors
2352 //
2353 void JavaThread::java_suspend() {
2354 ThreadsListHandle tlh;
2355 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2356 return;
2357 }
2358
2359 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2360 if (!is_external_suspend()) {
2361 // a racing resume has cancelled us; bail out now
2362 return;
2363 }
2364
2365 // suspend is done
2366 uint32_t debug_bits = 0;
2367 // Warning: is_ext_suspend_completed() may temporarily drop the
2368 // SR_lock to allow the thread to reach a stable thread state if
2369 // it is currently in a transient thread state.
2370 if (is_ext_suspend_completed(false /* !called_by_wait */,
2371 SuspendRetryDelay, &debug_bits)) {
2372 return;
2373 }
2374 }
2375
2376 VM_ThreadSuspend vm_suspend;
2377 VMThread::execute(&vm_suspend);
2378 }
2379
2380 // Part II of external suspension.
2381 // A JavaThread self suspends when it detects a pending external suspend
2382 // request. This is usually on transitions. It is also done in places
2383 // where continuing to the next transition would surprise the caller,
2384 // e.g., monitor entry.
2385 //
2386 // Returns the number of times that the thread self-suspended.
2387 //
2388 // Note: DO NOT call java_suspend_self() when you just want to block current
2389 // thread. java_suspend_self() is the second stage of cooperative
2390 // suspension for external suspend requests and should only be used
2391 // to complete an external suspend request.
2392 //
2393 int JavaThread::java_suspend_self() {
2394 int ret = 0;
2395
2396 // we are in the process of exiting so don't suspend
2397 if (is_exiting()) {
2398 clear_external_suspend();
2399 return ret;
2400 }
2401
2402 assert(_anchor.walkable() ||
2403 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2404 "must have walkable stack");
2405
2406 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2407
2408 assert(!this->is_ext_suspended(),
2409 "a thread trying to self-suspend should not already be suspended");
2410
2411 if (this->is_suspend_equivalent()) {
2412 // If we are self-suspending as a result of the lifting of a
2413 // suspend equivalent condition, then the suspend_equivalent
2414 // flag is not cleared until we set the ext_suspended flag so
2415 // that wait_for_ext_suspend_completion() returns consistent
2416 // results.
2417 this->clear_suspend_equivalent();
2418 }
2419
2420 // A racing resume may have cancelled us before we grabbed SR_lock
2421 // above. Or another external suspend request could be waiting for us
2422 // by the time we return from SR_lock()->wait(). The thread
2423 // that requested the suspension may already be trying to walk our
2424 // stack and if we return now, we can change the stack out from under
2425 // it. This would be a "bad thing (TM)" and cause the stack walker
2426 // to crash. We stay self-suspended until there are no more pending
2427 // external suspend requests.
2428 while (is_external_suspend()) {
2429 ret++;
2430 this->set_ext_suspended();
2431
2432 // _ext_suspended flag is cleared by java_resume()
2433 while (is_ext_suspended()) {
2434 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2435 }
2436 }
2437
2438 return ret;
2439 }
2440
2441 #ifdef ASSERT
2442 // verify the JavaThread has not yet been published in the Threads::list, and
2443 // hence doesn't need protection from concurrent access at this stage
2444 void JavaThread::verify_not_published() {
2445 ThreadsListHandle tlh;
2446 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2447 }
2448 #endif
2449
2450 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2451 // progress or when _suspend_flags is non-zero.
2452 // Current thread needs to self-suspend if there is a suspend request and/or
2453 // block if a safepoint is in progress.
2454 // Async exception ISN'T checked.
2455 // Note only the ThreadInVMfromNative transition can call this function
2456 // directly and when thread state is _thread_in_native_trans
2457 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2458 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2459
2460 JavaThread *curJT = JavaThread::current();
2461 bool do_self_suspend = thread->is_external_suspend();
2462
2463 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2464
2465 // If JNIEnv proxies are allowed, don't self-suspend if the target
2466 // thread is not the current thread. In older versions of jdbx, jdbx
2467 // threads could call into the VM with another thread's JNIEnv so we
2468 // can be here operating on behalf of a suspended thread (4432884).
2469 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2470 JavaThreadState state = thread->thread_state();
2471
2472 // We mark this thread_blocked state as a suspend-equivalent so
2473 // that a caller to is_ext_suspend_completed() won't be confused.
2474 // The suspend-equivalent state is cleared by java_suspend_self().
2475 thread->set_suspend_equivalent();
2476
2477 // If the safepoint code sees the _thread_in_native_trans state, it will
2478 // wait until the thread changes to other thread state. There is no
2479 // guarantee on how soon we can obtain the SR_lock and complete the
2480 // self-suspend request. It would be a bad idea to let safepoint wait for
2481 // too long. Temporarily change the state to _thread_blocked to
2482 // let the VM thread know that this thread is ready for GC. The problem
2483 // of changing thread state is that safepoint could happen just after
2484 // java_suspend_self() returns after being resumed, and VM thread will
2485 // see the _thread_blocked state. We must check for safepoint
2486 // after restoring the state and make sure we won't leave while a safepoint
2487 // is in progress.
2488 thread->set_thread_state(_thread_blocked);
2489 thread->java_suspend_self();
2490 thread->set_thread_state(state);
2491
2492 InterfaceSupport::serialize_thread_state_with_handler(thread);
2493 }
2494
2495 SafepointMechanism::block_if_requested(curJT);
2496
2497 if (thread->is_deopt_suspend()) {
2498 thread->clear_deopt_suspend();
2499 RegisterMap map(thread, false);
2500 frame f = thread->last_frame();
2501 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2502 f = f.sender(&map);
2503 }
2504 if (f.id() == thread->must_deopt_id()) {
2505 thread->clear_must_deopt_id();
2506 f.deoptimize(thread);
2507 } else {
2508 fatal("missed deoptimization!");
2509 }
2510 }
2511 #if INCLUDE_TRACE
2512 if (thread->is_trace_suspend()) {
2513 TRACE_SUSPEND_THREAD(thread);
2514 }
2515 #endif
2516 }
2517
2518 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2519 // progress or when _suspend_flags is non-zero.
2520 // Current thread needs to self-suspend if there is a suspend request and/or
2521 // block if a safepoint is in progress.
2522 // Also check for pending async exception (not including unsafe access error).
2523 // Note only the native==>VM/Java barriers can call this function and when
2524 // thread state is _thread_in_native_trans.
2525 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2526 check_safepoint_and_suspend_for_native_trans(thread);
2527
2528 if (thread->has_async_exception()) {
2529 // We are in _thread_in_native_trans state, don't handle unsafe
2530 // access error since that may block.
2531 thread->check_and_handle_async_exceptions(false);
2532 }
2533 }
2534
2535 // This is a variant of the normal
2536 // check_special_condition_for_native_trans with slightly different
2537 // semantics for use by critical native wrappers. It does all the
2538 // normal checks but also performs the transition back into
2539 // thread_in_Java state. This is required so that critical natives
2540 // can potentially block and perform a GC if they are the last thread
2541 // exiting the GCLocker.
2542 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2543 check_special_condition_for_native_trans(thread);
2544
2545 // Finish the transition
2546 thread->set_thread_state(_thread_in_Java);
2547
2548 if (thread->do_critical_native_unlock()) {
2549 ThreadInVMfromJavaNoAsyncException tiv(thread);
2550 GCLocker::unlock_critical(thread);
2551 thread->clear_critical_native_unlock();
2552 }
2553 }
2554
2555 // We need to guarantee the Threads_lock here, since resumes are not
2556 // allowed during safepoint synchronization
2557 // Can only resume from an external suspension
2558 void JavaThread::java_resume() {
2559 assert_locked_or_safepoint(Threads_lock);
2560
2561 // Sanity check: thread is gone, has started exiting or the thread
2562 // was not externally suspended.
2563 ThreadsListHandle tlh;
2564 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2565 return;
2566 }
2567
2568 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2569
2570 clear_external_suspend();
2571
2572 if (is_ext_suspended()) {
2573 clear_ext_suspended();
2574 SR_lock()->notify_all();
2575 }
2576 }
2577
2578 size_t JavaThread::_stack_red_zone_size = 0;
2579 size_t JavaThread::_stack_yellow_zone_size = 0;
2580 size_t JavaThread::_stack_reserved_zone_size = 0;
2581 size_t JavaThread::_stack_shadow_zone_size = 0;
2582
2583 void JavaThread::create_stack_guard_pages() {
2584 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2585 address low_addr = stack_end();
2586 size_t len = stack_guard_zone_size();
2587
2588 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2589 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2590
2591 int must_commit = os::must_commit_stack_guard_pages();
2592 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2593
2594 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2595 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2596 return;
2597 }
2598
2599 if (os::guard_memory((char *) low_addr, len)) {
2600 _stack_guard_state = stack_guard_enabled;
2601 } else {
2602 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2603 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2604 if (os::uncommit_memory((char *) low_addr, len)) {
2605 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2606 }
2607 return;
2608 }
2609
2610 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2611 PTR_FORMAT "-" PTR_FORMAT ".",
2612 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2613 }
2614
2615 void JavaThread::remove_stack_guard_pages() {
2616 assert(Thread::current() == this, "from different thread");
2617 if (_stack_guard_state == stack_guard_unused) return;
2618 address low_addr = stack_end();
2619 size_t len = stack_guard_zone_size();
2620
2621 if (os::must_commit_stack_guard_pages()) {
2622 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2623 _stack_guard_state = stack_guard_unused;
2624 } else {
2625 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2626 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2627 return;
2628 }
2629 } else {
2630 if (_stack_guard_state == stack_guard_unused) return;
2631 if (os::unguard_memory((char *) low_addr, len)) {
2632 _stack_guard_state = stack_guard_unused;
2633 } else {
2634 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2635 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2636 return;
2637 }
2638 }
2639
2640 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2641 PTR_FORMAT "-" PTR_FORMAT ".",
2642 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2643 }
2644
2645 void JavaThread::enable_stack_reserved_zone() {
2646 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2647 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2648
2649 // The base notation is from the stack's point of view, growing downward.
2650 // We need to adjust it to work correctly with guard_memory()
2651 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2652
2653 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2654 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2655
2656 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2657 _stack_guard_state = stack_guard_enabled;
2658 } else {
2659 warning("Attempt to guard stack reserved zone failed.");
2660 }
2661 enable_register_stack_guard();
2662 }
2663
2664 void JavaThread::disable_stack_reserved_zone() {
2665 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2666 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2667
2668 // Simply return if called for a thread that does not use guard pages.
2669 if (_stack_guard_state == stack_guard_unused) return;
2670
2671 // The base notation is from the stack's point of view, growing downward.
2672 // We need to adjust it to work correctly with guard_memory()
2673 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2674
2675 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2676 _stack_guard_state = stack_guard_reserved_disabled;
2677 } else {
2678 warning("Attempt to unguard stack reserved zone failed.");
2679 }
2680 disable_register_stack_guard();
2681 }
2682
2683 void JavaThread::enable_stack_yellow_reserved_zone() {
2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2685 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2686
2687 // The base notation is from the stacks point of view, growing downward.
2688 // We need to adjust it to work correctly with guard_memory()
2689 address base = stack_red_zone_base();
2690
2691 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2692 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2693
2694 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2695 _stack_guard_state = stack_guard_enabled;
2696 } else {
2697 warning("Attempt to guard stack yellow zone failed.");
2698 }
2699 enable_register_stack_guard();
2700 }
2701
2702 void JavaThread::disable_stack_yellow_reserved_zone() {
2703 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2704 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2705
2706 // Simply return if called for a thread that does not use guard pages.
2707 if (_stack_guard_state == stack_guard_unused) return;
2708
2709 // The base notation is from the stacks point of view, growing downward.
2710 // We need to adjust it to work correctly with guard_memory()
2711 address base = stack_red_zone_base();
2712
2713 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2714 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2715 } else {
2716 warning("Attempt to unguard stack yellow zone failed.");
2717 }
2718 disable_register_stack_guard();
2719 }
2720
2721 void JavaThread::enable_stack_red_zone() {
2722 // The base notation is from the stacks point of view, growing downward.
2723 // We need to adjust it to work correctly with guard_memory()
2724 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2725 address base = stack_red_zone_base() - stack_red_zone_size();
2726
2727 guarantee(base < stack_base(), "Error calculating stack red zone");
2728 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2729
2730 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2731 warning("Attempt to guard stack red zone failed.");
2732 }
2733 }
2734
2735 void JavaThread::disable_stack_red_zone() {
2736 // The base notation is from the stacks point of view, growing downward.
2737 // We need to adjust it to work correctly with guard_memory()
2738 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2739 address base = stack_red_zone_base() - stack_red_zone_size();
2740 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2741 warning("Attempt to unguard stack red zone failed.");
2742 }
2743 }
2744
2745 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2746 // ignore is there is no stack
2747 if (!has_last_Java_frame()) return;
2748 // traverse the stack frames. Starts from top frame.
2749 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2750 frame* fr = fst.current();
2751 f(fr, fst.register_map());
2752 }
2753 }
2754
2755
2756 #ifndef PRODUCT
2757 // Deoptimization
2758 // Function for testing deoptimization
2759 void JavaThread::deoptimize() {
2760 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2761 StackFrameStream fst(this, UseBiasedLocking);
2762 bool deopt = false; // Dump stack only if a deopt actually happens.
2763 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2764 // Iterate over all frames in the thread and deoptimize
2765 for (; !fst.is_done(); fst.next()) {
2766 if (fst.current()->can_be_deoptimized()) {
2767
2768 if (only_at) {
2769 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2770 // consists of comma or carriage return separated numbers so
2771 // search for the current bci in that string.
2772 address pc = fst.current()->pc();
2773 nmethod* nm = (nmethod*) fst.current()->cb();
2774 ScopeDesc* sd = nm->scope_desc_at(pc);
2775 char buffer[8];
2776 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2777 size_t len = strlen(buffer);
2778 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2779 while (found != NULL) {
2780 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2781 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2782 // Check that the bci found is bracketed by terminators.
2783 break;
2784 }
2785 found = strstr(found + 1, buffer);
2786 }
2787 if (!found) {
2788 continue;
2789 }
2790 }
2791
2792 if (DebugDeoptimization && !deopt) {
2793 deopt = true; // One-time only print before deopt
2794 tty->print_cr("[BEFORE Deoptimization]");
2795 trace_frames();
2796 trace_stack();
2797 }
2798 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2799 }
2800 }
2801
2802 if (DebugDeoptimization && deopt) {
2803 tty->print_cr("[AFTER Deoptimization]");
2804 trace_frames();
2805 }
2806 }
2807
2808
2809 // Make zombies
2810 void JavaThread::make_zombies() {
2811 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2812 if (fst.current()->can_be_deoptimized()) {
2813 // it is a Java nmethod
2814 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2815 nm->make_not_entrant();
2816 }
2817 }
2818 }
2819 #endif // PRODUCT
2820
2821
2822 void JavaThread::deoptimized_wrt_marked_nmethods() {
2823 if (!has_last_Java_frame()) return;
2824 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2825 StackFrameStream fst(this, UseBiasedLocking);
2826 for (; !fst.is_done(); fst.next()) {
2827 if (fst.current()->should_be_deoptimized()) {
2828 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2829 }
2830 }
2831 }
2832
2833
2834 // If the caller is a NamedThread, then remember, in the current scope,
2835 // the given JavaThread in its _processed_thread field.
2836 class RememberProcessedThread: public StackObj {
2837 NamedThread* _cur_thr;
2838 public:
2839 RememberProcessedThread(JavaThread* jthr) {
2840 Thread* thread = Thread::current();
2841 if (thread->is_Named_thread()) {
2842 _cur_thr = (NamedThread *)thread;
2843 _cur_thr->set_processed_thread(jthr);
2844 } else {
2845 _cur_thr = NULL;
2846 }
2847 }
2848
2849 ~RememberProcessedThread() {
2850 if (_cur_thr) {
2851 _cur_thr->set_processed_thread(NULL);
2852 }
2853 }
2854 };
2855
2856 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2857 // Verify that the deferred card marks have been flushed.
2858 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2859
2860 // Traverse the GCHandles
2861 Thread::oops_do(f, cf);
2862
2863 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2864
2865 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2866 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2867
2868 if (has_last_Java_frame()) {
2869 // Record JavaThread to GC thread
2870 RememberProcessedThread rpt(this);
2871
2872 // Traverse the privileged stack
2873 if (_privileged_stack_top != NULL) {
2874 _privileged_stack_top->oops_do(f);
2875 }
2876
2877 // traverse the registered growable array
2878 if (_array_for_gc != NULL) {
2879 for (int index = 0; index < _array_for_gc->length(); index++) {
2880 f->do_oop(_array_for_gc->adr_at(index));
2881 }
2882 }
2883
2884 // Traverse the monitor chunks
2885 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2886 chunk->oops_do(f);
2887 }
2888
2889 // Traverse the execution stack
2890 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2891 fst.current()->oops_do(f, cf, fst.register_map());
2892 }
2893 }
2894
2895 // callee_target is never live across a gc point so NULL it here should
2896 // it still contain a methdOop.
2897
2898 set_callee_target(NULL);
2899
2900 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2901 // If we have deferred set_locals there might be oops waiting to be
2902 // written
2903 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2904 if (list != NULL) {
2905 for (int i = 0; i < list->length(); i++) {
2906 list->at(i)->oops_do(f);
2907 }
2908 }
2909
2910 // Traverse instance variables at the end since the GC may be moving things
2911 // around using this function
2912 f->do_oop((oop*) &_threadObj);
2913 f->do_oop((oop*) &_vm_result);
2914 f->do_oop((oop*) &_exception_oop);
2915 f->do_oop((oop*) &_pending_async_exception);
2916
2917 if (jvmti_thread_state() != NULL) {
2918 jvmti_thread_state()->oops_do(f);
2919 }
2920 }
2921
2922 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2923 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2924 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2925
2926 if (has_last_Java_frame()) {
2927 // Traverse the execution stack
2928 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2929 fst.current()->nmethods_do(cf);
2930 }
2931 }
2932 }
2933
2934 void JavaThread::metadata_do(void f(Metadata*)) {
2935 if (has_last_Java_frame()) {
2936 // Traverse the execution stack to call f() on the methods in the stack
2937 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2938 fst.current()->metadata_do(f);
2939 }
2940 } else if (is_Compiler_thread()) {
2941 // need to walk ciMetadata in current compile tasks to keep alive.
2942 CompilerThread* ct = (CompilerThread*)this;
2943 if (ct->env() != NULL) {
2944 ct->env()->metadata_do(f);
2945 }
2946 if (ct->task() != NULL) {
2947 ct->task()->metadata_do(f);
2948 }
2949 }
2950 }
2951
2952 // Printing
2953 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2954 switch (_thread_state) {
2955 case _thread_uninitialized: return "_thread_uninitialized";
2956 case _thread_new: return "_thread_new";
2957 case _thread_new_trans: return "_thread_new_trans";
2958 case _thread_in_native: return "_thread_in_native";
2959 case _thread_in_native_trans: return "_thread_in_native_trans";
2960 case _thread_in_vm: return "_thread_in_vm";
2961 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2962 case _thread_in_Java: return "_thread_in_Java";
2963 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2964 case _thread_blocked: return "_thread_blocked";
2965 case _thread_blocked_trans: return "_thread_blocked_trans";
2966 default: return "unknown thread state";
2967 }
2968 }
2969
2970 #ifndef PRODUCT
2971 void JavaThread::print_thread_state_on(outputStream *st) const {
2972 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2973 };
2974 void JavaThread::print_thread_state() const {
2975 print_thread_state_on(tty);
2976 }
2977 #endif // PRODUCT
2978
2979 // Called by Threads::print() for VM_PrintThreads operation
2980 void JavaThread::print_on(outputStream *st) const {
2981 st->print_raw("\"");
2982 st->print_raw(get_thread_name());
2983 st->print_raw("\" ");
2984 oop thread_oop = threadObj();
2985 if (thread_oop != NULL) {
2986 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2987 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2988 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2989 }
2990 Thread::print_on(st);
2991 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2992 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2993 if (thread_oop != NULL) {
2994 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2995 }
2996 #ifndef PRODUCT
2997 print_thread_state_on(st);
2998 _safepoint_state->print_on(st);
2999 #endif // PRODUCT
3000 if (is_Compiler_thread()) {
3001 CompilerThread* ct = (CompilerThread*)this;
3002 if (ct->task() != NULL) {
3003 st->print(" Compiling: ");
3004 ct->task()->print(st, NULL, true, false);
3005 } else {
3006 st->print(" No compile task");
3007 }
3008 st->cr();
3009 }
3010 }
3011
3012 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3013 st->print("%s", get_thread_name_string(buf, buflen));
3014 }
3015
3016 // Called by fatal error handler. The difference between this and
3017 // JavaThread::print() is that we can't grab lock or allocate memory.
3018 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3019 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3020 oop thread_obj = threadObj();
3021 if (thread_obj != NULL) {
3022 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3023 }
3024 st->print(" [");
3025 st->print("%s", _get_thread_state_name(_thread_state));
3026 if (osthread()) {
3027 st->print(", id=%d", osthread()->thread_id());
3028 }
3029 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3030 p2i(stack_end()), p2i(stack_base()));
3031 st->print("]");
3032
3033 if (_threads_hazard_ptr != NULL) {
3034 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3035 }
3036 if (_nested_threads_hazard_ptr != NULL) {
3037 print_nested_threads_hazard_ptrs_on(st);
3038 }
3039 return;
3040 }
3041
3042 // Verification
3043
3044 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3045
3046 void JavaThread::verify() {
3047 // Verify oops in the thread.
3048 oops_do(&VerifyOopClosure::verify_oop, NULL);
3049
3050 // Verify the stack frames.
3051 frames_do(frame_verify);
3052 }
3053
3054 // CR 6300358 (sub-CR 2137150)
3055 // Most callers of this method assume that it can't return NULL but a
3056 // thread may not have a name whilst it is in the process of attaching to
3057 // the VM - see CR 6412693, and there are places where a JavaThread can be
3058 // seen prior to having it's threadObj set (eg JNI attaching threads and
3059 // if vm exit occurs during initialization). These cases can all be accounted
3060 // for such that this method never returns NULL.
3061 const char* JavaThread::get_thread_name() const {
3062 #ifdef ASSERT
3063 // early safepoints can hit while current thread does not yet have TLS
3064 if (!SafepointSynchronize::is_at_safepoint()) {
3065 Thread *cur = Thread::current();
3066 if (!(cur->is_Java_thread() && cur == this)) {
3067 // Current JavaThreads are allowed to get their own name without
3068 // the Threads_lock.
3069 assert_locked_or_safepoint(Threads_lock);
3070 }
3071 }
3072 #endif // ASSERT
3073 return get_thread_name_string();
3074 }
3075
3076 // Returns a non-NULL representation of this thread's name, or a suitable
3077 // descriptive string if there is no set name
3078 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3079 const char* name_str;
3080 oop thread_obj = threadObj();
3081 if (thread_obj != NULL) {
3082 oop name = java_lang_Thread::name(thread_obj);
3083 if (name != NULL) {
3084 if (buf == NULL) {
3085 name_str = java_lang_String::as_utf8_string(name);
3086 } else {
3087 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3088 }
3089 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3090 name_str = "<no-name - thread is attaching>";
3091 } else {
3092 name_str = Thread::name();
3093 }
3094 } else {
3095 name_str = Thread::name();
3096 }
3097 assert(name_str != NULL, "unexpected NULL thread name");
3098 return name_str;
3099 }
3100
3101
3102 const char* JavaThread::get_threadgroup_name() const {
3103 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3104 oop thread_obj = threadObj();
3105 if (thread_obj != NULL) {
3106 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3107 if (thread_group != NULL) {
3108 // ThreadGroup.name can be null
3109 return java_lang_ThreadGroup::name(thread_group);
3110 }
3111 }
3112 return NULL;
3113 }
3114
3115 const char* JavaThread::get_parent_name() const {
3116 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3117 oop thread_obj = threadObj();
3118 if (thread_obj != NULL) {
3119 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3120 if (thread_group != NULL) {
3121 oop parent = java_lang_ThreadGroup::parent(thread_group);
3122 if (parent != NULL) {
3123 // ThreadGroup.name can be null
3124 return java_lang_ThreadGroup::name(parent);
3125 }
3126 }
3127 }
3128 return NULL;
3129 }
3130
3131 ThreadPriority JavaThread::java_priority() const {
3132 oop thr_oop = threadObj();
3133 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3134 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3135 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3136 return priority;
3137 }
3138
3139 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3140
3141 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3142 // Link Java Thread object <-> C++ Thread
3143
3144 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3145 // and put it into a new Handle. The Handle "thread_oop" can then
3146 // be used to pass the C++ thread object to other methods.
3147
3148 // Set the Java level thread object (jthread) field of the
3149 // new thread (a JavaThread *) to C++ thread object using the
3150 // "thread_oop" handle.
3151
3152 // Set the thread field (a JavaThread *) of the
3153 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3154
3155 Handle thread_oop(Thread::current(),
3156 JNIHandles::resolve_non_null(jni_thread));
3157 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3158 "must be initialized");
3159 set_threadObj(thread_oop());
3160 java_lang_Thread::set_thread(thread_oop(), this);
3161
3162 if (prio == NoPriority) {
3163 prio = java_lang_Thread::priority(thread_oop());
3164 assert(prio != NoPriority, "A valid priority should be present");
3165 }
3166
3167 // Push the Java priority down to the native thread; needs Threads_lock
3168 Thread::set_priority(this, prio);
3169
3170 prepare_ext();
3171
3172 // Add the new thread to the Threads list and set it in motion.
3173 // We must have threads lock in order to call Threads::add.
3174 // It is crucial that we do not block before the thread is
3175 // added to the Threads list for if a GC happens, then the java_thread oop
3176 // will not be visited by GC.
3177 Threads::add(this);
3178 }
3179
3180 oop JavaThread::current_park_blocker() {
3181 // Support for JSR-166 locks
3182 oop thread_oop = threadObj();
3183 if (thread_oop != NULL &&
3184 JDK_Version::current().supports_thread_park_blocker()) {
3185 return java_lang_Thread::park_blocker(thread_oop);
3186 }
3187 return NULL;
3188 }
3189
3190
3191 void JavaThread::print_stack_on(outputStream* st) {
3192 if (!has_last_Java_frame()) return;
3193 ResourceMark rm;
3194 HandleMark hm;
3195
3196 RegisterMap reg_map(this);
3197 vframe* start_vf = last_java_vframe(®_map);
3198 int count = 0;
3199 for (vframe* f = start_vf; f; f = f->sender()) {
3200 if (f->is_java_frame()) {
3201 javaVFrame* jvf = javaVFrame::cast(f);
3202 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3203
3204 // Print out lock information
3205 if (JavaMonitorsInStackTrace) {
3206 jvf->print_lock_info_on(st, count);
3207 }
3208 } else {
3209 // Ignore non-Java frames
3210 }
3211
3212 // Bail-out case for too deep stacks
3213 count++;
3214 if (MaxJavaStackTraceDepth == count) return;
3215 }
3216 }
3217
3218
3219 // JVMTI PopFrame support
3220 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3221 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3222 if (in_bytes(size_in_bytes) != 0) {
3223 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3224 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3225 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3226 }
3227 }
3228
3229 void* JavaThread::popframe_preserved_args() {
3230 return _popframe_preserved_args;
3231 }
3232
3233 ByteSize JavaThread::popframe_preserved_args_size() {
3234 return in_ByteSize(_popframe_preserved_args_size);
3235 }
3236
3237 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3238 int sz = in_bytes(popframe_preserved_args_size());
3239 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3240 return in_WordSize(sz / wordSize);
3241 }
3242
3243 void JavaThread::popframe_free_preserved_args() {
3244 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3245 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3246 _popframe_preserved_args = NULL;
3247 _popframe_preserved_args_size = 0;
3248 }
3249
3250 #ifndef PRODUCT
3251
3252 void JavaThread::trace_frames() {
3253 tty->print_cr("[Describe stack]");
3254 int frame_no = 1;
3255 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3256 tty->print(" %d. ", frame_no++);
3257 fst.current()->print_value_on(tty, this);
3258 tty->cr();
3259 }
3260 }
3261
3262 class PrintAndVerifyOopClosure: public OopClosure {
3263 protected:
3264 template <class T> inline void do_oop_work(T* p) {
3265 oop obj = oopDesc::load_decode_heap_oop(p);
3266 if (obj == NULL) return;
3267 tty->print(INTPTR_FORMAT ": ", p2i(p));
3268 if (oopDesc::is_oop_or_null(obj)) {
3269 if (obj->is_objArray()) {
3270 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3271 } else {
3272 obj->print();
3273 }
3274 } else {
3275 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3276 }
3277 tty->cr();
3278 }
3279 public:
3280 virtual void do_oop(oop* p) { do_oop_work(p); }
3281 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3282 };
3283
3284
3285 static void oops_print(frame* f, const RegisterMap *map) {
3286 PrintAndVerifyOopClosure print;
3287 f->print_value();
3288 f->oops_do(&print, NULL, (RegisterMap*)map);
3289 }
3290
3291 // Print our all the locations that contain oops and whether they are
3292 // valid or not. This useful when trying to find the oldest frame
3293 // where an oop has gone bad since the frame walk is from youngest to
3294 // oldest.
3295 void JavaThread::trace_oops() {
3296 tty->print_cr("[Trace oops]");
3297 frames_do(oops_print);
3298 }
3299
3300
3301 #ifdef ASSERT
3302 // Print or validate the layout of stack frames
3303 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3304 ResourceMark rm;
3305 PRESERVE_EXCEPTION_MARK;
3306 FrameValues values;
3307 int frame_no = 0;
3308 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3309 fst.current()->describe(values, ++frame_no);
3310 if (depth == frame_no) break;
3311 }
3312 if (validate_only) {
3313 values.validate();
3314 } else {
3315 tty->print_cr("[Describe stack layout]");
3316 values.print(this);
3317 }
3318 }
3319 #endif
3320
3321 void JavaThread::trace_stack_from(vframe* start_vf) {
3322 ResourceMark rm;
3323 int vframe_no = 1;
3324 for (vframe* f = start_vf; f; f = f->sender()) {
3325 if (f->is_java_frame()) {
3326 javaVFrame::cast(f)->print_activation(vframe_no++);
3327 } else {
3328 f->print();
3329 }
3330 if (vframe_no > StackPrintLimit) {
3331 tty->print_cr("...<more frames>...");
3332 return;
3333 }
3334 }
3335 }
3336
3337
3338 void JavaThread::trace_stack() {
3339 if (!has_last_Java_frame()) return;
3340 ResourceMark rm;
3341 HandleMark hm;
3342 RegisterMap reg_map(this);
3343 trace_stack_from(last_java_vframe(®_map));
3344 }
3345
3346
3347 #endif // PRODUCT
3348
3349
3350 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3351 assert(reg_map != NULL, "a map must be given");
3352 frame f = last_frame();
3353 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3354 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3355 }
3356 return NULL;
3357 }
3358
3359
3360 Klass* JavaThread::security_get_caller_class(int depth) {
3361 vframeStream vfst(this);
3362 vfst.security_get_caller_frame(depth);
3363 if (!vfst.at_end()) {
3364 return vfst.method()->method_holder();
3365 }
3366 return NULL;
3367 }
3368
3369 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3370 assert(thread->is_Compiler_thread(), "must be compiler thread");
3371 CompileBroker::compiler_thread_loop();
3372 }
3373
3374 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3375 NMethodSweeper::sweeper_loop();
3376 }
3377
3378 // Create a CompilerThread
3379 CompilerThread::CompilerThread(CompileQueue* queue,
3380 CompilerCounters* counters)
3381 : JavaThread(&compiler_thread_entry) {
3382 _env = NULL;
3383 _log = NULL;
3384 _task = NULL;
3385 _queue = queue;
3386 _counters = counters;
3387 _buffer_blob = NULL;
3388 _compiler = NULL;
3389
3390 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3391 resource_area()->bias_to(mtCompiler);
3392
3393 #ifndef PRODUCT
3394 _ideal_graph_printer = NULL;
3395 #endif
3396 }
3397
3398 bool CompilerThread::can_call_java() const {
3399 return _compiler != NULL && _compiler->is_jvmci();
3400 }
3401
3402 // Create sweeper thread
3403 CodeCacheSweeperThread::CodeCacheSweeperThread()
3404 : JavaThread(&sweeper_thread_entry) {
3405 _scanned_compiled_method = NULL;
3406 }
3407
3408 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3409 JavaThread::oops_do(f, cf);
3410 if (_scanned_compiled_method != NULL && cf != NULL) {
3411 // Safepoints can occur when the sweeper is scanning an nmethod so
3412 // process it here to make sure it isn't unloaded in the middle of
3413 // a scan.
3414 cf->do_code_blob(_scanned_compiled_method);
3415 }
3416 }
3417
3418 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3419 JavaThread::nmethods_do(cf);
3420 if (_scanned_compiled_method != NULL && cf != NULL) {
3421 // Safepoints can occur when the sweeper is scanning an nmethod so
3422 // process it here to make sure it isn't unloaded in the middle of
3423 // a scan.
3424 cf->do_code_blob(_scanned_compiled_method);
3425 }
3426 }
3427
3428
3429 // ======= Threads ========
3430
3431 // The Threads class links together all active threads, and provides
3432 // operations over all threads. It is protected by the Threads_lock,
3433 // which is also used in other global contexts like safepointing.
3434 // ThreadsListHandles are used to safely perform operations on one
3435 // or more threads without the risk of the thread exiting during the
3436 // operation.
3437 //
3438 // Note: The Threads_lock is currently more widely used than we
3439 // would like. We are actively migrating Threads_lock uses to other
3440 // mechanisms in order to reduce Threads_lock contention.
3441
3442 JavaThread* Threads::_thread_list = NULL;
3443 int Threads::_number_of_threads = 0;
3444 int Threads::_number_of_non_daemon_threads = 0;
3445 int Threads::_return_code = 0;
3446 int Threads::_thread_claim_parity = 0;
3447 size_t JavaThread::_stack_size_at_create = 0;
3448 // Safe Memory Reclamation (SMR) support:
3449 Monitor* Threads::_smr_delete_lock =
3450 new Monitor(Monitor::special, "smr_delete_lock",
3451 false /* allow_vm_block */,
3452 Monitor::_safepoint_check_never);
3453 // The '_cnt', '_max' and '_times" fields are enabled via
3454 // -XX:+EnableThreadSMRStatistics:
3455
3456 // # of parallel threads in _smr_delete_lock->wait().
3457 // Impl note: Hard to imagine > 64K waiting threads so this could be 16-bit,
3458 // but there is no nice 16-bit _FORMAT support.
3459 uint Threads::_smr_delete_lock_wait_cnt = 0;
3460
3461 // Max # of parallel threads in _smr_delete_lock->wait().
3462 // Impl note: See _smr_delete_lock_wait_cnt note.
3463 uint Threads::_smr_delete_lock_wait_max = 0;
3464
3465 // Flag to indicate when an _smr_delete_lock->notify() is needed.
3466 // Impl note: See _smr_delete_lock_wait_cnt note.
3467 volatile uint Threads::_smr_delete_notify = 0;
3468
3469 // # of threads deleted over VM lifetime.
3470 // Impl note: Atomically incremented over VM lifetime so use unsigned for more
3471 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3472 // isn't available everywhere (or is it?).
3473 volatile uint Threads::_smr_deleted_thread_cnt = 0;
3474
3475 // Max time in millis to delete a thread.
3476 // Impl note: 16-bit might be too small on an overloaded machine. Use
3477 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3478 // loop for correctness.
3479 volatile uint Threads::_smr_deleted_thread_time_max = 0;
3480
3481 // Cumulative time in millis to delete threads.
3482 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3483 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3484 // isn't available everywhere (or is it?).
3485 volatile uint Threads::_smr_deleted_thread_times = 0;
3486
3487 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
3488
3489 // # of ThreadsLists allocated over VM lifetime.
3490 // Impl note: We allocate a new ThreadsList for every thread create and
3491 // every thread delete so we need a bigger type than the
3492 // _smr_deleted_thread_cnt field.
3493 uint64_t Threads::_smr_java_thread_list_alloc_cnt = 1;
3494
3495 // # of ThreadsLists freed over VM lifetime.
3496 // Impl note: See _smr_java_thread_list_alloc_cnt note.
3497 uint64_t Threads::_smr_java_thread_list_free_cnt = 0;
3498
3499 // Max size ThreadsList allocated.
3500 // Impl note: Max # of threads alive at one time should fit in unsigned 32-bit.
3501 uint Threads::_smr_java_thread_list_max = 0;
3502
3503 // Max # of nested ThreadsLists for a thread.
3504 // Impl note: Hard to imagine > 64K nested ThreadsLists so this could be
3505 // 16-bit, but there is no nice 16-bit _FORMAT support.
3506 uint Threads::_smr_nested_thread_list_max = 0;
3507
3508 // # of ThreadsListHandles deleted over VM lifetime.
3509 // Impl note: Atomically incremented over VM lifetime so use unsigned for
3510 // more range. There will be fewer ThreadsListHandles than threads so
3511 // unsigned 32-bit should be fine.
3512 volatile uint Threads::_smr_tlh_cnt = 0;
3513
3514 // Max time in millis to delete a ThreadsListHandle.
3515 // Impl note: 16-bit might be too small on an overloaded machine. Use
3516 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a
3517 // loop for correctness.
3518 volatile uint Threads::_smr_tlh_time_max = 0;
3519
3520 // Cumulative time in millis to delete ThreadsListHandles.
3521 // Impl note: Atomically added to over VM lifetime so use unsigned for more
3522 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc
3523 // isn't available everywhere (or is it?).
3524 volatile uint Threads::_smr_tlh_times = 0;
3525
3526 ThreadsList* Threads::_smr_to_delete_list = NULL;
3527
3528 // # of parallel ThreadsLists on the to-delete list.
3529 // Impl note: Hard to imagine > 64K ThreadsLists needing to be deleted so
3530 // this could be 16-bit, but there is no nice 16-bit _FORMAT support.
3531 uint Threads::_smr_to_delete_list_cnt = 0;
3532
3533 // Max # of parallel ThreadsLists on the to-delete list.
3534 // Impl note: See _smr_to_delete_list_cnt note.
3535 uint Threads::_smr_to_delete_list_max = 0;
3536
3537 #ifdef ASSERT
3538 bool Threads::_vm_complete = false;
3539 #endif
3540
3541 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3542 Prefetch::read((void*)addr, prefetch_interval);
3543 return *addr;
3544 }
3545
3546 // Possibly the ugliest for loop the world has seen. C++ does not allow
3547 // multiple types in the declaration section of the for loop. In this case
3548 // we are only dealing with pointers and hence can cast them. It looks ugly
3549 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3550 #define DO_JAVA_THREADS(LIST, X) \
3551 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3552 *MACRO_list = (JavaThread*)(LIST), \
3553 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3554 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3555 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3556 MACRO_current_p != MACRO_end; \
3557 MACRO_current_p++, \
3558 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3559
3560 // All JavaThreads
3561 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X)
3562
3563 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3564 void Threads::threads_do(ThreadClosure* tc) {
3565 assert_locked_or_safepoint(Threads_lock);
3566 // ALL_JAVA_THREADS iterates through all JavaThreads
3567 ALL_JAVA_THREADS(p) {
3568 tc->do_thread(p);
3569 }
3570 // Someday we could have a table or list of all non-JavaThreads.
3571 // For now, just manually iterate through them.
3572 tc->do_thread(VMThread::vm_thread());
3573 Universe::heap()->gc_threads_do(tc);
3574 WatcherThread *wt = WatcherThread::watcher_thread();
3575 // Strictly speaking, the following NULL check isn't sufficient to make sure
3576 // the data for WatcherThread is still valid upon being examined. However,
3577 // considering that WatchThread terminates when the VM is on the way to
3578 // exit at safepoint, the chance of the above is extremely small. The right
3579 // way to prevent termination of WatcherThread would be to acquire
3580 // Terminator_lock, but we can't do that without violating the lock rank
3581 // checking in some cases.
3582 if (wt != NULL) {
3583 tc->do_thread(wt);
3584 }
3585
3586 // If CompilerThreads ever become non-JavaThreads, add them here
3587 }
3588
3589 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3590 int cp = Threads::thread_claim_parity();
3591 ALL_JAVA_THREADS(p) {
3592 if (p->claim_oops_do(is_par, cp)) {
3593 tc->do_thread(p);
3594 }
3595 }
3596 VMThread* vmt = VMThread::vm_thread();
3597 if (vmt->claim_oops_do(is_par, cp)) {
3598 tc->do_thread(vmt);
3599 }
3600 }
3601
3602 // The system initialization in the library has three phases.
3603 //
3604 // Phase 1: java.lang.System class initialization
3605 // java.lang.System is a primordial class loaded and initialized
3606 // by the VM early during startup. java.lang.System.<clinit>
3607 // only does registerNatives and keeps the rest of the class
3608 // initialization work later until thread initialization completes.
3609 //
3610 // System.initPhase1 initializes the system properties, the static
3611 // fields in, out, and err. Set up java signal handlers, OS-specific
3612 // system settings, and thread group of the main thread.
3613 static void call_initPhase1(TRAPS) {
3614 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3615 JavaValue result(T_VOID);
3616 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3617 vmSymbols::void_method_signature(), CHECK);
3618 }
3619
3620 // Phase 2. Module system initialization
3621 // This will initialize the module system. Only java.base classes
3622 // can be loaded until phase 2 completes.
3623 //
3624 // Call System.initPhase2 after the compiler initialization and jsr292
3625 // classes get initialized because module initialization runs a lot of java
3626 // code, that for performance reasons, should be compiled. Also, this will
3627 // enable the startup code to use lambda and other language features in this
3628 // phase and onward.
3629 //
3630 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3631 static void call_initPhase2(TRAPS) {
3632 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3633
3634 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3635
3636 JavaValue result(T_INT);
3637 JavaCallArguments args;
3638 args.push_int(DisplayVMOutputToStderr);
3639 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3640 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3641 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3642 if (result.get_jint() != JNI_OK) {
3643 vm_exit_during_initialization(); // no message or exception
3644 }
3645
3646 universe_post_module_init();
3647 }
3648
3649 // Phase 3. final setup - set security manager, system class loader and TCCL
3650 //
3651 // This will instantiate and set the security manager, set the system class
3652 // loader as well as the thread context class loader. The security manager
3653 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3654 // other modules or the application's classpath.
3655 static void call_initPhase3(TRAPS) {
3656 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3657 JavaValue result(T_VOID);
3658 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3659 vmSymbols::void_method_signature(), CHECK);
3660 }
3661
3662 // Safe Memory Reclamation (SMR) support:
3663 //
3664
3665 // Acquire a stable ThreadsList.
3666 //
3667 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) {
3668 assert(self != NULL, "sanity check");
3669 // acquire_stable_list_nested_path() will grab the Threads_lock
3670 // so let's make sure the ThreadsListHandle is in a safe place.
3671 // ThreadsListSetter cannot make this check on this code path.
3672 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3673
3674 if (self->get_threads_hazard_ptr() == NULL) {
3675 // The typical case is first.
3676 return acquire_stable_list_fast_path(self);
3677 }
3678
3679 // The nested case is rare.
3680 return acquire_stable_list_nested_path(self);
3681 }
3682
3683 // Fast path (and lock free) way to acquire a stable ThreadsList.
3684 //
3685 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) {
3686 assert(self != NULL, "sanity check");
3687 assert(self->get_threads_hazard_ptr() == NULL, "sanity check");
3688 assert(self->get_nested_threads_hazard_ptr() == NULL,
3689 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
3690
3691 ThreadsList* threads;
3692
3693 // Stable recording of a hazard ptr for SMR. This code does not use
3694 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr
3695 // fields is racy relative to code that uses those fields with locks.
3696 // OrderAccess and Atomic functions are used to deal with those races.
3697 //
3698 while (true) {
3699 threads = get_smr_java_thread_list();
3700
3701 // Publish a tagged hazard ptr to denote that the hazard ptr is not
3702 // yet verified as being stable. Due to the fence after the hazard
3703 // ptr write, it will be sequentially consistent w.r.t. the
3704 // sequentially consistent writes of the ThreadsList, even on
3705 // non-multiple copy atomic machines where stores can be observed
3706 // in different order from different observer threads.
3707 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads);
3708 self->set_threads_hazard_ptr(unverified_threads);
3709
3710 // If _smr_java_thread_list has changed, we have lost a race with
3711 // Threads::add() or Threads::remove() and have to try again.
3712 if (get_smr_java_thread_list() != threads) {
3713 continue;
3714 }
3715
3716 // We try to remove the tag which will verify the hazard ptr as
3717 // being stable. This exchange can race with a scanning thread
3718 // which might invalidate the tagged hazard ptr to keep it from
3719 // being followed to access JavaThread ptrs. If we lose the race,
3720 // we simply retry. If we win the race, then the stable hazard
3721 // ptr is officially published.
3722 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) {
3723 break;
3724 }
3725 }
3726
3727 // A stable hazard ptr has been published letting other threads know
3728 // that the ThreadsList and the JavaThreads reachable from this list
3729 // are protected and hence they should not be deleted until everyone
3730 // agrees it is safe to do so.
3731
3732 return threads;
3733 }
3734
3735 // Acquire a nested stable ThreadsList; this is rare so it uses
3736 // Threads_lock.
3737 //
3738 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) {
3739 assert(self != NULL, "sanity check");
3740 assert(self->get_threads_hazard_ptr() != NULL,
3741 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr");
3742
3743 // The thread already has a hazard ptr (ThreadsList ref) so we need
3744 // to create a nested ThreadsListHandle with the current ThreadsList
3745 // since it might be different than our current hazard ptr. The need
3746 // for a nested ThreadsListHandle is rare so we do this while holding
3747 // the Threads_lock so we don't race with the scanning code; the code
3748 // is so much simpler this way.
3749
3750 NestedThreadsList* node;
3751 {
3752 // Only grab the Threads_lock if we don't already own it.
3753 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3754 node = new NestedThreadsList(get_smr_java_thread_list());
3755 // We insert at the front of the list to match up with the delete
3756 // in release_stable_list().
3757 node->set_next(self->get_nested_threads_hazard_ptr());
3758 self->set_nested_threads_hazard_ptr(node);
3759 if (EnableThreadSMRStatistics) {
3760 self->inc_nested_threads_hazard_ptr_cnt();
3761 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) {
3762 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt();
3763 }
3764 }
3765 }
3766 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3767
3768 return node->t_list();
3769 }
3770
3771 // Release a stable ThreadsList.
3772 //
3773 void Threads::release_stable_list(Thread *self) {
3774 assert(self != NULL, "sanity check");
3775 // release_stable_list_nested_path() will grab the Threads_lock
3776 // so let's make sure the ThreadsListHandle is in a safe place.
3777 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3778
3779 if (self->get_nested_threads_hazard_ptr() == NULL) {
3780 // The typical case is first.
3781 release_stable_list_fast_path(self);
3782 return;
3783 }
3784
3785 // The nested case is rare.
3786 release_stable_list_nested_path(self);
3787 }
3788
3789 // Fast path way to release a stable ThreadsList. The release portion
3790 // is lock-free, but the wake up portion is not.
3791 //
3792 void Threads::release_stable_list_fast_path(Thread *self) {
3793 assert(self != NULL, "sanity check");
3794 assert(self->get_threads_hazard_ptr() != NULL, "sanity check");
3795 assert(self->get_nested_threads_hazard_ptr() == NULL,
3796 "cannot have a nested hazard ptr when releasing a regular hazard ptr");
3797
3798 // After releasing the hazard ptr, other threads may go ahead and
3799 // free up some memory temporarily used by a ThreadsList snapshot.
3800 self->set_threads_hazard_ptr(NULL);
3801
3802 // We use double-check locking to reduce traffic on the system
3803 // wide smr_delete_lock.
3804 if (Threads::smr_delete_notify()) {
3805 // An exiting thread might be waiting in smr_delete(); we need to
3806 // check with smr_delete_lock to be sure.
3807 release_stable_list_wake_up((char *) "regular hazard ptr");
3808 }
3809 }
3810
3811 // Release a nested stable ThreadsList; this is rare so it uses
3812 // Threads_lock.
3813 //
3814 void Threads::release_stable_list_nested_path(Thread *self) {
3815 assert(self != NULL, "sanity check");
3816 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check");
3817 assert(self->get_threads_hazard_ptr() != NULL,
3818 "must have a regular hazard ptr to have nested hazard ptrs");
3819
3820 // We have a nested ThreadsListHandle so we have to release it first.
3821 // The need for a nested ThreadsListHandle is rare so we do this while
3822 // holding the Threads_lock so we don't race with the scanning code;
3823 // the code is so much simpler this way.
3824
3825 NestedThreadsList *node;
3826 {
3827 // Only grab the Threads_lock if we don't already own it.
3828 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3829 // We remove from the front of the list to match up with the insert
3830 // in acquire_stable_list().
3831 node = self->get_nested_threads_hazard_ptr();
3832 self->set_nested_threads_hazard_ptr(node->next());
3833 if (EnableThreadSMRStatistics) {
3834 self->dec_nested_threads_hazard_ptr_cnt();
3835 }
3836 }
3837
3838 // An exiting thread might be waiting in smr_delete(); we need to
3839 // check with smr_delete_lock to be sure.
3840 release_stable_list_wake_up((char *) "nested hazard ptr");
3841
3842 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list()));
3843
3844 delete node;
3845 }
3846
3847 // Wake up portion of the release stable ThreadsList protocol;
3848 // uses the smr_delete_lock().
3849 //
3850 void Threads::release_stable_list_wake_up(char *log_str) {
3851 assert(log_str != NULL, "sanity check");
3852
3853 // Note: smr_delete_lock is held in smr_delete() for the entire
3854 // hazard ptr search so that we do not lose this notify() if
3855 // the exiting thread has to wait. That code path also holds
3856 // Threads_lock (which was grabbed before smr_delete_lock) so that
3857 // threads_do() can be called. This means the system can't start a
3858 // safepoint which means this thread can't take too long to get to
3859 // a safepoint because of being blocked on smr_delete_lock.
3860 //
3861 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag);
3862 if (Threads::smr_delete_notify()) {
3863 // Notify any exiting JavaThreads that are waiting in smr_delete()
3864 // that we've released a ThreadsList.
3865 ml.notify_all();
3866 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str);
3867 }
3868 }
3869
3870 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3871 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3872
3873 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3874 create_vm_init_libraries();
3875 }
3876
3877 initialize_class(vmSymbols::java_lang_String(), CHECK);
3878
3879 // Inject CompactStrings value after the static initializers for String ran.
3880 java_lang_String::set_compact_strings(CompactStrings);
3881
3882 // Initialize java_lang.System (needed before creating the thread)
3883 initialize_class(vmSymbols::java_lang_System(), CHECK);
3884 // The VM creates & returns objects of this class. Make sure it's initialized.
3885 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3886 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3887 Handle thread_group = create_initial_thread_group(CHECK);
3888 Universe::set_main_thread_group(thread_group());
3889 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3890 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3891 main_thread->set_threadObj(thread_object);
3892 // Set thread status to running since main thread has
3893 // been started and running.
3894 java_lang_Thread::set_thread_status(thread_object,
3895 java_lang_Thread::RUNNABLE);
3896
3897 // The VM creates objects of this class.
3898 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3899
3900 // The VM preresolves methods to these classes. Make sure that they get initialized
3901 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3902 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3903
3904 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3905 call_initPhase1(CHECK);
3906
3907 // get the Java runtime name after java.lang.System is initialized
3908 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3909 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3910
3911 // an instance of OutOfMemory exception has been allocated earlier
3912 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3913 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3914 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3915 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3916 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3917 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3918 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3919 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3920 }
3921
3922 void Threads::initialize_jsr292_core_classes(TRAPS) {
3923 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3924
3925 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3926 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3927 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3928 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3929 }
3930
3931 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3932 extern void JDK_Version_init();
3933
3934 // Preinitialize version info.
3935 VM_Version::early_initialize();
3936
3937 // Check version
3938 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3939
3940 // Initialize library-based TLS
3941 ThreadLocalStorage::init();
3942
3943 // Initialize the output stream module
3944 ostream_init();
3945
3946 // Process java launcher properties.
3947 Arguments::process_sun_java_launcher_properties(args);
3948
3949 // Initialize the os module
3950 os::init();
3951
3952 // Record VM creation timing statistics
3953 TraceVmCreationTime create_vm_timer;
3954 create_vm_timer.start();
3955
3956 // Initialize system properties.
3957 Arguments::init_system_properties();
3958
3959 // So that JDK version can be used as a discriminator when parsing arguments
3960 JDK_Version_init();
3961
3962 // Update/Initialize System properties after JDK version number is known
3963 Arguments::init_version_specific_system_properties();
3964
3965 // Make sure to initialize log configuration *before* parsing arguments
3966 LogConfiguration::initialize(create_vm_timer.begin_time());
3967
3968 // Parse arguments
3969 // Note: this internally calls os::init_container_support()
3970 jint parse_result = Arguments::parse(args);
3971 if (parse_result != JNI_OK) return parse_result;
3972
3973 os::init_before_ergo();
3974
3975 jint ergo_result = Arguments::apply_ergo();
3976 if (ergo_result != JNI_OK) return ergo_result;
3977
3978 // Final check of all ranges after ergonomics which may change values.
3979 if (!CommandLineFlagRangeList::check_ranges()) {
3980 return JNI_EINVAL;
3981 }
3982
3983 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3984 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3985 if (!constraint_result) {
3986 return JNI_EINVAL;
3987 }
3988
3989 CommandLineFlagWriteableList::mark_startup();
3990
3991 if (PauseAtStartup) {
3992 os::pause();
3993 }
3994
3995 HOTSPOT_VM_INIT_BEGIN();
3996
3997 // Timing (must come after argument parsing)
3998 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3999
4000 SafepointMechanism::initialize();
4001
4002 // Initialize the os module after parsing the args
4003 jint os_init_2_result = os::init_2();
4004 if (os_init_2_result != JNI_OK) return os_init_2_result;
4005
4006 jint adjust_after_os_result = Arguments::adjust_after_os();
4007 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
4008
4009 // Initialize output stream logging
4010 ostream_init_log();
4011
4012 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
4013 // Must be before create_vm_init_agents()
4014 if (Arguments::init_libraries_at_startup()) {
4015 convert_vm_init_libraries_to_agents();
4016 }
4017
4018 // Launch -agentlib/-agentpath and converted -Xrun agents
4019 if (Arguments::init_agents_at_startup()) {
4020 create_vm_init_agents();
4021 }
4022
4023 // Initialize Threads state
4024 _thread_list = NULL;
4025 _number_of_threads = 0;
4026 _number_of_non_daemon_threads = 0;
4027
4028 // Initialize global data structures and create system classes in heap
4029 vm_init_globals();
4030
4031 #if INCLUDE_JVMCI
4032 if (JVMCICounterSize > 0) {
4033 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
4034 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
4035 } else {
4036 JavaThread::_jvmci_old_thread_counters = NULL;
4037 }
4038 #endif // INCLUDE_JVMCI
4039
4040 // Attach the main thread to this os thread
4041 JavaThread* main_thread = new JavaThread();
4042 main_thread->set_thread_state(_thread_in_vm);
4043 main_thread->initialize_thread_current();
4044 // must do this before set_active_handles
4045 main_thread->record_stack_base_and_size();
4046 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
4047
4048 if (!main_thread->set_as_starting_thread()) {
4049 vm_shutdown_during_initialization(
4050 "Failed necessary internal allocation. Out of swap space");
4051 main_thread->smr_delete();
4052 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4053 return JNI_ENOMEM;
4054 }
4055
4056 // Enable guard page *after* os::create_main_thread(), otherwise it would
4057 // crash Linux VM, see notes in os_linux.cpp.
4058 main_thread->create_stack_guard_pages();
4059
4060 // Initialize Java-Level synchronization subsystem
4061 ObjectMonitor::Initialize();
4062
4063 // Initialize global modules
4064 jint status = init_globals();
4065 if (status != JNI_OK) {
4066 main_thread->smr_delete();
4067 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4068 return status;
4069 }
4070
4071 if (TRACE_INITIALIZE() != JNI_OK) {
4072 vm_exit_during_initialization("Failed to initialize tracing backend");
4073 }
4074
4075 // Should be done after the heap is fully created
4076 main_thread->cache_global_variables();
4077
4078 HandleMark hm;
4079
4080 { MutexLocker mu(Threads_lock);
4081 Threads::add(main_thread);
4082 }
4083
4084 // Any JVMTI raw monitors entered in onload will transition into
4085 // real raw monitor. VM is setup enough here for raw monitor enter.
4086 JvmtiExport::transition_pending_onload_raw_monitors();
4087
4088 // Create the VMThread
4089 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
4090
4091 VMThread::create();
4092 Thread* vmthread = VMThread::vm_thread();
4093
4094 if (!os::create_thread(vmthread, os::vm_thread)) {
4095 vm_exit_during_initialization("Cannot create VM thread. "
4096 "Out of system resources.");
4097 }
4098
4099 // Wait for the VM thread to become ready, and VMThread::run to initialize
4100 // Monitors can have spurious returns, must always check another state flag
4101 {
4102 MutexLocker ml(Notify_lock);
4103 os::start_thread(vmthread);
4104 while (vmthread->active_handles() == NULL) {
4105 Notify_lock->wait();
4106 }
4107 }
4108 }
4109
4110 assert(Universe::is_fully_initialized(), "not initialized");
4111 if (VerifyDuringStartup) {
4112 // Make sure we're starting with a clean slate.
4113 VM_Verify verify_op;
4114 VMThread::execute(&verify_op);
4115 }
4116
4117 Thread* THREAD = Thread::current();
4118
4119 // Always call even when there are not JVMTI environments yet, since environments
4120 // may be attached late and JVMTI must track phases of VM execution
4121 JvmtiExport::enter_early_start_phase();
4122
4123 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4124 JvmtiExport::post_early_vm_start();
4125
4126 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4127
4128 // We need this for ClassDataSharing - the initial vm.info property is set
4129 // with the default value of CDS "sharing" which may be reset through
4130 // command line options.
4131 reset_vm_info_property(CHECK_JNI_ERR);
4132
4133 quicken_jni_functions();
4134
4135 // No more stub generation allowed after that point.
4136 StubCodeDesc::freeze();
4137
4138 // Set flag that basic initialization has completed. Used by exceptions and various
4139 // debug stuff, that does not work until all basic classes have been initialized.
4140 set_init_completed();
4141
4142 LogConfiguration::post_initialize();
4143 Metaspace::post_initialize();
4144
4145 HOTSPOT_VM_INIT_END();
4146
4147 // record VM initialization completion time
4148 #if INCLUDE_MANAGEMENT
4149 Management::record_vm_init_completed();
4150 #endif // INCLUDE_MANAGEMENT
4151
4152 // Signal Dispatcher needs to be started before VMInit event is posted
4153 os::signal_init(CHECK_JNI_ERR);
4154
4155 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4156 if (!DisableAttachMechanism) {
4157 AttachListener::vm_start();
4158 if (StartAttachListener || AttachListener::init_at_startup()) {
4159 AttachListener::init();
4160 }
4161 }
4162
4163 // Launch -Xrun agents
4164 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4165 // back-end can launch with -Xdebug -Xrunjdwp.
4166 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4167 create_vm_init_libraries();
4168 }
4169
4170 if (CleanChunkPoolAsync) {
4171 Chunk::start_chunk_pool_cleaner_task();
4172 }
4173
4174 // initialize compiler(s)
4175 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4176 CompileBroker::compilation_init(CHECK_JNI_ERR);
4177 #endif
4178
4179 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4180 // It is done after compilers are initialized, because otherwise compilations of
4181 // signature polymorphic MH intrinsics can be missed
4182 // (see SystemDictionary::find_method_handle_intrinsic).
4183 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4184
4185 // This will initialize the module system. Only java.base classes can be
4186 // loaded until phase 2 completes
4187 call_initPhase2(CHECK_JNI_ERR);
4188
4189 // Always call even when there are not JVMTI environments yet, since environments
4190 // may be attached late and JVMTI must track phases of VM execution
4191 JvmtiExport::enter_start_phase();
4192
4193 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4194 JvmtiExport::post_vm_start();
4195
4196 // Final system initialization including security manager and system class loader
4197 call_initPhase3(CHECK_JNI_ERR);
4198
4199 // cache the system and platform class loaders
4200 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4201
4202 #if INCLUDE_JVMCI
4203 if (EnableJVMCI) {
4204 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
4205 // The JVMCI Java initialization code will read this flag and
4206 // do the printing if it's set.
4207 bool init = JVMCIPrintProperties;
4208
4209 if (!init) {
4210 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4211 // compilations via JVMCI will not actually block until JVMCI is initialized.
4212 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4213 }
4214
4215 if (init) {
4216 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
4217 }
4218 }
4219 #endif
4220
4221 // Always call even when there are not JVMTI environments yet, since environments
4222 // may be attached late and JVMTI must track phases of VM execution
4223 JvmtiExport::enter_live_phase();
4224
4225 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4226 JvmtiExport::post_vm_initialized();
4227
4228 if (TRACE_START() != JNI_OK) {
4229 vm_exit_during_initialization("Failed to start tracing backend.");
4230 }
4231
4232 #if INCLUDE_MANAGEMENT
4233 Management::initialize(THREAD);
4234
4235 if (HAS_PENDING_EXCEPTION) {
4236 // management agent fails to start possibly due to
4237 // configuration problem and is responsible for printing
4238 // stack trace if appropriate. Simply exit VM.
4239 vm_exit(1);
4240 }
4241 #endif // INCLUDE_MANAGEMENT
4242
4243 if (MemProfiling) MemProfiler::engage();
4244 StatSampler::engage();
4245 if (CheckJNICalls) JniPeriodicChecker::engage();
4246
4247 BiasedLocking::init();
4248
4249 #if INCLUDE_RTM_OPT
4250 RTMLockingCounters::init();
4251 #endif
4252
4253 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4254 call_postVMInitHook(THREAD);
4255 // The Java side of PostVMInitHook.run must deal with all
4256 // exceptions and provide means of diagnosis.
4257 if (HAS_PENDING_EXCEPTION) {
4258 CLEAR_PENDING_EXCEPTION;
4259 }
4260 }
4261
4262 {
4263 MutexLocker ml(PeriodicTask_lock);
4264 // Make sure the WatcherThread can be started by WatcherThread::start()
4265 // or by dynamic enrollment.
4266 WatcherThread::make_startable();
4267 // Start up the WatcherThread if there are any periodic tasks
4268 // NOTE: All PeriodicTasks should be registered by now. If they
4269 // aren't, late joiners might appear to start slowly (we might
4270 // take a while to process their first tick).
4271 if (PeriodicTask::num_tasks() > 0) {
4272 WatcherThread::start();
4273 }
4274 }
4275
4276 create_vm_timer.end();
4277 #ifdef ASSERT
4278 _vm_complete = true;
4279 #endif
4280
4281 if (DumpSharedSpaces) {
4282 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4283 ShouldNotReachHere();
4284 }
4285
4286 return JNI_OK;
4287 }
4288
4289 // type for the Agent_OnLoad and JVM_OnLoad entry points
4290 extern "C" {
4291 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4292 }
4293 // Find a command line agent library and return its entry point for
4294 // -agentlib: -agentpath: -Xrun
4295 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4296 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4297 const char *on_load_symbols[],
4298 size_t num_symbol_entries) {
4299 OnLoadEntry_t on_load_entry = NULL;
4300 void *library = NULL;
4301
4302 if (!agent->valid()) {
4303 char buffer[JVM_MAXPATHLEN];
4304 char ebuf[1024] = "";
4305 const char *name = agent->name();
4306 const char *msg = "Could not find agent library ";
4307
4308 // First check to see if agent is statically linked into executable
4309 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4310 library = agent->os_lib();
4311 } else if (agent->is_absolute_path()) {
4312 library = os::dll_load(name, ebuf, sizeof ebuf);
4313 if (library == NULL) {
4314 const char *sub_msg = " in absolute path, with error: ";
4315 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4316 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4317 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4318 // If we can't find the agent, exit.
4319 vm_exit_during_initialization(buf, NULL);
4320 FREE_C_HEAP_ARRAY(char, buf);
4321 }
4322 } else {
4323 // Try to load the agent from the standard dll directory
4324 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4325 name)) {
4326 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4327 }
4328 if (library == NULL) { // Try the library path directory.
4329 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4330 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4331 }
4332 if (library == NULL) {
4333 const char *sub_msg = " on the library path, with error: ";
4334 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4335 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4336 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4337 // If we can't find the agent, exit.
4338 vm_exit_during_initialization(buf, NULL);
4339 FREE_C_HEAP_ARRAY(char, buf);
4340 }
4341 }
4342 }
4343 agent->set_os_lib(library);
4344 agent->set_valid();
4345 }
4346
4347 // Find the OnLoad function.
4348 on_load_entry =
4349 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4350 false,
4351 on_load_symbols,
4352 num_symbol_entries));
4353 return on_load_entry;
4354 }
4355
4356 // Find the JVM_OnLoad entry point
4357 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4358 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4359 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4360 }
4361
4362 // Find the Agent_OnLoad entry point
4363 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4364 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4365 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4366 }
4367
4368 // For backwards compatibility with -Xrun
4369 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4370 // treated like -agentpath:
4371 // Must be called before agent libraries are created
4372 void Threads::convert_vm_init_libraries_to_agents() {
4373 AgentLibrary* agent;
4374 AgentLibrary* next;
4375
4376 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4377 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4378 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4379
4380 // If there is an JVM_OnLoad function it will get called later,
4381 // otherwise see if there is an Agent_OnLoad
4382 if (on_load_entry == NULL) {
4383 on_load_entry = lookup_agent_on_load(agent);
4384 if (on_load_entry != NULL) {
4385 // switch it to the agent list -- so that Agent_OnLoad will be called,
4386 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4387 Arguments::convert_library_to_agent(agent);
4388 } else {
4389 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4390 }
4391 }
4392 }
4393 }
4394
4395 // Create agents for -agentlib: -agentpath: and converted -Xrun
4396 // Invokes Agent_OnLoad
4397 // Called very early -- before JavaThreads exist
4398 void Threads::create_vm_init_agents() {
4399 extern struct JavaVM_ main_vm;
4400 AgentLibrary* agent;
4401
4402 JvmtiExport::enter_onload_phase();
4403
4404 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4405 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4406
4407 if (on_load_entry != NULL) {
4408 // Invoke the Agent_OnLoad function
4409 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4410 if (err != JNI_OK) {
4411 vm_exit_during_initialization("agent library failed to init", agent->name());
4412 }
4413 } else {
4414 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4415 }
4416 }
4417 JvmtiExport::enter_primordial_phase();
4418 }
4419
4420 extern "C" {
4421 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4422 }
4423
4424 void Threads::shutdown_vm_agents() {
4425 // Send any Agent_OnUnload notifications
4426 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4427 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4428 extern struct JavaVM_ main_vm;
4429 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4430
4431 // Find the Agent_OnUnload function.
4432 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4433 os::find_agent_function(agent,
4434 false,
4435 on_unload_symbols,
4436 num_symbol_entries));
4437
4438 // Invoke the Agent_OnUnload function
4439 if (unload_entry != NULL) {
4440 JavaThread* thread = JavaThread::current();
4441 ThreadToNativeFromVM ttn(thread);
4442 HandleMark hm(thread);
4443 (*unload_entry)(&main_vm);
4444 }
4445 }
4446 }
4447
4448 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4449 // Invokes JVM_OnLoad
4450 void Threads::create_vm_init_libraries() {
4451 extern struct JavaVM_ main_vm;
4452 AgentLibrary* agent;
4453
4454 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4455 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4456
4457 if (on_load_entry != NULL) {
4458 // Invoke the JVM_OnLoad function
4459 JavaThread* thread = JavaThread::current();
4460 ThreadToNativeFromVM ttn(thread);
4461 HandleMark hm(thread);
4462 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4463 if (err != JNI_OK) {
4464 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4465 }
4466 } else {
4467 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4468 }
4469 }
4470 }
4471
4472
4473 // Last thread running calls java.lang.Shutdown.shutdown()
4474 void JavaThread::invoke_shutdown_hooks() {
4475 HandleMark hm(this);
4476
4477 // We could get here with a pending exception, if so clear it now.
4478 if (this->has_pending_exception()) {
4479 this->clear_pending_exception();
4480 }
4481
4482 EXCEPTION_MARK;
4483 Klass* shutdown_klass =
4484 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4485 THREAD);
4486 if (shutdown_klass != NULL) {
4487 // SystemDictionary::resolve_or_null will return null if there was
4488 // an exception. If we cannot load the Shutdown class, just don't
4489 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4490 // and finalizers (if runFinalizersOnExit is set) won't be run.
4491 // Note that if a shutdown hook was registered or runFinalizersOnExit
4492 // was called, the Shutdown class would have already been loaded
4493 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4494 JavaValue result(T_VOID);
4495 JavaCalls::call_static(&result,
4496 shutdown_klass,
4497 vmSymbols::shutdown_method_name(),
4498 vmSymbols::void_method_signature(),
4499 THREAD);
4500 }
4501 CLEAR_PENDING_EXCEPTION;
4502 }
4503
4504 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4505 // the program falls off the end of main(). Another VM exit path is through
4506 // vm_exit() when the program calls System.exit() to return a value or when
4507 // there is a serious error in VM. The two shutdown paths are not exactly
4508 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4509 // and VM_Exit op at VM level.
4510 //
4511 // Shutdown sequence:
4512 // + Shutdown native memory tracking if it is on
4513 // + Wait until we are the last non-daemon thread to execute
4514 // <-- every thing is still working at this moment -->
4515 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4516 // shutdown hooks, run finalizers if finalization-on-exit
4517 // + Call before_exit(), prepare for VM exit
4518 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4519 // currently the only user of this mechanism is File.deleteOnExit())
4520 // > stop StatSampler, watcher thread, CMS threads,
4521 // post thread end and vm death events to JVMTI,
4522 // stop signal thread
4523 // + Call JavaThread::exit(), it will:
4524 // > release JNI handle blocks, remove stack guard pages
4525 // > remove this thread from Threads list
4526 // <-- no more Java code from this thread after this point -->
4527 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4528 // the compiler threads at safepoint
4529 // <-- do not use anything that could get blocked by Safepoint -->
4530 // + Disable tracing at JNI/JVM barriers
4531 // + Set _vm_exited flag for threads that are still running native code
4532 // + Delete this thread
4533 // + Call exit_globals()
4534 // > deletes tty
4535 // > deletes PerfMemory resources
4536 // + Return to caller
4537
4538 bool Threads::destroy_vm() {
4539 JavaThread* thread = JavaThread::current();
4540
4541 #ifdef ASSERT
4542 _vm_complete = false;
4543 #endif
4544 // Wait until we are the last non-daemon thread to execute
4545 { MutexLocker nu(Threads_lock);
4546 while (Threads::number_of_non_daemon_threads() > 1)
4547 // This wait should make safepoint checks, wait without a timeout,
4548 // and wait as a suspend-equivalent condition.
4549 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4550 Mutex::_as_suspend_equivalent_flag);
4551 }
4552
4553 // Hang forever on exit if we are reporting an error.
4554 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4555 os::infinite_sleep();
4556 }
4557 os::wait_for_keypress_at_exit();
4558
4559 // run Java level shutdown hooks
4560 thread->invoke_shutdown_hooks();
4561
4562 before_exit(thread);
4563
4564 thread->exit(true);
4565
4566 // Stop VM thread.
4567 {
4568 // 4945125 The vm thread comes to a safepoint during exit.
4569 // GC vm_operations can get caught at the safepoint, and the
4570 // heap is unparseable if they are caught. Grab the Heap_lock
4571 // to prevent this. The GC vm_operations will not be able to
4572 // queue until after the vm thread is dead. After this point,
4573 // we'll never emerge out of the safepoint before the VM exits.
4574
4575 MutexLocker ml(Heap_lock);
4576
4577 VMThread::wait_for_vm_thread_exit();
4578 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4579 VMThread::destroy();
4580 }
4581
4582 // clean up ideal graph printers
4583 #if defined(COMPILER2) && !defined(PRODUCT)
4584 IdealGraphPrinter::clean_up();
4585 #endif
4586
4587 // Now, all Java threads are gone except daemon threads. Daemon threads
4588 // running Java code or in VM are stopped by the Safepoint. However,
4589 // daemon threads executing native code are still running. But they
4590 // will be stopped at native=>Java/VM barriers. Note that we can't
4591 // simply kill or suspend them, as it is inherently deadlock-prone.
4592
4593 VM_Exit::set_vm_exited();
4594
4595 notify_vm_shutdown();
4596
4597 // We are after VM_Exit::set_vm_exited() so we can't call
4598 // thread->smr_delete() or we will block on the Threads_lock.
4599 // Deleting the shutdown thread here is safe because another
4600 // JavaThread cannot have an active ThreadsListHandle for
4601 // this JavaThread.
4602 delete thread;
4603
4604 #if INCLUDE_JVMCI
4605 if (JVMCICounterSize > 0) {
4606 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4607 }
4608 #endif
4609
4610 // exit_globals() will delete tty
4611 exit_globals();
4612
4613 LogConfiguration::finalize();
4614
4615 return true;
4616 }
4617
4618
4619 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4620 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4621 return is_supported_jni_version(version);
4622 }
4623
4624
4625 jboolean Threads::is_supported_jni_version(jint version) {
4626 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4627 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4628 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4629 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4630 if (version == JNI_VERSION_9) return JNI_TRUE;
4631 if (version == JNI_VERSION_10) return JNI_TRUE;
4632 return JNI_FALSE;
4633 }
4634
4635 // Hash table of pointers found by a scan. Used for collecting hazard
4636 // pointers (ThreadsList references). Also used for collecting JavaThreads
4637 // that are indirectly referenced by hazard ptrs. An instance of this
4638 // class only contains one type of pointer.
4639 //
4640 class ThreadScanHashtable : public CHeapObj<mtThread> {
4641 private:
4642 static bool ptr_equals(void * const& s1, void * const& s2) {
4643 return s1 == s2;
4644 }
4645
4646 static unsigned int ptr_hash(void * const& s1) {
4647 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
4648 }
4649
4650 int _table_size;
4651 // ResourceHashtable SIZE is specified at compile time so our
4652 // dynamic _table_size is unused for now; 1031 is the first prime
4653 // after 1024.
4654 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash,
4655 &ThreadScanHashtable::ptr_equals, 1031,
4656 ResourceObj::C_HEAP, mtThread> PtrTable;
4657 PtrTable * _ptrs;
4658
4659 public:
4660 // ResourceHashtable is passed to various functions and populated in
4661 // different places so we allocate it using C_HEAP to make it immune
4662 // from any ResourceMarks that happen to be in the code paths.
4663 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {}
4664
4665 ~ThreadScanHashtable() { delete _ptrs; }
4666
4667 bool has_entry(void *pointer) {
4668 int *val_ptr = _ptrs->get(pointer);
4669 return val_ptr != NULL && *val_ptr == 1;
4670 }
4671
4672 void add_entry(void *pointer) {
4673 _ptrs->put(pointer, 1);
4674 }
4675 };
4676
4677 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4678 // (ThreadsList references) into a hash table. This closure handles part 2
4679 // of the dance - adding all the JavaThreads referenced by the hazard
4680 // pointer (ThreadsList reference) to the hash table.
4681 //
4682 class AddThreadHazardPointerThreadClosure : public ThreadClosure {
4683 private:
4684 ThreadScanHashtable *_table;
4685
4686 public:
4687 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {}
4688
4689 virtual void do_thread(Thread *thread) {
4690 if (!_table->has_entry((void*)thread)) {
4691 // The same JavaThread might be on more than one ThreadsList or
4692 // more than one thread might be using the same ThreadsList. In
4693 // either case, we only need a single entry for a JavaThread.
4694 _table->add_entry((void*)thread);
4695 }
4696 }
4697 };
4698
4699 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4700 // (ThreadsList references) into a hash table. This closure handles part 1
4701 // of the dance - hazard ptr chain walking and dispatch to another
4702 // closure.
4703 //
4704 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure {
4705 private:
4706 ThreadScanHashtable *_table;
4707 public:
4708 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {}
4709
4710 virtual void do_thread(Thread *thread) {
4711 assert_locked_or_safepoint(Threads_lock);
4712
4713 if (thread == NULL) return;
4714
4715 // This code races with Threads::acquire_stable_list() which is
4716 // lock-free so we have to handle some special situations.
4717 //
4718 ThreadsList *current_list = NULL;
4719 while (true) {
4720 current_list = thread->get_threads_hazard_ptr();
4721 // No hazard ptr so nothing more to do.
4722 if (current_list == NULL) {
4723 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4724 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4725 return;
4726 }
4727
4728 // If the hazard ptr is verified as stable (since it is not tagged),
4729 // then it is safe to use.
4730 if (!Thread::is_hazard_ptr_tagged(current_list)) break;
4731
4732 // The hazard ptr is tagged as not yet verified as being stable
4733 // so we are racing with acquire_stable_list(). This exchange
4734 // attempts to invalidate the hazard ptr. If we win the race,
4735 // then we can ignore this unstable hazard ptr and the other
4736 // thread will retry the attempt to publish a stable hazard ptr.
4737 // If we lose the race, then we retry our attempt to look at the
4738 // hazard ptr.
4739 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return;
4740 }
4741
4742 // The current JavaThread has a hazard ptr (ThreadsList reference)
4743 // which might be _smr_java_thread_list or it might be an older
4744 // ThreadsList that has been removed but not freed. In either case,
4745 // the hazard ptr is protecting all the JavaThreads on that
4746 // ThreadsList.
4747 AddThreadHazardPointerThreadClosure add_cl(_table);
4748 current_list->threads_do(&add_cl);
4749
4750 // Any NestedThreadsLists are also protecting JavaThreads so
4751 // gather those also; the ThreadsLists may be different.
4752 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4753 node != NULL; node = node->next()) {
4754 node->t_list()->threads_do(&add_cl);
4755 }
4756 }
4757 };
4758
4759 // Closure to print JavaThreads that have a hazard ptr (ThreadsList
4760 // reference) that contains an indirect reference to a specific JavaThread.
4761 //
4762 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure {
4763 private:
4764 JavaThread *_thread;
4765 public:
4766 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {}
4767
4768 virtual void do_thread(Thread *thread) {
4769 assert_locked_or_safepoint(Threads_lock);
4770
4771 if (thread == NULL) return;
4772 ThreadsList *current_list = thread->get_threads_hazard_ptr();
4773 if (current_list == NULL) {
4774 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4775 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4776 return;
4777 }
4778 // If the hazard ptr is unverified, then ignore it.
4779 if (Thread::is_hazard_ptr_tagged(current_list)) return;
4780
4781 // The current JavaThread has a hazard ptr (ThreadsList reference)
4782 // which might be _smr_java_thread_list or it might be an older
4783 // ThreadsList that has been removed but not freed. In either case,
4784 // the hazard ptr is protecting all the JavaThreads on that
4785 // ThreadsList, but we only care about matching a specific JavaThread.
4786 DO_JAVA_THREADS(current_list, p) {
4787 if (p == _thread) {
4788 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4789 break;
4790 }
4791 }
4792
4793 // Any NestedThreadsLists are also protecting JavaThreads so
4794 // check those also; the ThreadsLists may be different.
4795 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4796 node != NULL; node = node->next()) {
4797 DO_JAVA_THREADS(node->t_list(), p) {
4798 if (p == _thread) {
4799 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread));
4800 return;
4801 }
4802 }
4803 }
4804 }
4805 };
4806
4807 // Return true if the specified JavaThread is protected by a hazard
4808 // pointer (ThreadsList reference). Otherwise, returns false.
4809 //
4810 bool Threads::is_a_protected_JavaThread(JavaThread *thread) {
4811 assert_locked_or_safepoint(Threads_lock);
4812
4813 // Hash table size should be first power of two higher than twice
4814 // the length of the Threads list.
4815 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4816 hash_table_size--;
4817 hash_table_size |= hash_table_size >> 1;
4818 hash_table_size |= hash_table_size >> 2;
4819 hash_table_size |= hash_table_size >> 4;
4820 hash_table_size |= hash_table_size >> 8;
4821 hash_table_size |= hash_table_size >> 16;
4822 hash_table_size++;
4823
4824 // Gather a hash table of the JavaThreads indirectly referenced by
4825 // hazard ptrs.
4826 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4827 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table);
4828 Threads::threads_do(&scan_cl);
4829
4830 bool thread_is_protected = false;
4831 if (scan_table->has_entry((void*)thread)) {
4832 thread_is_protected = true;
4833 }
4834 delete scan_table;
4835 return thread_is_protected;
4836 }
4837
4838 // Safely delete a JavaThread when it is no longer in use by a
4839 // ThreadsListHandle.
4840 //
4841 void Threads::smr_delete(JavaThread *thread) {
4842 assert(!Threads_lock->owned_by_self(), "sanity");
4843
4844 bool has_logged_once = false;
4845 elapsedTimer timer;
4846 if (EnableThreadSMRStatistics) {
4847 timer.start();
4848 }
4849
4850 while (true) {
4851 {
4852 // No safepoint check because this JavaThread is not on the
4853 // Threads list.
4854 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
4855 // Cannot use a MonitorLockerEx helper here because we have
4856 // to drop the Threads_lock first if we wait.
4857 Threads::smr_delete_lock()->lock_without_safepoint_check();
4858 // Set the smr_delete_notify flag after we grab smr_delete_lock
4859 // and before we scan hazard ptrs because we're doing
4860 // double-check locking in release_stable_list().
4861 Threads::set_smr_delete_notify();
4862
4863 if (!is_a_protected_JavaThread(thread)) {
4864 // This is the common case.
4865 Threads::clear_smr_delete_notify();
4866 Threads::smr_delete_lock()->unlock();
4867 break;
4868 }
4869 if (!has_logged_once) {
4870 has_logged_once = true;
4871 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread));
4872 if (log_is_enabled(Debug, os, thread)) {
4873 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread);
4874 Threads::threads_do(&scan_cl);
4875 }
4876 }
4877 } // We have to drop the Threads_lock to wait or delete the thread
4878
4879 if (EnableThreadSMRStatistics) {
4880 _smr_delete_lock_wait_cnt++;
4881 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) {
4882 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt;
4883 }
4884 }
4885 // Wait for a release_stable_list() call before we check again. No
4886 // safepoint check, no timeout, and not as suspend equivalent flag
4887 // because this JavaThread is not on the Threads list.
4888 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0,
4889 !Mutex::_as_suspend_equivalent_flag);
4890 if (EnableThreadSMRStatistics) {
4891 _smr_delete_lock_wait_cnt--;
4892 }
4893
4894 Threads::clear_smr_delete_notify();
4895 Threads::smr_delete_lock()->unlock();
4896 // Retry the whole scenario.
4897 }
4898
4899 if (ThreadLocalHandshakes) {
4900 // The thread is about to be deleted so cancel any handshake.
4901 thread->cancel_handshake();
4902 }
4903
4904 delete thread;
4905 if (EnableThreadSMRStatistics) {
4906 timer.stop();
4907 uint millis = (uint)timer.milliseconds();
4908 Threads::inc_smr_deleted_thread_cnt();
4909 Threads::add_smr_deleted_thread_times(millis);
4910 Threads::update_smr_deleted_thread_time_max(millis);
4911 }
4912
4913 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread));
4914 }
4915
4916 bool Threads::smr_delete_notify() {
4917 // Use load_acquire() in order to see any updates to _smr_delete_notify
4918 // earlier than when smr_delete_lock is grabbed.
4919 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0);
4920 }
4921
4922 // set_smr_delete_notify() and clear_smr_delete_notify() are called
4923 // under the protection of the smr_delete_lock, but we also use an
4924 // Atomic operation to ensure the memory update is seen earlier than
4925 // when the smr_delete_lock is dropped.
4926 //
4927 void Threads::set_smr_delete_notify() {
4928 Atomic::inc(&_smr_delete_notify);
4929 }
4930
4931 void Threads::clear_smr_delete_notify() {
4932 Atomic::dec(&_smr_delete_notify);
4933 }
4934
4935 // Closure to gather hazard ptrs (ThreadsList references) into a hash table.
4936 //
4937 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure {
4938 private:
4939 ThreadScanHashtable *_table;
4940 public:
4941 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {}
4942
4943 virtual void do_thread(Thread* thread) {
4944 assert_locked_or_safepoint(Threads_lock);
4945
4946 if (thread == NULL) return;
4947 ThreadsList *threads = thread->get_threads_hazard_ptr();
4948 if (threads == NULL) {
4949 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4950 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4951 return;
4952 }
4953 // In this closure we always ignore the tag that might mark this
4954 // hazard ptr as not yet verified. If we happen to catch an
4955 // unverified hazard ptr that is subsequently discarded (not
4956 // published), then the only side effect is that we might keep a
4957 // to-be-deleted ThreadsList alive a little longer.
4958 threads = Thread::untag_hazard_ptr(threads);
4959 if (!_table->has_entry((void*)threads)) {
4960 _table->add_entry((void*)threads);
4961 }
4962
4963 // Any NestedThreadsLists are also protecting JavaThreads so
4964 // gather those also; the ThreadsLists may be different.
4965 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4966 node != NULL; node = node->next()) {
4967 threads = node->t_list();
4968 if (!_table->has_entry((void*)threads)) {
4969 _table->add_entry((void*)threads);
4970 }
4971 }
4972 }
4973 };
4974
4975 // Safely free a ThreadsList after a Threads::add() or Threads::remove().
4976 // The specified ThreadsList may not get deleted during this call if it
4977 // is still in-use (referenced by a hazard ptr). Other ThreadsLists
4978 // in the chain may get deleted by this call if they are no longer in-use.
4979 void Threads::smr_free_list(ThreadsList* threads) {
4980 assert_locked_or_safepoint(Threads_lock);
4981
4982 threads->set_next_list(_smr_to_delete_list);
4983 _smr_to_delete_list = threads;
4984 if (EnableThreadSMRStatistics) {
4985 _smr_to_delete_list_cnt++;
4986 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) {
4987 _smr_to_delete_list_max = _smr_to_delete_list_cnt;
4988 }
4989 }
4990
4991 // Hash table size should be first power of two higher than twice the length of the ThreadsList
4992 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4993 hash_table_size--;
4994 hash_table_size |= hash_table_size >> 1;
4995 hash_table_size |= hash_table_size >> 2;
4996 hash_table_size |= hash_table_size >> 4;
4997 hash_table_size |= hash_table_size >> 8;
4998 hash_table_size |= hash_table_size >> 16;
4999 hash_table_size++;
5000
5001 // Gather a hash table of the current hazard ptrs:
5002 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
5003 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table);
5004 Threads::threads_do(&scan_cl);
5005
5006 // Walk through the linked list of pending freeable ThreadsLists
5007 // and free the ones that are not referenced from hazard ptrs.
5008 ThreadsList* current = _smr_to_delete_list;
5009 ThreadsList* prev = NULL;
5010 ThreadsList* next = NULL;
5011 bool threads_is_freed = false;
5012 while (current != NULL) {
5013 next = current->next_list();
5014 if (!scan_table->has_entry((void*)current)) {
5015 // This ThreadsList is not referenced by a hazard ptr.
5016 if (prev != NULL) {
5017 prev->set_next_list(next);
5018 }
5019 if (_smr_to_delete_list == current) {
5020 _smr_to_delete_list = next;
5021 }
5022
5023 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current));
5024 if (current == threads) threads_is_freed = true;
5025 delete current;
5026 if (EnableThreadSMRStatistics) {
5027 _smr_java_thread_list_free_cnt++;
5028 _smr_to_delete_list_cnt--;
5029 }
5030 } else {
5031 prev = current;
5032 }
5033 current = next;
5034 }
5035
5036 if (!threads_is_freed) {
5037 // Only report "is not freed" on the original call to
5038 // smr_free_list() for this ThreadsList.
5039 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads));
5040 }
5041
5042 delete scan_table;
5043 }
5044
5045 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a
5046 // new copy of the specified ThreadsList with the specified JavaThread
5047 // removed.
5048 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) {
5049 assert(list->_length > 0, "sanity");
5050
5051 uint i = 0;
5052 DO_JAVA_THREADS(list, current) {
5053 if (current == java_thread) {
5054 break;
5055 }
5056 i++;
5057 }
5058 assert(i < list->_length, "did not find JavaThread on the list");
5059 const uint index = i;
5060 const uint new_length = list->_length - 1;
5061 const uint head_length = index;
5062 const uint tail_length = (new_length >= index) ? (new_length - index) : 0;
5063 ThreadsList *const new_list = new ThreadsList(new_length);
5064
5065 if (head_length > 0) {
5066 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5067 }
5068 if (tail_length > 0) {
5069 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length);
5070 }
5071
5072 return new_list;
5073 }
5074
5075 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a
5076 // new copy of the specified ThreadsList with the specified JavaThread
5077 // appended to the end.
5078 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) {
5079 const uint index = list->_length;
5080 const uint new_length = index + 1;
5081 const uint head_length = index;
5082 ThreadsList *const new_list = new ThreadsList(new_length);
5083
5084 if (head_length > 0) {
5085 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5086 }
5087 *(JavaThread**)(new_list->_threads + index) = java_thread;
5088
5089 return new_list;
5090 }
5091
5092 int ThreadsList::find_index_of_JavaThread(JavaThread *target) {
5093 if (target == NULL) {
5094 return -1;
5095 }
5096 for (uint i = 0; i < length(); i++) {
5097 if (target == thread_at(i)) {
5098 return (int)i;
5099 }
5100 }
5101 return -1;
5102 }
5103
5104 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const {
5105 DO_JAVA_THREADS(this, thread) {
5106 oop tobj = thread->threadObj();
5107 // Ignore the thread if it hasn't run yet, has exited
5108 // or is starting to exit.
5109 if (tobj != NULL && !thread->is_exiting() &&
5110 java_tid == java_lang_Thread::thread_id(tobj)) {
5111 // found a match
5112 return thread;
5113 }
5114 }
5115 return NULL;
5116 }
5117
5118 bool ThreadsList::includes(const JavaThread * const p) const {
5119 if (p == NULL) {
5120 return false;
5121 }
5122 DO_JAVA_THREADS(this, q) {
5123 if (q == p) {
5124 return true;
5125 }
5126 }
5127 return false;
5128 }
5129
5130 void Threads::add(JavaThread* p, bool force_daemon) {
5131 // The threads lock must be owned at this point
5132 assert_locked_or_safepoint(Threads_lock);
5133
5134 // See the comment for this method in thread.hpp for its purpose and
5135 // why it is called here.
5136 p->initialize_queues();
5137 p->set_next(_thread_list);
5138 _thread_list = p;
5139
5140 // Once a JavaThread is added to the Threads list, smr_delete() has
5141 // to be used to delete it. Otherwise we can just delete it directly.
5142 p->set_on_thread_list();
5143
5144 _number_of_threads++;
5145 oop threadObj = p->threadObj();
5146 bool daemon = true;
5147 // Bootstrapping problem: threadObj can be null for initial
5148 // JavaThread (or for threads attached via JNI)
5149 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
5150 _number_of_non_daemon_threads++;
5151 daemon = false;
5152 }
5153
5154 ThreadService::add_thread(p, daemon);
5155
5156 // Maintain fast thread list
5157 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p);
5158 if (EnableThreadSMRStatistics) {
5159 _smr_java_thread_list_alloc_cnt++;
5160 if (new_list->length() > _smr_java_thread_list_max) {
5161 _smr_java_thread_list_max = new_list->length();
5162 }
5163 }
5164 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg.
5165 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5166
5167 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5168 smr_free_list(old_list);
5169
5170 // Possible GC point.
5171 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
5172 }
5173
5174 void Threads::remove(JavaThread* p) {
5175
5176 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
5177 ObjectSynchronizer::omFlush(p);
5178
5179 // Extra scope needed for Thread_lock, so we can check
5180 // that we do not remove thread without safepoint code notice
5181 { MutexLocker ml(Threads_lock);
5182
5183 assert(get_smr_java_thread_list()->includes(p), "p must be present");
5184
5185 // Maintain fast thread list
5186 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p);
5187 if (EnableThreadSMRStatistics) {
5188 _smr_java_thread_list_alloc_cnt++;
5189 // This list is smaller so no need to check for a "longest" update.
5190 }
5191
5192 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg.
5193 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5194
5195 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5196 smr_free_list(old_list);
5197
5198 JavaThread* current = _thread_list;
5199 JavaThread* prev = NULL;
5200
5201 while (current != p) {
5202 prev = current;
5203 current = current->next();
5204 }
5205
5206 if (prev) {
5207 prev->set_next(current->next());
5208 } else {
5209 _thread_list = p->next();
5210 }
5211
5212 _number_of_threads--;
5213 oop threadObj = p->threadObj();
5214 bool daemon = true;
5215 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
5216 _number_of_non_daemon_threads--;
5217 daemon = false;
5218
5219 // Only one thread left, do a notify on the Threads_lock so a thread waiting
5220 // on destroy_vm will wake up.
5221 if (number_of_non_daemon_threads() == 1) {
5222 Threads_lock->notify_all();
5223 }
5224 }
5225 ThreadService::remove_thread(p, daemon);
5226
5227 // Make sure that safepoint code disregard this thread. This is needed since
5228 // the thread might mess around with locks after this point. This can cause it
5229 // to do callbacks into the safepoint code. However, the safepoint code is not aware
5230 // of this thread since it is removed from the queue.
5231 p->set_terminated_value();
5232 } // unlock Threads_lock
5233
5234 // Since Events::log uses a lock, we grab it outside the Threads_lock
5235 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
5236 }
5237
5238 // Operations on the Threads list for GC. These are not explicitly locked,
5239 // but the garbage collector must provide a safe context for them to run.
5240 // In particular, these things should never be called when the Threads_lock
5241 // is held by some other thread. (Note: the Safepoint abstraction also
5242 // uses the Threads_lock to guarantee this property. It also makes sure that
5243 // all threads gets blocked when exiting or starting).
5244
5245 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
5246 ALL_JAVA_THREADS(p) {
5247 p->oops_do(f, cf);
5248 }
5249 VMThread::vm_thread()->oops_do(f, cf);
5250 }
5251
5252 void Threads::change_thread_claim_parity() {
5253 // Set the new claim parity.
5254 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
5255 "Not in range.");
5256 _thread_claim_parity++;
5257 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
5258 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
5259 "Not in range.");
5260 }
5261
5262 #ifdef ASSERT
5263 void Threads::assert_all_threads_claimed() {
5264 ALL_JAVA_THREADS(p) {
5265 const int thread_parity = p->oops_do_parity();
5266 assert((thread_parity == _thread_claim_parity),
5267 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
5268 }
5269 VMThread* vmt = VMThread::vm_thread();
5270 const int thread_parity = vmt->oops_do_parity();
5271 assert((thread_parity == _thread_claim_parity),
5272 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
5273 }
5274 #endif // ASSERT
5275
5276 class ParallelOopsDoThreadClosure : public ThreadClosure {
5277 private:
5278 OopClosure* _f;
5279 CodeBlobClosure* _cf;
5280 public:
5281 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
5282 void do_thread(Thread* t) {
5283 t->oops_do(_f, _cf);
5284 }
5285 };
5286
5287 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
5288 ParallelOopsDoThreadClosure tc(f, cf);
5289 possibly_parallel_threads_do(is_par, &tc);
5290 }
5291
5292 #if INCLUDE_ALL_GCS
5293 // Used by ParallelScavenge
5294 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
5295 ALL_JAVA_THREADS(p) {
5296 q->enqueue(new ThreadRootsTask(p));
5297 }
5298 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
5299 }
5300
5301 // Used by Parallel Old
5302 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
5303 ALL_JAVA_THREADS(p) {
5304 q->enqueue(new ThreadRootsMarkingTask(p));
5305 }
5306 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
5307 }
5308 #endif // INCLUDE_ALL_GCS
5309
5310 void Threads::nmethods_do(CodeBlobClosure* cf) {
5311 ALL_JAVA_THREADS(p) {
5312 // This is used by the code cache sweeper to mark nmethods that are active
5313 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
5314 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
5315 if(!p->is_Code_cache_sweeper_thread()) {
5316 p->nmethods_do(cf);
5317 }
5318 }
5319 }
5320
5321 void Threads::metadata_do(void f(Metadata*)) {
5322 ALL_JAVA_THREADS(p) {
5323 p->metadata_do(f);
5324 }
5325 }
5326
5327 class ThreadHandlesClosure : public ThreadClosure {
5328 void (*_f)(Metadata*);
5329 public:
5330 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
5331 virtual void do_thread(Thread* thread) {
5332 thread->metadata_handles_do(_f);
5333 }
5334 };
5335
5336 void Threads::metadata_handles_do(void f(Metadata*)) {
5337 // Only walk the Handles in Thread.
5338 ThreadHandlesClosure handles_closure(f);
5339 threads_do(&handles_closure);
5340 }
5341
5342 void Threads::deoptimized_wrt_marked_nmethods() {
5343 ALL_JAVA_THREADS(p) {
5344 p->deoptimized_wrt_marked_nmethods();
5345 }
5346 }
5347
5348
5349 // Get count Java threads that are waiting to enter the specified monitor.
5350 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
5351 int count,
5352 address monitor) {
5353 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
5354
5355 int i = 0;
5356 DO_JAVA_THREADS(t_list, p) {
5357 if (!p->can_call_java()) continue;
5358
5359 address pending = (address)p->current_pending_monitor();
5360 if (pending == monitor) { // found a match
5361 if (i < count) result->append(p); // save the first count matches
5362 i++;
5363 }
5364 }
5365
5366 return result;
5367 }
5368
5369
5370 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
5371 address owner) {
5372 // NULL owner means not locked so we can skip the search
5373 if (owner == NULL) return NULL;
5374
5375 DO_JAVA_THREADS(t_list, p) {
5376 // first, see if owner is the address of a Java thread
5377 if (owner == (address)p) return p;
5378 }
5379
5380 // Cannot assert on lack of success here since this function may be
5381 // used by code that is trying to report useful problem information
5382 // like deadlock detection.
5383 if (UseHeavyMonitors) return NULL;
5384
5385 // If we didn't find a matching Java thread and we didn't force use of
5386 // heavyweight monitors, then the owner is the stack address of the
5387 // Lock Word in the owning Java thread's stack.
5388 //
5389 JavaThread* the_owner = NULL;
5390 DO_JAVA_THREADS(t_list, q) {
5391 if (q->is_lock_owned(owner)) {
5392 the_owner = q;
5393 break;
5394 }
5395 }
5396
5397 // cannot assert on lack of success here; see above comment
5398 return the_owner;
5399 }
5400
5401 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
5402 void Threads::print_on(outputStream* st, bool print_stacks,
5403 bool internal_format, bool print_concurrent_locks) {
5404 char buf[32];
5405 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
5406
5407 st->print_cr("Full thread dump %s (%s %s):",
5408 Abstract_VM_Version::vm_name(),
5409 Abstract_VM_Version::vm_release(),
5410 Abstract_VM_Version::vm_info_string());
5411 st->cr();
5412
5413 #if INCLUDE_SERVICES
5414 // Dump concurrent locks
5415 ConcurrentLocksDump concurrent_locks;
5416 if (print_concurrent_locks) {
5417 concurrent_locks.dump_at_safepoint();
5418 }
5419 #endif // INCLUDE_SERVICES
5420
5421 print_smr_info_on(st);
5422 st->cr();
5423
5424 ALL_JAVA_THREADS(p) {
5425 ResourceMark rm;
5426 p->print_on(st);
5427 if (print_stacks) {
5428 if (internal_format) {
5429 p->trace_stack();
5430 } else {
5431 p->print_stack_on(st);
5432 }
5433 }
5434 st->cr();
5435 #if INCLUDE_SERVICES
5436 if (print_concurrent_locks) {
5437 concurrent_locks.print_locks_on(p, st);
5438 }
5439 #endif // INCLUDE_SERVICES
5440 }
5441
5442 VMThread::vm_thread()->print_on(st);
5443 st->cr();
5444 Universe::heap()->print_gc_threads_on(st);
5445 WatcherThread* wt = WatcherThread::watcher_thread();
5446 if (wt != NULL) {
5447 wt->print_on(st);
5448 st->cr();
5449 }
5450
5451 st->flush();
5452 }
5453
5454 // Log Threads class SMR info.
5455 void Threads::log_smr_statistics() {
5456 LogTarget(Info, thread, smr) log;
5457 if (log.is_enabled()) {
5458 LogStream out(log);
5459 print_smr_info_on(&out);
5460 }
5461 }
5462
5463 // Print Threads class SMR info.
5464 void Threads::print_smr_info_on(outputStream* st) {
5465 // Only grab the Threads_lock if we don't already own it
5466 // and if we are not reporting an error.
5467 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock);
5468
5469 st->print_cr("Threads class SMR info:");
5470 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, "
5471 "elements={", p2i(_smr_java_thread_list),
5472 _smr_java_thread_list->length());
5473 print_smr_info_elements_on(st, _smr_java_thread_list);
5474 st->print_cr("}");
5475 if (_smr_to_delete_list != NULL) {
5476 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, "
5477 "elements={", p2i(_smr_to_delete_list),
5478 _smr_to_delete_list->length());
5479 print_smr_info_elements_on(st, _smr_to_delete_list);
5480 st->print_cr("}");
5481 for (ThreadsList *t_list = _smr_to_delete_list->next_list();
5482 t_list != NULL; t_list = t_list->next_list()) {
5483 st->print("next-> " INTPTR_FORMAT ", length=%u, "
5484 "elements={", p2i(t_list), t_list->length());
5485 print_smr_info_elements_on(st, t_list);
5486 st->print_cr("}");
5487 }
5488 }
5489 if (!EnableThreadSMRStatistics) {
5490 return;
5491 }
5492 st->print_cr("_smr_java_thread_list_alloc_cnt=" UINT64_FORMAT ","
5493 "_smr_java_thread_list_free_cnt=" UINT64_FORMAT ","
5494 "_smr_java_thread_list_max=%u, "
5495 "_smr_nested_thread_list_max=%u",
5496 _smr_java_thread_list_alloc_cnt,
5497 _smr_java_thread_list_free_cnt,
5498 _smr_java_thread_list_max,
5499 _smr_nested_thread_list_max);
5500 if (_smr_tlh_cnt > 0) {
5501 st->print_cr("_smr_tlh_cnt=%u"
5502 ", _smr_tlh_times=%u"
5503 ", avg_smr_tlh_time=%0.2f"
5504 ", _smr_tlh_time_max=%u",
5505 _smr_tlh_cnt, _smr_tlh_times,
5506 ((double) _smr_tlh_times / _smr_tlh_cnt),
5507 _smr_tlh_time_max);
5508 }
5509 if (_smr_deleted_thread_cnt > 0) {
5510 st->print_cr("_smr_deleted_thread_cnt=%u"
5511 ", _smr_deleted_thread_times=%u"
5512 ", avg_smr_deleted_thread_time=%0.2f"
5513 ", _smr_deleted_thread_time_max=%u",
5514 _smr_deleted_thread_cnt, _smr_deleted_thread_times,
5515 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt),
5516 _smr_deleted_thread_time_max);
5517 }
5518 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u",
5519 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max);
5520 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u",
5521 _smr_to_delete_list_cnt, _smr_to_delete_list_max);
5522 }
5523
5524 // Print ThreadsList elements (4 per line).
5525 void Threads::print_smr_info_elements_on(outputStream* st,
5526 ThreadsList* t_list) {
5527 uint cnt = 0;
5528 JavaThreadIterator jti(t_list);
5529 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) {
5530 st->print(INTPTR_FORMAT, p2i(jt));
5531 if (cnt < t_list->length() - 1) {
5532 // Separate with comma or comma-space except for the last one.
5533 if (((cnt + 1) % 4) == 0) {
5534 // Four INTPTR_FORMAT fit on an 80 column line so end the
5535 // current line with just a comma.
5536 st->print_cr(",");
5537 } else {
5538 // Not the last one on the current line so use comma-space:
5539 st->print(", ");
5540 }
5541 } else {
5542 // Last one so just end the current line.
5543 st->cr();
5544 }
5545 cnt++;
5546 }
5547 }
5548
5549 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
5550 int buflen, bool* found_current) {
5551 if (this_thread != NULL) {
5552 bool is_current = (current == this_thread);
5553 *found_current = *found_current || is_current;
5554 st->print("%s", is_current ? "=>" : " ");
5555
5556 st->print(PTR_FORMAT, p2i(this_thread));
5557 st->print(" ");
5558 this_thread->print_on_error(st, buf, buflen);
5559 st->cr();
5560 }
5561 }
5562
5563 class PrintOnErrorClosure : public ThreadClosure {
5564 outputStream* _st;
5565 Thread* _current;
5566 char* _buf;
5567 int _buflen;
5568 bool* _found_current;
5569 public:
5570 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
5571 int buflen, bool* found_current) :
5572 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
5573
5574 virtual void do_thread(Thread* thread) {
5575 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
5576 }
5577 };
5578
5579 // Threads::print_on_error() is called by fatal error handler. It's possible
5580 // that VM is not at safepoint and/or current thread is inside signal handler.
5581 // Don't print stack trace, as the stack may not be walkable. Don't allocate
5582 // memory (even in resource area), it might deadlock the error handler.
5583 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
5584 int buflen) {
5585 print_smr_info_on(st);
5586 st->cr();
5587
5588 bool found_current = false;
5589 st->print_cr("Java Threads: ( => current thread )");
5590 ALL_JAVA_THREADS(thread) {
5591 print_on_error(thread, st, current, buf, buflen, &found_current);
5592 }
5593 st->cr();
5594
5595 st->print_cr("Other Threads:");
5596 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
5597 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
5598
5599 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
5600 Universe::heap()->gc_threads_do(&print_closure);
5601
5602 if (!found_current) {
5603 st->cr();
5604 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
5605 current->print_on_error(st, buf, buflen);
5606 st->cr();
5607 }
5608 st->cr();
5609
5610 st->print_cr("Threads with active compile tasks:");
5611 print_threads_compiling(st, buf, buflen);
5612 }
5613
5614 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
5615 ALL_JAVA_THREADS(thread) {
5616 if (thread->is_Compiler_thread()) {
5617 CompilerThread* ct = (CompilerThread*) thread;
5618 if (ct->task() != NULL) {
5619 thread->print_name_on_error(st, buf, buflen);
5620 ct->task()->print(st, NULL, true, true);
5621 }
5622 }
5623 }
5624 }
5625
5626
5627 // Internal SpinLock and Mutex
5628 // Based on ParkEvent
5629
5630 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
5631 //
5632 // We employ SpinLocks _only for low-contention, fixed-length
5633 // short-duration critical sections where we're concerned
5634 // about native mutex_t or HotSpot Mutex:: latency.
5635 // The mux construct provides a spin-then-block mutual exclusion
5636 // mechanism.
5637 //
5638 // Testing has shown that contention on the ListLock guarding gFreeList
5639 // is common. If we implement ListLock as a simple SpinLock it's common
5640 // for the JVM to devolve to yielding with little progress. This is true
5641 // despite the fact that the critical sections protected by ListLock are
5642 // extremely short.
5643 //
5644 // TODO-FIXME: ListLock should be of type SpinLock.
5645 // We should make this a 1st-class type, integrated into the lock
5646 // hierarchy as leaf-locks. Critically, the SpinLock structure
5647 // should have sufficient padding to avoid false-sharing and excessive
5648 // cache-coherency traffic.
5649
5650
5651 typedef volatile int SpinLockT;
5652
5653 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
5654 if (Atomic::cmpxchg (1, adr, 0) == 0) {
5655 return; // normal fast-path return
5656 }
5657
5658 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
5659 TEVENT(SpinAcquire - ctx);
5660 int ctr = 0;
5661 int Yields = 0;
5662 for (;;) {
5663 while (*adr != 0) {
5664 ++ctr;
5665 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
5666 if (Yields > 5) {
5667 os::naked_short_sleep(1);
5668 } else {
5669 os::naked_yield();
5670 ++Yields;
5671 }
5672 } else {
5673 SpinPause();
5674 }
5675 }
5676 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
5677 }
5678 }
5679
5680 void Thread::SpinRelease(volatile int * adr) {
5681 assert(*adr != 0, "invariant");
5682 OrderAccess::fence(); // guarantee at least release consistency.
5683 // Roach-motel semantics.
5684 // It's safe if subsequent LDs and STs float "up" into the critical section,
5685 // but prior LDs and STs within the critical section can't be allowed
5686 // to reorder or float past the ST that releases the lock.
5687 // Loads and stores in the critical section - which appear in program
5688 // order before the store that releases the lock - must also appear
5689 // before the store that releases the lock in memory visibility order.
5690 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5691 // the ST of 0 into the lock-word which releases the lock, so fence
5692 // more than covers this on all platforms.
5693 *adr = 0;
5694 }
5695
5696 // muxAcquire and muxRelease:
5697 //
5698 // * muxAcquire and muxRelease support a single-word lock-word construct.
5699 // The LSB of the word is set IFF the lock is held.
5700 // The remainder of the word points to the head of a singly-linked list
5701 // of threads blocked on the lock.
5702 //
5703 // * The current implementation of muxAcquire-muxRelease uses its own
5704 // dedicated Thread._MuxEvent instance. If we're interested in
5705 // minimizing the peak number of extant ParkEvent instances then
5706 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5707 // as certain invariants were satisfied. Specifically, care would need
5708 // to be taken with regards to consuming unpark() "permits".
5709 // A safe rule of thumb is that a thread would never call muxAcquire()
5710 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5711 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5712 // consume an unpark() permit intended for monitorenter, for instance.
5713 // One way around this would be to widen the restricted-range semaphore
5714 // implemented in park(). Another alternative would be to provide
5715 // multiple instances of the PlatformEvent() for each thread. One
5716 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5717 //
5718 // * Usage:
5719 // -- Only as leaf locks
5720 // -- for short-term locking only as muxAcquire does not perform
5721 // thread state transitions.
5722 //
5723 // Alternatives:
5724 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5725 // but with parking or spin-then-park instead of pure spinning.
5726 // * Use Taura-Oyama-Yonenzawa locks.
5727 // * It's possible to construct a 1-0 lock if we encode the lockword as
5728 // (List,LockByte). Acquire will CAS the full lockword while Release
5729 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5730 // acquiring threads use timers (ParkTimed) to detect and recover from
5731 // the stranding window. Thread/Node structures must be aligned on 256-byte
5732 // boundaries by using placement-new.
5733 // * Augment MCS with advisory back-link fields maintained with CAS().
5734 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5735 // The validity of the backlinks must be ratified before we trust the value.
5736 // If the backlinks are invalid the exiting thread must back-track through the
5737 // the forward links, which are always trustworthy.
5738 // * Add a successor indication. The LockWord is currently encoded as
5739 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5740 // to provide the usual futile-wakeup optimization.
5741 // See RTStt for details.
5742 // * Consider schedctl.sc_nopreempt to cover the critical section.
5743 //
5744
5745
5746 const intptr_t LOCKBIT = 1;
5747
5748 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5749 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5750 if (w == 0) return;
5751 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5752 return;
5753 }
5754
5755 TEVENT(muxAcquire - Contention);
5756 ParkEvent * const Self = Thread::current()->_MuxEvent;
5757 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5758 for (;;) {
5759 int its = (os::is_MP() ? 100 : 0) + 1;
5760
5761 // Optional spin phase: spin-then-park strategy
5762 while (--its >= 0) {
5763 w = *Lock;
5764 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5765 return;
5766 }
5767 }
5768
5769 Self->reset();
5770 Self->OnList = intptr_t(Lock);
5771 // The following fence() isn't _strictly necessary as the subsequent
5772 // CAS() both serializes execution and ratifies the fetched *Lock value.
5773 OrderAccess::fence();
5774 for (;;) {
5775 w = *Lock;
5776 if ((w & LOCKBIT) == 0) {
5777 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5778 Self->OnList = 0; // hygiene - allows stronger asserts
5779 return;
5780 }
5781 continue; // Interference -- *Lock changed -- Just retry
5782 }
5783 assert(w & LOCKBIT, "invariant");
5784 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5785 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5786 }
5787
5788 while (Self->OnList != 0) {
5789 Self->park();
5790 }
5791 }
5792 }
5793
5794 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5795 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5796 if (w == 0) return;
5797 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5798 return;
5799 }
5800
5801 TEVENT(muxAcquire - Contention);
5802 ParkEvent * ReleaseAfter = NULL;
5803 if (ev == NULL) {
5804 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5805 }
5806 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5807 for (;;) {
5808 guarantee(ev->OnList == 0, "invariant");
5809 int its = (os::is_MP() ? 100 : 0) + 1;
5810
5811 // Optional spin phase: spin-then-park strategy
5812 while (--its >= 0) {
5813 w = *Lock;
5814 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5815 if (ReleaseAfter != NULL) {
5816 ParkEvent::Release(ReleaseAfter);
5817 }
5818 return;
5819 }
5820 }
5821
5822 ev->reset();
5823 ev->OnList = intptr_t(Lock);
5824 // The following fence() isn't _strictly necessary as the subsequent
5825 // CAS() both serializes execution and ratifies the fetched *Lock value.
5826 OrderAccess::fence();
5827 for (;;) {
5828 w = *Lock;
5829 if ((w & LOCKBIT) == 0) {
5830 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5831 ev->OnList = 0;
5832 // We call ::Release while holding the outer lock, thus
5833 // artificially lengthening the critical section.
5834 // Consider deferring the ::Release() until the subsequent unlock(),
5835 // after we've dropped the outer lock.
5836 if (ReleaseAfter != NULL) {
5837 ParkEvent::Release(ReleaseAfter);
5838 }
5839 return;
5840 }
5841 continue; // Interference -- *Lock changed -- Just retry
5842 }
5843 assert(w & LOCKBIT, "invariant");
5844 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5845 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5846 }
5847
5848 while (ev->OnList != 0) {
5849 ev->park();
5850 }
5851 }
5852 }
5853
5854 // Release() must extract a successor from the list and then wake that thread.
5855 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5856 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5857 // Release() would :
5858 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5859 // (B) Extract a successor from the private list "in-hand"
5860 // (C) attempt to CAS() the residual back into *Lock over null.
5861 // If there were any newly arrived threads and the CAS() would fail.
5862 // In that case Release() would detach the RATs, re-merge the list in-hand
5863 // with the RATs and repeat as needed. Alternately, Release() might
5864 // detach and extract a successor, but then pass the residual list to the wakee.
5865 // The wakee would be responsible for reattaching and remerging before it
5866 // competed for the lock.
5867 //
5868 // Both "pop" and DMR are immune from ABA corruption -- there can be
5869 // multiple concurrent pushers, but only one popper or detacher.
5870 // This implementation pops from the head of the list. This is unfair,
5871 // but tends to provide excellent throughput as hot threads remain hot.
5872 // (We wake recently run threads first).
5873 //
5874 // All paths through muxRelease() will execute a CAS.
5875 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5876 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5877 // executed within the critical section are complete and globally visible before the
5878 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5879 void Thread::muxRelease(volatile intptr_t * Lock) {
5880 for (;;) {
5881 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5882 assert(w & LOCKBIT, "invariant");
5883 if (w == LOCKBIT) return;
5884 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5885 assert(List != NULL, "invariant");
5886 assert(List->OnList == intptr_t(Lock), "invariant");
5887 ParkEvent * const nxt = List->ListNext;
5888 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5889
5890 // The following CAS() releases the lock and pops the head element.
5891 // The CAS() also ratifies the previously fetched lock-word value.
5892 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5893 continue;
5894 }
5895 List->OnList = 0;
5896 OrderAccess::fence();
5897 List->unpark();
5898 return;
5899 }
5900 }
5901
5902
5903 void Threads::verify() {
5904 ALL_JAVA_THREADS(p) {
5905 p->verify();
5906 }
5907 VMThread* thread = VMThread::vm_thread();
5908 if (thread != NULL) thread->verify();
5909 }