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 someone set a handshake on us just as we entered exit path, we simple cancel it.
2027 if (ThreadLocalHandshakes) {
2028 cancel_handshake();
2029 }
2030
2031 if (log_is_enabled(Debug, os, thread, timer)) {
2032 _timer_exit_phase4.stop();
2033 ResourceMark rm(this);
2034 log_debug(os, thread, timer)("name='%s'"
2035 ", exit-phase1=" JLONG_FORMAT
2036 ", exit-phase2=" JLONG_FORMAT
2037 ", exit-phase3=" JLONG_FORMAT
2038 ", exit-phase4=" JLONG_FORMAT,
2039 get_thread_name(),
2040 _timer_exit_phase1.milliseconds(),
2041 _timer_exit_phase2.milliseconds(),
2042 _timer_exit_phase3.milliseconds(),
2043 _timer_exit_phase4.milliseconds());
2044 }
2045 }
2046
2047 #if INCLUDE_ALL_GCS
2048 // Flush G1-related queues.
2049 void JavaThread::flush_barrier_queues() {
2050 satb_mark_queue().flush();
2051 dirty_card_queue().flush();
2052 }
2053
2054 void JavaThread::initialize_queues() {
2055 assert(!SafepointSynchronize::is_at_safepoint(),
2056 "we should not be at a safepoint");
2057
2058 SATBMarkQueue& satb_queue = satb_mark_queue();
2059 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2060 // The SATB queue should have been constructed with its active
2061 // field set to false.
2062 assert(!satb_queue.is_active(), "SATB queue should not be active");
2063 assert(satb_queue.is_empty(), "SATB queue should be empty");
2064 // If we are creating the thread during a marking cycle, we should
2065 // set the active field of the SATB queue to true.
2066 if (satb_queue_set.is_active()) {
2067 satb_queue.set_active(true);
2068 }
2069
2070 DirtyCardQueue& dirty_queue = dirty_card_queue();
2071 // The dirty card queue should have been constructed with its
2072 // active field set to true.
2073 assert(dirty_queue.is_active(), "dirty card queue should be active");
2074 }
2075 #endif // INCLUDE_ALL_GCS
2076
2077 void JavaThread::cleanup_failed_attach_current_thread() {
2078 if (active_handles() != NULL) {
2079 JNIHandleBlock* block = active_handles();
2080 set_active_handles(NULL);
2081 JNIHandleBlock::release_block(block);
2082 }
2083
2084 if (free_handle_block() != NULL) {
2085 JNIHandleBlock* block = free_handle_block();
2086 set_free_handle_block(NULL);
2087 JNIHandleBlock::release_block(block);
2088 }
2089
2090 // These have to be removed while this is still a valid thread.
2091 remove_stack_guard_pages();
2092
2093 if (UseTLAB) {
2094 tlab().make_parsable(true); // retire TLAB, if any
2095 }
2096
2097 #if INCLUDE_ALL_GCS
2098 if (UseG1GC) {
2099 flush_barrier_queues();
2100 }
2101 #endif // INCLUDE_ALL_GCS
2102
2103 Threads::remove(this);
2104 this->smr_delete();
2105 }
2106
2107
2108
2109
2110 JavaThread* JavaThread::active() {
2111 Thread* thread = Thread::current();
2112 if (thread->is_Java_thread()) {
2113 return (JavaThread*) thread;
2114 } else {
2115 assert(thread->is_VM_thread(), "this must be a vm thread");
2116 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2117 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2118 assert(ret->is_Java_thread(), "must be a Java thread");
2119 return ret;
2120 }
2121 }
2122
2123 bool JavaThread::is_lock_owned(address adr) const {
2124 if (Thread::is_lock_owned(adr)) return true;
2125
2126 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2127 if (chunk->contains(adr)) return true;
2128 }
2129
2130 return false;
2131 }
2132
2133
2134 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2135 chunk->set_next(monitor_chunks());
2136 set_monitor_chunks(chunk);
2137 }
2138
2139 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2140 guarantee(monitor_chunks() != NULL, "must be non empty");
2141 if (monitor_chunks() == chunk) {
2142 set_monitor_chunks(chunk->next());
2143 } else {
2144 MonitorChunk* prev = monitor_chunks();
2145 while (prev->next() != chunk) prev = prev->next();
2146 prev->set_next(chunk->next());
2147 }
2148 }
2149
2150 // JVM support.
2151
2152 // Note: this function shouldn't block if it's called in
2153 // _thread_in_native_trans state (such as from
2154 // check_special_condition_for_native_trans()).
2155 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2156
2157 if (has_last_Java_frame() && has_async_condition()) {
2158 // If we are at a polling page safepoint (not a poll return)
2159 // then we must defer async exception because live registers
2160 // will be clobbered by the exception path. Poll return is
2161 // ok because the call we a returning from already collides
2162 // with exception handling registers and so there is no issue.
2163 // (The exception handling path kills call result registers but
2164 // this is ok since the exception kills the result anyway).
2165
2166 if (is_at_poll_safepoint()) {
2167 // if the code we are returning to has deoptimized we must defer
2168 // the exception otherwise live registers get clobbered on the
2169 // exception path before deoptimization is able to retrieve them.
2170 //
2171 RegisterMap map(this, false);
2172 frame caller_fr = last_frame().sender(&map);
2173 assert(caller_fr.is_compiled_frame(), "what?");
2174 if (caller_fr.is_deoptimized_frame()) {
2175 log_info(exceptions)("deferred async exception at compiled safepoint");
2176 return;
2177 }
2178 }
2179 }
2180
2181 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2182 if (condition == _no_async_condition) {
2183 // Conditions have changed since has_special_runtime_exit_condition()
2184 // was called:
2185 // - if we were here only because of an external suspend request,
2186 // then that was taken care of above (or cancelled) so we are done
2187 // - if we were here because of another async request, then it has
2188 // been cleared between the has_special_runtime_exit_condition()
2189 // and now so again we are done
2190 return;
2191 }
2192
2193 // Check for pending async. exception
2194 if (_pending_async_exception != NULL) {
2195 // Only overwrite an already pending exception, if it is not a threadDeath.
2196 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2197
2198 // We cannot call Exceptions::_throw(...) here because we cannot block
2199 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2200
2201 LogTarget(Info, exceptions) lt;
2202 if (lt.is_enabled()) {
2203 ResourceMark rm;
2204 LogStream ls(lt);
2205 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2206 if (has_last_Java_frame()) {
2207 frame f = last_frame();
2208 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2209 }
2210 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2211 }
2212 _pending_async_exception = NULL;
2213 clear_has_async_exception();
2214 }
2215 }
2216
2217 if (check_unsafe_error &&
2218 condition == _async_unsafe_access_error && !has_pending_exception()) {
2219 condition = _no_async_condition; // done
2220 switch (thread_state()) {
2221 case _thread_in_vm: {
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_native: {
2226 ThreadInVMfromNative tiv(this);
2227 JavaThread* THREAD = this;
2228 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2229 }
2230 case _thread_in_Java: {
2231 ThreadInVMfromJava tiv(this);
2232 JavaThread* THREAD = this;
2233 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2234 }
2235 default:
2236 ShouldNotReachHere();
2237 }
2238 }
2239
2240 assert(condition == _no_async_condition || has_pending_exception() ||
2241 (!check_unsafe_error && condition == _async_unsafe_access_error),
2242 "must have handled the async condition, if no exception");
2243 }
2244
2245 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2246 //
2247 // Check for pending external suspend. Internal suspend requests do
2248 // not use handle_special_runtime_exit_condition().
2249 // If JNIEnv proxies are allowed, don't self-suspend if the target
2250 // thread is not the current thread. In older versions of jdbx, jdbx
2251 // threads could call into the VM with another thread's JNIEnv so we
2252 // can be here operating on behalf of a suspended thread (4432884).
2253 bool do_self_suspend = is_external_suspend_with_lock();
2254 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2255 //
2256 // Because thread is external suspended the safepoint code will count
2257 // thread as at a safepoint. This can be odd because we can be here
2258 // as _thread_in_Java which would normally transition to _thread_blocked
2259 // at a safepoint. We would like to mark the thread as _thread_blocked
2260 // before calling java_suspend_self like all other callers of it but
2261 // we must then observe proper safepoint protocol. (We can't leave
2262 // _thread_blocked with a safepoint in progress). However we can be
2263 // here as _thread_in_native_trans so we can't use a normal transition
2264 // constructor/destructor pair because they assert on that type of
2265 // transition. We could do something like:
2266 //
2267 // JavaThreadState state = thread_state();
2268 // set_thread_state(_thread_in_vm);
2269 // {
2270 // ThreadBlockInVM tbivm(this);
2271 // java_suspend_self()
2272 // }
2273 // set_thread_state(_thread_in_vm_trans);
2274 // if (safepoint) block;
2275 // set_thread_state(state);
2276 //
2277 // but that is pretty messy. Instead we just go with the way the
2278 // code has worked before and note that this is the only path to
2279 // java_suspend_self that doesn't put the thread in _thread_blocked
2280 // mode.
2281
2282 frame_anchor()->make_walkable(this);
2283 java_suspend_self();
2284
2285 // We might be here for reasons in addition to the self-suspend request
2286 // so check for other async requests.
2287 }
2288
2289 if (check_asyncs) {
2290 check_and_handle_async_exceptions();
2291 }
2292 #if INCLUDE_TRACE
2293 if (is_trace_suspend()) {
2294 TRACE_SUSPEND_THREAD(this);
2295 }
2296 #endif
2297 }
2298
2299 void JavaThread::send_thread_stop(oop java_throwable) {
2300 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2301 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2302 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2303
2304 // Do not throw asynchronous exceptions against the compiler thread
2305 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2306 if (!can_call_java()) return;
2307
2308 {
2309 // Actually throw the Throwable against the target Thread - however
2310 // only if there is no thread death exception installed already.
2311 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2312 // If the topmost frame is a runtime stub, then we are calling into
2313 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2314 // must deoptimize the caller before continuing, as the compiled exception handler table
2315 // may not be valid
2316 if (has_last_Java_frame()) {
2317 frame f = last_frame();
2318 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2319 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2320 RegisterMap reg_map(this, UseBiasedLocking);
2321 frame compiled_frame = f.sender(®_map);
2322 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2323 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2324 }
2325 }
2326 }
2327
2328 // Set async. pending exception in thread.
2329 set_pending_async_exception(java_throwable);
2330
2331 if (log_is_enabled(Info, exceptions)) {
2332 ResourceMark rm;
2333 log_info(exceptions)("Pending Async. exception installed of type: %s",
2334 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2335 }
2336 // for AbortVMOnException flag
2337 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2338 }
2339 }
2340
2341
2342 // Interrupt thread so it will wake up from a potential wait()
2343 Thread::interrupt(this);
2344 }
2345
2346 // External suspension mechanism.
2347 //
2348 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2349 // to any VM_locks and it is at a transition
2350 // Self-suspension will happen on the transition out of the vm.
2351 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2352 //
2353 // Guarantees on return:
2354 // + Target thread will not execute any new bytecode (that's why we need to
2355 // force a safepoint)
2356 // + Target thread will not enter any new monitors
2357 //
2358 void JavaThread::java_suspend() {
2359 ThreadsListHandle tlh;
2360 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2361 return;
2362 }
2363
2364 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2365 if (!is_external_suspend()) {
2366 // a racing resume has cancelled us; bail out now
2367 return;
2368 }
2369
2370 // suspend is done
2371 uint32_t debug_bits = 0;
2372 // Warning: is_ext_suspend_completed() may temporarily drop the
2373 // SR_lock to allow the thread to reach a stable thread state if
2374 // it is currently in a transient thread state.
2375 if (is_ext_suspend_completed(false /* !called_by_wait */,
2376 SuspendRetryDelay, &debug_bits)) {
2377 return;
2378 }
2379 }
2380
2381 VM_ThreadSuspend vm_suspend;
2382 VMThread::execute(&vm_suspend);
2383 }
2384
2385 // Part II of external suspension.
2386 // A JavaThread self suspends when it detects a pending external suspend
2387 // request. This is usually on transitions. It is also done in places
2388 // where continuing to the next transition would surprise the caller,
2389 // e.g., monitor entry.
2390 //
2391 // Returns the number of times that the thread self-suspended.
2392 //
2393 // Note: DO NOT call java_suspend_self() when you just want to block current
2394 // thread. java_suspend_self() is the second stage of cooperative
2395 // suspension for external suspend requests and should only be used
2396 // to complete an external suspend request.
2397 //
2398 int JavaThread::java_suspend_self() {
2399 int ret = 0;
2400
2401 // we are in the process of exiting so don't suspend
2402 if (is_exiting()) {
2403 clear_external_suspend();
2404 return ret;
2405 }
2406
2407 assert(_anchor.walkable() ||
2408 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2409 "must have walkable stack");
2410
2411 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2412
2413 assert(!this->is_ext_suspended(),
2414 "a thread trying to self-suspend should not already be suspended");
2415
2416 if (this->is_suspend_equivalent()) {
2417 // If we are self-suspending as a result of the lifting of a
2418 // suspend equivalent condition, then the suspend_equivalent
2419 // flag is not cleared until we set the ext_suspended flag so
2420 // that wait_for_ext_suspend_completion() returns consistent
2421 // results.
2422 this->clear_suspend_equivalent();
2423 }
2424
2425 // A racing resume may have cancelled us before we grabbed SR_lock
2426 // above. Or another external suspend request could be waiting for us
2427 // by the time we return from SR_lock()->wait(). The thread
2428 // that requested the suspension may already be trying to walk our
2429 // stack and if we return now, we can change the stack out from under
2430 // it. This would be a "bad thing (TM)" and cause the stack walker
2431 // to crash. We stay self-suspended until there are no more pending
2432 // external suspend requests.
2433 while (is_external_suspend()) {
2434 ret++;
2435 this->set_ext_suspended();
2436
2437 // _ext_suspended flag is cleared by java_resume()
2438 while (is_ext_suspended()) {
2439 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2440 }
2441 }
2442
2443 return ret;
2444 }
2445
2446 #ifdef ASSERT
2447 // verify the JavaThread has not yet been published in the Threads::list, and
2448 // hence doesn't need protection from concurrent access at this stage
2449 void JavaThread::verify_not_published() {
2450 ThreadsListHandle tlh;
2451 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2452 }
2453 #endif
2454
2455 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2456 // progress or when _suspend_flags is non-zero.
2457 // Current thread needs to self-suspend if there is a suspend request and/or
2458 // block if a safepoint is in progress.
2459 // Async exception ISN'T checked.
2460 // Note only the ThreadInVMfromNative transition can call this function
2461 // directly and when thread state is _thread_in_native_trans
2462 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2463 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2464
2465 JavaThread *curJT = JavaThread::current();
2466 bool do_self_suspend = thread->is_external_suspend();
2467
2468 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2469
2470 // If JNIEnv proxies are allowed, don't self-suspend if the target
2471 // thread is not the current thread. In older versions of jdbx, jdbx
2472 // threads could call into the VM with another thread's JNIEnv so we
2473 // can be here operating on behalf of a suspended thread (4432884).
2474 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2475 JavaThreadState state = thread->thread_state();
2476
2477 // We mark this thread_blocked state as a suspend-equivalent so
2478 // that a caller to is_ext_suspend_completed() won't be confused.
2479 // The suspend-equivalent state is cleared by java_suspend_self().
2480 thread->set_suspend_equivalent();
2481
2482 // If the safepoint code sees the _thread_in_native_trans state, it will
2483 // wait until the thread changes to other thread state. There is no
2484 // guarantee on how soon we can obtain the SR_lock and complete the
2485 // self-suspend request. It would be a bad idea to let safepoint wait for
2486 // too long. Temporarily change the state to _thread_blocked to
2487 // let the VM thread know that this thread is ready for GC. The problem
2488 // of changing thread state is that safepoint could happen just after
2489 // java_suspend_self() returns after being resumed, and VM thread will
2490 // see the _thread_blocked state. We must check for safepoint
2491 // after restoring the state and make sure we won't leave while a safepoint
2492 // is in progress.
2493 thread->set_thread_state(_thread_blocked);
2494 thread->java_suspend_self();
2495 thread->set_thread_state(state);
2496
2497 InterfaceSupport::serialize_thread_state_with_handler(thread);
2498 }
2499
2500 SafepointMechanism::block_if_requested(curJT);
2501
2502 if (thread->is_deopt_suspend()) {
2503 thread->clear_deopt_suspend();
2504 RegisterMap map(thread, false);
2505 frame f = thread->last_frame();
2506 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2507 f = f.sender(&map);
2508 }
2509 if (f.id() == thread->must_deopt_id()) {
2510 thread->clear_must_deopt_id();
2511 f.deoptimize(thread);
2512 } else {
2513 fatal("missed deoptimization!");
2514 }
2515 }
2516 #if INCLUDE_TRACE
2517 if (thread->is_trace_suspend()) {
2518 TRACE_SUSPEND_THREAD(thread);
2519 }
2520 #endif
2521 }
2522
2523 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2524 // progress or when _suspend_flags is non-zero.
2525 // Current thread needs to self-suspend if there is a suspend request and/or
2526 // block if a safepoint is in progress.
2527 // Also check for pending async exception (not including unsafe access error).
2528 // Note only the native==>VM/Java barriers can call this function and when
2529 // thread state is _thread_in_native_trans.
2530 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2531 check_safepoint_and_suspend_for_native_trans(thread);
2532
2533 if (thread->has_async_exception()) {
2534 // We are in _thread_in_native_trans state, don't handle unsafe
2535 // access error since that may block.
2536 thread->check_and_handle_async_exceptions(false);
2537 }
2538 }
2539
2540 // This is a variant of the normal
2541 // check_special_condition_for_native_trans with slightly different
2542 // semantics for use by critical native wrappers. It does all the
2543 // normal checks but also performs the transition back into
2544 // thread_in_Java state. This is required so that critical natives
2545 // can potentially block and perform a GC if they are the last thread
2546 // exiting the GCLocker.
2547 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2548 check_special_condition_for_native_trans(thread);
2549
2550 // Finish the transition
2551 thread->set_thread_state(_thread_in_Java);
2552
2553 if (thread->do_critical_native_unlock()) {
2554 ThreadInVMfromJavaNoAsyncException tiv(thread);
2555 GCLocker::unlock_critical(thread);
2556 thread->clear_critical_native_unlock();
2557 }
2558 }
2559
2560 // We need to guarantee the Threads_lock here, since resumes are not
2561 // allowed during safepoint synchronization
2562 // Can only resume from an external suspension
2563 void JavaThread::java_resume() {
2564 assert_locked_or_safepoint(Threads_lock);
2565
2566 // Sanity check: thread is gone, has started exiting or the thread
2567 // was not externally suspended.
2568 ThreadsListHandle tlh;
2569 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2570 return;
2571 }
2572
2573 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2574
2575 clear_external_suspend();
2576
2577 if (is_ext_suspended()) {
2578 clear_ext_suspended();
2579 SR_lock()->notify_all();
2580 }
2581 }
2582
2583 size_t JavaThread::_stack_red_zone_size = 0;
2584 size_t JavaThread::_stack_yellow_zone_size = 0;
2585 size_t JavaThread::_stack_reserved_zone_size = 0;
2586 size_t JavaThread::_stack_shadow_zone_size = 0;
2587
2588 void JavaThread::create_stack_guard_pages() {
2589 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2590 address low_addr = stack_end();
2591 size_t len = stack_guard_zone_size();
2592
2593 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2594 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2595
2596 int must_commit = os::must_commit_stack_guard_pages();
2597 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2598
2599 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2600 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2601 return;
2602 }
2603
2604 if (os::guard_memory((char *) low_addr, len)) {
2605 _stack_guard_state = stack_guard_enabled;
2606 } else {
2607 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2608 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2609 if (os::uncommit_memory((char *) low_addr, len)) {
2610 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2611 }
2612 return;
2613 }
2614
2615 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2616 PTR_FORMAT "-" PTR_FORMAT ".",
2617 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2618 }
2619
2620 void JavaThread::remove_stack_guard_pages() {
2621 assert(Thread::current() == this, "from different thread");
2622 if (_stack_guard_state == stack_guard_unused) return;
2623 address low_addr = stack_end();
2624 size_t len = stack_guard_zone_size();
2625
2626 if (os::must_commit_stack_guard_pages()) {
2627 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2628 _stack_guard_state = stack_guard_unused;
2629 } else {
2630 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2631 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2632 return;
2633 }
2634 } else {
2635 if (_stack_guard_state == stack_guard_unused) return;
2636 if (os::unguard_memory((char *) low_addr, len)) {
2637 _stack_guard_state = stack_guard_unused;
2638 } else {
2639 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2640 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2641 return;
2642 }
2643 }
2644
2645 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2646 PTR_FORMAT "-" PTR_FORMAT ".",
2647 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2648 }
2649
2650 void JavaThread::enable_stack_reserved_zone() {
2651 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2652 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2653
2654 // The base notation is from the stack's point of view, growing downward.
2655 // We need to adjust it to work correctly with guard_memory()
2656 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2657
2658 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2659 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2660
2661 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2662 _stack_guard_state = stack_guard_enabled;
2663 } else {
2664 warning("Attempt to guard stack reserved zone failed.");
2665 }
2666 enable_register_stack_guard();
2667 }
2668
2669 void JavaThread::disable_stack_reserved_zone() {
2670 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2671 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2672
2673 // Simply return if called for a thread that does not use guard pages.
2674 if (_stack_guard_state == stack_guard_unused) return;
2675
2676 // The base notation is from the stack's point of view, growing downward.
2677 // We need to adjust it to work correctly with guard_memory()
2678 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2679
2680 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2681 _stack_guard_state = stack_guard_reserved_disabled;
2682 } else {
2683 warning("Attempt to unguard stack reserved zone failed.");
2684 }
2685 disable_register_stack_guard();
2686 }
2687
2688 void JavaThread::enable_stack_yellow_reserved_zone() {
2689 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2690 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2691
2692 // The base notation is from the stacks point of view, growing downward.
2693 // We need to adjust it to work correctly with guard_memory()
2694 address base = stack_red_zone_base();
2695
2696 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2697 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2698
2699 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2700 _stack_guard_state = stack_guard_enabled;
2701 } else {
2702 warning("Attempt to guard stack yellow zone failed.");
2703 }
2704 enable_register_stack_guard();
2705 }
2706
2707 void JavaThread::disable_stack_yellow_reserved_zone() {
2708 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2709 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2710
2711 // Simply return if called for a thread that does not use guard pages.
2712 if (_stack_guard_state == stack_guard_unused) return;
2713
2714 // The base notation is from the stacks point of view, growing downward.
2715 // We need to adjust it to work correctly with guard_memory()
2716 address base = stack_red_zone_base();
2717
2718 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2719 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2720 } else {
2721 warning("Attempt to unguard stack yellow zone failed.");
2722 }
2723 disable_register_stack_guard();
2724 }
2725
2726 void JavaThread::enable_stack_red_zone() {
2727 // The base notation is from the stacks point of view, growing downward.
2728 // We need to adjust it to work correctly with guard_memory()
2729 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2730 address base = stack_red_zone_base() - stack_red_zone_size();
2731
2732 guarantee(base < stack_base(), "Error calculating stack red zone");
2733 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2734
2735 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2736 warning("Attempt to guard stack red zone failed.");
2737 }
2738 }
2739
2740 void JavaThread::disable_stack_red_zone() {
2741 // The base notation is from the stacks point of view, growing downward.
2742 // We need to adjust it to work correctly with guard_memory()
2743 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2744 address base = stack_red_zone_base() - stack_red_zone_size();
2745 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2746 warning("Attempt to unguard stack red zone failed.");
2747 }
2748 }
2749
2750 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2751 // ignore is there is no stack
2752 if (!has_last_Java_frame()) return;
2753 // traverse the stack frames. Starts from top frame.
2754 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2755 frame* fr = fst.current();
2756 f(fr, fst.register_map());
2757 }
2758 }
2759
2760
2761 #ifndef PRODUCT
2762 // Deoptimization
2763 // Function for testing deoptimization
2764 void JavaThread::deoptimize() {
2765 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2766 StackFrameStream fst(this, UseBiasedLocking);
2767 bool deopt = false; // Dump stack only if a deopt actually happens.
2768 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2769 // Iterate over all frames in the thread and deoptimize
2770 for (; !fst.is_done(); fst.next()) {
2771 if (fst.current()->can_be_deoptimized()) {
2772
2773 if (only_at) {
2774 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2775 // consists of comma or carriage return separated numbers so
2776 // search for the current bci in that string.
2777 address pc = fst.current()->pc();
2778 nmethod* nm = (nmethod*) fst.current()->cb();
2779 ScopeDesc* sd = nm->scope_desc_at(pc);
2780 char buffer[8];
2781 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2782 size_t len = strlen(buffer);
2783 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2784 while (found != NULL) {
2785 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2786 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2787 // Check that the bci found is bracketed by terminators.
2788 break;
2789 }
2790 found = strstr(found + 1, buffer);
2791 }
2792 if (!found) {
2793 continue;
2794 }
2795 }
2796
2797 if (DebugDeoptimization && !deopt) {
2798 deopt = true; // One-time only print before deopt
2799 tty->print_cr("[BEFORE Deoptimization]");
2800 trace_frames();
2801 trace_stack();
2802 }
2803 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2804 }
2805 }
2806
2807 if (DebugDeoptimization && deopt) {
2808 tty->print_cr("[AFTER Deoptimization]");
2809 trace_frames();
2810 }
2811 }
2812
2813
2814 // Make zombies
2815 void JavaThread::make_zombies() {
2816 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2817 if (fst.current()->can_be_deoptimized()) {
2818 // it is a Java nmethod
2819 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2820 nm->make_not_entrant();
2821 }
2822 }
2823 }
2824 #endif // PRODUCT
2825
2826
2827 void JavaThread::deoptimized_wrt_marked_nmethods() {
2828 if (!has_last_Java_frame()) return;
2829 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2830 StackFrameStream fst(this, UseBiasedLocking);
2831 for (; !fst.is_done(); fst.next()) {
2832 if (fst.current()->should_be_deoptimized()) {
2833 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2834 }
2835 }
2836 }
2837
2838
2839 // If the caller is a NamedThread, then remember, in the current scope,
2840 // the given JavaThread in its _processed_thread field.
2841 class RememberProcessedThread: public StackObj {
2842 NamedThread* _cur_thr;
2843 public:
2844 RememberProcessedThread(JavaThread* jthr) {
2845 Thread* thread = Thread::current();
2846 if (thread->is_Named_thread()) {
2847 _cur_thr = (NamedThread *)thread;
2848 _cur_thr->set_processed_thread(jthr);
2849 } else {
2850 _cur_thr = NULL;
2851 }
2852 }
2853
2854 ~RememberProcessedThread() {
2855 if (_cur_thr) {
2856 _cur_thr->set_processed_thread(NULL);
2857 }
2858 }
2859 };
2860
2861 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2862 // Verify that the deferred card marks have been flushed.
2863 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2864
2865 // Traverse the GCHandles
2866 Thread::oops_do(f, cf);
2867
2868 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2869
2870 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2871 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2872
2873 if (has_last_Java_frame()) {
2874 // Record JavaThread to GC thread
2875 RememberProcessedThread rpt(this);
2876
2877 // Traverse the privileged stack
2878 if (_privileged_stack_top != NULL) {
2879 _privileged_stack_top->oops_do(f);
2880 }
2881
2882 // traverse the registered growable array
2883 if (_array_for_gc != NULL) {
2884 for (int index = 0; index < _array_for_gc->length(); index++) {
2885 f->do_oop(_array_for_gc->adr_at(index));
2886 }
2887 }
2888
2889 // Traverse the monitor chunks
2890 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2891 chunk->oops_do(f);
2892 }
2893
2894 // Traverse the execution stack
2895 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896 fst.current()->oops_do(f, cf, fst.register_map());
2897 }
2898 }
2899
2900 // callee_target is never live across a gc point so NULL it here should
2901 // it still contain a methdOop.
2902
2903 set_callee_target(NULL);
2904
2905 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2906 // If we have deferred set_locals there might be oops waiting to be
2907 // written
2908 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2909 if (list != NULL) {
2910 for (int i = 0; i < list->length(); i++) {
2911 list->at(i)->oops_do(f);
2912 }
2913 }
2914
2915 // Traverse instance variables at the end since the GC may be moving things
2916 // around using this function
2917 f->do_oop((oop*) &_threadObj);
2918 f->do_oop((oop*) &_vm_result);
2919 f->do_oop((oop*) &_exception_oop);
2920 f->do_oop((oop*) &_pending_async_exception);
2921
2922 if (jvmti_thread_state() != NULL) {
2923 jvmti_thread_state()->oops_do(f);
2924 }
2925 }
2926
2927 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2928 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2929 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2930
2931 if (has_last_Java_frame()) {
2932 // Traverse the execution stack
2933 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2934 fst.current()->nmethods_do(cf);
2935 }
2936 }
2937 }
2938
2939 void JavaThread::metadata_do(void f(Metadata*)) {
2940 if (has_last_Java_frame()) {
2941 // Traverse the execution stack to call f() on the methods in the stack
2942 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2943 fst.current()->metadata_do(f);
2944 }
2945 } else if (is_Compiler_thread()) {
2946 // need to walk ciMetadata in current compile tasks to keep alive.
2947 CompilerThread* ct = (CompilerThread*)this;
2948 if (ct->env() != NULL) {
2949 ct->env()->metadata_do(f);
2950 }
2951 if (ct->task() != NULL) {
2952 ct->task()->metadata_do(f);
2953 }
2954 }
2955 }
2956
2957 // Printing
2958 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2959 switch (_thread_state) {
2960 case _thread_uninitialized: return "_thread_uninitialized";
2961 case _thread_new: return "_thread_new";
2962 case _thread_new_trans: return "_thread_new_trans";
2963 case _thread_in_native: return "_thread_in_native";
2964 case _thread_in_native_trans: return "_thread_in_native_trans";
2965 case _thread_in_vm: return "_thread_in_vm";
2966 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2967 case _thread_in_Java: return "_thread_in_Java";
2968 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2969 case _thread_blocked: return "_thread_blocked";
2970 case _thread_blocked_trans: return "_thread_blocked_trans";
2971 default: return "unknown thread state";
2972 }
2973 }
2974
2975 #ifndef PRODUCT
2976 void JavaThread::print_thread_state_on(outputStream *st) const {
2977 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2978 };
2979 void JavaThread::print_thread_state() const {
2980 print_thread_state_on(tty);
2981 }
2982 #endif // PRODUCT
2983
2984 // Called by Threads::print() for VM_PrintThreads operation
2985 void JavaThread::print_on(outputStream *st) const {
2986 st->print_raw("\"");
2987 st->print_raw(get_thread_name());
2988 st->print_raw("\" ");
2989 oop thread_oop = threadObj();
2990 if (thread_oop != NULL) {
2991 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2992 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2993 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2994 }
2995 Thread::print_on(st);
2996 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2997 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2998 if (thread_oop != NULL) {
2999 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3000 }
3001 #ifndef PRODUCT
3002 print_thread_state_on(st);
3003 _safepoint_state->print_on(st);
3004 #endif // PRODUCT
3005 if (is_Compiler_thread()) {
3006 CompilerThread* ct = (CompilerThread*)this;
3007 if (ct->task() != NULL) {
3008 st->print(" Compiling: ");
3009 ct->task()->print(st, NULL, true, false);
3010 } else {
3011 st->print(" No compile task");
3012 }
3013 st->cr();
3014 }
3015 }
3016
3017 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3018 st->print("%s", get_thread_name_string(buf, buflen));
3019 }
3020
3021 // Called by fatal error handler. The difference between this and
3022 // JavaThread::print() is that we can't grab lock or allocate memory.
3023 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3024 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3025 oop thread_obj = threadObj();
3026 if (thread_obj != NULL) {
3027 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3028 }
3029 st->print(" [");
3030 st->print("%s", _get_thread_state_name(_thread_state));
3031 if (osthread()) {
3032 st->print(", id=%d", osthread()->thread_id());
3033 }
3034 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3035 p2i(stack_end()), p2i(stack_base()));
3036 st->print("]");
3037
3038 if (_threads_hazard_ptr != NULL) {
3039 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3040 }
3041 if (_nested_threads_hazard_ptr != NULL) {
3042 print_nested_threads_hazard_ptrs_on(st);
3043 }
3044 return;
3045 }
3046
3047 // Verification
3048
3049 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3050
3051 void JavaThread::verify() {
3052 // Verify oops in the thread.
3053 oops_do(&VerifyOopClosure::verify_oop, NULL);
3054
3055 // Verify the stack frames.
3056 frames_do(frame_verify);
3057 }
3058
3059 // CR 6300358 (sub-CR 2137150)
3060 // Most callers of this method assume that it can't return NULL but a
3061 // thread may not have a name whilst it is in the process of attaching to
3062 // the VM - see CR 6412693, and there are places where a JavaThread can be
3063 // seen prior to having it's threadObj set (eg JNI attaching threads and
3064 // if vm exit occurs during initialization). These cases can all be accounted
3065 // for such that this method never returns NULL.
3066 const char* JavaThread::get_thread_name() const {
3067 #ifdef ASSERT
3068 // early safepoints can hit while current thread does not yet have TLS
3069 if (!SafepointSynchronize::is_at_safepoint()) {
3070 Thread *cur = Thread::current();
3071 if (!(cur->is_Java_thread() && cur == this)) {
3072 // Current JavaThreads are allowed to get their own name without
3073 // the Threads_lock.
3074 assert_locked_or_safepoint(Threads_lock);
3075 }
3076 }
3077 #endif // ASSERT
3078 return get_thread_name_string();
3079 }
3080
3081 // Returns a non-NULL representation of this thread's name, or a suitable
3082 // descriptive string if there is no set name
3083 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3084 const char* name_str;
3085 oop thread_obj = threadObj();
3086 if (thread_obj != NULL) {
3087 oop name = java_lang_Thread::name(thread_obj);
3088 if (name != NULL) {
3089 if (buf == NULL) {
3090 name_str = java_lang_String::as_utf8_string(name);
3091 } else {
3092 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3093 }
3094 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3095 name_str = "<no-name - thread is attaching>";
3096 } else {
3097 name_str = Thread::name();
3098 }
3099 } else {
3100 name_str = Thread::name();
3101 }
3102 assert(name_str != NULL, "unexpected NULL thread name");
3103 return name_str;
3104 }
3105
3106
3107 const char* JavaThread::get_threadgroup_name() const {
3108 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3109 oop thread_obj = threadObj();
3110 if (thread_obj != NULL) {
3111 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3112 if (thread_group != NULL) {
3113 // ThreadGroup.name can be null
3114 return java_lang_ThreadGroup::name(thread_group);
3115 }
3116 }
3117 return NULL;
3118 }
3119
3120 const char* JavaThread::get_parent_name() const {
3121 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3122 oop thread_obj = threadObj();
3123 if (thread_obj != NULL) {
3124 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3125 if (thread_group != NULL) {
3126 oop parent = java_lang_ThreadGroup::parent(thread_group);
3127 if (parent != NULL) {
3128 // ThreadGroup.name can be null
3129 return java_lang_ThreadGroup::name(parent);
3130 }
3131 }
3132 }
3133 return NULL;
3134 }
3135
3136 ThreadPriority JavaThread::java_priority() const {
3137 oop thr_oop = threadObj();
3138 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3139 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3140 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3141 return priority;
3142 }
3143
3144 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3145
3146 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3147 // Link Java Thread object <-> C++ Thread
3148
3149 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3150 // and put it into a new Handle. The Handle "thread_oop" can then
3151 // be used to pass the C++ thread object to other methods.
3152
3153 // Set the Java level thread object (jthread) field of the
3154 // new thread (a JavaThread *) to C++ thread object using the
3155 // "thread_oop" handle.
3156
3157 // Set the thread field (a JavaThread *) of the
3158 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3159
3160 Handle thread_oop(Thread::current(),
3161 JNIHandles::resolve_non_null(jni_thread));
3162 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3163 "must be initialized");
3164 set_threadObj(thread_oop());
3165 java_lang_Thread::set_thread(thread_oop(), this);
3166
3167 if (prio == NoPriority) {
3168 prio = java_lang_Thread::priority(thread_oop());
3169 assert(prio != NoPriority, "A valid priority should be present");
3170 }
3171
3172 // Push the Java priority down to the native thread; needs Threads_lock
3173 Thread::set_priority(this, prio);
3174
3175 prepare_ext();
3176
3177 // Add the new thread to the Threads list and set it in motion.
3178 // We must have threads lock in order to call Threads::add.
3179 // It is crucial that we do not block before the thread is
3180 // added to the Threads list for if a GC happens, then the java_thread oop
3181 // will not be visited by GC.
3182 Threads::add(this);
3183 }
3184
3185 oop JavaThread::current_park_blocker() {
3186 // Support for JSR-166 locks
3187 oop thread_oop = threadObj();
3188 if (thread_oop != NULL &&
3189 JDK_Version::current().supports_thread_park_blocker()) {
3190 return java_lang_Thread::park_blocker(thread_oop);
3191 }
3192 return NULL;
3193 }
3194
3195
3196 void JavaThread::print_stack_on(outputStream* st) {
3197 if (!has_last_Java_frame()) return;
3198 ResourceMark rm;
3199 HandleMark hm;
3200
3201 RegisterMap reg_map(this);
3202 vframe* start_vf = last_java_vframe(®_map);
3203 int count = 0;
3204 for (vframe* f = start_vf; f; f = f->sender()) {
3205 if (f->is_java_frame()) {
3206 javaVFrame* jvf = javaVFrame::cast(f);
3207 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3208
3209 // Print out lock information
3210 if (JavaMonitorsInStackTrace) {
3211 jvf->print_lock_info_on(st, count);
3212 }
3213 } else {
3214 // Ignore non-Java frames
3215 }
3216
3217 // Bail-out case for too deep stacks
3218 count++;
3219 if (MaxJavaStackTraceDepth == count) return;
3220 }
3221 }
3222
3223
3224 // JVMTI PopFrame support
3225 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3226 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3227 if (in_bytes(size_in_bytes) != 0) {
3228 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3229 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3230 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3231 }
3232 }
3233
3234 void* JavaThread::popframe_preserved_args() {
3235 return _popframe_preserved_args;
3236 }
3237
3238 ByteSize JavaThread::popframe_preserved_args_size() {
3239 return in_ByteSize(_popframe_preserved_args_size);
3240 }
3241
3242 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3243 int sz = in_bytes(popframe_preserved_args_size());
3244 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3245 return in_WordSize(sz / wordSize);
3246 }
3247
3248 void JavaThread::popframe_free_preserved_args() {
3249 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3250 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3251 _popframe_preserved_args = NULL;
3252 _popframe_preserved_args_size = 0;
3253 }
3254
3255 #ifndef PRODUCT
3256
3257 void JavaThread::trace_frames() {
3258 tty->print_cr("[Describe stack]");
3259 int frame_no = 1;
3260 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3261 tty->print(" %d. ", frame_no++);
3262 fst.current()->print_value_on(tty, this);
3263 tty->cr();
3264 }
3265 }
3266
3267 class PrintAndVerifyOopClosure: public OopClosure {
3268 protected:
3269 template <class T> inline void do_oop_work(T* p) {
3270 oop obj = oopDesc::load_decode_heap_oop(p);
3271 if (obj == NULL) return;
3272 tty->print(INTPTR_FORMAT ": ", p2i(p));
3273 if (oopDesc::is_oop_or_null(obj)) {
3274 if (obj->is_objArray()) {
3275 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3276 } else {
3277 obj->print();
3278 }
3279 } else {
3280 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3281 }
3282 tty->cr();
3283 }
3284 public:
3285 virtual void do_oop(oop* p) { do_oop_work(p); }
3286 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3287 };
3288
3289
3290 static void oops_print(frame* f, const RegisterMap *map) {
3291 PrintAndVerifyOopClosure print;
3292 f->print_value();
3293 f->oops_do(&print, NULL, (RegisterMap*)map);
3294 }
3295
3296 // Print our all the locations that contain oops and whether they are
3297 // valid or not. This useful when trying to find the oldest frame
3298 // where an oop has gone bad since the frame walk is from youngest to
3299 // oldest.
3300 void JavaThread::trace_oops() {
3301 tty->print_cr("[Trace oops]");
3302 frames_do(oops_print);
3303 }
3304
3305
3306 #ifdef ASSERT
3307 // Print or validate the layout of stack frames
3308 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3309 ResourceMark rm;
3310 PRESERVE_EXCEPTION_MARK;
3311 FrameValues values;
3312 int frame_no = 0;
3313 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3314 fst.current()->describe(values, ++frame_no);
3315 if (depth == frame_no) break;
3316 }
3317 if (validate_only) {
3318 values.validate();
3319 } else {
3320 tty->print_cr("[Describe stack layout]");
3321 values.print(this);
3322 }
3323 }
3324 #endif
3325
3326 void JavaThread::trace_stack_from(vframe* start_vf) {
3327 ResourceMark rm;
3328 int vframe_no = 1;
3329 for (vframe* f = start_vf; f; f = f->sender()) {
3330 if (f->is_java_frame()) {
3331 javaVFrame::cast(f)->print_activation(vframe_no++);
3332 } else {
3333 f->print();
3334 }
3335 if (vframe_no > StackPrintLimit) {
3336 tty->print_cr("...<more frames>...");
3337 return;
3338 }
3339 }
3340 }
3341
3342
3343 void JavaThread::trace_stack() {
3344 if (!has_last_Java_frame()) return;
3345 ResourceMark rm;
3346 HandleMark hm;
3347 RegisterMap reg_map(this);
3348 trace_stack_from(last_java_vframe(®_map));
3349 }
3350
3351
3352 #endif // PRODUCT
3353
3354
3355 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3356 assert(reg_map != NULL, "a map must be given");
3357 frame f = last_frame();
3358 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3359 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3360 }
3361 return NULL;
3362 }
3363
3364
3365 Klass* JavaThread::security_get_caller_class(int depth) {
3366 vframeStream vfst(this);
3367 vfst.security_get_caller_frame(depth);
3368 if (!vfst.at_end()) {
3369 return vfst.method()->method_holder();
3370 }
3371 return NULL;
3372 }
3373
3374 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3375 assert(thread->is_Compiler_thread(), "must be compiler thread");
3376 CompileBroker::compiler_thread_loop();
3377 }
3378
3379 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3380 NMethodSweeper::sweeper_loop();
3381 }
3382
3383 // Create a CompilerThread
3384 CompilerThread::CompilerThread(CompileQueue* queue,
3385 CompilerCounters* counters)
3386 : JavaThread(&compiler_thread_entry) {
3387 _env = NULL;
3388 _log = NULL;
3389 _task = NULL;
3390 _queue = queue;
3391 _counters = counters;
3392 _buffer_blob = NULL;
3393 _compiler = NULL;
3394
3395 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3396 resource_area()->bias_to(mtCompiler);
3397
3398 #ifndef PRODUCT
3399 _ideal_graph_printer = NULL;
3400 #endif
3401 }
3402
3403 bool CompilerThread::can_call_java() const {
3404 return _compiler != NULL && _compiler->is_jvmci();
3405 }
3406
3407 // Create sweeper thread
3408 CodeCacheSweeperThread::CodeCacheSweeperThread()
3409 : JavaThread(&sweeper_thread_entry) {
3410 _scanned_compiled_method = NULL;
3411 }
3412
3413 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3414 JavaThread::oops_do(f, cf);
3415 if (_scanned_compiled_method != NULL && cf != NULL) {
3416 // Safepoints can occur when the sweeper is scanning an nmethod so
3417 // process it here to make sure it isn't unloaded in the middle of
3418 // a scan.
3419 cf->do_code_blob(_scanned_compiled_method);
3420 }
3421 }
3422
3423 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3424 JavaThread::nmethods_do(cf);
3425 if (_scanned_compiled_method != NULL && cf != NULL) {
3426 // Safepoints can occur when the sweeper is scanning an nmethod so
3427 // process it here to make sure it isn't unloaded in the middle of
3428 // a scan.
3429 cf->do_code_blob(_scanned_compiled_method);
3430 }
3431 }
3432
3433
3434 // ======= Threads ========
3435
3436 // The Threads class links together all active threads, and provides
3437 // operations over all threads. It is protected by its own Mutex
3438 // lock, which is also used in other contexts to protect thread
3439 // operations from having the thread being operated on from exiting
3440 // and going away unexpectedly (e.g., safepoint synchronization)
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 Monitor* Threads::_smr_delete_lock =
3449 new Monitor(Monitor::special, "smr_delete_lock",
3450 false /* allow_vm_block */,
3451 Monitor::_safepoint_check_never);
3452 // The '_cnt', '_max' and '_times" fields are enabled via
3453 // -XX:+EnableThreadSMRStatistics:
3454 uint Threads::_smr_delete_lock_wait_cnt = 0;
3455 uint Threads::_smr_delete_lock_wait_max = 0;
3456 volatile jint Threads::_smr_delete_notify = 0;
3457 volatile jint Threads::_smr_deleted_thread_cnt = 0;
3458 volatile jint Threads::_smr_deleted_thread_time_max = 0;
3459 volatile jint Threads::_smr_deleted_thread_times = 0;
3460 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
3461 long Threads::_smr_java_thread_list_alloc_cnt = 1;
3462 long Threads::_smr_java_thread_list_free_cnt = 0;
3463 uint Threads::_smr_java_thread_list_max = 0;
3464 uint Threads::_smr_nested_thread_list_max = 0;
3465 volatile jint Threads::_smr_tlh_cnt = 0;
3466 volatile jint Threads::_smr_tlh_time_max = 0;
3467 volatile jint Threads::_smr_tlh_times = 0;
3468 ThreadsList* Threads::_smr_to_delete_list = NULL;
3469 uint Threads::_smr_to_delete_list_cnt = 0;
3470 uint Threads::_smr_to_delete_list_max = 0;
3471
3472 #ifdef ASSERT
3473 bool Threads::_vm_complete = false;
3474 #endif
3475
3476 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3477 Prefetch::read((void*)addr, prefetch_interval);
3478 return *addr;
3479 }
3480
3481 // Possibly the ugliest for loop the world has seen. C++ does not allow
3482 // multiple types in the declaration section of the for loop. In this case
3483 // we are only dealing with pointers and hence can cast them. It looks ugly
3484 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3485 #define DO_JAVA_THREADS(LIST, X) \
3486 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3487 *MACRO_list = (JavaThread*)(LIST), \
3488 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3489 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3490 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3491 MACRO_current_p != MACRO_end; \
3492 MACRO_current_p++, \
3493 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3494
3495 // All JavaThreads
3496 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X)
3497
3498 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3499 void Threads::threads_do(ThreadClosure* tc) {
3500 assert_locked_or_safepoint(Threads_lock);
3501 // ALL_JAVA_THREADS iterates through all JavaThreads
3502 ALL_JAVA_THREADS(p) {
3503 tc->do_thread(p);
3504 }
3505 // Someday we could have a table or list of all non-JavaThreads.
3506 // For now, just manually iterate through them.
3507 tc->do_thread(VMThread::vm_thread());
3508 Universe::heap()->gc_threads_do(tc);
3509 WatcherThread *wt = WatcherThread::watcher_thread();
3510 // Strictly speaking, the following NULL check isn't sufficient to make sure
3511 // the data for WatcherThread is still valid upon being examined. However,
3512 // considering that WatchThread terminates when the VM is on the way to
3513 // exit at safepoint, the chance of the above is extremely small. The right
3514 // way to prevent termination of WatcherThread would be to acquire
3515 // Terminator_lock, but we can't do that without violating the lock rank
3516 // checking in some cases.
3517 if (wt != NULL) {
3518 tc->do_thread(wt);
3519 }
3520
3521 // If CompilerThreads ever become non-JavaThreads, add them here
3522 }
3523
3524 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3525 int cp = Threads::thread_claim_parity();
3526 ALL_JAVA_THREADS(p) {
3527 if (p->claim_oops_do(is_par, cp)) {
3528 tc->do_thread(p);
3529 }
3530 }
3531 VMThread* vmt = VMThread::vm_thread();
3532 if (vmt->claim_oops_do(is_par, cp)) {
3533 tc->do_thread(vmt);
3534 }
3535 }
3536
3537 // The system initialization in the library has three phases.
3538 //
3539 // Phase 1: java.lang.System class initialization
3540 // java.lang.System is a primordial class loaded and initialized
3541 // by the VM early during startup. java.lang.System.<clinit>
3542 // only does registerNatives and keeps the rest of the class
3543 // initialization work later until thread initialization completes.
3544 //
3545 // System.initPhase1 initializes the system properties, the static
3546 // fields in, out, and err. Set up java signal handlers, OS-specific
3547 // system settings, and thread group of the main thread.
3548 static void call_initPhase1(TRAPS) {
3549 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3550 JavaValue result(T_VOID);
3551 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3552 vmSymbols::void_method_signature(), CHECK);
3553 }
3554
3555 // Phase 2. Module system initialization
3556 // This will initialize the module system. Only java.base classes
3557 // can be loaded until phase 2 completes.
3558 //
3559 // Call System.initPhase2 after the compiler initialization and jsr292
3560 // classes get initialized because module initialization runs a lot of java
3561 // code, that for performance reasons, should be compiled. Also, this will
3562 // enable the startup code to use lambda and other language features in this
3563 // phase and onward.
3564 //
3565 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3566 static void call_initPhase2(TRAPS) {
3567 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3568
3569 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3570
3571 JavaValue result(T_INT);
3572 JavaCallArguments args;
3573 args.push_int(DisplayVMOutputToStderr);
3574 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3575 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3576 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3577 if (result.get_jint() != JNI_OK) {
3578 vm_exit_during_initialization(); // no message or exception
3579 }
3580
3581 universe_post_module_init();
3582 }
3583
3584 // Phase 3. final setup - set security manager, system class loader and TCCL
3585 //
3586 // This will instantiate and set the security manager, set the system class
3587 // loader as well as the thread context class loader. The security manager
3588 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3589 // other modules or the application's classpath.
3590 static void call_initPhase3(TRAPS) {
3591 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3592 JavaValue result(T_VOID);
3593 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3594 vmSymbols::void_method_signature(), CHECK);
3595 }
3596
3597 // Safe Memory Reclamation (SMR) support:
3598 //
3599
3600 // Acquire a stable ThreadsList.
3601 //
3602 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) {
3603 assert(self != NULL, "sanity check");
3604 // acquire_stable_list_nested_path() will grab the Threads_lock
3605 // so let's make sure the ThreadsListHandle is in a safe place.
3606 // ThreadsListSetter cannot make this check on this code path.
3607 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3608
3609 if (self->get_threads_hazard_ptr() == NULL) {
3610 // The typical case is first.
3611 return acquire_stable_list_fast_path(self);
3612 }
3613
3614 // The nested case is rare.
3615 return acquire_stable_list_nested_path(self);
3616 }
3617
3618 // Fast path (and lock free) way to acquire a stable ThreadsList.
3619 //
3620 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) {
3621 assert(self != NULL, "sanity check");
3622 assert(self->get_threads_hazard_ptr() == NULL, "sanity check");
3623 assert(self->get_nested_threads_hazard_ptr() == NULL,
3624 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
3625
3626 ThreadsList* threads;
3627
3628 // Stable recording of a hazard ptr for SMR. This code does not use
3629 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr
3630 // fields is racy relative to code that uses those fields with locks.
3631 // OrderAccess and Atomic functions are used to deal with those races.
3632 //
3633 while (true) {
3634 threads = get_smr_java_thread_list();
3635
3636 // Publish a tagged hazard ptr to denote that the hazard ptr is not
3637 // yet verified as being stable. Due to the fence after the hazard
3638 // ptr write, it will be sequentially consistent w.r.t. the
3639 // sequentially consistent writes of the ThreadsList, even on
3640 // non-multiple copy atomic machines where stores can be observed
3641 // in different order from different observer threads.
3642 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads);
3643 self->set_threads_hazard_ptr(unverified_threads);
3644
3645 // If _smr_java_thread_list has changed, we have lost a race with
3646 // Threads::add() or Threads::remove() and have to try again.
3647 if (get_smr_java_thread_list() != threads) {
3648 continue;
3649 }
3650
3651 // We try to remove the tag which will verify the hazard ptr as
3652 // being stable. This exchange can race with a scanning thread
3653 // which might invalidate the tagged hazard ptr to keep it from
3654 // being followed to access JavaThread ptrs. If we lose the race,
3655 // we simply retry. If we win the race, then the stable hazard
3656 // ptr is officially published.
3657 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) {
3658 break;
3659 }
3660 }
3661
3662 // A stable hazard ptr has been published letting other threads know
3663 // that the ThreadsList and the JavaThreads reachable from this list
3664 // are protected and hence they should not be deleted until everyone
3665 // agrees it is safe to do so.
3666
3667 return threads;
3668 }
3669
3670 // Acquire a nested stable ThreadsList; this is rare so it uses
3671 // Threads_lock.
3672 //
3673 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) {
3674 assert(self != NULL, "sanity check");
3675 assert(self->get_threads_hazard_ptr() != NULL,
3676 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr");
3677
3678 // The thread already has a hazard ptr (ThreadsList ref) so we need
3679 // to create a nested ThreadsListHandle with the current ThreadsList
3680 // since it might be different than our current hazard ptr. The need
3681 // for a nested ThreadsListHandle is rare so we do this while holding
3682 // the Threads_lock so we don't race with the scanning code; the code
3683 // is so much simpler this way.
3684
3685 NestedThreadsList* node;
3686 {
3687 // Only grab the Threads_lock if we don't already own it.
3688 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3689 node = new NestedThreadsList(get_smr_java_thread_list());
3690 // We insert at the front of the list to match up with the delete
3691 // in release_stable_list().
3692 node->set_next(self->get_nested_threads_hazard_ptr());
3693 self->set_nested_threads_hazard_ptr(node);
3694 if (EnableThreadSMRStatistics) {
3695 self->inc_nested_threads_hazard_ptr_cnt();
3696 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) {
3697 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt();
3698 }
3699 }
3700 }
3701 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()));
3702
3703 return node->t_list();
3704 }
3705
3706 // Release a stable ThreadsList.
3707 //
3708 void Threads::release_stable_list(Thread *self) {
3709 assert(self != NULL, "sanity check");
3710 // release_stable_list_nested_path() will grab the Threads_lock
3711 // so let's make sure the ThreadsListHandle is in a safe place.
3712 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3713
3714 if (self->get_nested_threads_hazard_ptr() == NULL) {
3715 // The typical case is first.
3716 release_stable_list_fast_path(self);
3717 return;
3718 }
3719
3720 // The nested case is rare.
3721 release_stable_list_nested_path(self);
3722 }
3723
3724 // Fast path way to release a stable ThreadsList. The release portion
3725 // is lock-free, but the wake up portion is not.
3726 //
3727 void Threads::release_stable_list_fast_path(Thread *self) {
3728 assert(self != NULL, "sanity check");
3729 assert(self->get_threads_hazard_ptr() != NULL, "sanity check");
3730 assert(self->get_nested_threads_hazard_ptr() == NULL,
3731 "cannot have a nested hazard ptr when releasing a regular hazard ptr");
3732
3733 // After releasing the hazard ptr, other threads may go ahead and
3734 // free up some memory temporarily used by a ThreadsList snapshot.
3735 self->set_threads_hazard_ptr(NULL);
3736
3737 // We use double-check locking to reduce traffic on the system
3738 // wide smr_delete_lock.
3739 if (Threads::smr_delete_notify()) {
3740 // An exiting thread might be waiting in smr_delete(); we need to
3741 // check with smr_delete_lock to be sure.
3742 release_stable_list_wake_up((char *) "regular hazard ptr");
3743 }
3744 }
3745
3746 // Release a nested stable ThreadsList; this is rare so it uses
3747 // Threads_lock.
3748 //
3749 void Threads::release_stable_list_nested_path(Thread *self) {
3750 assert(self != NULL, "sanity check");
3751 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check");
3752 assert(self->get_threads_hazard_ptr() != NULL,
3753 "must have a regular hazard ptr to have nested hazard ptrs");
3754
3755 // We have a nested ThreadsListHandle so we have to release it first.
3756 // The need for a nested ThreadsListHandle is rare so we do this while
3757 // holding the Threads_lock so we don't race with the scanning code;
3758 // the code is so much simpler this way.
3759
3760 NestedThreadsList *node;
3761 {
3762 // Only grab the Threads_lock if we don't already own it.
3763 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3764 // We remove from the front of the list to match up with the insert
3765 // in acquire_stable_list().
3766 node = self->get_nested_threads_hazard_ptr();
3767 self->set_nested_threads_hazard_ptr(node->next());
3768 if (EnableThreadSMRStatistics) {
3769 self->dec_nested_threads_hazard_ptr_cnt();
3770 }
3771 }
3772
3773 // An exiting thread might be waiting in smr_delete(); we need to
3774 // check with smr_delete_lock to be sure.
3775 release_stable_list_wake_up((char *) "nested hazard ptr");
3776
3777 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()));
3778
3779 delete node;
3780 }
3781
3782 // Wake up portion of the release stable ThreadsList protocol;
3783 // uses the smr_delete_lock().
3784 //
3785 void Threads::release_stable_list_wake_up(char *log_str) {
3786 assert(log_str != NULL, "sanity check");
3787
3788 // Note: smr_delete_lock is held in smr_delete() for the entire
3789 // hazard ptr search so that we do not lose this notify() if
3790 // the exiting thread has to wait. That code path also holds
3791 // Threads_lock (which was grabbed before smr_delete_lock) so that
3792 // threads_do() can be called. This means the system can't start a
3793 // safepoint which means this thread can't take too long to get to
3794 // a safepoint because of being blocked on smr_delete_lock.
3795 //
3796 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag);
3797 if (Threads::smr_delete_notify()) {
3798 // Notify any exiting JavaThreads that are waiting in smr_delete()
3799 // that we've released a ThreadsList.
3800 ml.notify_all();
3801 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str);
3802 }
3803 }
3804
3805 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3806 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3807
3808 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3809 create_vm_init_libraries();
3810 }
3811
3812 initialize_class(vmSymbols::java_lang_String(), CHECK);
3813
3814 // Inject CompactStrings value after the static initializers for String ran.
3815 java_lang_String::set_compact_strings(CompactStrings);
3816
3817 // Initialize java_lang.System (needed before creating the thread)
3818 initialize_class(vmSymbols::java_lang_System(), CHECK);
3819 // The VM creates & returns objects of this class. Make sure it's initialized.
3820 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3821 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3822 Handle thread_group = create_initial_thread_group(CHECK);
3823 Universe::set_main_thread_group(thread_group());
3824 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3825 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3826 main_thread->set_threadObj(thread_object);
3827 // Set thread status to running since main thread has
3828 // been started and running.
3829 java_lang_Thread::set_thread_status(thread_object,
3830 java_lang_Thread::RUNNABLE);
3831
3832 // The VM creates objects of this class.
3833 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3834
3835 // The VM preresolves methods to these classes. Make sure that they get initialized
3836 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3837 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3838
3839 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3840 call_initPhase1(CHECK);
3841
3842 // get the Java runtime name after java.lang.System is initialized
3843 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3844 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3845
3846 // an instance of OutOfMemory exception has been allocated earlier
3847 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3848 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3849 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3850 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3851 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3852 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3853 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3854 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3855 }
3856
3857 void Threads::initialize_jsr292_core_classes(TRAPS) {
3858 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3859
3860 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3861 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3862 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3863 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3864 }
3865
3866 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3867 extern void JDK_Version_init();
3868
3869 // Preinitialize version info.
3870 VM_Version::early_initialize();
3871
3872 // Check version
3873 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3874
3875 // Initialize library-based TLS
3876 ThreadLocalStorage::init();
3877
3878 // Initialize the output stream module
3879 ostream_init();
3880
3881 // Process java launcher properties.
3882 Arguments::process_sun_java_launcher_properties(args);
3883
3884 // Initialize the os module
3885 os::init();
3886
3887 // Record VM creation timing statistics
3888 TraceVmCreationTime create_vm_timer;
3889 create_vm_timer.start();
3890
3891 // Initialize system properties.
3892 Arguments::init_system_properties();
3893
3894 // So that JDK version can be used as a discriminator when parsing arguments
3895 JDK_Version_init();
3896
3897 // Update/Initialize System properties after JDK version number is known
3898 Arguments::init_version_specific_system_properties();
3899
3900 // Make sure to initialize log configuration *before* parsing arguments
3901 LogConfiguration::initialize(create_vm_timer.begin_time());
3902
3903 // Parse arguments
3904 jint parse_result = Arguments::parse(args);
3905 if (parse_result != JNI_OK) return parse_result;
3906
3907 os::init_before_ergo();
3908
3909 jint ergo_result = Arguments::apply_ergo();
3910 if (ergo_result != JNI_OK) return ergo_result;
3911
3912 // Final check of all ranges after ergonomics which may change values.
3913 if (!CommandLineFlagRangeList::check_ranges()) {
3914 return JNI_EINVAL;
3915 }
3916
3917 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3918 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3919 if (!constraint_result) {
3920 return JNI_EINVAL;
3921 }
3922
3923 CommandLineFlagWriteableList::mark_startup();
3924
3925 if (PauseAtStartup) {
3926 os::pause();
3927 }
3928
3929 HOTSPOT_VM_INIT_BEGIN();
3930
3931 // Timing (must come after argument parsing)
3932 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3933
3934 SafepointMechanism::initialize();
3935
3936 // Initialize the os module after parsing the args
3937 jint os_init_2_result = os::init_2();
3938 if (os_init_2_result != JNI_OK) return os_init_2_result;
3939
3940 jint adjust_after_os_result = Arguments::adjust_after_os();
3941 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3942
3943 // Initialize output stream logging
3944 ostream_init_log();
3945
3946 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3947 // Must be before create_vm_init_agents()
3948 if (Arguments::init_libraries_at_startup()) {
3949 convert_vm_init_libraries_to_agents();
3950 }
3951
3952 // Launch -agentlib/-agentpath and converted -Xrun agents
3953 if (Arguments::init_agents_at_startup()) {
3954 create_vm_init_agents();
3955 }
3956
3957 // Initialize Threads state
3958 _thread_list = NULL;
3959 _number_of_threads = 0;
3960 _number_of_non_daemon_threads = 0;
3961
3962 // Initialize global data structures and create system classes in heap
3963 vm_init_globals();
3964
3965 #if INCLUDE_JVMCI
3966 if (JVMCICounterSize > 0) {
3967 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3968 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3969 } else {
3970 JavaThread::_jvmci_old_thread_counters = NULL;
3971 }
3972 #endif // INCLUDE_JVMCI
3973
3974 // Attach the main thread to this os thread
3975 JavaThread* main_thread = new JavaThread();
3976 main_thread->set_thread_state(_thread_in_vm);
3977 main_thread->initialize_thread_current();
3978 // must do this before set_active_handles
3979 main_thread->record_stack_base_and_size();
3980 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3981
3982 if (!main_thread->set_as_starting_thread()) {
3983 vm_shutdown_during_initialization(
3984 "Failed necessary internal allocation. Out of swap space");
3985 main_thread->smr_delete();
3986 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3987 return JNI_ENOMEM;
3988 }
3989
3990 // Enable guard page *after* os::create_main_thread(), otherwise it would
3991 // crash Linux VM, see notes in os_linux.cpp.
3992 main_thread->create_stack_guard_pages();
3993
3994 // Initialize Java-Level synchronization subsystem
3995 ObjectMonitor::Initialize();
3996
3997 // Initialize global modules
3998 jint status = init_globals();
3999 if (status != JNI_OK) {
4000 main_thread->smr_delete();
4001 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
4002 return status;
4003 }
4004
4005 if (TRACE_INITIALIZE() != JNI_OK) {
4006 vm_exit_during_initialization("Failed to initialize tracing backend");
4007 }
4008
4009 // Should be done after the heap is fully created
4010 main_thread->cache_global_variables();
4011
4012 HandleMark hm;
4013
4014 { MutexLocker mu(Threads_lock);
4015 Threads::add(main_thread);
4016 }
4017
4018 // Any JVMTI raw monitors entered in onload will transition into
4019 // real raw monitor. VM is setup enough here for raw monitor enter.
4020 JvmtiExport::transition_pending_onload_raw_monitors();
4021
4022 // Create the VMThread
4023 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
4024
4025 VMThread::create();
4026 Thread* vmthread = VMThread::vm_thread();
4027
4028 if (!os::create_thread(vmthread, os::vm_thread)) {
4029 vm_exit_during_initialization("Cannot create VM thread. "
4030 "Out of system resources.");
4031 }
4032
4033 // Wait for the VM thread to become ready, and VMThread::run to initialize
4034 // Monitors can have spurious returns, must always check another state flag
4035 {
4036 MutexLocker ml(Notify_lock);
4037 os::start_thread(vmthread);
4038 while (vmthread->active_handles() == NULL) {
4039 Notify_lock->wait();
4040 }
4041 }
4042 }
4043
4044 assert(Universe::is_fully_initialized(), "not initialized");
4045 if (VerifyDuringStartup) {
4046 // Make sure we're starting with a clean slate.
4047 VM_Verify verify_op;
4048 VMThread::execute(&verify_op);
4049 }
4050
4051 Thread* THREAD = Thread::current();
4052
4053 // Always call even when there are not JVMTI environments yet, since environments
4054 // may be attached late and JVMTI must track phases of VM execution
4055 JvmtiExport::enter_early_start_phase();
4056
4057 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4058 JvmtiExport::post_early_vm_start();
4059
4060 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4061
4062 // We need this for ClassDataSharing - the initial vm.info property is set
4063 // with the default value of CDS "sharing" which may be reset through
4064 // command line options.
4065 reset_vm_info_property(CHECK_JNI_ERR);
4066
4067 quicken_jni_functions();
4068
4069 // No more stub generation allowed after that point.
4070 StubCodeDesc::freeze();
4071
4072 // Set flag that basic initialization has completed. Used by exceptions and various
4073 // debug stuff, that does not work until all basic classes have been initialized.
4074 set_init_completed();
4075
4076 LogConfiguration::post_initialize();
4077 Metaspace::post_initialize();
4078
4079 HOTSPOT_VM_INIT_END();
4080
4081 // record VM initialization completion time
4082 #if INCLUDE_MANAGEMENT
4083 Management::record_vm_init_completed();
4084 #endif // INCLUDE_MANAGEMENT
4085
4086 // Signal Dispatcher needs to be started before VMInit event is posted
4087 os::signal_init(CHECK_JNI_ERR);
4088
4089 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4090 if (!DisableAttachMechanism) {
4091 AttachListener::vm_start();
4092 if (StartAttachListener || AttachListener::init_at_startup()) {
4093 AttachListener::init();
4094 }
4095 }
4096
4097 // Launch -Xrun agents
4098 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4099 // back-end can launch with -Xdebug -Xrunjdwp.
4100 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4101 create_vm_init_libraries();
4102 }
4103
4104 if (CleanChunkPoolAsync) {
4105 Chunk::start_chunk_pool_cleaner_task();
4106 }
4107
4108 // initialize compiler(s)
4109 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4110 CompileBroker::compilation_init(CHECK_JNI_ERR);
4111 #endif
4112
4113 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4114 // It is done after compilers are initialized, because otherwise compilations of
4115 // signature polymorphic MH intrinsics can be missed
4116 // (see SystemDictionary::find_method_handle_intrinsic).
4117 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4118
4119 // This will initialize the module system. Only java.base classes can be
4120 // loaded until phase 2 completes
4121 call_initPhase2(CHECK_JNI_ERR);
4122
4123 // Always call even when there are not JVMTI environments yet, since environments
4124 // may be attached late and JVMTI must track phases of VM execution
4125 JvmtiExport::enter_start_phase();
4126
4127 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4128 JvmtiExport::post_vm_start();
4129
4130 // Final system initialization including security manager and system class loader
4131 call_initPhase3(CHECK_JNI_ERR);
4132
4133 // cache the system and platform class loaders
4134 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4135
4136 #if INCLUDE_JVMCI
4137 if (EnableJVMCI) {
4138 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
4139 // The JVMCI Java initialization code will read this flag and
4140 // do the printing if it's set.
4141 bool init = JVMCIPrintProperties;
4142
4143 if (!init) {
4144 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4145 // compilations via JVMCI will not actually block until JVMCI is initialized.
4146 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4147 }
4148
4149 if (init) {
4150 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
4151 }
4152 }
4153 #endif
4154
4155 // Always call even when there are not JVMTI environments yet, since environments
4156 // may be attached late and JVMTI must track phases of VM execution
4157 JvmtiExport::enter_live_phase();
4158
4159 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4160 JvmtiExport::post_vm_initialized();
4161
4162 if (TRACE_START() != JNI_OK) {
4163 vm_exit_during_initialization("Failed to start tracing backend.");
4164 }
4165
4166 #if INCLUDE_MANAGEMENT
4167 Management::initialize(THREAD);
4168
4169 if (HAS_PENDING_EXCEPTION) {
4170 // management agent fails to start possibly due to
4171 // configuration problem and is responsible for printing
4172 // stack trace if appropriate. Simply exit VM.
4173 vm_exit(1);
4174 }
4175 #endif // INCLUDE_MANAGEMENT
4176
4177 if (MemProfiling) MemProfiler::engage();
4178 StatSampler::engage();
4179 if (CheckJNICalls) JniPeriodicChecker::engage();
4180
4181 BiasedLocking::init();
4182
4183 #if INCLUDE_RTM_OPT
4184 RTMLockingCounters::init();
4185 #endif
4186
4187 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4188 call_postVMInitHook(THREAD);
4189 // The Java side of PostVMInitHook.run must deal with all
4190 // exceptions and provide means of diagnosis.
4191 if (HAS_PENDING_EXCEPTION) {
4192 CLEAR_PENDING_EXCEPTION;
4193 }
4194 }
4195
4196 {
4197 MutexLocker ml(PeriodicTask_lock);
4198 // Make sure the WatcherThread can be started by WatcherThread::start()
4199 // or by dynamic enrollment.
4200 WatcherThread::make_startable();
4201 // Start up the WatcherThread if there are any periodic tasks
4202 // NOTE: All PeriodicTasks should be registered by now. If they
4203 // aren't, late joiners might appear to start slowly (we might
4204 // take a while to process their first tick).
4205 if (PeriodicTask::num_tasks() > 0) {
4206 WatcherThread::start();
4207 }
4208 }
4209
4210 create_vm_timer.end();
4211 #ifdef ASSERT
4212 _vm_complete = true;
4213 #endif
4214
4215 if (DumpSharedSpaces) {
4216 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4217 ShouldNotReachHere();
4218 }
4219
4220 return JNI_OK;
4221 }
4222
4223 // type for the Agent_OnLoad and JVM_OnLoad entry points
4224 extern "C" {
4225 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4226 }
4227 // Find a command line agent library and return its entry point for
4228 // -agentlib: -agentpath: -Xrun
4229 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4230 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4231 const char *on_load_symbols[],
4232 size_t num_symbol_entries) {
4233 OnLoadEntry_t on_load_entry = NULL;
4234 void *library = NULL;
4235
4236 if (!agent->valid()) {
4237 char buffer[JVM_MAXPATHLEN];
4238 char ebuf[1024] = "";
4239 const char *name = agent->name();
4240 const char *msg = "Could not find agent library ";
4241
4242 // First check to see if agent is statically linked into executable
4243 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4244 library = agent->os_lib();
4245 } else if (agent->is_absolute_path()) {
4246 library = os::dll_load(name, ebuf, sizeof ebuf);
4247 if (library == NULL) {
4248 const char *sub_msg = " in absolute path, with error: ";
4249 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4250 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4251 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4252 // If we can't find the agent, exit.
4253 vm_exit_during_initialization(buf, NULL);
4254 FREE_C_HEAP_ARRAY(char, buf);
4255 }
4256 } else {
4257 // Try to load the agent from the standard dll directory
4258 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4259 name)) {
4260 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4261 }
4262 if (library == NULL) { // Try the library path directory.
4263 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4264 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4265 }
4266 if (library == NULL) {
4267 const char *sub_msg = " on the library path, with error: ";
4268 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4269 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4270 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4271 // If we can't find the agent, exit.
4272 vm_exit_during_initialization(buf, NULL);
4273 FREE_C_HEAP_ARRAY(char, buf);
4274 }
4275 }
4276 }
4277 agent->set_os_lib(library);
4278 agent->set_valid();
4279 }
4280
4281 // Find the OnLoad function.
4282 on_load_entry =
4283 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4284 false,
4285 on_load_symbols,
4286 num_symbol_entries));
4287 return on_load_entry;
4288 }
4289
4290 // Find the JVM_OnLoad entry point
4291 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4292 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4293 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4294 }
4295
4296 // Find the Agent_OnLoad entry point
4297 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4298 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4299 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4300 }
4301
4302 // For backwards compatibility with -Xrun
4303 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4304 // treated like -agentpath:
4305 // Must be called before agent libraries are created
4306 void Threads::convert_vm_init_libraries_to_agents() {
4307 AgentLibrary* agent;
4308 AgentLibrary* next;
4309
4310 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4311 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4312 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4313
4314 // If there is an JVM_OnLoad function it will get called later,
4315 // otherwise see if there is an Agent_OnLoad
4316 if (on_load_entry == NULL) {
4317 on_load_entry = lookup_agent_on_load(agent);
4318 if (on_load_entry != NULL) {
4319 // switch it to the agent list -- so that Agent_OnLoad will be called,
4320 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4321 Arguments::convert_library_to_agent(agent);
4322 } else {
4323 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4324 }
4325 }
4326 }
4327 }
4328
4329 // Create agents for -agentlib: -agentpath: and converted -Xrun
4330 // Invokes Agent_OnLoad
4331 // Called very early -- before JavaThreads exist
4332 void Threads::create_vm_init_agents() {
4333 extern struct JavaVM_ main_vm;
4334 AgentLibrary* agent;
4335
4336 JvmtiExport::enter_onload_phase();
4337
4338 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4339 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4340
4341 if (on_load_entry != NULL) {
4342 // Invoke the Agent_OnLoad function
4343 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4344 if (err != JNI_OK) {
4345 vm_exit_during_initialization("agent library failed to init", agent->name());
4346 }
4347 } else {
4348 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4349 }
4350 }
4351 JvmtiExport::enter_primordial_phase();
4352 }
4353
4354 extern "C" {
4355 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4356 }
4357
4358 void Threads::shutdown_vm_agents() {
4359 // Send any Agent_OnUnload notifications
4360 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4361 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4362 extern struct JavaVM_ main_vm;
4363 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4364
4365 // Find the Agent_OnUnload function.
4366 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4367 os::find_agent_function(agent,
4368 false,
4369 on_unload_symbols,
4370 num_symbol_entries));
4371
4372 // Invoke the Agent_OnUnload function
4373 if (unload_entry != NULL) {
4374 JavaThread* thread = JavaThread::current();
4375 ThreadToNativeFromVM ttn(thread);
4376 HandleMark hm(thread);
4377 (*unload_entry)(&main_vm);
4378 }
4379 }
4380 }
4381
4382 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4383 // Invokes JVM_OnLoad
4384 void Threads::create_vm_init_libraries() {
4385 extern struct JavaVM_ main_vm;
4386 AgentLibrary* agent;
4387
4388 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4389 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4390
4391 if (on_load_entry != NULL) {
4392 // Invoke the JVM_OnLoad function
4393 JavaThread* thread = JavaThread::current();
4394 ThreadToNativeFromVM ttn(thread);
4395 HandleMark hm(thread);
4396 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4397 if (err != JNI_OK) {
4398 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4399 }
4400 } else {
4401 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4402 }
4403 }
4404 }
4405
4406
4407 // Last thread running calls java.lang.Shutdown.shutdown()
4408 void JavaThread::invoke_shutdown_hooks() {
4409 HandleMark hm(this);
4410
4411 // We could get here with a pending exception, if so clear it now.
4412 if (this->has_pending_exception()) {
4413 this->clear_pending_exception();
4414 }
4415
4416 EXCEPTION_MARK;
4417 Klass* shutdown_klass =
4418 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4419 THREAD);
4420 if (shutdown_klass != NULL) {
4421 // SystemDictionary::resolve_or_null will return null if there was
4422 // an exception. If we cannot load the Shutdown class, just don't
4423 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4424 // and finalizers (if runFinalizersOnExit is set) won't be run.
4425 // Note that if a shutdown hook was registered or runFinalizersOnExit
4426 // was called, the Shutdown class would have already been loaded
4427 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4428 JavaValue result(T_VOID);
4429 JavaCalls::call_static(&result,
4430 shutdown_klass,
4431 vmSymbols::shutdown_method_name(),
4432 vmSymbols::void_method_signature(),
4433 THREAD);
4434 }
4435 CLEAR_PENDING_EXCEPTION;
4436 }
4437
4438 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4439 // the program falls off the end of main(). Another VM exit path is through
4440 // vm_exit() when the program calls System.exit() to return a value or when
4441 // there is a serious error in VM. The two shutdown paths are not exactly
4442 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4443 // and VM_Exit op at VM level.
4444 //
4445 // Shutdown sequence:
4446 // + Shutdown native memory tracking if it is on
4447 // + Wait until we are the last non-daemon thread to execute
4448 // <-- every thing is still working at this moment -->
4449 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4450 // shutdown hooks, run finalizers if finalization-on-exit
4451 // + Call before_exit(), prepare for VM exit
4452 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4453 // currently the only user of this mechanism is File.deleteOnExit())
4454 // > stop StatSampler, watcher thread, CMS threads,
4455 // post thread end and vm death events to JVMTI,
4456 // stop signal thread
4457 // + Call JavaThread::exit(), it will:
4458 // > release JNI handle blocks, remove stack guard pages
4459 // > remove this thread from Threads list
4460 // <-- no more Java code from this thread after this point -->
4461 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4462 // the compiler threads at safepoint
4463 // <-- do not use anything that could get blocked by Safepoint -->
4464 // + Disable tracing at JNI/JVM barriers
4465 // + Set _vm_exited flag for threads that are still running native code
4466 // + Delete this thread
4467 // + Call exit_globals()
4468 // > deletes tty
4469 // > deletes PerfMemory resources
4470 // + Return to caller
4471
4472 bool Threads::destroy_vm() {
4473 JavaThread* thread = JavaThread::current();
4474
4475 #ifdef ASSERT
4476 _vm_complete = false;
4477 #endif
4478 // Wait until we are the last non-daemon thread to execute
4479 { MutexLocker nu(Threads_lock);
4480 while (Threads::number_of_non_daemon_threads() > 1)
4481 // This wait should make safepoint checks, wait without a timeout,
4482 // and wait as a suspend-equivalent condition.
4483 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4484 Mutex::_as_suspend_equivalent_flag);
4485 }
4486
4487 // Hang forever on exit if we are reporting an error.
4488 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4489 os::infinite_sleep();
4490 }
4491 os::wait_for_keypress_at_exit();
4492
4493 // run Java level shutdown hooks
4494 thread->invoke_shutdown_hooks();
4495
4496 before_exit(thread);
4497
4498 thread->exit(true);
4499
4500 // Stop VM thread.
4501 {
4502 // 4945125 The vm thread comes to a safepoint during exit.
4503 // GC vm_operations can get caught at the safepoint, and the
4504 // heap is unparseable if they are caught. Grab the Heap_lock
4505 // to prevent this. The GC vm_operations will not be able to
4506 // queue until after the vm thread is dead. After this point,
4507 // we'll never emerge out of the safepoint before the VM exits.
4508
4509 MutexLocker ml(Heap_lock);
4510
4511 VMThread::wait_for_vm_thread_exit();
4512 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4513 VMThread::destroy();
4514 }
4515
4516 // clean up ideal graph printers
4517 #if defined(COMPILER2) && !defined(PRODUCT)
4518 IdealGraphPrinter::clean_up();
4519 #endif
4520
4521 // Now, all Java threads are gone except daemon threads. Daemon threads
4522 // running Java code or in VM are stopped by the Safepoint. However,
4523 // daemon threads executing native code are still running. But they
4524 // will be stopped at native=>Java/VM barriers. Note that we can't
4525 // simply kill or suspend them, as it is inherently deadlock-prone.
4526
4527 VM_Exit::set_vm_exited();
4528
4529 notify_vm_shutdown();
4530
4531 // We are after VM_Exit::set_vm_exited() so we can't call
4532 // thread->smr_delete() or we will block on the Threads_lock.
4533 // Deleting the shutdown thread here is safe because another
4534 // JavaThread cannot have an active ThreadsListHandle for
4535 // this JavaThread.
4536 delete thread;
4537
4538 #if INCLUDE_JVMCI
4539 if (JVMCICounterSize > 0) {
4540 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4541 }
4542 #endif
4543
4544 // exit_globals() will delete tty
4545 exit_globals();
4546
4547 LogConfiguration::finalize();
4548
4549 return true;
4550 }
4551
4552
4553 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4554 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4555 return is_supported_jni_version(version);
4556 }
4557
4558
4559 jboolean Threads::is_supported_jni_version(jint version) {
4560 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4561 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4562 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4563 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4564 if (version == JNI_VERSION_9) return JNI_TRUE;
4565 if (version == JNI_VERSION_10) return JNI_TRUE;
4566 return JNI_FALSE;
4567 }
4568
4569 // Hash table of pointers found by a scan. Used for collecting hazard
4570 // pointers (ThreadsList references). Also used for collecting JavaThreads
4571 // that are indirectly referenced by hazard ptrs. An instance of this
4572 // class only contains one type of pointer.
4573 //
4574 class ThreadScanHashtable : public CHeapObj<mtThread> {
4575 private:
4576 static bool ptr_equals(void * const& s1, void * const& s2) {
4577 return s1 == s2;
4578 }
4579
4580 static unsigned int ptr_hash(void * const& s1) {
4581 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
4582 }
4583
4584 int _table_size;
4585 // ResourceHashtable SIZE is specified at compile time so our
4586 // dynamic _table_size is unused for now; 1031 is the first prime
4587 // after 1024.
4588 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash,
4589 &ThreadScanHashtable::ptr_equals, 1031,
4590 ResourceObj::C_HEAP, mtThread> PtrTable;
4591 PtrTable * _ptrs;
4592
4593 public:
4594 // ResourceHashtable is passed to various functions and populated in
4595 // different places so we allocate it using C_HEAP to make it immune
4596 // from any ResourceMarks that happen to be in the code paths.
4597 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {}
4598
4599 ~ThreadScanHashtable() { delete _ptrs; }
4600
4601 bool has_entry(void *pointer) {
4602 int *val_ptr = _ptrs->get(pointer);
4603 return val_ptr != NULL && *val_ptr == 1;
4604 }
4605
4606 void add_entry(void *pointer) {
4607 _ptrs->put(pointer, 1);
4608 }
4609 };
4610
4611 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4612 // (ThreadsList references) into a hash table. This closure handles part 2
4613 // of the dance - adding all the JavaThreads referenced by the hazard
4614 // pointer (ThreadsList reference) to the hash table.
4615 //
4616 class AddThreadHazardPointerThreadClosure : public ThreadClosure {
4617 private:
4618 ThreadScanHashtable *_table;
4619
4620 public:
4621 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {}
4622
4623 virtual void do_thread(Thread *thread) {
4624 if (!_table->has_entry((void*)thread)) {
4625 // The same JavaThread might be on more than one ThreadsList or
4626 // more than one thread might be using the same ThreadsList. In
4627 // either case, we only need a single entry for a JavaThread.
4628 _table->add_entry((void*)thread);
4629 }
4630 }
4631 };
4632
4633 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4634 // (ThreadsList references) into a hash table. This closure handles part 1
4635 // of the dance - hazard ptr chain walking and dispatch to another
4636 // closure.
4637 //
4638 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure {
4639 private:
4640 ThreadScanHashtable *_table;
4641 public:
4642 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {}
4643
4644 virtual void do_thread(Thread *thread) {
4645 assert_locked_or_safepoint(Threads_lock);
4646
4647 if (thread == NULL) return;
4648
4649 // This code races with Threads::acquire_stable_list() which is
4650 // lock-free so we have to handle some special situations.
4651 //
4652 ThreadsList *current_list = NULL;
4653 while (true) {
4654 current_list = thread->get_threads_hazard_ptr();
4655 // No hazard ptr so nothing more to do.
4656 if (current_list == NULL) {
4657 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4658 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4659 return;
4660 }
4661
4662 // If the hazard ptr is verified as stable (since it is not tagged),
4663 // then it is safe to use.
4664 if (!Thread::is_hazard_ptr_tagged(current_list)) break;
4665
4666 // The hazard ptr is tagged as not yet verified as being stable
4667 // so we are racing with acquire_stable_list(). This exchange
4668 // attempts to invalidate the hazard ptr. If we win the race,
4669 // then we can ignore this unstable hazard ptr and the other
4670 // thread will retry the attempt to publish a stable hazard ptr.
4671 // If we lose the race, then we retry our attempt to look at the
4672 // hazard ptr.
4673 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return;
4674 }
4675
4676 // The current JavaThread has a hazard ptr (ThreadsList reference)
4677 // which might be _smr_java_thread_list or it might be an older
4678 // ThreadsList that has been removed but not freed. In either case,
4679 // the hazard ptr is protecting all the JavaThreads on that
4680 // ThreadsList.
4681 AddThreadHazardPointerThreadClosure add_cl(_table);
4682 current_list->threads_do(&add_cl);
4683
4684 // Any NestedThreadsLists are also protecting JavaThreads so
4685 // gather those also; the ThreadsLists may be different.
4686 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4687 node != NULL; node = node->next()) {
4688 node->t_list()->threads_do(&add_cl);
4689 }
4690 }
4691 };
4692
4693 // Closure to print JavaThreads that have a hazard ptr (ThreadsList
4694 // reference) that contains an indirect reference to a specific JavaThread.
4695 //
4696 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure {
4697 private:
4698 JavaThread *_thread;
4699 public:
4700 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {}
4701
4702 virtual void do_thread(Thread *thread) {
4703 assert_locked_or_safepoint(Threads_lock);
4704
4705 if (thread == NULL) return;
4706 ThreadsList *current_list = thread->get_threads_hazard_ptr();
4707 if (current_list == NULL) {
4708 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4709 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4710 return;
4711 }
4712 // If the hazard ptr is unverified, then ignore it.
4713 if (Thread::is_hazard_ptr_tagged(current_list)) return;
4714
4715 // The current JavaThread has a hazard ptr (ThreadsList reference)
4716 // which might be _smr_java_thread_list or it might be an older
4717 // ThreadsList that has been removed but not freed. In either case,
4718 // the hazard ptr is protecting all the JavaThreads on that
4719 // ThreadsList, but we only care about matching a specific JavaThread.
4720 DO_JAVA_THREADS(current_list, p) {
4721 if (p == _thread) {
4722 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));
4723 break;
4724 }
4725 }
4726
4727 // Any NestedThreadsLists are also protecting JavaThreads so
4728 // check those also; the ThreadsLists may be different.
4729 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4730 node != NULL; node = node->next()) {
4731 DO_JAVA_THREADS(node->t_list(), p) {
4732 if (p == _thread) {
4733 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));
4734 return;
4735 }
4736 }
4737 }
4738 }
4739 };
4740
4741 // Return true if the specified JavaThread is protected by a hazard
4742 // pointer (ThreadsList reference). Otherwise, returns false.
4743 //
4744 bool Threads::is_a_protected_JavaThread(JavaThread *thread) {
4745 assert_locked_or_safepoint(Threads_lock);
4746
4747 // Hash table size should be first power of two higher than twice
4748 // the length of the Threads list.
4749 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4750 hash_table_size--;
4751 hash_table_size |= hash_table_size >> 1;
4752 hash_table_size |= hash_table_size >> 2;
4753 hash_table_size |= hash_table_size >> 4;
4754 hash_table_size |= hash_table_size >> 8;
4755 hash_table_size |= hash_table_size >> 16;
4756 hash_table_size++;
4757
4758 // Gather a hash table of the JavaThreads indirectly referenced by
4759 // hazard ptrs.
4760 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4761 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table);
4762 Threads::threads_do(&scan_cl);
4763
4764 bool thread_is_protected = false;
4765 if (scan_table->has_entry((void*)thread)) {
4766 thread_is_protected = true;
4767 }
4768 delete scan_table;
4769 return thread_is_protected;
4770 }
4771
4772 // Safely delete a JavaThread when it is no longer in use by a
4773 // ThreadsListHandle.
4774 //
4775 void Threads::smr_delete(JavaThread *thread) {
4776 assert(!Threads_lock->owned_by_self(), "sanity");
4777
4778 bool has_logged_once = false;
4779 elapsedTimer timer;
4780 if (EnableThreadSMRStatistics) {
4781 timer.start();
4782 }
4783
4784 while (true) {
4785 {
4786 // No safepoint check because this JavaThread is not on the
4787 // Threads list.
4788 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
4789 // Cannot use a MonitorLockerEx helper here because we have
4790 // to drop the Threads_lock first if we wait.
4791 Threads::smr_delete_lock()->lock_without_safepoint_check();
4792 // Set the smr_delete_notify flag after we grab smr_delete_lock
4793 // and before we scan hazard ptrs because we're doing
4794 // double-check locking in release_stable_list().
4795 Threads::set_smr_delete_notify();
4796
4797 if (!is_a_protected_JavaThread(thread)) {
4798 // This is the common case.
4799 Threads::clear_smr_delete_notify();
4800 Threads::smr_delete_lock()->unlock();
4801 break;
4802 }
4803 if (!has_logged_once) {
4804 has_logged_once = true;
4805 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread));
4806 if (log_is_enabled(Debug, os, thread)) {
4807 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread);
4808 Threads::threads_do(&scan_cl);
4809 }
4810 }
4811 } // We have to drop the Threads_lock to wait or delete the thread
4812
4813 if (EnableThreadSMRStatistics) {
4814 _smr_delete_lock_wait_cnt++;
4815 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) {
4816 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt;
4817 }
4818 }
4819 // Wait for a release_stable_list() call before we check again. No
4820 // safepoint check, no timeout, and not as suspend equivalent flag
4821 // because this JavaThread is not on the Threads list.
4822 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0,
4823 !Mutex::_as_suspend_equivalent_flag);
4824 if (EnableThreadSMRStatistics) {
4825 _smr_delete_lock_wait_cnt--;
4826 }
4827
4828 Threads::clear_smr_delete_notify();
4829 Threads::smr_delete_lock()->unlock();
4830 // Retry the whole scenario.
4831 }
4832
4833 delete thread;
4834 if (EnableThreadSMRStatistics) {
4835 timer.stop();
4836 jint millis = (jint)timer.milliseconds();
4837 Threads::inc_smr_deleted_thread_cnt();
4838 Threads::add_smr_deleted_thread_times(millis);
4839 Threads::update_smr_deleted_thread_time_max(millis);
4840 }
4841
4842 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread));
4843 }
4844
4845 bool Threads::smr_delete_notify() {
4846 // Use load_acquire() in order to see any updates to _smr_delete_notify
4847 // earlier than when smr_delete_lock is grabbed.
4848 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0);
4849 }
4850
4851 // set_smr_delete_notify() and clear_smr_delete_notify() are called
4852 // under the protection of the smr_delete_lock, but we also use an
4853 // Atomic operation to ensure the memory update is seen earlier than
4854 // when the smr_delete_lock is dropped.
4855 //
4856 void Threads::set_smr_delete_notify() {
4857 Atomic::inc(&_smr_delete_notify);
4858 }
4859
4860 void Threads::clear_smr_delete_notify() {
4861 Atomic::dec(&_smr_delete_notify);
4862 }
4863
4864 // Closure to gather hazard ptrs (ThreadsList references) into a hash table.
4865 //
4866 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure {
4867 private:
4868 ThreadScanHashtable *_table;
4869 public:
4870 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {}
4871
4872 virtual void do_thread(Thread* thread) {
4873 assert_locked_or_safepoint(Threads_lock);
4874
4875 if (thread == NULL) return;
4876 ThreadsList *threads = thread->get_threads_hazard_ptr();
4877 if (threads == NULL) {
4878 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4879 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4880 return;
4881 }
4882 // In this closure we always ignore the tag that might mark this
4883 // hazard ptr as not yet verified. If we happen to catch an
4884 // unverified hazard ptr that is subsequently discarded (not
4885 // published), then the only side effect is that we might keep a
4886 // to-be-deleted ThreadsList alive a little longer.
4887 threads = Thread::untag_hazard_ptr(threads);
4888 if (!_table->has_entry((void*)threads)) {
4889 _table->add_entry((void*)threads);
4890 }
4891
4892 // Any NestedThreadsLists are also protecting JavaThreads so
4893 // gather those also; the ThreadsLists may be different.
4894 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4895 node != NULL; node = node->next()) {
4896 threads = node->t_list();
4897 if (!_table->has_entry((void*)threads)) {
4898 _table->add_entry((void*)threads);
4899 }
4900 }
4901 }
4902 };
4903
4904 // Safely free a ThreadsList after a Threads::add() or Threads::remove().
4905 // The specified ThreadsList may not get deleted during this call if it
4906 // is still in-use (referenced by a hazard ptr). Other ThreadsLists
4907 // in the chain may get deleted by this call if they are no longer in-use.
4908 void Threads::smr_free_list(ThreadsList* threads) {
4909 assert_locked_or_safepoint(Threads_lock);
4910
4911 threads->set_next_list(_smr_to_delete_list);
4912 _smr_to_delete_list = threads;
4913 if (EnableThreadSMRStatistics) {
4914 _smr_to_delete_list_cnt++;
4915 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) {
4916 _smr_to_delete_list_max = _smr_to_delete_list_cnt;
4917 }
4918 }
4919
4920 // Hash table size should be first power of two higher than twice the length of the ThreadsList
4921 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4922 hash_table_size--;
4923 hash_table_size |= hash_table_size >> 1;
4924 hash_table_size |= hash_table_size >> 2;
4925 hash_table_size |= hash_table_size >> 4;
4926 hash_table_size |= hash_table_size >> 8;
4927 hash_table_size |= hash_table_size >> 16;
4928 hash_table_size++;
4929
4930 // Gather a hash table of the current hazard ptrs:
4931 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4932 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table);
4933 Threads::threads_do(&scan_cl);
4934
4935 // Walk through the linked list of pending freeable ThreadsLists
4936 // and free the ones that are not referenced from hazard ptrs.
4937 ThreadsList* current = _smr_to_delete_list;
4938 ThreadsList* prev = NULL;
4939 ThreadsList* next = NULL;
4940 bool threads_is_freed = false;
4941 while (current != NULL) {
4942 next = current->next_list();
4943 if (!scan_table->has_entry((void*)current)) {
4944 // This ThreadsList is not referenced by a hazard ptr.
4945 if (prev != NULL) {
4946 prev->set_next_list(next);
4947 }
4948 if (_smr_to_delete_list == current) {
4949 _smr_to_delete_list = next;
4950 }
4951
4952 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current));
4953 if (current == threads) threads_is_freed = true;
4954 delete current;
4955 if (EnableThreadSMRStatistics) {
4956 _smr_java_thread_list_free_cnt++;
4957 _smr_to_delete_list_cnt--;
4958 }
4959 } else {
4960 prev = current;
4961 }
4962 current = next;
4963 }
4964
4965 if (!threads_is_freed) {
4966 // Only report "is not freed" on the original call to
4967 // smr_free_list() for this ThreadsList.
4968 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads));
4969 }
4970
4971 delete scan_table;
4972 }
4973
4974 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a
4975 // new copy of the specified ThreadsList with the specified JavaThread
4976 // removed.
4977 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) {
4978 assert(list->_length > 0, "sanity");
4979
4980 uint i = 0;
4981 DO_JAVA_THREADS(list, current) {
4982 if (current == java_thread) {
4983 break;
4984 }
4985 i++;
4986 }
4987 assert(i < list->_length, "did not find JavaThread on the list");
4988 const uint index = i;
4989 const uint new_length = list->_length - 1;
4990 const uint head_length = index;
4991 const uint tail_length = (new_length >= index) ? (new_length - index) : 0;
4992 ThreadsList *const new_list = new ThreadsList(new_length);
4993
4994 if (head_length > 0) {
4995 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
4996 }
4997 if (tail_length > 0) {
4998 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length);
4999 }
5000
5001 return new_list;
5002 }
5003
5004 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a
5005 // new copy of the specified ThreadsList with the specified JavaThread
5006 // appended to the end.
5007 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) {
5008 const uint index = list->_length;
5009 const uint new_length = index + 1;
5010 const uint head_length = index;
5011 ThreadsList *const new_list = new ThreadsList(new_length);
5012
5013 if (head_length > 0) {
5014 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
5015 }
5016 *(JavaThread**)(new_list->_threads + index) = java_thread;
5017
5018 return new_list;
5019 }
5020
5021 int ThreadsList::find_index_of_JavaThread(JavaThread *target) {
5022 if (target == NULL) {
5023 return -1;
5024 }
5025 for (uint i = 0; i < length(); i++) {
5026 if (target == thread_at(i)) {
5027 return (int)i;
5028 }
5029 }
5030 return -1;
5031 }
5032
5033 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const {
5034 DO_JAVA_THREADS(this, thread) {
5035 oop tobj = thread->threadObj();
5036 // Ignore the thread if it hasn't run yet, has exited
5037 // or is starting to exit.
5038 if (tobj != NULL && !thread->is_exiting() &&
5039 java_tid == java_lang_Thread::thread_id(tobj)) {
5040 // found a match
5041 return thread;
5042 }
5043 }
5044 return NULL;
5045 }
5046
5047 bool ThreadsList::includes(const JavaThread * const p) const {
5048 if (p == NULL) {
5049 return false;
5050 }
5051 DO_JAVA_THREADS(this, q) {
5052 if (q == p) {
5053 return true;
5054 }
5055 }
5056 return false;
5057 }
5058
5059 void Threads::add(JavaThread* p, bool force_daemon) {
5060 // The threads lock must be owned at this point
5061 assert_locked_or_safepoint(Threads_lock);
5062
5063 // See the comment for this method in thread.hpp for its purpose and
5064 // why it is called here.
5065 p->initialize_queues();
5066 p->set_next(_thread_list);
5067 _thread_list = p;
5068
5069 // Once a JavaThread is added to the Threads list, smr_delete() has
5070 // to be used to delete it. Otherwise we can just delete it directly.
5071 p->set_on_thread_list();
5072
5073 _number_of_threads++;
5074 oop threadObj = p->threadObj();
5075 bool daemon = true;
5076 // Bootstrapping problem: threadObj can be null for initial
5077 // JavaThread (or for threads attached via JNI)
5078 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
5079 _number_of_non_daemon_threads++;
5080 daemon = false;
5081 }
5082
5083 ThreadService::add_thread(p, daemon);
5084
5085 // Maintain fast thread list
5086 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p);
5087 if (EnableThreadSMRStatistics) {
5088 _smr_java_thread_list_alloc_cnt++;
5089 if (new_list->length() > _smr_java_thread_list_max) {
5090 _smr_java_thread_list_max = new_list->length();
5091 }
5092 }
5093 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg.
5094 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5095
5096 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5097 smr_free_list(old_list);
5098
5099 // Possible GC point.
5100 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
5101 }
5102
5103 void Threads::remove(JavaThread* p) {
5104
5105 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
5106 ObjectSynchronizer::omFlush(p);
5107
5108 // Extra scope needed for Thread_lock, so we can check
5109 // that we do not remove thread without safepoint code notice
5110 { MutexLocker ml(Threads_lock);
5111
5112 assert(get_smr_java_thread_list()->includes(p), "p must be present");
5113
5114 // Maintain fast thread list
5115 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p);
5116 if (EnableThreadSMRStatistics) {
5117 _smr_java_thread_list_alloc_cnt++;
5118 // This list is smaller so no need to check for a "longest" update.
5119 }
5120
5121 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg.
5122 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5123
5124 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5125 smr_free_list(old_list);
5126
5127 JavaThread* current = _thread_list;
5128 JavaThread* prev = NULL;
5129
5130 while (current != p) {
5131 prev = current;
5132 current = current->next();
5133 }
5134
5135 if (prev) {
5136 prev->set_next(current->next());
5137 } else {
5138 _thread_list = p->next();
5139 }
5140
5141 _number_of_threads--;
5142 oop threadObj = p->threadObj();
5143 bool daemon = true;
5144 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
5145 _number_of_non_daemon_threads--;
5146 daemon = false;
5147
5148 // Only one thread left, do a notify on the Threads_lock so a thread waiting
5149 // on destroy_vm will wake up.
5150 if (number_of_non_daemon_threads() == 1) {
5151 Threads_lock->notify_all();
5152 }
5153 }
5154 ThreadService::remove_thread(p, daemon);
5155
5156 // Make sure that safepoint code disregard this thread. This is needed since
5157 // the thread might mess around with locks after this point. This can cause it
5158 // to do callbacks into the safepoint code. However, the safepoint code is not aware
5159 // of this thread since it is removed from the queue.
5160 p->set_terminated_value();
5161 } // unlock Threads_lock
5162
5163 // Since Events::log uses a lock, we grab it outside the Threads_lock
5164 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
5165 }
5166
5167 // Operations on the Threads list for GC. These are not explicitly locked,
5168 // but the garbage collector must provide a safe context for them to run.
5169 // In particular, these things should never be called when the Threads_lock
5170 // is held by some other thread. (Note: the Safepoint abstraction also
5171 // uses the Threads_lock to guarantee this property. It also makes sure that
5172 // all threads gets blocked when exiting or starting).
5173
5174 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
5175 ALL_JAVA_THREADS(p) {
5176 p->oops_do(f, cf);
5177 }
5178 VMThread::vm_thread()->oops_do(f, cf);
5179 }
5180
5181 void Threads::change_thread_claim_parity() {
5182 // Set the new claim parity.
5183 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
5184 "Not in range.");
5185 _thread_claim_parity++;
5186 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
5187 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
5188 "Not in range.");
5189 }
5190
5191 #ifdef ASSERT
5192 void Threads::assert_all_threads_claimed() {
5193 ALL_JAVA_THREADS(p) {
5194 const int thread_parity = p->oops_do_parity();
5195 assert((thread_parity == _thread_claim_parity),
5196 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
5197 }
5198 VMThread* vmt = VMThread::vm_thread();
5199 const int thread_parity = vmt->oops_do_parity();
5200 assert((thread_parity == _thread_claim_parity),
5201 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
5202 }
5203 #endif // ASSERT
5204
5205 class ParallelOopsDoThreadClosure : public ThreadClosure {
5206 private:
5207 OopClosure* _f;
5208 CodeBlobClosure* _cf;
5209 public:
5210 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
5211 void do_thread(Thread* t) {
5212 t->oops_do(_f, _cf);
5213 }
5214 };
5215
5216 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
5217 ParallelOopsDoThreadClosure tc(f, cf);
5218 possibly_parallel_threads_do(is_par, &tc);
5219 }
5220
5221 #if INCLUDE_ALL_GCS
5222 // Used by ParallelScavenge
5223 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
5224 ALL_JAVA_THREADS(p) {
5225 q->enqueue(new ThreadRootsTask(p));
5226 }
5227 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
5228 }
5229
5230 // Used by Parallel Old
5231 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
5232 ALL_JAVA_THREADS(p) {
5233 q->enqueue(new ThreadRootsMarkingTask(p));
5234 }
5235 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
5236 }
5237 #endif // INCLUDE_ALL_GCS
5238
5239 void Threads::nmethods_do(CodeBlobClosure* cf) {
5240 ALL_JAVA_THREADS(p) {
5241 // This is used by the code cache sweeper to mark nmethods that are active
5242 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
5243 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
5244 if(!p->is_Code_cache_sweeper_thread()) {
5245 p->nmethods_do(cf);
5246 }
5247 }
5248 }
5249
5250 void Threads::metadata_do(void f(Metadata*)) {
5251 ALL_JAVA_THREADS(p) {
5252 p->metadata_do(f);
5253 }
5254 }
5255
5256 class ThreadHandlesClosure : public ThreadClosure {
5257 void (*_f)(Metadata*);
5258 public:
5259 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
5260 virtual void do_thread(Thread* thread) {
5261 thread->metadata_handles_do(_f);
5262 }
5263 };
5264
5265 void Threads::metadata_handles_do(void f(Metadata*)) {
5266 // Only walk the Handles in Thread.
5267 ThreadHandlesClosure handles_closure(f);
5268 threads_do(&handles_closure);
5269 }
5270
5271 void Threads::deoptimized_wrt_marked_nmethods() {
5272 ALL_JAVA_THREADS(p) {
5273 p->deoptimized_wrt_marked_nmethods();
5274 }
5275 }
5276
5277
5278 // Get count Java threads that are waiting to enter the specified monitor.
5279 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
5280 int count,
5281 address monitor) {
5282 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
5283
5284 int i = 0;
5285 DO_JAVA_THREADS(t_list, p) {
5286 if (!p->can_call_java()) continue;
5287
5288 address pending = (address)p->current_pending_monitor();
5289 if (pending == monitor) { // found a match
5290 if (i < count) result->append(p); // save the first count matches
5291 i++;
5292 }
5293 }
5294
5295 return result;
5296 }
5297
5298
5299 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
5300 address owner) {
5301 // NULL owner means not locked so we can skip the search
5302 if (owner == NULL) return NULL;
5303
5304 DO_JAVA_THREADS(t_list, p) {
5305 // first, see if owner is the address of a Java thread
5306 if (owner == (address)p) return p;
5307 }
5308
5309 // Cannot assert on lack of success here since this function may be
5310 // used by code that is trying to report useful problem information
5311 // like deadlock detection.
5312 if (UseHeavyMonitors) return NULL;
5313
5314 // If we didn't find a matching Java thread and we didn't force use of
5315 // heavyweight monitors, then the owner is the stack address of the
5316 // Lock Word in the owning Java thread's stack.
5317 //
5318 JavaThread* the_owner = NULL;
5319 DO_JAVA_THREADS(t_list, q) {
5320 if (q->is_lock_owned(owner)) {
5321 the_owner = q;
5322 break;
5323 }
5324 }
5325
5326 // cannot assert on lack of success here; see above comment
5327 return the_owner;
5328 }
5329
5330 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
5331 void Threads::print_on(outputStream* st, bool print_stacks,
5332 bool internal_format, bool print_concurrent_locks) {
5333 char buf[32];
5334 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
5335
5336 st->print_cr("Full thread dump %s (%s %s):",
5337 Abstract_VM_Version::vm_name(),
5338 Abstract_VM_Version::vm_release(),
5339 Abstract_VM_Version::vm_info_string());
5340 st->cr();
5341
5342 #if INCLUDE_SERVICES
5343 // Dump concurrent locks
5344 ConcurrentLocksDump concurrent_locks;
5345 if (print_concurrent_locks) {
5346 concurrent_locks.dump_at_safepoint();
5347 }
5348 #endif // INCLUDE_SERVICES
5349
5350 print_smr_info_on(st);
5351 st->cr();
5352
5353 ALL_JAVA_THREADS(p) {
5354 ResourceMark rm;
5355 p->print_on(st);
5356 if (print_stacks) {
5357 if (internal_format) {
5358 p->trace_stack();
5359 } else {
5360 p->print_stack_on(st);
5361 }
5362 }
5363 st->cr();
5364 #if INCLUDE_SERVICES
5365 if (print_concurrent_locks) {
5366 concurrent_locks.print_locks_on(p, st);
5367 }
5368 #endif // INCLUDE_SERVICES
5369 }
5370
5371 VMThread::vm_thread()->print_on(st);
5372 st->cr();
5373 Universe::heap()->print_gc_threads_on(st);
5374 WatcherThread* wt = WatcherThread::watcher_thread();
5375 if (wt != NULL) {
5376 wt->print_on(st);
5377 st->cr();
5378 }
5379
5380 st->flush();
5381 }
5382
5383 // Log Threads class SMR info.
5384 void Threads::log_smr_statistics() {
5385 LogTarget(Info, thread, smr) log;
5386 if (log.is_enabled()) {
5387 LogStream out(log);
5388 print_smr_info_on(&out);
5389 }
5390 }
5391
5392 // Print Threads class SMR info.
5393 void Threads::print_smr_info_on(outputStream* st) {
5394 // Only grab the Threads_lock if we don't already own it
5395 // and if we are not reporting an error.
5396 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock);
5397
5398 st->print_cr("Threads class SMR info:");
5399 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, "
5400 "elements={", p2i(_smr_java_thread_list),
5401 _smr_java_thread_list->length());
5402 print_smr_info_elements_on(st, _smr_java_thread_list);
5403 st->print_cr("}");
5404 if (_smr_to_delete_list != NULL) {
5405 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, "
5406 "elements={", p2i(_smr_to_delete_list),
5407 _smr_to_delete_list->length());
5408 print_smr_info_elements_on(st, _smr_to_delete_list);
5409 st->print_cr("}");
5410 for (ThreadsList *t_list = _smr_to_delete_list->next_list();
5411 t_list != NULL; t_list = t_list->next_list()) {
5412 st->print("next-> " INTPTR_FORMAT ", length=%u, "
5413 "elements={", p2i(t_list), t_list->length());
5414 print_smr_info_elements_on(st, t_list);
5415 st->print_cr("}");
5416 }
5417 }
5418 if (!EnableThreadSMRStatistics) {
5419 return;
5420 }
5421 st->print_cr("_smr_java_thread_list_alloc_cnt=%ld, "
5422 "_smr_java_thread_list_free_cnt=%ld, "
5423 "_smr_java_thread_list_max=%u, "
5424 "_smr_nested_thread_list_max=%u",
5425 _smr_java_thread_list_alloc_cnt,
5426 _smr_java_thread_list_free_cnt,
5427 _smr_java_thread_list_max,
5428 _smr_nested_thread_list_max);
5429 if (_smr_tlh_cnt > 0) {
5430 st->print_cr("_smr_tlh_cnt=" INT32_FORMAT
5431 ", _smr_tlh_times=" INT32_FORMAT
5432 ", avg_smr_tlh_time=%0.2f"
5433 ", _smr_tlh_time_max=" INT32_FORMAT,
5434 _smr_tlh_cnt, _smr_tlh_times,
5435 ((double) _smr_tlh_times / _smr_tlh_cnt),
5436 _smr_tlh_time_max);
5437 }
5438 if (_smr_deleted_thread_cnt > 0) {
5439 st->print_cr("_smr_deleted_thread_cnt=" INT32_FORMAT
5440 ", _smr_deleted_thread_times=" INT32_FORMAT
5441 ", avg_smr_deleted_thread_time=%0.2f"
5442 ", _smr_deleted_thread_time_max=" INT32_FORMAT,
5443 _smr_deleted_thread_cnt, _smr_deleted_thread_times,
5444 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt),
5445 _smr_deleted_thread_time_max);
5446 }
5447 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u",
5448 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max);
5449 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u",
5450 _smr_to_delete_list_cnt, _smr_to_delete_list_max);
5451 }
5452
5453 // Print ThreadsList elements (4 per line).
5454 void Threads::print_smr_info_elements_on(outputStream* st,
5455 ThreadsList* t_list) {
5456 uint cnt = 0;
5457 JavaThreadIterator jti(t_list);
5458 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) {
5459 st->print(INTPTR_FORMAT, p2i(jt));
5460 if (cnt < t_list->length() - 1) {
5461 // Separate with comma or comma-space except for the last one.
5462 if (((cnt + 1) % 4) == 0) {
5463 // Four INTPTR_FORMAT fit on an 80 column line so end the
5464 // current line with just a comma.
5465 st->print_cr(",");
5466 } else {
5467 // Not the last one on the current line so use comma-space:
5468 st->print(", ");
5469 }
5470 } else {
5471 // Last one so just end the current line.
5472 st->cr();
5473 }
5474 cnt++;
5475 }
5476 }
5477
5478 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
5479 int buflen, bool* found_current) {
5480 if (this_thread != NULL) {
5481 bool is_current = (current == this_thread);
5482 *found_current = *found_current || is_current;
5483 st->print("%s", is_current ? "=>" : " ");
5484
5485 st->print(PTR_FORMAT, p2i(this_thread));
5486 st->print(" ");
5487 this_thread->print_on_error(st, buf, buflen);
5488 st->cr();
5489 }
5490 }
5491
5492 class PrintOnErrorClosure : public ThreadClosure {
5493 outputStream* _st;
5494 Thread* _current;
5495 char* _buf;
5496 int _buflen;
5497 bool* _found_current;
5498 public:
5499 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
5500 int buflen, bool* found_current) :
5501 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
5502
5503 virtual void do_thread(Thread* thread) {
5504 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
5505 }
5506 };
5507
5508 // Threads::print_on_error() is called by fatal error handler. It's possible
5509 // that VM is not at safepoint and/or current thread is inside signal handler.
5510 // Don't print stack trace, as the stack may not be walkable. Don't allocate
5511 // memory (even in resource area), it might deadlock the error handler.
5512 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
5513 int buflen) {
5514 print_smr_info_on(st);
5515 st->cr();
5516
5517 bool found_current = false;
5518 st->print_cr("Java Threads: ( => current thread )");
5519 ALL_JAVA_THREADS(thread) {
5520 print_on_error(thread, st, current, buf, buflen, &found_current);
5521 }
5522 st->cr();
5523
5524 st->print_cr("Other Threads:");
5525 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
5526 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
5527
5528 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
5529 Universe::heap()->gc_threads_do(&print_closure);
5530
5531 if (!found_current) {
5532 st->cr();
5533 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
5534 current->print_on_error(st, buf, buflen);
5535 st->cr();
5536 }
5537 st->cr();
5538
5539 st->print_cr("Threads with active compile tasks:");
5540 print_threads_compiling(st, buf, buflen);
5541 }
5542
5543 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
5544 ALL_JAVA_THREADS(thread) {
5545 if (thread->is_Compiler_thread()) {
5546 CompilerThread* ct = (CompilerThread*) thread;
5547 if (ct->task() != NULL) {
5548 thread->print_name_on_error(st, buf, buflen);
5549 ct->task()->print(st, NULL, true, true);
5550 }
5551 }
5552 }
5553 }
5554
5555
5556 // Internal SpinLock and Mutex
5557 // Based on ParkEvent
5558
5559 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
5560 //
5561 // We employ SpinLocks _only for low-contention, fixed-length
5562 // short-duration critical sections where we're concerned
5563 // about native mutex_t or HotSpot Mutex:: latency.
5564 // The mux construct provides a spin-then-block mutual exclusion
5565 // mechanism.
5566 //
5567 // Testing has shown that contention on the ListLock guarding gFreeList
5568 // is common. If we implement ListLock as a simple SpinLock it's common
5569 // for the JVM to devolve to yielding with little progress. This is true
5570 // despite the fact that the critical sections protected by ListLock are
5571 // extremely short.
5572 //
5573 // TODO-FIXME: ListLock should be of type SpinLock.
5574 // We should make this a 1st-class type, integrated into the lock
5575 // hierarchy as leaf-locks. Critically, the SpinLock structure
5576 // should have sufficient padding to avoid false-sharing and excessive
5577 // cache-coherency traffic.
5578
5579
5580 typedef volatile int SpinLockT;
5581
5582 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
5583 if (Atomic::cmpxchg (1, adr, 0) == 0) {
5584 return; // normal fast-path return
5585 }
5586
5587 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
5588 TEVENT(SpinAcquire - ctx);
5589 int ctr = 0;
5590 int Yields = 0;
5591 for (;;) {
5592 while (*adr != 0) {
5593 ++ctr;
5594 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
5595 if (Yields > 5) {
5596 os::naked_short_sleep(1);
5597 } else {
5598 os::naked_yield();
5599 ++Yields;
5600 }
5601 } else {
5602 SpinPause();
5603 }
5604 }
5605 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
5606 }
5607 }
5608
5609 void Thread::SpinRelease(volatile int * adr) {
5610 assert(*adr != 0, "invariant");
5611 OrderAccess::fence(); // guarantee at least release consistency.
5612 // Roach-motel semantics.
5613 // It's safe if subsequent LDs and STs float "up" into the critical section,
5614 // but prior LDs and STs within the critical section can't be allowed
5615 // to reorder or float past the ST that releases the lock.
5616 // Loads and stores in the critical section - which appear in program
5617 // order before the store that releases the lock - must also appear
5618 // before the store that releases the lock in memory visibility order.
5619 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5620 // the ST of 0 into the lock-word which releases the lock, so fence
5621 // more than covers this on all platforms.
5622 *adr = 0;
5623 }
5624
5625 // muxAcquire and muxRelease:
5626 //
5627 // * muxAcquire and muxRelease support a single-word lock-word construct.
5628 // The LSB of the word is set IFF the lock is held.
5629 // The remainder of the word points to the head of a singly-linked list
5630 // of threads blocked on the lock.
5631 //
5632 // * The current implementation of muxAcquire-muxRelease uses its own
5633 // dedicated Thread._MuxEvent instance. If we're interested in
5634 // minimizing the peak number of extant ParkEvent instances then
5635 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5636 // as certain invariants were satisfied. Specifically, care would need
5637 // to be taken with regards to consuming unpark() "permits".
5638 // A safe rule of thumb is that a thread would never call muxAcquire()
5639 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5640 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5641 // consume an unpark() permit intended for monitorenter, for instance.
5642 // One way around this would be to widen the restricted-range semaphore
5643 // implemented in park(). Another alternative would be to provide
5644 // multiple instances of the PlatformEvent() for each thread. One
5645 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5646 //
5647 // * Usage:
5648 // -- Only as leaf locks
5649 // -- for short-term locking only as muxAcquire does not perform
5650 // thread state transitions.
5651 //
5652 // Alternatives:
5653 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5654 // but with parking or spin-then-park instead of pure spinning.
5655 // * Use Taura-Oyama-Yonenzawa locks.
5656 // * It's possible to construct a 1-0 lock if we encode the lockword as
5657 // (List,LockByte). Acquire will CAS the full lockword while Release
5658 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5659 // acquiring threads use timers (ParkTimed) to detect and recover from
5660 // the stranding window. Thread/Node structures must be aligned on 256-byte
5661 // boundaries by using placement-new.
5662 // * Augment MCS with advisory back-link fields maintained with CAS().
5663 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5664 // The validity of the backlinks must be ratified before we trust the value.
5665 // If the backlinks are invalid the exiting thread must back-track through the
5666 // the forward links, which are always trustworthy.
5667 // * Add a successor indication. The LockWord is currently encoded as
5668 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5669 // to provide the usual futile-wakeup optimization.
5670 // See RTStt for details.
5671 // * Consider schedctl.sc_nopreempt to cover the critical section.
5672 //
5673
5674
5675 const intptr_t LOCKBIT = 1;
5676
5677 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5678 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5679 if (w == 0) return;
5680 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5681 return;
5682 }
5683
5684 TEVENT(muxAcquire - Contention);
5685 ParkEvent * const Self = Thread::current()->_MuxEvent;
5686 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5687 for (;;) {
5688 int its = (os::is_MP() ? 100 : 0) + 1;
5689
5690 // Optional spin phase: spin-then-park strategy
5691 while (--its >= 0) {
5692 w = *Lock;
5693 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5694 return;
5695 }
5696 }
5697
5698 Self->reset();
5699 Self->OnList = intptr_t(Lock);
5700 // The following fence() isn't _strictly necessary as the subsequent
5701 // CAS() both serializes execution and ratifies the fetched *Lock value.
5702 OrderAccess::fence();
5703 for (;;) {
5704 w = *Lock;
5705 if ((w & LOCKBIT) == 0) {
5706 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5707 Self->OnList = 0; // hygiene - allows stronger asserts
5708 return;
5709 }
5710 continue; // Interference -- *Lock changed -- Just retry
5711 }
5712 assert(w & LOCKBIT, "invariant");
5713 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5714 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5715 }
5716
5717 while (Self->OnList != 0) {
5718 Self->park();
5719 }
5720 }
5721 }
5722
5723 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5724 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5725 if (w == 0) return;
5726 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5727 return;
5728 }
5729
5730 TEVENT(muxAcquire - Contention);
5731 ParkEvent * ReleaseAfter = NULL;
5732 if (ev == NULL) {
5733 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5734 }
5735 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5736 for (;;) {
5737 guarantee(ev->OnList == 0, "invariant");
5738 int its = (os::is_MP() ? 100 : 0) + 1;
5739
5740 // Optional spin phase: spin-then-park strategy
5741 while (--its >= 0) {
5742 w = *Lock;
5743 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5744 if (ReleaseAfter != NULL) {
5745 ParkEvent::Release(ReleaseAfter);
5746 }
5747 return;
5748 }
5749 }
5750
5751 ev->reset();
5752 ev->OnList = intptr_t(Lock);
5753 // The following fence() isn't _strictly necessary as the subsequent
5754 // CAS() both serializes execution and ratifies the fetched *Lock value.
5755 OrderAccess::fence();
5756 for (;;) {
5757 w = *Lock;
5758 if ((w & LOCKBIT) == 0) {
5759 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5760 ev->OnList = 0;
5761 // We call ::Release while holding the outer lock, thus
5762 // artificially lengthening the critical section.
5763 // Consider deferring the ::Release() until the subsequent unlock(),
5764 // after we've dropped the outer lock.
5765 if (ReleaseAfter != NULL) {
5766 ParkEvent::Release(ReleaseAfter);
5767 }
5768 return;
5769 }
5770 continue; // Interference -- *Lock changed -- Just retry
5771 }
5772 assert(w & LOCKBIT, "invariant");
5773 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5774 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5775 }
5776
5777 while (ev->OnList != 0) {
5778 ev->park();
5779 }
5780 }
5781 }
5782
5783 // Release() must extract a successor from the list and then wake that thread.
5784 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5785 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5786 // Release() would :
5787 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5788 // (B) Extract a successor from the private list "in-hand"
5789 // (C) attempt to CAS() the residual back into *Lock over null.
5790 // If there were any newly arrived threads and the CAS() would fail.
5791 // In that case Release() would detach the RATs, re-merge the list in-hand
5792 // with the RATs and repeat as needed. Alternately, Release() might
5793 // detach and extract a successor, but then pass the residual list to the wakee.
5794 // The wakee would be responsible for reattaching and remerging before it
5795 // competed for the lock.
5796 //
5797 // Both "pop" and DMR are immune from ABA corruption -- there can be
5798 // multiple concurrent pushers, but only one popper or detacher.
5799 // This implementation pops from the head of the list. This is unfair,
5800 // but tends to provide excellent throughput as hot threads remain hot.
5801 // (We wake recently run threads first).
5802 //
5803 // All paths through muxRelease() will execute a CAS.
5804 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5805 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5806 // executed within the critical section are complete and globally visible before the
5807 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5808 void Thread::muxRelease(volatile intptr_t * Lock) {
5809 for (;;) {
5810 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5811 assert(w & LOCKBIT, "invariant");
5812 if (w == LOCKBIT) return;
5813 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5814 assert(List != NULL, "invariant");
5815 assert(List->OnList == intptr_t(Lock), "invariant");
5816 ParkEvent * const nxt = List->ListNext;
5817 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5818
5819 // The following CAS() releases the lock and pops the head element.
5820 // The CAS() also ratifies the previously fetched lock-word value.
5821 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5822 continue;
5823 }
5824 List->OnList = 0;
5825 OrderAccess::fence();
5826 List->unpark();
5827 return;
5828 }
5829 }
5830
5831
5832 void Threads::verify() {
5833 ALL_JAVA_THREADS(p) {
5834 p->verify();
5835 }
5836 VMThread* thread = VMThread::vm_thread();
5837 if (thread != NULL) thread->verify();
5838 }