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 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2020 Threads::remove(this);
2021
2022 // If someone set a handshake on us just as we entered exit path, we simple cancel it.
2023 if (ThreadLocalHandshakes) {
2024 cancel_handshake();
2025 }
2026 }
2027
2028 #if INCLUDE_ALL_GCS
2029 // Flush G1-related queues.
2030 void JavaThread::flush_barrier_queues() {
2031 satb_mark_queue().flush();
2032 dirty_card_queue().flush();
2033 }
2034
2035 void JavaThread::initialize_queues() {
2036 assert(!SafepointSynchronize::is_at_safepoint(),
2037 "we should not be at a safepoint");
2038
2039 SATBMarkQueue& satb_queue = satb_mark_queue();
2040 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
2041 // The SATB queue should have been constructed with its active
2042 // field set to false.
2043 assert(!satb_queue.is_active(), "SATB queue should not be active");
2044 assert(satb_queue.is_empty(), "SATB queue should be empty");
2045 // If we are creating the thread during a marking cycle, we should
2046 // set the active field of the SATB queue to true.
2047 if (satb_queue_set.is_active()) {
2048 satb_queue.set_active(true);
2049 }
2050
2051 DirtyCardQueue& dirty_queue = dirty_card_queue();
2052 // The dirty card queue should have been constructed with its
2053 // active field set to true.
2054 assert(dirty_queue.is_active(), "dirty card queue should be active");
2055 }
2056 #endif // INCLUDE_ALL_GCS
2057
2058 void JavaThread::cleanup_failed_attach_current_thread() {
2059 if (active_handles() != NULL) {
2060 JNIHandleBlock* block = active_handles();
2061 set_active_handles(NULL);
2062 JNIHandleBlock::release_block(block);
2063 }
2064
2065 if (free_handle_block() != NULL) {
2066 JNIHandleBlock* block = free_handle_block();
2067 set_free_handle_block(NULL);
2068 JNIHandleBlock::release_block(block);
2069 }
2070
2071 // These have to be removed while this is still a valid thread.
2072 remove_stack_guard_pages();
2073
2074 if (UseTLAB) {
2075 tlab().make_parsable(true); // retire TLAB, if any
2076 }
2077
2078 #if INCLUDE_ALL_GCS
2079 if (UseG1GC) {
2080 flush_barrier_queues();
2081 }
2082 #endif // INCLUDE_ALL_GCS
2083
2084 Threads::remove(this);
2085 this->smr_delete();
2086 }
2087
2088
2089
2090
2091 JavaThread* JavaThread::active() {
2092 Thread* thread = Thread::current();
2093 if (thread->is_Java_thread()) {
2094 return (JavaThread*) thread;
2095 } else {
2096 assert(thread->is_VM_thread(), "this must be a vm thread");
2097 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2098 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2099 assert(ret->is_Java_thread(), "must be a Java thread");
2100 return ret;
2101 }
2102 }
2103
2104 bool JavaThread::is_lock_owned(address adr) const {
2105 if (Thread::is_lock_owned(adr)) return true;
2106
2107 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2108 if (chunk->contains(adr)) return true;
2109 }
2110
2111 return false;
2112 }
2113
2114
2115 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2116 chunk->set_next(monitor_chunks());
2117 set_monitor_chunks(chunk);
2118 }
2119
2120 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2121 guarantee(monitor_chunks() != NULL, "must be non empty");
2122 if (monitor_chunks() == chunk) {
2123 set_monitor_chunks(chunk->next());
2124 } else {
2125 MonitorChunk* prev = monitor_chunks();
2126 while (prev->next() != chunk) prev = prev->next();
2127 prev->set_next(chunk->next());
2128 }
2129 }
2130
2131 // JVM support.
2132
2133 // Note: this function shouldn't block if it's called in
2134 // _thread_in_native_trans state (such as from
2135 // check_special_condition_for_native_trans()).
2136 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2137
2138 if (has_last_Java_frame() && has_async_condition()) {
2139 // If we are at a polling page safepoint (not a poll return)
2140 // then we must defer async exception because live registers
2141 // will be clobbered by the exception path. Poll return is
2142 // ok because the call we a returning from already collides
2143 // with exception handling registers and so there is no issue.
2144 // (The exception handling path kills call result registers but
2145 // this is ok since the exception kills the result anyway).
2146
2147 if (is_at_poll_safepoint()) {
2148 // if the code we are returning to has deoptimized we must defer
2149 // the exception otherwise live registers get clobbered on the
2150 // exception path before deoptimization is able to retrieve them.
2151 //
2152 RegisterMap map(this, false);
2153 frame caller_fr = last_frame().sender(&map);
2154 assert(caller_fr.is_compiled_frame(), "what?");
2155 if (caller_fr.is_deoptimized_frame()) {
2156 log_info(exceptions)("deferred async exception at compiled safepoint");
2157 return;
2158 }
2159 }
2160 }
2161
2162 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2163 if (condition == _no_async_condition) {
2164 // Conditions have changed since has_special_runtime_exit_condition()
2165 // was called:
2166 // - if we were here only because of an external suspend request,
2167 // then that was taken care of above (or cancelled) so we are done
2168 // - if we were here because of another async request, then it has
2169 // been cleared between the has_special_runtime_exit_condition()
2170 // and now so again we are done
2171 return;
2172 }
2173
2174 // Check for pending async. exception
2175 if (_pending_async_exception != NULL) {
2176 // Only overwrite an already pending exception, if it is not a threadDeath.
2177 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2178
2179 // We cannot call Exceptions::_throw(...) here because we cannot block
2180 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2181
2182 LogTarget(Info, exceptions) lt;
2183 if (lt.is_enabled()) {
2184 ResourceMark rm;
2185 LogStream ls(lt);
2186 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2187 if (has_last_Java_frame()) {
2188 frame f = last_frame();
2189 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2190 }
2191 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2192 }
2193 _pending_async_exception = NULL;
2194 clear_has_async_exception();
2195 }
2196 }
2197
2198 if (check_unsafe_error &&
2199 condition == _async_unsafe_access_error && !has_pending_exception()) {
2200 condition = _no_async_condition; // done
2201 switch (thread_state()) {
2202 case _thread_in_vm: {
2203 JavaThread* THREAD = this;
2204 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2205 }
2206 case _thread_in_native: {
2207 ThreadInVMfromNative tiv(this);
2208 JavaThread* THREAD = this;
2209 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2210 }
2211 case _thread_in_Java: {
2212 ThreadInVMfromJava tiv(this);
2213 JavaThread* THREAD = this;
2214 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2215 }
2216 default:
2217 ShouldNotReachHere();
2218 }
2219 }
2220
2221 assert(condition == _no_async_condition || has_pending_exception() ||
2222 (!check_unsafe_error && condition == _async_unsafe_access_error),
2223 "must have handled the async condition, if no exception");
2224 }
2225
2226 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2227 //
2228 // Check for pending external suspend. Internal suspend requests do
2229 // not use handle_special_runtime_exit_condition().
2230 // If JNIEnv proxies are allowed, don't self-suspend if the target
2231 // thread is not the current thread. In older versions of jdbx, jdbx
2232 // threads could call into the VM with another thread's JNIEnv so we
2233 // can be here operating on behalf of a suspended thread (4432884).
2234 bool do_self_suspend = is_external_suspend_with_lock();
2235 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2236 //
2237 // Because thread is external suspended the safepoint code will count
2238 // thread as at a safepoint. This can be odd because we can be here
2239 // as _thread_in_Java which would normally transition to _thread_blocked
2240 // at a safepoint. We would like to mark the thread as _thread_blocked
2241 // before calling java_suspend_self like all other callers of it but
2242 // we must then observe proper safepoint protocol. (We can't leave
2243 // _thread_blocked with a safepoint in progress). However we can be
2244 // here as _thread_in_native_trans so we can't use a normal transition
2245 // constructor/destructor pair because they assert on that type of
2246 // transition. We could do something like:
2247 //
2248 // JavaThreadState state = thread_state();
2249 // set_thread_state(_thread_in_vm);
2250 // {
2251 // ThreadBlockInVM tbivm(this);
2252 // java_suspend_self()
2253 // }
2254 // set_thread_state(_thread_in_vm_trans);
2255 // if (safepoint) block;
2256 // set_thread_state(state);
2257 //
2258 // but that is pretty messy. Instead we just go with the way the
2259 // code has worked before and note that this is the only path to
2260 // java_suspend_self that doesn't put the thread in _thread_blocked
2261 // mode.
2262
2263 frame_anchor()->make_walkable(this);
2264 java_suspend_self();
2265
2266 // We might be here for reasons in addition to the self-suspend request
2267 // so check for other async requests.
2268 }
2269
2270 if (check_asyncs) {
2271 check_and_handle_async_exceptions();
2272 }
2273 #if INCLUDE_TRACE
2274 if (is_trace_suspend()) {
2275 TRACE_SUSPEND_THREAD(this);
2276 }
2277 #endif
2278 }
2279
2280 void JavaThread::send_thread_stop(oop java_throwable) {
2281 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2282 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2283 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2284
2285 // Do not throw asynchronous exceptions against the compiler thread
2286 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2287 if (!can_call_java()) return;
2288
2289 {
2290 // Actually throw the Throwable against the target Thread - however
2291 // only if there is no thread death exception installed already.
2292 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2293 // If the topmost frame is a runtime stub, then we are calling into
2294 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2295 // must deoptimize the caller before continuing, as the compiled exception handler table
2296 // may not be valid
2297 if (has_last_Java_frame()) {
2298 frame f = last_frame();
2299 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2300 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2301 RegisterMap reg_map(this, UseBiasedLocking);
2302 frame compiled_frame = f.sender(®_map);
2303 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2304 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2305 }
2306 }
2307 }
2308
2309 // Set async. pending exception in thread.
2310 set_pending_async_exception(java_throwable);
2311
2312 if (log_is_enabled(Info, exceptions)) {
2313 ResourceMark rm;
2314 log_info(exceptions)("Pending Async. exception installed of type: %s",
2315 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2316 }
2317 // for AbortVMOnException flag
2318 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2319 }
2320 }
2321
2322
2323 // Interrupt thread so it will wake up from a potential wait()
2324 Thread::interrupt(this);
2325 }
2326
2327 // External suspension mechanism.
2328 //
2329 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2330 // to any VM_locks and it is at a transition
2331 // Self-suspension will happen on the transition out of the vm.
2332 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2333 //
2334 // Guarantees on return:
2335 // + Target thread will not execute any new bytecode (that's why we need to
2336 // force a safepoint)
2337 // + Target thread will not enter any new monitors
2338 //
2339 void JavaThread::java_suspend() {
2340 ThreadsListHandle tlh;
2341 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2342 return;
2343 }
2344
2345 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2346 if (!is_external_suspend()) {
2347 // a racing resume has cancelled us; bail out now
2348 return;
2349 }
2350
2351 // suspend is done
2352 uint32_t debug_bits = 0;
2353 // Warning: is_ext_suspend_completed() may temporarily drop the
2354 // SR_lock to allow the thread to reach a stable thread state if
2355 // it is currently in a transient thread state.
2356 if (is_ext_suspend_completed(false /* !called_by_wait */,
2357 SuspendRetryDelay, &debug_bits)) {
2358 return;
2359 }
2360 }
2361
2362 VM_ThreadSuspend vm_suspend;
2363 VMThread::execute(&vm_suspend);
2364 }
2365
2366 // Part II of external suspension.
2367 // A JavaThread self suspends when it detects a pending external suspend
2368 // request. This is usually on transitions. It is also done in places
2369 // where continuing to the next transition would surprise the caller,
2370 // e.g., monitor entry.
2371 //
2372 // Returns the number of times that the thread self-suspended.
2373 //
2374 // Note: DO NOT call java_suspend_self() when you just want to block current
2375 // thread. java_suspend_self() is the second stage of cooperative
2376 // suspension for external suspend requests and should only be used
2377 // to complete an external suspend request.
2378 //
2379 int JavaThread::java_suspend_self() {
2380 int ret = 0;
2381
2382 // we are in the process of exiting so don't suspend
2383 if (is_exiting()) {
2384 clear_external_suspend();
2385 return ret;
2386 }
2387
2388 assert(_anchor.walkable() ||
2389 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2390 "must have walkable stack");
2391
2392 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2393
2394 assert(!this->is_ext_suspended(),
2395 "a thread trying to self-suspend should not already be suspended");
2396
2397 if (this->is_suspend_equivalent()) {
2398 // If we are self-suspending as a result of the lifting of a
2399 // suspend equivalent condition, then the suspend_equivalent
2400 // flag is not cleared until we set the ext_suspended flag so
2401 // that wait_for_ext_suspend_completion() returns consistent
2402 // results.
2403 this->clear_suspend_equivalent();
2404 }
2405
2406 // A racing resume may have cancelled us before we grabbed SR_lock
2407 // above. Or another external suspend request could be waiting for us
2408 // by the time we return from SR_lock()->wait(). The thread
2409 // that requested the suspension may already be trying to walk our
2410 // stack and if we return now, we can change the stack out from under
2411 // it. This would be a "bad thing (TM)" and cause the stack walker
2412 // to crash. We stay self-suspended until there are no more pending
2413 // external suspend requests.
2414 while (is_external_suspend()) {
2415 ret++;
2416 this->set_ext_suspended();
2417
2418 // _ext_suspended flag is cleared by java_resume()
2419 while (is_ext_suspended()) {
2420 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2421 }
2422 }
2423
2424 return ret;
2425 }
2426
2427 #ifdef ASSERT
2428 // verify the JavaThread has not yet been published in the Threads::list, and
2429 // hence doesn't need protection from concurrent access at this stage
2430 void JavaThread::verify_not_published() {
2431 ThreadsListHandle tlh;
2432 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
2433 }
2434 #endif
2435
2436 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2437 // progress or when _suspend_flags is non-zero.
2438 // Current thread needs to self-suspend if there is a suspend request and/or
2439 // block if a safepoint is in progress.
2440 // Async exception ISN'T checked.
2441 // Note only the ThreadInVMfromNative transition can call this function
2442 // directly and when thread state is _thread_in_native_trans
2443 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2444 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2445
2446 JavaThread *curJT = JavaThread::current();
2447 bool do_self_suspend = thread->is_external_suspend();
2448
2449 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2450
2451 // If JNIEnv proxies are allowed, don't self-suspend if the target
2452 // thread is not the current thread. In older versions of jdbx, jdbx
2453 // threads could call into the VM with another thread's JNIEnv so we
2454 // can be here operating on behalf of a suspended thread (4432884).
2455 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2456 JavaThreadState state = thread->thread_state();
2457
2458 // We mark this thread_blocked state as a suspend-equivalent so
2459 // that a caller to is_ext_suspend_completed() won't be confused.
2460 // The suspend-equivalent state is cleared by java_suspend_self().
2461 thread->set_suspend_equivalent();
2462
2463 // If the safepoint code sees the _thread_in_native_trans state, it will
2464 // wait until the thread changes to other thread state. There is no
2465 // guarantee on how soon we can obtain the SR_lock and complete the
2466 // self-suspend request. It would be a bad idea to let safepoint wait for
2467 // too long. Temporarily change the state to _thread_blocked to
2468 // let the VM thread know that this thread is ready for GC. The problem
2469 // of changing thread state is that safepoint could happen just after
2470 // java_suspend_self() returns after being resumed, and VM thread will
2471 // see the _thread_blocked state. We must check for safepoint
2472 // after restoring the state and make sure we won't leave while a safepoint
2473 // is in progress.
2474 thread->set_thread_state(_thread_blocked);
2475 thread->java_suspend_self();
2476 thread->set_thread_state(state);
2477
2478 InterfaceSupport::serialize_thread_state_with_handler(thread);
2479 }
2480
2481 SafepointMechanism::block_if_requested(curJT);
2482
2483 if (thread->is_deopt_suspend()) {
2484 thread->clear_deopt_suspend();
2485 RegisterMap map(thread, false);
2486 frame f = thread->last_frame();
2487 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2488 f = f.sender(&map);
2489 }
2490 if (f.id() == thread->must_deopt_id()) {
2491 thread->clear_must_deopt_id();
2492 f.deoptimize(thread);
2493 } else {
2494 fatal("missed deoptimization!");
2495 }
2496 }
2497 #if INCLUDE_TRACE
2498 if (thread->is_trace_suspend()) {
2499 TRACE_SUSPEND_THREAD(thread);
2500 }
2501 #endif
2502 }
2503
2504 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2505 // progress or when _suspend_flags is non-zero.
2506 // Current thread needs to self-suspend if there is a suspend request and/or
2507 // block if a safepoint is in progress.
2508 // Also check for pending async exception (not including unsafe access error).
2509 // Note only the native==>VM/Java barriers can call this function and when
2510 // thread state is _thread_in_native_trans.
2511 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2512 check_safepoint_and_suspend_for_native_trans(thread);
2513
2514 if (thread->has_async_exception()) {
2515 // We are in _thread_in_native_trans state, don't handle unsafe
2516 // access error since that may block.
2517 thread->check_and_handle_async_exceptions(false);
2518 }
2519 }
2520
2521 // This is a variant of the normal
2522 // check_special_condition_for_native_trans with slightly different
2523 // semantics for use by critical native wrappers. It does all the
2524 // normal checks but also performs the transition back into
2525 // thread_in_Java state. This is required so that critical natives
2526 // can potentially block and perform a GC if they are the last thread
2527 // exiting the GCLocker.
2528 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2529 check_special_condition_for_native_trans(thread);
2530
2531 // Finish the transition
2532 thread->set_thread_state(_thread_in_Java);
2533
2534 if (thread->do_critical_native_unlock()) {
2535 ThreadInVMfromJavaNoAsyncException tiv(thread);
2536 GCLocker::unlock_critical(thread);
2537 thread->clear_critical_native_unlock();
2538 }
2539 }
2540
2541 // We need to guarantee the Threads_lock here, since resumes are not
2542 // allowed during safepoint synchronization
2543 // Can only resume from an external suspension
2544 void JavaThread::java_resume() {
2545 assert_locked_or_safepoint(Threads_lock);
2546
2547 // Sanity check: thread is gone, has started exiting or the thread
2548 // was not externally suspended.
2549 ThreadsListHandle tlh;
2550 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2551 return;
2552 }
2553
2554 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2555
2556 clear_external_suspend();
2557
2558 if (is_ext_suspended()) {
2559 clear_ext_suspended();
2560 SR_lock()->notify_all();
2561 }
2562 }
2563
2564 size_t JavaThread::_stack_red_zone_size = 0;
2565 size_t JavaThread::_stack_yellow_zone_size = 0;
2566 size_t JavaThread::_stack_reserved_zone_size = 0;
2567 size_t JavaThread::_stack_shadow_zone_size = 0;
2568
2569 void JavaThread::create_stack_guard_pages() {
2570 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2571 address low_addr = stack_end();
2572 size_t len = stack_guard_zone_size();
2573
2574 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2575 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2576
2577 int must_commit = os::must_commit_stack_guard_pages();
2578 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2579
2580 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2581 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2582 return;
2583 }
2584
2585 if (os::guard_memory((char *) low_addr, len)) {
2586 _stack_guard_state = stack_guard_enabled;
2587 } else {
2588 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2589 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2590 if (os::uncommit_memory((char *) low_addr, len)) {
2591 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2592 }
2593 return;
2594 }
2595
2596 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2597 PTR_FORMAT "-" PTR_FORMAT ".",
2598 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2599 }
2600
2601 void JavaThread::remove_stack_guard_pages() {
2602 assert(Thread::current() == this, "from different thread");
2603 if (_stack_guard_state == stack_guard_unused) return;
2604 address low_addr = stack_end();
2605 size_t len = stack_guard_zone_size();
2606
2607 if (os::must_commit_stack_guard_pages()) {
2608 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2609 _stack_guard_state = stack_guard_unused;
2610 } else {
2611 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2612 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2613 return;
2614 }
2615 } else {
2616 if (_stack_guard_state == stack_guard_unused) return;
2617 if (os::unguard_memory((char *) low_addr, len)) {
2618 _stack_guard_state = stack_guard_unused;
2619 } else {
2620 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2621 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2622 return;
2623 }
2624 }
2625
2626 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2627 PTR_FORMAT "-" PTR_FORMAT ".",
2628 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2629 }
2630
2631 void JavaThread::enable_stack_reserved_zone() {
2632 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2633 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2634
2635 // The base notation is from the stack's point of view, growing downward.
2636 // We need to adjust it to work correctly with guard_memory()
2637 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2638
2639 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2640 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2641
2642 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2643 _stack_guard_state = stack_guard_enabled;
2644 } else {
2645 warning("Attempt to guard stack reserved zone failed.");
2646 }
2647 enable_register_stack_guard();
2648 }
2649
2650 void JavaThread::disable_stack_reserved_zone() {
2651 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2652 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2653
2654 // Simply return if called for a thread that does not use guard pages.
2655 if (_stack_guard_state == stack_guard_unused) return;
2656
2657 // The base notation is from the stack's point of view, growing downward.
2658 // We need to adjust it to work correctly with guard_memory()
2659 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2660
2661 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2662 _stack_guard_state = stack_guard_reserved_disabled;
2663 } else {
2664 warning("Attempt to unguard stack reserved zone failed.");
2665 }
2666 disable_register_stack_guard();
2667 }
2668
2669 void JavaThread::enable_stack_yellow_reserved_zone() {
2670 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2671 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2672
2673 // The base notation is from the stacks point of view, growing downward.
2674 // We need to adjust it to work correctly with guard_memory()
2675 address base = stack_red_zone_base();
2676
2677 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2678 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2679
2680 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2681 _stack_guard_state = stack_guard_enabled;
2682 } else {
2683 warning("Attempt to guard stack yellow zone failed.");
2684 }
2685 enable_register_stack_guard();
2686 }
2687
2688 void JavaThread::disable_stack_yellow_reserved_zone() {
2689 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2690 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2691
2692 // Simply return if called for a thread that does not use guard pages.
2693 if (_stack_guard_state == stack_guard_unused) return;
2694
2695 // The base notation is from the stacks point of view, growing downward.
2696 // We need to adjust it to work correctly with guard_memory()
2697 address base = stack_red_zone_base();
2698
2699 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2700 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2701 } else {
2702 warning("Attempt to unguard stack yellow zone failed.");
2703 }
2704 disable_register_stack_guard();
2705 }
2706
2707 void JavaThread::enable_stack_red_zone() {
2708 // The base notation is from the stacks point of view, growing downward.
2709 // We need to adjust it to work correctly with guard_memory()
2710 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2711 address base = stack_red_zone_base() - stack_red_zone_size();
2712
2713 guarantee(base < stack_base(), "Error calculating stack red zone");
2714 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2715
2716 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2717 warning("Attempt to guard stack red zone failed.");
2718 }
2719 }
2720
2721 void JavaThread::disable_stack_red_zone() {
2722 // The base notation is from the stacks point of view, growing downward.
2723 // We need to adjust it to work correctly with guard_memory()
2724 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2725 address base = stack_red_zone_base() - stack_red_zone_size();
2726 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2727 warning("Attempt to unguard stack red zone failed.");
2728 }
2729 }
2730
2731 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2732 // ignore is there is no stack
2733 if (!has_last_Java_frame()) return;
2734 // traverse the stack frames. Starts from top frame.
2735 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2736 frame* fr = fst.current();
2737 f(fr, fst.register_map());
2738 }
2739 }
2740
2741
2742 #ifndef PRODUCT
2743 // Deoptimization
2744 // Function for testing deoptimization
2745 void JavaThread::deoptimize() {
2746 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2747 StackFrameStream fst(this, UseBiasedLocking);
2748 bool deopt = false; // Dump stack only if a deopt actually happens.
2749 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2750 // Iterate over all frames in the thread and deoptimize
2751 for (; !fst.is_done(); fst.next()) {
2752 if (fst.current()->can_be_deoptimized()) {
2753
2754 if (only_at) {
2755 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2756 // consists of comma or carriage return separated numbers so
2757 // search for the current bci in that string.
2758 address pc = fst.current()->pc();
2759 nmethod* nm = (nmethod*) fst.current()->cb();
2760 ScopeDesc* sd = nm->scope_desc_at(pc);
2761 char buffer[8];
2762 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2763 size_t len = strlen(buffer);
2764 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2765 while (found != NULL) {
2766 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2767 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2768 // Check that the bci found is bracketed by terminators.
2769 break;
2770 }
2771 found = strstr(found + 1, buffer);
2772 }
2773 if (!found) {
2774 continue;
2775 }
2776 }
2777
2778 if (DebugDeoptimization && !deopt) {
2779 deopt = true; // One-time only print before deopt
2780 tty->print_cr("[BEFORE Deoptimization]");
2781 trace_frames();
2782 trace_stack();
2783 }
2784 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2785 }
2786 }
2787
2788 if (DebugDeoptimization && deopt) {
2789 tty->print_cr("[AFTER Deoptimization]");
2790 trace_frames();
2791 }
2792 }
2793
2794
2795 // Make zombies
2796 void JavaThread::make_zombies() {
2797 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2798 if (fst.current()->can_be_deoptimized()) {
2799 // it is a Java nmethod
2800 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2801 nm->make_not_entrant();
2802 }
2803 }
2804 }
2805 #endif // PRODUCT
2806
2807
2808 void JavaThread::deoptimized_wrt_marked_nmethods() {
2809 if (!has_last_Java_frame()) return;
2810 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2811 StackFrameStream fst(this, UseBiasedLocking);
2812 for (; !fst.is_done(); fst.next()) {
2813 if (fst.current()->should_be_deoptimized()) {
2814 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2815 }
2816 }
2817 }
2818
2819
2820 // If the caller is a NamedThread, then remember, in the current scope,
2821 // the given JavaThread in its _processed_thread field.
2822 class RememberProcessedThread: public StackObj {
2823 NamedThread* _cur_thr;
2824 public:
2825 RememberProcessedThread(JavaThread* jthr) {
2826 Thread* thread = Thread::current();
2827 if (thread->is_Named_thread()) {
2828 _cur_thr = (NamedThread *)thread;
2829 _cur_thr->set_processed_thread(jthr);
2830 } else {
2831 _cur_thr = NULL;
2832 }
2833 }
2834
2835 ~RememberProcessedThread() {
2836 if (_cur_thr) {
2837 _cur_thr->set_processed_thread(NULL);
2838 }
2839 }
2840 };
2841
2842 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2843 // Verify that the deferred card marks have been flushed.
2844 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2845
2846 // Traverse the GCHandles
2847 Thread::oops_do(f, cf);
2848
2849 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2850
2851 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2852 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2853
2854 if (has_last_Java_frame()) {
2855 // Record JavaThread to GC thread
2856 RememberProcessedThread rpt(this);
2857
2858 // Traverse the privileged stack
2859 if (_privileged_stack_top != NULL) {
2860 _privileged_stack_top->oops_do(f);
2861 }
2862
2863 // traverse the registered growable array
2864 if (_array_for_gc != NULL) {
2865 for (int index = 0; index < _array_for_gc->length(); index++) {
2866 f->do_oop(_array_for_gc->adr_at(index));
2867 }
2868 }
2869
2870 // Traverse the monitor chunks
2871 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2872 chunk->oops_do(f);
2873 }
2874
2875 // Traverse the execution stack
2876 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2877 fst.current()->oops_do(f, cf, fst.register_map());
2878 }
2879 }
2880
2881 // callee_target is never live across a gc point so NULL it here should
2882 // it still contain a methdOop.
2883
2884 set_callee_target(NULL);
2885
2886 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2887 // If we have deferred set_locals there might be oops waiting to be
2888 // written
2889 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2890 if (list != NULL) {
2891 for (int i = 0; i < list->length(); i++) {
2892 list->at(i)->oops_do(f);
2893 }
2894 }
2895
2896 // Traverse instance variables at the end since the GC may be moving things
2897 // around using this function
2898 f->do_oop((oop*) &_threadObj);
2899 f->do_oop((oop*) &_vm_result);
2900 f->do_oop((oop*) &_exception_oop);
2901 f->do_oop((oop*) &_pending_async_exception);
2902
2903 if (jvmti_thread_state() != NULL) {
2904 jvmti_thread_state()->oops_do(f);
2905 }
2906 }
2907
2908 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2909 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2910 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2911
2912 if (has_last_Java_frame()) {
2913 // Traverse the execution stack
2914 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2915 fst.current()->nmethods_do(cf);
2916 }
2917 }
2918 }
2919
2920 void JavaThread::metadata_do(void f(Metadata*)) {
2921 if (has_last_Java_frame()) {
2922 // Traverse the execution stack to call f() on the methods in the stack
2923 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2924 fst.current()->metadata_do(f);
2925 }
2926 } else if (is_Compiler_thread()) {
2927 // need to walk ciMetadata in current compile tasks to keep alive.
2928 CompilerThread* ct = (CompilerThread*)this;
2929 if (ct->env() != NULL) {
2930 ct->env()->metadata_do(f);
2931 }
2932 if (ct->task() != NULL) {
2933 ct->task()->metadata_do(f);
2934 }
2935 }
2936 }
2937
2938 // Printing
2939 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2940 switch (_thread_state) {
2941 case _thread_uninitialized: return "_thread_uninitialized";
2942 case _thread_new: return "_thread_new";
2943 case _thread_new_trans: return "_thread_new_trans";
2944 case _thread_in_native: return "_thread_in_native";
2945 case _thread_in_native_trans: return "_thread_in_native_trans";
2946 case _thread_in_vm: return "_thread_in_vm";
2947 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2948 case _thread_in_Java: return "_thread_in_Java";
2949 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2950 case _thread_blocked: return "_thread_blocked";
2951 case _thread_blocked_trans: return "_thread_blocked_trans";
2952 default: return "unknown thread state";
2953 }
2954 }
2955
2956 #ifndef PRODUCT
2957 void JavaThread::print_thread_state_on(outputStream *st) const {
2958 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2959 };
2960 void JavaThread::print_thread_state() const {
2961 print_thread_state_on(tty);
2962 }
2963 #endif // PRODUCT
2964
2965 // Called by Threads::print() for VM_PrintThreads operation
2966 void JavaThread::print_on(outputStream *st) const {
2967 st->print_raw("\"");
2968 st->print_raw(get_thread_name());
2969 st->print_raw("\" ");
2970 oop thread_oop = threadObj();
2971 if (thread_oop != NULL) {
2972 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2973 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2974 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2975 }
2976 Thread::print_on(st);
2977 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2978 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2979 if (thread_oop != NULL) {
2980 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2981 }
2982 #ifndef PRODUCT
2983 print_thread_state_on(st);
2984 _safepoint_state->print_on(st);
2985 #endif // PRODUCT
2986 if (is_Compiler_thread()) {
2987 CompilerThread* ct = (CompilerThread*)this;
2988 if (ct->task() != NULL) {
2989 st->print(" Compiling: ");
2990 ct->task()->print(st, NULL, true, false);
2991 } else {
2992 st->print(" No compile task");
2993 }
2994 st->cr();
2995 }
2996 }
2997
2998 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2999 st->print("%s", get_thread_name_string(buf, buflen));
3000 }
3001
3002 // Called by fatal error handler. The difference between this and
3003 // JavaThread::print() is that we can't grab lock or allocate memory.
3004 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3005 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3006 oop thread_obj = threadObj();
3007 if (thread_obj != NULL) {
3008 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3009 }
3010 st->print(" [");
3011 st->print("%s", _get_thread_state_name(_thread_state));
3012 if (osthread()) {
3013 st->print(", id=%d", osthread()->thread_id());
3014 }
3015 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3016 p2i(stack_end()), p2i(stack_base()));
3017 st->print("]");
3018
3019 if (_threads_hazard_ptr != NULL) {
3020 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
3021 }
3022 if (_nested_threads_hazard_ptr != NULL) {
3023 print_nested_threads_hazard_ptrs_on(st);
3024 }
3025 return;
3026 }
3027
3028 // Verification
3029
3030 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3031
3032 void JavaThread::verify() {
3033 // Verify oops in the thread.
3034 oops_do(&VerifyOopClosure::verify_oop, NULL);
3035
3036 // Verify the stack frames.
3037 frames_do(frame_verify);
3038 }
3039
3040 // CR 6300358 (sub-CR 2137150)
3041 // Most callers of this method assume that it can't return NULL but a
3042 // thread may not have a name whilst it is in the process of attaching to
3043 // the VM - see CR 6412693, and there are places where a JavaThread can be
3044 // seen prior to having it's threadObj set (eg JNI attaching threads and
3045 // if vm exit occurs during initialization). These cases can all be accounted
3046 // for such that this method never returns NULL.
3047 const char* JavaThread::get_thread_name() const {
3048 #ifdef ASSERT
3049 // early safepoints can hit while current thread does not yet have TLS
3050 if (!SafepointSynchronize::is_at_safepoint()) {
3051 Thread *cur = Thread::current();
3052 if (!(cur->is_Java_thread() && cur == this)) {
3053 // Current JavaThreads are allowed to get their own name without
3054 // the Threads_lock.
3055 assert_locked_or_safepoint(Threads_lock);
3056 }
3057 }
3058 #endif // ASSERT
3059 return get_thread_name_string();
3060 }
3061
3062 // Returns a non-NULL representation of this thread's name, or a suitable
3063 // descriptive string if there is no set name
3064 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3065 const char* name_str;
3066 oop thread_obj = threadObj();
3067 if (thread_obj != NULL) {
3068 oop name = java_lang_Thread::name(thread_obj);
3069 if (name != NULL) {
3070 if (buf == NULL) {
3071 name_str = java_lang_String::as_utf8_string(name);
3072 } else {
3073 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3074 }
3075 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3076 name_str = "<no-name - thread is attaching>";
3077 } else {
3078 name_str = Thread::name();
3079 }
3080 } else {
3081 name_str = Thread::name();
3082 }
3083 assert(name_str != NULL, "unexpected NULL thread name");
3084 return name_str;
3085 }
3086
3087
3088 const char* JavaThread::get_threadgroup_name() const {
3089 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3090 oop thread_obj = threadObj();
3091 if (thread_obj != NULL) {
3092 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3093 if (thread_group != NULL) {
3094 // ThreadGroup.name can be null
3095 return java_lang_ThreadGroup::name(thread_group);
3096 }
3097 }
3098 return NULL;
3099 }
3100
3101 const char* JavaThread::get_parent_name() const {
3102 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3103 oop thread_obj = threadObj();
3104 if (thread_obj != NULL) {
3105 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3106 if (thread_group != NULL) {
3107 oop parent = java_lang_ThreadGroup::parent(thread_group);
3108 if (parent != NULL) {
3109 // ThreadGroup.name can be null
3110 return java_lang_ThreadGroup::name(parent);
3111 }
3112 }
3113 }
3114 return NULL;
3115 }
3116
3117 ThreadPriority JavaThread::java_priority() const {
3118 oop thr_oop = threadObj();
3119 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3120 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3121 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3122 return priority;
3123 }
3124
3125 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3126
3127 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3128 // Link Java Thread object <-> C++ Thread
3129
3130 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3131 // and put it into a new Handle. The Handle "thread_oop" can then
3132 // be used to pass the C++ thread object to other methods.
3133
3134 // Set the Java level thread object (jthread) field of the
3135 // new thread (a JavaThread *) to C++ thread object using the
3136 // "thread_oop" handle.
3137
3138 // Set the thread field (a JavaThread *) of the
3139 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3140
3141 Handle thread_oop(Thread::current(),
3142 JNIHandles::resolve_non_null(jni_thread));
3143 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3144 "must be initialized");
3145 set_threadObj(thread_oop());
3146 java_lang_Thread::set_thread(thread_oop(), this);
3147
3148 if (prio == NoPriority) {
3149 prio = java_lang_Thread::priority(thread_oop());
3150 assert(prio != NoPriority, "A valid priority should be present");
3151 }
3152
3153 // Push the Java priority down to the native thread; needs Threads_lock
3154 Thread::set_priority(this, prio);
3155
3156 prepare_ext();
3157
3158 // Add the new thread to the Threads list and set it in motion.
3159 // We must have threads lock in order to call Threads::add.
3160 // It is crucial that we do not block before the thread is
3161 // added to the Threads list for if a GC happens, then the java_thread oop
3162 // will not be visited by GC.
3163 Threads::add(this);
3164 }
3165
3166 oop JavaThread::current_park_blocker() {
3167 // Support for JSR-166 locks
3168 oop thread_oop = threadObj();
3169 if (thread_oop != NULL &&
3170 JDK_Version::current().supports_thread_park_blocker()) {
3171 return java_lang_Thread::park_blocker(thread_oop);
3172 }
3173 return NULL;
3174 }
3175
3176
3177 void JavaThread::print_stack_on(outputStream* st) {
3178 if (!has_last_Java_frame()) return;
3179 ResourceMark rm;
3180 HandleMark hm;
3181
3182 RegisterMap reg_map(this);
3183 vframe* start_vf = last_java_vframe(®_map);
3184 int count = 0;
3185 for (vframe* f = start_vf; f; f = f->sender()) {
3186 if (f->is_java_frame()) {
3187 javaVFrame* jvf = javaVFrame::cast(f);
3188 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3189
3190 // Print out lock information
3191 if (JavaMonitorsInStackTrace) {
3192 jvf->print_lock_info_on(st, count);
3193 }
3194 } else {
3195 // Ignore non-Java frames
3196 }
3197
3198 // Bail-out case for too deep stacks
3199 count++;
3200 if (MaxJavaStackTraceDepth == count) return;
3201 }
3202 }
3203
3204
3205 // JVMTI PopFrame support
3206 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3207 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3208 if (in_bytes(size_in_bytes) != 0) {
3209 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3210 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3211 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3212 }
3213 }
3214
3215 void* JavaThread::popframe_preserved_args() {
3216 return _popframe_preserved_args;
3217 }
3218
3219 ByteSize JavaThread::popframe_preserved_args_size() {
3220 return in_ByteSize(_popframe_preserved_args_size);
3221 }
3222
3223 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3224 int sz = in_bytes(popframe_preserved_args_size());
3225 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3226 return in_WordSize(sz / wordSize);
3227 }
3228
3229 void JavaThread::popframe_free_preserved_args() {
3230 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3231 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3232 _popframe_preserved_args = NULL;
3233 _popframe_preserved_args_size = 0;
3234 }
3235
3236 #ifndef PRODUCT
3237
3238 void JavaThread::trace_frames() {
3239 tty->print_cr("[Describe stack]");
3240 int frame_no = 1;
3241 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3242 tty->print(" %d. ", frame_no++);
3243 fst.current()->print_value_on(tty, this);
3244 tty->cr();
3245 }
3246 }
3247
3248 class PrintAndVerifyOopClosure: public OopClosure {
3249 protected:
3250 template <class T> inline void do_oop_work(T* p) {
3251 oop obj = oopDesc::load_decode_heap_oop(p);
3252 if (obj == NULL) return;
3253 tty->print(INTPTR_FORMAT ": ", p2i(p));
3254 if (oopDesc::is_oop_or_null(obj)) {
3255 if (obj->is_objArray()) {
3256 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3257 } else {
3258 obj->print();
3259 }
3260 } else {
3261 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3262 }
3263 tty->cr();
3264 }
3265 public:
3266 virtual void do_oop(oop* p) { do_oop_work(p); }
3267 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3268 };
3269
3270
3271 static void oops_print(frame* f, const RegisterMap *map) {
3272 PrintAndVerifyOopClosure print;
3273 f->print_value();
3274 f->oops_do(&print, NULL, (RegisterMap*)map);
3275 }
3276
3277 // Print our all the locations that contain oops and whether they are
3278 // valid or not. This useful when trying to find the oldest frame
3279 // where an oop has gone bad since the frame walk is from youngest to
3280 // oldest.
3281 void JavaThread::trace_oops() {
3282 tty->print_cr("[Trace oops]");
3283 frames_do(oops_print);
3284 }
3285
3286
3287 #ifdef ASSERT
3288 // Print or validate the layout of stack frames
3289 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3290 ResourceMark rm;
3291 PRESERVE_EXCEPTION_MARK;
3292 FrameValues values;
3293 int frame_no = 0;
3294 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3295 fst.current()->describe(values, ++frame_no);
3296 if (depth == frame_no) break;
3297 }
3298 if (validate_only) {
3299 values.validate();
3300 } else {
3301 tty->print_cr("[Describe stack layout]");
3302 values.print(this);
3303 }
3304 }
3305 #endif
3306
3307 void JavaThread::trace_stack_from(vframe* start_vf) {
3308 ResourceMark rm;
3309 int vframe_no = 1;
3310 for (vframe* f = start_vf; f; f = f->sender()) {
3311 if (f->is_java_frame()) {
3312 javaVFrame::cast(f)->print_activation(vframe_no++);
3313 } else {
3314 f->print();
3315 }
3316 if (vframe_no > StackPrintLimit) {
3317 tty->print_cr("...<more frames>...");
3318 return;
3319 }
3320 }
3321 }
3322
3323
3324 void JavaThread::trace_stack() {
3325 if (!has_last_Java_frame()) return;
3326 ResourceMark rm;
3327 HandleMark hm;
3328 RegisterMap reg_map(this);
3329 trace_stack_from(last_java_vframe(®_map));
3330 }
3331
3332
3333 #endif // PRODUCT
3334
3335
3336 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3337 assert(reg_map != NULL, "a map must be given");
3338 frame f = last_frame();
3339 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3340 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3341 }
3342 return NULL;
3343 }
3344
3345
3346 Klass* JavaThread::security_get_caller_class(int depth) {
3347 vframeStream vfst(this);
3348 vfst.security_get_caller_frame(depth);
3349 if (!vfst.at_end()) {
3350 return vfst.method()->method_holder();
3351 }
3352 return NULL;
3353 }
3354
3355 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3356 assert(thread->is_Compiler_thread(), "must be compiler thread");
3357 CompileBroker::compiler_thread_loop();
3358 }
3359
3360 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3361 NMethodSweeper::sweeper_loop();
3362 }
3363
3364 // Create a CompilerThread
3365 CompilerThread::CompilerThread(CompileQueue* queue,
3366 CompilerCounters* counters)
3367 : JavaThread(&compiler_thread_entry) {
3368 _env = NULL;
3369 _log = NULL;
3370 _task = NULL;
3371 _queue = queue;
3372 _counters = counters;
3373 _buffer_blob = NULL;
3374 _compiler = NULL;
3375
3376 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3377 resource_area()->bias_to(mtCompiler);
3378
3379 #ifndef PRODUCT
3380 _ideal_graph_printer = NULL;
3381 #endif
3382 }
3383
3384 bool CompilerThread::can_call_java() const {
3385 return _compiler != NULL && _compiler->is_jvmci();
3386 }
3387
3388 // Create sweeper thread
3389 CodeCacheSweeperThread::CodeCacheSweeperThread()
3390 : JavaThread(&sweeper_thread_entry) {
3391 _scanned_compiled_method = NULL;
3392 }
3393
3394 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3395 JavaThread::oops_do(f, cf);
3396 if (_scanned_compiled_method != NULL && cf != NULL) {
3397 // Safepoints can occur when the sweeper is scanning an nmethod so
3398 // process it here to make sure it isn't unloaded in the middle of
3399 // a scan.
3400 cf->do_code_blob(_scanned_compiled_method);
3401 }
3402 }
3403
3404 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3405 JavaThread::nmethods_do(cf);
3406 if (_scanned_compiled_method != NULL && cf != NULL) {
3407 // Safepoints can occur when the sweeper is scanning an nmethod so
3408 // process it here to make sure it isn't unloaded in the middle of
3409 // a scan.
3410 cf->do_code_blob(_scanned_compiled_method);
3411 }
3412 }
3413
3414
3415 // ======= Threads ========
3416
3417 // The Threads class links together all active threads, and provides
3418 // operations over all threads. It is protected by its own Mutex
3419 // lock, which is also used in other contexts to protect thread
3420 // operations from having the thread being operated on from exiting
3421 // and going away unexpectedly (e.g., safepoint synchronization)
3422
3423 JavaThread* Threads::_thread_list = NULL;
3424 int Threads::_number_of_threads = 0;
3425 int Threads::_number_of_non_daemon_threads = 0;
3426 int Threads::_return_code = 0;
3427 int Threads::_thread_claim_parity = 0;
3428 size_t JavaThread::_stack_size_at_create = 0;
3429 Monitor* Threads::_smr_delete_lock =
3430 new Monitor(Monitor::special, "smr_delete_lock",
3431 false /* allow_vm_block */,
3432 Monitor::_safepoint_check_never);
3433 // The '_cnt', '_max' and '_times" fields are enabled via
3434 // -XX:+EnableThreadSMRStatistics:
3435 uint Threads::_smr_delete_lock_wait_cnt = 0;
3436 uint Threads::_smr_delete_lock_wait_max = 0;
3437 volatile jint Threads::_smr_delete_notify = 0;
3438 volatile jint Threads::_smr_deleted_thread_cnt = 0;
3439 volatile jint Threads::_smr_deleted_thread_time_max = 0;
3440 volatile jint Threads::_smr_deleted_thread_times = 0;
3441 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
3442 long Threads::_smr_java_thread_list_alloc_cnt = 1;
3443 long Threads::_smr_java_thread_list_free_cnt = 0;
3444 uint Threads::_smr_java_thread_list_max = 0;
3445 uint Threads::_smr_nested_thread_list_max = 0;
3446 volatile jint Threads::_smr_tlh_cnt = 0;
3447 volatile jint Threads::_smr_tlh_time_max = 0;
3448 volatile jint Threads::_smr_tlh_times = 0;
3449 ThreadsList* Threads::_smr_to_delete_list = NULL;
3450 uint Threads::_smr_to_delete_list_cnt = 0;
3451 uint Threads::_smr_to_delete_list_max = 0;
3452
3453 #ifdef ASSERT
3454 bool Threads::_vm_complete = false;
3455 #endif
3456
3457 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3458 Prefetch::read((void*)addr, prefetch_interval);
3459 return *addr;
3460 }
3461
3462 // Possibly the ugliest for loop the world has seen. C++ does not allow
3463 // multiple types in the declaration section of the for loop. In this case
3464 // we are only dealing with pointers and hence can cast them. It looks ugly
3465 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3466 #define DO_JAVA_THREADS(LIST, X) \
3467 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3468 *MACRO_list = (JavaThread*)(LIST), \
3469 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3470 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3471 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3472 MACRO_current_p != MACRO_end; \
3473 MACRO_current_p++, \
3474 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3475
3476 // All JavaThreads
3477 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X)
3478
3479 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3480 void Threads::threads_do(ThreadClosure* tc) {
3481 assert_locked_or_safepoint(Threads_lock);
3482 // ALL_JAVA_THREADS iterates through all JavaThreads
3483 ALL_JAVA_THREADS(p) {
3484 tc->do_thread(p);
3485 }
3486 // Someday we could have a table or list of all non-JavaThreads.
3487 // For now, just manually iterate through them.
3488 tc->do_thread(VMThread::vm_thread());
3489 Universe::heap()->gc_threads_do(tc);
3490 WatcherThread *wt = WatcherThread::watcher_thread();
3491 // Strictly speaking, the following NULL check isn't sufficient to make sure
3492 // the data for WatcherThread is still valid upon being examined. However,
3493 // considering that WatchThread terminates when the VM is on the way to
3494 // exit at safepoint, the chance of the above is extremely small. The right
3495 // way to prevent termination of WatcherThread would be to acquire
3496 // Terminator_lock, but we can't do that without violating the lock rank
3497 // checking in some cases.
3498 if (wt != NULL) {
3499 tc->do_thread(wt);
3500 }
3501
3502 // If CompilerThreads ever become non-JavaThreads, add them here
3503 }
3504
3505 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3506 int cp = Threads::thread_claim_parity();
3507 ALL_JAVA_THREADS(p) {
3508 if (p->claim_oops_do(is_par, cp)) {
3509 tc->do_thread(p);
3510 }
3511 }
3512 VMThread* vmt = VMThread::vm_thread();
3513 if (vmt->claim_oops_do(is_par, cp)) {
3514 tc->do_thread(vmt);
3515 }
3516 }
3517
3518 // The system initialization in the library has three phases.
3519 //
3520 // Phase 1: java.lang.System class initialization
3521 // java.lang.System is a primordial class loaded and initialized
3522 // by the VM early during startup. java.lang.System.<clinit>
3523 // only does registerNatives and keeps the rest of the class
3524 // initialization work later until thread initialization completes.
3525 //
3526 // System.initPhase1 initializes the system properties, the static
3527 // fields in, out, and err. Set up java signal handlers, OS-specific
3528 // system settings, and thread group of the main thread.
3529 static void call_initPhase1(TRAPS) {
3530 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3531 JavaValue result(T_VOID);
3532 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3533 vmSymbols::void_method_signature(), CHECK);
3534 }
3535
3536 // Phase 2. Module system initialization
3537 // This will initialize the module system. Only java.base classes
3538 // can be loaded until phase 2 completes.
3539 //
3540 // Call System.initPhase2 after the compiler initialization and jsr292
3541 // classes get initialized because module initialization runs a lot of java
3542 // code, that for performance reasons, should be compiled. Also, this will
3543 // enable the startup code to use lambda and other language features in this
3544 // phase and onward.
3545 //
3546 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3547 static void call_initPhase2(TRAPS) {
3548 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3549
3550 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3551
3552 JavaValue result(T_INT);
3553 JavaCallArguments args;
3554 args.push_int(DisplayVMOutputToStderr);
3555 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3556 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3557 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3558 if (result.get_jint() != JNI_OK) {
3559 vm_exit_during_initialization(); // no message or exception
3560 }
3561
3562 universe_post_module_init();
3563 }
3564
3565 // Phase 3. final setup - set security manager, system class loader and TCCL
3566 //
3567 // This will instantiate and set the security manager, set the system class
3568 // loader as well as the thread context class loader. The security manager
3569 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3570 // other modules or the application's classpath.
3571 static void call_initPhase3(TRAPS) {
3572 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3573 JavaValue result(T_VOID);
3574 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3575 vmSymbols::void_method_signature(), CHECK);
3576 }
3577
3578 // Safe Memory Reclamation (SMR) support:
3579 //
3580
3581 // Acquire a stable ThreadsList.
3582 //
3583 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) {
3584 assert(self != NULL, "sanity check");
3585 // acquire_stable_list_nested_path() will grab the Threads_lock
3586 // so let's make sure the ThreadsListHandle is in a safe place.
3587 // ThreadsListSetter cannot make this check on this code path.
3588 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3589
3590 if (self->get_threads_hazard_ptr() == NULL) {
3591 // The typical case is first.
3592 return acquire_stable_list_fast_path(self);
3593 }
3594
3595 // The nested case is rare.
3596 return acquire_stable_list_nested_path(self);
3597 }
3598
3599 // Fast path (and lock free) way to acquire a stable ThreadsList.
3600 //
3601 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) {
3602 assert(self != NULL, "sanity check");
3603 assert(self->get_threads_hazard_ptr() == NULL, "sanity check");
3604 assert(self->get_nested_threads_hazard_ptr() == NULL,
3605 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
3606
3607 ThreadsList* threads;
3608
3609 // Stable recording of a hazard ptr for SMR. This code does not use
3610 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr
3611 // fields is racy relative to code that uses those fields with locks.
3612 // OrderAccess and Atomic functions are used to deal with those races.
3613 //
3614 while (true) {
3615 threads = get_smr_java_thread_list();
3616
3617 // Publish a tagged hazard ptr to denote that the hazard ptr is not
3618 // yet verified as being stable. Due to the fence after the hazard
3619 // ptr write, it will be sequentially consistent w.r.t. the
3620 // sequentially consistent writes of the ThreadsList, even on
3621 // non-multiple copy atomic machines where stores can be observed
3622 // in different order from different observer threads.
3623 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads);
3624 self->set_threads_hazard_ptr(unverified_threads);
3625
3626 // If _smr_java_thread_list has changed, we have lost a race with
3627 // Threads::add() or Threads::remove() and have to try again.
3628 if (get_smr_java_thread_list() != threads) {
3629 continue;
3630 }
3631
3632 // We try to remove the tag which will verify the hazard ptr as
3633 // being stable. This exchange can race with a scanning thread
3634 // which might invalidate the tagged hazard ptr to keep it from
3635 // being followed to access JavaThread ptrs. If we lose the race,
3636 // we simply retry. If we win the race, then the stable hazard
3637 // ptr is officially published.
3638 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) {
3639 break;
3640 }
3641 }
3642
3643 // A stable hazard ptr has been published letting other threads know
3644 // that the ThreadsList and the JavaThreads reachable from this list
3645 // are protected and hence they should not be deleted until everyone
3646 // agrees it is safe to do so.
3647
3648 return threads;
3649 }
3650
3651 // Acquire a nested stable ThreadsList; this is rare so it uses
3652 // Threads_lock.
3653 //
3654 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) {
3655 assert(self != NULL, "sanity check");
3656 assert(self->get_threads_hazard_ptr() != NULL,
3657 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr");
3658
3659 // The thread already has a hazard ptr (ThreadsList ref) so we need
3660 // to create a nested ThreadsListHandle with the current ThreadsList
3661 // since it might be different than our current hazard ptr. The need
3662 // for a nested ThreadsListHandle is rare so we do this while holding
3663 // the Threads_lock so we don't race with the scanning code; the code
3664 // is so much simpler this way.
3665
3666 NestedThreadsList* node;
3667 {
3668 // Only grab the Threads_lock if we don't already own it.
3669 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3670 node = new NestedThreadsList(get_smr_java_thread_list());
3671 // We insert at the front of the list to match up with the delete
3672 // in release_stable_list().
3673 node->set_next(self->get_nested_threads_hazard_ptr());
3674 self->set_nested_threads_hazard_ptr(node);
3675 if (EnableThreadSMRStatistics) {
3676 self->inc_nested_threads_hazard_ptr_cnt();
3677 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) {
3678 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt();
3679 }
3680 }
3681 }
3682 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()));
3683
3684 return node->t_list();
3685 }
3686
3687 // Release a stable ThreadsList.
3688 //
3689 void Threads::release_stable_list(Thread *self) {
3690 assert(self != NULL, "sanity check");
3691 // release_stable_list_nested_path() will grab the Threads_lock
3692 // so let's make sure the ThreadsListHandle is in a safe place.
3693 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);)
3694
3695 if (self->get_nested_threads_hazard_ptr() == NULL) {
3696 // The typical case is first.
3697 release_stable_list_fast_path(self);
3698 return;
3699 }
3700
3701 // The nested case is rare.
3702 release_stable_list_nested_path(self);
3703 }
3704
3705 // Fast path way to release a stable ThreadsList. The release portion
3706 // is lock-free, but the wake up portion is not.
3707 //
3708 void Threads::release_stable_list_fast_path(Thread *self) {
3709 assert(self != NULL, "sanity check");
3710 assert(self->get_threads_hazard_ptr() != NULL, "sanity check");
3711 assert(self->get_nested_threads_hazard_ptr() == NULL,
3712 "cannot have a nested hazard ptr when releasing a regular hazard ptr");
3713
3714 // After releasing the hazard ptr, other threads may go ahead and
3715 // free up some memory temporarily used by a ThreadsList snapshot.
3716 self->set_threads_hazard_ptr(NULL);
3717
3718 // We use double-check locking to reduce traffic on the system
3719 // wide smr_delete_lock.
3720 if (Threads::smr_delete_notify()) {
3721 // An exiting thread might be waiting in smr_delete(); we need to
3722 // check with smr_delete_lock to be sure.
3723 release_stable_list_wake_up((char *) "regular hazard ptr");
3724 }
3725 }
3726
3727 // Release a nested stable ThreadsList; this is rare so it uses
3728 // Threads_lock.
3729 //
3730 void Threads::release_stable_list_nested_path(Thread *self) {
3731 assert(self != NULL, "sanity check");
3732 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check");
3733 assert(self->get_threads_hazard_ptr() != NULL,
3734 "must have a regular hazard ptr to have nested hazard ptrs");
3735
3736 // We have a nested ThreadsListHandle so we have to release it first.
3737 // The need for a nested ThreadsListHandle is rare so we do this while
3738 // holding the Threads_lock so we don't race with the scanning code;
3739 // the code is so much simpler this way.
3740
3741 NestedThreadsList *node;
3742 {
3743 // Only grab the Threads_lock if we don't already own it.
3744 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock);
3745 // We remove from the front of the list to match up with the insert
3746 // in acquire_stable_list().
3747 node = self->get_nested_threads_hazard_ptr();
3748 self->set_nested_threads_hazard_ptr(node->next());
3749 if (EnableThreadSMRStatistics) {
3750 self->dec_nested_threads_hazard_ptr_cnt();
3751 }
3752 }
3753
3754 // An exiting thread might be waiting in smr_delete(); we need to
3755 // check with smr_delete_lock to be sure.
3756 release_stable_list_wake_up((char *) "nested hazard ptr");
3757
3758 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()));
3759
3760 delete node;
3761 }
3762
3763 // Wake up portion of the release stable ThreadsList protocol;
3764 // uses the smr_delete_lock().
3765 //
3766 void Threads::release_stable_list_wake_up(char *log_str) {
3767 assert(log_str != NULL, "sanity check");
3768
3769 // Note: smr_delete_lock is held in smr_delete() for the entire
3770 // hazard ptr search so that we do not lose this notify() if
3771 // the exiting thread has to wait. That code path also holds
3772 // Threads_lock (which was grabbed before smr_delete_lock) so that
3773 // threads_do() can be called. This means the system can't start a
3774 // safepoint which means this thread can't take too long to get to
3775 // a safepoint because of being blocked on smr_delete_lock.
3776 //
3777 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag);
3778 if (Threads::smr_delete_notify()) {
3779 // Notify any exiting JavaThreads that are waiting in smr_delete()
3780 // that we've released a ThreadsList.
3781 ml.notify_all();
3782 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str);
3783 }
3784 }
3785
3786 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3787 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3788
3789 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3790 create_vm_init_libraries();
3791 }
3792
3793 initialize_class(vmSymbols::java_lang_String(), CHECK);
3794
3795 // Inject CompactStrings value after the static initializers for String ran.
3796 java_lang_String::set_compact_strings(CompactStrings);
3797
3798 // Initialize java_lang.System (needed before creating the thread)
3799 initialize_class(vmSymbols::java_lang_System(), CHECK);
3800 // The VM creates & returns objects of this class. Make sure it's initialized.
3801 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3802 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3803 Handle thread_group = create_initial_thread_group(CHECK);
3804 Universe::set_main_thread_group(thread_group());
3805 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3806 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3807 main_thread->set_threadObj(thread_object);
3808 // Set thread status to running since main thread has
3809 // been started and running.
3810 java_lang_Thread::set_thread_status(thread_object,
3811 java_lang_Thread::RUNNABLE);
3812
3813 // The VM creates objects of this class.
3814 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3815
3816 // The VM preresolves methods to these classes. Make sure that they get initialized
3817 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3818 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3819
3820 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3821 call_initPhase1(CHECK);
3822
3823 // get the Java runtime name after java.lang.System is initialized
3824 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3825 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3826
3827 // an instance of OutOfMemory exception has been allocated earlier
3828 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3829 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3830 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3831 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3832 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3833 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3834 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3835 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3836 }
3837
3838 void Threads::initialize_jsr292_core_classes(TRAPS) {
3839 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3840
3841 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3842 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3843 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3844 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3845 }
3846
3847 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3848 extern void JDK_Version_init();
3849
3850 // Preinitialize version info.
3851 VM_Version::early_initialize();
3852
3853 // Check version
3854 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3855
3856 // Initialize library-based TLS
3857 ThreadLocalStorage::init();
3858
3859 // Initialize the output stream module
3860 ostream_init();
3861
3862 // Process java launcher properties.
3863 Arguments::process_sun_java_launcher_properties(args);
3864
3865 // Initialize the os module
3866 os::init();
3867
3868 // Record VM creation timing statistics
3869 TraceVmCreationTime create_vm_timer;
3870 create_vm_timer.start();
3871
3872 // Initialize system properties.
3873 Arguments::init_system_properties();
3874
3875 // So that JDK version can be used as a discriminator when parsing arguments
3876 JDK_Version_init();
3877
3878 // Update/Initialize System properties after JDK version number is known
3879 Arguments::init_version_specific_system_properties();
3880
3881 // Make sure to initialize log configuration *before* parsing arguments
3882 LogConfiguration::initialize(create_vm_timer.begin_time());
3883
3884 // Parse arguments
3885 jint parse_result = Arguments::parse(args);
3886 if (parse_result != JNI_OK) return parse_result;
3887
3888 os::init_before_ergo();
3889
3890 jint ergo_result = Arguments::apply_ergo();
3891 if (ergo_result != JNI_OK) return ergo_result;
3892
3893 // Final check of all ranges after ergonomics which may change values.
3894 if (!CommandLineFlagRangeList::check_ranges()) {
3895 return JNI_EINVAL;
3896 }
3897
3898 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3899 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3900 if (!constraint_result) {
3901 return JNI_EINVAL;
3902 }
3903
3904 CommandLineFlagWriteableList::mark_startup();
3905
3906 if (PauseAtStartup) {
3907 os::pause();
3908 }
3909
3910 HOTSPOT_VM_INIT_BEGIN();
3911
3912 // Timing (must come after argument parsing)
3913 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3914
3915 SafepointMechanism::initialize();
3916
3917 // Initialize the os module after parsing the args
3918 jint os_init_2_result = os::init_2();
3919 if (os_init_2_result != JNI_OK) return os_init_2_result;
3920
3921 jint adjust_after_os_result = Arguments::adjust_after_os();
3922 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3923
3924 // Initialize output stream logging
3925 ostream_init_log();
3926
3927 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3928 // Must be before create_vm_init_agents()
3929 if (Arguments::init_libraries_at_startup()) {
3930 convert_vm_init_libraries_to_agents();
3931 }
3932
3933 // Launch -agentlib/-agentpath and converted -Xrun agents
3934 if (Arguments::init_agents_at_startup()) {
3935 create_vm_init_agents();
3936 }
3937
3938 // Initialize Threads state
3939 _thread_list = NULL;
3940 _number_of_threads = 0;
3941 _number_of_non_daemon_threads = 0;
3942
3943 // Initialize global data structures and create system classes in heap
3944 vm_init_globals();
3945
3946 #if INCLUDE_JVMCI
3947 if (JVMCICounterSize > 0) {
3948 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3949 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3950 } else {
3951 JavaThread::_jvmci_old_thread_counters = NULL;
3952 }
3953 #endif // INCLUDE_JVMCI
3954
3955 // Attach the main thread to this os thread
3956 JavaThread* main_thread = new JavaThread();
3957 main_thread->set_thread_state(_thread_in_vm);
3958 main_thread->initialize_thread_current();
3959 // must do this before set_active_handles
3960 main_thread->record_stack_base_and_size();
3961 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3962
3963 if (!main_thread->set_as_starting_thread()) {
3964 vm_shutdown_during_initialization(
3965 "Failed necessary internal allocation. Out of swap space");
3966 main_thread->smr_delete();
3967 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3968 return JNI_ENOMEM;
3969 }
3970
3971 // Enable guard page *after* os::create_main_thread(), otherwise it would
3972 // crash Linux VM, see notes in os_linux.cpp.
3973 main_thread->create_stack_guard_pages();
3974
3975 // Initialize Java-Level synchronization subsystem
3976 ObjectMonitor::Initialize();
3977
3978 // Initialize global modules
3979 jint status = init_globals();
3980 if (status != JNI_OK) {
3981 main_thread->smr_delete();
3982 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3983 return status;
3984 }
3985
3986 if (TRACE_INITIALIZE() != JNI_OK) {
3987 vm_exit_during_initialization("Failed to initialize tracing backend");
3988 }
3989
3990 // Should be done after the heap is fully created
3991 main_thread->cache_global_variables();
3992
3993 HandleMark hm;
3994
3995 { MutexLocker mu(Threads_lock);
3996 Threads::add(main_thread);
3997 }
3998
3999 // Any JVMTI raw monitors entered in onload will transition into
4000 // real raw monitor. VM is setup enough here for raw monitor enter.
4001 JvmtiExport::transition_pending_onload_raw_monitors();
4002
4003 // Create the VMThread
4004 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
4005
4006 VMThread::create();
4007 Thread* vmthread = VMThread::vm_thread();
4008
4009 if (!os::create_thread(vmthread, os::vm_thread)) {
4010 vm_exit_during_initialization("Cannot create VM thread. "
4011 "Out of system resources.");
4012 }
4013
4014 // Wait for the VM thread to become ready, and VMThread::run to initialize
4015 // Monitors can have spurious returns, must always check another state flag
4016 {
4017 MutexLocker ml(Notify_lock);
4018 os::start_thread(vmthread);
4019 while (vmthread->active_handles() == NULL) {
4020 Notify_lock->wait();
4021 }
4022 }
4023 }
4024
4025 assert(Universe::is_fully_initialized(), "not initialized");
4026 if (VerifyDuringStartup) {
4027 // Make sure we're starting with a clean slate.
4028 VM_Verify verify_op;
4029 VMThread::execute(&verify_op);
4030 }
4031
4032 Thread* THREAD = Thread::current();
4033
4034 // Always call even when there are not JVMTI environments yet, since environments
4035 // may be attached late and JVMTI must track phases of VM execution
4036 JvmtiExport::enter_early_start_phase();
4037
4038 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4039 JvmtiExport::post_early_vm_start();
4040
4041 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
4042
4043 // We need this for ClassDataSharing - the initial vm.info property is set
4044 // with the default value of CDS "sharing" which may be reset through
4045 // command line options.
4046 reset_vm_info_property(CHECK_JNI_ERR);
4047
4048 quicken_jni_functions();
4049
4050 // No more stub generation allowed after that point.
4051 StubCodeDesc::freeze();
4052
4053 // Set flag that basic initialization has completed. Used by exceptions and various
4054 // debug stuff, that does not work until all basic classes have been initialized.
4055 set_init_completed();
4056
4057 LogConfiguration::post_initialize();
4058 Metaspace::post_initialize();
4059
4060 HOTSPOT_VM_INIT_END();
4061
4062 // record VM initialization completion time
4063 #if INCLUDE_MANAGEMENT
4064 Management::record_vm_init_completed();
4065 #endif // INCLUDE_MANAGEMENT
4066
4067 // Signal Dispatcher needs to be started before VMInit event is posted
4068 os::signal_init(CHECK_JNI_ERR);
4069
4070 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4071 if (!DisableAttachMechanism) {
4072 AttachListener::vm_start();
4073 if (StartAttachListener || AttachListener::init_at_startup()) {
4074 AttachListener::init();
4075 }
4076 }
4077
4078 // Launch -Xrun agents
4079 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4080 // back-end can launch with -Xdebug -Xrunjdwp.
4081 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4082 create_vm_init_libraries();
4083 }
4084
4085 if (CleanChunkPoolAsync) {
4086 Chunk::start_chunk_pool_cleaner_task();
4087 }
4088
4089 // initialize compiler(s)
4090 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4091 CompileBroker::compilation_init(CHECK_JNI_ERR);
4092 #endif
4093
4094 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4095 // It is done after compilers are initialized, because otherwise compilations of
4096 // signature polymorphic MH intrinsics can be missed
4097 // (see SystemDictionary::find_method_handle_intrinsic).
4098 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4099
4100 // This will initialize the module system. Only java.base classes can be
4101 // loaded until phase 2 completes
4102 call_initPhase2(CHECK_JNI_ERR);
4103
4104 // Always call even when there are not JVMTI environments yet, since environments
4105 // may be attached late and JVMTI must track phases of VM execution
4106 JvmtiExport::enter_start_phase();
4107
4108 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4109 JvmtiExport::post_vm_start();
4110
4111 // Final system initialization including security manager and system class loader
4112 call_initPhase3(CHECK_JNI_ERR);
4113
4114 // cache the system and platform class loaders
4115 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4116
4117 #if INCLUDE_JVMCI
4118 if (EnableJVMCI) {
4119 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
4120 // The JVMCI Java initialization code will read this flag and
4121 // do the printing if it's set.
4122 bool init = JVMCIPrintProperties;
4123
4124 if (!init) {
4125 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4126 // compilations via JVMCI will not actually block until JVMCI is initialized.
4127 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4128 }
4129
4130 if (init) {
4131 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
4132 }
4133 }
4134 #endif
4135
4136 // Always call even when there are not JVMTI environments yet, since environments
4137 // may be attached late and JVMTI must track phases of VM execution
4138 JvmtiExport::enter_live_phase();
4139
4140 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4141 JvmtiExport::post_vm_initialized();
4142
4143 if (TRACE_START() != JNI_OK) {
4144 vm_exit_during_initialization("Failed to start tracing backend.");
4145 }
4146
4147 #if INCLUDE_MANAGEMENT
4148 Management::initialize(THREAD);
4149
4150 if (HAS_PENDING_EXCEPTION) {
4151 // management agent fails to start possibly due to
4152 // configuration problem and is responsible for printing
4153 // stack trace if appropriate. Simply exit VM.
4154 vm_exit(1);
4155 }
4156 #endif // INCLUDE_MANAGEMENT
4157
4158 if (MemProfiling) MemProfiler::engage();
4159 StatSampler::engage();
4160 if (CheckJNICalls) JniPeriodicChecker::engage();
4161
4162 BiasedLocking::init();
4163
4164 #if INCLUDE_RTM_OPT
4165 RTMLockingCounters::init();
4166 #endif
4167
4168 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4169 call_postVMInitHook(THREAD);
4170 // The Java side of PostVMInitHook.run must deal with all
4171 // exceptions and provide means of diagnosis.
4172 if (HAS_PENDING_EXCEPTION) {
4173 CLEAR_PENDING_EXCEPTION;
4174 }
4175 }
4176
4177 {
4178 MutexLocker ml(PeriodicTask_lock);
4179 // Make sure the WatcherThread can be started by WatcherThread::start()
4180 // or by dynamic enrollment.
4181 WatcherThread::make_startable();
4182 // Start up the WatcherThread if there are any periodic tasks
4183 // NOTE: All PeriodicTasks should be registered by now. If they
4184 // aren't, late joiners might appear to start slowly (we might
4185 // take a while to process their first tick).
4186 if (PeriodicTask::num_tasks() > 0) {
4187 WatcherThread::start();
4188 }
4189 }
4190
4191 create_vm_timer.end();
4192 #ifdef ASSERT
4193 _vm_complete = true;
4194 #endif
4195
4196 if (DumpSharedSpaces) {
4197 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4198 ShouldNotReachHere();
4199 }
4200
4201 return JNI_OK;
4202 }
4203
4204 // type for the Agent_OnLoad and JVM_OnLoad entry points
4205 extern "C" {
4206 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4207 }
4208 // Find a command line agent library and return its entry point for
4209 // -agentlib: -agentpath: -Xrun
4210 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4211 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4212 const char *on_load_symbols[],
4213 size_t num_symbol_entries) {
4214 OnLoadEntry_t on_load_entry = NULL;
4215 void *library = NULL;
4216
4217 if (!agent->valid()) {
4218 char buffer[JVM_MAXPATHLEN];
4219 char ebuf[1024] = "";
4220 const char *name = agent->name();
4221 const char *msg = "Could not find agent library ";
4222
4223 // First check to see if agent is statically linked into executable
4224 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4225 library = agent->os_lib();
4226 } else if (agent->is_absolute_path()) {
4227 library = os::dll_load(name, ebuf, sizeof ebuf);
4228 if (library == NULL) {
4229 const char *sub_msg = " in absolute path, with error: ";
4230 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4231 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4232 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4233 // If we can't find the agent, exit.
4234 vm_exit_during_initialization(buf, NULL);
4235 FREE_C_HEAP_ARRAY(char, buf);
4236 }
4237 } else {
4238 // Try to load the agent from the standard dll directory
4239 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4240 name)) {
4241 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4242 }
4243 if (library == NULL) { // Try the library path directory.
4244 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4245 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4246 }
4247 if (library == NULL) {
4248 const char *sub_msg = " on the library 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 }
4257 }
4258 agent->set_os_lib(library);
4259 agent->set_valid();
4260 }
4261
4262 // Find the OnLoad function.
4263 on_load_entry =
4264 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4265 false,
4266 on_load_symbols,
4267 num_symbol_entries));
4268 return on_load_entry;
4269 }
4270
4271 // Find the JVM_OnLoad entry point
4272 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4273 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4274 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4275 }
4276
4277 // Find the Agent_OnLoad entry point
4278 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4279 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4280 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4281 }
4282
4283 // For backwards compatibility with -Xrun
4284 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4285 // treated like -agentpath:
4286 // Must be called before agent libraries are created
4287 void Threads::convert_vm_init_libraries_to_agents() {
4288 AgentLibrary* agent;
4289 AgentLibrary* next;
4290
4291 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4292 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4293 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4294
4295 // If there is an JVM_OnLoad function it will get called later,
4296 // otherwise see if there is an Agent_OnLoad
4297 if (on_load_entry == NULL) {
4298 on_load_entry = lookup_agent_on_load(agent);
4299 if (on_load_entry != NULL) {
4300 // switch it to the agent list -- so that Agent_OnLoad will be called,
4301 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4302 Arguments::convert_library_to_agent(agent);
4303 } else {
4304 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4305 }
4306 }
4307 }
4308 }
4309
4310 // Create agents for -agentlib: -agentpath: and converted -Xrun
4311 // Invokes Agent_OnLoad
4312 // Called very early -- before JavaThreads exist
4313 void Threads::create_vm_init_agents() {
4314 extern struct JavaVM_ main_vm;
4315 AgentLibrary* agent;
4316
4317 JvmtiExport::enter_onload_phase();
4318
4319 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4320 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4321
4322 if (on_load_entry != NULL) {
4323 // Invoke the Agent_OnLoad function
4324 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4325 if (err != JNI_OK) {
4326 vm_exit_during_initialization("agent library failed to init", agent->name());
4327 }
4328 } else {
4329 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4330 }
4331 }
4332 JvmtiExport::enter_primordial_phase();
4333 }
4334
4335 extern "C" {
4336 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4337 }
4338
4339 void Threads::shutdown_vm_agents() {
4340 // Send any Agent_OnUnload notifications
4341 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4342 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4343 extern struct JavaVM_ main_vm;
4344 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4345
4346 // Find the Agent_OnUnload function.
4347 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4348 os::find_agent_function(agent,
4349 false,
4350 on_unload_symbols,
4351 num_symbol_entries));
4352
4353 // Invoke the Agent_OnUnload function
4354 if (unload_entry != NULL) {
4355 JavaThread* thread = JavaThread::current();
4356 ThreadToNativeFromVM ttn(thread);
4357 HandleMark hm(thread);
4358 (*unload_entry)(&main_vm);
4359 }
4360 }
4361 }
4362
4363 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4364 // Invokes JVM_OnLoad
4365 void Threads::create_vm_init_libraries() {
4366 extern struct JavaVM_ main_vm;
4367 AgentLibrary* agent;
4368
4369 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4370 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4371
4372 if (on_load_entry != NULL) {
4373 // Invoke the JVM_OnLoad function
4374 JavaThread* thread = JavaThread::current();
4375 ThreadToNativeFromVM ttn(thread);
4376 HandleMark hm(thread);
4377 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4378 if (err != JNI_OK) {
4379 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4380 }
4381 } else {
4382 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4383 }
4384 }
4385 }
4386
4387
4388 // Last thread running calls java.lang.Shutdown.shutdown()
4389 void JavaThread::invoke_shutdown_hooks() {
4390 HandleMark hm(this);
4391
4392 // We could get here with a pending exception, if so clear it now.
4393 if (this->has_pending_exception()) {
4394 this->clear_pending_exception();
4395 }
4396
4397 EXCEPTION_MARK;
4398 Klass* shutdown_klass =
4399 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4400 THREAD);
4401 if (shutdown_klass != NULL) {
4402 // SystemDictionary::resolve_or_null will return null if there was
4403 // an exception. If we cannot load the Shutdown class, just don't
4404 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4405 // and finalizers (if runFinalizersOnExit is set) won't be run.
4406 // Note that if a shutdown hook was registered or runFinalizersOnExit
4407 // was called, the Shutdown class would have already been loaded
4408 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4409 JavaValue result(T_VOID);
4410 JavaCalls::call_static(&result,
4411 shutdown_klass,
4412 vmSymbols::shutdown_method_name(),
4413 vmSymbols::void_method_signature(),
4414 THREAD);
4415 }
4416 CLEAR_PENDING_EXCEPTION;
4417 }
4418
4419 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4420 // the program falls off the end of main(). Another VM exit path is through
4421 // vm_exit() when the program calls System.exit() to return a value or when
4422 // there is a serious error in VM. The two shutdown paths are not exactly
4423 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4424 // and VM_Exit op at VM level.
4425 //
4426 // Shutdown sequence:
4427 // + Shutdown native memory tracking if it is on
4428 // + Wait until we are the last non-daemon thread to execute
4429 // <-- every thing is still working at this moment -->
4430 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4431 // shutdown hooks, run finalizers if finalization-on-exit
4432 // + Call before_exit(), prepare for VM exit
4433 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4434 // currently the only user of this mechanism is File.deleteOnExit())
4435 // > stop StatSampler, watcher thread, CMS threads,
4436 // post thread end and vm death events to JVMTI,
4437 // stop signal thread
4438 // + Call JavaThread::exit(), it will:
4439 // > release JNI handle blocks, remove stack guard pages
4440 // > remove this thread from Threads list
4441 // <-- no more Java code from this thread after this point -->
4442 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4443 // the compiler threads at safepoint
4444 // <-- do not use anything that could get blocked by Safepoint -->
4445 // + Disable tracing at JNI/JVM barriers
4446 // + Set _vm_exited flag for threads that are still running native code
4447 // + Delete this thread
4448 // + Call exit_globals()
4449 // > deletes tty
4450 // > deletes PerfMemory resources
4451 // + Return to caller
4452
4453 bool Threads::destroy_vm() {
4454 JavaThread* thread = JavaThread::current();
4455
4456 #ifdef ASSERT
4457 _vm_complete = false;
4458 #endif
4459 // Wait until we are the last non-daemon thread to execute
4460 { MutexLocker nu(Threads_lock);
4461 while (Threads::number_of_non_daemon_threads() > 1)
4462 // This wait should make safepoint checks, wait without a timeout,
4463 // and wait as a suspend-equivalent condition.
4464 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4465 Mutex::_as_suspend_equivalent_flag);
4466 }
4467
4468 // Hang forever on exit if we are reporting an error.
4469 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4470 os::infinite_sleep();
4471 }
4472 os::wait_for_keypress_at_exit();
4473
4474 // run Java level shutdown hooks
4475 thread->invoke_shutdown_hooks();
4476
4477 before_exit(thread);
4478
4479 thread->exit(true);
4480
4481 // Stop VM thread.
4482 {
4483 // 4945125 The vm thread comes to a safepoint during exit.
4484 // GC vm_operations can get caught at the safepoint, and the
4485 // heap is unparseable if they are caught. Grab the Heap_lock
4486 // to prevent this. The GC vm_operations will not be able to
4487 // queue until after the vm thread is dead. After this point,
4488 // we'll never emerge out of the safepoint before the VM exits.
4489
4490 MutexLocker ml(Heap_lock);
4491
4492 VMThread::wait_for_vm_thread_exit();
4493 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4494 VMThread::destroy();
4495 }
4496
4497 // clean up ideal graph printers
4498 #if defined(COMPILER2) && !defined(PRODUCT)
4499 IdealGraphPrinter::clean_up();
4500 #endif
4501
4502 // Now, all Java threads are gone except daemon threads. Daemon threads
4503 // running Java code or in VM are stopped by the Safepoint. However,
4504 // daemon threads executing native code are still running. But they
4505 // will be stopped at native=>Java/VM barriers. Note that we can't
4506 // simply kill or suspend them, as it is inherently deadlock-prone.
4507
4508 VM_Exit::set_vm_exited();
4509
4510 notify_vm_shutdown();
4511
4512 // We are after VM_Exit::set_vm_exited() so we can't call
4513 // thread->smr_delete() or we will block on the Threads_lock.
4514 // Deleting the shutdown thread here is safe because another
4515 // JavaThread cannot have an active ThreadsListHandle for
4516 // this JavaThread.
4517 delete thread;
4518
4519 #if INCLUDE_JVMCI
4520 if (JVMCICounterSize > 0) {
4521 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4522 }
4523 #endif
4524
4525 // exit_globals() will delete tty
4526 exit_globals();
4527
4528 LogConfiguration::finalize();
4529
4530 return true;
4531 }
4532
4533
4534 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4535 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4536 return is_supported_jni_version(version);
4537 }
4538
4539
4540 jboolean Threads::is_supported_jni_version(jint version) {
4541 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4542 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4543 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4544 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4545 if (version == JNI_VERSION_9) return JNI_TRUE;
4546 if (version == JNI_VERSION_10) return JNI_TRUE;
4547 return JNI_FALSE;
4548 }
4549
4550 // Hash table of pointers found by a scan. Used for collecting hazard
4551 // pointers (ThreadsList references). Also used for collecting JavaThreads
4552 // that are indirectly referenced by hazard ptrs. An instance of this
4553 // class only contains one type of pointer.
4554 //
4555 class ThreadScanHashtable : public CHeapObj<mtThread> {
4556 private:
4557 static bool ptr_equals(void * const& s1, void * const& s2) {
4558 return s1 == s2;
4559 }
4560
4561 static unsigned int ptr_hash(void * const& s1) {
4562 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
4563 }
4564
4565 int _table_size;
4566 // ResourceHashtable SIZE is specified at compile time so our
4567 // dynamic _table_size is unused for now; 1031 is the first prime
4568 // after 1024.
4569 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash,
4570 &ThreadScanHashtable::ptr_equals, 1031,
4571 ResourceObj::C_HEAP, mtThread> PtrTable;
4572 PtrTable * _ptrs;
4573
4574 public:
4575 // ResourceHashtable is passed to various functions and populated in
4576 // different places so we allocate it using C_HEAP to make it immune
4577 // from any ResourceMarks that happen to be in the code paths.
4578 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {}
4579
4580 ~ThreadScanHashtable() { delete _ptrs; }
4581
4582 bool has_entry(void *pointer) {
4583 int *val_ptr = _ptrs->get(pointer);
4584 return val_ptr != NULL && *val_ptr == 1;
4585 }
4586
4587 void add_entry(void *pointer) {
4588 _ptrs->put(pointer, 1);
4589 }
4590 };
4591
4592 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4593 // (ThreadsList references) into a hash table. This closure handles part 2
4594 // of the dance - adding all the JavaThreads referenced by the hazard
4595 // pointer (ThreadsList reference) to the hash table.
4596 //
4597 class AddThreadHazardPointerThreadClosure : public ThreadClosure {
4598 private:
4599 ThreadScanHashtable *_table;
4600
4601 public:
4602 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {}
4603
4604 virtual void do_thread(Thread *thread) {
4605 if (!_table->has_entry((void*)thread)) {
4606 // The same JavaThread might be on more than one ThreadsList or
4607 // more than one thread might be using the same ThreadsList. In
4608 // either case, we only need a single entry for a JavaThread.
4609 _table->add_entry((void*)thread);
4610 }
4611 }
4612 };
4613
4614 // Closure to gather JavaThreads indirectly referenced by hazard ptrs
4615 // (ThreadsList references) into a hash table. This closure handles part 1
4616 // of the dance - hazard ptr chain walking and dispatch to another
4617 // closure.
4618 //
4619 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure {
4620 private:
4621 ThreadScanHashtable *_table;
4622 public:
4623 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {}
4624
4625 virtual void do_thread(Thread *thread) {
4626 assert_locked_or_safepoint(Threads_lock);
4627
4628 if (thread == NULL) return;
4629
4630 // This code races with Threads::acquire_stable_list() which is
4631 // lock-free so we have to handle some special situations.
4632 //
4633 ThreadsList *current_list = NULL;
4634 while (true) {
4635 current_list = thread->get_threads_hazard_ptr();
4636 // No hazard ptr so nothing more to do.
4637 if (current_list == NULL) {
4638 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4639 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4640 return;
4641 }
4642
4643 // If the hazard ptr is verified as stable (since it is not tagged),
4644 // then it is safe to use.
4645 if (!Thread::is_hazard_ptr_tagged(current_list)) break;
4646
4647 // The hazard ptr is tagged as not yet verified as being stable
4648 // so we are racing with acquire_stable_list(). This exchange
4649 // attempts to invalidate the hazard ptr. If we win the race,
4650 // then we can ignore this unstable hazard ptr and the other
4651 // thread will retry the attempt to publish a stable hazard ptr.
4652 // If we lose the race, then we retry our attempt to look at the
4653 // hazard ptr.
4654 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return;
4655 }
4656
4657 // The current JavaThread has a hazard ptr (ThreadsList reference)
4658 // which might be _smr_java_thread_list or it might be an older
4659 // ThreadsList that has been removed but not freed. In either case,
4660 // the hazard ptr is protecting all the JavaThreads on that
4661 // ThreadsList.
4662 AddThreadHazardPointerThreadClosure add_cl(_table);
4663 current_list->threads_do(&add_cl);
4664
4665 // Any NestedThreadsLists are also protecting JavaThreads so
4666 // gather those also; the ThreadsLists may be different.
4667 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4668 node != NULL; node = node->next()) {
4669 node->t_list()->threads_do(&add_cl);
4670 }
4671 }
4672 };
4673
4674 // Closure to print JavaThreads that have a hazard ptr (ThreadsList
4675 // reference) that contains an indirect reference to a specific JavaThread.
4676 //
4677 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure {
4678 private:
4679 JavaThread *_thread;
4680 public:
4681 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {}
4682
4683 virtual void do_thread(Thread *thread) {
4684 assert_locked_or_safepoint(Threads_lock);
4685
4686 if (thread == NULL) return;
4687 ThreadsList *current_list = thread->get_threads_hazard_ptr();
4688 if (current_list == NULL) {
4689 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4690 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4691 return;
4692 }
4693 // If the hazard ptr is unverified, then ignore it.
4694 if (Thread::is_hazard_ptr_tagged(current_list)) return;
4695
4696 // The current JavaThread has a hazard ptr (ThreadsList reference)
4697 // which might be _smr_java_thread_list or it might be an older
4698 // ThreadsList that has been removed but not freed. In either case,
4699 // the hazard ptr is protecting all the JavaThreads on that
4700 // ThreadsList, but we only care about matching a specific JavaThread.
4701 DO_JAVA_THREADS(current_list, p) {
4702 if (p == _thread) {
4703 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));
4704 break;
4705 }
4706 }
4707
4708 // Any NestedThreadsLists are also protecting JavaThreads so
4709 // check those also; the ThreadsLists may be different.
4710 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4711 node != NULL; node = node->next()) {
4712 DO_JAVA_THREADS(node->t_list(), p) {
4713 if (p == _thread) {
4714 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));
4715 return;
4716 }
4717 }
4718 }
4719 }
4720 };
4721
4722 // Return true if the specified JavaThread is protected by a hazard
4723 // pointer (ThreadsList reference). Otherwise, returns false.
4724 //
4725 bool Threads::is_a_protected_JavaThread(JavaThread *thread) {
4726 assert_locked_or_safepoint(Threads_lock);
4727
4728 // Hash table size should be first power of two higher than twice
4729 // the length of the Threads list.
4730 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4731 hash_table_size--;
4732 hash_table_size |= hash_table_size >> 1;
4733 hash_table_size |= hash_table_size >> 2;
4734 hash_table_size |= hash_table_size >> 4;
4735 hash_table_size |= hash_table_size >> 8;
4736 hash_table_size |= hash_table_size >> 16;
4737 hash_table_size++;
4738
4739 // Gather a hash table of the JavaThreads indirectly referenced by
4740 // hazard ptrs.
4741 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4742 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table);
4743 Threads::threads_do(&scan_cl);
4744
4745 bool thread_is_protected = false;
4746 if (scan_table->has_entry((void*)thread)) {
4747 thread_is_protected = true;
4748 }
4749 delete scan_table;
4750 return thread_is_protected;
4751 }
4752
4753 // Safely delete a JavaThread when it is no longer in use by a
4754 // ThreadsListHandle.
4755 //
4756 void Threads::smr_delete(JavaThread *thread) {
4757 assert(!Threads_lock->owned_by_self(), "sanity");
4758
4759 bool has_logged_once = false;
4760 elapsedTimer timer;
4761 if (EnableThreadSMRStatistics) {
4762 timer.start();
4763 }
4764
4765 while (true) {
4766 {
4767 // No safepoint check because this JavaThread is not on the
4768 // Threads list.
4769 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
4770 // Cannot use a MonitorLockerEx helper here because we have
4771 // to drop the Threads_lock first if we wait.
4772 Threads::smr_delete_lock()->lock_without_safepoint_check();
4773 // Set the smr_delete_notify flag after we grab smr_delete_lock
4774 // and before we scan hazard ptrs because we're doing
4775 // double-check locking in release_stable_list().
4776 Threads::set_smr_delete_notify();
4777
4778 if (!is_a_protected_JavaThread(thread)) {
4779 // This is the common case.
4780 Threads::clear_smr_delete_notify();
4781 Threads::smr_delete_lock()->unlock();
4782 break;
4783 }
4784 if (!has_logged_once) {
4785 has_logged_once = true;
4786 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread));
4787 if (log_is_enabled(Debug, os, thread)) {
4788 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread);
4789 Threads::threads_do(&scan_cl);
4790 }
4791 }
4792 } // We have to drop the Threads_lock to wait or delete the thread
4793
4794 if (EnableThreadSMRStatistics) {
4795 _smr_delete_lock_wait_cnt++;
4796 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) {
4797 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt;
4798 }
4799 }
4800 // Wait for a release_stable_list() call before we check again. No
4801 // safepoint check, no timeout, and not as suspend equivalent flag
4802 // because this JavaThread is not on the Threads list.
4803 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0,
4804 !Mutex::_as_suspend_equivalent_flag);
4805 if (EnableThreadSMRStatistics) {
4806 _smr_delete_lock_wait_cnt--;
4807 }
4808
4809 Threads::clear_smr_delete_notify();
4810 Threads::smr_delete_lock()->unlock();
4811 // Retry the whole scenario.
4812 }
4813
4814 delete thread;
4815 if (EnableThreadSMRStatistics) {
4816 timer.stop();
4817 jint millis = (jint)timer.milliseconds();
4818 Threads::inc_smr_deleted_thread_cnt();
4819 Threads::add_smr_deleted_thread_times(millis);
4820 Threads::update_smr_deleted_thread_time_max(millis);
4821 }
4822
4823 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread));
4824 }
4825
4826 bool Threads::smr_delete_notify() {
4827 // Use load_acquire() in order to see any updates to _smr_delete_notify
4828 // earlier than when smr_delete_lock is grabbed.
4829 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0);
4830 }
4831
4832 // set_smr_delete_notify() and clear_smr_delete_notify() are called
4833 // under the protection of the smr_delete_lock, but we also use an
4834 // Atomic operation to ensure the memory update is seen earlier than
4835 // when the smr_delete_lock is dropped.
4836 //
4837 void Threads::set_smr_delete_notify() {
4838 Atomic::inc(&_smr_delete_notify);
4839 }
4840
4841 void Threads::clear_smr_delete_notify() {
4842 Atomic::dec(&_smr_delete_notify);
4843 }
4844
4845 // Closure to gather hazard ptrs (ThreadsList references) into a hash table.
4846 //
4847 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure {
4848 private:
4849 ThreadScanHashtable *_table;
4850 public:
4851 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {}
4852
4853 virtual void do_thread(Thread* thread) {
4854 assert_locked_or_safepoint(Threads_lock);
4855
4856 if (thread == NULL) return;
4857 ThreadsList *threads = thread->get_threads_hazard_ptr();
4858 if (threads == NULL) {
4859 assert(thread->get_nested_threads_hazard_ptr() == NULL,
4860 "cannot have a nested hazard ptr with a NULL regular hazard ptr");
4861 return;
4862 }
4863 // In this closure we always ignore the tag that might mark this
4864 // hazard ptr as not yet verified. If we happen to catch an
4865 // unverified hazard ptr that is subsequently discarded (not
4866 // published), then the only side effect is that we might keep a
4867 // to-be-deleted ThreadsList alive a little longer.
4868 threads = Thread::untag_hazard_ptr(threads);
4869 if (!_table->has_entry((void*)threads)) {
4870 _table->add_entry((void*)threads);
4871 }
4872
4873 // Any NestedThreadsLists are also protecting JavaThreads so
4874 // gather those also; the ThreadsLists may be different.
4875 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr();
4876 node != NULL; node = node->next()) {
4877 threads = node->t_list();
4878 if (!_table->has_entry((void*)threads)) {
4879 _table->add_entry((void*)threads);
4880 }
4881 }
4882 }
4883 };
4884
4885 // Safely free a ThreadsList after a Threads::add() or Threads::remove().
4886 // The specified ThreadsList may not get deleted during this call if it
4887 // is still in-use (referenced by a hazard ptr). Other ThreadsLists
4888 // in the chain may get deleted by this call if they are no longer in-use.
4889 void Threads::smr_free_list(ThreadsList* threads) {
4890 assert_locked_or_safepoint(Threads_lock);
4891
4892 threads->set_next_list(_smr_to_delete_list);
4893 _smr_to_delete_list = threads;
4894 if (EnableThreadSMRStatistics) {
4895 _smr_to_delete_list_cnt++;
4896 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) {
4897 _smr_to_delete_list_max = _smr_to_delete_list_cnt;
4898 }
4899 }
4900
4901 // Hash table size should be first power of two higher than twice the length of the ThreadsList
4902 int hash_table_size = MIN2(_number_of_threads, 32) << 1;
4903 hash_table_size--;
4904 hash_table_size |= hash_table_size >> 1;
4905 hash_table_size |= hash_table_size >> 2;
4906 hash_table_size |= hash_table_size >> 4;
4907 hash_table_size |= hash_table_size >> 8;
4908 hash_table_size |= hash_table_size >> 16;
4909 hash_table_size++;
4910
4911 // Gather a hash table of the current hazard ptrs:
4912 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size);
4913 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table);
4914 Threads::threads_do(&scan_cl);
4915
4916 // Walk through the linked list of pending freeable ThreadsLists
4917 // and free the ones that are not referenced from hazard ptrs.
4918 ThreadsList* current = _smr_to_delete_list;
4919 ThreadsList* prev = NULL;
4920 ThreadsList* next = NULL;
4921 bool threads_is_freed = false;
4922 while (current != NULL) {
4923 next = current->next_list();
4924 if (!scan_table->has_entry((void*)current)) {
4925 // This ThreadsList is not referenced by a hazard ptr.
4926 if (prev != NULL) {
4927 prev->set_next_list(next);
4928 }
4929 if (_smr_to_delete_list == current) {
4930 _smr_to_delete_list = next;
4931 }
4932
4933 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current));
4934 if (current == threads) threads_is_freed = true;
4935 delete current;
4936 if (EnableThreadSMRStatistics) {
4937 _smr_java_thread_list_free_cnt++;
4938 _smr_to_delete_list_cnt--;
4939 }
4940 } else {
4941 prev = current;
4942 }
4943 current = next;
4944 }
4945
4946 if (!threads_is_freed) {
4947 // Only report "is not freed" on the original call to
4948 // smr_free_list() for this ThreadsList.
4949 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads));
4950 }
4951
4952 delete scan_table;
4953 }
4954
4955 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a
4956 // new copy of the specified ThreadsList with the specified JavaThread
4957 // removed.
4958 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) {
4959 assert(list->_length > 0, "sanity");
4960
4961 uint i = 0;
4962 DO_JAVA_THREADS(list, current) {
4963 if (current == java_thread) {
4964 break;
4965 }
4966 i++;
4967 }
4968 assert(i < list->_length, "did not find JavaThread on the list");
4969 const uint index = i;
4970 const uint new_length = list->_length - 1;
4971 const uint head_length = index;
4972 const uint tail_length = (new_length >= index) ? (new_length - index) : 0;
4973 ThreadsList *const new_list = new ThreadsList(new_length);
4974
4975 if (head_length > 0) {
4976 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length);
4977 }
4978 if (tail_length > 0) {
4979 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length);
4980 }
4981
4982 return new_list;
4983 }
4984
4985 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a
4986 // new copy of the specified ThreadsList with the specified JavaThread
4987 // appended to the end.
4988 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) {
4989 const uint index = list->_length;
4990 const uint new_length = index + 1;
4991 const uint head_length = index;
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 *(JavaThread**)(new_list->_threads + index) = java_thread;
4998
4999 return new_list;
5000 }
5001
5002 int ThreadsList::find_index_of_JavaThread(JavaThread *target) {
5003 if (target == NULL) {
5004 return -1;
5005 }
5006 for (uint i = 0; i < length(); i++) {
5007 if (target == thread_at(i)) {
5008 return (int)i;
5009 }
5010 }
5011 return -1;
5012 }
5013
5014 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const {
5015 DO_JAVA_THREADS(this, thread) {
5016 oop tobj = thread->threadObj();
5017 // Ignore the thread if it hasn't run yet, has exited
5018 // or is starting to exit.
5019 if (tobj != NULL && !thread->is_exiting() &&
5020 java_tid == java_lang_Thread::thread_id(tobj)) {
5021 // found a match
5022 return thread;
5023 }
5024 }
5025 return NULL;
5026 }
5027
5028 bool ThreadsList::includes(const JavaThread * const p) const {
5029 if (p == NULL) {
5030 return false;
5031 }
5032 DO_JAVA_THREADS(this, q) {
5033 if (q == p) {
5034 return true;
5035 }
5036 }
5037 return false;
5038 }
5039
5040 void Threads::add(JavaThread* p, bool force_daemon) {
5041 // The threads lock must be owned at this point
5042 assert_locked_or_safepoint(Threads_lock);
5043
5044 // See the comment for this method in thread.hpp for its purpose and
5045 // why it is called here.
5046 p->initialize_queues();
5047 p->set_next(_thread_list);
5048 _thread_list = p;
5049
5050 // Once a JavaThread is added to the Threads list, smr_delete() has
5051 // to be used to delete it. Otherwise we can just delete it directly.
5052 p->set_on_thread_list();
5053
5054 _number_of_threads++;
5055 oop threadObj = p->threadObj();
5056 bool daemon = true;
5057 // Bootstrapping problem: threadObj can be null for initial
5058 // JavaThread (or for threads attached via JNI)
5059 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
5060 _number_of_non_daemon_threads++;
5061 daemon = false;
5062 }
5063
5064 ThreadService::add_thread(p, daemon);
5065
5066 // Maintain fast thread list
5067 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p);
5068 if (EnableThreadSMRStatistics) {
5069 _smr_java_thread_list_alloc_cnt++;
5070 if (new_list->length() > _smr_java_thread_list_max) {
5071 _smr_java_thread_list_max = new_list->length();
5072 }
5073 }
5074 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg.
5075 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5076
5077 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5078 smr_free_list(old_list);
5079
5080 // Possible GC point.
5081 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
5082 }
5083
5084 void Threads::remove(JavaThread* p) {
5085
5086 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
5087 ObjectSynchronizer::omFlush(p);
5088
5089 // Extra scope needed for Thread_lock, so we can check
5090 // that we do not remove thread without safepoint code notice
5091 { MutexLocker ml(Threads_lock);
5092
5093 assert(get_smr_java_thread_list()->includes(p), "p must be present");
5094
5095 // Maintain fast thread list
5096 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p);
5097 if (EnableThreadSMRStatistics) {
5098 _smr_java_thread_list_alloc_cnt++;
5099 // This list is smaller so no need to check for a "longest" update.
5100 }
5101
5102 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg.
5103 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list));
5104
5105 ThreadsList *old_list = xchg_smr_java_thread_list(new_list);
5106 smr_free_list(old_list);
5107
5108 JavaThread* current = _thread_list;
5109 JavaThread* prev = NULL;
5110
5111 while (current != p) {
5112 prev = current;
5113 current = current->next();
5114 }
5115
5116 if (prev) {
5117 prev->set_next(current->next());
5118 } else {
5119 _thread_list = p->next();
5120 }
5121
5122 _number_of_threads--;
5123 oop threadObj = p->threadObj();
5124 bool daemon = true;
5125 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
5126 _number_of_non_daemon_threads--;
5127 daemon = false;
5128
5129 // Only one thread left, do a notify on the Threads_lock so a thread waiting
5130 // on destroy_vm will wake up.
5131 if (number_of_non_daemon_threads() == 1) {
5132 Threads_lock->notify_all();
5133 }
5134 }
5135 ThreadService::remove_thread(p, daemon);
5136
5137 // Make sure that safepoint code disregard this thread. This is needed since
5138 // the thread might mess around with locks after this point. This can cause it
5139 // to do callbacks into the safepoint code. However, the safepoint code is not aware
5140 // of this thread since it is removed from the queue.
5141 p->set_terminated_value();
5142 } // unlock Threads_lock
5143
5144 // Since Events::log uses a lock, we grab it outside the Threads_lock
5145 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
5146 }
5147
5148 // Operations on the Threads list for GC. These are not explicitly locked,
5149 // but the garbage collector must provide a safe context for them to run.
5150 // In particular, these things should never be called when the Threads_lock
5151 // is held by some other thread. (Note: the Safepoint abstraction also
5152 // uses the Threads_lock to guarantee this property. It also makes sure that
5153 // all threads gets blocked when exiting or starting).
5154
5155 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
5156 ALL_JAVA_THREADS(p) {
5157 p->oops_do(f, cf);
5158 }
5159 VMThread::vm_thread()->oops_do(f, cf);
5160 }
5161
5162 void Threads::change_thread_claim_parity() {
5163 // Set the new claim parity.
5164 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
5165 "Not in range.");
5166 _thread_claim_parity++;
5167 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
5168 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
5169 "Not in range.");
5170 }
5171
5172 #ifdef ASSERT
5173 void Threads::assert_all_threads_claimed() {
5174 ALL_JAVA_THREADS(p) {
5175 const int thread_parity = p->oops_do_parity();
5176 assert((thread_parity == _thread_claim_parity),
5177 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
5178 }
5179 VMThread* vmt = VMThread::vm_thread();
5180 const int thread_parity = vmt->oops_do_parity();
5181 assert((thread_parity == _thread_claim_parity),
5182 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
5183 }
5184 #endif // ASSERT
5185
5186 class ParallelOopsDoThreadClosure : public ThreadClosure {
5187 private:
5188 OopClosure* _f;
5189 CodeBlobClosure* _cf;
5190 public:
5191 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
5192 void do_thread(Thread* t) {
5193 t->oops_do(_f, _cf);
5194 }
5195 };
5196
5197 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
5198 ParallelOopsDoThreadClosure tc(f, cf);
5199 possibly_parallel_threads_do(is_par, &tc);
5200 }
5201
5202 #if INCLUDE_ALL_GCS
5203 // Used by ParallelScavenge
5204 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
5205 ALL_JAVA_THREADS(p) {
5206 q->enqueue(new ThreadRootsTask(p));
5207 }
5208 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
5209 }
5210
5211 // Used by Parallel Old
5212 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
5213 ALL_JAVA_THREADS(p) {
5214 q->enqueue(new ThreadRootsMarkingTask(p));
5215 }
5216 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
5217 }
5218 #endif // INCLUDE_ALL_GCS
5219
5220 void Threads::nmethods_do(CodeBlobClosure* cf) {
5221 ALL_JAVA_THREADS(p) {
5222 // This is used by the code cache sweeper to mark nmethods that are active
5223 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
5224 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
5225 if(!p->is_Code_cache_sweeper_thread()) {
5226 p->nmethods_do(cf);
5227 }
5228 }
5229 }
5230
5231 void Threads::metadata_do(void f(Metadata*)) {
5232 ALL_JAVA_THREADS(p) {
5233 p->metadata_do(f);
5234 }
5235 }
5236
5237 class ThreadHandlesClosure : public ThreadClosure {
5238 void (*_f)(Metadata*);
5239 public:
5240 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
5241 virtual void do_thread(Thread* thread) {
5242 thread->metadata_handles_do(_f);
5243 }
5244 };
5245
5246 void Threads::metadata_handles_do(void f(Metadata*)) {
5247 // Only walk the Handles in Thread.
5248 ThreadHandlesClosure handles_closure(f);
5249 threads_do(&handles_closure);
5250 }
5251
5252 void Threads::deoptimized_wrt_marked_nmethods() {
5253 ALL_JAVA_THREADS(p) {
5254 p->deoptimized_wrt_marked_nmethods();
5255 }
5256 }
5257
5258
5259 // Get count Java threads that are waiting to enter the specified monitor.
5260 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
5261 int count,
5262 address monitor) {
5263 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
5264
5265 int i = 0;
5266 DO_JAVA_THREADS(t_list, p) {
5267 if (!p->can_call_java()) continue;
5268
5269 address pending = (address)p->current_pending_monitor();
5270 if (pending == monitor) { // found a match
5271 if (i < count) result->append(p); // save the first count matches
5272 i++;
5273 }
5274 }
5275
5276 return result;
5277 }
5278
5279
5280 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
5281 address owner) {
5282 // NULL owner means not locked so we can skip the search
5283 if (owner == NULL) return NULL;
5284
5285 DO_JAVA_THREADS(t_list, p) {
5286 // first, see if owner is the address of a Java thread
5287 if (owner == (address)p) return p;
5288 }
5289
5290 // Cannot assert on lack of success here since this function may be
5291 // used by code that is trying to report useful problem information
5292 // like deadlock detection.
5293 if (UseHeavyMonitors) return NULL;
5294
5295 // If we didn't find a matching Java thread and we didn't force use of
5296 // heavyweight monitors, then the owner is the stack address of the
5297 // Lock Word in the owning Java thread's stack.
5298 //
5299 JavaThread* the_owner = NULL;
5300 DO_JAVA_THREADS(t_list, q) {
5301 if (q->is_lock_owned(owner)) {
5302 the_owner = q;
5303 break;
5304 }
5305 }
5306
5307 // cannot assert on lack of success here; see above comment
5308 return the_owner;
5309 }
5310
5311 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
5312 void Threads::print_on(outputStream* st, bool print_stacks,
5313 bool internal_format, bool print_concurrent_locks) {
5314 char buf[32];
5315 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
5316
5317 st->print_cr("Full thread dump %s (%s %s):",
5318 Abstract_VM_Version::vm_name(),
5319 Abstract_VM_Version::vm_release(),
5320 Abstract_VM_Version::vm_info_string());
5321 st->cr();
5322
5323 #if INCLUDE_SERVICES
5324 // Dump concurrent locks
5325 ConcurrentLocksDump concurrent_locks;
5326 if (print_concurrent_locks) {
5327 concurrent_locks.dump_at_safepoint();
5328 }
5329 #endif // INCLUDE_SERVICES
5330
5331 print_smr_info_on(st);
5332 st->cr();
5333
5334 ALL_JAVA_THREADS(p) {
5335 ResourceMark rm;
5336 p->print_on(st);
5337 if (print_stacks) {
5338 if (internal_format) {
5339 p->trace_stack();
5340 } else {
5341 p->print_stack_on(st);
5342 }
5343 }
5344 st->cr();
5345 #if INCLUDE_SERVICES
5346 if (print_concurrent_locks) {
5347 concurrent_locks.print_locks_on(p, st);
5348 }
5349 #endif // INCLUDE_SERVICES
5350 }
5351
5352 VMThread::vm_thread()->print_on(st);
5353 st->cr();
5354 Universe::heap()->print_gc_threads_on(st);
5355 WatcherThread* wt = WatcherThread::watcher_thread();
5356 if (wt != NULL) {
5357 wt->print_on(st);
5358 st->cr();
5359 }
5360
5361 st->flush();
5362 }
5363
5364 // Log Threads class SMR info.
5365 void Threads::log_smr_statistics() {
5366 LogTarget(Info, thread, smr) log;
5367 if (log.is_enabled()) {
5368 LogStream out(log);
5369 print_smr_info_on(&out);
5370 }
5371 }
5372
5373 // Print Threads class SMR info.
5374 void Threads::print_smr_info_on(outputStream* st) {
5375 // Only grab the Threads_lock if we don't already own it
5376 // and if we are not reporting an error.
5377 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock);
5378
5379 st->print_cr("Threads class SMR info:");
5380 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, "
5381 "elements={", p2i(_smr_java_thread_list),
5382 _smr_java_thread_list->length());
5383 print_smr_info_elements_on(st, _smr_java_thread_list);
5384 st->print_cr("}");
5385 if (_smr_to_delete_list != NULL) {
5386 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, "
5387 "elements={", p2i(_smr_to_delete_list),
5388 _smr_to_delete_list->length());
5389 print_smr_info_elements_on(st, _smr_to_delete_list);
5390 st->print_cr("}");
5391 for (ThreadsList *t_list = _smr_to_delete_list->next_list();
5392 t_list != NULL; t_list = t_list->next_list()) {
5393 st->print("next-> " INTPTR_FORMAT ", length=%u, "
5394 "elements={", p2i(t_list), t_list->length());
5395 print_smr_info_elements_on(st, t_list);
5396 st->print_cr("}");
5397 }
5398 }
5399 if (!EnableThreadSMRStatistics) {
5400 return;
5401 }
5402 st->print_cr("_smr_java_thread_list_alloc_cnt=%ld, "
5403 "_smr_java_thread_list_free_cnt=%ld, "
5404 "_smr_java_thread_list_max=%u, "
5405 "_smr_nested_thread_list_max=%u",
5406 _smr_java_thread_list_alloc_cnt,
5407 _smr_java_thread_list_free_cnt,
5408 _smr_java_thread_list_max,
5409 _smr_nested_thread_list_max);
5410 if (_smr_tlh_cnt > 0) {
5411 st->print_cr("_smr_tlh_cnt=" INT32_FORMAT
5412 ", _smr_tlh_times=" INT32_FORMAT
5413 ", avg_smr_tlh_time=%0.2f"
5414 ", _smr_tlh_time_max=" INT32_FORMAT,
5415 _smr_tlh_cnt, _smr_tlh_times,
5416 ((double) _smr_tlh_times / _smr_tlh_cnt),
5417 _smr_tlh_time_max);
5418 }
5419 if (_smr_deleted_thread_cnt > 0) {
5420 st->print_cr("_smr_deleted_thread_cnt=" INT32_FORMAT
5421 ", _smr_deleted_thread_times=" INT32_FORMAT
5422 ", avg_smr_deleted_thread_time=%0.2f"
5423 ", _smr_deleted_thread_time_max=" INT32_FORMAT,
5424 _smr_deleted_thread_cnt, _smr_deleted_thread_times,
5425 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt),
5426 _smr_deleted_thread_time_max);
5427 }
5428 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u",
5429 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max);
5430 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u",
5431 _smr_to_delete_list_cnt, _smr_to_delete_list_max);
5432 }
5433
5434 // Print ThreadsList elements (4 per line).
5435 void Threads::print_smr_info_elements_on(outputStream* st,
5436 ThreadsList* t_list) {
5437 uint cnt = 0;
5438 JavaThreadIterator jti(t_list);
5439 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) {
5440 st->print(INTPTR_FORMAT, p2i(jt));
5441 if (cnt < t_list->length() - 1) {
5442 // Separate with comma or comma-space except for the last one.
5443 if (((cnt + 1) % 4) == 0) {
5444 // Four INTPTR_FORMAT fit on an 80 column line so end the
5445 // current line with just a comma.
5446 st->print_cr(",");
5447 } else {
5448 // Not the last one on the current line so use comma-space:
5449 st->print(", ");
5450 }
5451 } else {
5452 // Last one so just end the current line.
5453 st->cr();
5454 }
5455 cnt++;
5456 }
5457 }
5458
5459 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
5460 int buflen, bool* found_current) {
5461 if (this_thread != NULL) {
5462 bool is_current = (current == this_thread);
5463 *found_current = *found_current || is_current;
5464 st->print("%s", is_current ? "=>" : " ");
5465
5466 st->print(PTR_FORMAT, p2i(this_thread));
5467 st->print(" ");
5468 this_thread->print_on_error(st, buf, buflen);
5469 st->cr();
5470 }
5471 }
5472
5473 class PrintOnErrorClosure : public ThreadClosure {
5474 outputStream* _st;
5475 Thread* _current;
5476 char* _buf;
5477 int _buflen;
5478 bool* _found_current;
5479 public:
5480 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
5481 int buflen, bool* found_current) :
5482 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
5483
5484 virtual void do_thread(Thread* thread) {
5485 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
5486 }
5487 };
5488
5489 // Threads::print_on_error() is called by fatal error handler. It's possible
5490 // that VM is not at safepoint and/or current thread is inside signal handler.
5491 // Don't print stack trace, as the stack may not be walkable. Don't allocate
5492 // memory (even in resource area), it might deadlock the error handler.
5493 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
5494 int buflen) {
5495 print_smr_info_on(st);
5496 st->cr();
5497
5498 bool found_current = false;
5499 st->print_cr("Java Threads: ( => current thread )");
5500 ALL_JAVA_THREADS(thread) {
5501 print_on_error(thread, st, current, buf, buflen, &found_current);
5502 }
5503 st->cr();
5504
5505 st->print_cr("Other Threads:");
5506 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
5507 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
5508
5509 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
5510 Universe::heap()->gc_threads_do(&print_closure);
5511
5512 if (!found_current) {
5513 st->cr();
5514 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
5515 current->print_on_error(st, buf, buflen);
5516 st->cr();
5517 }
5518 st->cr();
5519
5520 st->print_cr("Threads with active compile tasks:");
5521 print_threads_compiling(st, buf, buflen);
5522 }
5523
5524 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
5525 ALL_JAVA_THREADS(thread) {
5526 if (thread->is_Compiler_thread()) {
5527 CompilerThread* ct = (CompilerThread*) thread;
5528 if (ct->task() != NULL) {
5529 thread->print_name_on_error(st, buf, buflen);
5530 ct->task()->print(st, NULL, true, true);
5531 }
5532 }
5533 }
5534 }
5535
5536
5537 // Internal SpinLock and Mutex
5538 // Based on ParkEvent
5539
5540 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
5541 //
5542 // We employ SpinLocks _only for low-contention, fixed-length
5543 // short-duration critical sections where we're concerned
5544 // about native mutex_t or HotSpot Mutex:: latency.
5545 // The mux construct provides a spin-then-block mutual exclusion
5546 // mechanism.
5547 //
5548 // Testing has shown that contention on the ListLock guarding gFreeList
5549 // is common. If we implement ListLock as a simple SpinLock it's common
5550 // for the JVM to devolve to yielding with little progress. This is true
5551 // despite the fact that the critical sections protected by ListLock are
5552 // extremely short.
5553 //
5554 // TODO-FIXME: ListLock should be of type SpinLock.
5555 // We should make this a 1st-class type, integrated into the lock
5556 // hierarchy as leaf-locks. Critically, the SpinLock structure
5557 // should have sufficient padding to avoid false-sharing and excessive
5558 // cache-coherency traffic.
5559
5560
5561 typedef volatile int SpinLockT;
5562
5563 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
5564 if (Atomic::cmpxchg (1, adr, 0) == 0) {
5565 return; // normal fast-path return
5566 }
5567
5568 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
5569 TEVENT(SpinAcquire - ctx);
5570 int ctr = 0;
5571 int Yields = 0;
5572 for (;;) {
5573 while (*adr != 0) {
5574 ++ctr;
5575 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
5576 if (Yields > 5) {
5577 os::naked_short_sleep(1);
5578 } else {
5579 os::naked_yield();
5580 ++Yields;
5581 }
5582 } else {
5583 SpinPause();
5584 }
5585 }
5586 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
5587 }
5588 }
5589
5590 void Thread::SpinRelease(volatile int * adr) {
5591 assert(*adr != 0, "invariant");
5592 OrderAccess::fence(); // guarantee at least release consistency.
5593 // Roach-motel semantics.
5594 // It's safe if subsequent LDs and STs float "up" into the critical section,
5595 // but prior LDs and STs within the critical section can't be allowed
5596 // to reorder or float past the ST that releases the lock.
5597 // Loads and stores in the critical section - which appear in program
5598 // order before the store that releases the lock - must also appear
5599 // before the store that releases the lock in memory visibility order.
5600 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
5601 // the ST of 0 into the lock-word which releases the lock, so fence
5602 // more than covers this on all platforms.
5603 *adr = 0;
5604 }
5605
5606 // muxAcquire and muxRelease:
5607 //
5608 // * muxAcquire and muxRelease support a single-word lock-word construct.
5609 // The LSB of the word is set IFF the lock is held.
5610 // The remainder of the word points to the head of a singly-linked list
5611 // of threads blocked on the lock.
5612 //
5613 // * The current implementation of muxAcquire-muxRelease uses its own
5614 // dedicated Thread._MuxEvent instance. If we're interested in
5615 // minimizing the peak number of extant ParkEvent instances then
5616 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5617 // as certain invariants were satisfied. Specifically, care would need
5618 // to be taken with regards to consuming unpark() "permits".
5619 // A safe rule of thumb is that a thread would never call muxAcquire()
5620 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5621 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5622 // consume an unpark() permit intended for monitorenter, for instance.
5623 // One way around this would be to widen the restricted-range semaphore
5624 // implemented in park(). Another alternative would be to provide
5625 // multiple instances of the PlatformEvent() for each thread. One
5626 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5627 //
5628 // * Usage:
5629 // -- Only as leaf locks
5630 // -- for short-term locking only as muxAcquire does not perform
5631 // thread state transitions.
5632 //
5633 // Alternatives:
5634 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5635 // but with parking or spin-then-park instead of pure spinning.
5636 // * Use Taura-Oyama-Yonenzawa locks.
5637 // * It's possible to construct a 1-0 lock if we encode the lockword as
5638 // (List,LockByte). Acquire will CAS the full lockword while Release
5639 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5640 // acquiring threads use timers (ParkTimed) to detect and recover from
5641 // the stranding window. Thread/Node structures must be aligned on 256-byte
5642 // boundaries by using placement-new.
5643 // * Augment MCS with advisory back-link fields maintained with CAS().
5644 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5645 // The validity of the backlinks must be ratified before we trust the value.
5646 // If the backlinks are invalid the exiting thread must back-track through the
5647 // the forward links, which are always trustworthy.
5648 // * Add a successor indication. The LockWord is currently encoded as
5649 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5650 // to provide the usual futile-wakeup optimization.
5651 // See RTStt for details.
5652 // * Consider schedctl.sc_nopreempt to cover the critical section.
5653 //
5654
5655
5656 const intptr_t LOCKBIT = 1;
5657
5658 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5659 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5660 if (w == 0) return;
5661 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5662 return;
5663 }
5664
5665 TEVENT(muxAcquire - Contention);
5666 ParkEvent * const Self = Thread::current()->_MuxEvent;
5667 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5668 for (;;) {
5669 int its = (os::is_MP() ? 100 : 0) + 1;
5670
5671 // Optional spin phase: spin-then-park strategy
5672 while (--its >= 0) {
5673 w = *Lock;
5674 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5675 return;
5676 }
5677 }
5678
5679 Self->reset();
5680 Self->OnList = intptr_t(Lock);
5681 // The following fence() isn't _strictly necessary as the subsequent
5682 // CAS() both serializes execution and ratifies the fetched *Lock value.
5683 OrderAccess::fence();
5684 for (;;) {
5685 w = *Lock;
5686 if ((w & LOCKBIT) == 0) {
5687 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5688 Self->OnList = 0; // hygiene - allows stronger asserts
5689 return;
5690 }
5691 continue; // Interference -- *Lock changed -- Just retry
5692 }
5693 assert(w & LOCKBIT, "invariant");
5694 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5695 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5696 }
5697
5698 while (Self->OnList != 0) {
5699 Self->park();
5700 }
5701 }
5702 }
5703
5704 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5705 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5706 if (w == 0) return;
5707 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5708 return;
5709 }
5710
5711 TEVENT(muxAcquire - Contention);
5712 ParkEvent * ReleaseAfter = NULL;
5713 if (ev == NULL) {
5714 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5715 }
5716 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5717 for (;;) {
5718 guarantee(ev->OnList == 0, "invariant");
5719 int its = (os::is_MP() ? 100 : 0) + 1;
5720
5721 // Optional spin phase: spin-then-park strategy
5722 while (--its >= 0) {
5723 w = *Lock;
5724 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5725 if (ReleaseAfter != NULL) {
5726 ParkEvent::Release(ReleaseAfter);
5727 }
5728 return;
5729 }
5730 }
5731
5732 ev->reset();
5733 ev->OnList = intptr_t(Lock);
5734 // The following fence() isn't _strictly necessary as the subsequent
5735 // CAS() both serializes execution and ratifies the fetched *Lock value.
5736 OrderAccess::fence();
5737 for (;;) {
5738 w = *Lock;
5739 if ((w & LOCKBIT) == 0) {
5740 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5741 ev->OnList = 0;
5742 // We call ::Release while holding the outer lock, thus
5743 // artificially lengthening the critical section.
5744 // Consider deferring the ::Release() until the subsequent unlock(),
5745 // after we've dropped the outer lock.
5746 if (ReleaseAfter != NULL) {
5747 ParkEvent::Release(ReleaseAfter);
5748 }
5749 return;
5750 }
5751 continue; // Interference -- *Lock changed -- Just retry
5752 }
5753 assert(w & LOCKBIT, "invariant");
5754 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5755 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5756 }
5757
5758 while (ev->OnList != 0) {
5759 ev->park();
5760 }
5761 }
5762 }
5763
5764 // Release() must extract a successor from the list and then wake that thread.
5765 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5766 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5767 // Release() would :
5768 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5769 // (B) Extract a successor from the private list "in-hand"
5770 // (C) attempt to CAS() the residual back into *Lock over null.
5771 // If there were any newly arrived threads and the CAS() would fail.
5772 // In that case Release() would detach the RATs, re-merge the list in-hand
5773 // with the RATs and repeat as needed. Alternately, Release() might
5774 // detach and extract a successor, but then pass the residual list to the wakee.
5775 // The wakee would be responsible for reattaching and remerging before it
5776 // competed for the lock.
5777 //
5778 // Both "pop" and DMR are immune from ABA corruption -- there can be
5779 // multiple concurrent pushers, but only one popper or detacher.
5780 // This implementation pops from the head of the list. This is unfair,
5781 // but tends to provide excellent throughput as hot threads remain hot.
5782 // (We wake recently run threads first).
5783 //
5784 // All paths through muxRelease() will execute a CAS.
5785 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5786 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5787 // executed within the critical section are complete and globally visible before the
5788 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5789 void Thread::muxRelease(volatile intptr_t * Lock) {
5790 for (;;) {
5791 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5792 assert(w & LOCKBIT, "invariant");
5793 if (w == LOCKBIT) return;
5794 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5795 assert(List != NULL, "invariant");
5796 assert(List->OnList == intptr_t(Lock), "invariant");
5797 ParkEvent * const nxt = List->ListNext;
5798 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5799
5800 // The following CAS() releases the lock and pops the head element.
5801 // The CAS() also ratifies the previously fetched lock-word value.
5802 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5803 continue;
5804 }
5805 List->OnList = 0;
5806 OrderAccess::fence();
5807 List->unpark();
5808 return;
5809 }
5810 }
5811
5812
5813 void Threads::verify() {
5814 ALL_JAVA_THREADS(p) {
5815 p->verify();
5816 }
5817 VMThread* thread = VMThread::vm_thread();
5818 if (thread != NULL) thread->verify();
5819 }