1 /*
2 * Copyright (c) 1997, 2016, 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 "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/codeCacheExtensions.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 "memory/metaspaceShared.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/universe.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/symbol.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "prims/jvm_misc.hpp"
54 #include "prims/jvmtiExport.hpp"
55 #include "prims/jvmtiThreadState.hpp"
56 #include "prims/privilegedStack.hpp"
57 #include "runtime/arguments.hpp"
58 #include "runtime/atomic.inline.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/commandLineFlagConstraintList.hpp"
61 #include "runtime/commandLineFlagRangeList.hpp"
62 #include "runtime/deoptimization.hpp"
63 #include "runtime/fprofiler.hpp"
64 #include "runtime/frame.inline.hpp"
65 #include "runtime/globals.hpp"
66 #include "runtime/init.hpp"
67 #include "runtime/interfaceSupport.hpp"
68 #include "runtime/java.hpp"
69 #include "runtime/javaCalls.hpp"
70 #include "runtime/jniPeriodicChecker.hpp"
71 #include "runtime/logTimer.hpp"
72 #include "runtime/memprofiler.hpp"
73 #include "runtime/mutexLocker.hpp"
74 #include "runtime/objectMonitor.hpp"
75 #include "runtime/orderAccess.inline.hpp"
76 #include "runtime/osThread.hpp"
77 #include "runtime/safepoint.hpp"
78 #include "runtime/sharedRuntime.hpp"
79 #include "runtime/statSampler.hpp"
80 #include "runtime/stubRoutines.hpp"
81 #include "runtime/sweeper.hpp"
82 #include "runtime/task.hpp"
83 #include "runtime/thread.inline.hpp"
84 #include "runtime/threadCritical.hpp"
85 #include "runtime/vframe.hpp"
86 #include "runtime/vframeArray.hpp"
87 #include "runtime/vframe_hp.hpp"
88 #include "runtime/vmThread.hpp"
89 #include "runtime/vm_operations.hpp"
90 #include "runtime/vm_version.hpp"
91 #include "services/attachListener.hpp"
92 #include "services/management.hpp"
93 #include "services/memTracker.hpp"
94 #include "services/threadService.hpp"
95 #include "trace/traceMacros.hpp"
96 #include "trace/tracing.hpp"
97 #include "utilities/defaultStream.hpp"
98 #include "utilities/dtrace.hpp"
99 #include "utilities/events.hpp"
100 #include "utilities/macros.hpp"
101 #include "utilities/preserveException.hpp"
102 #if INCLUDE_ALL_GCS
103 #include "gc/cms/concurrentMarkSweepThread.hpp"
104 #include "gc/g1/concurrentMarkThread.inline.hpp"
105 #include "gc/parallel/pcTasks.hpp"
106 #endif // INCLUDE_ALL_GCS
107 #if INCLUDE_JVMCI
108 #include "jvmci/jvmciCompiler.hpp"
109 #include "jvmci/jvmciRuntime.hpp"
110 #endif
111 #ifdef COMPILER1
112 #include "c1/c1_Compiler.hpp"
113 #endif
114 #ifdef COMPILER2
115 #include "opto/c2compiler.hpp"
116 #include "opto/idealGraphPrinter.hpp"
117 #endif
118 #if INCLUDE_RTM_OPT
119 #include "runtime/rtmLocking.hpp"
120 #endif
121
122 // Initialization after module runtime initialization
123 void universe_post_module_init(); // must happen after call_initPhase2
124
125 #ifdef DTRACE_ENABLED
126
127 // Only bother with this argument setup if dtrace is available
128
129 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
130 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
131
132 #define DTRACE_THREAD_PROBE(probe, javathread) \
133 { \
134 ResourceMark rm(this); \
135 int len = 0; \
136 const char* name = (javathread)->get_thread_name(); \
137 len = strlen(name); \
138 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
139 (char *) name, len, \
140 java_lang_Thread::thread_id((javathread)->threadObj()), \
141 (uintptr_t) (javathread)->osthread()->thread_id(), \
142 java_lang_Thread::is_daemon((javathread)->threadObj())); \
143 }
144
145 #else // ndef DTRACE_ENABLED
146
147 #define DTRACE_THREAD_PROBE(probe, javathread)
148
149 #endif // ndef DTRACE_ENABLED
150
151 #ifndef USE_LIBRARY_BASED_TLS_ONLY
152 // Current thread is maintained as a thread-local variable
153 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
154 #endif
155
156 // Class hierarchy
157 // - Thread
158 // - VMThread
159 // - WatcherThread
160 // - ConcurrentMarkSweepThread
161 // - JavaThread
162 // - CompilerThread
163
164 // ======= Thread ========
165 // Support for forcing alignment of thread objects for biased locking
166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
167 if (UseBiasedLocking) {
168 const int alignment = markOopDesc::biased_lock_alignment;
169 size_t aligned_size = size + (alignment - sizeof(intptr_t));
170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
171 : AllocateHeap(aligned_size, flags, CURRENT_PC,
172 AllocFailStrategy::RETURN_NULL);
173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
176 "JavaThread alignment code overflowed allocated storage");
177 if (aligned_addr != real_malloc_addr) {
178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
179 p2i(real_malloc_addr),
180 p2i(aligned_addr));
181 }
182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
183 return aligned_addr;
184 } else {
185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
187 }
188 }
189
190 void Thread::operator delete(void* p) {
191 if (UseBiasedLocking) {
192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
193 FreeHeap(real_malloc_addr);
194 } else {
195 FreeHeap(p);
196 }
197 }
198
199
200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
201 // JavaThread
202
203
204 Thread::Thread() {
205 // stack and get_thread
206 set_stack_base(NULL);
207 set_stack_size(0);
208 set_self_raw_id(0);
209 set_lgrp_id(-1);
210 DEBUG_ONLY(clear_suspendible_thread();)
211
212 // allocated data structures
213 set_osthread(NULL);
214 set_resource_area(new (mtThread)ResourceArea());
215 DEBUG_ONLY(_current_resource_mark = NULL;)
216 set_handle_area(new (mtThread) HandleArea(NULL));
217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
218 set_active_handles(NULL);
219 set_free_handle_block(NULL);
220 set_last_handle_mark(NULL);
221
222 // This initial value ==> never claimed.
223 _oops_do_parity = 0;
224
225 // the handle mark links itself to last_handle_mark
226 new HandleMark(this);
227
228 // plain initialization
229 debug_only(_owned_locks = NULL;)
230 debug_only(_allow_allocation_count = 0;)
231 NOT_PRODUCT(_allow_safepoint_count = 0;)
232 NOT_PRODUCT(_skip_gcalot = false;)
233 _jvmti_env_iteration_count = 0;
234 set_allocated_bytes(0);
235 _vm_operation_started_count = 0;
236 _vm_operation_completed_count = 0;
237 _current_pending_monitor = NULL;
238 _current_pending_monitor_is_from_java = true;
239 _current_waiting_monitor = NULL;
240 _num_nested_signal = 0;
241 omFreeList = NULL;
242 omFreeCount = 0;
243 omFreeProvision = 32;
244 omInUseList = NULL;
245 omInUseCount = 0;
246
247 #ifdef ASSERT
248 _visited_for_critical_count = false;
249 #endif
250
251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
252 Monitor::_safepoint_check_sometimes);
253 _suspend_flags = 0;
254
255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
256 _hashStateX = os::random();
257 _hashStateY = 842502087;
258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
259 _hashStateW = 273326509;
260
261 _OnTrap = 0;
262 _schedctl = NULL;
263 _Stalled = 0;
264 _TypeTag = 0x2BAD;
265
266 // Many of the following fields are effectively final - immutable
267 // Note that nascent threads can't use the Native Monitor-Mutex
268 // construct until the _MutexEvent is initialized ...
269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
270 // we might instead use a stack of ParkEvents that we could provision on-demand.
271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
272 // and ::Release()
273 _ParkEvent = ParkEvent::Allocate(this);
274 _SleepEvent = ParkEvent::Allocate(this);
275 _MutexEvent = ParkEvent::Allocate(this);
276 _MuxEvent = ParkEvent::Allocate(this);
277
278 #ifdef CHECK_UNHANDLED_OOPS
279 if (CheckUnhandledOops) {
280 _unhandled_oops = new UnhandledOops(this);
281 }
282 #endif // CHECK_UNHANDLED_OOPS
283 #ifdef ASSERT
284 if (UseBiasedLocking) {
285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
286 assert(this == _real_malloc_address ||
287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
288 "bug in forced alignment of thread objects");
289 }
290 #endif // ASSERT
291 }
292
293 void Thread::initialize_thread_current() {
294 #ifndef USE_LIBRARY_BASED_TLS_ONLY
295 assert(_thr_current == NULL, "Thread::current already initialized");
296 _thr_current = this;
297 #endif
298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
299 ThreadLocalStorage::set_thread(this);
300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
301 }
302
303 void Thread::clear_thread_current() {
304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
305 #ifndef USE_LIBRARY_BASED_TLS_ONLY
306 _thr_current = NULL;
307 #endif
308 ThreadLocalStorage::set_thread(NULL);
309 }
310
311 void Thread::record_stack_base_and_size() {
312 set_stack_base(os::current_stack_base());
313 set_stack_size(os::current_stack_size());
314 // CR 7190089: on Solaris, primordial thread's stack is adjusted
315 // in initialize_thread(). Without the adjustment, stack size is
316 // incorrect if stack is set to unlimited (ulimit -s unlimited).
317 // So far, only Solaris has real implementation of initialize_thread().
318 //
319 // set up any platform-specific state.
320 os::initialize_thread(this);
321
322 // Set stack limits after thread is initialized.
323 if (is_Java_thread()) {
324 ((JavaThread*) this)->set_stack_overflow_limit();
325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
326 }
327 #if INCLUDE_NMT
328 // record thread's native stack, stack grows downward
329 MemTracker::record_thread_stack(stack_end(), stack_size());
330 #endif // INCLUDE_NMT
331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
333 os::current_thread_id(), p2i(stack_base() - stack_size()),
334 p2i(stack_base()), stack_size()/1024);
335 }
336
337
338 Thread::~Thread() {
339 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
340 ObjectSynchronizer::omFlush(this);
341
342 EVENT_THREAD_DESTRUCT(this);
343
344 // stack_base can be NULL if the thread is never started or exited before
345 // record_stack_base_and_size called. Although, we would like to ensure
346 // that all started threads do call record_stack_base_and_size(), there is
347 // not proper way to enforce that.
348 #if INCLUDE_NMT
349 if (_stack_base != NULL) {
350 MemTracker::release_thread_stack(stack_end(), stack_size());
351 #ifdef ASSERT
352 set_stack_base(NULL);
353 #endif
354 }
355 #endif // INCLUDE_NMT
356
357 // deallocate data structures
358 delete resource_area();
359 // since the handle marks are using the handle area, we have to deallocated the root
360 // handle mark before deallocating the thread's handle area,
361 assert(last_handle_mark() != NULL, "check we have an element");
362 delete last_handle_mark();
363 assert(last_handle_mark() == NULL, "check we have reached the end");
364
365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
366 // We NULL out the fields for good hygiene.
367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
371
372 delete handle_area();
373 delete metadata_handles();
374
375 // osthread() can be NULL, if creation of thread failed.
376 if (osthread() != NULL) os::free_thread(osthread());
377
378 delete _SR_lock;
379
380 // clear Thread::current if thread is deleting itself.
381 // Needed to ensure JNI correctly detects non-attached threads.
382 if (this == Thread::current()) {
383 clear_thread_current();
384 }
385
386 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
387 }
388
389 // NOTE: dummy function for assertion purpose.
390 void Thread::run() {
391 ShouldNotReachHere();
392 }
393
394 #ifdef ASSERT
395 // Private method to check for dangling thread pointer
396 void check_for_dangling_thread_pointer(Thread *thread) {
397 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
398 "possibility of dangling Thread pointer");
399 }
400 #endif
401
402 ThreadPriority Thread::get_priority(const Thread* const thread) {
403 ThreadPriority priority;
404 // Can return an error!
405 (void)os::get_priority(thread, priority);
406 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
407 return priority;
408 }
409
410 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
411 debug_only(check_for_dangling_thread_pointer(thread);)
412 // Can return an error!
413 (void)os::set_priority(thread, priority);
414 }
415
416
417 void Thread::start(Thread* thread) {
418 // Start is different from resume in that its safety is guaranteed by context or
419 // being called from a Java method synchronized on the Thread object.
420 if (!DisableStartThread) {
421 if (thread->is_Java_thread()) {
422 // Initialize the thread state to RUNNABLE before starting this thread.
423 // Can not set it after the thread started because we do not know the
424 // exact thread state at that time. It could be in MONITOR_WAIT or
425 // in SLEEPING or some other state.
426 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
427 java_lang_Thread::RUNNABLE);
428 }
429 os::start_thread(thread);
430 }
431 }
432
433 // Enqueue a VM_Operation to do the job for us - sometime later
434 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
435 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
436 VMThread::execute(vm_stop);
437 }
438
439
440 // Check if an external suspend request has completed (or has been
441 // cancelled). Returns true if the thread is externally suspended and
442 // false otherwise.
443 //
444 // The bits parameter returns information about the code path through
445 // the routine. Useful for debugging:
446 //
447 // set in is_ext_suspend_completed():
448 // 0x00000001 - routine was entered
449 // 0x00000010 - routine return false at end
450 // 0x00000100 - thread exited (return false)
451 // 0x00000200 - suspend request cancelled (return false)
452 // 0x00000400 - thread suspended (return true)
453 // 0x00001000 - thread is in a suspend equivalent state (return true)
454 // 0x00002000 - thread is native and walkable (return true)
455 // 0x00004000 - thread is native_trans and walkable (needed retry)
456 //
457 // set in wait_for_ext_suspend_completion():
458 // 0x00010000 - routine was entered
459 // 0x00020000 - suspend request cancelled before loop (return false)
460 // 0x00040000 - thread suspended before loop (return true)
461 // 0x00080000 - suspend request cancelled in loop (return false)
462 // 0x00100000 - thread suspended in loop (return true)
463 // 0x00200000 - suspend not completed during retry loop (return false)
464
465 // Helper class for tracing suspend wait debug bits.
466 //
467 // 0x00000100 indicates that the target thread exited before it could
468 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
469 // 0x00080000 each indicate a cancelled suspend request so they don't
470 // count as wait failures either.
471 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
472
473 class TraceSuspendDebugBits : public StackObj {
474 private:
475 JavaThread * jt;
476 bool is_wait;
477 bool called_by_wait; // meaningful when !is_wait
478 uint32_t * bits;
479
480 public:
481 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
482 uint32_t *_bits) {
483 jt = _jt;
484 is_wait = _is_wait;
485 called_by_wait = _called_by_wait;
486 bits = _bits;
487 }
488
489 ~TraceSuspendDebugBits() {
490 if (!is_wait) {
491 #if 1
492 // By default, don't trace bits for is_ext_suspend_completed() calls.
493 // That trace is very chatty.
494 return;
495 #else
496 if (!called_by_wait) {
497 // If tracing for is_ext_suspend_completed() is enabled, then only
498 // trace calls to it from wait_for_ext_suspend_completion()
499 return;
500 }
501 #endif
502 }
503
504 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
505 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
506 MutexLocker ml(Threads_lock); // needed for get_thread_name()
507 ResourceMark rm;
508
509 tty->print_cr(
510 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
511 jt->get_thread_name(), *bits);
512
513 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
514 }
515 }
516 }
517 };
518 #undef DEBUG_FALSE_BITS
519
520
521 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
522 uint32_t *bits) {
523 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
524
525 bool did_trans_retry = false; // only do thread_in_native_trans retry once
526 bool do_trans_retry; // flag to force the retry
527
528 *bits |= 0x00000001;
529
530 do {
531 do_trans_retry = false;
532
533 if (is_exiting()) {
534 // Thread is in the process of exiting. This is always checked
535 // first to reduce the risk of dereferencing a freed JavaThread.
536 *bits |= 0x00000100;
537 return false;
538 }
539
540 if (!is_external_suspend()) {
541 // Suspend request is cancelled. This is always checked before
542 // is_ext_suspended() to reduce the risk of a rogue resume
543 // confusing the thread that made the suspend request.
544 *bits |= 0x00000200;
545 return false;
546 }
547
548 if (is_ext_suspended()) {
549 // thread is suspended
550 *bits |= 0x00000400;
551 return true;
552 }
553
554 // Now that we no longer do hard suspends of threads running
555 // native code, the target thread can be changing thread state
556 // while we are in this routine:
557 //
558 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
559 //
560 // We save a copy of the thread state as observed at this moment
561 // and make our decision about suspend completeness based on the
562 // copy. This closes the race where the thread state is seen as
563 // _thread_in_native_trans in the if-thread_blocked check, but is
564 // seen as _thread_blocked in if-thread_in_native_trans check.
565 JavaThreadState save_state = thread_state();
566
567 if (save_state == _thread_blocked && is_suspend_equivalent()) {
568 // If the thread's state is _thread_blocked and this blocking
569 // condition is known to be equivalent to a suspend, then we can
570 // consider the thread to be externally suspended. This means that
571 // the code that sets _thread_blocked has been modified to do
572 // self-suspension if the blocking condition releases. We also
573 // used to check for CONDVAR_WAIT here, but that is now covered by
574 // the _thread_blocked with self-suspension check.
575 //
576 // Return true since we wouldn't be here unless there was still an
577 // external suspend request.
578 *bits |= 0x00001000;
579 return true;
580 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
581 // Threads running native code will self-suspend on native==>VM/Java
582 // transitions. If its stack is walkable (should always be the case
583 // unless this function is called before the actual java_suspend()
584 // call), then the wait is done.
585 *bits |= 0x00002000;
586 return true;
587 } else if (!called_by_wait && !did_trans_retry &&
588 save_state == _thread_in_native_trans &&
589 frame_anchor()->walkable()) {
590 // The thread is transitioning from thread_in_native to another
591 // thread state. check_safepoint_and_suspend_for_native_trans()
592 // will force the thread to self-suspend. If it hasn't gotten
593 // there yet we may have caught the thread in-between the native
594 // code check above and the self-suspend. Lucky us. If we were
595 // called by wait_for_ext_suspend_completion(), then it
596 // will be doing the retries so we don't have to.
597 //
598 // Since we use the saved thread state in the if-statement above,
599 // there is a chance that the thread has already transitioned to
600 // _thread_blocked by the time we get here. In that case, we will
601 // make a single unnecessary pass through the logic below. This
602 // doesn't hurt anything since we still do the trans retry.
603
604 *bits |= 0x00004000;
605
606 // Once the thread leaves thread_in_native_trans for another
607 // thread state, we break out of this retry loop. We shouldn't
608 // need this flag to prevent us from getting back here, but
609 // sometimes paranoia is good.
610 did_trans_retry = true;
611
612 // We wait for the thread to transition to a more usable state.
613 for (int i = 1; i <= SuspendRetryCount; i++) {
614 // We used to do an "os::yield_all(i)" call here with the intention
615 // that yielding would increase on each retry. However, the parameter
616 // is ignored on Linux which means the yield didn't scale up. Waiting
617 // on the SR_lock below provides a much more predictable scale up for
618 // the delay. It also provides a simple/direct point to check for any
619 // safepoint requests from the VMThread
620
621 // temporarily drops SR_lock while doing wait with safepoint check
622 // (if we're a JavaThread - the WatcherThread can also call this)
623 // and increase delay with each retry
624 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
625
626 // check the actual thread state instead of what we saved above
627 if (thread_state() != _thread_in_native_trans) {
628 // the thread has transitioned to another thread state so
629 // try all the checks (except this one) one more time.
630 do_trans_retry = true;
631 break;
632 }
633 } // end retry loop
634
635
636 }
637 } while (do_trans_retry);
638
639 *bits |= 0x00000010;
640 return false;
641 }
642
643 // Wait for an external suspend request to complete (or be cancelled).
644 // Returns true if the thread is externally suspended and false otherwise.
645 //
646 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
647 uint32_t *bits) {
648 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
649 false /* !called_by_wait */, bits);
650
651 // local flag copies to minimize SR_lock hold time
652 bool is_suspended;
653 bool pending;
654 uint32_t reset_bits;
655
656 // set a marker so is_ext_suspend_completed() knows we are the caller
657 *bits |= 0x00010000;
658
659 // We use reset_bits to reinitialize the bits value at the top of
660 // each retry loop. This allows the caller to make use of any
661 // unused bits for their own marking purposes.
662 reset_bits = *bits;
663
664 {
665 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
666 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
667 delay, bits);
668 pending = is_external_suspend();
669 }
670 // must release SR_lock to allow suspension to complete
671
672 if (!pending) {
673 // A cancelled suspend request is the only false return from
674 // is_ext_suspend_completed() that keeps us from entering the
675 // retry loop.
676 *bits |= 0x00020000;
677 return false;
678 }
679
680 if (is_suspended) {
681 *bits |= 0x00040000;
682 return true;
683 }
684
685 for (int i = 1; i <= retries; i++) {
686 *bits = reset_bits; // reinit to only track last retry
687
688 // We used to do an "os::yield_all(i)" call here with the intention
689 // that yielding would increase on each retry. However, the parameter
690 // is ignored on Linux which means the yield didn't scale up. Waiting
691 // on the SR_lock below provides a much more predictable scale up for
692 // the delay. It also provides a simple/direct point to check for any
693 // safepoint requests from the VMThread
694
695 {
696 MutexLocker ml(SR_lock());
697 // wait with safepoint check (if we're a JavaThread - the WatcherThread
698 // can also call this) and increase delay with each retry
699 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
700
701 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
702 delay, bits);
703
704 // It is possible for the external suspend request to be cancelled
705 // (by a resume) before the actual suspend operation is completed.
706 // Refresh our local copy to see if we still need to wait.
707 pending = is_external_suspend();
708 }
709
710 if (!pending) {
711 // A cancelled suspend request is the only false return from
712 // is_ext_suspend_completed() that keeps us from staying in the
713 // retry loop.
714 *bits |= 0x00080000;
715 return false;
716 }
717
718 if (is_suspended) {
719 *bits |= 0x00100000;
720 return true;
721 }
722 } // end retry loop
723
724 // thread did not suspend after all our retries
725 *bits |= 0x00200000;
726 return false;
727 }
728
729 #ifndef PRODUCT
730 void JavaThread::record_jump(address target, address instr, const char* file,
731 int line) {
732
733 // This should not need to be atomic as the only way for simultaneous
734 // updates is via interrupts. Even then this should be rare or non-existent
735 // and we don't care that much anyway.
736
737 int index = _jmp_ring_index;
738 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
739 _jmp_ring[index]._target = (intptr_t) target;
740 _jmp_ring[index]._instruction = (intptr_t) instr;
741 _jmp_ring[index]._file = file;
742 _jmp_ring[index]._line = line;
743 }
744 #endif // PRODUCT
745
746 // Called by flat profiler
747 // Callers have already called wait_for_ext_suspend_completion
748 // The assertion for that is currently too complex to put here:
749 bool JavaThread::profile_last_Java_frame(frame* _fr) {
750 bool gotframe = false;
751 // self suspension saves needed state.
752 if (has_last_Java_frame() && _anchor.walkable()) {
753 *_fr = pd_last_frame();
754 gotframe = true;
755 }
756 return gotframe;
757 }
758
759 void Thread::interrupt(Thread* thread) {
760 debug_only(check_for_dangling_thread_pointer(thread);)
761 os::interrupt(thread);
762 }
763
764 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
765 debug_only(check_for_dangling_thread_pointer(thread);)
766 // Note: If clear_interrupted==false, this simply fetches and
767 // returns the value of the field osthread()->interrupted().
768 return os::is_interrupted(thread, clear_interrupted);
769 }
770
771
772 // GC Support
773 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
774 jint thread_parity = _oops_do_parity;
775 if (thread_parity != strong_roots_parity) {
776 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
777 if (res == thread_parity) {
778 return true;
779 } else {
780 guarantee(res == strong_roots_parity, "Or else what?");
781 return false;
782 }
783 }
784 return false;
785 }
786
787 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
788 active_handles()->oops_do(f);
789 // Do oop for ThreadShadow
790 f->do_oop((oop*)&_pending_exception);
791 handle_area()->oops_do(f);
792 }
793
794 void Thread::nmethods_do(CodeBlobClosure* cf) {
795 // no nmethods in a generic thread...
796 }
797
798 void Thread::metadata_handles_do(void f(Metadata*)) {
799 // Only walk the Handles in Thread.
800 if (metadata_handles() != NULL) {
801 for (int i = 0; i< metadata_handles()->length(); i++) {
802 f(metadata_handles()->at(i));
803 }
804 }
805 }
806
807 void Thread::print_on(outputStream* st) const {
808 // get_priority assumes osthread initialized
809 if (osthread() != NULL) {
810 int os_prio;
811 if (os::get_native_priority(this, &os_prio) == OS_OK) {
812 st->print("os_prio=%d ", os_prio);
813 }
814 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
815 ext().print_on(st);
816 osthread()->print_on(st);
817 }
818 debug_only(if (WizardMode) print_owned_locks_on(st);)
819 }
820
821 // Thread::print_on_error() is called by fatal error handler. Don't use
822 // any lock or allocate memory.
823 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
824 if (is_VM_thread()) st->print("VMThread");
825 else if (is_Compiler_thread()) st->print("CompilerThread");
826 else if (is_Java_thread()) st->print("JavaThread");
827 else if (is_GC_task_thread()) st->print("GCTaskThread");
828 else if (is_Watcher_thread()) st->print("WatcherThread");
829 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
830 else st->print("Thread");
831
832 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
833 p2i(stack_end()), p2i(stack_base()));
834
835 if (osthread()) {
836 st->print(" [id=%d]", osthread()->thread_id());
837 }
838 }
839
840 #ifdef ASSERT
841 void Thread::print_owned_locks_on(outputStream* st) const {
842 Monitor *cur = _owned_locks;
843 if (cur == NULL) {
844 st->print(" (no locks) ");
845 } else {
846 st->print_cr(" Locks owned:");
847 while (cur) {
848 cur->print_on(st);
849 cur = cur->next();
850 }
851 }
852 }
853
854 static int ref_use_count = 0;
855
856 bool Thread::owns_locks_but_compiled_lock() const {
857 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
858 if (cur != Compile_lock) return true;
859 }
860 return false;
861 }
862
863
864 #endif
865
866 #ifndef PRODUCT
867
868 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
869 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
870 // no threads which allow_vm_block's are held
871 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
872 // Check if current thread is allowed to block at a safepoint
873 if (!(_allow_safepoint_count == 0)) {
874 fatal("Possible safepoint reached by thread that does not allow it");
875 }
876 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
877 fatal("LEAF method calling lock?");
878 }
879
880 #ifdef ASSERT
881 if (potential_vm_operation && is_Java_thread()
882 && !Universe::is_bootstrapping()) {
883 // Make sure we do not hold any locks that the VM thread also uses.
884 // This could potentially lead to deadlocks
885 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
886 // Threads_lock is special, since the safepoint synchronization will not start before this is
887 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
888 // since it is used to transfer control between JavaThreads and the VMThread
889 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
890 if ((cur->allow_vm_block() &&
891 cur != Threads_lock &&
892 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
893 cur != VMOperationRequest_lock &&
894 cur != VMOperationQueue_lock) ||
895 cur->rank() == Mutex::special) {
896 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
897 }
898 }
899 }
900
901 if (GCALotAtAllSafepoints) {
902 // We could enter a safepoint here and thus have a gc
903 InterfaceSupport::check_gc_alot();
904 }
905 #endif
906 }
907 #endif
908
909 bool Thread::is_in_stack(address adr) const {
910 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
911 address end = os::current_stack_pointer();
912 // Allow non Java threads to call this without stack_base
913 if (_stack_base == NULL) return true;
914 if (stack_base() >= adr && adr >= end) return true;
915
916 return false;
917 }
918
919 bool Thread::is_in_usable_stack(address adr) const {
920 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
921 size_t usable_stack_size = _stack_size - stack_guard_size;
922
923 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
924 }
925
926
927 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
928 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
929 // used for compilation in the future. If that change is made, the need for these methods
930 // should be revisited, and they should be removed if possible.
931
932 bool Thread::is_lock_owned(address adr) const {
933 return on_local_stack(adr);
934 }
935
936 bool Thread::set_as_starting_thread() {
937 // NOTE: this must be called inside the main thread.
938 return os::create_main_thread((JavaThread*)this);
939 }
940
941 static void initialize_class(Symbol* class_name, TRAPS) {
942 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
943 InstanceKlass::cast(klass)->initialize(CHECK);
944 }
945
946
947 // Creates the initial ThreadGroup
948 static Handle create_initial_thread_group(TRAPS) {
949 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
950 instanceKlassHandle klass (THREAD, k);
951
952 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
953 {
954 JavaValue result(T_VOID);
955 JavaCalls::call_special(&result,
956 system_instance,
957 klass,
958 vmSymbols::object_initializer_name(),
959 vmSymbols::void_method_signature(),
960 CHECK_NH);
961 }
962 Universe::set_system_thread_group(system_instance());
963
964 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
965 {
966 JavaValue result(T_VOID);
967 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
968 JavaCalls::call_special(&result,
969 main_instance,
970 klass,
971 vmSymbols::object_initializer_name(),
972 vmSymbols::threadgroup_string_void_signature(),
973 system_instance,
974 string,
975 CHECK_NH);
976 }
977 return main_instance;
978 }
979
980 // Creates the initial Thread
981 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
982 TRAPS) {
983 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
984 instanceKlassHandle klass (THREAD, k);
985 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
986
987 java_lang_Thread::set_thread(thread_oop(), thread);
988 java_lang_Thread::set_priority(thread_oop(), NormPriority);
989 thread->set_threadObj(thread_oop());
990
991 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
992
993 JavaValue result(T_VOID);
994 JavaCalls::call_special(&result, thread_oop,
995 klass,
996 vmSymbols::object_initializer_name(),
997 vmSymbols::threadgroup_string_void_signature(),
998 thread_group,
999 string,
1000 CHECK_NULL);
1001 return thread_oop();
1002 }
1003
1004 char java_runtime_name[128] = "";
1005 char java_runtime_version[128] = "";
1006
1007 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1008 static const char* get_java_runtime_name(TRAPS) {
1009 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1010 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1011 fieldDescriptor fd;
1012 bool found = k != NULL &&
1013 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1014 vmSymbols::string_signature(), &fd);
1015 if (found) {
1016 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1017 if (name_oop == NULL) {
1018 return NULL;
1019 }
1020 const char* name = java_lang_String::as_utf8_string(name_oop,
1021 java_runtime_name,
1022 sizeof(java_runtime_name));
1023 return name;
1024 } else {
1025 return NULL;
1026 }
1027 }
1028
1029 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1030 static const char* get_java_runtime_version(TRAPS) {
1031 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1032 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1033 fieldDescriptor fd;
1034 bool found = k != NULL &&
1035 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1036 vmSymbols::string_signature(), &fd);
1037 if (found) {
1038 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1039 if (name_oop == NULL) {
1040 return NULL;
1041 }
1042 const char* name = java_lang_String::as_utf8_string(name_oop,
1043 java_runtime_version,
1044 sizeof(java_runtime_version));
1045 return name;
1046 } else {
1047 return NULL;
1048 }
1049 }
1050
1051 // General purpose hook into Java code, run once when the VM is initialized.
1052 // The Java library method itself may be changed independently from the VM.
1053 static void call_postVMInitHook(TRAPS) {
1054 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1055 instanceKlassHandle klass (THREAD, k);
1056 if (klass.not_null()) {
1057 JavaValue result(T_VOID);
1058 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1059 vmSymbols::void_method_signature(),
1060 CHECK);
1061 }
1062 }
1063
1064 static void reset_vm_info_property(TRAPS) {
1065 // the vm info string
1066 ResourceMark rm(THREAD);
1067 const char *vm_info = VM_Version::vm_info_string();
1068
1069 // java.lang.System class
1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1071 instanceKlassHandle klass (THREAD, k);
1072
1073 // setProperty arguments
1074 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1075 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1076
1077 // return value
1078 JavaValue r(T_OBJECT);
1079
1080 // public static String setProperty(String key, String value);
1081 JavaCalls::call_static(&r,
1082 klass,
1083 vmSymbols::setProperty_name(),
1084 vmSymbols::string_string_string_signature(),
1085 key_str,
1086 value_str,
1087 CHECK);
1088 }
1089
1090
1091 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1092 bool daemon, TRAPS) {
1093 assert(thread_group.not_null(), "thread group should be specified");
1094 assert(threadObj() == NULL, "should only create Java thread object once");
1095
1096 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1097 instanceKlassHandle klass (THREAD, k);
1098 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1099
1100 java_lang_Thread::set_thread(thread_oop(), this);
1101 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1102 set_threadObj(thread_oop());
1103
1104 JavaValue result(T_VOID);
1105 if (thread_name != NULL) {
1106 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1107 // Thread gets assigned specified name and null target
1108 JavaCalls::call_special(&result,
1109 thread_oop,
1110 klass,
1111 vmSymbols::object_initializer_name(),
1112 vmSymbols::threadgroup_string_void_signature(),
1113 thread_group, // Argument 1
1114 name, // Argument 2
1115 THREAD);
1116 } else {
1117 // Thread gets assigned name "Thread-nnn" and null target
1118 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1119 JavaCalls::call_special(&result,
1120 thread_oop,
1121 klass,
1122 vmSymbols::object_initializer_name(),
1123 vmSymbols::threadgroup_runnable_void_signature(),
1124 thread_group, // Argument 1
1125 Handle(), // Argument 2
1126 THREAD);
1127 }
1128
1129
1130 if (daemon) {
1131 java_lang_Thread::set_daemon(thread_oop());
1132 }
1133
1134 if (HAS_PENDING_EXCEPTION) {
1135 return;
1136 }
1137
1138 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1139 Handle threadObj(THREAD, this->threadObj());
1140
1141 JavaCalls::call_special(&result,
1142 thread_group,
1143 group,
1144 vmSymbols::add_method_name(),
1145 vmSymbols::thread_void_signature(),
1146 threadObj, // Arg 1
1147 THREAD);
1148 }
1149
1150 // NamedThread -- non-JavaThread subclasses with multiple
1151 // uniquely named instances should derive from this.
1152 NamedThread::NamedThread() : Thread() {
1153 _name = NULL;
1154 _processed_thread = NULL;
1155 _gc_id = GCId::undefined();
1156 }
1157
1158 NamedThread::~NamedThread() {
1159 if (_name != NULL) {
1160 FREE_C_HEAP_ARRAY(char, _name);
1161 _name = NULL;
1162 }
1163 }
1164
1165 void NamedThread::set_name(const char* format, ...) {
1166 guarantee(_name == NULL, "Only get to set name once.");
1167 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1168 guarantee(_name != NULL, "alloc failure");
1169 va_list ap;
1170 va_start(ap, format);
1171 jio_vsnprintf(_name, max_name_len, format, ap);
1172 va_end(ap);
1173 }
1174
1175 void NamedThread::initialize_named_thread() {
1176 set_native_thread_name(name());
1177 }
1178
1179 void NamedThread::print_on(outputStream* st) const {
1180 st->print("\"%s\" ", name());
1181 Thread::print_on(st);
1182 st->cr();
1183 }
1184
1185
1186 // ======= WatcherThread ========
1187
1188 // The watcher thread exists to simulate timer interrupts. It should
1189 // be replaced by an abstraction over whatever native support for
1190 // timer interrupts exists on the platform.
1191
1192 WatcherThread* WatcherThread::_watcher_thread = NULL;
1193 bool WatcherThread::_startable = false;
1194 volatile bool WatcherThread::_should_terminate = false;
1195
1196 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1197 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1198 if (os::create_thread(this, os::watcher_thread)) {
1199 _watcher_thread = this;
1200
1201 // Set the watcher thread to the highest OS priority which should not be
1202 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1203 // is created. The only normal thread using this priority is the reference
1204 // handler thread, which runs for very short intervals only.
1205 // If the VMThread's priority is not lower than the WatcherThread profiling
1206 // will be inaccurate.
1207 os::set_priority(this, MaxPriority);
1208 if (!DisableStartThread) {
1209 os::start_thread(this);
1210 }
1211 }
1212 }
1213
1214 int WatcherThread::sleep() const {
1215 // The WatcherThread does not participate in the safepoint protocol
1216 // for the PeriodicTask_lock because it is not a JavaThread.
1217 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1218
1219 if (_should_terminate) {
1220 // check for termination before we do any housekeeping or wait
1221 return 0; // we did not sleep.
1222 }
1223
1224 // remaining will be zero if there are no tasks,
1225 // causing the WatcherThread to sleep until a task is
1226 // enrolled
1227 int remaining = PeriodicTask::time_to_wait();
1228 int time_slept = 0;
1229
1230 // we expect this to timeout - we only ever get unparked when
1231 // we should terminate or when a new task has been enrolled
1232 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1233
1234 jlong time_before_loop = os::javaTimeNanos();
1235
1236 while (true) {
1237 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1238 remaining);
1239 jlong now = os::javaTimeNanos();
1240
1241 if (remaining == 0) {
1242 // if we didn't have any tasks we could have waited for a long time
1243 // consider the time_slept zero and reset time_before_loop
1244 time_slept = 0;
1245 time_before_loop = now;
1246 } else {
1247 // need to recalculate since we might have new tasks in _tasks
1248 time_slept = (int) ((now - time_before_loop) / 1000000);
1249 }
1250
1251 // Change to task list or spurious wakeup of some kind
1252 if (timedout || _should_terminate) {
1253 break;
1254 }
1255
1256 remaining = PeriodicTask::time_to_wait();
1257 if (remaining == 0) {
1258 // Last task was just disenrolled so loop around and wait until
1259 // another task gets enrolled
1260 continue;
1261 }
1262
1263 remaining -= time_slept;
1264 if (remaining <= 0) {
1265 break;
1266 }
1267 }
1268
1269 return time_slept;
1270 }
1271
1272 void WatcherThread::run() {
1273 assert(this == watcher_thread(), "just checking");
1274
1275 this->record_stack_base_and_size();
1276 this->set_native_thread_name(this->name());
1277 this->set_active_handles(JNIHandleBlock::allocate_block());
1278 while (true) {
1279 assert(watcher_thread() == Thread::current(), "thread consistency check");
1280 assert(watcher_thread() == this, "thread consistency check");
1281
1282 // Calculate how long it'll be until the next PeriodicTask work
1283 // should be done, and sleep that amount of time.
1284 int time_waited = sleep();
1285
1286 if (is_error_reported()) {
1287 // A fatal error has happened, the error handler(VMError::report_and_die)
1288 // should abort JVM after creating an error log file. However in some
1289 // rare cases, the error handler itself might deadlock. Here we try to
1290 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1291 //
1292 // This code is in WatcherThread because WatcherThread wakes up
1293 // periodically so the fatal error handler doesn't need to do anything;
1294 // also because the WatcherThread is less likely to crash than other
1295 // threads.
1296
1297 for (;;) {
1298 if (!ShowMessageBoxOnError
1299 && (OnError == NULL || OnError[0] == '\0')
1300 && Arguments::abort_hook() == NULL) {
1301 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1302 fdStream err(defaultStream::output_fd());
1303 err.print_raw_cr("# [ timer expired, abort... ]");
1304 // skip atexit/vm_exit/vm_abort hooks
1305 os::die();
1306 }
1307
1308 // Wake up 5 seconds later, the fatal handler may reset OnError or
1309 // ShowMessageBoxOnError when it is ready to abort.
1310 os::sleep(this, 5 * 1000, false);
1311 }
1312 }
1313
1314 if (_should_terminate) {
1315 // check for termination before posting the next tick
1316 break;
1317 }
1318
1319 PeriodicTask::real_time_tick(time_waited);
1320 }
1321
1322 // Signal that it is terminated
1323 {
1324 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1325 _watcher_thread = NULL;
1326 Terminator_lock->notify();
1327 }
1328 }
1329
1330 void WatcherThread::start() {
1331 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1332
1333 if (watcher_thread() == NULL && _startable) {
1334 _should_terminate = false;
1335 // Create the single instance of WatcherThread
1336 new WatcherThread();
1337 }
1338 }
1339
1340 void WatcherThread::make_startable() {
1341 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1342 _startable = true;
1343 }
1344
1345 void WatcherThread::stop() {
1346 {
1347 // Follow normal safepoint aware lock enter protocol since the
1348 // WatcherThread is stopped by another JavaThread.
1349 MutexLocker ml(PeriodicTask_lock);
1350 _should_terminate = true;
1351
1352 WatcherThread* watcher = watcher_thread();
1353 if (watcher != NULL) {
1354 // unpark the WatcherThread so it can see that it should terminate
1355 watcher->unpark();
1356 }
1357 }
1358
1359 MutexLocker mu(Terminator_lock);
1360
1361 while (watcher_thread() != NULL) {
1362 // This wait should make safepoint checks, wait without a timeout,
1363 // and wait as a suspend-equivalent condition.
1364 //
1365 // Note: If the FlatProfiler is running, then this thread is waiting
1366 // for the WatcherThread to terminate and the WatcherThread, via the
1367 // FlatProfiler task, is waiting for the external suspend request on
1368 // this thread to complete. wait_for_ext_suspend_completion() will
1369 // eventually timeout, but that takes time. Making this wait a
1370 // suspend-equivalent condition solves that timeout problem.
1371 //
1372 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1373 Mutex::_as_suspend_equivalent_flag);
1374 }
1375 }
1376
1377 void WatcherThread::unpark() {
1378 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1379 PeriodicTask_lock->notify();
1380 }
1381
1382 void WatcherThread::print_on(outputStream* st) const {
1383 st->print("\"%s\" ", name());
1384 Thread::print_on(st);
1385 st->cr();
1386 }
1387
1388 // ======= JavaThread ========
1389
1390 #if INCLUDE_JVMCI
1391
1392 jlong* JavaThread::_jvmci_old_thread_counters;
1393
1394 bool jvmci_counters_include(JavaThread* thread) {
1395 oop threadObj = thread->threadObj();
1396 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1397 }
1398
1399 void JavaThread::collect_counters(typeArrayOop array) {
1400 if (JVMCICounterSize > 0) {
1401 MutexLocker tl(Threads_lock);
1402 for (int i = 0; i < array->length(); i++) {
1403 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1404 }
1405 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1406 if (jvmci_counters_include(tp)) {
1407 for (int i = 0; i < array->length(); i++) {
1408 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1409 }
1410 }
1411 }
1412 }
1413 }
1414
1415 #endif // INCLUDE_JVMCI
1416
1417 // A JavaThread is a normal Java thread
1418
1419 void JavaThread::initialize() {
1420 // Initialize fields
1421
1422 set_saved_exception_pc(NULL);
1423 set_threadObj(NULL);
1424 _anchor.clear();
1425 set_entry_point(NULL);
1426 set_jni_functions(jni_functions());
1427 set_callee_target(NULL);
1428 set_vm_result(NULL);
1429 set_vm_result_2(NULL);
1430 set_vframe_array_head(NULL);
1431 set_vframe_array_last(NULL);
1432 set_deferred_locals(NULL);
1433 set_deopt_mark(NULL);
1434 set_deopt_nmethod(NULL);
1435 clear_must_deopt_id();
1436 set_monitor_chunks(NULL);
1437 set_next(NULL);
1438 set_thread_state(_thread_new);
1439 _terminated = _not_terminated;
1440 _privileged_stack_top = NULL;
1441 _array_for_gc = NULL;
1442 _suspend_equivalent = false;
1443 _in_deopt_handler = 0;
1444 _doing_unsafe_access = false;
1445 _stack_guard_state = stack_guard_unused;
1446 #if INCLUDE_JVMCI
1447 _pending_monitorenter = false;
1448 _pending_deoptimization = -1;
1449 _pending_failed_speculation = NULL;
1450 _pending_transfer_to_interpreter = false;
1451 _jvmci._alternate_call_target = NULL;
1452 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1453 if (JVMCICounterSize > 0) {
1454 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1455 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1456 } else {
1457 _jvmci_counters = NULL;
1458 }
1459 #endif // INCLUDE_JVMCI
1460 _reserved_stack_activation = NULL; // stack base not known yet
1461 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1462 _exception_pc = 0;
1463 _exception_handler_pc = 0;
1464 _is_method_handle_return = 0;
1465 _jvmti_thread_state= NULL;
1466 _should_post_on_exceptions_flag = JNI_FALSE;
1467 _jvmti_get_loaded_classes_closure = NULL;
1468 _interp_only_mode = 0;
1469 _special_runtime_exit_condition = _no_async_condition;
1470 _pending_async_exception = NULL;
1471 _thread_stat = NULL;
1472 _thread_stat = new ThreadStatistics();
1473 _blocked_on_compilation = false;
1474 _jni_active_critical = 0;
1475 _pending_jni_exception_check_fn = NULL;
1476 _do_not_unlock_if_synchronized = false;
1477 _cached_monitor_info = NULL;
1478 _parker = Parker::Allocate(this);
1479
1480 #ifndef PRODUCT
1481 _jmp_ring_index = 0;
1482 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1483 record_jump(NULL, NULL, NULL, 0);
1484 }
1485 #endif // PRODUCT
1486
1487 set_thread_profiler(NULL);
1488 if (FlatProfiler::is_active()) {
1489 // This is where we would decide to either give each thread it's own profiler
1490 // or use one global one from FlatProfiler,
1491 // or up to some count of the number of profiled threads, etc.
1492 ThreadProfiler* pp = new ThreadProfiler();
1493 pp->engage();
1494 set_thread_profiler(pp);
1495 }
1496
1497 // Setup safepoint state info for this thread
1498 ThreadSafepointState::create(this);
1499
1500 debug_only(_java_call_counter = 0);
1501
1502 // JVMTI PopFrame support
1503 _popframe_condition = popframe_inactive;
1504 _popframe_preserved_args = NULL;
1505 _popframe_preserved_args_size = 0;
1506 _frames_to_pop_failed_realloc = 0;
1507
1508 pd_initialize();
1509 }
1510
1511 #if INCLUDE_ALL_GCS
1512 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1513 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1514 #endif // INCLUDE_ALL_GCS
1515
1516 JavaThread::JavaThread(bool is_attaching_via_jni) :
1517 Thread()
1518 #if INCLUDE_ALL_GCS
1519 , _satb_mark_queue(&_satb_mark_queue_set),
1520 _dirty_card_queue(&_dirty_card_queue_set)
1521 #endif // INCLUDE_ALL_GCS
1522 {
1523 initialize();
1524 if (is_attaching_via_jni) {
1525 _jni_attach_state = _attaching_via_jni;
1526 } else {
1527 _jni_attach_state = _not_attaching_via_jni;
1528 }
1529 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1530 }
1531
1532 bool JavaThread::reguard_stack(address cur_sp) {
1533 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1534 && _stack_guard_state != stack_guard_reserved_disabled) {
1535 return true; // Stack already guarded or guard pages not needed.
1536 }
1537
1538 if (register_stack_overflow()) {
1539 // For those architectures which have separate register and
1540 // memory stacks, we must check the register stack to see if
1541 // it has overflowed.
1542 return false;
1543 }
1544
1545 // Java code never executes within the yellow zone: the latter is only
1546 // there to provoke an exception during stack banging. If java code
1547 // is executing there, either StackShadowPages should be larger, or
1548 // some exception code in c1, c2 or the interpreter isn't unwinding
1549 // when it should.
1550 guarantee(cur_sp > stack_reserved_zone_base(),
1551 "not enough space to reguard - increase StackShadowPages");
1552 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1553 enable_stack_yellow_reserved_zone();
1554 if (reserved_stack_activation() != stack_base()) {
1555 set_reserved_stack_activation(stack_base());
1556 }
1557 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1558 set_reserved_stack_activation(stack_base());
1559 enable_stack_reserved_zone();
1560 }
1561 return true;
1562 }
1563
1564 bool JavaThread::reguard_stack(void) {
1565 return reguard_stack(os::current_stack_pointer());
1566 }
1567
1568
1569 void JavaThread::block_if_vm_exited() {
1570 if (_terminated == _vm_exited) {
1571 // _vm_exited is set at safepoint, and Threads_lock is never released
1572 // we will block here forever
1573 Threads_lock->lock_without_safepoint_check();
1574 ShouldNotReachHere();
1575 }
1576 }
1577
1578
1579 // Remove this ifdef when C1 is ported to the compiler interface.
1580 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1581 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1582
1583 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1584 Thread()
1585 #if INCLUDE_ALL_GCS
1586 , _satb_mark_queue(&_satb_mark_queue_set),
1587 _dirty_card_queue(&_dirty_card_queue_set)
1588 #endif // INCLUDE_ALL_GCS
1589 {
1590 initialize();
1591 _jni_attach_state = _not_attaching_via_jni;
1592 set_entry_point(entry_point);
1593 // Create the native thread itself.
1594 // %note runtime_23
1595 os::ThreadType thr_type = os::java_thread;
1596 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1597 os::java_thread;
1598 os::create_thread(this, thr_type, stack_sz);
1599 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1600 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1601 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1602 // the exception consists of creating the exception object & initializing it, initialization
1603 // will leave the VM via a JavaCall and then all locks must be unlocked).
1604 //
1605 // The thread is still suspended when we reach here. Thread must be explicit started
1606 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1607 // by calling Threads:add. The reason why this is not done here, is because the thread
1608 // object must be fully initialized (take a look at JVM_Start)
1609 }
1610
1611 JavaThread::~JavaThread() {
1612
1613 // JSR166 -- return the parker to the free list
1614 Parker::Release(_parker);
1615 _parker = NULL;
1616
1617 // Free any remaining previous UnrollBlock
1618 vframeArray* old_array = vframe_array_last();
1619
1620 if (old_array != NULL) {
1621 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1622 old_array->set_unroll_block(NULL);
1623 delete old_info;
1624 delete old_array;
1625 }
1626
1627 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1628 if (deferred != NULL) {
1629 // This can only happen if thread is destroyed before deoptimization occurs.
1630 assert(deferred->length() != 0, "empty array!");
1631 do {
1632 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1633 deferred->remove_at(0);
1634 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1635 delete dlv;
1636 } while (deferred->length() != 0);
1637 delete deferred;
1638 }
1639
1640 // All Java related clean up happens in exit
1641 ThreadSafepointState::destroy(this);
1642 if (_thread_profiler != NULL) delete _thread_profiler;
1643 if (_thread_stat != NULL) delete _thread_stat;
1644
1645 #if INCLUDE_JVMCI
1646 if (JVMCICounterSize > 0) {
1647 if (jvmci_counters_include(this)) {
1648 for (int i = 0; i < JVMCICounterSize; i++) {
1649 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1650 }
1651 }
1652 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1653 }
1654 #endif // INCLUDE_JVMCI
1655 }
1656
1657
1658 // The first routine called by a new Java thread
1659 void JavaThread::run() {
1660 // initialize thread-local alloc buffer related fields
1661 this->initialize_tlab();
1662
1663 // used to test validity of stack trace backs
1664 this->record_base_of_stack_pointer();
1665
1666 // Record real stack base and size.
1667 this->record_stack_base_and_size();
1668
1669 this->create_stack_guard_pages();
1670
1671 this->cache_global_variables();
1672
1673 // Thread is now sufficient initialized to be handled by the safepoint code as being
1674 // in the VM. Change thread state from _thread_new to _thread_in_vm
1675 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1676
1677 assert(JavaThread::current() == this, "sanity check");
1678 assert(!Thread::current()->owns_locks(), "sanity check");
1679
1680 DTRACE_THREAD_PROBE(start, this);
1681
1682 // This operation might block. We call that after all safepoint checks for a new thread has
1683 // been completed.
1684 this->set_active_handles(JNIHandleBlock::allocate_block());
1685
1686 if (JvmtiExport::should_post_thread_life()) {
1687 JvmtiExport::post_thread_start(this);
1688 }
1689
1690 EventThreadStart event;
1691 if (event.should_commit()) {
1692 event.set_thread(THREAD_TRACE_ID(this));
1693 event.commit();
1694 }
1695
1696 // We call another function to do the rest so we are sure that the stack addresses used
1697 // from there will be lower than the stack base just computed
1698 thread_main_inner();
1699
1700 // Note, thread is no longer valid at this point!
1701 }
1702
1703
1704 void JavaThread::thread_main_inner() {
1705 assert(JavaThread::current() == this, "sanity check");
1706 assert(this->threadObj() != NULL, "just checking");
1707
1708 // Execute thread entry point unless this thread has a pending exception
1709 // or has been stopped before starting.
1710 // Note: Due to JVM_StopThread we can have pending exceptions already!
1711 if (!this->has_pending_exception() &&
1712 !java_lang_Thread::is_stillborn(this->threadObj())) {
1713 {
1714 ResourceMark rm(this);
1715 this->set_native_thread_name(this->get_thread_name());
1716 }
1717 HandleMark hm(this);
1718 this->entry_point()(this, this);
1719 }
1720
1721 DTRACE_THREAD_PROBE(stop, this);
1722
1723 this->exit(false);
1724 delete this;
1725 }
1726
1727
1728 static void ensure_join(JavaThread* thread) {
1729 // We do not need to grap the Threads_lock, since we are operating on ourself.
1730 Handle threadObj(thread, thread->threadObj());
1731 assert(threadObj.not_null(), "java thread object must exist");
1732 ObjectLocker lock(threadObj, thread);
1733 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1734 thread->clear_pending_exception();
1735 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1736 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1737 // Clear the native thread instance - this makes isAlive return false and allows the join()
1738 // to complete once we've done the notify_all below
1739 java_lang_Thread::set_thread(threadObj(), NULL);
1740 lock.notify_all(thread);
1741 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1742 thread->clear_pending_exception();
1743 }
1744
1745
1746 // For any new cleanup additions, please check to see if they need to be applied to
1747 // cleanup_failed_attach_current_thread as well.
1748 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1749 assert(this == JavaThread::current(), "thread consistency check");
1750
1751 HandleMark hm(this);
1752 Handle uncaught_exception(this, this->pending_exception());
1753 this->clear_pending_exception();
1754 Handle threadObj(this, this->threadObj());
1755 assert(threadObj.not_null(), "Java thread object should be created");
1756
1757 if (get_thread_profiler() != NULL) {
1758 get_thread_profiler()->disengage();
1759 ResourceMark rm;
1760 get_thread_profiler()->print(get_thread_name());
1761 }
1762
1763
1764 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1765 {
1766 EXCEPTION_MARK;
1767
1768 CLEAR_PENDING_EXCEPTION;
1769 }
1770 if (!destroy_vm) {
1771 if (uncaught_exception.not_null()) {
1772 EXCEPTION_MARK;
1773 // Call method Thread.dispatchUncaughtException().
1774 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1775 JavaValue result(T_VOID);
1776 JavaCalls::call_virtual(&result,
1777 threadObj, thread_klass,
1778 vmSymbols::dispatchUncaughtException_name(),
1779 vmSymbols::throwable_void_signature(),
1780 uncaught_exception,
1781 THREAD);
1782 if (HAS_PENDING_EXCEPTION) {
1783 ResourceMark rm(this);
1784 jio_fprintf(defaultStream::error_stream(),
1785 "\nException: %s thrown from the UncaughtExceptionHandler"
1786 " in thread \"%s\"\n",
1787 pending_exception()->klass()->external_name(),
1788 get_thread_name());
1789 CLEAR_PENDING_EXCEPTION;
1790 }
1791 }
1792
1793 // Called before the java thread exit since we want to read info
1794 // from java_lang_Thread object
1795 EventThreadEnd event;
1796 if (event.should_commit()) {
1797 event.set_thread(THREAD_TRACE_ID(this));
1798 event.commit();
1799 }
1800
1801 // Call after last event on thread
1802 EVENT_THREAD_EXIT(this);
1803
1804 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1805 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1806 // is deprecated anyhow.
1807 if (!is_Compiler_thread()) {
1808 int count = 3;
1809 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1810 EXCEPTION_MARK;
1811 JavaValue result(T_VOID);
1812 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1813 JavaCalls::call_virtual(&result,
1814 threadObj, thread_klass,
1815 vmSymbols::exit_method_name(),
1816 vmSymbols::void_method_signature(),
1817 THREAD);
1818 CLEAR_PENDING_EXCEPTION;
1819 }
1820 }
1821 // notify JVMTI
1822 if (JvmtiExport::should_post_thread_life()) {
1823 JvmtiExport::post_thread_end(this);
1824 }
1825
1826 // We have notified the agents that we are exiting, before we go on,
1827 // we must check for a pending external suspend request and honor it
1828 // in order to not surprise the thread that made the suspend request.
1829 while (true) {
1830 {
1831 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1832 if (!is_external_suspend()) {
1833 set_terminated(_thread_exiting);
1834 ThreadService::current_thread_exiting(this);
1835 break;
1836 }
1837 // Implied else:
1838 // Things get a little tricky here. We have a pending external
1839 // suspend request, but we are holding the SR_lock so we
1840 // can't just self-suspend. So we temporarily drop the lock
1841 // and then self-suspend.
1842 }
1843
1844 ThreadBlockInVM tbivm(this);
1845 java_suspend_self();
1846
1847 // We're done with this suspend request, but we have to loop around
1848 // and check again. Eventually we will get SR_lock without a pending
1849 // external suspend request and will be able to mark ourselves as
1850 // exiting.
1851 }
1852 // no more external suspends are allowed at this point
1853 } else {
1854 // before_exit() has already posted JVMTI THREAD_END events
1855 }
1856
1857 // Notify waiters on thread object. This has to be done after exit() is called
1858 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1859 // group should have the destroyed bit set before waiters are notified).
1860 ensure_join(this);
1861 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1862
1863 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1864 // held by this thread must be released. The spec does not distinguish
1865 // between JNI-acquired and regular Java monitors. We can only see
1866 // regular Java monitors here if monitor enter-exit matching is broken.
1867 //
1868 // Optionally release any monitors for regular JavaThread exits. This
1869 // is provided as a work around for any bugs in monitor enter-exit
1870 // matching. This can be expensive so it is not enabled by default.
1871 //
1872 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1873 // ObjectSynchronizer::release_monitors_owned_by_thread().
1874 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1875 // Sanity check even though JNI DetachCurrentThread() would have
1876 // returned JNI_ERR if there was a Java frame. JavaThread exit
1877 // should be done executing Java code by the time we get here.
1878 assert(!this->has_last_Java_frame(),
1879 "should not have a Java frame when detaching or exiting");
1880 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1881 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1882 }
1883
1884 // These things needs to be done while we are still a Java Thread. Make sure that thread
1885 // is in a consistent state, in case GC happens
1886 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1887
1888 if (active_handles() != NULL) {
1889 JNIHandleBlock* block = active_handles();
1890 set_active_handles(NULL);
1891 JNIHandleBlock::release_block(block);
1892 }
1893
1894 if (free_handle_block() != NULL) {
1895 JNIHandleBlock* block = free_handle_block();
1896 set_free_handle_block(NULL);
1897 JNIHandleBlock::release_block(block);
1898 }
1899
1900 // These have to be removed while this is still a valid thread.
1901 remove_stack_guard_pages();
1902
1903 if (UseTLAB) {
1904 tlab().make_parsable(true); // retire TLAB
1905 }
1906
1907 if (JvmtiEnv::environments_might_exist()) {
1908 JvmtiExport::cleanup_thread(this);
1909 }
1910
1911 // We must flush any deferred card marks before removing a thread from
1912 // the list of active threads.
1913 Universe::heap()->flush_deferred_store_barrier(this);
1914 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1915
1916 #if INCLUDE_ALL_GCS
1917 // We must flush the G1-related buffers before removing a thread
1918 // from the list of active threads. We must do this after any deferred
1919 // card marks have been flushed (above) so that any entries that are
1920 // added to the thread's dirty card queue as a result are not lost.
1921 if (UseG1GC) {
1922 flush_barrier_queues();
1923 }
1924 #endif // INCLUDE_ALL_GCS
1925
1926 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1927 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1928 os::current_thread_id());
1929
1930 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1931 Threads::remove(this);
1932 }
1933
1934 #if INCLUDE_ALL_GCS
1935 // Flush G1-related queues.
1936 void JavaThread::flush_barrier_queues() {
1937 satb_mark_queue().flush();
1938 dirty_card_queue().flush();
1939 }
1940
1941 void JavaThread::initialize_queues() {
1942 assert(!SafepointSynchronize::is_at_safepoint(),
1943 "we should not be at a safepoint");
1944
1945 SATBMarkQueue& satb_queue = satb_mark_queue();
1946 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1947 // The SATB queue should have been constructed with its active
1948 // field set to false.
1949 assert(!satb_queue.is_active(), "SATB queue should not be active");
1950 assert(satb_queue.is_empty(), "SATB queue should be empty");
1951 // If we are creating the thread during a marking cycle, we should
1952 // set the active field of the SATB queue to true.
1953 if (satb_queue_set.is_active()) {
1954 satb_queue.set_active(true);
1955 }
1956
1957 DirtyCardQueue& dirty_queue = dirty_card_queue();
1958 // The dirty card queue should have been constructed with its
1959 // active field set to true.
1960 assert(dirty_queue.is_active(), "dirty card queue should be active");
1961 }
1962 #endif // INCLUDE_ALL_GCS
1963
1964 void JavaThread::cleanup_failed_attach_current_thread() {
1965 if (get_thread_profiler() != NULL) {
1966 get_thread_profiler()->disengage();
1967 ResourceMark rm;
1968 get_thread_profiler()->print(get_thread_name());
1969 }
1970
1971 if (active_handles() != NULL) {
1972 JNIHandleBlock* block = active_handles();
1973 set_active_handles(NULL);
1974 JNIHandleBlock::release_block(block);
1975 }
1976
1977 if (free_handle_block() != NULL) {
1978 JNIHandleBlock* block = free_handle_block();
1979 set_free_handle_block(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 // These have to be removed while this is still a valid thread.
1984 remove_stack_guard_pages();
1985
1986 if (UseTLAB) {
1987 tlab().make_parsable(true); // retire TLAB, if any
1988 }
1989
1990 #if INCLUDE_ALL_GCS
1991 if (UseG1GC) {
1992 flush_barrier_queues();
1993 }
1994 #endif // INCLUDE_ALL_GCS
1995
1996 Threads::remove(this);
1997 delete this;
1998 }
1999
2000
2001
2002
2003 JavaThread* JavaThread::active() {
2004 Thread* thread = Thread::current();
2005 if (thread->is_Java_thread()) {
2006 return (JavaThread*) thread;
2007 } else {
2008 assert(thread->is_VM_thread(), "this must be a vm thread");
2009 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2010 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2011 assert(ret->is_Java_thread(), "must be a Java thread");
2012 return ret;
2013 }
2014 }
2015
2016 bool JavaThread::is_lock_owned(address adr) const {
2017 if (Thread::is_lock_owned(adr)) return true;
2018
2019 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2020 if (chunk->contains(adr)) return true;
2021 }
2022
2023 return false;
2024 }
2025
2026
2027 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2028 chunk->set_next(monitor_chunks());
2029 set_monitor_chunks(chunk);
2030 }
2031
2032 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2033 guarantee(monitor_chunks() != NULL, "must be non empty");
2034 if (monitor_chunks() == chunk) {
2035 set_monitor_chunks(chunk->next());
2036 } else {
2037 MonitorChunk* prev = monitor_chunks();
2038 while (prev->next() != chunk) prev = prev->next();
2039 prev->set_next(chunk->next());
2040 }
2041 }
2042
2043 // JVM support.
2044
2045 // Note: this function shouldn't block if it's called in
2046 // _thread_in_native_trans state (such as from
2047 // check_special_condition_for_native_trans()).
2048 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2049
2050 if (has_last_Java_frame() && has_async_condition()) {
2051 // If we are at a polling page safepoint (not a poll return)
2052 // then we must defer async exception because live registers
2053 // will be clobbered by the exception path. Poll return is
2054 // ok because the call we a returning from already collides
2055 // with exception handling registers and so there is no issue.
2056 // (The exception handling path kills call result registers but
2057 // this is ok since the exception kills the result anyway).
2058
2059 if (is_at_poll_safepoint()) {
2060 // if the code we are returning to has deoptimized we must defer
2061 // the exception otherwise live registers get clobbered on the
2062 // exception path before deoptimization is able to retrieve them.
2063 //
2064 RegisterMap map(this, false);
2065 frame caller_fr = last_frame().sender(&map);
2066 assert(caller_fr.is_compiled_frame(), "what?");
2067 if (caller_fr.is_deoptimized_frame()) {
2068 log_info(exceptions)("deferred async exception at compiled safepoint");
2069 return;
2070 }
2071 }
2072 }
2073
2074 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2075 if (condition == _no_async_condition) {
2076 // Conditions have changed since has_special_runtime_exit_condition()
2077 // was called:
2078 // - if we were here only because of an external suspend request,
2079 // then that was taken care of above (or cancelled) so we are done
2080 // - if we were here because of another async request, then it has
2081 // been cleared between the has_special_runtime_exit_condition()
2082 // and now so again we are done
2083 return;
2084 }
2085
2086 // Check for pending async. exception
2087 if (_pending_async_exception != NULL) {
2088 // Only overwrite an already pending exception, if it is not a threadDeath.
2089 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2090
2091 // We cannot call Exceptions::_throw(...) here because we cannot block
2092 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2093
2094 if (log_is_enabled(Info, exceptions)) {
2095 ResourceMark rm;
2096 outputStream* logstream = LogHandle(exceptions)::info_stream();
2097 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2098 if (has_last_Java_frame()) {
2099 frame f = last_frame();
2100 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2101 }
2102 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2103 }
2104 _pending_async_exception = NULL;
2105 clear_has_async_exception();
2106 }
2107 }
2108
2109 if (check_unsafe_error &&
2110 condition == _async_unsafe_access_error && !has_pending_exception()) {
2111 condition = _no_async_condition; // done
2112 switch (thread_state()) {
2113 case _thread_in_vm: {
2114 JavaThread* THREAD = this;
2115 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2116 }
2117 case _thread_in_native: {
2118 ThreadInVMfromNative tiv(this);
2119 JavaThread* THREAD = this;
2120 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2121 }
2122 case _thread_in_Java: {
2123 ThreadInVMfromJava tiv(this);
2124 JavaThread* THREAD = this;
2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2126 }
2127 default:
2128 ShouldNotReachHere();
2129 }
2130 }
2131
2132 assert(condition == _no_async_condition || has_pending_exception() ||
2133 (!check_unsafe_error && condition == _async_unsafe_access_error),
2134 "must have handled the async condition, if no exception");
2135 }
2136
2137 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2138 //
2139 // Check for pending external suspend. Internal suspend requests do
2140 // not use handle_special_runtime_exit_condition().
2141 // If JNIEnv proxies are allowed, don't self-suspend if the target
2142 // thread is not the current thread. In older versions of jdbx, jdbx
2143 // threads could call into the VM with another thread's JNIEnv so we
2144 // can be here operating on behalf of a suspended thread (4432884).
2145 bool do_self_suspend = is_external_suspend_with_lock();
2146 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2147 //
2148 // Because thread is external suspended the safepoint code will count
2149 // thread as at a safepoint. This can be odd because we can be here
2150 // as _thread_in_Java which would normally transition to _thread_blocked
2151 // at a safepoint. We would like to mark the thread as _thread_blocked
2152 // before calling java_suspend_self like all other callers of it but
2153 // we must then observe proper safepoint protocol. (We can't leave
2154 // _thread_blocked with a safepoint in progress). However we can be
2155 // here as _thread_in_native_trans so we can't use a normal transition
2156 // constructor/destructor pair because they assert on that type of
2157 // transition. We could do something like:
2158 //
2159 // JavaThreadState state = thread_state();
2160 // set_thread_state(_thread_in_vm);
2161 // {
2162 // ThreadBlockInVM tbivm(this);
2163 // java_suspend_self()
2164 // }
2165 // set_thread_state(_thread_in_vm_trans);
2166 // if (safepoint) block;
2167 // set_thread_state(state);
2168 //
2169 // but that is pretty messy. Instead we just go with the way the
2170 // code has worked before and note that this is the only path to
2171 // java_suspend_self that doesn't put the thread in _thread_blocked
2172 // mode.
2173
2174 frame_anchor()->make_walkable(this);
2175 java_suspend_self();
2176
2177 // We might be here for reasons in addition to the self-suspend request
2178 // so check for other async requests.
2179 }
2180
2181 if (check_asyncs) {
2182 check_and_handle_async_exceptions();
2183 }
2184 }
2185
2186 void JavaThread::send_thread_stop(oop java_throwable) {
2187 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2188 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2189 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2190
2191 // Do not throw asynchronous exceptions against the compiler thread
2192 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2193 if (!can_call_java()) return;
2194
2195 {
2196 // Actually throw the Throwable against the target Thread - however
2197 // only if there is no thread death exception installed already.
2198 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2199 // If the topmost frame is a runtime stub, then we are calling into
2200 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2201 // must deoptimize the caller before continuing, as the compiled exception handler table
2202 // may not be valid
2203 if (has_last_Java_frame()) {
2204 frame f = last_frame();
2205 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2206 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2207 RegisterMap reg_map(this, UseBiasedLocking);
2208 frame compiled_frame = f.sender(®_map);
2209 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2210 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2211 }
2212 }
2213 }
2214
2215 // Set async. pending exception in thread.
2216 set_pending_async_exception(java_throwable);
2217
2218 if (log_is_enabled(Info, exceptions)) {
2219 ResourceMark rm;
2220 log_info(exceptions)("Pending Async. exception installed of type: %s",
2221 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2222 }
2223 // for AbortVMOnException flag
2224 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2225 }
2226 }
2227
2228
2229 // Interrupt thread so it will wake up from a potential wait()
2230 Thread::interrupt(this);
2231 }
2232
2233 // External suspension mechanism.
2234 //
2235 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2236 // to any VM_locks and it is at a transition
2237 // Self-suspension will happen on the transition out of the vm.
2238 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2239 //
2240 // Guarantees on return:
2241 // + Target thread will not execute any new bytecode (that's why we need to
2242 // force a safepoint)
2243 // + Target thread will not enter any new monitors
2244 //
2245 void JavaThread::java_suspend() {
2246 { MutexLocker mu(Threads_lock);
2247 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2248 return;
2249 }
2250 }
2251
2252 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2253 if (!is_external_suspend()) {
2254 // a racing resume has cancelled us; bail out now
2255 return;
2256 }
2257
2258 // suspend is done
2259 uint32_t debug_bits = 0;
2260 // Warning: is_ext_suspend_completed() may temporarily drop the
2261 // SR_lock to allow the thread to reach a stable thread state if
2262 // it is currently in a transient thread state.
2263 if (is_ext_suspend_completed(false /* !called_by_wait */,
2264 SuspendRetryDelay, &debug_bits)) {
2265 return;
2266 }
2267 }
2268
2269 VM_ForceSafepoint vm_suspend;
2270 VMThread::execute(&vm_suspend);
2271 }
2272
2273 // Part II of external suspension.
2274 // A JavaThread self suspends when it detects a pending external suspend
2275 // request. This is usually on transitions. It is also done in places
2276 // where continuing to the next transition would surprise the caller,
2277 // e.g., monitor entry.
2278 //
2279 // Returns the number of times that the thread self-suspended.
2280 //
2281 // Note: DO NOT call java_suspend_self() when you just want to block current
2282 // thread. java_suspend_self() is the second stage of cooperative
2283 // suspension for external suspend requests and should only be used
2284 // to complete an external suspend request.
2285 //
2286 int JavaThread::java_suspend_self() {
2287 int ret = 0;
2288
2289 // we are in the process of exiting so don't suspend
2290 if (is_exiting()) {
2291 clear_external_suspend();
2292 return ret;
2293 }
2294
2295 assert(_anchor.walkable() ||
2296 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2297 "must have walkable stack");
2298
2299 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2300
2301 assert(!this->is_ext_suspended(),
2302 "a thread trying to self-suspend should not already be suspended");
2303
2304 if (this->is_suspend_equivalent()) {
2305 // If we are self-suspending as a result of the lifting of a
2306 // suspend equivalent condition, then the suspend_equivalent
2307 // flag is not cleared until we set the ext_suspended flag so
2308 // that wait_for_ext_suspend_completion() returns consistent
2309 // results.
2310 this->clear_suspend_equivalent();
2311 }
2312
2313 // A racing resume may have cancelled us before we grabbed SR_lock
2314 // above. Or another external suspend request could be waiting for us
2315 // by the time we return from SR_lock()->wait(). The thread
2316 // that requested the suspension may already be trying to walk our
2317 // stack and if we return now, we can change the stack out from under
2318 // it. This would be a "bad thing (TM)" and cause the stack walker
2319 // to crash. We stay self-suspended until there are no more pending
2320 // external suspend requests.
2321 while (is_external_suspend()) {
2322 ret++;
2323 this->set_ext_suspended();
2324
2325 // _ext_suspended flag is cleared by java_resume()
2326 while (is_ext_suspended()) {
2327 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2328 }
2329 }
2330
2331 return ret;
2332 }
2333
2334 #ifdef ASSERT
2335 // verify the JavaThread has not yet been published in the Threads::list, and
2336 // hence doesn't need protection from concurrent access at this stage
2337 void JavaThread::verify_not_published() {
2338 if (!Threads_lock->owned_by_self()) {
2339 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2340 assert(!Threads::includes(this),
2341 "java thread shouldn't have been published yet!");
2342 } else {
2343 assert(!Threads::includes(this),
2344 "java thread shouldn't have been published yet!");
2345 }
2346 }
2347 #endif
2348
2349 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2350 // progress or when _suspend_flags is non-zero.
2351 // Current thread needs to self-suspend if there is a suspend request and/or
2352 // block if a safepoint is in progress.
2353 // Async exception ISN'T checked.
2354 // Note only the ThreadInVMfromNative transition can call this function
2355 // directly and when thread state is _thread_in_native_trans
2356 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2357 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2358
2359 JavaThread *curJT = JavaThread::current();
2360 bool do_self_suspend = thread->is_external_suspend();
2361
2362 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2363
2364 // If JNIEnv proxies are allowed, don't self-suspend if the target
2365 // thread is not the current thread. In older versions of jdbx, jdbx
2366 // threads could call into the VM with another thread's JNIEnv so we
2367 // can be here operating on behalf of a suspended thread (4432884).
2368 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2369 JavaThreadState state = thread->thread_state();
2370
2371 // We mark this thread_blocked state as a suspend-equivalent so
2372 // that a caller to is_ext_suspend_completed() won't be confused.
2373 // The suspend-equivalent state is cleared by java_suspend_self().
2374 thread->set_suspend_equivalent();
2375
2376 // If the safepoint code sees the _thread_in_native_trans state, it will
2377 // wait until the thread changes to other thread state. There is no
2378 // guarantee on how soon we can obtain the SR_lock and complete the
2379 // self-suspend request. It would be a bad idea to let safepoint wait for
2380 // too long. Temporarily change the state to _thread_blocked to
2381 // let the VM thread know that this thread is ready for GC. The problem
2382 // of changing thread state is that safepoint could happen just after
2383 // java_suspend_self() returns after being resumed, and VM thread will
2384 // see the _thread_blocked state. We must check for safepoint
2385 // after restoring the state and make sure we won't leave while a safepoint
2386 // is in progress.
2387 thread->set_thread_state(_thread_blocked);
2388 thread->java_suspend_self();
2389 thread->set_thread_state(state);
2390 // Make sure new state is seen by VM thread
2391 if (os::is_MP()) {
2392 if (UseMembar) {
2393 // Force a fence between the write above and read below
2394 OrderAccess::fence();
2395 } else {
2396 // Must use this rather than serialization page in particular on Windows
2397 InterfaceSupport::serialize_memory(thread);
2398 }
2399 }
2400 }
2401
2402 if (SafepointSynchronize::do_call_back()) {
2403 // If we are safepointing, then block the caller which may not be
2404 // the same as the target thread (see above).
2405 SafepointSynchronize::block(curJT);
2406 }
2407
2408 if (thread->is_deopt_suspend()) {
2409 thread->clear_deopt_suspend();
2410 RegisterMap map(thread, false);
2411 frame f = thread->last_frame();
2412 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2413 f = f.sender(&map);
2414 }
2415 if (f.id() == thread->must_deopt_id()) {
2416 thread->clear_must_deopt_id();
2417 f.deoptimize(thread);
2418 } else {
2419 fatal("missed deoptimization!");
2420 }
2421 }
2422 }
2423
2424 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2425 // progress or when _suspend_flags is non-zero.
2426 // Current thread needs to self-suspend if there is a suspend request and/or
2427 // block if a safepoint is in progress.
2428 // Also check for pending async exception (not including unsafe access error).
2429 // Note only the native==>VM/Java barriers can call this function and when
2430 // thread state is _thread_in_native_trans.
2431 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2432 check_safepoint_and_suspend_for_native_trans(thread);
2433
2434 if (thread->has_async_exception()) {
2435 // We are in _thread_in_native_trans state, don't handle unsafe
2436 // access error since that may block.
2437 thread->check_and_handle_async_exceptions(false);
2438 }
2439 }
2440
2441 // This is a variant of the normal
2442 // check_special_condition_for_native_trans with slightly different
2443 // semantics for use by critical native wrappers. It does all the
2444 // normal checks but also performs the transition back into
2445 // thread_in_Java state. This is required so that critical natives
2446 // can potentially block and perform a GC if they are the last thread
2447 // exiting the GCLocker.
2448 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2449 check_special_condition_for_native_trans(thread);
2450
2451 // Finish the transition
2452 thread->set_thread_state(_thread_in_Java);
2453
2454 if (thread->do_critical_native_unlock()) {
2455 ThreadInVMfromJavaNoAsyncException tiv(thread);
2456 GCLocker::unlock_critical(thread);
2457 thread->clear_critical_native_unlock();
2458 }
2459 }
2460
2461 // We need to guarantee the Threads_lock here, since resumes are not
2462 // allowed during safepoint synchronization
2463 // Can only resume from an external suspension
2464 void JavaThread::java_resume() {
2465 assert_locked_or_safepoint(Threads_lock);
2466
2467 // Sanity check: thread is gone, has started exiting or the thread
2468 // was not externally suspended.
2469 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2470 return;
2471 }
2472
2473 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2474
2475 clear_external_suspend();
2476
2477 if (is_ext_suspended()) {
2478 clear_ext_suspended();
2479 SR_lock()->notify_all();
2480 }
2481 }
2482
2483 size_t JavaThread::_stack_red_zone_size = 0;
2484 size_t JavaThread::_stack_yellow_zone_size = 0;
2485 size_t JavaThread::_stack_reserved_zone_size = 0;
2486 size_t JavaThread::_stack_shadow_zone_size = 0;
2487
2488 void JavaThread::create_stack_guard_pages() {
2489 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2490 address low_addr = stack_end();
2491 size_t len = stack_guard_zone_size();
2492
2493 int allocate = os::allocate_stack_guard_pages();
2494 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2495
2496 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2497 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2498 return;
2499 }
2500
2501 if (os::guard_memory((char *) low_addr, len)) {
2502 _stack_guard_state = stack_guard_enabled;
2503 } else {
2504 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2505 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2506 if (os::uncommit_memory((char *) low_addr, len)) {
2507 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2508 }
2509 return;
2510 }
2511
2512 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2513 PTR_FORMAT "-" PTR_FORMAT ".",
2514 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2515
2516 }
2517
2518 void JavaThread::remove_stack_guard_pages() {
2519 assert(Thread::current() == this, "from different thread");
2520 if (_stack_guard_state == stack_guard_unused) return;
2521 address low_addr = stack_end();
2522 size_t len = stack_guard_zone_size();
2523
2524 if (os::allocate_stack_guard_pages()) {
2525 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2526 _stack_guard_state = stack_guard_unused;
2527 } else {
2528 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2529 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2530 return;
2531 }
2532 } else {
2533 if (_stack_guard_state == stack_guard_unused) return;
2534 if (os::unguard_memory((char *) low_addr, len)) {
2535 _stack_guard_state = stack_guard_unused;
2536 } else {
2537 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2538 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2539 return;
2540 }
2541 }
2542
2543 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2544 PTR_FORMAT "-" PTR_FORMAT ".",
2545 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2546
2547 }
2548
2549 void JavaThread::enable_stack_reserved_zone() {
2550 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2551 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2552
2553 // The base notation is from the stack's point of view, growing downward.
2554 // We need to adjust it to work correctly with guard_memory()
2555 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2556
2557 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2558 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2559
2560 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2561 _stack_guard_state = stack_guard_enabled;
2562 } else {
2563 warning("Attempt to guard stack reserved zone failed.");
2564 }
2565 enable_register_stack_guard();
2566 }
2567
2568 void JavaThread::disable_stack_reserved_zone() {
2569 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2570 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2571
2572 // Simply return if called for a thread that does not use guard pages.
2573 if (_stack_guard_state == stack_guard_unused) return;
2574
2575 // The base notation is from the stack's point of view, growing downward.
2576 // We need to adjust it to work correctly with guard_memory()
2577 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2578
2579 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2580 _stack_guard_state = stack_guard_reserved_disabled;
2581 } else {
2582 warning("Attempt to unguard stack reserved zone failed.");
2583 }
2584 disable_register_stack_guard();
2585 }
2586
2587 void JavaThread::enable_stack_yellow_reserved_zone() {
2588 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2589 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2590
2591 // The base notation is from the stacks point of view, growing downward.
2592 // We need to adjust it to work correctly with guard_memory()
2593 address base = stack_red_zone_base();
2594
2595 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2596 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2597
2598 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2599 _stack_guard_state = stack_guard_enabled;
2600 } else {
2601 warning("Attempt to guard stack yellow zone failed.");
2602 }
2603 enable_register_stack_guard();
2604 }
2605
2606 void JavaThread::disable_stack_yellow_reserved_zone() {
2607 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2608 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2609
2610 // Simply return if called for a thread that does not use guard pages.
2611 if (_stack_guard_state == stack_guard_unused) return;
2612
2613 // The base notation is from the stacks point of view, growing downward.
2614 // We need to adjust it to work correctly with guard_memory()
2615 address base = stack_red_zone_base();
2616
2617 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2618 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2619 } else {
2620 warning("Attempt to unguard stack yellow zone failed.");
2621 }
2622 disable_register_stack_guard();
2623 }
2624
2625 void JavaThread::enable_stack_red_zone() {
2626 // The base notation is from the stacks point of view, growing downward.
2627 // We need to adjust it to work correctly with guard_memory()
2628 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2629 address base = stack_red_zone_base() - stack_red_zone_size();
2630
2631 guarantee(base < stack_base(), "Error calculating stack red zone");
2632 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2633
2634 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2635 warning("Attempt to guard stack red zone failed.");
2636 }
2637 }
2638
2639 void JavaThread::disable_stack_red_zone() {
2640 // The base notation is from the stacks point of view, growing downward.
2641 // We need to adjust it to work correctly with guard_memory()
2642 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2643 address base = stack_red_zone_base() - stack_red_zone_size();
2644 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2645 warning("Attempt to unguard stack red zone failed.");
2646 }
2647 }
2648
2649 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2650 // ignore is there is no stack
2651 if (!has_last_Java_frame()) return;
2652 // traverse the stack frames. Starts from top frame.
2653 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2654 frame* fr = fst.current();
2655 f(fr, fst.register_map());
2656 }
2657 }
2658
2659
2660 #ifndef PRODUCT
2661 // Deoptimization
2662 // Function for testing deoptimization
2663 void JavaThread::deoptimize() {
2664 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2665 StackFrameStream fst(this, UseBiasedLocking);
2666 bool deopt = false; // Dump stack only if a deopt actually happens.
2667 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2668 // Iterate over all frames in the thread and deoptimize
2669 for (; !fst.is_done(); fst.next()) {
2670 if (fst.current()->can_be_deoptimized()) {
2671
2672 if (only_at) {
2673 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2674 // consists of comma or carriage return separated numbers so
2675 // search for the current bci in that string.
2676 address pc = fst.current()->pc();
2677 nmethod* nm = (nmethod*) fst.current()->cb();
2678 ScopeDesc* sd = nm->scope_desc_at(pc);
2679 char buffer[8];
2680 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2681 size_t len = strlen(buffer);
2682 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2683 while (found != NULL) {
2684 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2685 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2686 // Check that the bci found is bracketed by terminators.
2687 break;
2688 }
2689 found = strstr(found + 1, buffer);
2690 }
2691 if (!found) {
2692 continue;
2693 }
2694 }
2695
2696 if (DebugDeoptimization && !deopt) {
2697 deopt = true; // One-time only print before deopt
2698 tty->print_cr("[BEFORE Deoptimization]");
2699 trace_frames();
2700 trace_stack();
2701 }
2702 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2703 }
2704 }
2705
2706 if (DebugDeoptimization && deopt) {
2707 tty->print_cr("[AFTER Deoptimization]");
2708 trace_frames();
2709 }
2710 }
2711
2712
2713 // Make zombies
2714 void JavaThread::make_zombies() {
2715 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2716 if (fst.current()->can_be_deoptimized()) {
2717 // it is a Java nmethod
2718 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2719 nm->make_not_entrant();
2720 }
2721 }
2722 }
2723 #endif // PRODUCT
2724
2725
2726 void JavaThread::deoptimized_wrt_marked_nmethods() {
2727 if (!has_last_Java_frame()) return;
2728 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2729 StackFrameStream fst(this, UseBiasedLocking);
2730 for (; !fst.is_done(); fst.next()) {
2731 if (fst.current()->should_be_deoptimized()) {
2732 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2733 }
2734 }
2735 }
2736
2737
2738 // If the caller is a NamedThread, then remember, in the current scope,
2739 // the given JavaThread in its _processed_thread field.
2740 class RememberProcessedThread: public StackObj {
2741 NamedThread* _cur_thr;
2742 public:
2743 RememberProcessedThread(JavaThread* jthr) {
2744 Thread* thread = Thread::current();
2745 if (thread->is_Named_thread()) {
2746 _cur_thr = (NamedThread *)thread;
2747 _cur_thr->set_processed_thread(jthr);
2748 } else {
2749 _cur_thr = NULL;
2750 }
2751 }
2752
2753 ~RememberProcessedThread() {
2754 if (_cur_thr) {
2755 _cur_thr->set_processed_thread(NULL);
2756 }
2757 }
2758 };
2759
2760 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2761 // Verify that the deferred card marks have been flushed.
2762 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2763
2764 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2765 // since there may be more than one thread using each ThreadProfiler.
2766
2767 // Traverse the GCHandles
2768 Thread::oops_do(f, cld_f, cf);
2769
2770 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2771
2772 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2773 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2774
2775 if (has_last_Java_frame()) {
2776 // Record JavaThread to GC thread
2777 RememberProcessedThread rpt(this);
2778
2779 // Traverse the privileged stack
2780 if (_privileged_stack_top != NULL) {
2781 _privileged_stack_top->oops_do(f);
2782 }
2783
2784 // traverse the registered growable array
2785 if (_array_for_gc != NULL) {
2786 for (int index = 0; index < _array_for_gc->length(); index++) {
2787 f->do_oop(_array_for_gc->adr_at(index));
2788 }
2789 }
2790
2791 // Traverse the monitor chunks
2792 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2793 chunk->oops_do(f);
2794 }
2795
2796 // Traverse the execution stack
2797 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2798 fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2799 }
2800 }
2801
2802 // callee_target is never live across a gc point so NULL it here should
2803 // it still contain a methdOop.
2804
2805 set_callee_target(NULL);
2806
2807 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2808 // If we have deferred set_locals there might be oops waiting to be
2809 // written
2810 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2811 if (list != NULL) {
2812 for (int i = 0; i < list->length(); i++) {
2813 list->at(i)->oops_do(f);
2814 }
2815 }
2816
2817 // Traverse instance variables at the end since the GC may be moving things
2818 // around using this function
2819 f->do_oop((oop*) &_threadObj);
2820 f->do_oop((oop*) &_vm_result);
2821 f->do_oop((oop*) &_exception_oop);
2822 f->do_oop((oop*) &_pending_async_exception);
2823
2824 if (jvmti_thread_state() != NULL) {
2825 jvmti_thread_state()->oops_do(f);
2826 }
2827 }
2828
2829 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2830 Thread::nmethods_do(cf); // (super method is a no-op)
2831
2832 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2833 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2834
2835 if (has_last_Java_frame()) {
2836 // Traverse the execution stack
2837 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2838 fst.current()->nmethods_do(cf);
2839 }
2840 }
2841 }
2842
2843 void JavaThread::metadata_do(void f(Metadata*)) {
2844 if (has_last_Java_frame()) {
2845 // Traverse the execution stack to call f() on the methods in the stack
2846 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2847 fst.current()->metadata_do(f);
2848 }
2849 } else if (is_Compiler_thread()) {
2850 // need to walk ciMetadata in current compile tasks to keep alive.
2851 CompilerThread* ct = (CompilerThread*)this;
2852 if (ct->env() != NULL) {
2853 ct->env()->metadata_do(f);
2854 }
2855 if (ct->task() != NULL) {
2856 ct->task()->metadata_do(f);
2857 }
2858 }
2859 }
2860
2861 // Printing
2862 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2863 switch (_thread_state) {
2864 case _thread_uninitialized: return "_thread_uninitialized";
2865 case _thread_new: return "_thread_new";
2866 case _thread_new_trans: return "_thread_new_trans";
2867 case _thread_in_native: return "_thread_in_native";
2868 case _thread_in_native_trans: return "_thread_in_native_trans";
2869 case _thread_in_vm: return "_thread_in_vm";
2870 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2871 case _thread_in_Java: return "_thread_in_Java";
2872 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2873 case _thread_blocked: return "_thread_blocked";
2874 case _thread_blocked_trans: return "_thread_blocked_trans";
2875 default: return "unknown thread state";
2876 }
2877 }
2878
2879 #ifndef PRODUCT
2880 void JavaThread::print_thread_state_on(outputStream *st) const {
2881 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2882 };
2883 void JavaThread::print_thread_state() const {
2884 print_thread_state_on(tty);
2885 }
2886 #endif // PRODUCT
2887
2888 // Called by Threads::print() for VM_PrintThreads operation
2889 void JavaThread::print_on(outputStream *st) const {
2890 st->print("\"%s\" ", get_thread_name());
2891 oop thread_oop = threadObj();
2892 if (thread_oop != NULL) {
2893 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2894 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2895 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2896 }
2897 Thread::print_on(st);
2898 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2899 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2900 if (thread_oop != NULL) {
2901 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2902 }
2903 #ifndef PRODUCT
2904 print_thread_state_on(st);
2905 _safepoint_state->print_on(st);
2906 #endif // PRODUCT
2907 if (is_Compiler_thread()) {
2908 CompilerThread* ct = (CompilerThread*)this;
2909 if (ct->task() != NULL) {
2910 st->print(" Compiling: ");
2911 ct->task()->print(st, NULL, true, false);
2912 } else {
2913 st->print(" No compile task");
2914 }
2915 st->cr();
2916 }
2917 }
2918
2919 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2920 st->print("%s", get_thread_name_string(buf, buflen));
2921 }
2922
2923 // Called by fatal error handler. The difference between this and
2924 // JavaThread::print() is that we can't grab lock or allocate memory.
2925 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2926 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2927 oop thread_obj = threadObj();
2928 if (thread_obj != NULL) {
2929 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2930 }
2931 st->print(" [");
2932 st->print("%s", _get_thread_state_name(_thread_state));
2933 if (osthread()) {
2934 st->print(", id=%d", osthread()->thread_id());
2935 }
2936 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2937 p2i(stack_end()), p2i(stack_base()));
2938 st->print("]");
2939 return;
2940 }
2941
2942 // Verification
2943
2944 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2945
2946 void JavaThread::verify() {
2947 // Verify oops in the thread.
2948 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2949
2950 // Verify the stack frames.
2951 frames_do(frame_verify);
2952 }
2953
2954 // CR 6300358 (sub-CR 2137150)
2955 // Most callers of this method assume that it can't return NULL but a
2956 // thread may not have a name whilst it is in the process of attaching to
2957 // the VM - see CR 6412693, and there are places where a JavaThread can be
2958 // seen prior to having it's threadObj set (eg JNI attaching threads and
2959 // if vm exit occurs during initialization). These cases can all be accounted
2960 // for such that this method never returns NULL.
2961 const char* JavaThread::get_thread_name() const {
2962 #ifdef ASSERT
2963 // early safepoints can hit while current thread does not yet have TLS
2964 if (!SafepointSynchronize::is_at_safepoint()) {
2965 Thread *cur = Thread::current();
2966 if (!(cur->is_Java_thread() && cur == this)) {
2967 // Current JavaThreads are allowed to get their own name without
2968 // the Threads_lock.
2969 assert_locked_or_safepoint(Threads_lock);
2970 }
2971 }
2972 #endif // ASSERT
2973 return get_thread_name_string();
2974 }
2975
2976 // Returns a non-NULL representation of this thread's name, or a suitable
2977 // descriptive string if there is no set name
2978 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2979 const char* name_str;
2980 oop thread_obj = threadObj();
2981 if (thread_obj != NULL) {
2982 oop name = java_lang_Thread::name(thread_obj);
2983 if (name != NULL) {
2984 if (buf == NULL) {
2985 name_str = java_lang_String::as_utf8_string(name);
2986 } else {
2987 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2988 }
2989 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2990 name_str = "<no-name - thread is attaching>";
2991 } else {
2992 name_str = Thread::name();
2993 }
2994 } else {
2995 name_str = Thread::name();
2996 }
2997 assert(name_str != NULL, "unexpected NULL thread name");
2998 return name_str;
2999 }
3000
3001
3002 const char* JavaThread::get_threadgroup_name() const {
3003 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3004 oop thread_obj = threadObj();
3005 if (thread_obj != NULL) {
3006 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3007 if (thread_group != NULL) {
3008 // ThreadGroup.name can be null
3009 return java_lang_ThreadGroup::name(thread_group);
3010 }
3011 }
3012 return NULL;
3013 }
3014
3015 const char* JavaThread::get_parent_name() const {
3016 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3017 oop thread_obj = threadObj();
3018 if (thread_obj != NULL) {
3019 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3020 if (thread_group != NULL) {
3021 oop parent = java_lang_ThreadGroup::parent(thread_group);
3022 if (parent != NULL) {
3023 // ThreadGroup.name can be null
3024 return java_lang_ThreadGroup::name(parent);
3025 }
3026 }
3027 }
3028 return NULL;
3029 }
3030
3031 ThreadPriority JavaThread::java_priority() const {
3032 oop thr_oop = threadObj();
3033 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3034 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3035 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3036 return priority;
3037 }
3038
3039 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3040
3041 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3042 // Link Java Thread object <-> C++ Thread
3043
3044 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3045 // and put it into a new Handle. The Handle "thread_oop" can then
3046 // be used to pass the C++ thread object to other methods.
3047
3048 // Set the Java level thread object (jthread) field of the
3049 // new thread (a JavaThread *) to C++ thread object using the
3050 // "thread_oop" handle.
3051
3052 // Set the thread field (a JavaThread *) of the
3053 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3054
3055 Handle thread_oop(Thread::current(),
3056 JNIHandles::resolve_non_null(jni_thread));
3057 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3058 "must be initialized");
3059 set_threadObj(thread_oop());
3060 java_lang_Thread::set_thread(thread_oop(), this);
3061
3062 if (prio == NoPriority) {
3063 prio = java_lang_Thread::priority(thread_oop());
3064 assert(prio != NoPriority, "A valid priority should be present");
3065 }
3066
3067 // Push the Java priority down to the native thread; needs Threads_lock
3068 Thread::set_priority(this, prio);
3069
3070 prepare_ext();
3071
3072 // Add the new thread to the Threads list and set it in motion.
3073 // We must have threads lock in order to call Threads::add.
3074 // It is crucial that we do not block before the thread is
3075 // added to the Threads list for if a GC happens, then the java_thread oop
3076 // will not be visited by GC.
3077 Threads::add(this);
3078 }
3079
3080 oop JavaThread::current_park_blocker() {
3081 // Support for JSR-166 locks
3082 oop thread_oop = threadObj();
3083 if (thread_oop != NULL &&
3084 JDK_Version::current().supports_thread_park_blocker()) {
3085 return java_lang_Thread::park_blocker(thread_oop);
3086 }
3087 return NULL;
3088 }
3089
3090
3091 void JavaThread::print_stack_on(outputStream* st) {
3092 if (!has_last_Java_frame()) return;
3093 ResourceMark rm;
3094 HandleMark hm;
3095
3096 RegisterMap reg_map(this);
3097 vframe* start_vf = last_java_vframe(®_map);
3098 int count = 0;
3099 for (vframe* f = start_vf; f; f = f->sender()) {
3100 if (f->is_java_frame()) {
3101 javaVFrame* jvf = javaVFrame::cast(f);
3102 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3103
3104 // Print out lock information
3105 if (JavaMonitorsInStackTrace) {
3106 jvf->print_lock_info_on(st, count);
3107 }
3108 } else {
3109 // Ignore non-Java frames
3110 }
3111
3112 // Bail-out case for too deep stacks
3113 count++;
3114 if (MaxJavaStackTraceDepth == count) return;
3115 }
3116 }
3117
3118
3119 // JVMTI PopFrame support
3120 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3121 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3122 if (in_bytes(size_in_bytes) != 0) {
3123 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3124 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3125 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3126 }
3127 }
3128
3129 void* JavaThread::popframe_preserved_args() {
3130 return _popframe_preserved_args;
3131 }
3132
3133 ByteSize JavaThread::popframe_preserved_args_size() {
3134 return in_ByteSize(_popframe_preserved_args_size);
3135 }
3136
3137 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3138 int sz = in_bytes(popframe_preserved_args_size());
3139 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3140 return in_WordSize(sz / wordSize);
3141 }
3142
3143 void JavaThread::popframe_free_preserved_args() {
3144 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3145 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3146 _popframe_preserved_args = NULL;
3147 _popframe_preserved_args_size = 0;
3148 }
3149
3150 #ifndef PRODUCT
3151
3152 void JavaThread::trace_frames() {
3153 tty->print_cr("[Describe stack]");
3154 int frame_no = 1;
3155 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3156 tty->print(" %d. ", frame_no++);
3157 fst.current()->print_value_on(tty, this);
3158 tty->cr();
3159 }
3160 }
3161
3162 class PrintAndVerifyOopClosure: public OopClosure {
3163 protected:
3164 template <class T> inline void do_oop_work(T* p) {
3165 oop obj = oopDesc::load_decode_heap_oop(p);
3166 if (obj == NULL) return;
3167 tty->print(INTPTR_FORMAT ": ", p2i(p));
3168 if (obj->is_oop_or_null()) {
3169 if (obj->is_objArray()) {
3170 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3171 } else {
3172 obj->print();
3173 }
3174 } else {
3175 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3176 }
3177 tty->cr();
3178 }
3179 public:
3180 virtual void do_oop(oop* p) { do_oop_work(p); }
3181 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3182 };
3183
3184
3185 static void oops_print(frame* f, const RegisterMap *map) {
3186 PrintAndVerifyOopClosure print;
3187 f->print_value();
3188 f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3189 }
3190
3191 // Print our all the locations that contain oops and whether they are
3192 // valid or not. This useful when trying to find the oldest frame
3193 // where an oop has gone bad since the frame walk is from youngest to
3194 // oldest.
3195 void JavaThread::trace_oops() {
3196 tty->print_cr("[Trace oops]");
3197 frames_do(oops_print);
3198 }
3199
3200
3201 #ifdef ASSERT
3202 // Print or validate the layout of stack frames
3203 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3204 ResourceMark rm;
3205 PRESERVE_EXCEPTION_MARK;
3206 FrameValues values;
3207 int frame_no = 0;
3208 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3209 fst.current()->describe(values, ++frame_no);
3210 if (depth == frame_no) break;
3211 }
3212 if (validate_only) {
3213 values.validate();
3214 } else {
3215 tty->print_cr("[Describe stack layout]");
3216 values.print(this);
3217 }
3218 }
3219 #endif
3220
3221 void JavaThread::trace_stack_from(vframe* start_vf) {
3222 ResourceMark rm;
3223 int vframe_no = 1;
3224 for (vframe* f = start_vf; f; f = f->sender()) {
3225 if (f->is_java_frame()) {
3226 javaVFrame::cast(f)->print_activation(vframe_no++);
3227 } else {
3228 f->print();
3229 }
3230 if (vframe_no > StackPrintLimit) {
3231 tty->print_cr("...<more frames>...");
3232 return;
3233 }
3234 }
3235 }
3236
3237
3238 void JavaThread::trace_stack() {
3239 if (!has_last_Java_frame()) return;
3240 ResourceMark rm;
3241 HandleMark hm;
3242 RegisterMap reg_map(this);
3243 trace_stack_from(last_java_vframe(®_map));
3244 }
3245
3246
3247 #endif // PRODUCT
3248
3249
3250 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3251 assert(reg_map != NULL, "a map must be given");
3252 frame f = last_frame();
3253 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3254 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3255 }
3256 return NULL;
3257 }
3258
3259
3260 Klass* JavaThread::security_get_caller_class(int depth) {
3261 vframeStream vfst(this);
3262 vfst.security_get_caller_frame(depth);
3263 if (!vfst.at_end()) {
3264 return vfst.method()->method_holder();
3265 }
3266 return NULL;
3267 }
3268
3269 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3270 assert(thread->is_Compiler_thread(), "must be compiler thread");
3271 CompileBroker::compiler_thread_loop();
3272 }
3273
3274 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3275 NMethodSweeper::sweeper_loop();
3276 }
3277
3278 // Create a CompilerThread
3279 CompilerThread::CompilerThread(CompileQueue* queue,
3280 CompilerCounters* counters)
3281 : JavaThread(&compiler_thread_entry) {
3282 _env = NULL;
3283 _log = NULL;
3284 _task = NULL;
3285 _queue = queue;
3286 _counters = counters;
3287 _buffer_blob = NULL;
3288 _compiler = NULL;
3289
3290 #ifndef PRODUCT
3291 _ideal_graph_printer = NULL;
3292 #endif
3293 }
3294
3295 bool CompilerThread::can_call_java() const {
3296 return _compiler != NULL && _compiler->is_jvmci();
3297 }
3298
3299 // Create sweeper thread
3300 CodeCacheSweeperThread::CodeCacheSweeperThread()
3301 : JavaThread(&sweeper_thread_entry) {
3302 _scanned_nmethod = NULL;
3303 }
3304 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3305 JavaThread::oops_do(f, cld_f, cf);
3306 if (_scanned_nmethod != NULL && cf != NULL) {
3307 // Safepoints can occur when the sweeper is scanning an nmethod so
3308 // process it here to make sure it isn't unloaded in the middle of
3309 // a scan.
3310 cf->do_code_blob(_scanned_nmethod);
3311 }
3312 }
3313
3314
3315 // ======= Threads ========
3316
3317 // The Threads class links together all active threads, and provides
3318 // operations over all threads. It is protected by its own Mutex
3319 // lock, which is also used in other contexts to protect thread
3320 // operations from having the thread being operated on from exiting
3321 // and going away unexpectedly (e.g., safepoint synchronization)
3322
3323 JavaThread* Threads::_thread_list = NULL;
3324 int Threads::_number_of_threads = 0;
3325 int Threads::_number_of_non_daemon_threads = 0;
3326 int Threads::_return_code = 0;
3327 int Threads::_thread_claim_parity = 0;
3328 size_t JavaThread::_stack_size_at_create = 0;
3329 #ifdef ASSERT
3330 bool Threads::_vm_complete = false;
3331 #endif
3332
3333 // All JavaThreads
3334 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3335
3336 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3337 void Threads::threads_do(ThreadClosure* tc) {
3338 assert_locked_or_safepoint(Threads_lock);
3339 // ALL_JAVA_THREADS iterates through all JavaThreads
3340 ALL_JAVA_THREADS(p) {
3341 tc->do_thread(p);
3342 }
3343 // Someday we could have a table or list of all non-JavaThreads.
3344 // For now, just manually iterate through them.
3345 tc->do_thread(VMThread::vm_thread());
3346 Universe::heap()->gc_threads_do(tc);
3347 WatcherThread *wt = WatcherThread::watcher_thread();
3348 // Strictly speaking, the following NULL check isn't sufficient to make sure
3349 // the data for WatcherThread is still valid upon being examined. However,
3350 // considering that WatchThread terminates when the VM is on the way to
3351 // exit at safepoint, the chance of the above is extremely small. The right
3352 // way to prevent termination of WatcherThread would be to acquire
3353 // Terminator_lock, but we can't do that without violating the lock rank
3354 // checking in some cases.
3355 if (wt != NULL) {
3356 tc->do_thread(wt);
3357 }
3358
3359 // If CompilerThreads ever become non-JavaThreads, add them here
3360 }
3361
3362 // The system initialization in the library has three phases.
3363 //
3364 // Phase 1: java.lang.System class initialization
3365 // java.lang.System is a primordial class loaded and initialized
3366 // by the VM early during startup. java.lang.System.<clinit>
3367 // only does registerNatives and keeps the rest of the class
3368 // initialization work later until thread initialization completes.
3369 //
3370 // System.initPhase1 initializes the system properties, the static
3371 // fields in, out, and err. Set up java signal handlers, OS-specific
3372 // system settings, and thread group of the main thread.
3373 static void call_initPhase1(TRAPS) {
3374 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3375 instanceKlassHandle klass (THREAD, k);
3376
3377 JavaValue result(T_VOID);
3378 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3379 vmSymbols::void_method_signature(), CHECK);
3380 }
3381
3382 // Phase 2. Module system initialization
3383 // This will initialize the module system. Only java.base classes
3384 // can be loaded until phase 2 completes.
3385 //
3386 // Call System.initPhase2 after the compiler initialization and jsr292
3387 // classes get initialized because module initialization runs a lot of java
3388 // code, that for performance reasons, should be compiled. Also, this will
3389 // enable the startup code to use lambda and other language features in this
3390 // phase and onward.
3391 //
3392 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3393 static void call_initPhase2(TRAPS) {
3394 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3395 instanceKlassHandle klass (THREAD, k);
3396
3397 JavaValue result(T_VOID);
3398 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3399 vmSymbols::void_method_signature(), CHECK);
3400 universe_post_module_init();
3401 }
3402
3403 // Phase 3. final setup - set security manager, system class loader and TCCL
3404 //
3405 // This will instantiate and set the security manager, set the system class
3406 // loader as well as the thread context class loader. The security manager
3407 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3408 // other modules or the application's classpath.
3409 static void call_initPhase3(TRAPS) {
3410 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3411 instanceKlassHandle klass (THREAD, k);
3412
3413 JavaValue result(T_VOID);
3414 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3415 vmSymbols::void_method_signature(), CHECK);
3416 }
3417
3418 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3419 TraceStartupTime timer("Initialize java.lang classes");
3420
3421 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3422 create_vm_init_libraries();
3423 }
3424
3425 initialize_class(vmSymbols::java_lang_String(), CHECK);
3426
3427 // Inject CompactStrings value after the static initializers for String ran.
3428 java_lang_String::set_compact_strings(CompactStrings);
3429
3430 // Initialize java_lang.System (needed before creating the thread)
3431 initialize_class(vmSymbols::java_lang_System(), CHECK);
3432 // The VM creates & returns objects of this class. Make sure it's initialized.
3433 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3434 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3435 Handle thread_group = create_initial_thread_group(CHECK);
3436 Universe::set_main_thread_group(thread_group());
3437 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3438 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3439 main_thread->set_threadObj(thread_object);
3440 // Set thread status to running since main thread has
3441 // been started and running.
3442 java_lang_Thread::set_thread_status(thread_object,
3443 java_lang_Thread::RUNNABLE);
3444
3445 // The VM creates objects of this class.
3446 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3447
3448 // The VM preresolves methods to these classes. Make sure that they get initialized
3449 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3450 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3451
3452 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3453 call_initPhase1(CHECK);
3454
3455 // get the Java runtime name after java.lang.System is initialized
3456 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3457 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3458
3459 // an instance of OutOfMemory exception has been allocated earlier
3460 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3461 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3462 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3463 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3464 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3465 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3466 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3467 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3468 }
3469
3470 void Threads::initialize_jsr292_core_classes(TRAPS) {
3471 TraceStartupTime timer("Initialize java.lang.invoke classes");
3472
3473 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3474 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3475 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3476 }
3477
3478 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3479 extern void JDK_Version_init();
3480
3481 // Preinitialize version info.
3482 VM_Version::early_initialize();
3483
3484 // Check version
3485 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3486
3487 // Initialize library-based TLS
3488 ThreadLocalStorage::init();
3489
3490 // Initialize the output stream module
3491 ostream_init();
3492
3493 // Process java launcher properties.
3494 Arguments::process_sun_java_launcher_properties(args);
3495
3496 // Initialize the os module
3497 os::init();
3498
3499 // Record VM creation timing statistics
3500 TraceVmCreationTime create_vm_timer;
3501 create_vm_timer.start();
3502
3503 // Initialize system properties.
3504 Arguments::init_system_properties();
3505
3506 // So that JDK version can be used as a discriminator when parsing arguments
3507 JDK_Version_init();
3508
3509 // Update/Initialize System properties after JDK version number is known
3510 Arguments::init_version_specific_system_properties();
3511
3512 // Make sure to initialize log configuration *before* parsing arguments
3513 LogConfiguration::initialize(create_vm_timer.begin_time());
3514
3515 // Parse arguments
3516 jint parse_result = Arguments::parse(args);
3517 if (parse_result != JNI_OK) return parse_result;
3518
3519 os::init_before_ergo();
3520
3521 jint ergo_result = Arguments::apply_ergo();
3522 if (ergo_result != JNI_OK) return ergo_result;
3523
3524 // Final check of all ranges after ergonomics which may change values.
3525 if (!CommandLineFlagRangeList::check_ranges()) {
3526 return JNI_EINVAL;
3527 }
3528
3529 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3530 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3531 if (!constraint_result) {
3532 return JNI_EINVAL;
3533 }
3534
3535 if (PauseAtStartup) {
3536 os::pause();
3537 }
3538
3539 HOTSPOT_VM_INIT_BEGIN();
3540
3541 // Timing (must come after argument parsing)
3542 TraceStartupTime timer("Create VM");
3543
3544 // Initialize the os module after parsing the args
3545 jint os_init_2_result = os::init_2();
3546 if (os_init_2_result != JNI_OK) return os_init_2_result;
3547
3548 jint adjust_after_os_result = Arguments::adjust_after_os();
3549 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3550
3551 // Initialize output stream logging
3552 ostream_init_log();
3553
3554 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3555 // Must be before create_vm_init_agents()
3556 if (Arguments::init_libraries_at_startup()) {
3557 convert_vm_init_libraries_to_agents();
3558 }
3559
3560 // Launch -agentlib/-agentpath and converted -Xrun agents
3561 if (Arguments::init_agents_at_startup()) {
3562 create_vm_init_agents();
3563 }
3564
3565 // Initialize Threads state
3566 _thread_list = NULL;
3567 _number_of_threads = 0;
3568 _number_of_non_daemon_threads = 0;
3569
3570 // Initialize global data structures and create system classes in heap
3571 vm_init_globals();
3572
3573 #if INCLUDE_JVMCI
3574 if (JVMCICounterSize > 0) {
3575 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3576 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3577 } else {
3578 JavaThread::_jvmci_old_thread_counters = NULL;
3579 }
3580 #endif // INCLUDE_JVMCI
3581
3582 // Attach the main thread to this os thread
3583 JavaThread* main_thread = new JavaThread();
3584 main_thread->set_thread_state(_thread_in_vm);
3585 main_thread->initialize_thread_current();
3586 // must do this before set_active_handles
3587 main_thread->record_stack_base_and_size();
3588 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3589
3590 if (!main_thread->set_as_starting_thread()) {
3591 vm_shutdown_during_initialization(
3592 "Failed necessary internal allocation. Out of swap space");
3593 delete main_thread;
3594 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3595 return JNI_ENOMEM;
3596 }
3597
3598 // Enable guard page *after* os::create_main_thread(), otherwise it would
3599 // crash Linux VM, see notes in os_linux.cpp.
3600 main_thread->create_stack_guard_pages();
3601
3602 // Initialize Java-Level synchronization subsystem
3603 ObjectMonitor::Initialize();
3604
3605 // Initialize global modules
3606 jint status = init_globals();
3607 if (status != JNI_OK) {
3608 delete main_thread;
3609 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3610 return status;
3611 }
3612
3613 if (TRACE_INITIALIZE() != JNI_OK) {
3614 vm_exit_during_initialization("Failed to initialize tracing backend");
3615 }
3616
3617 // Should be done after the heap is fully created
3618 main_thread->cache_global_variables();
3619
3620 HandleMark hm;
3621
3622 { MutexLocker mu(Threads_lock);
3623 Threads::add(main_thread);
3624 }
3625
3626 // Any JVMTI raw monitors entered in onload will transition into
3627 // real raw monitor. VM is setup enough here for raw monitor enter.
3628 JvmtiExport::transition_pending_onload_raw_monitors();
3629
3630 // Create the VMThread
3631 { TraceStartupTime timer("Start VMThread");
3632
3633 VMThread::create();
3634 Thread* vmthread = VMThread::vm_thread();
3635
3636 if (!os::create_thread(vmthread, os::vm_thread)) {
3637 vm_exit_during_initialization("Cannot create VM thread. "
3638 "Out of system resources.");
3639 }
3640
3641 // Wait for the VM thread to become ready, and VMThread::run to initialize
3642 // Monitors can have spurious returns, must always check another state flag
3643 {
3644 MutexLocker ml(Notify_lock);
3645 os::start_thread(vmthread);
3646 while (vmthread->active_handles() == NULL) {
3647 Notify_lock->wait();
3648 }
3649 }
3650 }
3651
3652 assert(Universe::is_fully_initialized(), "not initialized");
3653 if (VerifyDuringStartup) {
3654 // Make sure we're starting with a clean slate.
3655 VM_Verify verify_op;
3656 VMThread::execute(&verify_op);
3657 }
3658
3659 Thread* THREAD = Thread::current();
3660
3661 // At this point, the Universe is initialized, but we have not executed
3662 // any byte code. Now is a good time (the only time) to dump out the
3663 // internal state of the JVM for sharing.
3664 if (DumpSharedSpaces) {
3665 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3666 ShouldNotReachHere();
3667 }
3668
3669 // Always call even when there are not JVMTI environments yet, since environments
3670 // may be attached late and JVMTI must track phases of VM execution
3671 JvmtiExport::enter_early_start_phase();
3672
3673 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3674 JvmtiExport::post_early_vm_start();
3675
3676 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3677
3678 // We need this for ClassDataSharing - the initial vm.info property is set
3679 // with the default value of CDS "sharing" which may be reset through
3680 // command line options.
3681 reset_vm_info_property(CHECK_JNI_ERR);
3682
3683 quicken_jni_functions();
3684
3685 // No more stub generation allowed after that point.
3686 StubCodeDesc::freeze();
3687
3688 // Set flag that basic initialization has completed. Used by exceptions and various
3689 // debug stuff, that does not work until all basic classes have been initialized.
3690 set_init_completed();
3691
3692 LogConfiguration::post_initialize();
3693 Metaspace::post_initialize();
3694
3695 HOTSPOT_VM_INIT_END();
3696
3697 // record VM initialization completion time
3698 #if INCLUDE_MANAGEMENT
3699 Management::record_vm_init_completed();
3700 #endif // INCLUDE_MANAGEMENT
3701
3702 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3703 // set_init_completed has just been called, causing exceptions not to be shortcut
3704 // anymore. We call vm_exit_during_initialization directly instead.
3705
3706 #if INCLUDE_ALL_GCS
3707 // Support for ConcurrentMarkSweep. This should be cleaned up
3708 // and better encapsulated. The ugly nested if test would go away
3709 // once things are properly refactored. XXX YSR
3710 if (UseConcMarkSweepGC || UseG1GC) {
3711 if (UseConcMarkSweepGC) {
3712 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3713 } else {
3714 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3715 }
3716 }
3717 #endif // INCLUDE_ALL_GCS
3718
3719 // Signal Dispatcher needs to be started before VMInit event is posted
3720 os::signal_init();
3721
3722 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3723 if (!DisableAttachMechanism) {
3724 AttachListener::vm_start();
3725 if (StartAttachListener || AttachListener::init_at_startup()) {
3726 AttachListener::init();
3727 }
3728 }
3729
3730 // Launch -Xrun agents
3731 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3732 // back-end can launch with -Xdebug -Xrunjdwp.
3733 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3734 create_vm_init_libraries();
3735 }
3736
3737 if (CleanChunkPoolAsync) {
3738 Chunk::start_chunk_pool_cleaner_task();
3739 }
3740
3741 // initialize compiler(s)
3742 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3743 CompileBroker::compilation_init(CHECK_JNI_ERR);
3744 #endif
3745
3746 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3747 // It is done after compilers are initialized, because otherwise compilations of
3748 // signature polymorphic MH intrinsics can be missed
3749 // (see SystemDictionary::find_method_handle_intrinsic).
3750 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3751
3752 // This will initialize the module system. Only java.base classes can be
3753 // loaded until phase 2 completes
3754 call_initPhase2(CHECK_JNI_ERR);
3755
3756 // Always call even when there are not JVMTI environments yet, since environments
3757 // may be attached late and JVMTI must track phases of VM execution
3758 JvmtiExport::enter_start_phase();
3759
3760 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3761 JvmtiExport::post_vm_start();
3762
3763 // Final system initialization including security manager and system class loader
3764 call_initPhase3(CHECK_JNI_ERR);
3765
3766 // cache the system class loader
3767 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3768
3769 // Always call even when there are not JVMTI environments yet, since environments
3770 // may be attached late and JVMTI must track phases of VM execution
3771 JvmtiExport::enter_live_phase();
3772
3773 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3774 JvmtiExport::post_vm_initialized();
3775
3776 if (TRACE_START() != JNI_OK) {
3777 vm_exit_during_initialization("Failed to start tracing backend.");
3778 }
3779
3780 #if INCLUDE_MANAGEMENT
3781 Management::initialize(THREAD);
3782
3783 if (HAS_PENDING_EXCEPTION) {
3784 // management agent fails to start possibly due to
3785 // configuration problem and is responsible for printing
3786 // stack trace if appropriate. Simply exit VM.
3787 vm_exit(1);
3788 }
3789 #endif // INCLUDE_MANAGEMENT
3790
3791 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3792 if (MemProfiling) MemProfiler::engage();
3793 StatSampler::engage();
3794 if (CheckJNICalls) JniPeriodicChecker::engage();
3795
3796 BiasedLocking::init();
3797
3798 #if INCLUDE_RTM_OPT
3799 RTMLockingCounters::init();
3800 #endif
3801
3802 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3803 call_postVMInitHook(THREAD);
3804 // The Java side of PostVMInitHook.run must deal with all
3805 // exceptions and provide means of diagnosis.
3806 if (HAS_PENDING_EXCEPTION) {
3807 CLEAR_PENDING_EXCEPTION;
3808 }
3809 }
3810
3811 {
3812 MutexLocker ml(PeriodicTask_lock);
3813 // Make sure the WatcherThread can be started by WatcherThread::start()
3814 // or by dynamic enrollment.
3815 WatcherThread::make_startable();
3816 // Start up the WatcherThread if there are any periodic tasks
3817 // NOTE: All PeriodicTasks should be registered by now. If they
3818 // aren't, late joiners might appear to start slowly (we might
3819 // take a while to process their first tick).
3820 if (PeriodicTask::num_tasks() > 0) {
3821 WatcherThread::start();
3822 }
3823 }
3824
3825 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3826
3827 create_vm_timer.end();
3828 #ifdef ASSERT
3829 _vm_complete = true;
3830 #endif
3831 return JNI_OK;
3832 }
3833
3834 // type for the Agent_OnLoad and JVM_OnLoad entry points
3835 extern "C" {
3836 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3837 }
3838 // Find a command line agent library and return its entry point for
3839 // -agentlib: -agentpath: -Xrun
3840 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3841 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3842 const char *on_load_symbols[],
3843 size_t num_symbol_entries) {
3844 OnLoadEntry_t on_load_entry = NULL;
3845 void *library = NULL;
3846
3847 if (!agent->valid()) {
3848 char buffer[JVM_MAXPATHLEN];
3849 char ebuf[1024] = "";
3850 const char *name = agent->name();
3851 const char *msg = "Could not find agent library ";
3852
3853 // First check to see if agent is statically linked into executable
3854 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3855 library = agent->os_lib();
3856 } else if (agent->is_absolute_path()) {
3857 library = os::dll_load(name, ebuf, sizeof ebuf);
3858 if (library == NULL) {
3859 const char *sub_msg = " in absolute path, with error: ";
3860 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3861 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3862 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3863 // If we can't find the agent, exit.
3864 vm_exit_during_initialization(buf, NULL);
3865 FREE_C_HEAP_ARRAY(char, buf);
3866 }
3867 } else {
3868 // Try to load the agent from the standard dll directory
3869 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3870 name)) {
3871 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3872 }
3873 if (library == NULL) { // Try the local directory
3874 char ns[1] = {0};
3875 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3876 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3877 }
3878 if (library == NULL) {
3879 const char *sub_msg = " on the library path, with error: ";
3880 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3881 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3882 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3883 // If we can't find the agent, exit.
3884 vm_exit_during_initialization(buf, NULL);
3885 FREE_C_HEAP_ARRAY(char, buf);
3886 }
3887 }
3888 }
3889 agent->set_os_lib(library);
3890 agent->set_valid();
3891 }
3892
3893 // Find the OnLoad function.
3894 on_load_entry =
3895 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3896 false,
3897 on_load_symbols,
3898 num_symbol_entries));
3899 return on_load_entry;
3900 }
3901
3902 // Find the JVM_OnLoad entry point
3903 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3904 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3905 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3906 }
3907
3908 // Find the Agent_OnLoad entry point
3909 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3910 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3911 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3912 }
3913
3914 // For backwards compatibility with -Xrun
3915 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3916 // treated like -agentpath:
3917 // Must be called before agent libraries are created
3918 void Threads::convert_vm_init_libraries_to_agents() {
3919 AgentLibrary* agent;
3920 AgentLibrary* next;
3921
3922 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3923 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3924 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3925
3926 // If there is an JVM_OnLoad function it will get called later,
3927 // otherwise see if there is an Agent_OnLoad
3928 if (on_load_entry == NULL) {
3929 on_load_entry = lookup_agent_on_load(agent);
3930 if (on_load_entry != NULL) {
3931 // switch it to the agent list -- so that Agent_OnLoad will be called,
3932 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3933 Arguments::convert_library_to_agent(agent);
3934 } else {
3935 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3936 }
3937 }
3938 }
3939 }
3940
3941 // Create agents for -agentlib: -agentpath: and converted -Xrun
3942 // Invokes Agent_OnLoad
3943 // Called very early -- before JavaThreads exist
3944 void Threads::create_vm_init_agents() {
3945 extern struct JavaVM_ main_vm;
3946 AgentLibrary* agent;
3947
3948 JvmtiExport::enter_onload_phase();
3949
3950 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3951 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3952
3953 if (on_load_entry != NULL) {
3954 // Invoke the Agent_OnLoad function
3955 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3956 if (err != JNI_OK) {
3957 vm_exit_during_initialization("agent library failed to init", agent->name());
3958 }
3959 } else {
3960 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3961 }
3962 }
3963 JvmtiExport::enter_primordial_phase();
3964 }
3965
3966 extern "C" {
3967 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3968 }
3969
3970 void Threads::shutdown_vm_agents() {
3971 // Send any Agent_OnUnload notifications
3972 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3973 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3974 extern struct JavaVM_ main_vm;
3975 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3976
3977 // Find the Agent_OnUnload function.
3978 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3979 os::find_agent_function(agent,
3980 false,
3981 on_unload_symbols,
3982 num_symbol_entries));
3983
3984 // Invoke the Agent_OnUnload function
3985 if (unload_entry != NULL) {
3986 JavaThread* thread = JavaThread::current();
3987 ThreadToNativeFromVM ttn(thread);
3988 HandleMark hm(thread);
3989 (*unload_entry)(&main_vm);
3990 }
3991 }
3992 }
3993
3994 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3995 // Invokes JVM_OnLoad
3996 void Threads::create_vm_init_libraries() {
3997 extern struct JavaVM_ main_vm;
3998 AgentLibrary* agent;
3999
4000 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4001 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4002
4003 if (on_load_entry != NULL) {
4004 // Invoke the JVM_OnLoad function
4005 JavaThread* thread = JavaThread::current();
4006 ThreadToNativeFromVM ttn(thread);
4007 HandleMark hm(thread);
4008 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4009 if (err != JNI_OK) {
4010 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4011 }
4012 } else {
4013 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4014 }
4015 }
4016 }
4017
4018 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4019 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4020
4021 JavaThread* java_thread = NULL;
4022 // Sequential search for now. Need to do better optimization later.
4023 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4024 oop tobj = thread->threadObj();
4025 if (!thread->is_exiting() &&
4026 tobj != NULL &&
4027 java_tid == java_lang_Thread::thread_id(tobj)) {
4028 java_thread = thread;
4029 break;
4030 }
4031 }
4032 return java_thread;
4033 }
4034
4035
4036 // Last thread running calls java.lang.Shutdown.shutdown()
4037 void JavaThread::invoke_shutdown_hooks() {
4038 HandleMark hm(this);
4039
4040 // We could get here with a pending exception, if so clear it now.
4041 if (this->has_pending_exception()) {
4042 this->clear_pending_exception();
4043 }
4044
4045 EXCEPTION_MARK;
4046 Klass* k =
4047 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4048 THREAD);
4049 if (k != NULL) {
4050 // SystemDictionary::resolve_or_null will return null if there was
4051 // an exception. If we cannot load the Shutdown class, just don't
4052 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4053 // and finalizers (if runFinalizersOnExit is set) won't be run.
4054 // Note that if a shutdown hook was registered or runFinalizersOnExit
4055 // was called, the Shutdown class would have already been loaded
4056 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4057 instanceKlassHandle shutdown_klass (THREAD, k);
4058 JavaValue result(T_VOID);
4059 JavaCalls::call_static(&result,
4060 shutdown_klass,
4061 vmSymbols::shutdown_method_name(),
4062 vmSymbols::void_method_signature(),
4063 THREAD);
4064 }
4065 CLEAR_PENDING_EXCEPTION;
4066 }
4067
4068 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4069 // the program falls off the end of main(). Another VM exit path is through
4070 // vm_exit() when the program calls System.exit() to return a value or when
4071 // there is a serious error in VM. The two shutdown paths are not exactly
4072 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4073 // and VM_Exit op at VM level.
4074 //
4075 // Shutdown sequence:
4076 // + Shutdown native memory tracking if it is on
4077 // + Wait until we are the last non-daemon thread to execute
4078 // <-- every thing is still working at this moment -->
4079 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4080 // shutdown hooks, run finalizers if finalization-on-exit
4081 // + Call before_exit(), prepare for VM exit
4082 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4083 // currently the only user of this mechanism is File.deleteOnExit())
4084 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4085 // post thread end and vm death events to JVMTI,
4086 // stop signal thread
4087 // + Call JavaThread::exit(), it will:
4088 // > release JNI handle blocks, remove stack guard pages
4089 // > remove this thread from Threads list
4090 // <-- no more Java code from this thread after this point -->
4091 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4092 // the compiler threads at safepoint
4093 // <-- do not use anything that could get blocked by Safepoint -->
4094 // + Disable tracing at JNI/JVM barriers
4095 // + Set _vm_exited flag for threads that are still running native code
4096 // + Delete this thread
4097 // + Call exit_globals()
4098 // > deletes tty
4099 // > deletes PerfMemory resources
4100 // + Return to caller
4101
4102 bool Threads::destroy_vm() {
4103 JavaThread* thread = JavaThread::current();
4104
4105 #ifdef ASSERT
4106 _vm_complete = false;
4107 #endif
4108 // Wait until we are the last non-daemon thread to execute
4109 { MutexLocker nu(Threads_lock);
4110 while (Threads::number_of_non_daemon_threads() > 1)
4111 // This wait should make safepoint checks, wait without a timeout,
4112 // and wait as a suspend-equivalent condition.
4113 //
4114 // Note: If the FlatProfiler is running and this thread is waiting
4115 // for another non-daemon thread to finish, then the FlatProfiler
4116 // is waiting for the external suspend request on this thread to
4117 // complete. wait_for_ext_suspend_completion() will eventually
4118 // timeout, but that takes time. Making this wait a suspend-
4119 // equivalent condition solves that timeout problem.
4120 //
4121 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4122 Mutex::_as_suspend_equivalent_flag);
4123 }
4124
4125 // Hang forever on exit if we are reporting an error.
4126 if (ShowMessageBoxOnError && is_error_reported()) {
4127 os::infinite_sleep();
4128 }
4129 os::wait_for_keypress_at_exit();
4130
4131 // run Java level shutdown hooks
4132 thread->invoke_shutdown_hooks();
4133
4134 before_exit(thread);
4135
4136 thread->exit(true);
4137
4138 // Stop VM thread.
4139 {
4140 // 4945125 The vm thread comes to a safepoint during exit.
4141 // GC vm_operations can get caught at the safepoint, and the
4142 // heap is unparseable if they are caught. Grab the Heap_lock
4143 // to prevent this. The GC vm_operations will not be able to
4144 // queue until after the vm thread is dead. After this point,
4145 // we'll never emerge out of the safepoint before the VM exits.
4146
4147 MutexLocker ml(Heap_lock);
4148
4149 VMThread::wait_for_vm_thread_exit();
4150 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4151 VMThread::destroy();
4152 }
4153
4154 // clean up ideal graph printers
4155 #if defined(COMPILER2) && !defined(PRODUCT)
4156 IdealGraphPrinter::clean_up();
4157 #endif
4158
4159 // Now, all Java threads are gone except daemon threads. Daemon threads
4160 // running Java code or in VM are stopped by the Safepoint. However,
4161 // daemon threads executing native code are still running. But they
4162 // will be stopped at native=>Java/VM barriers. Note that we can't
4163 // simply kill or suspend them, as it is inherently deadlock-prone.
4164
4165 VM_Exit::set_vm_exited();
4166
4167 notify_vm_shutdown();
4168
4169 delete thread;
4170
4171 #if INCLUDE_JVMCI
4172 if (JVMCICounterSize > 0) {
4173 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4174 }
4175 #endif
4176
4177 // exit_globals() will delete tty
4178 exit_globals();
4179
4180 LogConfiguration::finalize();
4181
4182 return true;
4183 }
4184
4185
4186 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4187 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4188 return is_supported_jni_version(version);
4189 }
4190
4191
4192 jboolean Threads::is_supported_jni_version(jint version) {
4193 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4194 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4195 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4196 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4197 if (version == JNI_VERSION_9) return JNI_TRUE;
4198 return JNI_FALSE;
4199 }
4200
4201
4202 void Threads::add(JavaThread* p, bool force_daemon) {
4203 // The threads lock must be owned at this point
4204 assert_locked_or_safepoint(Threads_lock);
4205
4206 // See the comment for this method in thread.hpp for its purpose and
4207 // why it is called here.
4208 p->initialize_queues();
4209 p->set_next(_thread_list);
4210 _thread_list = p;
4211 _number_of_threads++;
4212 oop threadObj = p->threadObj();
4213 bool daemon = true;
4214 // Bootstrapping problem: threadObj can be null for initial
4215 // JavaThread (or for threads attached via JNI)
4216 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4217 _number_of_non_daemon_threads++;
4218 daemon = false;
4219 }
4220
4221 ThreadService::add_thread(p, daemon);
4222
4223 // Possible GC point.
4224 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4225 }
4226
4227 void Threads::remove(JavaThread* p) {
4228 // Extra scope needed for Thread_lock, so we can check
4229 // that we do not remove thread without safepoint code notice
4230 { MutexLocker ml(Threads_lock);
4231
4232 assert(includes(p), "p must be present");
4233
4234 JavaThread* current = _thread_list;
4235 JavaThread* prev = NULL;
4236
4237 while (current != p) {
4238 prev = current;
4239 current = current->next();
4240 }
4241
4242 if (prev) {
4243 prev->set_next(current->next());
4244 } else {
4245 _thread_list = p->next();
4246 }
4247 _number_of_threads--;
4248 oop threadObj = p->threadObj();
4249 bool daemon = true;
4250 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4251 _number_of_non_daemon_threads--;
4252 daemon = false;
4253
4254 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4255 // on destroy_vm will wake up.
4256 if (number_of_non_daemon_threads() == 1) {
4257 Threads_lock->notify_all();
4258 }
4259 }
4260 ThreadService::remove_thread(p, daemon);
4261
4262 // Make sure that safepoint code disregard this thread. This is needed since
4263 // the thread might mess around with locks after this point. This can cause it
4264 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4265 // of this thread since it is removed from the queue.
4266 p->set_terminated_value();
4267 } // unlock Threads_lock
4268
4269 // Since Events::log uses a lock, we grab it outside the Threads_lock
4270 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4271 }
4272
4273 // Threads_lock must be held when this is called (or must be called during a safepoint)
4274 bool Threads::includes(JavaThread* p) {
4275 assert(Threads_lock->is_locked(), "sanity check");
4276 ALL_JAVA_THREADS(q) {
4277 if (q == p) {
4278 return true;
4279 }
4280 }
4281 return false;
4282 }
4283
4284 // Operations on the Threads list for GC. These are not explicitly locked,
4285 // but the garbage collector must provide a safe context for them to run.
4286 // In particular, these things should never be called when the Threads_lock
4287 // is held by some other thread. (Note: the Safepoint abstraction also
4288 // uses the Threads_lock to guarantee this property. It also makes sure that
4289 // all threads gets blocked when exiting or starting).
4290
4291 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4292 ALL_JAVA_THREADS(p) {
4293 p->oops_do(f, cld_f, cf);
4294 }
4295 VMThread::vm_thread()->oops_do(f, cld_f, cf);
4296 }
4297
4298 void Threads::change_thread_claim_parity() {
4299 // Set the new claim parity.
4300 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4301 "Not in range.");
4302 _thread_claim_parity++;
4303 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4304 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4305 "Not in range.");
4306 }
4307
4308 #ifdef ASSERT
4309 void Threads::assert_all_threads_claimed() {
4310 ALL_JAVA_THREADS(p) {
4311 const int thread_parity = p->oops_do_parity();
4312 assert((thread_parity == _thread_claim_parity),
4313 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4314 }
4315 }
4316 #endif // ASSERT
4317
4318 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4319 int cp = Threads::thread_claim_parity();
4320 ALL_JAVA_THREADS(p) {
4321 if (p->claim_oops_do(is_par, cp)) {
4322 p->oops_do(f, cld_f, cf);
4323 }
4324 }
4325 VMThread* vmt = VMThread::vm_thread();
4326 if (vmt->claim_oops_do(is_par, cp)) {
4327 vmt->oops_do(f, cld_f, cf);
4328 }
4329 }
4330
4331 #if INCLUDE_ALL_GCS
4332 // Used by ParallelScavenge
4333 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4334 ALL_JAVA_THREADS(p) {
4335 q->enqueue(new ThreadRootsTask(p));
4336 }
4337 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4338 }
4339
4340 // Used by Parallel Old
4341 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4342 ALL_JAVA_THREADS(p) {
4343 q->enqueue(new ThreadRootsMarkingTask(p));
4344 }
4345 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4346 }
4347 #endif // INCLUDE_ALL_GCS
4348
4349 void Threads::nmethods_do(CodeBlobClosure* cf) {
4350 ALL_JAVA_THREADS(p) {
4351 p->nmethods_do(cf);
4352 }
4353 VMThread::vm_thread()->nmethods_do(cf);
4354 }
4355
4356 void Threads::metadata_do(void f(Metadata*)) {
4357 ALL_JAVA_THREADS(p) {
4358 p->metadata_do(f);
4359 }
4360 }
4361
4362 class ThreadHandlesClosure : public ThreadClosure {
4363 void (*_f)(Metadata*);
4364 public:
4365 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4366 virtual void do_thread(Thread* thread) {
4367 thread->metadata_handles_do(_f);
4368 }
4369 };
4370
4371 void Threads::metadata_handles_do(void f(Metadata*)) {
4372 // Only walk the Handles in Thread.
4373 ThreadHandlesClosure handles_closure(f);
4374 threads_do(&handles_closure);
4375 }
4376
4377 void Threads::deoptimized_wrt_marked_nmethods() {
4378 ALL_JAVA_THREADS(p) {
4379 p->deoptimized_wrt_marked_nmethods();
4380 }
4381 }
4382
4383
4384 // Get count Java threads that are waiting to enter the specified monitor.
4385 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4386 address monitor,
4387 bool doLock) {
4388 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4389 "must grab Threads_lock or be at safepoint");
4390 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4391
4392 int i = 0;
4393 {
4394 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4395 ALL_JAVA_THREADS(p) {
4396 if (!p->can_call_java()) continue;
4397
4398 address pending = (address)p->current_pending_monitor();
4399 if (pending == monitor) { // found a match
4400 if (i < count) result->append(p); // save the first count matches
4401 i++;
4402 }
4403 }
4404 }
4405 return result;
4406 }
4407
4408
4409 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4410 bool doLock) {
4411 assert(doLock ||
4412 Threads_lock->owned_by_self() ||
4413 SafepointSynchronize::is_at_safepoint(),
4414 "must grab Threads_lock or be at safepoint");
4415
4416 // NULL owner means not locked so we can skip the search
4417 if (owner == NULL) return NULL;
4418
4419 {
4420 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4421 ALL_JAVA_THREADS(p) {
4422 // first, see if owner is the address of a Java thread
4423 if (owner == (address)p) return p;
4424 }
4425 }
4426 // Cannot assert on lack of success here since this function may be
4427 // used by code that is trying to report useful problem information
4428 // like deadlock detection.
4429 if (UseHeavyMonitors) return NULL;
4430
4431 // If we didn't find a matching Java thread and we didn't force use of
4432 // heavyweight monitors, then the owner is the stack address of the
4433 // Lock Word in the owning Java thread's stack.
4434 //
4435 JavaThread* the_owner = NULL;
4436 {
4437 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4438 ALL_JAVA_THREADS(q) {
4439 if (q->is_lock_owned(owner)) {
4440 the_owner = q;
4441 break;
4442 }
4443 }
4444 }
4445 // cannot assert on lack of success here; see above comment
4446 return the_owner;
4447 }
4448
4449 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4450 void Threads::print_on(outputStream* st, bool print_stacks,
4451 bool internal_format, bool print_concurrent_locks) {
4452 char buf[32];
4453 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4454
4455 st->print_cr("Full thread dump %s (%s %s):",
4456 Abstract_VM_Version::vm_name(),
4457 Abstract_VM_Version::vm_release(),
4458 Abstract_VM_Version::vm_info_string());
4459 st->cr();
4460
4461 #if INCLUDE_SERVICES
4462 // Dump concurrent locks
4463 ConcurrentLocksDump concurrent_locks;
4464 if (print_concurrent_locks) {
4465 concurrent_locks.dump_at_safepoint();
4466 }
4467 #endif // INCLUDE_SERVICES
4468
4469 ALL_JAVA_THREADS(p) {
4470 ResourceMark rm;
4471 p->print_on(st);
4472 if (print_stacks) {
4473 if (internal_format) {
4474 p->trace_stack();
4475 } else {
4476 p->print_stack_on(st);
4477 }
4478 }
4479 st->cr();
4480 #if INCLUDE_SERVICES
4481 if (print_concurrent_locks) {
4482 concurrent_locks.print_locks_on(p, st);
4483 }
4484 #endif // INCLUDE_SERVICES
4485 }
4486
4487 VMThread::vm_thread()->print_on(st);
4488 st->cr();
4489 Universe::heap()->print_gc_threads_on(st);
4490 WatcherThread* wt = WatcherThread::watcher_thread();
4491 if (wt != NULL) {
4492 wt->print_on(st);
4493 st->cr();
4494 }
4495 st->flush();
4496 }
4497
4498 // Threads::print_on_error() is called by fatal error handler. It's possible
4499 // that VM is not at safepoint and/or current thread is inside signal handler.
4500 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4501 // memory (even in resource area), it might deadlock the error handler.
4502 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4503 int buflen) {
4504 bool found_current = false;
4505 st->print_cr("Java Threads: ( => current thread )");
4506 ALL_JAVA_THREADS(thread) {
4507 bool is_current = (current == thread);
4508 found_current = found_current || is_current;
4509
4510 st->print("%s", is_current ? "=>" : " ");
4511
4512 st->print(PTR_FORMAT, p2i(thread));
4513 st->print(" ");
4514 thread->print_on_error(st, buf, buflen);
4515 st->cr();
4516 }
4517 st->cr();
4518
4519 st->print_cr("Other Threads:");
4520 if (VMThread::vm_thread()) {
4521 bool is_current = (current == VMThread::vm_thread());
4522 found_current = found_current || is_current;
4523 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4524
4525 st->print(PTR_FORMAT, p2i(VMThread::vm_thread()));
4526 st->print(" ");
4527 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4528 st->cr();
4529 }
4530 WatcherThread* wt = WatcherThread::watcher_thread();
4531 if (wt != NULL) {
4532 bool is_current = (current == wt);
4533 found_current = found_current || is_current;
4534 st->print("%s", is_current ? "=>" : " ");
4535
4536 st->print(PTR_FORMAT, p2i(wt));
4537 st->print(" ");
4538 wt->print_on_error(st, buf, buflen);
4539 st->cr();
4540 }
4541 if (!found_current) {
4542 st->cr();
4543 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4544 current->print_on_error(st, buf, buflen);
4545 st->cr();
4546 }
4547 st->cr();
4548 st->print_cr("Threads with active compile tasks:");
4549 print_threads_compiling(st, buf, buflen);
4550 }
4551
4552 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4553 ALL_JAVA_THREADS(thread) {
4554 if (thread->is_Compiler_thread()) {
4555 CompilerThread* ct = (CompilerThread*) thread;
4556 if (ct->task() != NULL) {
4557 thread->print_name_on_error(st, buf, buflen);
4558 ct->task()->print(st, NULL, true, true);
4559 }
4560 }
4561 }
4562 }
4563
4564
4565 // Internal SpinLock and Mutex
4566 // Based on ParkEvent
4567
4568 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4569 //
4570 // We employ SpinLocks _only for low-contention, fixed-length
4571 // short-duration critical sections where we're concerned
4572 // about native mutex_t or HotSpot Mutex:: latency.
4573 // The mux construct provides a spin-then-block mutual exclusion
4574 // mechanism.
4575 //
4576 // Testing has shown that contention on the ListLock guarding gFreeList
4577 // is common. If we implement ListLock as a simple SpinLock it's common
4578 // for the JVM to devolve to yielding with little progress. This is true
4579 // despite the fact that the critical sections protected by ListLock are
4580 // extremely short.
4581 //
4582 // TODO-FIXME: ListLock should be of type SpinLock.
4583 // We should make this a 1st-class type, integrated into the lock
4584 // hierarchy as leaf-locks. Critically, the SpinLock structure
4585 // should have sufficient padding to avoid false-sharing and excessive
4586 // cache-coherency traffic.
4587
4588
4589 typedef volatile int SpinLockT;
4590
4591 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4592 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4593 return; // normal fast-path return
4594 }
4595
4596 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4597 TEVENT(SpinAcquire - ctx);
4598 int ctr = 0;
4599 int Yields = 0;
4600 for (;;) {
4601 while (*adr != 0) {
4602 ++ctr;
4603 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4604 if (Yields > 5) {
4605 os::naked_short_sleep(1);
4606 } else {
4607 os::naked_yield();
4608 ++Yields;
4609 }
4610 } else {
4611 SpinPause();
4612 }
4613 }
4614 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4615 }
4616 }
4617
4618 void Thread::SpinRelease(volatile int * adr) {
4619 assert(*adr != 0, "invariant");
4620 OrderAccess::fence(); // guarantee at least release consistency.
4621 // Roach-motel semantics.
4622 // It's safe if subsequent LDs and STs float "up" into the critical section,
4623 // but prior LDs and STs within the critical section can't be allowed
4624 // to reorder or float past the ST that releases the lock.
4625 // Loads and stores in the critical section - which appear in program
4626 // order before the store that releases the lock - must also appear
4627 // before the store that releases the lock in memory visibility order.
4628 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4629 // the ST of 0 into the lock-word which releases the lock, so fence
4630 // more than covers this on all platforms.
4631 *adr = 0;
4632 }
4633
4634 // muxAcquire and muxRelease:
4635 //
4636 // * muxAcquire and muxRelease support a single-word lock-word construct.
4637 // The LSB of the word is set IFF the lock is held.
4638 // The remainder of the word points to the head of a singly-linked list
4639 // of threads blocked on the lock.
4640 //
4641 // * The current implementation of muxAcquire-muxRelease uses its own
4642 // dedicated Thread._MuxEvent instance. If we're interested in
4643 // minimizing the peak number of extant ParkEvent instances then
4644 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4645 // as certain invariants were satisfied. Specifically, care would need
4646 // to be taken with regards to consuming unpark() "permits".
4647 // A safe rule of thumb is that a thread would never call muxAcquire()
4648 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4649 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4650 // consume an unpark() permit intended for monitorenter, for instance.
4651 // One way around this would be to widen the restricted-range semaphore
4652 // implemented in park(). Another alternative would be to provide
4653 // multiple instances of the PlatformEvent() for each thread. One
4654 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4655 //
4656 // * Usage:
4657 // -- Only as leaf locks
4658 // -- for short-term locking only as muxAcquire does not perform
4659 // thread state transitions.
4660 //
4661 // Alternatives:
4662 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4663 // but with parking or spin-then-park instead of pure spinning.
4664 // * Use Taura-Oyama-Yonenzawa locks.
4665 // * It's possible to construct a 1-0 lock if we encode the lockword as
4666 // (List,LockByte). Acquire will CAS the full lockword while Release
4667 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4668 // acquiring threads use timers (ParkTimed) to detect and recover from
4669 // the stranding window. Thread/Node structures must be aligned on 256-byte
4670 // boundaries by using placement-new.
4671 // * Augment MCS with advisory back-link fields maintained with CAS().
4672 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4673 // The validity of the backlinks must be ratified before we trust the value.
4674 // If the backlinks are invalid the exiting thread must back-track through the
4675 // the forward links, which are always trustworthy.
4676 // * Add a successor indication. The LockWord is currently encoded as
4677 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4678 // to provide the usual futile-wakeup optimization.
4679 // See RTStt for details.
4680 // * Consider schedctl.sc_nopreempt to cover the critical section.
4681 //
4682
4683
4684 typedef volatile intptr_t MutexT; // Mux Lock-word
4685 enum MuxBits { LOCKBIT = 1 };
4686
4687 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4688 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4689 if (w == 0) return;
4690 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4691 return;
4692 }
4693
4694 TEVENT(muxAcquire - Contention);
4695 ParkEvent * const Self = Thread::current()->_MuxEvent;
4696 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4697 for (;;) {
4698 int its = (os::is_MP() ? 100 : 0) + 1;
4699
4700 // Optional spin phase: spin-then-park strategy
4701 while (--its >= 0) {
4702 w = *Lock;
4703 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4704 return;
4705 }
4706 }
4707
4708 Self->reset();
4709 Self->OnList = intptr_t(Lock);
4710 // The following fence() isn't _strictly necessary as the subsequent
4711 // CAS() both serializes execution and ratifies the fetched *Lock value.
4712 OrderAccess::fence();
4713 for (;;) {
4714 w = *Lock;
4715 if ((w & LOCKBIT) == 0) {
4716 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4717 Self->OnList = 0; // hygiene - allows stronger asserts
4718 return;
4719 }
4720 continue; // Interference -- *Lock changed -- Just retry
4721 }
4722 assert(w & LOCKBIT, "invariant");
4723 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4724 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4725 }
4726
4727 while (Self->OnList != 0) {
4728 Self->park();
4729 }
4730 }
4731 }
4732
4733 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4734 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4735 if (w == 0) return;
4736 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4737 return;
4738 }
4739
4740 TEVENT(muxAcquire - Contention);
4741 ParkEvent * ReleaseAfter = NULL;
4742 if (ev == NULL) {
4743 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4744 }
4745 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4746 for (;;) {
4747 guarantee(ev->OnList == 0, "invariant");
4748 int its = (os::is_MP() ? 100 : 0) + 1;
4749
4750 // Optional spin phase: spin-then-park strategy
4751 while (--its >= 0) {
4752 w = *Lock;
4753 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4754 if (ReleaseAfter != NULL) {
4755 ParkEvent::Release(ReleaseAfter);
4756 }
4757 return;
4758 }
4759 }
4760
4761 ev->reset();
4762 ev->OnList = intptr_t(Lock);
4763 // The following fence() isn't _strictly necessary as the subsequent
4764 // CAS() both serializes execution and ratifies the fetched *Lock value.
4765 OrderAccess::fence();
4766 for (;;) {
4767 w = *Lock;
4768 if ((w & LOCKBIT) == 0) {
4769 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4770 ev->OnList = 0;
4771 // We call ::Release while holding the outer lock, thus
4772 // artificially lengthening the critical section.
4773 // Consider deferring the ::Release() until the subsequent unlock(),
4774 // after we've dropped the outer lock.
4775 if (ReleaseAfter != NULL) {
4776 ParkEvent::Release(ReleaseAfter);
4777 }
4778 return;
4779 }
4780 continue; // Interference -- *Lock changed -- Just retry
4781 }
4782 assert(w & LOCKBIT, "invariant");
4783 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4784 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4785 }
4786
4787 while (ev->OnList != 0) {
4788 ev->park();
4789 }
4790 }
4791 }
4792
4793 // Release() must extract a successor from the list and then wake that thread.
4794 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4795 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4796 // Release() would :
4797 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4798 // (B) Extract a successor from the private list "in-hand"
4799 // (C) attempt to CAS() the residual back into *Lock over null.
4800 // If there were any newly arrived threads and the CAS() would fail.
4801 // In that case Release() would detach the RATs, re-merge the list in-hand
4802 // with the RATs and repeat as needed. Alternately, Release() might
4803 // detach and extract a successor, but then pass the residual list to the wakee.
4804 // The wakee would be responsible for reattaching and remerging before it
4805 // competed for the lock.
4806 //
4807 // Both "pop" and DMR are immune from ABA corruption -- there can be
4808 // multiple concurrent pushers, but only one popper or detacher.
4809 // This implementation pops from the head of the list. This is unfair,
4810 // but tends to provide excellent throughput as hot threads remain hot.
4811 // (We wake recently run threads first).
4812 //
4813 // All paths through muxRelease() will execute a CAS.
4814 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4815 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4816 // executed within the critical section are complete and globally visible before the
4817 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4818 void Thread::muxRelease(volatile intptr_t * Lock) {
4819 for (;;) {
4820 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4821 assert(w & LOCKBIT, "invariant");
4822 if (w == LOCKBIT) return;
4823 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4824 assert(List != NULL, "invariant");
4825 assert(List->OnList == intptr_t(Lock), "invariant");
4826 ParkEvent * const nxt = List->ListNext;
4827 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4828
4829 // The following CAS() releases the lock and pops the head element.
4830 // The CAS() also ratifies the previously fetched lock-word value.
4831 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4832 continue;
4833 }
4834 List->OnList = 0;
4835 OrderAccess::fence();
4836 List->unpark();
4837 return;
4838 }
4839 }
4840
4841
4842 void Threads::verify() {
4843 ALL_JAVA_THREADS(p) {
4844 p->verify();
4845 }
4846 VMThread* thread = VMThread::vm_thread();
4847 if (thread != NULL) thread->verify();
4848 }