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/resourceArea.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm_misc.hpp"
55 #include "prims/jvmtiExport.hpp"
56 #include "prims/jvmtiThreadState.hpp"
57 #include "prims/privilegedStack.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/atomic.hpp"
60 #include "runtime/biasedLocking.hpp"
61 #include "runtime/commandLineFlagConstraintList.hpp"
62 #include "runtime/commandLineFlagWriteableList.hpp"
63 #include "runtime/commandLineFlagRangeList.hpp"
64 #include "runtime/deoptimization.hpp"
65 #include "runtime/fprofiler.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/interfaceSupport.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/javaCalls.hpp"
72 #include "runtime/jniPeriodicChecker.hpp"
73 #include "runtime/timerTrace.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/statSampler.hpp"
82 #include "runtime/stubRoutines.hpp"
83 #include "runtime/sweeper.hpp"
84 #include "runtime/task.hpp"
85 #include "runtime/thread.inline.hpp"
86 #include "runtime/threadCritical.hpp"
87 #include "runtime/vframe.hpp"
88 #include "runtime/vframeArray.hpp"
89 #include "runtime/vframe_hp.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "runtime/vm_operations.hpp"
92 #include "runtime/vm_version.hpp"
93 #include "services/attachListener.hpp"
94 #include "services/management.hpp"
95 #include "services/memTracker.hpp"
96 #include "services/threadService.hpp"
97 #include "trace/traceMacros.hpp"
98 #include "trace/tracing.hpp"
99 #include "utilities/defaultStream.hpp"
100 #include "utilities/dtrace.hpp"
101 #include "utilities/events.hpp"
102 #include "utilities/macros.hpp"
103 #include "utilities/preserveException.hpp"
104 #if INCLUDE_JVMCI
105 #include "jvmci/jvmciCompiler.hpp"
106 #include "jvmci/jvmciRuntime.hpp"
107 #endif
108 #ifdef COMPILER1
109 #include "c1/c1_Compiler.hpp"
110 #endif
111 #ifdef COMPILER2
112 #include "opto/c2compiler.hpp"
113 #include "opto/idealGraphPrinter.hpp"
114 #endif
115 #if INCLUDE_RTM_OPT
116 #include "runtime/rtmLocking.hpp"
117 #endif
118
119 // Initialization after module runtime initialization
120 void universe_post_module_init(); // must happen after call_initPhase2
121
122 #ifdef DTRACE_ENABLED
123
124 // Only bother with this argument setup if dtrace is available
125
126 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
127 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
128
129 #define DTRACE_THREAD_PROBE(probe, javathread) \
130 { \
131 ResourceMark rm(this); \
132 int len = 0; \
133 const char* name = (javathread)->get_thread_name(); \
134 len = strlen(name); \
135 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
136 (char *) name, len, \
137 java_lang_Thread::thread_id((javathread)->threadObj()), \
138 (uintptr_t) (javathread)->osthread()->thread_id(), \
139 java_lang_Thread::is_daemon((javathread)->threadObj())); \
140 }
141
142 #else // ndef DTRACE_ENABLED
143
144 #define DTRACE_THREAD_PROBE(probe, javathread)
145
146 #endif // ndef DTRACE_ENABLED
147
148 #ifndef USE_LIBRARY_BASED_TLS_ONLY
149 // Current thread is maintained as a thread-local variable
150 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
151 #endif
152 // Class hierarchy
153 // - Thread
154 // - VMThread
155 // - WatcherThread
156 // - ConcurrentMarkSweepThread
157 // - JavaThread
158 // - CompilerThread
159
160 // ======= Thread ========
161 // Support for forcing alignment of thread objects for biased locking
162 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
163 if (UseBiasedLocking) {
164 const int alignment = markOopDesc::biased_lock_alignment;
165 size_t aligned_size = size + (alignment - sizeof(intptr_t));
166 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
167 : AllocateHeap(aligned_size, flags, CURRENT_PC,
168 AllocFailStrategy::RETURN_NULL);
169 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
170 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
171 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
172 "JavaThread alignment code overflowed allocated storage");
173 if (aligned_addr != real_malloc_addr) {
174 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
175 p2i(real_malloc_addr),
176 p2i(aligned_addr));
177 }
178 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
179 return aligned_addr;
180 } else {
181 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
182 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
183 }
184 }
185
186 void Thread::operator delete(void* p) {
187 if (UseBiasedLocking) {
188 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
189 FreeHeap(real_malloc_addr);
190 } else {
191 FreeHeap(p);
192 }
193 }
194
195
196 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
197 // JavaThread
198
199
200 Thread::Thread() {
201 // stack and get_thread
202 set_stack_base(NULL);
203 set_stack_size(0);
204 set_self_raw_id(0);
205 set_lgrp_id(-1);
206 DEBUG_ONLY(clear_suspendible_thread();)
207
208 // allocated data structures
209 set_osthread(NULL);
210 set_resource_area(new (mtThread)ResourceArea());
211 DEBUG_ONLY(_current_resource_mark = NULL;)
212 set_handle_area(new (mtThread) HandleArea(NULL));
213 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
214 set_active_handles(NULL);
215 set_free_handle_block(NULL);
216 set_last_handle_mark(NULL);
217
218 // This initial value ==> never claimed.
219 _oops_do_parity = 0;
220
221 // the handle mark links itself to last_handle_mark
222 new HandleMark(this);
223
224 // plain initialization
225 debug_only(_owned_locks = NULL;)
226 debug_only(_allow_allocation_count = 0;)
227 NOT_PRODUCT(_allow_safepoint_count = 0;)
228 NOT_PRODUCT(_skip_gcalot = false;)
229 _jvmti_env_iteration_count = 0;
230 set_allocated_bytes(0);
231 _vm_operation_started_count = 0;
232 _vm_operation_completed_count = 0;
233 _current_pending_monitor = NULL;
234 _current_pending_monitor_is_from_java = true;
235 _current_waiting_monitor = NULL;
236 _num_nested_signal = 0;
237 omFreeList = NULL;
238 omFreeCount = 0;
239 omFreeProvision = 32;
240 omInUseList = NULL;
241 omInUseCount = 0;
242
243 #ifdef ASSERT
244 _visited_for_critical_count = false;
245 #endif
246
247 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
248 Monitor::_safepoint_check_sometimes);
249 _suspend_flags = 0;
250
251 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
252 _hashStateX = os::random();
253 _hashStateY = 842502087;
254 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
255 _hashStateW = 273326509;
256
257 _OnTrap = 0;
258 _schedctl = NULL;
259 _Stalled = 0;
260 _TypeTag = 0x2BAD;
261
262 // Many of the following fields are effectively final - immutable
263 // Note that nascent threads can't use the Native Monitor-Mutex
264 // construct until the _MutexEvent is initialized ...
265 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
266 // we might instead use a stack of ParkEvents that we could provision on-demand.
267 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
268 // and ::Release()
269 _ParkEvent = ParkEvent::Allocate(this);
270 _SleepEvent = ParkEvent::Allocate(this);
271 _MutexEvent = ParkEvent::Allocate(this);
272 _MuxEvent = ParkEvent::Allocate(this);
273
274 #ifdef CHECK_UNHANDLED_OOPS
275 if (CheckUnhandledOops) {
276 _unhandled_oops = new UnhandledOops(this);
277 }
278 #endif // CHECK_UNHANDLED_OOPS
279 #ifdef ASSERT
280 if (UseBiasedLocking) {
281 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
282 assert(this == _real_malloc_address ||
283 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
284 "bug in forced alignment of thread objects");
285 }
286 #endif // ASSERT
287 }
288
289 void Thread::initialize_thread_current() {
290 #ifndef USE_LIBRARY_BASED_TLS_ONLY
291 assert(_thr_current == NULL, "Thread::current already initialized");
292 _thr_current = this;
293 #endif
294 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
295 ThreadLocalStorage::set_thread(this);
296 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
297 }
298
299 void Thread::clear_thread_current() {
300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
301 #ifndef USE_LIBRARY_BASED_TLS_ONLY
302 _thr_current = NULL;
303 #endif
304 ThreadLocalStorage::set_thread(NULL);
305 }
306
307 void Thread::record_stack_base_and_size() {
308 set_stack_base(os::current_stack_base());
309 set_stack_size(os::current_stack_size());
310 // CR 7190089: on Solaris, primordial thread's stack is adjusted
311 // in initialize_thread(). Without the adjustment, stack size is
312 // incorrect if stack is set to unlimited (ulimit -s unlimited).
313 // So far, only Solaris has real implementation of initialize_thread().
314 //
315 // set up any platform-specific state.
316 os::initialize_thread(this);
317
318 // Set stack limits after thread is initialized.
319 if (is_Java_thread()) {
320 ((JavaThread*) this)->set_stack_overflow_limit();
321 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
322 }
323 #if INCLUDE_NMT
324 // record thread's native stack, stack grows downward
325 MemTracker::record_thread_stack(stack_end(), stack_size());
326 #endif // INCLUDE_NMT
327 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
328 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
329 os::current_thread_id(), p2i(stack_base() - stack_size()),
330 p2i(stack_base()), stack_size()/1024);
331 }
332
333
334 Thread::~Thread() {
335 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
336 ObjectSynchronizer::omFlush(this);
337
338 EVENT_THREAD_DESTRUCT(this);
339
340 // stack_base can be NULL if the thread is never started or exited before
341 // record_stack_base_and_size called. Although, we would like to ensure
342 // that all started threads do call record_stack_base_and_size(), there is
343 // not proper way to enforce that.
344 #if INCLUDE_NMT
345 if (_stack_base != NULL) {
346 MemTracker::release_thread_stack(stack_end(), stack_size());
347 #ifdef ASSERT
348 set_stack_base(NULL);
349 #endif
350 }
351 #endif // INCLUDE_NMT
352
353 // deallocate data structures
354 delete resource_area();
355 // since the handle marks are using the handle area, we have to deallocated the root
356 // handle mark before deallocating the thread's handle area,
357 assert(last_handle_mark() != NULL, "check we have an element");
358 delete last_handle_mark();
359 assert(last_handle_mark() == NULL, "check we have reached the end");
360
361 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
362 // We NULL out the fields for good hygiene.
363 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
364 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
365 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
366 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
367
368 delete handle_area();
369 delete metadata_handles();
370
371 // SR_handler uses this as a termination indicator -
372 // needs to happen before os::free_thread()
373 delete _SR_lock;
374 _SR_lock = NULL;
375
376 // osthread() can be NULL, if creation of thread failed.
377 if (osthread() != NULL) os::free_thread(osthread());
378
379 // clear Thread::current if thread is deleting itself.
380 // Needed to ensure JNI correctly detects non-attached threads.
381 if (this == Thread::current()) {
382 clear_thread_current();
383 }
384
385 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
386 }
387
388 // NOTE: dummy function for assertion purpose.
389 void Thread::run() {
390 ShouldNotReachHere();
391 }
392
393 #ifdef ASSERT
394 // Private method to check for dangling thread pointer
395 void check_for_dangling_thread_pointer(Thread *thread) {
396 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
397 "possibility of dangling Thread pointer");
398 }
399 #endif
400
401 ThreadPriority Thread::get_priority(const Thread* const thread) {
402 ThreadPriority priority;
403 // Can return an error!
404 (void)os::get_priority(thread, priority);
405 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
406 return priority;
407 }
408
409 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
410 debug_only(check_for_dangling_thread_pointer(thread);)
411 // Can return an error!
412 (void)os::set_priority(thread, priority);
413 }
414
415
416 void Thread::start(Thread* thread) {
417 // Start is different from resume in that its safety is guaranteed by context or
418 // being called from a Java method synchronized on the Thread object.
419 if (!DisableStartThread) {
420 if (thread->is_Java_thread()) {
421 // Initialize the thread state to RUNNABLE before starting this thread.
422 // Can not set it after the thread started because we do not know the
423 // exact thread state at that time. It could be in MONITOR_WAIT or
424 // in SLEEPING or some other state.
425 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
426 java_lang_Thread::RUNNABLE);
427 }
428 os::start_thread(thread);
429 }
430 }
431
432 // Enqueue a VM_Operation to do the job for us - sometime later
433 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
434 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
435 VMThread::execute(vm_stop);
436 }
437
438
439 // Check if an external suspend request has completed (or has been
440 // cancelled). Returns true if the thread is externally suspended and
441 // false otherwise.
442 //
443 // The bits parameter returns information about the code path through
444 // the routine. Useful for debugging:
445 //
446 // set in is_ext_suspend_completed():
447 // 0x00000001 - routine was entered
448 // 0x00000010 - routine return false at end
449 // 0x00000100 - thread exited (return false)
450 // 0x00000200 - suspend request cancelled (return false)
451 // 0x00000400 - thread suspended (return true)
452 // 0x00001000 - thread is in a suspend equivalent state (return true)
453 // 0x00002000 - thread is native and walkable (return true)
454 // 0x00004000 - thread is native_trans and walkable (needed retry)
455 //
456 // set in wait_for_ext_suspend_completion():
457 // 0x00010000 - routine was entered
458 // 0x00020000 - suspend request cancelled before loop (return false)
459 // 0x00040000 - thread suspended before loop (return true)
460 // 0x00080000 - suspend request cancelled in loop (return false)
461 // 0x00100000 - thread suspended in loop (return true)
462 // 0x00200000 - suspend not completed during retry loop (return false)
463
464 // Helper class for tracing suspend wait debug bits.
465 //
466 // 0x00000100 indicates that the target thread exited before it could
467 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
468 // 0x00080000 each indicate a cancelled suspend request so they don't
469 // count as wait failures either.
470 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
471
472 class TraceSuspendDebugBits : public StackObj {
473 private:
474 JavaThread * jt;
475 bool is_wait;
476 bool called_by_wait; // meaningful when !is_wait
477 uint32_t * bits;
478
479 public:
480 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
481 uint32_t *_bits) {
482 jt = _jt;
483 is_wait = _is_wait;
484 called_by_wait = _called_by_wait;
485 bits = _bits;
486 }
487
488 ~TraceSuspendDebugBits() {
489 if (!is_wait) {
490 #if 1
491 // By default, don't trace bits for is_ext_suspend_completed() calls.
492 // That trace is very chatty.
493 return;
494 #else
495 if (!called_by_wait) {
496 // If tracing for is_ext_suspend_completed() is enabled, then only
497 // trace calls to it from wait_for_ext_suspend_completion()
498 return;
499 }
500 #endif
501 }
502
503 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
504 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
505 MutexLocker ml(Threads_lock); // needed for get_thread_name()
506 ResourceMark rm;
507
508 tty->print_cr(
509 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
510 jt->get_thread_name(), *bits);
511
512 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
513 }
514 }
515 }
516 };
517 #undef DEBUG_FALSE_BITS
518
519
520 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
521 uint32_t *bits) {
522 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
523
524 bool did_trans_retry = false; // only do thread_in_native_trans retry once
525 bool do_trans_retry; // flag to force the retry
526
527 *bits |= 0x00000001;
528
529 do {
530 do_trans_retry = false;
531
532 if (is_exiting()) {
533 // Thread is in the process of exiting. This is always checked
534 // first to reduce the risk of dereferencing a freed JavaThread.
535 *bits |= 0x00000100;
536 return false;
537 }
538
539 if (!is_external_suspend()) {
540 // Suspend request is cancelled. This is always checked before
541 // is_ext_suspended() to reduce the risk of a rogue resume
542 // confusing the thread that made the suspend request.
543 *bits |= 0x00000200;
544 return false;
545 }
546
547 if (is_ext_suspended()) {
548 // thread is suspended
549 *bits |= 0x00000400;
550 return true;
551 }
552
553 // Now that we no longer do hard suspends of threads running
554 // native code, the target thread can be changing thread state
555 // while we are in this routine:
556 //
557 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
558 //
559 // We save a copy of the thread state as observed at this moment
560 // and make our decision about suspend completeness based on the
561 // copy. This closes the race where the thread state is seen as
562 // _thread_in_native_trans in the if-thread_blocked check, but is
563 // seen as _thread_blocked in if-thread_in_native_trans check.
564 JavaThreadState save_state = thread_state();
565
566 if (save_state == _thread_blocked && is_suspend_equivalent()) {
567 // If the thread's state is _thread_blocked and this blocking
568 // condition is known to be equivalent to a suspend, then we can
569 // consider the thread to be externally suspended. This means that
570 // the code that sets _thread_blocked has been modified to do
571 // self-suspension if the blocking condition releases. We also
572 // used to check for CONDVAR_WAIT here, but that is now covered by
573 // the _thread_blocked with self-suspension check.
574 //
575 // Return true since we wouldn't be here unless there was still an
576 // external suspend request.
577 *bits |= 0x00001000;
578 return true;
579 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
580 // Threads running native code will self-suspend on native==>VM/Java
581 // transitions. If its stack is walkable (should always be the case
582 // unless this function is called before the actual java_suspend()
583 // call), then the wait is done.
584 *bits |= 0x00002000;
585 return true;
586 } else if (!called_by_wait && !did_trans_retry &&
587 save_state == _thread_in_native_trans &&
588 frame_anchor()->walkable()) {
589 // The thread is transitioning from thread_in_native to another
590 // thread state. check_safepoint_and_suspend_for_native_trans()
591 // will force the thread to self-suspend. If it hasn't gotten
592 // there yet we may have caught the thread in-between the native
593 // code check above and the self-suspend. Lucky us. If we were
594 // called by wait_for_ext_suspend_completion(), then it
595 // will be doing the retries so we don't have to.
596 //
597 // Since we use the saved thread state in the if-statement above,
598 // there is a chance that the thread has already transitioned to
599 // _thread_blocked by the time we get here. In that case, we will
600 // make a single unnecessary pass through the logic below. This
601 // doesn't hurt anything since we still do the trans retry.
602
603 *bits |= 0x00004000;
604
605 // Once the thread leaves thread_in_native_trans for another
606 // thread state, we break out of this retry loop. We shouldn't
607 // need this flag to prevent us from getting back here, but
608 // sometimes paranoia is good.
609 did_trans_retry = true;
610
611 // We wait for the thread to transition to a more usable state.
612 for (int i = 1; i <= SuspendRetryCount; i++) {
613 // We used to do an "os::yield_all(i)" call here with the intention
614 // that yielding would increase on each retry. However, the parameter
615 // is ignored on Linux which means the yield didn't scale up. Waiting
616 // on the SR_lock below provides a much more predictable scale up for
617 // the delay. It also provides a simple/direct point to check for any
618 // safepoint requests from the VMThread
619
620 // temporarily drops SR_lock while doing wait with safepoint check
621 // (if we're a JavaThread - the WatcherThread can also call this)
622 // and increase delay with each retry
623 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
624
625 // check the actual thread state instead of what we saved above
626 if (thread_state() != _thread_in_native_trans) {
627 // the thread has transitioned to another thread state so
628 // try all the checks (except this one) one more time.
629 do_trans_retry = true;
630 break;
631 }
632 } // end retry loop
633
634
635 }
636 } while (do_trans_retry);
637
638 *bits |= 0x00000010;
639 return false;
640 }
641
642 // Wait for an external suspend request to complete (or be cancelled).
643 // Returns true if the thread is externally suspended and false otherwise.
644 //
645 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
646 uint32_t *bits) {
647 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
648 false /* !called_by_wait */, bits);
649
650 // local flag copies to minimize SR_lock hold time
651 bool is_suspended;
652 bool pending;
653 uint32_t reset_bits;
654
655 // set a marker so is_ext_suspend_completed() knows we are the caller
656 *bits |= 0x00010000;
657
658 // We use reset_bits to reinitialize the bits value at the top of
659 // each retry loop. This allows the caller to make use of any
660 // unused bits for their own marking purposes.
661 reset_bits = *bits;
662
663 {
664 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
665 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
666 delay, bits);
667 pending = is_external_suspend();
668 }
669 // must release SR_lock to allow suspension to complete
670
671 if (!pending) {
672 // A cancelled suspend request is the only false return from
673 // is_ext_suspend_completed() that keeps us from entering the
674 // retry loop.
675 *bits |= 0x00020000;
676 return false;
677 }
678
679 if (is_suspended) {
680 *bits |= 0x00040000;
681 return true;
682 }
683
684 for (int i = 1; i <= retries; i++) {
685 *bits = reset_bits; // reinit to only track last retry
686
687 // We used to do an "os::yield_all(i)" call here with the intention
688 // that yielding would increase on each retry. However, the parameter
689 // is ignored on Linux which means the yield didn't scale up. Waiting
690 // on the SR_lock below provides a much more predictable scale up for
691 // the delay. It also provides a simple/direct point to check for any
692 // safepoint requests from the VMThread
693
694 {
695 MutexLocker ml(SR_lock());
696 // wait with safepoint check (if we're a JavaThread - the WatcherThread
697 // can also call this) and increase delay with each retry
698 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
699
700 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
701 delay, bits);
702
703 // It is possible for the external suspend request to be cancelled
704 // (by a resume) before the actual suspend operation is completed.
705 // Refresh our local copy to see if we still need to wait.
706 pending = is_external_suspend();
707 }
708
709 if (!pending) {
710 // A cancelled suspend request is the only false return from
711 // is_ext_suspend_completed() that keeps us from staying in the
712 // retry loop.
713 *bits |= 0x00080000;
714 return false;
715 }
716
717 if (is_suspended) {
718 *bits |= 0x00100000;
719 return true;
720 }
721 } // end retry loop
722
723 // thread did not suspend after all our retries
724 *bits |= 0x00200000;
725 return false;
726 }
727
728 #ifndef PRODUCT
729 void JavaThread::record_jump(address target, address instr, const char* file,
730 int line) {
731
732 // This should not need to be atomic as the only way for simultaneous
733 // updates is via interrupts. Even then this should be rare or non-existent
734 // and we don't care that much anyway.
735
736 int index = _jmp_ring_index;
737 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
738 _jmp_ring[index]._target = (intptr_t) target;
739 _jmp_ring[index]._instruction = (intptr_t) instr;
740 _jmp_ring[index]._file = file;
741 _jmp_ring[index]._line = line;
742 }
743 #endif // PRODUCT
744
745 // Called by flat profiler
746 // Callers have already called wait_for_ext_suspend_completion
747 // The assertion for that is currently too complex to put here:
748 bool JavaThread::profile_last_Java_frame(frame* _fr) {
749 bool gotframe = false;
750 // self suspension saves needed state.
751 if (has_last_Java_frame() && _anchor.walkable()) {
752 *_fr = pd_last_frame();
753 gotframe = true;
754 }
755 return gotframe;
756 }
757
758 void Thread::interrupt(Thread* thread) {
759 debug_only(check_for_dangling_thread_pointer(thread);)
760 os::interrupt(thread);
761 }
762
763 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
764 debug_only(check_for_dangling_thread_pointer(thread);)
765 // Note: If clear_interrupted==false, this simply fetches and
766 // returns the value of the field osthread()->interrupted().
767 return os::is_interrupted(thread, clear_interrupted);
768 }
769
770
771 // GC Support
772 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
773 jint thread_parity = _oops_do_parity;
774 if (thread_parity != strong_roots_parity) {
775 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
776 if (res == thread_parity) {
777 return true;
778 } else {
779 guarantee(res == strong_roots_parity, "Or else what?");
780 return false;
781 }
782 }
783 return false;
784 }
785
786 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
787 active_handles()->oops_do(f);
788 // Do oop for ThreadShadow
789 f->do_oop((oop*)&_pending_exception);
790 handle_area()->oops_do(f);
791 }
792
793 void Thread::metadata_handles_do(void f(Metadata*)) {
794 // Only walk the Handles in Thread.
795 if (metadata_handles() != NULL) {
796 for (int i = 0; i< metadata_handles()->length(); i++) {
797 f(metadata_handles()->at(i));
798 }
799 }
800 }
801
802 void Thread::print_on(outputStream* st) const {
803 // get_priority assumes osthread initialized
804 if (osthread() != NULL) {
805 int os_prio;
806 if (os::get_native_priority(this, &os_prio) == OS_OK) {
807 st->print("os_prio=%d ", os_prio);
808 }
809 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
810 ext().print_on(st);
811 osthread()->print_on(st);
812 }
813 debug_only(if (WizardMode) print_owned_locks_on(st);)
814 }
815
816 // Thread::print_on_error() is called by fatal error handler. Don't use
817 // any lock or allocate memory.
818 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
819 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
820
821 if (is_VM_thread()) { st->print("VMThread"); }
822 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
823 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
824 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
825 else { st->print("Thread"); }
826
827 if (is_Named_thread()) {
828 st->print(" \"%s\"", name());
829 }
830
831 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
832 p2i(stack_end()), p2i(stack_base()));
833
834 if (osthread()) {
835 st->print(" [id=%d]", osthread()->thread_id());
836 }
837 }
838
839 #ifdef ASSERT
840 void Thread::print_owned_locks_on(outputStream* st) const {
841 Monitor *cur = _owned_locks;
842 if (cur == NULL) {
843 st->print(" (no locks) ");
844 } else {
845 st->print_cr(" Locks owned:");
846 while (cur) {
847 cur->print_on(st);
848 cur = cur->next();
849 }
850 }
851 }
852
853 static int ref_use_count = 0;
854
855 bool Thread::owns_locks_but_compiled_lock() const {
856 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
857 if (cur != Compile_lock) return true;
858 }
859 return false;
860 }
861
862
863 #endif
864
865 #ifndef PRODUCT
866
867 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
868 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
869 // no threads which allow_vm_block's are held
870 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
871 // Check if current thread is allowed to block at a safepoint
872 if (!(_allow_safepoint_count == 0)) {
873 fatal("Possible safepoint reached by thread that does not allow it");
874 }
875 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
876 fatal("LEAF method calling lock?");
877 }
878
879 #ifdef ASSERT
880 if (potential_vm_operation && is_Java_thread()
881 && !Universe::is_bootstrapping()) {
882 // Make sure we do not hold any locks that the VM thread also uses.
883 // This could potentially lead to deadlocks
884 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
885 // Threads_lock is special, since the safepoint synchronization will not start before this is
886 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
887 // since it is used to transfer control between JavaThreads and the VMThread
888 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
889 if ((cur->allow_vm_block() &&
890 cur != Threads_lock &&
891 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
892 cur != VMOperationRequest_lock &&
893 cur != VMOperationQueue_lock) ||
894 cur->rank() == Mutex::special) {
895 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
896 }
897 }
898 }
899
900 if (GCALotAtAllSafepoints) {
901 // We could enter a safepoint here and thus have a gc
902 InterfaceSupport::check_gc_alot();
903 }
904 #endif
905 }
906 #endif
907
908 bool Thread::is_in_stack(address adr) const {
909 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
910 address end = os::current_stack_pointer();
911 // Allow non Java threads to call this without stack_base
912 if (_stack_base == NULL) return true;
913 if (stack_base() >= adr && adr >= end) return true;
914
915 return false;
916 }
917
918 bool Thread::is_in_usable_stack(address adr) const {
919 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
920 size_t usable_stack_size = _stack_size - stack_guard_size;
921
922 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
923 }
924
925
926 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
927 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
928 // used for compilation in the future. If that change is made, the need for these methods
929 // should be revisited, and they should be removed if possible.
930
931 bool Thread::is_lock_owned(address adr) const {
932 return on_local_stack(adr);
933 }
934
935 bool Thread::set_as_starting_thread() {
936 // NOTE: this must be called inside the main thread.
937 return os::create_main_thread((JavaThread*)this);
938 }
939
940 static void initialize_class(Symbol* class_name, TRAPS) {
941 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
942 InstanceKlass::cast(klass)->initialize(CHECK);
943 }
944
945
946 // Creates the initial ThreadGroup
947 static Handle create_initial_thread_group(TRAPS) {
948 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
949 instanceKlassHandle klass (THREAD, k);
950
951 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
952 {
953 JavaValue result(T_VOID);
954 JavaCalls::call_special(&result,
955 system_instance,
956 klass,
957 vmSymbols::object_initializer_name(),
958 vmSymbols::void_method_signature(),
959 CHECK_NH);
960 }
961 Universe::set_system_thread_group(system_instance());
962
963 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
964 {
965 JavaValue result(T_VOID);
966 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
967 JavaCalls::call_special(&result,
968 main_instance,
969 klass,
970 vmSymbols::object_initializer_name(),
971 vmSymbols::threadgroup_string_void_signature(),
972 system_instance,
973 string,
974 CHECK_NH);
975 }
976 return main_instance;
977 }
978
979 // Creates the initial Thread
980 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
981 TRAPS) {
982 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
983 instanceKlassHandle klass (THREAD, k);
984 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
985
986 java_lang_Thread::set_thread(thread_oop(), thread);
987 java_lang_Thread::set_priority(thread_oop(), NormPriority);
988 thread->set_threadObj(thread_oop());
989
990 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
991
992 JavaValue result(T_VOID);
993 JavaCalls::call_special(&result, thread_oop,
994 klass,
995 vmSymbols::object_initializer_name(),
996 vmSymbols::threadgroup_string_void_signature(),
997 thread_group,
998 string,
999 CHECK_NULL);
1000 return thread_oop();
1001 }
1002
1003 char java_runtime_name[128] = "";
1004 char java_runtime_version[128] = "";
1005
1006 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1007 static const char* get_java_runtime_name(TRAPS) {
1008 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1009 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1010 fieldDescriptor fd;
1011 bool found = k != NULL &&
1012 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1013 vmSymbols::string_signature(), &fd);
1014 if (found) {
1015 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1016 if (name_oop == NULL) {
1017 return NULL;
1018 }
1019 const char* name = java_lang_String::as_utf8_string(name_oop,
1020 java_runtime_name,
1021 sizeof(java_runtime_name));
1022 return name;
1023 } else {
1024 return NULL;
1025 }
1026 }
1027
1028 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1029 static const char* get_java_runtime_version(TRAPS) {
1030 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1031 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1032 fieldDescriptor fd;
1033 bool found = k != NULL &&
1034 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1035 vmSymbols::string_signature(), &fd);
1036 if (found) {
1037 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1038 if (name_oop == NULL) {
1039 return NULL;
1040 }
1041 const char* name = java_lang_String::as_utf8_string(name_oop,
1042 java_runtime_version,
1043 sizeof(java_runtime_version));
1044 return name;
1045 } else {
1046 return NULL;
1047 }
1048 }
1049
1050 // General purpose hook into Java code, run once when the VM is initialized.
1051 // The Java library method itself may be changed independently from the VM.
1052 static void call_postVMInitHook(TRAPS) {
1053 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1054 instanceKlassHandle klass (THREAD, k);
1055 if (klass.not_null()) {
1056 JavaValue result(T_VOID);
1057 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1058 vmSymbols::void_method_signature(),
1059 CHECK);
1060 }
1061 }
1062
1063 static void reset_vm_info_property(TRAPS) {
1064 // the vm info string
1065 ResourceMark rm(THREAD);
1066 const char *vm_info = VM_Version::vm_info_string();
1067
1068 // java.lang.System class
1069 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1070 instanceKlassHandle klass (THREAD, k);
1071
1072 // setProperty arguments
1073 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1074 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1075
1076 // return value
1077 JavaValue r(T_OBJECT);
1078
1079 // public static String setProperty(String key, String value);
1080 JavaCalls::call_static(&r,
1081 klass,
1082 vmSymbols::setProperty_name(),
1083 vmSymbols::string_string_string_signature(),
1084 key_str,
1085 value_str,
1086 CHECK);
1087 }
1088
1089
1090 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1091 bool daemon, TRAPS) {
1092 assert(thread_group.not_null(), "thread group should be specified");
1093 assert(threadObj() == NULL, "should only create Java thread object once");
1094
1095 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1096 instanceKlassHandle klass (THREAD, k);
1097 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1098
1099 java_lang_Thread::set_thread(thread_oop(), this);
1100 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1101 set_threadObj(thread_oop());
1102
1103 JavaValue result(T_VOID);
1104 if (thread_name != NULL) {
1105 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1106 // Thread gets assigned specified name and null target
1107 JavaCalls::call_special(&result,
1108 thread_oop,
1109 klass,
1110 vmSymbols::object_initializer_name(),
1111 vmSymbols::threadgroup_string_void_signature(),
1112 thread_group, // Argument 1
1113 name, // Argument 2
1114 THREAD);
1115 } else {
1116 // Thread gets assigned name "Thread-nnn" and null target
1117 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1118 JavaCalls::call_special(&result,
1119 thread_oop,
1120 klass,
1121 vmSymbols::object_initializer_name(),
1122 vmSymbols::threadgroup_runnable_void_signature(),
1123 thread_group, // Argument 1
1124 Handle(), // Argument 2
1125 THREAD);
1126 }
1127
1128
1129 if (daemon) {
1130 java_lang_Thread::set_daemon(thread_oop());
1131 }
1132
1133 if (HAS_PENDING_EXCEPTION) {
1134 return;
1135 }
1136
1137 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1138 Handle threadObj(THREAD, this->threadObj());
1139
1140 JavaCalls::call_special(&result,
1141 thread_group,
1142 group,
1143 vmSymbols::add_method_name(),
1144 vmSymbols::thread_void_signature(),
1145 threadObj, // Arg 1
1146 THREAD);
1147 }
1148
1149 // NamedThread -- non-JavaThread subclasses with multiple
1150 // uniquely named instances should derive from this.
1151 NamedThread::NamedThread() : Thread() {
1152 _name = NULL;
1153 _processed_thread = NULL;
1154 _gc_id = GCId::undefined();
1155 }
1156
1157 NamedThread::~NamedThread() {
1158 if (_name != NULL) {
1159 FREE_C_HEAP_ARRAY(char, _name);
1160 _name = NULL;
1161 }
1162 }
1163
1164 void NamedThread::set_name(const char* format, ...) {
1165 guarantee(_name == NULL, "Only get to set name once.");
1166 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1167 guarantee(_name != NULL, "alloc failure");
1168 va_list ap;
1169 va_start(ap, format);
1170 jio_vsnprintf(_name, max_name_len, format, ap);
1171 va_end(ap);
1172 }
1173
1174 void NamedThread::initialize_named_thread() {
1175 set_native_thread_name(name());
1176 }
1177
1178 void NamedThread::print_on(outputStream* st) const {
1179 st->print("\"%s\" ", name());
1180 Thread::print_on(st);
1181 st->cr();
1182 }
1183
1184
1185 // ======= WatcherThread ========
1186
1187 // The watcher thread exists to simulate timer interrupts. It should
1188 // be replaced by an abstraction over whatever native support for
1189 // timer interrupts exists on the platform.
1190
1191 WatcherThread* WatcherThread::_watcher_thread = NULL;
1192 bool WatcherThread::_startable = false;
1193 volatile bool WatcherThread::_should_terminate = false;
1194
1195 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1196 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1197 if (os::create_thread(this, os::watcher_thread)) {
1198 _watcher_thread = this;
1199
1200 // Set the watcher thread to the highest OS priority which should not be
1201 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1202 // is created. The only normal thread using this priority is the reference
1203 // handler thread, which runs for very short intervals only.
1204 // If the VMThread's priority is not lower than the WatcherThread profiling
1205 // will be inaccurate.
1206 os::set_priority(this, MaxPriority);
1207 if (!DisableStartThread) {
1208 os::start_thread(this);
1209 }
1210 }
1211 }
1212
1213 int WatcherThread::sleep() const {
1214 // The WatcherThread does not participate in the safepoint protocol
1215 // for the PeriodicTask_lock because it is not a JavaThread.
1216 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1217
1218 if (_should_terminate) {
1219 // check for termination before we do any housekeeping or wait
1220 return 0; // we did not sleep.
1221 }
1222
1223 // remaining will be zero if there are no tasks,
1224 // causing the WatcherThread to sleep until a task is
1225 // enrolled
1226 int remaining = PeriodicTask::time_to_wait();
1227 int time_slept = 0;
1228
1229 // we expect this to timeout - we only ever get unparked when
1230 // we should terminate or when a new task has been enrolled
1231 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1232
1233 jlong time_before_loop = os::javaTimeNanos();
1234
1235 while (true) {
1236 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1237 remaining);
1238 jlong now = os::javaTimeNanos();
1239
1240 if (remaining == 0) {
1241 // if we didn't have any tasks we could have waited for a long time
1242 // consider the time_slept zero and reset time_before_loop
1243 time_slept = 0;
1244 time_before_loop = now;
1245 } else {
1246 // need to recalculate since we might have new tasks in _tasks
1247 time_slept = (int) ((now - time_before_loop) / 1000000);
1248 }
1249
1250 // Change to task list or spurious wakeup of some kind
1251 if (timedout || _should_terminate) {
1252 break;
1253 }
1254
1255 remaining = PeriodicTask::time_to_wait();
1256 if (remaining == 0) {
1257 // Last task was just disenrolled so loop around and wait until
1258 // another task gets enrolled
1259 continue;
1260 }
1261
1262 remaining -= time_slept;
1263 if (remaining <= 0) {
1264 break;
1265 }
1266 }
1267
1268 return time_slept;
1269 }
1270
1271 void WatcherThread::run() {
1272 assert(this == watcher_thread(), "just checking");
1273
1274 this->record_stack_base_and_size();
1275 this->set_native_thread_name(this->name());
1276 this->set_active_handles(JNIHandleBlock::allocate_block());
1277 while (true) {
1278 assert(watcher_thread() == Thread::current(), "thread consistency check");
1279 assert(watcher_thread() == this, "thread consistency check");
1280
1281 // Calculate how long it'll be until the next PeriodicTask work
1282 // should be done, and sleep that amount of time.
1283 int time_waited = sleep();
1284
1285 if (is_error_reported()) {
1286 // A fatal error has happened, the error handler(VMError::report_and_die)
1287 // should abort JVM after creating an error log file. However in some
1288 // rare cases, the error handler itself might deadlock. Here we try to
1289 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1290 //
1291 // This code is in WatcherThread because WatcherThread wakes up
1292 // periodically so the fatal error handler doesn't need to do anything;
1293 // also because the WatcherThread is less likely to crash than other
1294 // threads.
1295
1296 for (;;) {
1297 if (!ShowMessageBoxOnError
1298 && (OnError == NULL || OnError[0] == '\0')
1299 && Arguments::abort_hook() == NULL) {
1300 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1301 fdStream err(defaultStream::output_fd());
1302 err.print_raw_cr("# [ timer expired, abort... ]");
1303 // skip atexit/vm_exit/vm_abort hooks
1304 os::die();
1305 }
1306
1307 // Wake up 5 seconds later, the fatal handler may reset OnError or
1308 // ShowMessageBoxOnError when it is ready to abort.
1309 os::sleep(this, 5 * 1000, false);
1310 }
1311 }
1312
1313 if (_should_terminate) {
1314 // check for termination before posting the next tick
1315 break;
1316 }
1317
1318 PeriodicTask::real_time_tick(time_waited);
1319 }
1320
1321 // Signal that it is terminated
1322 {
1323 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1324 _watcher_thread = NULL;
1325 Terminator_lock->notify();
1326 }
1327 }
1328
1329 void WatcherThread::start() {
1330 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1331
1332 if (watcher_thread() == NULL && _startable) {
1333 _should_terminate = false;
1334 // Create the single instance of WatcherThread
1335 new WatcherThread();
1336 }
1337 }
1338
1339 void WatcherThread::make_startable() {
1340 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1341 _startable = true;
1342 }
1343
1344 void WatcherThread::stop() {
1345 {
1346 // Follow normal safepoint aware lock enter protocol since the
1347 // WatcherThread is stopped by another JavaThread.
1348 MutexLocker ml(PeriodicTask_lock);
1349 _should_terminate = true;
1350
1351 WatcherThread* watcher = watcher_thread();
1352 if (watcher != NULL) {
1353 // unpark the WatcherThread so it can see that it should terminate
1354 watcher->unpark();
1355 }
1356 }
1357
1358 MutexLocker mu(Terminator_lock);
1359
1360 while (watcher_thread() != NULL) {
1361 // This wait should make safepoint checks, wait without a timeout,
1362 // and wait as a suspend-equivalent condition.
1363 //
1364 // Note: If the FlatProfiler is running, then this thread is waiting
1365 // for the WatcherThread to terminate and the WatcherThread, via the
1366 // FlatProfiler task, is waiting for the external suspend request on
1367 // this thread to complete. wait_for_ext_suspend_completion() will
1368 // eventually timeout, but that takes time. Making this wait a
1369 // suspend-equivalent condition solves that timeout problem.
1370 //
1371 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1372 Mutex::_as_suspend_equivalent_flag);
1373 }
1374 }
1375
1376 void WatcherThread::unpark() {
1377 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1378 PeriodicTask_lock->notify();
1379 }
1380
1381 void WatcherThread::print_on(outputStream* st) const {
1382 st->print("\"%s\" ", name());
1383 Thread::print_on(st);
1384 st->cr();
1385 }
1386
1387 // ======= JavaThread ========
1388
1389 #if INCLUDE_JVMCI
1390
1391 jlong* JavaThread::_jvmci_old_thread_counters;
1392
1393 bool jvmci_counters_include(JavaThread* thread) {
1394 oop threadObj = thread->threadObj();
1395 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1396 }
1397
1398 void JavaThread::collect_counters(typeArrayOop array) {
1399 if (JVMCICounterSize > 0) {
1400 MutexLocker tl(Threads_lock);
1401 for (int i = 0; i < array->length(); i++) {
1402 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1403 }
1404 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1405 if (jvmci_counters_include(tp)) {
1406 for (int i = 0; i < array->length(); i++) {
1407 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1408 }
1409 }
1410 }
1411 }
1412 }
1413
1414 #endif // INCLUDE_JVMCI
1415
1416 // A JavaThread is a normal Java thread
1417
1418 void JavaThread::initialize() {
1419 // Initialize fields
1420
1421 set_saved_exception_pc(NULL);
1422 set_threadObj(NULL);
1423 _anchor.clear();
1424 set_entry_point(NULL);
1425 set_jni_functions(jni_functions());
1426 set_callee_target(NULL);
1427 set_vm_result(NULL);
1428 set_vm_result_2(NULL);
1429 set_vframe_array_head(NULL);
1430 set_vframe_array_last(NULL);
1431 set_deferred_locals(NULL);
1432 set_deopt_mark(NULL);
1433 set_deopt_compiled_method(NULL);
1434 clear_must_deopt_id();
1435 set_monitor_chunks(NULL);
1436 set_next(NULL);
1437 set_thread_state(_thread_new);
1438 _terminated = _not_terminated;
1439 _privileged_stack_top = NULL;
1440 _array_for_gc = NULL;
1441 _suspend_equivalent = false;
1442 _in_deopt_handler = 0;
1443 _doing_unsafe_access = false;
1444 _stack_guard_state = stack_guard_unused;
1445 #if INCLUDE_JVMCI
1446 _pending_monitorenter = false;
1447 _pending_deoptimization = -1;
1448 _pending_failed_speculation = NULL;
1449 _pending_transfer_to_interpreter = false;
1450 _adjusting_comp_level = 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 GC::gc()->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 = Log(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 must_commit = os::must_commit_stack_guard_pages();
2494 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2495
2496 if (must_commit && !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 void JavaThread::remove_stack_guard_pages() {
2518 assert(Thread::current() == this, "from different thread");
2519 if (_stack_guard_state == stack_guard_unused) return;
2520 address low_addr = stack_end();
2521 size_t len = stack_guard_zone_size();
2522
2523 if (os::must_commit_stack_guard_pages()) {
2524 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2525 _stack_guard_state = stack_guard_unused;
2526 } else {
2527 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2528 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2529 return;
2530 }
2531 } else {
2532 if (_stack_guard_state == stack_guard_unused) return;
2533 if (os::unguard_memory((char *) low_addr, len)) {
2534 _stack_guard_state = stack_guard_unused;
2535 } else {
2536 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2537 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2538 return;
2539 }
2540 }
2541
2542 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2543 PTR_FORMAT "-" PTR_FORMAT ".",
2544 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2545 }
2546
2547 void JavaThread::enable_stack_reserved_zone() {
2548 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2549 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2550
2551 // The base notation is from the stack's point of view, growing downward.
2552 // We need to adjust it to work correctly with guard_memory()
2553 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2554
2555 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2556 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2557
2558 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2559 _stack_guard_state = stack_guard_enabled;
2560 } else {
2561 warning("Attempt to guard stack reserved zone failed.");
2562 }
2563 enable_register_stack_guard();
2564 }
2565
2566 void JavaThread::disable_stack_reserved_zone() {
2567 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2568 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2569
2570 // Simply return if called for a thread that does not use guard pages.
2571 if (_stack_guard_state == stack_guard_unused) return;
2572
2573 // The base notation is from the stack's point of view, growing downward.
2574 // We need to adjust it to work correctly with guard_memory()
2575 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2576
2577 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2578 _stack_guard_state = stack_guard_reserved_disabled;
2579 } else {
2580 warning("Attempt to unguard stack reserved zone failed.");
2581 }
2582 disable_register_stack_guard();
2583 }
2584
2585 void JavaThread::enable_stack_yellow_reserved_zone() {
2586 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2587 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2588
2589 // The base notation is from the stacks point of view, growing downward.
2590 // We need to adjust it to work correctly with guard_memory()
2591 address base = stack_red_zone_base();
2592
2593 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2594 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2595
2596 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2597 _stack_guard_state = stack_guard_enabled;
2598 } else {
2599 warning("Attempt to guard stack yellow zone failed.");
2600 }
2601 enable_register_stack_guard();
2602 }
2603
2604 void JavaThread::disable_stack_yellow_reserved_zone() {
2605 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2606 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2607
2608 // Simply return if called for a thread that does not use guard pages.
2609 if (_stack_guard_state == stack_guard_unused) return;
2610
2611 // The base notation is from the stacks point of view, growing downward.
2612 // We need to adjust it to work correctly with guard_memory()
2613 address base = stack_red_zone_base();
2614
2615 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2616 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2617 } else {
2618 warning("Attempt to unguard stack yellow zone failed.");
2619 }
2620 disable_register_stack_guard();
2621 }
2622
2623 void JavaThread::enable_stack_red_zone() {
2624 // The base notation is from the stacks point of view, growing downward.
2625 // We need to adjust it to work correctly with guard_memory()
2626 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2627 address base = stack_red_zone_base() - stack_red_zone_size();
2628
2629 guarantee(base < stack_base(), "Error calculating stack red zone");
2630 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2631
2632 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2633 warning("Attempt to guard stack red zone failed.");
2634 }
2635 }
2636
2637 void JavaThread::disable_stack_red_zone() {
2638 // The base notation is from the stacks point of view, growing downward.
2639 // We need to adjust it to work correctly with guard_memory()
2640 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2641 address base = stack_red_zone_base() - stack_red_zone_size();
2642 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2643 warning("Attempt to unguard stack red zone failed.");
2644 }
2645 }
2646
2647 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2648 // ignore is there is no stack
2649 if (!has_last_Java_frame()) return;
2650 // traverse the stack frames. Starts from top frame.
2651 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2652 frame* fr = fst.current();
2653 f(fr, fst.register_map());
2654 }
2655 }
2656
2657
2658 #ifndef PRODUCT
2659 // Deoptimization
2660 // Function for testing deoptimization
2661 void JavaThread::deoptimize() {
2662 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2663 StackFrameStream fst(this, UseBiasedLocking);
2664 bool deopt = false; // Dump stack only if a deopt actually happens.
2665 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2666 // Iterate over all frames in the thread and deoptimize
2667 for (; !fst.is_done(); fst.next()) {
2668 if (fst.current()->can_be_deoptimized()) {
2669
2670 if (only_at) {
2671 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2672 // consists of comma or carriage return separated numbers so
2673 // search for the current bci in that string.
2674 address pc = fst.current()->pc();
2675 nmethod* nm = (nmethod*) fst.current()->cb();
2676 ScopeDesc* sd = nm->scope_desc_at(pc);
2677 char buffer[8];
2678 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2679 size_t len = strlen(buffer);
2680 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2681 while (found != NULL) {
2682 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2683 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2684 // Check that the bci found is bracketed by terminators.
2685 break;
2686 }
2687 found = strstr(found + 1, buffer);
2688 }
2689 if (!found) {
2690 continue;
2691 }
2692 }
2693
2694 if (DebugDeoptimization && !deopt) {
2695 deopt = true; // One-time only print before deopt
2696 tty->print_cr("[BEFORE Deoptimization]");
2697 trace_frames();
2698 trace_stack();
2699 }
2700 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2701 }
2702 }
2703
2704 if (DebugDeoptimization && deopt) {
2705 tty->print_cr("[AFTER Deoptimization]");
2706 trace_frames();
2707 }
2708 }
2709
2710
2711 // Make zombies
2712 void JavaThread::make_zombies() {
2713 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2714 if (fst.current()->can_be_deoptimized()) {
2715 // it is a Java nmethod
2716 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2717 nm->make_not_entrant();
2718 }
2719 }
2720 }
2721 #endif // PRODUCT
2722
2723
2724 void JavaThread::deoptimized_wrt_marked_nmethods() {
2725 if (!has_last_Java_frame()) return;
2726 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2727 StackFrameStream fst(this, UseBiasedLocking);
2728 for (; !fst.is_done(); fst.next()) {
2729 if (fst.current()->should_be_deoptimized()) {
2730 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2731 }
2732 }
2733 }
2734
2735
2736 // If the caller is a NamedThread, then remember, in the current scope,
2737 // the given JavaThread in its _processed_thread field.
2738 class RememberProcessedThread: public StackObj {
2739 NamedThread* _cur_thr;
2740 public:
2741 RememberProcessedThread(JavaThread* jthr) {
2742 Thread* thread = Thread::current();
2743 if (thread->is_Named_thread()) {
2744 _cur_thr = (NamedThread *)thread;
2745 _cur_thr->set_processed_thread(jthr);
2746 } else {
2747 _cur_thr = NULL;
2748 }
2749 }
2750
2751 ~RememberProcessedThread() {
2752 if (_cur_thr) {
2753 _cur_thr->set_processed_thread(NULL);
2754 }
2755 }
2756 };
2757
2758 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2759 // Verify that the deferred card marks have been flushed.
2760 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2761
2762 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2763 // since there may be more than one thread using each ThreadProfiler.
2764
2765 // Traverse the GCHandles
2766 Thread::oops_do(f, cf);
2767
2768 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2769
2770 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2771 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2772
2773 if (has_last_Java_frame()) {
2774 // Record JavaThread to GC thread
2775 RememberProcessedThread rpt(this);
2776
2777 // Traverse the privileged stack
2778 if (_privileged_stack_top != NULL) {
2779 _privileged_stack_top->oops_do(f);
2780 }
2781
2782 // traverse the registered growable array
2783 if (_array_for_gc != NULL) {
2784 for (int index = 0; index < _array_for_gc->length(); index++) {
2785 f->do_oop(_array_for_gc->adr_at(index));
2786 }
2787 }
2788
2789 // Traverse the monitor chunks
2790 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2791 chunk->oops_do(f);
2792 }
2793
2794 // Traverse the execution stack
2795 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2796 fst.current()->oops_do(f, cf, fst.register_map());
2797 }
2798 }
2799
2800 // callee_target is never live across a gc point so NULL it here should
2801 // it still contain a methdOop.
2802
2803 set_callee_target(NULL);
2804
2805 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2806 // If we have deferred set_locals there might be oops waiting to be
2807 // written
2808 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2809 if (list != NULL) {
2810 for (int i = 0; i < list->length(); i++) {
2811 list->at(i)->oops_do(f);
2812 }
2813 }
2814
2815 // Traverse instance variables at the end since the GC may be moving things
2816 // around using this function
2817 f->do_oop((oop*) &_threadObj);
2818 f->do_oop((oop*) &_vm_result);
2819 f->do_oop((oop*) &_exception_oop);
2820 f->do_oop((oop*) &_pending_async_exception);
2821
2822 if (jvmti_thread_state() != NULL) {
2823 jvmti_thread_state()->oops_do(f);
2824 }
2825 }
2826
2827 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2828 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2829 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2830
2831 if (has_last_Java_frame()) {
2832 // Traverse the execution stack
2833 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2834 fst.current()->nmethods_do(cf);
2835 }
2836 }
2837 }
2838
2839 void JavaThread::metadata_do(void f(Metadata*)) {
2840 if (has_last_Java_frame()) {
2841 // Traverse the execution stack to call f() on the methods in the stack
2842 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2843 fst.current()->metadata_do(f);
2844 }
2845 } else if (is_Compiler_thread()) {
2846 // need to walk ciMetadata in current compile tasks to keep alive.
2847 CompilerThread* ct = (CompilerThread*)this;
2848 if (ct->env() != NULL) {
2849 ct->env()->metadata_do(f);
2850 }
2851 if (ct->task() != NULL) {
2852 ct->task()->metadata_do(f);
2853 }
2854 }
2855 }
2856
2857 // Printing
2858 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2859 switch (_thread_state) {
2860 case _thread_uninitialized: return "_thread_uninitialized";
2861 case _thread_new: return "_thread_new";
2862 case _thread_new_trans: return "_thread_new_trans";
2863 case _thread_in_native: return "_thread_in_native";
2864 case _thread_in_native_trans: return "_thread_in_native_trans";
2865 case _thread_in_vm: return "_thread_in_vm";
2866 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2867 case _thread_in_Java: return "_thread_in_Java";
2868 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2869 case _thread_blocked: return "_thread_blocked";
2870 case _thread_blocked_trans: return "_thread_blocked_trans";
2871 default: return "unknown thread state";
2872 }
2873 }
2874
2875 #ifndef PRODUCT
2876 void JavaThread::print_thread_state_on(outputStream *st) const {
2877 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2878 };
2879 void JavaThread::print_thread_state() const {
2880 print_thread_state_on(tty);
2881 }
2882 #endif // PRODUCT
2883
2884 // Called by Threads::print() for VM_PrintThreads operation
2885 void JavaThread::print_on(outputStream *st) const {
2886 st->print_raw("\"");
2887 st->print_raw(get_thread_name());
2888 st->print_raw("\" ");
2889 oop thread_oop = threadObj();
2890 if (thread_oop != NULL) {
2891 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2892 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2893 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2894 }
2895 Thread::print_on(st);
2896 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2897 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2898 if (thread_oop != NULL) {
2899 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2900 }
2901 #ifndef PRODUCT
2902 print_thread_state_on(st);
2903 _safepoint_state->print_on(st);
2904 #endif // PRODUCT
2905 if (is_Compiler_thread()) {
2906 CompilerThread* ct = (CompilerThread*)this;
2907 if (ct->task() != NULL) {
2908 st->print(" Compiling: ");
2909 ct->task()->print(st, NULL, true, false);
2910 } else {
2911 st->print(" No compile task");
2912 }
2913 st->cr();
2914 }
2915 }
2916
2917 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2918 st->print("%s", get_thread_name_string(buf, buflen));
2919 }
2920
2921 // Called by fatal error handler. The difference between this and
2922 // JavaThread::print() is that we can't grab lock or allocate memory.
2923 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2924 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2925 oop thread_obj = threadObj();
2926 if (thread_obj != NULL) {
2927 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2928 }
2929 st->print(" [");
2930 st->print("%s", _get_thread_state_name(_thread_state));
2931 if (osthread()) {
2932 st->print(", id=%d", osthread()->thread_id());
2933 }
2934 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2935 p2i(stack_end()), p2i(stack_base()));
2936 st->print("]");
2937 return;
2938 }
2939
2940 // Verification
2941
2942 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2943
2944 void JavaThread::verify() {
2945 // Verify oops in the thread.
2946 oops_do(&VerifyOopClosure::verify_oop, NULL);
2947
2948 // Verify the stack frames.
2949 frames_do(frame_verify);
2950 }
2951
2952 // CR 6300358 (sub-CR 2137150)
2953 // Most callers of this method assume that it can't return NULL but a
2954 // thread may not have a name whilst it is in the process of attaching to
2955 // the VM - see CR 6412693, and there are places where a JavaThread can be
2956 // seen prior to having it's threadObj set (eg JNI attaching threads and
2957 // if vm exit occurs during initialization). These cases can all be accounted
2958 // for such that this method never returns NULL.
2959 const char* JavaThread::get_thread_name() const {
2960 #ifdef ASSERT
2961 // early safepoints can hit while current thread does not yet have TLS
2962 if (!SafepointSynchronize::is_at_safepoint()) {
2963 Thread *cur = Thread::current();
2964 if (!(cur->is_Java_thread() && cur == this)) {
2965 // Current JavaThreads are allowed to get their own name without
2966 // the Threads_lock.
2967 assert_locked_or_safepoint(Threads_lock);
2968 }
2969 }
2970 #endif // ASSERT
2971 return get_thread_name_string();
2972 }
2973
2974 // Returns a non-NULL representation of this thread's name, or a suitable
2975 // descriptive string if there is no set name
2976 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2977 const char* name_str;
2978 oop thread_obj = threadObj();
2979 if (thread_obj != NULL) {
2980 oop name = java_lang_Thread::name(thread_obj);
2981 if (name != NULL) {
2982 if (buf == NULL) {
2983 name_str = java_lang_String::as_utf8_string(name);
2984 } else {
2985 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2986 }
2987 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2988 name_str = "<no-name - thread is attaching>";
2989 } else {
2990 name_str = Thread::name();
2991 }
2992 } else {
2993 name_str = Thread::name();
2994 }
2995 assert(name_str != NULL, "unexpected NULL thread name");
2996 return name_str;
2997 }
2998
2999
3000 const char* JavaThread::get_threadgroup_name() const {
3001 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3002 oop thread_obj = threadObj();
3003 if (thread_obj != NULL) {
3004 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3005 if (thread_group != NULL) {
3006 // ThreadGroup.name can be null
3007 return java_lang_ThreadGroup::name(thread_group);
3008 }
3009 }
3010 return NULL;
3011 }
3012
3013 const char* JavaThread::get_parent_name() const {
3014 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3015 oop thread_obj = threadObj();
3016 if (thread_obj != NULL) {
3017 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3018 if (thread_group != NULL) {
3019 oop parent = java_lang_ThreadGroup::parent(thread_group);
3020 if (parent != NULL) {
3021 // ThreadGroup.name can be null
3022 return java_lang_ThreadGroup::name(parent);
3023 }
3024 }
3025 }
3026 return NULL;
3027 }
3028
3029 ThreadPriority JavaThread::java_priority() const {
3030 oop thr_oop = threadObj();
3031 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3032 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3033 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3034 return priority;
3035 }
3036
3037 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3038
3039 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3040 // Link Java Thread object <-> C++ Thread
3041
3042 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3043 // and put it into a new Handle. The Handle "thread_oop" can then
3044 // be used to pass the C++ thread object to other methods.
3045
3046 // Set the Java level thread object (jthread) field of the
3047 // new thread (a JavaThread *) to C++ thread object using the
3048 // "thread_oop" handle.
3049
3050 // Set the thread field (a JavaThread *) of the
3051 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3052
3053 Handle thread_oop(Thread::current(),
3054 JNIHandles::resolve_non_null(jni_thread));
3055 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3056 "must be initialized");
3057 set_threadObj(thread_oop());
3058 java_lang_Thread::set_thread(thread_oop(), this);
3059
3060 if (prio == NoPriority) {
3061 prio = java_lang_Thread::priority(thread_oop());
3062 assert(prio != NoPriority, "A valid priority should be present");
3063 }
3064
3065 // Push the Java priority down to the native thread; needs Threads_lock
3066 Thread::set_priority(this, prio);
3067
3068 prepare_ext();
3069
3070 // Add the new thread to the Threads list and set it in motion.
3071 // We must have threads lock in order to call Threads::add.
3072 // It is crucial that we do not block before the thread is
3073 // added to the Threads list for if a GC happens, then the java_thread oop
3074 // will not be visited by GC.
3075 Threads::add(this);
3076 }
3077
3078 oop JavaThread::current_park_blocker() {
3079 // Support for JSR-166 locks
3080 oop thread_oop = threadObj();
3081 if (thread_oop != NULL &&
3082 JDK_Version::current().supports_thread_park_blocker()) {
3083 return java_lang_Thread::park_blocker(thread_oop);
3084 }
3085 return NULL;
3086 }
3087
3088
3089 void JavaThread::print_stack_on(outputStream* st) {
3090 if (!has_last_Java_frame()) return;
3091 ResourceMark rm;
3092 HandleMark hm;
3093
3094 RegisterMap reg_map(this);
3095 vframe* start_vf = last_java_vframe(®_map);
3096 int count = 0;
3097 for (vframe* f = start_vf; f; f = f->sender()) {
3098 if (f->is_java_frame()) {
3099 javaVFrame* jvf = javaVFrame::cast(f);
3100 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3101
3102 // Print out lock information
3103 if (JavaMonitorsInStackTrace) {
3104 jvf->print_lock_info_on(st, count);
3105 }
3106 } else {
3107 // Ignore non-Java frames
3108 }
3109
3110 // Bail-out case for too deep stacks
3111 count++;
3112 if (MaxJavaStackTraceDepth == count) return;
3113 }
3114 }
3115
3116
3117 // JVMTI PopFrame support
3118 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3119 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3120 if (in_bytes(size_in_bytes) != 0) {
3121 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3122 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3123 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3124 }
3125 }
3126
3127 void* JavaThread::popframe_preserved_args() {
3128 return _popframe_preserved_args;
3129 }
3130
3131 ByteSize JavaThread::popframe_preserved_args_size() {
3132 return in_ByteSize(_popframe_preserved_args_size);
3133 }
3134
3135 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3136 int sz = in_bytes(popframe_preserved_args_size());
3137 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3138 return in_WordSize(sz / wordSize);
3139 }
3140
3141 void JavaThread::popframe_free_preserved_args() {
3142 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3143 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3144 _popframe_preserved_args = NULL;
3145 _popframe_preserved_args_size = 0;
3146 }
3147
3148 #ifndef PRODUCT
3149
3150 void JavaThread::trace_frames() {
3151 tty->print_cr("[Describe stack]");
3152 int frame_no = 1;
3153 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3154 tty->print(" %d. ", frame_no++);
3155 fst.current()->print_value_on(tty, this);
3156 tty->cr();
3157 }
3158 }
3159
3160 class PrintAndVerifyOopClosure: public OopClosure {
3161 protected:
3162 template <class T> inline void do_oop_work(T* p) {
3163 oop obj = oopDesc::load_decode_heap_oop(p);
3164 if (obj == NULL) return;
3165 tty->print(INTPTR_FORMAT ": ", p2i(p));
3166 if (obj->is_oop_or_null()) {
3167 if (obj->is_objArray()) {
3168 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3169 } else {
3170 obj->print();
3171 }
3172 } else {
3173 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3174 }
3175 tty->cr();
3176 }
3177 public:
3178 virtual void do_oop(oop* p) { do_oop_work(p); }
3179 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3180 };
3181
3182
3183 static void oops_print(frame* f, const RegisterMap *map) {
3184 PrintAndVerifyOopClosure print;
3185 f->print_value();
3186 f->oops_do(&print, NULL, (RegisterMap*)map);
3187 }
3188
3189 // Print our all the locations that contain oops and whether they are
3190 // valid or not. This useful when trying to find the oldest frame
3191 // where an oop has gone bad since the frame walk is from youngest to
3192 // oldest.
3193 void JavaThread::trace_oops() {
3194 tty->print_cr("[Trace oops]");
3195 frames_do(oops_print);
3196 }
3197
3198
3199 #ifdef ASSERT
3200 // Print or validate the layout of stack frames
3201 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3202 ResourceMark rm;
3203 PRESERVE_EXCEPTION_MARK;
3204 FrameValues values;
3205 int frame_no = 0;
3206 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3207 fst.current()->describe(values, ++frame_no);
3208 if (depth == frame_no) break;
3209 }
3210 if (validate_only) {
3211 values.validate();
3212 } else {
3213 tty->print_cr("[Describe stack layout]");
3214 values.print(this);
3215 }
3216 }
3217 #endif
3218
3219 void JavaThread::trace_stack_from(vframe* start_vf) {
3220 ResourceMark rm;
3221 int vframe_no = 1;
3222 for (vframe* f = start_vf; f; f = f->sender()) {
3223 if (f->is_java_frame()) {
3224 javaVFrame::cast(f)->print_activation(vframe_no++);
3225 } else {
3226 f->print();
3227 }
3228 if (vframe_no > StackPrintLimit) {
3229 tty->print_cr("...<more frames>...");
3230 return;
3231 }
3232 }
3233 }
3234
3235
3236 void JavaThread::trace_stack() {
3237 if (!has_last_Java_frame()) return;
3238 ResourceMark rm;
3239 HandleMark hm;
3240 RegisterMap reg_map(this);
3241 trace_stack_from(last_java_vframe(®_map));
3242 }
3243
3244
3245 #endif // PRODUCT
3246
3247
3248 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3249 assert(reg_map != NULL, "a map must be given");
3250 frame f = last_frame();
3251 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3252 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3253 }
3254 return NULL;
3255 }
3256
3257
3258 Klass* JavaThread::security_get_caller_class(int depth) {
3259 vframeStream vfst(this);
3260 vfst.security_get_caller_frame(depth);
3261 if (!vfst.at_end()) {
3262 return vfst.method()->method_holder();
3263 }
3264 return NULL;
3265 }
3266
3267 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3268 assert(thread->is_Compiler_thread(), "must be compiler thread");
3269 CompileBroker::compiler_thread_loop();
3270 }
3271
3272 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3273 NMethodSweeper::sweeper_loop();
3274 }
3275
3276 // Create a CompilerThread
3277 CompilerThread::CompilerThread(CompileQueue* queue,
3278 CompilerCounters* counters)
3279 : JavaThread(&compiler_thread_entry) {
3280 _env = NULL;
3281 _log = NULL;
3282 _task = NULL;
3283 _queue = queue;
3284 _counters = counters;
3285 _buffer_blob = NULL;
3286 _compiler = NULL;
3287
3288 #ifndef PRODUCT
3289 _ideal_graph_printer = NULL;
3290 #endif
3291 }
3292
3293 bool CompilerThread::can_call_java() const {
3294 return _compiler != NULL && _compiler->is_jvmci();
3295 }
3296
3297 // Create sweeper thread
3298 CodeCacheSweeperThread::CodeCacheSweeperThread()
3299 : JavaThread(&sweeper_thread_entry) {
3300 _scanned_compiled_method = NULL;
3301 }
3302
3303 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3304 JavaThread::oops_do(f, cf);
3305 if (_scanned_compiled_method != NULL && cf != NULL) {
3306 // Safepoints can occur when the sweeper is scanning an nmethod so
3307 // process it here to make sure it isn't unloaded in the middle of
3308 // a scan.
3309 cf->do_code_blob(_scanned_compiled_method);
3310 }
3311 }
3312
3313 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3314 JavaThread::nmethods_do(cf);
3315 if (_scanned_compiled_method != NULL && cf != NULL) {
3316 // Safepoints can occur when the sweeper is scanning an nmethod so
3317 // process it here to make sure it isn't unloaded in the middle of
3318 // a scan.
3319 cf->do_code_blob(_scanned_compiled_method);
3320 }
3321 }
3322
3323
3324 // ======= Threads ========
3325
3326 // The Threads class links together all active threads, and provides
3327 // operations over all threads. It is protected by its own Mutex
3328 // lock, which is also used in other contexts to protect thread
3329 // operations from having the thread being operated on from exiting
3330 // and going away unexpectedly (e.g., safepoint synchronization)
3331
3332 JavaThread* Threads::_thread_list = NULL;
3333 int Threads::_number_of_threads = 0;
3334 int Threads::_number_of_non_daemon_threads = 0;
3335 int Threads::_return_code = 0;
3336 int Threads::_thread_claim_parity = 0;
3337 size_t JavaThread::_stack_size_at_create = 0;
3338 #ifdef ASSERT
3339 bool Threads::_vm_complete = false;
3340 #endif
3341
3342 // All JavaThreads
3343 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3344
3345 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3346 void Threads::threads_do(ThreadClosure* tc) {
3347 assert_locked_or_safepoint(Threads_lock);
3348 // ALL_JAVA_THREADS iterates through all JavaThreads
3349 ALL_JAVA_THREADS(p) {
3350 tc->do_thread(p);
3351 }
3352 // Someday we could have a table or list of all non-JavaThreads.
3353 // For now, just manually iterate through them.
3354 tc->do_thread(VMThread::vm_thread());
3355 GC::gc()->heap()->gc_threads_do(tc);
3356 WatcherThread *wt = WatcherThread::watcher_thread();
3357 // Strictly speaking, the following NULL check isn't sufficient to make sure
3358 // the data for WatcherThread is still valid upon being examined. However,
3359 // considering that WatchThread terminates when the VM is on the way to
3360 // exit at safepoint, the chance of the above is extremely small. The right
3361 // way to prevent termination of WatcherThread would be to acquire
3362 // Terminator_lock, but we can't do that without violating the lock rank
3363 // checking in some cases.
3364 if (wt != NULL) {
3365 tc->do_thread(wt);
3366 }
3367
3368 // If CompilerThreads ever become non-JavaThreads, add them here
3369 }
3370
3371 // The system initialization in the library has three phases.
3372 //
3373 // Phase 1: java.lang.System class initialization
3374 // java.lang.System is a primordial class loaded and initialized
3375 // by the VM early during startup. java.lang.System.<clinit>
3376 // only does registerNatives and keeps the rest of the class
3377 // initialization work later until thread initialization completes.
3378 //
3379 // System.initPhase1 initializes the system properties, the static
3380 // fields in, out, and err. Set up java signal handlers, OS-specific
3381 // system settings, and thread group of the main thread.
3382 static void call_initPhase1(TRAPS) {
3383 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3384 instanceKlassHandle klass (THREAD, k);
3385
3386 JavaValue result(T_VOID);
3387 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3388 vmSymbols::void_method_signature(), CHECK);
3389 }
3390
3391 // Phase 2. Module system initialization
3392 // This will initialize the module system. Only java.base classes
3393 // can be loaded until phase 2 completes.
3394 //
3395 // Call System.initPhase2 after the compiler initialization and jsr292
3396 // classes get initialized because module initialization runs a lot of java
3397 // code, that for performance reasons, should be compiled. Also, this will
3398 // enable the startup code to use lambda and other language features in this
3399 // phase and onward.
3400 //
3401 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3402 static void call_initPhase2(TRAPS) {
3403 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3404
3405 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3406 instanceKlassHandle klass (THREAD, k);
3407
3408 JavaValue result(T_VOID);
3409 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3410 vmSymbols::void_method_signature(), CHECK);
3411 universe_post_module_init();
3412 }
3413
3414 // Phase 3. final setup - set security manager, system class loader and TCCL
3415 //
3416 // This will instantiate and set the security manager, set the system class
3417 // loader as well as the thread context class loader. The security manager
3418 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3419 // other modules or the application's classpath.
3420 static void call_initPhase3(TRAPS) {
3421 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3422 instanceKlassHandle klass (THREAD, k);
3423
3424 JavaValue result(T_VOID);
3425 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3426 vmSymbols::void_method_signature(), CHECK);
3427 }
3428
3429 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3430 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3431
3432 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3433 create_vm_init_libraries();
3434 }
3435
3436 initialize_class(vmSymbols::java_lang_String(), CHECK);
3437
3438 // Inject CompactStrings value after the static initializers for String ran.
3439 java_lang_String::set_compact_strings(CompactStrings);
3440
3441 // Initialize java_lang.System (needed before creating the thread)
3442 initialize_class(vmSymbols::java_lang_System(), CHECK);
3443 // The VM creates & returns objects of this class. Make sure it's initialized.
3444 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3445 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3446 Handle thread_group = create_initial_thread_group(CHECK);
3447 Universe::set_main_thread_group(thread_group());
3448 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3449 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3450 main_thread->set_threadObj(thread_object);
3451 // Set thread status to running since main thread has
3452 // been started and running.
3453 java_lang_Thread::set_thread_status(thread_object,
3454 java_lang_Thread::RUNNABLE);
3455
3456 // The VM creates objects of this class.
3457 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3458
3459 // The VM preresolves methods to these classes. Make sure that they get initialized
3460 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3461 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3462
3463 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3464 call_initPhase1(CHECK);
3465
3466 // get the Java runtime name after java.lang.System is initialized
3467 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3468 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3469
3470 // an instance of OutOfMemory exception has been allocated earlier
3471 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3472 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3473 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3474 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3475 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3476 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3477 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3478 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3479 }
3480
3481 void Threads::initialize_jsr292_core_classes(TRAPS) {
3482 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3483
3484 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3485 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3486 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3487 }
3488
3489 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3490 extern void JDK_Version_init();
3491
3492 // Preinitialize version info.
3493 VM_Version::early_initialize();
3494
3495 // Check version
3496 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3497
3498 // Initialize library-based TLS
3499 ThreadLocalStorage::init();
3500
3501 // Initialize the output stream module
3502 ostream_init();
3503
3504 // Process java launcher properties.
3505 Arguments::process_sun_java_launcher_properties(args);
3506
3507 // Initialize the os module
3508 os::init();
3509
3510 // Record VM creation timing statistics
3511 TraceVmCreationTime create_vm_timer;
3512 create_vm_timer.start();
3513
3514 // Initialize system properties.
3515 Arguments::init_system_properties();
3516
3517 // So that JDK version can be used as a discriminator when parsing arguments
3518 JDK_Version_init();
3519
3520 // Update/Initialize System properties after JDK version number is known
3521 Arguments::init_version_specific_system_properties();
3522
3523 // Make sure to initialize log configuration *before* parsing arguments
3524 LogConfiguration::initialize(create_vm_timer.begin_time());
3525
3526 // Parse arguments
3527 jint parse_result = Arguments::parse(args);
3528 if (parse_result != JNI_OK) return parse_result;
3529
3530 os::init_before_ergo();
3531
3532 Arguments::select_gc();
3533 jint gc_result = GC::initialize();
3534 if (gc_result != JNI_OK) {
3535 return gc_result;
3536 }
3537
3538 jint ergo_result = Arguments::apply_ergo();
3539 if (ergo_result != JNI_OK) return ergo_result;
3540
3541 // Final check of all ranges after ergonomics which may change values.
3542 if (!CommandLineFlagRangeList::check_ranges()) {
3543 return JNI_EINVAL;
3544 }
3545
3546 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3547 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3548 if (!constraint_result) {
3549 return JNI_EINVAL;
3550 }
3551
3552 CommandLineFlagWriteableList::mark_startup();
3553
3554 if (PauseAtStartup) {
3555 os::pause();
3556 }
3557
3558 HOTSPOT_VM_INIT_BEGIN();
3559
3560 // Timing (must come after argument parsing)
3561 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3562
3563 // Initialize the os module after parsing the args
3564 jint os_init_2_result = os::init_2();
3565 if (os_init_2_result != JNI_OK) return os_init_2_result;
3566
3567 jint adjust_after_os_result = Arguments::adjust_after_os();
3568 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3569
3570 // Initialize output stream logging
3571 ostream_init_log();
3572
3573 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3574 // Must be before create_vm_init_agents()
3575 if (Arguments::init_libraries_at_startup()) {
3576 convert_vm_init_libraries_to_agents();
3577 }
3578
3579 // Launch -agentlib/-agentpath and converted -Xrun agents
3580 if (Arguments::init_agents_at_startup()) {
3581 create_vm_init_agents();
3582 }
3583
3584 // Initialize Threads state
3585 _thread_list = NULL;
3586 _number_of_threads = 0;
3587 _number_of_non_daemon_threads = 0;
3588
3589 // Initialize global data structures and create system classes in heap
3590 vm_init_globals();
3591
3592 #if INCLUDE_JVMCI
3593 if (JVMCICounterSize > 0) {
3594 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3595 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3596 } else {
3597 JavaThread::_jvmci_old_thread_counters = NULL;
3598 }
3599 #endif // INCLUDE_JVMCI
3600
3601 // Attach the main thread to this os thread
3602 JavaThread* main_thread = new JavaThread();
3603 main_thread->set_thread_state(_thread_in_vm);
3604 main_thread->initialize_thread_current();
3605 // must do this before set_active_handles
3606 main_thread->record_stack_base_and_size();
3607 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3608
3609 if (!main_thread->set_as_starting_thread()) {
3610 vm_shutdown_during_initialization(
3611 "Failed necessary internal allocation. Out of swap space");
3612 delete main_thread;
3613 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3614 return JNI_ENOMEM;
3615 }
3616
3617 // Enable guard page *after* os::create_main_thread(), otherwise it would
3618 // crash Linux VM, see notes in os_linux.cpp.
3619 main_thread->create_stack_guard_pages();
3620
3621 // Initialize Java-Level synchronization subsystem
3622 ObjectMonitor::Initialize();
3623
3624 // Initialize global modules
3625 jint status = init_globals();
3626 if (status != JNI_OK) {
3627 delete main_thread;
3628 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3629 return status;
3630 }
3631
3632 if (TRACE_INITIALIZE() != JNI_OK) {
3633 vm_exit_during_initialization("Failed to initialize tracing backend");
3634 }
3635
3636 // Should be done after the heap is fully created
3637 main_thread->cache_global_variables();
3638
3639 HandleMark hm;
3640
3641 { MutexLocker mu(Threads_lock);
3642 Threads::add(main_thread);
3643 }
3644
3645 // Any JVMTI raw monitors entered in onload will transition into
3646 // real raw monitor. VM is setup enough here for raw monitor enter.
3647 JvmtiExport::transition_pending_onload_raw_monitors();
3648
3649 // Create the VMThread
3650 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3651
3652 VMThread::create();
3653 Thread* vmthread = VMThread::vm_thread();
3654
3655 if (!os::create_thread(vmthread, os::vm_thread)) {
3656 vm_exit_during_initialization("Cannot create VM thread. "
3657 "Out of system resources.");
3658 }
3659
3660 // Wait for the VM thread to become ready, and VMThread::run to initialize
3661 // Monitors can have spurious returns, must always check another state flag
3662 {
3663 MutexLocker ml(Notify_lock);
3664 os::start_thread(vmthread);
3665 while (vmthread->active_handles() == NULL) {
3666 Notify_lock->wait();
3667 }
3668 }
3669 }
3670
3671 assert(Universe::is_fully_initialized(), "not initialized");
3672 if (VerifyDuringStartup) {
3673 // Make sure we're starting with a clean slate.
3674 VM_Verify verify_op;
3675 VMThread::execute(&verify_op);
3676 }
3677
3678 Thread* THREAD = Thread::current();
3679
3680 // At this point, the Universe is initialized, but we have not executed
3681 // any byte code. Now is a good time (the only time) to dump out the
3682 // internal state of the JVM for sharing.
3683 if (DumpSharedSpaces) {
3684 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3685 ShouldNotReachHere();
3686 }
3687
3688 // Always call even when there are not JVMTI environments yet, since environments
3689 // may be attached late and JVMTI must track phases of VM execution
3690 JvmtiExport::enter_early_start_phase();
3691
3692 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3693 JvmtiExport::post_early_vm_start();
3694
3695 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3696
3697 // We need this for ClassDataSharing - the initial vm.info property is set
3698 // with the default value of CDS "sharing" which may be reset through
3699 // command line options.
3700 reset_vm_info_property(CHECK_JNI_ERR);
3701
3702 quicken_jni_functions();
3703
3704 // No more stub generation allowed after that point.
3705 StubCodeDesc::freeze();
3706
3707 // Set flag that basic initialization has completed. Used by exceptions and various
3708 // debug stuff, that does not work until all basic classes have been initialized.
3709 set_init_completed();
3710
3711 LogConfiguration::post_initialize();
3712 Metaspace::post_initialize();
3713
3714 HOTSPOT_VM_INIT_END();
3715
3716 // record VM initialization completion time
3717 #if INCLUDE_MANAGEMENT
3718 Management::record_vm_init_completed();
3719 #endif // INCLUDE_MANAGEMENT
3720
3721 // Signal Dispatcher needs to be started before VMInit event is posted
3722 os::signal_init();
3723
3724 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3725 if (!DisableAttachMechanism) {
3726 AttachListener::vm_start();
3727 if (StartAttachListener || AttachListener::init_at_startup()) {
3728 AttachListener::init();
3729 }
3730 }
3731
3732 // Launch -Xrun agents
3733 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3734 // back-end can launch with -Xdebug -Xrunjdwp.
3735 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3736 create_vm_init_libraries();
3737 }
3738
3739 if (CleanChunkPoolAsync) {
3740 Chunk::start_chunk_pool_cleaner_task();
3741 }
3742
3743 // initialize compiler(s)
3744 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3745 CompileBroker::compilation_init(CHECK_JNI_ERR);
3746 #endif
3747
3748 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3749 // It is done after compilers are initialized, because otherwise compilations of
3750 // signature polymorphic MH intrinsics can be missed
3751 // (see SystemDictionary::find_method_handle_intrinsic).
3752 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3753
3754 // This will initialize the module system. Only java.base classes can be
3755 // loaded until phase 2 completes
3756 call_initPhase2(CHECK_JNI_ERR);
3757
3758 // Always call even when there are not JVMTI environments yet, since environments
3759 // may be attached late and JVMTI must track phases of VM execution
3760 JvmtiExport::enter_start_phase();
3761
3762 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3763 JvmtiExport::post_vm_start();
3764
3765 // Final system initialization including security manager and system class loader
3766 call_initPhase3(CHECK_JNI_ERR);
3767
3768 // cache the system class loader
3769 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3770
3771 #if INCLUDE_JVMCI
3772 if (EnableJVMCI) {
3773 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3774 // The JVMCI Java initialization code will read this flag and
3775 // do the printing if it's set.
3776 bool init = JVMCIPrintProperties;
3777
3778 if (!init) {
3779 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3780 // compilations via JVMCI will not actually block until JVMCI is initialized.
3781 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3782 }
3783
3784 if (init) {
3785 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3786 }
3787 }
3788 #endif
3789
3790 // Always call even when there are not JVMTI environments yet, since environments
3791 // may be attached late and JVMTI must track phases of VM execution
3792 JvmtiExport::enter_live_phase();
3793
3794 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3795 JvmtiExport::post_vm_initialized();
3796
3797 if (TRACE_START() != JNI_OK) {
3798 vm_exit_during_initialization("Failed to start tracing backend.");
3799 }
3800
3801 #if INCLUDE_MANAGEMENT
3802 Management::initialize(THREAD);
3803
3804 if (HAS_PENDING_EXCEPTION) {
3805 // management agent fails to start possibly due to
3806 // configuration problem and is responsible for printing
3807 // stack trace if appropriate. Simply exit VM.
3808 vm_exit(1);
3809 }
3810 #endif // INCLUDE_MANAGEMENT
3811
3812 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3813 if (MemProfiling) MemProfiler::engage();
3814 StatSampler::engage();
3815 if (CheckJNICalls) JniPeriodicChecker::engage();
3816
3817 BiasedLocking::init();
3818
3819 #if INCLUDE_RTM_OPT
3820 RTMLockingCounters::init();
3821 #endif
3822
3823 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3824 call_postVMInitHook(THREAD);
3825 // The Java side of PostVMInitHook.run must deal with all
3826 // exceptions and provide means of diagnosis.
3827 if (HAS_PENDING_EXCEPTION) {
3828 CLEAR_PENDING_EXCEPTION;
3829 }
3830 }
3831
3832 {
3833 MutexLocker ml(PeriodicTask_lock);
3834 // Make sure the WatcherThread can be started by WatcherThread::start()
3835 // or by dynamic enrollment.
3836 WatcherThread::make_startable();
3837 // Start up the WatcherThread if there are any periodic tasks
3838 // NOTE: All PeriodicTasks should be registered by now. If they
3839 // aren't, late joiners might appear to start slowly (we might
3840 // take a while to process their first tick).
3841 if (PeriodicTask::num_tasks() > 0) {
3842 WatcherThread::start();
3843 }
3844 }
3845
3846 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3847
3848 create_vm_timer.end();
3849 #ifdef ASSERT
3850 _vm_complete = true;
3851 #endif
3852 return JNI_OK;
3853 }
3854
3855 // type for the Agent_OnLoad and JVM_OnLoad entry points
3856 extern "C" {
3857 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3858 }
3859 // Find a command line agent library and return its entry point for
3860 // -agentlib: -agentpath: -Xrun
3861 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3862 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3863 const char *on_load_symbols[],
3864 size_t num_symbol_entries) {
3865 OnLoadEntry_t on_load_entry = NULL;
3866 void *library = NULL;
3867
3868 if (!agent->valid()) {
3869 char buffer[JVM_MAXPATHLEN];
3870 char ebuf[1024] = "";
3871 const char *name = agent->name();
3872 const char *msg = "Could not find agent library ";
3873
3874 // First check to see if agent is statically linked into executable
3875 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3876 library = agent->os_lib();
3877 } else if (agent->is_absolute_path()) {
3878 library = os::dll_load(name, ebuf, sizeof ebuf);
3879 if (library == NULL) {
3880 const char *sub_msg = " in absolute path, with error: ";
3881 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3882 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3883 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3884 // If we can't find the agent, exit.
3885 vm_exit_during_initialization(buf, NULL);
3886 FREE_C_HEAP_ARRAY(char, buf);
3887 }
3888 } else {
3889 // Try to load the agent from the standard dll directory
3890 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3891 name)) {
3892 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3893 }
3894 if (library == NULL) { // Try the local directory
3895 char ns[1] = {0};
3896 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3897 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3898 }
3899 if (library == NULL) {
3900 const char *sub_msg = " on the library path, with error: ";
3901 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3902 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3903 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3904 // If we can't find the agent, exit.
3905 vm_exit_during_initialization(buf, NULL);
3906 FREE_C_HEAP_ARRAY(char, buf);
3907 }
3908 }
3909 }
3910 agent->set_os_lib(library);
3911 agent->set_valid();
3912 }
3913
3914 // Find the OnLoad function.
3915 on_load_entry =
3916 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3917 false,
3918 on_load_symbols,
3919 num_symbol_entries));
3920 return on_load_entry;
3921 }
3922
3923 // Find the JVM_OnLoad entry point
3924 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3925 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3926 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3927 }
3928
3929 // Find the Agent_OnLoad entry point
3930 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3931 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3932 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3933 }
3934
3935 // For backwards compatibility with -Xrun
3936 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3937 // treated like -agentpath:
3938 // Must be called before agent libraries are created
3939 void Threads::convert_vm_init_libraries_to_agents() {
3940 AgentLibrary* agent;
3941 AgentLibrary* next;
3942
3943 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3944 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3945 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3946
3947 // If there is an JVM_OnLoad function it will get called later,
3948 // otherwise see if there is an Agent_OnLoad
3949 if (on_load_entry == NULL) {
3950 on_load_entry = lookup_agent_on_load(agent);
3951 if (on_load_entry != NULL) {
3952 // switch it to the agent list -- so that Agent_OnLoad will be called,
3953 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3954 Arguments::convert_library_to_agent(agent);
3955 } else {
3956 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3957 }
3958 }
3959 }
3960 }
3961
3962 // Create agents for -agentlib: -agentpath: and converted -Xrun
3963 // Invokes Agent_OnLoad
3964 // Called very early -- before JavaThreads exist
3965 void Threads::create_vm_init_agents() {
3966 extern struct JavaVM_ main_vm;
3967 AgentLibrary* agent;
3968
3969 JvmtiExport::enter_onload_phase();
3970
3971 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3972 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3973
3974 if (on_load_entry != NULL) {
3975 // Invoke the Agent_OnLoad function
3976 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3977 if (err != JNI_OK) {
3978 vm_exit_during_initialization("agent library failed to init", agent->name());
3979 }
3980 } else {
3981 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3982 }
3983 }
3984 JvmtiExport::enter_primordial_phase();
3985 }
3986
3987 extern "C" {
3988 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3989 }
3990
3991 void Threads::shutdown_vm_agents() {
3992 // Send any Agent_OnUnload notifications
3993 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3994 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3995 extern struct JavaVM_ main_vm;
3996 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3997
3998 // Find the Agent_OnUnload function.
3999 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4000 os::find_agent_function(agent,
4001 false,
4002 on_unload_symbols,
4003 num_symbol_entries));
4004
4005 // Invoke the Agent_OnUnload function
4006 if (unload_entry != NULL) {
4007 JavaThread* thread = JavaThread::current();
4008 ThreadToNativeFromVM ttn(thread);
4009 HandleMark hm(thread);
4010 (*unload_entry)(&main_vm);
4011 }
4012 }
4013 }
4014
4015 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4016 // Invokes JVM_OnLoad
4017 void Threads::create_vm_init_libraries() {
4018 extern struct JavaVM_ main_vm;
4019 AgentLibrary* agent;
4020
4021 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4022 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4023
4024 if (on_load_entry != NULL) {
4025 // Invoke the JVM_OnLoad function
4026 JavaThread* thread = JavaThread::current();
4027 ThreadToNativeFromVM ttn(thread);
4028 HandleMark hm(thread);
4029 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4030 if (err != JNI_OK) {
4031 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4032 }
4033 } else {
4034 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4035 }
4036 }
4037 }
4038
4039 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4040 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4041
4042 JavaThread* java_thread = NULL;
4043 // Sequential search for now. Need to do better optimization later.
4044 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4045 oop tobj = thread->threadObj();
4046 if (!thread->is_exiting() &&
4047 tobj != NULL &&
4048 java_tid == java_lang_Thread::thread_id(tobj)) {
4049 java_thread = thread;
4050 break;
4051 }
4052 }
4053 return java_thread;
4054 }
4055
4056
4057 // Last thread running calls java.lang.Shutdown.shutdown()
4058 void JavaThread::invoke_shutdown_hooks() {
4059 HandleMark hm(this);
4060
4061 // We could get here with a pending exception, if so clear it now.
4062 if (this->has_pending_exception()) {
4063 this->clear_pending_exception();
4064 }
4065
4066 EXCEPTION_MARK;
4067 Klass* k =
4068 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4069 THREAD);
4070 if (k != NULL) {
4071 // SystemDictionary::resolve_or_null will return null if there was
4072 // an exception. If we cannot load the Shutdown class, just don't
4073 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4074 // and finalizers (if runFinalizersOnExit is set) won't be run.
4075 // Note that if a shutdown hook was registered or runFinalizersOnExit
4076 // was called, the Shutdown class would have already been loaded
4077 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4078 instanceKlassHandle shutdown_klass (THREAD, k);
4079 JavaValue result(T_VOID);
4080 JavaCalls::call_static(&result,
4081 shutdown_klass,
4082 vmSymbols::shutdown_method_name(),
4083 vmSymbols::void_method_signature(),
4084 THREAD);
4085 }
4086 CLEAR_PENDING_EXCEPTION;
4087 }
4088
4089 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4090 // the program falls off the end of main(). Another VM exit path is through
4091 // vm_exit() when the program calls System.exit() to return a value or when
4092 // there is a serious error in VM. The two shutdown paths are not exactly
4093 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4094 // and VM_Exit op at VM level.
4095 //
4096 // Shutdown sequence:
4097 // + Shutdown native memory tracking if it is on
4098 // + Wait until we are the last non-daemon thread to execute
4099 // <-- every thing is still working at this moment -->
4100 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4101 // shutdown hooks, run finalizers if finalization-on-exit
4102 // + Call before_exit(), prepare for VM exit
4103 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4104 // currently the only user of this mechanism is File.deleteOnExit())
4105 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4106 // post thread end and vm death events to JVMTI,
4107 // stop signal thread
4108 // + Call JavaThread::exit(), it will:
4109 // > release JNI handle blocks, remove stack guard pages
4110 // > remove this thread from Threads list
4111 // <-- no more Java code from this thread after this point -->
4112 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4113 // the compiler threads at safepoint
4114 // <-- do not use anything that could get blocked by Safepoint -->
4115 // + Disable tracing at JNI/JVM barriers
4116 // + Set _vm_exited flag for threads that are still running native code
4117 // + Delete this thread
4118 // + Call exit_globals()
4119 // > deletes tty
4120 // > deletes PerfMemory resources
4121 // + Return to caller
4122
4123 bool Threads::destroy_vm() {
4124 JavaThread* thread = JavaThread::current();
4125
4126 #ifdef ASSERT
4127 _vm_complete = false;
4128 #endif
4129 // Wait until we are the last non-daemon thread to execute
4130 { MutexLocker nu(Threads_lock);
4131 while (Threads::number_of_non_daemon_threads() > 1)
4132 // This wait should make safepoint checks, wait without a timeout,
4133 // and wait as a suspend-equivalent condition.
4134 //
4135 // Note: If the FlatProfiler is running and this thread is waiting
4136 // for another non-daemon thread to finish, then the FlatProfiler
4137 // is waiting for the external suspend request on this thread to
4138 // complete. wait_for_ext_suspend_completion() will eventually
4139 // timeout, but that takes time. Making this wait a suspend-
4140 // equivalent condition solves that timeout problem.
4141 //
4142 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4143 Mutex::_as_suspend_equivalent_flag);
4144 }
4145
4146 // Hang forever on exit if we are reporting an error.
4147 if (ShowMessageBoxOnError && is_error_reported()) {
4148 os::infinite_sleep();
4149 }
4150 os::wait_for_keypress_at_exit();
4151
4152 // run Java level shutdown hooks
4153 thread->invoke_shutdown_hooks();
4154
4155 before_exit(thread);
4156
4157 thread->exit(true);
4158
4159 // Stop VM thread.
4160 {
4161 // 4945125 The vm thread comes to a safepoint during exit.
4162 // GC vm_operations can get caught at the safepoint, and the
4163 // heap is unparseable if they are caught. Grab the Heap_lock
4164 // to prevent this. The GC vm_operations will not be able to
4165 // queue until after the vm thread is dead. After this point,
4166 // we'll never emerge out of the safepoint before the VM exits.
4167
4168 MutexLocker ml(Heap_lock);
4169
4170 VMThread::wait_for_vm_thread_exit();
4171 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4172 VMThread::destroy();
4173 }
4174
4175 // clean up ideal graph printers
4176 #if defined(COMPILER2) && !defined(PRODUCT)
4177 IdealGraphPrinter::clean_up();
4178 #endif
4179
4180 // Now, all Java threads are gone except daemon threads. Daemon threads
4181 // running Java code or in VM are stopped by the Safepoint. However,
4182 // daemon threads executing native code are still running. But they
4183 // will be stopped at native=>Java/VM barriers. Note that we can't
4184 // simply kill or suspend them, as it is inherently deadlock-prone.
4185
4186 VM_Exit::set_vm_exited();
4187
4188 notify_vm_shutdown();
4189
4190 delete thread;
4191
4192 #if INCLUDE_JVMCI
4193 if (JVMCICounterSize > 0) {
4194 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4195 }
4196 #endif
4197
4198 // exit_globals() will delete tty
4199 exit_globals();
4200
4201 LogConfiguration::finalize();
4202
4203 return true;
4204 }
4205
4206
4207 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4208 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4209 return is_supported_jni_version(version);
4210 }
4211
4212
4213 jboolean Threads::is_supported_jni_version(jint version) {
4214 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4215 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4216 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4217 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4218 if (version == JNI_VERSION_9) return JNI_TRUE;
4219 return JNI_FALSE;
4220 }
4221
4222
4223 void Threads::add(JavaThread* p, bool force_daemon) {
4224 // The threads lock must be owned at this point
4225 assert_locked_or_safepoint(Threads_lock);
4226
4227 // See the comment for this method in thread.hpp for its purpose and
4228 // why it is called here.
4229 p->initialize_queues();
4230 p->set_next(_thread_list);
4231 _thread_list = p;
4232 _number_of_threads++;
4233 oop threadObj = p->threadObj();
4234 bool daemon = true;
4235 // Bootstrapping problem: threadObj can be null for initial
4236 // JavaThread (or for threads attached via JNI)
4237 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4238 _number_of_non_daemon_threads++;
4239 daemon = false;
4240 }
4241
4242 ThreadService::add_thread(p, daemon);
4243
4244 // Possible GC point.
4245 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4246 }
4247
4248 void Threads::remove(JavaThread* p) {
4249 // Extra scope needed for Thread_lock, so we can check
4250 // that we do not remove thread without safepoint code notice
4251 { MutexLocker ml(Threads_lock);
4252
4253 assert(includes(p), "p must be present");
4254
4255 JavaThread* current = _thread_list;
4256 JavaThread* prev = NULL;
4257
4258 while (current != p) {
4259 prev = current;
4260 current = current->next();
4261 }
4262
4263 if (prev) {
4264 prev->set_next(current->next());
4265 } else {
4266 _thread_list = p->next();
4267 }
4268 _number_of_threads--;
4269 oop threadObj = p->threadObj();
4270 bool daemon = true;
4271 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4272 _number_of_non_daemon_threads--;
4273 daemon = false;
4274
4275 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4276 // on destroy_vm will wake up.
4277 if (number_of_non_daemon_threads() == 1) {
4278 Threads_lock->notify_all();
4279 }
4280 }
4281 ThreadService::remove_thread(p, daemon);
4282
4283 // Make sure that safepoint code disregard this thread. This is needed since
4284 // the thread might mess around with locks after this point. This can cause it
4285 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4286 // of this thread since it is removed from the queue.
4287 p->set_terminated_value();
4288 } // unlock Threads_lock
4289
4290 // Since Events::log uses a lock, we grab it outside the Threads_lock
4291 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4292 }
4293
4294 // Threads_lock must be held when this is called (or must be called during a safepoint)
4295 bool Threads::includes(JavaThread* p) {
4296 assert(Threads_lock->is_locked(), "sanity check");
4297 ALL_JAVA_THREADS(q) {
4298 if (q == p) {
4299 return true;
4300 }
4301 }
4302 return false;
4303 }
4304
4305 // Operations on the Threads list for GC. These are not explicitly locked,
4306 // but the garbage collector must provide a safe context for them to run.
4307 // In particular, these things should never be called when the Threads_lock
4308 // is held by some other thread. (Note: the Safepoint abstraction also
4309 // uses the Threads_lock to guarantee this property. It also makes sure that
4310 // all threads gets blocked when exiting or starting).
4311
4312 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4313 ALL_JAVA_THREADS(p) {
4314 p->oops_do(f, cf);
4315 }
4316 VMThread::vm_thread()->oops_do(f, cf);
4317 }
4318
4319 void Threads::change_thread_claim_parity() {
4320 // Set the new claim parity.
4321 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4322 "Not in range.");
4323 _thread_claim_parity++;
4324 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4325 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4326 "Not in range.");
4327 }
4328
4329 #ifdef ASSERT
4330 void Threads::assert_all_threads_claimed() {
4331 ALL_JAVA_THREADS(p) {
4332 const int thread_parity = p->oops_do_parity();
4333 assert((thread_parity == _thread_claim_parity),
4334 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4335 }
4336 }
4337 #endif // ASSERT
4338
4339 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4340 int cp = Threads::thread_claim_parity();
4341 ALL_JAVA_THREADS(p) {
4342 if (p->claim_oops_do(is_par, cp)) {
4343 p->oops_do(f, cf);
4344 }
4345 }
4346 VMThread* vmt = VMThread::vm_thread();
4347 if (vmt->claim_oops_do(is_par, cp)) {
4348 vmt->oops_do(f, cf);
4349 }
4350 }
4351
4352 void Threads::nmethods_do(CodeBlobClosure* cf) {
4353 ALL_JAVA_THREADS(p) {
4354 // This is used by the code cache sweeper to mark nmethods that are active
4355 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4356 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4357 if(!p->is_Code_cache_sweeper_thread()) {
4358 p->nmethods_do(cf);
4359 }
4360 }
4361 }
4362
4363 void Threads::metadata_do(void f(Metadata*)) {
4364 ALL_JAVA_THREADS(p) {
4365 p->metadata_do(f);
4366 }
4367 }
4368
4369 class ThreadHandlesClosure : public ThreadClosure {
4370 void (*_f)(Metadata*);
4371 public:
4372 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4373 virtual void do_thread(Thread* thread) {
4374 thread->metadata_handles_do(_f);
4375 }
4376 };
4377
4378 void Threads::metadata_handles_do(void f(Metadata*)) {
4379 // Only walk the Handles in Thread.
4380 ThreadHandlesClosure handles_closure(f);
4381 threads_do(&handles_closure);
4382 }
4383
4384 void Threads::deoptimized_wrt_marked_nmethods() {
4385 ALL_JAVA_THREADS(p) {
4386 p->deoptimized_wrt_marked_nmethods();
4387 }
4388 }
4389
4390
4391 // Get count Java threads that are waiting to enter the specified monitor.
4392 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4393 address monitor,
4394 bool doLock) {
4395 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4396 "must grab Threads_lock or be at safepoint");
4397 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4398
4399 int i = 0;
4400 {
4401 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4402 ALL_JAVA_THREADS(p) {
4403 if (!p->can_call_java()) continue;
4404
4405 address pending = (address)p->current_pending_monitor();
4406 if (pending == monitor) { // found a match
4407 if (i < count) result->append(p); // save the first count matches
4408 i++;
4409 }
4410 }
4411 }
4412 return result;
4413 }
4414
4415
4416 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4417 bool doLock) {
4418 assert(doLock ||
4419 Threads_lock->owned_by_self() ||
4420 SafepointSynchronize::is_at_safepoint(),
4421 "must grab Threads_lock or be at safepoint");
4422
4423 // NULL owner means not locked so we can skip the search
4424 if (owner == NULL) return NULL;
4425
4426 {
4427 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4428 ALL_JAVA_THREADS(p) {
4429 // first, see if owner is the address of a Java thread
4430 if (owner == (address)p) return p;
4431 }
4432 }
4433 // Cannot assert on lack of success here since this function may be
4434 // used by code that is trying to report useful problem information
4435 // like deadlock detection.
4436 if (UseHeavyMonitors) return NULL;
4437
4438 // If we didn't find a matching Java thread and we didn't force use of
4439 // heavyweight monitors, then the owner is the stack address of the
4440 // Lock Word in the owning Java thread's stack.
4441 //
4442 JavaThread* the_owner = NULL;
4443 {
4444 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4445 ALL_JAVA_THREADS(q) {
4446 if (q->is_lock_owned(owner)) {
4447 the_owner = q;
4448 break;
4449 }
4450 }
4451 }
4452 // cannot assert on lack of success here; see above comment
4453 return the_owner;
4454 }
4455
4456 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4457 void Threads::print_on(outputStream* st, bool print_stacks,
4458 bool internal_format, bool print_concurrent_locks) {
4459 char buf[32];
4460 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4461
4462 st->print_cr("Full thread dump %s (%s %s):",
4463 Abstract_VM_Version::vm_name(),
4464 Abstract_VM_Version::vm_release(),
4465 Abstract_VM_Version::vm_info_string());
4466 st->cr();
4467
4468 #if INCLUDE_SERVICES
4469 // Dump concurrent locks
4470 ConcurrentLocksDump concurrent_locks;
4471 if (print_concurrent_locks) {
4472 concurrent_locks.dump_at_safepoint();
4473 }
4474 #endif // INCLUDE_SERVICES
4475
4476 ALL_JAVA_THREADS(p) {
4477 ResourceMark rm;
4478 p->print_on(st);
4479 if (print_stacks) {
4480 if (internal_format) {
4481 p->trace_stack();
4482 } else {
4483 p->print_stack_on(st);
4484 }
4485 }
4486 st->cr();
4487 #if INCLUDE_SERVICES
4488 if (print_concurrent_locks) {
4489 concurrent_locks.print_locks_on(p, st);
4490 }
4491 #endif // INCLUDE_SERVICES
4492 }
4493
4494 VMThread::vm_thread()->print_on(st);
4495 st->cr();
4496 GC::gc()->heap()->print_gc_threads_on(st);
4497 WatcherThread* wt = WatcherThread::watcher_thread();
4498 if (wt != NULL) {
4499 wt->print_on(st);
4500 st->cr();
4501 }
4502 st->flush();
4503 }
4504
4505 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4506 int buflen, bool* found_current) {
4507 if (this_thread != NULL) {
4508 bool is_current = (current == this_thread);
4509 *found_current = *found_current || is_current;
4510 st->print("%s", is_current ? "=>" : " ");
4511
4512 st->print(PTR_FORMAT, p2i(this_thread));
4513 st->print(" ");
4514 this_thread->print_on_error(st, buf, buflen);
4515 st->cr();
4516 }
4517 }
4518
4519 class PrintOnErrorClosure : public ThreadClosure {
4520 outputStream* _st;
4521 Thread* _current;
4522 char* _buf;
4523 int _buflen;
4524 bool* _found_current;
4525 public:
4526 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4527 int buflen, bool* found_current) :
4528 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4529
4530 virtual void do_thread(Thread* thread) {
4531 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4532 }
4533 };
4534
4535 // Threads::print_on_error() is called by fatal error handler. It's possible
4536 // that VM is not at safepoint and/or current thread is inside signal handler.
4537 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4538 // memory (even in resource area), it might deadlock the error handler.
4539 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4540 int buflen) {
4541 bool found_current = false;
4542 st->print_cr("Java Threads: ( => current thread )");
4543 ALL_JAVA_THREADS(thread) {
4544 print_on_error(thread, st, current, buf, buflen, &found_current);
4545 }
4546 st->cr();
4547
4548 st->print_cr("Other Threads:");
4549 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4550 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4551
4552 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4553 GC::gc()->heap()->gc_threads_do(&print_closure);
4554
4555 if (!found_current) {
4556 st->cr();
4557 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4558 current->print_on_error(st, buf, buflen);
4559 st->cr();
4560 }
4561 st->cr();
4562 st->print_cr("Threads with active compile tasks:");
4563 print_threads_compiling(st, buf, buflen);
4564 }
4565
4566 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4567 ALL_JAVA_THREADS(thread) {
4568 if (thread->is_Compiler_thread()) {
4569 CompilerThread* ct = (CompilerThread*) thread;
4570 if (ct->task() != NULL) {
4571 thread->print_name_on_error(st, buf, buflen);
4572 ct->task()->print(st, NULL, true, true);
4573 }
4574 }
4575 }
4576 }
4577
4578
4579 // Internal SpinLock and Mutex
4580 // Based on ParkEvent
4581
4582 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4583 //
4584 // We employ SpinLocks _only for low-contention, fixed-length
4585 // short-duration critical sections where we're concerned
4586 // about native mutex_t or HotSpot Mutex:: latency.
4587 // The mux construct provides a spin-then-block mutual exclusion
4588 // mechanism.
4589 //
4590 // Testing has shown that contention on the ListLock guarding gFreeList
4591 // is common. If we implement ListLock as a simple SpinLock it's common
4592 // for the JVM to devolve to yielding with little progress. This is true
4593 // despite the fact that the critical sections protected by ListLock are
4594 // extremely short.
4595 //
4596 // TODO-FIXME: ListLock should be of type SpinLock.
4597 // We should make this a 1st-class type, integrated into the lock
4598 // hierarchy as leaf-locks. Critically, the SpinLock structure
4599 // should have sufficient padding to avoid false-sharing and excessive
4600 // cache-coherency traffic.
4601
4602
4603 typedef volatile int SpinLockT;
4604
4605 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4606 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4607 return; // normal fast-path return
4608 }
4609
4610 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4611 TEVENT(SpinAcquire - ctx);
4612 int ctr = 0;
4613 int Yields = 0;
4614 for (;;) {
4615 while (*adr != 0) {
4616 ++ctr;
4617 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4618 if (Yields > 5) {
4619 os::naked_short_sleep(1);
4620 } else {
4621 os::naked_yield();
4622 ++Yields;
4623 }
4624 } else {
4625 SpinPause();
4626 }
4627 }
4628 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4629 }
4630 }
4631
4632 void Thread::SpinRelease(volatile int * adr) {
4633 assert(*adr != 0, "invariant");
4634 OrderAccess::fence(); // guarantee at least release consistency.
4635 // Roach-motel semantics.
4636 // It's safe if subsequent LDs and STs float "up" into the critical section,
4637 // but prior LDs and STs within the critical section can't be allowed
4638 // to reorder or float past the ST that releases the lock.
4639 // Loads and stores in the critical section - which appear in program
4640 // order before the store that releases the lock - must also appear
4641 // before the store that releases the lock in memory visibility order.
4642 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4643 // the ST of 0 into the lock-word which releases the lock, so fence
4644 // more than covers this on all platforms.
4645 *adr = 0;
4646 }
4647
4648 // muxAcquire and muxRelease:
4649 //
4650 // * muxAcquire and muxRelease support a single-word lock-word construct.
4651 // The LSB of the word is set IFF the lock is held.
4652 // The remainder of the word points to the head of a singly-linked list
4653 // of threads blocked on the lock.
4654 //
4655 // * The current implementation of muxAcquire-muxRelease uses its own
4656 // dedicated Thread._MuxEvent instance. If we're interested in
4657 // minimizing the peak number of extant ParkEvent instances then
4658 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4659 // as certain invariants were satisfied. Specifically, care would need
4660 // to be taken with regards to consuming unpark() "permits".
4661 // A safe rule of thumb is that a thread would never call muxAcquire()
4662 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4663 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4664 // consume an unpark() permit intended for monitorenter, for instance.
4665 // One way around this would be to widen the restricted-range semaphore
4666 // implemented in park(). Another alternative would be to provide
4667 // multiple instances of the PlatformEvent() for each thread. One
4668 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4669 //
4670 // * Usage:
4671 // -- Only as leaf locks
4672 // -- for short-term locking only as muxAcquire does not perform
4673 // thread state transitions.
4674 //
4675 // Alternatives:
4676 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4677 // but with parking or spin-then-park instead of pure spinning.
4678 // * Use Taura-Oyama-Yonenzawa locks.
4679 // * It's possible to construct a 1-0 lock if we encode the lockword as
4680 // (List,LockByte). Acquire will CAS the full lockword while Release
4681 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4682 // acquiring threads use timers (ParkTimed) to detect and recover from
4683 // the stranding window. Thread/Node structures must be aligned on 256-byte
4684 // boundaries by using placement-new.
4685 // * Augment MCS with advisory back-link fields maintained with CAS().
4686 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4687 // The validity of the backlinks must be ratified before we trust the value.
4688 // If the backlinks are invalid the exiting thread must back-track through the
4689 // the forward links, which are always trustworthy.
4690 // * Add a successor indication. The LockWord is currently encoded as
4691 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4692 // to provide the usual futile-wakeup optimization.
4693 // See RTStt for details.
4694 // * Consider schedctl.sc_nopreempt to cover the critical section.
4695 //
4696
4697
4698 typedef volatile intptr_t MutexT; // Mux Lock-word
4699 enum MuxBits { LOCKBIT = 1 };
4700
4701 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4702 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4703 if (w == 0) return;
4704 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4705 return;
4706 }
4707
4708 TEVENT(muxAcquire - Contention);
4709 ParkEvent * const Self = Thread::current()->_MuxEvent;
4710 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4711 for (;;) {
4712 int its = (os::is_MP() ? 100 : 0) + 1;
4713
4714 // Optional spin phase: spin-then-park strategy
4715 while (--its >= 0) {
4716 w = *Lock;
4717 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4718 return;
4719 }
4720 }
4721
4722 Self->reset();
4723 Self->OnList = intptr_t(Lock);
4724 // The following fence() isn't _strictly necessary as the subsequent
4725 // CAS() both serializes execution and ratifies the fetched *Lock value.
4726 OrderAccess::fence();
4727 for (;;) {
4728 w = *Lock;
4729 if ((w & LOCKBIT) == 0) {
4730 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4731 Self->OnList = 0; // hygiene - allows stronger asserts
4732 return;
4733 }
4734 continue; // Interference -- *Lock changed -- Just retry
4735 }
4736 assert(w & LOCKBIT, "invariant");
4737 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4738 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4739 }
4740
4741 while (Self->OnList != 0) {
4742 Self->park();
4743 }
4744 }
4745 }
4746
4747 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4748 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4749 if (w == 0) return;
4750 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4751 return;
4752 }
4753
4754 TEVENT(muxAcquire - Contention);
4755 ParkEvent * ReleaseAfter = NULL;
4756 if (ev == NULL) {
4757 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4758 }
4759 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4760 for (;;) {
4761 guarantee(ev->OnList == 0, "invariant");
4762 int its = (os::is_MP() ? 100 : 0) + 1;
4763
4764 // Optional spin phase: spin-then-park strategy
4765 while (--its >= 0) {
4766 w = *Lock;
4767 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4768 if (ReleaseAfter != NULL) {
4769 ParkEvent::Release(ReleaseAfter);
4770 }
4771 return;
4772 }
4773 }
4774
4775 ev->reset();
4776 ev->OnList = intptr_t(Lock);
4777 // The following fence() isn't _strictly necessary as the subsequent
4778 // CAS() both serializes execution and ratifies the fetched *Lock value.
4779 OrderAccess::fence();
4780 for (;;) {
4781 w = *Lock;
4782 if ((w & LOCKBIT) == 0) {
4783 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4784 ev->OnList = 0;
4785 // We call ::Release while holding the outer lock, thus
4786 // artificially lengthening the critical section.
4787 // Consider deferring the ::Release() until the subsequent unlock(),
4788 // after we've dropped the outer lock.
4789 if (ReleaseAfter != NULL) {
4790 ParkEvent::Release(ReleaseAfter);
4791 }
4792 return;
4793 }
4794 continue; // Interference -- *Lock changed -- Just retry
4795 }
4796 assert(w & LOCKBIT, "invariant");
4797 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4798 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4799 }
4800
4801 while (ev->OnList != 0) {
4802 ev->park();
4803 }
4804 }
4805 }
4806
4807 // Release() must extract a successor from the list and then wake that thread.
4808 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4809 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4810 // Release() would :
4811 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4812 // (B) Extract a successor from the private list "in-hand"
4813 // (C) attempt to CAS() the residual back into *Lock over null.
4814 // If there were any newly arrived threads and the CAS() would fail.
4815 // In that case Release() would detach the RATs, re-merge the list in-hand
4816 // with the RATs and repeat as needed. Alternately, Release() might
4817 // detach and extract a successor, but then pass the residual list to the wakee.
4818 // The wakee would be responsible for reattaching and remerging before it
4819 // competed for the lock.
4820 //
4821 // Both "pop" and DMR are immune from ABA corruption -- there can be
4822 // multiple concurrent pushers, but only one popper or detacher.
4823 // This implementation pops from the head of the list. This is unfair,
4824 // but tends to provide excellent throughput as hot threads remain hot.
4825 // (We wake recently run threads first).
4826 //
4827 // All paths through muxRelease() will execute a CAS.
4828 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4829 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4830 // executed within the critical section are complete and globally visible before the
4831 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4832 void Thread::muxRelease(volatile intptr_t * Lock) {
4833 for (;;) {
4834 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4835 assert(w & LOCKBIT, "invariant");
4836 if (w == LOCKBIT) return;
4837 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4838 assert(List != NULL, "invariant");
4839 assert(List->OnList == intptr_t(Lock), "invariant");
4840 ParkEvent * const nxt = List->ListNext;
4841 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4842
4843 // The following CAS() releases the lock and pops the head element.
4844 // The CAS() also ratifies the previously fetched lock-word value.
4845 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4846 continue;
4847 }
4848 List->OnList = 0;
4849 OrderAccess::fence();
4850 List->unpark();
4851 return;
4852 }
4853 }
4854
4855
4856 void Threads::verify() {
4857 ALL_JAVA_THREADS(p) {
4858 p->verify();
4859 }
4860 VMThread* thread = VMThread::vm_thread();
4861 if (thread != NULL) thread->verify();
4862 }