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/referencePendingListLocker.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/fprofiler.hpp"
67 #include "runtime/frame.inline.hpp"
68 #include "runtime/globals.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/interfaceSupport.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniPeriodicChecker.hpp"
74 #include "runtime/timerTrace.hpp"
75 #include "runtime/memprofiler.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/objectMonitor.hpp"
78 #include "runtime/orderAccess.inline.hpp"
79 #include "runtime/osThread.hpp"
80 #include "runtime/safepoint.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/defaultStream.hpp"
101 #include "utilities/dtrace.hpp"
102 #include "utilities/events.hpp"
103 #include "utilities/macros.hpp"
104 #include "utilities/preserveException.hpp"
105 #if INCLUDE_ALL_GCS
106 #include "gc/cms/concurrentMarkSweepThread.hpp"
107 #include "gc/g1/concurrentMarkThread.inline.hpp"
108 #include "gc/parallel/pcTasks.hpp"
109 #endif // INCLUDE_ALL_GCS
110 #if INCLUDE_JVMCI
111 #include "jvmci/jvmciCompiler.hpp"
112 #include "jvmci/jvmciRuntime.hpp"
113 #endif
114 #ifdef COMPILER1
115 #include "c1/c1_Compiler.hpp"
116 #endif
117 #ifdef COMPILER2
118 #include "opto/c2compiler.hpp"
119 #include "opto/idealGraphPrinter.hpp"
120 #endif
121 #if INCLUDE_RTM_OPT
122 #include "runtime/rtmLocking.hpp"
123 #endif
124
125 // Initialization after module runtime initialization
126 void universe_post_module_init(); // must happen after call_initPhase2
127
128 #ifdef DTRACE_ENABLED
129
130 // Only bother with this argument setup if dtrace is available
131
132 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
133 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
134
135 #define DTRACE_THREAD_PROBE(probe, javathread) \
136 { \
137 ResourceMark rm(this); \
138 int len = 0; \
139 const char* name = (javathread)->get_thread_name(); \
140 len = strlen(name); \
141 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
142 (char *) name, len, \
143 java_lang_Thread::thread_id((javathread)->threadObj()), \
144 (uintptr_t) (javathread)->osthread()->thread_id(), \
145 java_lang_Thread::is_daemon((javathread)->threadObj())); \
146 }
147
148 #else // ndef DTRACE_ENABLED
149
150 #define DTRACE_THREAD_PROBE(probe, javathread)
151
152 #endif // ndef DTRACE_ENABLED
153
154 #ifndef USE_LIBRARY_BASED_TLS_ONLY
155 // Current thread is maintained as a thread-local variable
156 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
157 #endif
158 // Class hierarchy
159 // - Thread
160 // - VMThread
161 // - WatcherThread
162 // - ConcurrentMarkSweepThread
163 // - JavaThread
164 // - CompilerThread
165
166 // ======= Thread ========
167 // Support for forcing alignment of thread objects for biased locking
168 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
169 if (UseBiasedLocking) {
170 const int alignment = markOopDesc::biased_lock_alignment;
171 size_t aligned_size = size + (alignment - sizeof(intptr_t));
172 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
173 : AllocateHeap(aligned_size, flags, CURRENT_PC,
174 AllocFailStrategy::RETURN_NULL);
175 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
176 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
177 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
178 "JavaThread alignment code overflowed allocated storage");
179 if (aligned_addr != real_malloc_addr) {
180 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
181 p2i(real_malloc_addr),
182 p2i(aligned_addr));
183 }
184 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
185 return aligned_addr;
186 } else {
187 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
188 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
189 }
190 }
191
192 void Thread::operator delete(void* p) {
193 if (UseBiasedLocking) {
194 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
195 FreeHeap(real_malloc_addr);
196 } else {
197 FreeHeap(p);
198 }
199 }
200
201
202 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
203 // JavaThread
204
205
206 Thread::Thread() {
207 // stack and get_thread
208 set_stack_base(NULL);
209 set_stack_size(0);
210 set_self_raw_id(0);
211 set_lgrp_id(-1);
212 DEBUG_ONLY(clear_suspendible_thread();)
213
214 // allocated data structures
215 set_osthread(NULL);
216 set_resource_area(new (mtThread)ResourceArea());
217 DEBUG_ONLY(_current_resource_mark = NULL;)
218 set_handle_area(new (mtThread) HandleArea(NULL));
219 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
220 set_active_handles(NULL);
221 set_free_handle_block(NULL);
222 set_last_handle_mark(NULL);
223
224 // This initial value ==> never claimed.
225 _oops_do_parity = 0;
226
227 // the handle mark links itself to last_handle_mark
228 new HandleMark(this);
229
230 // plain initialization
231 debug_only(_owned_locks = NULL;)
232 debug_only(_allow_allocation_count = 0;)
233 NOT_PRODUCT(_allow_safepoint_count = 0;)
234 NOT_PRODUCT(_skip_gcalot = false;)
235 _jvmti_env_iteration_count = 0;
236 set_allocated_bytes(0);
237 _vm_operation_started_count = 0;
238 _vm_operation_completed_count = 0;
239 _current_pending_monitor = NULL;
240 _current_pending_monitor_is_from_java = true;
241 _current_waiting_monitor = NULL;
242 _num_nested_signal = 0;
243 omFreeList = NULL;
244 omFreeCount = 0;
245 omFreeProvision = 32;
246 omInUseList = NULL;
247 omInUseCount = 0;
248
249 #ifdef ASSERT
250 _visited_for_critical_count = false;
251 #endif
252
253 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
254 Monitor::_safepoint_check_sometimes);
255 _suspend_flags = 0;
256
257 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
258 _hashStateX = os::random();
259 _hashStateY = 842502087;
260 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
261 _hashStateW = 273326509;
262
263 _OnTrap = 0;
264 _schedctl = NULL;
265 _Stalled = 0;
266 _TypeTag = 0x2BAD;
267
268 // Many of the following fields are effectively final - immutable
269 // Note that nascent threads can't use the Native Monitor-Mutex
270 // construct until the _MutexEvent is initialized ...
271 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
272 // we might instead use a stack of ParkEvents that we could provision on-demand.
273 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
274 // and ::Release()
275 _ParkEvent = ParkEvent::Allocate(this);
276 _SleepEvent = ParkEvent::Allocate(this);
277 _MutexEvent = ParkEvent::Allocate(this);
278 _MuxEvent = ParkEvent::Allocate(this);
279
280 #ifdef CHECK_UNHANDLED_OOPS
281 if (CheckUnhandledOops) {
282 _unhandled_oops = new UnhandledOops(this);
283 }
284 #endif // CHECK_UNHANDLED_OOPS
285 #ifdef ASSERT
286 if (UseBiasedLocking) {
287 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
288 assert(this == _real_malloc_address ||
289 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
290 "bug in forced alignment of thread objects");
291 }
292 #endif // ASSERT
293 }
294
295 void Thread::initialize_thread_current() {
296 #ifndef USE_LIBRARY_BASED_TLS_ONLY
297 assert(_thr_current == NULL, "Thread::current already initialized");
298 _thr_current = this;
299 #endif
300 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
301 ThreadLocalStorage::set_thread(this);
302 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
303 }
304
305 void Thread::clear_thread_current() {
306 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
307 #ifndef USE_LIBRARY_BASED_TLS_ONLY
308 _thr_current = NULL;
309 #endif
310 ThreadLocalStorage::set_thread(NULL);
311 }
312
313 void Thread::record_stack_base_and_size() {
314 set_stack_base(os::current_stack_base());
315 set_stack_size(os::current_stack_size());
316 // CR 7190089: on Solaris, primordial thread's stack is adjusted
317 // in initialize_thread(). Without the adjustment, stack size is
318 // incorrect if stack is set to unlimited (ulimit -s unlimited).
319 // So far, only Solaris has real implementation of initialize_thread().
320 //
321 // set up any platform-specific state.
322 os::initialize_thread(this);
323
324 // Set stack limits after thread is initialized.
325 if (is_Java_thread()) {
326 ((JavaThread*) this)->set_stack_overflow_limit();
327 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
328 }
329 #if INCLUDE_NMT
330 // record thread's native stack, stack grows downward
331 MemTracker::record_thread_stack(stack_end(), stack_size());
332 #endif // INCLUDE_NMT
333 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
334 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
335 os::current_thread_id(), p2i(stack_base() - stack_size()),
336 p2i(stack_base()), stack_size()/1024);
337 }
338
339
340 Thread::~Thread() {
341 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
342 ObjectSynchronizer::omFlush(this);
343
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // osthread() can be NULL, if creation of thread failed.
378 if (osthread() != NULL) os::free_thread(osthread());
379
380 delete _SR_lock;
381
382 // clear Thread::current if thread is deleting itself.
383 // Needed to ensure JNI correctly detects non-attached threads.
384 if (this == Thread::current()) {
385 clear_thread_current();
386 }
387
388 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
389 }
390
391 // NOTE: dummy function for assertion purpose.
392 void Thread::run() {
393 ShouldNotReachHere();
394 }
395
396 #ifdef ASSERT
397 // Private method to check for dangling thread pointer
398 void check_for_dangling_thread_pointer(Thread *thread) {
399 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
400 "possibility of dangling Thread pointer");
401 }
402 #endif
403
404 ThreadPriority Thread::get_priority(const Thread* const thread) {
405 ThreadPriority priority;
406 // Can return an error!
407 (void)os::get_priority(thread, priority);
408 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
409 return priority;
410 }
411
412 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
413 debug_only(check_for_dangling_thread_pointer(thread);)
414 // Can return an error!
415 (void)os::set_priority(thread, priority);
416 }
417
418
419 void Thread::start(Thread* thread) {
420 // Start is different from resume in that its safety is guaranteed by context or
421 // being called from a Java method synchronized on the Thread object.
422 if (!DisableStartThread) {
423 if (thread->is_Java_thread()) {
424 // Initialize the thread state to RUNNABLE before starting this thread.
425 // Can not set it after the thread started because we do not know the
426 // exact thread state at that time. It could be in MONITOR_WAIT or
427 // in SLEEPING or some other state.
428 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
429 java_lang_Thread::RUNNABLE);
430 }
431 os::start_thread(thread);
432 }
433 }
434
435 // Enqueue a VM_Operation to do the job for us - sometime later
436 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
437 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
438 VMThread::execute(vm_stop);
439 }
440
441
442 // Check if an external suspend request has completed (or has been
443 // cancelled). Returns true if the thread is externally suspended and
444 // false otherwise.
445 //
446 // The bits parameter returns information about the code path through
447 // the routine. Useful for debugging:
448 //
449 // set in is_ext_suspend_completed():
450 // 0x00000001 - routine was entered
451 // 0x00000010 - routine return false at end
452 // 0x00000100 - thread exited (return false)
453 // 0x00000200 - suspend request cancelled (return false)
454 // 0x00000400 - thread suspended (return true)
455 // 0x00001000 - thread is in a suspend equivalent state (return true)
456 // 0x00002000 - thread is native and walkable (return true)
457 // 0x00004000 - thread is native_trans and walkable (needed retry)
458 //
459 // set in wait_for_ext_suspend_completion():
460 // 0x00010000 - routine was entered
461 // 0x00020000 - suspend request cancelled before loop (return false)
462 // 0x00040000 - thread suspended before loop (return true)
463 // 0x00080000 - suspend request cancelled in loop (return false)
464 // 0x00100000 - thread suspended in loop (return true)
465 // 0x00200000 - suspend not completed during retry loop (return false)
466
467 // Helper class for tracing suspend wait debug bits.
468 //
469 // 0x00000100 indicates that the target thread exited before it could
470 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
471 // 0x00080000 each indicate a cancelled suspend request so they don't
472 // count as wait failures either.
473 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
474
475 class TraceSuspendDebugBits : public StackObj {
476 private:
477 JavaThread * jt;
478 bool is_wait;
479 bool called_by_wait; // meaningful when !is_wait
480 uint32_t * bits;
481
482 public:
483 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
484 uint32_t *_bits) {
485 jt = _jt;
486 is_wait = _is_wait;
487 called_by_wait = _called_by_wait;
488 bits = _bits;
489 }
490
491 ~TraceSuspendDebugBits() {
492 if (!is_wait) {
493 #if 1
494 // By default, don't trace bits for is_ext_suspend_completed() calls.
495 // That trace is very chatty.
496 return;
497 #else
498 if (!called_by_wait) {
499 // If tracing for is_ext_suspend_completed() is enabled, then only
500 // trace calls to it from wait_for_ext_suspend_completion()
501 return;
502 }
503 #endif
504 }
505
506 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
507 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
508 MutexLocker ml(Threads_lock); // needed for get_thread_name()
509 ResourceMark rm;
510
511 tty->print_cr(
512 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
513 jt->get_thread_name(), *bits);
514
515 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
516 }
517 }
518 }
519 };
520 #undef DEBUG_FALSE_BITS
521
522
523 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
524 uint32_t *bits) {
525 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
526
527 bool did_trans_retry = false; // only do thread_in_native_trans retry once
528 bool do_trans_retry; // flag to force the retry
529
530 *bits |= 0x00000001;
531
532 do {
533 do_trans_retry = false;
534
535 if (is_exiting()) {
536 // Thread is in the process of exiting. This is always checked
537 // first to reduce the risk of dereferencing a freed JavaThread.
538 *bits |= 0x00000100;
539 return false;
540 }
541
542 if (!is_external_suspend()) {
543 // Suspend request is cancelled. This is always checked before
544 // is_ext_suspended() to reduce the risk of a rogue resume
545 // confusing the thread that made the suspend request.
546 *bits |= 0x00000200;
547 return false;
548 }
549
550 if (is_ext_suspended()) {
551 // thread is suspended
552 *bits |= 0x00000400;
553 return true;
554 }
555
556 // Now that we no longer do hard suspends of threads running
557 // native code, the target thread can be changing thread state
558 // while we are in this routine:
559 //
560 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
561 //
562 // We save a copy of the thread state as observed at this moment
563 // and make our decision about suspend completeness based on the
564 // copy. This closes the race where the thread state is seen as
565 // _thread_in_native_trans in the if-thread_blocked check, but is
566 // seen as _thread_blocked in if-thread_in_native_trans check.
567 JavaThreadState save_state = thread_state();
568
569 if (save_state == _thread_blocked && is_suspend_equivalent()) {
570 // If the thread's state is _thread_blocked and this blocking
571 // condition is known to be equivalent to a suspend, then we can
572 // consider the thread to be externally suspended. This means that
573 // the code that sets _thread_blocked has been modified to do
574 // self-suspension if the blocking condition releases. We also
575 // used to check for CONDVAR_WAIT here, but that is now covered by
576 // the _thread_blocked with self-suspension check.
577 //
578 // Return true since we wouldn't be here unless there was still an
579 // external suspend request.
580 *bits |= 0x00001000;
581 return true;
582 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
583 // Threads running native code will self-suspend on native==>VM/Java
584 // transitions. If its stack is walkable (should always be the case
585 // unless this function is called before the actual java_suspend()
586 // call), then the wait is done.
587 *bits |= 0x00002000;
588 return true;
589 } else if (!called_by_wait && !did_trans_retry &&
590 save_state == _thread_in_native_trans &&
591 frame_anchor()->walkable()) {
592 // The thread is transitioning from thread_in_native to another
593 // thread state. check_safepoint_and_suspend_for_native_trans()
594 // will force the thread to self-suspend. If it hasn't gotten
595 // there yet we may have caught the thread in-between the native
596 // code check above and the self-suspend. Lucky us. If we were
597 // called by wait_for_ext_suspend_completion(), then it
598 // will be doing the retries so we don't have to.
599 //
600 // Since we use the saved thread state in the if-statement above,
601 // there is a chance that the thread has already transitioned to
602 // _thread_blocked by the time we get here. In that case, we will
603 // make a single unnecessary pass through the logic below. This
604 // doesn't hurt anything since we still do the trans retry.
605
606 *bits |= 0x00004000;
607
608 // Once the thread leaves thread_in_native_trans for another
609 // thread state, we break out of this retry loop. We shouldn't
610 // need this flag to prevent us from getting back here, but
611 // sometimes paranoia is good.
612 did_trans_retry = true;
613
614 // We wait for the thread to transition to a more usable state.
615 for (int i = 1; i <= SuspendRetryCount; i++) {
616 // We used to do an "os::yield_all(i)" call here with the intention
617 // that yielding would increase on each retry. However, the parameter
618 // is ignored on Linux which means the yield didn't scale up. Waiting
619 // on the SR_lock below provides a much more predictable scale up for
620 // the delay. It also provides a simple/direct point to check for any
621 // safepoint requests from the VMThread
622
623 // temporarily drops SR_lock while doing wait with safepoint check
624 // (if we're a JavaThread - the WatcherThread can also call this)
625 // and increase delay with each retry
626 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
627
628 // check the actual thread state instead of what we saved above
629 if (thread_state() != _thread_in_native_trans) {
630 // the thread has transitioned to another thread state so
631 // try all the checks (except this one) one more time.
632 do_trans_retry = true;
633 break;
634 }
635 } // end retry loop
636
637
638 }
639 } while (do_trans_retry);
640
641 *bits |= 0x00000010;
642 return false;
643 }
644
645 // Wait for an external suspend request to complete (or be cancelled).
646 // Returns true if the thread is externally suspended and false otherwise.
647 //
648 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
649 uint32_t *bits) {
650 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
651 false /* !called_by_wait */, bits);
652
653 // local flag copies to minimize SR_lock hold time
654 bool is_suspended;
655 bool pending;
656 uint32_t reset_bits;
657
658 // set a marker so is_ext_suspend_completed() knows we are the caller
659 *bits |= 0x00010000;
660
661 // We use reset_bits to reinitialize the bits value at the top of
662 // each retry loop. This allows the caller to make use of any
663 // unused bits for their own marking purposes.
664 reset_bits = *bits;
665
666 {
667 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
668 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
669 delay, bits);
670 pending = is_external_suspend();
671 }
672 // must release SR_lock to allow suspension to complete
673
674 if (!pending) {
675 // A cancelled suspend request is the only false return from
676 // is_ext_suspend_completed() that keeps us from entering the
677 // retry loop.
678 *bits |= 0x00020000;
679 return false;
680 }
681
682 if (is_suspended) {
683 *bits |= 0x00040000;
684 return true;
685 }
686
687 for (int i = 1; i <= retries; i++) {
688 *bits = reset_bits; // reinit to only track last retry
689
690 // We used to do an "os::yield_all(i)" call here with the intention
691 // that yielding would increase on each retry. However, the parameter
692 // is ignored on Linux which means the yield didn't scale up. Waiting
693 // on the SR_lock below provides a much more predictable scale up for
694 // the delay. It also provides a simple/direct point to check for any
695 // safepoint requests from the VMThread
696
697 {
698 MutexLocker ml(SR_lock());
699 // wait with safepoint check (if we're a JavaThread - the WatcherThread
700 // can also call this) and increase delay with each retry
701 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
702
703 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
704 delay, bits);
705
706 // It is possible for the external suspend request to be cancelled
707 // (by a resume) before the actual suspend operation is completed.
708 // Refresh our local copy to see if we still need to wait.
709 pending = is_external_suspend();
710 }
711
712 if (!pending) {
713 // A cancelled suspend request is the only false return from
714 // is_ext_suspend_completed() that keeps us from staying in the
715 // retry loop.
716 *bits |= 0x00080000;
717 return false;
718 }
719
720 if (is_suspended) {
721 *bits |= 0x00100000;
722 return true;
723 }
724 } // end retry loop
725
726 // thread did not suspend after all our retries
727 *bits |= 0x00200000;
728 return false;
729 }
730
731 #ifndef PRODUCT
732 void JavaThread::record_jump(address target, address instr, const char* file,
733 int line) {
734
735 // This should not need to be atomic as the only way for simultaneous
736 // updates is via interrupts. Even then this should be rare or non-existent
737 // and we don't care that much anyway.
738
739 int index = _jmp_ring_index;
740 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
741 _jmp_ring[index]._target = (intptr_t) target;
742 _jmp_ring[index]._instruction = (intptr_t) instr;
743 _jmp_ring[index]._file = file;
744 _jmp_ring[index]._line = line;
745 }
746 #endif // PRODUCT
747
748 // Called by flat profiler
749 // Callers have already called wait_for_ext_suspend_completion
750 // The assertion for that is currently too complex to put here:
751 bool JavaThread::profile_last_Java_frame(frame* _fr) {
752 bool gotframe = false;
753 // self suspension saves needed state.
754 if (has_last_Java_frame() && _anchor.walkable()) {
755 *_fr = pd_last_frame();
756 gotframe = true;
757 }
758 return gotframe;
759 }
760
761 void Thread::interrupt(Thread* thread) {
762 debug_only(check_for_dangling_thread_pointer(thread);)
763 os::interrupt(thread);
764 }
765
766 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
767 debug_only(check_for_dangling_thread_pointer(thread);)
768 // Note: If clear_interrupted==false, this simply fetches and
769 // returns the value of the field osthread()->interrupted().
770 return os::is_interrupted(thread, clear_interrupted);
771 }
772
773
774 // GC Support
775 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
776 jint thread_parity = _oops_do_parity;
777 if (thread_parity != strong_roots_parity) {
778 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
779 if (res == thread_parity) {
780 return true;
781 } else {
782 guarantee(res == strong_roots_parity, "Or else what?");
783 return false;
784 }
785 }
786 return false;
787 }
788
789 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
790 active_handles()->oops_do(f);
791 // Do oop for ThreadShadow
792 f->do_oop((oop*)&_pending_exception);
793 handle_area()->oops_do(f);
794 }
795
796 void Thread::metadata_handles_do(void f(Metadata*)) {
797 // Only walk the Handles in Thread.
798 if (metadata_handles() != NULL) {
799 for (int i = 0; i< metadata_handles()->length(); i++) {
800 f(metadata_handles()->at(i));
801 }
802 }
803 }
804
805 void Thread::print_on(outputStream* st) const {
806 // get_priority assumes osthread initialized
807 if (osthread() != NULL) {
808 int os_prio;
809 if (os::get_native_priority(this, &os_prio) == OS_OK) {
810 st->print("os_prio=%d ", os_prio);
811 }
812 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
813 ext().print_on(st);
814 osthread()->print_on(st);
815 }
816 debug_only(if (WizardMode) print_owned_locks_on(st);)
817 }
818
819 // Thread::print_on_error() is called by fatal error handler. Don't use
820 // any lock or allocate memory.
821 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
822 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
823
824 if (is_VM_thread()) { st->print("VMThread"); }
825 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
826 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
827 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
828 else { st->print("Thread"); }
829
830 if (is_Named_thread()) {
831 st->print(" \"%s\"", name());
832 }
833
834 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
835 p2i(stack_end()), p2i(stack_base()));
836
837 if (osthread()) {
838 st->print(" [id=%d]", osthread()->thread_id());
839 }
840 }
841
842 #ifdef ASSERT
843 void Thread::print_owned_locks_on(outputStream* st) const {
844 Monitor *cur = _owned_locks;
845 if (cur == NULL) {
846 st->print(" (no locks) ");
847 } else {
848 st->print_cr(" Locks owned:");
849 while (cur) {
850 cur->print_on(st);
851 cur = cur->next();
852 }
853 }
854 }
855
856 static int ref_use_count = 0;
857
858 bool Thread::owns_locks_but_compiled_lock() const {
859 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
860 if (cur != Compile_lock) return true;
861 }
862 return false;
863 }
864
865
866 #endif
867
868 #ifndef PRODUCT
869
870 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
871 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
872 // no threads which allow_vm_block's are held
873 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
874 // Check if current thread is allowed to block at a safepoint
875 if (!(_allow_safepoint_count == 0)) {
876 fatal("Possible safepoint reached by thread that does not allow it");
877 }
878 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
879 fatal("LEAF method calling lock?");
880 }
881
882 #ifdef ASSERT
883 if (potential_vm_operation && is_Java_thread()
884 && !Universe::is_bootstrapping()) {
885 // Make sure we do not hold any locks that the VM thread also uses.
886 // This could potentially lead to deadlocks
887 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
888 // Threads_lock is special, since the safepoint synchronization will not start before this is
889 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
890 // since it is used to transfer control between JavaThreads and the VMThread
891 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
892 if ((cur->allow_vm_block() &&
893 cur != Threads_lock &&
894 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
895 cur != VMOperationRequest_lock &&
896 cur != VMOperationQueue_lock) ||
897 cur->rank() == Mutex::special) {
898 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
899 }
900 }
901 }
902
903 if (GCALotAtAllSafepoints) {
904 // We could enter a safepoint here and thus have a gc
905 InterfaceSupport::check_gc_alot();
906 }
907 #endif
908 }
909 #endif
910
911 bool Thread::is_in_stack(address adr) const {
912 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
913 address end = os::current_stack_pointer();
914 // Allow non Java threads to call this without stack_base
915 if (_stack_base == NULL) return true;
916 if (stack_base() >= adr && adr >= end) return true;
917
918 return false;
919 }
920
921 bool Thread::is_in_usable_stack(address adr) const {
922 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
923 size_t usable_stack_size = _stack_size - stack_guard_size;
924
925 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
926 }
927
928
929 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
930 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
931 // used for compilation in the future. If that change is made, the need for these methods
932 // should be revisited, and they should be removed if possible.
933
934 bool Thread::is_lock_owned(address adr) const {
935 return on_local_stack(adr);
936 }
937
938 bool Thread::set_as_starting_thread() {
939 // NOTE: this must be called inside the main thread.
940 return os::create_main_thread((JavaThread*)this);
941 }
942
943 static void initialize_class(Symbol* class_name, TRAPS) {
944 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
945 InstanceKlass::cast(klass)->initialize(CHECK);
946 }
947
948
949 // Creates the initial ThreadGroup
950 static Handle create_initial_thread_group(TRAPS) {
951 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
952 instanceKlassHandle klass (THREAD, k);
953
954 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
955 {
956 JavaValue result(T_VOID);
957 JavaCalls::call_special(&result,
958 system_instance,
959 klass,
960 vmSymbols::object_initializer_name(),
961 vmSymbols::void_method_signature(),
962 CHECK_NH);
963 }
964 Universe::set_system_thread_group(system_instance());
965
966 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
967 {
968 JavaValue result(T_VOID);
969 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
970 JavaCalls::call_special(&result,
971 main_instance,
972 klass,
973 vmSymbols::object_initializer_name(),
974 vmSymbols::threadgroup_string_void_signature(),
975 system_instance,
976 string,
977 CHECK_NH);
978 }
979 return main_instance;
980 }
981
982 // Creates the initial Thread
983 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
984 TRAPS) {
985 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
986 instanceKlassHandle klass (THREAD, k);
987 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
988
989 java_lang_Thread::set_thread(thread_oop(), thread);
990 java_lang_Thread::set_priority(thread_oop(), NormPriority);
991 thread->set_threadObj(thread_oop());
992
993 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
994
995 JavaValue result(T_VOID);
996 JavaCalls::call_special(&result, thread_oop,
997 klass,
998 vmSymbols::object_initializer_name(),
999 vmSymbols::threadgroup_string_void_signature(),
1000 thread_group,
1001 string,
1002 CHECK_NULL);
1003 return thread_oop();
1004 }
1005
1006 char java_runtime_name[128] = "";
1007 char java_runtime_version[128] = "";
1008
1009 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1010 static const char* get_java_runtime_name(TRAPS) {
1011 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1012 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1013 fieldDescriptor fd;
1014 bool found = k != NULL &&
1015 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1016 vmSymbols::string_signature(), &fd);
1017 if (found) {
1018 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1019 if (name_oop == NULL) {
1020 return NULL;
1021 }
1022 const char* name = java_lang_String::as_utf8_string(name_oop,
1023 java_runtime_name,
1024 sizeof(java_runtime_name));
1025 return name;
1026 } else {
1027 return NULL;
1028 }
1029 }
1030
1031 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1032 static const char* get_java_runtime_version(TRAPS) {
1033 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1034 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1035 fieldDescriptor fd;
1036 bool found = k != NULL &&
1037 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1038 vmSymbols::string_signature(), &fd);
1039 if (found) {
1040 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1041 if (name_oop == NULL) {
1042 return NULL;
1043 }
1044 const char* name = java_lang_String::as_utf8_string(name_oop,
1045 java_runtime_version,
1046 sizeof(java_runtime_version));
1047 return name;
1048 } else {
1049 return NULL;
1050 }
1051 }
1052
1053 // General purpose hook into Java code, run once when the VM is initialized.
1054 // The Java library method itself may be changed independently from the VM.
1055 static void call_postVMInitHook(TRAPS) {
1056 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1057 instanceKlassHandle klass (THREAD, k);
1058 if (klass.not_null()) {
1059 JavaValue result(T_VOID);
1060 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1061 vmSymbols::void_method_signature(),
1062 CHECK);
1063 }
1064 }
1065
1066 static void reset_vm_info_property(TRAPS) {
1067 // the vm info string
1068 ResourceMark rm(THREAD);
1069 const char *vm_info = VM_Version::vm_info_string();
1070
1071 // java.lang.System class
1072 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1073 instanceKlassHandle klass (THREAD, k);
1074
1075 // setProperty arguments
1076 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1077 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1078
1079 // return value
1080 JavaValue r(T_OBJECT);
1081
1082 // public static String setProperty(String key, String value);
1083 JavaCalls::call_static(&r,
1084 klass,
1085 vmSymbols::setProperty_name(),
1086 vmSymbols::string_string_string_signature(),
1087 key_str,
1088 value_str,
1089 CHECK);
1090 }
1091
1092
1093 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1094 bool daemon, TRAPS) {
1095 assert(thread_group.not_null(), "thread group should be specified");
1096 assert(threadObj() == NULL, "should only create Java thread object once");
1097
1098 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1099 instanceKlassHandle klass (THREAD, k);
1100 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1101
1102 java_lang_Thread::set_thread(thread_oop(), this);
1103 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1104 set_threadObj(thread_oop());
1105
1106 JavaValue result(T_VOID);
1107 if (thread_name != NULL) {
1108 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1109 // Thread gets assigned specified name and null target
1110 JavaCalls::call_special(&result,
1111 thread_oop,
1112 klass,
1113 vmSymbols::object_initializer_name(),
1114 vmSymbols::threadgroup_string_void_signature(),
1115 thread_group, // Argument 1
1116 name, // Argument 2
1117 THREAD);
1118 } else {
1119 // Thread gets assigned name "Thread-nnn" and null target
1120 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1121 JavaCalls::call_special(&result,
1122 thread_oop,
1123 klass,
1124 vmSymbols::object_initializer_name(),
1125 vmSymbols::threadgroup_runnable_void_signature(),
1126 thread_group, // Argument 1
1127 Handle(), // Argument 2
1128 THREAD);
1129 }
1130
1131
1132 if (daemon) {
1133 java_lang_Thread::set_daemon(thread_oop());
1134 }
1135
1136 if (HAS_PENDING_EXCEPTION) {
1137 return;
1138 }
1139
1140 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1141 Handle threadObj(THREAD, this->threadObj());
1142
1143 JavaCalls::call_special(&result,
1144 thread_group,
1145 group,
1146 vmSymbols::add_method_name(),
1147 vmSymbols::thread_void_signature(),
1148 threadObj, // Arg 1
1149 THREAD);
1150 }
1151
1152 // NamedThread -- non-JavaThread subclasses with multiple
1153 // uniquely named instances should derive from this.
1154 NamedThread::NamedThread() : Thread() {
1155 _name = NULL;
1156 _processed_thread = NULL;
1157 _gc_id = GCId::undefined();
1158 }
1159
1160 NamedThread::~NamedThread() {
1161 if (_name != NULL) {
1162 FREE_C_HEAP_ARRAY(char, _name);
1163 _name = NULL;
1164 }
1165 }
1166
1167 void NamedThread::set_name(const char* format, ...) {
1168 guarantee(_name == NULL, "Only get to set name once.");
1169 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1170 guarantee(_name != NULL, "alloc failure");
1171 va_list ap;
1172 va_start(ap, format);
1173 jio_vsnprintf(_name, max_name_len, format, ap);
1174 va_end(ap);
1175 }
1176
1177 void NamedThread::initialize_named_thread() {
1178 set_native_thread_name(name());
1179 }
1180
1181 void NamedThread::print_on(outputStream* st) const {
1182 st->print("\"%s\" ", name());
1183 Thread::print_on(st);
1184 st->cr();
1185 }
1186
1187
1188 // ======= WatcherThread ========
1189
1190 // The watcher thread exists to simulate timer interrupts. It should
1191 // be replaced by an abstraction over whatever native support for
1192 // timer interrupts exists on the platform.
1193
1194 WatcherThread* WatcherThread::_watcher_thread = NULL;
1195 bool WatcherThread::_startable = false;
1196 volatile bool WatcherThread::_should_terminate = false;
1197
1198 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1199 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1200 if (os::create_thread(this, os::watcher_thread)) {
1201 _watcher_thread = this;
1202
1203 // Set the watcher thread to the highest OS priority which should not be
1204 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1205 // is created. The only normal thread using this priority is the reference
1206 // handler thread, which runs for very short intervals only.
1207 // If the VMThread's priority is not lower than the WatcherThread profiling
1208 // will be inaccurate.
1209 os::set_priority(this, MaxPriority);
1210 if (!DisableStartThread) {
1211 os::start_thread(this);
1212 }
1213 }
1214 }
1215
1216 int WatcherThread::sleep() const {
1217 // The WatcherThread does not participate in the safepoint protocol
1218 // for the PeriodicTask_lock because it is not a JavaThread.
1219 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1220
1221 if (_should_terminate) {
1222 // check for termination before we do any housekeeping or wait
1223 return 0; // we did not sleep.
1224 }
1225
1226 // remaining will be zero if there are no tasks,
1227 // causing the WatcherThread to sleep until a task is
1228 // enrolled
1229 int remaining = PeriodicTask::time_to_wait();
1230 int time_slept = 0;
1231
1232 // we expect this to timeout - we only ever get unparked when
1233 // we should terminate or when a new task has been enrolled
1234 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1235
1236 jlong time_before_loop = os::javaTimeNanos();
1237
1238 while (true) {
1239 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1240 remaining);
1241 jlong now = os::javaTimeNanos();
1242
1243 if (remaining == 0) {
1244 // if we didn't have any tasks we could have waited for a long time
1245 // consider the time_slept zero and reset time_before_loop
1246 time_slept = 0;
1247 time_before_loop = now;
1248 } else {
1249 // need to recalculate since we might have new tasks in _tasks
1250 time_slept = (int) ((now - time_before_loop) / 1000000);
1251 }
1252
1253 // Change to task list or spurious wakeup of some kind
1254 if (timedout || _should_terminate) {
1255 break;
1256 }
1257
1258 remaining = PeriodicTask::time_to_wait();
1259 if (remaining == 0) {
1260 // Last task was just disenrolled so loop around and wait until
1261 // another task gets enrolled
1262 continue;
1263 }
1264
1265 remaining -= time_slept;
1266 if (remaining <= 0) {
1267 break;
1268 }
1269 }
1270
1271 return time_slept;
1272 }
1273
1274 void WatcherThread::run() {
1275 assert(this == watcher_thread(), "just checking");
1276
1277 this->record_stack_base_and_size();
1278 this->set_native_thread_name(this->name());
1279 this->set_active_handles(JNIHandleBlock::allocate_block());
1280 while (true) {
1281 assert(watcher_thread() == Thread::current(), "thread consistency check");
1282 assert(watcher_thread() == this, "thread consistency check");
1283
1284 // Calculate how long it'll be until the next PeriodicTask work
1285 // should be done, and sleep that amount of time.
1286 int time_waited = sleep();
1287
1288 if (is_error_reported()) {
1289 // A fatal error has happened, the error handler(VMError::report_and_die)
1290 // should abort JVM after creating an error log file. However in some
1291 // rare cases, the error handler itself might deadlock. Here we try to
1292 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1293 //
1294 // This code is in WatcherThread because WatcherThread wakes up
1295 // periodically so the fatal error handler doesn't need to do anything;
1296 // also because the WatcherThread is less likely to crash than other
1297 // threads.
1298
1299 for (;;) {
1300 if (!ShowMessageBoxOnError
1301 && (OnError == NULL || OnError[0] == '\0')
1302 && Arguments::abort_hook() == NULL) {
1303 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1304 fdStream err(defaultStream::output_fd());
1305 err.print_raw_cr("# [ timer expired, abort... ]");
1306 // skip atexit/vm_exit/vm_abort hooks
1307 os::die();
1308 }
1309
1310 // Wake up 5 seconds later, the fatal handler may reset OnError or
1311 // ShowMessageBoxOnError when it is ready to abort.
1312 os::sleep(this, 5 * 1000, false);
1313 }
1314 }
1315
1316 if (_should_terminate) {
1317 // check for termination before posting the next tick
1318 break;
1319 }
1320
1321 PeriodicTask::real_time_tick(time_waited);
1322 }
1323
1324 // Signal that it is terminated
1325 {
1326 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1327 _watcher_thread = NULL;
1328 Terminator_lock->notify();
1329 }
1330 }
1331
1332 void WatcherThread::start() {
1333 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1334
1335 if (watcher_thread() == NULL && _startable) {
1336 _should_terminate = false;
1337 // Create the single instance of WatcherThread
1338 new WatcherThread();
1339 }
1340 }
1341
1342 void WatcherThread::make_startable() {
1343 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1344 _startable = true;
1345 }
1346
1347 void WatcherThread::stop() {
1348 {
1349 // Follow normal safepoint aware lock enter protocol since the
1350 // WatcherThread is stopped by another JavaThread.
1351 MutexLocker ml(PeriodicTask_lock);
1352 _should_terminate = true;
1353
1354 WatcherThread* watcher = watcher_thread();
1355 if (watcher != NULL) {
1356 // unpark the WatcherThread so it can see that it should terminate
1357 watcher->unpark();
1358 }
1359 }
1360
1361 MutexLocker mu(Terminator_lock);
1362
1363 while (watcher_thread() != NULL) {
1364 // This wait should make safepoint checks, wait without a timeout,
1365 // and wait as a suspend-equivalent condition.
1366 //
1367 // Note: If the FlatProfiler is running, then this thread is waiting
1368 // for the WatcherThread to terminate and the WatcherThread, via the
1369 // FlatProfiler task, is waiting for the external suspend request on
1370 // this thread to complete. wait_for_ext_suspend_completion() will
1371 // eventually timeout, but that takes time. Making this wait a
1372 // suspend-equivalent condition solves that timeout problem.
1373 //
1374 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1375 Mutex::_as_suspend_equivalent_flag);
1376 }
1377 }
1378
1379 void WatcherThread::unpark() {
1380 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1381 PeriodicTask_lock->notify();
1382 }
1383
1384 void WatcherThread::print_on(outputStream* st) const {
1385 st->print("\"%s\" ", name());
1386 Thread::print_on(st);
1387 st->cr();
1388 }
1389
1390 // ======= JavaThread ========
1391
1392 #if INCLUDE_JVMCI
1393
1394 jlong* JavaThread::_jvmci_old_thread_counters;
1395
1396 bool jvmci_counters_include(JavaThread* thread) {
1397 oop threadObj = thread->threadObj();
1398 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1399 }
1400
1401 void JavaThread::collect_counters(typeArrayOop array) {
1402 if (JVMCICounterSize > 0) {
1403 MutexLocker tl(Threads_lock);
1404 for (int i = 0; i < array->length(); i++) {
1405 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1406 }
1407 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1408 if (jvmci_counters_include(tp)) {
1409 for (int i = 0; i < array->length(); i++) {
1410 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1411 }
1412 }
1413 }
1414 }
1415 }
1416
1417 #endif // INCLUDE_JVMCI
1418
1419 // A JavaThread is a normal Java thread
1420
1421 void JavaThread::initialize() {
1422 // Initialize fields
1423
1424 set_saved_exception_pc(NULL);
1425 set_threadObj(NULL);
1426 _anchor.clear();
1427 set_entry_point(NULL);
1428 set_jni_functions(jni_functions());
1429 set_callee_target(NULL);
1430 set_vm_result(NULL);
1431 set_vm_result_2(NULL);
1432 set_vframe_array_head(NULL);
1433 set_vframe_array_last(NULL);
1434 set_deferred_locals(NULL);
1435 set_deopt_mark(NULL);
1436 set_deopt_compiled_method(NULL);
1437 clear_must_deopt_id();
1438 set_monitor_chunks(NULL);
1439 set_next(NULL);
1440 set_thread_state(_thread_new);
1441 _terminated = _not_terminated;
1442 _privileged_stack_top = NULL;
1443 _array_for_gc = NULL;
1444 _suspend_equivalent = false;
1445 _in_deopt_handler = 0;
1446 _doing_unsafe_access = false;
1447 _stack_guard_state = stack_guard_unused;
1448 #if INCLUDE_JVMCI
1449 _pending_monitorenter = false;
1450 _pending_deoptimization = -1;
1451 _pending_failed_speculation = NULL;
1452 _pending_transfer_to_interpreter = false;
1453 _adjusting_comp_level = false;
1454 _jvmci._alternate_call_target = NULL;
1455 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1456 if (JVMCICounterSize > 0) {
1457 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1458 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1459 } else {
1460 _jvmci_counters = NULL;
1461 }
1462 #endif // INCLUDE_JVMCI
1463 _reserved_stack_activation = NULL; // stack base not known yet
1464 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1465 _exception_pc = 0;
1466 _exception_handler_pc = 0;
1467 _is_method_handle_return = 0;
1468 _jvmti_thread_state= NULL;
1469 _should_post_on_exceptions_flag = JNI_FALSE;
1470 _jvmti_get_loaded_classes_closure = NULL;
1471 _interp_only_mode = 0;
1472 _special_runtime_exit_condition = _no_async_condition;
1473 _pending_async_exception = NULL;
1474 _thread_stat = NULL;
1475 _thread_stat = new ThreadStatistics();
1476 _blocked_on_compilation = false;
1477 _jni_active_critical = 0;
1478 _pending_jni_exception_check_fn = NULL;
1479 _do_not_unlock_if_synchronized = false;
1480 _cached_monitor_info = NULL;
1481 _parker = Parker::Allocate(this);
1482
1483 #ifndef PRODUCT
1484 _jmp_ring_index = 0;
1485 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1486 record_jump(NULL, NULL, NULL, 0);
1487 }
1488 #endif // PRODUCT
1489
1490 set_thread_profiler(NULL);
1491 if (FlatProfiler::is_active()) {
1492 // This is where we would decide to either give each thread it's own profiler
1493 // or use one global one from FlatProfiler,
1494 // or up to some count of the number of profiled threads, etc.
1495 ThreadProfiler* pp = new ThreadProfiler();
1496 pp->engage();
1497 set_thread_profiler(pp);
1498 }
1499
1500 // Setup safepoint state info for this thread
1501 ThreadSafepointState::create(this);
1502
1503 debug_only(_java_call_counter = 0);
1504
1505 // JVMTI PopFrame support
1506 _popframe_condition = popframe_inactive;
1507 _popframe_preserved_args = NULL;
1508 _popframe_preserved_args_size = 0;
1509 _frames_to_pop_failed_realloc = 0;
1510
1511 pd_initialize();
1512 }
1513
1514 #if INCLUDE_ALL_GCS
1515 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1516 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1517 #endif // INCLUDE_ALL_GCS
1518
1519 JavaThread::JavaThread(bool is_attaching_via_jni) :
1520 Thread()
1521 #if INCLUDE_ALL_GCS
1522 , _satb_mark_queue(&_satb_mark_queue_set),
1523 _dirty_card_queue(&_dirty_card_queue_set)
1524 #endif // INCLUDE_ALL_GCS
1525 {
1526 initialize();
1527 if (is_attaching_via_jni) {
1528 _jni_attach_state = _attaching_via_jni;
1529 } else {
1530 _jni_attach_state = _not_attaching_via_jni;
1531 }
1532 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1533 }
1534
1535 bool JavaThread::reguard_stack(address cur_sp) {
1536 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1537 && _stack_guard_state != stack_guard_reserved_disabled) {
1538 return true; // Stack already guarded or guard pages not needed.
1539 }
1540
1541 if (register_stack_overflow()) {
1542 // For those architectures which have separate register and
1543 // memory stacks, we must check the register stack to see if
1544 // it has overflowed.
1545 return false;
1546 }
1547
1548 // Java code never executes within the yellow zone: the latter is only
1549 // there to provoke an exception during stack banging. If java code
1550 // is executing there, either StackShadowPages should be larger, or
1551 // some exception code in c1, c2 or the interpreter isn't unwinding
1552 // when it should.
1553 guarantee(cur_sp > stack_reserved_zone_base(),
1554 "not enough space to reguard - increase StackShadowPages");
1555 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1556 enable_stack_yellow_reserved_zone();
1557 if (reserved_stack_activation() != stack_base()) {
1558 set_reserved_stack_activation(stack_base());
1559 }
1560 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1561 set_reserved_stack_activation(stack_base());
1562 enable_stack_reserved_zone();
1563 }
1564 return true;
1565 }
1566
1567 bool JavaThread::reguard_stack(void) {
1568 return reguard_stack(os::current_stack_pointer());
1569 }
1570
1571
1572 void JavaThread::block_if_vm_exited() {
1573 if (_terminated == _vm_exited) {
1574 // _vm_exited is set at safepoint, and Threads_lock is never released
1575 // we will block here forever
1576 Threads_lock->lock_without_safepoint_check();
1577 ShouldNotReachHere();
1578 }
1579 }
1580
1581
1582 // Remove this ifdef when C1 is ported to the compiler interface.
1583 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1584 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1585
1586 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1587 Thread()
1588 #if INCLUDE_ALL_GCS
1589 , _satb_mark_queue(&_satb_mark_queue_set),
1590 _dirty_card_queue(&_dirty_card_queue_set)
1591 #endif // INCLUDE_ALL_GCS
1592 {
1593 initialize();
1594 _jni_attach_state = _not_attaching_via_jni;
1595 set_entry_point(entry_point);
1596 // Create the native thread itself.
1597 // %note runtime_23
1598 os::ThreadType thr_type = os::java_thread;
1599 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1600 os::java_thread;
1601 os::create_thread(this, thr_type, stack_sz);
1602 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1603 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1604 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1605 // the exception consists of creating the exception object & initializing it, initialization
1606 // will leave the VM via a JavaCall and then all locks must be unlocked).
1607 //
1608 // The thread is still suspended when we reach here. Thread must be explicit started
1609 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1610 // by calling Threads:add. The reason why this is not done here, is because the thread
1611 // object must be fully initialized (take a look at JVM_Start)
1612 }
1613
1614 JavaThread::~JavaThread() {
1615
1616 // JSR166 -- return the parker to the free list
1617 Parker::Release(_parker);
1618 _parker = NULL;
1619
1620 // Free any remaining previous UnrollBlock
1621 vframeArray* old_array = vframe_array_last();
1622
1623 if (old_array != NULL) {
1624 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1625 old_array->set_unroll_block(NULL);
1626 delete old_info;
1627 delete old_array;
1628 }
1629
1630 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1631 if (deferred != NULL) {
1632 // This can only happen if thread is destroyed before deoptimization occurs.
1633 assert(deferred->length() != 0, "empty array!");
1634 do {
1635 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1636 deferred->remove_at(0);
1637 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1638 delete dlv;
1639 } while (deferred->length() != 0);
1640 delete deferred;
1641 }
1642
1643 // All Java related clean up happens in exit
1644 ThreadSafepointState::destroy(this);
1645 if (_thread_profiler != NULL) delete _thread_profiler;
1646 if (_thread_stat != NULL) delete _thread_stat;
1647
1648 #if INCLUDE_JVMCI
1649 if (JVMCICounterSize > 0) {
1650 if (jvmci_counters_include(this)) {
1651 for (int i = 0; i < JVMCICounterSize; i++) {
1652 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1653 }
1654 }
1655 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1656 }
1657 #endif // INCLUDE_JVMCI
1658 }
1659
1660
1661 // The first routine called by a new Java thread
1662 void JavaThread::run() {
1663 // initialize thread-local alloc buffer related fields
1664 this->initialize_tlab();
1665
1666 // used to test validity of stack trace backs
1667 this->record_base_of_stack_pointer();
1668
1669 // Record real stack base and size.
1670 this->record_stack_base_and_size();
1671
1672 this->create_stack_guard_pages();
1673
1674 this->cache_global_variables();
1675
1676 // Thread is now sufficient initialized to be handled by the safepoint code as being
1677 // in the VM. Change thread state from _thread_new to _thread_in_vm
1678 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1679
1680 assert(JavaThread::current() == this, "sanity check");
1681 assert(!Thread::current()->owns_locks(), "sanity check");
1682
1683 DTRACE_THREAD_PROBE(start, this);
1684
1685 // This operation might block. We call that after all safepoint checks for a new thread has
1686 // been completed.
1687 this->set_active_handles(JNIHandleBlock::allocate_block());
1688
1689 if (JvmtiExport::should_post_thread_life()) {
1690 JvmtiExport::post_thread_start(this);
1691 }
1692
1693 EventThreadStart event;
1694 if (event.should_commit()) {
1695 event.set_thread(THREAD_TRACE_ID(this));
1696 event.commit();
1697 }
1698
1699 // We call another function to do the rest so we are sure that the stack addresses used
1700 // from there will be lower than the stack base just computed
1701 thread_main_inner();
1702
1703 // Note, thread is no longer valid at this point!
1704 }
1705
1706
1707 void JavaThread::thread_main_inner() {
1708 assert(JavaThread::current() == this, "sanity check");
1709 assert(this->threadObj() != NULL, "just checking");
1710
1711 // Execute thread entry point unless this thread has a pending exception
1712 // or has been stopped before starting.
1713 // Note: Due to JVM_StopThread we can have pending exceptions already!
1714 if (!this->has_pending_exception() &&
1715 !java_lang_Thread::is_stillborn(this->threadObj())) {
1716 {
1717 ResourceMark rm(this);
1718 this->set_native_thread_name(this->get_thread_name());
1719 }
1720 HandleMark hm(this);
1721 this->entry_point()(this, this);
1722 }
1723
1724 DTRACE_THREAD_PROBE(stop, this);
1725
1726 this->exit(false);
1727 delete this;
1728 }
1729
1730
1731 static void ensure_join(JavaThread* thread) {
1732 // We do not need to grap the Threads_lock, since we are operating on ourself.
1733 Handle threadObj(thread, thread->threadObj());
1734 assert(threadObj.not_null(), "java thread object must exist");
1735 ObjectLocker lock(threadObj, thread);
1736 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1737 thread->clear_pending_exception();
1738 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1739 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1740 // Clear the native thread instance - this makes isAlive return false and allows the join()
1741 // to complete once we've done the notify_all below
1742 java_lang_Thread::set_thread(threadObj(), NULL);
1743 lock.notify_all(thread);
1744 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1745 thread->clear_pending_exception();
1746 }
1747
1748
1749 // For any new cleanup additions, please check to see if they need to be applied to
1750 // cleanup_failed_attach_current_thread as well.
1751 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1752 assert(this == JavaThread::current(), "thread consistency check");
1753
1754 HandleMark hm(this);
1755 Handle uncaught_exception(this, this->pending_exception());
1756 this->clear_pending_exception();
1757 Handle threadObj(this, this->threadObj());
1758 assert(threadObj.not_null(), "Java thread object should be created");
1759
1760 if (get_thread_profiler() != NULL) {
1761 get_thread_profiler()->disengage();
1762 ResourceMark rm;
1763 get_thread_profiler()->print(get_thread_name());
1764 }
1765
1766
1767 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1768 {
1769 EXCEPTION_MARK;
1770
1771 CLEAR_PENDING_EXCEPTION;
1772 }
1773 if (!destroy_vm) {
1774 if (uncaught_exception.not_null()) {
1775 EXCEPTION_MARK;
1776 // Call method Thread.dispatchUncaughtException().
1777 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1778 JavaValue result(T_VOID);
1779 JavaCalls::call_virtual(&result,
1780 threadObj, thread_klass,
1781 vmSymbols::dispatchUncaughtException_name(),
1782 vmSymbols::throwable_void_signature(),
1783 uncaught_exception,
1784 THREAD);
1785 if (HAS_PENDING_EXCEPTION) {
1786 ResourceMark rm(this);
1787 jio_fprintf(defaultStream::error_stream(),
1788 "\nException: %s thrown from the UncaughtExceptionHandler"
1789 " in thread \"%s\"\n",
1790 pending_exception()->klass()->external_name(),
1791 get_thread_name());
1792 CLEAR_PENDING_EXCEPTION;
1793 }
1794 }
1795
1796 // Called before the java thread exit since we want to read info
1797 // from java_lang_Thread object
1798 EventThreadEnd event;
1799 if (event.should_commit()) {
1800 event.set_thread(THREAD_TRACE_ID(this));
1801 event.commit();
1802 }
1803
1804 // Call after last event on thread
1805 EVENT_THREAD_EXIT(this);
1806
1807 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1808 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1809 // is deprecated anyhow.
1810 if (!is_Compiler_thread()) {
1811 int count = 3;
1812 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1813 EXCEPTION_MARK;
1814 JavaValue result(T_VOID);
1815 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1816 JavaCalls::call_virtual(&result,
1817 threadObj, thread_klass,
1818 vmSymbols::exit_method_name(),
1819 vmSymbols::void_method_signature(),
1820 THREAD);
1821 CLEAR_PENDING_EXCEPTION;
1822 }
1823 }
1824 // notify JVMTI
1825 if (JvmtiExport::should_post_thread_life()) {
1826 JvmtiExport::post_thread_end(this);
1827 }
1828
1829 // We have notified the agents that we are exiting, before we go on,
1830 // we must check for a pending external suspend request and honor it
1831 // in order to not surprise the thread that made the suspend request.
1832 while (true) {
1833 {
1834 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1835 if (!is_external_suspend()) {
1836 set_terminated(_thread_exiting);
1837 ThreadService::current_thread_exiting(this);
1838 break;
1839 }
1840 // Implied else:
1841 // Things get a little tricky here. We have a pending external
1842 // suspend request, but we are holding the SR_lock so we
1843 // can't just self-suspend. So we temporarily drop the lock
1844 // and then self-suspend.
1845 }
1846
1847 ThreadBlockInVM tbivm(this);
1848 java_suspend_self();
1849
1850 // We're done with this suspend request, but we have to loop around
1851 // and check again. Eventually we will get SR_lock without a pending
1852 // external suspend request and will be able to mark ourselves as
1853 // exiting.
1854 }
1855 // no more external suspends are allowed at this point
1856 } else {
1857 // before_exit() has already posted JVMTI THREAD_END events
1858 }
1859
1860 // Notify waiters on thread object. This has to be done after exit() is called
1861 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1862 // group should have the destroyed bit set before waiters are notified).
1863 ensure_join(this);
1864 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1865
1866 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1867 // held by this thread must be released. The spec does not distinguish
1868 // between JNI-acquired and regular Java monitors. We can only see
1869 // regular Java monitors here if monitor enter-exit matching is broken.
1870 //
1871 // Optionally release any monitors for regular JavaThread exits. This
1872 // is provided as a work around for any bugs in monitor enter-exit
1873 // matching. This can be expensive so it is not enabled by default.
1874 //
1875 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1876 // ObjectSynchronizer::release_monitors_owned_by_thread().
1877 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1878 // Sanity check even though JNI DetachCurrentThread() would have
1879 // returned JNI_ERR if there was a Java frame. JavaThread exit
1880 // should be done executing Java code by the time we get here.
1881 assert(!this->has_last_Java_frame(),
1882 "should not have a Java frame when detaching or exiting");
1883 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1884 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1885 }
1886
1887 // These things needs to be done while we are still a Java Thread. Make sure that thread
1888 // is in a consistent state, in case GC happens
1889 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1890
1891 if (active_handles() != NULL) {
1892 JNIHandleBlock* block = active_handles();
1893 set_active_handles(NULL);
1894 JNIHandleBlock::release_block(block);
1895 }
1896
1897 if (free_handle_block() != NULL) {
1898 JNIHandleBlock* block = free_handle_block();
1899 set_free_handle_block(NULL);
1900 JNIHandleBlock::release_block(block);
1901 }
1902
1903 // These have to be removed while this is still a valid thread.
1904 remove_stack_guard_pages();
1905
1906 if (UseTLAB) {
1907 tlab().make_parsable(true); // retire TLAB
1908 }
1909
1910 if (JvmtiEnv::environments_might_exist()) {
1911 JvmtiExport::cleanup_thread(this);
1912 }
1913
1914 // We must flush any deferred card marks before removing a thread from
1915 // the list of active threads.
1916 Universe::heap()->flush_deferred_store_barrier(this);
1917 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1918
1919 #if INCLUDE_ALL_GCS
1920 // We must flush the G1-related buffers before removing a thread
1921 // from the list of active threads. We must do this after any deferred
1922 // card marks have been flushed (above) so that any entries that are
1923 // added to the thread's dirty card queue as a result are not lost.
1924 if (UseG1GC) {
1925 flush_barrier_queues();
1926 }
1927 #endif // INCLUDE_ALL_GCS
1928
1929 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1930 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1931 os::current_thread_id());
1932
1933 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1934 Threads::remove(this);
1935 }
1936
1937 #if INCLUDE_ALL_GCS
1938 // Flush G1-related queues.
1939 void JavaThread::flush_barrier_queues() {
1940 satb_mark_queue().flush();
1941 dirty_card_queue().flush();
1942 }
1943
1944 void JavaThread::initialize_queues() {
1945 assert(!SafepointSynchronize::is_at_safepoint(),
1946 "we should not be at a safepoint");
1947
1948 SATBMarkQueue& satb_queue = satb_mark_queue();
1949 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1950 // The SATB queue should have been constructed with its active
1951 // field set to false.
1952 assert(!satb_queue.is_active(), "SATB queue should not be active");
1953 assert(satb_queue.is_empty(), "SATB queue should be empty");
1954 // If we are creating the thread during a marking cycle, we should
1955 // set the active field of the SATB queue to true.
1956 if (satb_queue_set.is_active()) {
1957 satb_queue.set_active(true);
1958 }
1959
1960 DirtyCardQueue& dirty_queue = dirty_card_queue();
1961 // The dirty card queue should have been constructed with its
1962 // active field set to true.
1963 assert(dirty_queue.is_active(), "dirty card queue should be active");
1964 }
1965 #endif // INCLUDE_ALL_GCS
1966
1967 void JavaThread::cleanup_failed_attach_current_thread() {
1968 if (get_thread_profiler() != NULL) {
1969 get_thread_profiler()->disengage();
1970 ResourceMark rm;
1971 get_thread_profiler()->print(get_thread_name());
1972 }
1973
1974 if (active_handles() != NULL) {
1975 JNIHandleBlock* block = active_handles();
1976 set_active_handles(NULL);
1977 JNIHandleBlock::release_block(block);
1978 }
1979
1980 if (free_handle_block() != NULL) {
1981 JNIHandleBlock* block = free_handle_block();
1982 set_free_handle_block(NULL);
1983 JNIHandleBlock::release_block(block);
1984 }
1985
1986 // These have to be removed while this is still a valid thread.
1987 remove_stack_guard_pages();
1988
1989 if (UseTLAB) {
1990 tlab().make_parsable(true); // retire TLAB, if any
1991 }
1992
1993 #if INCLUDE_ALL_GCS
1994 if (UseG1GC) {
1995 flush_barrier_queues();
1996 }
1997 #endif // INCLUDE_ALL_GCS
1998
1999 Threads::remove(this);
2000 delete this;
2001 }
2002
2003
2004
2005
2006 JavaThread* JavaThread::active() {
2007 Thread* thread = Thread::current();
2008 if (thread->is_Java_thread()) {
2009 return (JavaThread*) thread;
2010 } else {
2011 assert(thread->is_VM_thread(), "this must be a vm thread");
2012 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2013 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2014 assert(ret->is_Java_thread(), "must be a Java thread");
2015 return ret;
2016 }
2017 }
2018
2019 bool JavaThread::is_lock_owned(address adr) const {
2020 if (Thread::is_lock_owned(adr)) return true;
2021
2022 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2023 if (chunk->contains(adr)) return true;
2024 }
2025
2026 return false;
2027 }
2028
2029
2030 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2031 chunk->set_next(monitor_chunks());
2032 set_monitor_chunks(chunk);
2033 }
2034
2035 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2036 guarantee(monitor_chunks() != NULL, "must be non empty");
2037 if (monitor_chunks() == chunk) {
2038 set_monitor_chunks(chunk->next());
2039 } else {
2040 MonitorChunk* prev = monitor_chunks();
2041 while (prev->next() != chunk) prev = prev->next();
2042 prev->set_next(chunk->next());
2043 }
2044 }
2045
2046 // JVM support.
2047
2048 // Note: this function shouldn't block if it's called in
2049 // _thread_in_native_trans state (such as from
2050 // check_special_condition_for_native_trans()).
2051 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2052
2053 if (has_last_Java_frame() && has_async_condition()) {
2054 // If we are at a polling page safepoint (not a poll return)
2055 // then we must defer async exception because live registers
2056 // will be clobbered by the exception path. Poll return is
2057 // ok because the call we a returning from already collides
2058 // with exception handling registers and so there is no issue.
2059 // (The exception handling path kills call result registers but
2060 // this is ok since the exception kills the result anyway).
2061
2062 if (is_at_poll_safepoint()) {
2063 // if the code we are returning to has deoptimized we must defer
2064 // the exception otherwise live registers get clobbered on the
2065 // exception path before deoptimization is able to retrieve them.
2066 //
2067 RegisterMap map(this, false);
2068 frame caller_fr = last_frame().sender(&map);
2069 assert(caller_fr.is_compiled_frame(), "what?");
2070 if (caller_fr.is_deoptimized_frame()) {
2071 log_info(exceptions)("deferred async exception at compiled safepoint");
2072 return;
2073 }
2074 }
2075 }
2076
2077 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2078 if (condition == _no_async_condition) {
2079 // Conditions have changed since has_special_runtime_exit_condition()
2080 // was called:
2081 // - if we were here only because of an external suspend request,
2082 // then that was taken care of above (or cancelled) so we are done
2083 // - if we were here because of another async request, then it has
2084 // been cleared between the has_special_runtime_exit_condition()
2085 // and now so again we are done
2086 return;
2087 }
2088
2089 // Check for pending async. exception
2090 if (_pending_async_exception != NULL) {
2091 // Only overwrite an already pending exception, if it is not a threadDeath.
2092 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2093
2094 // We cannot call Exceptions::_throw(...) here because we cannot block
2095 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2096
2097 if (log_is_enabled(Info, exceptions)) {
2098 ResourceMark rm;
2099 outputStream* logstream = Log(exceptions)::info_stream();
2100 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2101 if (has_last_Java_frame()) {
2102 frame f = last_frame();
2103 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2104 }
2105 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2106 }
2107 _pending_async_exception = NULL;
2108 clear_has_async_exception();
2109 }
2110 }
2111
2112 if (check_unsafe_error &&
2113 condition == _async_unsafe_access_error && !has_pending_exception()) {
2114 condition = _no_async_condition; // done
2115 switch (thread_state()) {
2116 case _thread_in_vm: {
2117 JavaThread* THREAD = this;
2118 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2119 }
2120 case _thread_in_native: {
2121 ThreadInVMfromNative tiv(this);
2122 JavaThread* THREAD = this;
2123 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2124 }
2125 case _thread_in_Java: {
2126 ThreadInVMfromJava tiv(this);
2127 JavaThread* THREAD = this;
2128 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2129 }
2130 default:
2131 ShouldNotReachHere();
2132 }
2133 }
2134
2135 assert(condition == _no_async_condition || has_pending_exception() ||
2136 (!check_unsafe_error && condition == _async_unsafe_access_error),
2137 "must have handled the async condition, if no exception");
2138 }
2139
2140 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2141 //
2142 // Check for pending external suspend. Internal suspend requests do
2143 // not use handle_special_runtime_exit_condition().
2144 // If JNIEnv proxies are allowed, don't self-suspend if the target
2145 // thread is not the current thread. In older versions of jdbx, jdbx
2146 // threads could call into the VM with another thread's JNIEnv so we
2147 // can be here operating on behalf of a suspended thread (4432884).
2148 bool do_self_suspend = is_external_suspend_with_lock();
2149 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2150 //
2151 // Because thread is external suspended the safepoint code will count
2152 // thread as at a safepoint. This can be odd because we can be here
2153 // as _thread_in_Java which would normally transition to _thread_blocked
2154 // at a safepoint. We would like to mark the thread as _thread_blocked
2155 // before calling java_suspend_self like all other callers of it but
2156 // we must then observe proper safepoint protocol. (We can't leave
2157 // _thread_blocked with a safepoint in progress). However we can be
2158 // here as _thread_in_native_trans so we can't use a normal transition
2159 // constructor/destructor pair because they assert on that type of
2160 // transition. We could do something like:
2161 //
2162 // JavaThreadState state = thread_state();
2163 // set_thread_state(_thread_in_vm);
2164 // {
2165 // ThreadBlockInVM tbivm(this);
2166 // java_suspend_self()
2167 // }
2168 // set_thread_state(_thread_in_vm_trans);
2169 // if (safepoint) block;
2170 // set_thread_state(state);
2171 //
2172 // but that is pretty messy. Instead we just go with the way the
2173 // code has worked before and note that this is the only path to
2174 // java_suspend_self that doesn't put the thread in _thread_blocked
2175 // mode.
2176
2177 frame_anchor()->make_walkable(this);
2178 java_suspend_self();
2179
2180 // We might be here for reasons in addition to the self-suspend request
2181 // so check for other async requests.
2182 }
2183
2184 if (check_asyncs) {
2185 check_and_handle_async_exceptions();
2186 }
2187 }
2188
2189 void JavaThread::send_thread_stop(oop java_throwable) {
2190 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2191 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2192 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2193
2194 // Do not throw asynchronous exceptions against the compiler thread
2195 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2196 if (!can_call_java()) return;
2197
2198 {
2199 // Actually throw the Throwable against the target Thread - however
2200 // only if there is no thread death exception installed already.
2201 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2202 // If the topmost frame is a runtime stub, then we are calling into
2203 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2204 // must deoptimize the caller before continuing, as the compiled exception handler table
2205 // may not be valid
2206 if (has_last_Java_frame()) {
2207 frame f = last_frame();
2208 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2209 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2210 RegisterMap reg_map(this, UseBiasedLocking);
2211 frame compiled_frame = f.sender(®_map);
2212 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2213 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2214 }
2215 }
2216 }
2217
2218 // Set async. pending exception in thread.
2219 set_pending_async_exception(java_throwable);
2220
2221 if (log_is_enabled(Info, exceptions)) {
2222 ResourceMark rm;
2223 log_info(exceptions)("Pending Async. exception installed of type: %s",
2224 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2225 }
2226 // for AbortVMOnException flag
2227 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2228 }
2229 }
2230
2231
2232 // Interrupt thread so it will wake up from a potential wait()
2233 Thread::interrupt(this);
2234 }
2235
2236 // External suspension mechanism.
2237 //
2238 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2239 // to any VM_locks and it is at a transition
2240 // Self-suspension will happen on the transition out of the vm.
2241 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2242 //
2243 // Guarantees on return:
2244 // + Target thread will not execute any new bytecode (that's why we need to
2245 // force a safepoint)
2246 // + Target thread will not enter any new monitors
2247 //
2248 void JavaThread::java_suspend() {
2249 { MutexLocker mu(Threads_lock);
2250 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2251 return;
2252 }
2253 }
2254
2255 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2256 if (!is_external_suspend()) {
2257 // a racing resume has cancelled us; bail out now
2258 return;
2259 }
2260
2261 // suspend is done
2262 uint32_t debug_bits = 0;
2263 // Warning: is_ext_suspend_completed() may temporarily drop the
2264 // SR_lock to allow the thread to reach a stable thread state if
2265 // it is currently in a transient thread state.
2266 if (is_ext_suspend_completed(false /* !called_by_wait */,
2267 SuspendRetryDelay, &debug_bits)) {
2268 return;
2269 }
2270 }
2271
2272 VM_ForceSafepoint vm_suspend;
2273 VMThread::execute(&vm_suspend);
2274 }
2275
2276 // Part II of external suspension.
2277 // A JavaThread self suspends when it detects a pending external suspend
2278 // request. This is usually on transitions. It is also done in places
2279 // where continuing to the next transition would surprise the caller,
2280 // e.g., monitor entry.
2281 //
2282 // Returns the number of times that the thread self-suspended.
2283 //
2284 // Note: DO NOT call java_suspend_self() when you just want to block current
2285 // thread. java_suspend_self() is the second stage of cooperative
2286 // suspension for external suspend requests and should only be used
2287 // to complete an external suspend request.
2288 //
2289 int JavaThread::java_suspend_self() {
2290 int ret = 0;
2291
2292 // we are in the process of exiting so don't suspend
2293 if (is_exiting()) {
2294 clear_external_suspend();
2295 return ret;
2296 }
2297
2298 assert(_anchor.walkable() ||
2299 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2300 "must have walkable stack");
2301
2302 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2303
2304 assert(!this->is_ext_suspended(),
2305 "a thread trying to self-suspend should not already be suspended");
2306
2307 if (this->is_suspend_equivalent()) {
2308 // If we are self-suspending as a result of the lifting of a
2309 // suspend equivalent condition, then the suspend_equivalent
2310 // flag is not cleared until we set the ext_suspended flag so
2311 // that wait_for_ext_suspend_completion() returns consistent
2312 // results.
2313 this->clear_suspend_equivalent();
2314 }
2315
2316 // A racing resume may have cancelled us before we grabbed SR_lock
2317 // above. Or another external suspend request could be waiting for us
2318 // by the time we return from SR_lock()->wait(). The thread
2319 // that requested the suspension may already be trying to walk our
2320 // stack and if we return now, we can change the stack out from under
2321 // it. This would be a "bad thing (TM)" and cause the stack walker
2322 // to crash. We stay self-suspended until there are no more pending
2323 // external suspend requests.
2324 while (is_external_suspend()) {
2325 ret++;
2326 this->set_ext_suspended();
2327
2328 // _ext_suspended flag is cleared by java_resume()
2329 while (is_ext_suspended()) {
2330 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2331 }
2332 }
2333
2334 return ret;
2335 }
2336
2337 #ifdef ASSERT
2338 // verify the JavaThread has not yet been published in the Threads::list, and
2339 // hence doesn't need protection from concurrent access at this stage
2340 void JavaThread::verify_not_published() {
2341 if (!Threads_lock->owned_by_self()) {
2342 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2343 assert(!Threads::includes(this),
2344 "java thread shouldn't have been published yet!");
2345 } else {
2346 assert(!Threads::includes(this),
2347 "java thread shouldn't have been published yet!");
2348 }
2349 }
2350 #endif
2351
2352 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2353 // progress or when _suspend_flags is non-zero.
2354 // Current thread needs to self-suspend if there is a suspend request and/or
2355 // block if a safepoint is in progress.
2356 // Async exception ISN'T checked.
2357 // Note only the ThreadInVMfromNative transition can call this function
2358 // directly and when thread state is _thread_in_native_trans
2359 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2360 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2361
2362 JavaThread *curJT = JavaThread::current();
2363 bool do_self_suspend = thread->is_external_suspend();
2364
2365 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2366
2367 // If JNIEnv proxies are allowed, don't self-suspend if the target
2368 // thread is not the current thread. In older versions of jdbx, jdbx
2369 // threads could call into the VM with another thread's JNIEnv so we
2370 // can be here operating on behalf of a suspended thread (4432884).
2371 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2372 JavaThreadState state = thread->thread_state();
2373
2374 // We mark this thread_blocked state as a suspend-equivalent so
2375 // that a caller to is_ext_suspend_completed() won't be confused.
2376 // The suspend-equivalent state is cleared by java_suspend_self().
2377 thread->set_suspend_equivalent();
2378
2379 // If the safepoint code sees the _thread_in_native_trans state, it will
2380 // wait until the thread changes to other thread state. There is no
2381 // guarantee on how soon we can obtain the SR_lock and complete the
2382 // self-suspend request. It would be a bad idea to let safepoint wait for
2383 // too long. Temporarily change the state to _thread_blocked to
2384 // let the VM thread know that this thread is ready for GC. The problem
2385 // of changing thread state is that safepoint could happen just after
2386 // java_suspend_self() returns after being resumed, and VM thread will
2387 // see the _thread_blocked state. We must check for safepoint
2388 // after restoring the state and make sure we won't leave while a safepoint
2389 // is in progress.
2390 thread->set_thread_state(_thread_blocked);
2391 thread->java_suspend_self();
2392 thread->set_thread_state(state);
2393 // Make sure new state is seen by VM thread
2394 if (os::is_MP()) {
2395 if (UseMembar) {
2396 // Force a fence between the write above and read below
2397 OrderAccess::fence();
2398 } else {
2399 // Must use this rather than serialization page in particular on Windows
2400 InterfaceSupport::serialize_memory(thread);
2401 }
2402 }
2403 }
2404
2405 if (SafepointSynchronize::do_call_back()) {
2406 // If we are safepointing, then block the caller which may not be
2407 // the same as the target thread (see above).
2408 SafepointSynchronize::block(curJT);
2409 }
2410
2411 if (thread->is_deopt_suspend()) {
2412 thread->clear_deopt_suspend();
2413 RegisterMap map(thread, false);
2414 frame f = thread->last_frame();
2415 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2416 f = f.sender(&map);
2417 }
2418 if (f.id() == thread->must_deopt_id()) {
2419 thread->clear_must_deopt_id();
2420 f.deoptimize(thread);
2421 } else {
2422 fatal("missed deoptimization!");
2423 }
2424 }
2425 }
2426
2427 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2428 // progress or when _suspend_flags is non-zero.
2429 // Current thread needs to self-suspend if there is a suspend request and/or
2430 // block if a safepoint is in progress.
2431 // Also check for pending async exception (not including unsafe access error).
2432 // Note only the native==>VM/Java barriers can call this function and when
2433 // thread state is _thread_in_native_trans.
2434 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2435 check_safepoint_and_suspend_for_native_trans(thread);
2436
2437 if (thread->has_async_exception()) {
2438 // We are in _thread_in_native_trans state, don't handle unsafe
2439 // access error since that may block.
2440 thread->check_and_handle_async_exceptions(false);
2441 }
2442 }
2443
2444 // This is a variant of the normal
2445 // check_special_condition_for_native_trans with slightly different
2446 // semantics for use by critical native wrappers. It does all the
2447 // normal checks but also performs the transition back into
2448 // thread_in_Java state. This is required so that critical natives
2449 // can potentially block and perform a GC if they are the last thread
2450 // exiting the GCLocker.
2451 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2452 check_special_condition_for_native_trans(thread);
2453
2454 // Finish the transition
2455 thread->set_thread_state(_thread_in_Java);
2456
2457 if (thread->do_critical_native_unlock()) {
2458 ThreadInVMfromJavaNoAsyncException tiv(thread);
2459 GCLocker::unlock_critical(thread);
2460 thread->clear_critical_native_unlock();
2461 }
2462 }
2463
2464 // We need to guarantee the Threads_lock here, since resumes are not
2465 // allowed during safepoint synchronization
2466 // Can only resume from an external suspension
2467 void JavaThread::java_resume() {
2468 assert_locked_or_safepoint(Threads_lock);
2469
2470 // Sanity check: thread is gone, has started exiting or the thread
2471 // was not externally suspended.
2472 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2473 return;
2474 }
2475
2476 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2477
2478 clear_external_suspend();
2479
2480 if (is_ext_suspended()) {
2481 clear_ext_suspended();
2482 SR_lock()->notify_all();
2483 }
2484 }
2485
2486 size_t JavaThread::_stack_red_zone_size = 0;
2487 size_t JavaThread::_stack_yellow_zone_size = 0;
2488 size_t JavaThread::_stack_reserved_zone_size = 0;
2489 size_t JavaThread::_stack_shadow_zone_size = 0;
2490
2491 void JavaThread::create_stack_guard_pages() {
2492 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2493 address low_addr = stack_end();
2494 size_t len = stack_guard_zone_size();
2495
2496 int allocate = os::allocate_stack_guard_pages();
2497 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2498
2499 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2500 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2501 return;
2502 }
2503
2504 if (os::guard_memory((char *) low_addr, len)) {
2505 _stack_guard_state = stack_guard_enabled;
2506 } else {
2507 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2508 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2509 if (os::uncommit_memory((char *) low_addr, len)) {
2510 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2511 }
2512 return;
2513 }
2514
2515 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2516 PTR_FORMAT "-" PTR_FORMAT ".",
2517 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2518
2519 }
2520
2521 void JavaThread::remove_stack_guard_pages() {
2522 assert(Thread::current() == this, "from different thread");
2523 if (_stack_guard_state == stack_guard_unused) return;
2524 address low_addr = stack_end();
2525 size_t len = stack_guard_zone_size();
2526
2527 if (os::allocate_stack_guard_pages()) {
2528 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2529 _stack_guard_state = stack_guard_unused;
2530 } else {
2531 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2532 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2533 return;
2534 }
2535 } else {
2536 if (_stack_guard_state == stack_guard_unused) return;
2537 if (os::unguard_memory((char *) low_addr, len)) {
2538 _stack_guard_state = stack_guard_unused;
2539 } else {
2540 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2541 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2542 return;
2543 }
2544 }
2545
2546 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2547 PTR_FORMAT "-" PTR_FORMAT ".",
2548 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2549
2550 }
2551
2552 void JavaThread::enable_stack_reserved_zone() {
2553 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2554 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2555
2556 // The base notation is from the stack's point of view, growing downward.
2557 // We need to adjust it to work correctly with guard_memory()
2558 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2559
2560 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2561 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2562
2563 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2564 _stack_guard_state = stack_guard_enabled;
2565 } else {
2566 warning("Attempt to guard stack reserved zone failed.");
2567 }
2568 enable_register_stack_guard();
2569 }
2570
2571 void JavaThread::disable_stack_reserved_zone() {
2572 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2573 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2574
2575 // Simply return if called for a thread that does not use guard pages.
2576 if (_stack_guard_state == stack_guard_unused) return;
2577
2578 // The base notation is from the stack's point of view, growing downward.
2579 // We need to adjust it to work correctly with guard_memory()
2580 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2581
2582 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2583 _stack_guard_state = stack_guard_reserved_disabled;
2584 } else {
2585 warning("Attempt to unguard stack reserved zone failed.");
2586 }
2587 disable_register_stack_guard();
2588 }
2589
2590 void JavaThread::enable_stack_yellow_reserved_zone() {
2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2592 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2593
2594 // The base notation is from the stacks point of view, growing downward.
2595 // We need to adjust it to work correctly with guard_memory()
2596 address base = stack_red_zone_base();
2597
2598 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2599 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2600
2601 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2602 _stack_guard_state = stack_guard_enabled;
2603 } else {
2604 warning("Attempt to guard stack yellow zone failed.");
2605 }
2606 enable_register_stack_guard();
2607 }
2608
2609 void JavaThread::disable_stack_yellow_reserved_zone() {
2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2611 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2612
2613 // Simply return if called for a thread that does not use guard pages.
2614 if (_stack_guard_state == stack_guard_unused) return;
2615
2616 // The base notation is from the stacks point of view, growing downward.
2617 // We need to adjust it to work correctly with guard_memory()
2618 address base = stack_red_zone_base();
2619
2620 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2621 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2622 } else {
2623 warning("Attempt to unguard stack yellow zone failed.");
2624 }
2625 disable_register_stack_guard();
2626 }
2627
2628 void JavaThread::enable_stack_red_zone() {
2629 // The base notation is from the stacks point of view, growing downward.
2630 // We need to adjust it to work correctly with guard_memory()
2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2632 address base = stack_red_zone_base() - stack_red_zone_size();
2633
2634 guarantee(base < stack_base(), "Error calculating stack red zone");
2635 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2636
2637 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2638 warning("Attempt to guard stack red zone failed.");
2639 }
2640 }
2641
2642 void JavaThread::disable_stack_red_zone() {
2643 // The base notation is from the stacks point of view, growing downward.
2644 // We need to adjust it to work correctly with guard_memory()
2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2646 address base = stack_red_zone_base() - stack_red_zone_size();
2647 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2648 warning("Attempt to unguard stack red zone failed.");
2649 }
2650 }
2651
2652 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2653 // ignore is there is no stack
2654 if (!has_last_Java_frame()) return;
2655 // traverse the stack frames. Starts from top frame.
2656 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2657 frame* fr = fst.current();
2658 f(fr, fst.register_map());
2659 }
2660 }
2661
2662
2663 #ifndef PRODUCT
2664 // Deoptimization
2665 // Function for testing deoptimization
2666 void JavaThread::deoptimize() {
2667 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2668 StackFrameStream fst(this, UseBiasedLocking);
2669 bool deopt = false; // Dump stack only if a deopt actually happens.
2670 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2671 // Iterate over all frames in the thread and deoptimize
2672 for (; !fst.is_done(); fst.next()) {
2673 if (fst.current()->can_be_deoptimized()) {
2674
2675 if (only_at) {
2676 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2677 // consists of comma or carriage return separated numbers so
2678 // search for the current bci in that string.
2679 address pc = fst.current()->pc();
2680 nmethod* nm = (nmethod*) fst.current()->cb();
2681 ScopeDesc* sd = nm->scope_desc_at(pc);
2682 char buffer[8];
2683 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2684 size_t len = strlen(buffer);
2685 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2686 while (found != NULL) {
2687 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2688 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2689 // Check that the bci found is bracketed by terminators.
2690 break;
2691 }
2692 found = strstr(found + 1, buffer);
2693 }
2694 if (!found) {
2695 continue;
2696 }
2697 }
2698
2699 if (DebugDeoptimization && !deopt) {
2700 deopt = true; // One-time only print before deopt
2701 tty->print_cr("[BEFORE Deoptimization]");
2702 trace_frames();
2703 trace_stack();
2704 }
2705 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2706 }
2707 }
2708
2709 if (DebugDeoptimization && deopt) {
2710 tty->print_cr("[AFTER Deoptimization]");
2711 trace_frames();
2712 }
2713 }
2714
2715
2716 // Make zombies
2717 void JavaThread::make_zombies() {
2718 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2719 if (fst.current()->can_be_deoptimized()) {
2720 // it is a Java nmethod
2721 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2722 nm->make_not_entrant();
2723 }
2724 }
2725 }
2726 #endif // PRODUCT
2727
2728
2729 void JavaThread::deoptimized_wrt_marked_nmethods() {
2730 if (!has_last_Java_frame()) return;
2731 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2732 StackFrameStream fst(this, UseBiasedLocking);
2733 for (; !fst.is_done(); fst.next()) {
2734 if (fst.current()->should_be_deoptimized()) {
2735 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2736 }
2737 }
2738 }
2739
2740
2741 // If the caller is a NamedThread, then remember, in the current scope,
2742 // the given JavaThread in its _processed_thread field.
2743 class RememberProcessedThread: public StackObj {
2744 NamedThread* _cur_thr;
2745 public:
2746 RememberProcessedThread(JavaThread* jthr) {
2747 Thread* thread = Thread::current();
2748 if (thread->is_Named_thread()) {
2749 _cur_thr = (NamedThread *)thread;
2750 _cur_thr->set_processed_thread(jthr);
2751 } else {
2752 _cur_thr = NULL;
2753 }
2754 }
2755
2756 ~RememberProcessedThread() {
2757 if (_cur_thr) {
2758 _cur_thr->set_processed_thread(NULL);
2759 }
2760 }
2761 };
2762
2763 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2764 // Verify that the deferred card marks have been flushed.
2765 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2766
2767 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2768 // since there may be more than one thread using each ThreadProfiler.
2769
2770 // Traverse the GCHandles
2771 Thread::oops_do(f, cf);
2772
2773 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2774
2775 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2776 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2777
2778 if (has_last_Java_frame()) {
2779 // Record JavaThread to GC thread
2780 RememberProcessedThread rpt(this);
2781
2782 // Traverse the privileged stack
2783 if (_privileged_stack_top != NULL) {
2784 _privileged_stack_top->oops_do(f);
2785 }
2786
2787 // traverse the registered growable array
2788 if (_array_for_gc != NULL) {
2789 for (int index = 0; index < _array_for_gc->length(); index++) {
2790 f->do_oop(_array_for_gc->adr_at(index));
2791 }
2792 }
2793
2794 // Traverse the monitor chunks
2795 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2796 chunk->oops_do(f);
2797 }
2798
2799 // Traverse the execution stack
2800 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2801 fst.current()->oops_do(f, cf, fst.register_map());
2802 }
2803 }
2804
2805 // callee_target is never live across a gc point so NULL it here should
2806 // it still contain a methdOop.
2807
2808 set_callee_target(NULL);
2809
2810 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2811 // If we have deferred set_locals there might be oops waiting to be
2812 // written
2813 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2814 if (list != NULL) {
2815 for (int i = 0; i < list->length(); i++) {
2816 list->at(i)->oops_do(f);
2817 }
2818 }
2819
2820 // Traverse instance variables at the end since the GC may be moving things
2821 // around using this function
2822 f->do_oop((oop*) &_threadObj);
2823 f->do_oop((oop*) &_vm_result);
2824 f->do_oop((oop*) &_exception_oop);
2825 f->do_oop((oop*) &_pending_async_exception);
2826
2827 if (jvmti_thread_state() != NULL) {
2828 jvmti_thread_state()->oops_do(f);
2829 }
2830 }
2831
2832 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2833 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2835
2836 if (has_last_Java_frame()) {
2837 // Traverse the execution stack
2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2839 fst.current()->nmethods_do(cf);
2840 }
2841 }
2842 }
2843
2844 void JavaThread::metadata_do(void f(Metadata*)) {
2845 if (has_last_Java_frame()) {
2846 // Traverse the execution stack to call f() on the methods in the stack
2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2848 fst.current()->metadata_do(f);
2849 }
2850 } else if (is_Compiler_thread()) {
2851 // need to walk ciMetadata in current compile tasks to keep alive.
2852 CompilerThread* ct = (CompilerThread*)this;
2853 if (ct->env() != NULL) {
2854 ct->env()->metadata_do(f);
2855 }
2856 if (ct->task() != NULL) {
2857 ct->task()->metadata_do(f);
2858 }
2859 }
2860 }
2861
2862 // Printing
2863 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2864 switch (_thread_state) {
2865 case _thread_uninitialized: return "_thread_uninitialized";
2866 case _thread_new: return "_thread_new";
2867 case _thread_new_trans: return "_thread_new_trans";
2868 case _thread_in_native: return "_thread_in_native";
2869 case _thread_in_native_trans: return "_thread_in_native_trans";
2870 case _thread_in_vm: return "_thread_in_vm";
2871 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2872 case _thread_in_Java: return "_thread_in_Java";
2873 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2874 case _thread_blocked: return "_thread_blocked";
2875 case _thread_blocked_trans: return "_thread_blocked_trans";
2876 default: return "unknown thread state";
2877 }
2878 }
2879
2880 #ifndef PRODUCT
2881 void JavaThread::print_thread_state_on(outputStream *st) const {
2882 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2883 };
2884 void JavaThread::print_thread_state() const {
2885 print_thread_state_on(tty);
2886 }
2887 #endif // PRODUCT
2888
2889 // Called by Threads::print() for VM_PrintThreads operation
2890 void JavaThread::print_on(outputStream *st) const {
2891 st->print_raw("\"");
2892 st->print_raw(get_thread_name());
2893 st->print_raw("\" ");
2894 oop thread_oop = threadObj();
2895 if (thread_oop != NULL) {
2896 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2897 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2898 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2899 }
2900 Thread::print_on(st);
2901 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2902 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2903 if (thread_oop != NULL) {
2904 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2905 }
2906 #ifndef PRODUCT
2907 print_thread_state_on(st);
2908 _safepoint_state->print_on(st);
2909 #endif // PRODUCT
2910 if (is_Compiler_thread()) {
2911 CompilerThread* ct = (CompilerThread*)this;
2912 if (ct->task() != NULL) {
2913 st->print(" Compiling: ");
2914 ct->task()->print(st, NULL, true, false);
2915 } else {
2916 st->print(" No compile task");
2917 }
2918 st->cr();
2919 }
2920 }
2921
2922 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2923 st->print("%s", get_thread_name_string(buf, buflen));
2924 }
2925
2926 // Called by fatal error handler. The difference between this and
2927 // JavaThread::print() is that we can't grab lock or allocate memory.
2928 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2929 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2930 oop thread_obj = threadObj();
2931 if (thread_obj != NULL) {
2932 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2933 }
2934 st->print(" [");
2935 st->print("%s", _get_thread_state_name(_thread_state));
2936 if (osthread()) {
2937 st->print(", id=%d", osthread()->thread_id());
2938 }
2939 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2940 p2i(stack_end()), p2i(stack_base()));
2941 st->print("]");
2942 return;
2943 }
2944
2945 // Verification
2946
2947 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2948
2949 void JavaThread::verify() {
2950 // Verify oops in the thread.
2951 oops_do(&VerifyOopClosure::verify_oop, NULL);
2952
2953 // Verify the stack frames.
2954 frames_do(frame_verify);
2955 }
2956
2957 // CR 6300358 (sub-CR 2137150)
2958 // Most callers of this method assume that it can't return NULL but a
2959 // thread may not have a name whilst it is in the process of attaching to
2960 // the VM - see CR 6412693, and there are places where a JavaThread can be
2961 // seen prior to having it's threadObj set (eg JNI attaching threads and
2962 // if vm exit occurs during initialization). These cases can all be accounted
2963 // for such that this method never returns NULL.
2964 const char* JavaThread::get_thread_name() const {
2965 #ifdef ASSERT
2966 // early safepoints can hit while current thread does not yet have TLS
2967 if (!SafepointSynchronize::is_at_safepoint()) {
2968 Thread *cur = Thread::current();
2969 if (!(cur->is_Java_thread() && cur == this)) {
2970 // Current JavaThreads are allowed to get their own name without
2971 // the Threads_lock.
2972 assert_locked_or_safepoint(Threads_lock);
2973 }
2974 }
2975 #endif // ASSERT
2976 return get_thread_name_string();
2977 }
2978
2979 // Returns a non-NULL representation of this thread's name, or a suitable
2980 // descriptive string if there is no set name
2981 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2982 const char* name_str;
2983 oop thread_obj = threadObj();
2984 if (thread_obj != NULL) {
2985 oop name = java_lang_Thread::name(thread_obj);
2986 if (name != NULL) {
2987 if (buf == NULL) {
2988 name_str = java_lang_String::as_utf8_string(name);
2989 } else {
2990 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2991 }
2992 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2993 name_str = "<no-name - thread is attaching>";
2994 } else {
2995 name_str = Thread::name();
2996 }
2997 } else {
2998 name_str = Thread::name();
2999 }
3000 assert(name_str != NULL, "unexpected NULL thread name");
3001 return name_str;
3002 }
3003
3004
3005 const char* JavaThread::get_threadgroup_name() const {
3006 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3007 oop thread_obj = threadObj();
3008 if (thread_obj != NULL) {
3009 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3010 if (thread_group != NULL) {
3011 // ThreadGroup.name can be null
3012 return java_lang_ThreadGroup::name(thread_group);
3013 }
3014 }
3015 return NULL;
3016 }
3017
3018 const char* JavaThread::get_parent_name() const {
3019 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3020 oop thread_obj = threadObj();
3021 if (thread_obj != NULL) {
3022 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3023 if (thread_group != NULL) {
3024 oop parent = java_lang_ThreadGroup::parent(thread_group);
3025 if (parent != NULL) {
3026 // ThreadGroup.name can be null
3027 return java_lang_ThreadGroup::name(parent);
3028 }
3029 }
3030 }
3031 return NULL;
3032 }
3033
3034 ThreadPriority JavaThread::java_priority() const {
3035 oop thr_oop = threadObj();
3036 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3037 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3038 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3039 return priority;
3040 }
3041
3042 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3043
3044 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3045 // Link Java Thread object <-> C++ Thread
3046
3047 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3048 // and put it into a new Handle. The Handle "thread_oop" can then
3049 // be used to pass the C++ thread object to other methods.
3050
3051 // Set the Java level thread object (jthread) field of the
3052 // new thread (a JavaThread *) to C++ thread object using the
3053 // "thread_oop" handle.
3054
3055 // Set the thread field (a JavaThread *) of the
3056 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3057
3058 Handle thread_oop(Thread::current(),
3059 JNIHandles::resolve_non_null(jni_thread));
3060 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3061 "must be initialized");
3062 set_threadObj(thread_oop());
3063 java_lang_Thread::set_thread(thread_oop(), this);
3064
3065 if (prio == NoPriority) {
3066 prio = java_lang_Thread::priority(thread_oop());
3067 assert(prio != NoPriority, "A valid priority should be present");
3068 }
3069
3070 // Push the Java priority down to the native thread; needs Threads_lock
3071 Thread::set_priority(this, prio);
3072
3073 prepare_ext();
3074
3075 // Add the new thread to the Threads list and set it in motion.
3076 // We must have threads lock in order to call Threads::add.
3077 // It is crucial that we do not block before the thread is
3078 // added to the Threads list for if a GC happens, then the java_thread oop
3079 // will not be visited by GC.
3080 Threads::add(this);
3081 }
3082
3083 oop JavaThread::current_park_blocker() {
3084 // Support for JSR-166 locks
3085 oop thread_oop = threadObj();
3086 if (thread_oop != NULL &&
3087 JDK_Version::current().supports_thread_park_blocker()) {
3088 return java_lang_Thread::park_blocker(thread_oop);
3089 }
3090 return NULL;
3091 }
3092
3093
3094 void JavaThread::print_stack_on(outputStream* st) {
3095 if (!has_last_Java_frame()) return;
3096 ResourceMark rm;
3097 HandleMark hm;
3098
3099 RegisterMap reg_map(this);
3100 vframe* start_vf = last_java_vframe(®_map);
3101 int count = 0;
3102 for (vframe* f = start_vf; f; f = f->sender()) {
3103 if (f->is_java_frame()) {
3104 javaVFrame* jvf = javaVFrame::cast(f);
3105 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3106
3107 // Print out lock information
3108 if (JavaMonitorsInStackTrace) {
3109 jvf->print_lock_info_on(st, count);
3110 }
3111 } else {
3112 // Ignore non-Java frames
3113 }
3114
3115 // Bail-out case for too deep stacks
3116 count++;
3117 if (MaxJavaStackTraceDepth == count) return;
3118 }
3119 }
3120
3121
3122 // JVMTI PopFrame support
3123 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3124 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3125 if (in_bytes(size_in_bytes) != 0) {
3126 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3127 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3128 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3129 }
3130 }
3131
3132 void* JavaThread::popframe_preserved_args() {
3133 return _popframe_preserved_args;
3134 }
3135
3136 ByteSize JavaThread::popframe_preserved_args_size() {
3137 return in_ByteSize(_popframe_preserved_args_size);
3138 }
3139
3140 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3141 int sz = in_bytes(popframe_preserved_args_size());
3142 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3143 return in_WordSize(sz / wordSize);
3144 }
3145
3146 void JavaThread::popframe_free_preserved_args() {
3147 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3148 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3149 _popframe_preserved_args = NULL;
3150 _popframe_preserved_args_size = 0;
3151 }
3152
3153 #ifndef PRODUCT
3154
3155 void JavaThread::trace_frames() {
3156 tty->print_cr("[Describe stack]");
3157 int frame_no = 1;
3158 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3159 tty->print(" %d. ", frame_no++);
3160 fst.current()->print_value_on(tty, this);
3161 tty->cr();
3162 }
3163 }
3164
3165 class PrintAndVerifyOopClosure: public OopClosure {
3166 protected:
3167 template <class T> inline void do_oop_work(T* p) {
3168 oop obj = oopDesc::load_decode_heap_oop(p);
3169 if (obj == NULL) return;
3170 tty->print(INTPTR_FORMAT ": ", p2i(p));
3171 if (obj->is_oop_or_null()) {
3172 if (obj->is_objArray()) {
3173 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3174 } else {
3175 obj->print();
3176 }
3177 } else {
3178 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3179 }
3180 tty->cr();
3181 }
3182 public:
3183 virtual void do_oop(oop* p) { do_oop_work(p); }
3184 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3185 };
3186
3187
3188 static void oops_print(frame* f, const RegisterMap *map) {
3189 PrintAndVerifyOopClosure print;
3190 f->print_value();
3191 f->oops_do(&print, NULL, (RegisterMap*)map);
3192 }
3193
3194 // Print our all the locations that contain oops and whether they are
3195 // valid or not. This useful when trying to find the oldest frame
3196 // where an oop has gone bad since the frame walk is from youngest to
3197 // oldest.
3198 void JavaThread::trace_oops() {
3199 tty->print_cr("[Trace oops]");
3200 frames_do(oops_print);
3201 }
3202
3203
3204 #ifdef ASSERT
3205 // Print or validate the layout of stack frames
3206 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3207 ResourceMark rm;
3208 PRESERVE_EXCEPTION_MARK;
3209 FrameValues values;
3210 int frame_no = 0;
3211 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3212 fst.current()->describe(values, ++frame_no);
3213 if (depth == frame_no) break;
3214 }
3215 if (validate_only) {
3216 values.validate();
3217 } else {
3218 tty->print_cr("[Describe stack layout]");
3219 values.print(this);
3220 }
3221 }
3222 #endif
3223
3224 void JavaThread::trace_stack_from(vframe* start_vf) {
3225 ResourceMark rm;
3226 int vframe_no = 1;
3227 for (vframe* f = start_vf; f; f = f->sender()) {
3228 if (f->is_java_frame()) {
3229 javaVFrame::cast(f)->print_activation(vframe_no++);
3230 } else {
3231 f->print();
3232 }
3233 if (vframe_no > StackPrintLimit) {
3234 tty->print_cr("...<more frames>...");
3235 return;
3236 }
3237 }
3238 }
3239
3240
3241 void JavaThread::trace_stack() {
3242 if (!has_last_Java_frame()) return;
3243 ResourceMark rm;
3244 HandleMark hm;
3245 RegisterMap reg_map(this);
3246 trace_stack_from(last_java_vframe(®_map));
3247 }
3248
3249
3250 #endif // PRODUCT
3251
3252
3253 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3254 assert(reg_map != NULL, "a map must be given");
3255 frame f = last_frame();
3256 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3257 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3258 }
3259 return NULL;
3260 }
3261
3262
3263 Klass* JavaThread::security_get_caller_class(int depth) {
3264 vframeStream vfst(this);
3265 vfst.security_get_caller_frame(depth);
3266 if (!vfst.at_end()) {
3267 return vfst.method()->method_holder();
3268 }
3269 return NULL;
3270 }
3271
3272 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3273 assert(thread->is_Compiler_thread(), "must be compiler thread");
3274 CompileBroker::compiler_thread_loop();
3275 }
3276
3277 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3278 NMethodSweeper::sweeper_loop();
3279 }
3280
3281 // Create a CompilerThread
3282 CompilerThread::CompilerThread(CompileQueue* queue,
3283 CompilerCounters* counters)
3284 : JavaThread(&compiler_thread_entry) {
3285 _env = NULL;
3286 _log = NULL;
3287 _task = NULL;
3288 _queue = queue;
3289 _counters = counters;
3290 _buffer_blob = NULL;
3291 _compiler = NULL;
3292
3293 #ifndef PRODUCT
3294 _ideal_graph_printer = NULL;
3295 #endif
3296 }
3297
3298 bool CompilerThread::can_call_java() const {
3299 return _compiler != NULL && _compiler->is_jvmci();
3300 }
3301
3302 // Create sweeper thread
3303 CodeCacheSweeperThread::CodeCacheSweeperThread()
3304 : JavaThread(&sweeper_thread_entry) {
3305 _scanned_compiled_method = NULL;
3306 }
3307
3308 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3309 JavaThread::oops_do(f, cf);
3310 if (_scanned_compiled_method != NULL && cf != NULL) {
3311 // Safepoints can occur when the sweeper is scanning an nmethod so
3312 // process it here to make sure it isn't unloaded in the middle of
3313 // a scan.
3314 cf->do_code_blob(_scanned_compiled_method);
3315 }
3316 }
3317
3318 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3319 JavaThread::nmethods_do(cf);
3320 if (_scanned_compiled_method != NULL && cf != NULL) {
3321 // Safepoints can occur when the sweeper is scanning an nmethod so
3322 // process it here to make sure it isn't unloaded in the middle of
3323 // a scan.
3324 cf->do_code_blob(_scanned_compiled_method);
3325 }
3326 }
3327
3328
3329 // ======= Threads ========
3330
3331 // The Threads class links together all active threads, and provides
3332 // operations over all threads. It is protected by its own Mutex
3333 // lock, which is also used in other contexts to protect thread
3334 // operations from having the thread being operated on from exiting
3335 // and going away unexpectedly (e.g., safepoint synchronization)
3336
3337 JavaThread* Threads::_thread_list = NULL;
3338 int Threads::_number_of_threads = 0;
3339 int Threads::_number_of_non_daemon_threads = 0;
3340 int Threads::_return_code = 0;
3341 int Threads::_thread_claim_parity = 0;
3342 size_t JavaThread::_stack_size_at_create = 0;
3343 #ifdef ASSERT
3344 bool Threads::_vm_complete = false;
3345 #endif
3346
3347 // All JavaThreads
3348 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3349
3350 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3351 void Threads::threads_do(ThreadClosure* tc) {
3352 assert_locked_or_safepoint(Threads_lock);
3353 // ALL_JAVA_THREADS iterates through all JavaThreads
3354 ALL_JAVA_THREADS(p) {
3355 tc->do_thread(p);
3356 }
3357 // Someday we could have a table or list of all non-JavaThreads.
3358 // For now, just manually iterate through them.
3359 tc->do_thread(VMThread::vm_thread());
3360 Universe::heap()->gc_threads_do(tc);
3361 WatcherThread *wt = WatcherThread::watcher_thread();
3362 // Strictly speaking, the following NULL check isn't sufficient to make sure
3363 // the data for WatcherThread is still valid upon being examined. However,
3364 // considering that WatchThread terminates when the VM is on the way to
3365 // exit at safepoint, the chance of the above is extremely small. The right
3366 // way to prevent termination of WatcherThread would be to acquire
3367 // Terminator_lock, but we can't do that without violating the lock rank
3368 // checking in some cases.
3369 if (wt != NULL) {
3370 tc->do_thread(wt);
3371 }
3372
3373 // If CompilerThreads ever become non-JavaThreads, add them here
3374 }
3375
3376 // The system initialization in the library has three phases.
3377 //
3378 // Phase 1: java.lang.System class initialization
3379 // java.lang.System is a primordial class loaded and initialized
3380 // by the VM early during startup. java.lang.System.<clinit>
3381 // only does registerNatives and keeps the rest of the class
3382 // initialization work later until thread initialization completes.
3383 //
3384 // System.initPhase1 initializes the system properties, the static
3385 // fields in, out, and err. Set up java signal handlers, OS-specific
3386 // system settings, and thread group of the main thread.
3387 static void call_initPhase1(TRAPS) {
3388 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3389 instanceKlassHandle klass (THREAD, k);
3390
3391 JavaValue result(T_VOID);
3392 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3393 vmSymbols::void_method_signature(), CHECK);
3394 }
3395
3396 // Phase 2. Module system initialization
3397 // This will initialize the module system. Only java.base classes
3398 // can be loaded until phase 2 completes.
3399 //
3400 // Call System.initPhase2 after the compiler initialization and jsr292
3401 // classes get initialized because module initialization runs a lot of java
3402 // code, that for performance reasons, should be compiled. Also, this will
3403 // enable the startup code to use lambda and other language features in this
3404 // phase and onward.
3405 //
3406 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3407 static void call_initPhase2(TRAPS) {
3408 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3409 instanceKlassHandle klass (THREAD, k);
3410
3411 JavaValue result(T_VOID);
3412 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3413 vmSymbols::void_method_signature(), CHECK);
3414 universe_post_module_init();
3415 }
3416
3417 // Phase 3. final setup - set security manager, system class loader and TCCL
3418 //
3419 // This will instantiate and set the security manager, set the system class
3420 // loader as well as the thread context class loader. The security manager
3421 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3422 // other modules or the application's classpath.
3423 static void call_initPhase3(TRAPS) {
3424 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3425 instanceKlassHandle klass (THREAD, k);
3426
3427 JavaValue result(T_VOID);
3428 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3429 vmSymbols::void_method_signature(), CHECK);
3430 }
3431
3432 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3433 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3434
3435 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3436 create_vm_init_libraries();
3437 }
3438
3439 initialize_class(vmSymbols::java_lang_String(), CHECK);
3440
3441 // Inject CompactStrings value after the static initializers for String ran.
3442 java_lang_String::set_compact_strings(CompactStrings);
3443
3444 // Initialize java_lang.System (needed before creating the thread)
3445 initialize_class(vmSymbols::java_lang_System(), CHECK);
3446 // The VM creates & returns objects of this class. Make sure it's initialized.
3447 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3448 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3449 Handle thread_group = create_initial_thread_group(CHECK);
3450 Universe::set_main_thread_group(thread_group());
3451 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3452 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3453 main_thread->set_threadObj(thread_object);
3454 // Set thread status to running since main thread has
3455 // been started and running.
3456 java_lang_Thread::set_thread_status(thread_object,
3457 java_lang_Thread::RUNNABLE);
3458
3459 // The VM creates objects of this class.
3460 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3461
3462 // The VM preresolves methods to these classes. Make sure that they get initialized
3463 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3464 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3465
3466 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3467 call_initPhase1(CHECK);
3468
3469 // get the Java runtime name after java.lang.System is initialized
3470 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3471 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3472
3473 // an instance of OutOfMemory exception has been allocated earlier
3474 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3475 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3476 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3477 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3478 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3479 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3480 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3481 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3482 }
3483
3484 void Threads::initialize_jsr292_core_classes(TRAPS) {
3485 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3486
3487 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3488 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3489 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3490 }
3491
3492 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3493 extern void JDK_Version_init();
3494
3495 // Preinitialize version info.
3496 VM_Version::early_initialize();
3497
3498 // Check version
3499 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3500
3501 // Initialize library-based TLS
3502 ThreadLocalStorage::init();
3503
3504 // Initialize the output stream module
3505 ostream_init();
3506
3507 // Process java launcher properties.
3508 Arguments::process_sun_java_launcher_properties(args);
3509
3510 // Initialize the os module
3511 os::init();
3512
3513 // Record VM creation timing statistics
3514 TraceVmCreationTime create_vm_timer;
3515 create_vm_timer.start();
3516
3517 // Initialize system properties.
3518 Arguments::init_system_properties();
3519
3520 // So that JDK version can be used as a discriminator when parsing arguments
3521 JDK_Version_init();
3522
3523 // Update/Initialize System properties after JDK version number is known
3524 Arguments::init_version_specific_system_properties();
3525
3526 // Make sure to initialize log configuration *before* parsing arguments
3527 LogConfiguration::initialize(create_vm_timer.begin_time());
3528
3529 // Parse arguments
3530 jint parse_result = Arguments::parse(args);
3531 if (parse_result != JNI_OK) return parse_result;
3532
3533 os::init_before_ergo();
3534
3535 jint ergo_result = Arguments::apply_ergo();
3536 if (ergo_result != JNI_OK) return ergo_result;
3537
3538 // Final check of all ranges after ergonomics which may change values.
3539 if (!CommandLineFlagRangeList::check_ranges()) {
3540 return JNI_EINVAL;
3541 }
3542
3543 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3544 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3545 if (!constraint_result) {
3546 return JNI_EINVAL;
3547 }
3548
3549 CommandLineFlagWriteableList::mark_startup();
3550
3551 if (PauseAtStartup) {
3552 os::pause();
3553 }
3554
3555 HOTSPOT_VM_INIT_BEGIN();
3556
3557 // Timing (must come after argument parsing)
3558 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3559
3560 // Initialize the os module after parsing the args
3561 jint os_init_2_result = os::init_2();
3562 if (os_init_2_result != JNI_OK) return os_init_2_result;
3563
3564 jint adjust_after_os_result = Arguments::adjust_after_os();
3565 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3566
3567 // Initialize output stream logging
3568 ostream_init_log();
3569
3570 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3571 // Must be before create_vm_init_agents()
3572 if (Arguments::init_libraries_at_startup()) {
3573 convert_vm_init_libraries_to_agents();
3574 }
3575
3576 // Launch -agentlib/-agentpath and converted -Xrun agents
3577 if (Arguments::init_agents_at_startup()) {
3578 create_vm_init_agents();
3579 }
3580
3581 // Initialize Threads state
3582 _thread_list = NULL;
3583 _number_of_threads = 0;
3584 _number_of_non_daemon_threads = 0;
3585
3586 // Initialize global data structures and create system classes in heap
3587 vm_init_globals();
3588
3589 #if INCLUDE_JVMCI
3590 if (JVMCICounterSize > 0) {
3591 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3592 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3593 } else {
3594 JavaThread::_jvmci_old_thread_counters = NULL;
3595 }
3596 #endif // INCLUDE_JVMCI
3597
3598 // Attach the main thread to this os thread
3599 JavaThread* main_thread = new JavaThread();
3600 main_thread->set_thread_state(_thread_in_vm);
3601 main_thread->initialize_thread_current();
3602 // must do this before set_active_handles
3603 main_thread->record_stack_base_and_size();
3604 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3605
3606 if (!main_thread->set_as_starting_thread()) {
3607 vm_shutdown_during_initialization(
3608 "Failed necessary internal allocation. Out of swap space");
3609 delete main_thread;
3610 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3611 return JNI_ENOMEM;
3612 }
3613
3614 // Enable guard page *after* os::create_main_thread(), otherwise it would
3615 // crash Linux VM, see notes in os_linux.cpp.
3616 main_thread->create_stack_guard_pages();
3617
3618 // Initialize Java-Level synchronization subsystem
3619 ObjectMonitor::Initialize();
3620
3621 // Initialize global modules
3622 jint status = init_globals();
3623 if (status != JNI_OK) {
3624 delete main_thread;
3625 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3626 return status;
3627 }
3628
3629 if (TRACE_INITIALIZE() != JNI_OK) {
3630 vm_exit_during_initialization("Failed to initialize tracing backend");
3631 }
3632
3633 // Should be done after the heap is fully created
3634 main_thread->cache_global_variables();
3635
3636 HandleMark hm;
3637
3638 { MutexLocker mu(Threads_lock);
3639 Threads::add(main_thread);
3640 }
3641
3642 // Any JVMTI raw monitors entered in onload will transition into
3643 // real raw monitor. VM is setup enough here for raw monitor enter.
3644 JvmtiExport::transition_pending_onload_raw_monitors();
3645
3646 // Create the VMThread
3647 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3648
3649 VMThread::create();
3650 Thread* vmthread = VMThread::vm_thread();
3651
3652 if (!os::create_thread(vmthread, os::vm_thread)) {
3653 vm_exit_during_initialization("Cannot create VM thread. "
3654 "Out of system resources.");
3655 }
3656
3657 // Wait for the VM thread to become ready, and VMThread::run to initialize
3658 // Monitors can have spurious returns, must always check another state flag
3659 {
3660 MutexLocker ml(Notify_lock);
3661 os::start_thread(vmthread);
3662 while (vmthread->active_handles() == NULL) {
3663 Notify_lock->wait();
3664 }
3665 }
3666 }
3667
3668 assert(Universe::is_fully_initialized(), "not initialized");
3669 if (VerifyDuringStartup) {
3670 // Make sure we're starting with a clean slate.
3671 VM_Verify verify_op;
3672 VMThread::execute(&verify_op);
3673 }
3674
3675 Thread* THREAD = Thread::current();
3676
3677 // At this point, the Universe is initialized, but we have not executed
3678 // any byte code. Now is a good time (the only time) to dump out the
3679 // internal state of the JVM for sharing.
3680 if (DumpSharedSpaces) {
3681 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3682 ShouldNotReachHere();
3683 }
3684
3685 // Always call even when there are not JVMTI environments yet, since environments
3686 // may be attached late and JVMTI must track phases of VM execution
3687 JvmtiExport::enter_early_start_phase();
3688
3689 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3690 JvmtiExport::post_early_vm_start();
3691
3692 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3693
3694 // We need this for ClassDataSharing - the initial vm.info property is set
3695 // with the default value of CDS "sharing" which may be reset through
3696 // command line options.
3697 reset_vm_info_property(CHECK_JNI_ERR);
3698
3699 quicken_jni_functions();
3700
3701 // No more stub generation allowed after that point.
3702 StubCodeDesc::freeze();
3703
3704 // Set flag that basic initialization has completed. Used by exceptions and various
3705 // debug stuff, that does not work until all basic classes have been initialized.
3706 set_init_completed();
3707
3708 LogConfiguration::post_initialize();
3709 Metaspace::post_initialize();
3710
3711 HOTSPOT_VM_INIT_END();
3712
3713 // record VM initialization completion time
3714 #if INCLUDE_MANAGEMENT
3715 Management::record_vm_init_completed();
3716 #endif // INCLUDE_MANAGEMENT
3717
3718 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3719 // set_init_completed has just been called, causing exceptions not to be shortcut
3720 // anymore. We call vm_exit_during_initialization directly instead.
3721
3722 // Initialize reference pending list locker
3723 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3724 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3725
3726 // Signal Dispatcher needs to be started before VMInit event is posted
3727 os::signal_init();
3728
3729 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3730 if (!DisableAttachMechanism) {
3731 AttachListener::vm_start();
3732 if (StartAttachListener || AttachListener::init_at_startup()) {
3733 AttachListener::init();
3734 }
3735 }
3736
3737 // Launch -Xrun agents
3738 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3739 // back-end can launch with -Xdebug -Xrunjdwp.
3740 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3741 create_vm_init_libraries();
3742 }
3743
3744 if (CleanChunkPoolAsync) {
3745 Chunk::start_chunk_pool_cleaner_task();
3746 }
3747
3748 // initialize compiler(s)
3749 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3750 CompileBroker::compilation_init(CHECK_JNI_ERR);
3751 #endif
3752
3753 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3754 // It is done after compilers are initialized, because otherwise compilations of
3755 // signature polymorphic MH intrinsics can be missed
3756 // (see SystemDictionary::find_method_handle_intrinsic).
3757 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3758
3759 // This will initialize the module system. Only java.base classes can be
3760 // loaded until phase 2 completes
3761 call_initPhase2(CHECK_JNI_ERR);
3762
3763 // Always call even when there are not JVMTI environments yet, since environments
3764 // may be attached late and JVMTI must track phases of VM execution
3765 JvmtiExport::enter_start_phase();
3766
3767 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3768 JvmtiExport::post_vm_start();
3769
3770 // Final system initialization including security manager and system class loader
3771 call_initPhase3(CHECK_JNI_ERR);
3772
3773 #ifdef INCLUDE_JVMCI
3774 if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
3775 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3776 // compilations via JVMCI will not actually block until JVMCI is initialized.
3777 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3778 }
3779 #endif
3780 // cache the system class loader
3781 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3782
3783 // Always call even when there are not JVMTI environments yet, since environments
3784 // may be attached late and JVMTI must track phases of VM execution
3785 JvmtiExport::enter_live_phase();
3786
3787 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3788 JvmtiExport::post_vm_initialized();
3789
3790 if (TRACE_START() != JNI_OK) {
3791 vm_exit_during_initialization("Failed to start tracing backend.");
3792 }
3793
3794 #if INCLUDE_MANAGEMENT
3795 Management::initialize(THREAD);
3796
3797 if (HAS_PENDING_EXCEPTION) {
3798 // management agent fails to start possibly due to
3799 // configuration problem and is responsible for printing
3800 // stack trace if appropriate. Simply exit VM.
3801 vm_exit(1);
3802 }
3803 #endif // INCLUDE_MANAGEMENT
3804
3805 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3806 if (MemProfiling) MemProfiler::engage();
3807 StatSampler::engage();
3808 if (CheckJNICalls) JniPeriodicChecker::engage();
3809
3810 BiasedLocking::init();
3811
3812 #if INCLUDE_RTM_OPT
3813 RTMLockingCounters::init();
3814 #endif
3815
3816 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3817 call_postVMInitHook(THREAD);
3818 // The Java side of PostVMInitHook.run must deal with all
3819 // exceptions and provide means of diagnosis.
3820 if (HAS_PENDING_EXCEPTION) {
3821 CLEAR_PENDING_EXCEPTION;
3822 }
3823 }
3824
3825 {
3826 MutexLocker ml(PeriodicTask_lock);
3827 // Make sure the WatcherThread can be started by WatcherThread::start()
3828 // or by dynamic enrollment.
3829 WatcherThread::make_startable();
3830 // Start up the WatcherThread if there are any periodic tasks
3831 // NOTE: All PeriodicTasks should be registered by now. If they
3832 // aren't, late joiners might appear to start slowly (we might
3833 // take a while to process their first tick).
3834 if (PeriodicTask::num_tasks() > 0) {
3835 WatcherThread::start();
3836 }
3837 }
3838
3839 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3840
3841 create_vm_timer.end();
3842 #ifdef ASSERT
3843 _vm_complete = true;
3844 #endif
3845 return JNI_OK;
3846 }
3847
3848 // type for the Agent_OnLoad and JVM_OnLoad entry points
3849 extern "C" {
3850 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3851 }
3852 // Find a command line agent library and return its entry point for
3853 // -agentlib: -agentpath: -Xrun
3854 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3855 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3856 const char *on_load_symbols[],
3857 size_t num_symbol_entries) {
3858 OnLoadEntry_t on_load_entry = NULL;
3859 void *library = NULL;
3860
3861 if (!agent->valid()) {
3862 char buffer[JVM_MAXPATHLEN];
3863 char ebuf[1024] = "";
3864 const char *name = agent->name();
3865 const char *msg = "Could not find agent library ";
3866
3867 // First check to see if agent is statically linked into executable
3868 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3869 library = agent->os_lib();
3870 } else if (agent->is_absolute_path()) {
3871 library = os::dll_load(name, ebuf, sizeof ebuf);
3872 if (library == NULL) {
3873 const char *sub_msg = " in absolute path, with error: ";
3874 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3875 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3876 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3877 // If we can't find the agent, exit.
3878 vm_exit_during_initialization(buf, NULL);
3879 FREE_C_HEAP_ARRAY(char, buf);
3880 }
3881 } else {
3882 // Try to load the agent from the standard dll directory
3883 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3884 name)) {
3885 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3886 }
3887 if (library == NULL) { // Try the local directory
3888 char ns[1] = {0};
3889 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3890 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3891 }
3892 if (library == NULL) {
3893 const char *sub_msg = " on the library path, with error: ";
3894 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3895 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3896 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3897 // If we can't find the agent, exit.
3898 vm_exit_during_initialization(buf, NULL);
3899 FREE_C_HEAP_ARRAY(char, buf);
3900 }
3901 }
3902 }
3903 agent->set_os_lib(library);
3904 agent->set_valid();
3905 }
3906
3907 // Find the OnLoad function.
3908 on_load_entry =
3909 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3910 false,
3911 on_load_symbols,
3912 num_symbol_entries));
3913 return on_load_entry;
3914 }
3915
3916 // Find the JVM_OnLoad entry point
3917 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3918 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3919 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3920 }
3921
3922 // Find the Agent_OnLoad entry point
3923 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3924 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3925 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3926 }
3927
3928 // For backwards compatibility with -Xrun
3929 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3930 // treated like -agentpath:
3931 // Must be called before agent libraries are created
3932 void Threads::convert_vm_init_libraries_to_agents() {
3933 AgentLibrary* agent;
3934 AgentLibrary* next;
3935
3936 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3937 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3938 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3939
3940 // If there is an JVM_OnLoad function it will get called later,
3941 // otherwise see if there is an Agent_OnLoad
3942 if (on_load_entry == NULL) {
3943 on_load_entry = lookup_agent_on_load(agent);
3944 if (on_load_entry != NULL) {
3945 // switch it to the agent list -- so that Agent_OnLoad will be called,
3946 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3947 Arguments::convert_library_to_agent(agent);
3948 } else {
3949 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3950 }
3951 }
3952 }
3953 }
3954
3955 // Create agents for -agentlib: -agentpath: and converted -Xrun
3956 // Invokes Agent_OnLoad
3957 // Called very early -- before JavaThreads exist
3958 void Threads::create_vm_init_agents() {
3959 extern struct JavaVM_ main_vm;
3960 AgentLibrary* agent;
3961
3962 JvmtiExport::enter_onload_phase();
3963
3964 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3965 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3966
3967 if (on_load_entry != NULL) {
3968 // Invoke the Agent_OnLoad function
3969 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3970 if (err != JNI_OK) {
3971 vm_exit_during_initialization("agent library failed to init", agent->name());
3972 }
3973 } else {
3974 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3975 }
3976 }
3977 JvmtiExport::enter_primordial_phase();
3978 }
3979
3980 extern "C" {
3981 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3982 }
3983
3984 void Threads::shutdown_vm_agents() {
3985 // Send any Agent_OnUnload notifications
3986 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3987 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3988 extern struct JavaVM_ main_vm;
3989 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3990
3991 // Find the Agent_OnUnload function.
3992 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3993 os::find_agent_function(agent,
3994 false,
3995 on_unload_symbols,
3996 num_symbol_entries));
3997
3998 // Invoke the Agent_OnUnload function
3999 if (unload_entry != NULL) {
4000 JavaThread* thread = JavaThread::current();
4001 ThreadToNativeFromVM ttn(thread);
4002 HandleMark hm(thread);
4003 (*unload_entry)(&main_vm);
4004 }
4005 }
4006 }
4007
4008 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4009 // Invokes JVM_OnLoad
4010 void Threads::create_vm_init_libraries() {
4011 extern struct JavaVM_ main_vm;
4012 AgentLibrary* agent;
4013
4014 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4015 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4016
4017 if (on_load_entry != NULL) {
4018 // Invoke the JVM_OnLoad function
4019 JavaThread* thread = JavaThread::current();
4020 ThreadToNativeFromVM ttn(thread);
4021 HandleMark hm(thread);
4022 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4023 if (err != JNI_OK) {
4024 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4025 }
4026 } else {
4027 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4028 }
4029 }
4030 }
4031
4032 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4033 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4034
4035 JavaThread* java_thread = NULL;
4036 // Sequential search for now. Need to do better optimization later.
4037 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4038 oop tobj = thread->threadObj();
4039 if (!thread->is_exiting() &&
4040 tobj != NULL &&
4041 java_tid == java_lang_Thread::thread_id(tobj)) {
4042 java_thread = thread;
4043 break;
4044 }
4045 }
4046 return java_thread;
4047 }
4048
4049
4050 // Last thread running calls java.lang.Shutdown.shutdown()
4051 void JavaThread::invoke_shutdown_hooks() {
4052 HandleMark hm(this);
4053
4054 // We could get here with a pending exception, if so clear it now.
4055 if (this->has_pending_exception()) {
4056 this->clear_pending_exception();
4057 }
4058
4059 EXCEPTION_MARK;
4060 Klass* k =
4061 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4062 THREAD);
4063 if (k != NULL) {
4064 // SystemDictionary::resolve_or_null will return null if there was
4065 // an exception. If we cannot load the Shutdown class, just don't
4066 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4067 // and finalizers (if runFinalizersOnExit is set) won't be run.
4068 // Note that if a shutdown hook was registered or runFinalizersOnExit
4069 // was called, the Shutdown class would have already been loaded
4070 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4071 instanceKlassHandle shutdown_klass (THREAD, k);
4072 JavaValue result(T_VOID);
4073 JavaCalls::call_static(&result,
4074 shutdown_klass,
4075 vmSymbols::shutdown_method_name(),
4076 vmSymbols::void_method_signature(),
4077 THREAD);
4078 }
4079 CLEAR_PENDING_EXCEPTION;
4080 }
4081
4082 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4083 // the program falls off the end of main(). Another VM exit path is through
4084 // vm_exit() when the program calls System.exit() to return a value or when
4085 // there is a serious error in VM. The two shutdown paths are not exactly
4086 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4087 // and VM_Exit op at VM level.
4088 //
4089 // Shutdown sequence:
4090 // + Shutdown native memory tracking if it is on
4091 // + Wait until we are the last non-daemon thread to execute
4092 // <-- every thing is still working at this moment -->
4093 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4094 // shutdown hooks, run finalizers if finalization-on-exit
4095 // + Call before_exit(), prepare for VM exit
4096 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4097 // currently the only user of this mechanism is File.deleteOnExit())
4098 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4099 // post thread end and vm death events to JVMTI,
4100 // stop signal thread
4101 // + Call JavaThread::exit(), it will:
4102 // > release JNI handle blocks, remove stack guard pages
4103 // > remove this thread from Threads list
4104 // <-- no more Java code from this thread after this point -->
4105 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4106 // the compiler threads at safepoint
4107 // <-- do not use anything that could get blocked by Safepoint -->
4108 // + Disable tracing at JNI/JVM barriers
4109 // + Set _vm_exited flag for threads that are still running native code
4110 // + Delete this thread
4111 // + Call exit_globals()
4112 // > deletes tty
4113 // > deletes PerfMemory resources
4114 // + Return to caller
4115
4116 bool Threads::destroy_vm() {
4117 JavaThread* thread = JavaThread::current();
4118
4119 #ifdef ASSERT
4120 _vm_complete = false;
4121 #endif
4122 // Wait until we are the last non-daemon thread to execute
4123 { MutexLocker nu(Threads_lock);
4124 while (Threads::number_of_non_daemon_threads() > 1)
4125 // This wait should make safepoint checks, wait without a timeout,
4126 // and wait as a suspend-equivalent condition.
4127 //
4128 // Note: If the FlatProfiler is running and this thread is waiting
4129 // for another non-daemon thread to finish, then the FlatProfiler
4130 // is waiting for the external suspend request on this thread to
4131 // complete. wait_for_ext_suspend_completion() will eventually
4132 // timeout, but that takes time. Making this wait a suspend-
4133 // equivalent condition solves that timeout problem.
4134 //
4135 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4136 Mutex::_as_suspend_equivalent_flag);
4137 }
4138
4139 // Hang forever on exit if we are reporting an error.
4140 if (ShowMessageBoxOnError && is_error_reported()) {
4141 os::infinite_sleep();
4142 }
4143 os::wait_for_keypress_at_exit();
4144
4145 // run Java level shutdown hooks
4146 thread->invoke_shutdown_hooks();
4147
4148 before_exit(thread);
4149
4150 thread->exit(true);
4151
4152 // Stop VM thread.
4153 {
4154 // 4945125 The vm thread comes to a safepoint during exit.
4155 // GC vm_operations can get caught at the safepoint, and the
4156 // heap is unparseable if they are caught. Grab the Heap_lock
4157 // to prevent this. The GC vm_operations will not be able to
4158 // queue until after the vm thread is dead. After this point,
4159 // we'll never emerge out of the safepoint before the VM exits.
4160
4161 MutexLocker ml(Heap_lock);
4162
4163 VMThread::wait_for_vm_thread_exit();
4164 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4165 VMThread::destroy();
4166 }
4167
4168 // clean up ideal graph printers
4169 #if defined(COMPILER2) && !defined(PRODUCT)
4170 IdealGraphPrinter::clean_up();
4171 #endif
4172
4173 // Now, all Java threads are gone except daemon threads. Daemon threads
4174 // running Java code or in VM are stopped by the Safepoint. However,
4175 // daemon threads executing native code are still running. But they
4176 // will be stopped at native=>Java/VM barriers. Note that we can't
4177 // simply kill or suspend them, as it is inherently deadlock-prone.
4178
4179 VM_Exit::set_vm_exited();
4180
4181 notify_vm_shutdown();
4182
4183 delete thread;
4184
4185 #if INCLUDE_JVMCI
4186 if (JVMCICounterSize > 0) {
4187 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4188 }
4189 #endif
4190
4191 // exit_globals() will delete tty
4192 exit_globals();
4193
4194 LogConfiguration::finalize();
4195
4196 return true;
4197 }
4198
4199
4200 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4201 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4202 return is_supported_jni_version(version);
4203 }
4204
4205
4206 jboolean Threads::is_supported_jni_version(jint version) {
4207 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4208 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4209 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4210 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4211 if (version == JNI_VERSION_9) return JNI_TRUE;
4212 return JNI_FALSE;
4213 }
4214
4215
4216 void Threads::add(JavaThread* p, bool force_daemon) {
4217 // The threads lock must be owned at this point
4218 assert_locked_or_safepoint(Threads_lock);
4219
4220 // See the comment for this method in thread.hpp for its purpose and
4221 // why it is called here.
4222 p->initialize_queues();
4223 p->set_next(_thread_list);
4224 _thread_list = p;
4225 _number_of_threads++;
4226 oop threadObj = p->threadObj();
4227 bool daemon = true;
4228 // Bootstrapping problem: threadObj can be null for initial
4229 // JavaThread (or for threads attached via JNI)
4230 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4231 _number_of_non_daemon_threads++;
4232 daemon = false;
4233 }
4234
4235 ThreadService::add_thread(p, daemon);
4236
4237 // Possible GC point.
4238 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4239 }
4240
4241 void Threads::remove(JavaThread* p) {
4242 // Extra scope needed for Thread_lock, so we can check
4243 // that we do not remove thread without safepoint code notice
4244 { MutexLocker ml(Threads_lock);
4245
4246 assert(includes(p), "p must be present");
4247
4248 JavaThread* current = _thread_list;
4249 JavaThread* prev = NULL;
4250
4251 while (current != p) {
4252 prev = current;
4253 current = current->next();
4254 }
4255
4256 if (prev) {
4257 prev->set_next(current->next());
4258 } else {
4259 _thread_list = p->next();
4260 }
4261 _number_of_threads--;
4262 oop threadObj = p->threadObj();
4263 bool daemon = true;
4264 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4265 _number_of_non_daemon_threads--;
4266 daemon = false;
4267
4268 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4269 // on destroy_vm will wake up.
4270 if (number_of_non_daemon_threads() == 1) {
4271 Threads_lock->notify_all();
4272 }
4273 }
4274 ThreadService::remove_thread(p, daemon);
4275
4276 // Make sure that safepoint code disregard this thread. This is needed since
4277 // the thread might mess around with locks after this point. This can cause it
4278 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4279 // of this thread since it is removed from the queue.
4280 p->set_terminated_value();
4281 } // unlock Threads_lock
4282
4283 // Since Events::log uses a lock, we grab it outside the Threads_lock
4284 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4285 }
4286
4287 // Threads_lock must be held when this is called (or must be called during a safepoint)
4288 bool Threads::includes(JavaThread* p) {
4289 assert(Threads_lock->is_locked(), "sanity check");
4290 ALL_JAVA_THREADS(q) {
4291 if (q == p) {
4292 return true;
4293 }
4294 }
4295 return false;
4296 }
4297
4298 // Operations on the Threads list for GC. These are not explicitly locked,
4299 // but the garbage collector must provide a safe context for them to run.
4300 // In particular, these things should never be called when the Threads_lock
4301 // is held by some other thread. (Note: the Safepoint abstraction also
4302 // uses the Threads_lock to guarantee this property. It also makes sure that
4303 // all threads gets blocked when exiting or starting).
4304
4305 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4306 ALL_JAVA_THREADS(p) {
4307 p->oops_do(f, cf);
4308 }
4309 VMThread::vm_thread()->oops_do(f, cf);
4310 }
4311
4312 void Threads::change_thread_claim_parity() {
4313 // Set the new claim parity.
4314 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4315 "Not in range.");
4316 _thread_claim_parity++;
4317 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4318 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4319 "Not in range.");
4320 }
4321
4322 #ifdef ASSERT
4323 void Threads::assert_all_threads_claimed() {
4324 ALL_JAVA_THREADS(p) {
4325 const int thread_parity = p->oops_do_parity();
4326 assert((thread_parity == _thread_claim_parity),
4327 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4328 }
4329 }
4330 #endif // ASSERT
4331
4332 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4333 int cp = Threads::thread_claim_parity();
4334 ALL_JAVA_THREADS(p) {
4335 if (p->claim_oops_do(is_par, cp)) {
4336 p->oops_do(f, cf);
4337 }
4338 }
4339 VMThread* vmt = VMThread::vm_thread();
4340 if (vmt->claim_oops_do(is_par, cp)) {
4341 vmt->oops_do(f, cf);
4342 }
4343 }
4344
4345 #if INCLUDE_ALL_GCS
4346 // Used by ParallelScavenge
4347 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4348 ALL_JAVA_THREADS(p) {
4349 q->enqueue(new ThreadRootsTask(p));
4350 }
4351 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4352 }
4353
4354 // Used by Parallel Old
4355 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4356 ALL_JAVA_THREADS(p) {
4357 q->enqueue(new ThreadRootsMarkingTask(p));
4358 }
4359 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4360 }
4361 #endif // INCLUDE_ALL_GCS
4362
4363 void Threads::nmethods_do(CodeBlobClosure* cf) {
4364 ALL_JAVA_THREADS(p) {
4365 // This is used by the code cache sweeper to mark nmethods that are active
4366 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4367 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4368 if(!p->is_Code_cache_sweeper_thread()) {
4369 p->nmethods_do(cf);
4370 }
4371 }
4372 }
4373
4374 void Threads::metadata_do(void f(Metadata*)) {
4375 ALL_JAVA_THREADS(p) {
4376 p->metadata_do(f);
4377 }
4378 }
4379
4380 class ThreadHandlesClosure : public ThreadClosure {
4381 void (*_f)(Metadata*);
4382 public:
4383 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4384 virtual void do_thread(Thread* thread) {
4385 thread->metadata_handles_do(_f);
4386 }
4387 };
4388
4389 void Threads::metadata_handles_do(void f(Metadata*)) {
4390 // Only walk the Handles in Thread.
4391 ThreadHandlesClosure handles_closure(f);
4392 threads_do(&handles_closure);
4393 }
4394
4395 void Threads::deoptimized_wrt_marked_nmethods() {
4396 ALL_JAVA_THREADS(p) {
4397 p->deoptimized_wrt_marked_nmethods();
4398 }
4399 }
4400
4401
4402 // Get count Java threads that are waiting to enter the specified monitor.
4403 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4404 address monitor,
4405 bool doLock) {
4406 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4407 "must grab Threads_lock or be at safepoint");
4408 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4409
4410 int i = 0;
4411 {
4412 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4413 ALL_JAVA_THREADS(p) {
4414 if (!p->can_call_java()) continue;
4415
4416 address pending = (address)p->current_pending_monitor();
4417 if (pending == monitor) { // found a match
4418 if (i < count) result->append(p); // save the first count matches
4419 i++;
4420 }
4421 }
4422 }
4423 return result;
4424 }
4425
4426
4427 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4428 bool doLock) {
4429 assert(doLock ||
4430 Threads_lock->owned_by_self() ||
4431 SafepointSynchronize::is_at_safepoint(),
4432 "must grab Threads_lock or be at safepoint");
4433
4434 // NULL owner means not locked so we can skip the search
4435 if (owner == NULL) return NULL;
4436
4437 {
4438 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4439 ALL_JAVA_THREADS(p) {
4440 // first, see if owner is the address of a Java thread
4441 if (owner == (address)p) return p;
4442 }
4443 }
4444 // Cannot assert on lack of success here since this function may be
4445 // used by code that is trying to report useful problem information
4446 // like deadlock detection.
4447 if (UseHeavyMonitors) return NULL;
4448
4449 // If we didn't find a matching Java thread and we didn't force use of
4450 // heavyweight monitors, then the owner is the stack address of the
4451 // Lock Word in the owning Java thread's stack.
4452 //
4453 JavaThread* the_owner = NULL;
4454 {
4455 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4456 ALL_JAVA_THREADS(q) {
4457 if (q->is_lock_owned(owner)) {
4458 the_owner = q;
4459 break;
4460 }
4461 }
4462 }
4463 // cannot assert on lack of success here; see above comment
4464 return the_owner;
4465 }
4466
4467 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4468 void Threads::print_on(outputStream* st, bool print_stacks,
4469 bool internal_format, bool print_concurrent_locks) {
4470 char buf[32];
4471 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4472
4473 st->print_cr("Full thread dump %s (%s %s):",
4474 Abstract_VM_Version::vm_name(),
4475 Abstract_VM_Version::vm_release(),
4476 Abstract_VM_Version::vm_info_string());
4477 st->cr();
4478
4479 #if INCLUDE_SERVICES
4480 // Dump concurrent locks
4481 ConcurrentLocksDump concurrent_locks;
4482 if (print_concurrent_locks) {
4483 concurrent_locks.dump_at_safepoint();
4484 }
4485 #endif // INCLUDE_SERVICES
4486
4487 ALL_JAVA_THREADS(p) {
4488 ResourceMark rm;
4489 p->print_on(st);
4490 if (print_stacks) {
4491 if (internal_format) {
4492 p->trace_stack();
4493 } else {
4494 p->print_stack_on(st);
4495 }
4496 }
4497 st->cr();
4498 #if INCLUDE_SERVICES
4499 if (print_concurrent_locks) {
4500 concurrent_locks.print_locks_on(p, st);
4501 }
4502 #endif // INCLUDE_SERVICES
4503 }
4504
4505 VMThread::vm_thread()->print_on(st);
4506 st->cr();
4507 Universe::heap()->print_gc_threads_on(st);
4508 WatcherThread* wt = WatcherThread::watcher_thread();
4509 if (wt != NULL) {
4510 wt->print_on(st);
4511 st->cr();
4512 }
4513 st->flush();
4514 }
4515
4516 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4517 int buflen, bool* found_current) {
4518 if (this_thread != NULL) {
4519 bool is_current = (current == this_thread);
4520 *found_current = *found_current || is_current;
4521 st->print("%s", is_current ? "=>" : " ");
4522
4523 st->print(PTR_FORMAT, p2i(this_thread));
4524 st->print(" ");
4525 this_thread->print_on_error(st, buf, buflen);
4526 st->cr();
4527 }
4528 }
4529
4530 class PrintOnErrorClosure : public ThreadClosure {
4531 outputStream* _st;
4532 Thread* _current;
4533 char* _buf;
4534 int _buflen;
4535 bool* _found_current;
4536 public:
4537 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4538 int buflen, bool* found_current) :
4539 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4540
4541 virtual void do_thread(Thread* thread) {
4542 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4543 }
4544 };
4545
4546 // Threads::print_on_error() is called by fatal error handler. It's possible
4547 // that VM is not at safepoint and/or current thread is inside signal handler.
4548 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4549 // memory (even in resource area), it might deadlock the error handler.
4550 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4551 int buflen) {
4552 bool found_current = false;
4553 st->print_cr("Java Threads: ( => current thread )");
4554 ALL_JAVA_THREADS(thread) {
4555 print_on_error(thread, st, current, buf, buflen, &found_current);
4556 }
4557 st->cr();
4558
4559 st->print_cr("Other Threads:");
4560 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4561 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4562
4563 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4564 Universe::heap()->gc_threads_do(&print_closure);
4565
4566 if (!found_current) {
4567 st->cr();
4568 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4569 current->print_on_error(st, buf, buflen);
4570 st->cr();
4571 }
4572 st->cr();
4573 st->print_cr("Threads with active compile tasks:");
4574 print_threads_compiling(st, buf, buflen);
4575 }
4576
4577 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4578 ALL_JAVA_THREADS(thread) {
4579 if (thread->is_Compiler_thread()) {
4580 CompilerThread* ct = (CompilerThread*) thread;
4581 if (ct->task() != NULL) {
4582 thread->print_name_on_error(st, buf, buflen);
4583 ct->task()->print(st, NULL, true, true);
4584 }
4585 }
4586 }
4587 }
4588
4589
4590 // Internal SpinLock and Mutex
4591 // Based on ParkEvent
4592
4593 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4594 //
4595 // We employ SpinLocks _only for low-contention, fixed-length
4596 // short-duration critical sections where we're concerned
4597 // about native mutex_t or HotSpot Mutex:: latency.
4598 // The mux construct provides a spin-then-block mutual exclusion
4599 // mechanism.
4600 //
4601 // Testing has shown that contention on the ListLock guarding gFreeList
4602 // is common. If we implement ListLock as a simple SpinLock it's common
4603 // for the JVM to devolve to yielding with little progress. This is true
4604 // despite the fact that the critical sections protected by ListLock are
4605 // extremely short.
4606 //
4607 // TODO-FIXME: ListLock should be of type SpinLock.
4608 // We should make this a 1st-class type, integrated into the lock
4609 // hierarchy as leaf-locks. Critically, the SpinLock structure
4610 // should have sufficient padding to avoid false-sharing and excessive
4611 // cache-coherency traffic.
4612
4613
4614 typedef volatile int SpinLockT;
4615
4616 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4617 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4618 return; // normal fast-path return
4619 }
4620
4621 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4622 TEVENT(SpinAcquire - ctx);
4623 int ctr = 0;
4624 int Yields = 0;
4625 for (;;) {
4626 while (*adr != 0) {
4627 ++ctr;
4628 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4629 if (Yields > 5) {
4630 os::naked_short_sleep(1);
4631 } else {
4632 os::naked_yield();
4633 ++Yields;
4634 }
4635 } else {
4636 SpinPause();
4637 }
4638 }
4639 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4640 }
4641 }
4642
4643 void Thread::SpinRelease(volatile int * adr) {
4644 assert(*adr != 0, "invariant");
4645 OrderAccess::fence(); // guarantee at least release consistency.
4646 // Roach-motel semantics.
4647 // It's safe if subsequent LDs and STs float "up" into the critical section,
4648 // but prior LDs and STs within the critical section can't be allowed
4649 // to reorder or float past the ST that releases the lock.
4650 // Loads and stores in the critical section - which appear in program
4651 // order before the store that releases the lock - must also appear
4652 // before the store that releases the lock in memory visibility order.
4653 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4654 // the ST of 0 into the lock-word which releases the lock, so fence
4655 // more than covers this on all platforms.
4656 *adr = 0;
4657 }
4658
4659 // muxAcquire and muxRelease:
4660 //
4661 // * muxAcquire and muxRelease support a single-word lock-word construct.
4662 // The LSB of the word is set IFF the lock is held.
4663 // The remainder of the word points to the head of a singly-linked list
4664 // of threads blocked on the lock.
4665 //
4666 // * The current implementation of muxAcquire-muxRelease uses its own
4667 // dedicated Thread._MuxEvent instance. If we're interested in
4668 // minimizing the peak number of extant ParkEvent instances then
4669 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4670 // as certain invariants were satisfied. Specifically, care would need
4671 // to be taken with regards to consuming unpark() "permits".
4672 // A safe rule of thumb is that a thread would never call muxAcquire()
4673 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4674 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4675 // consume an unpark() permit intended for monitorenter, for instance.
4676 // One way around this would be to widen the restricted-range semaphore
4677 // implemented in park(). Another alternative would be to provide
4678 // multiple instances of the PlatformEvent() for each thread. One
4679 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4680 //
4681 // * Usage:
4682 // -- Only as leaf locks
4683 // -- for short-term locking only as muxAcquire does not perform
4684 // thread state transitions.
4685 //
4686 // Alternatives:
4687 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4688 // but with parking or spin-then-park instead of pure spinning.
4689 // * Use Taura-Oyama-Yonenzawa locks.
4690 // * It's possible to construct a 1-0 lock if we encode the lockword as
4691 // (List,LockByte). Acquire will CAS the full lockword while Release
4692 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4693 // acquiring threads use timers (ParkTimed) to detect and recover from
4694 // the stranding window. Thread/Node structures must be aligned on 256-byte
4695 // boundaries by using placement-new.
4696 // * Augment MCS with advisory back-link fields maintained with CAS().
4697 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4698 // The validity of the backlinks must be ratified before we trust the value.
4699 // If the backlinks are invalid the exiting thread must back-track through the
4700 // the forward links, which are always trustworthy.
4701 // * Add a successor indication. The LockWord is currently encoded as
4702 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4703 // to provide the usual futile-wakeup optimization.
4704 // See RTStt for details.
4705 // * Consider schedctl.sc_nopreempt to cover the critical section.
4706 //
4707
4708
4709 typedef volatile intptr_t MutexT; // Mux Lock-word
4710 enum MuxBits { LOCKBIT = 1 };
4711
4712 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4713 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4714 if (w == 0) return;
4715 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4716 return;
4717 }
4718
4719 TEVENT(muxAcquire - Contention);
4720 ParkEvent * const Self = Thread::current()->_MuxEvent;
4721 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4722 for (;;) {
4723 int its = (os::is_MP() ? 100 : 0) + 1;
4724
4725 // Optional spin phase: spin-then-park strategy
4726 while (--its >= 0) {
4727 w = *Lock;
4728 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4729 return;
4730 }
4731 }
4732
4733 Self->reset();
4734 Self->OnList = intptr_t(Lock);
4735 // The following fence() isn't _strictly necessary as the subsequent
4736 // CAS() both serializes execution and ratifies the fetched *Lock value.
4737 OrderAccess::fence();
4738 for (;;) {
4739 w = *Lock;
4740 if ((w & LOCKBIT) == 0) {
4741 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4742 Self->OnList = 0; // hygiene - allows stronger asserts
4743 return;
4744 }
4745 continue; // Interference -- *Lock changed -- Just retry
4746 }
4747 assert(w & LOCKBIT, "invariant");
4748 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4749 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4750 }
4751
4752 while (Self->OnList != 0) {
4753 Self->park();
4754 }
4755 }
4756 }
4757
4758 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4759 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4760 if (w == 0) return;
4761 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4762 return;
4763 }
4764
4765 TEVENT(muxAcquire - Contention);
4766 ParkEvent * ReleaseAfter = NULL;
4767 if (ev == NULL) {
4768 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4769 }
4770 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4771 for (;;) {
4772 guarantee(ev->OnList == 0, "invariant");
4773 int its = (os::is_MP() ? 100 : 0) + 1;
4774
4775 // Optional spin phase: spin-then-park strategy
4776 while (--its >= 0) {
4777 w = *Lock;
4778 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4779 if (ReleaseAfter != NULL) {
4780 ParkEvent::Release(ReleaseAfter);
4781 }
4782 return;
4783 }
4784 }
4785
4786 ev->reset();
4787 ev->OnList = intptr_t(Lock);
4788 // The following fence() isn't _strictly necessary as the subsequent
4789 // CAS() both serializes execution and ratifies the fetched *Lock value.
4790 OrderAccess::fence();
4791 for (;;) {
4792 w = *Lock;
4793 if ((w & LOCKBIT) == 0) {
4794 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4795 ev->OnList = 0;
4796 // We call ::Release while holding the outer lock, thus
4797 // artificially lengthening the critical section.
4798 // Consider deferring the ::Release() until the subsequent unlock(),
4799 // after we've dropped the outer lock.
4800 if (ReleaseAfter != NULL) {
4801 ParkEvent::Release(ReleaseAfter);
4802 }
4803 return;
4804 }
4805 continue; // Interference -- *Lock changed -- Just retry
4806 }
4807 assert(w & LOCKBIT, "invariant");
4808 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4809 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4810 }
4811
4812 while (ev->OnList != 0) {
4813 ev->park();
4814 }
4815 }
4816 }
4817
4818 // Release() must extract a successor from the list and then wake that thread.
4819 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4820 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4821 // Release() would :
4822 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4823 // (B) Extract a successor from the private list "in-hand"
4824 // (C) attempt to CAS() the residual back into *Lock over null.
4825 // If there were any newly arrived threads and the CAS() would fail.
4826 // In that case Release() would detach the RATs, re-merge the list in-hand
4827 // with the RATs and repeat as needed. Alternately, Release() might
4828 // detach and extract a successor, but then pass the residual list to the wakee.
4829 // The wakee would be responsible for reattaching and remerging before it
4830 // competed for the lock.
4831 //
4832 // Both "pop" and DMR are immune from ABA corruption -- there can be
4833 // multiple concurrent pushers, but only one popper or detacher.
4834 // This implementation pops from the head of the list. This is unfair,
4835 // but tends to provide excellent throughput as hot threads remain hot.
4836 // (We wake recently run threads first).
4837 //
4838 // All paths through muxRelease() will execute a CAS.
4839 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4840 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4841 // executed within the critical section are complete and globally visible before the
4842 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4843 void Thread::muxRelease(volatile intptr_t * Lock) {
4844 for (;;) {
4845 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4846 assert(w & LOCKBIT, "invariant");
4847 if (w == LOCKBIT) return;
4848 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4849 assert(List != NULL, "invariant");
4850 assert(List->OnList == intptr_t(Lock), "invariant");
4851 ParkEvent * const nxt = List->ListNext;
4852 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4853
4854 // The following CAS() releases the lock and pops the head element.
4855 // The CAS() also ratifies the previously fetched lock-word value.
4856 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4857 continue;
4858 }
4859 List->OnList = 0;
4860 OrderAccess::fence();
4861 List->unpark();
4862 return;
4863 }
4864 }
4865
4866
4867 void Threads::verify() {
4868 ALL_JAVA_THREADS(p) {
4869 p->verify();
4870 }
4871 VMThread* thread = VMThread::vm_thread();
4872 if (thread != NULL) thread->verify();
4873 }