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/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "memory/metaspaceShared.hpp"
45 #include "memory/oopFactory.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/symbol.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "prims/jvm_misc.hpp"
54 #include "prims/jvmtiExport.hpp"
55 #include "prims/jvmtiThreadState.hpp"
56 #include "prims/privilegedStack.hpp"
57 #include "runtime/arguments.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/commandLineFlagConstraintList.hpp"
61 #include "runtime/commandLineFlagWriteableList.hpp"
62 #include "runtime/commandLineFlagRangeList.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/fprofiler.hpp"
65 #include "runtime/frame.inline.hpp"
66 #include "runtime/globals.hpp"
67 #include "runtime/init.hpp"
68 #include "runtime/interfaceSupport.hpp"
69 #include "runtime/java.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniPeriodicChecker.hpp"
72 #include "runtime/timerTrace.hpp"
73 #include "runtime/memprofiler.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/objectMonitor.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/osThread.hpp"
78 #include "runtime/safepoint.hpp"
79 #include "runtime/sharedRuntime.hpp"
80 #include "runtime/statSampler.hpp"
81 #include "runtime/stubRoutines.hpp"
82 #include "runtime/sweeper.hpp"
83 #include "runtime/task.hpp"
84 #include "runtime/thread.inline.hpp"
85 #include "runtime/threadCritical.hpp"
86 #include "runtime/vframe.hpp"
87 #include "runtime/vframeArray.hpp"
88 #include "runtime/vframe_hp.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "runtime/vm_operations.hpp"
91 #include "runtime/vm_version.hpp"
92 #include "services/attachListener.hpp"
93 #include "services/management.hpp"
94 #include "services/memTracker.hpp"
95 #include "services/threadService.hpp"
96 #include "trace/traceMacros.hpp"
97 #include "trace/tracing.hpp"
98 #include "utilities/defaultStream.hpp"
99 #include "utilities/dtrace.hpp"
100 #include "utilities/events.hpp"
101 #include "utilities/macros.hpp"
102 #include "utilities/preserveException.hpp"
103 #if INCLUDE_ALL_GCS
104 #include "gc/cms/concurrentMarkSweepThread.hpp"
105 #include "gc/g1/concurrentMarkThread.inline.hpp"
106 #include "gc/parallel/pcTasks.hpp"
107 #endif // INCLUDE_ALL_GCS
108 #if INCLUDE_JVMCI
109 #include "jvmci/jvmciCompiler.hpp"
110 #include "jvmci/jvmciRuntime.hpp"
111 #endif
112 #ifdef COMPILER1
113 #include "c1/c1_Compiler.hpp"
114 #endif
115 #ifdef COMPILER2
116 #include "opto/c2compiler.hpp"
117 #include "opto/idealGraphPrinter.hpp"
118 #endif
119 #if INCLUDE_RTM_OPT
120 #include "runtime/rtmLocking.hpp"
121 #endif
122
123 // Initialization after module runtime initialization
124 void universe_post_module_init(); // must happen after call_initPhase2
125
126 #ifdef DTRACE_ENABLED
127
128 // Only bother with this argument setup if dtrace is available
129
130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
132
133 #define DTRACE_THREAD_PROBE(probe, javathread) \
134 { \
135 ResourceMark rm(this); \
136 int len = 0; \
137 const char* name = (javathread)->get_thread_name(); \
138 len = strlen(name); \
139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
140 (char *) name, len, \
141 java_lang_Thread::thread_id((javathread)->threadObj()), \
142 (uintptr_t) (javathread)->osthread()->thread_id(), \
143 java_lang_Thread::is_daemon((javathread)->threadObj())); \
144 }
145
146 #else // ndef DTRACE_ENABLED
147
148 #define DTRACE_THREAD_PROBE(probe, javathread)
149
150 #endif // ndef DTRACE_ENABLED
151
152 #ifndef USE_LIBRARY_BASED_TLS_ONLY
153 // Current thread is maintained as a thread-local variable
154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
155 #endif
156 // Class hierarchy
157 // - Thread
158 // - VMThread
159 // - WatcherThread
160 // - ConcurrentMarkSweepThread
161 // - JavaThread
162 // - CompilerThread
163
164 // ======= Thread ========
165 // Support for forcing alignment of thread objects for biased locking
166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
167 if (UseBiasedLocking) {
168 const int alignment = markOopDesc::biased_lock_alignment;
169 size_t aligned_size = size + (alignment - sizeof(intptr_t));
170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
171 : AllocateHeap(aligned_size, flags, CURRENT_PC,
172 AllocFailStrategy::RETURN_NULL);
173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
176 "JavaThread alignment code overflowed allocated storage");
177 if (aligned_addr != real_malloc_addr) {
178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
179 p2i(real_malloc_addr),
180 p2i(aligned_addr));
181 }
182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
183 return aligned_addr;
184 } else {
185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
187 }
188 }
189
190 void Thread::operator delete(void* p) {
191 if (UseBiasedLocking) {
192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
193 FreeHeap(real_malloc_addr);
194 } else {
195 FreeHeap(p);
196 }
197 }
198
199
200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
201 // JavaThread
202
203
204 Thread::Thread() {
205 // stack and get_thread
206 set_stack_base(NULL);
207 set_stack_size(0);
208 set_self_raw_id(0);
209 set_lgrp_id(-1);
210 DEBUG_ONLY(clear_suspendible_thread();)
211
212 // allocated data structures
213 set_osthread(NULL);
214 set_resource_area(new (mtThread)ResourceArea());
215 DEBUG_ONLY(_current_resource_mark = NULL;)
216 set_handle_area(new (mtThread) HandleArea(NULL));
217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
218 set_active_handles(NULL);
219 set_free_handle_block(NULL);
220 set_last_handle_mark(NULL);
221
222 // This initial value ==> never claimed.
223 _oops_do_parity = 0;
224
225 // the handle mark links itself to last_handle_mark
226 new HandleMark(this);
227
228 // plain initialization
229 debug_only(_owned_locks = NULL;)
230 debug_only(_allow_allocation_count = 0;)
231 NOT_PRODUCT(_allow_safepoint_count = 0;)
232 NOT_PRODUCT(_skip_gcalot = false;)
233 _jvmti_env_iteration_count = 0;
234 set_allocated_bytes(0);
235 _vm_operation_started_count = 0;
236 _vm_operation_completed_count = 0;
237 _current_pending_monitor = NULL;
238 _current_pending_monitor_is_from_java = true;
239 _current_waiting_monitor = NULL;
240 _num_nested_signal = 0;
241 omFreeList = NULL;
242 omFreeCount = 0;
243 omFreeProvision = 32;
244 omInUseList = NULL;
245 omInUseCount = 0;
246
247 #ifdef ASSERT
248 _visited_for_critical_count = false;
249 #endif
250
251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
252 Monitor::_safepoint_check_sometimes);
253 _suspend_flags = 0;
254
255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
256 _hashStateX = os::random();
257 _hashStateY = 842502087;
258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
259 _hashStateW = 273326509;
260
261 _OnTrap = 0;
262 _schedctl = NULL;
263 _Stalled = 0;
264 _TypeTag = 0x2BAD;
265
266 // Many of the following fields are effectively final - immutable
267 // Note that nascent threads can't use the Native Monitor-Mutex
268 // construct until the _MutexEvent is initialized ...
269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
270 // we might instead use a stack of ParkEvents that we could provision on-demand.
271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
272 // and ::Release()
273 _ParkEvent = ParkEvent::Allocate(this);
274 _SleepEvent = ParkEvent::Allocate(this);
275 _MutexEvent = ParkEvent::Allocate(this);
276 _MuxEvent = ParkEvent::Allocate(this);
277
278 #ifdef CHECK_UNHANDLED_OOPS
279 if (CheckUnhandledOops) {
280 _unhandled_oops = new UnhandledOops(this);
281 }
282 #endif // CHECK_UNHANDLED_OOPS
283 #ifdef ASSERT
284 if (UseBiasedLocking) {
285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
286 assert(this == _real_malloc_address ||
287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
288 "bug in forced alignment of thread objects");
289 }
290 #endif // ASSERT
291 }
292
293 void Thread::initialize_thread_current() {
294 #ifndef USE_LIBRARY_BASED_TLS_ONLY
295 assert(_thr_current == NULL, "Thread::current already initialized");
296 _thr_current = this;
297 #endif
298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
299 ThreadLocalStorage::set_thread(this);
300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
301 }
302
303 void Thread::clear_thread_current() {
304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
305 #ifndef USE_LIBRARY_BASED_TLS_ONLY
306 _thr_current = NULL;
307 #endif
308 ThreadLocalStorage::set_thread(NULL);
309 }
310
311 void Thread::record_stack_base_and_size() {
312 set_stack_base(os::current_stack_base());
313 set_stack_size(os::current_stack_size());
314 // CR 7190089: on Solaris, primordial thread's stack is adjusted
315 // in initialize_thread(). Without the adjustment, stack size is
316 // incorrect if stack is set to unlimited (ulimit -s unlimited).
317 // So far, only Solaris has real implementation of initialize_thread().
318 //
319 // set up any platform-specific state.
320 os::initialize_thread(this);
321
322 // Set stack limits after thread is initialized.
323 if (is_Java_thread()) {
324 ((JavaThread*) this)->set_stack_overflow_limit();
325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
326 }
327 #if INCLUDE_NMT
328 // record thread's native stack, stack grows downward
329 MemTracker::record_thread_stack(stack_end(), stack_size());
330 #endif // INCLUDE_NMT
331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
333 os::current_thread_id(), p2i(stack_base() - stack_size()),
334 p2i(stack_base()), stack_size()/1024);
335 }
336
337
338 Thread::~Thread() {
339 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
340 ObjectSynchronizer::omFlush(this);
341
342 EVENT_THREAD_DESTRUCT(this);
343
344 // stack_base can be NULL if the thread is never started or exited before
345 // record_stack_base_and_size called. Although, we would like to ensure
346 // that all started threads do call record_stack_base_and_size(), there is
347 // not proper way to enforce that.
348 #if INCLUDE_NMT
349 if (_stack_base != NULL) {
350 MemTracker::release_thread_stack(stack_end(), stack_size());
351 #ifdef ASSERT
352 set_stack_base(NULL);
353 #endif
354 }
355 #endif // INCLUDE_NMT
356
357 // deallocate data structures
358 delete resource_area();
359 // since the handle marks are using the handle area, we have to deallocated the root
360 // handle mark before deallocating the thread's handle area,
361 assert(last_handle_mark() != NULL, "check we have an element");
362 delete last_handle_mark();
363 assert(last_handle_mark() == NULL, "check we have reached the end");
364
365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
366 // We NULL out the fields for good hygiene.
367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
371
372 delete handle_area();
373 delete metadata_handles();
374
375 // SR_handler uses this as a termination indicator -
376 // needs to happen before os::free_thread()
377 delete _SR_lock;
378 _SR_lock = NULL;
379
380 // osthread() can be NULL, if creation of thread failed.
381 if (osthread() != NULL) os::free_thread(osthread());
382
383 // clear Thread::current if thread is deleting itself.
384 // Needed to ensure JNI correctly detects non-attached threads.
385 if (this == Thread::current()) {
386 clear_thread_current();
387 }
388
389 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
390 }
391
392 // NOTE: dummy function for assertion purpose.
393 void Thread::run() {
394 ShouldNotReachHere();
395 }
396
397 #ifdef ASSERT
398 // Private method to check for dangling thread pointer
399 void check_for_dangling_thread_pointer(Thread *thread) {
400 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
401 "possibility of dangling Thread pointer");
402 }
403 #endif
404
405 ThreadPriority Thread::get_priority(const Thread* const thread) {
406 ThreadPriority priority;
407 // Can return an error!
408 (void)os::get_priority(thread, priority);
409 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
410 return priority;
411 }
412
413 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
414 debug_only(check_for_dangling_thread_pointer(thread);)
415 // Can return an error!
416 (void)os::set_priority(thread, priority);
417 }
418
419
420 void Thread::start(Thread* thread) {
421 // Start is different from resume in that its safety is guaranteed by context or
422 // being called from a Java method synchronized on the Thread object.
423 if (!DisableStartThread) {
424 if (thread->is_Java_thread()) {
425 // Initialize the thread state to RUNNABLE before starting this thread.
426 // Can not set it after the thread started because we do not know the
427 // exact thread state at that time. It could be in MONITOR_WAIT or
428 // in SLEEPING or some other state.
429 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
430 java_lang_Thread::RUNNABLE);
431 }
432 os::start_thread(thread);
433 }
434 }
435
436 // Enqueue a VM_Operation to do the job for us - sometime later
437 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
438 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
439 VMThread::execute(vm_stop);
440 }
441
442
443 // Check if an external suspend request has completed (or has been
444 // cancelled). Returns true if the thread is externally suspended and
445 // false otherwise.
446 //
447 // The bits parameter returns information about the code path through
448 // the routine. Useful for debugging:
449 //
450 // set in is_ext_suspend_completed():
451 // 0x00000001 - routine was entered
452 // 0x00000010 - routine return false at end
453 // 0x00000100 - thread exited (return false)
454 // 0x00000200 - suspend request cancelled (return false)
455 // 0x00000400 - thread suspended (return true)
456 // 0x00001000 - thread is in a suspend equivalent state (return true)
457 // 0x00002000 - thread is native and walkable (return true)
458 // 0x00004000 - thread is native_trans and walkable (needed retry)
459 //
460 // set in wait_for_ext_suspend_completion():
461 // 0x00010000 - routine was entered
462 // 0x00020000 - suspend request cancelled before loop (return false)
463 // 0x00040000 - thread suspended before loop (return true)
464 // 0x00080000 - suspend request cancelled in loop (return false)
465 // 0x00100000 - thread suspended in loop (return true)
466 // 0x00200000 - suspend not completed during retry loop (return false)
467
468 // Helper class for tracing suspend wait debug bits.
469 //
470 // 0x00000100 indicates that the target thread exited before it could
471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
472 // 0x00080000 each indicate a cancelled suspend request so they don't
473 // count as wait failures either.
474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
475
476 class TraceSuspendDebugBits : public StackObj {
477 private:
478 JavaThread * jt;
479 bool is_wait;
480 bool called_by_wait; // meaningful when !is_wait
481 uint32_t * bits;
482
483 public:
484 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
485 uint32_t *_bits) {
486 jt = _jt;
487 is_wait = _is_wait;
488 called_by_wait = _called_by_wait;
489 bits = _bits;
490 }
491
492 ~TraceSuspendDebugBits() {
493 if (!is_wait) {
494 #if 1
495 // By default, don't trace bits for is_ext_suspend_completed() calls.
496 // That trace is very chatty.
497 return;
498 #else
499 if (!called_by_wait) {
500 // If tracing for is_ext_suspend_completed() is enabled, then only
501 // trace calls to it from wait_for_ext_suspend_completion()
502 return;
503 }
504 #endif
505 }
506
507 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
508 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
509 MutexLocker ml(Threads_lock); // needed for get_thread_name()
510 ResourceMark rm;
511
512 tty->print_cr(
513 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
514 jt->get_thread_name(), *bits);
515
516 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
517 }
518 }
519 }
520 };
521 #undef DEBUG_FALSE_BITS
522
523
524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
525 uint32_t *bits) {
526 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
527
528 bool did_trans_retry = false; // only do thread_in_native_trans retry once
529 bool do_trans_retry; // flag to force the retry
530
531 *bits |= 0x00000001;
532
533 do {
534 do_trans_retry = false;
535
536 if (is_exiting()) {
537 // Thread is in the process of exiting. This is always checked
538 // first to reduce the risk of dereferencing a freed JavaThread.
539 *bits |= 0x00000100;
540 return false;
541 }
542
543 if (!is_external_suspend()) {
544 // Suspend request is cancelled. This is always checked before
545 // is_ext_suspended() to reduce the risk of a rogue resume
546 // confusing the thread that made the suspend request.
547 *bits |= 0x00000200;
548 return false;
549 }
550
551 if (is_ext_suspended()) {
552 // thread is suspended
553 *bits |= 0x00000400;
554 return true;
555 }
556
557 // Now that we no longer do hard suspends of threads running
558 // native code, the target thread can be changing thread state
559 // while we are in this routine:
560 //
561 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
562 //
563 // We save a copy of the thread state as observed at this moment
564 // and make our decision about suspend completeness based on the
565 // copy. This closes the race where the thread state is seen as
566 // _thread_in_native_trans in the if-thread_blocked check, but is
567 // seen as _thread_blocked in if-thread_in_native_trans check.
568 JavaThreadState save_state = thread_state();
569
570 if (save_state == _thread_blocked && is_suspend_equivalent()) {
571 // If the thread's state is _thread_blocked and this blocking
572 // condition is known to be equivalent to a suspend, then we can
573 // consider the thread to be externally suspended. This means that
574 // the code that sets _thread_blocked has been modified to do
575 // self-suspension if the blocking condition releases. We also
576 // used to check for CONDVAR_WAIT here, but that is now covered by
577 // the _thread_blocked with self-suspension check.
578 //
579 // Return true since we wouldn't be here unless there was still an
580 // external suspend request.
581 *bits |= 0x00001000;
582 return true;
583 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
584 // Threads running native code will self-suspend on native==>VM/Java
585 // transitions. If its stack is walkable (should always be the case
586 // unless this function is called before the actual java_suspend()
587 // call), then the wait is done.
588 *bits |= 0x00002000;
589 return true;
590 } else if (!called_by_wait && !did_trans_retry &&
591 save_state == _thread_in_native_trans &&
592 frame_anchor()->walkable()) {
593 // The thread is transitioning from thread_in_native to another
594 // thread state. check_safepoint_and_suspend_for_native_trans()
595 // will force the thread to self-suspend. If it hasn't gotten
596 // there yet we may have caught the thread in-between the native
597 // code check above and the self-suspend. Lucky us. If we were
598 // called by wait_for_ext_suspend_completion(), then it
599 // will be doing the retries so we don't have to.
600 //
601 // Since we use the saved thread state in the if-statement above,
602 // there is a chance that the thread has already transitioned to
603 // _thread_blocked by the time we get here. In that case, we will
604 // make a single unnecessary pass through the logic below. This
605 // doesn't hurt anything since we still do the trans retry.
606
607 *bits |= 0x00004000;
608
609 // Once the thread leaves thread_in_native_trans for another
610 // thread state, we break out of this retry loop. We shouldn't
611 // need this flag to prevent us from getting back here, but
612 // sometimes paranoia is good.
613 did_trans_retry = true;
614
615 // We wait for the thread to transition to a more usable state.
616 for (int i = 1; i <= SuspendRetryCount; i++) {
617 // We used to do an "os::yield_all(i)" call here with the intention
618 // that yielding would increase on each retry. However, the parameter
619 // is ignored on Linux which means the yield didn't scale up. Waiting
620 // on the SR_lock below provides a much more predictable scale up for
621 // the delay. It also provides a simple/direct point to check for any
622 // safepoint requests from the VMThread
623
624 // temporarily drops SR_lock while doing wait with safepoint check
625 // (if we're a JavaThread - the WatcherThread can also call this)
626 // and increase delay with each retry
627 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
628
629 // check the actual thread state instead of what we saved above
630 if (thread_state() != _thread_in_native_trans) {
631 // the thread has transitioned to another thread state so
632 // try all the checks (except this one) one more time.
633 do_trans_retry = true;
634 break;
635 }
636 } // end retry loop
637
638
639 }
640 } while (do_trans_retry);
641
642 *bits |= 0x00000010;
643 return false;
644 }
645
646 // Wait for an external suspend request to complete (or be cancelled).
647 // Returns true if the thread is externally suspended and false otherwise.
648 //
649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
650 uint32_t *bits) {
651 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
652 false /* !called_by_wait */, bits);
653
654 // local flag copies to minimize SR_lock hold time
655 bool is_suspended;
656 bool pending;
657 uint32_t reset_bits;
658
659 // set a marker so is_ext_suspend_completed() knows we are the caller
660 *bits |= 0x00010000;
661
662 // We use reset_bits to reinitialize the bits value at the top of
663 // each retry loop. This allows the caller to make use of any
664 // unused bits for their own marking purposes.
665 reset_bits = *bits;
666
667 {
668 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
669 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
670 delay, bits);
671 pending = is_external_suspend();
672 }
673 // must release SR_lock to allow suspension to complete
674
675 if (!pending) {
676 // A cancelled suspend request is the only false return from
677 // is_ext_suspend_completed() that keeps us from entering the
678 // retry loop.
679 *bits |= 0x00020000;
680 return false;
681 }
682
683 if (is_suspended) {
684 *bits |= 0x00040000;
685 return true;
686 }
687
688 for (int i = 1; i <= retries; i++) {
689 *bits = reset_bits; // reinit to only track last retry
690
691 // We used to do an "os::yield_all(i)" call here with the intention
692 // that yielding would increase on each retry. However, the parameter
693 // is ignored on Linux which means the yield didn't scale up. Waiting
694 // on the SR_lock below provides a much more predictable scale up for
695 // the delay. It also provides a simple/direct point to check for any
696 // safepoint requests from the VMThread
697
698 {
699 MutexLocker ml(SR_lock());
700 // wait with safepoint check (if we're a JavaThread - the WatcherThread
701 // can also call this) and increase delay with each retry
702 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
703
704 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
705 delay, bits);
706
707 // It is possible for the external suspend request to be cancelled
708 // (by a resume) before the actual suspend operation is completed.
709 // Refresh our local copy to see if we still need to wait.
710 pending = is_external_suspend();
711 }
712
713 if (!pending) {
714 // A cancelled suspend request is the only false return from
715 // is_ext_suspend_completed() that keeps us from staying in the
716 // retry loop.
717 *bits |= 0x00080000;
718 return false;
719 }
720
721 if (is_suspended) {
722 *bits |= 0x00100000;
723 return true;
724 }
725 } // end retry loop
726
727 // thread did not suspend after all our retries
728 *bits |= 0x00200000;
729 return false;
730 }
731
732 #ifndef PRODUCT
733 void JavaThread::record_jump(address target, address instr, const char* file,
734 int line) {
735
736 // This should not need to be atomic as the only way for simultaneous
737 // updates is via interrupts. Even then this should be rare or non-existent
738 // and we don't care that much anyway.
739
740 int index = _jmp_ring_index;
741 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
742 _jmp_ring[index]._target = (intptr_t) target;
743 _jmp_ring[index]._instruction = (intptr_t) instr;
744 _jmp_ring[index]._file = file;
745 _jmp_ring[index]._line = line;
746 }
747 #endif // PRODUCT
748
749 // Called by flat profiler
750 // Callers have already called wait_for_ext_suspend_completion
751 // The assertion for that is currently too complex to put here:
752 bool JavaThread::profile_last_Java_frame(frame* _fr) {
753 bool gotframe = false;
754 // self suspension saves needed state.
755 if (has_last_Java_frame() && _anchor.walkable()) {
756 *_fr = pd_last_frame();
757 gotframe = true;
758 }
759 return gotframe;
760 }
761
762 void Thread::interrupt(Thread* thread) {
763 debug_only(check_for_dangling_thread_pointer(thread);)
764 os::interrupt(thread);
765 }
766
767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
768 debug_only(check_for_dangling_thread_pointer(thread);)
769 // Note: If clear_interrupted==false, this simply fetches and
770 // returns the value of the field osthread()->interrupted().
771 return os::is_interrupted(thread, clear_interrupted);
772 }
773
774
775 // GC Support
776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
777 jint thread_parity = _oops_do_parity;
778 if (thread_parity != strong_roots_parity) {
779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
780 if (res == thread_parity) {
781 return true;
782 } else {
783 guarantee(res == strong_roots_parity, "Or else what?");
784 return false;
785 }
786 }
787 return false;
788 }
789
790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
791 active_handles()->oops_do(f);
792 // Do oop for ThreadShadow
793 f->do_oop((oop*)&_pending_exception);
794 handle_area()->oops_do(f);
795 }
796
797 void Thread::metadata_handles_do(void f(Metadata*)) {
798 // Only walk the Handles in Thread.
799 if (metadata_handles() != NULL) {
800 for (int i = 0; i< metadata_handles()->length(); i++) {
801 f(metadata_handles()->at(i));
802 }
803 }
804 }
805
806 void Thread::print_on(outputStream* st) const {
807 // get_priority assumes osthread initialized
808 if (osthread() != NULL) {
809 int os_prio;
810 if (os::get_native_priority(this, &os_prio) == OS_OK) {
811 st->print("os_prio=%d ", os_prio);
812 }
813 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
814 ext().print_on(st);
815 osthread()->print_on(st);
816 }
817 debug_only(if (WizardMode) print_owned_locks_on(st);)
818 }
819
820 // Thread::print_on_error() is called by fatal error handler. Don't use
821 // any lock or allocate memory.
822 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
823 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
824
825 if (is_VM_thread()) { st->print("VMThread"); }
826 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
827 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
828 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
829 else { st->print("Thread"); }
830
831 if (is_Named_thread()) {
832 st->print(" \"%s\"", name());
833 }
834
835 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
836 p2i(stack_end()), p2i(stack_base()));
837
838 if (osthread()) {
839 st->print(" [id=%d]", osthread()->thread_id());
840 }
841 }
842
843 #ifdef ASSERT
844 void Thread::print_owned_locks_on(outputStream* st) const {
845 Monitor *cur = _owned_locks;
846 if (cur == NULL) {
847 st->print(" (no locks) ");
848 } else {
849 st->print_cr(" Locks owned:");
850 while (cur) {
851 cur->print_on(st);
852 cur = cur->next();
853 }
854 }
855 }
856
857 static int ref_use_count = 0;
858
859 bool Thread::owns_locks_but_compiled_lock() const {
860 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
861 if (cur != Compile_lock) return true;
862 }
863 return false;
864 }
865
866
867 #endif
868
869 #ifndef PRODUCT
870
871 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
872 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
873 // no threads which allow_vm_block's are held
874 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
875 // Check if current thread is allowed to block at a safepoint
876 if (!(_allow_safepoint_count == 0)) {
877 fatal("Possible safepoint reached by thread that does not allow it");
878 }
879 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
880 fatal("LEAF method calling lock?");
881 }
882
883 #ifdef ASSERT
884 if (potential_vm_operation && is_Java_thread()
885 && !Universe::is_bootstrapping()) {
886 // Make sure we do not hold any locks that the VM thread also uses.
887 // This could potentially lead to deadlocks
888 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
889 // Threads_lock is special, since the safepoint synchronization will not start before this is
890 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
891 // since it is used to transfer control between JavaThreads and the VMThread
892 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
893 if ((cur->allow_vm_block() &&
894 cur != Threads_lock &&
895 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
896 cur != VMOperationRequest_lock &&
897 cur != VMOperationQueue_lock) ||
898 cur->rank() == Mutex::special) {
899 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
900 }
901 }
902 }
903
904 if (GCALotAtAllSafepoints) {
905 // We could enter a safepoint here and thus have a gc
906 InterfaceSupport::check_gc_alot();
907 }
908 #endif
909 }
910 #endif
911
912 bool Thread::is_in_stack(address adr) const {
913 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
914 address end = os::current_stack_pointer();
915 // Allow non Java threads to call this without stack_base
916 if (_stack_base == NULL) return true;
917 if (stack_base() >= adr && adr >= end) return true;
918
919 return false;
920 }
921
922 bool Thread::is_in_usable_stack(address adr) const {
923 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
924 size_t usable_stack_size = _stack_size - stack_guard_size;
925
926 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
927 }
928
929
930 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
931 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
932 // used for compilation in the future. If that change is made, the need for these methods
933 // should be revisited, and they should be removed if possible.
934
935 bool Thread::is_lock_owned(address adr) const {
936 return on_local_stack(adr);
937 }
938
939 bool Thread::set_as_starting_thread() {
940 // NOTE: this must be called inside the main thread.
941 return os::create_main_thread((JavaThread*)this);
942 }
943
944 static void initialize_class(Symbol* class_name, TRAPS) {
945 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
946 InstanceKlass::cast(klass)->initialize(CHECK);
947 }
948
949
950 // Creates the initial ThreadGroup
951 static Handle create_initial_thread_group(TRAPS) {
952 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
953 instanceKlassHandle klass (THREAD, k);
954
955 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
956 {
957 JavaValue result(T_VOID);
958 JavaCalls::call_special(&result,
959 system_instance,
960 klass,
961 vmSymbols::object_initializer_name(),
962 vmSymbols::void_method_signature(),
963 CHECK_NH);
964 }
965 Universe::set_system_thread_group(system_instance());
966
967 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
968 {
969 JavaValue result(T_VOID);
970 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
971 JavaCalls::call_special(&result,
972 main_instance,
973 klass,
974 vmSymbols::object_initializer_name(),
975 vmSymbols::threadgroup_string_void_signature(),
976 system_instance,
977 string,
978 CHECK_NH);
979 }
980 return main_instance;
981 }
982
983 // Creates the initial Thread
984 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
985 TRAPS) {
986 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
987 instanceKlassHandle klass (THREAD, k);
988 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
989
990 java_lang_Thread::set_thread(thread_oop(), thread);
991 java_lang_Thread::set_priority(thread_oop(), NormPriority);
992 thread->set_threadObj(thread_oop());
993
994 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
995
996 JavaValue result(T_VOID);
997 JavaCalls::call_special(&result, thread_oop,
998 klass,
999 vmSymbols::object_initializer_name(),
1000 vmSymbols::threadgroup_string_void_signature(),
1001 thread_group,
1002 string,
1003 CHECK_NULL);
1004 return thread_oop();
1005 }
1006
1007 char java_runtime_name[128] = "";
1008 char java_runtime_version[128] = "";
1009
1010 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1011 static const char* get_java_runtime_name(TRAPS) {
1012 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1013 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1014 fieldDescriptor fd;
1015 bool found = k != NULL &&
1016 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1017 vmSymbols::string_signature(), &fd);
1018 if (found) {
1019 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1020 if (name_oop == NULL) {
1021 return NULL;
1022 }
1023 const char* name = java_lang_String::as_utf8_string(name_oop,
1024 java_runtime_name,
1025 sizeof(java_runtime_name));
1026 return name;
1027 } else {
1028 return NULL;
1029 }
1030 }
1031
1032 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1033 static const char* get_java_runtime_version(TRAPS) {
1034 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1035 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1036 fieldDescriptor fd;
1037 bool found = k != NULL &&
1038 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1039 vmSymbols::string_signature(), &fd);
1040 if (found) {
1041 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1042 if (name_oop == NULL) {
1043 return NULL;
1044 }
1045 const char* name = java_lang_String::as_utf8_string(name_oop,
1046 java_runtime_version,
1047 sizeof(java_runtime_version));
1048 return name;
1049 } else {
1050 return NULL;
1051 }
1052 }
1053
1054 // General purpose hook into Java code, run once when the VM is initialized.
1055 // The Java library method itself may be changed independently from the VM.
1056 static void call_postVMInitHook(TRAPS) {
1057 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1058 instanceKlassHandle klass (THREAD, k);
1059 if (klass.not_null()) {
1060 JavaValue result(T_VOID);
1061 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1062 vmSymbols::void_method_signature(),
1063 CHECK);
1064 }
1065 }
1066
1067 static void reset_vm_info_property(TRAPS) {
1068 // the vm info string
1069 ResourceMark rm(THREAD);
1070 const char *vm_info = VM_Version::vm_info_string();
1071
1072 // java.lang.System class
1073 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1074 instanceKlassHandle klass (THREAD, k);
1075
1076 // setProperty arguments
1077 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1078 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1079
1080 // return value
1081 JavaValue r(T_OBJECT);
1082
1083 // public static String setProperty(String key, String value);
1084 JavaCalls::call_static(&r,
1085 klass,
1086 vmSymbols::setProperty_name(),
1087 vmSymbols::string_string_string_signature(),
1088 key_str,
1089 value_str,
1090 CHECK);
1091 }
1092
1093
1094 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1095 bool daemon, TRAPS) {
1096 assert(thread_group.not_null(), "thread group should be specified");
1097 assert(threadObj() == NULL, "should only create Java thread object once");
1098
1099 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1100 instanceKlassHandle klass (THREAD, k);
1101 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1102
1103 java_lang_Thread::set_thread(thread_oop(), this);
1104 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1105 set_threadObj(thread_oop());
1106
1107 JavaValue result(T_VOID);
1108 if (thread_name != NULL) {
1109 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1110 // Thread gets assigned specified name and null target
1111 JavaCalls::call_special(&result,
1112 thread_oop,
1113 klass,
1114 vmSymbols::object_initializer_name(),
1115 vmSymbols::threadgroup_string_void_signature(),
1116 thread_group, // Argument 1
1117 name, // Argument 2
1118 THREAD);
1119 } else {
1120 // Thread gets assigned name "Thread-nnn" and null target
1121 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1122 JavaCalls::call_special(&result,
1123 thread_oop,
1124 klass,
1125 vmSymbols::object_initializer_name(),
1126 vmSymbols::threadgroup_runnable_void_signature(),
1127 thread_group, // Argument 1
1128 Handle(), // Argument 2
1129 THREAD);
1130 }
1131
1132
1133 if (daemon) {
1134 java_lang_Thread::set_daemon(thread_oop());
1135 }
1136
1137 if (HAS_PENDING_EXCEPTION) {
1138 return;
1139 }
1140
1141 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1142 Handle threadObj(THREAD, this->threadObj());
1143
1144 JavaCalls::call_special(&result,
1145 thread_group,
1146 group,
1147 vmSymbols::add_method_name(),
1148 vmSymbols::thread_void_signature(),
1149 threadObj, // Arg 1
1150 THREAD);
1151 }
1152
1153 // NamedThread -- non-JavaThread subclasses with multiple
1154 // uniquely named instances should derive from this.
1155 NamedThread::NamedThread() : Thread() {
1156 _name = NULL;
1157 _processed_thread = NULL;
1158 _gc_id = GCId::undefined();
1159 }
1160
1161 NamedThread::~NamedThread() {
1162 if (_name != NULL) {
1163 FREE_C_HEAP_ARRAY(char, _name);
1164 _name = NULL;
1165 }
1166 }
1167
1168 void NamedThread::set_name(const char* format, ...) {
1169 guarantee(_name == NULL, "Only get to set name once.");
1170 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1171 guarantee(_name != NULL, "alloc failure");
1172 va_list ap;
1173 va_start(ap, format);
1174 jio_vsnprintf(_name, max_name_len, format, ap);
1175 va_end(ap);
1176 }
1177
1178 void NamedThread::initialize_named_thread() {
1179 set_native_thread_name(name());
1180 }
1181
1182 void NamedThread::print_on(outputStream* st) const {
1183 st->print("\"%s\" ", name());
1184 Thread::print_on(st);
1185 st->cr();
1186 }
1187
1188
1189 // ======= WatcherThread ========
1190
1191 // The watcher thread exists to simulate timer interrupts. It should
1192 // be replaced by an abstraction over whatever native support for
1193 // timer interrupts exists on the platform.
1194
1195 WatcherThread* WatcherThread::_watcher_thread = NULL;
1196 bool WatcherThread::_startable = false;
1197 volatile bool WatcherThread::_should_terminate = false;
1198
1199 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1200 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1201 if (os::create_thread(this, os::watcher_thread)) {
1202 _watcher_thread = this;
1203
1204 // Set the watcher thread to the highest OS priority which should not be
1205 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1206 // is created. The only normal thread using this priority is the reference
1207 // handler thread, which runs for very short intervals only.
1208 // If the VMThread's priority is not lower than the WatcherThread profiling
1209 // will be inaccurate.
1210 os::set_priority(this, MaxPriority);
1211 if (!DisableStartThread) {
1212 os::start_thread(this);
1213 }
1214 }
1215 }
1216
1217 int WatcherThread::sleep() const {
1218 // The WatcherThread does not participate in the safepoint protocol
1219 // for the PeriodicTask_lock because it is not a JavaThread.
1220 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1221
1222 if (_should_terminate) {
1223 // check for termination before we do any housekeeping or wait
1224 return 0; // we did not sleep.
1225 }
1226
1227 // remaining will be zero if there are no tasks,
1228 // causing the WatcherThread to sleep until a task is
1229 // enrolled
1230 int remaining = PeriodicTask::time_to_wait();
1231 int time_slept = 0;
1232
1233 // we expect this to timeout - we only ever get unparked when
1234 // we should terminate or when a new task has been enrolled
1235 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1236
1237 jlong time_before_loop = os::javaTimeNanos();
1238
1239 while (true) {
1240 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1241 remaining);
1242 jlong now = os::javaTimeNanos();
1243
1244 if (remaining == 0) {
1245 // if we didn't have any tasks we could have waited for a long time
1246 // consider the time_slept zero and reset time_before_loop
1247 time_slept = 0;
1248 time_before_loop = now;
1249 } else {
1250 // need to recalculate since we might have new tasks in _tasks
1251 time_slept = (int) ((now - time_before_loop) / 1000000);
1252 }
1253
1254 // Change to task list or spurious wakeup of some kind
1255 if (timedout || _should_terminate) {
1256 break;
1257 }
1258
1259 remaining = PeriodicTask::time_to_wait();
1260 if (remaining == 0) {
1261 // Last task was just disenrolled so loop around and wait until
1262 // another task gets enrolled
1263 continue;
1264 }
1265
1266 remaining -= time_slept;
1267 if (remaining <= 0) {
1268 break;
1269 }
1270 }
1271
1272 return time_slept;
1273 }
1274
1275 void WatcherThread::run() {
1276 assert(this == watcher_thread(), "just checking");
1277
1278 this->record_stack_base_and_size();
1279 this->set_native_thread_name(this->name());
1280 this->set_active_handles(JNIHandleBlock::allocate_block());
1281 while (true) {
1282 assert(watcher_thread() == Thread::current(), "thread consistency check");
1283 assert(watcher_thread() == this, "thread consistency check");
1284
1285 // Calculate how long it'll be until the next PeriodicTask work
1286 // should be done, and sleep that amount of time.
1287 int time_waited = sleep();
1288
1289 if (is_error_reported()) {
1290 // A fatal error has happened, the error handler(VMError::report_and_die)
1291 // should abort JVM after creating an error log file. However in some
1292 // rare cases, the error handler itself might deadlock. Here periodically
1293 // check for error reporting timeouts, and if it happens, just proceed to
1294 // abort the VM.
1295
1296 // This code is in WatcherThread because WatcherThread wakes up
1297 // periodically so the fatal error handler doesn't need to do anything;
1298 // also because the WatcherThread is less likely to crash than other
1299 // threads.
1300
1301 for (;;) {
1302 // Note: we use naked sleep in this loop because we want to avoid using
1303 // any kind of VM infrastructure which may be broken at this point.
1304 if (VMError::check_timeout()) {
1305 // We hit error reporting timeout. Error reporting was interrupted and
1306 // will be wrapping things up now (closing files etc). Give it some more
1307 // time, then quit the VM.
1308 os::naked_short_sleep(200);
1309 // Print a message to stderr.
1310 fdStream err(defaultStream::output_fd());
1311 err.print_raw_cr("# [ timer expired, abort... ]");
1312 // skip atexit/vm_exit/vm_abort hooks
1313 os::die();
1314 }
1315
1316 // Wait a second, then recheck for timeout.
1317 os::naked_short_sleep(999);
1318 }
1319 }
1320
1321 if (_should_terminate) {
1322 // check for termination before posting the next tick
1323 break;
1324 }
1325
1326 PeriodicTask::real_time_tick(time_waited);
1327 }
1328
1329 // Signal that it is terminated
1330 {
1331 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1332 _watcher_thread = NULL;
1333 Terminator_lock->notify();
1334 }
1335 }
1336
1337 void WatcherThread::start() {
1338 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1339
1340 if (watcher_thread() == NULL && _startable) {
1341 _should_terminate = false;
1342 // Create the single instance of WatcherThread
1343 new WatcherThread();
1344 }
1345 }
1346
1347 void WatcherThread::make_startable() {
1348 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1349 _startable = true;
1350 }
1351
1352 void WatcherThread::stop() {
1353 {
1354 // Follow normal safepoint aware lock enter protocol since the
1355 // WatcherThread is stopped by another JavaThread.
1356 MutexLocker ml(PeriodicTask_lock);
1357 _should_terminate = true;
1358
1359 WatcherThread* watcher = watcher_thread();
1360 if (watcher != NULL) {
1361 // unpark the WatcherThread so it can see that it should terminate
1362 watcher->unpark();
1363 }
1364 }
1365
1366 MutexLocker mu(Terminator_lock);
1367
1368 while (watcher_thread() != NULL) {
1369 // This wait should make safepoint checks, wait without a timeout,
1370 // and wait as a suspend-equivalent condition.
1371 //
1372 // Note: If the FlatProfiler is running, then this thread is waiting
1373 // for the WatcherThread to terminate and the WatcherThread, via the
1374 // FlatProfiler task, is waiting for the external suspend request on
1375 // this thread to complete. wait_for_ext_suspend_completion() will
1376 // eventually timeout, but that takes time. Making this wait a
1377 // suspend-equivalent condition solves that timeout problem.
1378 //
1379 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1380 Mutex::_as_suspend_equivalent_flag);
1381 }
1382 }
1383
1384 void WatcherThread::unpark() {
1385 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1386 PeriodicTask_lock->notify();
1387 }
1388
1389 void WatcherThread::print_on(outputStream* st) const {
1390 st->print("\"%s\" ", name());
1391 Thread::print_on(st);
1392 st->cr();
1393 }
1394
1395 // ======= JavaThread ========
1396
1397 #if INCLUDE_JVMCI
1398
1399 jlong* JavaThread::_jvmci_old_thread_counters;
1400
1401 bool jvmci_counters_include(JavaThread* thread) {
1402 oop threadObj = thread->threadObj();
1403 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1404 }
1405
1406 void JavaThread::collect_counters(typeArrayOop array) {
1407 if (JVMCICounterSize > 0) {
1408 MutexLocker tl(Threads_lock);
1409 for (int i = 0; i < array->length(); i++) {
1410 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1411 }
1412 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1413 if (jvmci_counters_include(tp)) {
1414 for (int i = 0; i < array->length(); i++) {
1415 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1416 }
1417 }
1418 }
1419 }
1420 }
1421
1422 #endif // INCLUDE_JVMCI
1423
1424 // A JavaThread is a normal Java thread
1425
1426 void JavaThread::initialize() {
1427 // Initialize fields
1428
1429 set_saved_exception_pc(NULL);
1430 set_threadObj(NULL);
1431 _anchor.clear();
1432 set_entry_point(NULL);
1433 set_jni_functions(jni_functions());
1434 set_callee_target(NULL);
1435 set_vm_result(NULL);
1436 set_vm_result_2(NULL);
1437 set_vframe_array_head(NULL);
1438 set_vframe_array_last(NULL);
1439 set_deferred_locals(NULL);
1440 set_deopt_mark(NULL);
1441 set_deopt_compiled_method(NULL);
1442 clear_must_deopt_id();
1443 set_monitor_chunks(NULL);
1444 set_next(NULL);
1445 set_thread_state(_thread_new);
1446 _terminated = _not_terminated;
1447 _privileged_stack_top = NULL;
1448 _array_for_gc = NULL;
1449 _suspend_equivalent = false;
1450 _in_deopt_handler = 0;
1451 _doing_unsafe_access = false;
1452 _stack_guard_state = stack_guard_unused;
1453 #if INCLUDE_JVMCI
1454 _pending_monitorenter = false;
1455 _pending_deoptimization = -1;
1456 _pending_failed_speculation = NULL;
1457 _pending_transfer_to_interpreter = false;
1458 _adjusting_comp_level = false;
1459 _jvmci._alternate_call_target = NULL;
1460 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1461 if (JVMCICounterSize > 0) {
1462 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1463 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1464 } else {
1465 _jvmci_counters = NULL;
1466 }
1467 #endif // INCLUDE_JVMCI
1468 _reserved_stack_activation = NULL; // stack base not known yet
1469 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1470 _exception_pc = 0;
1471 _exception_handler_pc = 0;
1472 _is_method_handle_return = 0;
1473 _jvmti_thread_state= NULL;
1474 _should_post_on_exceptions_flag = JNI_FALSE;
1475 _jvmti_get_loaded_classes_closure = NULL;
1476 _interp_only_mode = 0;
1477 _special_runtime_exit_condition = _no_async_condition;
1478 _pending_async_exception = NULL;
1479 _thread_stat = NULL;
1480 _thread_stat = new ThreadStatistics();
1481 _blocked_on_compilation = false;
1482 _jni_active_critical = 0;
1483 _pending_jni_exception_check_fn = NULL;
1484 _do_not_unlock_if_synchronized = false;
1485 _cached_monitor_info = NULL;
1486 _parker = Parker::Allocate(this);
1487
1488 #ifndef PRODUCT
1489 _jmp_ring_index = 0;
1490 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1491 record_jump(NULL, NULL, NULL, 0);
1492 }
1493 #endif // PRODUCT
1494
1495 set_thread_profiler(NULL);
1496 if (FlatProfiler::is_active()) {
1497 // This is where we would decide to either give each thread it's own profiler
1498 // or use one global one from FlatProfiler,
1499 // or up to some count of the number of profiled threads, etc.
1500 ThreadProfiler* pp = new ThreadProfiler();
1501 pp->engage();
1502 set_thread_profiler(pp);
1503 }
1504
1505 // Setup safepoint state info for this thread
1506 ThreadSafepointState::create(this);
1507
1508 debug_only(_java_call_counter = 0);
1509
1510 // JVMTI PopFrame support
1511 _popframe_condition = popframe_inactive;
1512 _popframe_preserved_args = NULL;
1513 _popframe_preserved_args_size = 0;
1514 _frames_to_pop_failed_realloc = 0;
1515
1516 pd_initialize();
1517 }
1518
1519 #if INCLUDE_ALL_GCS
1520 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1521 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1522 #endif // INCLUDE_ALL_GCS
1523
1524 JavaThread::JavaThread(bool is_attaching_via_jni) :
1525 Thread()
1526 #if INCLUDE_ALL_GCS
1527 , _satb_mark_queue(&_satb_mark_queue_set),
1528 _dirty_card_queue(&_dirty_card_queue_set)
1529 #endif // INCLUDE_ALL_GCS
1530 {
1531 initialize();
1532 if (is_attaching_via_jni) {
1533 _jni_attach_state = _attaching_via_jni;
1534 } else {
1535 _jni_attach_state = _not_attaching_via_jni;
1536 }
1537 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1538 }
1539
1540 bool JavaThread::reguard_stack(address cur_sp) {
1541 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1542 && _stack_guard_state != stack_guard_reserved_disabled) {
1543 return true; // Stack already guarded or guard pages not needed.
1544 }
1545
1546 if (register_stack_overflow()) {
1547 // For those architectures which have separate register and
1548 // memory stacks, we must check the register stack to see if
1549 // it has overflowed.
1550 return false;
1551 }
1552
1553 // Java code never executes within the yellow zone: the latter is only
1554 // there to provoke an exception during stack banging. If java code
1555 // is executing there, either StackShadowPages should be larger, or
1556 // some exception code in c1, c2 or the interpreter isn't unwinding
1557 // when it should.
1558 guarantee(cur_sp > stack_reserved_zone_base(),
1559 "not enough space to reguard - increase StackShadowPages");
1560 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1561 enable_stack_yellow_reserved_zone();
1562 if (reserved_stack_activation() != stack_base()) {
1563 set_reserved_stack_activation(stack_base());
1564 }
1565 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1566 set_reserved_stack_activation(stack_base());
1567 enable_stack_reserved_zone();
1568 }
1569 return true;
1570 }
1571
1572 bool JavaThread::reguard_stack(void) {
1573 return reguard_stack(os::current_stack_pointer());
1574 }
1575
1576
1577 void JavaThread::block_if_vm_exited() {
1578 if (_terminated == _vm_exited) {
1579 // _vm_exited is set at safepoint, and Threads_lock is never released
1580 // we will block here forever
1581 Threads_lock->lock_without_safepoint_check();
1582 ShouldNotReachHere();
1583 }
1584 }
1585
1586
1587 // Remove this ifdef when C1 is ported to the compiler interface.
1588 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1589 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1590
1591 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1592 Thread()
1593 #if INCLUDE_ALL_GCS
1594 , _satb_mark_queue(&_satb_mark_queue_set),
1595 _dirty_card_queue(&_dirty_card_queue_set)
1596 #endif // INCLUDE_ALL_GCS
1597 {
1598 initialize();
1599 _jni_attach_state = _not_attaching_via_jni;
1600 set_entry_point(entry_point);
1601 // Create the native thread itself.
1602 // %note runtime_23
1603 os::ThreadType thr_type = os::java_thread;
1604 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1605 os::java_thread;
1606 os::create_thread(this, thr_type, stack_sz);
1607 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1608 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1609 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1610 // the exception consists of creating the exception object & initializing it, initialization
1611 // will leave the VM via a JavaCall and then all locks must be unlocked).
1612 //
1613 // The thread is still suspended when we reach here. Thread must be explicit started
1614 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1615 // by calling Threads:add. The reason why this is not done here, is because the thread
1616 // object must be fully initialized (take a look at JVM_Start)
1617 }
1618
1619 JavaThread::~JavaThread() {
1620
1621 // JSR166 -- return the parker to the free list
1622 Parker::Release(_parker);
1623 _parker = NULL;
1624
1625 // Free any remaining previous UnrollBlock
1626 vframeArray* old_array = vframe_array_last();
1627
1628 if (old_array != NULL) {
1629 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1630 old_array->set_unroll_block(NULL);
1631 delete old_info;
1632 delete old_array;
1633 }
1634
1635 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1636 if (deferred != NULL) {
1637 // This can only happen if thread is destroyed before deoptimization occurs.
1638 assert(deferred->length() != 0, "empty array!");
1639 do {
1640 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1641 deferred->remove_at(0);
1642 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1643 delete dlv;
1644 } while (deferred->length() != 0);
1645 delete deferred;
1646 }
1647
1648 // All Java related clean up happens in exit
1649 ThreadSafepointState::destroy(this);
1650 if (_thread_profiler != NULL) delete _thread_profiler;
1651 if (_thread_stat != NULL) delete _thread_stat;
1652
1653 #if INCLUDE_JVMCI
1654 if (JVMCICounterSize > 0) {
1655 if (jvmci_counters_include(this)) {
1656 for (int i = 0; i < JVMCICounterSize; i++) {
1657 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1658 }
1659 }
1660 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1661 }
1662 #endif // INCLUDE_JVMCI
1663 }
1664
1665
1666 // The first routine called by a new Java thread
1667 void JavaThread::run() {
1668 // initialize thread-local alloc buffer related fields
1669 this->initialize_tlab();
1670
1671 // used to test validity of stack trace backs
1672 this->record_base_of_stack_pointer();
1673
1674 // Record real stack base and size.
1675 this->record_stack_base_and_size();
1676
1677 this->create_stack_guard_pages();
1678
1679 this->cache_global_variables();
1680
1681 // Thread is now sufficient initialized to be handled by the safepoint code as being
1682 // in the VM. Change thread state from _thread_new to _thread_in_vm
1683 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1684
1685 assert(JavaThread::current() == this, "sanity check");
1686 assert(!Thread::current()->owns_locks(), "sanity check");
1687
1688 DTRACE_THREAD_PROBE(start, this);
1689
1690 // This operation might block. We call that after all safepoint checks for a new thread has
1691 // been completed.
1692 this->set_active_handles(JNIHandleBlock::allocate_block());
1693
1694 if (JvmtiExport::should_post_thread_life()) {
1695 JvmtiExport::post_thread_start(this);
1696 }
1697
1698 EventThreadStart event;
1699 if (event.should_commit()) {
1700 event.set_thread(THREAD_TRACE_ID(this));
1701 event.commit();
1702 }
1703
1704 // We call another function to do the rest so we are sure that the stack addresses used
1705 // from there will be lower than the stack base just computed
1706 thread_main_inner();
1707
1708 // Note, thread is no longer valid at this point!
1709 }
1710
1711
1712 void JavaThread::thread_main_inner() {
1713 assert(JavaThread::current() == this, "sanity check");
1714 assert(this->threadObj() != NULL, "just checking");
1715
1716 // Execute thread entry point unless this thread has a pending exception
1717 // or has been stopped before starting.
1718 // Note: Due to JVM_StopThread we can have pending exceptions already!
1719 if (!this->has_pending_exception() &&
1720 !java_lang_Thread::is_stillborn(this->threadObj())) {
1721 {
1722 ResourceMark rm(this);
1723 this->set_native_thread_name(this->get_thread_name());
1724 }
1725 HandleMark hm(this);
1726 this->entry_point()(this, this);
1727 }
1728
1729 DTRACE_THREAD_PROBE(stop, this);
1730
1731 this->exit(false);
1732 delete this;
1733 }
1734
1735
1736 static void ensure_join(JavaThread* thread) {
1737 // We do not need to grap the Threads_lock, since we are operating on ourself.
1738 Handle threadObj(thread, thread->threadObj());
1739 assert(threadObj.not_null(), "java thread object must exist");
1740 ObjectLocker lock(threadObj, thread);
1741 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1742 thread->clear_pending_exception();
1743 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1744 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1745 // Clear the native thread instance - this makes isAlive return false and allows the join()
1746 // to complete once we've done the notify_all below
1747 java_lang_Thread::set_thread(threadObj(), NULL);
1748 lock.notify_all(thread);
1749 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1750 thread->clear_pending_exception();
1751 }
1752
1753
1754 // For any new cleanup additions, please check to see if they need to be applied to
1755 // cleanup_failed_attach_current_thread as well.
1756 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1757 assert(this == JavaThread::current(), "thread consistency check");
1758
1759 HandleMark hm(this);
1760 Handle uncaught_exception(this, this->pending_exception());
1761 this->clear_pending_exception();
1762 Handle threadObj(this, this->threadObj());
1763 assert(threadObj.not_null(), "Java thread object should be created");
1764
1765 if (get_thread_profiler() != NULL) {
1766 get_thread_profiler()->disengage();
1767 ResourceMark rm;
1768 get_thread_profiler()->print(get_thread_name());
1769 }
1770
1771
1772 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1773 {
1774 EXCEPTION_MARK;
1775
1776 CLEAR_PENDING_EXCEPTION;
1777 }
1778 if (!destroy_vm) {
1779 if (uncaught_exception.not_null()) {
1780 EXCEPTION_MARK;
1781 // Call method Thread.dispatchUncaughtException().
1782 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1783 JavaValue result(T_VOID);
1784 JavaCalls::call_virtual(&result,
1785 threadObj, thread_klass,
1786 vmSymbols::dispatchUncaughtException_name(),
1787 vmSymbols::throwable_void_signature(),
1788 uncaught_exception,
1789 THREAD);
1790 if (HAS_PENDING_EXCEPTION) {
1791 ResourceMark rm(this);
1792 jio_fprintf(defaultStream::error_stream(),
1793 "\nException: %s thrown from the UncaughtExceptionHandler"
1794 " in thread \"%s\"\n",
1795 pending_exception()->klass()->external_name(),
1796 get_thread_name());
1797 CLEAR_PENDING_EXCEPTION;
1798 }
1799 }
1800
1801 // Called before the java thread exit since we want to read info
1802 // from java_lang_Thread object
1803 EventThreadEnd event;
1804 if (event.should_commit()) {
1805 event.set_thread(THREAD_TRACE_ID(this));
1806 event.commit();
1807 }
1808
1809 // Call after last event on thread
1810 EVENT_THREAD_EXIT(this);
1811
1812 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1813 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1814 // is deprecated anyhow.
1815 if (!is_Compiler_thread()) {
1816 int count = 3;
1817 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1818 EXCEPTION_MARK;
1819 JavaValue result(T_VOID);
1820 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1821 JavaCalls::call_virtual(&result,
1822 threadObj, thread_klass,
1823 vmSymbols::exit_method_name(),
1824 vmSymbols::void_method_signature(),
1825 THREAD);
1826 CLEAR_PENDING_EXCEPTION;
1827 }
1828 }
1829 // notify JVMTI
1830 if (JvmtiExport::should_post_thread_life()) {
1831 JvmtiExport::post_thread_end(this);
1832 }
1833
1834 // We have notified the agents that we are exiting, before we go on,
1835 // we must check for a pending external suspend request and honor it
1836 // in order to not surprise the thread that made the suspend request.
1837 while (true) {
1838 {
1839 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1840 if (!is_external_suspend()) {
1841 set_terminated(_thread_exiting);
1842 ThreadService::current_thread_exiting(this);
1843 break;
1844 }
1845 // Implied else:
1846 // Things get a little tricky here. We have a pending external
1847 // suspend request, but we are holding the SR_lock so we
1848 // can't just self-suspend. So we temporarily drop the lock
1849 // and then self-suspend.
1850 }
1851
1852 ThreadBlockInVM tbivm(this);
1853 java_suspend_self();
1854
1855 // We're done with this suspend request, but we have to loop around
1856 // and check again. Eventually we will get SR_lock without a pending
1857 // external suspend request and will be able to mark ourselves as
1858 // exiting.
1859 }
1860 // no more external suspends are allowed at this point
1861 } else {
1862 // before_exit() has already posted JVMTI THREAD_END events
1863 }
1864
1865 // Notify waiters on thread object. This has to be done after exit() is called
1866 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1867 // group should have the destroyed bit set before waiters are notified).
1868 ensure_join(this);
1869 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1870
1871 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1872 // held by this thread must be released. The spec does not distinguish
1873 // between JNI-acquired and regular Java monitors. We can only see
1874 // regular Java monitors here if monitor enter-exit matching is broken.
1875 //
1876 // Optionally release any monitors for regular JavaThread exits. This
1877 // is provided as a work around for any bugs in monitor enter-exit
1878 // matching. This can be expensive so it is not enabled by default.
1879 //
1880 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1881 // ObjectSynchronizer::release_monitors_owned_by_thread().
1882 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1883 // Sanity check even though JNI DetachCurrentThread() would have
1884 // returned JNI_ERR if there was a Java frame. JavaThread exit
1885 // should be done executing Java code by the time we get here.
1886 assert(!this->has_last_Java_frame(),
1887 "should not have a Java frame when detaching or exiting");
1888 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1889 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1890 }
1891
1892 // These things needs to be done while we are still a Java Thread. Make sure that thread
1893 // is in a consistent state, in case GC happens
1894 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1895
1896 if (active_handles() != NULL) {
1897 JNIHandleBlock* block = active_handles();
1898 set_active_handles(NULL);
1899 JNIHandleBlock::release_block(block);
1900 }
1901
1902 if (free_handle_block() != NULL) {
1903 JNIHandleBlock* block = free_handle_block();
1904 set_free_handle_block(NULL);
1905 JNIHandleBlock::release_block(block);
1906 }
1907
1908 // These have to be removed while this is still a valid thread.
1909 remove_stack_guard_pages();
1910
1911 if (UseTLAB) {
1912 tlab().make_parsable(true); // retire TLAB
1913 }
1914
1915 if (JvmtiEnv::environments_might_exist()) {
1916 JvmtiExport::cleanup_thread(this);
1917 }
1918
1919 // We must flush any deferred card marks before removing a thread from
1920 // the list of active threads.
1921 Universe::heap()->flush_deferred_store_barrier(this);
1922 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1923
1924 #if INCLUDE_ALL_GCS
1925 // We must flush the G1-related buffers before removing a thread
1926 // from the list of active threads. We must do this after any deferred
1927 // card marks have been flushed (above) so that any entries that are
1928 // added to the thread's dirty card queue as a result are not lost.
1929 if (UseG1GC) {
1930 flush_barrier_queues();
1931 }
1932 #endif // INCLUDE_ALL_GCS
1933
1934 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1935 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1936 os::current_thread_id());
1937
1938 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1939 Threads::remove(this);
1940 }
1941
1942 #if INCLUDE_ALL_GCS
1943 // Flush G1-related queues.
1944 void JavaThread::flush_barrier_queues() {
1945 satb_mark_queue().flush();
1946 dirty_card_queue().flush();
1947 }
1948
1949 void JavaThread::initialize_queues() {
1950 assert(!SafepointSynchronize::is_at_safepoint(),
1951 "we should not be at a safepoint");
1952
1953 SATBMarkQueue& satb_queue = satb_mark_queue();
1954 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1955 // The SATB queue should have been constructed with its active
1956 // field set to false.
1957 assert(!satb_queue.is_active(), "SATB queue should not be active");
1958 assert(satb_queue.is_empty(), "SATB queue should be empty");
1959 // If we are creating the thread during a marking cycle, we should
1960 // set the active field of the SATB queue to true.
1961 if (satb_queue_set.is_active()) {
1962 satb_queue.set_active(true);
1963 }
1964
1965 DirtyCardQueue& dirty_queue = dirty_card_queue();
1966 // The dirty card queue should have been constructed with its
1967 // active field set to true.
1968 assert(dirty_queue.is_active(), "dirty card queue should be active");
1969 }
1970 #endif // INCLUDE_ALL_GCS
1971
1972 void JavaThread::cleanup_failed_attach_current_thread() {
1973 if (get_thread_profiler() != NULL) {
1974 get_thread_profiler()->disengage();
1975 ResourceMark rm;
1976 get_thread_profiler()->print(get_thread_name());
1977 }
1978
1979 if (active_handles() != NULL) {
1980 JNIHandleBlock* block = active_handles();
1981 set_active_handles(NULL);
1982 JNIHandleBlock::release_block(block);
1983 }
1984
1985 if (free_handle_block() != NULL) {
1986 JNIHandleBlock* block = free_handle_block();
1987 set_free_handle_block(NULL);
1988 JNIHandleBlock::release_block(block);
1989 }
1990
1991 // These have to be removed while this is still a valid thread.
1992 remove_stack_guard_pages();
1993
1994 if (UseTLAB) {
1995 tlab().make_parsable(true); // retire TLAB, if any
1996 }
1997
1998 #if INCLUDE_ALL_GCS
1999 if (UseG1GC) {
2000 flush_barrier_queues();
2001 }
2002 #endif // INCLUDE_ALL_GCS
2003
2004 Threads::remove(this);
2005 delete this;
2006 }
2007
2008
2009
2010
2011 JavaThread* JavaThread::active() {
2012 Thread* thread = Thread::current();
2013 if (thread->is_Java_thread()) {
2014 return (JavaThread*) thread;
2015 } else {
2016 assert(thread->is_VM_thread(), "this must be a vm thread");
2017 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2018 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2019 assert(ret->is_Java_thread(), "must be a Java thread");
2020 return ret;
2021 }
2022 }
2023
2024 bool JavaThread::is_lock_owned(address adr) const {
2025 if (Thread::is_lock_owned(adr)) return true;
2026
2027 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2028 if (chunk->contains(adr)) return true;
2029 }
2030
2031 return false;
2032 }
2033
2034
2035 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2036 chunk->set_next(monitor_chunks());
2037 set_monitor_chunks(chunk);
2038 }
2039
2040 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2041 guarantee(monitor_chunks() != NULL, "must be non empty");
2042 if (monitor_chunks() == chunk) {
2043 set_monitor_chunks(chunk->next());
2044 } else {
2045 MonitorChunk* prev = monitor_chunks();
2046 while (prev->next() != chunk) prev = prev->next();
2047 prev->set_next(chunk->next());
2048 }
2049 }
2050
2051 // JVM support.
2052
2053 // Note: this function shouldn't block if it's called in
2054 // _thread_in_native_trans state (such as from
2055 // check_special_condition_for_native_trans()).
2056 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2057
2058 if (has_last_Java_frame() && has_async_condition()) {
2059 // If we are at a polling page safepoint (not a poll return)
2060 // then we must defer async exception because live registers
2061 // will be clobbered by the exception path. Poll return is
2062 // ok because the call we a returning from already collides
2063 // with exception handling registers and so there is no issue.
2064 // (The exception handling path kills call result registers but
2065 // this is ok since the exception kills the result anyway).
2066
2067 if (is_at_poll_safepoint()) {
2068 // if the code we are returning to has deoptimized we must defer
2069 // the exception otherwise live registers get clobbered on the
2070 // exception path before deoptimization is able to retrieve them.
2071 //
2072 RegisterMap map(this, false);
2073 frame caller_fr = last_frame().sender(&map);
2074 assert(caller_fr.is_compiled_frame(), "what?");
2075 if (caller_fr.is_deoptimized_frame()) {
2076 log_info(exceptions)("deferred async exception at compiled safepoint");
2077 return;
2078 }
2079 }
2080 }
2081
2082 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2083 if (condition == _no_async_condition) {
2084 // Conditions have changed since has_special_runtime_exit_condition()
2085 // was called:
2086 // - if we were here only because of an external suspend request,
2087 // then that was taken care of above (or cancelled) so we are done
2088 // - if we were here because of another async request, then it has
2089 // been cleared between the has_special_runtime_exit_condition()
2090 // and now so again we are done
2091 return;
2092 }
2093
2094 // Check for pending async. exception
2095 if (_pending_async_exception != NULL) {
2096 // Only overwrite an already pending exception, if it is not a threadDeath.
2097 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2098
2099 // We cannot call Exceptions::_throw(...) here because we cannot block
2100 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2101
2102 if (log_is_enabled(Info, exceptions)) {
2103 ResourceMark rm;
2104 outputStream* logstream = Log(exceptions)::info_stream();
2105 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2106 if (has_last_Java_frame()) {
2107 frame f = last_frame();
2108 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2109 }
2110 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2111 }
2112 _pending_async_exception = NULL;
2113 clear_has_async_exception();
2114 }
2115 }
2116
2117 if (check_unsafe_error &&
2118 condition == _async_unsafe_access_error && !has_pending_exception()) {
2119 condition = _no_async_condition; // done
2120 switch (thread_state()) {
2121 case _thread_in_vm: {
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_native: {
2126 ThreadInVMfromNative tiv(this);
2127 JavaThread* THREAD = this;
2128 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2129 }
2130 case _thread_in_Java: {
2131 ThreadInVMfromJava tiv(this);
2132 JavaThread* THREAD = this;
2133 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2134 }
2135 default:
2136 ShouldNotReachHere();
2137 }
2138 }
2139
2140 assert(condition == _no_async_condition || has_pending_exception() ||
2141 (!check_unsafe_error && condition == _async_unsafe_access_error),
2142 "must have handled the async condition, if no exception");
2143 }
2144
2145 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2146 //
2147 // Check for pending external suspend. Internal suspend requests do
2148 // not use handle_special_runtime_exit_condition().
2149 // If JNIEnv proxies are allowed, don't self-suspend if the target
2150 // thread is not the current thread. In older versions of jdbx, jdbx
2151 // threads could call into the VM with another thread's JNIEnv so we
2152 // can be here operating on behalf of a suspended thread (4432884).
2153 bool do_self_suspend = is_external_suspend_with_lock();
2154 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2155 //
2156 // Because thread is external suspended the safepoint code will count
2157 // thread as at a safepoint. This can be odd because we can be here
2158 // as _thread_in_Java which would normally transition to _thread_blocked
2159 // at a safepoint. We would like to mark the thread as _thread_blocked
2160 // before calling java_suspend_self like all other callers of it but
2161 // we must then observe proper safepoint protocol. (We can't leave
2162 // _thread_blocked with a safepoint in progress). However we can be
2163 // here as _thread_in_native_trans so we can't use a normal transition
2164 // constructor/destructor pair because they assert on that type of
2165 // transition. We could do something like:
2166 //
2167 // JavaThreadState state = thread_state();
2168 // set_thread_state(_thread_in_vm);
2169 // {
2170 // ThreadBlockInVM tbivm(this);
2171 // java_suspend_self()
2172 // }
2173 // set_thread_state(_thread_in_vm_trans);
2174 // if (safepoint) block;
2175 // set_thread_state(state);
2176 //
2177 // but that is pretty messy. Instead we just go with the way the
2178 // code has worked before and note that this is the only path to
2179 // java_suspend_self that doesn't put the thread in _thread_blocked
2180 // mode.
2181
2182 frame_anchor()->make_walkable(this);
2183 java_suspend_self();
2184
2185 // We might be here for reasons in addition to the self-suspend request
2186 // so check for other async requests.
2187 }
2188
2189 if (check_asyncs) {
2190 check_and_handle_async_exceptions();
2191 }
2192 }
2193
2194 void JavaThread::send_thread_stop(oop java_throwable) {
2195 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2196 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2197 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2198
2199 // Do not throw asynchronous exceptions against the compiler thread
2200 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2201 if (!can_call_java()) return;
2202
2203 {
2204 // Actually throw the Throwable against the target Thread - however
2205 // only if there is no thread death exception installed already.
2206 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2207 // If the topmost frame is a runtime stub, then we are calling into
2208 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2209 // must deoptimize the caller before continuing, as the compiled exception handler table
2210 // may not be valid
2211 if (has_last_Java_frame()) {
2212 frame f = last_frame();
2213 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2214 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2215 RegisterMap reg_map(this, UseBiasedLocking);
2216 frame compiled_frame = f.sender(®_map);
2217 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2218 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2219 }
2220 }
2221 }
2222
2223 // Set async. pending exception in thread.
2224 set_pending_async_exception(java_throwable);
2225
2226 if (log_is_enabled(Info, exceptions)) {
2227 ResourceMark rm;
2228 log_info(exceptions)("Pending Async. exception installed of type: %s",
2229 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2230 }
2231 // for AbortVMOnException flag
2232 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2233 }
2234 }
2235
2236
2237 // Interrupt thread so it will wake up from a potential wait()
2238 Thread::interrupt(this);
2239 }
2240
2241 // External suspension mechanism.
2242 //
2243 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2244 // to any VM_locks and it is at a transition
2245 // Self-suspension will happen on the transition out of the vm.
2246 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2247 //
2248 // Guarantees on return:
2249 // + Target thread will not execute any new bytecode (that's why we need to
2250 // force a safepoint)
2251 // + Target thread will not enter any new monitors
2252 //
2253 void JavaThread::java_suspend() {
2254 { MutexLocker mu(Threads_lock);
2255 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2256 return;
2257 }
2258 }
2259
2260 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2261 if (!is_external_suspend()) {
2262 // a racing resume has cancelled us; bail out now
2263 return;
2264 }
2265
2266 // suspend is done
2267 uint32_t debug_bits = 0;
2268 // Warning: is_ext_suspend_completed() may temporarily drop the
2269 // SR_lock to allow the thread to reach a stable thread state if
2270 // it is currently in a transient thread state.
2271 if (is_ext_suspend_completed(false /* !called_by_wait */,
2272 SuspendRetryDelay, &debug_bits)) {
2273 return;
2274 }
2275 }
2276
2277 VM_ForceSafepoint vm_suspend;
2278 VMThread::execute(&vm_suspend);
2279 }
2280
2281 // Part II of external suspension.
2282 // A JavaThread self suspends when it detects a pending external suspend
2283 // request. This is usually on transitions. It is also done in places
2284 // where continuing to the next transition would surprise the caller,
2285 // e.g., monitor entry.
2286 //
2287 // Returns the number of times that the thread self-suspended.
2288 //
2289 // Note: DO NOT call java_suspend_self() when you just want to block current
2290 // thread. java_suspend_self() is the second stage of cooperative
2291 // suspension for external suspend requests and should only be used
2292 // to complete an external suspend request.
2293 //
2294 int JavaThread::java_suspend_self() {
2295 int ret = 0;
2296
2297 // we are in the process of exiting so don't suspend
2298 if (is_exiting()) {
2299 clear_external_suspend();
2300 return ret;
2301 }
2302
2303 assert(_anchor.walkable() ||
2304 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2305 "must have walkable stack");
2306
2307 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2308
2309 assert(!this->is_ext_suspended(),
2310 "a thread trying to self-suspend should not already be suspended");
2311
2312 if (this->is_suspend_equivalent()) {
2313 // If we are self-suspending as a result of the lifting of a
2314 // suspend equivalent condition, then the suspend_equivalent
2315 // flag is not cleared until we set the ext_suspended flag so
2316 // that wait_for_ext_suspend_completion() returns consistent
2317 // results.
2318 this->clear_suspend_equivalent();
2319 }
2320
2321 // A racing resume may have cancelled us before we grabbed SR_lock
2322 // above. Or another external suspend request could be waiting for us
2323 // by the time we return from SR_lock()->wait(). The thread
2324 // that requested the suspension may already be trying to walk our
2325 // stack and if we return now, we can change the stack out from under
2326 // it. This would be a "bad thing (TM)" and cause the stack walker
2327 // to crash. We stay self-suspended until there are no more pending
2328 // external suspend requests.
2329 while (is_external_suspend()) {
2330 ret++;
2331 this->set_ext_suspended();
2332
2333 // _ext_suspended flag is cleared by java_resume()
2334 while (is_ext_suspended()) {
2335 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2336 }
2337 }
2338
2339 return ret;
2340 }
2341
2342 #ifdef ASSERT
2343 // verify the JavaThread has not yet been published in the Threads::list, and
2344 // hence doesn't need protection from concurrent access at this stage
2345 void JavaThread::verify_not_published() {
2346 if (!Threads_lock->owned_by_self()) {
2347 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2348 assert(!Threads::includes(this),
2349 "java thread shouldn't have been published yet!");
2350 } else {
2351 assert(!Threads::includes(this),
2352 "java thread shouldn't have been published yet!");
2353 }
2354 }
2355 #endif
2356
2357 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2358 // progress or when _suspend_flags is non-zero.
2359 // Current thread needs to self-suspend if there is a suspend request and/or
2360 // block if a safepoint is in progress.
2361 // Async exception ISN'T checked.
2362 // Note only the ThreadInVMfromNative transition can call this function
2363 // directly and when thread state is _thread_in_native_trans
2364 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2365 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2366
2367 JavaThread *curJT = JavaThread::current();
2368 bool do_self_suspend = thread->is_external_suspend();
2369
2370 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2371
2372 // If JNIEnv proxies are allowed, don't self-suspend if the target
2373 // thread is not the current thread. In older versions of jdbx, jdbx
2374 // threads could call into the VM with another thread's JNIEnv so we
2375 // can be here operating on behalf of a suspended thread (4432884).
2376 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2377 JavaThreadState state = thread->thread_state();
2378
2379 // We mark this thread_blocked state as a suspend-equivalent so
2380 // that a caller to is_ext_suspend_completed() won't be confused.
2381 // The suspend-equivalent state is cleared by java_suspend_self().
2382 thread->set_suspend_equivalent();
2383
2384 // If the safepoint code sees the _thread_in_native_trans state, it will
2385 // wait until the thread changes to other thread state. There is no
2386 // guarantee on how soon we can obtain the SR_lock and complete the
2387 // self-suspend request. It would be a bad idea to let safepoint wait for
2388 // too long. Temporarily change the state to _thread_blocked to
2389 // let the VM thread know that this thread is ready for GC. The problem
2390 // of changing thread state is that safepoint could happen just after
2391 // java_suspend_self() returns after being resumed, and VM thread will
2392 // see the _thread_blocked state. We must check for safepoint
2393 // after restoring the state and make sure we won't leave while a safepoint
2394 // is in progress.
2395 thread->set_thread_state(_thread_blocked);
2396 thread->java_suspend_self();
2397 thread->set_thread_state(state);
2398 // Make sure new state is seen by VM thread
2399 if (os::is_MP()) {
2400 if (UseMembar) {
2401 // Force a fence between the write above and read below
2402 OrderAccess::fence();
2403 } else {
2404 // Must use this rather than serialization page in particular on Windows
2405 InterfaceSupport::serialize_memory(thread);
2406 }
2407 }
2408 }
2409
2410 if (SafepointSynchronize::do_call_back()) {
2411 // If we are safepointing, then block the caller which may not be
2412 // the same as the target thread (see above).
2413 SafepointSynchronize::block(curJT);
2414 }
2415
2416 if (thread->is_deopt_suspend()) {
2417 thread->clear_deopt_suspend();
2418 RegisterMap map(thread, false);
2419 frame f = thread->last_frame();
2420 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2421 f = f.sender(&map);
2422 }
2423 if (f.id() == thread->must_deopt_id()) {
2424 thread->clear_must_deopt_id();
2425 f.deoptimize(thread);
2426 } else {
2427 fatal("missed deoptimization!");
2428 }
2429 }
2430 }
2431
2432 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2433 // progress or when _suspend_flags is non-zero.
2434 // Current thread needs to self-suspend if there is a suspend request and/or
2435 // block if a safepoint is in progress.
2436 // Also check for pending async exception (not including unsafe access error).
2437 // Note only the native==>VM/Java barriers can call this function and when
2438 // thread state is _thread_in_native_trans.
2439 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2440 check_safepoint_and_suspend_for_native_trans(thread);
2441
2442 if (thread->has_async_exception()) {
2443 // We are in _thread_in_native_trans state, don't handle unsafe
2444 // access error since that may block.
2445 thread->check_and_handle_async_exceptions(false);
2446 }
2447 }
2448
2449 // This is a variant of the normal
2450 // check_special_condition_for_native_trans with slightly different
2451 // semantics for use by critical native wrappers. It does all the
2452 // normal checks but also performs the transition back into
2453 // thread_in_Java state. This is required so that critical natives
2454 // can potentially block and perform a GC if they are the last thread
2455 // exiting the GCLocker.
2456 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2457 check_special_condition_for_native_trans(thread);
2458
2459 // Finish the transition
2460 thread->set_thread_state(_thread_in_Java);
2461
2462 if (thread->do_critical_native_unlock()) {
2463 ThreadInVMfromJavaNoAsyncException tiv(thread);
2464 GCLocker::unlock_critical(thread);
2465 thread->clear_critical_native_unlock();
2466 }
2467 }
2468
2469 // We need to guarantee the Threads_lock here, since resumes are not
2470 // allowed during safepoint synchronization
2471 // Can only resume from an external suspension
2472 void JavaThread::java_resume() {
2473 assert_locked_or_safepoint(Threads_lock);
2474
2475 // Sanity check: thread is gone, has started exiting or the thread
2476 // was not externally suspended.
2477 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2478 return;
2479 }
2480
2481 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2482
2483 clear_external_suspend();
2484
2485 if (is_ext_suspended()) {
2486 clear_ext_suspended();
2487 SR_lock()->notify_all();
2488 }
2489 }
2490
2491 size_t JavaThread::_stack_red_zone_size = 0;
2492 size_t JavaThread::_stack_yellow_zone_size = 0;
2493 size_t JavaThread::_stack_reserved_zone_size = 0;
2494 size_t JavaThread::_stack_shadow_zone_size = 0;
2495
2496 void JavaThread::create_stack_guard_pages() {
2497 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2498 address low_addr = stack_end();
2499 size_t len = stack_guard_zone_size();
2500
2501 int must_commit = os::must_commit_stack_guard_pages();
2502 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2503
2504 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2505 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2506 return;
2507 }
2508
2509 if (os::guard_memory((char *) low_addr, len)) {
2510 _stack_guard_state = stack_guard_enabled;
2511 } else {
2512 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2513 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2514 if (os::uncommit_memory((char *) low_addr, len)) {
2515 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2516 }
2517 return;
2518 }
2519
2520 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2521 PTR_FORMAT "-" PTR_FORMAT ".",
2522 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2523 }
2524
2525 void JavaThread::remove_stack_guard_pages() {
2526 assert(Thread::current() == this, "from different thread");
2527 if (_stack_guard_state == stack_guard_unused) return;
2528 address low_addr = stack_end();
2529 size_t len = stack_guard_zone_size();
2530
2531 if (os::must_commit_stack_guard_pages()) {
2532 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2533 _stack_guard_state = stack_guard_unused;
2534 } else {
2535 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2536 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2537 return;
2538 }
2539 } else {
2540 if (_stack_guard_state == stack_guard_unused) return;
2541 if (os::unguard_memory((char *) low_addr, len)) {
2542 _stack_guard_state = stack_guard_unused;
2543 } else {
2544 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2545 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2546 return;
2547 }
2548 }
2549
2550 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2551 PTR_FORMAT "-" PTR_FORMAT ".",
2552 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2553 }
2554
2555 void JavaThread::enable_stack_reserved_zone() {
2556 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2557 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2558
2559 // The base notation is from the stack's point of view, growing downward.
2560 // We need to adjust it to work correctly with guard_memory()
2561 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2562
2563 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2564 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2565
2566 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2567 _stack_guard_state = stack_guard_enabled;
2568 } else {
2569 warning("Attempt to guard stack reserved zone failed.");
2570 }
2571 enable_register_stack_guard();
2572 }
2573
2574 void JavaThread::disable_stack_reserved_zone() {
2575 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2576 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2577
2578 // Simply return if called for a thread that does not use guard pages.
2579 if (_stack_guard_state == stack_guard_unused) return;
2580
2581 // The base notation is from the stack's point of view, growing downward.
2582 // We need to adjust it to work correctly with guard_memory()
2583 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2584
2585 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2586 _stack_guard_state = stack_guard_reserved_disabled;
2587 } else {
2588 warning("Attempt to unguard stack reserved zone failed.");
2589 }
2590 disable_register_stack_guard();
2591 }
2592
2593 void JavaThread::enable_stack_yellow_reserved_zone() {
2594 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2595 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2596
2597 // The base notation is from the stacks point of view, growing downward.
2598 // We need to adjust it to work correctly with guard_memory()
2599 address base = stack_red_zone_base();
2600
2601 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2602 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2603
2604 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2605 _stack_guard_state = stack_guard_enabled;
2606 } else {
2607 warning("Attempt to guard stack yellow zone failed.");
2608 }
2609 enable_register_stack_guard();
2610 }
2611
2612 void JavaThread::disable_stack_yellow_reserved_zone() {
2613 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2614 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2615
2616 // Simply return if called for a thread that does not use guard pages.
2617 if (_stack_guard_state == stack_guard_unused) return;
2618
2619 // The base notation is from the stacks point of view, growing downward.
2620 // We need to adjust it to work correctly with guard_memory()
2621 address base = stack_red_zone_base();
2622
2623 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2624 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2625 } else {
2626 warning("Attempt to unguard stack yellow zone failed.");
2627 }
2628 disable_register_stack_guard();
2629 }
2630
2631 void JavaThread::enable_stack_red_zone() {
2632 // The base notation is from the stacks point of view, growing downward.
2633 // We need to adjust it to work correctly with guard_memory()
2634 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2635 address base = stack_red_zone_base() - stack_red_zone_size();
2636
2637 guarantee(base < stack_base(), "Error calculating stack red zone");
2638 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2639
2640 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2641 warning("Attempt to guard stack red zone failed.");
2642 }
2643 }
2644
2645 void JavaThread::disable_stack_red_zone() {
2646 // The base notation is from the stacks point of view, growing downward.
2647 // We need to adjust it to work correctly with guard_memory()
2648 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2649 address base = stack_red_zone_base() - stack_red_zone_size();
2650 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2651 warning("Attempt to unguard stack red zone failed.");
2652 }
2653 }
2654
2655 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2656 // ignore is there is no stack
2657 if (!has_last_Java_frame()) return;
2658 // traverse the stack frames. Starts from top frame.
2659 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2660 frame* fr = fst.current();
2661 f(fr, fst.register_map());
2662 }
2663 }
2664
2665
2666 #ifndef PRODUCT
2667 // Deoptimization
2668 // Function for testing deoptimization
2669 void JavaThread::deoptimize() {
2670 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2671 StackFrameStream fst(this, UseBiasedLocking);
2672 bool deopt = false; // Dump stack only if a deopt actually happens.
2673 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2674 // Iterate over all frames in the thread and deoptimize
2675 for (; !fst.is_done(); fst.next()) {
2676 if (fst.current()->can_be_deoptimized()) {
2677
2678 if (only_at) {
2679 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2680 // consists of comma or carriage return separated numbers so
2681 // search for the current bci in that string.
2682 address pc = fst.current()->pc();
2683 nmethod* nm = (nmethod*) fst.current()->cb();
2684 ScopeDesc* sd = nm->scope_desc_at(pc);
2685 char buffer[8];
2686 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2687 size_t len = strlen(buffer);
2688 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2689 while (found != NULL) {
2690 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2691 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2692 // Check that the bci found is bracketed by terminators.
2693 break;
2694 }
2695 found = strstr(found + 1, buffer);
2696 }
2697 if (!found) {
2698 continue;
2699 }
2700 }
2701
2702 if (DebugDeoptimization && !deopt) {
2703 deopt = true; // One-time only print before deopt
2704 tty->print_cr("[BEFORE Deoptimization]");
2705 trace_frames();
2706 trace_stack();
2707 }
2708 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2709 }
2710 }
2711
2712 if (DebugDeoptimization && deopt) {
2713 tty->print_cr("[AFTER Deoptimization]");
2714 trace_frames();
2715 }
2716 }
2717
2718
2719 // Make zombies
2720 void JavaThread::make_zombies() {
2721 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2722 if (fst.current()->can_be_deoptimized()) {
2723 // it is a Java nmethod
2724 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2725 nm->make_not_entrant();
2726 }
2727 }
2728 }
2729 #endif // PRODUCT
2730
2731
2732 void JavaThread::deoptimized_wrt_marked_nmethods() {
2733 if (!has_last_Java_frame()) return;
2734 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2735 StackFrameStream fst(this, UseBiasedLocking);
2736 for (; !fst.is_done(); fst.next()) {
2737 if (fst.current()->should_be_deoptimized()) {
2738 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2739 }
2740 }
2741 }
2742
2743
2744 // If the caller is a NamedThread, then remember, in the current scope,
2745 // the given JavaThread in its _processed_thread field.
2746 class RememberProcessedThread: public StackObj {
2747 NamedThread* _cur_thr;
2748 public:
2749 RememberProcessedThread(JavaThread* jthr) {
2750 Thread* thread = Thread::current();
2751 if (thread->is_Named_thread()) {
2752 _cur_thr = (NamedThread *)thread;
2753 _cur_thr->set_processed_thread(jthr);
2754 } else {
2755 _cur_thr = NULL;
2756 }
2757 }
2758
2759 ~RememberProcessedThread() {
2760 if (_cur_thr) {
2761 _cur_thr->set_processed_thread(NULL);
2762 }
2763 }
2764 };
2765
2766 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2767 // Verify that the deferred card marks have been flushed.
2768 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2769
2770 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2771 // since there may be more than one thread using each ThreadProfiler.
2772
2773 // Traverse the GCHandles
2774 Thread::oops_do(f, cf);
2775
2776 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2777
2778 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2779 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2780
2781 if (has_last_Java_frame()) {
2782 // Record JavaThread to GC thread
2783 RememberProcessedThread rpt(this);
2784
2785 // Traverse the privileged stack
2786 if (_privileged_stack_top != NULL) {
2787 _privileged_stack_top->oops_do(f);
2788 }
2789
2790 // traverse the registered growable array
2791 if (_array_for_gc != NULL) {
2792 for (int index = 0; index < _array_for_gc->length(); index++) {
2793 f->do_oop(_array_for_gc->adr_at(index));
2794 }
2795 }
2796
2797 // Traverse the monitor chunks
2798 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2799 chunk->oops_do(f);
2800 }
2801
2802 // Traverse the execution stack
2803 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2804 fst.current()->oops_do(f, cf, fst.register_map());
2805 }
2806 }
2807
2808 // callee_target is never live across a gc point so NULL it here should
2809 // it still contain a methdOop.
2810
2811 set_callee_target(NULL);
2812
2813 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2814 // If we have deferred set_locals there might be oops waiting to be
2815 // written
2816 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2817 if (list != NULL) {
2818 for (int i = 0; i < list->length(); i++) {
2819 list->at(i)->oops_do(f);
2820 }
2821 }
2822
2823 // Traverse instance variables at the end since the GC may be moving things
2824 // around using this function
2825 f->do_oop((oop*) &_threadObj);
2826 f->do_oop((oop*) &_vm_result);
2827 f->do_oop((oop*) &_exception_oop);
2828 f->do_oop((oop*) &_pending_async_exception);
2829
2830 if (jvmti_thread_state() != NULL) {
2831 jvmti_thread_state()->oops_do(f);
2832 }
2833 }
2834
2835 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2836 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2837 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2838
2839 if (has_last_Java_frame()) {
2840 // Traverse the execution stack
2841 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2842 fst.current()->nmethods_do(cf);
2843 }
2844 }
2845 }
2846
2847 void JavaThread::metadata_do(void f(Metadata*)) {
2848 if (has_last_Java_frame()) {
2849 // Traverse the execution stack to call f() on the methods in the stack
2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851 fst.current()->metadata_do(f);
2852 }
2853 } else if (is_Compiler_thread()) {
2854 // need to walk ciMetadata in current compile tasks to keep alive.
2855 CompilerThread* ct = (CompilerThread*)this;
2856 if (ct->env() != NULL) {
2857 ct->env()->metadata_do(f);
2858 }
2859 if (ct->task() != NULL) {
2860 ct->task()->metadata_do(f);
2861 }
2862 }
2863 }
2864
2865 // Printing
2866 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2867 switch (_thread_state) {
2868 case _thread_uninitialized: return "_thread_uninitialized";
2869 case _thread_new: return "_thread_new";
2870 case _thread_new_trans: return "_thread_new_trans";
2871 case _thread_in_native: return "_thread_in_native";
2872 case _thread_in_native_trans: return "_thread_in_native_trans";
2873 case _thread_in_vm: return "_thread_in_vm";
2874 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2875 case _thread_in_Java: return "_thread_in_Java";
2876 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2877 case _thread_blocked: return "_thread_blocked";
2878 case _thread_blocked_trans: return "_thread_blocked_trans";
2879 default: return "unknown thread state";
2880 }
2881 }
2882
2883 #ifndef PRODUCT
2884 void JavaThread::print_thread_state_on(outputStream *st) const {
2885 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2886 };
2887 void JavaThread::print_thread_state() const {
2888 print_thread_state_on(tty);
2889 }
2890 #endif // PRODUCT
2891
2892 // Called by Threads::print() for VM_PrintThreads operation
2893 void JavaThread::print_on(outputStream *st) const {
2894 st->print_raw("\"");
2895 st->print_raw(get_thread_name());
2896 st->print_raw("\" ");
2897 oop thread_oop = threadObj();
2898 if (thread_oop != NULL) {
2899 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2900 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2901 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2902 }
2903 Thread::print_on(st);
2904 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2905 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2906 if (thread_oop != NULL) {
2907 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2908 }
2909 #ifndef PRODUCT
2910 print_thread_state_on(st);
2911 _safepoint_state->print_on(st);
2912 #endif // PRODUCT
2913 if (is_Compiler_thread()) {
2914 CompilerThread* ct = (CompilerThread*)this;
2915 if (ct->task() != NULL) {
2916 st->print(" Compiling: ");
2917 ct->task()->print(st, NULL, true, false);
2918 } else {
2919 st->print(" No compile task");
2920 }
2921 st->cr();
2922 }
2923 }
2924
2925 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2926 st->print("%s", get_thread_name_string(buf, buflen));
2927 }
2928
2929 // Called by fatal error handler. The difference between this and
2930 // JavaThread::print() is that we can't grab lock or allocate memory.
2931 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2932 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2933 oop thread_obj = threadObj();
2934 if (thread_obj != NULL) {
2935 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2936 }
2937 st->print(" [");
2938 st->print("%s", _get_thread_state_name(_thread_state));
2939 if (osthread()) {
2940 st->print(", id=%d", osthread()->thread_id());
2941 }
2942 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2943 p2i(stack_end()), p2i(stack_base()));
2944 st->print("]");
2945 return;
2946 }
2947
2948 // Verification
2949
2950 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2951
2952 void JavaThread::verify() {
2953 // Verify oops in the thread.
2954 oops_do(&VerifyOopClosure::verify_oop, NULL);
2955
2956 // Verify the stack frames.
2957 frames_do(frame_verify);
2958 }
2959
2960 // CR 6300358 (sub-CR 2137150)
2961 // Most callers of this method assume that it can't return NULL but a
2962 // thread may not have a name whilst it is in the process of attaching to
2963 // the VM - see CR 6412693, and there are places where a JavaThread can be
2964 // seen prior to having it's threadObj set (eg JNI attaching threads and
2965 // if vm exit occurs during initialization). These cases can all be accounted
2966 // for such that this method never returns NULL.
2967 const char* JavaThread::get_thread_name() const {
2968 #ifdef ASSERT
2969 // early safepoints can hit while current thread does not yet have TLS
2970 if (!SafepointSynchronize::is_at_safepoint()) {
2971 Thread *cur = Thread::current();
2972 if (!(cur->is_Java_thread() && cur == this)) {
2973 // Current JavaThreads are allowed to get their own name without
2974 // the Threads_lock.
2975 assert_locked_or_safepoint(Threads_lock);
2976 }
2977 }
2978 #endif // ASSERT
2979 return get_thread_name_string();
2980 }
2981
2982 // Returns a non-NULL representation of this thread's name, or a suitable
2983 // descriptive string if there is no set name
2984 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2985 const char* name_str;
2986 oop thread_obj = threadObj();
2987 if (thread_obj != NULL) {
2988 oop name = java_lang_Thread::name(thread_obj);
2989 if (name != NULL) {
2990 if (buf == NULL) {
2991 name_str = java_lang_String::as_utf8_string(name);
2992 } else {
2993 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2994 }
2995 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2996 name_str = "<no-name - thread is attaching>";
2997 } else {
2998 name_str = Thread::name();
2999 }
3000 } else {
3001 name_str = Thread::name();
3002 }
3003 assert(name_str != NULL, "unexpected NULL thread name");
3004 return name_str;
3005 }
3006
3007
3008 const char* JavaThread::get_threadgroup_name() const {
3009 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3010 oop thread_obj = threadObj();
3011 if (thread_obj != NULL) {
3012 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3013 if (thread_group != NULL) {
3014 // ThreadGroup.name can be null
3015 return java_lang_ThreadGroup::name(thread_group);
3016 }
3017 }
3018 return NULL;
3019 }
3020
3021 const char* JavaThread::get_parent_name() const {
3022 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3023 oop thread_obj = threadObj();
3024 if (thread_obj != NULL) {
3025 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3026 if (thread_group != NULL) {
3027 oop parent = java_lang_ThreadGroup::parent(thread_group);
3028 if (parent != NULL) {
3029 // ThreadGroup.name can be null
3030 return java_lang_ThreadGroup::name(parent);
3031 }
3032 }
3033 }
3034 return NULL;
3035 }
3036
3037 ThreadPriority JavaThread::java_priority() const {
3038 oop thr_oop = threadObj();
3039 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3040 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3041 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3042 return priority;
3043 }
3044
3045 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3046
3047 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3048 // Link Java Thread object <-> C++ Thread
3049
3050 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3051 // and put it into a new Handle. The Handle "thread_oop" can then
3052 // be used to pass the C++ thread object to other methods.
3053
3054 // Set the Java level thread object (jthread) field of the
3055 // new thread (a JavaThread *) to C++ thread object using the
3056 // "thread_oop" handle.
3057
3058 // Set the thread field (a JavaThread *) of the
3059 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3060
3061 Handle thread_oop(Thread::current(),
3062 JNIHandles::resolve_non_null(jni_thread));
3063 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3064 "must be initialized");
3065 set_threadObj(thread_oop());
3066 java_lang_Thread::set_thread(thread_oop(), this);
3067
3068 if (prio == NoPriority) {
3069 prio = java_lang_Thread::priority(thread_oop());
3070 assert(prio != NoPriority, "A valid priority should be present");
3071 }
3072
3073 // Push the Java priority down to the native thread; needs Threads_lock
3074 Thread::set_priority(this, prio);
3075
3076 prepare_ext();
3077
3078 // Add the new thread to the Threads list and set it in motion.
3079 // We must have threads lock in order to call Threads::add.
3080 // It is crucial that we do not block before the thread is
3081 // added to the Threads list for if a GC happens, then the java_thread oop
3082 // will not be visited by GC.
3083 Threads::add(this);
3084 }
3085
3086 oop JavaThread::current_park_blocker() {
3087 // Support for JSR-166 locks
3088 oop thread_oop = threadObj();
3089 if (thread_oop != NULL &&
3090 JDK_Version::current().supports_thread_park_blocker()) {
3091 return java_lang_Thread::park_blocker(thread_oop);
3092 }
3093 return NULL;
3094 }
3095
3096
3097 void JavaThread::print_stack_on(outputStream* st) {
3098 if (!has_last_Java_frame()) return;
3099 ResourceMark rm;
3100 HandleMark hm;
3101
3102 RegisterMap reg_map(this);
3103 vframe* start_vf = last_java_vframe(®_map);
3104 int count = 0;
3105 for (vframe* f = start_vf; f; f = f->sender()) {
3106 if (f->is_java_frame()) {
3107 javaVFrame* jvf = javaVFrame::cast(f);
3108 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3109
3110 // Print out lock information
3111 if (JavaMonitorsInStackTrace) {
3112 jvf->print_lock_info_on(st, count);
3113 }
3114 } else {
3115 // Ignore non-Java frames
3116 }
3117
3118 // Bail-out case for too deep stacks
3119 count++;
3120 if (MaxJavaStackTraceDepth == count) return;
3121 }
3122 }
3123
3124
3125 // JVMTI PopFrame support
3126 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3127 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3128 if (in_bytes(size_in_bytes) != 0) {
3129 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3130 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3131 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3132 }
3133 }
3134
3135 void* JavaThread::popframe_preserved_args() {
3136 return _popframe_preserved_args;
3137 }
3138
3139 ByteSize JavaThread::popframe_preserved_args_size() {
3140 return in_ByteSize(_popframe_preserved_args_size);
3141 }
3142
3143 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3144 int sz = in_bytes(popframe_preserved_args_size());
3145 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3146 return in_WordSize(sz / wordSize);
3147 }
3148
3149 void JavaThread::popframe_free_preserved_args() {
3150 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3151 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3152 _popframe_preserved_args = NULL;
3153 _popframe_preserved_args_size = 0;
3154 }
3155
3156 #ifndef PRODUCT
3157
3158 void JavaThread::trace_frames() {
3159 tty->print_cr("[Describe stack]");
3160 int frame_no = 1;
3161 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3162 tty->print(" %d. ", frame_no++);
3163 fst.current()->print_value_on(tty, this);
3164 tty->cr();
3165 }
3166 }
3167
3168 class PrintAndVerifyOopClosure: public OopClosure {
3169 protected:
3170 template <class T> inline void do_oop_work(T* p) {
3171 oop obj = oopDesc::load_decode_heap_oop(p);
3172 if (obj == NULL) return;
3173 tty->print(INTPTR_FORMAT ": ", p2i(p));
3174 if (obj->is_oop_or_null()) {
3175 if (obj->is_objArray()) {
3176 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3177 } else {
3178 obj->print();
3179 }
3180 } else {
3181 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3182 }
3183 tty->cr();
3184 }
3185 public:
3186 virtual void do_oop(oop* p) { do_oop_work(p); }
3187 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3188 };
3189
3190
3191 static void oops_print(frame* f, const RegisterMap *map) {
3192 PrintAndVerifyOopClosure print;
3193 f->print_value();
3194 f->oops_do(&print, NULL, (RegisterMap*)map);
3195 }
3196
3197 // Print our all the locations that contain oops and whether they are
3198 // valid or not. This useful when trying to find the oldest frame
3199 // where an oop has gone bad since the frame walk is from youngest to
3200 // oldest.
3201 void JavaThread::trace_oops() {
3202 tty->print_cr("[Trace oops]");
3203 frames_do(oops_print);
3204 }
3205
3206
3207 #ifdef ASSERT
3208 // Print or validate the layout of stack frames
3209 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3210 ResourceMark rm;
3211 PRESERVE_EXCEPTION_MARK;
3212 FrameValues values;
3213 int frame_no = 0;
3214 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3215 fst.current()->describe(values, ++frame_no);
3216 if (depth == frame_no) break;
3217 }
3218 if (validate_only) {
3219 values.validate();
3220 } else {
3221 tty->print_cr("[Describe stack layout]");
3222 values.print(this);
3223 }
3224 }
3225 #endif
3226
3227 void JavaThread::trace_stack_from(vframe* start_vf) {
3228 ResourceMark rm;
3229 int vframe_no = 1;
3230 for (vframe* f = start_vf; f; f = f->sender()) {
3231 if (f->is_java_frame()) {
3232 javaVFrame::cast(f)->print_activation(vframe_no++);
3233 } else {
3234 f->print();
3235 }
3236 if (vframe_no > StackPrintLimit) {
3237 tty->print_cr("...<more frames>...");
3238 return;
3239 }
3240 }
3241 }
3242
3243
3244 void JavaThread::trace_stack() {
3245 if (!has_last_Java_frame()) return;
3246 ResourceMark rm;
3247 HandleMark hm;
3248 RegisterMap reg_map(this);
3249 trace_stack_from(last_java_vframe(®_map));
3250 }
3251
3252
3253 #endif // PRODUCT
3254
3255
3256 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3257 assert(reg_map != NULL, "a map must be given");
3258 frame f = last_frame();
3259 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3260 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3261 }
3262 return NULL;
3263 }
3264
3265
3266 Klass* JavaThread::security_get_caller_class(int depth) {
3267 vframeStream vfst(this);
3268 vfst.security_get_caller_frame(depth);
3269 if (!vfst.at_end()) {
3270 return vfst.method()->method_holder();
3271 }
3272 return NULL;
3273 }
3274
3275 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3276 assert(thread->is_Compiler_thread(), "must be compiler thread");
3277 CompileBroker::compiler_thread_loop();
3278 }
3279
3280 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3281 NMethodSweeper::sweeper_loop();
3282 }
3283
3284 // Create a CompilerThread
3285 CompilerThread::CompilerThread(CompileQueue* queue,
3286 CompilerCounters* counters)
3287 : JavaThread(&compiler_thread_entry) {
3288 _env = NULL;
3289 _log = NULL;
3290 _task = NULL;
3291 _queue = queue;
3292 _counters = counters;
3293 _buffer_blob = NULL;
3294 _compiler = NULL;
3295
3296 #ifndef PRODUCT
3297 _ideal_graph_printer = NULL;
3298 #endif
3299 }
3300
3301 bool CompilerThread::can_call_java() const {
3302 return _compiler != NULL && _compiler->is_jvmci();
3303 }
3304
3305 // Create sweeper thread
3306 CodeCacheSweeperThread::CodeCacheSweeperThread()
3307 : JavaThread(&sweeper_thread_entry) {
3308 _scanned_compiled_method = NULL;
3309 }
3310
3311 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3312 JavaThread::oops_do(f, cf);
3313 if (_scanned_compiled_method != NULL && cf != NULL) {
3314 // Safepoints can occur when the sweeper is scanning an nmethod so
3315 // process it here to make sure it isn't unloaded in the middle of
3316 // a scan.
3317 cf->do_code_blob(_scanned_compiled_method);
3318 }
3319 }
3320
3321 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3322 JavaThread::nmethods_do(cf);
3323 if (_scanned_compiled_method != NULL && cf != NULL) {
3324 // Safepoints can occur when the sweeper is scanning an nmethod so
3325 // process it here to make sure it isn't unloaded in the middle of
3326 // a scan.
3327 cf->do_code_blob(_scanned_compiled_method);
3328 }
3329 }
3330
3331
3332 // ======= Threads ========
3333
3334 // The Threads class links together all active threads, and provides
3335 // operations over all threads. It is protected by its own Mutex
3336 // lock, which is also used in other contexts to protect thread
3337 // operations from having the thread being operated on from exiting
3338 // and going away unexpectedly (e.g., safepoint synchronization)
3339
3340 JavaThread* Threads::_thread_list = NULL;
3341 int Threads::_number_of_threads = 0;
3342 int Threads::_number_of_non_daemon_threads = 0;
3343 int Threads::_return_code = 0;
3344 int Threads::_thread_claim_parity = 0;
3345 size_t JavaThread::_stack_size_at_create = 0;
3346 #ifdef ASSERT
3347 bool Threads::_vm_complete = false;
3348 #endif
3349
3350 // All JavaThreads
3351 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3352
3353 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3354 void Threads::threads_do(ThreadClosure* tc) {
3355 assert_locked_or_safepoint(Threads_lock);
3356 // ALL_JAVA_THREADS iterates through all JavaThreads
3357 ALL_JAVA_THREADS(p) {
3358 tc->do_thread(p);
3359 }
3360 // Someday we could have a table or list of all non-JavaThreads.
3361 // For now, just manually iterate through them.
3362 tc->do_thread(VMThread::vm_thread());
3363 Universe::heap()->gc_threads_do(tc);
3364 WatcherThread *wt = WatcherThread::watcher_thread();
3365 // Strictly speaking, the following NULL check isn't sufficient to make sure
3366 // the data for WatcherThread is still valid upon being examined. However,
3367 // considering that WatchThread terminates when the VM is on the way to
3368 // exit at safepoint, the chance of the above is extremely small. The right
3369 // way to prevent termination of WatcherThread would be to acquire
3370 // Terminator_lock, but we can't do that without violating the lock rank
3371 // checking in some cases.
3372 if (wt != NULL) {
3373 tc->do_thread(wt);
3374 }
3375
3376 // If CompilerThreads ever become non-JavaThreads, add them here
3377 }
3378
3379 // The system initialization in the library has three phases.
3380 //
3381 // Phase 1: java.lang.System class initialization
3382 // java.lang.System is a primordial class loaded and initialized
3383 // by the VM early during startup. java.lang.System.<clinit>
3384 // only does registerNatives and keeps the rest of the class
3385 // initialization work later until thread initialization completes.
3386 //
3387 // System.initPhase1 initializes the system properties, the static
3388 // fields in, out, and err. Set up java signal handlers, OS-specific
3389 // system settings, and thread group of the main thread.
3390 static void call_initPhase1(TRAPS) {
3391 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3392 instanceKlassHandle klass (THREAD, k);
3393
3394 JavaValue result(T_VOID);
3395 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3396 vmSymbols::void_method_signature(), CHECK);
3397 }
3398
3399 // Phase 2. Module system initialization
3400 // This will initialize the module system. Only java.base classes
3401 // can be loaded until phase 2 completes.
3402 //
3403 // Call System.initPhase2 after the compiler initialization and jsr292
3404 // classes get initialized because module initialization runs a lot of java
3405 // code, that for performance reasons, should be compiled. Also, this will
3406 // enable the startup code to use lambda and other language features in this
3407 // phase and onward.
3408 //
3409 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3410 static void call_initPhase2(TRAPS) {
3411 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime));
3412
3413 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3414 instanceKlassHandle klass (THREAD, k);
3415
3416 JavaValue result(T_VOID);
3417 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3418 vmSymbols::void_method_signature(), CHECK);
3419 universe_post_module_init();
3420 }
3421
3422 // Phase 3. final setup - set security manager, system class loader and TCCL
3423 //
3424 // This will instantiate and set the security manager, set the system class
3425 // loader as well as the thread context class loader. The security manager
3426 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3427 // other modules or the application's classpath.
3428 static void call_initPhase3(TRAPS) {
3429 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3430 instanceKlassHandle klass (THREAD, k);
3431
3432 JavaValue result(T_VOID);
3433 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3434 vmSymbols::void_method_signature(), CHECK);
3435 }
3436
3437 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3438 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3439
3440 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3441 create_vm_init_libraries();
3442 }
3443
3444 initialize_class(vmSymbols::java_lang_String(), CHECK);
3445
3446 // Inject CompactStrings value after the static initializers for String ran.
3447 java_lang_String::set_compact_strings(CompactStrings);
3448
3449 // Initialize java_lang.System (needed before creating the thread)
3450 initialize_class(vmSymbols::java_lang_System(), CHECK);
3451 // The VM creates & returns objects of this class. Make sure it's initialized.
3452 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3453 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3454 Handle thread_group = create_initial_thread_group(CHECK);
3455 Universe::set_main_thread_group(thread_group());
3456 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3457 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3458 main_thread->set_threadObj(thread_object);
3459 // Set thread status to running since main thread has
3460 // been started and running.
3461 java_lang_Thread::set_thread_status(thread_object,
3462 java_lang_Thread::RUNNABLE);
3463
3464 // The VM creates objects of this class.
3465 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3466
3467 // The VM preresolves methods to these classes. Make sure that they get initialized
3468 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3469 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3470
3471 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3472 call_initPhase1(CHECK);
3473
3474 // get the Java runtime name after java.lang.System is initialized
3475 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3476 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3477
3478 // an instance of OutOfMemory exception has been allocated earlier
3479 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3480 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3481 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3482 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3483 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3484 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3485 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3486 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3487 }
3488
3489 void Threads::initialize_jsr292_core_classes(TRAPS) {
3490 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3491
3492 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3493 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3494 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3495 }
3496
3497 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3498 extern void JDK_Version_init();
3499
3500 // Preinitialize version info.
3501 VM_Version::early_initialize();
3502
3503 // Check version
3504 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3505
3506 // Initialize library-based TLS
3507 ThreadLocalStorage::init();
3508
3509 // Initialize the output stream module
3510 ostream_init();
3511
3512 // Process java launcher properties.
3513 Arguments::process_sun_java_launcher_properties(args);
3514
3515 // Initialize the os module
3516 os::init();
3517
3518 // Record VM creation timing statistics
3519 TraceVmCreationTime create_vm_timer;
3520 create_vm_timer.start();
3521
3522 // Initialize system properties.
3523 Arguments::init_system_properties();
3524
3525 // So that JDK version can be used as a discriminator when parsing arguments
3526 JDK_Version_init();
3527
3528 // Update/Initialize System properties after JDK version number is known
3529 Arguments::init_version_specific_system_properties();
3530
3531 // Make sure to initialize log configuration *before* parsing arguments
3532 LogConfiguration::initialize(create_vm_timer.begin_time());
3533
3534 // Parse arguments
3535 jint parse_result = Arguments::parse(args);
3536 if (parse_result != JNI_OK) return parse_result;
3537
3538 os::init_before_ergo();
3539
3540 jint ergo_result = Arguments::apply_ergo();
3541 if (ergo_result != JNI_OK) return ergo_result;
3542
3543 // Final check of all ranges after ergonomics which may change values.
3544 if (!CommandLineFlagRangeList::check_ranges()) {
3545 return JNI_EINVAL;
3546 }
3547
3548 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3549 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3550 if (!constraint_result) {
3551 return JNI_EINVAL;
3552 }
3553
3554 CommandLineFlagWriteableList::mark_startup();
3555
3556 if (PauseAtStartup) {
3557 os::pause();
3558 }
3559
3560 HOTSPOT_VM_INIT_BEGIN();
3561
3562 // Timing (must come after argument parsing)
3563 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3564
3565 // Initialize the os module after parsing the args
3566 jint os_init_2_result = os::init_2();
3567 if (os_init_2_result != JNI_OK) return os_init_2_result;
3568
3569 jint adjust_after_os_result = Arguments::adjust_after_os();
3570 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3571
3572 // Initialize output stream logging
3573 ostream_init_log();
3574
3575 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3576 // Must be before create_vm_init_agents()
3577 if (Arguments::init_libraries_at_startup()) {
3578 convert_vm_init_libraries_to_agents();
3579 }
3580
3581 // Launch -agentlib/-agentpath and converted -Xrun agents
3582 if (Arguments::init_agents_at_startup()) {
3583 create_vm_init_agents();
3584 }
3585
3586 // Initialize Threads state
3587 _thread_list = NULL;
3588 _number_of_threads = 0;
3589 _number_of_non_daemon_threads = 0;
3590
3591 // Initialize global data structures and create system classes in heap
3592 vm_init_globals();
3593
3594 #if INCLUDE_JVMCI
3595 if (JVMCICounterSize > 0) {
3596 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3597 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3598 } else {
3599 JavaThread::_jvmci_old_thread_counters = NULL;
3600 }
3601 #endif // INCLUDE_JVMCI
3602
3603 // Attach the main thread to this os thread
3604 JavaThread* main_thread = new JavaThread();
3605 main_thread->set_thread_state(_thread_in_vm);
3606 main_thread->initialize_thread_current();
3607 // must do this before set_active_handles
3608 main_thread->record_stack_base_and_size();
3609 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3610
3611 if (!main_thread->set_as_starting_thread()) {
3612 vm_shutdown_during_initialization(
3613 "Failed necessary internal allocation. Out of swap space");
3614 delete main_thread;
3615 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3616 return JNI_ENOMEM;
3617 }
3618
3619 // Enable guard page *after* os::create_main_thread(), otherwise it would
3620 // crash Linux VM, see notes in os_linux.cpp.
3621 main_thread->create_stack_guard_pages();
3622
3623 // Initialize Java-Level synchronization subsystem
3624 ObjectMonitor::Initialize();
3625
3626 // Initialize global modules
3627 jint status = init_globals();
3628 if (status != JNI_OK) {
3629 delete main_thread;
3630 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3631 return status;
3632 }
3633
3634 if (TRACE_INITIALIZE() != JNI_OK) {
3635 vm_exit_during_initialization("Failed to initialize tracing backend");
3636 }
3637
3638 // Should be done after the heap is fully created
3639 main_thread->cache_global_variables();
3640
3641 HandleMark hm;
3642
3643 { MutexLocker mu(Threads_lock);
3644 Threads::add(main_thread);
3645 }
3646
3647 // Any JVMTI raw monitors entered in onload will transition into
3648 // real raw monitor. VM is setup enough here for raw monitor enter.
3649 JvmtiExport::transition_pending_onload_raw_monitors();
3650
3651 // Create the VMThread
3652 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3653
3654 VMThread::create();
3655 Thread* vmthread = VMThread::vm_thread();
3656
3657 if (!os::create_thread(vmthread, os::vm_thread)) {
3658 vm_exit_during_initialization("Cannot create VM thread. "
3659 "Out of system resources.");
3660 }
3661
3662 // Wait for the VM thread to become ready, and VMThread::run to initialize
3663 // Monitors can have spurious returns, must always check another state flag
3664 {
3665 MutexLocker ml(Notify_lock);
3666 os::start_thread(vmthread);
3667 while (vmthread->active_handles() == NULL) {
3668 Notify_lock->wait();
3669 }
3670 }
3671 }
3672
3673 assert(Universe::is_fully_initialized(), "not initialized");
3674 if (VerifyDuringStartup) {
3675 // Make sure we're starting with a clean slate.
3676 VM_Verify verify_op;
3677 VMThread::execute(&verify_op);
3678 }
3679
3680 Thread* THREAD = Thread::current();
3681
3682 // At this point, the Universe is initialized, but we have not executed
3683 // any byte code. Now is a good time (the only time) to dump out the
3684 // internal state of the JVM for sharing.
3685 if (DumpSharedSpaces) {
3686 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3687 ShouldNotReachHere();
3688 }
3689
3690 // Always call even when there are not JVMTI environments yet, since environments
3691 // may be attached late and JVMTI must track phases of VM execution
3692 JvmtiExport::enter_early_start_phase();
3693
3694 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3695 JvmtiExport::post_early_vm_start();
3696
3697 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3698
3699 // We need this for ClassDataSharing - the initial vm.info property is set
3700 // with the default value of CDS "sharing" which may be reset through
3701 // command line options.
3702 reset_vm_info_property(CHECK_JNI_ERR);
3703
3704 quicken_jni_functions();
3705
3706 // No more stub generation allowed after that point.
3707 StubCodeDesc::freeze();
3708
3709 // Set flag that basic initialization has completed. Used by exceptions and various
3710 // debug stuff, that does not work until all basic classes have been initialized.
3711 set_init_completed();
3712
3713 LogConfiguration::post_initialize();
3714 Metaspace::post_initialize();
3715
3716 HOTSPOT_VM_INIT_END();
3717
3718 // record VM initialization completion time
3719 #if INCLUDE_MANAGEMENT
3720 Management::record_vm_init_completed();
3721 #endif // INCLUDE_MANAGEMENT
3722
3723 // Signal Dispatcher needs to be started before VMInit event is posted
3724 os::signal_init();
3725
3726 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3727 if (!DisableAttachMechanism) {
3728 AttachListener::vm_start();
3729 if (StartAttachListener || AttachListener::init_at_startup()) {
3730 AttachListener::init();
3731 }
3732 }
3733
3734 // Launch -Xrun agents
3735 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3736 // back-end can launch with -Xdebug -Xrunjdwp.
3737 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3738 create_vm_init_libraries();
3739 }
3740
3741 if (CleanChunkPoolAsync) {
3742 Chunk::start_chunk_pool_cleaner_task();
3743 }
3744
3745 // initialize compiler(s)
3746 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3747 CompileBroker::compilation_init(CHECK_JNI_ERR);
3748 #endif
3749
3750 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3751 // It is done after compilers are initialized, because otherwise compilations of
3752 // signature polymorphic MH intrinsics can be missed
3753 // (see SystemDictionary::find_method_handle_intrinsic).
3754 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3755
3756 // This will initialize the module system. Only java.base classes can be
3757 // loaded until phase 2 completes
3758 call_initPhase2(CHECK_JNI_ERR);
3759
3760 // Always call even when there are not JVMTI environments yet, since environments
3761 // may be attached late and JVMTI must track phases of VM execution
3762 JvmtiExport::enter_start_phase();
3763
3764 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3765 JvmtiExport::post_vm_start();
3766
3767 // Final system initialization including security manager and system class loader
3768 call_initPhase3(CHECK_JNI_ERR);
3769
3770 // cache the system class loader
3771 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3772
3773 #if INCLUDE_JVMCI
3774 if (EnableJVMCI) {
3775 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3776 // The JVMCI Java initialization code will read this flag and
3777 // do the printing if it's set.
3778 bool init = JVMCIPrintProperties;
3779
3780 if (!init) {
3781 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3782 // compilations via JVMCI will not actually block until JVMCI is initialized.
3783 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3784 }
3785
3786 if (init) {
3787 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3788 }
3789 }
3790 #endif
3791
3792 // Always call even when there are not JVMTI environments yet, since environments
3793 // may be attached late and JVMTI must track phases of VM execution
3794 JvmtiExport::enter_live_phase();
3795
3796 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3797 JvmtiExport::post_vm_initialized();
3798
3799 if (TRACE_START() != JNI_OK) {
3800 vm_exit_during_initialization("Failed to start tracing backend.");
3801 }
3802
3803 #if INCLUDE_MANAGEMENT
3804 Management::initialize(THREAD);
3805
3806 if (HAS_PENDING_EXCEPTION) {
3807 // management agent fails to start possibly due to
3808 // configuration problem and is responsible for printing
3809 // stack trace if appropriate. Simply exit VM.
3810 vm_exit(1);
3811 }
3812 #endif // INCLUDE_MANAGEMENT
3813
3814 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3815 if (MemProfiling) MemProfiler::engage();
3816 StatSampler::engage();
3817 if (CheckJNICalls) JniPeriodicChecker::engage();
3818
3819 BiasedLocking::init();
3820
3821 #if INCLUDE_RTM_OPT
3822 RTMLockingCounters::init();
3823 #endif
3824
3825 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3826 call_postVMInitHook(THREAD);
3827 // The Java side of PostVMInitHook.run must deal with all
3828 // exceptions and provide means of diagnosis.
3829 if (HAS_PENDING_EXCEPTION) {
3830 CLEAR_PENDING_EXCEPTION;
3831 }
3832 }
3833
3834 {
3835 MutexLocker ml(PeriodicTask_lock);
3836 // Make sure the WatcherThread can be started by WatcherThread::start()
3837 // or by dynamic enrollment.
3838 WatcherThread::make_startable();
3839 // Start up the WatcherThread if there are any periodic tasks
3840 // NOTE: All PeriodicTasks should be registered by now. If they
3841 // aren't, late joiners might appear to start slowly (we might
3842 // take a while to process their first tick).
3843 if (PeriodicTask::num_tasks() > 0) {
3844 WatcherThread::start();
3845 }
3846 }
3847
3848 create_vm_timer.end();
3849 #ifdef ASSERT
3850 _vm_complete = true;
3851 #endif
3852 return JNI_OK;
3853 }
3854
3855 // type for the Agent_OnLoad and JVM_OnLoad entry points
3856 extern "C" {
3857 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3858 }
3859 // Find a command line agent library and return its entry point for
3860 // -agentlib: -agentpath: -Xrun
3861 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3862 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3863 const char *on_load_symbols[],
3864 size_t num_symbol_entries) {
3865 OnLoadEntry_t on_load_entry = NULL;
3866 void *library = NULL;
3867
3868 if (!agent->valid()) {
3869 char buffer[JVM_MAXPATHLEN];
3870 char ebuf[1024] = "";
3871 const char *name = agent->name();
3872 const char *msg = "Could not find agent library ";
3873
3874 // First check to see if agent is statically linked into executable
3875 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3876 library = agent->os_lib();
3877 } else if (agent->is_absolute_path()) {
3878 library = os::dll_load(name, ebuf, sizeof ebuf);
3879 if (library == NULL) {
3880 const char *sub_msg = " in absolute path, with error: ";
3881 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3882 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3883 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3884 // If we can't find the agent, exit.
3885 vm_exit_during_initialization(buf, NULL);
3886 FREE_C_HEAP_ARRAY(char, buf);
3887 }
3888 } else {
3889 // Try to load the agent from the standard dll directory
3890 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3891 name)) {
3892 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3893 }
3894 if (library == NULL) { // Try the local directory
3895 char ns[1] = {0};
3896 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3897 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3898 }
3899 if (library == NULL) {
3900 const char *sub_msg = " on the library path, with error: ";
3901 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3902 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3903 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3904 // If we can't find the agent, exit.
3905 vm_exit_during_initialization(buf, NULL);
3906 FREE_C_HEAP_ARRAY(char, buf);
3907 }
3908 }
3909 }
3910 agent->set_os_lib(library);
3911 agent->set_valid();
3912 }
3913
3914 // Find the OnLoad function.
3915 on_load_entry =
3916 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3917 false,
3918 on_load_symbols,
3919 num_symbol_entries));
3920 return on_load_entry;
3921 }
3922
3923 // Find the JVM_OnLoad entry point
3924 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3925 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3926 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3927 }
3928
3929 // Find the Agent_OnLoad entry point
3930 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3931 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3932 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3933 }
3934
3935 // For backwards compatibility with -Xrun
3936 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3937 // treated like -agentpath:
3938 // Must be called before agent libraries are created
3939 void Threads::convert_vm_init_libraries_to_agents() {
3940 AgentLibrary* agent;
3941 AgentLibrary* next;
3942
3943 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3944 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3945 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3946
3947 // If there is an JVM_OnLoad function it will get called later,
3948 // otherwise see if there is an Agent_OnLoad
3949 if (on_load_entry == NULL) {
3950 on_load_entry = lookup_agent_on_load(agent);
3951 if (on_load_entry != NULL) {
3952 // switch it to the agent list -- so that Agent_OnLoad will be called,
3953 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3954 Arguments::convert_library_to_agent(agent);
3955 } else {
3956 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3957 }
3958 }
3959 }
3960 }
3961
3962 // Create agents for -agentlib: -agentpath: and converted -Xrun
3963 // Invokes Agent_OnLoad
3964 // Called very early -- before JavaThreads exist
3965 void Threads::create_vm_init_agents() {
3966 extern struct JavaVM_ main_vm;
3967 AgentLibrary* agent;
3968
3969 JvmtiExport::enter_onload_phase();
3970
3971 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3972 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3973
3974 if (on_load_entry != NULL) {
3975 // Invoke the Agent_OnLoad function
3976 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3977 if (err != JNI_OK) {
3978 vm_exit_during_initialization("agent library failed to init", agent->name());
3979 }
3980 } else {
3981 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3982 }
3983 }
3984 JvmtiExport::enter_primordial_phase();
3985 }
3986
3987 extern "C" {
3988 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3989 }
3990
3991 void Threads::shutdown_vm_agents() {
3992 // Send any Agent_OnUnload notifications
3993 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3994 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3995 extern struct JavaVM_ main_vm;
3996 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3997
3998 // Find the Agent_OnUnload function.
3999 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4000 os::find_agent_function(agent,
4001 false,
4002 on_unload_symbols,
4003 num_symbol_entries));
4004
4005 // Invoke the Agent_OnUnload function
4006 if (unload_entry != NULL) {
4007 JavaThread* thread = JavaThread::current();
4008 ThreadToNativeFromVM ttn(thread);
4009 HandleMark hm(thread);
4010 (*unload_entry)(&main_vm);
4011 }
4012 }
4013 }
4014
4015 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4016 // Invokes JVM_OnLoad
4017 void Threads::create_vm_init_libraries() {
4018 extern struct JavaVM_ main_vm;
4019 AgentLibrary* agent;
4020
4021 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4022 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4023
4024 if (on_load_entry != NULL) {
4025 // Invoke the JVM_OnLoad function
4026 JavaThread* thread = JavaThread::current();
4027 ThreadToNativeFromVM ttn(thread);
4028 HandleMark hm(thread);
4029 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4030 if (err != JNI_OK) {
4031 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4032 }
4033 } else {
4034 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4035 }
4036 }
4037 }
4038
4039 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4040 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4041
4042 JavaThread* java_thread = NULL;
4043 // Sequential search for now. Need to do better optimization later.
4044 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4045 oop tobj = thread->threadObj();
4046 if (!thread->is_exiting() &&
4047 tobj != NULL &&
4048 java_tid == java_lang_Thread::thread_id(tobj)) {
4049 java_thread = thread;
4050 break;
4051 }
4052 }
4053 return java_thread;
4054 }
4055
4056
4057 // Last thread running calls java.lang.Shutdown.shutdown()
4058 void JavaThread::invoke_shutdown_hooks() {
4059 HandleMark hm(this);
4060
4061 // We could get here with a pending exception, if so clear it now.
4062 if (this->has_pending_exception()) {
4063 this->clear_pending_exception();
4064 }
4065
4066 EXCEPTION_MARK;
4067 Klass* k =
4068 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4069 THREAD);
4070 if (k != NULL) {
4071 // SystemDictionary::resolve_or_null will return null if there was
4072 // an exception. If we cannot load the Shutdown class, just don't
4073 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4074 // and finalizers (if runFinalizersOnExit is set) won't be run.
4075 // Note that if a shutdown hook was registered or runFinalizersOnExit
4076 // was called, the Shutdown class would have already been loaded
4077 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4078 instanceKlassHandle shutdown_klass (THREAD, k);
4079 JavaValue result(T_VOID);
4080 JavaCalls::call_static(&result,
4081 shutdown_klass,
4082 vmSymbols::shutdown_method_name(),
4083 vmSymbols::void_method_signature(),
4084 THREAD);
4085 }
4086 CLEAR_PENDING_EXCEPTION;
4087 }
4088
4089 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4090 // the program falls off the end of main(). Another VM exit path is through
4091 // vm_exit() when the program calls System.exit() to return a value or when
4092 // there is a serious error in VM. The two shutdown paths are not exactly
4093 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4094 // and VM_Exit op at VM level.
4095 //
4096 // Shutdown sequence:
4097 // + Shutdown native memory tracking if it is on
4098 // + Wait until we are the last non-daemon thread to execute
4099 // <-- every thing is still working at this moment -->
4100 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4101 // shutdown hooks, run finalizers if finalization-on-exit
4102 // + Call before_exit(), prepare for VM exit
4103 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4104 // currently the only user of this mechanism is File.deleteOnExit())
4105 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4106 // post thread end and vm death events to JVMTI,
4107 // stop signal thread
4108 // + Call JavaThread::exit(), it will:
4109 // > release JNI handle blocks, remove stack guard pages
4110 // > remove this thread from Threads list
4111 // <-- no more Java code from this thread after this point -->
4112 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4113 // the compiler threads at safepoint
4114 // <-- do not use anything that could get blocked by Safepoint -->
4115 // + Disable tracing at JNI/JVM barriers
4116 // + Set _vm_exited flag for threads that are still running native code
4117 // + Delete this thread
4118 // + Call exit_globals()
4119 // > deletes tty
4120 // > deletes PerfMemory resources
4121 // + Return to caller
4122
4123 bool Threads::destroy_vm() {
4124 JavaThread* thread = JavaThread::current();
4125
4126 #ifdef ASSERT
4127 _vm_complete = false;
4128 #endif
4129 // Wait until we are the last non-daemon thread to execute
4130 { MutexLocker nu(Threads_lock);
4131 while (Threads::number_of_non_daemon_threads() > 1)
4132 // This wait should make safepoint checks, wait without a timeout,
4133 // and wait as a suspend-equivalent condition.
4134 //
4135 // Note: If the FlatProfiler is running and this thread is waiting
4136 // for another non-daemon thread to finish, then the FlatProfiler
4137 // is waiting for the external suspend request on this thread to
4138 // complete. wait_for_ext_suspend_completion() will eventually
4139 // timeout, but that takes time. Making this wait a suspend-
4140 // equivalent condition solves that timeout problem.
4141 //
4142 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4143 Mutex::_as_suspend_equivalent_flag);
4144 }
4145
4146 // Hang forever on exit if we are reporting an error.
4147 if (ShowMessageBoxOnError && is_error_reported()) {
4148 os::infinite_sleep();
4149 }
4150 os::wait_for_keypress_at_exit();
4151
4152 // run Java level shutdown hooks
4153 thread->invoke_shutdown_hooks();
4154
4155 before_exit(thread);
4156
4157 thread->exit(true);
4158
4159 // Stop VM thread.
4160 {
4161 // 4945125 The vm thread comes to a safepoint during exit.
4162 // GC vm_operations can get caught at the safepoint, and the
4163 // heap is unparseable if they are caught. Grab the Heap_lock
4164 // to prevent this. The GC vm_operations will not be able to
4165 // queue until after the vm thread is dead. After this point,
4166 // we'll never emerge out of the safepoint before the VM exits.
4167
4168 MutexLocker ml(Heap_lock);
4169
4170 VMThread::wait_for_vm_thread_exit();
4171 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4172 VMThread::destroy();
4173 }
4174
4175 // clean up ideal graph printers
4176 #if defined(COMPILER2) && !defined(PRODUCT)
4177 IdealGraphPrinter::clean_up();
4178 #endif
4179
4180 // Now, all Java threads are gone except daemon threads. Daemon threads
4181 // running Java code or in VM are stopped by the Safepoint. However,
4182 // daemon threads executing native code are still running. But they
4183 // will be stopped at native=>Java/VM barriers. Note that we can't
4184 // simply kill or suspend them, as it is inherently deadlock-prone.
4185
4186 VM_Exit::set_vm_exited();
4187
4188 notify_vm_shutdown();
4189
4190 delete thread;
4191
4192 #if INCLUDE_JVMCI
4193 if (JVMCICounterSize > 0) {
4194 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4195 }
4196 #endif
4197
4198 // exit_globals() will delete tty
4199 exit_globals();
4200
4201 LogConfiguration::finalize();
4202
4203 return true;
4204 }
4205
4206
4207 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4208 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4209 return is_supported_jni_version(version);
4210 }
4211
4212
4213 jboolean Threads::is_supported_jni_version(jint version) {
4214 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4215 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4216 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4217 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4218 if (version == JNI_VERSION_9) return JNI_TRUE;
4219 return JNI_FALSE;
4220 }
4221
4222
4223 void Threads::add(JavaThread* p, bool force_daemon) {
4224 // The threads lock must be owned at this point
4225 assert_locked_or_safepoint(Threads_lock);
4226
4227 // See the comment for this method in thread.hpp for its purpose and
4228 // why it is called here.
4229 p->initialize_queues();
4230 p->set_next(_thread_list);
4231 _thread_list = p;
4232 _number_of_threads++;
4233 oop threadObj = p->threadObj();
4234 bool daemon = true;
4235 // Bootstrapping problem: threadObj can be null for initial
4236 // JavaThread (or for threads attached via JNI)
4237 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4238 _number_of_non_daemon_threads++;
4239 daemon = false;
4240 }
4241
4242 ThreadService::add_thread(p, daemon);
4243
4244 // Possible GC point.
4245 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4246 }
4247
4248 void Threads::remove(JavaThread* p) {
4249 // Extra scope needed for Thread_lock, so we can check
4250 // that we do not remove thread without safepoint code notice
4251 { MutexLocker ml(Threads_lock);
4252
4253 assert(includes(p), "p must be present");
4254
4255 JavaThread* current = _thread_list;
4256 JavaThread* prev = NULL;
4257
4258 while (current != p) {
4259 prev = current;
4260 current = current->next();
4261 }
4262
4263 if (prev) {
4264 prev->set_next(current->next());
4265 } else {
4266 _thread_list = p->next();
4267 }
4268 _number_of_threads--;
4269 oop threadObj = p->threadObj();
4270 bool daemon = true;
4271 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4272 _number_of_non_daemon_threads--;
4273 daemon = false;
4274
4275 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4276 // on destroy_vm will wake up.
4277 if (number_of_non_daemon_threads() == 1) {
4278 Threads_lock->notify_all();
4279 }
4280 }
4281 ThreadService::remove_thread(p, daemon);
4282
4283 // Make sure that safepoint code disregard this thread. This is needed since
4284 // the thread might mess around with locks after this point. This can cause it
4285 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4286 // of this thread since it is removed from the queue.
4287 p->set_terminated_value();
4288 } // unlock Threads_lock
4289
4290 // Since Events::log uses a lock, we grab it outside the Threads_lock
4291 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4292 }
4293
4294 // Threads_lock must be held when this is called (or must be called during a safepoint)
4295 bool Threads::includes(JavaThread* p) {
4296 assert(Threads_lock->is_locked(), "sanity check");
4297 ALL_JAVA_THREADS(q) {
4298 if (q == p) {
4299 return true;
4300 }
4301 }
4302 return false;
4303 }
4304
4305 // Operations on the Threads list for GC. These are not explicitly locked,
4306 // but the garbage collector must provide a safe context for them to run.
4307 // In particular, these things should never be called when the Threads_lock
4308 // is held by some other thread. (Note: the Safepoint abstraction also
4309 // uses the Threads_lock to guarantee this property. It also makes sure that
4310 // all threads gets blocked when exiting or starting).
4311
4312 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4313 ALL_JAVA_THREADS(p) {
4314 p->oops_do(f, cf);
4315 }
4316 VMThread::vm_thread()->oops_do(f, cf);
4317 }
4318
4319 void Threads::change_thread_claim_parity() {
4320 // Set the new claim parity.
4321 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4322 "Not in range.");
4323 _thread_claim_parity++;
4324 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4325 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4326 "Not in range.");
4327 }
4328
4329 #ifdef ASSERT
4330 void Threads::assert_all_threads_claimed() {
4331 ALL_JAVA_THREADS(p) {
4332 const int thread_parity = p->oops_do_parity();
4333 assert((thread_parity == _thread_claim_parity),
4334 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4335 }
4336 }
4337 #endif // ASSERT
4338
4339 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4340 int cp = Threads::thread_claim_parity();
4341 ALL_JAVA_THREADS(p) {
4342 if (p->claim_oops_do(is_par, cp)) {
4343 p->oops_do(f, cf);
4344 }
4345 }
4346 VMThread* vmt = VMThread::vm_thread();
4347 if (vmt->claim_oops_do(is_par, cp)) {
4348 vmt->oops_do(f, cf);
4349 }
4350 }
4351
4352 #if INCLUDE_ALL_GCS
4353 // Used by ParallelScavenge
4354 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4355 ALL_JAVA_THREADS(p) {
4356 q->enqueue(new ThreadRootsTask(p));
4357 }
4358 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4359 }
4360
4361 // Used by Parallel Old
4362 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4363 ALL_JAVA_THREADS(p) {
4364 q->enqueue(new ThreadRootsMarkingTask(p));
4365 }
4366 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4367 }
4368 #endif // INCLUDE_ALL_GCS
4369
4370 void Threads::nmethods_do(CodeBlobClosure* cf) {
4371 ALL_JAVA_THREADS(p) {
4372 // This is used by the code cache sweeper to mark nmethods that are active
4373 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4374 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4375 if(!p->is_Code_cache_sweeper_thread()) {
4376 p->nmethods_do(cf);
4377 }
4378 }
4379 }
4380
4381 void Threads::metadata_do(void f(Metadata*)) {
4382 ALL_JAVA_THREADS(p) {
4383 p->metadata_do(f);
4384 }
4385 }
4386
4387 class ThreadHandlesClosure : public ThreadClosure {
4388 void (*_f)(Metadata*);
4389 public:
4390 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4391 virtual void do_thread(Thread* thread) {
4392 thread->metadata_handles_do(_f);
4393 }
4394 };
4395
4396 void Threads::metadata_handles_do(void f(Metadata*)) {
4397 // Only walk the Handles in Thread.
4398 ThreadHandlesClosure handles_closure(f);
4399 threads_do(&handles_closure);
4400 }
4401
4402 void Threads::deoptimized_wrt_marked_nmethods() {
4403 ALL_JAVA_THREADS(p) {
4404 p->deoptimized_wrt_marked_nmethods();
4405 }
4406 }
4407
4408
4409 // Get count Java threads that are waiting to enter the specified monitor.
4410 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4411 address monitor,
4412 bool doLock) {
4413 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4414 "must grab Threads_lock or be at safepoint");
4415 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4416
4417 int i = 0;
4418 {
4419 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4420 ALL_JAVA_THREADS(p) {
4421 if (!p->can_call_java()) continue;
4422
4423 address pending = (address)p->current_pending_monitor();
4424 if (pending == monitor) { // found a match
4425 if (i < count) result->append(p); // save the first count matches
4426 i++;
4427 }
4428 }
4429 }
4430 return result;
4431 }
4432
4433
4434 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4435 bool doLock) {
4436 assert(doLock ||
4437 Threads_lock->owned_by_self() ||
4438 SafepointSynchronize::is_at_safepoint(),
4439 "must grab Threads_lock or be at safepoint");
4440
4441 // NULL owner means not locked so we can skip the search
4442 if (owner == NULL) return NULL;
4443
4444 {
4445 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4446 ALL_JAVA_THREADS(p) {
4447 // first, see if owner is the address of a Java thread
4448 if (owner == (address)p) return p;
4449 }
4450 }
4451 // Cannot assert on lack of success here since this function may be
4452 // used by code that is trying to report useful problem information
4453 // like deadlock detection.
4454 if (UseHeavyMonitors) return NULL;
4455
4456 // If we didn't find a matching Java thread and we didn't force use of
4457 // heavyweight monitors, then the owner is the stack address of the
4458 // Lock Word in the owning Java thread's stack.
4459 //
4460 JavaThread* the_owner = NULL;
4461 {
4462 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4463 ALL_JAVA_THREADS(q) {
4464 if (q->is_lock_owned(owner)) {
4465 the_owner = q;
4466 break;
4467 }
4468 }
4469 }
4470 // cannot assert on lack of success here; see above comment
4471 return the_owner;
4472 }
4473
4474 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4475 void Threads::print_on(outputStream* st, bool print_stacks,
4476 bool internal_format, bool print_concurrent_locks) {
4477 char buf[32];
4478 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4479
4480 st->print_cr("Full thread dump %s (%s %s):",
4481 Abstract_VM_Version::vm_name(),
4482 Abstract_VM_Version::vm_release(),
4483 Abstract_VM_Version::vm_info_string());
4484 st->cr();
4485
4486 #if INCLUDE_SERVICES
4487 // Dump concurrent locks
4488 ConcurrentLocksDump concurrent_locks;
4489 if (print_concurrent_locks) {
4490 concurrent_locks.dump_at_safepoint();
4491 }
4492 #endif // INCLUDE_SERVICES
4493
4494 ALL_JAVA_THREADS(p) {
4495 ResourceMark rm;
4496 p->print_on(st);
4497 if (print_stacks) {
4498 if (internal_format) {
4499 p->trace_stack();
4500 } else {
4501 p->print_stack_on(st);
4502 }
4503 }
4504 st->cr();
4505 #if INCLUDE_SERVICES
4506 if (print_concurrent_locks) {
4507 concurrent_locks.print_locks_on(p, st);
4508 }
4509 #endif // INCLUDE_SERVICES
4510 }
4511
4512 VMThread::vm_thread()->print_on(st);
4513 st->cr();
4514 Universe::heap()->print_gc_threads_on(st);
4515 WatcherThread* wt = WatcherThread::watcher_thread();
4516 if (wt != NULL) {
4517 wt->print_on(st);
4518 st->cr();
4519 }
4520 st->flush();
4521 }
4522
4523 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4524 int buflen, bool* found_current) {
4525 if (this_thread != NULL) {
4526 bool is_current = (current == this_thread);
4527 *found_current = *found_current || is_current;
4528 st->print("%s", is_current ? "=>" : " ");
4529
4530 st->print(PTR_FORMAT, p2i(this_thread));
4531 st->print(" ");
4532 this_thread->print_on_error(st, buf, buflen);
4533 st->cr();
4534 }
4535 }
4536
4537 class PrintOnErrorClosure : public ThreadClosure {
4538 outputStream* _st;
4539 Thread* _current;
4540 char* _buf;
4541 int _buflen;
4542 bool* _found_current;
4543 public:
4544 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4545 int buflen, bool* found_current) :
4546 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4547
4548 virtual void do_thread(Thread* thread) {
4549 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4550 }
4551 };
4552
4553 // Threads::print_on_error() is called by fatal error handler. It's possible
4554 // that VM is not at safepoint and/or current thread is inside signal handler.
4555 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4556 // memory (even in resource area), it might deadlock the error handler.
4557 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4558 int buflen) {
4559 bool found_current = false;
4560 st->print_cr("Java Threads: ( => current thread )");
4561 ALL_JAVA_THREADS(thread) {
4562 print_on_error(thread, st, current, buf, buflen, &found_current);
4563 }
4564 st->cr();
4565
4566 st->print_cr("Other Threads:");
4567 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4568 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4569
4570 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4571 Universe::heap()->gc_threads_do(&print_closure);
4572
4573 if (!found_current) {
4574 st->cr();
4575 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4576 current->print_on_error(st, buf, buflen);
4577 st->cr();
4578 }
4579 st->cr();
4580 st->print_cr("Threads with active compile tasks:");
4581 print_threads_compiling(st, buf, buflen);
4582 }
4583
4584 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4585 ALL_JAVA_THREADS(thread) {
4586 if (thread->is_Compiler_thread()) {
4587 CompilerThread* ct = (CompilerThread*) thread;
4588 if (ct->task() != NULL) {
4589 thread->print_name_on_error(st, buf, buflen);
4590 ct->task()->print(st, NULL, true, true);
4591 }
4592 }
4593 }
4594 }
4595
4596
4597 // Internal SpinLock and Mutex
4598 // Based on ParkEvent
4599
4600 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4601 //
4602 // We employ SpinLocks _only for low-contention, fixed-length
4603 // short-duration critical sections where we're concerned
4604 // about native mutex_t or HotSpot Mutex:: latency.
4605 // The mux construct provides a spin-then-block mutual exclusion
4606 // mechanism.
4607 //
4608 // Testing has shown that contention on the ListLock guarding gFreeList
4609 // is common. If we implement ListLock as a simple SpinLock it's common
4610 // for the JVM to devolve to yielding with little progress. This is true
4611 // despite the fact that the critical sections protected by ListLock are
4612 // extremely short.
4613 //
4614 // TODO-FIXME: ListLock should be of type SpinLock.
4615 // We should make this a 1st-class type, integrated into the lock
4616 // hierarchy as leaf-locks. Critically, the SpinLock structure
4617 // should have sufficient padding to avoid false-sharing and excessive
4618 // cache-coherency traffic.
4619
4620
4621 typedef volatile int SpinLockT;
4622
4623 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4624 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4625 return; // normal fast-path return
4626 }
4627
4628 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4629 TEVENT(SpinAcquire - ctx);
4630 int ctr = 0;
4631 int Yields = 0;
4632 for (;;) {
4633 while (*adr != 0) {
4634 ++ctr;
4635 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4636 if (Yields > 5) {
4637 os::naked_short_sleep(1);
4638 } else {
4639 os::naked_yield();
4640 ++Yields;
4641 }
4642 } else {
4643 SpinPause();
4644 }
4645 }
4646 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4647 }
4648 }
4649
4650 void Thread::SpinRelease(volatile int * adr) {
4651 assert(*adr != 0, "invariant");
4652 OrderAccess::fence(); // guarantee at least release consistency.
4653 // Roach-motel semantics.
4654 // It's safe if subsequent LDs and STs float "up" into the critical section,
4655 // but prior LDs and STs within the critical section can't be allowed
4656 // to reorder or float past the ST that releases the lock.
4657 // Loads and stores in the critical section - which appear in program
4658 // order before the store that releases the lock - must also appear
4659 // before the store that releases the lock in memory visibility order.
4660 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4661 // the ST of 0 into the lock-word which releases the lock, so fence
4662 // more than covers this on all platforms.
4663 *adr = 0;
4664 }
4665
4666 // muxAcquire and muxRelease:
4667 //
4668 // * muxAcquire and muxRelease support a single-word lock-word construct.
4669 // The LSB of the word is set IFF the lock is held.
4670 // The remainder of the word points to the head of a singly-linked list
4671 // of threads blocked on the lock.
4672 //
4673 // * The current implementation of muxAcquire-muxRelease uses its own
4674 // dedicated Thread._MuxEvent instance. If we're interested in
4675 // minimizing the peak number of extant ParkEvent instances then
4676 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4677 // as certain invariants were satisfied. Specifically, care would need
4678 // to be taken with regards to consuming unpark() "permits".
4679 // A safe rule of thumb is that a thread would never call muxAcquire()
4680 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4681 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4682 // consume an unpark() permit intended for monitorenter, for instance.
4683 // One way around this would be to widen the restricted-range semaphore
4684 // implemented in park(). Another alternative would be to provide
4685 // multiple instances of the PlatformEvent() for each thread. One
4686 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4687 //
4688 // * Usage:
4689 // -- Only as leaf locks
4690 // -- for short-term locking only as muxAcquire does not perform
4691 // thread state transitions.
4692 //
4693 // Alternatives:
4694 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4695 // but with parking or spin-then-park instead of pure spinning.
4696 // * Use Taura-Oyama-Yonenzawa locks.
4697 // * It's possible to construct a 1-0 lock if we encode the lockword as
4698 // (List,LockByte). Acquire will CAS the full lockword while Release
4699 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4700 // acquiring threads use timers (ParkTimed) to detect and recover from
4701 // the stranding window. Thread/Node structures must be aligned on 256-byte
4702 // boundaries by using placement-new.
4703 // * Augment MCS with advisory back-link fields maintained with CAS().
4704 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4705 // The validity of the backlinks must be ratified before we trust the value.
4706 // If the backlinks are invalid the exiting thread must back-track through the
4707 // the forward links, which are always trustworthy.
4708 // * Add a successor indication. The LockWord is currently encoded as
4709 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4710 // to provide the usual futile-wakeup optimization.
4711 // See RTStt for details.
4712 // * Consider schedctl.sc_nopreempt to cover the critical section.
4713 //
4714
4715
4716 typedef volatile intptr_t MutexT; // Mux Lock-word
4717 enum MuxBits { LOCKBIT = 1 };
4718
4719 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4720 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4721 if (w == 0) return;
4722 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4723 return;
4724 }
4725
4726 TEVENT(muxAcquire - Contention);
4727 ParkEvent * const Self = Thread::current()->_MuxEvent;
4728 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4729 for (;;) {
4730 int its = (os::is_MP() ? 100 : 0) + 1;
4731
4732 // Optional spin phase: spin-then-park strategy
4733 while (--its >= 0) {
4734 w = *Lock;
4735 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4736 return;
4737 }
4738 }
4739
4740 Self->reset();
4741 Self->OnList = intptr_t(Lock);
4742 // The following fence() isn't _strictly necessary as the subsequent
4743 // CAS() both serializes execution and ratifies the fetched *Lock value.
4744 OrderAccess::fence();
4745 for (;;) {
4746 w = *Lock;
4747 if ((w & LOCKBIT) == 0) {
4748 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4749 Self->OnList = 0; // hygiene - allows stronger asserts
4750 return;
4751 }
4752 continue; // Interference -- *Lock changed -- Just retry
4753 }
4754 assert(w & LOCKBIT, "invariant");
4755 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4756 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4757 }
4758
4759 while (Self->OnList != 0) {
4760 Self->park();
4761 }
4762 }
4763 }
4764
4765 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4766 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4767 if (w == 0) return;
4768 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4769 return;
4770 }
4771
4772 TEVENT(muxAcquire - Contention);
4773 ParkEvent * ReleaseAfter = NULL;
4774 if (ev == NULL) {
4775 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4776 }
4777 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4778 for (;;) {
4779 guarantee(ev->OnList == 0, "invariant");
4780 int its = (os::is_MP() ? 100 : 0) + 1;
4781
4782 // Optional spin phase: spin-then-park strategy
4783 while (--its >= 0) {
4784 w = *Lock;
4785 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4786 if (ReleaseAfter != NULL) {
4787 ParkEvent::Release(ReleaseAfter);
4788 }
4789 return;
4790 }
4791 }
4792
4793 ev->reset();
4794 ev->OnList = intptr_t(Lock);
4795 // The following fence() isn't _strictly necessary as the subsequent
4796 // CAS() both serializes execution and ratifies the fetched *Lock value.
4797 OrderAccess::fence();
4798 for (;;) {
4799 w = *Lock;
4800 if ((w & LOCKBIT) == 0) {
4801 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4802 ev->OnList = 0;
4803 // We call ::Release while holding the outer lock, thus
4804 // artificially lengthening the critical section.
4805 // Consider deferring the ::Release() until the subsequent unlock(),
4806 // after we've dropped the outer lock.
4807 if (ReleaseAfter != NULL) {
4808 ParkEvent::Release(ReleaseAfter);
4809 }
4810 return;
4811 }
4812 continue; // Interference -- *Lock changed -- Just retry
4813 }
4814 assert(w & LOCKBIT, "invariant");
4815 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4816 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4817 }
4818
4819 while (ev->OnList != 0) {
4820 ev->park();
4821 }
4822 }
4823 }
4824
4825 // Release() must extract a successor from the list and then wake that thread.
4826 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4827 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4828 // Release() would :
4829 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4830 // (B) Extract a successor from the private list "in-hand"
4831 // (C) attempt to CAS() the residual back into *Lock over null.
4832 // If there were any newly arrived threads and the CAS() would fail.
4833 // In that case Release() would detach the RATs, re-merge the list in-hand
4834 // with the RATs and repeat as needed. Alternately, Release() might
4835 // detach and extract a successor, but then pass the residual list to the wakee.
4836 // The wakee would be responsible for reattaching and remerging before it
4837 // competed for the lock.
4838 //
4839 // Both "pop" and DMR are immune from ABA corruption -- there can be
4840 // multiple concurrent pushers, but only one popper or detacher.
4841 // This implementation pops from the head of the list. This is unfair,
4842 // but tends to provide excellent throughput as hot threads remain hot.
4843 // (We wake recently run threads first).
4844 //
4845 // All paths through muxRelease() will execute a CAS.
4846 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4847 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4848 // executed within the critical section are complete and globally visible before the
4849 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4850 void Thread::muxRelease(volatile intptr_t * Lock) {
4851 for (;;) {
4852 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4853 assert(w & LOCKBIT, "invariant");
4854 if (w == LOCKBIT) return;
4855 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4856 assert(List != NULL, "invariant");
4857 assert(List->OnList == intptr_t(Lock), "invariant");
4858 ParkEvent * const nxt = List->ListNext;
4859 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4860
4861 // The following CAS() releases the lock and pops the head element.
4862 // The CAS() also ratifies the previously fetched lock-word value.
4863 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4864 continue;
4865 }
4866 List->OnList = 0;
4867 OrderAccess::fence();
4868 List->unpark();
4869 return;
4870 }
4871 }
4872
4873
4874 void Threads::verify() {
4875 ALL_JAVA_THREADS(p) {
4876 p->verify();
4877 }
4878 VMThread* thread = VMThread::vm_thread();
4879 if (thread != NULL) thread->verify();
4880 }