1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "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 if (MonitorInUseLists) {
797 ObjectSynchronizer::thread_local_used_oops_do(this, f);
798 }
799 }
800
801 void Thread::metadata_handles_do(void f(Metadata*)) {
802 // Only walk the Handles in Thread.
803 if (metadata_handles() != NULL) {
804 for (int i = 0; i< metadata_handles()->length(); i++) {
805 f(metadata_handles()->at(i));
806 }
807 }
808 }
809
810 void Thread::print_on(outputStream* st) const {
811 // get_priority assumes osthread initialized
812 if (osthread() != NULL) {
813 int os_prio;
814 if (os::get_native_priority(this, &os_prio) == OS_OK) {
815 st->print("os_prio=%d ", os_prio);
816 }
817 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
818 ext().print_on(st);
819 osthread()->print_on(st);
820 }
821 debug_only(if (WizardMode) print_owned_locks_on(st);)
822 }
823
824 // Thread::print_on_error() is called by fatal error handler. Don't use
825 // any lock or allocate memory.
826 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
827 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
828
829 if (is_VM_thread()) { st->print("VMThread"); }
830 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
831 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
832 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
833 else { st->print("Thread"); }
834
835 if (is_Named_thread()) {
836 st->print(" \"%s\"", name());
837 }
838
839 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
840 p2i(stack_end()), p2i(stack_base()));
841
842 if (osthread()) {
843 st->print(" [id=%d]", osthread()->thread_id());
844 }
845 }
846
847 #ifdef ASSERT
848 void Thread::print_owned_locks_on(outputStream* st) const {
849 Monitor *cur = _owned_locks;
850 if (cur == NULL) {
851 st->print(" (no locks) ");
852 } else {
853 st->print_cr(" Locks owned:");
854 while (cur) {
855 cur->print_on(st);
856 cur = cur->next();
857 }
858 }
859 }
860
861 static int ref_use_count = 0;
862
863 bool Thread::owns_locks_but_compiled_lock() const {
864 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
865 if (cur != Compile_lock) return true;
866 }
867 return false;
868 }
869
870
871 #endif
872
873 #ifndef PRODUCT
874
875 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
876 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
877 // no threads which allow_vm_block's are held
878 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
879 // Check if current thread is allowed to block at a safepoint
880 if (!(_allow_safepoint_count == 0)) {
881 fatal("Possible safepoint reached by thread that does not allow it");
882 }
883 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
884 fatal("LEAF method calling lock?");
885 }
886
887 #ifdef ASSERT
888 if (potential_vm_operation && is_Java_thread()
889 && !Universe::is_bootstrapping()) {
890 // Make sure we do not hold any locks that the VM thread also uses.
891 // This could potentially lead to deadlocks
892 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
893 // Threads_lock is special, since the safepoint synchronization will not start before this is
894 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
895 // since it is used to transfer control between JavaThreads and the VMThread
896 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
897 if ((cur->allow_vm_block() &&
898 cur != Threads_lock &&
899 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
900 cur != VMOperationRequest_lock &&
901 cur != VMOperationQueue_lock) ||
902 cur->rank() == Mutex::special) {
903 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
904 }
905 }
906 }
907
908 if (GCALotAtAllSafepoints) {
909 // We could enter a safepoint here and thus have a gc
910 InterfaceSupport::check_gc_alot();
911 }
912 #endif
913 }
914 #endif
915
916 bool Thread::is_in_stack(address adr) const {
917 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
918 address end = os::current_stack_pointer();
919 // Allow non Java threads to call this without stack_base
920 if (_stack_base == NULL) return true;
921 if (stack_base() >= adr && adr >= end) return true;
922
923 return false;
924 }
925
926 bool Thread::is_in_usable_stack(address adr) const {
927 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
928 size_t usable_stack_size = _stack_size - stack_guard_size;
929
930 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
931 }
932
933
934 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
935 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
936 // used for compilation in the future. If that change is made, the need for these methods
937 // should be revisited, and they should be removed if possible.
938
939 bool Thread::is_lock_owned(address adr) const {
940 return on_local_stack(adr);
941 }
942
943 bool Thread::set_as_starting_thread() {
944 // NOTE: this must be called inside the main thread.
945 return os::create_main_thread((JavaThread*)this);
946 }
947
948 static void initialize_class(Symbol* class_name, TRAPS) {
949 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
950 InstanceKlass::cast(klass)->initialize(CHECK);
951 }
952
953
954 // Creates the initial ThreadGroup
955 static Handle create_initial_thread_group(TRAPS) {
956 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
957 InstanceKlass* ik = InstanceKlass::cast(k);
958
959 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
960 {
961 JavaValue result(T_VOID);
962 JavaCalls::call_special(&result,
963 system_instance,
964 ik,
965 vmSymbols::object_initializer_name(),
966 vmSymbols::void_method_signature(),
967 CHECK_NH);
968 }
969 Universe::set_system_thread_group(system_instance());
970
971 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
972 {
973 JavaValue result(T_VOID);
974 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
975 JavaCalls::call_special(&result,
976 main_instance,
977 ik,
978 vmSymbols::object_initializer_name(),
979 vmSymbols::threadgroup_string_void_signature(),
980 system_instance,
981 string,
982 CHECK_NH);
983 }
984 return main_instance;
985 }
986
987 // Creates the initial Thread
988 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
989 TRAPS) {
990 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
991 InstanceKlass* ik = InstanceKlass::cast(k);
992 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
993
994 java_lang_Thread::set_thread(thread_oop(), thread);
995 java_lang_Thread::set_priority(thread_oop(), NormPriority);
996 thread->set_threadObj(thread_oop());
997
998 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
999
1000 JavaValue result(T_VOID);
1001 JavaCalls::call_special(&result, thread_oop,
1002 ik,
1003 vmSymbols::object_initializer_name(),
1004 vmSymbols::threadgroup_string_void_signature(),
1005 thread_group,
1006 string,
1007 CHECK_NULL);
1008 return thread_oop();
1009 }
1010
1011 char java_runtime_name[128] = "";
1012 char java_runtime_version[128] = "";
1013
1014 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1015 static const char* get_java_runtime_name(TRAPS) {
1016 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1017 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1018 fieldDescriptor fd;
1019 bool found = k != NULL &&
1020 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1021 vmSymbols::string_signature(), &fd);
1022 if (found) {
1023 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1024 if (name_oop == NULL) {
1025 return NULL;
1026 }
1027 const char* name = java_lang_String::as_utf8_string(name_oop,
1028 java_runtime_name,
1029 sizeof(java_runtime_name));
1030 return name;
1031 } else {
1032 return NULL;
1033 }
1034 }
1035
1036 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1037 static const char* get_java_runtime_version(TRAPS) {
1038 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1039 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1040 fieldDescriptor fd;
1041 bool found = k != NULL &&
1042 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1043 vmSymbols::string_signature(), &fd);
1044 if (found) {
1045 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1046 if (name_oop == NULL) {
1047 return NULL;
1048 }
1049 const char* name = java_lang_String::as_utf8_string(name_oop,
1050 java_runtime_version,
1051 sizeof(java_runtime_version));
1052 return name;
1053 } else {
1054 return NULL;
1055 }
1056 }
1057
1058 // General purpose hook into Java code, run once when the VM is initialized.
1059 // The Java library method itself may be changed independently from the VM.
1060 static void call_postVMInitHook(TRAPS) {
1061 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1062 if (klass != NULL) {
1063 JavaValue result(T_VOID);
1064 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1065 vmSymbols::void_method_signature(),
1066 CHECK);
1067 }
1068 }
1069
1070 static void reset_vm_info_property(TRAPS) {
1071 // the vm info string
1072 ResourceMark rm(THREAD);
1073 const char *vm_info = VM_Version::vm_info_string();
1074
1075 // java.lang.System class
1076 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1077
1078 // setProperty arguments
1079 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1080 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1081
1082 // return value
1083 JavaValue r(T_OBJECT);
1084
1085 // public static String setProperty(String key, String value);
1086 JavaCalls::call_static(&r,
1087 klass,
1088 vmSymbols::setProperty_name(),
1089 vmSymbols::string_string_string_signature(),
1090 key_str,
1091 value_str,
1092 CHECK);
1093 }
1094
1095
1096 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1097 bool daemon, TRAPS) {
1098 assert(thread_group.not_null(), "thread group should be specified");
1099 assert(threadObj() == NULL, "should only create Java thread object once");
1100
1101 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1102 InstanceKlass* ik = InstanceKlass::cast(k);
1103 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1104
1105 java_lang_Thread::set_thread(thread_oop(), this);
1106 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1107 set_threadObj(thread_oop());
1108
1109 JavaValue result(T_VOID);
1110 if (thread_name != NULL) {
1111 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1112 // Thread gets assigned specified name and null target
1113 JavaCalls::call_special(&result,
1114 thread_oop,
1115 ik,
1116 vmSymbols::object_initializer_name(),
1117 vmSymbols::threadgroup_string_void_signature(),
1118 thread_group, // Argument 1
1119 name, // Argument 2
1120 THREAD);
1121 } else {
1122 // Thread gets assigned name "Thread-nnn" and null target
1123 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1124 JavaCalls::call_special(&result,
1125 thread_oop,
1126 ik,
1127 vmSymbols::object_initializer_name(),
1128 vmSymbols::threadgroup_runnable_void_signature(),
1129 thread_group, // Argument 1
1130 Handle(), // Argument 2
1131 THREAD);
1132 }
1133
1134
1135 if (daemon) {
1136 java_lang_Thread::set_daemon(thread_oop());
1137 }
1138
1139 if (HAS_PENDING_EXCEPTION) {
1140 return;
1141 }
1142
1143 Klass* group = SystemDictionary::ThreadGroup_klass();
1144 Handle threadObj(THREAD, this->threadObj());
1145
1146 JavaCalls::call_special(&result,
1147 thread_group,
1148 group,
1149 vmSymbols::add_method_name(),
1150 vmSymbols::thread_void_signature(),
1151 threadObj, // Arg 1
1152 THREAD);
1153 }
1154
1155 // NamedThread -- non-JavaThread subclasses with multiple
1156 // uniquely named instances should derive from this.
1157 NamedThread::NamedThread() : Thread() {
1158 _name = NULL;
1159 _processed_thread = NULL;
1160 _gc_id = GCId::undefined();
1161 }
1162
1163 NamedThread::~NamedThread() {
1164 if (_name != NULL) {
1165 FREE_C_HEAP_ARRAY(char, _name);
1166 _name = NULL;
1167 }
1168 }
1169
1170 void NamedThread::set_name(const char* format, ...) {
1171 guarantee(_name == NULL, "Only get to set name once.");
1172 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1173 guarantee(_name != NULL, "alloc failure");
1174 va_list ap;
1175 va_start(ap, format);
1176 jio_vsnprintf(_name, max_name_len, format, ap);
1177 va_end(ap);
1178 }
1179
1180 void NamedThread::initialize_named_thread() {
1181 set_native_thread_name(name());
1182 }
1183
1184 void NamedThread::print_on(outputStream* st) const {
1185 st->print("\"%s\" ", name());
1186 Thread::print_on(st);
1187 st->cr();
1188 }
1189
1190
1191 // ======= WatcherThread ========
1192
1193 // The watcher thread exists to simulate timer interrupts. It should
1194 // be replaced by an abstraction over whatever native support for
1195 // timer interrupts exists on the platform.
1196
1197 WatcherThread* WatcherThread::_watcher_thread = NULL;
1198 bool WatcherThread::_startable = false;
1199 volatile bool WatcherThread::_should_terminate = false;
1200
1201 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1202 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1203 if (os::create_thread(this, os::watcher_thread)) {
1204 _watcher_thread = this;
1205
1206 // Set the watcher thread to the highest OS priority which should not be
1207 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1208 // is created. The only normal thread using this priority is the reference
1209 // handler thread, which runs for very short intervals only.
1210 // If the VMThread's priority is not lower than the WatcherThread profiling
1211 // will be inaccurate.
1212 os::set_priority(this, MaxPriority);
1213 if (!DisableStartThread) {
1214 os::start_thread(this);
1215 }
1216 }
1217 }
1218
1219 int WatcherThread::sleep() const {
1220 // The WatcherThread does not participate in the safepoint protocol
1221 // for the PeriodicTask_lock because it is not a JavaThread.
1222 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1223
1224 if (_should_terminate) {
1225 // check for termination before we do any housekeeping or wait
1226 return 0; // we did not sleep.
1227 }
1228
1229 // remaining will be zero if there are no tasks,
1230 // causing the WatcherThread to sleep until a task is
1231 // enrolled
1232 int remaining = PeriodicTask::time_to_wait();
1233 int time_slept = 0;
1234
1235 // we expect this to timeout - we only ever get unparked when
1236 // we should terminate or when a new task has been enrolled
1237 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1238
1239 jlong time_before_loop = os::javaTimeNanos();
1240
1241 while (true) {
1242 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1243 remaining);
1244 jlong now = os::javaTimeNanos();
1245
1246 if (remaining == 0) {
1247 // if we didn't have any tasks we could have waited for a long time
1248 // consider the time_slept zero and reset time_before_loop
1249 time_slept = 0;
1250 time_before_loop = now;
1251 } else {
1252 // need to recalculate since we might have new tasks in _tasks
1253 time_slept = (int) ((now - time_before_loop) / 1000000);
1254 }
1255
1256 // Change to task list or spurious wakeup of some kind
1257 if (timedout || _should_terminate) {
1258 break;
1259 }
1260
1261 remaining = PeriodicTask::time_to_wait();
1262 if (remaining == 0) {
1263 // Last task was just disenrolled so loop around and wait until
1264 // another task gets enrolled
1265 continue;
1266 }
1267
1268 remaining -= time_slept;
1269 if (remaining <= 0) {
1270 break;
1271 }
1272 }
1273
1274 return time_slept;
1275 }
1276
1277 void WatcherThread::run() {
1278 assert(this == watcher_thread(), "just checking");
1279
1280 this->record_stack_base_and_size();
1281 this->set_native_thread_name(this->name());
1282 this->set_active_handles(JNIHandleBlock::allocate_block());
1283 while (true) {
1284 assert(watcher_thread() == Thread::current(), "thread consistency check");
1285 assert(watcher_thread() == this, "thread consistency check");
1286
1287 // Calculate how long it'll be until the next PeriodicTask work
1288 // should be done, and sleep that amount of time.
1289 int time_waited = sleep();
1290
1291 if (is_error_reported()) {
1292 // A fatal error has happened, the error handler(VMError::report_and_die)
1293 // should abort JVM after creating an error log file. However in some
1294 // rare cases, the error handler itself might deadlock. Here periodically
1295 // check for error reporting timeouts, and if it happens, just proceed to
1296 // abort the VM.
1297
1298 // This code is in WatcherThread because WatcherThread wakes up
1299 // periodically so the fatal error handler doesn't need to do anything;
1300 // also because the WatcherThread is less likely to crash than other
1301 // threads.
1302
1303 for (;;) {
1304 // Note: we use naked sleep in this loop because we want to avoid using
1305 // any kind of VM infrastructure which may be broken at this point.
1306 if (VMError::check_timeout()) {
1307 // We hit error reporting timeout. Error reporting was interrupted and
1308 // will be wrapping things up now (closing files etc). Give it some more
1309 // time, then quit the VM.
1310 os::naked_short_sleep(200);
1311 // Print a message to stderr.
1312 fdStream err(defaultStream::output_fd());
1313 err.print_raw_cr("# [ timer expired, abort... ]");
1314 // skip atexit/vm_exit/vm_abort hooks
1315 os::die();
1316 }
1317
1318 // Wait a second, then recheck for timeout.
1319 os::naked_short_sleep(999);
1320 }
1321 }
1322
1323 if (_should_terminate) {
1324 // check for termination before posting the next tick
1325 break;
1326 }
1327
1328 PeriodicTask::real_time_tick(time_waited);
1329 }
1330
1331 // Signal that it is terminated
1332 {
1333 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1334 _watcher_thread = NULL;
1335 Terminator_lock->notify();
1336 }
1337 }
1338
1339 void WatcherThread::start() {
1340 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1341
1342 if (watcher_thread() == NULL && _startable) {
1343 _should_terminate = false;
1344 // Create the single instance of WatcherThread
1345 new WatcherThread();
1346 }
1347 }
1348
1349 void WatcherThread::make_startable() {
1350 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1351 _startable = true;
1352 }
1353
1354 void WatcherThread::stop() {
1355 {
1356 // Follow normal safepoint aware lock enter protocol since the
1357 // WatcherThread is stopped by another JavaThread.
1358 MutexLocker ml(PeriodicTask_lock);
1359 _should_terminate = true;
1360
1361 WatcherThread* watcher = watcher_thread();
1362 if (watcher != NULL) {
1363 // unpark the WatcherThread so it can see that it should terminate
1364 watcher->unpark();
1365 }
1366 }
1367
1368 MutexLocker mu(Terminator_lock);
1369
1370 while (watcher_thread() != NULL) {
1371 // This wait should make safepoint checks, wait without a timeout,
1372 // and wait as a suspend-equivalent condition.
1373 //
1374 // Note: If the FlatProfiler is running, then this thread is waiting
1375 // for the WatcherThread to terminate and the WatcherThread, via the
1376 // FlatProfiler task, is waiting for the external suspend request on
1377 // this thread to complete. wait_for_ext_suspend_completion() will
1378 // eventually timeout, but that takes time. Making this wait a
1379 // suspend-equivalent condition solves that timeout problem.
1380 //
1381 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1382 Mutex::_as_suspend_equivalent_flag);
1383 }
1384 }
1385
1386 void WatcherThread::unpark() {
1387 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1388 PeriodicTask_lock->notify();
1389 }
1390
1391 void WatcherThread::print_on(outputStream* st) const {
1392 st->print("\"%s\" ", name());
1393 Thread::print_on(st);
1394 st->cr();
1395 }
1396
1397 // ======= JavaThread ========
1398
1399 #if INCLUDE_JVMCI
1400
1401 jlong* JavaThread::_jvmci_old_thread_counters;
1402
1403 bool jvmci_counters_include(JavaThread* thread) {
1404 oop threadObj = thread->threadObj();
1405 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1406 }
1407
1408 void JavaThread::collect_counters(typeArrayOop array) {
1409 if (JVMCICounterSize > 0) {
1410 MutexLocker tl(Threads_lock);
1411 for (int i = 0; i < array->length(); i++) {
1412 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1413 }
1414 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1415 if (jvmci_counters_include(tp)) {
1416 for (int i = 0; i < array->length(); i++) {
1417 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1418 }
1419 }
1420 }
1421 }
1422 }
1423
1424 #endif // INCLUDE_JVMCI
1425
1426 // A JavaThread is a normal Java thread
1427
1428 void JavaThread::initialize() {
1429 // Initialize fields
1430
1431 set_saved_exception_pc(NULL);
1432 set_threadObj(NULL);
1433 _anchor.clear();
1434 set_entry_point(NULL);
1435 set_jni_functions(jni_functions());
1436 set_callee_target(NULL);
1437 set_vm_result(NULL);
1438 set_vm_result_2(NULL);
1439 set_vframe_array_head(NULL);
1440 set_vframe_array_last(NULL);
1441 set_deferred_locals(NULL);
1442 set_deopt_mark(NULL);
1443 set_deopt_compiled_method(NULL);
1444 clear_must_deopt_id();
1445 set_monitor_chunks(NULL);
1446 set_next(NULL);
1447 set_thread_state(_thread_new);
1448 _terminated = _not_terminated;
1449 _privileged_stack_top = NULL;
1450 _array_for_gc = NULL;
1451 _suspend_equivalent = false;
1452 _in_deopt_handler = 0;
1453 _doing_unsafe_access = false;
1454 _stack_guard_state = stack_guard_unused;
1455 #if INCLUDE_JVMCI
1456 _pending_monitorenter = false;
1457 _pending_deoptimization = -1;
1458 _pending_failed_speculation = NULL;
1459 _pending_transfer_to_interpreter = false;
1460 _adjusting_comp_level = false;
1461 _jvmci._alternate_call_target = NULL;
1462 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1463 if (JVMCICounterSize > 0) {
1464 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1465 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1466 } else {
1467 _jvmci_counters = NULL;
1468 }
1469 #endif // INCLUDE_JVMCI
1470 _reserved_stack_activation = NULL; // stack base not known yet
1471 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1472 _exception_pc = 0;
1473 _exception_handler_pc = 0;
1474 _is_method_handle_return = 0;
1475 _jvmti_thread_state= NULL;
1476 _should_post_on_exceptions_flag = JNI_FALSE;
1477 _jvmti_get_loaded_classes_closure = NULL;
1478 _interp_only_mode = 0;
1479 _special_runtime_exit_condition = _no_async_condition;
1480 _pending_async_exception = NULL;
1481 _thread_stat = NULL;
1482 _thread_stat = new ThreadStatistics();
1483 _blocked_on_compilation = false;
1484 _jni_active_critical = 0;
1485 _pending_jni_exception_check_fn = NULL;
1486 _do_not_unlock_if_synchronized = false;
1487 _cached_monitor_info = NULL;
1488 _parker = Parker::Allocate(this);
1489
1490 #ifndef PRODUCT
1491 _jmp_ring_index = 0;
1492 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1493 record_jump(NULL, NULL, NULL, 0);
1494 }
1495 #endif // PRODUCT
1496
1497 set_thread_profiler(NULL);
1498 if (FlatProfiler::is_active()) {
1499 // This is where we would decide to either give each thread it's own profiler
1500 // or use one global one from FlatProfiler,
1501 // or up to some count of the number of profiled threads, etc.
1502 ThreadProfiler* pp = new ThreadProfiler();
1503 pp->engage();
1504 set_thread_profiler(pp);
1505 }
1506
1507 // Setup safepoint state info for this thread
1508 ThreadSafepointState::create(this);
1509
1510 debug_only(_java_call_counter = 0);
1511
1512 // JVMTI PopFrame support
1513 _popframe_condition = popframe_inactive;
1514 _popframe_preserved_args = NULL;
1515 _popframe_preserved_args_size = 0;
1516 _frames_to_pop_failed_realloc = 0;
1517
1518 pd_initialize();
1519 }
1520
1521 #if INCLUDE_ALL_GCS
1522 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1523 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1524 #endif // INCLUDE_ALL_GCS
1525
1526 JavaThread::JavaThread(bool is_attaching_via_jni) :
1527 Thread()
1528 #if INCLUDE_ALL_GCS
1529 , _satb_mark_queue(&_satb_mark_queue_set),
1530 _dirty_card_queue(&_dirty_card_queue_set)
1531 #endif // INCLUDE_ALL_GCS
1532 {
1533 initialize();
1534 if (is_attaching_via_jni) {
1535 _jni_attach_state = _attaching_via_jni;
1536 } else {
1537 _jni_attach_state = _not_attaching_via_jni;
1538 }
1539 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1540 }
1541
1542 bool JavaThread::reguard_stack(address cur_sp) {
1543 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1544 && _stack_guard_state != stack_guard_reserved_disabled) {
1545 return true; // Stack already guarded or guard pages not needed.
1546 }
1547
1548 if (register_stack_overflow()) {
1549 // For those architectures which have separate register and
1550 // memory stacks, we must check the register stack to see if
1551 // it has overflowed.
1552 return false;
1553 }
1554
1555 // Java code never executes within the yellow zone: the latter is only
1556 // there to provoke an exception during stack banging. If java code
1557 // is executing there, either StackShadowPages should be larger, or
1558 // some exception code in c1, c2 or the interpreter isn't unwinding
1559 // when it should.
1560 guarantee(cur_sp > stack_reserved_zone_base(),
1561 "not enough space to reguard - increase StackShadowPages");
1562 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1563 enable_stack_yellow_reserved_zone();
1564 if (reserved_stack_activation() != stack_base()) {
1565 set_reserved_stack_activation(stack_base());
1566 }
1567 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1568 set_reserved_stack_activation(stack_base());
1569 enable_stack_reserved_zone();
1570 }
1571 return true;
1572 }
1573
1574 bool JavaThread::reguard_stack(void) {
1575 return reguard_stack(os::current_stack_pointer());
1576 }
1577
1578
1579 void JavaThread::block_if_vm_exited() {
1580 if (_terminated == _vm_exited) {
1581 // _vm_exited is set at safepoint, and Threads_lock is never released
1582 // we will block here forever
1583 Threads_lock->lock_without_safepoint_check();
1584 ShouldNotReachHere();
1585 }
1586 }
1587
1588
1589 // Remove this ifdef when C1 is ported to the compiler interface.
1590 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1591 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1592
1593 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1594 Thread()
1595 #if INCLUDE_ALL_GCS
1596 , _satb_mark_queue(&_satb_mark_queue_set),
1597 _dirty_card_queue(&_dirty_card_queue_set)
1598 #endif // INCLUDE_ALL_GCS
1599 {
1600 initialize();
1601 _jni_attach_state = _not_attaching_via_jni;
1602 set_entry_point(entry_point);
1603 // Create the native thread itself.
1604 // %note runtime_23
1605 os::ThreadType thr_type = os::java_thread;
1606 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1607 os::java_thread;
1608 os::create_thread(this, thr_type, stack_sz);
1609 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1610 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1611 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1612 // the exception consists of creating the exception object & initializing it, initialization
1613 // will leave the VM via a JavaCall and then all locks must be unlocked).
1614 //
1615 // The thread is still suspended when we reach here. Thread must be explicit started
1616 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1617 // by calling Threads:add. The reason why this is not done here, is because the thread
1618 // object must be fully initialized (take a look at JVM_Start)
1619 }
1620
1621 JavaThread::~JavaThread() {
1622
1623 // JSR166 -- return the parker to the free list
1624 Parker::Release(_parker);
1625 _parker = NULL;
1626
1627 // Free any remaining previous UnrollBlock
1628 vframeArray* old_array = vframe_array_last();
1629
1630 if (old_array != NULL) {
1631 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1632 old_array->set_unroll_block(NULL);
1633 delete old_info;
1634 delete old_array;
1635 }
1636
1637 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1638 if (deferred != NULL) {
1639 // This can only happen if thread is destroyed before deoptimization occurs.
1640 assert(deferred->length() != 0, "empty array!");
1641 do {
1642 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1643 deferred->remove_at(0);
1644 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1645 delete dlv;
1646 } while (deferred->length() != 0);
1647 delete deferred;
1648 }
1649
1650 // All Java related clean up happens in exit
1651 ThreadSafepointState::destroy(this);
1652 if (_thread_profiler != NULL) delete _thread_profiler;
1653 if (_thread_stat != NULL) delete _thread_stat;
1654
1655 #if INCLUDE_JVMCI
1656 if (JVMCICounterSize > 0) {
1657 if (jvmci_counters_include(this)) {
1658 for (int i = 0; i < JVMCICounterSize; i++) {
1659 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1660 }
1661 }
1662 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1663 }
1664 #endif // INCLUDE_JVMCI
1665 }
1666
1667
1668 // The first routine called by a new Java thread
1669 void JavaThread::run() {
1670 // initialize thread-local alloc buffer related fields
1671 this->initialize_tlab();
1672
1673 // used to test validity of stack trace backs
1674 this->record_base_of_stack_pointer();
1675
1676 // Record real stack base and size.
1677 this->record_stack_base_and_size();
1678
1679 this->create_stack_guard_pages();
1680
1681 this->cache_global_variables();
1682
1683 // Thread is now sufficient initialized to be handled by the safepoint code as being
1684 // in the VM. Change thread state from _thread_new to _thread_in_vm
1685 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1686
1687 assert(JavaThread::current() == this, "sanity check");
1688 assert(!Thread::current()->owns_locks(), "sanity check");
1689
1690 DTRACE_THREAD_PROBE(start, this);
1691
1692 // This operation might block. We call that after all safepoint checks for a new thread has
1693 // been completed.
1694 this->set_active_handles(JNIHandleBlock::allocate_block());
1695
1696 if (JvmtiExport::should_post_thread_life()) {
1697 JvmtiExport::post_thread_start(this);
1698 }
1699
1700 EventThreadStart event;
1701 if (event.should_commit()) {
1702 event.set_thread(THREAD_TRACE_ID(this));
1703 event.commit();
1704 }
1705
1706 // We call another function to do the rest so we are sure that the stack addresses used
1707 // from there will be lower than the stack base just computed
1708 thread_main_inner();
1709
1710 // Note, thread is no longer valid at this point!
1711 }
1712
1713
1714 void JavaThread::thread_main_inner() {
1715 assert(JavaThread::current() == this, "sanity check");
1716 assert(this->threadObj() != NULL, "just checking");
1717
1718 // Execute thread entry point unless this thread has a pending exception
1719 // or has been stopped before starting.
1720 // Note: Due to JVM_StopThread we can have pending exceptions already!
1721 if (!this->has_pending_exception() &&
1722 !java_lang_Thread::is_stillborn(this->threadObj())) {
1723 {
1724 ResourceMark rm(this);
1725 this->set_native_thread_name(this->get_thread_name());
1726 }
1727 HandleMark hm(this);
1728 this->entry_point()(this, this);
1729 }
1730
1731 DTRACE_THREAD_PROBE(stop, this);
1732
1733 this->exit(false);
1734 delete this;
1735 }
1736
1737
1738 static void ensure_join(JavaThread* thread) {
1739 // We do not need to grap the Threads_lock, since we are operating on ourself.
1740 Handle threadObj(thread, thread->threadObj());
1741 assert(threadObj.not_null(), "java thread object must exist");
1742 ObjectLocker lock(threadObj, thread);
1743 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1744 thread->clear_pending_exception();
1745 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1746 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1747 // Clear the native thread instance - this makes isAlive return false and allows the join()
1748 // to complete once we've done the notify_all below
1749 java_lang_Thread::set_thread(threadObj(), NULL);
1750 lock.notify_all(thread);
1751 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1752 thread->clear_pending_exception();
1753 }
1754
1755
1756 // For any new cleanup additions, please check to see if they need to be applied to
1757 // cleanup_failed_attach_current_thread as well.
1758 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1759 assert(this == JavaThread::current(), "thread consistency check");
1760
1761 HandleMark hm(this);
1762 Handle uncaught_exception(this, this->pending_exception());
1763 this->clear_pending_exception();
1764 Handle threadObj(this, this->threadObj());
1765 assert(threadObj.not_null(), "Java thread object should be created");
1766
1767 if (get_thread_profiler() != NULL) {
1768 get_thread_profiler()->disengage();
1769 ResourceMark rm;
1770 get_thread_profiler()->print(get_thread_name());
1771 }
1772
1773
1774 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1775 {
1776 EXCEPTION_MARK;
1777
1778 CLEAR_PENDING_EXCEPTION;
1779 }
1780 if (!destroy_vm) {
1781 if (uncaught_exception.not_null()) {
1782 EXCEPTION_MARK;
1783 // Call method Thread.dispatchUncaughtException().
1784 Klass* thread_klass = SystemDictionary::Thread_klass();
1785 JavaValue result(T_VOID);
1786 JavaCalls::call_virtual(&result,
1787 threadObj, thread_klass,
1788 vmSymbols::dispatchUncaughtException_name(),
1789 vmSymbols::throwable_void_signature(),
1790 uncaught_exception,
1791 THREAD);
1792 if (HAS_PENDING_EXCEPTION) {
1793 ResourceMark rm(this);
1794 jio_fprintf(defaultStream::error_stream(),
1795 "\nException: %s thrown from the UncaughtExceptionHandler"
1796 " in thread \"%s\"\n",
1797 pending_exception()->klass()->external_name(),
1798 get_thread_name());
1799 CLEAR_PENDING_EXCEPTION;
1800 }
1801 }
1802
1803 // Called before the java thread exit since we want to read info
1804 // from java_lang_Thread object
1805 EventThreadEnd event;
1806 if (event.should_commit()) {
1807 event.set_thread(THREAD_TRACE_ID(this));
1808 event.commit();
1809 }
1810
1811 // Call after last event on thread
1812 EVENT_THREAD_EXIT(this);
1813
1814 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1815 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1816 // is deprecated anyhow.
1817 if (!is_Compiler_thread()) {
1818 int count = 3;
1819 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1820 EXCEPTION_MARK;
1821 JavaValue result(T_VOID);
1822 Klass* thread_klass = SystemDictionary::Thread_klass();
1823 JavaCalls::call_virtual(&result,
1824 threadObj, thread_klass,
1825 vmSymbols::exit_method_name(),
1826 vmSymbols::void_method_signature(),
1827 THREAD);
1828 CLEAR_PENDING_EXCEPTION;
1829 }
1830 }
1831 // notify JVMTI
1832 if (JvmtiExport::should_post_thread_life()) {
1833 JvmtiExport::post_thread_end(this);
1834 }
1835
1836 // We have notified the agents that we are exiting, before we go on,
1837 // we must check for a pending external suspend request and honor it
1838 // in order to not surprise the thread that made the suspend request.
1839 while (true) {
1840 {
1841 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1842 if (!is_external_suspend()) {
1843 set_terminated(_thread_exiting);
1844 ThreadService::current_thread_exiting(this);
1845 break;
1846 }
1847 // Implied else:
1848 // Things get a little tricky here. We have a pending external
1849 // suspend request, but we are holding the SR_lock so we
1850 // can't just self-suspend. So we temporarily drop the lock
1851 // and then self-suspend.
1852 }
1853
1854 ThreadBlockInVM tbivm(this);
1855 java_suspend_self();
1856
1857 // We're done with this suspend request, but we have to loop around
1858 // and check again. Eventually we will get SR_lock without a pending
1859 // external suspend request and will be able to mark ourselves as
1860 // exiting.
1861 }
1862 // no more external suspends are allowed at this point
1863 } else {
1864 // before_exit() has already posted JVMTI THREAD_END events
1865 }
1866
1867 // Notify waiters on thread object. This has to be done after exit() is called
1868 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1869 // group should have the destroyed bit set before waiters are notified).
1870 ensure_join(this);
1871 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1872
1873 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1874 // held by this thread must be released. The spec does not distinguish
1875 // between JNI-acquired and regular Java monitors. We can only see
1876 // regular Java monitors here if monitor enter-exit matching is broken.
1877 //
1878 // Optionally release any monitors for regular JavaThread exits. This
1879 // is provided as a work around for any bugs in monitor enter-exit
1880 // matching. This can be expensive so it is not enabled by default.
1881 //
1882 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1883 // ObjectSynchronizer::release_monitors_owned_by_thread().
1884 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1885 // Sanity check even though JNI DetachCurrentThread() would have
1886 // returned JNI_ERR if there was a Java frame. JavaThread exit
1887 // should be done executing Java code by the time we get here.
1888 assert(!this->has_last_Java_frame(),
1889 "should not have a Java frame when detaching or exiting");
1890 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1891 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1892 }
1893
1894 // These things needs to be done while we are still a Java Thread. Make sure that thread
1895 // is in a consistent state, in case GC happens
1896 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1897
1898 if (active_handles() != NULL) {
1899 JNIHandleBlock* block = active_handles();
1900 set_active_handles(NULL);
1901 JNIHandleBlock::release_block(block);
1902 }
1903
1904 if (free_handle_block() != NULL) {
1905 JNIHandleBlock* block = free_handle_block();
1906 set_free_handle_block(NULL);
1907 JNIHandleBlock::release_block(block);
1908 }
1909
1910 // These have to be removed while this is still a valid thread.
1911 remove_stack_guard_pages();
1912
1913 if (UseTLAB) {
1914 tlab().make_parsable(true); // retire TLAB
1915 }
1916
1917 if (JvmtiEnv::environments_might_exist()) {
1918 JvmtiExport::cleanup_thread(this);
1919 }
1920
1921 // We must flush any deferred card marks before removing a thread from
1922 // the list of active threads.
1923 Universe::heap()->flush_deferred_store_barrier(this);
1924 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1925
1926 #if INCLUDE_ALL_GCS
1927 // We must flush the G1-related buffers before removing a thread
1928 // from the list of active threads. We must do this after any deferred
1929 // card marks have been flushed (above) so that any entries that are
1930 // added to the thread's dirty card queue as a result are not lost.
1931 if (UseG1GC) {
1932 flush_barrier_queues();
1933 }
1934 #endif // INCLUDE_ALL_GCS
1935
1936 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1937 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1938 os::current_thread_id());
1939
1940 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1941 Threads::remove(this);
1942 }
1943
1944 #if INCLUDE_ALL_GCS
1945 // Flush G1-related queues.
1946 void JavaThread::flush_barrier_queues() {
1947 satb_mark_queue().flush();
1948 dirty_card_queue().flush();
1949 }
1950
1951 void JavaThread::initialize_queues() {
1952 assert(!SafepointSynchronize::is_at_safepoint(),
1953 "we should not be at a safepoint");
1954
1955 SATBMarkQueue& satb_queue = satb_mark_queue();
1956 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1957 // The SATB queue should have been constructed with its active
1958 // field set to false.
1959 assert(!satb_queue.is_active(), "SATB queue should not be active");
1960 assert(satb_queue.is_empty(), "SATB queue should be empty");
1961 // If we are creating the thread during a marking cycle, we should
1962 // set the active field of the SATB queue to true.
1963 if (satb_queue_set.is_active()) {
1964 satb_queue.set_active(true);
1965 }
1966
1967 DirtyCardQueue& dirty_queue = dirty_card_queue();
1968 // The dirty card queue should have been constructed with its
1969 // active field set to true.
1970 assert(dirty_queue.is_active(), "dirty card queue should be active");
1971 }
1972 #endif // INCLUDE_ALL_GCS
1973
1974 void JavaThread::cleanup_failed_attach_current_thread() {
1975 if (get_thread_profiler() != NULL) {
1976 get_thread_profiler()->disengage();
1977 ResourceMark rm;
1978 get_thread_profiler()->print(get_thread_name());
1979 }
1980
1981 if (active_handles() != NULL) {
1982 JNIHandleBlock* block = active_handles();
1983 set_active_handles(NULL);
1984 JNIHandleBlock::release_block(block);
1985 }
1986
1987 if (free_handle_block() != NULL) {
1988 JNIHandleBlock* block = free_handle_block();
1989 set_free_handle_block(NULL);
1990 JNIHandleBlock::release_block(block);
1991 }
1992
1993 // These have to be removed while this is still a valid thread.
1994 remove_stack_guard_pages();
1995
1996 if (UseTLAB) {
1997 tlab().make_parsable(true); // retire TLAB, if any
1998 }
1999
2000 #if INCLUDE_ALL_GCS
2001 if (UseG1GC) {
2002 flush_barrier_queues();
2003 }
2004 #endif // INCLUDE_ALL_GCS
2005
2006 Threads::remove(this);
2007 delete this;
2008 }
2009
2010
2011
2012
2013 JavaThread* JavaThread::active() {
2014 Thread* thread = Thread::current();
2015 if (thread->is_Java_thread()) {
2016 return (JavaThread*) thread;
2017 } else {
2018 assert(thread->is_VM_thread(), "this must be a vm thread");
2019 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2020 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2021 assert(ret->is_Java_thread(), "must be a Java thread");
2022 return ret;
2023 }
2024 }
2025
2026 bool JavaThread::is_lock_owned(address adr) const {
2027 if (Thread::is_lock_owned(adr)) return true;
2028
2029 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2030 if (chunk->contains(adr)) return true;
2031 }
2032
2033 return false;
2034 }
2035
2036
2037 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2038 chunk->set_next(monitor_chunks());
2039 set_monitor_chunks(chunk);
2040 }
2041
2042 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2043 guarantee(monitor_chunks() != NULL, "must be non empty");
2044 if (monitor_chunks() == chunk) {
2045 set_monitor_chunks(chunk->next());
2046 } else {
2047 MonitorChunk* prev = monitor_chunks();
2048 while (prev->next() != chunk) prev = prev->next();
2049 prev->set_next(chunk->next());
2050 }
2051 }
2052
2053 // JVM support.
2054
2055 // Note: this function shouldn't block if it's called in
2056 // _thread_in_native_trans state (such as from
2057 // check_special_condition_for_native_trans()).
2058 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2059
2060 if (has_last_Java_frame() && has_async_condition()) {
2061 // If we are at a polling page safepoint (not a poll return)
2062 // then we must defer async exception because live registers
2063 // will be clobbered by the exception path. Poll return is
2064 // ok because the call we a returning from already collides
2065 // with exception handling registers and so there is no issue.
2066 // (The exception handling path kills call result registers but
2067 // this is ok since the exception kills the result anyway).
2068
2069 if (is_at_poll_safepoint()) {
2070 // if the code we are returning to has deoptimized we must defer
2071 // the exception otherwise live registers get clobbered on the
2072 // exception path before deoptimization is able to retrieve them.
2073 //
2074 RegisterMap map(this, false);
2075 frame caller_fr = last_frame().sender(&map);
2076 assert(caller_fr.is_compiled_frame(), "what?");
2077 if (caller_fr.is_deoptimized_frame()) {
2078 log_info(exceptions)("deferred async exception at compiled safepoint");
2079 return;
2080 }
2081 }
2082 }
2083
2084 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2085 if (condition == _no_async_condition) {
2086 // Conditions have changed since has_special_runtime_exit_condition()
2087 // was called:
2088 // - if we were here only because of an external suspend request,
2089 // then that was taken care of above (or cancelled) so we are done
2090 // - if we were here because of another async request, then it has
2091 // been cleared between the has_special_runtime_exit_condition()
2092 // and now so again we are done
2093 return;
2094 }
2095
2096 // Check for pending async. exception
2097 if (_pending_async_exception != NULL) {
2098 // Only overwrite an already pending exception, if it is not a threadDeath.
2099 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2100
2101 // We cannot call Exceptions::_throw(...) here because we cannot block
2102 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2103
2104 if (log_is_enabled(Info, exceptions)) {
2105 ResourceMark rm;
2106 outputStream* logstream = Log(exceptions)::info_stream();
2107 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2108 if (has_last_Java_frame()) {
2109 frame f = last_frame();
2110 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2111 }
2112 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2113 }
2114 _pending_async_exception = NULL;
2115 clear_has_async_exception();
2116 }
2117 }
2118
2119 if (check_unsafe_error &&
2120 condition == _async_unsafe_access_error && !has_pending_exception()) {
2121 condition = _no_async_condition; // done
2122 switch (thread_state()) {
2123 case _thread_in_vm: {
2124 JavaThread* THREAD = this;
2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2126 }
2127 case _thread_in_native: {
2128 ThreadInVMfromNative tiv(this);
2129 JavaThread* THREAD = this;
2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2131 }
2132 case _thread_in_Java: {
2133 ThreadInVMfromJava tiv(this);
2134 JavaThread* THREAD = this;
2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2136 }
2137 default:
2138 ShouldNotReachHere();
2139 }
2140 }
2141
2142 assert(condition == _no_async_condition || has_pending_exception() ||
2143 (!check_unsafe_error && condition == _async_unsafe_access_error),
2144 "must have handled the async condition, if no exception");
2145 }
2146
2147 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2148 //
2149 // Check for pending external suspend. Internal suspend requests do
2150 // not use handle_special_runtime_exit_condition().
2151 // If JNIEnv proxies are allowed, don't self-suspend if the target
2152 // thread is not the current thread. In older versions of jdbx, jdbx
2153 // threads could call into the VM with another thread's JNIEnv so we
2154 // can be here operating on behalf of a suspended thread (4432884).
2155 bool do_self_suspend = is_external_suspend_with_lock();
2156 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2157 //
2158 // Because thread is external suspended the safepoint code will count
2159 // thread as at a safepoint. This can be odd because we can be here
2160 // as _thread_in_Java which would normally transition to _thread_blocked
2161 // at a safepoint. We would like to mark the thread as _thread_blocked
2162 // before calling java_suspend_self like all other callers of it but
2163 // we must then observe proper safepoint protocol. (We can't leave
2164 // _thread_blocked with a safepoint in progress). However we can be
2165 // here as _thread_in_native_trans so we can't use a normal transition
2166 // constructor/destructor pair because they assert on that type of
2167 // transition. We could do something like:
2168 //
2169 // JavaThreadState state = thread_state();
2170 // set_thread_state(_thread_in_vm);
2171 // {
2172 // ThreadBlockInVM tbivm(this);
2173 // java_suspend_self()
2174 // }
2175 // set_thread_state(_thread_in_vm_trans);
2176 // if (safepoint) block;
2177 // set_thread_state(state);
2178 //
2179 // but that is pretty messy. Instead we just go with the way the
2180 // code has worked before and note that this is the only path to
2181 // java_suspend_self that doesn't put the thread in _thread_blocked
2182 // mode.
2183
2184 frame_anchor()->make_walkable(this);
2185 java_suspend_self();
2186
2187 // We might be here for reasons in addition to the self-suspend request
2188 // so check for other async requests.
2189 }
2190
2191 if (check_asyncs) {
2192 check_and_handle_async_exceptions();
2193 }
2194 }
2195
2196 void JavaThread::send_thread_stop(oop java_throwable) {
2197 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2198 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2199 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2200
2201 // Do not throw asynchronous exceptions against the compiler thread
2202 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2203 if (!can_call_java()) return;
2204
2205 {
2206 // Actually throw the Throwable against the target Thread - however
2207 // only if there is no thread death exception installed already.
2208 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2209 // If the topmost frame is a runtime stub, then we are calling into
2210 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2211 // must deoptimize the caller before continuing, as the compiled exception handler table
2212 // may not be valid
2213 if (has_last_Java_frame()) {
2214 frame f = last_frame();
2215 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2216 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2217 RegisterMap reg_map(this, UseBiasedLocking);
2218 frame compiled_frame = f.sender(®_map);
2219 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2220 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2221 }
2222 }
2223 }
2224
2225 // Set async. pending exception in thread.
2226 set_pending_async_exception(java_throwable);
2227
2228 if (log_is_enabled(Info, exceptions)) {
2229 ResourceMark rm;
2230 log_info(exceptions)("Pending Async. exception installed of type: %s",
2231 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2232 }
2233 // for AbortVMOnException flag
2234 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2235 }
2236 }
2237
2238
2239 // Interrupt thread so it will wake up from a potential wait()
2240 Thread::interrupt(this);
2241 }
2242
2243 // External suspension mechanism.
2244 //
2245 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2246 // to any VM_locks and it is at a transition
2247 // Self-suspension will happen on the transition out of the vm.
2248 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2249 //
2250 // Guarantees on return:
2251 // + Target thread will not execute any new bytecode (that's why we need to
2252 // force a safepoint)
2253 // + Target thread will not enter any new monitors
2254 //
2255 void JavaThread::java_suspend() {
2256 { MutexLocker mu(Threads_lock);
2257 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2258 return;
2259 }
2260 }
2261
2262 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2263 if (!is_external_suspend()) {
2264 // a racing resume has cancelled us; bail out now
2265 return;
2266 }
2267
2268 // suspend is done
2269 uint32_t debug_bits = 0;
2270 // Warning: is_ext_suspend_completed() may temporarily drop the
2271 // SR_lock to allow the thread to reach a stable thread state if
2272 // it is currently in a transient thread state.
2273 if (is_ext_suspend_completed(false /* !called_by_wait */,
2274 SuspendRetryDelay, &debug_bits)) {
2275 return;
2276 }
2277 }
2278
2279 VM_ForceSafepoint vm_suspend;
2280 VMThread::execute(&vm_suspend);
2281 }
2282
2283 // Part II of external suspension.
2284 // A JavaThread self suspends when it detects a pending external suspend
2285 // request. This is usually on transitions. It is also done in places
2286 // where continuing to the next transition would surprise the caller,
2287 // e.g., monitor entry.
2288 //
2289 // Returns the number of times that the thread self-suspended.
2290 //
2291 // Note: DO NOT call java_suspend_self() when you just want to block current
2292 // thread. java_suspend_self() is the second stage of cooperative
2293 // suspension for external suspend requests and should only be used
2294 // to complete an external suspend request.
2295 //
2296 int JavaThread::java_suspend_self() {
2297 int ret = 0;
2298
2299 // we are in the process of exiting so don't suspend
2300 if (is_exiting()) {
2301 clear_external_suspend();
2302 return ret;
2303 }
2304
2305 assert(_anchor.walkable() ||
2306 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2307 "must have walkable stack");
2308
2309 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2310
2311 assert(!this->is_ext_suspended(),
2312 "a thread trying to self-suspend should not already be suspended");
2313
2314 if (this->is_suspend_equivalent()) {
2315 // If we are self-suspending as a result of the lifting of a
2316 // suspend equivalent condition, then the suspend_equivalent
2317 // flag is not cleared until we set the ext_suspended flag so
2318 // that wait_for_ext_suspend_completion() returns consistent
2319 // results.
2320 this->clear_suspend_equivalent();
2321 }
2322
2323 // A racing resume may have cancelled us before we grabbed SR_lock
2324 // above. Or another external suspend request could be waiting for us
2325 // by the time we return from SR_lock()->wait(). The thread
2326 // that requested the suspension may already be trying to walk our
2327 // stack and if we return now, we can change the stack out from under
2328 // it. This would be a "bad thing (TM)" and cause the stack walker
2329 // to crash. We stay self-suspended until there are no more pending
2330 // external suspend requests.
2331 while (is_external_suspend()) {
2332 ret++;
2333 this->set_ext_suspended();
2334
2335 // _ext_suspended flag is cleared by java_resume()
2336 while (is_ext_suspended()) {
2337 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2338 }
2339 }
2340
2341 return ret;
2342 }
2343
2344 #ifdef ASSERT
2345 // verify the JavaThread has not yet been published in the Threads::list, and
2346 // hence doesn't need protection from concurrent access at this stage
2347 void JavaThread::verify_not_published() {
2348 if (!Threads_lock->owned_by_self()) {
2349 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2350 assert(!Threads::includes(this),
2351 "java thread shouldn't have been published yet!");
2352 } else {
2353 assert(!Threads::includes(this),
2354 "java thread shouldn't have been published yet!");
2355 }
2356 }
2357 #endif
2358
2359 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2360 // progress or when _suspend_flags is non-zero.
2361 // Current thread needs to self-suspend if there is a suspend request and/or
2362 // block if a safepoint is in progress.
2363 // Async exception ISN'T checked.
2364 // Note only the ThreadInVMfromNative transition can call this function
2365 // directly and when thread state is _thread_in_native_trans
2366 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2367 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2368
2369 JavaThread *curJT = JavaThread::current();
2370 bool do_self_suspend = thread->is_external_suspend();
2371
2372 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2373
2374 // If JNIEnv proxies are allowed, don't self-suspend if the target
2375 // thread is not the current thread. In older versions of jdbx, jdbx
2376 // threads could call into the VM with another thread's JNIEnv so we
2377 // can be here operating on behalf of a suspended thread (4432884).
2378 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2379 JavaThreadState state = thread->thread_state();
2380
2381 // We mark this thread_blocked state as a suspend-equivalent so
2382 // that a caller to is_ext_suspend_completed() won't be confused.
2383 // The suspend-equivalent state is cleared by java_suspend_self().
2384 thread->set_suspend_equivalent();
2385
2386 // If the safepoint code sees the _thread_in_native_trans state, it will
2387 // wait until the thread changes to other thread state. There is no
2388 // guarantee on how soon we can obtain the SR_lock and complete the
2389 // self-suspend request. It would be a bad idea to let safepoint wait for
2390 // too long. Temporarily change the state to _thread_blocked to
2391 // let the VM thread know that this thread is ready for GC. The problem
2392 // of changing thread state is that safepoint could happen just after
2393 // java_suspend_self() returns after being resumed, and VM thread will
2394 // see the _thread_blocked state. We must check for safepoint
2395 // after restoring the state and make sure we won't leave while a safepoint
2396 // is in progress.
2397 thread->set_thread_state(_thread_blocked);
2398 thread->java_suspend_self();
2399 thread->set_thread_state(state);
2400 // Make sure new state is seen by VM thread
2401 if (os::is_MP()) {
2402 if (UseMembar) {
2403 // Force a fence between the write above and read below
2404 OrderAccess::fence();
2405 } else {
2406 // Must use this rather than serialization page in particular on Windows
2407 InterfaceSupport::serialize_memory(thread);
2408 }
2409 }
2410 }
2411
2412 if (SafepointSynchronize::do_call_back()) {
2413 // If we are safepointing, then block the caller which may not be
2414 // the same as the target thread (see above).
2415 SafepointSynchronize::block(curJT);
2416 }
2417
2418 if (thread->is_deopt_suspend()) {
2419 thread->clear_deopt_suspend();
2420 RegisterMap map(thread, false);
2421 frame f = thread->last_frame();
2422 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2423 f = f.sender(&map);
2424 }
2425 if (f.id() == thread->must_deopt_id()) {
2426 thread->clear_must_deopt_id();
2427 f.deoptimize(thread);
2428 } else {
2429 fatal("missed deoptimization!");
2430 }
2431 }
2432 }
2433
2434 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2435 // progress or when _suspend_flags is non-zero.
2436 // Current thread needs to self-suspend if there is a suspend request and/or
2437 // block if a safepoint is in progress.
2438 // Also check for pending async exception (not including unsafe access error).
2439 // Note only the native==>VM/Java barriers can call this function and when
2440 // thread state is _thread_in_native_trans.
2441 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2442 check_safepoint_and_suspend_for_native_trans(thread);
2443
2444 if (thread->has_async_exception()) {
2445 // We are in _thread_in_native_trans state, don't handle unsafe
2446 // access error since that may block.
2447 thread->check_and_handle_async_exceptions(false);
2448 }
2449 }
2450
2451 // This is a variant of the normal
2452 // check_special_condition_for_native_trans with slightly different
2453 // semantics for use by critical native wrappers. It does all the
2454 // normal checks but also performs the transition back into
2455 // thread_in_Java state. This is required so that critical natives
2456 // can potentially block and perform a GC if they are the last thread
2457 // exiting the GCLocker.
2458 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2459 check_special_condition_for_native_trans(thread);
2460
2461 // Finish the transition
2462 thread->set_thread_state(_thread_in_Java);
2463
2464 if (thread->do_critical_native_unlock()) {
2465 ThreadInVMfromJavaNoAsyncException tiv(thread);
2466 GCLocker::unlock_critical(thread);
2467 thread->clear_critical_native_unlock();
2468 }
2469 }
2470
2471 // We need to guarantee the Threads_lock here, since resumes are not
2472 // allowed during safepoint synchronization
2473 // Can only resume from an external suspension
2474 void JavaThread::java_resume() {
2475 assert_locked_or_safepoint(Threads_lock);
2476
2477 // Sanity check: thread is gone, has started exiting or the thread
2478 // was not externally suspended.
2479 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2480 return;
2481 }
2482
2483 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2484
2485 clear_external_suspend();
2486
2487 if (is_ext_suspended()) {
2488 clear_ext_suspended();
2489 SR_lock()->notify_all();
2490 }
2491 }
2492
2493 size_t JavaThread::_stack_red_zone_size = 0;
2494 size_t JavaThread::_stack_yellow_zone_size = 0;
2495 size_t JavaThread::_stack_reserved_zone_size = 0;
2496 size_t JavaThread::_stack_shadow_zone_size = 0;
2497
2498 void JavaThread::create_stack_guard_pages() {
2499 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2500 address low_addr = stack_end();
2501 size_t len = stack_guard_zone_size();
2502
2503 int must_commit = os::must_commit_stack_guard_pages();
2504 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2505
2506 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2507 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2508 return;
2509 }
2510
2511 if (os::guard_memory((char *) low_addr, len)) {
2512 _stack_guard_state = stack_guard_enabled;
2513 } else {
2514 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2515 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2516 if (os::uncommit_memory((char *) low_addr, len)) {
2517 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2518 }
2519 return;
2520 }
2521
2522 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2523 PTR_FORMAT "-" PTR_FORMAT ".",
2524 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2525 }
2526
2527 void JavaThread::remove_stack_guard_pages() {
2528 assert(Thread::current() == this, "from different thread");
2529 if (_stack_guard_state == stack_guard_unused) return;
2530 address low_addr = stack_end();
2531 size_t len = stack_guard_zone_size();
2532
2533 if (os::must_commit_stack_guard_pages()) {
2534 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2535 _stack_guard_state = stack_guard_unused;
2536 } else {
2537 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2538 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2539 return;
2540 }
2541 } else {
2542 if (_stack_guard_state == stack_guard_unused) return;
2543 if (os::unguard_memory((char *) low_addr, len)) {
2544 _stack_guard_state = stack_guard_unused;
2545 } else {
2546 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2547 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2548 return;
2549 }
2550 }
2551
2552 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2553 PTR_FORMAT "-" PTR_FORMAT ".",
2554 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2555 }
2556
2557 void JavaThread::enable_stack_reserved_zone() {
2558 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2559 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2560
2561 // The base notation is from the stack's point of view, growing downward.
2562 // We need to adjust it to work correctly with guard_memory()
2563 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2564
2565 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2566 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2567
2568 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2569 _stack_guard_state = stack_guard_enabled;
2570 } else {
2571 warning("Attempt to guard stack reserved zone failed.");
2572 }
2573 enable_register_stack_guard();
2574 }
2575
2576 void JavaThread::disable_stack_reserved_zone() {
2577 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2578 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2579
2580 // Simply return if called for a thread that does not use guard pages.
2581 if (_stack_guard_state == stack_guard_unused) return;
2582
2583 // The base notation is from the stack's point of view, growing downward.
2584 // We need to adjust it to work correctly with guard_memory()
2585 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2586
2587 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2588 _stack_guard_state = stack_guard_reserved_disabled;
2589 } else {
2590 warning("Attempt to unguard stack reserved zone failed.");
2591 }
2592 disable_register_stack_guard();
2593 }
2594
2595 void JavaThread::enable_stack_yellow_reserved_zone() {
2596 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2597 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2598
2599 // The base notation is from the stacks point of view, growing downward.
2600 // We need to adjust it to work correctly with guard_memory()
2601 address base = stack_red_zone_base();
2602
2603 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2604 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2605
2606 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2607 _stack_guard_state = stack_guard_enabled;
2608 } else {
2609 warning("Attempt to guard stack yellow zone failed.");
2610 }
2611 enable_register_stack_guard();
2612 }
2613
2614 void JavaThread::disable_stack_yellow_reserved_zone() {
2615 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2616 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2617
2618 // Simply return if called for a thread that does not use guard pages.
2619 if (_stack_guard_state == stack_guard_unused) return;
2620
2621 // The base notation is from the stacks point of view, growing downward.
2622 // We need to adjust it to work correctly with guard_memory()
2623 address base = stack_red_zone_base();
2624
2625 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2626 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2627 } else {
2628 warning("Attempt to unguard stack yellow zone failed.");
2629 }
2630 disable_register_stack_guard();
2631 }
2632
2633 void JavaThread::enable_stack_red_zone() {
2634 // The base notation is from the stacks point of view, growing downward.
2635 // We need to adjust it to work correctly with guard_memory()
2636 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2637 address base = stack_red_zone_base() - stack_red_zone_size();
2638
2639 guarantee(base < stack_base(), "Error calculating stack red zone");
2640 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2641
2642 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2643 warning("Attempt to guard stack red zone failed.");
2644 }
2645 }
2646
2647 void JavaThread::disable_stack_red_zone() {
2648 // The base notation is from the stacks point of view, growing downward.
2649 // We need to adjust it to work correctly with guard_memory()
2650 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2651 address base = stack_red_zone_base() - stack_red_zone_size();
2652 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2653 warning("Attempt to unguard stack red zone failed.");
2654 }
2655 }
2656
2657 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2658 // ignore is there is no stack
2659 if (!has_last_Java_frame()) return;
2660 // traverse the stack frames. Starts from top frame.
2661 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2662 frame* fr = fst.current();
2663 f(fr, fst.register_map());
2664 }
2665 }
2666
2667
2668 #ifndef PRODUCT
2669 // Deoptimization
2670 // Function for testing deoptimization
2671 void JavaThread::deoptimize() {
2672 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2673 StackFrameStream fst(this, UseBiasedLocking);
2674 bool deopt = false; // Dump stack only if a deopt actually happens.
2675 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2676 // Iterate over all frames in the thread and deoptimize
2677 for (; !fst.is_done(); fst.next()) {
2678 if (fst.current()->can_be_deoptimized()) {
2679
2680 if (only_at) {
2681 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2682 // consists of comma or carriage return separated numbers so
2683 // search for the current bci in that string.
2684 address pc = fst.current()->pc();
2685 nmethod* nm = (nmethod*) fst.current()->cb();
2686 ScopeDesc* sd = nm->scope_desc_at(pc);
2687 char buffer[8];
2688 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2689 size_t len = strlen(buffer);
2690 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2691 while (found != NULL) {
2692 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2693 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2694 // Check that the bci found is bracketed by terminators.
2695 break;
2696 }
2697 found = strstr(found + 1, buffer);
2698 }
2699 if (!found) {
2700 continue;
2701 }
2702 }
2703
2704 if (DebugDeoptimization && !deopt) {
2705 deopt = true; // One-time only print before deopt
2706 tty->print_cr("[BEFORE Deoptimization]");
2707 trace_frames();
2708 trace_stack();
2709 }
2710 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2711 }
2712 }
2713
2714 if (DebugDeoptimization && deopt) {
2715 tty->print_cr("[AFTER Deoptimization]");
2716 trace_frames();
2717 }
2718 }
2719
2720
2721 // Make zombies
2722 void JavaThread::make_zombies() {
2723 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2724 if (fst.current()->can_be_deoptimized()) {
2725 // it is a Java nmethod
2726 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2727 nm->make_not_entrant();
2728 }
2729 }
2730 }
2731 #endif // PRODUCT
2732
2733
2734 void JavaThread::deoptimized_wrt_marked_nmethods() {
2735 if (!has_last_Java_frame()) return;
2736 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2737 StackFrameStream fst(this, UseBiasedLocking);
2738 for (; !fst.is_done(); fst.next()) {
2739 if (fst.current()->should_be_deoptimized()) {
2740 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2741 }
2742 }
2743 }
2744
2745
2746 // If the caller is a NamedThread, then remember, in the current scope,
2747 // the given JavaThread in its _processed_thread field.
2748 class RememberProcessedThread: public StackObj {
2749 NamedThread* _cur_thr;
2750 public:
2751 RememberProcessedThread(JavaThread* jthr) {
2752 Thread* thread = Thread::current();
2753 if (thread->is_Named_thread()) {
2754 _cur_thr = (NamedThread *)thread;
2755 _cur_thr->set_processed_thread(jthr);
2756 } else {
2757 _cur_thr = NULL;
2758 }
2759 }
2760
2761 ~RememberProcessedThread() {
2762 if (_cur_thr) {
2763 _cur_thr->set_processed_thread(NULL);
2764 }
2765 }
2766 };
2767
2768 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2769 // Verify that the deferred card marks have been flushed.
2770 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2771
2772 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2773 // since there may be more than one thread using each ThreadProfiler.
2774
2775 // Traverse the GCHandles
2776 Thread::oops_do(f, cf);
2777
2778 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2779
2780 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2781 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2782
2783 if (has_last_Java_frame()) {
2784 // Record JavaThread to GC thread
2785 RememberProcessedThread rpt(this);
2786
2787 // Traverse the privileged stack
2788 if (_privileged_stack_top != NULL) {
2789 _privileged_stack_top->oops_do(f);
2790 }
2791
2792 // traverse the registered growable array
2793 if (_array_for_gc != NULL) {
2794 for (int index = 0; index < _array_for_gc->length(); index++) {
2795 f->do_oop(_array_for_gc->adr_at(index));
2796 }
2797 }
2798
2799 // Traverse the monitor chunks
2800 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2801 chunk->oops_do(f);
2802 }
2803
2804 // Traverse the execution stack
2805 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2806 fst.current()->oops_do(f, cf, fst.register_map());
2807 }
2808 }
2809
2810 // callee_target is never live across a gc point so NULL it here should
2811 // it still contain a methdOop.
2812
2813 set_callee_target(NULL);
2814
2815 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2816 // If we have deferred set_locals there might be oops waiting to be
2817 // written
2818 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2819 if (list != NULL) {
2820 for (int i = 0; i < list->length(); i++) {
2821 list->at(i)->oops_do(f);
2822 }
2823 }
2824
2825 // Traverse instance variables at the end since the GC may be moving things
2826 // around using this function
2827 f->do_oop((oop*) &_threadObj);
2828 f->do_oop((oop*) &_vm_result);
2829 f->do_oop((oop*) &_exception_oop);
2830 f->do_oop((oop*) &_pending_async_exception);
2831
2832 if (jvmti_thread_state() != NULL) {
2833 jvmti_thread_state()->oops_do(f);
2834 }
2835 }
2836
2837 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2838 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2839 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2840
2841 if (has_last_Java_frame()) {
2842 // Traverse the execution stack
2843 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2844 fst.current()->nmethods_do(cf);
2845 }
2846 }
2847 }
2848
2849 void JavaThread::metadata_do(void f(Metadata*)) {
2850 if (has_last_Java_frame()) {
2851 // Traverse the execution stack to call f() on the methods in the stack
2852 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2853 fst.current()->metadata_do(f);
2854 }
2855 } else if (is_Compiler_thread()) {
2856 // need to walk ciMetadata in current compile tasks to keep alive.
2857 CompilerThread* ct = (CompilerThread*)this;
2858 if (ct->env() != NULL) {
2859 ct->env()->metadata_do(f);
2860 }
2861 if (ct->task() != NULL) {
2862 ct->task()->metadata_do(f);
2863 }
2864 }
2865 }
2866
2867 // Printing
2868 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2869 switch (_thread_state) {
2870 case _thread_uninitialized: return "_thread_uninitialized";
2871 case _thread_new: return "_thread_new";
2872 case _thread_new_trans: return "_thread_new_trans";
2873 case _thread_in_native: return "_thread_in_native";
2874 case _thread_in_native_trans: return "_thread_in_native_trans";
2875 case _thread_in_vm: return "_thread_in_vm";
2876 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2877 case _thread_in_Java: return "_thread_in_Java";
2878 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2879 case _thread_blocked: return "_thread_blocked";
2880 case _thread_blocked_trans: return "_thread_blocked_trans";
2881 default: return "unknown thread state";
2882 }
2883 }
2884
2885 #ifndef PRODUCT
2886 void JavaThread::print_thread_state_on(outputStream *st) const {
2887 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2888 };
2889 void JavaThread::print_thread_state() const {
2890 print_thread_state_on(tty);
2891 }
2892 #endif // PRODUCT
2893
2894 // Called by Threads::print() for VM_PrintThreads operation
2895 void JavaThread::print_on(outputStream *st) const {
2896 st->print_raw("\"");
2897 st->print_raw(get_thread_name());
2898 st->print_raw("\" ");
2899 oop thread_oop = threadObj();
2900 if (thread_oop != NULL) {
2901 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2902 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2903 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2904 }
2905 Thread::print_on(st);
2906 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2907 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2908 if (thread_oop != NULL) {
2909 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2910 }
2911 #ifndef PRODUCT
2912 print_thread_state_on(st);
2913 _safepoint_state->print_on(st);
2914 #endif // PRODUCT
2915 if (is_Compiler_thread()) {
2916 CompilerThread* ct = (CompilerThread*)this;
2917 if (ct->task() != NULL) {
2918 st->print(" Compiling: ");
2919 ct->task()->print(st, NULL, true, false);
2920 } else {
2921 st->print(" No compile task");
2922 }
2923 st->cr();
2924 }
2925 }
2926
2927 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2928 st->print("%s", get_thread_name_string(buf, buflen));
2929 }
2930
2931 // Called by fatal error handler. The difference between this and
2932 // JavaThread::print() is that we can't grab lock or allocate memory.
2933 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2934 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2935 oop thread_obj = threadObj();
2936 if (thread_obj != NULL) {
2937 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2938 }
2939 st->print(" [");
2940 st->print("%s", _get_thread_state_name(_thread_state));
2941 if (osthread()) {
2942 st->print(", id=%d", osthread()->thread_id());
2943 }
2944 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2945 p2i(stack_end()), p2i(stack_base()));
2946 st->print("]");
2947 return;
2948 }
2949
2950 // Verification
2951
2952 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2953
2954 void JavaThread::verify() {
2955 // Verify oops in the thread.
2956 oops_do(&VerifyOopClosure::verify_oop, NULL);
2957
2958 // Verify the stack frames.
2959 frames_do(frame_verify);
2960 }
2961
2962 // CR 6300358 (sub-CR 2137150)
2963 // Most callers of this method assume that it can't return NULL but a
2964 // thread may not have a name whilst it is in the process of attaching to
2965 // the VM - see CR 6412693, and there are places where a JavaThread can be
2966 // seen prior to having it's threadObj set (eg JNI attaching threads and
2967 // if vm exit occurs during initialization). These cases can all be accounted
2968 // for such that this method never returns NULL.
2969 const char* JavaThread::get_thread_name() const {
2970 #ifdef ASSERT
2971 // early safepoints can hit while current thread does not yet have TLS
2972 if (!SafepointSynchronize::is_at_safepoint()) {
2973 Thread *cur = Thread::current();
2974 if (!(cur->is_Java_thread() && cur == this)) {
2975 // Current JavaThreads are allowed to get their own name without
2976 // the Threads_lock.
2977 assert_locked_or_safepoint(Threads_lock);
2978 }
2979 }
2980 #endif // ASSERT
2981 return get_thread_name_string();
2982 }
2983
2984 // Returns a non-NULL representation of this thread's name, or a suitable
2985 // descriptive string if there is no set name
2986 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2987 const char* name_str;
2988 oop thread_obj = threadObj();
2989 if (thread_obj != NULL) {
2990 oop name = java_lang_Thread::name(thread_obj);
2991 if (name != NULL) {
2992 if (buf == NULL) {
2993 name_str = java_lang_String::as_utf8_string(name);
2994 } else {
2995 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2996 }
2997 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2998 name_str = "<no-name - thread is attaching>";
2999 } else {
3000 name_str = Thread::name();
3001 }
3002 } else {
3003 name_str = Thread::name();
3004 }
3005 assert(name_str != NULL, "unexpected NULL thread name");
3006 return name_str;
3007 }
3008
3009
3010 const char* JavaThread::get_threadgroup_name() const {
3011 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3012 oop thread_obj = threadObj();
3013 if (thread_obj != NULL) {
3014 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3015 if (thread_group != NULL) {
3016 // ThreadGroup.name can be null
3017 return java_lang_ThreadGroup::name(thread_group);
3018 }
3019 }
3020 return NULL;
3021 }
3022
3023 const char* JavaThread::get_parent_name() const {
3024 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3025 oop thread_obj = threadObj();
3026 if (thread_obj != NULL) {
3027 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3028 if (thread_group != NULL) {
3029 oop parent = java_lang_ThreadGroup::parent(thread_group);
3030 if (parent != NULL) {
3031 // ThreadGroup.name can be null
3032 return java_lang_ThreadGroup::name(parent);
3033 }
3034 }
3035 }
3036 return NULL;
3037 }
3038
3039 ThreadPriority JavaThread::java_priority() const {
3040 oop thr_oop = threadObj();
3041 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3042 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3043 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3044 return priority;
3045 }
3046
3047 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3048
3049 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3050 // Link Java Thread object <-> C++ Thread
3051
3052 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3053 // and put it into a new Handle. The Handle "thread_oop" can then
3054 // be used to pass the C++ thread object to other methods.
3055
3056 // Set the Java level thread object (jthread) field of the
3057 // new thread (a JavaThread *) to C++ thread object using the
3058 // "thread_oop" handle.
3059
3060 // Set the thread field (a JavaThread *) of the
3061 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3062
3063 Handle thread_oop(Thread::current(),
3064 JNIHandles::resolve_non_null(jni_thread));
3065 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3066 "must be initialized");
3067 set_threadObj(thread_oop());
3068 java_lang_Thread::set_thread(thread_oop(), this);
3069
3070 if (prio == NoPriority) {
3071 prio = java_lang_Thread::priority(thread_oop());
3072 assert(prio != NoPriority, "A valid priority should be present");
3073 }
3074
3075 // Push the Java priority down to the native thread; needs Threads_lock
3076 Thread::set_priority(this, prio);
3077
3078 prepare_ext();
3079
3080 // Add the new thread to the Threads list and set it in motion.
3081 // We must have threads lock in order to call Threads::add.
3082 // It is crucial that we do not block before the thread is
3083 // added to the Threads list for if a GC happens, then the java_thread oop
3084 // will not be visited by GC.
3085 Threads::add(this);
3086 }
3087
3088 oop JavaThread::current_park_blocker() {
3089 // Support for JSR-166 locks
3090 oop thread_oop = threadObj();
3091 if (thread_oop != NULL &&
3092 JDK_Version::current().supports_thread_park_blocker()) {
3093 return java_lang_Thread::park_blocker(thread_oop);
3094 }
3095 return NULL;
3096 }
3097
3098
3099 void JavaThread::print_stack_on(outputStream* st) {
3100 if (!has_last_Java_frame()) return;
3101 ResourceMark rm;
3102 HandleMark hm;
3103
3104 RegisterMap reg_map(this);
3105 vframe* start_vf = last_java_vframe(®_map);
3106 int count = 0;
3107 for (vframe* f = start_vf; f; f = f->sender()) {
3108 if (f->is_java_frame()) {
3109 javaVFrame* jvf = javaVFrame::cast(f);
3110 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3111
3112 // Print out lock information
3113 if (JavaMonitorsInStackTrace) {
3114 jvf->print_lock_info_on(st, count);
3115 }
3116 } else {
3117 // Ignore non-Java frames
3118 }
3119
3120 // Bail-out case for too deep stacks
3121 count++;
3122 if (MaxJavaStackTraceDepth == count) return;
3123 }
3124 }
3125
3126
3127 // JVMTI PopFrame support
3128 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3129 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3130 if (in_bytes(size_in_bytes) != 0) {
3131 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3132 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3133 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3134 }
3135 }
3136
3137 void* JavaThread::popframe_preserved_args() {
3138 return _popframe_preserved_args;
3139 }
3140
3141 ByteSize JavaThread::popframe_preserved_args_size() {
3142 return in_ByteSize(_popframe_preserved_args_size);
3143 }
3144
3145 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3146 int sz = in_bytes(popframe_preserved_args_size());
3147 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3148 return in_WordSize(sz / wordSize);
3149 }
3150
3151 void JavaThread::popframe_free_preserved_args() {
3152 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3153 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3154 _popframe_preserved_args = NULL;
3155 _popframe_preserved_args_size = 0;
3156 }
3157
3158 #ifndef PRODUCT
3159
3160 void JavaThread::trace_frames() {
3161 tty->print_cr("[Describe stack]");
3162 int frame_no = 1;
3163 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3164 tty->print(" %d. ", frame_no++);
3165 fst.current()->print_value_on(tty, this);
3166 tty->cr();
3167 }
3168 }
3169
3170 class PrintAndVerifyOopClosure: public OopClosure {
3171 protected:
3172 template <class T> inline void do_oop_work(T* p) {
3173 oop obj = oopDesc::load_decode_heap_oop(p);
3174 if (obj == NULL) return;
3175 tty->print(INTPTR_FORMAT ": ", p2i(p));
3176 if (obj->is_oop_or_null()) {
3177 if (obj->is_objArray()) {
3178 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3179 } else {
3180 obj->print();
3181 }
3182 } else {
3183 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3184 }
3185 tty->cr();
3186 }
3187 public:
3188 virtual void do_oop(oop* p) { do_oop_work(p); }
3189 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3190 };
3191
3192
3193 static void oops_print(frame* f, const RegisterMap *map) {
3194 PrintAndVerifyOopClosure print;
3195 f->print_value();
3196 f->oops_do(&print, NULL, (RegisterMap*)map);
3197 }
3198
3199 // Print our all the locations that contain oops and whether they are
3200 // valid or not. This useful when trying to find the oldest frame
3201 // where an oop has gone bad since the frame walk is from youngest to
3202 // oldest.
3203 void JavaThread::trace_oops() {
3204 tty->print_cr("[Trace oops]");
3205 frames_do(oops_print);
3206 }
3207
3208
3209 #ifdef ASSERT
3210 // Print or validate the layout of stack frames
3211 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3212 ResourceMark rm;
3213 PRESERVE_EXCEPTION_MARK;
3214 FrameValues values;
3215 int frame_no = 0;
3216 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3217 fst.current()->describe(values, ++frame_no);
3218 if (depth == frame_no) break;
3219 }
3220 if (validate_only) {
3221 values.validate();
3222 } else {
3223 tty->print_cr("[Describe stack layout]");
3224 values.print(this);
3225 }
3226 }
3227 #endif
3228
3229 void JavaThread::trace_stack_from(vframe* start_vf) {
3230 ResourceMark rm;
3231 int vframe_no = 1;
3232 for (vframe* f = start_vf; f; f = f->sender()) {
3233 if (f->is_java_frame()) {
3234 javaVFrame::cast(f)->print_activation(vframe_no++);
3235 } else {
3236 f->print();
3237 }
3238 if (vframe_no > StackPrintLimit) {
3239 tty->print_cr("...<more frames>...");
3240 return;
3241 }
3242 }
3243 }
3244
3245
3246 void JavaThread::trace_stack() {
3247 if (!has_last_Java_frame()) return;
3248 ResourceMark rm;
3249 HandleMark hm;
3250 RegisterMap reg_map(this);
3251 trace_stack_from(last_java_vframe(®_map));
3252 }
3253
3254
3255 #endif // PRODUCT
3256
3257
3258 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3259 assert(reg_map != NULL, "a map must be given");
3260 frame f = last_frame();
3261 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3262 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3263 }
3264 return NULL;
3265 }
3266
3267
3268 Klass* JavaThread::security_get_caller_class(int depth) {
3269 vframeStream vfst(this);
3270 vfst.security_get_caller_frame(depth);
3271 if (!vfst.at_end()) {
3272 return vfst.method()->method_holder();
3273 }
3274 return NULL;
3275 }
3276
3277 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3278 assert(thread->is_Compiler_thread(), "must be compiler thread");
3279 CompileBroker::compiler_thread_loop();
3280 }
3281
3282 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3283 NMethodSweeper::sweeper_loop();
3284 }
3285
3286 // Create a CompilerThread
3287 CompilerThread::CompilerThread(CompileQueue* queue,
3288 CompilerCounters* counters)
3289 : JavaThread(&compiler_thread_entry) {
3290 _env = NULL;
3291 _log = NULL;
3292 _task = NULL;
3293 _queue = queue;
3294 _counters = counters;
3295 _buffer_blob = NULL;
3296 _compiler = NULL;
3297
3298 #ifndef PRODUCT
3299 _ideal_graph_printer = NULL;
3300 #endif
3301 }
3302
3303 bool CompilerThread::can_call_java() const {
3304 return _compiler != NULL && _compiler->is_jvmci();
3305 }
3306
3307 // Create sweeper thread
3308 CodeCacheSweeperThread::CodeCacheSweeperThread()
3309 : JavaThread(&sweeper_thread_entry) {
3310 _scanned_compiled_method = NULL;
3311 }
3312
3313 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3314 JavaThread::oops_do(f, cf);
3315 if (_scanned_compiled_method != NULL && cf != NULL) {
3316 // Safepoints can occur when the sweeper is scanning an nmethod so
3317 // process it here to make sure it isn't unloaded in the middle of
3318 // a scan.
3319 cf->do_code_blob(_scanned_compiled_method);
3320 }
3321 }
3322
3323 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3324 JavaThread::nmethods_do(cf);
3325 if (_scanned_compiled_method != NULL && cf != NULL) {
3326 // Safepoints can occur when the sweeper is scanning an nmethod so
3327 // process it here to make sure it isn't unloaded in the middle of
3328 // a scan.
3329 cf->do_code_blob(_scanned_compiled_method);
3330 }
3331 }
3332
3333
3334 // ======= Threads ========
3335
3336 // The Threads class links together all active threads, and provides
3337 // operations over all threads. It is protected by its own Mutex
3338 // lock, which is also used in other contexts to protect thread
3339 // operations from having the thread being operated on from exiting
3340 // and going away unexpectedly (e.g., safepoint synchronization)
3341
3342 JavaThread* Threads::_thread_list = NULL;
3343 int Threads::_number_of_threads = 0;
3344 int Threads::_number_of_non_daemon_threads = 0;
3345 int Threads::_return_code = 0;
3346 int Threads::_thread_claim_parity = 0;
3347 size_t JavaThread::_stack_size_at_create = 0;
3348 #ifdef ASSERT
3349 bool Threads::_vm_complete = false;
3350 #endif
3351
3352 // All JavaThreads
3353 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3354
3355 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3356 void Threads::threads_do(ThreadClosure* tc) {
3357 assert_locked_or_safepoint(Threads_lock);
3358 // ALL_JAVA_THREADS iterates through all JavaThreads
3359 ALL_JAVA_THREADS(p) {
3360 tc->do_thread(p);
3361 }
3362 // Someday we could have a table or list of all non-JavaThreads.
3363 // For now, just manually iterate through them.
3364 tc->do_thread(VMThread::vm_thread());
3365 Universe::heap()->gc_threads_do(tc);
3366 WatcherThread *wt = WatcherThread::watcher_thread();
3367 // Strictly speaking, the following NULL check isn't sufficient to make sure
3368 // the data for WatcherThread is still valid upon being examined. However,
3369 // considering that WatchThread terminates when the VM is on the way to
3370 // exit at safepoint, the chance of the above is extremely small. The right
3371 // way to prevent termination of WatcherThread would be to acquire
3372 // Terminator_lock, but we can't do that without violating the lock rank
3373 // checking in some cases.
3374 if (wt != NULL) {
3375 tc->do_thread(wt);
3376 }
3377
3378 // If CompilerThreads ever become non-JavaThreads, add them here
3379 }
3380
3381 // The system initialization in the library has three phases.
3382 //
3383 // Phase 1: java.lang.System class initialization
3384 // java.lang.System is a primordial class loaded and initialized
3385 // by the VM early during startup. java.lang.System.<clinit>
3386 // only does registerNatives and keeps the rest of the class
3387 // initialization work later until thread initialization completes.
3388 //
3389 // System.initPhase1 initializes the system properties, the static
3390 // fields in, out, and err. Set up java signal handlers, OS-specific
3391 // system settings, and thread group of the main thread.
3392 static void call_initPhase1(TRAPS) {
3393 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
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* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3414
3415 JavaValue result(T_INT);
3416 JavaCallArguments args;
3417 args.push_int(DisplayVMOutputToStderr);
3418 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3419 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3420 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3421 if (result.get_jint() != JNI_OK) {
3422 vm_exit_during_initialization(); // no message or exception
3423 }
3424
3425 universe_post_module_init();
3426 }
3427
3428 // Phase 3. final setup - set security manager, system class loader and TCCL
3429 //
3430 // This will instantiate and set the security manager, set the system class
3431 // loader as well as the thread context class loader. The security manager
3432 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3433 // other modules or the application's classpath.
3434 static void call_initPhase3(TRAPS) {
3435 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3436 JavaValue result(T_VOID);
3437 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3438 vmSymbols::void_method_signature(), CHECK);
3439 }
3440
3441 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3442 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3443
3444 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3445 create_vm_init_libraries();
3446 }
3447
3448 initialize_class(vmSymbols::java_lang_String(), CHECK);
3449
3450 // Inject CompactStrings value after the static initializers for String ran.
3451 java_lang_String::set_compact_strings(CompactStrings);
3452
3453 // Initialize java_lang.System (needed before creating the thread)
3454 initialize_class(vmSymbols::java_lang_System(), CHECK);
3455 // The VM creates & returns objects of this class. Make sure it's initialized.
3456 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3457 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3458 Handle thread_group = create_initial_thread_group(CHECK);
3459 Universe::set_main_thread_group(thread_group());
3460 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3461 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3462 main_thread->set_threadObj(thread_object);
3463 // Set thread status to running since main thread has
3464 // been started and running.
3465 java_lang_Thread::set_thread_status(thread_object,
3466 java_lang_Thread::RUNNABLE);
3467
3468 // The VM creates objects of this class.
3469 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3470
3471 // The VM preresolves methods to these classes. Make sure that they get initialized
3472 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3473 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3474
3475 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3476 call_initPhase1(CHECK);
3477
3478 // get the Java runtime name after java.lang.System is initialized
3479 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3480 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3481
3482 // an instance of OutOfMemory exception has been allocated earlier
3483 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3484 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3485 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3486 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3487 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3488 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3489 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3490 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3491 }
3492
3493 void Threads::initialize_jsr292_core_classes(TRAPS) {
3494 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3495
3496 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3497 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3498 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3499 }
3500
3501 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3502 extern void JDK_Version_init();
3503
3504 // Preinitialize version info.
3505 VM_Version::early_initialize();
3506
3507 // Check version
3508 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3509
3510 // Initialize library-based TLS
3511 ThreadLocalStorage::init();
3512
3513 // Initialize the output stream module
3514 ostream_init();
3515
3516 // Process java launcher properties.
3517 Arguments::process_sun_java_launcher_properties(args);
3518
3519 // Initialize the os module
3520 os::init();
3521
3522 // Record VM creation timing statistics
3523 TraceVmCreationTime create_vm_timer;
3524 create_vm_timer.start();
3525
3526 // Initialize system properties.
3527 Arguments::init_system_properties();
3528
3529 // So that JDK version can be used as a discriminator when parsing arguments
3530 JDK_Version_init();
3531
3532 // Update/Initialize System properties after JDK version number is known
3533 Arguments::init_version_specific_system_properties();
3534
3535 // Make sure to initialize log configuration *before* parsing arguments
3536 LogConfiguration::initialize(create_vm_timer.begin_time());
3537
3538 // Parse arguments
3539 jint parse_result = Arguments::parse(args);
3540 if (parse_result != JNI_OK) return parse_result;
3541
3542 os::init_before_ergo();
3543
3544 jint ergo_result = Arguments::apply_ergo();
3545 if (ergo_result != JNI_OK) return ergo_result;
3546
3547 // Final check of all ranges after ergonomics which may change values.
3548 if (!CommandLineFlagRangeList::check_ranges()) {
3549 return JNI_EINVAL;
3550 }
3551
3552 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3553 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3554 if (!constraint_result) {
3555 return JNI_EINVAL;
3556 }
3557
3558 CommandLineFlagWriteableList::mark_startup();
3559
3560 if (PauseAtStartup) {
3561 os::pause();
3562 }
3563
3564 HOTSPOT_VM_INIT_BEGIN();
3565
3566 // Timing (must come after argument parsing)
3567 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3568
3569 // Initialize the os module after parsing the args
3570 jint os_init_2_result = os::init_2();
3571 if (os_init_2_result != JNI_OK) return os_init_2_result;
3572
3573 jint adjust_after_os_result = Arguments::adjust_after_os();
3574 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3575
3576 // Initialize output stream logging
3577 ostream_init_log();
3578
3579 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3580 // Must be before create_vm_init_agents()
3581 if (Arguments::init_libraries_at_startup()) {
3582 convert_vm_init_libraries_to_agents();
3583 }
3584
3585 // Launch -agentlib/-agentpath and converted -Xrun agents
3586 if (Arguments::init_agents_at_startup()) {
3587 create_vm_init_agents();
3588 }
3589
3590 // Initialize Threads state
3591 _thread_list = NULL;
3592 _number_of_threads = 0;
3593 _number_of_non_daemon_threads = 0;
3594
3595 // Initialize global data structures and create system classes in heap
3596 vm_init_globals();
3597
3598 #if INCLUDE_JVMCI
3599 if (JVMCICounterSize > 0) {
3600 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3601 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3602 } else {
3603 JavaThread::_jvmci_old_thread_counters = NULL;
3604 }
3605 #endif // INCLUDE_JVMCI
3606
3607 // Attach the main thread to this os thread
3608 JavaThread* main_thread = new JavaThread();
3609 main_thread->set_thread_state(_thread_in_vm);
3610 main_thread->initialize_thread_current();
3611 // must do this before set_active_handles
3612 main_thread->record_stack_base_and_size();
3613 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3614
3615 if (!main_thread->set_as_starting_thread()) {
3616 vm_shutdown_during_initialization(
3617 "Failed necessary internal allocation. Out of swap space");
3618 delete main_thread;
3619 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3620 return JNI_ENOMEM;
3621 }
3622
3623 // Enable guard page *after* os::create_main_thread(), otherwise it would
3624 // crash Linux VM, see notes in os_linux.cpp.
3625 main_thread->create_stack_guard_pages();
3626
3627 // Initialize Java-Level synchronization subsystem
3628 ObjectMonitor::Initialize();
3629
3630 // Initialize global modules
3631 jint status = init_globals();
3632 if (status != JNI_OK) {
3633 delete main_thread;
3634 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3635 return status;
3636 }
3637
3638 if (TRACE_INITIALIZE() != JNI_OK) {
3639 vm_exit_during_initialization("Failed to initialize tracing backend");
3640 }
3641
3642 // Should be done after the heap is fully created
3643 main_thread->cache_global_variables();
3644
3645 HandleMark hm;
3646
3647 { MutexLocker mu(Threads_lock);
3648 Threads::add(main_thread);
3649 }
3650
3651 // Any JVMTI raw monitors entered in onload will transition into
3652 // real raw monitor. VM is setup enough here for raw monitor enter.
3653 JvmtiExport::transition_pending_onload_raw_monitors();
3654
3655 // Create the VMThread
3656 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3657
3658 VMThread::create();
3659 Thread* vmthread = VMThread::vm_thread();
3660
3661 if (!os::create_thread(vmthread, os::vm_thread)) {
3662 vm_exit_during_initialization("Cannot create VM thread. "
3663 "Out of system resources.");
3664 }
3665
3666 // Wait for the VM thread to become ready, and VMThread::run to initialize
3667 // Monitors can have spurious returns, must always check another state flag
3668 {
3669 MutexLocker ml(Notify_lock);
3670 os::start_thread(vmthread);
3671 while (vmthread->active_handles() == NULL) {
3672 Notify_lock->wait();
3673 }
3674 }
3675 }
3676
3677 assert(Universe::is_fully_initialized(), "not initialized");
3678 if (VerifyDuringStartup) {
3679 // Make sure we're starting with a clean slate.
3680 VM_Verify verify_op;
3681 VMThread::execute(&verify_op);
3682 }
3683
3684 Thread* THREAD = Thread::current();
3685
3686 // At this point, the Universe is initialized, but we have not executed
3687 // any byte code. Now is a good time (the only time) to dump out the
3688 // internal state of the JVM for sharing.
3689 if (DumpSharedSpaces) {
3690 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3691 ShouldNotReachHere();
3692 }
3693
3694 // Always call even when there are not JVMTI environments yet, since environments
3695 // may be attached late and JVMTI must track phases of VM execution
3696 JvmtiExport::enter_early_start_phase();
3697
3698 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3699 JvmtiExport::post_early_vm_start();
3700
3701 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3702
3703 // We need this for ClassDataSharing - the initial vm.info property is set
3704 // with the default value of CDS "sharing" which may be reset through
3705 // command line options.
3706 reset_vm_info_property(CHECK_JNI_ERR);
3707
3708 quicken_jni_functions();
3709
3710 // No more stub generation allowed after that point.
3711 StubCodeDesc::freeze();
3712
3713 // Set flag that basic initialization has completed. Used by exceptions and various
3714 // debug stuff, that does not work until all basic classes have been initialized.
3715 set_init_completed();
3716
3717 LogConfiguration::post_initialize();
3718 Metaspace::post_initialize();
3719
3720 HOTSPOT_VM_INIT_END();
3721
3722 // record VM initialization completion time
3723 #if INCLUDE_MANAGEMENT
3724 Management::record_vm_init_completed();
3725 #endif // INCLUDE_MANAGEMENT
3726
3727 // Signal Dispatcher needs to be started before VMInit event is posted
3728 os::signal_init(CHECK_JNI_ERR);
3729
3730 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3731 if (!DisableAttachMechanism) {
3732 AttachListener::vm_start();
3733 if (StartAttachListener || AttachListener::init_at_startup()) {
3734 AttachListener::init();
3735 }
3736 }
3737
3738 // Launch -Xrun agents
3739 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3740 // back-end can launch with -Xdebug -Xrunjdwp.
3741 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3742 create_vm_init_libraries();
3743 }
3744
3745 if (CleanChunkPoolAsync) {
3746 Chunk::start_chunk_pool_cleaner_task();
3747 }
3748
3749 // initialize compiler(s)
3750 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3751 CompileBroker::compilation_init(CHECK_JNI_ERR);
3752 #endif
3753
3754 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3755 // It is done after compilers are initialized, because otherwise compilations of
3756 // signature polymorphic MH intrinsics can be missed
3757 // (see SystemDictionary::find_method_handle_intrinsic).
3758 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3759
3760 // This will initialize the module system. Only java.base classes can be
3761 // loaded until phase 2 completes
3762 call_initPhase2(CHECK_JNI_ERR);
3763
3764 // Always call even when there are not JVMTI environments yet, since environments
3765 // may be attached late and JVMTI must track phases of VM execution
3766 JvmtiExport::enter_start_phase();
3767
3768 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3769 JvmtiExport::post_vm_start();
3770
3771 // Final system initialization including security manager and system class loader
3772 call_initPhase3(CHECK_JNI_ERR);
3773
3774 // cache the system class loader
3775 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3776
3777 #if INCLUDE_JVMCI
3778 if (EnableJVMCI) {
3779 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3780 // The JVMCI Java initialization code will read this flag and
3781 // do the printing if it's set.
3782 bool init = JVMCIPrintProperties;
3783
3784 if (!init) {
3785 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3786 // compilations via JVMCI will not actually block until JVMCI is initialized.
3787 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3788 }
3789
3790 if (init) {
3791 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3792 }
3793 }
3794 #endif
3795
3796 // Always call even when there are not JVMTI environments yet, since environments
3797 // may be attached late and JVMTI must track phases of VM execution
3798 JvmtiExport::enter_live_phase();
3799
3800 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3801 JvmtiExport::post_vm_initialized();
3802
3803 if (TRACE_START() != JNI_OK) {
3804 vm_exit_during_initialization("Failed to start tracing backend.");
3805 }
3806
3807 #if INCLUDE_MANAGEMENT
3808 Management::initialize(THREAD);
3809
3810 if (HAS_PENDING_EXCEPTION) {
3811 // management agent fails to start possibly due to
3812 // configuration problem and is responsible for printing
3813 // stack trace if appropriate. Simply exit VM.
3814 vm_exit(1);
3815 }
3816 #endif // INCLUDE_MANAGEMENT
3817
3818 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3819 if (MemProfiling) MemProfiler::engage();
3820 StatSampler::engage();
3821 if (CheckJNICalls) JniPeriodicChecker::engage();
3822
3823 BiasedLocking::init();
3824
3825 #if INCLUDE_RTM_OPT
3826 RTMLockingCounters::init();
3827 #endif
3828
3829 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3830 call_postVMInitHook(THREAD);
3831 // The Java side of PostVMInitHook.run must deal with all
3832 // exceptions and provide means of diagnosis.
3833 if (HAS_PENDING_EXCEPTION) {
3834 CLEAR_PENDING_EXCEPTION;
3835 }
3836 }
3837
3838 {
3839 MutexLocker ml(PeriodicTask_lock);
3840 // Make sure the WatcherThread can be started by WatcherThread::start()
3841 // or by dynamic enrollment.
3842 WatcherThread::make_startable();
3843 // Start up the WatcherThread if there are any periodic tasks
3844 // NOTE: All PeriodicTasks should be registered by now. If they
3845 // aren't, late joiners might appear to start slowly (we might
3846 // take a while to process their first tick).
3847 if (PeriodicTask::num_tasks() > 0) {
3848 WatcherThread::start();
3849 }
3850 }
3851
3852 create_vm_timer.end();
3853 #ifdef ASSERT
3854 _vm_complete = true;
3855 #endif
3856 return JNI_OK;
3857 }
3858
3859 // type for the Agent_OnLoad and JVM_OnLoad entry points
3860 extern "C" {
3861 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3862 }
3863 // Find a command line agent library and return its entry point for
3864 // -agentlib: -agentpath: -Xrun
3865 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3866 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3867 const char *on_load_symbols[],
3868 size_t num_symbol_entries) {
3869 OnLoadEntry_t on_load_entry = NULL;
3870 void *library = NULL;
3871
3872 if (!agent->valid()) {
3873 char buffer[JVM_MAXPATHLEN];
3874 char ebuf[1024] = "";
3875 const char *name = agent->name();
3876 const char *msg = "Could not find agent library ";
3877
3878 // First check to see if agent is statically linked into executable
3879 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3880 library = agent->os_lib();
3881 } else if (agent->is_absolute_path()) {
3882 library = os::dll_load(name, ebuf, sizeof ebuf);
3883 if (library == NULL) {
3884 const char *sub_msg = " in absolute path, with error: ";
3885 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3886 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3887 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3888 // If we can't find the agent, exit.
3889 vm_exit_during_initialization(buf, NULL);
3890 FREE_C_HEAP_ARRAY(char, buf);
3891 }
3892 } else {
3893 // Try to load the agent from the standard dll directory
3894 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3895 name)) {
3896 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3897 }
3898 if (library == NULL) { // Try the local directory
3899 char ns[1] = {0};
3900 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3901 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3902 }
3903 if (library == NULL) {
3904 const char *sub_msg = " on the library path, with error: ";
3905 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3906 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3907 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3908 // If we can't find the agent, exit.
3909 vm_exit_during_initialization(buf, NULL);
3910 FREE_C_HEAP_ARRAY(char, buf);
3911 }
3912 }
3913 }
3914 agent->set_os_lib(library);
3915 agent->set_valid();
3916 }
3917
3918 // Find the OnLoad function.
3919 on_load_entry =
3920 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3921 false,
3922 on_load_symbols,
3923 num_symbol_entries));
3924 return on_load_entry;
3925 }
3926
3927 // Find the JVM_OnLoad entry point
3928 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3929 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3930 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3931 }
3932
3933 // Find the Agent_OnLoad entry point
3934 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3935 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3936 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3937 }
3938
3939 // For backwards compatibility with -Xrun
3940 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3941 // treated like -agentpath:
3942 // Must be called before agent libraries are created
3943 void Threads::convert_vm_init_libraries_to_agents() {
3944 AgentLibrary* agent;
3945 AgentLibrary* next;
3946
3947 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3948 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3949 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3950
3951 // If there is an JVM_OnLoad function it will get called later,
3952 // otherwise see if there is an Agent_OnLoad
3953 if (on_load_entry == NULL) {
3954 on_load_entry = lookup_agent_on_load(agent);
3955 if (on_load_entry != NULL) {
3956 // switch it to the agent list -- so that Agent_OnLoad will be called,
3957 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3958 Arguments::convert_library_to_agent(agent);
3959 } else {
3960 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3961 }
3962 }
3963 }
3964 }
3965
3966 // Create agents for -agentlib: -agentpath: and converted -Xrun
3967 // Invokes Agent_OnLoad
3968 // Called very early -- before JavaThreads exist
3969 void Threads::create_vm_init_agents() {
3970 extern struct JavaVM_ main_vm;
3971 AgentLibrary* agent;
3972
3973 JvmtiExport::enter_onload_phase();
3974
3975 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3976 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3977
3978 if (on_load_entry != NULL) {
3979 // Invoke the Agent_OnLoad function
3980 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3981 if (err != JNI_OK) {
3982 vm_exit_during_initialization("agent library failed to init", agent->name());
3983 }
3984 } else {
3985 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3986 }
3987 }
3988 JvmtiExport::enter_primordial_phase();
3989 }
3990
3991 extern "C" {
3992 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3993 }
3994
3995 void Threads::shutdown_vm_agents() {
3996 // Send any Agent_OnUnload notifications
3997 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3998 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3999 extern struct JavaVM_ main_vm;
4000 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4001
4002 // Find the Agent_OnUnload function.
4003 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4004 os::find_agent_function(agent,
4005 false,
4006 on_unload_symbols,
4007 num_symbol_entries));
4008
4009 // Invoke the Agent_OnUnload function
4010 if (unload_entry != NULL) {
4011 JavaThread* thread = JavaThread::current();
4012 ThreadToNativeFromVM ttn(thread);
4013 HandleMark hm(thread);
4014 (*unload_entry)(&main_vm);
4015 }
4016 }
4017 }
4018
4019 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4020 // Invokes JVM_OnLoad
4021 void Threads::create_vm_init_libraries() {
4022 extern struct JavaVM_ main_vm;
4023 AgentLibrary* agent;
4024
4025 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4026 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4027
4028 if (on_load_entry != NULL) {
4029 // Invoke the JVM_OnLoad function
4030 JavaThread* thread = JavaThread::current();
4031 ThreadToNativeFromVM ttn(thread);
4032 HandleMark hm(thread);
4033 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4034 if (err != JNI_OK) {
4035 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4036 }
4037 } else {
4038 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4039 }
4040 }
4041 }
4042
4043 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4044 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4045
4046 JavaThread* java_thread = NULL;
4047 // Sequential search for now. Need to do better optimization later.
4048 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4049 oop tobj = thread->threadObj();
4050 if (!thread->is_exiting() &&
4051 tobj != NULL &&
4052 java_tid == java_lang_Thread::thread_id(tobj)) {
4053 java_thread = thread;
4054 break;
4055 }
4056 }
4057 return java_thread;
4058 }
4059
4060
4061 // Last thread running calls java.lang.Shutdown.shutdown()
4062 void JavaThread::invoke_shutdown_hooks() {
4063 HandleMark hm(this);
4064
4065 // We could get here with a pending exception, if so clear it now.
4066 if (this->has_pending_exception()) {
4067 this->clear_pending_exception();
4068 }
4069
4070 EXCEPTION_MARK;
4071 Klass* shutdown_klass =
4072 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4073 THREAD);
4074 if (shutdown_klass != NULL) {
4075 // SystemDictionary::resolve_or_null will return null if there was
4076 // an exception. If we cannot load the Shutdown class, just don't
4077 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4078 // and finalizers (if runFinalizersOnExit is set) won't be run.
4079 // Note that if a shutdown hook was registered or runFinalizersOnExit
4080 // was called, the Shutdown class would have already been loaded
4081 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4082 JavaValue result(T_VOID);
4083 JavaCalls::call_static(&result,
4084 shutdown_klass,
4085 vmSymbols::shutdown_method_name(),
4086 vmSymbols::void_method_signature(),
4087 THREAD);
4088 }
4089 CLEAR_PENDING_EXCEPTION;
4090 }
4091
4092 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4093 // the program falls off the end of main(). Another VM exit path is through
4094 // vm_exit() when the program calls System.exit() to return a value or when
4095 // there is a serious error in VM. The two shutdown paths are not exactly
4096 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4097 // and VM_Exit op at VM level.
4098 //
4099 // Shutdown sequence:
4100 // + Shutdown native memory tracking if it is on
4101 // + Wait until we are the last non-daemon thread to execute
4102 // <-- every thing is still working at this moment -->
4103 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4104 // shutdown hooks, run finalizers if finalization-on-exit
4105 // + Call before_exit(), prepare for VM exit
4106 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4107 // currently the only user of this mechanism is File.deleteOnExit())
4108 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4109 // post thread end and vm death events to JVMTI,
4110 // stop signal thread
4111 // + Call JavaThread::exit(), it will:
4112 // > release JNI handle blocks, remove stack guard pages
4113 // > remove this thread from Threads list
4114 // <-- no more Java code from this thread after this point -->
4115 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4116 // the compiler threads at safepoint
4117 // <-- do not use anything that could get blocked by Safepoint -->
4118 // + Disable tracing at JNI/JVM barriers
4119 // + Set _vm_exited flag for threads that are still running native code
4120 // + Delete this thread
4121 // + Call exit_globals()
4122 // > deletes tty
4123 // > deletes PerfMemory resources
4124 // + Return to caller
4125
4126 bool Threads::destroy_vm() {
4127 JavaThread* thread = JavaThread::current();
4128
4129 #ifdef ASSERT
4130 _vm_complete = false;
4131 #endif
4132 // Wait until we are the last non-daemon thread to execute
4133 { MutexLocker nu(Threads_lock);
4134 while (Threads::number_of_non_daemon_threads() > 1)
4135 // This wait should make safepoint checks, wait without a timeout,
4136 // and wait as a suspend-equivalent condition.
4137 //
4138 // Note: If the FlatProfiler is running and this thread is waiting
4139 // for another non-daemon thread to finish, then the FlatProfiler
4140 // is waiting for the external suspend request on this thread to
4141 // complete. wait_for_ext_suspend_completion() will eventually
4142 // timeout, but that takes time. Making this wait a suspend-
4143 // equivalent condition solves that timeout problem.
4144 //
4145 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4146 Mutex::_as_suspend_equivalent_flag);
4147 }
4148
4149 // Hang forever on exit if we are reporting an error.
4150 if (ShowMessageBoxOnError && is_error_reported()) {
4151 os::infinite_sleep();
4152 }
4153 os::wait_for_keypress_at_exit();
4154
4155 // run Java level shutdown hooks
4156 thread->invoke_shutdown_hooks();
4157
4158 before_exit(thread);
4159
4160 thread->exit(true);
4161
4162 // Stop VM thread.
4163 {
4164 // 4945125 The vm thread comes to a safepoint during exit.
4165 // GC vm_operations can get caught at the safepoint, and the
4166 // heap is unparseable if they are caught. Grab the Heap_lock
4167 // to prevent this. The GC vm_operations will not be able to
4168 // queue until after the vm thread is dead. After this point,
4169 // we'll never emerge out of the safepoint before the VM exits.
4170
4171 MutexLocker ml(Heap_lock);
4172
4173 VMThread::wait_for_vm_thread_exit();
4174 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4175 VMThread::destroy();
4176 }
4177
4178 // clean up ideal graph printers
4179 #if defined(COMPILER2) && !defined(PRODUCT)
4180 IdealGraphPrinter::clean_up();
4181 #endif
4182
4183 // Now, all Java threads are gone except daemon threads. Daemon threads
4184 // running Java code or in VM are stopped by the Safepoint. However,
4185 // daemon threads executing native code are still running. But they
4186 // will be stopped at native=>Java/VM barriers. Note that we can't
4187 // simply kill or suspend them, as it is inherently deadlock-prone.
4188
4189 VM_Exit::set_vm_exited();
4190
4191 notify_vm_shutdown();
4192
4193 delete thread;
4194
4195 #if INCLUDE_JVMCI
4196 if (JVMCICounterSize > 0) {
4197 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4198 }
4199 #endif
4200
4201 // exit_globals() will delete tty
4202 exit_globals();
4203
4204 LogConfiguration::finalize();
4205
4206 return true;
4207 }
4208
4209
4210 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4211 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4212 return is_supported_jni_version(version);
4213 }
4214
4215
4216 jboolean Threads::is_supported_jni_version(jint version) {
4217 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4218 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4219 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4220 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4221 if (version == JNI_VERSION_9) return JNI_TRUE;
4222 return JNI_FALSE;
4223 }
4224
4225
4226 void Threads::add(JavaThread* p, bool force_daemon) {
4227 // The threads lock must be owned at this point
4228 assert_locked_or_safepoint(Threads_lock);
4229
4230 // See the comment for this method in thread.hpp for its purpose and
4231 // why it is called here.
4232 p->initialize_queues();
4233 p->set_next(_thread_list);
4234 _thread_list = p;
4235 _number_of_threads++;
4236 oop threadObj = p->threadObj();
4237 bool daemon = true;
4238 // Bootstrapping problem: threadObj can be null for initial
4239 // JavaThread (or for threads attached via JNI)
4240 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4241 _number_of_non_daemon_threads++;
4242 daemon = false;
4243 }
4244
4245 ThreadService::add_thread(p, daemon);
4246
4247 // Possible GC point.
4248 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4249 }
4250
4251 void Threads::remove(JavaThread* p) {
4252 // Extra scope needed for Thread_lock, so we can check
4253 // that we do not remove thread without safepoint code notice
4254 { MutexLocker ml(Threads_lock);
4255
4256 assert(includes(p), "p must be present");
4257
4258 JavaThread* current = _thread_list;
4259 JavaThread* prev = NULL;
4260
4261 while (current != p) {
4262 prev = current;
4263 current = current->next();
4264 }
4265
4266 if (prev) {
4267 prev->set_next(current->next());
4268 } else {
4269 _thread_list = p->next();
4270 }
4271 _number_of_threads--;
4272 oop threadObj = p->threadObj();
4273 bool daemon = true;
4274 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4275 _number_of_non_daemon_threads--;
4276 daemon = false;
4277
4278 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4279 // on destroy_vm will wake up.
4280 if (number_of_non_daemon_threads() == 1) {
4281 Threads_lock->notify_all();
4282 }
4283 }
4284 ThreadService::remove_thread(p, daemon);
4285
4286 // Make sure that safepoint code disregard this thread. This is needed since
4287 // the thread might mess around with locks after this point. This can cause it
4288 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4289 // of this thread since it is removed from the queue.
4290 p->set_terminated_value();
4291 } // unlock Threads_lock
4292
4293 // Since Events::log uses a lock, we grab it outside the Threads_lock
4294 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4295 }
4296
4297 // Threads_lock must be held when this is called (or must be called during a safepoint)
4298 bool Threads::includes(JavaThread* p) {
4299 assert(Threads_lock->is_locked(), "sanity check");
4300 ALL_JAVA_THREADS(q) {
4301 if (q == p) {
4302 return true;
4303 }
4304 }
4305 return false;
4306 }
4307
4308 // Operations on the Threads list for GC. These are not explicitly locked,
4309 // but the garbage collector must provide a safe context for them to run.
4310 // In particular, these things should never be called when the Threads_lock
4311 // is held by some other thread. (Note: the Safepoint abstraction also
4312 // uses the Threads_lock to guarantee this property. It also makes sure that
4313 // all threads gets blocked when exiting or starting).
4314
4315 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4316 ALL_JAVA_THREADS(p) {
4317 p->oops_do(f, cf);
4318 }
4319 VMThread::vm_thread()->oops_do(f, cf);
4320 }
4321
4322 void Threads::change_thread_claim_parity() {
4323 // Set the new claim parity.
4324 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4325 "Not in range.");
4326 _thread_claim_parity++;
4327 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4328 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4329 "Not in range.");
4330 }
4331
4332 #ifdef ASSERT
4333 void Threads::assert_all_threads_claimed() {
4334 ALL_JAVA_THREADS(p) {
4335 const int thread_parity = p->oops_do_parity();
4336 assert((thread_parity == _thread_claim_parity),
4337 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4338 }
4339 }
4340 #endif // ASSERT
4341
4342 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4343 int cp = Threads::thread_claim_parity();
4344 ALL_JAVA_THREADS(p) {
4345 if (p->claim_oops_do(is_par, cp)) {
4346 p->oops_do(f, cf);
4347 }
4348 }
4349 VMThread* vmt = VMThread::vm_thread();
4350 if (vmt->claim_oops_do(is_par, cp)) {
4351 vmt->oops_do(f, cf);
4352 }
4353 }
4354
4355 #if INCLUDE_ALL_GCS
4356 // Used by ParallelScavenge
4357 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4358 ALL_JAVA_THREADS(p) {
4359 q->enqueue(new ThreadRootsTask(p));
4360 }
4361 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4362 }
4363
4364 // Used by Parallel Old
4365 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4366 ALL_JAVA_THREADS(p) {
4367 q->enqueue(new ThreadRootsMarkingTask(p));
4368 }
4369 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4370 }
4371 #endif // INCLUDE_ALL_GCS
4372
4373 void Threads::nmethods_do(CodeBlobClosure* cf) {
4374 ALL_JAVA_THREADS(p) {
4375 // This is used by the code cache sweeper to mark nmethods that are active
4376 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4377 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4378 if(!p->is_Code_cache_sweeper_thread()) {
4379 p->nmethods_do(cf);
4380 }
4381 }
4382 }
4383
4384 void Threads::metadata_do(void f(Metadata*)) {
4385 ALL_JAVA_THREADS(p) {
4386 p->metadata_do(f);
4387 }
4388 }
4389
4390 class ThreadHandlesClosure : public ThreadClosure {
4391 void (*_f)(Metadata*);
4392 public:
4393 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4394 virtual void do_thread(Thread* thread) {
4395 thread->metadata_handles_do(_f);
4396 }
4397 };
4398
4399 void Threads::metadata_handles_do(void f(Metadata*)) {
4400 // Only walk the Handles in Thread.
4401 ThreadHandlesClosure handles_closure(f);
4402 threads_do(&handles_closure);
4403 }
4404
4405 void Threads::deoptimized_wrt_marked_nmethods() {
4406 ALL_JAVA_THREADS(p) {
4407 p->deoptimized_wrt_marked_nmethods();
4408 }
4409 }
4410
4411
4412 // Get count Java threads that are waiting to enter the specified monitor.
4413 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4414 address monitor,
4415 bool doLock) {
4416 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4417 "must grab Threads_lock or be at safepoint");
4418 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4419
4420 int i = 0;
4421 {
4422 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4423 ALL_JAVA_THREADS(p) {
4424 if (!p->can_call_java()) continue;
4425
4426 address pending = (address)p->current_pending_monitor();
4427 if (pending == monitor) { // found a match
4428 if (i < count) result->append(p); // save the first count matches
4429 i++;
4430 }
4431 }
4432 }
4433 return result;
4434 }
4435
4436
4437 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4438 bool doLock) {
4439 assert(doLock ||
4440 Threads_lock->owned_by_self() ||
4441 SafepointSynchronize::is_at_safepoint(),
4442 "must grab Threads_lock or be at safepoint");
4443
4444 // NULL owner means not locked so we can skip the search
4445 if (owner == NULL) return NULL;
4446
4447 {
4448 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4449 ALL_JAVA_THREADS(p) {
4450 // first, see if owner is the address of a Java thread
4451 if (owner == (address)p) return p;
4452 }
4453 }
4454 // Cannot assert on lack of success here since this function may be
4455 // used by code that is trying to report useful problem information
4456 // like deadlock detection.
4457 if (UseHeavyMonitors) return NULL;
4458
4459 // If we didn't find a matching Java thread and we didn't force use of
4460 // heavyweight monitors, then the owner is the stack address of the
4461 // Lock Word in the owning Java thread's stack.
4462 //
4463 JavaThread* the_owner = NULL;
4464 {
4465 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4466 ALL_JAVA_THREADS(q) {
4467 if (q->is_lock_owned(owner)) {
4468 the_owner = q;
4469 break;
4470 }
4471 }
4472 }
4473 // cannot assert on lack of success here; see above comment
4474 return the_owner;
4475 }
4476
4477 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4478 void Threads::print_on(outputStream* st, bool print_stacks,
4479 bool internal_format, bool print_concurrent_locks) {
4480 char buf[32];
4481 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4482
4483 st->print_cr("Full thread dump %s (%s %s):",
4484 Abstract_VM_Version::vm_name(),
4485 Abstract_VM_Version::vm_release(),
4486 Abstract_VM_Version::vm_info_string());
4487 st->cr();
4488
4489 #if INCLUDE_SERVICES
4490 // Dump concurrent locks
4491 ConcurrentLocksDump concurrent_locks;
4492 if (print_concurrent_locks) {
4493 concurrent_locks.dump_at_safepoint();
4494 }
4495 #endif // INCLUDE_SERVICES
4496
4497 ALL_JAVA_THREADS(p) {
4498 ResourceMark rm;
4499 p->print_on(st);
4500 if (print_stacks) {
4501 if (internal_format) {
4502 p->trace_stack();
4503 } else {
4504 p->print_stack_on(st);
4505 }
4506 }
4507 st->cr();
4508 #if INCLUDE_SERVICES
4509 if (print_concurrent_locks) {
4510 concurrent_locks.print_locks_on(p, st);
4511 }
4512 #endif // INCLUDE_SERVICES
4513 }
4514
4515 VMThread::vm_thread()->print_on(st);
4516 st->cr();
4517 Universe::heap()->print_gc_threads_on(st);
4518 WatcherThread* wt = WatcherThread::watcher_thread();
4519 if (wt != NULL) {
4520 wt->print_on(st);
4521 st->cr();
4522 }
4523 st->flush();
4524 }
4525
4526 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4527 int buflen, bool* found_current) {
4528 if (this_thread != NULL) {
4529 bool is_current = (current == this_thread);
4530 *found_current = *found_current || is_current;
4531 st->print("%s", is_current ? "=>" : " ");
4532
4533 st->print(PTR_FORMAT, p2i(this_thread));
4534 st->print(" ");
4535 this_thread->print_on_error(st, buf, buflen);
4536 st->cr();
4537 }
4538 }
4539
4540 class PrintOnErrorClosure : public ThreadClosure {
4541 outputStream* _st;
4542 Thread* _current;
4543 char* _buf;
4544 int _buflen;
4545 bool* _found_current;
4546 public:
4547 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4548 int buflen, bool* found_current) :
4549 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4550
4551 virtual void do_thread(Thread* thread) {
4552 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4553 }
4554 };
4555
4556 // Threads::print_on_error() is called by fatal error handler. It's possible
4557 // that VM is not at safepoint and/or current thread is inside signal handler.
4558 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4559 // memory (even in resource area), it might deadlock the error handler.
4560 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4561 int buflen) {
4562 bool found_current = false;
4563 st->print_cr("Java Threads: ( => current thread )");
4564 ALL_JAVA_THREADS(thread) {
4565 print_on_error(thread, st, current, buf, buflen, &found_current);
4566 }
4567 st->cr();
4568
4569 st->print_cr("Other Threads:");
4570 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4571 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4572
4573 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4574 Universe::heap()->gc_threads_do(&print_closure);
4575
4576 if (!found_current) {
4577 st->cr();
4578 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4579 current->print_on_error(st, buf, buflen);
4580 st->cr();
4581 }
4582 st->cr();
4583 st->print_cr("Threads with active compile tasks:");
4584 print_threads_compiling(st, buf, buflen);
4585 }
4586
4587 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4588 ALL_JAVA_THREADS(thread) {
4589 if (thread->is_Compiler_thread()) {
4590 CompilerThread* ct = (CompilerThread*) thread;
4591 if (ct->task() != NULL) {
4592 thread->print_name_on_error(st, buf, buflen);
4593 ct->task()->print(st, NULL, true, true);
4594 }
4595 }
4596 }
4597 }
4598
4599
4600 // Internal SpinLock and Mutex
4601 // Based on ParkEvent
4602
4603 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4604 //
4605 // We employ SpinLocks _only for low-contention, fixed-length
4606 // short-duration critical sections where we're concerned
4607 // about native mutex_t or HotSpot Mutex:: latency.
4608 // The mux construct provides a spin-then-block mutual exclusion
4609 // mechanism.
4610 //
4611 // Testing has shown that contention on the ListLock guarding gFreeList
4612 // is common. If we implement ListLock as a simple SpinLock it's common
4613 // for the JVM to devolve to yielding with little progress. This is true
4614 // despite the fact that the critical sections protected by ListLock are
4615 // extremely short.
4616 //
4617 // TODO-FIXME: ListLock should be of type SpinLock.
4618 // We should make this a 1st-class type, integrated into the lock
4619 // hierarchy as leaf-locks. Critically, the SpinLock structure
4620 // should have sufficient padding to avoid false-sharing and excessive
4621 // cache-coherency traffic.
4622
4623
4624 typedef volatile int SpinLockT;
4625
4626 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4627 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4628 return; // normal fast-path return
4629 }
4630
4631 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4632 TEVENT(SpinAcquire - ctx);
4633 int ctr = 0;
4634 int Yields = 0;
4635 for (;;) {
4636 while (*adr != 0) {
4637 ++ctr;
4638 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4639 if (Yields > 5) {
4640 os::naked_short_sleep(1);
4641 } else {
4642 os::naked_yield();
4643 ++Yields;
4644 }
4645 } else {
4646 SpinPause();
4647 }
4648 }
4649 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4650 }
4651 }
4652
4653 void Thread::SpinRelease(volatile int * adr) {
4654 assert(*adr != 0, "invariant");
4655 OrderAccess::fence(); // guarantee at least release consistency.
4656 // Roach-motel semantics.
4657 // It's safe if subsequent LDs and STs float "up" into the critical section,
4658 // but prior LDs and STs within the critical section can't be allowed
4659 // to reorder or float past the ST that releases the lock.
4660 // Loads and stores in the critical section - which appear in program
4661 // order before the store that releases the lock - must also appear
4662 // before the store that releases the lock in memory visibility order.
4663 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4664 // the ST of 0 into the lock-word which releases the lock, so fence
4665 // more than covers this on all platforms.
4666 *adr = 0;
4667 }
4668
4669 // muxAcquire and muxRelease:
4670 //
4671 // * muxAcquire and muxRelease support a single-word lock-word construct.
4672 // The LSB of the word is set IFF the lock is held.
4673 // The remainder of the word points to the head of a singly-linked list
4674 // of threads blocked on the lock.
4675 //
4676 // * The current implementation of muxAcquire-muxRelease uses its own
4677 // dedicated Thread._MuxEvent instance. If we're interested in
4678 // minimizing the peak number of extant ParkEvent instances then
4679 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4680 // as certain invariants were satisfied. Specifically, care would need
4681 // to be taken with regards to consuming unpark() "permits".
4682 // A safe rule of thumb is that a thread would never call muxAcquire()
4683 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4684 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4685 // consume an unpark() permit intended for monitorenter, for instance.
4686 // One way around this would be to widen the restricted-range semaphore
4687 // implemented in park(). Another alternative would be to provide
4688 // multiple instances of the PlatformEvent() for each thread. One
4689 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4690 //
4691 // * Usage:
4692 // -- Only as leaf locks
4693 // -- for short-term locking only as muxAcquire does not perform
4694 // thread state transitions.
4695 //
4696 // Alternatives:
4697 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4698 // but with parking or spin-then-park instead of pure spinning.
4699 // * Use Taura-Oyama-Yonenzawa locks.
4700 // * It's possible to construct a 1-0 lock if we encode the lockword as
4701 // (List,LockByte). Acquire will CAS the full lockword while Release
4702 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4703 // acquiring threads use timers (ParkTimed) to detect and recover from
4704 // the stranding window. Thread/Node structures must be aligned on 256-byte
4705 // boundaries by using placement-new.
4706 // * Augment MCS with advisory back-link fields maintained with CAS().
4707 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4708 // The validity of the backlinks must be ratified before we trust the value.
4709 // If the backlinks are invalid the exiting thread must back-track through the
4710 // the forward links, which are always trustworthy.
4711 // * Add a successor indication. The LockWord is currently encoded as
4712 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4713 // to provide the usual futile-wakeup optimization.
4714 // See RTStt for details.
4715 // * Consider schedctl.sc_nopreempt to cover the critical section.
4716 //
4717
4718
4719 typedef volatile intptr_t MutexT; // Mux Lock-word
4720 enum MuxBits { LOCKBIT = 1 };
4721
4722 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4723 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4724 if (w == 0) return;
4725 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4726 return;
4727 }
4728
4729 TEVENT(muxAcquire - Contention);
4730 ParkEvent * const Self = Thread::current()->_MuxEvent;
4731 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4732 for (;;) {
4733 int its = (os::is_MP() ? 100 : 0) + 1;
4734
4735 // Optional spin phase: spin-then-park strategy
4736 while (--its >= 0) {
4737 w = *Lock;
4738 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4739 return;
4740 }
4741 }
4742
4743 Self->reset();
4744 Self->OnList = intptr_t(Lock);
4745 // The following fence() isn't _strictly necessary as the subsequent
4746 // CAS() both serializes execution and ratifies the fetched *Lock value.
4747 OrderAccess::fence();
4748 for (;;) {
4749 w = *Lock;
4750 if ((w & LOCKBIT) == 0) {
4751 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4752 Self->OnList = 0; // hygiene - allows stronger asserts
4753 return;
4754 }
4755 continue; // Interference -- *Lock changed -- Just retry
4756 }
4757 assert(w & LOCKBIT, "invariant");
4758 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4759 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4760 }
4761
4762 while (Self->OnList != 0) {
4763 Self->park();
4764 }
4765 }
4766 }
4767
4768 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4769 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4770 if (w == 0) return;
4771 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4772 return;
4773 }
4774
4775 TEVENT(muxAcquire - Contention);
4776 ParkEvent * ReleaseAfter = NULL;
4777 if (ev == NULL) {
4778 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4779 }
4780 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4781 for (;;) {
4782 guarantee(ev->OnList == 0, "invariant");
4783 int its = (os::is_MP() ? 100 : 0) + 1;
4784
4785 // Optional spin phase: spin-then-park strategy
4786 while (--its >= 0) {
4787 w = *Lock;
4788 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4789 if (ReleaseAfter != NULL) {
4790 ParkEvent::Release(ReleaseAfter);
4791 }
4792 return;
4793 }
4794 }
4795
4796 ev->reset();
4797 ev->OnList = intptr_t(Lock);
4798 // The following fence() isn't _strictly necessary as the subsequent
4799 // CAS() both serializes execution and ratifies the fetched *Lock value.
4800 OrderAccess::fence();
4801 for (;;) {
4802 w = *Lock;
4803 if ((w & LOCKBIT) == 0) {
4804 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4805 ev->OnList = 0;
4806 // We call ::Release while holding the outer lock, thus
4807 // artificially lengthening the critical section.
4808 // Consider deferring the ::Release() until the subsequent unlock(),
4809 // after we've dropped the outer lock.
4810 if (ReleaseAfter != NULL) {
4811 ParkEvent::Release(ReleaseAfter);
4812 }
4813 return;
4814 }
4815 continue; // Interference -- *Lock changed -- Just retry
4816 }
4817 assert(w & LOCKBIT, "invariant");
4818 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4819 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4820 }
4821
4822 while (ev->OnList != 0) {
4823 ev->park();
4824 }
4825 }
4826 }
4827
4828 // Release() must extract a successor from the list and then wake that thread.
4829 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4830 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4831 // Release() would :
4832 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4833 // (B) Extract a successor from the private list "in-hand"
4834 // (C) attempt to CAS() the residual back into *Lock over null.
4835 // If there were any newly arrived threads and the CAS() would fail.
4836 // In that case Release() would detach the RATs, re-merge the list in-hand
4837 // with the RATs and repeat as needed. Alternately, Release() might
4838 // detach and extract a successor, but then pass the residual list to the wakee.
4839 // The wakee would be responsible for reattaching and remerging before it
4840 // competed for the lock.
4841 //
4842 // Both "pop" and DMR are immune from ABA corruption -- there can be
4843 // multiple concurrent pushers, but only one popper or detacher.
4844 // This implementation pops from the head of the list. This is unfair,
4845 // but tends to provide excellent throughput as hot threads remain hot.
4846 // (We wake recently run threads first).
4847 //
4848 // All paths through muxRelease() will execute a CAS.
4849 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4850 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4851 // executed within the critical section are complete and globally visible before the
4852 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4853 void Thread::muxRelease(volatile intptr_t * Lock) {
4854 for (;;) {
4855 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4856 assert(w & LOCKBIT, "invariant");
4857 if (w == LOCKBIT) return;
4858 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4859 assert(List != NULL, "invariant");
4860 assert(List->OnList == intptr_t(Lock), "invariant");
4861 ParkEvent * const nxt = List->ListNext;
4862 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4863
4864 // The following CAS() releases the lock and pops the head element.
4865 // The CAS() also ratifies the previously fetched lock-word value.
4866 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4867 continue;
4868 }
4869 List->OnList = 0;
4870 OrderAccess::fence();
4871 List->unpark();
4872 return;
4873 }
4874 }
4875
4876
4877 void Threads::verify() {
4878 ALL_JAVA_THREADS(p) {
4879 p->verify();
4880 }
4881 VMThread* thread = VMThread::vm_thread();
4882 if (thread != NULL) thread->verify();
4883 }