1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/codeCacheExtensions.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/gcId.hpp"
37 #include "gc/shared/gcLocker.inline.hpp"
38 #include "gc/shared/referencePendingListLocker.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "memory/metaspaceShared.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.inline.hpp"
50 #include "oops/instanceKlass.hpp"
51 #include "oops/objArrayOop.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/symbol.hpp"
54 #include "oops/verifyOopClosure.hpp"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagRangeList.hpp"
64 #include "runtime/deoptimization.hpp"
65 #include "runtime/fprofiler.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/interfaceSupport.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/javaCalls.hpp"
72 #include "runtime/jniPeriodicChecker.hpp"
73 #include "runtime/timerTrace.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/statSampler.hpp"
82 #include "runtime/stubRoutines.hpp"
83 #include "runtime/sweeper.hpp"
84 #include "runtime/task.hpp"
85 #include "runtime/thread.inline.hpp"
86 #include "runtime/threadCritical.hpp"
87 #include "runtime/vframe.hpp"
88 #include "runtime/vframeArray.hpp"
89 #include "runtime/vframe_hp.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "runtime/vm_operations.hpp"
92 #include "runtime/vm_version.hpp"
93 #include "services/attachListener.hpp"
94 #include "services/management.hpp"
95 #include "services/memTracker.hpp"
96 #include "services/threadService.hpp"
97 #include "trace/traceMacros.hpp"
98 #include "trace/tracing.hpp"
99 #include "utilities/defaultStream.hpp"
100 #include "utilities/dtrace.hpp"
101 #include "utilities/events.hpp"
102 #include "utilities/macros.hpp"
103 #include "utilities/preserveException.hpp"
104 #if INCLUDE_ALL_GCS
105 #include "gc/cms/concurrentMarkSweepThread.hpp"
106 #include "gc/g1/concurrentMarkThread.inline.hpp"
107 #include "gc/parallel/pcTasks.hpp"
108 #endif // INCLUDE_ALL_GCS
109 #if INCLUDE_JVMCI
110 #include "jvmci/jvmciCompiler.hpp"
111 #include "jvmci/jvmciRuntime.hpp"
112 #endif
113 #ifdef COMPILER1
114 #include "c1/c1_Compiler.hpp"
115 #endif
116 #ifdef COMPILER2
117 #include "opto/c2compiler.hpp"
118 #include "opto/idealGraphPrinter.hpp"
119 #endif
120 #if INCLUDE_RTM_OPT
121 #include "runtime/rtmLocking.hpp"
122 #endif
123
124 // Initialization after module runtime initialization
125 void universe_post_module_init(); // must happen after call_initPhase2
126
127 #ifdef DTRACE_ENABLED
128
129 // Only bother with this argument setup if dtrace is available
130
131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
133
134 #define DTRACE_THREAD_PROBE(probe, javathread) \
135 { \
136 ResourceMark rm(this); \
137 int len = 0; \
138 const char* name = (javathread)->get_thread_name(); \
139 len = strlen(name); \
140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
141 (char *) name, len, \
142 java_lang_Thread::thread_id((javathread)->threadObj()), \
143 (uintptr_t) (javathread)->osthread()->thread_id(), \
144 java_lang_Thread::is_daemon((javathread)->threadObj())); \
145 }
146
147 #else // ndef DTRACE_ENABLED
148
149 #define DTRACE_THREAD_PROBE(probe, javathread)
150
151 #endif // ndef DTRACE_ENABLED
152
153 #ifndef USE_LIBRARY_BASED_TLS_ONLY
154 // Current thread is maintained as a thread-local variable
155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
156 #endif
157 // Class hierarchy
158 // - Thread
159 // - VMThread
160 // - WatcherThread
161 // - ConcurrentMarkSweepThread
162 // - JavaThread
163 // - CompilerThread
164
165 // ======= Thread ========
166 // Support for forcing alignment of thread objects for biased locking
167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
168 if (UseBiasedLocking) {
169 const int alignment = markOopDesc::biased_lock_alignment;
170 size_t aligned_size = size + (alignment - sizeof(intptr_t));
171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
172 : AllocateHeap(aligned_size, flags, CURRENT_PC,
173 AllocFailStrategy::RETURN_NULL);
174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
177 "JavaThread alignment code overflowed allocated storage");
178 if (aligned_addr != real_malloc_addr) {
179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
180 p2i(real_malloc_addr),
181 p2i(aligned_addr));
182 }
183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
184 return aligned_addr;
185 } else {
186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
188 }
189 }
190
191 void Thread::operator delete(void* p) {
192 if (UseBiasedLocking) {
193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
194 FreeHeap(real_malloc_addr);
195 } else {
196 FreeHeap(p);
197 }
198 }
199
200
201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
202 // JavaThread
203
204
205 Thread::Thread() {
206 // stack and get_thread
207 set_stack_base(NULL);
208 set_stack_size(0);
209 set_self_raw_id(0);
210 set_lgrp_id(-1);
211 DEBUG_ONLY(clear_suspendible_thread();)
212
213 // allocated data structures
214 set_osthread(NULL);
215 set_resource_area(new (mtThread)ResourceArea());
216 DEBUG_ONLY(_current_resource_mark = NULL;)
217 set_handle_area(new (mtThread) HandleArea(NULL));
218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
219 set_active_handles(NULL);
220 set_free_handle_block(NULL);
221 set_last_handle_mark(NULL);
222
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
225
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
228
229 // plain initialization
230 debug_only(_owned_locks = NULL;)
231 debug_only(_allow_allocation_count = 0;)
232 NOT_PRODUCT(_allow_safepoint_count = 0;)
233 NOT_PRODUCT(_skip_gcalot = false;)
234 _jvmti_env_iteration_count = 0;
235 set_allocated_bytes(0);
236 _vm_operation_started_count = 0;
237 _vm_operation_completed_count = 0;
238 _current_pending_monitor = NULL;
239 _current_pending_monitor_is_from_java = true;
240 _current_waiting_monitor = NULL;
241 _num_nested_signal = 0;
242 omFreeList = NULL;
243 omFreeCount = 0;
244 omFreeProvision = 32;
245 omInUseList = NULL;
246 omInUseCount = 0;
247
248 #ifdef ASSERT
249 _visited_for_critical_count = false;
250 #endif
251
252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
253 Monitor::_safepoint_check_sometimes);
254 _suspend_flags = 0;
255
256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
257 _hashStateX = os::random();
258 _hashStateY = 842502087;
259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
260 _hashStateW = 273326509;
261
262 _OnTrap = 0;
263 _schedctl = NULL;
264 _Stalled = 0;
265 _TypeTag = 0x2BAD;
266
267 // Many of the following fields are effectively final - immutable
268 // Note that nascent threads can't use the Native Monitor-Mutex
269 // construct until the _MutexEvent is initialized ...
270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
271 // we might instead use a stack of ParkEvents that we could provision on-demand.
272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
273 // and ::Release()
274 _ParkEvent = ParkEvent::Allocate(this);
275 _SleepEvent = ParkEvent::Allocate(this);
276 _MutexEvent = ParkEvent::Allocate(this);
277 _MuxEvent = ParkEvent::Allocate(this);
278
279 #ifdef CHECK_UNHANDLED_OOPS
280 if (CheckUnhandledOops) {
281 _unhandled_oops = new UnhandledOops(this);
282 }
283 #endif // CHECK_UNHANDLED_OOPS
284 #ifdef ASSERT
285 if (UseBiasedLocking) {
286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
287 assert(this == _real_malloc_address ||
288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
289 "bug in forced alignment of thread objects");
290 }
291 #endif // ASSERT
292 }
293
294 void Thread::initialize_thread_current() {
295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
296 assert(_thr_current == NULL, "Thread::current already initialized");
297 _thr_current = this;
298 #endif
299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
300 ThreadLocalStorage::set_thread(this);
301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
302 }
303
304 void Thread::clear_thread_current() {
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
307 _thr_current = NULL;
308 #endif
309 ThreadLocalStorage::set_thread(NULL);
310 }
311
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 // CR 7190089: on Solaris, primordial thread's stack is adjusted
316 // in initialize_thread(). Without the adjustment, stack size is
317 // incorrect if stack is set to unlimited (ulimit -s unlimited).
318 // So far, only Solaris has real implementation of initialize_thread().
319 //
320 // set up any platform-specific state.
321 os::initialize_thread(this);
322
323 // Set stack limits after thread is initialized.
324 if (is_Java_thread()) {
325 ((JavaThread*) this)->set_stack_overflow_limit();
326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
327 }
328 #if INCLUDE_NMT
329 // record thread's native stack, stack grows downward
330 MemTracker::record_thread_stack(stack_end(), stack_size());
331 #endif // INCLUDE_NMT
332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
334 os::current_thread_id(), p2i(stack_base() - stack_size()),
335 p2i(stack_base()), stack_size()/1024);
336 }
337
338
339 Thread::~Thread() {
340 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
341 ObjectSynchronizer::omFlush(this);
342
343 EVENT_THREAD_DESTRUCT(this);
344
345 // stack_base can be NULL if the thread is never started or exited before
346 // record_stack_base_and_size called. Although, we would like to ensure
347 // that all started threads do call record_stack_base_and_size(), there is
348 // not proper way to enforce that.
349 #if INCLUDE_NMT
350 if (_stack_base != NULL) {
351 MemTracker::release_thread_stack(stack_end(), stack_size());
352 #ifdef ASSERT
353 set_stack_base(NULL);
354 #endif
355 }
356 #endif // INCLUDE_NMT
357
358 // deallocate data structures
359 delete resource_area();
360 // since the handle marks are using the handle area, we have to deallocated the root
361 // handle mark before deallocating the thread's handle area,
362 assert(last_handle_mark() != NULL, "check we have an element");
363 delete last_handle_mark();
364 assert(last_handle_mark() == NULL, "check we have reached the end");
365
366 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
367 // We NULL out the fields for good hygiene.
368 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
369 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
370 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
371 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
372
373 delete handle_area();
374 delete metadata_handles();
375
376 // osthread() can be NULL, if creation of thread failed.
377 if (osthread() != NULL) os::free_thread(osthread());
378
379 delete _SR_lock;
380
381 // clear Thread::current if thread is deleting itself.
382 // Needed to ensure JNI correctly detects non-attached threads.
383 if (this == Thread::current()) {
384 clear_thread_current();
385 }
386
387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
388 }
389
390 // NOTE: dummy function for assertion purpose.
391 void Thread::run() {
392 ShouldNotReachHere();
393 }
394
395 #ifdef ASSERT
396 // Private method to check for dangling thread pointer
397 void check_for_dangling_thread_pointer(Thread *thread) {
398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
399 "possibility of dangling Thread pointer");
400 }
401 #endif
402
403 ThreadPriority Thread::get_priority(const Thread* const thread) {
404 ThreadPriority priority;
405 // Can return an error!
406 (void)os::get_priority(thread, priority);
407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
408 return priority;
409 }
410
411 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
412 debug_only(check_for_dangling_thread_pointer(thread);)
413 // Can return an error!
414 (void)os::set_priority(thread, priority);
415 }
416
417
418 void Thread::start(Thread* thread) {
419 // Start is different from resume in that its safety is guaranteed by context or
420 // being called from a Java method synchronized on the Thread object.
421 if (!DisableStartThread) {
422 if (thread->is_Java_thread()) {
423 // Initialize the thread state to RUNNABLE before starting this thread.
424 // Can not set it after the thread started because we do not know the
425 // exact thread state at that time. It could be in MONITOR_WAIT or
426 // in SLEEPING or some other state.
427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
428 java_lang_Thread::RUNNABLE);
429 }
430 os::start_thread(thread);
431 }
432 }
433
434 // Enqueue a VM_Operation to do the job for us - sometime later
435 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
437 VMThread::execute(vm_stop);
438 }
439
440
441 // Check if an external suspend request has completed (or has been
442 // cancelled). Returns true if the thread is externally suspended and
443 // false otherwise.
444 //
445 // The bits parameter returns information about the code path through
446 // the routine. Useful for debugging:
447 //
448 // set in is_ext_suspend_completed():
449 // 0x00000001 - routine was entered
450 // 0x00000010 - routine return false at end
451 // 0x00000100 - thread exited (return false)
452 // 0x00000200 - suspend request cancelled (return false)
453 // 0x00000400 - thread suspended (return true)
454 // 0x00001000 - thread is in a suspend equivalent state (return true)
455 // 0x00002000 - thread is native and walkable (return true)
456 // 0x00004000 - thread is native_trans and walkable (needed retry)
457 //
458 // set in wait_for_ext_suspend_completion():
459 // 0x00010000 - routine was entered
460 // 0x00020000 - suspend request cancelled before loop (return false)
461 // 0x00040000 - thread suspended before loop (return true)
462 // 0x00080000 - suspend request cancelled in loop (return false)
463 // 0x00100000 - thread suspended in loop (return true)
464 // 0x00200000 - suspend not completed during retry loop (return false)
465
466 // Helper class for tracing suspend wait debug bits.
467 //
468 // 0x00000100 indicates that the target thread exited before it could
469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
470 // 0x00080000 each indicate a cancelled suspend request so they don't
471 // count as wait failures either.
472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
473
474 class TraceSuspendDebugBits : public StackObj {
475 private:
476 JavaThread * jt;
477 bool is_wait;
478 bool called_by_wait; // meaningful when !is_wait
479 uint32_t * bits;
480
481 public:
482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
483 uint32_t *_bits) {
484 jt = _jt;
485 is_wait = _is_wait;
486 called_by_wait = _called_by_wait;
487 bits = _bits;
488 }
489
490 ~TraceSuspendDebugBits() {
491 if (!is_wait) {
492 #if 1
493 // By default, don't trace bits for is_ext_suspend_completed() calls.
494 // That trace is very chatty.
495 return;
496 #else
497 if (!called_by_wait) {
498 // If tracing for is_ext_suspend_completed() is enabled, then only
499 // trace calls to it from wait_for_ext_suspend_completion()
500 return;
501 }
502 #endif
503 }
504
505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
507 MutexLocker ml(Threads_lock); // needed for get_thread_name()
508 ResourceMark rm;
509
510 tty->print_cr(
511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
512 jt->get_thread_name(), *bits);
513
514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
515 }
516 }
517 }
518 };
519 #undef DEBUG_FALSE_BITS
520
521
522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
523 uint32_t *bits) {
524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
525
526 bool did_trans_retry = false; // only do thread_in_native_trans retry once
527 bool do_trans_retry; // flag to force the retry
528
529 *bits |= 0x00000001;
530
531 do {
532 do_trans_retry = false;
533
534 if (is_exiting()) {
535 // Thread is in the process of exiting. This is always checked
536 // first to reduce the risk of dereferencing a freed JavaThread.
537 *bits |= 0x00000100;
538 return false;
539 }
540
541 if (!is_external_suspend()) {
542 // Suspend request is cancelled. This is always checked before
543 // is_ext_suspended() to reduce the risk of a rogue resume
544 // confusing the thread that made the suspend request.
545 *bits |= 0x00000200;
546 return false;
547 }
548
549 if (is_ext_suspended()) {
550 // thread is suspended
551 *bits |= 0x00000400;
552 return true;
553 }
554
555 // Now that we no longer do hard suspends of threads running
556 // native code, the target thread can be changing thread state
557 // while we are in this routine:
558 //
559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
560 //
561 // We save a copy of the thread state as observed at this moment
562 // and make our decision about suspend completeness based on the
563 // copy. This closes the race where the thread state is seen as
564 // _thread_in_native_trans in the if-thread_blocked check, but is
565 // seen as _thread_blocked in if-thread_in_native_trans check.
566 JavaThreadState save_state = thread_state();
567
568 if (save_state == _thread_blocked && is_suspend_equivalent()) {
569 // If the thread's state is _thread_blocked and this blocking
570 // condition is known to be equivalent to a suspend, then we can
571 // consider the thread to be externally suspended. This means that
572 // the code that sets _thread_blocked has been modified to do
573 // self-suspension if the blocking condition releases. We also
574 // used to check for CONDVAR_WAIT here, but that is now covered by
575 // the _thread_blocked with self-suspension check.
576 //
577 // Return true since we wouldn't be here unless there was still an
578 // external suspend request.
579 *bits |= 0x00001000;
580 return true;
581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
582 // Threads running native code will self-suspend on native==>VM/Java
583 // transitions. If its stack is walkable (should always be the case
584 // unless this function is called before the actual java_suspend()
585 // call), then the wait is done.
586 *bits |= 0x00002000;
587 return true;
588 } else if (!called_by_wait && !did_trans_retry &&
589 save_state == _thread_in_native_trans &&
590 frame_anchor()->walkable()) {
591 // The thread is transitioning from thread_in_native to another
592 // thread state. check_safepoint_and_suspend_for_native_trans()
593 // will force the thread to self-suspend. If it hasn't gotten
594 // there yet we may have caught the thread in-between the native
595 // code check above and the self-suspend. Lucky us. If we were
596 // called by wait_for_ext_suspend_completion(), then it
597 // will be doing the retries so we don't have to.
598 //
599 // Since we use the saved thread state in the if-statement above,
600 // there is a chance that the thread has already transitioned to
601 // _thread_blocked by the time we get here. In that case, we will
602 // make a single unnecessary pass through the logic below. This
603 // doesn't hurt anything since we still do the trans retry.
604
605 *bits |= 0x00004000;
606
607 // Once the thread leaves thread_in_native_trans for another
608 // thread state, we break out of this retry loop. We shouldn't
609 // need this flag to prevent us from getting back here, but
610 // sometimes paranoia is good.
611 did_trans_retry = true;
612
613 // We wait for the thread to transition to a more usable state.
614 for (int i = 1; i <= SuspendRetryCount; i++) {
615 // We used to do an "os::yield_all(i)" call here with the intention
616 // that yielding would increase on each retry. However, the parameter
617 // is ignored on Linux which means the yield didn't scale up. Waiting
618 // on the SR_lock below provides a much more predictable scale up for
619 // the delay. It also provides a simple/direct point to check for any
620 // safepoint requests from the VMThread
621
622 // temporarily drops SR_lock while doing wait with safepoint check
623 // (if we're a JavaThread - the WatcherThread can also call this)
624 // and increase delay with each retry
625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
626
627 // check the actual thread state instead of what we saved above
628 if (thread_state() != _thread_in_native_trans) {
629 // the thread has transitioned to another thread state so
630 // try all the checks (except this one) one more time.
631 do_trans_retry = true;
632 break;
633 }
634 } // end retry loop
635
636
637 }
638 } while (do_trans_retry);
639
640 *bits |= 0x00000010;
641 return false;
642 }
643
644 // Wait for an external suspend request to complete (or be cancelled).
645 // Returns true if the thread is externally suspended and false otherwise.
646 //
647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
648 uint32_t *bits) {
649 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
650 false /* !called_by_wait */, bits);
651
652 // local flag copies to minimize SR_lock hold time
653 bool is_suspended;
654 bool pending;
655 uint32_t reset_bits;
656
657 // set a marker so is_ext_suspend_completed() knows we are the caller
658 *bits |= 0x00010000;
659
660 // We use reset_bits to reinitialize the bits value at the top of
661 // each retry loop. This allows the caller to make use of any
662 // unused bits for their own marking purposes.
663 reset_bits = *bits;
664
665 {
666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
668 delay, bits);
669 pending = is_external_suspend();
670 }
671 // must release SR_lock to allow suspension to complete
672
673 if (!pending) {
674 // A cancelled suspend request is the only false return from
675 // is_ext_suspend_completed() that keeps us from entering the
676 // retry loop.
677 *bits |= 0x00020000;
678 return false;
679 }
680
681 if (is_suspended) {
682 *bits |= 0x00040000;
683 return true;
684 }
685
686 for (int i = 1; i <= retries; i++) {
687 *bits = reset_bits; // reinit to only track last retry
688
689 // We used to do an "os::yield_all(i)" call here with the intention
690 // that yielding would increase on each retry. However, the parameter
691 // is ignored on Linux which means the yield didn't scale up. Waiting
692 // on the SR_lock below provides a much more predictable scale up for
693 // the delay. It also provides a simple/direct point to check for any
694 // safepoint requests from the VMThread
695
696 {
697 MutexLocker ml(SR_lock());
698 // wait with safepoint check (if we're a JavaThread - the WatcherThread
699 // can also call this) and increase delay with each retry
700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
701
702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
703 delay, bits);
704
705 // It is possible for the external suspend request to be cancelled
706 // (by a resume) before the actual suspend operation is completed.
707 // Refresh our local copy to see if we still need to wait.
708 pending = is_external_suspend();
709 }
710
711 if (!pending) {
712 // A cancelled suspend request is the only false return from
713 // is_ext_suspend_completed() that keeps us from staying in the
714 // retry loop.
715 *bits |= 0x00080000;
716 return false;
717 }
718
719 if (is_suspended) {
720 *bits |= 0x00100000;
721 return true;
722 }
723 } // end retry loop
724
725 // thread did not suspend after all our retries
726 *bits |= 0x00200000;
727 return false;
728 }
729
730 #ifndef PRODUCT
731 void JavaThread::record_jump(address target, address instr, const char* file,
732 int line) {
733
734 // This should not need to be atomic as the only way for simultaneous
735 // updates is via interrupts. Even then this should be rare or non-existent
736 // and we don't care that much anyway.
737
738 int index = _jmp_ring_index;
739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
740 _jmp_ring[index]._target = (intptr_t) target;
741 _jmp_ring[index]._instruction = (intptr_t) instr;
742 _jmp_ring[index]._file = file;
743 _jmp_ring[index]._line = line;
744 }
745 #endif // PRODUCT
746
747 // Called by flat profiler
748 // Callers have already called wait_for_ext_suspend_completion
749 // The assertion for that is currently too complex to put here:
750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
751 bool gotframe = false;
752 // self suspension saves needed state.
753 if (has_last_Java_frame() && _anchor.walkable()) {
754 *_fr = pd_last_frame();
755 gotframe = true;
756 }
757 return gotframe;
758 }
759
760 void Thread::interrupt(Thread* thread) {
761 debug_only(check_for_dangling_thread_pointer(thread);)
762 os::interrupt(thread);
763 }
764
765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 // Note: If clear_interrupted==false, this simply fetches and
768 // returns the value of the field osthread()->interrupted().
769 return os::is_interrupted(thread, clear_interrupted);
770 }
771
772
773 // GC Support
774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
775 jint thread_parity = _oops_do_parity;
776 if (thread_parity != strong_roots_parity) {
777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
778 if (res == thread_parity) {
779 return true;
780 } else {
781 guarantee(res == strong_roots_parity, "Or else what?");
782 return false;
783 }
784 }
785 return false;
786 }
787
788 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
789 active_handles()->oops_do(f);
790 // Do oop for ThreadShadow
791 f->do_oop((oop*)&_pending_exception);
792 handle_area()->oops_do(f);
793 }
794
795 void Thread::metadata_handles_do(void f(Metadata*)) {
796 // Only walk the Handles in Thread.
797 if (metadata_handles() != NULL) {
798 for (int i = 0; i< metadata_handles()->length(); i++) {
799 f(metadata_handles()->at(i));
800 }
801 }
802 }
803
804 void Thread::print_on(outputStream* st) const {
805 // get_priority assumes osthread initialized
806 if (osthread() != NULL) {
807 int os_prio;
808 if (os::get_native_priority(this, &os_prio) == OS_OK) {
809 st->print("os_prio=%d ", os_prio);
810 }
811 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
812 ext().print_on(st);
813 osthread()->print_on(st);
814 }
815 debug_only(if (WizardMode) print_owned_locks_on(st);)
816 }
817
818 // Thread::print_on_error() is called by fatal error handler. Don't use
819 // any lock or allocate memory.
820 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
821 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
822
823 if (is_VM_thread()) { st->print("VMThread"); }
824 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
825 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
826 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
827 else { st->print("Thread"); }
828
829 if (is_Named_thread()) {
830 st->print(" \"%s\"", name());
831 }
832
833 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
834 p2i(stack_end()), p2i(stack_base()));
835
836 if (osthread()) {
837 st->print(" [id=%d]", osthread()->thread_id());
838 }
839 }
840
841 #ifdef ASSERT
842 void Thread::print_owned_locks_on(outputStream* st) const {
843 Monitor *cur = _owned_locks;
844 if (cur == NULL) {
845 st->print(" (no locks) ");
846 } else {
847 st->print_cr(" Locks owned:");
848 while (cur) {
849 cur->print_on(st);
850 cur = cur->next();
851 }
852 }
853 }
854
855 static int ref_use_count = 0;
856
857 bool Thread::owns_locks_but_compiled_lock() const {
858 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
859 if (cur != Compile_lock) return true;
860 }
861 return false;
862 }
863
864
865 #endif
866
867 #ifndef PRODUCT
868
869 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
870 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
871 // no threads which allow_vm_block's are held
872 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
873 // Check if current thread is allowed to block at a safepoint
874 if (!(_allow_safepoint_count == 0)) {
875 fatal("Possible safepoint reached by thread that does not allow it");
876 }
877 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
878 fatal("LEAF method calling lock?");
879 }
880
881 #ifdef ASSERT
882 if (potential_vm_operation && is_Java_thread()
883 && !Universe::is_bootstrapping()) {
884 // Make sure we do not hold any locks that the VM thread also uses.
885 // This could potentially lead to deadlocks
886 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
887 // Threads_lock is special, since the safepoint synchronization will not start before this is
888 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
889 // since it is used to transfer control between JavaThreads and the VMThread
890 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
891 if ((cur->allow_vm_block() &&
892 cur != Threads_lock &&
893 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
894 cur != VMOperationRequest_lock &&
895 cur != VMOperationQueue_lock) ||
896 cur->rank() == Mutex::special) {
897 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
898 }
899 }
900 }
901
902 if (GCALotAtAllSafepoints) {
903 // We could enter a safepoint here and thus have a gc
904 InterfaceSupport::check_gc_alot();
905 }
906 #endif
907 }
908 #endif
909
910 bool Thread::is_in_stack(address adr) const {
911 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
912 address end = os::current_stack_pointer();
913 // Allow non Java threads to call this without stack_base
914 if (_stack_base == NULL) return true;
915 if (stack_base() >= adr && adr >= end) return true;
916
917 return false;
918 }
919
920 bool Thread::is_in_usable_stack(address adr) const {
921 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
922 size_t usable_stack_size = _stack_size - stack_guard_size;
923
924 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
925 }
926
927
928 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
929 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
930 // used for compilation in the future. If that change is made, the need for these methods
931 // should be revisited, and they should be removed if possible.
932
933 bool Thread::is_lock_owned(address adr) const {
934 return on_local_stack(adr);
935 }
936
937 bool Thread::set_as_starting_thread() {
938 // NOTE: this must be called inside the main thread.
939 return os::create_main_thread((JavaThread*)this);
940 }
941
942 static void initialize_class(Symbol* class_name, TRAPS) {
943 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
944 InstanceKlass::cast(klass)->initialize(CHECK);
945 }
946
947
948 // Creates the initial ThreadGroup
949 static Handle create_initial_thread_group(TRAPS) {
950 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
951 instanceKlassHandle klass (THREAD, k);
952
953 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
954 {
955 JavaValue result(T_VOID);
956 JavaCalls::call_special(&result,
957 system_instance,
958 klass,
959 vmSymbols::object_initializer_name(),
960 vmSymbols::void_method_signature(),
961 CHECK_NH);
962 }
963 Universe::set_system_thread_group(system_instance());
964
965 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
966 {
967 JavaValue result(T_VOID);
968 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
969 JavaCalls::call_special(&result,
970 main_instance,
971 klass,
972 vmSymbols::object_initializer_name(),
973 vmSymbols::threadgroup_string_void_signature(),
974 system_instance,
975 string,
976 CHECK_NH);
977 }
978 return main_instance;
979 }
980
981 // Creates the initial Thread
982 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
983 TRAPS) {
984 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
985 instanceKlassHandle klass (THREAD, k);
986 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
987
988 java_lang_Thread::set_thread(thread_oop(), thread);
989 java_lang_Thread::set_priority(thread_oop(), NormPriority);
990 thread->set_threadObj(thread_oop());
991
992 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
993
994 JavaValue result(T_VOID);
995 JavaCalls::call_special(&result, thread_oop,
996 klass,
997 vmSymbols::object_initializer_name(),
998 vmSymbols::threadgroup_string_void_signature(),
999 thread_group,
1000 string,
1001 CHECK_NULL);
1002 return thread_oop();
1003 }
1004
1005 char java_runtime_name[128] = "";
1006 char java_runtime_version[128] = "";
1007
1008 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1009 static const char* get_java_runtime_name(TRAPS) {
1010 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1011 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1012 fieldDescriptor fd;
1013 bool found = k != NULL &&
1014 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1015 vmSymbols::string_signature(), &fd);
1016 if (found) {
1017 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1018 if (name_oop == NULL) {
1019 return NULL;
1020 }
1021 const char* name = java_lang_String::as_utf8_string(name_oop,
1022 java_runtime_name,
1023 sizeof(java_runtime_name));
1024 return name;
1025 } else {
1026 return NULL;
1027 }
1028 }
1029
1030 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1031 static const char* get_java_runtime_version(TRAPS) {
1032 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1033 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1034 fieldDescriptor fd;
1035 bool found = k != NULL &&
1036 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1037 vmSymbols::string_signature(), &fd);
1038 if (found) {
1039 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1040 if (name_oop == NULL) {
1041 return NULL;
1042 }
1043 const char* name = java_lang_String::as_utf8_string(name_oop,
1044 java_runtime_version,
1045 sizeof(java_runtime_version));
1046 return name;
1047 } else {
1048 return NULL;
1049 }
1050 }
1051
1052 // General purpose hook into Java code, run once when the VM is initialized.
1053 // The Java library method itself may be changed independently from the VM.
1054 static void call_postVMInitHook(TRAPS) {
1055 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1056 instanceKlassHandle klass (THREAD, k);
1057 if (klass.not_null()) {
1058 JavaValue result(T_VOID);
1059 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1060 vmSymbols::void_method_signature(),
1061 CHECK);
1062 }
1063 }
1064
1065 static void reset_vm_info_property(TRAPS) {
1066 // the vm info string
1067 ResourceMark rm(THREAD);
1068 const char *vm_info = VM_Version::vm_info_string();
1069
1070 // java.lang.System class
1071 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1072 instanceKlassHandle klass (THREAD, k);
1073
1074 // setProperty arguments
1075 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1076 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1077
1078 // return value
1079 JavaValue r(T_OBJECT);
1080
1081 // public static String setProperty(String key, String value);
1082 JavaCalls::call_static(&r,
1083 klass,
1084 vmSymbols::setProperty_name(),
1085 vmSymbols::string_string_string_signature(),
1086 key_str,
1087 value_str,
1088 CHECK);
1089 }
1090
1091
1092 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1093 bool daemon, TRAPS) {
1094 assert(thread_group.not_null(), "thread group should be specified");
1095 assert(threadObj() == NULL, "should only create Java thread object once");
1096
1097 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1098 instanceKlassHandle klass (THREAD, k);
1099 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1100
1101 java_lang_Thread::set_thread(thread_oop(), this);
1102 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1103 set_threadObj(thread_oop());
1104
1105 JavaValue result(T_VOID);
1106 if (thread_name != NULL) {
1107 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1108 // Thread gets assigned specified name and null target
1109 JavaCalls::call_special(&result,
1110 thread_oop,
1111 klass,
1112 vmSymbols::object_initializer_name(),
1113 vmSymbols::threadgroup_string_void_signature(),
1114 thread_group, // Argument 1
1115 name, // Argument 2
1116 THREAD);
1117 } else {
1118 // Thread gets assigned name "Thread-nnn" and null target
1119 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1120 JavaCalls::call_special(&result,
1121 thread_oop,
1122 klass,
1123 vmSymbols::object_initializer_name(),
1124 vmSymbols::threadgroup_runnable_void_signature(),
1125 thread_group, // Argument 1
1126 Handle(), // Argument 2
1127 THREAD);
1128 }
1129
1130
1131 if (daemon) {
1132 java_lang_Thread::set_daemon(thread_oop());
1133 }
1134
1135 if (HAS_PENDING_EXCEPTION) {
1136 return;
1137 }
1138
1139 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1140 Handle threadObj(THREAD, this->threadObj());
1141
1142 JavaCalls::call_special(&result,
1143 thread_group,
1144 group,
1145 vmSymbols::add_method_name(),
1146 vmSymbols::thread_void_signature(),
1147 threadObj, // Arg 1
1148 THREAD);
1149 }
1150
1151 // NamedThread -- non-JavaThread subclasses with multiple
1152 // uniquely named instances should derive from this.
1153 NamedThread::NamedThread() : Thread() {
1154 _name = NULL;
1155 _processed_thread = NULL;
1156 _gc_id = GCId::undefined();
1157 }
1158
1159 NamedThread::~NamedThread() {
1160 if (_name != NULL) {
1161 FREE_C_HEAP_ARRAY(char, _name);
1162 _name = NULL;
1163 }
1164 }
1165
1166 void NamedThread::set_name(const char* format, ...) {
1167 guarantee(_name == NULL, "Only get to set name once.");
1168 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1169 guarantee(_name != NULL, "alloc failure");
1170 va_list ap;
1171 va_start(ap, format);
1172 jio_vsnprintf(_name, max_name_len, format, ap);
1173 va_end(ap);
1174 }
1175
1176 void NamedThread::initialize_named_thread() {
1177 set_native_thread_name(name());
1178 }
1179
1180 void NamedThread::print_on(outputStream* st) const {
1181 st->print("\"%s\" ", name());
1182 Thread::print_on(st);
1183 st->cr();
1184 }
1185
1186
1187 // ======= WatcherThread ========
1188
1189 // The watcher thread exists to simulate timer interrupts. It should
1190 // be replaced by an abstraction over whatever native support for
1191 // timer interrupts exists on the platform.
1192
1193 WatcherThread* WatcherThread::_watcher_thread = NULL;
1194 bool WatcherThread::_startable = false;
1195 volatile bool WatcherThread::_should_terminate = false;
1196
1197 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1198 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1199 if (os::create_thread(this, os::watcher_thread)) {
1200 _watcher_thread = this;
1201
1202 // Set the watcher thread to the highest OS priority which should not be
1203 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1204 // is created. The only normal thread using this priority is the reference
1205 // handler thread, which runs for very short intervals only.
1206 // If the VMThread's priority is not lower than the WatcherThread profiling
1207 // will be inaccurate.
1208 os::set_priority(this, MaxPriority);
1209 if (!DisableStartThread) {
1210 os::start_thread(this);
1211 }
1212 }
1213 }
1214
1215 int WatcherThread::sleep() const {
1216 // The WatcherThread does not participate in the safepoint protocol
1217 // for the PeriodicTask_lock because it is not a JavaThread.
1218 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1219
1220 if (_should_terminate) {
1221 // check for termination before we do any housekeeping or wait
1222 return 0; // we did not sleep.
1223 }
1224
1225 // remaining will be zero if there are no tasks,
1226 // causing the WatcherThread to sleep until a task is
1227 // enrolled
1228 int remaining = PeriodicTask::time_to_wait();
1229 int time_slept = 0;
1230
1231 // we expect this to timeout - we only ever get unparked when
1232 // we should terminate or when a new task has been enrolled
1233 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1234
1235 jlong time_before_loop = os::javaTimeNanos();
1236
1237 while (true) {
1238 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1239 remaining);
1240 jlong now = os::javaTimeNanos();
1241
1242 if (remaining == 0) {
1243 // if we didn't have any tasks we could have waited for a long time
1244 // consider the time_slept zero and reset time_before_loop
1245 time_slept = 0;
1246 time_before_loop = now;
1247 } else {
1248 // need to recalculate since we might have new tasks in _tasks
1249 time_slept = (int) ((now - time_before_loop) / 1000000);
1250 }
1251
1252 // Change to task list or spurious wakeup of some kind
1253 if (timedout || _should_terminate) {
1254 break;
1255 }
1256
1257 remaining = PeriodicTask::time_to_wait();
1258 if (remaining == 0) {
1259 // Last task was just disenrolled so loop around and wait until
1260 // another task gets enrolled
1261 continue;
1262 }
1263
1264 remaining -= time_slept;
1265 if (remaining <= 0) {
1266 break;
1267 }
1268 }
1269
1270 return time_slept;
1271 }
1272
1273 void WatcherThread::run() {
1274 assert(this == watcher_thread(), "just checking");
1275
1276 this->record_stack_base_and_size();
1277 this->set_native_thread_name(this->name());
1278 this->set_active_handles(JNIHandleBlock::allocate_block());
1279 while (true) {
1280 assert(watcher_thread() == Thread::current(), "thread consistency check");
1281 assert(watcher_thread() == this, "thread consistency check");
1282
1283 // Calculate how long it'll be until the next PeriodicTask work
1284 // should be done, and sleep that amount of time.
1285 int time_waited = sleep();
1286
1287 if (is_error_reported()) {
1288 // A fatal error has happened, the error handler(VMError::report_and_die)
1289 // should abort JVM after creating an error log file. However in some
1290 // rare cases, the error handler itself might deadlock. Here we try to
1291 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1292 //
1293 // This code is in WatcherThread because WatcherThread wakes up
1294 // periodically so the fatal error handler doesn't need to do anything;
1295 // also because the WatcherThread is less likely to crash than other
1296 // threads.
1297
1298 for (;;) {
1299 if (!ShowMessageBoxOnError
1300 && (OnError == NULL || OnError[0] == '\0')
1301 && Arguments::abort_hook() == NULL) {
1302 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1303 fdStream err(defaultStream::output_fd());
1304 err.print_raw_cr("# [ timer expired, abort... ]");
1305 // skip atexit/vm_exit/vm_abort hooks
1306 os::die();
1307 }
1308
1309 // Wake up 5 seconds later, the fatal handler may reset OnError or
1310 // ShowMessageBoxOnError when it is ready to abort.
1311 os::sleep(this, 5 * 1000, false);
1312 }
1313 }
1314
1315 if (_should_terminate) {
1316 // check for termination before posting the next tick
1317 break;
1318 }
1319
1320 PeriodicTask::real_time_tick(time_waited);
1321 }
1322
1323 // Signal that it is terminated
1324 {
1325 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1326 _watcher_thread = NULL;
1327 Terminator_lock->notify();
1328 }
1329
1330 // Deletion is done synchronously by the thread terminating the VM
1331 // so that the WatcherThread deletion doesn't race with that thread as it
1332 // tears down VM resources. That means 'this' may already have been
1333 // deallocated so we can't reference it. However we must do some cleanup
1334 // ourselves before allowing the native thread to terminate
1335
1336 ThreadLocalStorage::set_thread(NULL);
1337
1338 }
1339
1340 void WatcherThread::start() {
1341 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1342
1343 if (watcher_thread() == NULL && _startable) {
1344 _should_terminate = false;
1345 // Create the single instance of WatcherThread
1346 new WatcherThread();
1347 }
1348 }
1349
1350 void WatcherThread::make_startable() {
1351 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1352 _startable = true;
1353 }
1354
1355 void WatcherThread::stop() {
1356 WatcherThread* watcher = NULL;
1357 {
1358 // Follow normal safepoint aware lock enter protocol since the
1359 // WatcherThread is stopped by another JavaThread.
1360 MutexLocker ml(PeriodicTask_lock);
1361 _should_terminate = true;
1362
1363 watcher = watcher_thread();
1364 if (watcher != NULL) {
1365 // unpark the WatcherThread so it can see that it should terminate
1366 watcher->unpark();
1367 }
1368 }
1369
1370 MutexLocker mu(Terminator_lock);
1371
1372 while (watcher_thread() != NULL) {
1373 // This wait should make safepoint checks, wait without a timeout,
1374 // and wait as a suspend-equivalent condition.
1375 //
1376 // Note: If the FlatProfiler is running, then this thread is waiting
1377 // for the WatcherThread to terminate and the WatcherThread, via the
1378 // FlatProfiler task, is waiting for the external suspend request on
1379 // this thread to complete. wait_for_ext_suspend_completion() will
1380 // eventually timeout, but that takes time. Making this wait a
1381 // suspend-equivalent condition solves that timeout problem.
1382 //
1383 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1384 Mutex::_as_suspend_equivalent_flag);
1385 }
1386
1387 // can't get here till the WatcherThread has indicated it is terminating
1388 if (watcher != NULL)
1389 delete watcher;
1390 }
1391
1392 void WatcherThread::unpark() {
1393 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1394 PeriodicTask_lock->notify();
1395 }
1396
1397 void WatcherThread::print_on(outputStream* st) const {
1398 st->print("\"%s\" ", name());
1399 Thread::print_on(st);
1400 st->cr();
1401 }
1402
1403 // ======= JavaThread ========
1404
1405 #if INCLUDE_JVMCI
1406
1407 jlong* JavaThread::_jvmci_old_thread_counters;
1408
1409 bool jvmci_counters_include(JavaThread* thread) {
1410 oop threadObj = thread->threadObj();
1411 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1412 }
1413
1414 void JavaThread::collect_counters(typeArrayOop array) {
1415 if (JVMCICounterSize > 0) {
1416 MutexLocker tl(Threads_lock);
1417 for (int i = 0; i < array->length(); i++) {
1418 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1419 }
1420 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1421 if (jvmci_counters_include(tp)) {
1422 for (int i = 0; i < array->length(); i++) {
1423 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1424 }
1425 }
1426 }
1427 }
1428 }
1429
1430 #endif // INCLUDE_JVMCI
1431
1432 // A JavaThread is a normal Java thread
1433
1434 void JavaThread::initialize() {
1435 // Initialize fields
1436
1437 set_saved_exception_pc(NULL);
1438 set_threadObj(NULL);
1439 _anchor.clear();
1440 set_entry_point(NULL);
1441 set_jni_functions(jni_functions());
1442 set_callee_target(NULL);
1443 set_vm_result(NULL);
1444 set_vm_result_2(NULL);
1445 set_vframe_array_head(NULL);
1446 set_vframe_array_last(NULL);
1447 set_deferred_locals(NULL);
1448 set_deopt_mark(NULL);
1449 set_deopt_nmethod(NULL);
1450 clear_must_deopt_id();
1451 set_monitor_chunks(NULL);
1452 set_next(NULL);
1453 set_thread_state(_thread_new);
1454 _terminated = _not_terminated;
1455 _privileged_stack_top = NULL;
1456 _array_for_gc = NULL;
1457 _suspend_equivalent = false;
1458 _in_deopt_handler = 0;
1459 _doing_unsafe_access = false;
1460 _stack_guard_state = stack_guard_unused;
1461 #if INCLUDE_JVMCI
1462 _pending_monitorenter = false;
1463 _pending_deoptimization = -1;
1464 _pending_failed_speculation = NULL;
1465 _pending_transfer_to_interpreter = false;
1466 _jvmci._alternate_call_target = NULL;
1467 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1468 if (JVMCICounterSize > 0) {
1469 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1470 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1471 } else {
1472 _jvmci_counters = NULL;
1473 }
1474 #endif // INCLUDE_JVMCI
1475 _reserved_stack_activation = NULL; // stack base not known yet
1476 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1477 _exception_pc = 0;
1478 _exception_handler_pc = 0;
1479 _is_method_handle_return = 0;
1480 _jvmti_thread_state= NULL;
1481 _should_post_on_exceptions_flag = JNI_FALSE;
1482 _jvmti_get_loaded_classes_closure = NULL;
1483 _interp_only_mode = 0;
1484 _special_runtime_exit_condition = _no_async_condition;
1485 _pending_async_exception = NULL;
1486 _thread_stat = NULL;
1487 _thread_stat = new ThreadStatistics();
1488 _blocked_on_compilation = false;
1489 _jni_active_critical = 0;
1490 _pending_jni_exception_check_fn = NULL;
1491 _do_not_unlock_if_synchronized = false;
1492 _cached_monitor_info = NULL;
1493 _parker = Parker::Allocate(this);
1494
1495 #ifndef PRODUCT
1496 _jmp_ring_index = 0;
1497 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1498 record_jump(NULL, NULL, NULL, 0);
1499 }
1500 #endif // PRODUCT
1501
1502 set_thread_profiler(NULL);
1503 if (FlatProfiler::is_active()) {
1504 // This is where we would decide to either give each thread it's own profiler
1505 // or use one global one from FlatProfiler,
1506 // or up to some count of the number of profiled threads, etc.
1507 ThreadProfiler* pp = new ThreadProfiler();
1508 pp->engage();
1509 set_thread_profiler(pp);
1510 }
1511
1512 // Setup safepoint state info for this thread
1513 ThreadSafepointState::create(this);
1514
1515 debug_only(_java_call_counter = 0);
1516
1517 // JVMTI PopFrame support
1518 _popframe_condition = popframe_inactive;
1519 _popframe_preserved_args = NULL;
1520 _popframe_preserved_args_size = 0;
1521 _frames_to_pop_failed_realloc = 0;
1522
1523 pd_initialize();
1524 }
1525
1526 #if INCLUDE_ALL_GCS
1527 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1528 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1529 #endif // INCLUDE_ALL_GCS
1530
1531 JavaThread::JavaThread(bool is_attaching_via_jni) :
1532 Thread()
1533 #if INCLUDE_ALL_GCS
1534 , _satb_mark_queue(&_satb_mark_queue_set),
1535 _dirty_card_queue(&_dirty_card_queue_set)
1536 #endif // INCLUDE_ALL_GCS
1537 {
1538 initialize();
1539 if (is_attaching_via_jni) {
1540 _jni_attach_state = _attaching_via_jni;
1541 } else {
1542 _jni_attach_state = _not_attaching_via_jni;
1543 }
1544 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1545 }
1546
1547 bool JavaThread::reguard_stack(address cur_sp) {
1548 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1549 && _stack_guard_state != stack_guard_reserved_disabled) {
1550 return true; // Stack already guarded or guard pages not needed.
1551 }
1552
1553 if (register_stack_overflow()) {
1554 // For those architectures which have separate register and
1555 // memory stacks, we must check the register stack to see if
1556 // it has overflowed.
1557 return false;
1558 }
1559
1560 // Java code never executes within the yellow zone: the latter is only
1561 // there to provoke an exception during stack banging. If java code
1562 // is executing there, either StackShadowPages should be larger, or
1563 // some exception code in c1, c2 or the interpreter isn't unwinding
1564 // when it should.
1565 guarantee(cur_sp > stack_reserved_zone_base(),
1566 "not enough space to reguard - increase StackShadowPages");
1567 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1568 enable_stack_yellow_reserved_zone();
1569 if (reserved_stack_activation() != stack_base()) {
1570 set_reserved_stack_activation(stack_base());
1571 }
1572 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1573 set_reserved_stack_activation(stack_base());
1574 enable_stack_reserved_zone();
1575 }
1576 return true;
1577 }
1578
1579 bool JavaThread::reguard_stack(void) {
1580 return reguard_stack(os::current_stack_pointer());
1581 }
1582
1583
1584 void JavaThread::block_if_vm_exited() {
1585 if (_terminated == _vm_exited) {
1586 // _vm_exited is set at safepoint, and Threads_lock is never released
1587 // we will block here forever
1588 Threads_lock->lock_without_safepoint_check();
1589 ShouldNotReachHere();
1590 }
1591 }
1592
1593
1594 // Remove this ifdef when C1 is ported to the compiler interface.
1595 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1596 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1597
1598 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1599 Thread()
1600 #if INCLUDE_ALL_GCS
1601 , _satb_mark_queue(&_satb_mark_queue_set),
1602 _dirty_card_queue(&_dirty_card_queue_set)
1603 #endif // INCLUDE_ALL_GCS
1604 {
1605 initialize();
1606 _jni_attach_state = _not_attaching_via_jni;
1607 set_entry_point(entry_point);
1608 // Create the native thread itself.
1609 // %note runtime_23
1610 os::ThreadType thr_type = os::java_thread;
1611 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1612 os::java_thread;
1613 os::create_thread(this, thr_type, stack_sz);
1614 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1615 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1616 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1617 // the exception consists of creating the exception object & initializing it, initialization
1618 // will leave the VM via a JavaCall and then all locks must be unlocked).
1619 //
1620 // The thread is still suspended when we reach here. Thread must be explicit started
1621 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1622 // by calling Threads:add. The reason why this is not done here, is because the thread
1623 // object must be fully initialized (take a look at JVM_Start)
1624 }
1625
1626 JavaThread::~JavaThread() {
1627
1628 // JSR166 -- return the parker to the free list
1629 Parker::Release(_parker);
1630 _parker = NULL;
1631
1632 // Free any remaining previous UnrollBlock
1633 vframeArray* old_array = vframe_array_last();
1634
1635 if (old_array != NULL) {
1636 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1637 old_array->set_unroll_block(NULL);
1638 delete old_info;
1639 delete old_array;
1640 }
1641
1642 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1643 if (deferred != NULL) {
1644 // This can only happen if thread is destroyed before deoptimization occurs.
1645 assert(deferred->length() != 0, "empty array!");
1646 do {
1647 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1648 deferred->remove_at(0);
1649 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1650 delete dlv;
1651 } while (deferred->length() != 0);
1652 delete deferred;
1653 }
1654
1655 // All Java related clean up happens in exit
1656 ThreadSafepointState::destroy(this);
1657 if (_thread_profiler != NULL) delete _thread_profiler;
1658 if (_thread_stat != NULL) delete _thread_stat;
1659
1660 #if INCLUDE_JVMCI
1661 if (JVMCICounterSize > 0) {
1662 if (jvmci_counters_include(this)) {
1663 for (int i = 0; i < JVMCICounterSize; i++) {
1664 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1665 }
1666 }
1667 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1668 }
1669 #endif // INCLUDE_JVMCI
1670 }
1671
1672
1673 // The first routine called by a new Java thread
1674 void JavaThread::run() {
1675 // initialize thread-local alloc buffer related fields
1676 this->initialize_tlab();
1677
1678 // used to test validity of stack trace backs
1679 this->record_base_of_stack_pointer();
1680
1681 // Record real stack base and size.
1682 this->record_stack_base_and_size();
1683
1684 this->create_stack_guard_pages();
1685
1686 this->cache_global_variables();
1687
1688 // Thread is now sufficient initialized to be handled by the safepoint code as being
1689 // in the VM. Change thread state from _thread_new to _thread_in_vm
1690 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1691
1692 assert(JavaThread::current() == this, "sanity check");
1693 assert(!Thread::current()->owns_locks(), "sanity check");
1694
1695 DTRACE_THREAD_PROBE(start, this);
1696
1697 // This operation might block. We call that after all safepoint checks for a new thread has
1698 // been completed.
1699 this->set_active_handles(JNIHandleBlock::allocate_block());
1700
1701 if (JvmtiExport::should_post_thread_life()) {
1702 JvmtiExport::post_thread_start(this);
1703 }
1704
1705 EventThreadStart event;
1706 if (event.should_commit()) {
1707 event.set_thread(THREAD_TRACE_ID(this));
1708 event.commit();
1709 }
1710
1711 // We call another function to do the rest so we are sure that the stack addresses used
1712 // from there will be lower than the stack base just computed
1713 thread_main_inner();
1714
1715 // Note, thread is no longer valid at this point!
1716 }
1717
1718
1719 void JavaThread::thread_main_inner() {
1720 assert(JavaThread::current() == this, "sanity check");
1721 assert(this->threadObj() != NULL, "just checking");
1722
1723 // Execute thread entry point unless this thread has a pending exception
1724 // or has been stopped before starting.
1725 // Note: Due to JVM_StopThread we can have pending exceptions already!
1726 if (!this->has_pending_exception() &&
1727 !java_lang_Thread::is_stillborn(this->threadObj())) {
1728 {
1729 ResourceMark rm(this);
1730 this->set_native_thread_name(this->get_thread_name());
1731 }
1732 HandleMark hm(this);
1733 this->entry_point()(this, this);
1734 }
1735
1736 DTRACE_THREAD_PROBE(stop, this);
1737
1738 this->exit(false);
1739 delete this;
1740 }
1741
1742
1743 static void ensure_join(JavaThread* thread) {
1744 // We do not need to grap the Threads_lock, since we are operating on ourself.
1745 Handle threadObj(thread, thread->threadObj());
1746 assert(threadObj.not_null(), "java thread object must exist");
1747 ObjectLocker lock(threadObj, thread);
1748 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1749 thread->clear_pending_exception();
1750 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1751 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1752 // Clear the native thread instance - this makes isAlive return false and allows the join()
1753 // to complete once we've done the notify_all below
1754 java_lang_Thread::set_thread(threadObj(), NULL);
1755 lock.notify_all(thread);
1756 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1757 thread->clear_pending_exception();
1758 }
1759
1760
1761 // For any new cleanup additions, please check to see if they need to be applied to
1762 // cleanup_failed_attach_current_thread as well.
1763 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1764 assert(this == JavaThread::current(), "thread consistency check");
1765
1766 HandleMark hm(this);
1767 Handle uncaught_exception(this, this->pending_exception());
1768 this->clear_pending_exception();
1769 Handle threadObj(this, this->threadObj());
1770 assert(threadObj.not_null(), "Java thread object should be created");
1771
1772 if (get_thread_profiler() != NULL) {
1773 get_thread_profiler()->disengage();
1774 ResourceMark rm;
1775 get_thread_profiler()->print(get_thread_name());
1776 }
1777
1778
1779 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1780 {
1781 EXCEPTION_MARK;
1782
1783 CLEAR_PENDING_EXCEPTION;
1784 }
1785 if (!destroy_vm) {
1786 if (uncaught_exception.not_null()) {
1787 EXCEPTION_MARK;
1788 // Call method Thread.dispatchUncaughtException().
1789 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1790 JavaValue result(T_VOID);
1791 JavaCalls::call_virtual(&result,
1792 threadObj, thread_klass,
1793 vmSymbols::dispatchUncaughtException_name(),
1794 vmSymbols::throwable_void_signature(),
1795 uncaught_exception,
1796 THREAD);
1797 if (HAS_PENDING_EXCEPTION) {
1798 ResourceMark rm(this);
1799 jio_fprintf(defaultStream::error_stream(),
1800 "\nException: %s thrown from the UncaughtExceptionHandler"
1801 " in thread \"%s\"\n",
1802 pending_exception()->klass()->external_name(),
1803 get_thread_name());
1804 CLEAR_PENDING_EXCEPTION;
1805 }
1806 }
1807
1808 // Called before the java thread exit since we want to read info
1809 // from java_lang_Thread object
1810 EventThreadEnd event;
1811 if (event.should_commit()) {
1812 event.set_thread(THREAD_TRACE_ID(this));
1813 event.commit();
1814 }
1815
1816 // Call after last event on thread
1817 EVENT_THREAD_EXIT(this);
1818
1819 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1820 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1821 // is deprecated anyhow.
1822 if (!is_Compiler_thread()) {
1823 int count = 3;
1824 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1825 EXCEPTION_MARK;
1826 JavaValue result(T_VOID);
1827 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1828 JavaCalls::call_virtual(&result,
1829 threadObj, thread_klass,
1830 vmSymbols::exit_method_name(),
1831 vmSymbols::void_method_signature(),
1832 THREAD);
1833 CLEAR_PENDING_EXCEPTION;
1834 }
1835 }
1836 // notify JVMTI
1837 if (JvmtiExport::should_post_thread_life()) {
1838 JvmtiExport::post_thread_end(this);
1839 }
1840
1841 // We have notified the agents that we are exiting, before we go on,
1842 // we must check for a pending external suspend request and honor it
1843 // in order to not surprise the thread that made the suspend request.
1844 while (true) {
1845 {
1846 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1847 if (!is_external_suspend()) {
1848 set_terminated(_thread_exiting);
1849 ThreadService::current_thread_exiting(this);
1850 break;
1851 }
1852 // Implied else:
1853 // Things get a little tricky here. We have a pending external
1854 // suspend request, but we are holding the SR_lock so we
1855 // can't just self-suspend. So we temporarily drop the lock
1856 // and then self-suspend.
1857 }
1858
1859 ThreadBlockInVM tbivm(this);
1860 java_suspend_self();
1861
1862 // We're done with this suspend request, but we have to loop around
1863 // and check again. Eventually we will get SR_lock without a pending
1864 // external suspend request and will be able to mark ourselves as
1865 // exiting.
1866 }
1867 // no more external suspends are allowed at this point
1868 } else {
1869 // before_exit() has already posted JVMTI THREAD_END events
1870 }
1871
1872 // Notify waiters on thread object. This has to be done after exit() is called
1873 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1874 // group should have the destroyed bit set before waiters are notified).
1875 ensure_join(this);
1876 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1877
1878 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1879 // held by this thread must be released. The spec does not distinguish
1880 // between JNI-acquired and regular Java monitors. We can only see
1881 // regular Java monitors here if monitor enter-exit matching is broken.
1882 //
1883 // Optionally release any monitors for regular JavaThread exits. This
1884 // is provided as a work around for any bugs in monitor enter-exit
1885 // matching. This can be expensive so it is not enabled by default.
1886 //
1887 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1888 // ObjectSynchronizer::release_monitors_owned_by_thread().
1889 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1890 // Sanity check even though JNI DetachCurrentThread() would have
1891 // returned JNI_ERR if there was a Java frame. JavaThread exit
1892 // should be done executing Java code by the time we get here.
1893 assert(!this->has_last_Java_frame(),
1894 "should not have a Java frame when detaching or exiting");
1895 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1896 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1897 }
1898
1899 // These things needs to be done while we are still a Java Thread. Make sure that thread
1900 // is in a consistent state, in case GC happens
1901 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1902
1903 if (active_handles() != NULL) {
1904 JNIHandleBlock* block = active_handles();
1905 set_active_handles(NULL);
1906 JNIHandleBlock::release_block(block);
1907 }
1908
1909 if (free_handle_block() != NULL) {
1910 JNIHandleBlock* block = free_handle_block();
1911 set_free_handle_block(NULL);
1912 JNIHandleBlock::release_block(block);
1913 }
1914
1915 // These have to be removed while this is still a valid thread.
1916 remove_stack_guard_pages();
1917
1918 if (UseTLAB) {
1919 tlab().make_parsable(true); // retire TLAB
1920 }
1921
1922 if (JvmtiEnv::environments_might_exist()) {
1923 JvmtiExport::cleanup_thread(this);
1924 }
1925
1926 // We must flush any deferred card marks before removing a thread from
1927 // the list of active threads.
1928 Universe::heap()->flush_deferred_store_barrier(this);
1929 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1930
1931 #if INCLUDE_ALL_GCS
1932 // We must flush the G1-related buffers before removing a thread
1933 // from the list of active threads. We must do this after any deferred
1934 // card marks have been flushed (above) so that any entries that are
1935 // added to the thread's dirty card queue as a result are not lost.
1936 if (UseG1GC) {
1937 flush_barrier_queues();
1938 }
1939 #endif // INCLUDE_ALL_GCS
1940
1941 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1942 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1943 os::current_thread_id());
1944
1945 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1946 Threads::remove(this);
1947 }
1948
1949 #if INCLUDE_ALL_GCS
1950 // Flush G1-related queues.
1951 void JavaThread::flush_barrier_queues() {
1952 satb_mark_queue().flush();
1953 dirty_card_queue().flush();
1954 }
1955
1956 void JavaThread::initialize_queues() {
1957 assert(!SafepointSynchronize::is_at_safepoint(),
1958 "we should not be at a safepoint");
1959
1960 SATBMarkQueue& satb_queue = satb_mark_queue();
1961 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1962 // The SATB queue should have been constructed with its active
1963 // field set to false.
1964 assert(!satb_queue.is_active(), "SATB queue should not be active");
1965 assert(satb_queue.is_empty(), "SATB queue should be empty");
1966 // If we are creating the thread during a marking cycle, we should
1967 // set the active field of the SATB queue to true.
1968 if (satb_queue_set.is_active()) {
1969 satb_queue.set_active(true);
1970 }
1971
1972 DirtyCardQueue& dirty_queue = dirty_card_queue();
1973 // The dirty card queue should have been constructed with its
1974 // active field set to true.
1975 assert(dirty_queue.is_active(), "dirty card queue should be active");
1976 }
1977 #endif // INCLUDE_ALL_GCS
1978
1979 void JavaThread::cleanup_failed_attach_current_thread() {
1980 if (get_thread_profiler() != NULL) {
1981 get_thread_profiler()->disengage();
1982 ResourceMark rm;
1983 get_thread_profiler()->print(get_thread_name());
1984 }
1985
1986 if (active_handles() != NULL) {
1987 JNIHandleBlock* block = active_handles();
1988 set_active_handles(NULL);
1989 JNIHandleBlock::release_block(block);
1990 }
1991
1992 if (free_handle_block() != NULL) {
1993 JNIHandleBlock* block = free_handle_block();
1994 set_free_handle_block(NULL);
1995 JNIHandleBlock::release_block(block);
1996 }
1997
1998 // These have to be removed while this is still a valid thread.
1999 remove_stack_guard_pages();
2000
2001 if (UseTLAB) {
2002 tlab().make_parsable(true); // retire TLAB, if any
2003 }
2004
2005 #if INCLUDE_ALL_GCS
2006 if (UseG1GC) {
2007 flush_barrier_queues();
2008 }
2009 #endif // INCLUDE_ALL_GCS
2010
2011 Threads::remove(this);
2012 delete this;
2013 }
2014
2015
2016
2017
2018 JavaThread* JavaThread::active() {
2019 Thread* thread = Thread::current();
2020 if (thread->is_Java_thread()) {
2021 return (JavaThread*) thread;
2022 } else {
2023 assert(thread->is_VM_thread(), "this must be a vm thread");
2024 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2025 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2026 assert(ret->is_Java_thread(), "must be a Java thread");
2027 return ret;
2028 }
2029 }
2030
2031 bool JavaThread::is_lock_owned(address adr) const {
2032 if (Thread::is_lock_owned(adr)) return true;
2033
2034 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2035 if (chunk->contains(adr)) return true;
2036 }
2037
2038 return false;
2039 }
2040
2041
2042 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2043 chunk->set_next(monitor_chunks());
2044 set_monitor_chunks(chunk);
2045 }
2046
2047 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2048 guarantee(monitor_chunks() != NULL, "must be non empty");
2049 if (monitor_chunks() == chunk) {
2050 set_monitor_chunks(chunk->next());
2051 } else {
2052 MonitorChunk* prev = monitor_chunks();
2053 while (prev->next() != chunk) prev = prev->next();
2054 prev->set_next(chunk->next());
2055 }
2056 }
2057
2058 // JVM support.
2059
2060 // Note: this function shouldn't block if it's called in
2061 // _thread_in_native_trans state (such as from
2062 // check_special_condition_for_native_trans()).
2063 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2064
2065 if (has_last_Java_frame() && has_async_condition()) {
2066 // If we are at a polling page safepoint (not a poll return)
2067 // then we must defer async exception because live registers
2068 // will be clobbered by the exception path. Poll return is
2069 // ok because the call we a returning from already collides
2070 // with exception handling registers and so there is no issue.
2071 // (The exception handling path kills call result registers but
2072 // this is ok since the exception kills the result anyway).
2073
2074 if (is_at_poll_safepoint()) {
2075 // if the code we are returning to has deoptimized we must defer
2076 // the exception otherwise live registers get clobbered on the
2077 // exception path before deoptimization is able to retrieve them.
2078 //
2079 RegisterMap map(this, false);
2080 frame caller_fr = last_frame().sender(&map);
2081 assert(caller_fr.is_compiled_frame(), "what?");
2082 if (caller_fr.is_deoptimized_frame()) {
2083 log_info(exceptions)("deferred async exception at compiled safepoint");
2084 return;
2085 }
2086 }
2087 }
2088
2089 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2090 if (condition == _no_async_condition) {
2091 // Conditions have changed since has_special_runtime_exit_condition()
2092 // was called:
2093 // - if we were here only because of an external suspend request,
2094 // then that was taken care of above (or cancelled) so we are done
2095 // - if we were here because of another async request, then it has
2096 // been cleared between the has_special_runtime_exit_condition()
2097 // and now so again we are done
2098 return;
2099 }
2100
2101 // Check for pending async. exception
2102 if (_pending_async_exception != NULL) {
2103 // Only overwrite an already pending exception, if it is not a threadDeath.
2104 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2105
2106 // We cannot call Exceptions::_throw(...) here because we cannot block
2107 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2108
2109 if (log_is_enabled(Info, exceptions)) {
2110 ResourceMark rm;
2111 outputStream* logstream = Log(exceptions)::info_stream();
2112 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2113 if (has_last_Java_frame()) {
2114 frame f = last_frame();
2115 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2116 }
2117 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2118 }
2119 _pending_async_exception = NULL;
2120 clear_has_async_exception();
2121 }
2122 }
2123
2124 if (check_unsafe_error &&
2125 condition == _async_unsafe_access_error && !has_pending_exception()) {
2126 condition = _no_async_condition; // done
2127 switch (thread_state()) {
2128 case _thread_in_vm: {
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_native: {
2133 ThreadInVMfromNative tiv(this);
2134 JavaThread* THREAD = this;
2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2136 }
2137 case _thread_in_Java: {
2138 ThreadInVMfromJava tiv(this);
2139 JavaThread* THREAD = this;
2140 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2141 }
2142 default:
2143 ShouldNotReachHere();
2144 }
2145 }
2146
2147 assert(condition == _no_async_condition || has_pending_exception() ||
2148 (!check_unsafe_error && condition == _async_unsafe_access_error),
2149 "must have handled the async condition, if no exception");
2150 }
2151
2152 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2153 //
2154 // Check for pending external suspend. Internal suspend requests do
2155 // not use handle_special_runtime_exit_condition().
2156 // If JNIEnv proxies are allowed, don't self-suspend if the target
2157 // thread is not the current thread. In older versions of jdbx, jdbx
2158 // threads could call into the VM with another thread's JNIEnv so we
2159 // can be here operating on behalf of a suspended thread (4432884).
2160 bool do_self_suspend = is_external_suspend_with_lock();
2161 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2162 //
2163 // Because thread is external suspended the safepoint code will count
2164 // thread as at a safepoint. This can be odd because we can be here
2165 // as _thread_in_Java which would normally transition to _thread_blocked
2166 // at a safepoint. We would like to mark the thread as _thread_blocked
2167 // before calling java_suspend_self like all other callers of it but
2168 // we must then observe proper safepoint protocol. (We can't leave
2169 // _thread_blocked with a safepoint in progress). However we can be
2170 // here as _thread_in_native_trans so we can't use a normal transition
2171 // constructor/destructor pair because they assert on that type of
2172 // transition. We could do something like:
2173 //
2174 // JavaThreadState state = thread_state();
2175 // set_thread_state(_thread_in_vm);
2176 // {
2177 // ThreadBlockInVM tbivm(this);
2178 // java_suspend_self()
2179 // }
2180 // set_thread_state(_thread_in_vm_trans);
2181 // if (safepoint) block;
2182 // set_thread_state(state);
2183 //
2184 // but that is pretty messy. Instead we just go with the way the
2185 // code has worked before and note that this is the only path to
2186 // java_suspend_self that doesn't put the thread in _thread_blocked
2187 // mode.
2188
2189 frame_anchor()->make_walkable(this);
2190 java_suspend_self();
2191
2192 // We might be here for reasons in addition to the self-suspend request
2193 // so check for other async requests.
2194 }
2195
2196 if (check_asyncs) {
2197 check_and_handle_async_exceptions();
2198 }
2199 }
2200
2201 void JavaThread::send_thread_stop(oop java_throwable) {
2202 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2203 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2204 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2205
2206 // Do not throw asynchronous exceptions against the compiler thread
2207 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2208 if (!can_call_java()) return;
2209
2210 {
2211 // Actually throw the Throwable against the target Thread - however
2212 // only if there is no thread death exception installed already.
2213 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2214 // If the topmost frame is a runtime stub, then we are calling into
2215 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2216 // must deoptimize the caller before continuing, as the compiled exception handler table
2217 // may not be valid
2218 if (has_last_Java_frame()) {
2219 frame f = last_frame();
2220 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2221 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2222 RegisterMap reg_map(this, UseBiasedLocking);
2223 frame compiled_frame = f.sender(®_map);
2224 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2225 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2226 }
2227 }
2228 }
2229
2230 // Set async. pending exception in thread.
2231 set_pending_async_exception(java_throwable);
2232
2233 if (log_is_enabled(Info, exceptions)) {
2234 ResourceMark rm;
2235 log_info(exceptions)("Pending Async. exception installed of type: %s",
2236 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2237 }
2238 // for AbortVMOnException flag
2239 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2240 }
2241 }
2242
2243
2244 // Interrupt thread so it will wake up from a potential wait()
2245 Thread::interrupt(this);
2246 }
2247
2248 // External suspension mechanism.
2249 //
2250 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2251 // to any VM_locks and it is at a transition
2252 // Self-suspension will happen on the transition out of the vm.
2253 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2254 //
2255 // Guarantees on return:
2256 // + Target thread will not execute any new bytecode (that's why we need to
2257 // force a safepoint)
2258 // + Target thread will not enter any new monitors
2259 //
2260 void JavaThread::java_suspend() {
2261 { MutexLocker mu(Threads_lock);
2262 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2263 return;
2264 }
2265 }
2266
2267 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2268 if (!is_external_suspend()) {
2269 // a racing resume has cancelled us; bail out now
2270 return;
2271 }
2272
2273 // suspend is done
2274 uint32_t debug_bits = 0;
2275 // Warning: is_ext_suspend_completed() may temporarily drop the
2276 // SR_lock to allow the thread to reach a stable thread state if
2277 // it is currently in a transient thread state.
2278 if (is_ext_suspend_completed(false /* !called_by_wait */,
2279 SuspendRetryDelay, &debug_bits)) {
2280 return;
2281 }
2282 }
2283
2284 VM_ForceSafepoint vm_suspend;
2285 VMThread::execute(&vm_suspend);
2286 }
2287
2288 // Part II of external suspension.
2289 // A JavaThread self suspends when it detects a pending external suspend
2290 // request. This is usually on transitions. It is also done in places
2291 // where continuing to the next transition would surprise the caller,
2292 // e.g., monitor entry.
2293 //
2294 // Returns the number of times that the thread self-suspended.
2295 //
2296 // Note: DO NOT call java_suspend_self() when you just want to block current
2297 // thread. java_suspend_self() is the second stage of cooperative
2298 // suspension for external suspend requests and should only be used
2299 // to complete an external suspend request.
2300 //
2301 int JavaThread::java_suspend_self() {
2302 int ret = 0;
2303
2304 // we are in the process of exiting so don't suspend
2305 if (is_exiting()) {
2306 clear_external_suspend();
2307 return ret;
2308 }
2309
2310 assert(_anchor.walkable() ||
2311 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2312 "must have walkable stack");
2313
2314 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2315
2316 assert(!this->is_ext_suspended(),
2317 "a thread trying to self-suspend should not already be suspended");
2318
2319 if (this->is_suspend_equivalent()) {
2320 // If we are self-suspending as a result of the lifting of a
2321 // suspend equivalent condition, then the suspend_equivalent
2322 // flag is not cleared until we set the ext_suspended flag so
2323 // that wait_for_ext_suspend_completion() returns consistent
2324 // results.
2325 this->clear_suspend_equivalent();
2326 }
2327
2328 // A racing resume may have cancelled us before we grabbed SR_lock
2329 // above. Or another external suspend request could be waiting for us
2330 // by the time we return from SR_lock()->wait(). The thread
2331 // that requested the suspension may already be trying to walk our
2332 // stack and if we return now, we can change the stack out from under
2333 // it. This would be a "bad thing (TM)" and cause the stack walker
2334 // to crash. We stay self-suspended until there are no more pending
2335 // external suspend requests.
2336 while (is_external_suspend()) {
2337 ret++;
2338 this->set_ext_suspended();
2339
2340 // _ext_suspended flag is cleared by java_resume()
2341 while (is_ext_suspended()) {
2342 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2343 }
2344 }
2345
2346 return ret;
2347 }
2348
2349 #ifdef ASSERT
2350 // verify the JavaThread has not yet been published in the Threads::list, and
2351 // hence doesn't need protection from concurrent access at this stage
2352 void JavaThread::verify_not_published() {
2353 if (!Threads_lock->owned_by_self()) {
2354 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2355 assert(!Threads::includes(this),
2356 "java thread shouldn't have been published yet!");
2357 } else {
2358 assert(!Threads::includes(this),
2359 "java thread shouldn't have been published yet!");
2360 }
2361 }
2362 #endif
2363
2364 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2365 // progress or when _suspend_flags is non-zero.
2366 // Current thread needs to self-suspend if there is a suspend request and/or
2367 // block if a safepoint is in progress.
2368 // Async exception ISN'T checked.
2369 // Note only the ThreadInVMfromNative transition can call this function
2370 // directly and when thread state is _thread_in_native_trans
2371 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2372 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2373
2374 JavaThread *curJT = JavaThread::current();
2375 bool do_self_suspend = thread->is_external_suspend();
2376
2377 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2378
2379 // If JNIEnv proxies are allowed, don't self-suspend if the target
2380 // thread is not the current thread. In older versions of jdbx, jdbx
2381 // threads could call into the VM with another thread's JNIEnv so we
2382 // can be here operating on behalf of a suspended thread (4432884).
2383 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2384 JavaThreadState state = thread->thread_state();
2385
2386 // We mark this thread_blocked state as a suspend-equivalent so
2387 // that a caller to is_ext_suspend_completed() won't be confused.
2388 // The suspend-equivalent state is cleared by java_suspend_self().
2389 thread->set_suspend_equivalent();
2390
2391 // If the safepoint code sees the _thread_in_native_trans state, it will
2392 // wait until the thread changes to other thread state. There is no
2393 // guarantee on how soon we can obtain the SR_lock and complete the
2394 // self-suspend request. It would be a bad idea to let safepoint wait for
2395 // too long. Temporarily change the state to _thread_blocked to
2396 // let the VM thread know that this thread is ready for GC. The problem
2397 // of changing thread state is that safepoint could happen just after
2398 // java_suspend_self() returns after being resumed, and VM thread will
2399 // see the _thread_blocked state. We must check for safepoint
2400 // after restoring the state and make sure we won't leave while a safepoint
2401 // is in progress.
2402 thread->set_thread_state(_thread_blocked);
2403 thread->java_suspend_self();
2404 thread->set_thread_state(state);
2405 // Make sure new state is seen by VM thread
2406 if (os::is_MP()) {
2407 if (UseMembar) {
2408 // Force a fence between the write above and read below
2409 OrderAccess::fence();
2410 } else {
2411 // Must use this rather than serialization page in particular on Windows
2412 InterfaceSupport::serialize_memory(thread);
2413 }
2414 }
2415 }
2416
2417 if (SafepointSynchronize::do_call_back()) {
2418 // If we are safepointing, then block the caller which may not be
2419 // the same as the target thread (see above).
2420 SafepointSynchronize::block(curJT);
2421 }
2422
2423 if (thread->is_deopt_suspend()) {
2424 thread->clear_deopt_suspend();
2425 RegisterMap map(thread, false);
2426 frame f = thread->last_frame();
2427 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2428 f = f.sender(&map);
2429 }
2430 if (f.id() == thread->must_deopt_id()) {
2431 thread->clear_must_deopt_id();
2432 f.deoptimize(thread);
2433 } else {
2434 fatal("missed deoptimization!");
2435 }
2436 }
2437 }
2438
2439 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2440 // progress or when _suspend_flags is non-zero.
2441 // Current thread needs to self-suspend if there is a suspend request and/or
2442 // block if a safepoint is in progress.
2443 // Also check for pending async exception (not including unsafe access error).
2444 // Note only the native==>VM/Java barriers can call this function and when
2445 // thread state is _thread_in_native_trans.
2446 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2447 check_safepoint_and_suspend_for_native_trans(thread);
2448
2449 if (thread->has_async_exception()) {
2450 // We are in _thread_in_native_trans state, don't handle unsafe
2451 // access error since that may block.
2452 thread->check_and_handle_async_exceptions(false);
2453 }
2454 }
2455
2456 // This is a variant of the normal
2457 // check_special_condition_for_native_trans with slightly different
2458 // semantics for use by critical native wrappers. It does all the
2459 // normal checks but also performs the transition back into
2460 // thread_in_Java state. This is required so that critical natives
2461 // can potentially block and perform a GC if they are the last thread
2462 // exiting the GCLocker.
2463 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2464 check_special_condition_for_native_trans(thread);
2465
2466 // Finish the transition
2467 thread->set_thread_state(_thread_in_Java);
2468
2469 if (thread->do_critical_native_unlock()) {
2470 ThreadInVMfromJavaNoAsyncException tiv(thread);
2471 GCLocker::unlock_critical(thread);
2472 thread->clear_critical_native_unlock();
2473 }
2474 }
2475
2476 // We need to guarantee the Threads_lock here, since resumes are not
2477 // allowed during safepoint synchronization
2478 // Can only resume from an external suspension
2479 void JavaThread::java_resume() {
2480 assert_locked_or_safepoint(Threads_lock);
2481
2482 // Sanity check: thread is gone, has started exiting or the thread
2483 // was not externally suspended.
2484 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2485 return;
2486 }
2487
2488 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2489
2490 clear_external_suspend();
2491
2492 if (is_ext_suspended()) {
2493 clear_ext_suspended();
2494 SR_lock()->notify_all();
2495 }
2496 }
2497
2498 size_t JavaThread::_stack_red_zone_size = 0;
2499 size_t JavaThread::_stack_yellow_zone_size = 0;
2500 size_t JavaThread::_stack_reserved_zone_size = 0;
2501 size_t JavaThread::_stack_shadow_zone_size = 0;
2502
2503 void JavaThread::create_stack_guard_pages() {
2504 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2505 address low_addr = stack_end();
2506 size_t len = stack_guard_zone_size();
2507
2508 int allocate = os::allocate_stack_guard_pages();
2509 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2510
2511 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2512 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2513 return;
2514 }
2515
2516 if (os::guard_memory((char *) low_addr, len)) {
2517 _stack_guard_state = stack_guard_enabled;
2518 } else {
2519 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2520 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2521 if (os::uncommit_memory((char *) low_addr, len)) {
2522 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2523 }
2524 return;
2525 }
2526
2527 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2528 PTR_FORMAT "-" PTR_FORMAT ".",
2529 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2530
2531 }
2532
2533 void JavaThread::remove_stack_guard_pages() {
2534 assert(Thread::current() == this, "from different thread");
2535 if (_stack_guard_state == stack_guard_unused) return;
2536 address low_addr = stack_end();
2537 size_t len = stack_guard_zone_size();
2538
2539 if (os::allocate_stack_guard_pages()) {
2540 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2541 _stack_guard_state = stack_guard_unused;
2542 } else {
2543 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2544 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2545 return;
2546 }
2547 } else {
2548 if (_stack_guard_state == stack_guard_unused) return;
2549 if (os::unguard_memory((char *) low_addr, len)) {
2550 _stack_guard_state = stack_guard_unused;
2551 } else {
2552 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2553 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2554 return;
2555 }
2556 }
2557
2558 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2559 PTR_FORMAT "-" PTR_FORMAT ".",
2560 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2561
2562 }
2563
2564 void JavaThread::enable_stack_reserved_zone() {
2565 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2566 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2567
2568 // The base notation is from the stack's point of view, growing downward.
2569 // We need to adjust it to work correctly with guard_memory()
2570 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2571
2572 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2573 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2574
2575 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2576 _stack_guard_state = stack_guard_enabled;
2577 } else {
2578 warning("Attempt to guard stack reserved zone failed.");
2579 }
2580 enable_register_stack_guard();
2581 }
2582
2583 void JavaThread::disable_stack_reserved_zone() {
2584 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2585 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2586
2587 // Simply return if called for a thread that does not use guard pages.
2588 if (_stack_guard_state == stack_guard_unused) return;
2589
2590 // The base notation is from the stack's point of view, growing downward.
2591 // We need to adjust it to work correctly with guard_memory()
2592 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2593
2594 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2595 _stack_guard_state = stack_guard_reserved_disabled;
2596 } else {
2597 warning("Attempt to unguard stack reserved zone failed.");
2598 }
2599 disable_register_stack_guard();
2600 }
2601
2602 void JavaThread::enable_stack_yellow_reserved_zone() {
2603 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2604 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2605
2606 // The base notation is from the stacks point of view, growing downward.
2607 // We need to adjust it to work correctly with guard_memory()
2608 address base = stack_red_zone_base();
2609
2610 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2611 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2612
2613 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2614 _stack_guard_state = stack_guard_enabled;
2615 } else {
2616 warning("Attempt to guard stack yellow zone failed.");
2617 }
2618 enable_register_stack_guard();
2619 }
2620
2621 void JavaThread::disable_stack_yellow_reserved_zone() {
2622 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2623 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2624
2625 // Simply return if called for a thread that does not use guard pages.
2626 if (_stack_guard_state == stack_guard_unused) return;
2627
2628 // The base notation is from the stacks point of view, growing downward.
2629 // We need to adjust it to work correctly with guard_memory()
2630 address base = stack_red_zone_base();
2631
2632 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2633 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2634 } else {
2635 warning("Attempt to unguard stack yellow zone failed.");
2636 }
2637 disable_register_stack_guard();
2638 }
2639
2640 void JavaThread::enable_stack_red_zone() {
2641 // The base notation is from the stacks point of view, growing downward.
2642 // We need to adjust it to work correctly with guard_memory()
2643 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2644 address base = stack_red_zone_base() - stack_red_zone_size();
2645
2646 guarantee(base < stack_base(), "Error calculating stack red zone");
2647 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2648
2649 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2650 warning("Attempt to guard stack red zone failed.");
2651 }
2652 }
2653
2654 void JavaThread::disable_stack_red_zone() {
2655 // The base notation is from the stacks point of view, growing downward.
2656 // We need to adjust it to work correctly with guard_memory()
2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658 address base = stack_red_zone_base() - stack_red_zone_size();
2659 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2660 warning("Attempt to unguard stack red zone failed.");
2661 }
2662 }
2663
2664 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2665 // ignore is there is no stack
2666 if (!has_last_Java_frame()) return;
2667 // traverse the stack frames. Starts from top frame.
2668 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2669 frame* fr = fst.current();
2670 f(fr, fst.register_map());
2671 }
2672 }
2673
2674
2675 #ifndef PRODUCT
2676 // Deoptimization
2677 // Function for testing deoptimization
2678 void JavaThread::deoptimize() {
2679 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2680 StackFrameStream fst(this, UseBiasedLocking);
2681 bool deopt = false; // Dump stack only if a deopt actually happens.
2682 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2683 // Iterate over all frames in the thread and deoptimize
2684 for (; !fst.is_done(); fst.next()) {
2685 if (fst.current()->can_be_deoptimized()) {
2686
2687 if (only_at) {
2688 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2689 // consists of comma or carriage return separated numbers so
2690 // search for the current bci in that string.
2691 address pc = fst.current()->pc();
2692 nmethod* nm = (nmethod*) fst.current()->cb();
2693 ScopeDesc* sd = nm->scope_desc_at(pc);
2694 char buffer[8];
2695 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2696 size_t len = strlen(buffer);
2697 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2698 while (found != NULL) {
2699 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2700 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2701 // Check that the bci found is bracketed by terminators.
2702 break;
2703 }
2704 found = strstr(found + 1, buffer);
2705 }
2706 if (!found) {
2707 continue;
2708 }
2709 }
2710
2711 if (DebugDeoptimization && !deopt) {
2712 deopt = true; // One-time only print before deopt
2713 tty->print_cr("[BEFORE Deoptimization]");
2714 trace_frames();
2715 trace_stack();
2716 }
2717 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2718 }
2719 }
2720
2721 if (DebugDeoptimization && deopt) {
2722 tty->print_cr("[AFTER Deoptimization]");
2723 trace_frames();
2724 }
2725 }
2726
2727
2728 // Make zombies
2729 void JavaThread::make_zombies() {
2730 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2731 if (fst.current()->can_be_deoptimized()) {
2732 // it is a Java nmethod
2733 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2734 nm->make_not_entrant();
2735 }
2736 }
2737 }
2738 #endif // PRODUCT
2739
2740
2741 void JavaThread::deoptimized_wrt_marked_nmethods() {
2742 if (!has_last_Java_frame()) return;
2743 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2744 StackFrameStream fst(this, UseBiasedLocking);
2745 for (; !fst.is_done(); fst.next()) {
2746 if (fst.current()->should_be_deoptimized()) {
2747 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2748 }
2749 }
2750 }
2751
2752
2753 // If the caller is a NamedThread, then remember, in the current scope,
2754 // the given JavaThread in its _processed_thread field.
2755 class RememberProcessedThread: public StackObj {
2756 NamedThread* _cur_thr;
2757 public:
2758 RememberProcessedThread(JavaThread* jthr) {
2759 Thread* thread = Thread::current();
2760 if (thread->is_Named_thread()) {
2761 _cur_thr = (NamedThread *)thread;
2762 _cur_thr->set_processed_thread(jthr);
2763 } else {
2764 _cur_thr = NULL;
2765 }
2766 }
2767
2768 ~RememberProcessedThread() {
2769 if (_cur_thr) {
2770 _cur_thr->set_processed_thread(NULL);
2771 }
2772 }
2773 };
2774
2775 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2776 // Verify that the deferred card marks have been flushed.
2777 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2778
2779 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2780 // since there may be more than one thread using each ThreadProfiler.
2781
2782 // Traverse the GCHandles
2783 Thread::oops_do(f, cf);
2784
2785 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2786
2787 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2788 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2789
2790 if (has_last_Java_frame()) {
2791 // Record JavaThread to GC thread
2792 RememberProcessedThread rpt(this);
2793
2794 // Traverse the privileged stack
2795 if (_privileged_stack_top != NULL) {
2796 _privileged_stack_top->oops_do(f);
2797 }
2798
2799 // traverse the registered growable array
2800 if (_array_for_gc != NULL) {
2801 for (int index = 0; index < _array_for_gc->length(); index++) {
2802 f->do_oop(_array_for_gc->adr_at(index));
2803 }
2804 }
2805
2806 // Traverse the monitor chunks
2807 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2808 chunk->oops_do(f);
2809 }
2810
2811 // Traverse the execution stack
2812 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2813 fst.current()->oops_do(f, cf, fst.register_map());
2814 }
2815 }
2816
2817 // callee_target is never live across a gc point so NULL it here should
2818 // it still contain a methdOop.
2819
2820 set_callee_target(NULL);
2821
2822 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2823 // If we have deferred set_locals there might be oops waiting to be
2824 // written
2825 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2826 if (list != NULL) {
2827 for (int i = 0; i < list->length(); i++) {
2828 list->at(i)->oops_do(f);
2829 }
2830 }
2831
2832 // Traverse instance variables at the end since the GC may be moving things
2833 // around using this function
2834 f->do_oop((oop*) &_threadObj);
2835 f->do_oop((oop*) &_vm_result);
2836 f->do_oop((oop*) &_exception_oop);
2837 f->do_oop((oop*) &_pending_async_exception);
2838
2839 if (jvmti_thread_state() != NULL) {
2840 jvmti_thread_state()->oops_do(f);
2841 }
2842 }
2843
2844 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2845 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2846 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2847
2848 if (has_last_Java_frame()) {
2849 // Traverse the execution stack
2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851 fst.current()->nmethods_do(cf);
2852 }
2853 }
2854 }
2855
2856 void JavaThread::metadata_do(void f(Metadata*)) {
2857 if (has_last_Java_frame()) {
2858 // Traverse the execution stack to call f() on the methods in the stack
2859 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2860 fst.current()->metadata_do(f);
2861 }
2862 } else if (is_Compiler_thread()) {
2863 // need to walk ciMetadata in current compile tasks to keep alive.
2864 CompilerThread* ct = (CompilerThread*)this;
2865 if (ct->env() != NULL) {
2866 ct->env()->metadata_do(f);
2867 }
2868 if (ct->task() != NULL) {
2869 ct->task()->metadata_do(f);
2870 }
2871 }
2872 }
2873
2874 // Printing
2875 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2876 switch (_thread_state) {
2877 case _thread_uninitialized: return "_thread_uninitialized";
2878 case _thread_new: return "_thread_new";
2879 case _thread_new_trans: return "_thread_new_trans";
2880 case _thread_in_native: return "_thread_in_native";
2881 case _thread_in_native_trans: return "_thread_in_native_trans";
2882 case _thread_in_vm: return "_thread_in_vm";
2883 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2884 case _thread_in_Java: return "_thread_in_Java";
2885 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2886 case _thread_blocked: return "_thread_blocked";
2887 case _thread_blocked_trans: return "_thread_blocked_trans";
2888 default: return "unknown thread state";
2889 }
2890 }
2891
2892 #ifndef PRODUCT
2893 void JavaThread::print_thread_state_on(outputStream *st) const {
2894 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2895 };
2896 void JavaThread::print_thread_state() const {
2897 print_thread_state_on(tty);
2898 }
2899 #endif // PRODUCT
2900
2901 // Called by Threads::print() for VM_PrintThreads operation
2902 void JavaThread::print_on(outputStream *st) const {
2903 st->print_raw("\"");
2904 st->print_raw(get_thread_name());
2905 st->print_raw("\" ");
2906 oop thread_oop = threadObj();
2907 if (thread_oop != NULL) {
2908 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2909 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2910 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2911 }
2912 Thread::print_on(st);
2913 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2914 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2915 if (thread_oop != NULL) {
2916 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2917 }
2918 #ifndef PRODUCT
2919 print_thread_state_on(st);
2920 _safepoint_state->print_on(st);
2921 #endif // PRODUCT
2922 if (is_Compiler_thread()) {
2923 CompilerThread* ct = (CompilerThread*)this;
2924 if (ct->task() != NULL) {
2925 st->print(" Compiling: ");
2926 ct->task()->print(st, NULL, true, false);
2927 } else {
2928 st->print(" No compile task");
2929 }
2930 st->cr();
2931 }
2932 }
2933
2934 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2935 st->print("%s", get_thread_name_string(buf, buflen));
2936 }
2937
2938 // Called by fatal error handler. The difference between this and
2939 // JavaThread::print() is that we can't grab lock or allocate memory.
2940 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2941 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2942 oop thread_obj = threadObj();
2943 if (thread_obj != NULL) {
2944 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2945 }
2946 st->print(" [");
2947 st->print("%s", _get_thread_state_name(_thread_state));
2948 if (osthread()) {
2949 st->print(", id=%d", osthread()->thread_id());
2950 }
2951 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2952 p2i(stack_end()), p2i(stack_base()));
2953 st->print("]");
2954 return;
2955 }
2956
2957 // Verification
2958
2959 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2960
2961 void JavaThread::verify() {
2962 // Verify oops in the thread.
2963 oops_do(&VerifyOopClosure::verify_oop, NULL);
2964
2965 // Verify the stack frames.
2966 frames_do(frame_verify);
2967 }
2968
2969 // CR 6300358 (sub-CR 2137150)
2970 // Most callers of this method assume that it can't return NULL but a
2971 // thread may not have a name whilst it is in the process of attaching to
2972 // the VM - see CR 6412693, and there are places where a JavaThread can be
2973 // seen prior to having it's threadObj set (eg JNI attaching threads and
2974 // if vm exit occurs during initialization). These cases can all be accounted
2975 // for such that this method never returns NULL.
2976 const char* JavaThread::get_thread_name() const {
2977 #ifdef ASSERT
2978 // early safepoints can hit while current thread does not yet have TLS
2979 if (!SafepointSynchronize::is_at_safepoint()) {
2980 Thread *cur = Thread::current();
2981 if (!(cur->is_Java_thread() && cur == this)) {
2982 // Current JavaThreads are allowed to get their own name without
2983 // the Threads_lock.
2984 assert_locked_or_safepoint(Threads_lock);
2985 }
2986 }
2987 #endif // ASSERT
2988 return get_thread_name_string();
2989 }
2990
2991 // Returns a non-NULL representation of this thread's name, or a suitable
2992 // descriptive string if there is no set name
2993 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2994 const char* name_str;
2995 oop thread_obj = threadObj();
2996 if (thread_obj != NULL) {
2997 oop name = java_lang_Thread::name(thread_obj);
2998 if (name != NULL) {
2999 if (buf == NULL) {
3000 name_str = java_lang_String::as_utf8_string(name);
3001 } else {
3002 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3003 }
3004 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3005 name_str = "<no-name - thread is attaching>";
3006 } else {
3007 name_str = Thread::name();
3008 }
3009 } else {
3010 name_str = Thread::name();
3011 }
3012 assert(name_str != NULL, "unexpected NULL thread name");
3013 return name_str;
3014 }
3015
3016
3017 const char* JavaThread::get_threadgroup_name() const {
3018 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3019 oop thread_obj = threadObj();
3020 if (thread_obj != NULL) {
3021 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3022 if (thread_group != NULL) {
3023 // ThreadGroup.name can be null
3024 return java_lang_ThreadGroup::name(thread_group);
3025 }
3026 }
3027 return NULL;
3028 }
3029
3030 const char* JavaThread::get_parent_name() const {
3031 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3032 oop thread_obj = threadObj();
3033 if (thread_obj != NULL) {
3034 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3035 if (thread_group != NULL) {
3036 oop parent = java_lang_ThreadGroup::parent(thread_group);
3037 if (parent != NULL) {
3038 // ThreadGroup.name can be null
3039 return java_lang_ThreadGroup::name(parent);
3040 }
3041 }
3042 }
3043 return NULL;
3044 }
3045
3046 ThreadPriority JavaThread::java_priority() const {
3047 oop thr_oop = threadObj();
3048 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3049 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3050 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3051 return priority;
3052 }
3053
3054 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3055
3056 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3057 // Link Java Thread object <-> C++ Thread
3058
3059 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3060 // and put it into a new Handle. The Handle "thread_oop" can then
3061 // be used to pass the C++ thread object to other methods.
3062
3063 // Set the Java level thread object (jthread) field of the
3064 // new thread (a JavaThread *) to C++ thread object using the
3065 // "thread_oop" handle.
3066
3067 // Set the thread field (a JavaThread *) of the
3068 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3069
3070 Handle thread_oop(Thread::current(),
3071 JNIHandles::resolve_non_null(jni_thread));
3072 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3073 "must be initialized");
3074 set_threadObj(thread_oop());
3075 java_lang_Thread::set_thread(thread_oop(), this);
3076
3077 if (prio == NoPriority) {
3078 prio = java_lang_Thread::priority(thread_oop());
3079 assert(prio != NoPriority, "A valid priority should be present");
3080 }
3081
3082 // Push the Java priority down to the native thread; needs Threads_lock
3083 Thread::set_priority(this, prio);
3084
3085 prepare_ext();
3086
3087 // Add the new thread to the Threads list and set it in motion.
3088 // We must have threads lock in order to call Threads::add.
3089 // It is crucial that we do not block before the thread is
3090 // added to the Threads list for if a GC happens, then the java_thread oop
3091 // will not be visited by GC.
3092 Threads::add(this);
3093 }
3094
3095 oop JavaThread::current_park_blocker() {
3096 // Support for JSR-166 locks
3097 oop thread_oop = threadObj();
3098 if (thread_oop != NULL &&
3099 JDK_Version::current().supports_thread_park_blocker()) {
3100 return java_lang_Thread::park_blocker(thread_oop);
3101 }
3102 return NULL;
3103 }
3104
3105
3106 void JavaThread::print_stack_on(outputStream* st) {
3107 if (!has_last_Java_frame()) return;
3108 ResourceMark rm;
3109 HandleMark hm;
3110
3111 RegisterMap reg_map(this);
3112 vframe* start_vf = last_java_vframe(®_map);
3113 int count = 0;
3114 for (vframe* f = start_vf; f; f = f->sender()) {
3115 if (f->is_java_frame()) {
3116 javaVFrame* jvf = javaVFrame::cast(f);
3117 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3118
3119 // Print out lock information
3120 if (JavaMonitorsInStackTrace) {
3121 jvf->print_lock_info_on(st, count);
3122 }
3123 } else {
3124 // Ignore non-Java frames
3125 }
3126
3127 // Bail-out case for too deep stacks
3128 count++;
3129 if (MaxJavaStackTraceDepth == count) return;
3130 }
3131 }
3132
3133
3134 // JVMTI PopFrame support
3135 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3136 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3137 if (in_bytes(size_in_bytes) != 0) {
3138 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3139 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3140 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3141 }
3142 }
3143
3144 void* JavaThread::popframe_preserved_args() {
3145 return _popframe_preserved_args;
3146 }
3147
3148 ByteSize JavaThread::popframe_preserved_args_size() {
3149 return in_ByteSize(_popframe_preserved_args_size);
3150 }
3151
3152 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3153 int sz = in_bytes(popframe_preserved_args_size());
3154 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3155 return in_WordSize(sz / wordSize);
3156 }
3157
3158 void JavaThread::popframe_free_preserved_args() {
3159 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3160 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3161 _popframe_preserved_args = NULL;
3162 _popframe_preserved_args_size = 0;
3163 }
3164
3165 #ifndef PRODUCT
3166
3167 void JavaThread::trace_frames() {
3168 tty->print_cr("[Describe stack]");
3169 int frame_no = 1;
3170 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3171 tty->print(" %d. ", frame_no++);
3172 fst.current()->print_value_on(tty, this);
3173 tty->cr();
3174 }
3175 }
3176
3177 class PrintAndVerifyOopClosure: public OopClosure {
3178 protected:
3179 template <class T> inline void do_oop_work(T* p) {
3180 oop obj = oopDesc::load_decode_heap_oop(p);
3181 if (obj == NULL) return;
3182 tty->print(INTPTR_FORMAT ": ", p2i(p));
3183 if (obj->is_oop_or_null()) {
3184 if (obj->is_objArray()) {
3185 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3186 } else {
3187 obj->print();
3188 }
3189 } else {
3190 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3191 }
3192 tty->cr();
3193 }
3194 public:
3195 virtual void do_oop(oop* p) { do_oop_work(p); }
3196 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3197 };
3198
3199
3200 static void oops_print(frame* f, const RegisterMap *map) {
3201 PrintAndVerifyOopClosure print;
3202 f->print_value();
3203 f->oops_do(&print, NULL, (RegisterMap*)map);
3204 }
3205
3206 // Print our all the locations that contain oops and whether they are
3207 // valid or not. This useful when trying to find the oldest frame
3208 // where an oop has gone bad since the frame walk is from youngest to
3209 // oldest.
3210 void JavaThread::trace_oops() {
3211 tty->print_cr("[Trace oops]");
3212 frames_do(oops_print);
3213 }
3214
3215
3216 #ifdef ASSERT
3217 // Print or validate the layout of stack frames
3218 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3219 ResourceMark rm;
3220 PRESERVE_EXCEPTION_MARK;
3221 FrameValues values;
3222 int frame_no = 0;
3223 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3224 fst.current()->describe(values, ++frame_no);
3225 if (depth == frame_no) break;
3226 }
3227 if (validate_only) {
3228 values.validate();
3229 } else {
3230 tty->print_cr("[Describe stack layout]");
3231 values.print(this);
3232 }
3233 }
3234 #endif
3235
3236 void JavaThread::trace_stack_from(vframe* start_vf) {
3237 ResourceMark rm;
3238 int vframe_no = 1;
3239 for (vframe* f = start_vf; f; f = f->sender()) {
3240 if (f->is_java_frame()) {
3241 javaVFrame::cast(f)->print_activation(vframe_no++);
3242 } else {
3243 f->print();
3244 }
3245 if (vframe_no > StackPrintLimit) {
3246 tty->print_cr("...<more frames>...");
3247 return;
3248 }
3249 }
3250 }
3251
3252
3253 void JavaThread::trace_stack() {
3254 if (!has_last_Java_frame()) return;
3255 ResourceMark rm;
3256 HandleMark hm;
3257 RegisterMap reg_map(this);
3258 trace_stack_from(last_java_vframe(®_map));
3259 }
3260
3261
3262 #endif // PRODUCT
3263
3264
3265 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3266 assert(reg_map != NULL, "a map must be given");
3267 frame f = last_frame();
3268 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3269 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3270 }
3271 return NULL;
3272 }
3273
3274
3275 Klass* JavaThread::security_get_caller_class(int depth) {
3276 vframeStream vfst(this);
3277 vfst.security_get_caller_frame(depth);
3278 if (!vfst.at_end()) {
3279 return vfst.method()->method_holder();
3280 }
3281 return NULL;
3282 }
3283
3284 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3285 assert(thread->is_Compiler_thread(), "must be compiler thread");
3286 CompileBroker::compiler_thread_loop();
3287 }
3288
3289 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3290 NMethodSweeper::sweeper_loop();
3291 }
3292
3293 // Create a CompilerThread
3294 CompilerThread::CompilerThread(CompileQueue* queue,
3295 CompilerCounters* counters)
3296 : JavaThread(&compiler_thread_entry) {
3297 _env = NULL;
3298 _log = NULL;
3299 _task = NULL;
3300 _queue = queue;
3301 _counters = counters;
3302 _buffer_blob = NULL;
3303 _compiler = NULL;
3304
3305 #ifndef PRODUCT
3306 _ideal_graph_printer = NULL;
3307 #endif
3308 }
3309
3310 bool CompilerThread::can_call_java() const {
3311 return _compiler != NULL && _compiler->is_jvmci();
3312 }
3313
3314 // Create sweeper thread
3315 CodeCacheSweeperThread::CodeCacheSweeperThread()
3316 : JavaThread(&sweeper_thread_entry) {
3317 _scanned_nmethod = NULL;
3318 }
3319
3320 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3321 JavaThread::oops_do(f, cf);
3322 if (_scanned_nmethod != NULL && cf != NULL) {
3323 // Safepoints can occur when the sweeper is scanning an nmethod so
3324 // process it here to make sure it isn't unloaded in the middle of
3325 // a scan.
3326 cf->do_code_blob(_scanned_nmethod);
3327 }
3328 }
3329
3330 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3331 JavaThread::nmethods_do(cf);
3332 if (_scanned_nmethod != NULL && cf != NULL) {
3333 // Safepoints can occur when the sweeper is scanning an nmethod so
3334 // process it here to make sure it isn't unloaded in the middle of
3335 // a scan.
3336 cf->do_code_blob(_scanned_nmethod);
3337 }
3338 }
3339
3340
3341 // ======= Threads ========
3342
3343 // The Threads class links together all active threads, and provides
3344 // operations over all threads. It is protected by its own Mutex
3345 // lock, which is also used in other contexts to protect thread
3346 // operations from having the thread being operated on from exiting
3347 // and going away unexpectedly (e.g., safepoint synchronization)
3348
3349 JavaThread* Threads::_thread_list = NULL;
3350 int Threads::_number_of_threads = 0;
3351 int Threads::_number_of_non_daemon_threads = 0;
3352 int Threads::_return_code = 0;
3353 int Threads::_thread_claim_parity = 0;
3354 size_t JavaThread::_stack_size_at_create = 0;
3355 #ifdef ASSERT
3356 bool Threads::_vm_complete = false;
3357 #endif
3358
3359 // All JavaThreads
3360 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3361
3362 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3363 void Threads::threads_do(ThreadClosure* tc) {
3364 assert_locked_or_safepoint(Threads_lock);
3365 // ALL_JAVA_THREADS iterates through all JavaThreads
3366 ALL_JAVA_THREADS(p) {
3367 tc->do_thread(p);
3368 }
3369 // Someday we could have a table or list of all non-JavaThreads.
3370 // For now, just manually iterate through them.
3371 tc->do_thread(VMThread::vm_thread());
3372 Universe::heap()->gc_threads_do(tc);
3373 WatcherThread *wt = WatcherThread::watcher_thread();
3374 // Strictly speaking, the following NULL check isn't sufficient to make sure
3375 // the data for WatcherThread is still valid upon being examined. However,
3376 // considering that WatchThread terminates when the VM is on the way to
3377 // exit at safepoint, the chance of the above is extremely small. The right
3378 // way to prevent termination of WatcherThread would be to acquire
3379 // Terminator_lock, but we can't do that without violating the lock rank
3380 // checking in some cases.
3381 if (wt != NULL) {
3382 tc->do_thread(wt);
3383 }
3384
3385 // If CompilerThreads ever become non-JavaThreads, add them here
3386 }
3387
3388 // The system initialization in the library has three phases.
3389 //
3390 // Phase 1: java.lang.System class initialization
3391 // java.lang.System is a primordial class loaded and initialized
3392 // by the VM early during startup. java.lang.System.<clinit>
3393 // only does registerNatives and keeps the rest of the class
3394 // initialization work later until thread initialization completes.
3395 //
3396 // System.initPhase1 initializes the system properties, the static
3397 // fields in, out, and err. Set up java signal handlers, OS-specific
3398 // system settings, and thread group of the main thread.
3399 static void call_initPhase1(TRAPS) {
3400 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3401 instanceKlassHandle klass (THREAD, k);
3402
3403 JavaValue result(T_VOID);
3404 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3405 vmSymbols::void_method_signature(), CHECK);
3406 }
3407
3408 // Phase 2. Module system initialization
3409 // This will initialize the module system. Only java.base classes
3410 // can be loaded until phase 2 completes.
3411 //
3412 // Call System.initPhase2 after the compiler initialization and jsr292
3413 // classes get initialized because module initialization runs a lot of java
3414 // code, that for performance reasons, should be compiled. Also, this will
3415 // enable the startup code to use lambda and other language features in this
3416 // phase and onward.
3417 //
3418 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3419 static void call_initPhase2(TRAPS) {
3420 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3421 instanceKlassHandle klass (THREAD, k);
3422
3423 JavaValue result(T_VOID);
3424 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3425 vmSymbols::void_method_signature(), CHECK);
3426 universe_post_module_init();
3427 }
3428
3429 // Phase 3. final setup - set security manager, system class loader and TCCL
3430 //
3431 // This will instantiate and set the security manager, set the system class
3432 // loader as well as the thread context class loader. The security manager
3433 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3434 // other modules or the application's classpath.
3435 static void call_initPhase3(TRAPS) {
3436 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3437 instanceKlassHandle klass (THREAD, k);
3438
3439 JavaValue result(T_VOID);
3440 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3441 vmSymbols::void_method_signature(), CHECK);
3442 }
3443
3444 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3445 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3446
3447 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3448 create_vm_init_libraries();
3449 }
3450
3451 initialize_class(vmSymbols::java_lang_String(), CHECK);
3452
3453 // Inject CompactStrings value after the static initializers for String ran.
3454 java_lang_String::set_compact_strings(CompactStrings);
3455
3456 // Initialize java_lang.System (needed before creating the thread)
3457 initialize_class(vmSymbols::java_lang_System(), CHECK);
3458 // The VM creates & returns objects of this class. Make sure it's initialized.
3459 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3460 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3461 Handle thread_group = create_initial_thread_group(CHECK);
3462 Universe::set_main_thread_group(thread_group());
3463 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3464 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3465 main_thread->set_threadObj(thread_object);
3466 // Set thread status to running since main thread has
3467 // been started and running.
3468 java_lang_Thread::set_thread_status(thread_object,
3469 java_lang_Thread::RUNNABLE);
3470
3471 // The VM creates objects of this class.
3472 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK);
3473
3474 // The VM preresolves methods to these classes. Make sure that they get initialized
3475 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3476 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3477
3478 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3479 call_initPhase1(CHECK);
3480
3481 // get the Java runtime name after java.lang.System is initialized
3482 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3483 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3484
3485 // an instance of OutOfMemory exception has been allocated earlier
3486 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3487 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3488 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3489 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3490 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3491 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3492 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3493 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3494 }
3495
3496 void Threads::initialize_jsr292_core_classes(TRAPS) {
3497 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3498
3499 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3500 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3501 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3502 }
3503
3504 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3505 extern void JDK_Version_init();
3506
3507 // Preinitialize version info.
3508 VM_Version::early_initialize();
3509
3510 // Check version
3511 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3512
3513 // Initialize library-based TLS
3514 ThreadLocalStorage::init();
3515
3516 // Initialize the output stream module
3517 ostream_init();
3518
3519 // Process java launcher properties.
3520 Arguments::process_sun_java_launcher_properties(args);
3521
3522 // Initialize the os module
3523 os::init();
3524
3525 // Record VM creation timing statistics
3526 TraceVmCreationTime create_vm_timer;
3527 create_vm_timer.start();
3528
3529 // Initialize system properties.
3530 Arguments::init_system_properties();
3531
3532 // So that JDK version can be used as a discriminator when parsing arguments
3533 JDK_Version_init();
3534
3535 // Update/Initialize System properties after JDK version number is known
3536 Arguments::init_version_specific_system_properties();
3537
3538 // Make sure to initialize log configuration *before* parsing arguments
3539 LogConfiguration::initialize(create_vm_timer.begin_time());
3540
3541 // Parse arguments
3542 jint parse_result = Arguments::parse(args);
3543 if (parse_result != JNI_OK) return parse_result;
3544
3545 os::init_before_ergo();
3546
3547 jint ergo_result = Arguments::apply_ergo();
3548 if (ergo_result != JNI_OK) return ergo_result;
3549
3550 // Final check of all ranges after ergonomics which may change values.
3551 if (!CommandLineFlagRangeList::check_ranges()) {
3552 return JNI_EINVAL;
3553 }
3554
3555 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3556 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3557 if (!constraint_result) {
3558 return JNI_EINVAL;
3559 }
3560
3561 if (PauseAtStartup) {
3562 os::pause();
3563 }
3564
3565 HOTSPOT_VM_INIT_BEGIN();
3566
3567 // Timing (must come after argument parsing)
3568 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3569
3570 // Initialize the os module after parsing the args
3571 jint os_init_2_result = os::init_2();
3572 if (os_init_2_result != JNI_OK) return os_init_2_result;
3573
3574 jint adjust_after_os_result = Arguments::adjust_after_os();
3575 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3576
3577 // Initialize output stream logging
3578 ostream_init_log();
3579
3580 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3581 // Must be before create_vm_init_agents()
3582 if (Arguments::init_libraries_at_startup()) {
3583 convert_vm_init_libraries_to_agents();
3584 }
3585
3586 // Launch -agentlib/-agentpath and converted -Xrun agents
3587 if (Arguments::init_agents_at_startup()) {
3588 create_vm_init_agents();
3589 }
3590
3591 // Initialize Threads state
3592 _thread_list = NULL;
3593 _number_of_threads = 0;
3594 _number_of_non_daemon_threads = 0;
3595
3596 // Initialize global data structures and create system classes in heap
3597 vm_init_globals();
3598
3599 #if INCLUDE_JVMCI
3600 if (JVMCICounterSize > 0) {
3601 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3602 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3603 } else {
3604 JavaThread::_jvmci_old_thread_counters = NULL;
3605 }
3606 #endif // INCLUDE_JVMCI
3607
3608 // Attach the main thread to this os thread
3609 JavaThread* main_thread = new JavaThread();
3610 main_thread->set_thread_state(_thread_in_vm);
3611 main_thread->initialize_thread_current();
3612 // must do this before set_active_handles
3613 main_thread->record_stack_base_and_size();
3614 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3615
3616 if (!main_thread->set_as_starting_thread()) {
3617 vm_shutdown_during_initialization(
3618 "Failed necessary internal allocation. Out of swap space");
3619 delete main_thread;
3620 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3621 return JNI_ENOMEM;
3622 }
3623
3624 // Enable guard page *after* os::create_main_thread(), otherwise it would
3625 // crash Linux VM, see notes in os_linux.cpp.
3626 main_thread->create_stack_guard_pages();
3627
3628 // Initialize Java-Level synchronization subsystem
3629 ObjectMonitor::Initialize();
3630
3631 // Initialize global modules
3632 jint status = init_globals();
3633 if (status != JNI_OK) {
3634 delete main_thread;
3635 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3636 return status;
3637 }
3638
3639 if (TRACE_INITIALIZE() != JNI_OK) {
3640 vm_exit_during_initialization("Failed to initialize tracing backend");
3641 }
3642
3643 // Should be done after the heap is fully created
3644 main_thread->cache_global_variables();
3645
3646 HandleMark hm;
3647
3648 { MutexLocker mu(Threads_lock);
3649 Threads::add(main_thread);
3650 }
3651
3652 // Any JVMTI raw monitors entered in onload will transition into
3653 // real raw monitor. VM is setup enough here for raw monitor enter.
3654 JvmtiExport::transition_pending_onload_raw_monitors();
3655
3656 // Create the VMThread
3657 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3658
3659 VMThread::create();
3660 Thread* vmthread = VMThread::vm_thread();
3661
3662 if (!os::create_thread(vmthread, os::vm_thread)) {
3663 vm_exit_during_initialization("Cannot create VM thread. "
3664 "Out of system resources.");
3665 }
3666
3667 // Wait for the VM thread to become ready, and VMThread::run to initialize
3668 // Monitors can have spurious returns, must always check another state flag
3669 {
3670 MutexLocker ml(Notify_lock);
3671 os::start_thread(vmthread);
3672 while (vmthread->active_handles() == NULL) {
3673 Notify_lock->wait();
3674 }
3675 }
3676 }
3677
3678 assert(Universe::is_fully_initialized(), "not initialized");
3679 if (VerifyDuringStartup) {
3680 // Make sure we're starting with a clean slate.
3681 VM_Verify verify_op;
3682 VMThread::execute(&verify_op);
3683 }
3684
3685 Thread* THREAD = Thread::current();
3686
3687 // At this point, the Universe is initialized, but we have not executed
3688 // any byte code. Now is a good time (the only time) to dump out the
3689 // internal state of the JVM for sharing.
3690 if (DumpSharedSpaces) {
3691 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3692 ShouldNotReachHere();
3693 }
3694
3695 // Always call even when there are not JVMTI environments yet, since environments
3696 // may be attached late and JVMTI must track phases of VM execution
3697 JvmtiExport::enter_early_start_phase();
3698
3699 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3700 JvmtiExport::post_early_vm_start();
3701
3702 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3703
3704 // We need this for ClassDataSharing - the initial vm.info property is set
3705 // with the default value of CDS "sharing" which may be reset through
3706 // command line options.
3707 reset_vm_info_property(CHECK_JNI_ERR);
3708
3709 quicken_jni_functions();
3710
3711 // No more stub generation allowed after that point.
3712 StubCodeDesc::freeze();
3713
3714 // Set flag that basic initialization has completed. Used by exceptions and various
3715 // debug stuff, that does not work until all basic classes have been initialized.
3716 set_init_completed();
3717
3718 LogConfiguration::post_initialize();
3719 Metaspace::post_initialize();
3720
3721 HOTSPOT_VM_INIT_END();
3722
3723 // record VM initialization completion time
3724 #if INCLUDE_MANAGEMENT
3725 Management::record_vm_init_completed();
3726 #endif // INCLUDE_MANAGEMENT
3727
3728 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3729 // set_init_completed has just been called, causing exceptions not to be shortcut
3730 // anymore. We call vm_exit_during_initialization directly instead.
3731
3732 // Initialize reference pending list locker
3733 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread();
3734 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR);
3735
3736 // Signal Dispatcher needs to be started before VMInit event is posted
3737 os::signal_init();
3738
3739 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3740 if (!DisableAttachMechanism) {
3741 AttachListener::vm_start();
3742 if (StartAttachListener || AttachListener::init_at_startup()) {
3743 AttachListener::init();
3744 }
3745 }
3746
3747 // Launch -Xrun agents
3748 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3749 // back-end can launch with -Xdebug -Xrunjdwp.
3750 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3751 create_vm_init_libraries();
3752 }
3753
3754 if (CleanChunkPoolAsync) {
3755 Chunk::start_chunk_pool_cleaner_task();
3756 }
3757
3758 // initialize compiler(s)
3759 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3760 CompileBroker::compilation_init(CHECK_JNI_ERR);
3761 #endif
3762
3763 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3764 // It is done after compilers are initialized, because otherwise compilations of
3765 // signature polymorphic MH intrinsics can be missed
3766 // (see SystemDictionary::find_method_handle_intrinsic).
3767 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3768
3769 // This will initialize the module system. Only java.base classes can be
3770 // loaded until phase 2 completes
3771 call_initPhase2(CHECK_JNI_ERR);
3772
3773 // Always call even when there are not JVMTI environments yet, since environments
3774 // may be attached late and JVMTI must track phases of VM execution
3775 JvmtiExport::enter_start_phase();
3776
3777 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3778 JvmtiExport::post_vm_start();
3779
3780 // Final system initialization including security manager and system class loader
3781 call_initPhase3(CHECK_JNI_ERR);
3782
3783 // cache the system class loader
3784 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3785
3786 // Always call even when there are not JVMTI environments yet, since environments
3787 // may be attached late and JVMTI must track phases of VM execution
3788 JvmtiExport::enter_live_phase();
3789
3790 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3791 JvmtiExport::post_vm_initialized();
3792
3793 if (TRACE_START() != JNI_OK) {
3794 vm_exit_during_initialization("Failed to start tracing backend.");
3795 }
3796
3797 #if INCLUDE_MANAGEMENT
3798 Management::initialize(THREAD);
3799
3800 if (HAS_PENDING_EXCEPTION) {
3801 // management agent fails to start possibly due to
3802 // configuration problem and is responsible for printing
3803 // stack trace if appropriate. Simply exit VM.
3804 vm_exit(1);
3805 }
3806 #endif // INCLUDE_MANAGEMENT
3807
3808 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3809 if (MemProfiling) MemProfiler::engage();
3810 StatSampler::engage();
3811 if (CheckJNICalls) JniPeriodicChecker::engage();
3812
3813 BiasedLocking::init();
3814
3815 #if INCLUDE_RTM_OPT
3816 RTMLockingCounters::init();
3817 #endif
3818
3819 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3820 call_postVMInitHook(THREAD);
3821 // The Java side of PostVMInitHook.run must deal with all
3822 // exceptions and provide means of diagnosis.
3823 if (HAS_PENDING_EXCEPTION) {
3824 CLEAR_PENDING_EXCEPTION;
3825 }
3826 }
3827
3828 {
3829 MutexLocker ml(PeriodicTask_lock);
3830 // Make sure the WatcherThread can be started by WatcherThread::start()
3831 // or by dynamic enrollment.
3832 WatcherThread::make_startable();
3833 // Start up the WatcherThread if there are any periodic tasks
3834 // NOTE: All PeriodicTasks should be registered by now. If they
3835 // aren't, late joiners might appear to start slowly (we might
3836 // take a while to process their first tick).
3837 if (PeriodicTask::num_tasks() > 0) {
3838 WatcherThread::start();
3839 }
3840 }
3841
3842 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3843
3844 create_vm_timer.end();
3845 #ifdef ASSERT
3846 _vm_complete = true;
3847 #endif
3848 return JNI_OK;
3849 }
3850
3851 // type for the Agent_OnLoad and JVM_OnLoad entry points
3852 extern "C" {
3853 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3854 }
3855 // Find a command line agent library and return its entry point for
3856 // -agentlib: -agentpath: -Xrun
3857 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3858 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3859 const char *on_load_symbols[],
3860 size_t num_symbol_entries) {
3861 OnLoadEntry_t on_load_entry = NULL;
3862 void *library = NULL;
3863
3864 if (!agent->valid()) {
3865 char buffer[JVM_MAXPATHLEN];
3866 char ebuf[1024] = "";
3867 const char *name = agent->name();
3868 const char *msg = "Could not find agent library ";
3869
3870 // First check to see if agent is statically linked into executable
3871 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3872 library = agent->os_lib();
3873 } else if (agent->is_absolute_path()) {
3874 library = os::dll_load(name, ebuf, sizeof ebuf);
3875 if (library == NULL) {
3876 const char *sub_msg = " in absolute path, with error: ";
3877 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3878 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3879 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3880 // If we can't find the agent, exit.
3881 vm_exit_during_initialization(buf, NULL);
3882 FREE_C_HEAP_ARRAY(char, buf);
3883 }
3884 } else {
3885 // Try to load the agent from the standard dll directory
3886 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3887 name)) {
3888 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3889 }
3890 if (library == NULL) { // Try the local directory
3891 char ns[1] = {0};
3892 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3893 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3894 }
3895 if (library == NULL) {
3896 const char *sub_msg = " on the library path, with error: ";
3897 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3898 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3899 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3900 // If we can't find the agent, exit.
3901 vm_exit_during_initialization(buf, NULL);
3902 FREE_C_HEAP_ARRAY(char, buf);
3903 }
3904 }
3905 }
3906 agent->set_os_lib(library);
3907 agent->set_valid();
3908 }
3909
3910 // Find the OnLoad function.
3911 on_load_entry =
3912 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3913 false,
3914 on_load_symbols,
3915 num_symbol_entries));
3916 return on_load_entry;
3917 }
3918
3919 // Find the JVM_OnLoad entry point
3920 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3921 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3922 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3923 }
3924
3925 // Find the Agent_OnLoad entry point
3926 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3927 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3928 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3929 }
3930
3931 // For backwards compatibility with -Xrun
3932 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3933 // treated like -agentpath:
3934 // Must be called before agent libraries are created
3935 void Threads::convert_vm_init_libraries_to_agents() {
3936 AgentLibrary* agent;
3937 AgentLibrary* next;
3938
3939 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3940 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3941 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3942
3943 // If there is an JVM_OnLoad function it will get called later,
3944 // otherwise see if there is an Agent_OnLoad
3945 if (on_load_entry == NULL) {
3946 on_load_entry = lookup_agent_on_load(agent);
3947 if (on_load_entry != NULL) {
3948 // switch it to the agent list -- so that Agent_OnLoad will be called,
3949 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3950 Arguments::convert_library_to_agent(agent);
3951 } else {
3952 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3953 }
3954 }
3955 }
3956 }
3957
3958 // Create agents for -agentlib: -agentpath: and converted -Xrun
3959 // Invokes Agent_OnLoad
3960 // Called very early -- before JavaThreads exist
3961 void Threads::create_vm_init_agents() {
3962 extern struct JavaVM_ main_vm;
3963 AgentLibrary* agent;
3964
3965 JvmtiExport::enter_onload_phase();
3966
3967 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3968 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3969
3970 if (on_load_entry != NULL) {
3971 // Invoke the Agent_OnLoad function
3972 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3973 if (err != JNI_OK) {
3974 vm_exit_during_initialization("agent library failed to init", agent->name());
3975 }
3976 } else {
3977 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3978 }
3979 }
3980 JvmtiExport::enter_primordial_phase();
3981 }
3982
3983 extern "C" {
3984 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3985 }
3986
3987 void Threads::shutdown_vm_agents() {
3988 // Send any Agent_OnUnload notifications
3989 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3990 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3991 extern struct JavaVM_ main_vm;
3992 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3993
3994 // Find the Agent_OnUnload function.
3995 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3996 os::find_agent_function(agent,
3997 false,
3998 on_unload_symbols,
3999 num_symbol_entries));
4000
4001 // Invoke the Agent_OnUnload function
4002 if (unload_entry != NULL) {
4003 JavaThread* thread = JavaThread::current();
4004 ThreadToNativeFromVM ttn(thread);
4005 HandleMark hm(thread);
4006 (*unload_entry)(&main_vm);
4007 }
4008 }
4009 }
4010
4011 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4012 // Invokes JVM_OnLoad
4013 void Threads::create_vm_init_libraries() {
4014 extern struct JavaVM_ main_vm;
4015 AgentLibrary* agent;
4016
4017 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4018 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4019
4020 if (on_load_entry != NULL) {
4021 // Invoke the JVM_OnLoad function
4022 JavaThread* thread = JavaThread::current();
4023 ThreadToNativeFromVM ttn(thread);
4024 HandleMark hm(thread);
4025 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4026 if (err != JNI_OK) {
4027 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4028 }
4029 } else {
4030 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4031 }
4032 }
4033 }
4034
4035 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4036 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4037
4038 JavaThread* java_thread = NULL;
4039 // Sequential search for now. Need to do better optimization later.
4040 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4041 oop tobj = thread->threadObj();
4042 if (!thread->is_exiting() &&
4043 tobj != NULL &&
4044 java_tid == java_lang_Thread::thread_id(tobj)) {
4045 java_thread = thread;
4046 break;
4047 }
4048 }
4049 return java_thread;
4050 }
4051
4052
4053 // Last thread running calls java.lang.Shutdown.shutdown()
4054 void JavaThread::invoke_shutdown_hooks() {
4055 HandleMark hm(this);
4056
4057 // We could get here with a pending exception, if so clear it now.
4058 if (this->has_pending_exception()) {
4059 this->clear_pending_exception();
4060 }
4061
4062 EXCEPTION_MARK;
4063 Klass* k =
4064 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4065 THREAD);
4066 if (k != NULL) {
4067 // SystemDictionary::resolve_or_null will return null if there was
4068 // an exception. If we cannot load the Shutdown class, just don't
4069 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4070 // and finalizers (if runFinalizersOnExit is set) won't be run.
4071 // Note that if a shutdown hook was registered or runFinalizersOnExit
4072 // was called, the Shutdown class would have already been loaded
4073 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4074 instanceKlassHandle shutdown_klass (THREAD, k);
4075 JavaValue result(T_VOID);
4076 JavaCalls::call_static(&result,
4077 shutdown_klass,
4078 vmSymbols::shutdown_method_name(),
4079 vmSymbols::void_method_signature(),
4080 THREAD);
4081 }
4082 CLEAR_PENDING_EXCEPTION;
4083 }
4084
4085 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4086 // the program falls off the end of main(). Another VM exit path is through
4087 // vm_exit() when the program calls System.exit() to return a value or when
4088 // there is a serious error in VM. The two shutdown paths are not exactly
4089 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4090 // and VM_Exit op at VM level.
4091 //
4092 // Shutdown sequence:
4093 // + Shutdown native memory tracking if it is on
4094 // + Wait until we are the last non-daemon thread to execute
4095 // <-- every thing is still working at this moment -->
4096 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4097 // shutdown hooks, run finalizers if finalization-on-exit
4098 // + Call before_exit(), prepare for VM exit
4099 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4100 // currently the only user of this mechanism is File.deleteOnExit())
4101 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4102 // post thread end and vm death events to JVMTI,
4103 // stop signal thread
4104 // + Call JavaThread::exit(), it will:
4105 // > release JNI handle blocks, remove stack guard pages
4106 // > remove this thread from Threads list
4107 // <-- no more Java code from this thread after this point -->
4108 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4109 // the compiler threads at safepoint
4110 // <-- do not use anything that could get blocked by Safepoint -->
4111 // + Disable tracing at JNI/JVM barriers
4112 // + Set _vm_exited flag for threads that are still running native code
4113 // + Delete this thread
4114 // + Call exit_globals()
4115 // > deletes tty
4116 // > deletes PerfMemory resources
4117 // + Return to caller
4118
4119 bool Threads::destroy_vm() {
4120 JavaThread* thread = JavaThread::current();
4121
4122 #ifdef ASSERT
4123 _vm_complete = false;
4124 #endif
4125 // Wait until we are the last non-daemon thread to execute
4126 { MutexLocker nu(Threads_lock);
4127 while (Threads::number_of_non_daemon_threads() > 1)
4128 // This wait should make safepoint checks, wait without a timeout,
4129 // and wait as a suspend-equivalent condition.
4130 //
4131 // Note: If the FlatProfiler is running and this thread is waiting
4132 // for another non-daemon thread to finish, then the FlatProfiler
4133 // is waiting for the external suspend request on this thread to
4134 // complete. wait_for_ext_suspend_completion() will eventually
4135 // timeout, but that takes time. Making this wait a suspend-
4136 // equivalent condition solves that timeout problem.
4137 //
4138 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4139 Mutex::_as_suspend_equivalent_flag);
4140 }
4141
4142 // Hang forever on exit if we are reporting an error.
4143 if (ShowMessageBoxOnError && is_error_reported()) {
4144 os::infinite_sleep();
4145 }
4146 os::wait_for_keypress_at_exit();
4147
4148 // run Java level shutdown hooks
4149 thread->invoke_shutdown_hooks();
4150
4151 before_exit(thread);
4152
4153 thread->exit(true);
4154
4155 // Stop VM thread.
4156 {
4157 // 4945125 The vm thread comes to a safepoint during exit.
4158 // GC vm_operations can get caught at the safepoint, and the
4159 // heap is unparseable if they are caught. Grab the Heap_lock
4160 // to prevent this. The GC vm_operations will not be able to
4161 // queue until after the vm thread is dead. After this point,
4162 // we'll never emerge out of the safepoint before the VM exits.
4163
4164 MutexLocker ml(Heap_lock);
4165
4166 VMThread::wait_for_vm_thread_exit();
4167 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4168 VMThread::destroy();
4169 }
4170
4171 // clean up ideal graph printers
4172 #if defined(COMPILER2) && !defined(PRODUCT)
4173 IdealGraphPrinter::clean_up();
4174 #endif
4175
4176 // Now, all Java threads are gone except daemon threads. Daemon threads
4177 // running Java code or in VM are stopped by the Safepoint. However,
4178 // daemon threads executing native code are still running. But they
4179 // will be stopped at native=>Java/VM barriers. Note that we can't
4180 // simply kill or suspend them, as it is inherently deadlock-prone.
4181
4182 VM_Exit::set_vm_exited();
4183
4184 notify_vm_shutdown();
4185
4186 delete thread;
4187
4188 #if INCLUDE_JVMCI
4189 if (JVMCICounterSize > 0) {
4190 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4191 }
4192 #endif
4193
4194 // exit_globals() will delete tty
4195 exit_globals();
4196
4197 LogConfiguration::finalize();
4198
4199 return true;
4200 }
4201
4202
4203 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4204 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4205 return is_supported_jni_version(version);
4206 }
4207
4208
4209 jboolean Threads::is_supported_jni_version(jint version) {
4210 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4211 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4212 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4213 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4214 if (version == JNI_VERSION_9) return JNI_TRUE;
4215 return JNI_FALSE;
4216 }
4217
4218
4219 void Threads::add(JavaThread* p, bool force_daemon) {
4220 // The threads lock must be owned at this point
4221 assert_locked_or_safepoint(Threads_lock);
4222
4223 // See the comment for this method in thread.hpp for its purpose and
4224 // why it is called here.
4225 p->initialize_queues();
4226 p->set_next(_thread_list);
4227 _thread_list = p;
4228 _number_of_threads++;
4229 oop threadObj = p->threadObj();
4230 bool daemon = true;
4231 // Bootstrapping problem: threadObj can be null for initial
4232 // JavaThread (or for threads attached via JNI)
4233 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4234 _number_of_non_daemon_threads++;
4235 daemon = false;
4236 }
4237
4238 ThreadService::add_thread(p, daemon);
4239
4240 // Possible GC point.
4241 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4242 }
4243
4244 void Threads::remove(JavaThread* p) {
4245 // Extra scope needed for Thread_lock, so we can check
4246 // that we do not remove thread without safepoint code notice
4247 { MutexLocker ml(Threads_lock);
4248
4249 assert(includes(p), "p must be present");
4250
4251 JavaThread* current = _thread_list;
4252 JavaThread* prev = NULL;
4253
4254 while (current != p) {
4255 prev = current;
4256 current = current->next();
4257 }
4258
4259 if (prev) {
4260 prev->set_next(current->next());
4261 } else {
4262 _thread_list = p->next();
4263 }
4264 _number_of_threads--;
4265 oop threadObj = p->threadObj();
4266 bool daemon = true;
4267 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4268 _number_of_non_daemon_threads--;
4269 daemon = false;
4270
4271 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4272 // on destroy_vm will wake up.
4273 if (number_of_non_daemon_threads() == 1) {
4274 Threads_lock->notify_all();
4275 }
4276 }
4277 ThreadService::remove_thread(p, daemon);
4278
4279 // Make sure that safepoint code disregard this thread. This is needed since
4280 // the thread might mess around with locks after this point. This can cause it
4281 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4282 // of this thread since it is removed from the queue.
4283 p->set_terminated_value();
4284 } // unlock Threads_lock
4285
4286 // Since Events::log uses a lock, we grab it outside the Threads_lock
4287 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4288 }
4289
4290 // Threads_lock must be held when this is called (or must be called during a safepoint)
4291 bool Threads::includes(JavaThread* p) {
4292 assert(Threads_lock->is_locked(), "sanity check");
4293 ALL_JAVA_THREADS(q) {
4294 if (q == p) {
4295 return true;
4296 }
4297 }
4298 return false;
4299 }
4300
4301 // Operations on the Threads list for GC. These are not explicitly locked,
4302 // but the garbage collector must provide a safe context for them to run.
4303 // In particular, these things should never be called when the Threads_lock
4304 // is held by some other thread. (Note: the Safepoint abstraction also
4305 // uses the Threads_lock to guarantee this property. It also makes sure that
4306 // all threads gets blocked when exiting or starting).
4307
4308 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4309 ALL_JAVA_THREADS(p) {
4310 p->oops_do(f, cf);
4311 }
4312 VMThread::vm_thread()->oops_do(f, cf);
4313 }
4314
4315 void Threads::change_thread_claim_parity() {
4316 // Set the new claim parity.
4317 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4318 "Not in range.");
4319 _thread_claim_parity++;
4320 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4321 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4322 "Not in range.");
4323 }
4324
4325 #ifdef ASSERT
4326 void Threads::assert_all_threads_claimed() {
4327 ALL_JAVA_THREADS(p) {
4328 const int thread_parity = p->oops_do_parity();
4329 assert((thread_parity == _thread_claim_parity),
4330 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4331 }
4332 }
4333 #endif // ASSERT
4334
4335 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4336 int cp = Threads::thread_claim_parity();
4337 ALL_JAVA_THREADS(p) {
4338 if (p->claim_oops_do(is_par, cp)) {
4339 p->oops_do(f, cf);
4340 }
4341 }
4342 VMThread* vmt = VMThread::vm_thread();
4343 if (vmt->claim_oops_do(is_par, cp)) {
4344 vmt->oops_do(f, cf);
4345 }
4346 }
4347
4348 #if INCLUDE_ALL_GCS
4349 // Used by ParallelScavenge
4350 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4351 ALL_JAVA_THREADS(p) {
4352 q->enqueue(new ThreadRootsTask(p));
4353 }
4354 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4355 }
4356
4357 // Used by Parallel Old
4358 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4359 ALL_JAVA_THREADS(p) {
4360 q->enqueue(new ThreadRootsMarkingTask(p));
4361 }
4362 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4363 }
4364 #endif // INCLUDE_ALL_GCS
4365
4366 void Threads::nmethods_do(CodeBlobClosure* cf) {
4367 ALL_JAVA_THREADS(p) {
4368 // This is used by the code cache sweeper to mark nmethods that are active
4369 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4370 // marking CodeCacheSweeperThread::_scanned_nmethod as active.
4371 if(!p->is_Code_cache_sweeper_thread()) {
4372 p->nmethods_do(cf);
4373 }
4374 }
4375 }
4376
4377 void Threads::metadata_do(void f(Metadata*)) {
4378 ALL_JAVA_THREADS(p) {
4379 p->metadata_do(f);
4380 }
4381 }
4382
4383 class ThreadHandlesClosure : public ThreadClosure {
4384 void (*_f)(Metadata*);
4385 public:
4386 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4387 virtual void do_thread(Thread* thread) {
4388 thread->metadata_handles_do(_f);
4389 }
4390 };
4391
4392 void Threads::metadata_handles_do(void f(Metadata*)) {
4393 // Only walk the Handles in Thread.
4394 ThreadHandlesClosure handles_closure(f);
4395 threads_do(&handles_closure);
4396 }
4397
4398 void Threads::deoptimized_wrt_marked_nmethods() {
4399 ALL_JAVA_THREADS(p) {
4400 p->deoptimized_wrt_marked_nmethods();
4401 }
4402 }
4403
4404
4405 // Get count Java threads that are waiting to enter the specified monitor.
4406 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4407 address monitor,
4408 bool doLock) {
4409 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4410 "must grab Threads_lock or be at safepoint");
4411 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4412
4413 int i = 0;
4414 {
4415 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4416 ALL_JAVA_THREADS(p) {
4417 if (!p->can_call_java()) continue;
4418
4419 address pending = (address)p->current_pending_monitor();
4420 if (pending == monitor) { // found a match
4421 if (i < count) result->append(p); // save the first count matches
4422 i++;
4423 }
4424 }
4425 }
4426 return result;
4427 }
4428
4429
4430 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4431 bool doLock) {
4432 assert(doLock ||
4433 Threads_lock->owned_by_self() ||
4434 SafepointSynchronize::is_at_safepoint(),
4435 "must grab Threads_lock or be at safepoint");
4436
4437 // NULL owner means not locked so we can skip the search
4438 if (owner == NULL) return NULL;
4439
4440 {
4441 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4442 ALL_JAVA_THREADS(p) {
4443 // first, see if owner is the address of a Java thread
4444 if (owner == (address)p) return p;
4445 }
4446 }
4447 // Cannot assert on lack of success here since this function may be
4448 // used by code that is trying to report useful problem information
4449 // like deadlock detection.
4450 if (UseHeavyMonitors) return NULL;
4451
4452 // If we didn't find a matching Java thread and we didn't force use of
4453 // heavyweight monitors, then the owner is the stack address of the
4454 // Lock Word in the owning Java thread's stack.
4455 //
4456 JavaThread* the_owner = NULL;
4457 {
4458 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4459 ALL_JAVA_THREADS(q) {
4460 if (q->is_lock_owned(owner)) {
4461 the_owner = q;
4462 break;
4463 }
4464 }
4465 }
4466 // cannot assert on lack of success here; see above comment
4467 return the_owner;
4468 }
4469
4470 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4471 void Threads::print_on(outputStream* st, bool print_stacks,
4472 bool internal_format, bool print_concurrent_locks) {
4473 char buf[32];
4474 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4475
4476 st->print_cr("Full thread dump %s (%s %s):",
4477 Abstract_VM_Version::vm_name(),
4478 Abstract_VM_Version::vm_release(),
4479 Abstract_VM_Version::vm_info_string());
4480 st->cr();
4481
4482 #if INCLUDE_SERVICES
4483 // Dump concurrent locks
4484 ConcurrentLocksDump concurrent_locks;
4485 if (print_concurrent_locks) {
4486 concurrent_locks.dump_at_safepoint();
4487 }
4488 #endif // INCLUDE_SERVICES
4489
4490 ALL_JAVA_THREADS(p) {
4491 ResourceMark rm;
4492 p->print_on(st);
4493 if (print_stacks) {
4494 if (internal_format) {
4495 p->trace_stack();
4496 } else {
4497 p->print_stack_on(st);
4498 }
4499 }
4500 st->cr();
4501 #if INCLUDE_SERVICES
4502 if (print_concurrent_locks) {
4503 concurrent_locks.print_locks_on(p, st);
4504 }
4505 #endif // INCLUDE_SERVICES
4506 }
4507
4508 VMThread::vm_thread()->print_on(st);
4509 st->cr();
4510 Universe::heap()->print_gc_threads_on(st);
4511 WatcherThread* wt = WatcherThread::watcher_thread();
4512 if (wt != NULL) {
4513 wt->print_on(st);
4514 st->cr();
4515 }
4516 st->flush();
4517 }
4518
4519 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4520 int buflen, bool* found_current) {
4521 if (this_thread != NULL) {
4522 bool is_current = (current == this_thread);
4523 *found_current = *found_current || is_current;
4524 st->print("%s", is_current ? "=>" : " ");
4525
4526 st->print(PTR_FORMAT, p2i(this_thread));
4527 st->print(" ");
4528 this_thread->print_on_error(st, buf, buflen);
4529 st->cr();
4530 }
4531 }
4532
4533 class PrintOnErrorClosure : public ThreadClosure {
4534 outputStream* _st;
4535 Thread* _current;
4536 char* _buf;
4537 int _buflen;
4538 bool* _found_current;
4539 public:
4540 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4541 int buflen, bool* found_current) :
4542 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4543
4544 virtual void do_thread(Thread* thread) {
4545 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4546 }
4547 };
4548
4549 // Threads::print_on_error() is called by fatal error handler. It's possible
4550 // that VM is not at safepoint and/or current thread is inside signal handler.
4551 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4552 // memory (even in resource area), it might deadlock the error handler.
4553 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4554 int buflen) {
4555 bool found_current = false;
4556 st->print_cr("Java Threads: ( => current thread )");
4557 ALL_JAVA_THREADS(thread) {
4558 print_on_error(thread, st, current, buf, buflen, &found_current);
4559 }
4560 st->cr();
4561
4562 st->print_cr("Other Threads:");
4563 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4564 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4565
4566 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4567 Universe::heap()->gc_threads_do(&print_closure);
4568
4569 if (!found_current) {
4570 st->cr();
4571 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4572 current->print_on_error(st, buf, buflen);
4573 st->cr();
4574 }
4575 st->cr();
4576 st->print_cr("Threads with active compile tasks:");
4577 print_threads_compiling(st, buf, buflen);
4578 }
4579
4580 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4581 ALL_JAVA_THREADS(thread) {
4582 if (thread->is_Compiler_thread()) {
4583 CompilerThread* ct = (CompilerThread*) thread;
4584 if (ct->task() != NULL) {
4585 thread->print_name_on_error(st, buf, buflen);
4586 ct->task()->print(st, NULL, true, true);
4587 }
4588 }
4589 }
4590 }
4591
4592
4593 // Internal SpinLock and Mutex
4594 // Based on ParkEvent
4595
4596 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4597 //
4598 // We employ SpinLocks _only for low-contention, fixed-length
4599 // short-duration critical sections where we're concerned
4600 // about native mutex_t or HotSpot Mutex:: latency.
4601 // The mux construct provides a spin-then-block mutual exclusion
4602 // mechanism.
4603 //
4604 // Testing has shown that contention on the ListLock guarding gFreeList
4605 // is common. If we implement ListLock as a simple SpinLock it's common
4606 // for the JVM to devolve to yielding with little progress. This is true
4607 // despite the fact that the critical sections protected by ListLock are
4608 // extremely short.
4609 //
4610 // TODO-FIXME: ListLock should be of type SpinLock.
4611 // We should make this a 1st-class type, integrated into the lock
4612 // hierarchy as leaf-locks. Critically, the SpinLock structure
4613 // should have sufficient padding to avoid false-sharing and excessive
4614 // cache-coherency traffic.
4615
4616
4617 typedef volatile int SpinLockT;
4618
4619 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4620 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4621 return; // normal fast-path return
4622 }
4623
4624 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4625 TEVENT(SpinAcquire - ctx);
4626 int ctr = 0;
4627 int Yields = 0;
4628 for (;;) {
4629 while (*adr != 0) {
4630 ++ctr;
4631 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4632 if (Yields > 5) {
4633 os::naked_short_sleep(1);
4634 } else {
4635 os::naked_yield();
4636 ++Yields;
4637 }
4638 } else {
4639 SpinPause();
4640 }
4641 }
4642 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4643 }
4644 }
4645
4646 void Thread::SpinRelease(volatile int * adr) {
4647 assert(*adr != 0, "invariant");
4648 OrderAccess::fence(); // guarantee at least release consistency.
4649 // Roach-motel semantics.
4650 // It's safe if subsequent LDs and STs float "up" into the critical section,
4651 // but prior LDs and STs within the critical section can't be allowed
4652 // to reorder or float past the ST that releases the lock.
4653 // Loads and stores in the critical section - which appear in program
4654 // order before the store that releases the lock - must also appear
4655 // before the store that releases the lock in memory visibility order.
4656 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4657 // the ST of 0 into the lock-word which releases the lock, so fence
4658 // more than covers this on all platforms.
4659 *adr = 0;
4660 }
4661
4662 // muxAcquire and muxRelease:
4663 //
4664 // * muxAcquire and muxRelease support a single-word lock-word construct.
4665 // The LSB of the word is set IFF the lock is held.
4666 // The remainder of the word points to the head of a singly-linked list
4667 // of threads blocked on the lock.
4668 //
4669 // * The current implementation of muxAcquire-muxRelease uses its own
4670 // dedicated Thread._MuxEvent instance. If we're interested in
4671 // minimizing the peak number of extant ParkEvent instances then
4672 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4673 // as certain invariants were satisfied. Specifically, care would need
4674 // to be taken with regards to consuming unpark() "permits".
4675 // A safe rule of thumb is that a thread would never call muxAcquire()
4676 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4677 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4678 // consume an unpark() permit intended for monitorenter, for instance.
4679 // One way around this would be to widen the restricted-range semaphore
4680 // implemented in park(). Another alternative would be to provide
4681 // multiple instances of the PlatformEvent() for each thread. One
4682 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4683 //
4684 // * Usage:
4685 // -- Only as leaf locks
4686 // -- for short-term locking only as muxAcquire does not perform
4687 // thread state transitions.
4688 //
4689 // Alternatives:
4690 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4691 // but with parking or spin-then-park instead of pure spinning.
4692 // * Use Taura-Oyama-Yonenzawa locks.
4693 // * It's possible to construct a 1-0 lock if we encode the lockword as
4694 // (List,LockByte). Acquire will CAS the full lockword while Release
4695 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4696 // acquiring threads use timers (ParkTimed) to detect and recover from
4697 // the stranding window. Thread/Node structures must be aligned on 256-byte
4698 // boundaries by using placement-new.
4699 // * Augment MCS with advisory back-link fields maintained with CAS().
4700 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4701 // The validity of the backlinks must be ratified before we trust the value.
4702 // If the backlinks are invalid the exiting thread must back-track through the
4703 // the forward links, which are always trustworthy.
4704 // * Add a successor indication. The LockWord is currently encoded as
4705 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4706 // to provide the usual futile-wakeup optimization.
4707 // See RTStt for details.
4708 // * Consider schedctl.sc_nopreempt to cover the critical section.
4709 //
4710
4711
4712 typedef volatile intptr_t MutexT; // Mux Lock-word
4713 enum MuxBits { LOCKBIT = 1 };
4714
4715 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4716 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4717 if (w == 0) return;
4718 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4719 return;
4720 }
4721
4722 TEVENT(muxAcquire - Contention);
4723 ParkEvent * const Self = Thread::current()->_MuxEvent;
4724 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4725 for (;;) {
4726 int its = (os::is_MP() ? 100 : 0) + 1;
4727
4728 // Optional spin phase: spin-then-park strategy
4729 while (--its >= 0) {
4730 w = *Lock;
4731 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4732 return;
4733 }
4734 }
4735
4736 Self->reset();
4737 Self->OnList = intptr_t(Lock);
4738 // The following fence() isn't _strictly necessary as the subsequent
4739 // CAS() both serializes execution and ratifies the fetched *Lock value.
4740 OrderAccess::fence();
4741 for (;;) {
4742 w = *Lock;
4743 if ((w & LOCKBIT) == 0) {
4744 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4745 Self->OnList = 0; // hygiene - allows stronger asserts
4746 return;
4747 }
4748 continue; // Interference -- *Lock changed -- Just retry
4749 }
4750 assert(w & LOCKBIT, "invariant");
4751 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4752 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4753 }
4754
4755 while (Self->OnList != 0) {
4756 Self->park();
4757 }
4758 }
4759 }
4760
4761 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4762 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4763 if (w == 0) return;
4764 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4765 return;
4766 }
4767
4768 TEVENT(muxAcquire - Contention);
4769 ParkEvent * ReleaseAfter = NULL;
4770 if (ev == NULL) {
4771 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4772 }
4773 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4774 for (;;) {
4775 guarantee(ev->OnList == 0, "invariant");
4776 int its = (os::is_MP() ? 100 : 0) + 1;
4777
4778 // Optional spin phase: spin-then-park strategy
4779 while (--its >= 0) {
4780 w = *Lock;
4781 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4782 if (ReleaseAfter != NULL) {
4783 ParkEvent::Release(ReleaseAfter);
4784 }
4785 return;
4786 }
4787 }
4788
4789 ev->reset();
4790 ev->OnList = intptr_t(Lock);
4791 // The following fence() isn't _strictly necessary as the subsequent
4792 // CAS() both serializes execution and ratifies the fetched *Lock value.
4793 OrderAccess::fence();
4794 for (;;) {
4795 w = *Lock;
4796 if ((w & LOCKBIT) == 0) {
4797 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4798 ev->OnList = 0;
4799 // We call ::Release while holding the outer lock, thus
4800 // artificially lengthening the critical section.
4801 // Consider deferring the ::Release() until the subsequent unlock(),
4802 // after we've dropped the outer lock.
4803 if (ReleaseAfter != NULL) {
4804 ParkEvent::Release(ReleaseAfter);
4805 }
4806 return;
4807 }
4808 continue; // Interference -- *Lock changed -- Just retry
4809 }
4810 assert(w & LOCKBIT, "invariant");
4811 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4812 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4813 }
4814
4815 while (ev->OnList != 0) {
4816 ev->park();
4817 }
4818 }
4819 }
4820
4821 // Release() must extract a successor from the list and then wake that thread.
4822 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4823 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4824 // Release() would :
4825 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4826 // (B) Extract a successor from the private list "in-hand"
4827 // (C) attempt to CAS() the residual back into *Lock over null.
4828 // If there were any newly arrived threads and the CAS() would fail.
4829 // In that case Release() would detach the RATs, re-merge the list in-hand
4830 // with the RATs and repeat as needed. Alternately, Release() might
4831 // detach and extract a successor, but then pass the residual list to the wakee.
4832 // The wakee would be responsible for reattaching and remerging before it
4833 // competed for the lock.
4834 //
4835 // Both "pop" and DMR are immune from ABA corruption -- there can be
4836 // multiple concurrent pushers, but only one popper or detacher.
4837 // This implementation pops from the head of the list. This is unfair,
4838 // but tends to provide excellent throughput as hot threads remain hot.
4839 // (We wake recently run threads first).
4840 //
4841 // All paths through muxRelease() will execute a CAS.
4842 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4843 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4844 // executed within the critical section are complete and globally visible before the
4845 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4846 void Thread::muxRelease(volatile intptr_t * Lock) {
4847 for (;;) {
4848 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4849 assert(w & LOCKBIT, "invariant");
4850 if (w == LOCKBIT) return;
4851 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4852 assert(List != NULL, "invariant");
4853 assert(List->OnList == intptr_t(Lock), "invariant");
4854 ParkEvent * const nxt = List->ListNext;
4855 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4856
4857 // The following CAS() releases the lock and pops the head element.
4858 // The CAS() also ratifies the previously fetched lock-word value.
4859 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4860 continue;
4861 }
4862 List->OnList = 0;
4863 OrderAccess::fence();
4864 List->unpark();
4865 return;
4866 }
4867 }
4868
4869
4870 void Threads::verify() {
4871 ALL_JAVA_THREADS(p) {
4872 p->verify();
4873 }
4874 VMThread* thread = VMThread::vm_thread();
4875 if (thread != NULL) thread->verify();
4876 }