1 /*
2 * Copyright (c) 1997, 2010, 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/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/scopeDesc.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/linkResolver.hpp"
34 #include "jvmtifiles/jvmtiEnv.hpp"
35 #include "memory/oopFactory.hpp"
36 #include "memory/universe.inline.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/objArrayOop.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "oops/symbolOop.hpp"
41 #include "prims/jvm_misc.hpp"
42 #include "prims/jvmtiExport.hpp"
43 #include "prims/jvmtiThreadState.hpp"
44 #include "prims/privilegedStack.hpp"
45 #include "runtime/aprofiler.hpp"
46 #include "runtime/arguments.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/deoptimization.hpp"
49 #include "runtime/fprofiler.hpp"
50 #include "runtime/frame.inline.hpp"
51 #include "runtime/init.hpp"
52 #include "runtime/interfaceSupport.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/javaCalls.hpp"
55 #include "runtime/jniPeriodicChecker.hpp"
56 #include "runtime/memprofiler.hpp"
57 #include "runtime/mutexLocker.hpp"
58 #include "runtime/objectMonitor.hpp"
59 #include "runtime/osThread.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/statSampler.hpp"
63 #include "runtime/stubRoutines.hpp"
64 #include "runtime/task.hpp"
65 #include "runtime/threadCritical.hpp"
66 #include "runtime/threadLocalStorage.hpp"
67 #include "runtime/vframe.hpp"
68 #include "runtime/vframeArray.hpp"
69 #include "runtime/vframe_hp.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "runtime/vm_operations.hpp"
72 #include "services/attachListener.hpp"
73 #include "services/management.hpp"
74 #include "services/threadService.hpp"
75 #include "utilities/defaultStream.hpp"
76 #include "utilities/dtrace.hpp"
77 #include "utilities/events.hpp"
78 #include "utilities/preserveException.hpp"
79 #ifdef TARGET_OS_FAMILY_linux
80 # include "os_linux.inline.hpp"
81 # include "thread_linux.inline.hpp"
82 #endif
83 #ifdef TARGET_OS_FAMILY_solaris
84 # include "os_solaris.inline.hpp"
85 # include "thread_solaris.inline.hpp"
86 #endif
87 #ifdef TARGET_OS_FAMILY_windows
88 # include "os_windows.inline.hpp"
89 # include "thread_windows.inline.hpp"
90 #endif
91 #ifndef SERIALGC
92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
95 #endif
96 #ifdef COMPILER1
97 #include "c1/c1_Compiler.hpp"
98 #endif
99 #ifdef COMPILER2
100 #include "opto/c2compiler.hpp"
101 #include "opto/idealGraphPrinter.hpp"
102 #endif
103
104 #ifdef DTRACE_ENABLED
105
106 // Only bother with this argument setup if dtrace is available
107
108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
111 intptr_t, intptr_t, bool);
112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
113 intptr_t, intptr_t, bool);
114
115 #define DTRACE_THREAD_PROBE(probe, javathread) \
116 { \
117 ResourceMark rm(this); \
118 int len = 0; \
119 const char* name = (javathread)->get_thread_name(); \
120 len = strlen(name); \
121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
122 name, len, \
123 java_lang_Thread::thread_id((javathread)->threadObj()), \
124 (javathread)->osthread()->thread_id(), \
125 java_lang_Thread::is_daemon((javathread)->threadObj())); \
126 }
127
128 #else // ndef DTRACE_ENABLED
129
130 #define DTRACE_THREAD_PROBE(probe, javathread)
131
132 #endif // ndef DTRACE_ENABLED
133
134 // Class hierarchy
135 // - Thread
136 // - VMThread
137 // - WatcherThread
138 // - ConcurrentMarkSweepThread
139 // - JavaThread
140 // - CompilerThread
141
142 // ======= Thread ========
143
144 // Support for forcing alignment of thread objects for biased locking
145 void* Thread::operator new(size_t size) {
146 if (UseBiasedLocking) {
147 const int alignment = markOopDesc::biased_lock_alignment;
148 size_t aligned_size = size + (alignment - sizeof(intptr_t));
149 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
153 "JavaThread alignment code overflowed allocated storage");
154 if (TraceBiasedLocking) {
155 if (aligned_addr != real_malloc_addr)
156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
157 real_malloc_addr, aligned_addr);
158 }
159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
160 return aligned_addr;
161 } else {
162 return CHeapObj::operator new(size);
163 }
164 }
165
166 void Thread::operator delete(void* p) {
167 if (UseBiasedLocking) {
168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
169 CHeapObj::operator delete(real_malloc_addr);
170 } else {
171 CHeapObj::operator delete(p);
172 }
173 }
174
175
176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
177 // JavaThread
178
179
180 Thread::Thread() {
181 // stack
182 _stack_base = NULL;
183 _stack_size = 0;
184 _self_raw_id = 0;
185 _lgrp_id = -1;
186 _osthread = NULL;
187
188 // allocated data structures
189 set_resource_area(new ResourceArea());
190 set_handle_area(new HandleArea(NULL));
191 set_active_handles(NULL);
192 set_free_handle_block(NULL);
193 set_last_handle_mark(NULL);
194 set_osthread(NULL);
195
196 // This initial value ==> never claimed.
197 _oops_do_parity = 0;
198
199 // the handle mark links itself to last_handle_mark
200 new HandleMark(this);
201
202 // plain initialization
203 debug_only(_owned_locks = NULL;)
204 debug_only(_allow_allocation_count = 0;)
205 NOT_PRODUCT(_allow_safepoint_count = 0;)
206 NOT_PRODUCT(_skip_gcalot = false;)
207 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
208 _jvmti_env_iteration_count = 0;
209 _vm_operation_started_count = 0;
210 _vm_operation_completed_count = 0;
211 _current_pending_monitor = NULL;
212 _current_pending_monitor_is_from_java = true;
213 _current_waiting_monitor = NULL;
214 _num_nested_signal = 0;
215 omFreeList = NULL ;
216 omFreeCount = 0 ;
217 omFreeProvision = 32 ;
218 omInUseList = NULL ;
219 omInUseCount = 0 ;
220
221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
222 _suspend_flags = 0;
223
224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
225 _hashStateX = os::random() ;
226 _hashStateY = 842502087 ;
227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
228 _hashStateW = 273326509 ;
229
230 _OnTrap = 0 ;
231 _schedctl = NULL ;
232 _Stalled = 0 ;
233 _TypeTag = 0x2BAD ;
234
235 // Many of the following fields are effectively final - immutable
236 // Note that nascent threads can't use the Native Monitor-Mutex
237 // construct until the _MutexEvent is initialized ...
238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
239 // we might instead use a stack of ParkEvents that we could provision on-demand.
240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
241 // and ::Release()
242 _ParkEvent = ParkEvent::Allocate (this) ;
243 _SleepEvent = ParkEvent::Allocate (this) ;
244 _MutexEvent = ParkEvent::Allocate (this) ;
245 _MuxEvent = ParkEvent::Allocate (this) ;
246
247 #ifdef CHECK_UNHANDLED_OOPS
248 if (CheckUnhandledOops) {
249 _unhandled_oops = new UnhandledOops(this);
250 }
251 #endif // CHECK_UNHANDLED_OOPS
252 #ifdef ASSERT
253 if (UseBiasedLocking) {
254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
255 assert(this == _real_malloc_address ||
256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
257 "bug in forced alignment of thread objects");
258 }
259 #endif /* ASSERT */
260 }
261
262 void Thread::initialize_thread_local_storage() {
263 // Note: Make sure this method only calls
264 // non-blocking operations. Otherwise, it might not work
265 // with the thread-startup/safepoint interaction.
266
267 // During Java thread startup, safepoint code should allow this
268 // method to complete because it may need to allocate memory to
269 // store information for the new thread.
270
271 // initialize structure dependent on thread local storage
272 ThreadLocalStorage::set_thread(this);
273
274 // set up any platform-specific state.
275 os::initialize_thread();
276
277 }
278
279 void Thread::record_stack_base_and_size() {
280 set_stack_base(os::current_stack_base());
281 set_stack_size(os::current_stack_size());
282 }
283
284
285 Thread::~Thread() {
286 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
287 ObjectSynchronizer::omFlush (this) ;
288
289 // deallocate data structures
290 delete resource_area();
291 // since the handle marks are using the handle area, we have to deallocated the root
292 // handle mark before deallocating the thread's handle area,
293 assert(last_handle_mark() != NULL, "check we have an element");
294 delete last_handle_mark();
295 assert(last_handle_mark() == NULL, "check we have reached the end");
296
297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
298 // We NULL out the fields for good hygiene.
299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
303
304 delete handle_area();
305
306 // osthread() can be NULL, if creation of thread failed.
307 if (osthread() != NULL) os::free_thread(osthread());
308
309 delete _SR_lock;
310
311 // clear thread local storage if the Thread is deleting itself
312 if (this == Thread::current()) {
313 ThreadLocalStorage::set_thread(NULL);
314 } else {
315 // In the case where we're not the current thread, invalidate all the
316 // caches in case some code tries to get the current thread or the
317 // thread that was destroyed, and gets stale information.
318 ThreadLocalStorage::invalidate_all();
319 }
320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
321 }
322
323 // NOTE: dummy function for assertion purpose.
324 void Thread::run() {
325 ShouldNotReachHere();
326 }
327
328 #ifdef ASSERT
329 // Private method to check for dangling thread pointer
330 void check_for_dangling_thread_pointer(Thread *thread) {
331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
332 "possibility of dangling Thread pointer");
333 }
334 #endif
335
336
337 #ifndef PRODUCT
338 // Tracing method for basic thread operations
339 void Thread::trace(const char* msg, const Thread* const thread) {
340 if (!TraceThreadEvents) return;
341 ResourceMark rm;
342 ThreadCritical tc;
343 const char *name = "non-Java thread";
344 int prio = -1;
345 if (thread->is_Java_thread()
346 && !thread->is_Compiler_thread()) {
347 // The Threads_lock must be held to get information about
348 // this thread but may not be in some situations when
349 // tracing thread events.
350 bool release_Threads_lock = false;
351 if (!Threads_lock->owned_by_self()) {
352 Threads_lock->lock();
353 release_Threads_lock = true;
354 }
355 JavaThread* jt = (JavaThread *)thread;
356 name = (char *)jt->get_thread_name();
357 oop thread_oop = jt->threadObj();
358 if (thread_oop != NULL) {
359 prio = java_lang_Thread::priority(thread_oop);
360 }
361 if (release_Threads_lock) {
362 Threads_lock->unlock();
363 }
364 }
365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
366 }
367 #endif
368
369
370 ThreadPriority Thread::get_priority(const Thread* const thread) {
371 trace("get priority", thread);
372 ThreadPriority priority;
373 // Can return an error!
374 (void)os::get_priority(thread, priority);
375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
376 return priority;
377 }
378
379 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
380 trace("set priority", thread);
381 debug_only(check_for_dangling_thread_pointer(thread);)
382 // Can return an error!
383 (void)os::set_priority(thread, priority);
384 }
385
386
387 void Thread::start(Thread* thread) {
388 trace("start", thread);
389 // Start is different from resume in that its safety is guaranteed by context or
390 // being called from a Java method synchronized on the Thread object.
391 if (!DisableStartThread) {
392 if (thread->is_Java_thread()) {
393 // Initialize the thread state to RUNNABLE before starting this thread.
394 // Can not set it after the thread started because we do not know the
395 // exact thread state at that time. It could be in MONITOR_WAIT or
396 // in SLEEPING or some other state.
397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
398 java_lang_Thread::RUNNABLE);
399 }
400 os::start_thread(thread);
401 }
402 }
403
404 // Enqueue a VM_Operation to do the job for us - sometime later
405 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
407 VMThread::execute(vm_stop);
408 }
409
410
411 //
412 // Check if an external suspend request has completed (or has been
413 // cancelled). Returns true if the thread is externally suspended and
414 // false otherwise.
415 //
416 // The bits parameter returns information about the code path through
417 // the routine. Useful for debugging:
418 //
419 // set in is_ext_suspend_completed():
420 // 0x00000001 - routine was entered
421 // 0x00000010 - routine return false at end
422 // 0x00000100 - thread exited (return false)
423 // 0x00000200 - suspend request cancelled (return false)
424 // 0x00000400 - thread suspended (return true)
425 // 0x00001000 - thread is in a suspend equivalent state (return true)
426 // 0x00002000 - thread is native and walkable (return true)
427 // 0x00004000 - thread is native_trans and walkable (needed retry)
428 //
429 // set in wait_for_ext_suspend_completion():
430 // 0x00010000 - routine was entered
431 // 0x00020000 - suspend request cancelled before loop (return false)
432 // 0x00040000 - thread suspended before loop (return true)
433 // 0x00080000 - suspend request cancelled in loop (return false)
434 // 0x00100000 - thread suspended in loop (return true)
435 // 0x00200000 - suspend not completed during retry loop (return false)
436 //
437
438 // Helper class for tracing suspend wait debug bits.
439 //
440 // 0x00000100 indicates that the target thread exited before it could
441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
442 // 0x00080000 each indicate a cancelled suspend request so they don't
443 // count as wait failures either.
444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
445
446 class TraceSuspendDebugBits : public StackObj {
447 private:
448 JavaThread * jt;
449 bool is_wait;
450 bool called_by_wait; // meaningful when !is_wait
451 uint32_t * bits;
452
453 public:
454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
455 uint32_t *_bits) {
456 jt = _jt;
457 is_wait = _is_wait;
458 called_by_wait = _called_by_wait;
459 bits = _bits;
460 }
461
462 ~TraceSuspendDebugBits() {
463 if (!is_wait) {
464 #if 1
465 // By default, don't trace bits for is_ext_suspend_completed() calls.
466 // That trace is very chatty.
467 return;
468 #else
469 if (!called_by_wait) {
470 // If tracing for is_ext_suspend_completed() is enabled, then only
471 // trace calls to it from wait_for_ext_suspend_completion()
472 return;
473 }
474 #endif
475 }
476
477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
479 MutexLocker ml(Threads_lock); // needed for get_thread_name()
480 ResourceMark rm;
481
482 tty->print_cr(
483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
484 jt->get_thread_name(), *bits);
485
486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
487 }
488 }
489 }
490 };
491 #undef DEBUG_FALSE_BITS
492
493
494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
496
497 bool did_trans_retry = false; // only do thread_in_native_trans retry once
498 bool do_trans_retry; // flag to force the retry
499
500 *bits |= 0x00000001;
501
502 do {
503 do_trans_retry = false;
504
505 if (is_exiting()) {
506 // Thread is in the process of exiting. This is always checked
507 // first to reduce the risk of dereferencing a freed JavaThread.
508 *bits |= 0x00000100;
509 return false;
510 }
511
512 if (!is_external_suspend()) {
513 // Suspend request is cancelled. This is always checked before
514 // is_ext_suspended() to reduce the risk of a rogue resume
515 // confusing the thread that made the suspend request.
516 *bits |= 0x00000200;
517 return false;
518 }
519
520 if (is_ext_suspended()) {
521 // thread is suspended
522 *bits |= 0x00000400;
523 return true;
524 }
525
526 // Now that we no longer do hard suspends of threads running
527 // native code, the target thread can be changing thread state
528 // while we are in this routine:
529 //
530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
531 //
532 // We save a copy of the thread state as observed at this moment
533 // and make our decision about suspend completeness based on the
534 // copy. This closes the race where the thread state is seen as
535 // _thread_in_native_trans in the if-thread_blocked check, but is
536 // seen as _thread_blocked in if-thread_in_native_trans check.
537 JavaThreadState save_state = thread_state();
538
539 if (save_state == _thread_blocked && is_suspend_equivalent()) {
540 // If the thread's state is _thread_blocked and this blocking
541 // condition is known to be equivalent to a suspend, then we can
542 // consider the thread to be externally suspended. This means that
543 // the code that sets _thread_blocked has been modified to do
544 // self-suspension if the blocking condition releases. We also
545 // used to check for CONDVAR_WAIT here, but that is now covered by
546 // the _thread_blocked with self-suspension check.
547 //
548 // Return true since we wouldn't be here unless there was still an
549 // external suspend request.
550 *bits |= 0x00001000;
551 return true;
552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
553 // Threads running native code will self-suspend on native==>VM/Java
554 // transitions. If its stack is walkable (should always be the case
555 // unless this function is called before the actual java_suspend()
556 // call), then the wait is done.
557 *bits |= 0x00002000;
558 return true;
559 } else if (!called_by_wait && !did_trans_retry &&
560 save_state == _thread_in_native_trans &&
561 frame_anchor()->walkable()) {
562 // The thread is transitioning from thread_in_native to another
563 // thread state. check_safepoint_and_suspend_for_native_trans()
564 // will force the thread to self-suspend. If it hasn't gotten
565 // there yet we may have caught the thread in-between the native
566 // code check above and the self-suspend. Lucky us. If we were
567 // called by wait_for_ext_suspend_completion(), then it
568 // will be doing the retries so we don't have to.
569 //
570 // Since we use the saved thread state in the if-statement above,
571 // there is a chance that the thread has already transitioned to
572 // _thread_blocked by the time we get here. In that case, we will
573 // make a single unnecessary pass through the logic below. This
574 // doesn't hurt anything since we still do the trans retry.
575
576 *bits |= 0x00004000;
577
578 // Once the thread leaves thread_in_native_trans for another
579 // thread state, we break out of this retry loop. We shouldn't
580 // need this flag to prevent us from getting back here, but
581 // sometimes paranoia is good.
582 did_trans_retry = true;
583
584 // We wait for the thread to transition to a more usable state.
585 for (int i = 1; i <= SuspendRetryCount; i++) {
586 // We used to do an "os::yield_all(i)" call here with the intention
587 // that yielding would increase on each retry. However, the parameter
588 // is ignored on Linux which means the yield didn't scale up. Waiting
589 // on the SR_lock below provides a much more predictable scale up for
590 // the delay. It also provides a simple/direct point to check for any
591 // safepoint requests from the VMThread
592
593 // temporarily drops SR_lock while doing wait with safepoint check
594 // (if we're a JavaThread - the WatcherThread can also call this)
595 // and increase delay with each retry
596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
597
598 // check the actual thread state instead of what we saved above
599 if (thread_state() != _thread_in_native_trans) {
600 // the thread has transitioned to another thread state so
601 // try all the checks (except this one) one more time.
602 do_trans_retry = true;
603 break;
604 }
605 } // end retry loop
606
607
608 }
609 } while (do_trans_retry);
610
611 *bits |= 0x00000010;
612 return false;
613 }
614
615 //
616 // Wait for an external suspend request to complete (or be cancelled).
617 // Returns true if the thread is externally suspended and false otherwise.
618 //
619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
620 uint32_t *bits) {
621 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
622 false /* !called_by_wait */, bits);
623
624 // local flag copies to minimize SR_lock hold time
625 bool is_suspended;
626 bool pending;
627 uint32_t reset_bits;
628
629 // set a marker so is_ext_suspend_completed() knows we are the caller
630 *bits |= 0x00010000;
631
632 // We use reset_bits to reinitialize the bits value at the top of
633 // each retry loop. This allows the caller to make use of any
634 // unused bits for their own marking purposes.
635 reset_bits = *bits;
636
637 {
638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
640 delay, bits);
641 pending = is_external_suspend();
642 }
643 // must release SR_lock to allow suspension to complete
644
645 if (!pending) {
646 // A cancelled suspend request is the only false return from
647 // is_ext_suspend_completed() that keeps us from entering the
648 // retry loop.
649 *bits |= 0x00020000;
650 return false;
651 }
652
653 if (is_suspended) {
654 *bits |= 0x00040000;
655 return true;
656 }
657
658 for (int i = 1; i <= retries; i++) {
659 *bits = reset_bits; // reinit to only track last retry
660
661 // We used to do an "os::yield_all(i)" call here with the intention
662 // that yielding would increase on each retry. However, the parameter
663 // is ignored on Linux which means the yield didn't scale up. Waiting
664 // on the SR_lock below provides a much more predictable scale up for
665 // the delay. It also provides a simple/direct point to check for any
666 // safepoint requests from the VMThread
667
668 {
669 MutexLocker ml(SR_lock());
670 // wait with safepoint check (if we're a JavaThread - the WatcherThread
671 // can also call this) and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
673
674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
675 delay, bits);
676
677 // It is possible for the external suspend request to be cancelled
678 // (by a resume) before the actual suspend operation is completed.
679 // Refresh our local copy to see if we still need to wait.
680 pending = is_external_suspend();
681 }
682
683 if (!pending) {
684 // A cancelled suspend request is the only false return from
685 // is_ext_suspend_completed() that keeps us from staying in the
686 // retry loop.
687 *bits |= 0x00080000;
688 return false;
689 }
690
691 if (is_suspended) {
692 *bits |= 0x00100000;
693 return true;
694 }
695 } // end retry loop
696
697 // thread did not suspend after all our retries
698 *bits |= 0x00200000;
699 return false;
700 }
701
702 #ifndef PRODUCT
703 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
704
705 // This should not need to be atomic as the only way for simultaneous
706 // updates is via interrupts. Even then this should be rare or non-existant
707 // and we don't care that much anyway.
708
709 int index = _jmp_ring_index;
710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
711 _jmp_ring[index]._target = (intptr_t) target;
712 _jmp_ring[index]._instruction = (intptr_t) instr;
713 _jmp_ring[index]._file = file;
714 _jmp_ring[index]._line = line;
715 }
716 #endif /* PRODUCT */
717
718 // Called by flat profiler
719 // Callers have already called wait_for_ext_suspend_completion
720 // The assertion for that is currently too complex to put here:
721 bool JavaThread::profile_last_Java_frame(frame* _fr) {
722 bool gotframe = false;
723 // self suspension saves needed state.
724 if (has_last_Java_frame() && _anchor.walkable()) {
725 *_fr = pd_last_frame();
726 gotframe = true;
727 }
728 return gotframe;
729 }
730
731 void Thread::interrupt(Thread* thread) {
732 trace("interrupt", thread);
733 debug_only(check_for_dangling_thread_pointer(thread);)
734 os::interrupt(thread);
735 }
736
737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
738 trace("is_interrupted", thread);
739 debug_only(check_for_dangling_thread_pointer(thread);)
740 // Note: If clear_interrupted==false, this simply fetches and
741 // returns the value of the field osthread()->interrupted().
742 return os::is_interrupted(thread, clear_interrupted);
743 }
744
745
746 // GC Support
747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
748 jint thread_parity = _oops_do_parity;
749 if (thread_parity != strong_roots_parity) {
750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
751 if (res == thread_parity) return true;
752 else {
753 guarantee(res == strong_roots_parity, "Or else what?");
754 assert(SharedHeap::heap()->n_par_threads() > 0,
755 "Should only fail when parallel.");
756 return false;
757 }
758 }
759 assert(SharedHeap::heap()->n_par_threads() > 0,
760 "Should only fail when parallel.");
761 return false;
762 }
763
764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
765 active_handles()->oops_do(f);
766 // Do oop for ThreadShadow
767 f->do_oop((oop*)&_pending_exception);
768 handle_area()->oops_do(f);
769 }
770
771 void Thread::nmethods_do(CodeBlobClosure* cf) {
772 // no nmethods in a generic thread...
773 }
774
775 void Thread::print_on(outputStream* st) const {
776 // get_priority assumes osthread initialized
777 if (osthread() != NULL) {
778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
779 osthread()->print_on(st);
780 }
781 debug_only(if (WizardMode) print_owned_locks_on(st);)
782 }
783
784 // Thread::print_on_error() is called by fatal error handler. Don't use
785 // any lock or allocate memory.
786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
787 if (is_VM_thread()) st->print("VMThread");
788 else if (is_Compiler_thread()) st->print("CompilerThread");
789 else if (is_Java_thread()) st->print("JavaThread");
790 else if (is_GC_task_thread()) st->print("GCTaskThread");
791 else if (is_Watcher_thread()) st->print("WatcherThread");
792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
793 else st->print("Thread");
794
795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
796 _stack_base - _stack_size, _stack_base);
797
798 if (osthread()) {
799 st->print(" [id=%d]", osthread()->thread_id());
800 }
801 }
802
803 #ifdef ASSERT
804 void Thread::print_owned_locks_on(outputStream* st) const {
805 Monitor *cur = _owned_locks;
806 if (cur == NULL) {
807 st->print(" (no locks) ");
808 } else {
809 st->print_cr(" Locks owned:");
810 while(cur) {
811 cur->print_on(st);
812 cur = cur->next();
813 }
814 }
815 }
816
817 static int ref_use_count = 0;
818
819 bool Thread::owns_locks_but_compiled_lock() const {
820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
821 if (cur != Compile_lock) return true;
822 }
823 return false;
824 }
825
826
827 #endif
828
829 #ifndef PRODUCT
830
831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
833 // no threads which allow_vm_block's are held
834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
835 // Check if current thread is allowed to block at a safepoint
836 if (!(_allow_safepoint_count == 0))
837 fatal("Possible safepoint reached by thread that does not allow it");
838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
839 fatal("LEAF method calling lock?");
840 }
841
842 #ifdef ASSERT
843 if (potential_vm_operation && is_Java_thread()
844 && !Universe::is_bootstrapping()) {
845 // Make sure we do not hold any locks that the VM thread also uses.
846 // This could potentially lead to deadlocks
847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
848 // Threads_lock is special, since the safepoint synchronization will not start before this is
849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
850 // since it is used to transfer control between JavaThreads and the VMThread
851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
852 if ( (cur->allow_vm_block() &&
853 cur != Threads_lock &&
854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
855 cur != VMOperationRequest_lock &&
856 cur != VMOperationQueue_lock) ||
857 cur->rank() == Mutex::special) {
858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
859 }
860 }
861 }
862
863 if (GCALotAtAllSafepoints) {
864 // We could enter a safepoint here and thus have a gc
865 InterfaceSupport::check_gc_alot();
866 }
867 #endif
868 }
869 #endif
870
871 bool Thread::is_in_stack(address adr) const {
872 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
873 address end = os::current_stack_pointer();
874 if (stack_base() >= adr && adr >= end) return true;
875
876 return false;
877 }
878
879
880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
882 // used for compilation in the future. If that change is made, the need for these methods
883 // should be revisited, and they should be removed if possible.
884
885 bool Thread::is_lock_owned(address adr) const {
886 return on_local_stack(adr);
887 }
888
889 bool Thread::set_as_starting_thread() {
890 // NOTE: this must be called inside the main thread.
891 return os::create_main_thread((JavaThread*)this);
892 }
893
894 static void initialize_class(symbolHandle class_name, TRAPS) {
895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
896 instanceKlass::cast(klass)->initialize(CHECK);
897 }
898
899
900 // Creates the initial ThreadGroup
901 static Handle create_initial_thread_group(TRAPS) {
902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_ThreadGroup(), true, CHECK_NH);
903 instanceKlassHandle klass (THREAD, k);
904
905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
906 {
907 JavaValue result(T_VOID);
908 JavaCalls::call_special(&result,
909 system_instance,
910 klass,
911 vmSymbolHandles::object_initializer_name(),
912 vmSymbolHandles::void_method_signature(),
913 CHECK_NH);
914 }
915 Universe::set_system_thread_group(system_instance());
916
917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
918 {
919 JavaValue result(T_VOID);
920 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
921 JavaCalls::call_special(&result,
922 main_instance,
923 klass,
924 vmSymbolHandles::object_initializer_name(),
925 vmSymbolHandles::threadgroup_string_void_signature(),
926 system_instance,
927 string,
928 CHECK_NH);
929 }
930 return main_instance;
931 }
932
933 // Creates the initial Thread
934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK_NULL);
936 instanceKlassHandle klass (THREAD, k);
937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
938
939 java_lang_Thread::set_thread(thread_oop(), thread);
940 java_lang_Thread::set_priority(thread_oop(), NormPriority);
941 thread->set_threadObj(thread_oop());
942
943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
944
945 JavaValue result(T_VOID);
946 JavaCalls::call_special(&result, thread_oop,
947 klass,
948 vmSymbolHandles::object_initializer_name(),
949 vmSymbolHandles::threadgroup_string_void_signature(),
950 thread_group,
951 string,
952 CHECK_NULL);
953 return thread_oop();
954 }
955
956 static void call_initializeSystemClass(TRAPS) {
957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
958 instanceKlassHandle klass (THREAD, k);
959
960 JavaValue result(T_VOID);
961 JavaCalls::call_static(&result, klass, vmSymbolHandles::initializeSystemClass_name(),
962 vmSymbolHandles::void_method_signature(), CHECK);
963 }
964
965 #ifdef KERNEL
966 static void set_jkernel_boot_classloader_hook(TRAPS) {
967 klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass();
968 instanceKlassHandle klass (THREAD, k);
969
970 if (k == NULL) {
971 // sun.jkernel.DownloadManager may not present in the JDK; just return
972 return;
973 }
974
975 JavaValue result(T_VOID);
976 JavaCalls::call_static(&result, klass, vmSymbolHandles::setBootClassLoaderHook_name(),
977 vmSymbolHandles::void_method_signature(), CHECK);
978 }
979 #endif // KERNEL
980
981 static void reset_vm_info_property(TRAPS) {
982 // the vm info string
983 ResourceMark rm(THREAD);
984 const char *vm_info = VM_Version::vm_info_string();
985
986 // java.lang.System class
987 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
988 instanceKlassHandle klass (THREAD, k);
989
990 // setProperty arguments
991 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
992 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
993
994 // return value
995 JavaValue r(T_OBJECT);
996
997 // public static String setProperty(String key, String value);
998 JavaCalls::call_static(&r,
999 klass,
1000 vmSymbolHandles::setProperty_name(),
1001 vmSymbolHandles::string_string_string_signature(),
1002 key_str,
1003 value_str,
1004 CHECK);
1005 }
1006
1007
1008 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1009 assert(thread_group.not_null(), "thread group should be specified");
1010 assert(threadObj() == NULL, "should only create Java thread object once");
1011
1012 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
1013 instanceKlassHandle klass (THREAD, k);
1014 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1015
1016 java_lang_Thread::set_thread(thread_oop(), this);
1017 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1018 set_threadObj(thread_oop());
1019
1020 JavaValue result(T_VOID);
1021 if (thread_name != NULL) {
1022 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1023 // Thread gets assigned specified name and null target
1024 JavaCalls::call_special(&result,
1025 thread_oop,
1026 klass,
1027 vmSymbolHandles::object_initializer_name(),
1028 vmSymbolHandles::threadgroup_string_void_signature(),
1029 thread_group, // Argument 1
1030 name, // Argument 2
1031 THREAD);
1032 } else {
1033 // Thread gets assigned name "Thread-nnn" and null target
1034 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1035 JavaCalls::call_special(&result,
1036 thread_oop,
1037 klass,
1038 vmSymbolHandles::object_initializer_name(),
1039 vmSymbolHandles::threadgroup_runnable_void_signature(),
1040 thread_group, // Argument 1
1041 Handle(), // Argument 2
1042 THREAD);
1043 }
1044
1045
1046 if (daemon) {
1047 java_lang_Thread::set_daemon(thread_oop());
1048 }
1049
1050 if (HAS_PENDING_EXCEPTION) {
1051 return;
1052 }
1053
1054 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1055 Handle threadObj(this, this->threadObj());
1056
1057 JavaCalls::call_special(&result,
1058 thread_group,
1059 group,
1060 vmSymbolHandles::add_method_name(),
1061 vmSymbolHandles::thread_void_signature(),
1062 threadObj, // Arg 1
1063 THREAD);
1064
1065
1066 }
1067
1068 // NamedThread -- non-JavaThread subclasses with multiple
1069 // uniquely named instances should derive from this.
1070 NamedThread::NamedThread() : Thread() {
1071 _name = NULL;
1072 _processed_thread = NULL;
1073 }
1074
1075 NamedThread::~NamedThread() {
1076 if (_name != NULL) {
1077 FREE_C_HEAP_ARRAY(char, _name);
1078 _name = NULL;
1079 }
1080 }
1081
1082 void NamedThread::set_name(const char* format, ...) {
1083 guarantee(_name == NULL, "Only get to set name once.");
1084 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1085 guarantee(_name != NULL, "alloc failure");
1086 va_list ap;
1087 va_start(ap, format);
1088 jio_vsnprintf(_name, max_name_len, format, ap);
1089 va_end(ap);
1090 }
1091
1092 // ======= WatcherThread ========
1093
1094 // The watcher thread exists to simulate timer interrupts. It should
1095 // be replaced by an abstraction over whatever native support for
1096 // timer interrupts exists on the platform.
1097
1098 WatcherThread* WatcherThread::_watcher_thread = NULL;
1099 volatile bool WatcherThread::_should_terminate = false;
1100
1101 WatcherThread::WatcherThread() : Thread() {
1102 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1103 if (os::create_thread(this, os::watcher_thread)) {
1104 _watcher_thread = this;
1105
1106 // Set the watcher thread to the highest OS priority which should not be
1107 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1108 // is created. The only normal thread using this priority is the reference
1109 // handler thread, which runs for very short intervals only.
1110 // If the VMThread's priority is not lower than the WatcherThread profiling
1111 // will be inaccurate.
1112 os::set_priority(this, MaxPriority);
1113 if (!DisableStartThread) {
1114 os::start_thread(this);
1115 }
1116 }
1117 }
1118
1119 void WatcherThread::run() {
1120 assert(this == watcher_thread(), "just checking");
1121
1122 this->record_stack_base_and_size();
1123 this->initialize_thread_local_storage();
1124 this->set_active_handles(JNIHandleBlock::allocate_block());
1125 while(!_should_terminate) {
1126 assert(watcher_thread() == Thread::current(), "thread consistency check");
1127 assert(watcher_thread() == this, "thread consistency check");
1128
1129 // Calculate how long it'll be until the next PeriodicTask work
1130 // should be done, and sleep that amount of time.
1131 size_t time_to_wait = PeriodicTask::time_to_wait();
1132
1133 // we expect this to timeout - we only ever get unparked when
1134 // we should terminate
1135 {
1136 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1137
1138 jlong prev_time = os::javaTimeNanos();
1139 for (;;) {
1140 int res= _SleepEvent->park(time_to_wait);
1141 if (res == OS_TIMEOUT || _should_terminate)
1142 break;
1143 // spurious wakeup of some kind
1144 jlong now = os::javaTimeNanos();
1145 time_to_wait -= (now - prev_time) / 1000000;
1146 if (time_to_wait <= 0)
1147 break;
1148 prev_time = now;
1149 }
1150 }
1151
1152 if (is_error_reported()) {
1153 // A fatal error has happened, the error handler(VMError::report_and_die)
1154 // should abort JVM after creating an error log file. However in some
1155 // rare cases, the error handler itself might deadlock. Here we try to
1156 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1157 //
1158 // This code is in WatcherThread because WatcherThread wakes up
1159 // periodically so the fatal error handler doesn't need to do anything;
1160 // also because the WatcherThread is less likely to crash than other
1161 // threads.
1162
1163 for (;;) {
1164 if (!ShowMessageBoxOnError
1165 && (OnError == NULL || OnError[0] == '\0')
1166 && Arguments::abort_hook() == NULL) {
1167 os::sleep(this, 2 * 60 * 1000, false);
1168 fdStream err(defaultStream::output_fd());
1169 err.print_raw_cr("# [ timer expired, abort... ]");
1170 // skip atexit/vm_exit/vm_abort hooks
1171 os::die();
1172 }
1173
1174 // Wake up 5 seconds later, the fatal handler may reset OnError or
1175 // ShowMessageBoxOnError when it is ready to abort.
1176 os::sleep(this, 5 * 1000, false);
1177 }
1178 }
1179
1180 PeriodicTask::real_time_tick(time_to_wait);
1181
1182 // If we have no more tasks left due to dynamic disenrollment,
1183 // shut down the thread since we don't currently support dynamic enrollment
1184 if (PeriodicTask::num_tasks() == 0) {
1185 _should_terminate = true;
1186 }
1187 }
1188
1189 // Signal that it is terminated
1190 {
1191 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1192 _watcher_thread = NULL;
1193 Terminator_lock->notify();
1194 }
1195
1196 // Thread destructor usually does this..
1197 ThreadLocalStorage::set_thread(NULL);
1198 }
1199
1200 void WatcherThread::start() {
1201 if (watcher_thread() == NULL) {
1202 _should_terminate = false;
1203 // Create the single instance of WatcherThread
1204 new WatcherThread();
1205 }
1206 }
1207
1208 void WatcherThread::stop() {
1209 // it is ok to take late safepoints here, if needed
1210 MutexLocker mu(Terminator_lock);
1211 _should_terminate = true;
1212 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1213
1214 Thread* watcher = watcher_thread();
1215 if (watcher != NULL)
1216 watcher->_SleepEvent->unpark();
1217
1218 while(watcher_thread() != NULL) {
1219 // This wait should make safepoint checks, wait without a timeout,
1220 // and wait as a suspend-equivalent condition.
1221 //
1222 // Note: If the FlatProfiler is running, then this thread is waiting
1223 // for the WatcherThread to terminate and the WatcherThread, via the
1224 // FlatProfiler task, is waiting for the external suspend request on
1225 // this thread to complete. wait_for_ext_suspend_completion() will
1226 // eventually timeout, but that takes time. Making this wait a
1227 // suspend-equivalent condition solves that timeout problem.
1228 //
1229 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1230 Mutex::_as_suspend_equivalent_flag);
1231 }
1232 }
1233
1234 void WatcherThread::print_on(outputStream* st) const {
1235 st->print("\"%s\" ", name());
1236 Thread::print_on(st);
1237 st->cr();
1238 }
1239
1240 // ======= JavaThread ========
1241
1242 // A JavaThread is a normal Java thread
1243
1244 void JavaThread::initialize() {
1245 // Initialize fields
1246
1247 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1248 set_claimed_par_id(-1);
1249
1250 set_saved_exception_pc(NULL);
1251 set_threadObj(NULL);
1252 _anchor.clear();
1253 set_entry_point(NULL);
1254 set_jni_functions(jni_functions());
1255 set_callee_target(NULL);
1256 set_vm_result(NULL);
1257 set_vm_result_2(NULL);
1258 set_vframe_array_head(NULL);
1259 set_vframe_array_last(NULL);
1260 set_deferred_locals(NULL);
1261 set_deopt_mark(NULL);
1262 set_deopt_nmethod(NULL);
1263 clear_must_deopt_id();
1264 set_monitor_chunks(NULL);
1265 set_next(NULL);
1266 set_thread_state(_thread_new);
1267 _terminated = _not_terminated;
1268 _privileged_stack_top = NULL;
1269 _array_for_gc = NULL;
1270 _suspend_equivalent = false;
1271 _in_deopt_handler = 0;
1272 _doing_unsafe_access = false;
1273 _stack_guard_state = stack_guard_unused;
1274 _exception_oop = NULL;
1275 _exception_pc = 0;
1276 _exception_handler_pc = 0;
1277 _exception_stack_size = 0;
1278 _is_method_handle_return = 0;
1279 _jvmti_thread_state= NULL;
1280 _should_post_on_exceptions_flag = JNI_FALSE;
1281 _jvmti_get_loaded_classes_closure = NULL;
1282 _interp_only_mode = 0;
1283 _special_runtime_exit_condition = _no_async_condition;
1284 _pending_async_exception = NULL;
1285 _is_compiling = false;
1286 _thread_stat = NULL;
1287 _thread_stat = new ThreadStatistics();
1288 _blocked_on_compilation = false;
1289 _jni_active_critical = 0;
1290 _do_not_unlock_if_synchronized = false;
1291 _cached_monitor_info = NULL;
1292 _parker = Parker::Allocate(this) ;
1293
1294 #ifndef PRODUCT
1295 _jmp_ring_index = 0;
1296 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1297 record_jump(NULL, NULL, NULL, 0);
1298 }
1299 #endif /* PRODUCT */
1300
1301 set_thread_profiler(NULL);
1302 if (FlatProfiler::is_active()) {
1303 // This is where we would decide to either give each thread it's own profiler
1304 // or use one global one from FlatProfiler,
1305 // or up to some count of the number of profiled threads, etc.
1306 ThreadProfiler* pp = new ThreadProfiler();
1307 pp->engage();
1308 set_thread_profiler(pp);
1309 }
1310
1311 // Setup safepoint state info for this thread
1312 ThreadSafepointState::create(this);
1313
1314 debug_only(_java_call_counter = 0);
1315
1316 // JVMTI PopFrame support
1317 _popframe_condition = popframe_inactive;
1318 _popframe_preserved_args = NULL;
1319 _popframe_preserved_args_size = 0;
1320
1321 pd_initialize();
1322 }
1323
1324 #ifndef SERIALGC
1325 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1326 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1327 #endif // !SERIALGC
1328
1329 JavaThread::JavaThread(bool is_attaching) :
1330 Thread()
1331 #ifndef SERIALGC
1332 , _satb_mark_queue(&_satb_mark_queue_set),
1333 _dirty_card_queue(&_dirty_card_queue_set)
1334 #endif // !SERIALGC
1335 {
1336 initialize();
1337 _is_attaching = is_attaching;
1338 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1339 }
1340
1341 bool JavaThread::reguard_stack(address cur_sp) {
1342 if (_stack_guard_state != stack_guard_yellow_disabled) {
1343 return true; // Stack already guarded or guard pages not needed.
1344 }
1345
1346 if (register_stack_overflow()) {
1347 // For those architectures which have separate register and
1348 // memory stacks, we must check the register stack to see if
1349 // it has overflowed.
1350 return false;
1351 }
1352
1353 // Java code never executes within the yellow zone: the latter is only
1354 // there to provoke an exception during stack banging. If java code
1355 // is executing there, either StackShadowPages should be larger, or
1356 // some exception code in c1, c2 or the interpreter isn't unwinding
1357 // when it should.
1358 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1359
1360 enable_stack_yellow_zone();
1361 return true;
1362 }
1363
1364 bool JavaThread::reguard_stack(void) {
1365 return reguard_stack(os::current_stack_pointer());
1366 }
1367
1368
1369 void JavaThread::block_if_vm_exited() {
1370 if (_terminated == _vm_exited) {
1371 // _vm_exited is set at safepoint, and Threads_lock is never released
1372 // we will block here forever
1373 Threads_lock->lock_without_safepoint_check();
1374 ShouldNotReachHere();
1375 }
1376 }
1377
1378
1379 // Remove this ifdef when C1 is ported to the compiler interface.
1380 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1381
1382 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1383 Thread()
1384 #ifndef SERIALGC
1385 , _satb_mark_queue(&_satb_mark_queue_set),
1386 _dirty_card_queue(&_dirty_card_queue_set)
1387 #endif // !SERIALGC
1388 {
1389 if (TraceThreadEvents) {
1390 tty->print_cr("creating thread %p", this);
1391 }
1392 initialize();
1393 _is_attaching = false;
1394 set_entry_point(entry_point);
1395 // Create the native thread itself.
1396 // %note runtime_23
1397 os::ThreadType thr_type = os::java_thread;
1398 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1399 os::java_thread;
1400 os::create_thread(this, thr_type, stack_sz);
1401
1402 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1403 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1404 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1405 // the exception consists of creating the exception object & initializing it, initialization
1406 // will leave the VM via a JavaCall and then all locks must be unlocked).
1407 //
1408 // The thread is still suspended when we reach here. Thread must be explicit started
1409 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1410 // by calling Threads:add. The reason why this is not done here, is because the thread
1411 // object must be fully initialized (take a look at JVM_Start)
1412 }
1413
1414 JavaThread::~JavaThread() {
1415 if (TraceThreadEvents) {
1416 tty->print_cr("terminate thread %p", this);
1417 }
1418
1419 // JSR166 -- return the parker to the free list
1420 Parker::Release(_parker);
1421 _parker = NULL ;
1422
1423 // Free any remaining previous UnrollBlock
1424 vframeArray* old_array = vframe_array_last();
1425
1426 if (old_array != NULL) {
1427 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1428 old_array->set_unroll_block(NULL);
1429 delete old_info;
1430 delete old_array;
1431 }
1432
1433 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1434 if (deferred != NULL) {
1435 // This can only happen if thread is destroyed before deoptimization occurs.
1436 assert(deferred->length() != 0, "empty array!");
1437 do {
1438 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1439 deferred->remove_at(0);
1440 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1441 delete dlv;
1442 } while (deferred->length() != 0);
1443 delete deferred;
1444 }
1445
1446 // All Java related clean up happens in exit
1447 ThreadSafepointState::destroy(this);
1448 if (_thread_profiler != NULL) delete _thread_profiler;
1449 if (_thread_stat != NULL) delete _thread_stat;
1450 }
1451
1452
1453 // The first routine called by a new Java thread
1454 void JavaThread::run() {
1455 // initialize thread-local alloc buffer related fields
1456 this->initialize_tlab();
1457
1458 // used to test validitity of stack trace backs
1459 this->record_base_of_stack_pointer();
1460
1461 // Record real stack base and size.
1462 this->record_stack_base_and_size();
1463
1464 // Initialize thread local storage; set before calling MutexLocker
1465 this->initialize_thread_local_storage();
1466
1467 this->create_stack_guard_pages();
1468
1469 this->cache_global_variables();
1470
1471 // Thread is now sufficient initialized to be handled by the safepoint code as being
1472 // in the VM. Change thread state from _thread_new to _thread_in_vm
1473 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1474
1475 assert(JavaThread::current() == this, "sanity check");
1476 assert(!Thread::current()->owns_locks(), "sanity check");
1477
1478 DTRACE_THREAD_PROBE(start, this);
1479
1480 // This operation might block. We call that after all safepoint checks for a new thread has
1481 // been completed.
1482 this->set_active_handles(JNIHandleBlock::allocate_block());
1483
1484 if (JvmtiExport::should_post_thread_life()) {
1485 JvmtiExport::post_thread_start(this);
1486 }
1487
1488 // We call another function to do the rest so we are sure that the stack addresses used
1489 // from there will be lower than the stack base just computed
1490 thread_main_inner();
1491
1492 // Note, thread is no longer valid at this point!
1493 }
1494
1495
1496 void JavaThread::thread_main_inner() {
1497 assert(JavaThread::current() == this, "sanity check");
1498 assert(this->threadObj() != NULL, "just checking");
1499
1500 // Execute thread entry point. If this thread is being asked to restart,
1501 // or has been stopped before starting, do not reexecute entry point.
1502 // Note: Due to JVM_StopThread we can have pending exceptions already!
1503 if (!this->has_pending_exception() && !java_lang_Thread::is_stillborn(this->threadObj())) {
1504 // enter the thread's entry point only if we have no pending exceptions
1505 HandleMark hm(this);
1506 this->entry_point()(this, this);
1507 }
1508
1509 DTRACE_THREAD_PROBE(stop, this);
1510
1511 this->exit(false);
1512 delete this;
1513 }
1514
1515
1516 static void ensure_join(JavaThread* thread) {
1517 // We do not need to grap the Threads_lock, since we are operating on ourself.
1518 Handle threadObj(thread, thread->threadObj());
1519 assert(threadObj.not_null(), "java thread object must exist");
1520 ObjectLocker lock(threadObj, thread);
1521 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1522 thread->clear_pending_exception();
1523 // It is of profound importance that we set the stillborn bit and reset the thread object,
1524 // before we do the notify. Since, changing these two variable will make JVM_IsAlive return
1525 // false. So in case another thread is doing a join on this thread , it will detect that the thread
1526 // is dead when it gets notified.
1527 java_lang_Thread::set_stillborn(threadObj());
1528 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1529 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1530 java_lang_Thread::set_thread(threadObj(), NULL);
1531 lock.notify_all(thread);
1532 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1533 thread->clear_pending_exception();
1534 }
1535
1536
1537 // For any new cleanup additions, please check to see if they need to be applied to
1538 // cleanup_failed_attach_current_thread as well.
1539 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1540 assert(this == JavaThread::current(), "thread consistency check");
1541 if (!InitializeJavaLangSystem) return;
1542
1543 HandleMark hm(this);
1544 Handle uncaught_exception(this, this->pending_exception());
1545 this->clear_pending_exception();
1546 Handle threadObj(this, this->threadObj());
1547 assert(threadObj.not_null(), "Java thread object should be created");
1548
1549 if (get_thread_profiler() != NULL) {
1550 get_thread_profiler()->disengage();
1551 ResourceMark rm;
1552 get_thread_profiler()->print(get_thread_name());
1553 }
1554
1555
1556 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1557 {
1558 EXCEPTION_MARK;
1559
1560 CLEAR_PENDING_EXCEPTION;
1561 }
1562 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1563 // has to be fixed by a runtime query method
1564 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1565 // JSR-166: change call from from ThreadGroup.uncaughtException to
1566 // java.lang.Thread.dispatchUncaughtException
1567 if (uncaught_exception.not_null()) {
1568 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1569 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1570 (address)uncaught_exception(), (address)threadObj(), (address)group());
1571 {
1572 EXCEPTION_MARK;
1573 // Check if the method Thread.dispatchUncaughtException() exists. If so
1574 // call it. Otherwise we have an older library without the JSR-166 changes,
1575 // so call ThreadGroup.uncaughtException()
1576 KlassHandle recvrKlass(THREAD, threadObj->klass());
1577 CallInfo callinfo;
1578 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1579 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1580 vmSymbolHandles::dispatchUncaughtException_name(),
1581 vmSymbolHandles::throwable_void_signature(),
1582 KlassHandle(), false, false, THREAD);
1583 CLEAR_PENDING_EXCEPTION;
1584 methodHandle method = callinfo.selected_method();
1585 if (method.not_null()) {
1586 JavaValue result(T_VOID);
1587 JavaCalls::call_virtual(&result,
1588 threadObj, thread_klass,
1589 vmSymbolHandles::dispatchUncaughtException_name(),
1590 vmSymbolHandles::throwable_void_signature(),
1591 uncaught_exception,
1592 THREAD);
1593 } else {
1594 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1595 JavaValue result(T_VOID);
1596 JavaCalls::call_virtual(&result,
1597 group, thread_group,
1598 vmSymbolHandles::uncaughtException_name(),
1599 vmSymbolHandles::thread_throwable_void_signature(),
1600 threadObj, // Arg 1
1601 uncaught_exception, // Arg 2
1602 THREAD);
1603 }
1604 CLEAR_PENDING_EXCEPTION;
1605 }
1606 }
1607
1608 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1609 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1610 // is deprecated anyhow.
1611 { int count = 3;
1612 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1613 EXCEPTION_MARK;
1614 JavaValue result(T_VOID);
1615 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1616 JavaCalls::call_virtual(&result,
1617 threadObj, thread_klass,
1618 vmSymbolHandles::exit_method_name(),
1619 vmSymbolHandles::void_method_signature(),
1620 THREAD);
1621 CLEAR_PENDING_EXCEPTION;
1622 }
1623 }
1624
1625 // notify JVMTI
1626 if (JvmtiExport::should_post_thread_life()) {
1627 JvmtiExport::post_thread_end(this);
1628 }
1629
1630 // We have notified the agents that we are exiting, before we go on,
1631 // we must check for a pending external suspend request and honor it
1632 // in order to not surprise the thread that made the suspend request.
1633 while (true) {
1634 {
1635 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1636 if (!is_external_suspend()) {
1637 set_terminated(_thread_exiting);
1638 ThreadService::current_thread_exiting(this);
1639 break;
1640 }
1641 // Implied else:
1642 // Things get a little tricky here. We have a pending external
1643 // suspend request, but we are holding the SR_lock so we
1644 // can't just self-suspend. So we temporarily drop the lock
1645 // and then self-suspend.
1646 }
1647
1648 ThreadBlockInVM tbivm(this);
1649 java_suspend_self();
1650
1651 // We're done with this suspend request, but we have to loop around
1652 // and check again. Eventually we will get SR_lock without a pending
1653 // external suspend request and will be able to mark ourselves as
1654 // exiting.
1655 }
1656 // no more external suspends are allowed at this point
1657 } else {
1658 // before_exit() has already posted JVMTI THREAD_END events
1659 }
1660
1661 // Notify waiters on thread object. This has to be done after exit() is called
1662 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1663 // group should have the destroyed bit set before waiters are notified).
1664 ensure_join(this);
1665 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1666
1667 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1668 // held by this thread must be released. A detach operation must only
1669 // get here if there are no Java frames on the stack. Therefore, any
1670 // owned monitors at this point MUST be JNI-acquired monitors which are
1671 // pre-inflated and in the monitor cache.
1672 //
1673 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1674 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1675 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1676 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1677 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1678 }
1679
1680 // These things needs to be done while we are still a Java Thread. Make sure that thread
1681 // is in a consistent state, in case GC happens
1682 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1683
1684 if (active_handles() != NULL) {
1685 JNIHandleBlock* block = active_handles();
1686 set_active_handles(NULL);
1687 JNIHandleBlock::release_block(block);
1688 }
1689
1690 if (free_handle_block() != NULL) {
1691 JNIHandleBlock* block = free_handle_block();
1692 set_free_handle_block(NULL);
1693 JNIHandleBlock::release_block(block);
1694 }
1695
1696 // These have to be removed while this is still a valid thread.
1697 remove_stack_guard_pages();
1698
1699 if (UseTLAB) {
1700 tlab().make_parsable(true); // retire TLAB
1701 }
1702
1703 if (JvmtiEnv::environments_might_exist()) {
1704 MutexLocker mu(JvmtiThreadState_lock);
1705 if (jvmti_thread_state() != NULL) {
1706 JvmtiExport::cleanup_thread(this);
1707 }
1708 }
1709
1710 #ifndef SERIALGC
1711 // We must flush G1-related buffers before removing a thread from
1712 // the list of active threads.
1713 if (UseG1GC) {
1714 flush_barrier_queues();
1715 }
1716 #endif
1717
1718 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1719 Threads::remove(this);
1720 }
1721
1722 #ifndef SERIALGC
1723 // Flush G1-related queues.
1724 void JavaThread::flush_barrier_queues() {
1725 satb_mark_queue().flush();
1726 dirty_card_queue().flush();
1727 }
1728
1729 void JavaThread::initialize_queues() {
1730 assert(!SafepointSynchronize::is_at_safepoint(),
1731 "we should not be at a safepoint");
1732
1733 ObjPtrQueue& satb_queue = satb_mark_queue();
1734 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1735 // The SATB queue should have been constructed with its active
1736 // field set to false.
1737 assert(!satb_queue.is_active(), "SATB queue should not be active");
1738 assert(satb_queue.is_empty(), "SATB queue should be empty");
1739 // If we are creating the thread during a marking cycle, we should
1740 // set the active field of the SATB queue to true.
1741 if (satb_queue_set.is_active()) {
1742 satb_queue.set_active(true);
1743 }
1744
1745 DirtyCardQueue& dirty_queue = dirty_card_queue();
1746 // The dirty card queue should have been constructed with its
1747 // active field set to true.
1748 assert(dirty_queue.is_active(), "dirty card queue should be active");
1749 }
1750 #endif // !SERIALGC
1751
1752 void JavaThread::cleanup_failed_attach_current_thread() {
1753 if (get_thread_profiler() != NULL) {
1754 get_thread_profiler()->disengage();
1755 ResourceMark rm;
1756 get_thread_profiler()->print(get_thread_name());
1757 }
1758
1759 if (active_handles() != NULL) {
1760 JNIHandleBlock* block = active_handles();
1761 set_active_handles(NULL);
1762 JNIHandleBlock::release_block(block);
1763 }
1764
1765 if (free_handle_block() != NULL) {
1766 JNIHandleBlock* block = free_handle_block();
1767 set_free_handle_block(NULL);
1768 JNIHandleBlock::release_block(block);
1769 }
1770
1771 // These have to be removed while this is still a valid thread.
1772 remove_stack_guard_pages();
1773
1774 if (UseTLAB) {
1775 tlab().make_parsable(true); // retire TLAB, if any
1776 }
1777
1778 #ifndef SERIALGC
1779 if (UseG1GC) {
1780 flush_barrier_queues();
1781 }
1782 #endif
1783
1784 Threads::remove(this);
1785 delete this;
1786 }
1787
1788
1789
1790
1791 JavaThread* JavaThread::active() {
1792 Thread* thread = ThreadLocalStorage::thread();
1793 assert(thread != NULL, "just checking");
1794 if (thread->is_Java_thread()) {
1795 return (JavaThread*) thread;
1796 } else {
1797 assert(thread->is_VM_thread(), "this must be a vm thread");
1798 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1799 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1800 assert(ret->is_Java_thread(), "must be a Java thread");
1801 return ret;
1802 }
1803 }
1804
1805 bool JavaThread::is_lock_owned(address adr) const {
1806 if (Thread::is_lock_owned(adr)) return true;
1807
1808 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1809 if (chunk->contains(adr)) return true;
1810 }
1811
1812 return false;
1813 }
1814
1815
1816 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1817 chunk->set_next(monitor_chunks());
1818 set_monitor_chunks(chunk);
1819 }
1820
1821 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1822 guarantee(monitor_chunks() != NULL, "must be non empty");
1823 if (monitor_chunks() == chunk) {
1824 set_monitor_chunks(chunk->next());
1825 } else {
1826 MonitorChunk* prev = monitor_chunks();
1827 while (prev->next() != chunk) prev = prev->next();
1828 prev->set_next(chunk->next());
1829 }
1830 }
1831
1832 // JVM support.
1833
1834 // Note: this function shouldn't block if it's called in
1835 // _thread_in_native_trans state (such as from
1836 // check_special_condition_for_native_trans()).
1837 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1838
1839 if (has_last_Java_frame() && has_async_condition()) {
1840 // If we are at a polling page safepoint (not a poll return)
1841 // then we must defer async exception because live registers
1842 // will be clobbered by the exception path. Poll return is
1843 // ok because the call we a returning from already collides
1844 // with exception handling registers and so there is no issue.
1845 // (The exception handling path kills call result registers but
1846 // this is ok since the exception kills the result anyway).
1847
1848 if (is_at_poll_safepoint()) {
1849 // if the code we are returning to has deoptimized we must defer
1850 // the exception otherwise live registers get clobbered on the
1851 // exception path before deoptimization is able to retrieve them.
1852 //
1853 RegisterMap map(this, false);
1854 frame caller_fr = last_frame().sender(&map);
1855 assert(caller_fr.is_compiled_frame(), "what?");
1856 if (caller_fr.is_deoptimized_frame()) {
1857 if (TraceExceptions) {
1858 ResourceMark rm;
1859 tty->print_cr("deferred async exception at compiled safepoint");
1860 }
1861 return;
1862 }
1863 }
1864 }
1865
1866 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1867 if (condition == _no_async_condition) {
1868 // Conditions have changed since has_special_runtime_exit_condition()
1869 // was called:
1870 // - if we were here only because of an external suspend request,
1871 // then that was taken care of above (or cancelled) so we are done
1872 // - if we were here because of another async request, then it has
1873 // been cleared between the has_special_runtime_exit_condition()
1874 // and now so again we are done
1875 return;
1876 }
1877
1878 // Check for pending async. exception
1879 if (_pending_async_exception != NULL) {
1880 // Only overwrite an already pending exception, if it is not a threadDeath.
1881 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1882
1883 // We cannot call Exceptions::_throw(...) here because we cannot block
1884 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1885
1886 if (TraceExceptions) {
1887 ResourceMark rm;
1888 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1889 if (has_last_Java_frame() ) {
1890 frame f = last_frame();
1891 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1892 }
1893 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1894 }
1895 _pending_async_exception = NULL;
1896 clear_has_async_exception();
1897 }
1898 }
1899
1900 if (check_unsafe_error &&
1901 condition == _async_unsafe_access_error && !has_pending_exception()) {
1902 condition = _no_async_condition; // done
1903 switch (thread_state()) {
1904 case _thread_in_vm:
1905 {
1906 JavaThread* THREAD = this;
1907 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1908 }
1909 case _thread_in_native:
1910 {
1911 ThreadInVMfromNative tiv(this);
1912 JavaThread* THREAD = this;
1913 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1914 }
1915 case _thread_in_Java:
1916 {
1917 ThreadInVMfromJava tiv(this);
1918 JavaThread* THREAD = this;
1919 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1920 }
1921 default:
1922 ShouldNotReachHere();
1923 }
1924 }
1925
1926 assert(condition == _no_async_condition || has_pending_exception() ||
1927 (!check_unsafe_error && condition == _async_unsafe_access_error),
1928 "must have handled the async condition, if no exception");
1929 }
1930
1931 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1932 //
1933 // Check for pending external suspend. Internal suspend requests do
1934 // not use handle_special_runtime_exit_condition().
1935 // If JNIEnv proxies are allowed, don't self-suspend if the target
1936 // thread is not the current thread. In older versions of jdbx, jdbx
1937 // threads could call into the VM with another thread's JNIEnv so we
1938 // can be here operating on behalf of a suspended thread (4432884).
1939 bool do_self_suspend = is_external_suspend_with_lock();
1940 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1941 //
1942 // Because thread is external suspended the safepoint code will count
1943 // thread as at a safepoint. This can be odd because we can be here
1944 // as _thread_in_Java which would normally transition to _thread_blocked
1945 // at a safepoint. We would like to mark the thread as _thread_blocked
1946 // before calling java_suspend_self like all other callers of it but
1947 // we must then observe proper safepoint protocol. (We can't leave
1948 // _thread_blocked with a safepoint in progress). However we can be
1949 // here as _thread_in_native_trans so we can't use a normal transition
1950 // constructor/destructor pair because they assert on that type of
1951 // transition. We could do something like:
1952 //
1953 // JavaThreadState state = thread_state();
1954 // set_thread_state(_thread_in_vm);
1955 // {
1956 // ThreadBlockInVM tbivm(this);
1957 // java_suspend_self()
1958 // }
1959 // set_thread_state(_thread_in_vm_trans);
1960 // if (safepoint) block;
1961 // set_thread_state(state);
1962 //
1963 // but that is pretty messy. Instead we just go with the way the
1964 // code has worked before and note that this is the only path to
1965 // java_suspend_self that doesn't put the thread in _thread_blocked
1966 // mode.
1967
1968 frame_anchor()->make_walkable(this);
1969 java_suspend_self();
1970
1971 // We might be here for reasons in addition to the self-suspend request
1972 // so check for other async requests.
1973 }
1974
1975 if (check_asyncs) {
1976 check_and_handle_async_exceptions();
1977 }
1978 }
1979
1980 void JavaThread::send_thread_stop(oop java_throwable) {
1981 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1982 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1983 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1984
1985 // Do not throw asynchronous exceptions against the compiler thread
1986 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1987 if (is_Compiler_thread()) return;
1988
1989 // This is a change from JDK 1.1, but JDK 1.2 will also do it:
1990 if (java_throwable->is_a(SystemDictionary::ThreadDeath_klass())) {
1991 java_lang_Thread::set_stillborn(threadObj());
1992 }
1993
1994 {
1995 // Actually throw the Throwable against the target Thread - however
1996 // only if there is no thread death exception installed already.
1997 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1998 // If the topmost frame is a runtime stub, then we are calling into
1999 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2000 // must deoptimize the caller before continuing, as the compiled exception handler table
2001 // may not be valid
2002 if (has_last_Java_frame()) {
2003 frame f = last_frame();
2004 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2005 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2006 RegisterMap reg_map(this, UseBiasedLocking);
2007 frame compiled_frame = f.sender(®_map);
2008 if (compiled_frame.can_be_deoptimized()) {
2009 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2010 }
2011 }
2012 }
2013
2014 // Set async. pending exception in thread.
2015 set_pending_async_exception(java_throwable);
2016
2017 if (TraceExceptions) {
2018 ResourceMark rm;
2019 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2020 }
2021 // for AbortVMOnException flag
2022 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2023 }
2024 }
2025
2026
2027 // Interrupt thread so it will wake up from a potential wait()
2028 Thread::interrupt(this);
2029 }
2030
2031 // External suspension mechanism.
2032 //
2033 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2034 // to any VM_locks and it is at a transition
2035 // Self-suspension will happen on the transition out of the vm.
2036 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2037 //
2038 // Guarantees on return:
2039 // + Target thread will not execute any new bytecode (that's why we need to
2040 // force a safepoint)
2041 // + Target thread will not enter any new monitors
2042 //
2043 void JavaThread::java_suspend() {
2044 { MutexLocker mu(Threads_lock);
2045 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2046 return;
2047 }
2048 }
2049
2050 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2051 if (!is_external_suspend()) {
2052 // a racing resume has cancelled us; bail out now
2053 return;
2054 }
2055
2056 // suspend is done
2057 uint32_t debug_bits = 0;
2058 // Warning: is_ext_suspend_completed() may temporarily drop the
2059 // SR_lock to allow the thread to reach a stable thread state if
2060 // it is currently in a transient thread state.
2061 if (is_ext_suspend_completed(false /* !called_by_wait */,
2062 SuspendRetryDelay, &debug_bits) ) {
2063 return;
2064 }
2065 }
2066
2067 VM_ForceSafepoint vm_suspend;
2068 VMThread::execute(&vm_suspend);
2069 }
2070
2071 // Part II of external suspension.
2072 // A JavaThread self suspends when it detects a pending external suspend
2073 // request. This is usually on transitions. It is also done in places
2074 // where continuing to the next transition would surprise the caller,
2075 // e.g., monitor entry.
2076 //
2077 // Returns the number of times that the thread self-suspended.
2078 //
2079 // Note: DO NOT call java_suspend_self() when you just want to block current
2080 // thread. java_suspend_self() is the second stage of cooperative
2081 // suspension for external suspend requests and should only be used
2082 // to complete an external suspend request.
2083 //
2084 int JavaThread::java_suspend_self() {
2085 int ret = 0;
2086
2087 // we are in the process of exiting so don't suspend
2088 if (is_exiting()) {
2089 clear_external_suspend();
2090 return ret;
2091 }
2092
2093 assert(_anchor.walkable() ||
2094 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2095 "must have walkable stack");
2096
2097 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2098
2099 assert(!this->is_ext_suspended(),
2100 "a thread trying to self-suspend should not already be suspended");
2101
2102 if (this->is_suspend_equivalent()) {
2103 // If we are self-suspending as a result of the lifting of a
2104 // suspend equivalent condition, then the suspend_equivalent
2105 // flag is not cleared until we set the ext_suspended flag so
2106 // that wait_for_ext_suspend_completion() returns consistent
2107 // results.
2108 this->clear_suspend_equivalent();
2109 }
2110
2111 // A racing resume may have cancelled us before we grabbed SR_lock
2112 // above. Or another external suspend request could be waiting for us
2113 // by the time we return from SR_lock()->wait(). The thread
2114 // that requested the suspension may already be trying to walk our
2115 // stack and if we return now, we can change the stack out from under
2116 // it. This would be a "bad thing (TM)" and cause the stack walker
2117 // to crash. We stay self-suspended until there are no more pending
2118 // external suspend requests.
2119 while (is_external_suspend()) {
2120 ret++;
2121 this->set_ext_suspended();
2122
2123 // _ext_suspended flag is cleared by java_resume()
2124 while (is_ext_suspended()) {
2125 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2126 }
2127 }
2128
2129 return ret;
2130 }
2131
2132 #ifdef ASSERT
2133 // verify the JavaThread has not yet been published in the Threads::list, and
2134 // hence doesn't need protection from concurrent access at this stage
2135 void JavaThread::verify_not_published() {
2136 if (!Threads_lock->owned_by_self()) {
2137 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2138 assert( !Threads::includes(this),
2139 "java thread shouldn't have been published yet!");
2140 }
2141 else {
2142 assert( !Threads::includes(this),
2143 "java thread shouldn't have been published yet!");
2144 }
2145 }
2146 #endif
2147
2148 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2149 // progress or when _suspend_flags is non-zero.
2150 // Current thread needs to self-suspend if there is a suspend request and/or
2151 // block if a safepoint is in progress.
2152 // Async exception ISN'T checked.
2153 // Note only the ThreadInVMfromNative transition can call this function
2154 // directly and when thread state is _thread_in_native_trans
2155 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2156 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2157
2158 JavaThread *curJT = JavaThread::current();
2159 bool do_self_suspend = thread->is_external_suspend();
2160
2161 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2162
2163 // If JNIEnv proxies are allowed, don't self-suspend if the target
2164 // thread is not the current thread. In older versions of jdbx, jdbx
2165 // threads could call into the VM with another thread's JNIEnv so we
2166 // can be here operating on behalf of a suspended thread (4432884).
2167 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2168 JavaThreadState state = thread->thread_state();
2169
2170 // We mark this thread_blocked state as a suspend-equivalent so
2171 // that a caller to is_ext_suspend_completed() won't be confused.
2172 // The suspend-equivalent state is cleared by java_suspend_self().
2173 thread->set_suspend_equivalent();
2174
2175 // If the safepoint code sees the _thread_in_native_trans state, it will
2176 // wait until the thread changes to other thread state. There is no
2177 // guarantee on how soon we can obtain the SR_lock and complete the
2178 // self-suspend request. It would be a bad idea to let safepoint wait for
2179 // too long. Temporarily change the state to _thread_blocked to
2180 // let the VM thread know that this thread is ready for GC. The problem
2181 // of changing thread state is that safepoint could happen just after
2182 // java_suspend_self() returns after being resumed, and VM thread will
2183 // see the _thread_blocked state. We must check for safepoint
2184 // after restoring the state and make sure we won't leave while a safepoint
2185 // is in progress.
2186 thread->set_thread_state(_thread_blocked);
2187 thread->java_suspend_self();
2188 thread->set_thread_state(state);
2189 // Make sure new state is seen by VM thread
2190 if (os::is_MP()) {
2191 if (UseMembar) {
2192 // Force a fence between the write above and read below
2193 OrderAccess::fence();
2194 } else {
2195 // Must use this rather than serialization page in particular on Windows
2196 InterfaceSupport::serialize_memory(thread);
2197 }
2198 }
2199 }
2200
2201 if (SafepointSynchronize::do_call_back()) {
2202 // If we are safepointing, then block the caller which may not be
2203 // the same as the target thread (see above).
2204 SafepointSynchronize::block(curJT);
2205 }
2206
2207 if (thread->is_deopt_suspend()) {
2208 thread->clear_deopt_suspend();
2209 RegisterMap map(thread, false);
2210 frame f = thread->last_frame();
2211 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2212 f = f.sender(&map);
2213 }
2214 if (f.id() == thread->must_deopt_id()) {
2215 thread->clear_must_deopt_id();
2216 f.deoptimize(thread);
2217 } else {
2218 fatal("missed deoptimization!");
2219 }
2220 }
2221 }
2222
2223 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2224 // progress or when _suspend_flags is non-zero.
2225 // Current thread needs to self-suspend if there is a suspend request and/or
2226 // block if a safepoint is in progress.
2227 // Also check for pending async exception (not including unsafe access error).
2228 // Note only the native==>VM/Java barriers can call this function and when
2229 // thread state is _thread_in_native_trans.
2230 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2231 check_safepoint_and_suspend_for_native_trans(thread);
2232
2233 if (thread->has_async_exception()) {
2234 // We are in _thread_in_native_trans state, don't handle unsafe
2235 // access error since that may block.
2236 thread->check_and_handle_async_exceptions(false);
2237 }
2238 }
2239
2240 // We need to guarantee the Threads_lock here, since resumes are not
2241 // allowed during safepoint synchronization
2242 // Can only resume from an external suspension
2243 void JavaThread::java_resume() {
2244 assert_locked_or_safepoint(Threads_lock);
2245
2246 // Sanity check: thread is gone, has started exiting or the thread
2247 // was not externally suspended.
2248 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2249 return;
2250 }
2251
2252 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2253
2254 clear_external_suspend();
2255
2256 if (is_ext_suspended()) {
2257 clear_ext_suspended();
2258 SR_lock()->notify_all();
2259 }
2260 }
2261
2262 void JavaThread::create_stack_guard_pages() {
2263 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2264 address low_addr = stack_base() - stack_size();
2265 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2266
2267 int allocate = os::allocate_stack_guard_pages();
2268 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2269
2270 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2271 warning("Attempt to allocate stack guard pages failed.");
2272 return;
2273 }
2274
2275 if (os::guard_memory((char *) low_addr, len)) {
2276 _stack_guard_state = stack_guard_enabled;
2277 } else {
2278 warning("Attempt to protect stack guard pages failed.");
2279 if (os::uncommit_memory((char *) low_addr, len)) {
2280 warning("Attempt to deallocate stack guard pages failed.");
2281 }
2282 }
2283 }
2284
2285 void JavaThread::remove_stack_guard_pages() {
2286 if (_stack_guard_state == stack_guard_unused) return;
2287 address low_addr = stack_base() - stack_size();
2288 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2289
2290 if (os::allocate_stack_guard_pages()) {
2291 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2292 _stack_guard_state = stack_guard_unused;
2293 } else {
2294 warning("Attempt to deallocate stack guard pages failed.");
2295 }
2296 } else {
2297 if (_stack_guard_state == stack_guard_unused) return;
2298 if (os::unguard_memory((char *) low_addr, len)) {
2299 _stack_guard_state = stack_guard_unused;
2300 } else {
2301 warning("Attempt to unprotect stack guard pages failed.");
2302 }
2303 }
2304 }
2305
2306 void JavaThread::enable_stack_yellow_zone() {
2307 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2308 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2309
2310 // The base notation is from the stacks point of view, growing downward.
2311 // We need to adjust it to work correctly with guard_memory()
2312 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2313
2314 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2315 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2316
2317 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2318 _stack_guard_state = stack_guard_enabled;
2319 } else {
2320 warning("Attempt to guard stack yellow zone failed.");
2321 }
2322 enable_register_stack_guard();
2323 }
2324
2325 void JavaThread::disable_stack_yellow_zone() {
2326 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2327 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2328
2329 // Simply return if called for a thread that does not use guard pages.
2330 if (_stack_guard_state == stack_guard_unused) return;
2331
2332 // The base notation is from the stacks point of view, growing downward.
2333 // We need to adjust it to work correctly with guard_memory()
2334 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2335
2336 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2337 _stack_guard_state = stack_guard_yellow_disabled;
2338 } else {
2339 warning("Attempt to unguard stack yellow zone failed.");
2340 }
2341 disable_register_stack_guard();
2342 }
2343
2344 void JavaThread::enable_stack_red_zone() {
2345 // The base notation is from the stacks point of view, growing downward.
2346 // We need to adjust it to work correctly with guard_memory()
2347 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2348 address base = stack_red_zone_base() - stack_red_zone_size();
2349
2350 guarantee(base < stack_base(),"Error calculating stack red zone");
2351 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2352
2353 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2354 warning("Attempt to guard stack red zone failed.");
2355 }
2356 }
2357
2358 void JavaThread::disable_stack_red_zone() {
2359 // The base notation is from the stacks point of view, growing downward.
2360 // We need to adjust it to work correctly with guard_memory()
2361 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2362 address base = stack_red_zone_base() - stack_red_zone_size();
2363 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2364 warning("Attempt to unguard stack red zone failed.");
2365 }
2366 }
2367
2368 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2369 // ignore is there is no stack
2370 if (!has_last_Java_frame()) return;
2371 // traverse the stack frames. Starts from top frame.
2372 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2373 frame* fr = fst.current();
2374 f(fr, fst.register_map());
2375 }
2376 }
2377
2378
2379 #ifndef PRODUCT
2380 // Deoptimization
2381 // Function for testing deoptimization
2382 void JavaThread::deoptimize() {
2383 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2384 StackFrameStream fst(this, UseBiasedLocking);
2385 bool deopt = false; // Dump stack only if a deopt actually happens.
2386 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2387 // Iterate over all frames in the thread and deoptimize
2388 for(; !fst.is_done(); fst.next()) {
2389 if(fst.current()->can_be_deoptimized()) {
2390
2391 if (only_at) {
2392 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2393 // consists of comma or carriage return separated numbers so
2394 // search for the current bci in that string.
2395 address pc = fst.current()->pc();
2396 nmethod* nm = (nmethod*) fst.current()->cb();
2397 ScopeDesc* sd = nm->scope_desc_at( pc);
2398 char buffer[8];
2399 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2400 size_t len = strlen(buffer);
2401 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2402 while (found != NULL) {
2403 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2404 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2405 // Check that the bci found is bracketed by terminators.
2406 break;
2407 }
2408 found = strstr(found + 1, buffer);
2409 }
2410 if (!found) {
2411 continue;
2412 }
2413 }
2414
2415 if (DebugDeoptimization && !deopt) {
2416 deopt = true; // One-time only print before deopt
2417 tty->print_cr("[BEFORE Deoptimization]");
2418 trace_frames();
2419 trace_stack();
2420 }
2421 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2422 }
2423 }
2424
2425 if (DebugDeoptimization && deopt) {
2426 tty->print_cr("[AFTER Deoptimization]");
2427 trace_frames();
2428 }
2429 }
2430
2431
2432 // Make zombies
2433 void JavaThread::make_zombies() {
2434 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2435 if (fst.current()->can_be_deoptimized()) {
2436 // it is a Java nmethod
2437 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2438 nm->make_not_entrant();
2439 }
2440 }
2441 }
2442 #endif // PRODUCT
2443
2444
2445 void JavaThread::deoptimized_wrt_marked_nmethods() {
2446 if (!has_last_Java_frame()) return;
2447 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2448 StackFrameStream fst(this, UseBiasedLocking);
2449 for(; !fst.is_done(); fst.next()) {
2450 if (fst.current()->should_be_deoptimized()) {
2451 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2452 }
2453 }
2454 }
2455
2456
2457 // GC support
2458 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2459
2460 void JavaThread::gc_epilogue() {
2461 frames_do(frame_gc_epilogue);
2462 }
2463
2464
2465 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2466
2467 void JavaThread::gc_prologue() {
2468 frames_do(frame_gc_prologue);
2469 }
2470
2471 // If the caller is a NamedThread, then remember, in the current scope,
2472 // the given JavaThread in its _processed_thread field.
2473 class RememberProcessedThread: public StackObj {
2474 NamedThread* _cur_thr;
2475 public:
2476 RememberProcessedThread(JavaThread* jthr) {
2477 Thread* thread = Thread::current();
2478 if (thread->is_Named_thread()) {
2479 _cur_thr = (NamedThread *)thread;
2480 _cur_thr->set_processed_thread(jthr);
2481 } else {
2482 _cur_thr = NULL;
2483 }
2484 }
2485
2486 ~RememberProcessedThread() {
2487 if (_cur_thr) {
2488 _cur_thr->set_processed_thread(NULL);
2489 }
2490 }
2491 };
2492
2493 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2494 // Verify that the deferred card marks have been flushed.
2495 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2496
2497 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2498 // since there may be more than one thread using each ThreadProfiler.
2499
2500 // Traverse the GCHandles
2501 Thread::oops_do(f, cf);
2502
2503 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2504 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2505
2506 if (has_last_Java_frame()) {
2507 // Record JavaThread to GC thread
2508 RememberProcessedThread rpt(this);
2509
2510 // Traverse the privileged stack
2511 if (_privileged_stack_top != NULL) {
2512 _privileged_stack_top->oops_do(f);
2513 }
2514
2515 // traverse the registered growable array
2516 if (_array_for_gc != NULL) {
2517 for (int index = 0; index < _array_for_gc->length(); index++) {
2518 f->do_oop(_array_for_gc->adr_at(index));
2519 }
2520 }
2521
2522 // Traverse the monitor chunks
2523 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2524 chunk->oops_do(f);
2525 }
2526
2527 // Traverse the execution stack
2528 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2529 fst.current()->oops_do(f, cf, fst.register_map());
2530 }
2531 }
2532
2533 // callee_target is never live across a gc point so NULL it here should
2534 // it still contain a methdOop.
2535
2536 set_callee_target(NULL);
2537
2538 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2539 // If we have deferred set_locals there might be oops waiting to be
2540 // written
2541 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2542 if (list != NULL) {
2543 for (int i = 0; i < list->length(); i++) {
2544 list->at(i)->oops_do(f);
2545 }
2546 }
2547
2548 // Traverse instance variables at the end since the GC may be moving things
2549 // around using this function
2550 f->do_oop((oop*) &_threadObj);
2551 f->do_oop((oop*) &_vm_result);
2552 f->do_oop((oop*) &_vm_result_2);
2553 f->do_oop((oop*) &_exception_oop);
2554 f->do_oop((oop*) &_pending_async_exception);
2555
2556 if (jvmti_thread_state() != NULL) {
2557 jvmti_thread_state()->oops_do(f);
2558 }
2559 }
2560
2561 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2562 Thread::nmethods_do(cf); // (super method is a no-op)
2563
2564 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2565 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2566
2567 if (has_last_Java_frame()) {
2568 // Traverse the execution stack
2569 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2570 fst.current()->nmethods_do(cf);
2571 }
2572 }
2573 }
2574
2575 // Printing
2576 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2577 switch (_thread_state) {
2578 case _thread_uninitialized: return "_thread_uninitialized";
2579 case _thread_new: return "_thread_new";
2580 case _thread_new_trans: return "_thread_new_trans";
2581 case _thread_in_native: return "_thread_in_native";
2582 case _thread_in_native_trans: return "_thread_in_native_trans";
2583 case _thread_in_vm: return "_thread_in_vm";
2584 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2585 case _thread_in_Java: return "_thread_in_Java";
2586 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2587 case _thread_blocked: return "_thread_blocked";
2588 case _thread_blocked_trans: return "_thread_blocked_trans";
2589 default: return "unknown thread state";
2590 }
2591 }
2592
2593 #ifndef PRODUCT
2594 void JavaThread::print_thread_state_on(outputStream *st) const {
2595 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2596 };
2597 void JavaThread::print_thread_state() const {
2598 print_thread_state_on(tty);
2599 };
2600 #endif // PRODUCT
2601
2602 // Called by Threads::print() for VM_PrintThreads operation
2603 void JavaThread::print_on(outputStream *st) const {
2604 st->print("\"%s\" ", get_thread_name());
2605 oop thread_oop = threadObj();
2606 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2607 Thread::print_on(st);
2608 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2609 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2610 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2611 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2612 }
2613 #ifndef PRODUCT
2614 print_thread_state_on(st);
2615 _safepoint_state->print_on(st);
2616 #endif // PRODUCT
2617 }
2618
2619 // Called by fatal error handler. The difference between this and
2620 // JavaThread::print() is that we can't grab lock or allocate memory.
2621 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2622 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2623 oop thread_obj = threadObj();
2624 if (thread_obj != NULL) {
2625 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2626 }
2627 st->print(" [");
2628 st->print("%s", _get_thread_state_name(_thread_state));
2629 if (osthread()) {
2630 st->print(", id=%d", osthread()->thread_id());
2631 }
2632 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2633 _stack_base - _stack_size, _stack_base);
2634 st->print("]");
2635 return;
2636 }
2637
2638 // Verification
2639
2640 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2641
2642 void JavaThread::verify() {
2643 // Verify oops in the thread.
2644 oops_do(&VerifyOopClosure::verify_oop, NULL);
2645
2646 // Verify the stack frames.
2647 frames_do(frame_verify);
2648 }
2649
2650 // CR 6300358 (sub-CR 2137150)
2651 // Most callers of this method assume that it can't return NULL but a
2652 // thread may not have a name whilst it is in the process of attaching to
2653 // the VM - see CR 6412693, and there are places where a JavaThread can be
2654 // seen prior to having it's threadObj set (eg JNI attaching threads and
2655 // if vm exit occurs during initialization). These cases can all be accounted
2656 // for such that this method never returns NULL.
2657 const char* JavaThread::get_thread_name() const {
2658 #ifdef ASSERT
2659 // early safepoints can hit while current thread does not yet have TLS
2660 if (!SafepointSynchronize::is_at_safepoint()) {
2661 Thread *cur = Thread::current();
2662 if (!(cur->is_Java_thread() && cur == this)) {
2663 // Current JavaThreads are allowed to get their own name without
2664 // the Threads_lock.
2665 assert_locked_or_safepoint(Threads_lock);
2666 }
2667 }
2668 #endif // ASSERT
2669 return get_thread_name_string();
2670 }
2671
2672 // Returns a non-NULL representation of this thread's name, or a suitable
2673 // descriptive string if there is no set name
2674 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2675 const char* name_str;
2676 oop thread_obj = threadObj();
2677 if (thread_obj != NULL) {
2678 typeArrayOop name = java_lang_Thread::name(thread_obj);
2679 if (name != NULL) {
2680 if (buf == NULL) {
2681 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2682 }
2683 else {
2684 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2685 }
2686 }
2687 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2688 name_str = "<no-name - thread is attaching>";
2689 }
2690 else {
2691 name_str = Thread::name();
2692 }
2693 }
2694 else {
2695 name_str = Thread::name();
2696 }
2697 assert(name_str != NULL, "unexpected NULL thread name");
2698 return name_str;
2699 }
2700
2701
2702 const char* JavaThread::get_threadgroup_name() const {
2703 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2704 oop thread_obj = threadObj();
2705 if (thread_obj != NULL) {
2706 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2707 if (thread_group != NULL) {
2708 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2709 // ThreadGroup.name can be null
2710 if (name != NULL) {
2711 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2712 return str;
2713 }
2714 }
2715 }
2716 return NULL;
2717 }
2718
2719 const char* JavaThread::get_parent_name() const {
2720 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2721 oop thread_obj = threadObj();
2722 if (thread_obj != NULL) {
2723 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2724 if (thread_group != NULL) {
2725 oop parent = java_lang_ThreadGroup::parent(thread_group);
2726 if (parent != NULL) {
2727 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2728 // ThreadGroup.name can be null
2729 if (name != NULL) {
2730 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2731 return str;
2732 }
2733 }
2734 }
2735 }
2736 return NULL;
2737 }
2738
2739 ThreadPriority JavaThread::java_priority() const {
2740 oop thr_oop = threadObj();
2741 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2742 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2743 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2744 return priority;
2745 }
2746
2747 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2748
2749 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2750 // Link Java Thread object <-> C++ Thread
2751
2752 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2753 // and put it into a new Handle. The Handle "thread_oop" can then
2754 // be used to pass the C++ thread object to other methods.
2755
2756 // Set the Java level thread object (jthread) field of the
2757 // new thread (a JavaThread *) to C++ thread object using the
2758 // "thread_oop" handle.
2759
2760 // Set the thread field (a JavaThread *) of the
2761 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2762
2763 Handle thread_oop(Thread::current(),
2764 JNIHandles::resolve_non_null(jni_thread));
2765 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2766 "must be initialized");
2767 set_threadObj(thread_oop());
2768 java_lang_Thread::set_thread(thread_oop(), this);
2769
2770 if (prio == NoPriority) {
2771 prio = java_lang_Thread::priority(thread_oop());
2772 assert(prio != NoPriority, "A valid priority should be present");
2773 }
2774
2775 // Push the Java priority down to the native thread; needs Threads_lock
2776 Thread::set_priority(this, prio);
2777
2778 // Add the new thread to the Threads list and set it in motion.
2779 // We must have threads lock in order to call Threads::add.
2780 // It is crucial that we do not block before the thread is
2781 // added to the Threads list for if a GC happens, then the java_thread oop
2782 // will not be visited by GC.
2783 Threads::add(this);
2784 }
2785
2786 oop JavaThread::current_park_blocker() {
2787 // Support for JSR-166 locks
2788 oop thread_oop = threadObj();
2789 if (thread_oop != NULL &&
2790 JDK_Version::current().supports_thread_park_blocker()) {
2791 return java_lang_Thread::park_blocker(thread_oop);
2792 }
2793 return NULL;
2794 }
2795
2796
2797 void JavaThread::print_stack_on(outputStream* st) {
2798 if (!has_last_Java_frame()) return;
2799 ResourceMark rm;
2800 HandleMark hm;
2801
2802 RegisterMap reg_map(this);
2803 vframe* start_vf = last_java_vframe(®_map);
2804 int count = 0;
2805 for (vframe* f = start_vf; f; f = f->sender() ) {
2806 if (f->is_java_frame()) {
2807 javaVFrame* jvf = javaVFrame::cast(f);
2808 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2809
2810 // Print out lock information
2811 if (JavaMonitorsInStackTrace) {
2812 jvf->print_lock_info_on(st, count);
2813 }
2814 } else {
2815 // Ignore non-Java frames
2816 }
2817
2818 // Bail-out case for too deep stacks
2819 count++;
2820 if (MaxJavaStackTraceDepth == count) return;
2821 }
2822 }
2823
2824
2825 // JVMTI PopFrame support
2826 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2827 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2828 if (in_bytes(size_in_bytes) != 0) {
2829 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2830 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2831 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2832 }
2833 }
2834
2835 void* JavaThread::popframe_preserved_args() {
2836 return _popframe_preserved_args;
2837 }
2838
2839 ByteSize JavaThread::popframe_preserved_args_size() {
2840 return in_ByteSize(_popframe_preserved_args_size);
2841 }
2842
2843 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2844 int sz = in_bytes(popframe_preserved_args_size());
2845 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2846 return in_WordSize(sz / wordSize);
2847 }
2848
2849 void JavaThread::popframe_free_preserved_args() {
2850 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2851 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2852 _popframe_preserved_args = NULL;
2853 _popframe_preserved_args_size = 0;
2854 }
2855
2856 #ifndef PRODUCT
2857
2858 void JavaThread::trace_frames() {
2859 tty->print_cr("[Describe stack]");
2860 int frame_no = 1;
2861 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2862 tty->print(" %d. ", frame_no++);
2863 fst.current()->print_value_on(tty,this);
2864 tty->cr();
2865 }
2866 }
2867
2868
2869 void JavaThread::trace_stack_from(vframe* start_vf) {
2870 ResourceMark rm;
2871 int vframe_no = 1;
2872 for (vframe* f = start_vf; f; f = f->sender() ) {
2873 if (f->is_java_frame()) {
2874 javaVFrame::cast(f)->print_activation(vframe_no++);
2875 } else {
2876 f->print();
2877 }
2878 if (vframe_no > StackPrintLimit) {
2879 tty->print_cr("...<more frames>...");
2880 return;
2881 }
2882 }
2883 }
2884
2885
2886 void JavaThread::trace_stack() {
2887 if (!has_last_Java_frame()) return;
2888 ResourceMark rm;
2889 HandleMark hm;
2890 RegisterMap reg_map(this);
2891 trace_stack_from(last_java_vframe(®_map));
2892 }
2893
2894
2895 #endif // PRODUCT
2896
2897
2898 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2899 assert(reg_map != NULL, "a map must be given");
2900 frame f = last_frame();
2901 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2902 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2903 }
2904 return NULL;
2905 }
2906
2907
2908 klassOop JavaThread::security_get_caller_class(int depth) {
2909 vframeStream vfst(this);
2910 vfst.security_get_caller_frame(depth);
2911 if (!vfst.at_end()) {
2912 return vfst.method()->method_holder();
2913 }
2914 return NULL;
2915 }
2916
2917 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2918 assert(thread->is_Compiler_thread(), "must be compiler thread");
2919 CompileBroker::compiler_thread_loop();
2920 }
2921
2922 // Create a CompilerThread
2923 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2924 : JavaThread(&compiler_thread_entry) {
2925 _env = NULL;
2926 _log = NULL;
2927 _task = NULL;
2928 _queue = queue;
2929 _counters = counters;
2930 _buffer_blob = NULL;
2931
2932 #ifndef PRODUCT
2933 _ideal_graph_printer = NULL;
2934 #endif
2935 }
2936
2937
2938 // ======= Threads ========
2939
2940 // The Threads class links together all active threads, and provides
2941 // operations over all threads. It is protected by its own Mutex
2942 // lock, which is also used in other contexts to protect thread
2943 // operations from having the thread being operated on from exiting
2944 // and going away unexpectedly (e.g., safepoint synchronization)
2945
2946 JavaThread* Threads::_thread_list = NULL;
2947 int Threads::_number_of_threads = 0;
2948 int Threads::_number_of_non_daemon_threads = 0;
2949 int Threads::_return_code = 0;
2950 size_t JavaThread::_stack_size_at_create = 0;
2951
2952 // All JavaThreads
2953 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2954
2955 void os_stream();
2956
2957 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2958 void Threads::threads_do(ThreadClosure* tc) {
2959 assert_locked_or_safepoint(Threads_lock);
2960 // ALL_JAVA_THREADS iterates through all JavaThreads
2961 ALL_JAVA_THREADS(p) {
2962 tc->do_thread(p);
2963 }
2964 // Someday we could have a table or list of all non-JavaThreads.
2965 // For now, just manually iterate through them.
2966 tc->do_thread(VMThread::vm_thread());
2967 Universe::heap()->gc_threads_do(tc);
2968 WatcherThread *wt = WatcherThread::watcher_thread();
2969 // Strictly speaking, the following NULL check isn't sufficient to make sure
2970 // the data for WatcherThread is still valid upon being examined. However,
2971 // considering that WatchThread terminates when the VM is on the way to
2972 // exit at safepoint, the chance of the above is extremely small. The right
2973 // way to prevent termination of WatcherThread would be to acquire
2974 // Terminator_lock, but we can't do that without violating the lock rank
2975 // checking in some cases.
2976 if (wt != NULL)
2977 tc->do_thread(wt);
2978
2979 // If CompilerThreads ever become non-JavaThreads, add them here
2980 }
2981
2982 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2983
2984 extern void JDK_Version_init();
2985
2986 // Check version
2987 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2988
2989 // Initialize the output stream module
2990 ostream_init();
2991
2992 // Process java launcher properties.
2993 Arguments::process_sun_java_launcher_properties(args);
2994
2995 // Initialize the os module before using TLS
2996 os::init();
2997
2998 // Initialize system properties.
2999 Arguments::init_system_properties();
3000
3001 // So that JDK version can be used as a discrimintor when parsing arguments
3002 JDK_Version_init();
3003
3004 // Update/Initialize System properties after JDK version number is known
3005 Arguments::init_version_specific_system_properties();
3006
3007 // Parse arguments
3008 jint parse_result = Arguments::parse(args);
3009 if (parse_result != JNI_OK) return parse_result;
3010
3011 if (PauseAtStartup) {
3012 os::pause();
3013 }
3014
3015 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3016
3017 // Record VM creation timing statistics
3018 TraceVmCreationTime create_vm_timer;
3019 create_vm_timer.start();
3020
3021 // Timing (must come after argument parsing)
3022 TraceTime timer("Create VM", TraceStartupTime);
3023
3024 // Initialize the os module after parsing the args
3025 jint os_init_2_result = os::init_2();
3026 if (os_init_2_result != JNI_OK) return os_init_2_result;
3027
3028 // Initialize output stream logging
3029 ostream_init_log();
3030
3031 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3032 // Must be before create_vm_init_agents()
3033 if (Arguments::init_libraries_at_startup()) {
3034 convert_vm_init_libraries_to_agents();
3035 }
3036
3037 // Launch -agentlib/-agentpath and converted -Xrun agents
3038 if (Arguments::init_agents_at_startup()) {
3039 create_vm_init_agents();
3040 }
3041
3042 // Initialize Threads state
3043 _thread_list = NULL;
3044 _number_of_threads = 0;
3045 _number_of_non_daemon_threads = 0;
3046
3047 // Initialize TLS
3048 ThreadLocalStorage::init();
3049
3050 // Initialize global data structures and create system classes in heap
3051 vm_init_globals();
3052
3053 // Attach the main thread to this os thread
3054 JavaThread* main_thread = new JavaThread();
3055 main_thread->set_thread_state(_thread_in_vm);
3056 // must do this before set_active_handles and initialize_thread_local_storage
3057 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3058 // change the stack size recorded here to one based on the java thread
3059 // stacksize. This adjusted size is what is used to figure the placement
3060 // of the guard pages.
3061 main_thread->record_stack_base_and_size();
3062 main_thread->initialize_thread_local_storage();
3063
3064 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3065
3066 if (!main_thread->set_as_starting_thread()) {
3067 vm_shutdown_during_initialization(
3068 "Failed necessary internal allocation. Out of swap space");
3069 delete main_thread;
3070 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3071 return JNI_ENOMEM;
3072 }
3073
3074 // Enable guard page *after* os::create_main_thread(), otherwise it would
3075 // crash Linux VM, see notes in os_linux.cpp.
3076 main_thread->create_stack_guard_pages();
3077
3078 // Initialize Java-Level synchronization subsystem
3079 ObjectMonitor::Initialize() ;
3080
3081 // Initialize global modules
3082 jint status = init_globals();
3083 if (status != JNI_OK) {
3084 delete main_thread;
3085 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3086 return status;
3087 }
3088
3089 // Should be done after the heap is fully created
3090 main_thread->cache_global_variables();
3091
3092 HandleMark hm;
3093
3094 { MutexLocker mu(Threads_lock);
3095 Threads::add(main_thread);
3096 }
3097
3098 // Any JVMTI raw monitors entered in onload will transition into
3099 // real raw monitor. VM is setup enough here for raw monitor enter.
3100 JvmtiExport::transition_pending_onload_raw_monitors();
3101
3102 if (VerifyBeforeGC &&
3103 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3104 Universe::heap()->prepare_for_verify();
3105 Universe::verify(); // make sure we're starting with a clean slate
3106 }
3107
3108 // Create the VMThread
3109 { TraceTime timer("Start VMThread", TraceStartupTime);
3110 VMThread::create();
3111 Thread* vmthread = VMThread::vm_thread();
3112
3113 if (!os::create_thread(vmthread, os::vm_thread))
3114 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3115
3116 // Wait for the VM thread to become ready, and VMThread::run to initialize
3117 // Monitors can have spurious returns, must always check another state flag
3118 {
3119 MutexLocker ml(Notify_lock);
3120 os::start_thread(vmthread);
3121 while (vmthread->active_handles() == NULL) {
3122 Notify_lock->wait();
3123 }
3124 }
3125 }
3126
3127 assert (Universe::is_fully_initialized(), "not initialized");
3128 EXCEPTION_MARK;
3129
3130 // At this point, the Universe is initialized, but we have not executed
3131 // any byte code. Now is a good time (the only time) to dump out the
3132 // internal state of the JVM for sharing.
3133
3134 if (DumpSharedSpaces) {
3135 Universe::heap()->preload_and_dump(CHECK_0);
3136 ShouldNotReachHere();
3137 }
3138
3139 // Always call even when there are not JVMTI environments yet, since environments
3140 // may be attached late and JVMTI must track phases of VM execution
3141 JvmtiExport::enter_start_phase();
3142
3143 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3144 JvmtiExport::post_vm_start();
3145
3146 {
3147 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3148
3149 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3150 create_vm_init_libraries();
3151 }
3152
3153 if (InitializeJavaLangString) {
3154 initialize_class(vmSymbolHandles::java_lang_String(), CHECK_0);
3155 } else {
3156 warning("java.lang.String not initialized");
3157 }
3158
3159 if (AggressiveOpts) {
3160 {
3161 // Forcibly initialize java/util/HashMap and mutate the private
3162 // static final "frontCacheEnabled" field before we start creating instances
3163 #ifdef ASSERT
3164 klassOop tmp_k = SystemDictionary::find(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3165 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3166 #endif
3167 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3168 KlassHandle k = KlassHandle(THREAD, k_o);
3169 guarantee(k.not_null(), "Must find java/util/HashMap");
3170 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3171 ik->initialize(CHECK_0);
3172 fieldDescriptor fd;
3173 // Possible we might not find this field; if so, don't break
3174 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3175 k()->bool_field_put(fd.offset(), true);
3176 }
3177 }
3178
3179 if (UseStringCache) {
3180 // Forcibly initialize java/lang/StringValue and mutate the private
3181 // static final "stringCacheEnabled" field before we start creating instances
3182 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3183 // Possible that StringValue isn't present: if so, silently don't break
3184 if (k_o != NULL) {
3185 KlassHandle k = KlassHandle(THREAD, k_o);
3186 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3187 ik->initialize(CHECK_0);
3188 fieldDescriptor fd;
3189 // Possible we might not find this field: if so, silently don't break
3190 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3191 k()->bool_field_put(fd.offset(), true);
3192 }
3193 }
3194 }
3195 }
3196
3197 // Initialize java_lang.System (needed before creating the thread)
3198 if (InitializeJavaLangSystem) {
3199 initialize_class(vmSymbolHandles::java_lang_System(), CHECK_0);
3200 initialize_class(vmSymbolHandles::java_lang_ThreadGroup(), CHECK_0);
3201 Handle thread_group = create_initial_thread_group(CHECK_0);
3202 Universe::set_main_thread_group(thread_group());
3203 initialize_class(vmSymbolHandles::java_lang_Thread(), CHECK_0);
3204 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3205 main_thread->set_threadObj(thread_object);
3206 // Set thread status to running since main thread has
3207 // been started and running.
3208 java_lang_Thread::set_thread_status(thread_object,
3209 java_lang_Thread::RUNNABLE);
3210
3211 // The VM preresolve methods to these classes. Make sure that get initialized
3212 initialize_class(vmSymbolHandles::java_lang_reflect_Method(), CHECK_0);
3213 initialize_class(vmSymbolHandles::java_lang_ref_Finalizer(), CHECK_0);
3214 // The VM creates & returns objects of this class. Make sure it's initialized.
3215 initialize_class(vmSymbolHandles::java_lang_Class(), CHECK_0);
3216 call_initializeSystemClass(CHECK_0);
3217 } else {
3218 warning("java.lang.System not initialized");
3219 }
3220
3221 // an instance of OutOfMemory exception has been allocated earlier
3222 if (InitializeJavaLangExceptionsErrors) {
3223 initialize_class(vmSymbolHandles::java_lang_OutOfMemoryError(), CHECK_0);
3224 initialize_class(vmSymbolHandles::java_lang_NullPointerException(), CHECK_0);
3225 initialize_class(vmSymbolHandles::java_lang_ClassCastException(), CHECK_0);
3226 initialize_class(vmSymbolHandles::java_lang_ArrayStoreException(), CHECK_0);
3227 initialize_class(vmSymbolHandles::java_lang_ArithmeticException(), CHECK_0);
3228 initialize_class(vmSymbolHandles::java_lang_StackOverflowError(), CHECK_0);
3229 initialize_class(vmSymbolHandles::java_lang_IllegalMonitorStateException(), CHECK_0);
3230 } else {
3231 warning("java.lang.OutOfMemoryError has not been initialized");
3232 warning("java.lang.NullPointerException has not been initialized");
3233 warning("java.lang.ClassCastException has not been initialized");
3234 warning("java.lang.ArrayStoreException has not been initialized");
3235 warning("java.lang.ArithmeticException has not been initialized");
3236 warning("java.lang.StackOverflowError has not been initialized");
3237 }
3238 }
3239
3240 // See : bugid 4211085.
3241 // Background : the static initializer of java.lang.Compiler tries to read
3242 // property"java.compiler" and read & write property "java.vm.info".
3243 // When a security manager is installed through the command line
3244 // option "-Djava.security.manager", the above properties are not
3245 // readable and the static initializer for java.lang.Compiler fails
3246 // resulting in a NoClassDefFoundError. This can happen in any
3247 // user code which calls methods in java.lang.Compiler.
3248 // Hack : the hack is to pre-load and initialize this class, so that only
3249 // system domains are on the stack when the properties are read.
3250 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3251 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3252 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3253 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3254 // Once that is done, we should remove this hack.
3255 initialize_class(vmSymbolHandles::java_lang_Compiler(), CHECK_0);
3256
3257 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3258 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3259 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3260 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3261 // This should also be taken out as soon as 4211383 gets fixed.
3262 reset_vm_info_property(CHECK_0);
3263
3264 quicken_jni_functions();
3265
3266 // Set flag that basic initialization has completed. Used by exceptions and various
3267 // debug stuff, that does not work until all basic classes have been initialized.
3268 set_init_completed();
3269
3270 HS_DTRACE_PROBE(hotspot, vm__init__end);
3271
3272 // record VM initialization completion time
3273 Management::record_vm_init_completed();
3274
3275 // Compute system loader. Note that this has to occur after set_init_completed, since
3276 // valid exceptions may be thrown in the process.
3277 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3278 // set_init_completed has just been called, causing exceptions not to be shortcut
3279 // anymore. We call vm_exit_during_initialization directly instead.
3280 SystemDictionary::compute_java_system_loader(THREAD);
3281 if (HAS_PENDING_EXCEPTION) {
3282 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3283 }
3284
3285 #ifdef KERNEL
3286 if (JDK_Version::is_gte_jdk17x_version()) {
3287 set_jkernel_boot_classloader_hook(THREAD);
3288 }
3289 #endif // KERNEL
3290
3291 #ifndef SERIALGC
3292 // Support for ConcurrentMarkSweep. This should be cleaned up
3293 // and better encapsulated. The ugly nested if test would go away
3294 // once things are properly refactored. XXX YSR
3295 if (UseConcMarkSweepGC || UseG1GC) {
3296 if (UseConcMarkSweepGC) {
3297 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3298 } else {
3299 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3300 }
3301 if (HAS_PENDING_EXCEPTION) {
3302 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3303 }
3304 }
3305 #endif // SERIALGC
3306
3307 // Always call even when there are not JVMTI environments yet, since environments
3308 // may be attached late and JVMTI must track phases of VM execution
3309 JvmtiExport::enter_live_phase();
3310
3311 // Signal Dispatcher needs to be started before VMInit event is posted
3312 os::signal_init();
3313
3314 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3315 if (!DisableAttachMechanism) {
3316 if (StartAttachListener || AttachListener::init_at_startup()) {
3317 AttachListener::init();
3318 }
3319 }
3320
3321 // Launch -Xrun agents
3322 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3323 // back-end can launch with -Xdebug -Xrunjdwp.
3324 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3325 create_vm_init_libraries();
3326 }
3327
3328 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3329 JvmtiExport::post_vm_initialized();
3330
3331 Chunk::start_chunk_pool_cleaner_task();
3332
3333 // initialize compiler(s)
3334 CompileBroker::compilation_init();
3335
3336 Management::initialize(THREAD);
3337 if (HAS_PENDING_EXCEPTION) {
3338 // management agent fails to start possibly due to
3339 // configuration problem and is responsible for printing
3340 // stack trace if appropriate. Simply exit VM.
3341 vm_exit(1);
3342 }
3343
3344 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3345 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3346 if (MemProfiling) MemProfiler::engage();
3347 StatSampler::engage();
3348 if (CheckJNICalls) JniPeriodicChecker::engage();
3349
3350 BiasedLocking::init();
3351
3352
3353 // Start up the WatcherThread if there are any periodic tasks
3354 // NOTE: All PeriodicTasks should be registered by now. If they
3355 // aren't, late joiners might appear to start slowly (we might
3356 // take a while to process their first tick).
3357 if (PeriodicTask::num_tasks() > 0) {
3358 WatcherThread::start();
3359 }
3360
3361 // Give os specific code one last chance to start
3362 os::init_3();
3363
3364 create_vm_timer.end();
3365 return JNI_OK;
3366 }
3367
3368 // type for the Agent_OnLoad and JVM_OnLoad entry points
3369 extern "C" {
3370 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3371 }
3372 // Find a command line agent library and return its entry point for
3373 // -agentlib: -agentpath: -Xrun
3374 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3375 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3376 OnLoadEntry_t on_load_entry = NULL;
3377 void *library = agent->os_lib(); // check if we have looked it up before
3378
3379 if (library == NULL) {
3380 char buffer[JVM_MAXPATHLEN];
3381 char ebuf[1024];
3382 const char *name = agent->name();
3383 const char *msg = "Could not find agent library ";
3384
3385 if (agent->is_absolute_path()) {
3386 library = os::dll_load(name, ebuf, sizeof ebuf);
3387 if (library == NULL) {
3388 const char *sub_msg = " in absolute path, with error: ";
3389 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3390 char *buf = NEW_C_HEAP_ARRAY(char, len);
3391 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3392 // If we can't find the agent, exit.
3393 vm_exit_during_initialization(buf, NULL);
3394 FREE_C_HEAP_ARRAY(char, buf);
3395 }
3396 } else {
3397 // Try to load the agent from the standard dll directory
3398 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3399 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3400 #ifdef KERNEL
3401 // Download instrument dll
3402 if (library == NULL && strcmp(name, "instrument") == 0) {
3403 char *props = Arguments::get_kernel_properties();
3404 char *home = Arguments::get_java_home();
3405 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3406 " sun.jkernel.DownloadManager -download client_jvm";
3407 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3408 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3409 jio_snprintf(cmd, length, fmt, home, props);
3410 int status = os::fork_and_exec(cmd);
3411 FreeHeap(props);
3412 if (status == -1) {
3413 warning(cmd);
3414 vm_exit_during_initialization("fork_and_exec failed: %s",
3415 strerror(errno));
3416 }
3417 FREE_C_HEAP_ARRAY(char, cmd);
3418 // when this comes back the instrument.dll should be where it belongs.
3419 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3420 }
3421 #endif // KERNEL
3422 if (library == NULL) { // Try the local directory
3423 char ns[1] = {0};
3424 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3425 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3426 if (library == NULL) {
3427 const char *sub_msg = " on the library path, with error: ";
3428 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3429 char *buf = NEW_C_HEAP_ARRAY(char, len);
3430 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3431 // If we can't find the agent, exit.
3432 vm_exit_during_initialization(buf, NULL);
3433 FREE_C_HEAP_ARRAY(char, buf);
3434 }
3435 }
3436 }
3437 agent->set_os_lib(library);
3438 }
3439
3440 // Find the OnLoad function.
3441 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3442 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3443 if (on_load_entry != NULL) break;
3444 }
3445 return on_load_entry;
3446 }
3447
3448 // Find the JVM_OnLoad entry point
3449 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3450 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3451 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3452 }
3453
3454 // Find the Agent_OnLoad entry point
3455 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3456 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3457 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3458 }
3459
3460 // For backwards compatibility with -Xrun
3461 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3462 // treated like -agentpath:
3463 // Must be called before agent libraries are created
3464 void Threads::convert_vm_init_libraries_to_agents() {
3465 AgentLibrary* agent;
3466 AgentLibrary* next;
3467
3468 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3469 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3470 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3471
3472 // If there is an JVM_OnLoad function it will get called later,
3473 // otherwise see if there is an Agent_OnLoad
3474 if (on_load_entry == NULL) {
3475 on_load_entry = lookup_agent_on_load(agent);
3476 if (on_load_entry != NULL) {
3477 // switch it to the agent list -- so that Agent_OnLoad will be called,
3478 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3479 Arguments::convert_library_to_agent(agent);
3480 } else {
3481 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3482 }
3483 }
3484 }
3485 }
3486
3487 // Create agents for -agentlib: -agentpath: and converted -Xrun
3488 // Invokes Agent_OnLoad
3489 // Called very early -- before JavaThreads exist
3490 void Threads::create_vm_init_agents() {
3491 extern struct JavaVM_ main_vm;
3492 AgentLibrary* agent;
3493
3494 JvmtiExport::enter_onload_phase();
3495 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3496 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3497
3498 if (on_load_entry != NULL) {
3499 // Invoke the Agent_OnLoad function
3500 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3501 if (err != JNI_OK) {
3502 vm_exit_during_initialization("agent library failed to init", agent->name());
3503 }
3504 } else {
3505 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3506 }
3507 }
3508 JvmtiExport::enter_primordial_phase();
3509 }
3510
3511 extern "C" {
3512 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3513 }
3514
3515 void Threads::shutdown_vm_agents() {
3516 // Send any Agent_OnUnload notifications
3517 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3518 extern struct JavaVM_ main_vm;
3519 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3520
3521 // Find the Agent_OnUnload function.
3522 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3523 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3524 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3525
3526 // Invoke the Agent_OnUnload function
3527 if (unload_entry != NULL) {
3528 JavaThread* thread = JavaThread::current();
3529 ThreadToNativeFromVM ttn(thread);
3530 HandleMark hm(thread);
3531 (*unload_entry)(&main_vm);
3532 break;
3533 }
3534 }
3535 }
3536 }
3537
3538 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3539 // Invokes JVM_OnLoad
3540 void Threads::create_vm_init_libraries() {
3541 extern struct JavaVM_ main_vm;
3542 AgentLibrary* agent;
3543
3544 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3545 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3546
3547 if (on_load_entry != NULL) {
3548 // Invoke the JVM_OnLoad function
3549 JavaThread* thread = JavaThread::current();
3550 ThreadToNativeFromVM ttn(thread);
3551 HandleMark hm(thread);
3552 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3553 if (err != JNI_OK) {
3554 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3555 }
3556 } else {
3557 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3558 }
3559 }
3560 }
3561
3562 // Last thread running calls java.lang.Shutdown.shutdown()
3563 void JavaThread::invoke_shutdown_hooks() {
3564 HandleMark hm(this);
3565
3566 // We could get here with a pending exception, if so clear it now.
3567 if (this->has_pending_exception()) {
3568 this->clear_pending_exception();
3569 }
3570
3571 EXCEPTION_MARK;
3572 klassOop k =
3573 SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_Shutdown(),
3574 THREAD);
3575 if (k != NULL) {
3576 // SystemDictionary::resolve_or_null will return null if there was
3577 // an exception. If we cannot load the Shutdown class, just don't
3578 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3579 // and finalizers (if runFinalizersOnExit is set) won't be run.
3580 // Note that if a shutdown hook was registered or runFinalizersOnExit
3581 // was called, the Shutdown class would have already been loaded
3582 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3583 instanceKlassHandle shutdown_klass (THREAD, k);
3584 JavaValue result(T_VOID);
3585 JavaCalls::call_static(&result,
3586 shutdown_klass,
3587 vmSymbolHandles::shutdown_method_name(),
3588 vmSymbolHandles::void_method_signature(),
3589 THREAD);
3590 }
3591 CLEAR_PENDING_EXCEPTION;
3592 }
3593
3594 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3595 // the program falls off the end of main(). Another VM exit path is through
3596 // vm_exit() when the program calls System.exit() to return a value or when
3597 // there is a serious error in VM. The two shutdown paths are not exactly
3598 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3599 // and VM_Exit op at VM level.
3600 //
3601 // Shutdown sequence:
3602 // + Wait until we are the last non-daemon thread to execute
3603 // <-- every thing is still working at this moment -->
3604 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3605 // shutdown hooks, run finalizers if finalization-on-exit
3606 // + Call before_exit(), prepare for VM exit
3607 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3608 // currently the only user of this mechanism is File.deleteOnExit())
3609 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3610 // post thread end and vm death events to JVMTI,
3611 // stop signal thread
3612 // + Call JavaThread::exit(), it will:
3613 // > release JNI handle blocks, remove stack guard pages
3614 // > remove this thread from Threads list
3615 // <-- no more Java code from this thread after this point -->
3616 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3617 // the compiler threads at safepoint
3618 // <-- do not use anything that could get blocked by Safepoint -->
3619 // + Disable tracing at JNI/JVM barriers
3620 // + Set _vm_exited flag for threads that are still running native code
3621 // + Delete this thread
3622 // + Call exit_globals()
3623 // > deletes tty
3624 // > deletes PerfMemory resources
3625 // + Return to caller
3626
3627 bool Threads::destroy_vm() {
3628 JavaThread* thread = JavaThread::current();
3629
3630 // Wait until we are the last non-daemon thread to execute
3631 { MutexLocker nu(Threads_lock);
3632 while (Threads::number_of_non_daemon_threads() > 1 )
3633 // This wait should make safepoint checks, wait without a timeout,
3634 // and wait as a suspend-equivalent condition.
3635 //
3636 // Note: If the FlatProfiler is running and this thread is waiting
3637 // for another non-daemon thread to finish, then the FlatProfiler
3638 // is waiting for the external suspend request on this thread to
3639 // complete. wait_for_ext_suspend_completion() will eventually
3640 // timeout, but that takes time. Making this wait a suspend-
3641 // equivalent condition solves that timeout problem.
3642 //
3643 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3644 Mutex::_as_suspend_equivalent_flag);
3645 }
3646
3647 // Hang forever on exit if we are reporting an error.
3648 if (ShowMessageBoxOnError && is_error_reported()) {
3649 os::infinite_sleep();
3650 }
3651
3652 if (JDK_Version::is_jdk12x_version()) {
3653 // We are the last thread running, so check if finalizers should be run.
3654 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3655 HandleMark rm(thread);
3656 Universe::run_finalizers_on_exit();
3657 } else {
3658 // run Java level shutdown hooks
3659 thread->invoke_shutdown_hooks();
3660 }
3661
3662 before_exit(thread);
3663
3664 thread->exit(true);
3665
3666 // Stop VM thread.
3667 {
3668 // 4945125 The vm thread comes to a safepoint during exit.
3669 // GC vm_operations can get caught at the safepoint, and the
3670 // heap is unparseable if they are caught. Grab the Heap_lock
3671 // to prevent this. The GC vm_operations will not be able to
3672 // queue until after the vm thread is dead.
3673 MutexLocker ml(Heap_lock);
3674
3675 VMThread::wait_for_vm_thread_exit();
3676 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3677 VMThread::destroy();
3678 }
3679
3680 // clean up ideal graph printers
3681 #if defined(COMPILER2) && !defined(PRODUCT)
3682 IdealGraphPrinter::clean_up();
3683 #endif
3684
3685 // Now, all Java threads are gone except daemon threads. Daemon threads
3686 // running Java code or in VM are stopped by the Safepoint. However,
3687 // daemon threads executing native code are still running. But they
3688 // will be stopped at native=>Java/VM barriers. Note that we can't
3689 // simply kill or suspend them, as it is inherently deadlock-prone.
3690
3691 #ifndef PRODUCT
3692 // disable function tracing at JNI/JVM barriers
3693 TraceJNICalls = false;
3694 TraceJVMCalls = false;
3695 TraceRuntimeCalls = false;
3696 #endif
3697
3698 VM_Exit::set_vm_exited();
3699
3700 notify_vm_shutdown();
3701
3702 delete thread;
3703
3704 // exit_globals() will delete tty
3705 exit_globals();
3706
3707 return true;
3708 }
3709
3710
3711 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3712 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3713 return is_supported_jni_version(version);
3714 }
3715
3716
3717 jboolean Threads::is_supported_jni_version(jint version) {
3718 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3719 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3720 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3721 return JNI_FALSE;
3722 }
3723
3724
3725 void Threads::add(JavaThread* p, bool force_daemon) {
3726 // The threads lock must be owned at this point
3727 assert_locked_or_safepoint(Threads_lock);
3728
3729 // See the comment for this method in thread.hpp for its purpose and
3730 // why it is called here.
3731 p->initialize_queues();
3732 p->set_next(_thread_list);
3733 _thread_list = p;
3734 _number_of_threads++;
3735 oop threadObj = p->threadObj();
3736 bool daemon = true;
3737 // Bootstrapping problem: threadObj can be null for initial
3738 // JavaThread (or for threads attached via JNI)
3739 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3740 _number_of_non_daemon_threads++;
3741 daemon = false;
3742 }
3743
3744 ThreadService::add_thread(p, daemon);
3745
3746 // Possible GC point.
3747 Events::log("Thread added: " INTPTR_FORMAT, p);
3748 }
3749
3750 void Threads::remove(JavaThread* p) {
3751 // Extra scope needed for Thread_lock, so we can check
3752 // that we do not remove thread without safepoint code notice
3753 { MutexLocker ml(Threads_lock);
3754
3755 assert(includes(p), "p must be present");
3756
3757 JavaThread* current = _thread_list;
3758 JavaThread* prev = NULL;
3759
3760 while (current != p) {
3761 prev = current;
3762 current = current->next();
3763 }
3764
3765 if (prev) {
3766 prev->set_next(current->next());
3767 } else {
3768 _thread_list = p->next();
3769 }
3770 _number_of_threads--;
3771 oop threadObj = p->threadObj();
3772 bool daemon = true;
3773 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3774 _number_of_non_daemon_threads--;
3775 daemon = false;
3776
3777 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3778 // on destroy_vm will wake up.
3779 if (number_of_non_daemon_threads() == 1)
3780 Threads_lock->notify_all();
3781 }
3782 ThreadService::remove_thread(p, daemon);
3783
3784 // Make sure that safepoint code disregard this thread. This is needed since
3785 // the thread might mess around with locks after this point. This can cause it
3786 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3787 // of this thread since it is removed from the queue.
3788 p->set_terminated_value();
3789 } // unlock Threads_lock
3790
3791 // Since Events::log uses a lock, we grab it outside the Threads_lock
3792 Events::log("Thread exited: " INTPTR_FORMAT, p);
3793 }
3794
3795 // Threads_lock must be held when this is called (or must be called during a safepoint)
3796 bool Threads::includes(JavaThread* p) {
3797 assert(Threads_lock->is_locked(), "sanity check");
3798 ALL_JAVA_THREADS(q) {
3799 if (q == p ) {
3800 return true;
3801 }
3802 }
3803 return false;
3804 }
3805
3806 // Operations on the Threads list for GC. These are not explicitly locked,
3807 // but the garbage collector must provide a safe context for them to run.
3808 // In particular, these things should never be called when the Threads_lock
3809 // is held by some other thread. (Note: the Safepoint abstraction also
3810 // uses the Threads_lock to gurantee this property. It also makes sure that
3811 // all threads gets blocked when exiting or starting).
3812
3813 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3814 ALL_JAVA_THREADS(p) {
3815 p->oops_do(f, cf);
3816 }
3817 VMThread::vm_thread()->oops_do(f, cf);
3818 }
3819
3820 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3821 // Introduce a mechanism allowing parallel threads to claim threads as
3822 // root groups. Overhead should be small enough to use all the time,
3823 // even in sequential code.
3824 SharedHeap* sh = SharedHeap::heap();
3825 bool is_par = (sh->n_par_threads() > 0);
3826 int cp = SharedHeap::heap()->strong_roots_parity();
3827 ALL_JAVA_THREADS(p) {
3828 if (p->claim_oops_do(is_par, cp)) {
3829 p->oops_do(f, cf);
3830 }
3831 }
3832 VMThread* vmt = VMThread::vm_thread();
3833 if (vmt->claim_oops_do(is_par, cp))
3834 vmt->oops_do(f, cf);
3835 }
3836
3837 #ifndef SERIALGC
3838 // Used by ParallelScavenge
3839 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3840 ALL_JAVA_THREADS(p) {
3841 q->enqueue(new ThreadRootsTask(p));
3842 }
3843 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3844 }
3845
3846 // Used by Parallel Old
3847 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3848 ALL_JAVA_THREADS(p) {
3849 q->enqueue(new ThreadRootsMarkingTask(p));
3850 }
3851 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3852 }
3853 #endif // SERIALGC
3854
3855 void Threads::nmethods_do(CodeBlobClosure* cf) {
3856 ALL_JAVA_THREADS(p) {
3857 p->nmethods_do(cf);
3858 }
3859 VMThread::vm_thread()->nmethods_do(cf);
3860 }
3861
3862 void Threads::gc_epilogue() {
3863 ALL_JAVA_THREADS(p) {
3864 p->gc_epilogue();
3865 }
3866 }
3867
3868 void Threads::gc_prologue() {
3869 ALL_JAVA_THREADS(p) {
3870 p->gc_prologue();
3871 }
3872 }
3873
3874 void Threads::deoptimized_wrt_marked_nmethods() {
3875 ALL_JAVA_THREADS(p) {
3876 p->deoptimized_wrt_marked_nmethods();
3877 }
3878 }
3879
3880
3881 // Get count Java threads that are waiting to enter the specified monitor.
3882 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3883 address monitor, bool doLock) {
3884 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3885 "must grab Threads_lock or be at safepoint");
3886 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3887
3888 int i = 0;
3889 {
3890 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3891 ALL_JAVA_THREADS(p) {
3892 if (p->is_Compiler_thread()) continue;
3893
3894 address pending = (address)p->current_pending_monitor();
3895 if (pending == monitor) { // found a match
3896 if (i < count) result->append(p); // save the first count matches
3897 i++;
3898 }
3899 }
3900 }
3901 return result;
3902 }
3903
3904
3905 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3906 assert(doLock ||
3907 Threads_lock->owned_by_self() ||
3908 SafepointSynchronize::is_at_safepoint(),
3909 "must grab Threads_lock or be at safepoint");
3910
3911 // NULL owner means not locked so we can skip the search
3912 if (owner == NULL) return NULL;
3913
3914 {
3915 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3916 ALL_JAVA_THREADS(p) {
3917 // first, see if owner is the address of a Java thread
3918 if (owner == (address)p) return p;
3919 }
3920 }
3921 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3922 if (UseHeavyMonitors) return NULL;
3923
3924 //
3925 // If we didn't find a matching Java thread and we didn't force use of
3926 // heavyweight monitors, then the owner is the stack address of the
3927 // Lock Word in the owning Java thread's stack.
3928 //
3929 JavaThread* the_owner = NULL;
3930 {
3931 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3932 ALL_JAVA_THREADS(q) {
3933 if (q->is_lock_owned(owner)) {
3934 the_owner = q;
3935 break;
3936 }
3937 }
3938 }
3939 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3940 return the_owner;
3941 }
3942
3943 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3944 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3945 char buf[32];
3946 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3947
3948 st->print_cr("Full thread dump %s (%s %s):",
3949 Abstract_VM_Version::vm_name(),
3950 Abstract_VM_Version::vm_release(),
3951 Abstract_VM_Version::vm_info_string()
3952 );
3953 st->cr();
3954
3955 #ifndef SERIALGC
3956 // Dump concurrent locks
3957 ConcurrentLocksDump concurrent_locks;
3958 if (print_concurrent_locks) {
3959 concurrent_locks.dump_at_safepoint();
3960 }
3961 #endif // SERIALGC
3962
3963 ALL_JAVA_THREADS(p) {
3964 ResourceMark rm;
3965 p->print_on(st);
3966 if (print_stacks) {
3967 if (internal_format) {
3968 p->trace_stack();
3969 } else {
3970 p->print_stack_on(st);
3971 }
3972 }
3973 st->cr();
3974 #ifndef SERIALGC
3975 if (print_concurrent_locks) {
3976 concurrent_locks.print_locks_on(p, st);
3977 }
3978 #endif // SERIALGC
3979 }
3980
3981 VMThread::vm_thread()->print_on(st);
3982 st->cr();
3983 Universe::heap()->print_gc_threads_on(st);
3984 WatcherThread* wt = WatcherThread::watcher_thread();
3985 if (wt != NULL) wt->print_on(st);
3986 st->cr();
3987 CompileBroker::print_compiler_threads_on(st);
3988 st->flush();
3989 }
3990
3991 // Threads::print_on_error() is called by fatal error handler. It's possible
3992 // that VM is not at safepoint and/or current thread is inside signal handler.
3993 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3994 // memory (even in resource area), it might deadlock the error handler.
3995 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
3996 bool found_current = false;
3997 st->print_cr("Java Threads: ( => current thread )");
3998 ALL_JAVA_THREADS(thread) {
3999 bool is_current = (current == thread);
4000 found_current = found_current || is_current;
4001
4002 st->print("%s", is_current ? "=>" : " ");
4003
4004 st->print(PTR_FORMAT, thread);
4005 st->print(" ");
4006 thread->print_on_error(st, buf, buflen);
4007 st->cr();
4008 }
4009 st->cr();
4010
4011 st->print_cr("Other Threads:");
4012 if (VMThread::vm_thread()) {
4013 bool is_current = (current == VMThread::vm_thread());
4014 found_current = found_current || is_current;
4015 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4016
4017 st->print(PTR_FORMAT, VMThread::vm_thread());
4018 st->print(" ");
4019 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4020 st->cr();
4021 }
4022 WatcherThread* wt = WatcherThread::watcher_thread();
4023 if (wt != NULL) {
4024 bool is_current = (current == wt);
4025 found_current = found_current || is_current;
4026 st->print("%s", is_current ? "=>" : " ");
4027
4028 st->print(PTR_FORMAT, wt);
4029 st->print(" ");
4030 wt->print_on_error(st, buf, buflen);
4031 st->cr();
4032 }
4033 if (!found_current) {
4034 st->cr();
4035 st->print("=>" PTR_FORMAT " (exited) ", current);
4036 current->print_on_error(st, buf, buflen);
4037 st->cr();
4038 }
4039 }
4040
4041 // Internal SpinLock and Mutex
4042 // Based on ParkEvent
4043
4044 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4045 //
4046 // We employ SpinLocks _only for low-contention, fixed-length
4047 // short-duration critical sections where we're concerned
4048 // about native mutex_t or HotSpot Mutex:: latency.
4049 // The mux construct provides a spin-then-block mutual exclusion
4050 // mechanism.
4051 //
4052 // Testing has shown that contention on the ListLock guarding gFreeList
4053 // is common. If we implement ListLock as a simple SpinLock it's common
4054 // for the JVM to devolve to yielding with little progress. This is true
4055 // despite the fact that the critical sections protected by ListLock are
4056 // extremely short.
4057 //
4058 // TODO-FIXME: ListLock should be of type SpinLock.
4059 // We should make this a 1st-class type, integrated into the lock
4060 // hierarchy as leaf-locks. Critically, the SpinLock structure
4061 // should have sufficient padding to avoid false-sharing and excessive
4062 // cache-coherency traffic.
4063
4064
4065 typedef volatile int SpinLockT ;
4066
4067 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4068 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4069 return ; // normal fast-path return
4070 }
4071
4072 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4073 TEVENT (SpinAcquire - ctx) ;
4074 int ctr = 0 ;
4075 int Yields = 0 ;
4076 for (;;) {
4077 while (*adr != 0) {
4078 ++ctr ;
4079 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4080 if (Yields > 5) {
4081 // Consider using a simple NakedSleep() instead.
4082 // Then SpinAcquire could be called by non-JVM threads
4083 Thread::current()->_ParkEvent->park(1) ;
4084 } else {
4085 os::NakedYield() ;
4086 ++Yields ;
4087 }
4088 } else {
4089 SpinPause() ;
4090 }
4091 }
4092 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4093 }
4094 }
4095
4096 void Thread::SpinRelease (volatile int * adr) {
4097 assert (*adr != 0, "invariant") ;
4098 OrderAccess::fence() ; // guarantee at least release consistency.
4099 // Roach-motel semantics.
4100 // It's safe if subsequent LDs and STs float "up" into the critical section,
4101 // but prior LDs and STs within the critical section can't be allowed
4102 // to reorder or float past the ST that releases the lock.
4103 *adr = 0 ;
4104 }
4105
4106 // muxAcquire and muxRelease:
4107 //
4108 // * muxAcquire and muxRelease support a single-word lock-word construct.
4109 // The LSB of the word is set IFF the lock is held.
4110 // The remainder of the word points to the head of a singly-linked list
4111 // of threads blocked on the lock.
4112 //
4113 // * The current implementation of muxAcquire-muxRelease uses its own
4114 // dedicated Thread._MuxEvent instance. If we're interested in
4115 // minimizing the peak number of extant ParkEvent instances then
4116 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4117 // as certain invariants were satisfied. Specifically, care would need
4118 // to be taken with regards to consuming unpark() "permits".
4119 // A safe rule of thumb is that a thread would never call muxAcquire()
4120 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4121 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4122 // consume an unpark() permit intended for monitorenter, for instance.
4123 // One way around this would be to widen the restricted-range semaphore
4124 // implemented in park(). Another alternative would be to provide
4125 // multiple instances of the PlatformEvent() for each thread. One
4126 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4127 //
4128 // * Usage:
4129 // -- Only as leaf locks
4130 // -- for short-term locking only as muxAcquire does not perform
4131 // thread state transitions.
4132 //
4133 // Alternatives:
4134 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4135 // but with parking or spin-then-park instead of pure spinning.
4136 // * Use Taura-Oyama-Yonenzawa locks.
4137 // * It's possible to construct a 1-0 lock if we encode the lockword as
4138 // (List,LockByte). Acquire will CAS the full lockword while Release
4139 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4140 // acquiring threads use timers (ParkTimed) to detect and recover from
4141 // the stranding window. Thread/Node structures must be aligned on 256-byte
4142 // boundaries by using placement-new.
4143 // * Augment MCS with advisory back-link fields maintained with CAS().
4144 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4145 // The validity of the backlinks must be ratified before we trust the value.
4146 // If the backlinks are invalid the exiting thread must back-track through the
4147 // the forward links, which are always trustworthy.
4148 // * Add a successor indication. The LockWord is currently encoded as
4149 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4150 // to provide the usual futile-wakeup optimization.
4151 // See RTStt for details.
4152 // * Consider schedctl.sc_nopreempt to cover the critical section.
4153 //
4154
4155
4156 typedef volatile intptr_t MutexT ; // Mux Lock-word
4157 enum MuxBits { LOCKBIT = 1 } ;
4158
4159 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4160 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4161 if (w == 0) return ;
4162 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4163 return ;
4164 }
4165
4166 TEVENT (muxAcquire - Contention) ;
4167 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4168 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4169 for (;;) {
4170 int its = (os::is_MP() ? 100 : 0) + 1 ;
4171
4172 // Optional spin phase: spin-then-park strategy
4173 while (--its >= 0) {
4174 w = *Lock ;
4175 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4176 return ;
4177 }
4178 }
4179
4180 Self->reset() ;
4181 Self->OnList = intptr_t(Lock) ;
4182 // The following fence() isn't _strictly necessary as the subsequent
4183 // CAS() both serializes execution and ratifies the fetched *Lock value.
4184 OrderAccess::fence();
4185 for (;;) {
4186 w = *Lock ;
4187 if ((w & LOCKBIT) == 0) {
4188 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4189 Self->OnList = 0 ; // hygiene - allows stronger asserts
4190 return ;
4191 }
4192 continue ; // Interference -- *Lock changed -- Just retry
4193 }
4194 assert (w & LOCKBIT, "invariant") ;
4195 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4196 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4197 }
4198
4199 while (Self->OnList != 0) {
4200 Self->park() ;
4201 }
4202 }
4203 }
4204
4205 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4206 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4207 if (w == 0) return ;
4208 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4209 return ;
4210 }
4211
4212 TEVENT (muxAcquire - Contention) ;
4213 ParkEvent * ReleaseAfter = NULL ;
4214 if (ev == NULL) {
4215 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4216 }
4217 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4218 for (;;) {
4219 guarantee (ev->OnList == 0, "invariant") ;
4220 int its = (os::is_MP() ? 100 : 0) + 1 ;
4221
4222 // Optional spin phase: spin-then-park strategy
4223 while (--its >= 0) {
4224 w = *Lock ;
4225 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4226 if (ReleaseAfter != NULL) {
4227 ParkEvent::Release (ReleaseAfter) ;
4228 }
4229 return ;
4230 }
4231 }
4232
4233 ev->reset() ;
4234 ev->OnList = intptr_t(Lock) ;
4235 // The following fence() isn't _strictly necessary as the subsequent
4236 // CAS() both serializes execution and ratifies the fetched *Lock value.
4237 OrderAccess::fence();
4238 for (;;) {
4239 w = *Lock ;
4240 if ((w & LOCKBIT) == 0) {
4241 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4242 ev->OnList = 0 ;
4243 // We call ::Release while holding the outer lock, thus
4244 // artificially lengthening the critical section.
4245 // Consider deferring the ::Release() until the subsequent unlock(),
4246 // after we've dropped the outer lock.
4247 if (ReleaseAfter != NULL) {
4248 ParkEvent::Release (ReleaseAfter) ;
4249 }
4250 return ;
4251 }
4252 continue ; // Interference -- *Lock changed -- Just retry
4253 }
4254 assert (w & LOCKBIT, "invariant") ;
4255 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4256 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4257 }
4258
4259 while (ev->OnList != 0) {
4260 ev->park() ;
4261 }
4262 }
4263 }
4264
4265 // Release() must extract a successor from the list and then wake that thread.
4266 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4267 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4268 // Release() would :
4269 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4270 // (B) Extract a successor from the private list "in-hand"
4271 // (C) attempt to CAS() the residual back into *Lock over null.
4272 // If there were any newly arrived threads and the CAS() would fail.
4273 // In that case Release() would detach the RATs, re-merge the list in-hand
4274 // with the RATs and repeat as needed. Alternately, Release() might
4275 // detach and extract a successor, but then pass the residual list to the wakee.
4276 // The wakee would be responsible for reattaching and remerging before it
4277 // competed for the lock.
4278 //
4279 // Both "pop" and DMR are immune from ABA corruption -- there can be
4280 // multiple concurrent pushers, but only one popper or detacher.
4281 // This implementation pops from the head of the list. This is unfair,
4282 // but tends to provide excellent throughput as hot threads remain hot.
4283 // (We wake recently run threads first).
4284
4285 void Thread::muxRelease (volatile intptr_t * Lock) {
4286 for (;;) {
4287 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4288 assert (w & LOCKBIT, "invariant") ;
4289 if (w == LOCKBIT) return ;
4290 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4291 assert (List != NULL, "invariant") ;
4292 assert (List->OnList == intptr_t(Lock), "invariant") ;
4293 ParkEvent * nxt = List->ListNext ;
4294
4295 // The following CAS() releases the lock and pops the head element.
4296 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4297 continue ;
4298 }
4299 List->OnList = 0 ;
4300 OrderAccess::fence() ;
4301 List->unpark () ;
4302 return ;
4303 }
4304 }
4305
4306
4307 void Threads::verify() {
4308 ALL_JAVA_THREADS(p) {
4309 p->verify();
4310 }
4311 VMThread* thread = VMThread::vm_thread();
4312 if (thread != NULL) thread->verify();
4313 }