1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "logging/logStream.hpp"
45 #include "memory/metaspaceShared.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "memory/universe.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/objArrayOop.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/symbol.hpp"
53 #include "oops/verifyOopClosure.hpp"
54 #include "prims/jvm.h"
55 #include "prims/jvm_misc.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "prims/jvmtiThreadState.hpp"
58 #include "prims/privilegedStack.hpp"
59 #include "runtime/arguments.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/commandLineFlagConstraintList.hpp"
63 #include "runtime/commandLineFlagWriteableList.hpp"
64 #include "runtime/commandLineFlagRangeList.hpp"
65 #include "runtime/deoptimization.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/interfaceSupport.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/javaCalls.hpp"
72 #include "runtime/jniPeriodicChecker.hpp"
73 #include "runtime/timerTrace.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "runtime/safepointMechanism.inline.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/statSampler.hpp"
83 #include "runtime/stubRoutines.hpp"
84 #include "runtime/sweeper.hpp"
85 #include "runtime/task.hpp"
86 #include "runtime/thread.inline.hpp"
87 #include "runtime/threadCritical.hpp"
88 #include "runtime/vframe.hpp"
89 #include "runtime/vframeArray.hpp"
90 #include "runtime/vframe_hp.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "runtime/vm_operations.hpp"
93 #include "runtime/vm_version.hpp"
94 #include "services/attachListener.hpp"
95 #include "services/management.hpp"
96 #include "services/memTracker.hpp"
97 #include "services/threadService.hpp"
98 #include "trace/traceMacros.hpp"
99 #include "trace/tracing.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/defaultStream.hpp"
102 #include "utilities/dtrace.hpp"
103 #include "utilities/events.hpp"
104 #include "utilities/macros.hpp"
105 #include "utilities/preserveException.hpp"
106 #include "utilities/vmError.hpp"
107 #if INCLUDE_ALL_GCS
108 #include "gc/cms/concurrentMarkSweepThread.hpp"
109 #include "gc/g1/concurrentMarkThread.inline.hpp"
110 #include "gc/parallel/pcTasks.hpp"
111 #endif // INCLUDE_ALL_GCS
112 #if INCLUDE_JVMCI
113 #include "jvmci/jvmciCompiler.hpp"
114 #include "jvmci/jvmciRuntime.hpp"
115 #include "logging/logHandle.hpp"
116 #endif
117 #ifdef COMPILER1
118 #include "c1/c1_Compiler.hpp"
119 #endif
120 #ifdef COMPILER2
121 #include "opto/c2compiler.hpp"
122 #include "opto/idealGraphPrinter.hpp"
123 #endif
124 #if INCLUDE_RTM_OPT
125 #include "runtime/rtmLocking.hpp"
126 #endif
127
128 // Initialization after module runtime initialization
129 void universe_post_module_init(); // must happen after call_initPhase2
130
131 #ifdef DTRACE_ENABLED
132
133 // Only bother with this argument setup if dtrace is available
134
135 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
136 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
137
138 #define DTRACE_THREAD_PROBE(probe, javathread) \
139 { \
140 ResourceMark rm(this); \
141 int len = 0; \
142 const char* name = (javathread)->get_thread_name(); \
143 len = strlen(name); \
144 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
145 (char *) name, len, \
146 java_lang_Thread::thread_id((javathread)->threadObj()), \
147 (uintptr_t) (javathread)->osthread()->thread_id(), \
148 java_lang_Thread::is_daemon((javathread)->threadObj())); \
149 }
150
151 #else // ndef DTRACE_ENABLED
152
153 #define DTRACE_THREAD_PROBE(probe, javathread)
154
155 #endif // ndef DTRACE_ENABLED
156
157 #ifndef USE_LIBRARY_BASED_TLS_ONLY
158 // Current thread is maintained as a thread-local variable
159 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
160 #endif
161 // Class hierarchy
162 // - Thread
163 // - VMThread
164 // - WatcherThread
165 // - ConcurrentMarkSweepThread
166 // - JavaThread
167 // - CompilerThread
168
169 // ======= Thread ========
170 // Support for forcing alignment of thread objects for biased locking
171 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
172 if (UseBiasedLocking) {
173 const int alignment = markOopDesc::biased_lock_alignment;
174 size_t aligned_size = size + (alignment - sizeof(intptr_t));
175 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
176 : AllocateHeap(aligned_size, flags, CURRENT_PC,
177 AllocFailStrategy::RETURN_NULL);
178 void* aligned_addr = align_up(real_malloc_addr, alignment);
179 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
180 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
181 "JavaThread alignment code overflowed allocated storage");
182 if (aligned_addr != real_malloc_addr) {
183 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
184 p2i(real_malloc_addr),
185 p2i(aligned_addr));
186 }
187 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
188 return aligned_addr;
189 } else {
190 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
191 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
192 }
193 }
194
195 void Thread::operator delete(void* p) {
196 if (UseBiasedLocking) {
197 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
198 FreeHeap(real_malloc_addr);
199 } else {
200 FreeHeap(p);
201 }
202 }
203
204
205 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
206 // JavaThread
207
208
209 Thread::Thread() {
210 // stack and get_thread
211 set_stack_base(NULL);
212 set_stack_size(0);
213 set_self_raw_id(0);
214 set_lgrp_id(-1);
215 DEBUG_ONLY(clear_suspendible_thread();)
216
217 // allocated data structures
218 set_osthread(NULL);
219 set_resource_area(new (mtThread)ResourceArea());
220 DEBUG_ONLY(_current_resource_mark = NULL;)
221 set_handle_area(new (mtThread) HandleArea(NULL));
222 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
223 set_active_handles(NULL);
224 set_free_handle_block(NULL);
225 set_last_handle_mark(NULL);
226
227 // This initial value ==> never claimed.
228 _oops_do_parity = 0;
229
230 // the handle mark links itself to last_handle_mark
231 new HandleMark(this);
232
233 // plain initialization
234 debug_only(_owned_locks = NULL;)
235 debug_only(_allow_allocation_count = 0;)
236 NOT_PRODUCT(_allow_safepoint_count = 0;)
237 NOT_PRODUCT(_skip_gcalot = false;)
238 _jvmti_env_iteration_count = 0;
239 set_allocated_bytes(0);
240 _vm_operation_started_count = 0;
241 _vm_operation_completed_count = 0;
242 _current_pending_monitor = NULL;
243 _current_pending_monitor_is_from_java = true;
244 _current_waiting_monitor = NULL;
245 _num_nested_signal = 0;
246 omFreeList = NULL;
247 omFreeCount = 0;
248 omFreeProvision = 32;
249 omInUseList = NULL;
250 omInUseCount = 0;
251
252 #ifdef ASSERT
253 _visited_for_critical_count = false;
254 #endif
255
256 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
257 Monitor::_safepoint_check_sometimes);
258 _suspend_flags = 0;
259
260 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
261 _hashStateX = os::random();
262 _hashStateY = 842502087;
263 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
264 _hashStateW = 273326509;
265
266 _OnTrap = 0;
267 _schedctl = NULL;
268 _Stalled = 0;
269 _TypeTag = 0x2BAD;
270
271 // Many of the following fields are effectively final - immutable
272 // Note that nascent threads can't use the Native Monitor-Mutex
273 // construct until the _MutexEvent is initialized ...
274 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
275 // we might instead use a stack of ParkEvents that we could provision on-demand.
276 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
277 // and ::Release()
278 _ParkEvent = ParkEvent::Allocate(this);
279 _SleepEvent = ParkEvent::Allocate(this);
280 _MutexEvent = ParkEvent::Allocate(this);
281 _MuxEvent = ParkEvent::Allocate(this);
282
283 #ifdef CHECK_UNHANDLED_OOPS
284 if (CheckUnhandledOops) {
285 _unhandled_oops = new UnhandledOops(this);
286 }
287 #endif // CHECK_UNHANDLED_OOPS
288 #ifdef ASSERT
289 if (UseBiasedLocking) {
290 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
291 assert(this == _real_malloc_address ||
292 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
293 "bug in forced alignment of thread objects");
294 }
295 #endif // ASSERT
296 }
297
298 void Thread::initialize_thread_current() {
299 #ifndef USE_LIBRARY_BASED_TLS_ONLY
300 assert(_thr_current == NULL, "Thread::current already initialized");
301 _thr_current = this;
302 #endif
303 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
304 ThreadLocalStorage::set_thread(this);
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 }
307
308 void Thread::clear_thread_current() {
309 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
310 #ifndef USE_LIBRARY_BASED_TLS_ONLY
311 _thr_current = NULL;
312 #endif
313 ThreadLocalStorage::set_thread(NULL);
314 }
315
316 void Thread::record_stack_base_and_size() {
317 set_stack_base(os::current_stack_base());
318 set_stack_size(os::current_stack_size());
319 // CR 7190089: on Solaris, primordial thread's stack is adjusted
320 // in initialize_thread(). Without the adjustment, stack size is
321 // incorrect if stack is set to unlimited (ulimit -s unlimited).
322 // So far, only Solaris has real implementation of initialize_thread().
323 //
324 // set up any platform-specific state.
325 os::initialize_thread(this);
326
327 // Set stack limits after thread is initialized.
328 if (is_Java_thread()) {
329 ((JavaThread*) this)->set_stack_overflow_limit();
330 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
331 }
332 #if INCLUDE_NMT
333 // record thread's native stack, stack grows downward
334 MemTracker::record_thread_stack(stack_end(), stack_size());
335 #endif // INCLUDE_NMT
336 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
337 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
338 os::current_thread_id(), p2i(stack_base() - stack_size()),
339 p2i(stack_base()), stack_size()/1024);
340 }
341
342
343 Thread::~Thread() {
344 EVENT_THREAD_DESTRUCT(this);
345
346 // stack_base can be NULL if the thread is never started or exited before
347 // record_stack_base_and_size called. Although, we would like to ensure
348 // that all started threads do call record_stack_base_and_size(), there is
349 // not proper way to enforce that.
350 #if INCLUDE_NMT
351 if (_stack_base != NULL) {
352 MemTracker::release_thread_stack(stack_end(), stack_size());
353 #ifdef ASSERT
354 set_stack_base(NULL);
355 #endif
356 }
357 #endif // INCLUDE_NMT
358
359 // deallocate data structures
360 delete resource_area();
361 // since the handle marks are using the handle area, we have to deallocated the root
362 // handle mark before deallocating the thread's handle area,
363 assert(last_handle_mark() != NULL, "check we have an element");
364 delete last_handle_mark();
365 assert(last_handle_mark() == NULL, "check we have reached the end");
366
367 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
368 // We NULL out the fields for good hygiene.
369 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
370 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
371 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
372 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
373
374 delete handle_area();
375 delete metadata_handles();
376
377 // SR_handler uses this as a termination indicator -
378 // needs to happen before os::free_thread()
379 delete _SR_lock;
380 _SR_lock = NULL;
381
382 // osthread() can be NULL, if creation of thread failed.
383 if (osthread() != NULL) os::free_thread(osthread());
384
385 // clear Thread::current if thread is deleting itself.
386 // Needed to ensure JNI correctly detects non-attached threads.
387 if (this == Thread::current()) {
388 clear_thread_current();
389 }
390
391 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
392 }
393
394 // NOTE: dummy function for assertion purpose.
395 void Thread::run() {
396 ShouldNotReachHere();
397 }
398
399 #ifdef ASSERT
400 // Private method to check for dangling thread pointer
401 void check_for_dangling_thread_pointer(Thread *thread) {
402 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
403 "possibility of dangling Thread pointer");
404 }
405 #endif
406
407 ThreadPriority Thread::get_priority(const Thread* const thread) {
408 ThreadPriority priority;
409 // Can return an error!
410 (void)os::get_priority(thread, priority);
411 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
412 return priority;
413 }
414
415 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
416 debug_only(check_for_dangling_thread_pointer(thread);)
417 // Can return an error!
418 (void)os::set_priority(thread, priority);
419 }
420
421
422 void Thread::start(Thread* thread) {
423 // Start is different from resume in that its safety is guaranteed by context or
424 // being called from a Java method synchronized on the Thread object.
425 if (!DisableStartThread) {
426 if (thread->is_Java_thread()) {
427 // Initialize the thread state to RUNNABLE before starting this thread.
428 // Can not set it after the thread started because we do not know the
429 // exact thread state at that time. It could be in MONITOR_WAIT or
430 // in SLEEPING or some other state.
431 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
432 java_lang_Thread::RUNNABLE);
433 }
434 os::start_thread(thread);
435 }
436 }
437
438 // Enqueue a VM_Operation to do the job for us - sometime later
439 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
440 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
441 VMThread::execute(vm_stop);
442 }
443
444
445 // Check if an external suspend request has completed (or has been
446 // cancelled). Returns true if the thread is externally suspended and
447 // false otherwise.
448 //
449 // The bits parameter returns information about the code path through
450 // the routine. Useful for debugging:
451 //
452 // set in is_ext_suspend_completed():
453 // 0x00000001 - routine was entered
454 // 0x00000010 - routine return false at end
455 // 0x00000100 - thread exited (return false)
456 // 0x00000200 - suspend request cancelled (return false)
457 // 0x00000400 - thread suspended (return true)
458 // 0x00001000 - thread is in a suspend equivalent state (return true)
459 // 0x00002000 - thread is native and walkable (return true)
460 // 0x00004000 - thread is native_trans and walkable (needed retry)
461 //
462 // set in wait_for_ext_suspend_completion():
463 // 0x00010000 - routine was entered
464 // 0x00020000 - suspend request cancelled before loop (return false)
465 // 0x00040000 - thread suspended before loop (return true)
466 // 0x00080000 - suspend request cancelled in loop (return false)
467 // 0x00100000 - thread suspended in loop (return true)
468 // 0x00200000 - suspend not completed during retry loop (return false)
469
470 // Helper class for tracing suspend wait debug bits.
471 //
472 // 0x00000100 indicates that the target thread exited before it could
473 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
474 // 0x00080000 each indicate a cancelled suspend request so they don't
475 // count as wait failures either.
476 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
477
478 class TraceSuspendDebugBits : public StackObj {
479 private:
480 JavaThread * jt;
481 bool is_wait;
482 bool called_by_wait; // meaningful when !is_wait
483 uint32_t * bits;
484
485 public:
486 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
487 uint32_t *_bits) {
488 jt = _jt;
489 is_wait = _is_wait;
490 called_by_wait = _called_by_wait;
491 bits = _bits;
492 }
493
494 ~TraceSuspendDebugBits() {
495 if (!is_wait) {
496 #if 1
497 // By default, don't trace bits for is_ext_suspend_completed() calls.
498 // That trace is very chatty.
499 return;
500 #else
501 if (!called_by_wait) {
502 // If tracing for is_ext_suspend_completed() is enabled, then only
503 // trace calls to it from wait_for_ext_suspend_completion()
504 return;
505 }
506 #endif
507 }
508
509 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
510 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
511 MutexLocker ml(Threads_lock); // needed for get_thread_name()
512 ResourceMark rm;
513
514 tty->print_cr(
515 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
516 jt->get_thread_name(), *bits);
517
518 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
519 }
520 }
521 }
522 };
523 #undef DEBUG_FALSE_BITS
524
525
526 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
527 uint32_t *bits) {
528 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
529
530 bool did_trans_retry = false; // only do thread_in_native_trans retry once
531 bool do_trans_retry; // flag to force the retry
532
533 *bits |= 0x00000001;
534
535 do {
536 do_trans_retry = false;
537
538 if (is_exiting()) {
539 // Thread is in the process of exiting. This is always checked
540 // first to reduce the risk of dereferencing a freed JavaThread.
541 *bits |= 0x00000100;
542 return false;
543 }
544
545 if (!is_external_suspend()) {
546 // Suspend request is cancelled. This is always checked before
547 // is_ext_suspended() to reduce the risk of a rogue resume
548 // confusing the thread that made the suspend request.
549 *bits |= 0x00000200;
550 return false;
551 }
552
553 if (is_ext_suspended()) {
554 // thread is suspended
555 *bits |= 0x00000400;
556 return true;
557 }
558
559 // Now that we no longer do hard suspends of threads running
560 // native code, the target thread can be changing thread state
561 // while we are in this routine:
562 //
563 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
564 //
565 // We save a copy of the thread state as observed at this moment
566 // and make our decision about suspend completeness based on the
567 // copy. This closes the race where the thread state is seen as
568 // _thread_in_native_trans in the if-thread_blocked check, but is
569 // seen as _thread_blocked in if-thread_in_native_trans check.
570 JavaThreadState save_state = thread_state();
571
572 if (save_state == _thread_blocked && is_suspend_equivalent()) {
573 // If the thread's state is _thread_blocked and this blocking
574 // condition is known to be equivalent to a suspend, then we can
575 // consider the thread to be externally suspended. This means that
576 // the code that sets _thread_blocked has been modified to do
577 // self-suspension if the blocking condition releases. We also
578 // used to check for CONDVAR_WAIT here, but that is now covered by
579 // the _thread_blocked with self-suspension check.
580 //
581 // Return true since we wouldn't be here unless there was still an
582 // external suspend request.
583 *bits |= 0x00001000;
584 return true;
585 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
586 // Threads running native code will self-suspend on native==>VM/Java
587 // transitions. If its stack is walkable (should always be the case
588 // unless this function is called before the actual java_suspend()
589 // call), then the wait is done.
590 *bits |= 0x00002000;
591 return true;
592 } else if (!called_by_wait && !did_trans_retry &&
593 save_state == _thread_in_native_trans &&
594 frame_anchor()->walkable()) {
595 // The thread is transitioning from thread_in_native to another
596 // thread state. check_safepoint_and_suspend_for_native_trans()
597 // will force the thread to self-suspend. If it hasn't gotten
598 // there yet we may have caught the thread in-between the native
599 // code check above and the self-suspend. Lucky us. If we were
600 // called by wait_for_ext_suspend_completion(), then it
601 // will be doing the retries so we don't have to.
602 //
603 // Since we use the saved thread state in the if-statement above,
604 // there is a chance that the thread has already transitioned to
605 // _thread_blocked by the time we get here. In that case, we will
606 // make a single unnecessary pass through the logic below. This
607 // doesn't hurt anything since we still do the trans retry.
608
609 *bits |= 0x00004000;
610
611 // Once the thread leaves thread_in_native_trans for another
612 // thread state, we break out of this retry loop. We shouldn't
613 // need this flag to prevent us from getting back here, but
614 // sometimes paranoia is good.
615 did_trans_retry = true;
616
617 // We wait for the thread to transition to a more usable state.
618 for (int i = 1; i <= SuspendRetryCount; i++) {
619 // We used to do an "os::yield_all(i)" call here with the intention
620 // that yielding would increase on each retry. However, the parameter
621 // is ignored on Linux which means the yield didn't scale up. Waiting
622 // on the SR_lock below provides a much more predictable scale up for
623 // the delay. It also provides a simple/direct point to check for any
624 // safepoint requests from the VMThread
625
626 // temporarily drops SR_lock while doing wait with safepoint check
627 // (if we're a JavaThread - the WatcherThread can also call this)
628 // and increase delay with each retry
629 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
630
631 // check the actual thread state instead of what we saved above
632 if (thread_state() != _thread_in_native_trans) {
633 // the thread has transitioned to another thread state so
634 // try all the checks (except this one) one more time.
635 do_trans_retry = true;
636 break;
637 }
638 } // end retry loop
639
640
641 }
642 } while (do_trans_retry);
643
644 *bits |= 0x00000010;
645 return false;
646 }
647
648 // Wait for an external suspend request to complete (or be cancelled).
649 // Returns true if the thread is externally suspended and false otherwise.
650 //
651 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
652 uint32_t *bits) {
653 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
654 false /* !called_by_wait */, bits);
655
656 // local flag copies to minimize SR_lock hold time
657 bool is_suspended;
658 bool pending;
659 uint32_t reset_bits;
660
661 // set a marker so is_ext_suspend_completed() knows we are the caller
662 *bits |= 0x00010000;
663
664 // We use reset_bits to reinitialize the bits value at the top of
665 // each retry loop. This allows the caller to make use of any
666 // unused bits for their own marking purposes.
667 reset_bits = *bits;
668
669 {
670 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
671 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
672 delay, bits);
673 pending = is_external_suspend();
674 }
675 // must release SR_lock to allow suspension to complete
676
677 if (!pending) {
678 // A cancelled suspend request is the only false return from
679 // is_ext_suspend_completed() that keeps us from entering the
680 // retry loop.
681 *bits |= 0x00020000;
682 return false;
683 }
684
685 if (is_suspended) {
686 *bits |= 0x00040000;
687 return true;
688 }
689
690 for (int i = 1; i <= retries; i++) {
691 *bits = reset_bits; // reinit to only track last retry
692
693 // We used to do an "os::yield_all(i)" call here with the intention
694 // that yielding would increase on each retry. However, the parameter
695 // is ignored on Linux which means the yield didn't scale up. Waiting
696 // on the SR_lock below provides a much more predictable scale up for
697 // the delay. It also provides a simple/direct point to check for any
698 // safepoint requests from the VMThread
699
700 {
701 MutexLocker ml(SR_lock());
702 // wait with safepoint check (if we're a JavaThread - the WatcherThread
703 // can also call this) and increase delay with each retry
704 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
705
706 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
707 delay, bits);
708
709 // It is possible for the external suspend request to be cancelled
710 // (by a resume) before the actual suspend operation is completed.
711 // Refresh our local copy to see if we still need to wait.
712 pending = is_external_suspend();
713 }
714
715 if (!pending) {
716 // A cancelled suspend request is the only false return from
717 // is_ext_suspend_completed() that keeps us from staying in the
718 // retry loop.
719 *bits |= 0x00080000;
720 return false;
721 }
722
723 if (is_suspended) {
724 *bits |= 0x00100000;
725 return true;
726 }
727 } // end retry loop
728
729 // thread did not suspend after all our retries
730 *bits |= 0x00200000;
731 return false;
732 }
733
734 #ifndef PRODUCT
735 void JavaThread::record_jump(address target, address instr, const char* file,
736 int line) {
737
738 // This should not need to be atomic as the only way for simultaneous
739 // updates is via interrupts. Even then this should be rare or non-existent
740 // and we don't care that much anyway.
741
742 int index = _jmp_ring_index;
743 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
744 _jmp_ring[index]._target = (intptr_t) target;
745 _jmp_ring[index]._instruction = (intptr_t) instr;
746 _jmp_ring[index]._file = file;
747 _jmp_ring[index]._line = line;
748 }
749 #endif // PRODUCT
750
751 void Thread::interrupt(Thread* thread) {
752 debug_only(check_for_dangling_thread_pointer(thread);)
753 os::interrupt(thread);
754 }
755
756 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
757 debug_only(check_for_dangling_thread_pointer(thread);)
758 // Note: If clear_interrupted==false, this simply fetches and
759 // returns the value of the field osthread()->interrupted().
760 return os::is_interrupted(thread, clear_interrupted);
761 }
762
763
764 // GC Support
765 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
766 jint thread_parity = _oops_do_parity;
767 if (thread_parity != strong_roots_parity) {
768 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
769 if (res == thread_parity) {
770 return true;
771 } else {
772 guarantee(res == strong_roots_parity, "Or else what?");
773 return false;
774 }
775 }
776 return false;
777 }
778
779 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
780 active_handles()->oops_do(f);
781 // Do oop for ThreadShadow
782 f->do_oop((oop*)&_pending_exception);
783 handle_area()->oops_do(f);
784
785 if (MonitorInUseLists) {
786 // When using thread local monitor lists, we scan them here,
787 // and the remaining global monitors in ObjectSynchronizer::oops_do().
788 ObjectSynchronizer::thread_local_used_oops_do(this, f);
789 }
790 }
791
792 void Thread::metadata_handles_do(void f(Metadata*)) {
793 // Only walk the Handles in Thread.
794 if (metadata_handles() != NULL) {
795 for (int i = 0; i< metadata_handles()->length(); i++) {
796 f(metadata_handles()->at(i));
797 }
798 }
799 }
800
801 void Thread::print_on(outputStream* st) const {
802 // get_priority assumes osthread initialized
803 if (osthread() != NULL) {
804 int os_prio;
805 if (os::get_native_priority(this, &os_prio) == OS_OK) {
806 st->print("os_prio=%d ", os_prio);
807 }
808 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
809 ext().print_on(st);
810 osthread()->print_on(st);
811 }
812 debug_only(if (WizardMode) print_owned_locks_on(st);)
813 }
814
815 // Thread::print_on_error() is called by fatal error handler. Don't use
816 // any lock or allocate memory.
817 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
818 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
819
820 if (is_VM_thread()) { st->print("VMThread"); }
821 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
822 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
823 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
824 else { st->print("Thread"); }
825
826 if (is_Named_thread()) {
827 st->print(" \"%s\"", name());
828 }
829
830 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
831 p2i(stack_end()), p2i(stack_base()));
832
833 if (osthread()) {
834 st->print(" [id=%d]", osthread()->thread_id());
835 }
836 }
837
838 void Thread::print_value_on(outputStream* st) const {
839 if (is_Named_thread()) {
840 st->print(" \"%s\" ", name());
841 }
842 st->print(INTPTR_FORMAT, p2i(this)); // print address
843 }
844
845 #ifdef ASSERT
846 void Thread::print_owned_locks_on(outputStream* st) const {
847 Monitor *cur = _owned_locks;
848 if (cur == NULL) {
849 st->print(" (no locks) ");
850 } else {
851 st->print_cr(" Locks owned:");
852 while (cur) {
853 cur->print_on(st);
854 cur = cur->next();
855 }
856 }
857 }
858
859 static int ref_use_count = 0;
860
861 bool Thread::owns_locks_but_compiled_lock() const {
862 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
863 if (cur != Compile_lock) return true;
864 }
865 return false;
866 }
867
868
869 #endif
870
871 #ifndef PRODUCT
872
873 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
874 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
875 // no threads which allow_vm_block's are held
876 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
877 // Check if current thread is allowed to block at a safepoint
878 if (!(_allow_safepoint_count == 0)) {
879 fatal("Possible safepoint reached by thread that does not allow it");
880 }
881 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
882 fatal("LEAF method calling lock?");
883 }
884
885 #ifdef ASSERT
886 if (potential_vm_operation && is_Java_thread()
887 && !Universe::is_bootstrapping()) {
888 // Make sure we do not hold any locks that the VM thread also uses.
889 // This could potentially lead to deadlocks
890 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
891 // Threads_lock is special, since the safepoint synchronization will not start before this is
892 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
893 // since it is used to transfer control between JavaThreads and the VMThread
894 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
895 if ((cur->allow_vm_block() &&
896 cur != Threads_lock &&
897 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
898 cur != VMOperationRequest_lock &&
899 cur != VMOperationQueue_lock) ||
900 cur->rank() == Mutex::special) {
901 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
902 }
903 }
904 }
905
906 if (GCALotAtAllSafepoints) {
907 // We could enter a safepoint here and thus have a gc
908 InterfaceSupport::check_gc_alot();
909 }
910 #endif
911 }
912 #endif
913
914 bool Thread::is_in_stack(address adr) const {
915 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
916 address end = os::current_stack_pointer();
917 // Allow non Java threads to call this without stack_base
918 if (_stack_base == NULL) return true;
919 if (stack_base() >= adr && adr >= end) return true;
920
921 return false;
922 }
923
924 bool Thread::is_in_usable_stack(address adr) const {
925 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
926 size_t usable_stack_size = _stack_size - stack_guard_size;
927
928 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
929 }
930
931
932 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
933 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
934 // used for compilation in the future. If that change is made, the need for these methods
935 // should be revisited, and they should be removed if possible.
936
937 bool Thread::is_lock_owned(address adr) const {
938 return on_local_stack(adr);
939 }
940
941 bool Thread::set_as_starting_thread() {
942 // NOTE: this must be called inside the main thread.
943 return os::create_main_thread((JavaThread*)this);
944 }
945
946 static void initialize_class(Symbol* class_name, TRAPS) {
947 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
948 InstanceKlass::cast(klass)->initialize(CHECK);
949 }
950
951
952 // Creates the initial ThreadGroup
953 static Handle create_initial_thread_group(TRAPS) {
954 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
955 InstanceKlass* ik = InstanceKlass::cast(k);
956
957 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
958 {
959 JavaValue result(T_VOID);
960 JavaCalls::call_special(&result,
961 system_instance,
962 ik,
963 vmSymbols::object_initializer_name(),
964 vmSymbols::void_method_signature(),
965 CHECK_NH);
966 }
967 Universe::set_system_thread_group(system_instance());
968
969 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
970 {
971 JavaValue result(T_VOID);
972 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
973 JavaCalls::call_special(&result,
974 main_instance,
975 ik,
976 vmSymbols::object_initializer_name(),
977 vmSymbols::threadgroup_string_void_signature(),
978 system_instance,
979 string,
980 CHECK_NH);
981 }
982 return main_instance;
983 }
984
985 // Creates the initial Thread
986 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
987 TRAPS) {
988 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
989 InstanceKlass* ik = InstanceKlass::cast(k);
990 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
991
992 java_lang_Thread::set_thread(thread_oop(), thread);
993 java_lang_Thread::set_priority(thread_oop(), NormPriority);
994 thread->set_threadObj(thread_oop());
995
996 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
997
998 JavaValue result(T_VOID);
999 JavaCalls::call_special(&result, thread_oop,
1000 ik,
1001 vmSymbols::object_initializer_name(),
1002 vmSymbols::threadgroup_string_void_signature(),
1003 thread_group,
1004 string,
1005 CHECK_NULL);
1006 return thread_oop();
1007 }
1008
1009 char java_runtime_name[128] = "";
1010 char java_runtime_version[128] = "";
1011
1012 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1013 static const char* get_java_runtime_name(TRAPS) {
1014 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1015 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1016 fieldDescriptor fd;
1017 bool found = k != NULL &&
1018 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1019 vmSymbols::string_signature(), &fd);
1020 if (found) {
1021 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1022 if (name_oop == NULL) {
1023 return NULL;
1024 }
1025 const char* name = java_lang_String::as_utf8_string(name_oop,
1026 java_runtime_name,
1027 sizeof(java_runtime_name));
1028 return name;
1029 } else {
1030 return NULL;
1031 }
1032 }
1033
1034 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1035 static const char* get_java_runtime_version(TRAPS) {
1036 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1037 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1038 fieldDescriptor fd;
1039 bool found = k != NULL &&
1040 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1041 vmSymbols::string_signature(), &fd);
1042 if (found) {
1043 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1044 if (name_oop == NULL) {
1045 return NULL;
1046 }
1047 const char* name = java_lang_String::as_utf8_string(name_oop,
1048 java_runtime_version,
1049 sizeof(java_runtime_version));
1050 return name;
1051 } else {
1052 return NULL;
1053 }
1054 }
1055
1056 // General purpose hook into Java code, run once when the VM is initialized.
1057 // The Java library method itself may be changed independently from the VM.
1058 static void call_postVMInitHook(TRAPS) {
1059 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1060 if (klass != NULL) {
1061 JavaValue result(T_VOID);
1062 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1063 vmSymbols::void_method_signature(),
1064 CHECK);
1065 }
1066 }
1067
1068 static void reset_vm_info_property(TRAPS) {
1069 // the vm info string
1070 ResourceMark rm(THREAD);
1071 const char *vm_info = VM_Version::vm_info_string();
1072
1073 // java.lang.System class
1074 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1075
1076 // setProperty arguments
1077 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1078 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1079
1080 // return value
1081 JavaValue r(T_OBJECT);
1082
1083 // public static String setProperty(String key, String value);
1084 JavaCalls::call_static(&r,
1085 klass,
1086 vmSymbols::setProperty_name(),
1087 vmSymbols::string_string_string_signature(),
1088 key_str,
1089 value_str,
1090 CHECK);
1091 }
1092
1093
1094 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1095 bool daemon, TRAPS) {
1096 assert(thread_group.not_null(), "thread group should be specified");
1097 assert(threadObj() == NULL, "should only create Java thread object once");
1098
1099 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1100 InstanceKlass* ik = InstanceKlass::cast(k);
1101 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1102
1103 java_lang_Thread::set_thread(thread_oop(), this);
1104 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1105 set_threadObj(thread_oop());
1106
1107 JavaValue result(T_VOID);
1108 if (thread_name != NULL) {
1109 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1110 // Thread gets assigned specified name and null target
1111 JavaCalls::call_special(&result,
1112 thread_oop,
1113 ik,
1114 vmSymbols::object_initializer_name(),
1115 vmSymbols::threadgroup_string_void_signature(),
1116 thread_group, // Argument 1
1117 name, // Argument 2
1118 THREAD);
1119 } else {
1120 // Thread gets assigned name "Thread-nnn" and null target
1121 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1122 JavaCalls::call_special(&result,
1123 thread_oop,
1124 ik,
1125 vmSymbols::object_initializer_name(),
1126 vmSymbols::threadgroup_runnable_void_signature(),
1127 thread_group, // Argument 1
1128 Handle(), // Argument 2
1129 THREAD);
1130 }
1131
1132
1133 if (daemon) {
1134 java_lang_Thread::set_daemon(thread_oop());
1135 }
1136
1137 if (HAS_PENDING_EXCEPTION) {
1138 return;
1139 }
1140
1141 Klass* group = SystemDictionary::ThreadGroup_klass();
1142 Handle threadObj(THREAD, this->threadObj());
1143
1144 JavaCalls::call_special(&result,
1145 thread_group,
1146 group,
1147 vmSymbols::add_method_name(),
1148 vmSymbols::thread_void_signature(),
1149 threadObj, // Arg 1
1150 THREAD);
1151 }
1152
1153 // NamedThread -- non-JavaThread subclasses with multiple
1154 // uniquely named instances should derive from this.
1155 NamedThread::NamedThread() : Thread() {
1156 _name = NULL;
1157 _processed_thread = NULL;
1158 _gc_id = GCId::undefined();
1159 }
1160
1161 NamedThread::~NamedThread() {
1162 if (_name != NULL) {
1163 FREE_C_HEAP_ARRAY(char, _name);
1164 _name = NULL;
1165 }
1166 }
1167
1168 void NamedThread::set_name(const char* format, ...) {
1169 guarantee(_name == NULL, "Only get to set name once.");
1170 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1171 guarantee(_name != NULL, "alloc failure");
1172 va_list ap;
1173 va_start(ap, format);
1174 jio_vsnprintf(_name, max_name_len, format, ap);
1175 va_end(ap);
1176 }
1177
1178 void NamedThread::initialize_named_thread() {
1179 set_native_thread_name(name());
1180 }
1181
1182 void NamedThread::print_on(outputStream* st) const {
1183 st->print("\"%s\" ", name());
1184 Thread::print_on(st);
1185 st->cr();
1186 }
1187
1188
1189 // ======= WatcherThread ========
1190
1191 // The watcher thread exists to simulate timer interrupts. It should
1192 // be replaced by an abstraction over whatever native support for
1193 // timer interrupts exists on the platform.
1194
1195 WatcherThread* WatcherThread::_watcher_thread = NULL;
1196 bool WatcherThread::_startable = false;
1197 volatile bool WatcherThread::_should_terminate = false;
1198
1199 WatcherThread::WatcherThread() : Thread() {
1200 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1201 if (os::create_thread(this, os::watcher_thread)) {
1202 _watcher_thread = this;
1203
1204 // Set the watcher thread to the highest OS priority which should not be
1205 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1206 // is created. The only normal thread using this priority is the reference
1207 // handler thread, which runs for very short intervals only.
1208 // If the VMThread's priority is not lower than the WatcherThread profiling
1209 // will be inaccurate.
1210 os::set_priority(this, MaxPriority);
1211 if (!DisableStartThread) {
1212 os::start_thread(this);
1213 }
1214 }
1215 }
1216
1217 int WatcherThread::sleep() const {
1218 // The WatcherThread does not participate in the safepoint protocol
1219 // for the PeriodicTask_lock because it is not a JavaThread.
1220 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1221
1222 if (_should_terminate) {
1223 // check for termination before we do any housekeeping or wait
1224 return 0; // we did not sleep.
1225 }
1226
1227 // remaining will be zero if there are no tasks,
1228 // causing the WatcherThread to sleep until a task is
1229 // enrolled
1230 int remaining = PeriodicTask::time_to_wait();
1231 int time_slept = 0;
1232
1233 // we expect this to timeout - we only ever get unparked when
1234 // we should terminate or when a new task has been enrolled
1235 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1236
1237 jlong time_before_loop = os::javaTimeNanos();
1238
1239 while (true) {
1240 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1241 remaining);
1242 jlong now = os::javaTimeNanos();
1243
1244 if (remaining == 0) {
1245 // if we didn't have any tasks we could have waited for a long time
1246 // consider the time_slept zero and reset time_before_loop
1247 time_slept = 0;
1248 time_before_loop = now;
1249 } else {
1250 // need to recalculate since we might have new tasks in _tasks
1251 time_slept = (int) ((now - time_before_loop) / 1000000);
1252 }
1253
1254 // Change to task list or spurious wakeup of some kind
1255 if (timedout || _should_terminate) {
1256 break;
1257 }
1258
1259 remaining = PeriodicTask::time_to_wait();
1260 if (remaining == 0) {
1261 // Last task was just disenrolled so loop around and wait until
1262 // another task gets enrolled
1263 continue;
1264 }
1265
1266 remaining -= time_slept;
1267 if (remaining <= 0) {
1268 break;
1269 }
1270 }
1271
1272 return time_slept;
1273 }
1274
1275 void WatcherThread::run() {
1276 assert(this == watcher_thread(), "just checking");
1277
1278 this->record_stack_base_and_size();
1279 this->set_native_thread_name(this->name());
1280 this->set_active_handles(JNIHandleBlock::allocate_block());
1281 while (true) {
1282 assert(watcher_thread() == Thread::current(), "thread consistency check");
1283 assert(watcher_thread() == this, "thread consistency check");
1284
1285 // Calculate how long it'll be until the next PeriodicTask work
1286 // should be done, and sleep that amount of time.
1287 int time_waited = sleep();
1288
1289 if (VMError::is_error_reported()) {
1290 // A fatal error has happened, the error handler(VMError::report_and_die)
1291 // should abort JVM after creating an error log file. However in some
1292 // rare cases, the error handler itself might deadlock. Here periodically
1293 // check for error reporting timeouts, and if it happens, just proceed to
1294 // abort the VM.
1295
1296 // This code is in WatcherThread because WatcherThread wakes up
1297 // periodically so the fatal error handler doesn't need to do anything;
1298 // also because the WatcherThread is less likely to crash than other
1299 // threads.
1300
1301 for (;;) {
1302 // Note: we use naked sleep in this loop because we want to avoid using
1303 // any kind of VM infrastructure which may be broken at this point.
1304 if (VMError::check_timeout()) {
1305 // We hit error reporting timeout. Error reporting was interrupted and
1306 // will be wrapping things up now (closing files etc). Give it some more
1307 // time, then quit the VM.
1308 os::naked_short_sleep(200);
1309 // Print a message to stderr.
1310 fdStream err(defaultStream::output_fd());
1311 err.print_raw_cr("# [ timer expired, abort... ]");
1312 // skip atexit/vm_exit/vm_abort hooks
1313 os::die();
1314 }
1315
1316 // Wait a second, then recheck for timeout.
1317 os::naked_short_sleep(999);
1318 }
1319 }
1320
1321 if (_should_terminate) {
1322 // check for termination before posting the next tick
1323 break;
1324 }
1325
1326 PeriodicTask::real_time_tick(time_waited);
1327 }
1328
1329 // Signal that it is terminated
1330 {
1331 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1332 _watcher_thread = NULL;
1333 Terminator_lock->notify();
1334 }
1335 }
1336
1337 void WatcherThread::start() {
1338 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1339
1340 if (watcher_thread() == NULL && _startable) {
1341 _should_terminate = false;
1342 // Create the single instance of WatcherThread
1343 new WatcherThread();
1344 }
1345 }
1346
1347 void WatcherThread::make_startable() {
1348 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1349 _startable = true;
1350 }
1351
1352 void WatcherThread::stop() {
1353 {
1354 // Follow normal safepoint aware lock enter protocol since the
1355 // WatcherThread is stopped by another JavaThread.
1356 MutexLocker ml(PeriodicTask_lock);
1357 _should_terminate = true;
1358
1359 WatcherThread* watcher = watcher_thread();
1360 if (watcher != NULL) {
1361 // unpark the WatcherThread so it can see that it should terminate
1362 watcher->unpark();
1363 }
1364 }
1365
1366 MutexLocker mu(Terminator_lock);
1367
1368 while (watcher_thread() != NULL) {
1369 // This wait should make safepoint checks, wait without a timeout,
1370 // and wait as a suspend-equivalent condition.
1371 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1372 Mutex::_as_suspend_equivalent_flag);
1373 }
1374 }
1375
1376 void WatcherThread::unpark() {
1377 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1378 PeriodicTask_lock->notify();
1379 }
1380
1381 void WatcherThread::print_on(outputStream* st) const {
1382 st->print("\"%s\" ", name());
1383 Thread::print_on(st);
1384 st->cr();
1385 }
1386
1387 // ======= JavaThread ========
1388
1389 #if INCLUDE_JVMCI
1390
1391 jlong* JavaThread::_jvmci_old_thread_counters;
1392
1393 bool jvmci_counters_include(JavaThread* thread) {
1394 oop threadObj = thread->threadObj();
1395 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1396 }
1397
1398 void JavaThread::collect_counters(typeArrayOop array) {
1399 if (JVMCICounterSize > 0) {
1400 MutexLocker tl(Threads_lock);
1401 for (int i = 0; i < array->length(); i++) {
1402 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1403 }
1404 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1405 if (jvmci_counters_include(tp)) {
1406 for (int i = 0; i < array->length(); i++) {
1407 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1408 }
1409 }
1410 }
1411 }
1412 }
1413
1414 #endif // INCLUDE_JVMCI
1415
1416 // A JavaThread is a normal Java thread
1417
1418 void JavaThread::initialize() {
1419 // Initialize fields
1420
1421 set_saved_exception_pc(NULL);
1422 set_threadObj(NULL);
1423 _anchor.clear();
1424 set_entry_point(NULL);
1425 set_jni_functions(jni_functions());
1426 set_callee_target(NULL);
1427 set_vm_result(NULL);
1428 set_vm_result_2(NULL);
1429 set_vframe_array_head(NULL);
1430 set_vframe_array_last(NULL);
1431 set_deferred_locals(NULL);
1432 set_deopt_mark(NULL);
1433 set_deopt_compiled_method(NULL);
1434 clear_must_deopt_id();
1435 set_monitor_chunks(NULL);
1436 set_next(NULL);
1437 set_thread_state(_thread_new);
1438 _terminated = _not_terminated;
1439 _privileged_stack_top = NULL;
1440 _array_for_gc = NULL;
1441 _suspend_equivalent = false;
1442 _in_deopt_handler = 0;
1443 _doing_unsafe_access = false;
1444 _stack_guard_state = stack_guard_unused;
1445 #if INCLUDE_JVMCI
1446 _pending_monitorenter = false;
1447 _pending_deoptimization = -1;
1448 _pending_failed_speculation = NULL;
1449 _pending_transfer_to_interpreter = false;
1450 _adjusting_comp_level = false;
1451 _jvmci._alternate_call_target = NULL;
1452 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1453 if (JVMCICounterSize > 0) {
1454 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1455 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1456 } else {
1457 _jvmci_counters = NULL;
1458 }
1459 #endif // INCLUDE_JVMCI
1460 _reserved_stack_activation = NULL; // stack base not known yet
1461 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1462 _exception_pc = 0;
1463 _exception_handler_pc = 0;
1464 _is_method_handle_return = 0;
1465 _jvmti_thread_state= NULL;
1466 _should_post_on_exceptions_flag = JNI_FALSE;
1467 _jvmti_get_loaded_classes_closure = NULL;
1468 _interp_only_mode = 0;
1469 _special_runtime_exit_condition = _no_async_condition;
1470 _pending_async_exception = NULL;
1471 _thread_stat = NULL;
1472 _thread_stat = new ThreadStatistics();
1473 _blocked_on_compilation = false;
1474 _jni_active_critical = 0;
1475 _pending_jni_exception_check_fn = NULL;
1476 _do_not_unlock_if_synchronized = false;
1477 _cached_monitor_info = NULL;
1478 _parker = Parker::Allocate(this);
1479
1480 #ifndef PRODUCT
1481 _jmp_ring_index = 0;
1482 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1483 record_jump(NULL, NULL, NULL, 0);
1484 }
1485 #endif // PRODUCT
1486
1487 // Setup safepoint state info for this thread
1488 ThreadSafepointState::create(this);
1489
1490 debug_only(_java_call_counter = 0);
1491
1492 // JVMTI PopFrame support
1493 _popframe_condition = popframe_inactive;
1494 _popframe_preserved_args = NULL;
1495 _popframe_preserved_args_size = 0;
1496 _frames_to_pop_failed_realloc = 0;
1497
1498 pd_initialize();
1499 }
1500
1501 #if INCLUDE_ALL_GCS
1502 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1503 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1504 #endif // INCLUDE_ALL_GCS
1505
1506 JavaThread::JavaThread(bool is_attaching_via_jni) :
1507 Thread()
1508 #if INCLUDE_ALL_GCS
1509 , _satb_mark_queue(&_satb_mark_queue_set),
1510 _dirty_card_queue(&_dirty_card_queue_set)
1511 #endif // INCLUDE_ALL_GCS
1512 {
1513 initialize();
1514 if (is_attaching_via_jni) {
1515 _jni_attach_state = _attaching_via_jni;
1516 } else {
1517 _jni_attach_state = _not_attaching_via_jni;
1518 }
1519 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1520 }
1521
1522 bool JavaThread::reguard_stack(address cur_sp) {
1523 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1524 && _stack_guard_state != stack_guard_reserved_disabled) {
1525 return true; // Stack already guarded or guard pages not needed.
1526 }
1527
1528 if (register_stack_overflow()) {
1529 // For those architectures which have separate register and
1530 // memory stacks, we must check the register stack to see if
1531 // it has overflowed.
1532 return false;
1533 }
1534
1535 // Java code never executes within the yellow zone: the latter is only
1536 // there to provoke an exception during stack banging. If java code
1537 // is executing there, either StackShadowPages should be larger, or
1538 // some exception code in c1, c2 or the interpreter isn't unwinding
1539 // when it should.
1540 guarantee(cur_sp > stack_reserved_zone_base(),
1541 "not enough space to reguard - increase StackShadowPages");
1542 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1543 enable_stack_yellow_reserved_zone();
1544 if (reserved_stack_activation() != stack_base()) {
1545 set_reserved_stack_activation(stack_base());
1546 }
1547 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1548 set_reserved_stack_activation(stack_base());
1549 enable_stack_reserved_zone();
1550 }
1551 return true;
1552 }
1553
1554 bool JavaThread::reguard_stack(void) {
1555 return reguard_stack(os::current_stack_pointer());
1556 }
1557
1558
1559 void JavaThread::block_if_vm_exited() {
1560 if (_terminated == _vm_exited) {
1561 // _vm_exited is set at safepoint, and Threads_lock is never released
1562 // we will block here forever
1563 Threads_lock->lock_without_safepoint_check();
1564 ShouldNotReachHere();
1565 }
1566 }
1567
1568
1569 // Remove this ifdef when C1 is ported to the compiler interface.
1570 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1571 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1572
1573 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1574 Thread()
1575 #if INCLUDE_ALL_GCS
1576 , _satb_mark_queue(&_satb_mark_queue_set),
1577 _dirty_card_queue(&_dirty_card_queue_set)
1578 #endif // INCLUDE_ALL_GCS
1579 {
1580 initialize();
1581 _jni_attach_state = _not_attaching_via_jni;
1582 set_entry_point(entry_point);
1583 // Create the native thread itself.
1584 // %note runtime_23
1585 os::ThreadType thr_type = os::java_thread;
1586 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1587 os::java_thread;
1588 os::create_thread(this, thr_type, stack_sz);
1589 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1590 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1591 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1592 // the exception consists of creating the exception object & initializing it, initialization
1593 // will leave the VM via a JavaCall and then all locks must be unlocked).
1594 //
1595 // The thread is still suspended when we reach here. Thread must be explicit started
1596 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1597 // by calling Threads:add. The reason why this is not done here, is because the thread
1598 // object must be fully initialized (take a look at JVM_Start)
1599 }
1600
1601 JavaThread::~JavaThread() {
1602
1603 // JSR166 -- return the parker to the free list
1604 Parker::Release(_parker);
1605 _parker = NULL;
1606
1607 // Free any remaining previous UnrollBlock
1608 vframeArray* old_array = vframe_array_last();
1609
1610 if (old_array != NULL) {
1611 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1612 old_array->set_unroll_block(NULL);
1613 delete old_info;
1614 delete old_array;
1615 }
1616
1617 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1618 if (deferred != NULL) {
1619 // This can only happen if thread is destroyed before deoptimization occurs.
1620 assert(deferred->length() != 0, "empty array!");
1621 do {
1622 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1623 deferred->remove_at(0);
1624 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1625 delete dlv;
1626 } while (deferred->length() != 0);
1627 delete deferred;
1628 }
1629
1630 // All Java related clean up happens in exit
1631 ThreadSafepointState::destroy(this);
1632 if (_thread_stat != NULL) delete _thread_stat;
1633
1634 #if INCLUDE_JVMCI
1635 if (JVMCICounterSize > 0) {
1636 if (jvmci_counters_include(this)) {
1637 for (int i = 0; i < JVMCICounterSize; i++) {
1638 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1639 }
1640 }
1641 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1642 }
1643 #endif // INCLUDE_JVMCI
1644 }
1645
1646
1647 // The first routine called by a new Java thread
1648 void JavaThread::run() {
1649 // initialize thread-local alloc buffer related fields
1650 this->initialize_tlab();
1651
1652 // used to test validity of stack trace backs
1653 this->record_base_of_stack_pointer();
1654
1655 // Record real stack base and size.
1656 this->record_stack_base_and_size();
1657
1658 this->create_stack_guard_pages();
1659
1660 this->cache_global_variables();
1661
1662 // Thread is now sufficient initialized to be handled by the safepoint code as being
1663 // in the VM. Change thread state from _thread_new to _thread_in_vm
1664 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1665
1666 assert(JavaThread::current() == this, "sanity check");
1667 assert(!Thread::current()->owns_locks(), "sanity check");
1668
1669 DTRACE_THREAD_PROBE(start, this);
1670
1671 // This operation might block. We call that after all safepoint checks for a new thread has
1672 // been completed.
1673 this->set_active_handles(JNIHandleBlock::allocate_block());
1674
1675 if (JvmtiExport::should_post_thread_life()) {
1676 JvmtiExport::post_thread_start(this);
1677 }
1678
1679 EventThreadStart event;
1680 if (event.should_commit()) {
1681 event.set_thread(THREAD_TRACE_ID(this));
1682 event.commit();
1683 }
1684
1685 // We call another function to do the rest so we are sure that the stack addresses used
1686 // from there will be lower than the stack base just computed
1687 thread_main_inner();
1688
1689 // Note, thread is no longer valid at this point!
1690 }
1691
1692
1693 void JavaThread::thread_main_inner() {
1694 assert(JavaThread::current() == this, "sanity check");
1695 assert(this->threadObj() != NULL, "just checking");
1696
1697 // Execute thread entry point unless this thread has a pending exception
1698 // or has been stopped before starting.
1699 // Note: Due to JVM_StopThread we can have pending exceptions already!
1700 if (!this->has_pending_exception() &&
1701 !java_lang_Thread::is_stillborn(this->threadObj())) {
1702 {
1703 ResourceMark rm(this);
1704 this->set_native_thread_name(this->get_thread_name());
1705 }
1706 HandleMark hm(this);
1707 this->entry_point()(this, this);
1708 }
1709
1710 DTRACE_THREAD_PROBE(stop, this);
1711
1712 this->exit(false);
1713 delete this;
1714 }
1715
1716
1717 static void ensure_join(JavaThread* thread) {
1718 // We do not need to grap the Threads_lock, since we are operating on ourself.
1719 Handle threadObj(thread, thread->threadObj());
1720 assert(threadObj.not_null(), "java thread object must exist");
1721 ObjectLocker lock(threadObj, thread);
1722 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1723 thread->clear_pending_exception();
1724 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1725 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1726 // Clear the native thread instance - this makes isAlive return false and allows the join()
1727 // to complete once we've done the notify_all below
1728 java_lang_Thread::set_thread(threadObj(), NULL);
1729 lock.notify_all(thread);
1730 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1731 thread->clear_pending_exception();
1732 }
1733
1734
1735 // For any new cleanup additions, please check to see if they need to be applied to
1736 // cleanup_failed_attach_current_thread as well.
1737 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1738 assert(this == JavaThread::current(), "thread consistency check");
1739
1740 HandleMark hm(this);
1741 Handle uncaught_exception(this, this->pending_exception());
1742 this->clear_pending_exception();
1743 Handle threadObj(this, this->threadObj());
1744 assert(threadObj.not_null(), "Java thread object should be created");
1745
1746 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1747 {
1748 EXCEPTION_MARK;
1749
1750 CLEAR_PENDING_EXCEPTION;
1751 }
1752 if (!destroy_vm) {
1753 if (uncaught_exception.not_null()) {
1754 EXCEPTION_MARK;
1755 // Call method Thread.dispatchUncaughtException().
1756 Klass* thread_klass = SystemDictionary::Thread_klass();
1757 JavaValue result(T_VOID);
1758 JavaCalls::call_virtual(&result,
1759 threadObj, thread_klass,
1760 vmSymbols::dispatchUncaughtException_name(),
1761 vmSymbols::throwable_void_signature(),
1762 uncaught_exception,
1763 THREAD);
1764 if (HAS_PENDING_EXCEPTION) {
1765 ResourceMark rm(this);
1766 jio_fprintf(defaultStream::error_stream(),
1767 "\nException: %s thrown from the UncaughtExceptionHandler"
1768 " in thread \"%s\"\n",
1769 pending_exception()->klass()->external_name(),
1770 get_thread_name());
1771 CLEAR_PENDING_EXCEPTION;
1772 }
1773 }
1774
1775 // Called before the java thread exit since we want to read info
1776 // from java_lang_Thread object
1777 EventThreadEnd event;
1778 if (event.should_commit()) {
1779 event.set_thread(THREAD_TRACE_ID(this));
1780 event.commit();
1781 }
1782
1783 // Call after last event on thread
1784 EVENT_THREAD_EXIT(this);
1785
1786 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1787 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1788 // is deprecated anyhow.
1789 if (!is_Compiler_thread()) {
1790 int count = 3;
1791 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1792 EXCEPTION_MARK;
1793 JavaValue result(T_VOID);
1794 Klass* thread_klass = SystemDictionary::Thread_klass();
1795 JavaCalls::call_virtual(&result,
1796 threadObj, thread_klass,
1797 vmSymbols::exit_method_name(),
1798 vmSymbols::void_method_signature(),
1799 THREAD);
1800 CLEAR_PENDING_EXCEPTION;
1801 }
1802 }
1803 // notify JVMTI
1804 if (JvmtiExport::should_post_thread_life()) {
1805 JvmtiExport::post_thread_end(this);
1806 }
1807
1808 // We have notified the agents that we are exiting, before we go on,
1809 // we must check for a pending external suspend request and honor it
1810 // in order to not surprise the thread that made the suspend request.
1811 while (true) {
1812 {
1813 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1814 if (!is_external_suspend()) {
1815 set_terminated(_thread_exiting);
1816 ThreadService::current_thread_exiting(this);
1817 break;
1818 }
1819 // Implied else:
1820 // Things get a little tricky here. We have a pending external
1821 // suspend request, but we are holding the SR_lock so we
1822 // can't just self-suspend. So we temporarily drop the lock
1823 // and then self-suspend.
1824 }
1825
1826 ThreadBlockInVM tbivm(this);
1827 java_suspend_self();
1828
1829 // We're done with this suspend request, but we have to loop around
1830 // and check again. Eventually we will get SR_lock without a pending
1831 // external suspend request and will be able to mark ourselves as
1832 // exiting.
1833 }
1834 // no more external suspends are allowed at this point
1835 } else {
1836 // before_exit() has already posted JVMTI THREAD_END events
1837 }
1838
1839 // Notify waiters on thread object. This has to be done after exit() is called
1840 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1841 // group should have the destroyed bit set before waiters are notified).
1842 ensure_join(this);
1843 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1844
1845 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1846 // held by this thread must be released. The spec does not distinguish
1847 // between JNI-acquired and regular Java monitors. We can only see
1848 // regular Java monitors here if monitor enter-exit matching is broken.
1849 //
1850 // Optionally release any monitors for regular JavaThread exits. This
1851 // is provided as a work around for any bugs in monitor enter-exit
1852 // matching. This can be expensive so it is not enabled by default.
1853 //
1854 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1855 // ObjectSynchronizer::release_monitors_owned_by_thread().
1856 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1857 // Sanity check even though JNI DetachCurrentThread() would have
1858 // returned JNI_ERR if there was a Java frame. JavaThread exit
1859 // should be done executing Java code by the time we get here.
1860 assert(!this->has_last_Java_frame(),
1861 "should not have a Java frame when detaching or exiting");
1862 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1863 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1864 }
1865
1866 // These things needs to be done while we are still a Java Thread. Make sure that thread
1867 // is in a consistent state, in case GC happens
1868 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1869
1870 if (active_handles() != NULL) {
1871 JNIHandleBlock* block = active_handles();
1872 set_active_handles(NULL);
1873 JNIHandleBlock::release_block(block);
1874 }
1875
1876 if (free_handle_block() != NULL) {
1877 JNIHandleBlock* block = free_handle_block();
1878 set_free_handle_block(NULL);
1879 JNIHandleBlock::release_block(block);
1880 }
1881
1882 // These have to be removed while this is still a valid thread.
1883 remove_stack_guard_pages();
1884
1885 if (UseTLAB) {
1886 tlab().make_parsable(true); // retire TLAB
1887 }
1888
1889 if (JvmtiEnv::environments_might_exist()) {
1890 JvmtiExport::cleanup_thread(this);
1891 }
1892
1893 // We must flush any deferred card marks before removing a thread from
1894 // the list of active threads.
1895 Universe::heap()->flush_deferred_store_barrier(this);
1896 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1897
1898 #if INCLUDE_ALL_GCS
1899 // We must flush the G1-related buffers before removing a thread
1900 // from the list of active threads. We must do this after any deferred
1901 // card marks have been flushed (above) so that any entries that are
1902 // added to the thread's dirty card queue as a result are not lost.
1903 if (UseG1GC) {
1904 flush_barrier_queues();
1905 }
1906 #endif // INCLUDE_ALL_GCS
1907
1908 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1909 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1910 os::current_thread_id());
1911
1912 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1913 Threads::remove(this);
1914 }
1915
1916 #if INCLUDE_ALL_GCS
1917 // Flush G1-related queues.
1918 void JavaThread::flush_barrier_queues() {
1919 satb_mark_queue().flush();
1920 dirty_card_queue().flush();
1921 }
1922
1923 void JavaThread::initialize_queues() {
1924 assert(!SafepointSynchronize::is_at_safepoint(),
1925 "we should not be at a safepoint");
1926
1927 SATBMarkQueue& satb_queue = satb_mark_queue();
1928 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1929 // The SATB queue should have been constructed with its active
1930 // field set to false.
1931 assert(!satb_queue.is_active(), "SATB queue should not be active");
1932 assert(satb_queue.is_empty(), "SATB queue should be empty");
1933 // If we are creating the thread during a marking cycle, we should
1934 // set the active field of the SATB queue to true.
1935 if (satb_queue_set.is_active()) {
1936 satb_queue.set_active(true);
1937 }
1938
1939 DirtyCardQueue& dirty_queue = dirty_card_queue();
1940 // The dirty card queue should have been constructed with its
1941 // active field set to true.
1942 assert(dirty_queue.is_active(), "dirty card queue should be active");
1943 }
1944 #endif // INCLUDE_ALL_GCS
1945
1946 void JavaThread::cleanup_failed_attach_current_thread() {
1947 if (active_handles() != NULL) {
1948 JNIHandleBlock* block = active_handles();
1949 set_active_handles(NULL);
1950 JNIHandleBlock::release_block(block);
1951 }
1952
1953 if (free_handle_block() != NULL) {
1954 JNIHandleBlock* block = free_handle_block();
1955 set_free_handle_block(NULL);
1956 JNIHandleBlock::release_block(block);
1957 }
1958
1959 // These have to be removed while this is still a valid thread.
1960 remove_stack_guard_pages();
1961
1962 if (UseTLAB) {
1963 tlab().make_parsable(true); // retire TLAB, if any
1964 }
1965
1966 #if INCLUDE_ALL_GCS
1967 if (UseG1GC) {
1968 flush_barrier_queues();
1969 }
1970 #endif // INCLUDE_ALL_GCS
1971
1972 Threads::remove(this);
1973 delete this;
1974 }
1975
1976
1977
1978
1979 JavaThread* JavaThread::active() {
1980 Thread* thread = Thread::current();
1981 if (thread->is_Java_thread()) {
1982 return (JavaThread*) thread;
1983 } else {
1984 assert(thread->is_VM_thread(), "this must be a vm thread");
1985 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1986 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1987 assert(ret->is_Java_thread(), "must be a Java thread");
1988 return ret;
1989 }
1990 }
1991
1992 bool JavaThread::is_lock_owned(address adr) const {
1993 if (Thread::is_lock_owned(adr)) return true;
1994
1995 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1996 if (chunk->contains(adr)) return true;
1997 }
1998
1999 return false;
2000 }
2001
2002
2003 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2004 chunk->set_next(monitor_chunks());
2005 set_monitor_chunks(chunk);
2006 }
2007
2008 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2009 guarantee(monitor_chunks() != NULL, "must be non empty");
2010 if (monitor_chunks() == chunk) {
2011 set_monitor_chunks(chunk->next());
2012 } else {
2013 MonitorChunk* prev = monitor_chunks();
2014 while (prev->next() != chunk) prev = prev->next();
2015 prev->set_next(chunk->next());
2016 }
2017 }
2018
2019 // JVM support.
2020
2021 // Note: this function shouldn't block if it's called in
2022 // _thread_in_native_trans state (such as from
2023 // check_special_condition_for_native_trans()).
2024 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2025
2026 if (has_last_Java_frame() && has_async_condition()) {
2027 // If we are at a polling page safepoint (not a poll return)
2028 // then we must defer async exception because live registers
2029 // will be clobbered by the exception path. Poll return is
2030 // ok because the call we a returning from already collides
2031 // with exception handling registers and so there is no issue.
2032 // (The exception handling path kills call result registers but
2033 // this is ok since the exception kills the result anyway).
2034
2035 if (is_at_poll_safepoint()) {
2036 // if the code we are returning to has deoptimized we must defer
2037 // the exception otherwise live registers get clobbered on the
2038 // exception path before deoptimization is able to retrieve them.
2039 //
2040 RegisterMap map(this, false);
2041 frame caller_fr = last_frame().sender(&map);
2042 assert(caller_fr.is_compiled_frame(), "what?");
2043 if (caller_fr.is_deoptimized_frame()) {
2044 log_info(exceptions)("deferred async exception at compiled safepoint");
2045 return;
2046 }
2047 }
2048 }
2049
2050 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2051 if (condition == _no_async_condition) {
2052 // Conditions have changed since has_special_runtime_exit_condition()
2053 // was called:
2054 // - if we were here only because of an external suspend request,
2055 // then that was taken care of above (or cancelled) so we are done
2056 // - if we were here because of another async request, then it has
2057 // been cleared between the has_special_runtime_exit_condition()
2058 // and now so again we are done
2059 return;
2060 }
2061
2062 // Check for pending async. exception
2063 if (_pending_async_exception != NULL) {
2064 // Only overwrite an already pending exception, if it is not a threadDeath.
2065 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2066
2067 // We cannot call Exceptions::_throw(...) here because we cannot block
2068 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2069
2070 LogTarget(Info, exceptions) lt;
2071 if (lt.is_enabled()) {
2072 ResourceMark rm;
2073 LogStream ls(lt);
2074 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2075 if (has_last_Java_frame()) {
2076 frame f = last_frame();
2077 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2078 }
2079 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2080 }
2081 _pending_async_exception = NULL;
2082 clear_has_async_exception();
2083 }
2084 }
2085
2086 if (check_unsafe_error &&
2087 condition == _async_unsafe_access_error && !has_pending_exception()) {
2088 condition = _no_async_condition; // done
2089 switch (thread_state()) {
2090 case _thread_in_vm: {
2091 JavaThread* THREAD = this;
2092 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2093 }
2094 case _thread_in_native: {
2095 ThreadInVMfromNative tiv(this);
2096 JavaThread* THREAD = this;
2097 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2098 }
2099 case _thread_in_Java: {
2100 ThreadInVMfromJava tiv(this);
2101 JavaThread* THREAD = this;
2102 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2103 }
2104 default:
2105 ShouldNotReachHere();
2106 }
2107 }
2108
2109 assert(condition == _no_async_condition || has_pending_exception() ||
2110 (!check_unsafe_error && condition == _async_unsafe_access_error),
2111 "must have handled the async condition, if no exception");
2112 }
2113
2114 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2115 //
2116 // Check for pending external suspend. Internal suspend requests do
2117 // not use handle_special_runtime_exit_condition().
2118 // If JNIEnv proxies are allowed, don't self-suspend if the target
2119 // thread is not the current thread. In older versions of jdbx, jdbx
2120 // threads could call into the VM with another thread's JNIEnv so we
2121 // can be here operating on behalf of a suspended thread (4432884).
2122 bool do_self_suspend = is_external_suspend_with_lock();
2123 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2124 //
2125 // Because thread is external suspended the safepoint code will count
2126 // thread as at a safepoint. This can be odd because we can be here
2127 // as _thread_in_Java which would normally transition to _thread_blocked
2128 // at a safepoint. We would like to mark the thread as _thread_blocked
2129 // before calling java_suspend_self like all other callers of it but
2130 // we must then observe proper safepoint protocol. (We can't leave
2131 // _thread_blocked with a safepoint in progress). However we can be
2132 // here as _thread_in_native_trans so we can't use a normal transition
2133 // constructor/destructor pair because they assert on that type of
2134 // transition. We could do something like:
2135 //
2136 // JavaThreadState state = thread_state();
2137 // set_thread_state(_thread_in_vm);
2138 // {
2139 // ThreadBlockInVM tbivm(this);
2140 // java_suspend_self()
2141 // }
2142 // set_thread_state(_thread_in_vm_trans);
2143 // if (safepoint) block;
2144 // set_thread_state(state);
2145 //
2146 // but that is pretty messy. Instead we just go with the way the
2147 // code has worked before and note that this is the only path to
2148 // java_suspend_self that doesn't put the thread in _thread_blocked
2149 // mode.
2150
2151 frame_anchor()->make_walkable(this);
2152 java_suspend_self();
2153
2154 // We might be here for reasons in addition to the self-suspend request
2155 // so check for other async requests.
2156 }
2157
2158 if (check_asyncs) {
2159 check_and_handle_async_exceptions();
2160 }
2161 #if INCLUDE_TRACE
2162 if (is_trace_suspend()) {
2163 TRACE_SUSPEND_THREAD(this);
2164 }
2165 #endif
2166 }
2167
2168 void JavaThread::send_thread_stop(oop java_throwable) {
2169 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2170 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2171 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2172
2173 // Do not throw asynchronous exceptions against the compiler thread
2174 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2175 if (!can_call_java()) return;
2176
2177 {
2178 // Actually throw the Throwable against the target Thread - however
2179 // only if there is no thread death exception installed already.
2180 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2181 // If the topmost frame is a runtime stub, then we are calling into
2182 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2183 // must deoptimize the caller before continuing, as the compiled exception handler table
2184 // may not be valid
2185 if (has_last_Java_frame()) {
2186 frame f = last_frame();
2187 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2188 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2189 RegisterMap reg_map(this, UseBiasedLocking);
2190 frame compiled_frame = f.sender(®_map);
2191 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2192 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2193 }
2194 }
2195 }
2196
2197 // Set async. pending exception in thread.
2198 set_pending_async_exception(java_throwable);
2199
2200 if (log_is_enabled(Info, exceptions)) {
2201 ResourceMark rm;
2202 log_info(exceptions)("Pending Async. exception installed of type: %s",
2203 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2204 }
2205 // for AbortVMOnException flag
2206 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2207 }
2208 }
2209
2210
2211 // Interrupt thread so it will wake up from a potential wait()
2212 Thread::interrupt(this);
2213 }
2214
2215 // External suspension mechanism.
2216 //
2217 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2218 // to any VM_locks and it is at a transition
2219 // Self-suspension will happen on the transition out of the vm.
2220 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2221 //
2222 // Guarantees on return:
2223 // + Target thread will not execute any new bytecode (that's why we need to
2224 // force a safepoint)
2225 // + Target thread will not enter any new monitors
2226 //
2227 void JavaThread::java_suspend() {
2228 { MutexLocker mu(Threads_lock);
2229 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2230 return;
2231 }
2232 }
2233
2234 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2235 if (!is_external_suspend()) {
2236 // a racing resume has cancelled us; bail out now
2237 return;
2238 }
2239
2240 // suspend is done
2241 uint32_t debug_bits = 0;
2242 // Warning: is_ext_suspend_completed() may temporarily drop the
2243 // SR_lock to allow the thread to reach a stable thread state if
2244 // it is currently in a transient thread state.
2245 if (is_ext_suspend_completed(false /* !called_by_wait */,
2246 SuspendRetryDelay, &debug_bits)) {
2247 return;
2248 }
2249 }
2250
2251 VM_ThreadSuspend vm_suspend;
2252 VMThread::execute(&vm_suspend);
2253 }
2254
2255 // Part II of external suspension.
2256 // A JavaThread self suspends when it detects a pending external suspend
2257 // request. This is usually on transitions. It is also done in places
2258 // where continuing to the next transition would surprise the caller,
2259 // e.g., monitor entry.
2260 //
2261 // Returns the number of times that the thread self-suspended.
2262 //
2263 // Note: DO NOT call java_suspend_self() when you just want to block current
2264 // thread. java_suspend_self() is the second stage of cooperative
2265 // suspension for external suspend requests and should only be used
2266 // to complete an external suspend request.
2267 //
2268 int JavaThread::java_suspend_self() {
2269 int ret = 0;
2270
2271 // we are in the process of exiting so don't suspend
2272 if (is_exiting()) {
2273 clear_external_suspend();
2274 return ret;
2275 }
2276
2277 assert(_anchor.walkable() ||
2278 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2279 "must have walkable stack");
2280
2281 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2282
2283 assert(!this->is_ext_suspended(),
2284 "a thread trying to self-suspend should not already be suspended");
2285
2286 if (this->is_suspend_equivalent()) {
2287 // If we are self-suspending as a result of the lifting of a
2288 // suspend equivalent condition, then the suspend_equivalent
2289 // flag is not cleared until we set the ext_suspended flag so
2290 // that wait_for_ext_suspend_completion() returns consistent
2291 // results.
2292 this->clear_suspend_equivalent();
2293 }
2294
2295 // A racing resume may have cancelled us before we grabbed SR_lock
2296 // above. Or another external suspend request could be waiting for us
2297 // by the time we return from SR_lock()->wait(). The thread
2298 // that requested the suspension may already be trying to walk our
2299 // stack and if we return now, we can change the stack out from under
2300 // it. This would be a "bad thing (TM)" and cause the stack walker
2301 // to crash. We stay self-suspended until there are no more pending
2302 // external suspend requests.
2303 while (is_external_suspend()) {
2304 ret++;
2305 this->set_ext_suspended();
2306
2307 // _ext_suspended flag is cleared by java_resume()
2308 while (is_ext_suspended()) {
2309 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2310 }
2311 }
2312
2313 return ret;
2314 }
2315
2316 #ifdef ASSERT
2317 // verify the JavaThread has not yet been published in the Threads::list, and
2318 // hence doesn't need protection from concurrent access at this stage
2319 void JavaThread::verify_not_published() {
2320 if (!Threads_lock->owned_by_self()) {
2321 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2322 assert(!Threads::includes(this),
2323 "java thread shouldn't have been published yet!");
2324 } else {
2325 assert(!Threads::includes(this),
2326 "java thread shouldn't have been published yet!");
2327 }
2328 }
2329 #endif
2330
2331 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2332 // progress or when _suspend_flags is non-zero.
2333 // Current thread needs to self-suspend if there is a suspend request and/or
2334 // block if a safepoint is in progress.
2335 // Async exception ISN'T checked.
2336 // Note only the ThreadInVMfromNative transition can call this function
2337 // directly and when thread state is _thread_in_native_trans
2338 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2339 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2340
2341 JavaThread *curJT = JavaThread::current();
2342 bool do_self_suspend = thread->is_external_suspend();
2343
2344 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2345
2346 // If JNIEnv proxies are allowed, don't self-suspend if the target
2347 // thread is not the current thread. In older versions of jdbx, jdbx
2348 // threads could call into the VM with another thread's JNIEnv so we
2349 // can be here operating on behalf of a suspended thread (4432884).
2350 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2351 JavaThreadState state = thread->thread_state();
2352
2353 // We mark this thread_blocked state as a suspend-equivalent so
2354 // that a caller to is_ext_suspend_completed() won't be confused.
2355 // The suspend-equivalent state is cleared by java_suspend_self().
2356 thread->set_suspend_equivalent();
2357
2358 // If the safepoint code sees the _thread_in_native_trans state, it will
2359 // wait until the thread changes to other thread state. There is no
2360 // guarantee on how soon we can obtain the SR_lock and complete the
2361 // self-suspend request. It would be a bad idea to let safepoint wait for
2362 // too long. Temporarily change the state to _thread_blocked to
2363 // let the VM thread know that this thread is ready for GC. The problem
2364 // of changing thread state is that safepoint could happen just after
2365 // java_suspend_self() returns after being resumed, and VM thread will
2366 // see the _thread_blocked state. We must check for safepoint
2367 // after restoring the state and make sure we won't leave while a safepoint
2368 // is in progress.
2369 thread->set_thread_state(_thread_blocked);
2370 thread->java_suspend_self();
2371 thread->set_thread_state(state);
2372
2373 InterfaceSupport::serialize_thread_state_with_handler(thread);
2374 }
2375
2376 SafepointMechanism::block_if_requested(curJT);
2377
2378 if (thread->is_deopt_suspend()) {
2379 thread->clear_deopt_suspend();
2380 RegisterMap map(thread, false);
2381 frame f = thread->last_frame();
2382 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2383 f = f.sender(&map);
2384 }
2385 if (f.id() == thread->must_deopt_id()) {
2386 thread->clear_must_deopt_id();
2387 f.deoptimize(thread);
2388 } else {
2389 fatal("missed deoptimization!");
2390 }
2391 }
2392 #if INCLUDE_TRACE
2393 if (thread->is_trace_suspend()) {
2394 TRACE_SUSPEND_THREAD(thread);
2395 }
2396 #endif
2397 }
2398
2399 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2400 // progress or when _suspend_flags is non-zero.
2401 // Current thread needs to self-suspend if there is a suspend request and/or
2402 // block if a safepoint is in progress.
2403 // Also check for pending async exception (not including unsafe access error).
2404 // Note only the native==>VM/Java barriers can call this function and when
2405 // thread state is _thread_in_native_trans.
2406 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2407 check_safepoint_and_suspend_for_native_trans(thread);
2408
2409 if (thread->has_async_exception()) {
2410 // We are in _thread_in_native_trans state, don't handle unsafe
2411 // access error since that may block.
2412 thread->check_and_handle_async_exceptions(false);
2413 }
2414 }
2415
2416 // This is a variant of the normal
2417 // check_special_condition_for_native_trans with slightly different
2418 // semantics for use by critical native wrappers. It does all the
2419 // normal checks but also performs the transition back into
2420 // thread_in_Java state. This is required so that critical natives
2421 // can potentially block and perform a GC if they are the last thread
2422 // exiting the GCLocker.
2423 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2424 check_special_condition_for_native_trans(thread);
2425
2426 // Finish the transition
2427 thread->set_thread_state(_thread_in_Java);
2428
2429 if (thread->do_critical_native_unlock()) {
2430 ThreadInVMfromJavaNoAsyncException tiv(thread);
2431 GCLocker::unlock_critical(thread);
2432 thread->clear_critical_native_unlock();
2433 }
2434 }
2435
2436 // We need to guarantee the Threads_lock here, since resumes are not
2437 // allowed during safepoint synchronization
2438 // Can only resume from an external suspension
2439 void JavaThread::java_resume() {
2440 assert_locked_or_safepoint(Threads_lock);
2441
2442 // Sanity check: thread is gone, has started exiting or the thread
2443 // was not externally suspended.
2444 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2445 return;
2446 }
2447
2448 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2449
2450 clear_external_suspend();
2451
2452 if (is_ext_suspended()) {
2453 clear_ext_suspended();
2454 SR_lock()->notify_all();
2455 }
2456 }
2457
2458 size_t JavaThread::_stack_red_zone_size = 0;
2459 size_t JavaThread::_stack_yellow_zone_size = 0;
2460 size_t JavaThread::_stack_reserved_zone_size = 0;
2461 size_t JavaThread::_stack_shadow_zone_size = 0;
2462
2463 void JavaThread::create_stack_guard_pages() {
2464 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2465 address low_addr = stack_end();
2466 size_t len = stack_guard_zone_size();
2467
2468 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2469 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2470
2471 int must_commit = os::must_commit_stack_guard_pages();
2472 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2473
2474 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2475 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2476 return;
2477 }
2478
2479 if (os::guard_memory((char *) low_addr, len)) {
2480 _stack_guard_state = stack_guard_enabled;
2481 } else {
2482 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2483 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2484 if (os::uncommit_memory((char *) low_addr, len)) {
2485 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2486 }
2487 return;
2488 }
2489
2490 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2491 PTR_FORMAT "-" PTR_FORMAT ".",
2492 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2493 }
2494
2495 void JavaThread::remove_stack_guard_pages() {
2496 assert(Thread::current() == this, "from different thread");
2497 if (_stack_guard_state == stack_guard_unused) return;
2498 address low_addr = stack_end();
2499 size_t len = stack_guard_zone_size();
2500
2501 if (os::must_commit_stack_guard_pages()) {
2502 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2503 _stack_guard_state = stack_guard_unused;
2504 } else {
2505 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2506 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2507 return;
2508 }
2509 } else {
2510 if (_stack_guard_state == stack_guard_unused) return;
2511 if (os::unguard_memory((char *) low_addr, len)) {
2512 _stack_guard_state = stack_guard_unused;
2513 } else {
2514 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2515 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2516 return;
2517 }
2518 }
2519
2520 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2521 PTR_FORMAT "-" PTR_FORMAT ".",
2522 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2523 }
2524
2525 void JavaThread::enable_stack_reserved_zone() {
2526 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2527 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2528
2529 // The base notation is from the stack's point of view, growing downward.
2530 // We need to adjust it to work correctly with guard_memory()
2531 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2532
2533 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2534 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2535
2536 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2537 _stack_guard_state = stack_guard_enabled;
2538 } else {
2539 warning("Attempt to guard stack reserved zone failed.");
2540 }
2541 enable_register_stack_guard();
2542 }
2543
2544 void JavaThread::disable_stack_reserved_zone() {
2545 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2546 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2547
2548 // Simply return if called for a thread that does not use guard pages.
2549 if (_stack_guard_state == stack_guard_unused) return;
2550
2551 // The base notation is from the stack's point of view, growing downward.
2552 // We need to adjust it to work correctly with guard_memory()
2553 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2554
2555 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2556 _stack_guard_state = stack_guard_reserved_disabled;
2557 } else {
2558 warning("Attempt to unguard stack reserved zone failed.");
2559 }
2560 disable_register_stack_guard();
2561 }
2562
2563 void JavaThread::enable_stack_yellow_reserved_zone() {
2564 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2565 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2566
2567 // The base notation is from the stacks point of view, growing downward.
2568 // We need to adjust it to work correctly with guard_memory()
2569 address base = stack_red_zone_base();
2570
2571 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2572 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2573
2574 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2575 _stack_guard_state = stack_guard_enabled;
2576 } else {
2577 warning("Attempt to guard stack yellow zone failed.");
2578 }
2579 enable_register_stack_guard();
2580 }
2581
2582 void JavaThread::disable_stack_yellow_reserved_zone() {
2583 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2584 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2585
2586 // Simply return if called for a thread that does not use guard pages.
2587 if (_stack_guard_state == stack_guard_unused) return;
2588
2589 // The base notation is from the stacks point of view, growing downward.
2590 // We need to adjust it to work correctly with guard_memory()
2591 address base = stack_red_zone_base();
2592
2593 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2594 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2595 } else {
2596 warning("Attempt to unguard stack yellow zone failed.");
2597 }
2598 disable_register_stack_guard();
2599 }
2600
2601 void JavaThread::enable_stack_red_zone() {
2602 // The base notation is from the stacks point of view, growing downward.
2603 // We need to adjust it to work correctly with guard_memory()
2604 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2605 address base = stack_red_zone_base() - stack_red_zone_size();
2606
2607 guarantee(base < stack_base(), "Error calculating stack red zone");
2608 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2609
2610 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2611 warning("Attempt to guard stack red zone failed.");
2612 }
2613 }
2614
2615 void JavaThread::disable_stack_red_zone() {
2616 // The base notation is from the stacks point of view, growing downward.
2617 // We need to adjust it to work correctly with guard_memory()
2618 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2619 address base = stack_red_zone_base() - stack_red_zone_size();
2620 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2621 warning("Attempt to unguard stack red zone failed.");
2622 }
2623 }
2624
2625 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2626 // ignore is there is no stack
2627 if (!has_last_Java_frame()) return;
2628 // traverse the stack frames. Starts from top frame.
2629 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2630 frame* fr = fst.current();
2631 f(fr, fst.register_map());
2632 }
2633 }
2634
2635
2636 #ifndef PRODUCT
2637 // Deoptimization
2638 // Function for testing deoptimization
2639 void JavaThread::deoptimize() {
2640 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2641 StackFrameStream fst(this, UseBiasedLocking);
2642 bool deopt = false; // Dump stack only if a deopt actually happens.
2643 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2644 // Iterate over all frames in the thread and deoptimize
2645 for (; !fst.is_done(); fst.next()) {
2646 if (fst.current()->can_be_deoptimized()) {
2647
2648 if (only_at) {
2649 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2650 // consists of comma or carriage return separated numbers so
2651 // search for the current bci in that string.
2652 address pc = fst.current()->pc();
2653 nmethod* nm = (nmethod*) fst.current()->cb();
2654 ScopeDesc* sd = nm->scope_desc_at(pc);
2655 char buffer[8];
2656 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2657 size_t len = strlen(buffer);
2658 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2659 while (found != NULL) {
2660 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2661 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2662 // Check that the bci found is bracketed by terminators.
2663 break;
2664 }
2665 found = strstr(found + 1, buffer);
2666 }
2667 if (!found) {
2668 continue;
2669 }
2670 }
2671
2672 if (DebugDeoptimization && !deopt) {
2673 deopt = true; // One-time only print before deopt
2674 tty->print_cr("[BEFORE Deoptimization]");
2675 trace_frames();
2676 trace_stack();
2677 }
2678 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2679 }
2680 }
2681
2682 if (DebugDeoptimization && deopt) {
2683 tty->print_cr("[AFTER Deoptimization]");
2684 trace_frames();
2685 }
2686 }
2687
2688
2689 // Make zombies
2690 void JavaThread::make_zombies() {
2691 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2692 if (fst.current()->can_be_deoptimized()) {
2693 // it is a Java nmethod
2694 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2695 nm->make_not_entrant();
2696 }
2697 }
2698 }
2699 #endif // PRODUCT
2700
2701
2702 void JavaThread::deoptimized_wrt_marked_nmethods() {
2703 if (!has_last_Java_frame()) return;
2704 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2705 StackFrameStream fst(this, UseBiasedLocking);
2706 for (; !fst.is_done(); fst.next()) {
2707 if (fst.current()->should_be_deoptimized()) {
2708 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2709 }
2710 }
2711 }
2712
2713
2714 // If the caller is a NamedThread, then remember, in the current scope,
2715 // the given JavaThread in its _processed_thread field.
2716 class RememberProcessedThread: public StackObj {
2717 NamedThread* _cur_thr;
2718 public:
2719 RememberProcessedThread(JavaThread* jthr) {
2720 Thread* thread = Thread::current();
2721 if (thread->is_Named_thread()) {
2722 _cur_thr = (NamedThread *)thread;
2723 _cur_thr->set_processed_thread(jthr);
2724 } else {
2725 _cur_thr = NULL;
2726 }
2727 }
2728
2729 ~RememberProcessedThread() {
2730 if (_cur_thr) {
2731 _cur_thr->set_processed_thread(NULL);
2732 }
2733 }
2734 };
2735
2736 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2737 // Verify that the deferred card marks have been flushed.
2738 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2739
2740 // Traverse the GCHandles
2741 Thread::oops_do(f, cf);
2742
2743 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2744
2745 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2746 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2747
2748 if (has_last_Java_frame()) {
2749 // Record JavaThread to GC thread
2750 RememberProcessedThread rpt(this);
2751
2752 // Traverse the privileged stack
2753 if (_privileged_stack_top != NULL) {
2754 _privileged_stack_top->oops_do(f);
2755 }
2756
2757 // traverse the registered growable array
2758 if (_array_for_gc != NULL) {
2759 for (int index = 0; index < _array_for_gc->length(); index++) {
2760 f->do_oop(_array_for_gc->adr_at(index));
2761 }
2762 }
2763
2764 // Traverse the monitor chunks
2765 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2766 chunk->oops_do(f);
2767 }
2768
2769 // Traverse the execution stack
2770 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2771 fst.current()->oops_do(f, cf, fst.register_map());
2772 }
2773 }
2774
2775 // callee_target is never live across a gc point so NULL it here should
2776 // it still contain a methdOop.
2777
2778 set_callee_target(NULL);
2779
2780 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2781 // If we have deferred set_locals there might be oops waiting to be
2782 // written
2783 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2784 if (list != NULL) {
2785 for (int i = 0; i < list->length(); i++) {
2786 list->at(i)->oops_do(f);
2787 }
2788 }
2789
2790 // Traverse instance variables at the end since the GC may be moving things
2791 // around using this function
2792 f->do_oop((oop*) &_threadObj);
2793 f->do_oop((oop*) &_vm_result);
2794 f->do_oop((oop*) &_exception_oop);
2795 f->do_oop((oop*) &_pending_async_exception);
2796
2797 if (jvmti_thread_state() != NULL) {
2798 jvmti_thread_state()->oops_do(f);
2799 }
2800 }
2801
2802 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2803 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2804 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2805
2806 if (has_last_Java_frame()) {
2807 // Traverse the execution stack
2808 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2809 fst.current()->nmethods_do(cf);
2810 }
2811 }
2812 }
2813
2814 void JavaThread::metadata_do(void f(Metadata*)) {
2815 if (has_last_Java_frame()) {
2816 // Traverse the execution stack to call f() on the methods in the stack
2817 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2818 fst.current()->metadata_do(f);
2819 }
2820 } else if (is_Compiler_thread()) {
2821 // need to walk ciMetadata in current compile tasks to keep alive.
2822 CompilerThread* ct = (CompilerThread*)this;
2823 if (ct->env() != NULL) {
2824 ct->env()->metadata_do(f);
2825 }
2826 if (ct->task() != NULL) {
2827 ct->task()->metadata_do(f);
2828 }
2829 }
2830 }
2831
2832 // Printing
2833 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2834 switch (_thread_state) {
2835 case _thread_uninitialized: return "_thread_uninitialized";
2836 case _thread_new: return "_thread_new";
2837 case _thread_new_trans: return "_thread_new_trans";
2838 case _thread_in_native: return "_thread_in_native";
2839 case _thread_in_native_trans: return "_thread_in_native_trans";
2840 case _thread_in_vm: return "_thread_in_vm";
2841 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2842 case _thread_in_Java: return "_thread_in_Java";
2843 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2844 case _thread_blocked: return "_thread_blocked";
2845 case _thread_blocked_trans: return "_thread_blocked_trans";
2846 default: return "unknown thread state";
2847 }
2848 }
2849
2850 #ifndef PRODUCT
2851 void JavaThread::print_thread_state_on(outputStream *st) const {
2852 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2853 };
2854 void JavaThread::print_thread_state() const {
2855 print_thread_state_on(tty);
2856 }
2857 #endif // PRODUCT
2858
2859 // Called by Threads::print() for VM_PrintThreads operation
2860 void JavaThread::print_on(outputStream *st) const {
2861 st->print_raw("\"");
2862 st->print_raw(get_thread_name());
2863 st->print_raw("\" ");
2864 oop thread_oop = threadObj();
2865 if (thread_oop != NULL) {
2866 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2867 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2868 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2869 }
2870 Thread::print_on(st);
2871 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2872 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2873 if (thread_oop != NULL) {
2874 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2875 }
2876 #ifndef PRODUCT
2877 print_thread_state_on(st);
2878 _safepoint_state->print_on(st);
2879 #endif // PRODUCT
2880 if (is_Compiler_thread()) {
2881 CompilerThread* ct = (CompilerThread*)this;
2882 if (ct->task() != NULL) {
2883 st->print(" Compiling: ");
2884 ct->task()->print(st, NULL, true, false);
2885 } else {
2886 st->print(" No compile task");
2887 }
2888 st->cr();
2889 }
2890 }
2891
2892 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2893 st->print("%s", get_thread_name_string(buf, buflen));
2894 }
2895
2896 // Called by fatal error handler. The difference between this and
2897 // JavaThread::print() is that we can't grab lock or allocate memory.
2898 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2899 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2900 oop thread_obj = threadObj();
2901 if (thread_obj != NULL) {
2902 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2903 }
2904 st->print(" [");
2905 st->print("%s", _get_thread_state_name(_thread_state));
2906 if (osthread()) {
2907 st->print(", id=%d", osthread()->thread_id());
2908 }
2909 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2910 p2i(stack_end()), p2i(stack_base()));
2911 st->print("]");
2912 return;
2913 }
2914
2915 // Verification
2916
2917 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2918
2919 void JavaThread::verify() {
2920 // Verify oops in the thread.
2921 oops_do(&VerifyOopClosure::verify_oop, NULL);
2922
2923 // Verify the stack frames.
2924 frames_do(frame_verify);
2925 }
2926
2927 // CR 6300358 (sub-CR 2137150)
2928 // Most callers of this method assume that it can't return NULL but a
2929 // thread may not have a name whilst it is in the process of attaching to
2930 // the VM - see CR 6412693, and there are places where a JavaThread can be
2931 // seen prior to having it's threadObj set (eg JNI attaching threads and
2932 // if vm exit occurs during initialization). These cases can all be accounted
2933 // for such that this method never returns NULL.
2934 const char* JavaThread::get_thread_name() const {
2935 #ifdef ASSERT
2936 // early safepoints can hit while current thread does not yet have TLS
2937 if (!SafepointSynchronize::is_at_safepoint()) {
2938 Thread *cur = Thread::current();
2939 if (!(cur->is_Java_thread() && cur == this)) {
2940 // Current JavaThreads are allowed to get their own name without
2941 // the Threads_lock.
2942 assert_locked_or_safepoint(Threads_lock);
2943 }
2944 }
2945 #endif // ASSERT
2946 return get_thread_name_string();
2947 }
2948
2949 // Returns a non-NULL representation of this thread's name, or a suitable
2950 // descriptive string if there is no set name
2951 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2952 const char* name_str;
2953 oop thread_obj = threadObj();
2954 if (thread_obj != NULL) {
2955 oop name = java_lang_Thread::name(thread_obj);
2956 if (name != NULL) {
2957 if (buf == NULL) {
2958 name_str = java_lang_String::as_utf8_string(name);
2959 } else {
2960 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2961 }
2962 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2963 name_str = "<no-name - thread is attaching>";
2964 } else {
2965 name_str = Thread::name();
2966 }
2967 } else {
2968 name_str = Thread::name();
2969 }
2970 assert(name_str != NULL, "unexpected NULL thread name");
2971 return name_str;
2972 }
2973
2974
2975 const char* JavaThread::get_threadgroup_name() const {
2976 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2977 oop thread_obj = threadObj();
2978 if (thread_obj != NULL) {
2979 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2980 if (thread_group != NULL) {
2981 // ThreadGroup.name can be null
2982 return java_lang_ThreadGroup::name(thread_group);
2983 }
2984 }
2985 return NULL;
2986 }
2987
2988 const char* JavaThread::get_parent_name() const {
2989 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2990 oop thread_obj = threadObj();
2991 if (thread_obj != NULL) {
2992 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2993 if (thread_group != NULL) {
2994 oop parent = java_lang_ThreadGroup::parent(thread_group);
2995 if (parent != NULL) {
2996 // ThreadGroup.name can be null
2997 return java_lang_ThreadGroup::name(parent);
2998 }
2999 }
3000 }
3001 return NULL;
3002 }
3003
3004 ThreadPriority JavaThread::java_priority() const {
3005 oop thr_oop = threadObj();
3006 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3007 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3008 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3009 return priority;
3010 }
3011
3012 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3013
3014 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3015 // Link Java Thread object <-> C++ Thread
3016
3017 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3018 // and put it into a new Handle. The Handle "thread_oop" can then
3019 // be used to pass the C++ thread object to other methods.
3020
3021 // Set the Java level thread object (jthread) field of the
3022 // new thread (a JavaThread *) to C++ thread object using the
3023 // "thread_oop" handle.
3024
3025 // Set the thread field (a JavaThread *) of the
3026 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3027
3028 Handle thread_oop(Thread::current(),
3029 JNIHandles::resolve_non_null(jni_thread));
3030 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3031 "must be initialized");
3032 set_threadObj(thread_oop());
3033 java_lang_Thread::set_thread(thread_oop(), this);
3034
3035 if (prio == NoPriority) {
3036 prio = java_lang_Thread::priority(thread_oop());
3037 assert(prio != NoPriority, "A valid priority should be present");
3038 }
3039
3040 // Push the Java priority down to the native thread; needs Threads_lock
3041 Thread::set_priority(this, prio);
3042
3043 prepare_ext();
3044
3045 // Add the new thread to the Threads list and set it in motion.
3046 // We must have threads lock in order to call Threads::add.
3047 // It is crucial that we do not block before the thread is
3048 // added to the Threads list for if a GC happens, then the java_thread oop
3049 // will not be visited by GC.
3050 Threads::add(this);
3051 }
3052
3053 oop JavaThread::current_park_blocker() {
3054 // Support for JSR-166 locks
3055 oop thread_oop = threadObj();
3056 if (thread_oop != NULL &&
3057 JDK_Version::current().supports_thread_park_blocker()) {
3058 return java_lang_Thread::park_blocker(thread_oop);
3059 }
3060 return NULL;
3061 }
3062
3063
3064 void JavaThread::print_stack_on(outputStream* st) {
3065 if (!has_last_Java_frame()) return;
3066 ResourceMark rm;
3067 HandleMark hm;
3068
3069 RegisterMap reg_map(this);
3070 vframe* start_vf = last_java_vframe(®_map);
3071 int count = 0;
3072 for (vframe* f = start_vf; f; f = f->sender()) {
3073 if (f->is_java_frame()) {
3074 javaVFrame* jvf = javaVFrame::cast(f);
3075 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3076
3077 // Print out lock information
3078 if (JavaMonitorsInStackTrace) {
3079 jvf->print_lock_info_on(st, count);
3080 }
3081 } else {
3082 // Ignore non-Java frames
3083 }
3084
3085 // Bail-out case for too deep stacks
3086 count++;
3087 if (MaxJavaStackTraceDepth == count) return;
3088 }
3089 }
3090
3091
3092 // JVMTI PopFrame support
3093 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3094 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3095 if (in_bytes(size_in_bytes) != 0) {
3096 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3097 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3098 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3099 }
3100 }
3101
3102 void* JavaThread::popframe_preserved_args() {
3103 return _popframe_preserved_args;
3104 }
3105
3106 ByteSize JavaThread::popframe_preserved_args_size() {
3107 return in_ByteSize(_popframe_preserved_args_size);
3108 }
3109
3110 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3111 int sz = in_bytes(popframe_preserved_args_size());
3112 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3113 return in_WordSize(sz / wordSize);
3114 }
3115
3116 void JavaThread::popframe_free_preserved_args() {
3117 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3118 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3119 _popframe_preserved_args = NULL;
3120 _popframe_preserved_args_size = 0;
3121 }
3122
3123 #ifndef PRODUCT
3124
3125 void JavaThread::trace_frames() {
3126 tty->print_cr("[Describe stack]");
3127 int frame_no = 1;
3128 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3129 tty->print(" %d. ", frame_no++);
3130 fst.current()->print_value_on(tty, this);
3131 tty->cr();
3132 }
3133 }
3134
3135 class PrintAndVerifyOopClosure: public OopClosure {
3136 protected:
3137 template <class T> inline void do_oop_work(T* p) {
3138 oop obj = oopDesc::load_decode_heap_oop(p);
3139 if (obj == NULL) return;
3140 tty->print(INTPTR_FORMAT ": ", p2i(p));
3141 if (oopDesc::is_oop_or_null(obj)) {
3142 if (obj->is_objArray()) {
3143 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3144 } else {
3145 obj->print();
3146 }
3147 } else {
3148 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3149 }
3150 tty->cr();
3151 }
3152 public:
3153 virtual void do_oop(oop* p) { do_oop_work(p); }
3154 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3155 };
3156
3157
3158 static void oops_print(frame* f, const RegisterMap *map) {
3159 PrintAndVerifyOopClosure print;
3160 f->print_value();
3161 f->oops_do(&print, NULL, (RegisterMap*)map);
3162 }
3163
3164 // Print our all the locations that contain oops and whether they are
3165 // valid or not. This useful when trying to find the oldest frame
3166 // where an oop has gone bad since the frame walk is from youngest to
3167 // oldest.
3168 void JavaThread::trace_oops() {
3169 tty->print_cr("[Trace oops]");
3170 frames_do(oops_print);
3171 }
3172
3173
3174 #ifdef ASSERT
3175 // Print or validate the layout of stack frames
3176 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3177 ResourceMark rm;
3178 PRESERVE_EXCEPTION_MARK;
3179 FrameValues values;
3180 int frame_no = 0;
3181 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3182 fst.current()->describe(values, ++frame_no);
3183 if (depth == frame_no) break;
3184 }
3185 if (validate_only) {
3186 values.validate();
3187 } else {
3188 tty->print_cr("[Describe stack layout]");
3189 values.print(this);
3190 }
3191 }
3192 #endif
3193
3194 void JavaThread::trace_stack_from(vframe* start_vf) {
3195 ResourceMark rm;
3196 int vframe_no = 1;
3197 for (vframe* f = start_vf; f; f = f->sender()) {
3198 if (f->is_java_frame()) {
3199 javaVFrame::cast(f)->print_activation(vframe_no++);
3200 } else {
3201 f->print();
3202 }
3203 if (vframe_no > StackPrintLimit) {
3204 tty->print_cr("...<more frames>...");
3205 return;
3206 }
3207 }
3208 }
3209
3210
3211 void JavaThread::trace_stack() {
3212 if (!has_last_Java_frame()) return;
3213 ResourceMark rm;
3214 HandleMark hm;
3215 RegisterMap reg_map(this);
3216 trace_stack_from(last_java_vframe(®_map));
3217 }
3218
3219
3220 #endif // PRODUCT
3221
3222
3223 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3224 assert(reg_map != NULL, "a map must be given");
3225 frame f = last_frame();
3226 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3227 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3228 }
3229 return NULL;
3230 }
3231
3232
3233 Klass* JavaThread::security_get_caller_class(int depth) {
3234 vframeStream vfst(this);
3235 vfst.security_get_caller_frame(depth);
3236 if (!vfst.at_end()) {
3237 return vfst.method()->method_holder();
3238 }
3239 return NULL;
3240 }
3241
3242 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3243 assert(thread->is_Compiler_thread(), "must be compiler thread");
3244 CompileBroker::compiler_thread_loop();
3245 }
3246
3247 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3248 NMethodSweeper::sweeper_loop();
3249 }
3250
3251 // Create a CompilerThread
3252 CompilerThread::CompilerThread(CompileQueue* queue,
3253 CompilerCounters* counters)
3254 : JavaThread(&compiler_thread_entry) {
3255 _env = NULL;
3256 _log = NULL;
3257 _task = NULL;
3258 _queue = queue;
3259 _counters = counters;
3260 _buffer_blob = NULL;
3261 _compiler = NULL;
3262
3263 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3264 resource_area()->bias_to(mtCompiler);
3265
3266 #ifndef PRODUCT
3267 _ideal_graph_printer = NULL;
3268 #endif
3269 }
3270
3271 bool CompilerThread::can_call_java() const {
3272 return _compiler != NULL && _compiler->is_jvmci();
3273 }
3274
3275 // Create sweeper thread
3276 CodeCacheSweeperThread::CodeCacheSweeperThread()
3277 : JavaThread(&sweeper_thread_entry) {
3278 _scanned_compiled_method = NULL;
3279 }
3280
3281 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3282 JavaThread::oops_do(f, cf);
3283 if (_scanned_compiled_method != NULL && cf != NULL) {
3284 // Safepoints can occur when the sweeper is scanning an nmethod so
3285 // process it here to make sure it isn't unloaded in the middle of
3286 // a scan.
3287 cf->do_code_blob(_scanned_compiled_method);
3288 }
3289 }
3290
3291 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3292 JavaThread::nmethods_do(cf);
3293 if (_scanned_compiled_method != NULL && cf != NULL) {
3294 // Safepoints can occur when the sweeper is scanning an nmethod so
3295 // process it here to make sure it isn't unloaded in the middle of
3296 // a scan.
3297 cf->do_code_blob(_scanned_compiled_method);
3298 }
3299 }
3300
3301
3302 // ======= Threads ========
3303
3304 // The Threads class links together all active threads, and provides
3305 // operations over all threads. It is protected by its own Mutex
3306 // lock, which is also used in other contexts to protect thread
3307 // operations from having the thread being operated on from exiting
3308 // and going away unexpectedly (e.g., safepoint synchronization)
3309
3310 JavaThread* Threads::_thread_list = NULL;
3311 int Threads::_number_of_threads = 0;
3312 int Threads::_number_of_non_daemon_threads = 0;
3313 int Threads::_return_code = 0;
3314 int Threads::_thread_claim_parity = 0;
3315 size_t JavaThread::_stack_size_at_create = 0;
3316 #ifdef ASSERT
3317 bool Threads::_vm_complete = false;
3318 #endif
3319
3320 // All JavaThreads
3321 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3322
3323 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3324 void Threads::threads_do(ThreadClosure* tc) {
3325 assert_locked_or_safepoint(Threads_lock);
3326 // ALL_JAVA_THREADS iterates through all JavaThreads
3327 ALL_JAVA_THREADS(p) {
3328 tc->do_thread(p);
3329 }
3330 // Someday we could have a table or list of all non-JavaThreads.
3331 // For now, just manually iterate through them.
3332 tc->do_thread(VMThread::vm_thread());
3333 Universe::heap()->gc_threads_do(tc);
3334 WatcherThread *wt = WatcherThread::watcher_thread();
3335 // Strictly speaking, the following NULL check isn't sufficient to make sure
3336 // the data for WatcherThread is still valid upon being examined. However,
3337 // considering that WatchThread terminates when the VM is on the way to
3338 // exit at safepoint, the chance of the above is extremely small. The right
3339 // way to prevent termination of WatcherThread would be to acquire
3340 // Terminator_lock, but we can't do that without violating the lock rank
3341 // checking in some cases.
3342 if (wt != NULL) {
3343 tc->do_thread(wt);
3344 }
3345
3346 // If CompilerThreads ever become non-JavaThreads, add them here
3347 }
3348
3349 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3350 int cp = Threads::thread_claim_parity();
3351 ALL_JAVA_THREADS(p) {
3352 if (p->claim_oops_do(true, cp)) {
3353 tc->do_thread(p);
3354 }
3355 }
3356 // Thread claiming protocol requires us to claim the same interesting
3357 // threads on all paths. Notably, Threads::possibly_parallel_threads_do
3358 // claims all Java threads *and* the VMThread. To avoid breaking the
3359 // claiming protocol, we have to claim VMThread on this path too, even
3360 // if we do not apply the closure to the VMThread.
3361 VMThread* vmt = VMThread::vm_thread();
3362 (void)vmt->claim_oops_do(true, cp);
3363 }
3364
3365 // The system initialization in the library has three phases.
3366 //
3367 // Phase 1: java.lang.System class initialization
3368 // java.lang.System is a primordial class loaded and initialized
3369 // by the VM early during startup. java.lang.System.<clinit>
3370 // only does registerNatives and keeps the rest of the class
3371 // initialization work later until thread initialization completes.
3372 //
3373 // System.initPhase1 initializes the system properties, the static
3374 // fields in, out, and err. Set up java signal handlers, OS-specific
3375 // system settings, and thread group of the main thread.
3376 static void call_initPhase1(TRAPS) {
3377 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3378 JavaValue result(T_VOID);
3379 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3380 vmSymbols::void_method_signature(), CHECK);
3381 }
3382
3383 // Phase 2. Module system initialization
3384 // This will initialize the module system. Only java.base classes
3385 // can be loaded until phase 2 completes.
3386 //
3387 // Call System.initPhase2 after the compiler initialization and jsr292
3388 // classes get initialized because module initialization runs a lot of java
3389 // code, that for performance reasons, should be compiled. Also, this will
3390 // enable the startup code to use lambda and other language features in this
3391 // phase and onward.
3392 //
3393 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3394 static void call_initPhase2(TRAPS) {
3395 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3396
3397 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3398
3399 JavaValue result(T_INT);
3400 JavaCallArguments args;
3401 args.push_int(DisplayVMOutputToStderr);
3402 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3403 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3404 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3405 if (result.get_jint() != JNI_OK) {
3406 vm_exit_during_initialization(); // no message or exception
3407 }
3408
3409 universe_post_module_init();
3410 }
3411
3412 // Phase 3. final setup - set security manager, system class loader and TCCL
3413 //
3414 // This will instantiate and set the security manager, set the system class
3415 // loader as well as the thread context class loader. The security manager
3416 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3417 // other modules or the application's classpath.
3418 static void call_initPhase3(TRAPS) {
3419 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3420 JavaValue result(T_VOID);
3421 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3422 vmSymbols::void_method_signature(), CHECK);
3423 }
3424
3425 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3426 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3427
3428 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3429 create_vm_init_libraries();
3430 }
3431
3432 initialize_class(vmSymbols::java_lang_String(), CHECK);
3433
3434 // Inject CompactStrings value after the static initializers for String ran.
3435 java_lang_String::set_compact_strings(CompactStrings);
3436
3437 // Initialize java_lang.System (needed before creating the thread)
3438 initialize_class(vmSymbols::java_lang_System(), CHECK);
3439 // The VM creates & returns objects of this class. Make sure it's initialized.
3440 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3441 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3442 Handle thread_group = create_initial_thread_group(CHECK);
3443 Universe::set_main_thread_group(thread_group());
3444 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3445 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3446 main_thread->set_threadObj(thread_object);
3447 // Set thread status to running since main thread has
3448 // been started and running.
3449 java_lang_Thread::set_thread_status(thread_object,
3450 java_lang_Thread::RUNNABLE);
3451
3452 // The VM creates objects of this class.
3453 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3454
3455 // The VM preresolves methods to these classes. Make sure that they get initialized
3456 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3457 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3458
3459 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3460 call_initPhase1(CHECK);
3461
3462 // get the Java runtime name after java.lang.System is initialized
3463 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3464 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3465
3466 // an instance of OutOfMemory exception has been allocated earlier
3467 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3468 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3469 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3470 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3471 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3472 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3473 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3474 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3475 }
3476
3477 void Threads::initialize_jsr292_core_classes(TRAPS) {
3478 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3479
3480 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3481 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3482 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3483 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3484 }
3485
3486 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3487 extern void JDK_Version_init();
3488
3489 // Preinitialize version info.
3490 VM_Version::early_initialize();
3491
3492 // Check version
3493 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3494
3495 // Initialize library-based TLS
3496 ThreadLocalStorage::init();
3497
3498 // Initialize the output stream module
3499 ostream_init();
3500
3501 // Process java launcher properties.
3502 Arguments::process_sun_java_launcher_properties(args);
3503
3504 // Initialize the os module
3505 os::init();
3506
3507 // Record VM creation timing statistics
3508 TraceVmCreationTime create_vm_timer;
3509 create_vm_timer.start();
3510
3511 // Initialize system properties.
3512 Arguments::init_system_properties();
3513
3514 // So that JDK version can be used as a discriminator when parsing arguments
3515 JDK_Version_init();
3516
3517 // Update/Initialize System properties after JDK version number is known
3518 Arguments::init_version_specific_system_properties();
3519
3520 // Make sure to initialize log configuration *before* parsing arguments
3521 LogConfiguration::initialize(create_vm_timer.begin_time());
3522
3523 // Parse arguments
3524 jint parse_result = Arguments::parse(args);
3525 if (parse_result != JNI_OK) return parse_result;
3526
3527 os::init_before_ergo();
3528
3529 jint ergo_result = Arguments::apply_ergo();
3530 if (ergo_result != JNI_OK) return ergo_result;
3531
3532 // Final check of all ranges after ergonomics which may change values.
3533 if (!CommandLineFlagRangeList::check_ranges()) {
3534 return JNI_EINVAL;
3535 }
3536
3537 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3538 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3539 if (!constraint_result) {
3540 return JNI_EINVAL;
3541 }
3542
3543 CommandLineFlagWriteableList::mark_startup();
3544
3545 if (PauseAtStartup) {
3546 os::pause();
3547 }
3548
3549 HOTSPOT_VM_INIT_BEGIN();
3550
3551 // Timing (must come after argument parsing)
3552 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3553
3554 SafepointMechanism::initialize();
3555
3556 // Initialize the os module after parsing the args
3557 jint os_init_2_result = os::init_2();
3558 if (os_init_2_result != JNI_OK) return os_init_2_result;
3559
3560 jint adjust_after_os_result = Arguments::adjust_after_os();
3561 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3562
3563 // Initialize output stream logging
3564 ostream_init_log();
3565
3566 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3567 // Must be before create_vm_init_agents()
3568 if (Arguments::init_libraries_at_startup()) {
3569 convert_vm_init_libraries_to_agents();
3570 }
3571
3572 // Launch -agentlib/-agentpath and converted -Xrun agents
3573 if (Arguments::init_agents_at_startup()) {
3574 create_vm_init_agents();
3575 }
3576
3577 // Initialize Threads state
3578 _thread_list = NULL;
3579 _number_of_threads = 0;
3580 _number_of_non_daemon_threads = 0;
3581
3582 // Initialize global data structures and create system classes in heap
3583 vm_init_globals();
3584
3585 #if INCLUDE_JVMCI
3586 if (JVMCICounterSize > 0) {
3587 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3588 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3589 } else {
3590 JavaThread::_jvmci_old_thread_counters = NULL;
3591 }
3592 #endif // INCLUDE_JVMCI
3593
3594 // Attach the main thread to this os thread
3595 JavaThread* main_thread = new JavaThread();
3596 main_thread->set_thread_state(_thread_in_vm);
3597 main_thread->initialize_thread_current();
3598 // must do this before set_active_handles
3599 main_thread->record_stack_base_and_size();
3600 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3601
3602 if (!main_thread->set_as_starting_thread()) {
3603 vm_shutdown_during_initialization(
3604 "Failed necessary internal allocation. Out of swap space");
3605 delete main_thread;
3606 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3607 return JNI_ENOMEM;
3608 }
3609
3610 // Enable guard page *after* os::create_main_thread(), otherwise it would
3611 // crash Linux VM, see notes in os_linux.cpp.
3612 main_thread->create_stack_guard_pages();
3613
3614 // Initialize Java-Level synchronization subsystem
3615 ObjectMonitor::Initialize();
3616
3617 // Initialize global modules
3618 jint status = init_globals();
3619 if (status != JNI_OK) {
3620 delete main_thread;
3621 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3622 return status;
3623 }
3624
3625 if (TRACE_INITIALIZE() != JNI_OK) {
3626 vm_exit_during_initialization("Failed to initialize tracing backend");
3627 }
3628
3629 // Should be done after the heap is fully created
3630 main_thread->cache_global_variables();
3631
3632 HandleMark hm;
3633
3634 { MutexLocker mu(Threads_lock);
3635 Threads::add(main_thread);
3636 }
3637
3638 // Any JVMTI raw monitors entered in onload will transition into
3639 // real raw monitor. VM is setup enough here for raw monitor enter.
3640 JvmtiExport::transition_pending_onload_raw_monitors();
3641
3642 // Create the VMThread
3643 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3644
3645 VMThread::create();
3646 Thread* vmthread = VMThread::vm_thread();
3647
3648 if (!os::create_thread(vmthread, os::vm_thread)) {
3649 vm_exit_during_initialization("Cannot create VM thread. "
3650 "Out of system resources.");
3651 }
3652
3653 // Wait for the VM thread to become ready, and VMThread::run to initialize
3654 // Monitors can have spurious returns, must always check another state flag
3655 {
3656 MutexLocker ml(Notify_lock);
3657 os::start_thread(vmthread);
3658 while (vmthread->active_handles() == NULL) {
3659 Notify_lock->wait();
3660 }
3661 }
3662 }
3663
3664 assert(Universe::is_fully_initialized(), "not initialized");
3665 if (VerifyDuringStartup) {
3666 // Make sure we're starting with a clean slate.
3667 VM_Verify verify_op;
3668 VMThread::execute(&verify_op);
3669 }
3670
3671 Thread* THREAD = Thread::current();
3672
3673 // Always call even when there are not JVMTI environments yet, since environments
3674 // may be attached late and JVMTI must track phases of VM execution
3675 JvmtiExport::enter_early_start_phase();
3676
3677 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3678 JvmtiExport::post_early_vm_start();
3679
3680 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3681
3682 // We need this for ClassDataSharing - the initial vm.info property is set
3683 // with the default value of CDS "sharing" which may be reset through
3684 // command line options.
3685 reset_vm_info_property(CHECK_JNI_ERR);
3686
3687 quicken_jni_functions();
3688
3689 // No more stub generation allowed after that point.
3690 StubCodeDesc::freeze();
3691
3692 // Set flag that basic initialization has completed. Used by exceptions and various
3693 // debug stuff, that does not work until all basic classes have been initialized.
3694 set_init_completed();
3695
3696 LogConfiguration::post_initialize();
3697 Metaspace::post_initialize();
3698
3699 HOTSPOT_VM_INIT_END();
3700
3701 // record VM initialization completion time
3702 #if INCLUDE_MANAGEMENT
3703 Management::record_vm_init_completed();
3704 #endif // INCLUDE_MANAGEMENT
3705
3706 // Signal Dispatcher needs to be started before VMInit event is posted
3707 os::signal_init(CHECK_JNI_ERR);
3708
3709 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3710 if (!DisableAttachMechanism) {
3711 AttachListener::vm_start();
3712 if (StartAttachListener || AttachListener::init_at_startup()) {
3713 AttachListener::init();
3714 }
3715 }
3716
3717 // Launch -Xrun agents
3718 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3719 // back-end can launch with -Xdebug -Xrunjdwp.
3720 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3721 create_vm_init_libraries();
3722 }
3723
3724 if (CleanChunkPoolAsync) {
3725 Chunk::start_chunk_pool_cleaner_task();
3726 }
3727
3728 // initialize compiler(s)
3729 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3730 CompileBroker::compilation_init(CHECK_JNI_ERR);
3731 #endif
3732
3733 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3734 // It is done after compilers are initialized, because otherwise compilations of
3735 // signature polymorphic MH intrinsics can be missed
3736 // (see SystemDictionary::find_method_handle_intrinsic).
3737 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3738
3739 // This will initialize the module system. Only java.base classes can be
3740 // loaded until phase 2 completes
3741 call_initPhase2(CHECK_JNI_ERR);
3742
3743 // Always call even when there are not JVMTI environments yet, since environments
3744 // may be attached late and JVMTI must track phases of VM execution
3745 JvmtiExport::enter_start_phase();
3746
3747 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3748 JvmtiExport::post_vm_start();
3749
3750 // Final system initialization including security manager and system class loader
3751 call_initPhase3(CHECK_JNI_ERR);
3752
3753 // cache the system and platform class loaders
3754 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3755
3756 #if INCLUDE_JVMCI
3757 if (EnableJVMCI) {
3758 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3759 // The JVMCI Java initialization code will read this flag and
3760 // do the printing if it's set.
3761 bool init = JVMCIPrintProperties;
3762
3763 if (!init) {
3764 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3765 // compilations via JVMCI will not actually block until JVMCI is initialized.
3766 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3767 }
3768
3769 if (init) {
3770 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3771 }
3772 }
3773 #endif
3774
3775 // Always call even when there are not JVMTI environments yet, since environments
3776 // may be attached late and JVMTI must track phases of VM execution
3777 JvmtiExport::enter_live_phase();
3778
3779 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3780 JvmtiExport::post_vm_initialized();
3781
3782 if (TRACE_START() != JNI_OK) {
3783 vm_exit_during_initialization("Failed to start tracing backend.");
3784 }
3785
3786 #if INCLUDE_MANAGEMENT
3787 Management::initialize(THREAD);
3788
3789 if (HAS_PENDING_EXCEPTION) {
3790 // management agent fails to start possibly due to
3791 // configuration problem and is responsible for printing
3792 // stack trace if appropriate. Simply exit VM.
3793 vm_exit(1);
3794 }
3795 #endif // INCLUDE_MANAGEMENT
3796
3797 if (MemProfiling) MemProfiler::engage();
3798 StatSampler::engage();
3799 if (CheckJNICalls) JniPeriodicChecker::engage();
3800
3801 BiasedLocking::init();
3802
3803 #if INCLUDE_RTM_OPT
3804 RTMLockingCounters::init();
3805 #endif
3806
3807 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3808 call_postVMInitHook(THREAD);
3809 // The Java side of PostVMInitHook.run must deal with all
3810 // exceptions and provide means of diagnosis.
3811 if (HAS_PENDING_EXCEPTION) {
3812 CLEAR_PENDING_EXCEPTION;
3813 }
3814 }
3815
3816 {
3817 MutexLocker ml(PeriodicTask_lock);
3818 // Make sure the WatcherThread can be started by WatcherThread::start()
3819 // or by dynamic enrollment.
3820 WatcherThread::make_startable();
3821 // Start up the WatcherThread if there are any periodic tasks
3822 // NOTE: All PeriodicTasks should be registered by now. If they
3823 // aren't, late joiners might appear to start slowly (we might
3824 // take a while to process their first tick).
3825 if (PeriodicTask::num_tasks() > 0) {
3826 WatcherThread::start();
3827 }
3828 }
3829
3830 create_vm_timer.end();
3831 #ifdef ASSERT
3832 _vm_complete = true;
3833 #endif
3834
3835 if (DumpSharedSpaces) {
3836 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3837 ShouldNotReachHere();
3838 }
3839
3840 return JNI_OK;
3841 }
3842
3843 // type for the Agent_OnLoad and JVM_OnLoad entry points
3844 extern "C" {
3845 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3846 }
3847 // Find a command line agent library and return its entry point for
3848 // -agentlib: -agentpath: -Xrun
3849 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3850 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3851 const char *on_load_symbols[],
3852 size_t num_symbol_entries) {
3853 OnLoadEntry_t on_load_entry = NULL;
3854 void *library = NULL;
3855
3856 if (!agent->valid()) {
3857 char buffer[JVM_MAXPATHLEN];
3858 char ebuf[1024] = "";
3859 const char *name = agent->name();
3860 const char *msg = "Could not find agent library ";
3861
3862 // First check to see if agent is statically linked into executable
3863 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3864 library = agent->os_lib();
3865 } else if (agent->is_absolute_path()) {
3866 library = os::dll_load(name, ebuf, sizeof ebuf);
3867 if (library == NULL) {
3868 const char *sub_msg = " in absolute path, with error: ";
3869 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3870 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3871 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3872 // If we can't find the agent, exit.
3873 vm_exit_during_initialization(buf, NULL);
3874 FREE_C_HEAP_ARRAY(char, buf);
3875 }
3876 } else {
3877 // Try to load the agent from the standard dll directory
3878 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3879 name)) {
3880 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3881 }
3882 if (library == NULL) { // Try the library path directory.
3883 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
3884 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3885 }
3886 if (library == NULL) {
3887 const char *sub_msg = " on the library path, with error: ";
3888 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3889 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3890 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3891 // If we can't find the agent, exit.
3892 vm_exit_during_initialization(buf, NULL);
3893 FREE_C_HEAP_ARRAY(char, buf);
3894 }
3895 }
3896 }
3897 agent->set_os_lib(library);
3898 agent->set_valid();
3899 }
3900
3901 // Find the OnLoad function.
3902 on_load_entry =
3903 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3904 false,
3905 on_load_symbols,
3906 num_symbol_entries));
3907 return on_load_entry;
3908 }
3909
3910 // Find the JVM_OnLoad entry point
3911 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3912 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3913 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3914 }
3915
3916 // Find the Agent_OnLoad entry point
3917 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3918 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3919 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3920 }
3921
3922 // For backwards compatibility with -Xrun
3923 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3924 // treated like -agentpath:
3925 // Must be called before agent libraries are created
3926 void Threads::convert_vm_init_libraries_to_agents() {
3927 AgentLibrary* agent;
3928 AgentLibrary* next;
3929
3930 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3931 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3932 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3933
3934 // If there is an JVM_OnLoad function it will get called later,
3935 // otherwise see if there is an Agent_OnLoad
3936 if (on_load_entry == NULL) {
3937 on_load_entry = lookup_agent_on_load(agent);
3938 if (on_load_entry != NULL) {
3939 // switch it to the agent list -- so that Agent_OnLoad will be called,
3940 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3941 Arguments::convert_library_to_agent(agent);
3942 } else {
3943 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3944 }
3945 }
3946 }
3947 }
3948
3949 // Create agents for -agentlib: -agentpath: and converted -Xrun
3950 // Invokes Agent_OnLoad
3951 // Called very early -- before JavaThreads exist
3952 void Threads::create_vm_init_agents() {
3953 extern struct JavaVM_ main_vm;
3954 AgentLibrary* agent;
3955
3956 JvmtiExport::enter_onload_phase();
3957
3958 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3959 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3960
3961 if (on_load_entry != NULL) {
3962 // Invoke the Agent_OnLoad function
3963 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3964 if (err != JNI_OK) {
3965 vm_exit_during_initialization("agent library failed to init", agent->name());
3966 }
3967 } else {
3968 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3969 }
3970 }
3971 JvmtiExport::enter_primordial_phase();
3972 }
3973
3974 extern "C" {
3975 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3976 }
3977
3978 void Threads::shutdown_vm_agents() {
3979 // Send any Agent_OnUnload notifications
3980 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3981 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3982 extern struct JavaVM_ main_vm;
3983 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3984
3985 // Find the Agent_OnUnload function.
3986 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3987 os::find_agent_function(agent,
3988 false,
3989 on_unload_symbols,
3990 num_symbol_entries));
3991
3992 // Invoke the Agent_OnUnload function
3993 if (unload_entry != NULL) {
3994 JavaThread* thread = JavaThread::current();
3995 ThreadToNativeFromVM ttn(thread);
3996 HandleMark hm(thread);
3997 (*unload_entry)(&main_vm);
3998 }
3999 }
4000 }
4001
4002 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4003 // Invokes JVM_OnLoad
4004 void Threads::create_vm_init_libraries() {
4005 extern struct JavaVM_ main_vm;
4006 AgentLibrary* agent;
4007
4008 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4009 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4010
4011 if (on_load_entry != NULL) {
4012 // Invoke the JVM_OnLoad function
4013 JavaThread* thread = JavaThread::current();
4014 ThreadToNativeFromVM ttn(thread);
4015 HandleMark hm(thread);
4016 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4017 if (err != JNI_OK) {
4018 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4019 }
4020 } else {
4021 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4022 }
4023 }
4024 }
4025
4026 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4027 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4028
4029 JavaThread* java_thread = NULL;
4030 // Sequential search for now. Need to do better optimization later.
4031 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4032 oop tobj = thread->threadObj();
4033 if (!thread->is_exiting() &&
4034 tobj != NULL &&
4035 java_tid == java_lang_Thread::thread_id(tobj)) {
4036 java_thread = thread;
4037 break;
4038 }
4039 }
4040 return java_thread;
4041 }
4042
4043
4044 // Last thread running calls java.lang.Shutdown.shutdown()
4045 void JavaThread::invoke_shutdown_hooks() {
4046 HandleMark hm(this);
4047
4048 // We could get here with a pending exception, if so clear it now.
4049 if (this->has_pending_exception()) {
4050 this->clear_pending_exception();
4051 }
4052
4053 EXCEPTION_MARK;
4054 Klass* shutdown_klass =
4055 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4056 THREAD);
4057 if (shutdown_klass != NULL) {
4058 // SystemDictionary::resolve_or_null will return null if there was
4059 // an exception. If we cannot load the Shutdown class, just don't
4060 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4061 // and finalizers (if runFinalizersOnExit is set) won't be run.
4062 // Note that if a shutdown hook was registered or runFinalizersOnExit
4063 // was called, the Shutdown class would have already been loaded
4064 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4065 JavaValue result(T_VOID);
4066 JavaCalls::call_static(&result,
4067 shutdown_klass,
4068 vmSymbols::shutdown_method_name(),
4069 vmSymbols::void_method_signature(),
4070 THREAD);
4071 }
4072 CLEAR_PENDING_EXCEPTION;
4073 }
4074
4075 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4076 // the program falls off the end of main(). Another VM exit path is through
4077 // vm_exit() when the program calls System.exit() to return a value or when
4078 // there is a serious error in VM. The two shutdown paths are not exactly
4079 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4080 // and VM_Exit op at VM level.
4081 //
4082 // Shutdown sequence:
4083 // + Shutdown native memory tracking if it is on
4084 // + Wait until we are the last non-daemon thread to execute
4085 // <-- every thing is still working at this moment -->
4086 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4087 // shutdown hooks, run finalizers if finalization-on-exit
4088 // + Call before_exit(), prepare for VM exit
4089 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4090 // currently the only user of this mechanism is File.deleteOnExit())
4091 // > stop StatSampler, watcher thread, CMS threads,
4092 // post thread end and vm death events to JVMTI,
4093 // stop signal thread
4094 // + Call JavaThread::exit(), it will:
4095 // > release JNI handle blocks, remove stack guard pages
4096 // > remove this thread from Threads list
4097 // <-- no more Java code from this thread after this point -->
4098 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4099 // the compiler threads at safepoint
4100 // <-- do not use anything that could get blocked by Safepoint -->
4101 // + Disable tracing at JNI/JVM barriers
4102 // + Set _vm_exited flag for threads that are still running native code
4103 // + Delete this thread
4104 // + Call exit_globals()
4105 // > deletes tty
4106 // > deletes PerfMemory resources
4107 // + Return to caller
4108
4109 bool Threads::destroy_vm() {
4110 JavaThread* thread = JavaThread::current();
4111
4112 #ifdef ASSERT
4113 _vm_complete = false;
4114 #endif
4115 // Wait until we are the last non-daemon thread to execute
4116 { MutexLocker nu(Threads_lock);
4117 while (Threads::number_of_non_daemon_threads() > 1)
4118 // This wait should make safepoint checks, wait without a timeout,
4119 // and wait as a suspend-equivalent condition.
4120 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4121 Mutex::_as_suspend_equivalent_flag);
4122 }
4123
4124 // Hang forever on exit if we are reporting an error.
4125 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4126 os::infinite_sleep();
4127 }
4128 os::wait_for_keypress_at_exit();
4129
4130 // run Java level shutdown hooks
4131 thread->invoke_shutdown_hooks();
4132
4133 before_exit(thread);
4134
4135 thread->exit(true);
4136
4137 // Stop VM thread.
4138 {
4139 // 4945125 The vm thread comes to a safepoint during exit.
4140 // GC vm_operations can get caught at the safepoint, and the
4141 // heap is unparseable if they are caught. Grab the Heap_lock
4142 // to prevent this. The GC vm_operations will not be able to
4143 // queue until after the vm thread is dead. After this point,
4144 // we'll never emerge out of the safepoint before the VM exits.
4145
4146 MutexLocker ml(Heap_lock);
4147
4148 VMThread::wait_for_vm_thread_exit();
4149 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4150 VMThread::destroy();
4151 }
4152
4153 // clean up ideal graph printers
4154 #if defined(COMPILER2) && !defined(PRODUCT)
4155 IdealGraphPrinter::clean_up();
4156 #endif
4157
4158 // Now, all Java threads are gone except daemon threads. Daemon threads
4159 // running Java code or in VM are stopped by the Safepoint. However,
4160 // daemon threads executing native code are still running. But they
4161 // will be stopped at native=>Java/VM barriers. Note that we can't
4162 // simply kill or suspend them, as it is inherently deadlock-prone.
4163
4164 VM_Exit::set_vm_exited();
4165
4166 notify_vm_shutdown();
4167
4168 delete thread;
4169
4170 #if INCLUDE_JVMCI
4171 if (JVMCICounterSize > 0) {
4172 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4173 }
4174 #endif
4175
4176 // exit_globals() will delete tty
4177 exit_globals();
4178
4179 LogConfiguration::finalize();
4180
4181 return true;
4182 }
4183
4184
4185 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4186 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4187 return is_supported_jni_version(version);
4188 }
4189
4190
4191 jboolean Threads::is_supported_jni_version(jint version) {
4192 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4193 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4194 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4195 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4196 if (version == JNI_VERSION_9) return JNI_TRUE;
4197 if (version == JNI_VERSION_10) return JNI_TRUE;
4198 return JNI_FALSE;
4199 }
4200
4201
4202 void Threads::add(JavaThread* p, bool force_daemon) {
4203 // The threads lock must be owned at this point
4204 assert_locked_or_safepoint(Threads_lock);
4205
4206 // See the comment for this method in thread.hpp for its purpose and
4207 // why it is called here.
4208 p->initialize_queues();
4209 p->set_next(_thread_list);
4210 _thread_list = p;
4211 _number_of_threads++;
4212 oop threadObj = p->threadObj();
4213 bool daemon = true;
4214 // Bootstrapping problem: threadObj can be null for initial
4215 // JavaThread (or for threads attached via JNI)
4216 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4217 _number_of_non_daemon_threads++;
4218 daemon = false;
4219 }
4220
4221 ThreadService::add_thread(p, daemon);
4222
4223 // Possible GC point.
4224 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4225 }
4226
4227 void Threads::remove(JavaThread* p) {
4228
4229 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4230 ObjectSynchronizer::omFlush(p);
4231
4232 // Extra scope needed for Thread_lock, so we can check
4233 // that we do not remove thread without safepoint code notice
4234 { MutexLocker ml(Threads_lock);
4235
4236 assert(includes(p), "p must be present");
4237
4238 JavaThread* current = _thread_list;
4239 JavaThread* prev = NULL;
4240
4241 while (current != p) {
4242 prev = current;
4243 current = current->next();
4244 }
4245
4246 if (prev) {
4247 prev->set_next(current->next());
4248 } else {
4249 _thread_list = p->next();
4250 }
4251 _number_of_threads--;
4252 oop threadObj = p->threadObj();
4253 bool daemon = true;
4254 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4255 _number_of_non_daemon_threads--;
4256 daemon = false;
4257
4258 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4259 // on destroy_vm will wake up.
4260 if (number_of_non_daemon_threads() == 1) {
4261 Threads_lock->notify_all();
4262 }
4263 }
4264 ThreadService::remove_thread(p, daemon);
4265
4266 // Make sure that safepoint code disregard this thread. This is needed since
4267 // the thread might mess around with locks after this point. This can cause it
4268 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4269 // of this thread since it is removed from the queue.
4270 p->set_terminated_value();
4271 } // unlock Threads_lock
4272
4273 // Since Events::log uses a lock, we grab it outside the Threads_lock
4274 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4275 }
4276
4277 // Threads_lock must be held when this is called (or must be called during a safepoint)
4278 bool Threads::includes(JavaThread* p) {
4279 assert(Threads_lock->is_locked(), "sanity check");
4280 ALL_JAVA_THREADS(q) {
4281 if (q == p) {
4282 return true;
4283 }
4284 }
4285 return false;
4286 }
4287
4288 // Operations on the Threads list for GC. These are not explicitly locked,
4289 // but the garbage collector must provide a safe context for them to run.
4290 // In particular, these things should never be called when the Threads_lock
4291 // is held by some other thread. (Note: the Safepoint abstraction also
4292 // uses the Threads_lock to guarantee this property. It also makes sure that
4293 // all threads gets blocked when exiting or starting).
4294
4295 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4296 ALL_JAVA_THREADS(p) {
4297 p->oops_do(f, cf);
4298 }
4299 VMThread::vm_thread()->oops_do(f, cf);
4300 }
4301
4302 void Threads::change_thread_claim_parity() {
4303 // Set the new claim parity.
4304 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4305 "Not in range.");
4306 _thread_claim_parity++;
4307 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4308 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4309 "Not in range.");
4310 }
4311
4312 #ifdef ASSERT
4313 void Threads::assert_all_threads_claimed() {
4314 ALL_JAVA_THREADS(p) {
4315 const int thread_parity = p->oops_do_parity();
4316 assert((thread_parity == _thread_claim_parity),
4317 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4318 }
4319 VMThread* vmt = VMThread::vm_thread();
4320 const int thread_parity = vmt->oops_do_parity();
4321 assert((thread_parity == _thread_claim_parity),
4322 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4323 }
4324 #endif // ASSERT
4325
4326 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4327 int cp = Threads::thread_claim_parity();
4328 ALL_JAVA_THREADS(p) {
4329 if (p->claim_oops_do(is_par, cp)) {
4330 p->oops_do(f, cf);
4331 }
4332 }
4333 VMThread* vmt = VMThread::vm_thread();
4334 if (vmt->claim_oops_do(is_par, cp)) {
4335 vmt->oops_do(f, cf);
4336 }
4337 }
4338
4339 #if INCLUDE_ALL_GCS
4340 // Used by ParallelScavenge
4341 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4342 ALL_JAVA_THREADS(p) {
4343 q->enqueue(new ThreadRootsTask(p));
4344 }
4345 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4346 }
4347
4348 // Used by Parallel Old
4349 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4350 ALL_JAVA_THREADS(p) {
4351 q->enqueue(new ThreadRootsMarkingTask(p));
4352 }
4353 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4354 }
4355 #endif // INCLUDE_ALL_GCS
4356
4357 void Threads::nmethods_do(CodeBlobClosure* cf) {
4358 ALL_JAVA_THREADS(p) {
4359 // This is used by the code cache sweeper to mark nmethods that are active
4360 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4361 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4362 if(!p->is_Code_cache_sweeper_thread()) {
4363 p->nmethods_do(cf);
4364 }
4365 }
4366 }
4367
4368 void Threads::metadata_do(void f(Metadata*)) {
4369 ALL_JAVA_THREADS(p) {
4370 p->metadata_do(f);
4371 }
4372 }
4373
4374 class ThreadHandlesClosure : public ThreadClosure {
4375 void (*_f)(Metadata*);
4376 public:
4377 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4378 virtual void do_thread(Thread* thread) {
4379 thread->metadata_handles_do(_f);
4380 }
4381 };
4382
4383 void Threads::metadata_handles_do(void f(Metadata*)) {
4384 // Only walk the Handles in Thread.
4385 ThreadHandlesClosure handles_closure(f);
4386 threads_do(&handles_closure);
4387 }
4388
4389 void Threads::deoptimized_wrt_marked_nmethods() {
4390 ALL_JAVA_THREADS(p) {
4391 p->deoptimized_wrt_marked_nmethods();
4392 }
4393 }
4394
4395
4396 // Get count Java threads that are waiting to enter the specified monitor.
4397 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4398 address monitor,
4399 bool doLock) {
4400 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4401 "must grab Threads_lock or be at safepoint");
4402 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4403
4404 int i = 0;
4405 {
4406 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4407 ALL_JAVA_THREADS(p) {
4408 if (!p->can_call_java()) continue;
4409
4410 address pending = (address)p->current_pending_monitor();
4411 if (pending == monitor) { // found a match
4412 if (i < count) result->append(p); // save the first count matches
4413 i++;
4414 }
4415 }
4416 }
4417 return result;
4418 }
4419
4420
4421 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4422 bool doLock) {
4423 assert(doLock ||
4424 Threads_lock->owned_by_self() ||
4425 SafepointSynchronize::is_at_safepoint(),
4426 "must grab Threads_lock or be at safepoint");
4427
4428 // NULL owner means not locked so we can skip the search
4429 if (owner == NULL) return NULL;
4430
4431 {
4432 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4433 ALL_JAVA_THREADS(p) {
4434 // first, see if owner is the address of a Java thread
4435 if (owner == (address)p) return p;
4436 }
4437 }
4438 // Cannot assert on lack of success here since this function may be
4439 // used by code that is trying to report useful problem information
4440 // like deadlock detection.
4441 if (UseHeavyMonitors) return NULL;
4442
4443 // If we didn't find a matching Java thread and we didn't force use of
4444 // heavyweight monitors, then the owner is the stack address of the
4445 // Lock Word in the owning Java thread's stack.
4446 //
4447 JavaThread* the_owner = NULL;
4448 {
4449 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4450 ALL_JAVA_THREADS(q) {
4451 if (q->is_lock_owned(owner)) {
4452 the_owner = q;
4453 break;
4454 }
4455 }
4456 }
4457 // cannot assert on lack of success here; see above comment
4458 return the_owner;
4459 }
4460
4461 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4462 void Threads::print_on(outputStream* st, bool print_stacks,
4463 bool internal_format, bool print_concurrent_locks) {
4464 char buf[32];
4465 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4466
4467 st->print_cr("Full thread dump %s (%s %s):",
4468 Abstract_VM_Version::vm_name(),
4469 Abstract_VM_Version::vm_release(),
4470 Abstract_VM_Version::vm_info_string());
4471 st->cr();
4472
4473 #if INCLUDE_SERVICES
4474 // Dump concurrent locks
4475 ConcurrentLocksDump concurrent_locks;
4476 if (print_concurrent_locks) {
4477 concurrent_locks.dump_at_safepoint();
4478 }
4479 #endif // INCLUDE_SERVICES
4480
4481 ALL_JAVA_THREADS(p) {
4482 ResourceMark rm;
4483 p->print_on(st);
4484 if (print_stacks) {
4485 if (internal_format) {
4486 p->trace_stack();
4487 } else {
4488 p->print_stack_on(st);
4489 }
4490 }
4491 st->cr();
4492 #if INCLUDE_SERVICES
4493 if (print_concurrent_locks) {
4494 concurrent_locks.print_locks_on(p, st);
4495 }
4496 #endif // INCLUDE_SERVICES
4497 }
4498
4499 VMThread::vm_thread()->print_on(st);
4500 st->cr();
4501 Universe::heap()->print_gc_threads_on(st);
4502 WatcherThread* wt = WatcherThread::watcher_thread();
4503 if (wt != NULL) {
4504 wt->print_on(st);
4505 st->cr();
4506 }
4507 st->flush();
4508 }
4509
4510 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4511 int buflen, bool* found_current) {
4512 if (this_thread != NULL) {
4513 bool is_current = (current == this_thread);
4514 *found_current = *found_current || is_current;
4515 st->print("%s", is_current ? "=>" : " ");
4516
4517 st->print(PTR_FORMAT, p2i(this_thread));
4518 st->print(" ");
4519 this_thread->print_on_error(st, buf, buflen);
4520 st->cr();
4521 }
4522 }
4523
4524 class PrintOnErrorClosure : public ThreadClosure {
4525 outputStream* _st;
4526 Thread* _current;
4527 char* _buf;
4528 int _buflen;
4529 bool* _found_current;
4530 public:
4531 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4532 int buflen, bool* found_current) :
4533 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4534
4535 virtual void do_thread(Thread* thread) {
4536 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4537 }
4538 };
4539
4540 // Threads::print_on_error() is called by fatal error handler. It's possible
4541 // that VM is not at safepoint and/or current thread is inside signal handler.
4542 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4543 // memory (even in resource area), it might deadlock the error handler.
4544 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4545 int buflen) {
4546 bool found_current = false;
4547 st->print_cr("Java Threads: ( => current thread )");
4548 ALL_JAVA_THREADS(thread) {
4549 print_on_error(thread, st, current, buf, buflen, &found_current);
4550 }
4551 st->cr();
4552
4553 st->print_cr("Other Threads:");
4554 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4555 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4556
4557 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4558 Universe::heap()->gc_threads_do(&print_closure);
4559
4560 if (!found_current) {
4561 st->cr();
4562 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4563 current->print_on_error(st, buf, buflen);
4564 st->cr();
4565 }
4566 st->cr();
4567 st->print_cr("Threads with active compile tasks:");
4568 print_threads_compiling(st, buf, buflen);
4569 }
4570
4571 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4572 ALL_JAVA_THREADS(thread) {
4573 if (thread->is_Compiler_thread()) {
4574 CompilerThread* ct = (CompilerThread*) thread;
4575 if (ct->task() != NULL) {
4576 thread->print_name_on_error(st, buf, buflen);
4577 ct->task()->print(st, NULL, true, true);
4578 }
4579 }
4580 }
4581 }
4582
4583
4584 // Internal SpinLock and Mutex
4585 // Based on ParkEvent
4586
4587 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4588 //
4589 // We employ SpinLocks _only for low-contention, fixed-length
4590 // short-duration critical sections where we're concerned
4591 // about native mutex_t or HotSpot Mutex:: latency.
4592 // The mux construct provides a spin-then-block mutual exclusion
4593 // mechanism.
4594 //
4595 // Testing has shown that contention on the ListLock guarding gFreeList
4596 // is common. If we implement ListLock as a simple SpinLock it's common
4597 // for the JVM to devolve to yielding with little progress. This is true
4598 // despite the fact that the critical sections protected by ListLock are
4599 // extremely short.
4600 //
4601 // TODO-FIXME: ListLock should be of type SpinLock.
4602 // We should make this a 1st-class type, integrated into the lock
4603 // hierarchy as leaf-locks. Critically, the SpinLock structure
4604 // should have sufficient padding to avoid false-sharing and excessive
4605 // cache-coherency traffic.
4606
4607
4608 typedef volatile int SpinLockT;
4609
4610 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4611 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4612 return; // normal fast-path return
4613 }
4614
4615 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4616 TEVENT(SpinAcquire - ctx);
4617 int ctr = 0;
4618 int Yields = 0;
4619 for (;;) {
4620 while (*adr != 0) {
4621 ++ctr;
4622 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4623 if (Yields > 5) {
4624 os::naked_short_sleep(1);
4625 } else {
4626 os::naked_yield();
4627 ++Yields;
4628 }
4629 } else {
4630 SpinPause();
4631 }
4632 }
4633 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4634 }
4635 }
4636
4637 void Thread::SpinRelease(volatile int * adr) {
4638 assert(*adr != 0, "invariant");
4639 OrderAccess::fence(); // guarantee at least release consistency.
4640 // Roach-motel semantics.
4641 // It's safe if subsequent LDs and STs float "up" into the critical section,
4642 // but prior LDs and STs within the critical section can't be allowed
4643 // to reorder or float past the ST that releases the lock.
4644 // Loads and stores in the critical section - which appear in program
4645 // order before the store that releases the lock - must also appear
4646 // before the store that releases the lock in memory visibility order.
4647 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4648 // the ST of 0 into the lock-word which releases the lock, so fence
4649 // more than covers this on all platforms.
4650 *adr = 0;
4651 }
4652
4653 // muxAcquire and muxRelease:
4654 //
4655 // * muxAcquire and muxRelease support a single-word lock-word construct.
4656 // The LSB of the word is set IFF the lock is held.
4657 // The remainder of the word points to the head of a singly-linked list
4658 // of threads blocked on the lock.
4659 //
4660 // * The current implementation of muxAcquire-muxRelease uses its own
4661 // dedicated Thread._MuxEvent instance. If we're interested in
4662 // minimizing the peak number of extant ParkEvent instances then
4663 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4664 // as certain invariants were satisfied. Specifically, care would need
4665 // to be taken with regards to consuming unpark() "permits".
4666 // A safe rule of thumb is that a thread would never call muxAcquire()
4667 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4668 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4669 // consume an unpark() permit intended for monitorenter, for instance.
4670 // One way around this would be to widen the restricted-range semaphore
4671 // implemented in park(). Another alternative would be to provide
4672 // multiple instances of the PlatformEvent() for each thread. One
4673 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4674 //
4675 // * Usage:
4676 // -- Only as leaf locks
4677 // -- for short-term locking only as muxAcquire does not perform
4678 // thread state transitions.
4679 //
4680 // Alternatives:
4681 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4682 // but with parking or spin-then-park instead of pure spinning.
4683 // * Use Taura-Oyama-Yonenzawa locks.
4684 // * It's possible to construct a 1-0 lock if we encode the lockword as
4685 // (List,LockByte). Acquire will CAS the full lockword while Release
4686 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4687 // acquiring threads use timers (ParkTimed) to detect and recover from
4688 // the stranding window. Thread/Node structures must be aligned on 256-byte
4689 // boundaries by using placement-new.
4690 // * Augment MCS with advisory back-link fields maintained with CAS().
4691 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4692 // The validity of the backlinks must be ratified before we trust the value.
4693 // If the backlinks are invalid the exiting thread must back-track through the
4694 // the forward links, which are always trustworthy.
4695 // * Add a successor indication. The LockWord is currently encoded as
4696 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4697 // to provide the usual futile-wakeup optimization.
4698 // See RTStt for details.
4699 // * Consider schedctl.sc_nopreempt to cover the critical section.
4700 //
4701
4702
4703 typedef volatile intptr_t MutexT; // Mux Lock-word
4704 enum MuxBits { LOCKBIT = 1 };
4705
4706 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4707 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4708 if (w == 0) return;
4709 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4710 return;
4711 }
4712
4713 TEVENT(muxAcquire - Contention);
4714 ParkEvent * const Self = Thread::current()->_MuxEvent;
4715 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4716 for (;;) {
4717 int its = (os::is_MP() ? 100 : 0) + 1;
4718
4719 // Optional spin phase: spin-then-park strategy
4720 while (--its >= 0) {
4721 w = *Lock;
4722 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4723 return;
4724 }
4725 }
4726
4727 Self->reset();
4728 Self->OnList = intptr_t(Lock);
4729 // The following fence() isn't _strictly necessary as the subsequent
4730 // CAS() both serializes execution and ratifies the fetched *Lock value.
4731 OrderAccess::fence();
4732 for (;;) {
4733 w = *Lock;
4734 if ((w & LOCKBIT) == 0) {
4735 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4736 Self->OnList = 0; // hygiene - allows stronger asserts
4737 return;
4738 }
4739 continue; // Interference -- *Lock changed -- Just retry
4740 }
4741 assert(w & LOCKBIT, "invariant");
4742 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4743 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4744 }
4745
4746 while (Self->OnList != 0) {
4747 Self->park();
4748 }
4749 }
4750 }
4751
4752 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4753 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4754 if (w == 0) return;
4755 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4756 return;
4757 }
4758
4759 TEVENT(muxAcquire - Contention);
4760 ParkEvent * ReleaseAfter = NULL;
4761 if (ev == NULL) {
4762 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4763 }
4764 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4765 for (;;) {
4766 guarantee(ev->OnList == 0, "invariant");
4767 int its = (os::is_MP() ? 100 : 0) + 1;
4768
4769 // Optional spin phase: spin-then-park strategy
4770 while (--its >= 0) {
4771 w = *Lock;
4772 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4773 if (ReleaseAfter != NULL) {
4774 ParkEvent::Release(ReleaseAfter);
4775 }
4776 return;
4777 }
4778 }
4779
4780 ev->reset();
4781 ev->OnList = intptr_t(Lock);
4782 // The following fence() isn't _strictly necessary as the subsequent
4783 // CAS() both serializes execution and ratifies the fetched *Lock value.
4784 OrderAccess::fence();
4785 for (;;) {
4786 w = *Lock;
4787 if ((w & LOCKBIT) == 0) {
4788 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4789 ev->OnList = 0;
4790 // We call ::Release while holding the outer lock, thus
4791 // artificially lengthening the critical section.
4792 // Consider deferring the ::Release() until the subsequent unlock(),
4793 // after we've dropped the outer lock.
4794 if (ReleaseAfter != NULL) {
4795 ParkEvent::Release(ReleaseAfter);
4796 }
4797 return;
4798 }
4799 continue; // Interference -- *Lock changed -- Just retry
4800 }
4801 assert(w & LOCKBIT, "invariant");
4802 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4803 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4804 }
4805
4806 while (ev->OnList != 0) {
4807 ev->park();
4808 }
4809 }
4810 }
4811
4812 // Release() must extract a successor from the list and then wake that thread.
4813 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4814 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4815 // Release() would :
4816 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4817 // (B) Extract a successor from the private list "in-hand"
4818 // (C) attempt to CAS() the residual back into *Lock over null.
4819 // If there were any newly arrived threads and the CAS() would fail.
4820 // In that case Release() would detach the RATs, re-merge the list in-hand
4821 // with the RATs and repeat as needed. Alternately, Release() might
4822 // detach and extract a successor, but then pass the residual list to the wakee.
4823 // The wakee would be responsible for reattaching and remerging before it
4824 // competed for the lock.
4825 //
4826 // Both "pop" and DMR are immune from ABA corruption -- there can be
4827 // multiple concurrent pushers, but only one popper or detacher.
4828 // This implementation pops from the head of the list. This is unfair,
4829 // but tends to provide excellent throughput as hot threads remain hot.
4830 // (We wake recently run threads first).
4831 //
4832 // All paths through muxRelease() will execute a CAS.
4833 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4834 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4835 // executed within the critical section are complete and globally visible before the
4836 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4837 void Thread::muxRelease(volatile intptr_t * Lock) {
4838 for (;;) {
4839 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4840 assert(w & LOCKBIT, "invariant");
4841 if (w == LOCKBIT) return;
4842 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4843 assert(List != NULL, "invariant");
4844 assert(List->OnList == intptr_t(Lock), "invariant");
4845 ParkEvent * const nxt = List->ListNext;
4846 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4847
4848 // The following CAS() releases the lock and pops the head element.
4849 // The CAS() also ratifies the previously fetched lock-word value.
4850 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4851 continue;
4852 }
4853 List->OnList = 0;
4854 OrderAccess::fence();
4855 List->unpark();
4856 return;
4857 }
4858 }
4859
4860
4861 void Threads::verify() {
4862 ALL_JAVA_THREADS(p) {
4863 p->verify();
4864 }
4865 VMThread* thread = VMThread::vm_thread();
4866 if (thread != NULL) thread->verify();
4867 }