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_misc.hpp"
55 #include "prims/jvmtiExport.hpp"
56 #include "prims/jvmtiThreadState.hpp"
57 #include "prims/privilegedStack.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/atomic.hpp"
60 #include "runtime/biasedLocking.hpp"
61 #include "runtime/commandLineFlagConstraintList.hpp"
62 #include "runtime/commandLineFlagWriteableList.hpp"
63 #include "runtime/commandLineFlagRangeList.hpp"
64 #include "runtime/deoptimization.hpp"
65 #include "runtime/fprofiler.hpp"
66 #include "runtime/frame.inline.hpp"
67 #include "runtime/globals.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/interfaceSupport.hpp"
70 #include "runtime/java.hpp"
71 #include "runtime/javaCalls.hpp"
72 #include "runtime/jniPeriodicChecker.hpp"
73 #include "runtime/timerTrace.hpp"
74 #include "runtime/memprofiler.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/objectMonitor.hpp"
77 #include "runtime/orderAccess.inline.hpp"
78 #include "runtime/osThread.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/statSampler.hpp"
82 #include "runtime/stubRoutines.hpp"
83 #include "runtime/sweeper.hpp"
84 #include "runtime/task.hpp"
85 #include "runtime/thread.inline.hpp"
86 #include "runtime/threadCritical.hpp"
87 #include "runtime/vframe.hpp"
88 #include "runtime/vframeArray.hpp"
89 #include "runtime/vframe_hp.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "runtime/vm_operations.hpp"
92 #include "runtime/vm_version.hpp"
93 #include "services/attachListener.hpp"
94 #include "services/management.hpp"
95 #include "services/memTracker.hpp"
96 #include "services/threadService.hpp"
97 #include "trace/traceMacros.hpp"
98 #include "trace/tracing.hpp"
99 #include "utilities/defaultStream.hpp"
100 #include "utilities/dtrace.hpp"
101 #include "utilities/events.hpp"
102 #include "utilities/macros.hpp"
103 #include "utilities/preserveException.hpp"
104 #if INCLUDE_ALL_GCS
105 #include "gc/cms/concurrentMarkSweepThread.hpp"
106 #include "gc/g1/concurrentMarkThread.inline.hpp"
107 #include "gc/parallel/pcTasks.hpp"
108 #endif // INCLUDE_ALL_GCS
109 #if INCLUDE_JVMCI
110 #include "jvmci/jvmciCompiler.hpp"
111 #include "jvmci/jvmciRuntime.hpp"
112 #include "logging/logHandle.hpp"
113 #endif
114 #ifdef COMPILER1
115 #include "c1/c1_Compiler.hpp"
116 #endif
117 #ifdef COMPILER2
118 #include "opto/c2compiler.hpp"
119 #include "opto/idealGraphPrinter.hpp"
120 #endif
121 #if INCLUDE_RTM_OPT
122 #include "runtime/rtmLocking.hpp"
123 #endif
124
125 // Initialization after module runtime initialization
126 void universe_post_module_init(); // must happen after call_initPhase2
127
128 #ifdef DTRACE_ENABLED
129
130 // Only bother with this argument setup if dtrace is available
131
132 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
133 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
134
135 #define DTRACE_THREAD_PROBE(probe, javathread) \
136 { \
137 ResourceMark rm(this); \
138 int len = 0; \
139 const char* name = (javathread)->get_thread_name(); \
140 len = strlen(name); \
141 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
142 (char *) name, len, \
143 java_lang_Thread::thread_id((javathread)->threadObj()), \
144 (uintptr_t) (javathread)->osthread()->thread_id(), \
145 java_lang_Thread::is_daemon((javathread)->threadObj())); \
146 }
147
148 #else // ndef DTRACE_ENABLED
149
150 #define DTRACE_THREAD_PROBE(probe, javathread)
151
152 #endif // ndef DTRACE_ENABLED
153
154 #ifndef USE_LIBRARY_BASED_TLS_ONLY
155 // Current thread is maintained as a thread-local variable
156 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
157 #endif
158 // Class hierarchy
159 // - Thread
160 // - VMThread
161 // - WatcherThread
162 // - ConcurrentMarkSweepThread
163 // - JavaThread
164 // - CompilerThread
165
166 // ======= Thread ========
167 // Support for forcing alignment of thread objects for biased locking
168 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
169 if (UseBiasedLocking) {
170 const int alignment = markOopDesc::biased_lock_alignment;
171 size_t aligned_size = size + (alignment - sizeof(intptr_t));
172 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
173 : AllocateHeap(aligned_size, flags, CURRENT_PC,
174 AllocFailStrategy::RETURN_NULL);
175 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
176 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
177 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
178 "JavaThread alignment code overflowed allocated storage");
179 if (aligned_addr != real_malloc_addr) {
180 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
181 p2i(real_malloc_addr),
182 p2i(aligned_addr));
183 }
184 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
185 return aligned_addr;
186 } else {
187 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
188 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
189 }
190 }
191
192 void Thread::operator delete(void* p) {
193 if (UseBiasedLocking) {
194 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
195 FreeHeap(real_malloc_addr);
196 } else {
197 FreeHeap(p);
198 }
199 }
200
201
202 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
203 // JavaThread
204
205
206 Thread::Thread() {
207 // stack and get_thread
208 set_stack_base(NULL);
209 set_stack_size(0);
210 set_self_raw_id(0);
211 set_lgrp_id(-1);
212 DEBUG_ONLY(clear_suspendible_thread();)
213
214 // allocated data structures
215 set_osthread(NULL);
216 set_resource_area(new (mtThread)ResourceArea());
217 DEBUG_ONLY(_current_resource_mark = NULL;)
218 set_handle_area(new (mtThread) HandleArea(NULL));
219 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
220 set_active_handles(NULL);
221 set_free_handle_block(NULL);
222 set_last_handle_mark(NULL);
223
224 // This initial value ==> never claimed.
225 _oops_do_parity = 0;
226
227 // the handle mark links itself to last_handle_mark
228 new HandleMark(this);
229
230 // plain initialization
231 debug_only(_owned_locks = NULL;)
232 debug_only(_allow_allocation_count = 0;)
233 NOT_PRODUCT(_allow_safepoint_count = 0;)
234 NOT_PRODUCT(_skip_gcalot = false;)
235 _jvmti_env_iteration_count = 0;
236 set_allocated_bytes(0);
237 _vm_operation_started_count = 0;
238 _vm_operation_completed_count = 0;
239 _current_pending_monitor = NULL;
240 _current_pending_monitor_is_from_java = true;
241 _current_waiting_monitor = NULL;
242 _num_nested_signal = 0;
243 omFreeList = NULL;
244 omFreeCount = 0;
245 omFreeProvision = 32;
246 omInUseList = NULL;
247 omInUseCount = 0;
248
249 #ifdef ASSERT
250 _visited_for_critical_count = false;
251 #endif
252
253 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
254 Monitor::_safepoint_check_sometimes);
255 _suspend_flags = 0;
256
257 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
258 _hashStateX = os::random();
259 _hashStateY = 842502087;
260 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
261 _hashStateW = 273326509;
262
263 _OnTrap = 0;
264 _schedctl = NULL;
265 _Stalled = 0;
266 _TypeTag = 0x2BAD;
267
268 // Many of the following fields are effectively final - immutable
269 // Note that nascent threads can't use the Native Monitor-Mutex
270 // construct until the _MutexEvent is initialized ...
271 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
272 // we might instead use a stack of ParkEvents that we could provision on-demand.
273 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
274 // and ::Release()
275 _ParkEvent = ParkEvent::Allocate(this);
276 _SleepEvent = ParkEvent::Allocate(this);
277 _MutexEvent = ParkEvent::Allocate(this);
278 _MuxEvent = ParkEvent::Allocate(this);
279
280 #ifdef CHECK_UNHANDLED_OOPS
281 if (CheckUnhandledOops) {
282 _unhandled_oops = new UnhandledOops(this);
283 }
284 #endif // CHECK_UNHANDLED_OOPS
285 #ifdef ASSERT
286 if (UseBiasedLocking) {
287 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
288 assert(this == _real_malloc_address ||
289 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
290 "bug in forced alignment of thread objects");
291 }
292 #endif // ASSERT
293 }
294
295 void Thread::initialize_thread_current() {
296 #ifndef USE_LIBRARY_BASED_TLS_ONLY
297 assert(_thr_current == NULL, "Thread::current already initialized");
298 _thr_current = this;
299 #endif
300 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
301 ThreadLocalStorage::set_thread(this);
302 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
303 }
304
305 void Thread::clear_thread_current() {
306 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
307 #ifndef USE_LIBRARY_BASED_TLS_ONLY
308 _thr_current = NULL;
309 #endif
310 ThreadLocalStorage::set_thread(NULL);
311 }
312
313 void Thread::record_stack_base_and_size() {
314 set_stack_base(os::current_stack_base());
315 set_stack_size(os::current_stack_size());
316 // CR 7190089: on Solaris, primordial thread's stack is adjusted
317 // in initialize_thread(). Without the adjustment, stack size is
318 // incorrect if stack is set to unlimited (ulimit -s unlimited).
319 // So far, only Solaris has real implementation of initialize_thread().
320 //
321 // set up any platform-specific state.
322 os::initialize_thread(this);
323
324 // Set stack limits after thread is initialized.
325 if (is_Java_thread()) {
326 ((JavaThread*) this)->set_stack_overflow_limit();
327 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
328 }
329 #if INCLUDE_NMT
330 // record thread's native stack, stack grows downward
331 MemTracker::record_thread_stack(stack_end(), stack_size());
332 #endif // INCLUDE_NMT
333 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
334 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
335 os::current_thread_id(), p2i(stack_base() - stack_size()),
336 p2i(stack_base()), stack_size()/1024);
337 }
338
339
340 Thread::~Thread() {
341 EVENT_THREAD_DESTRUCT(this);
342
343 // stack_base can be NULL if the thread is never started or exited before
344 // record_stack_base_and_size called. Although, we would like to ensure
345 // that all started threads do call record_stack_base_and_size(), there is
346 // not proper way to enforce that.
347 #if INCLUDE_NMT
348 if (_stack_base != NULL) {
349 MemTracker::release_thread_stack(stack_end(), stack_size());
350 #ifdef ASSERT
351 set_stack_base(NULL);
352 #endif
353 }
354 #endif // INCLUDE_NMT
355
356 // deallocate data structures
357 delete resource_area();
358 // since the handle marks are using the handle area, we have to deallocated the root
359 // handle mark before deallocating the thread's handle area,
360 assert(last_handle_mark() != NULL, "check we have an element");
361 delete last_handle_mark();
362 assert(last_handle_mark() == NULL, "check we have reached the end");
363
364 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
365 // We NULL out the fields for good hygiene.
366 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
367 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
368 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
369 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
370
371 delete handle_area();
372 delete metadata_handles();
373
374 // SR_handler uses this as a termination indicator -
375 // needs to happen before os::free_thread()
376 delete _SR_lock;
377 _SR_lock = NULL;
378
379 // osthread() can be NULL, if creation of thread failed.
380 if (osthread() != NULL) os::free_thread(osthread());
381
382 // clear Thread::current if thread is deleting itself.
383 // Needed to ensure JNI correctly detects non-attached threads.
384 if (this == Thread::current()) {
385 clear_thread_current();
386 }
387
388 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
389 }
390
391 // NOTE: dummy function for assertion purpose.
392 void Thread::run() {
393 ShouldNotReachHere();
394 }
395
396 #ifdef ASSERT
397 // Private method to check for dangling thread pointer
398 void check_for_dangling_thread_pointer(Thread *thread) {
399 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
400 "possibility of dangling Thread pointer");
401 }
402 #endif
403
404 ThreadPriority Thread::get_priority(const Thread* const thread) {
405 ThreadPriority priority;
406 // Can return an error!
407 (void)os::get_priority(thread, priority);
408 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
409 return priority;
410 }
411
412 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
413 debug_only(check_for_dangling_thread_pointer(thread);)
414 // Can return an error!
415 (void)os::set_priority(thread, priority);
416 }
417
418
419 void Thread::start(Thread* thread) {
420 // Start is different from resume in that its safety is guaranteed by context or
421 // being called from a Java method synchronized on the Thread object.
422 if (!DisableStartThread) {
423 if (thread->is_Java_thread()) {
424 // Initialize the thread state to RUNNABLE before starting this thread.
425 // Can not set it after the thread started because we do not know the
426 // exact thread state at that time. It could be in MONITOR_WAIT or
427 // in SLEEPING or some other state.
428 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
429 java_lang_Thread::RUNNABLE);
430 }
431 os::start_thread(thread);
432 }
433 }
434
435 // Enqueue a VM_Operation to do the job for us - sometime later
436 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
437 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
438 VMThread::execute(vm_stop);
439 }
440
441
442 // Check if an external suspend request has completed (or has been
443 // cancelled). Returns true if the thread is externally suspended and
444 // false otherwise.
445 //
446 // The bits parameter returns information about the code path through
447 // the routine. Useful for debugging:
448 //
449 // set in is_ext_suspend_completed():
450 // 0x00000001 - routine was entered
451 // 0x00000010 - routine return false at end
452 // 0x00000100 - thread exited (return false)
453 // 0x00000200 - suspend request cancelled (return false)
454 // 0x00000400 - thread suspended (return true)
455 // 0x00001000 - thread is in a suspend equivalent state (return true)
456 // 0x00002000 - thread is native and walkable (return true)
457 // 0x00004000 - thread is native_trans and walkable (needed retry)
458 //
459 // set in wait_for_ext_suspend_completion():
460 // 0x00010000 - routine was entered
461 // 0x00020000 - suspend request cancelled before loop (return false)
462 // 0x00040000 - thread suspended before loop (return true)
463 // 0x00080000 - suspend request cancelled in loop (return false)
464 // 0x00100000 - thread suspended in loop (return true)
465 // 0x00200000 - suspend not completed during retry loop (return false)
466
467 // Helper class for tracing suspend wait debug bits.
468 //
469 // 0x00000100 indicates that the target thread exited before it could
470 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
471 // 0x00080000 each indicate a cancelled suspend request so they don't
472 // count as wait failures either.
473 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
474
475 class TraceSuspendDebugBits : public StackObj {
476 private:
477 JavaThread * jt;
478 bool is_wait;
479 bool called_by_wait; // meaningful when !is_wait
480 uint32_t * bits;
481
482 public:
483 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
484 uint32_t *_bits) {
485 jt = _jt;
486 is_wait = _is_wait;
487 called_by_wait = _called_by_wait;
488 bits = _bits;
489 }
490
491 ~TraceSuspendDebugBits() {
492 if (!is_wait) {
493 #if 1
494 // By default, don't trace bits for is_ext_suspend_completed() calls.
495 // That trace is very chatty.
496 return;
497 #else
498 if (!called_by_wait) {
499 // If tracing for is_ext_suspend_completed() is enabled, then only
500 // trace calls to it from wait_for_ext_suspend_completion()
501 return;
502 }
503 #endif
504 }
505
506 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
507 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
508 MutexLocker ml(Threads_lock); // needed for get_thread_name()
509 ResourceMark rm;
510
511 tty->print_cr(
512 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
513 jt->get_thread_name(), *bits);
514
515 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
516 }
517 }
518 }
519 };
520 #undef DEBUG_FALSE_BITS
521
522
523 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
524 uint32_t *bits) {
525 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
526
527 bool did_trans_retry = false; // only do thread_in_native_trans retry once
528 bool do_trans_retry; // flag to force the retry
529
530 *bits |= 0x00000001;
531
532 do {
533 do_trans_retry = false;
534
535 if (is_exiting()) {
536 // Thread is in the process of exiting. This is always checked
537 // first to reduce the risk of dereferencing a freed JavaThread.
538 *bits |= 0x00000100;
539 return false;
540 }
541
542 if (!is_external_suspend()) {
543 // Suspend request is cancelled. This is always checked before
544 // is_ext_suspended() to reduce the risk of a rogue resume
545 // confusing the thread that made the suspend request.
546 *bits |= 0x00000200;
547 return false;
548 }
549
550 if (is_ext_suspended()) {
551 // thread is suspended
552 *bits |= 0x00000400;
553 return true;
554 }
555
556 // Now that we no longer do hard suspends of threads running
557 // native code, the target thread can be changing thread state
558 // while we are in this routine:
559 //
560 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
561 //
562 // We save a copy of the thread state as observed at this moment
563 // and make our decision about suspend completeness based on the
564 // copy. This closes the race where the thread state is seen as
565 // _thread_in_native_trans in the if-thread_blocked check, but is
566 // seen as _thread_blocked in if-thread_in_native_trans check.
567 JavaThreadState save_state = thread_state();
568
569 if (save_state == _thread_blocked && is_suspend_equivalent()) {
570 // If the thread's state is _thread_blocked and this blocking
571 // condition is known to be equivalent to a suspend, then we can
572 // consider the thread to be externally suspended. This means that
573 // the code that sets _thread_blocked has been modified to do
574 // self-suspension if the blocking condition releases. We also
575 // used to check for CONDVAR_WAIT here, but that is now covered by
576 // the _thread_blocked with self-suspension check.
577 //
578 // Return true since we wouldn't be here unless there was still an
579 // external suspend request.
580 *bits |= 0x00001000;
581 return true;
582 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
583 // Threads running native code will self-suspend on native==>VM/Java
584 // transitions. If its stack is walkable (should always be the case
585 // unless this function is called before the actual java_suspend()
586 // call), then the wait is done.
587 *bits |= 0x00002000;
588 return true;
589 } else if (!called_by_wait && !did_trans_retry &&
590 save_state == _thread_in_native_trans &&
591 frame_anchor()->walkable()) {
592 // The thread is transitioning from thread_in_native to another
593 // thread state. check_safepoint_and_suspend_for_native_trans()
594 // will force the thread to self-suspend. If it hasn't gotten
595 // there yet we may have caught the thread in-between the native
596 // code check above and the self-suspend. Lucky us. If we were
597 // called by wait_for_ext_suspend_completion(), then it
598 // will be doing the retries so we don't have to.
599 //
600 // Since we use the saved thread state in the if-statement above,
601 // there is a chance that the thread has already transitioned to
602 // _thread_blocked by the time we get here. In that case, we will
603 // make a single unnecessary pass through the logic below. This
604 // doesn't hurt anything since we still do the trans retry.
605
606 *bits |= 0x00004000;
607
608 // Once the thread leaves thread_in_native_trans for another
609 // thread state, we break out of this retry loop. We shouldn't
610 // need this flag to prevent us from getting back here, but
611 // sometimes paranoia is good.
612 did_trans_retry = true;
613
614 // We wait for the thread to transition to a more usable state.
615 for (int i = 1; i <= SuspendRetryCount; i++) {
616 // We used to do an "os::yield_all(i)" call here with the intention
617 // that yielding would increase on each retry. However, the parameter
618 // is ignored on Linux which means the yield didn't scale up. Waiting
619 // on the SR_lock below provides a much more predictable scale up for
620 // the delay. It also provides a simple/direct point to check for any
621 // safepoint requests from the VMThread
622
623 // temporarily drops SR_lock while doing wait with safepoint check
624 // (if we're a JavaThread - the WatcherThread can also call this)
625 // and increase delay with each retry
626 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
627
628 // check the actual thread state instead of what we saved above
629 if (thread_state() != _thread_in_native_trans) {
630 // the thread has transitioned to another thread state so
631 // try all the checks (except this one) one more time.
632 do_trans_retry = true;
633 break;
634 }
635 } // end retry loop
636
637
638 }
639 } while (do_trans_retry);
640
641 *bits |= 0x00000010;
642 return false;
643 }
644
645 // Wait for an external suspend request to complete (or be cancelled).
646 // Returns true if the thread is externally suspended and false otherwise.
647 //
648 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
649 uint32_t *bits) {
650 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
651 false /* !called_by_wait */, bits);
652
653 // local flag copies to minimize SR_lock hold time
654 bool is_suspended;
655 bool pending;
656 uint32_t reset_bits;
657
658 // set a marker so is_ext_suspend_completed() knows we are the caller
659 *bits |= 0x00010000;
660
661 // We use reset_bits to reinitialize the bits value at the top of
662 // each retry loop. This allows the caller to make use of any
663 // unused bits for their own marking purposes.
664 reset_bits = *bits;
665
666 {
667 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
668 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
669 delay, bits);
670 pending = is_external_suspend();
671 }
672 // must release SR_lock to allow suspension to complete
673
674 if (!pending) {
675 // A cancelled suspend request is the only false return from
676 // is_ext_suspend_completed() that keeps us from entering the
677 // retry loop.
678 *bits |= 0x00020000;
679 return false;
680 }
681
682 if (is_suspended) {
683 *bits |= 0x00040000;
684 return true;
685 }
686
687 for (int i = 1; i <= retries; i++) {
688 *bits = reset_bits; // reinit to only track last retry
689
690 // We used to do an "os::yield_all(i)" call here with the intention
691 // that yielding would increase on each retry. However, the parameter
692 // is ignored on Linux which means the yield didn't scale up. Waiting
693 // on the SR_lock below provides a much more predictable scale up for
694 // the delay. It also provides a simple/direct point to check for any
695 // safepoint requests from the VMThread
696
697 {
698 MutexLocker ml(SR_lock());
699 // wait with safepoint check (if we're a JavaThread - the WatcherThread
700 // can also call this) and increase delay with each retry
701 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
702
703 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
704 delay, bits);
705
706 // It is possible for the external suspend request to be cancelled
707 // (by a resume) before the actual suspend operation is completed.
708 // Refresh our local copy to see if we still need to wait.
709 pending = is_external_suspend();
710 }
711
712 if (!pending) {
713 // A cancelled suspend request is the only false return from
714 // is_ext_suspend_completed() that keeps us from staying in the
715 // retry loop.
716 *bits |= 0x00080000;
717 return false;
718 }
719
720 if (is_suspended) {
721 *bits |= 0x00100000;
722 return true;
723 }
724 } // end retry loop
725
726 // thread did not suspend after all our retries
727 *bits |= 0x00200000;
728 return false;
729 }
730
731 #ifndef PRODUCT
732 void JavaThread::record_jump(address target, address instr, const char* file,
733 int line) {
734
735 // This should not need to be atomic as the only way for simultaneous
736 // updates is via interrupts. Even then this should be rare or non-existent
737 // and we don't care that much anyway.
738
739 int index = _jmp_ring_index;
740 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
741 _jmp_ring[index]._target = (intptr_t) target;
742 _jmp_ring[index]._instruction = (intptr_t) instr;
743 _jmp_ring[index]._file = file;
744 _jmp_ring[index]._line = line;
745 }
746 #endif // PRODUCT
747
748 // Called by flat profiler
749 // Callers have already called wait_for_ext_suspend_completion
750 // The assertion for that is currently too complex to put here:
751 bool JavaThread::profile_last_Java_frame(frame* _fr) {
752 bool gotframe = false;
753 // self suspension saves needed state.
754 if (has_last_Java_frame() && _anchor.walkable()) {
755 *_fr = pd_last_frame();
756 gotframe = true;
757 }
758 return gotframe;
759 }
760
761 void Thread::interrupt(Thread* thread) {
762 debug_only(check_for_dangling_thread_pointer(thread);)
763 os::interrupt(thread);
764 }
765
766 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
767 debug_only(check_for_dangling_thread_pointer(thread);)
768 // Note: If clear_interrupted==false, this simply fetches and
769 // returns the value of the field osthread()->interrupted().
770 return os::is_interrupted(thread, clear_interrupted);
771 }
772
773
774 // GC Support
775 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
776 jint thread_parity = _oops_do_parity;
777 if (thread_parity != strong_roots_parity) {
778 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
779 if (res == thread_parity) {
780 return true;
781 } else {
782 guarantee(res == strong_roots_parity, "Or else what?");
783 return false;
784 }
785 }
786 return false;
787 }
788
789 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
790 active_handles()->oops_do(f);
791 // Do oop for ThreadShadow
792 f->do_oop((oop*)&_pending_exception);
793 handle_area()->oops_do(f);
794
795 if (MonitorInUseLists) {
796 // When using thread local monitor lists, we scan them here,
797 // and the remaining global monitors in ObjectSynchronizer::oops_do().
798 ObjectSynchronizer::thread_local_used_oops_do(this, f);
799 }
800 }
801
802 void Thread::metadata_handles_do(void f(Metadata*)) {
803 // Only walk the Handles in Thread.
804 if (metadata_handles() != NULL) {
805 for (int i = 0; i< metadata_handles()->length(); i++) {
806 f(metadata_handles()->at(i));
807 }
808 }
809 }
810
811 void Thread::print_on(outputStream* st) const {
812 // get_priority assumes osthread initialized
813 if (osthread() != NULL) {
814 int os_prio;
815 if (os::get_native_priority(this, &os_prio) == OS_OK) {
816 st->print("os_prio=%d ", os_prio);
817 }
818 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
819 ext().print_on(st);
820 osthread()->print_on(st);
821 }
822 debug_only(if (WizardMode) print_owned_locks_on(st);)
823 }
824
825 // Thread::print_on_error() is called by fatal error handler. Don't use
826 // any lock or allocate memory.
827 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
828 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
829
830 if (is_VM_thread()) { st->print("VMThread"); }
831 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
832 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
833 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
834 else { st->print("Thread"); }
835
836 if (is_Named_thread()) {
837 st->print(" \"%s\"", name());
838 }
839
840 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
841 p2i(stack_end()), p2i(stack_base()));
842
843 if (osthread()) {
844 st->print(" [id=%d]", osthread()->thread_id());
845 }
846 }
847
848 #ifdef ASSERT
849 void Thread::print_owned_locks_on(outputStream* st) const {
850 Monitor *cur = _owned_locks;
851 if (cur == NULL) {
852 st->print(" (no locks) ");
853 } else {
854 st->print_cr(" Locks owned:");
855 while (cur) {
856 cur->print_on(st);
857 cur = cur->next();
858 }
859 }
860 }
861
862 static int ref_use_count = 0;
863
864 bool Thread::owns_locks_but_compiled_lock() const {
865 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
866 if (cur != Compile_lock) return true;
867 }
868 return false;
869 }
870
871
872 #endif
873
874 #ifndef PRODUCT
875
876 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
877 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
878 // no threads which allow_vm_block's are held
879 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
880 // Check if current thread is allowed to block at a safepoint
881 if (!(_allow_safepoint_count == 0)) {
882 fatal("Possible safepoint reached by thread that does not allow it");
883 }
884 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
885 fatal("LEAF method calling lock?");
886 }
887
888 #ifdef ASSERT
889 if (potential_vm_operation && is_Java_thread()
890 && !Universe::is_bootstrapping()) {
891 // Make sure we do not hold any locks that the VM thread also uses.
892 // This could potentially lead to deadlocks
893 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
894 // Threads_lock is special, since the safepoint synchronization will not start before this is
895 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
896 // since it is used to transfer control between JavaThreads and the VMThread
897 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
898 if ((cur->allow_vm_block() &&
899 cur != Threads_lock &&
900 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
901 cur != VMOperationRequest_lock &&
902 cur != VMOperationQueue_lock) ||
903 cur->rank() == Mutex::special) {
904 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
905 }
906 }
907 }
908
909 if (GCALotAtAllSafepoints) {
910 // We could enter a safepoint here and thus have a gc
911 InterfaceSupport::check_gc_alot();
912 }
913 #endif
914 }
915 #endif
916
917 bool Thread::is_in_stack(address adr) const {
918 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
919 address end = os::current_stack_pointer();
920 // Allow non Java threads to call this without stack_base
921 if (_stack_base == NULL) return true;
922 if (stack_base() >= adr && adr >= end) return true;
923
924 return false;
925 }
926
927 bool Thread::is_in_usable_stack(address adr) const {
928 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
929 size_t usable_stack_size = _stack_size - stack_guard_size;
930
931 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
932 }
933
934
935 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
936 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
937 // used for compilation in the future. If that change is made, the need for these methods
938 // should be revisited, and they should be removed if possible.
939
940 bool Thread::is_lock_owned(address adr) const {
941 return on_local_stack(adr);
942 }
943
944 bool Thread::set_as_starting_thread() {
945 // NOTE: this must be called inside the main thread.
946 return os::create_main_thread((JavaThread*)this);
947 }
948
949 static void initialize_class(Symbol* class_name, TRAPS) {
950 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
951 InstanceKlass::cast(klass)->initialize(CHECK);
952 }
953
954
955 // Creates the initial ThreadGroup
956 static Handle create_initial_thread_group(TRAPS) {
957 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
958 InstanceKlass* ik = InstanceKlass::cast(k);
959
960 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
961 {
962 JavaValue result(T_VOID);
963 JavaCalls::call_special(&result,
964 system_instance,
965 ik,
966 vmSymbols::object_initializer_name(),
967 vmSymbols::void_method_signature(),
968 CHECK_NH);
969 }
970 Universe::set_system_thread_group(system_instance());
971
972 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
973 {
974 JavaValue result(T_VOID);
975 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
976 JavaCalls::call_special(&result,
977 main_instance,
978 ik,
979 vmSymbols::object_initializer_name(),
980 vmSymbols::threadgroup_string_void_signature(),
981 system_instance,
982 string,
983 CHECK_NH);
984 }
985 return main_instance;
986 }
987
988 // Creates the initial Thread
989 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
990 TRAPS) {
991 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
992 InstanceKlass* ik = InstanceKlass::cast(k);
993 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
994
995 java_lang_Thread::set_thread(thread_oop(), thread);
996 java_lang_Thread::set_priority(thread_oop(), NormPriority);
997 thread->set_threadObj(thread_oop());
998
999 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1000
1001 JavaValue result(T_VOID);
1002 JavaCalls::call_special(&result, thread_oop,
1003 ik,
1004 vmSymbols::object_initializer_name(),
1005 vmSymbols::threadgroup_string_void_signature(),
1006 thread_group,
1007 string,
1008 CHECK_NULL);
1009 return thread_oop();
1010 }
1011
1012 char java_runtime_name[128] = "";
1013 char java_runtime_version[128] = "";
1014
1015 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1016 static const char* get_java_runtime_name(TRAPS) {
1017 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1018 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1019 fieldDescriptor fd;
1020 bool found = k != NULL &&
1021 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1022 vmSymbols::string_signature(), &fd);
1023 if (found) {
1024 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1025 if (name_oop == NULL) {
1026 return NULL;
1027 }
1028 const char* name = java_lang_String::as_utf8_string(name_oop,
1029 java_runtime_name,
1030 sizeof(java_runtime_name));
1031 return name;
1032 } else {
1033 return NULL;
1034 }
1035 }
1036
1037 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1038 static const char* get_java_runtime_version(TRAPS) {
1039 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1040 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1041 fieldDescriptor fd;
1042 bool found = k != NULL &&
1043 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1044 vmSymbols::string_signature(), &fd);
1045 if (found) {
1046 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1047 if (name_oop == NULL) {
1048 return NULL;
1049 }
1050 const char* name = java_lang_String::as_utf8_string(name_oop,
1051 java_runtime_version,
1052 sizeof(java_runtime_version));
1053 return name;
1054 } else {
1055 return NULL;
1056 }
1057 }
1058
1059 // General purpose hook into Java code, run once when the VM is initialized.
1060 // The Java library method itself may be changed independently from the VM.
1061 static void call_postVMInitHook(TRAPS) {
1062 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1063 if (klass != NULL) {
1064 JavaValue result(T_VOID);
1065 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1066 vmSymbols::void_method_signature(),
1067 CHECK);
1068 }
1069 }
1070
1071 static void reset_vm_info_property(TRAPS) {
1072 // the vm info string
1073 ResourceMark rm(THREAD);
1074 const char *vm_info = VM_Version::vm_info_string();
1075
1076 // java.lang.System class
1077 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1078
1079 // setProperty arguments
1080 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1081 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1082
1083 // return value
1084 JavaValue r(T_OBJECT);
1085
1086 // public static String setProperty(String key, String value);
1087 JavaCalls::call_static(&r,
1088 klass,
1089 vmSymbols::setProperty_name(),
1090 vmSymbols::string_string_string_signature(),
1091 key_str,
1092 value_str,
1093 CHECK);
1094 }
1095
1096
1097 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1098 bool daemon, TRAPS) {
1099 assert(thread_group.not_null(), "thread group should be specified");
1100 assert(threadObj() == NULL, "should only create Java thread object once");
1101
1102 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1103 InstanceKlass* ik = InstanceKlass::cast(k);
1104 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1105
1106 java_lang_Thread::set_thread(thread_oop(), this);
1107 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1108 set_threadObj(thread_oop());
1109
1110 JavaValue result(T_VOID);
1111 if (thread_name != NULL) {
1112 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1113 // Thread gets assigned specified name and null target
1114 JavaCalls::call_special(&result,
1115 thread_oop,
1116 ik,
1117 vmSymbols::object_initializer_name(),
1118 vmSymbols::threadgroup_string_void_signature(),
1119 thread_group, // Argument 1
1120 name, // Argument 2
1121 THREAD);
1122 } else {
1123 // Thread gets assigned name "Thread-nnn" and null target
1124 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1125 JavaCalls::call_special(&result,
1126 thread_oop,
1127 ik,
1128 vmSymbols::object_initializer_name(),
1129 vmSymbols::threadgroup_runnable_void_signature(),
1130 thread_group, // Argument 1
1131 Handle(), // Argument 2
1132 THREAD);
1133 }
1134
1135
1136 if (daemon) {
1137 java_lang_Thread::set_daemon(thread_oop());
1138 }
1139
1140 if (HAS_PENDING_EXCEPTION) {
1141 return;
1142 }
1143
1144 Klass* group = SystemDictionary::ThreadGroup_klass();
1145 Handle threadObj(THREAD, this->threadObj());
1146
1147 JavaCalls::call_special(&result,
1148 thread_group,
1149 group,
1150 vmSymbols::add_method_name(),
1151 vmSymbols::thread_void_signature(),
1152 threadObj, // Arg 1
1153 THREAD);
1154 }
1155
1156 // NamedThread -- non-JavaThread subclasses with multiple
1157 // uniquely named instances should derive from this.
1158 NamedThread::NamedThread() : Thread() {
1159 _name = NULL;
1160 _processed_thread = NULL;
1161 _gc_id = GCId::undefined();
1162 }
1163
1164 NamedThread::~NamedThread() {
1165 if (_name != NULL) {
1166 FREE_C_HEAP_ARRAY(char, _name);
1167 _name = NULL;
1168 }
1169 }
1170
1171 void NamedThread::set_name(const char* format, ...) {
1172 guarantee(_name == NULL, "Only get to set name once.");
1173 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1174 guarantee(_name != NULL, "alloc failure");
1175 va_list ap;
1176 va_start(ap, format);
1177 jio_vsnprintf(_name, max_name_len, format, ap);
1178 va_end(ap);
1179 }
1180
1181 void NamedThread::initialize_named_thread() {
1182 set_native_thread_name(name());
1183 }
1184
1185 void NamedThread::print_on(outputStream* st) const {
1186 st->print("\"%s\" ", name());
1187 Thread::print_on(st);
1188 st->cr();
1189 }
1190
1191
1192 // ======= WatcherThread ========
1193
1194 // The watcher thread exists to simulate timer interrupts. It should
1195 // be replaced by an abstraction over whatever native support for
1196 // timer interrupts exists on the platform.
1197
1198 WatcherThread* WatcherThread::_watcher_thread = NULL;
1199 bool WatcherThread::_startable = false;
1200 volatile bool WatcherThread::_should_terminate = false;
1201
1202 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1203 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1204 if (os::create_thread(this, os::watcher_thread)) {
1205 _watcher_thread = this;
1206
1207 // Set the watcher thread to the highest OS priority which should not be
1208 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1209 // is created. The only normal thread using this priority is the reference
1210 // handler thread, which runs for very short intervals only.
1211 // If the VMThread's priority is not lower than the WatcherThread profiling
1212 // will be inaccurate.
1213 os::set_priority(this, MaxPriority);
1214 if (!DisableStartThread) {
1215 os::start_thread(this);
1216 }
1217 }
1218 }
1219
1220 int WatcherThread::sleep() const {
1221 // The WatcherThread does not participate in the safepoint protocol
1222 // for the PeriodicTask_lock because it is not a JavaThread.
1223 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1224
1225 if (_should_terminate) {
1226 // check for termination before we do any housekeeping or wait
1227 return 0; // we did not sleep.
1228 }
1229
1230 // remaining will be zero if there are no tasks,
1231 // causing the WatcherThread to sleep until a task is
1232 // enrolled
1233 int remaining = PeriodicTask::time_to_wait();
1234 int time_slept = 0;
1235
1236 // we expect this to timeout - we only ever get unparked when
1237 // we should terminate or when a new task has been enrolled
1238 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1239
1240 jlong time_before_loop = os::javaTimeNanos();
1241
1242 while (true) {
1243 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1244 remaining);
1245 jlong now = os::javaTimeNanos();
1246
1247 if (remaining == 0) {
1248 // if we didn't have any tasks we could have waited for a long time
1249 // consider the time_slept zero and reset time_before_loop
1250 time_slept = 0;
1251 time_before_loop = now;
1252 } else {
1253 // need to recalculate since we might have new tasks in _tasks
1254 time_slept = (int) ((now - time_before_loop) / 1000000);
1255 }
1256
1257 // Change to task list or spurious wakeup of some kind
1258 if (timedout || _should_terminate) {
1259 break;
1260 }
1261
1262 remaining = PeriodicTask::time_to_wait();
1263 if (remaining == 0) {
1264 // Last task was just disenrolled so loop around and wait until
1265 // another task gets enrolled
1266 continue;
1267 }
1268
1269 remaining -= time_slept;
1270 if (remaining <= 0) {
1271 break;
1272 }
1273 }
1274
1275 return time_slept;
1276 }
1277
1278 void WatcherThread::run() {
1279 assert(this == watcher_thread(), "just checking");
1280
1281 this->record_stack_base_and_size();
1282 this->set_native_thread_name(this->name());
1283 this->set_active_handles(JNIHandleBlock::allocate_block());
1284 while (true) {
1285 assert(watcher_thread() == Thread::current(), "thread consistency check");
1286 assert(watcher_thread() == this, "thread consistency check");
1287
1288 // Calculate how long it'll be until the next PeriodicTask work
1289 // should be done, and sleep that amount of time.
1290 int time_waited = sleep();
1291
1292 if (is_error_reported()) {
1293 // A fatal error has happened, the error handler(VMError::report_and_die)
1294 // should abort JVM after creating an error log file. However in some
1295 // rare cases, the error handler itself might deadlock. Here periodically
1296 // check for error reporting timeouts, and if it happens, just proceed to
1297 // abort the VM.
1298
1299 // This code is in WatcherThread because WatcherThread wakes up
1300 // periodically so the fatal error handler doesn't need to do anything;
1301 // also because the WatcherThread is less likely to crash than other
1302 // threads.
1303
1304 for (;;) {
1305 // Note: we use naked sleep in this loop because we want to avoid using
1306 // any kind of VM infrastructure which may be broken at this point.
1307 if (VMError::check_timeout()) {
1308 // We hit error reporting timeout. Error reporting was interrupted and
1309 // will be wrapping things up now (closing files etc). Give it some more
1310 // time, then quit the VM.
1311 os::naked_short_sleep(200);
1312 // Print a message to stderr.
1313 fdStream err(defaultStream::output_fd());
1314 err.print_raw_cr("# [ timer expired, abort... ]");
1315 // skip atexit/vm_exit/vm_abort hooks
1316 os::die();
1317 }
1318
1319 // Wait a second, then recheck for timeout.
1320 os::naked_short_sleep(999);
1321 }
1322 }
1323
1324 if (_should_terminate) {
1325 // check for termination before posting the next tick
1326 break;
1327 }
1328
1329 PeriodicTask::real_time_tick(time_waited);
1330 }
1331
1332 // Signal that it is terminated
1333 {
1334 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1335 _watcher_thread = NULL;
1336 Terminator_lock->notify();
1337 }
1338 }
1339
1340 void WatcherThread::start() {
1341 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1342
1343 if (watcher_thread() == NULL && _startable) {
1344 _should_terminate = false;
1345 // Create the single instance of WatcherThread
1346 new WatcherThread();
1347 }
1348 }
1349
1350 void WatcherThread::make_startable() {
1351 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1352 _startable = true;
1353 }
1354
1355 void WatcherThread::stop() {
1356 {
1357 // Follow normal safepoint aware lock enter protocol since the
1358 // WatcherThread is stopped by another JavaThread.
1359 MutexLocker ml(PeriodicTask_lock);
1360 _should_terminate = true;
1361
1362 WatcherThread* watcher = watcher_thread();
1363 if (watcher != NULL) {
1364 // unpark the WatcherThread so it can see that it should terminate
1365 watcher->unpark();
1366 }
1367 }
1368
1369 MutexLocker mu(Terminator_lock);
1370
1371 while (watcher_thread() != NULL) {
1372 // This wait should make safepoint checks, wait without a timeout,
1373 // and wait as a suspend-equivalent condition.
1374 //
1375 // Note: If the FlatProfiler is running, then this thread is waiting
1376 // for the WatcherThread to terminate and the WatcherThread, via the
1377 // FlatProfiler task, is waiting for the external suspend request on
1378 // this thread to complete. wait_for_ext_suspend_completion() will
1379 // eventually timeout, but that takes time. Making this wait a
1380 // suspend-equivalent condition solves that timeout problem.
1381 //
1382 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1383 Mutex::_as_suspend_equivalent_flag);
1384 }
1385 }
1386
1387 void WatcherThread::unpark() {
1388 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1389 PeriodicTask_lock->notify();
1390 }
1391
1392 void WatcherThread::print_on(outputStream* st) const {
1393 st->print("\"%s\" ", name());
1394 Thread::print_on(st);
1395 st->cr();
1396 }
1397
1398 // ======= JavaThread ========
1399
1400 #if INCLUDE_JVMCI
1401
1402 jlong* JavaThread::_jvmci_old_thread_counters;
1403
1404 bool jvmci_counters_include(JavaThread* thread) {
1405 oop threadObj = thread->threadObj();
1406 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1407 }
1408
1409 void JavaThread::collect_counters(typeArrayOop array) {
1410 if (JVMCICounterSize > 0) {
1411 MutexLocker tl(Threads_lock);
1412 for (int i = 0; i < array->length(); i++) {
1413 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1414 }
1415 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1416 if (jvmci_counters_include(tp)) {
1417 for (int i = 0; i < array->length(); i++) {
1418 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1419 }
1420 }
1421 }
1422 }
1423 }
1424
1425 #endif // INCLUDE_JVMCI
1426
1427 // A JavaThread is a normal Java thread
1428
1429 void JavaThread::initialize() {
1430 // Initialize fields
1431
1432 set_saved_exception_pc(NULL);
1433 set_threadObj(NULL);
1434 _anchor.clear();
1435 set_entry_point(NULL);
1436 set_jni_functions(jni_functions());
1437 set_callee_target(NULL);
1438 set_vm_result(NULL);
1439 set_vm_result_2(NULL);
1440 set_vframe_array_head(NULL);
1441 set_vframe_array_last(NULL);
1442 set_deferred_locals(NULL);
1443 set_deopt_mark(NULL);
1444 set_deopt_compiled_method(NULL);
1445 clear_must_deopt_id();
1446 set_monitor_chunks(NULL);
1447 set_next(NULL);
1448 set_thread_state(_thread_new);
1449 _terminated = _not_terminated;
1450 _privileged_stack_top = NULL;
1451 _array_for_gc = NULL;
1452 _suspend_equivalent = false;
1453 _in_deopt_handler = 0;
1454 _doing_unsafe_access = false;
1455 _stack_guard_state = stack_guard_unused;
1456 #if INCLUDE_JVMCI
1457 _pending_monitorenter = false;
1458 _pending_deoptimization = -1;
1459 _pending_failed_speculation = NULL;
1460 _pending_transfer_to_interpreter = false;
1461 _adjusting_comp_level = false;
1462 _jvmci._alternate_call_target = NULL;
1463 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1464 if (JVMCICounterSize > 0) {
1465 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1466 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1467 } else {
1468 _jvmci_counters = NULL;
1469 }
1470 #endif // INCLUDE_JVMCI
1471 _reserved_stack_activation = NULL; // stack base not known yet
1472 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1473 _exception_pc = 0;
1474 _exception_handler_pc = 0;
1475 _is_method_handle_return = 0;
1476 _jvmti_thread_state= NULL;
1477 _should_post_on_exceptions_flag = JNI_FALSE;
1478 _jvmti_get_loaded_classes_closure = NULL;
1479 _interp_only_mode = 0;
1480 _special_runtime_exit_condition = _no_async_condition;
1481 _pending_async_exception = NULL;
1482 _thread_stat = NULL;
1483 _thread_stat = new ThreadStatistics();
1484 _blocked_on_compilation = false;
1485 _jni_active_critical = 0;
1486 _pending_jni_exception_check_fn = NULL;
1487 _do_not_unlock_if_synchronized = false;
1488 _cached_monitor_info = NULL;
1489 _parker = Parker::Allocate(this);
1490
1491 #ifndef PRODUCT
1492 _jmp_ring_index = 0;
1493 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1494 record_jump(NULL, NULL, NULL, 0);
1495 }
1496 #endif // PRODUCT
1497
1498 set_thread_profiler(NULL);
1499 if (FlatProfiler::is_active()) {
1500 // This is where we would decide to either give each thread it's own profiler
1501 // or use one global one from FlatProfiler,
1502 // or up to some count of the number of profiled threads, etc.
1503 ThreadProfiler* pp = new ThreadProfiler();
1504 pp->engage();
1505 set_thread_profiler(pp);
1506 }
1507
1508 // Setup safepoint state info for this thread
1509 ThreadSafepointState::create(this);
1510
1511 debug_only(_java_call_counter = 0);
1512
1513 // JVMTI PopFrame support
1514 _popframe_condition = popframe_inactive;
1515 _popframe_preserved_args = NULL;
1516 _popframe_preserved_args_size = 0;
1517 _frames_to_pop_failed_realloc = 0;
1518
1519 pd_initialize();
1520 }
1521
1522 #if INCLUDE_ALL_GCS
1523 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1524 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1525 #endif // INCLUDE_ALL_GCS
1526
1527 JavaThread::JavaThread(bool is_attaching_via_jni) :
1528 Thread()
1529 #if INCLUDE_ALL_GCS
1530 , _satb_mark_queue(&_satb_mark_queue_set),
1531 _dirty_card_queue(&_dirty_card_queue_set)
1532 #endif // INCLUDE_ALL_GCS
1533 {
1534 initialize();
1535 if (is_attaching_via_jni) {
1536 _jni_attach_state = _attaching_via_jni;
1537 } else {
1538 _jni_attach_state = _not_attaching_via_jni;
1539 }
1540 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1541 }
1542
1543 bool JavaThread::reguard_stack(address cur_sp) {
1544 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1545 && _stack_guard_state != stack_guard_reserved_disabled) {
1546 return true; // Stack already guarded or guard pages not needed.
1547 }
1548
1549 if (register_stack_overflow()) {
1550 // For those architectures which have separate register and
1551 // memory stacks, we must check the register stack to see if
1552 // it has overflowed.
1553 return false;
1554 }
1555
1556 // Java code never executes within the yellow zone: the latter is only
1557 // there to provoke an exception during stack banging. If java code
1558 // is executing there, either StackShadowPages should be larger, or
1559 // some exception code in c1, c2 or the interpreter isn't unwinding
1560 // when it should.
1561 guarantee(cur_sp > stack_reserved_zone_base(),
1562 "not enough space to reguard - increase StackShadowPages");
1563 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1564 enable_stack_yellow_reserved_zone();
1565 if (reserved_stack_activation() != stack_base()) {
1566 set_reserved_stack_activation(stack_base());
1567 }
1568 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1569 set_reserved_stack_activation(stack_base());
1570 enable_stack_reserved_zone();
1571 }
1572 return true;
1573 }
1574
1575 bool JavaThread::reguard_stack(void) {
1576 return reguard_stack(os::current_stack_pointer());
1577 }
1578
1579
1580 void JavaThread::block_if_vm_exited() {
1581 if (_terminated == _vm_exited) {
1582 // _vm_exited is set at safepoint, and Threads_lock is never released
1583 // we will block here forever
1584 Threads_lock->lock_without_safepoint_check();
1585 ShouldNotReachHere();
1586 }
1587 }
1588
1589
1590 // Remove this ifdef when C1 is ported to the compiler interface.
1591 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1592 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1593
1594 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1595 Thread()
1596 #if INCLUDE_ALL_GCS
1597 , _satb_mark_queue(&_satb_mark_queue_set),
1598 _dirty_card_queue(&_dirty_card_queue_set)
1599 #endif // INCLUDE_ALL_GCS
1600 {
1601 initialize();
1602 _jni_attach_state = _not_attaching_via_jni;
1603 set_entry_point(entry_point);
1604 // Create the native thread itself.
1605 // %note runtime_23
1606 os::ThreadType thr_type = os::java_thread;
1607 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1608 os::java_thread;
1609 os::create_thread(this, thr_type, stack_sz);
1610 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1611 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1612 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1613 // the exception consists of creating the exception object & initializing it, initialization
1614 // will leave the VM via a JavaCall and then all locks must be unlocked).
1615 //
1616 // The thread is still suspended when we reach here. Thread must be explicit started
1617 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1618 // by calling Threads:add. The reason why this is not done here, is because the thread
1619 // object must be fully initialized (take a look at JVM_Start)
1620 }
1621
1622 JavaThread::~JavaThread() {
1623
1624 // JSR166 -- return the parker to the free list
1625 Parker::Release(_parker);
1626 _parker = NULL;
1627
1628 // Free any remaining previous UnrollBlock
1629 vframeArray* old_array = vframe_array_last();
1630
1631 if (old_array != NULL) {
1632 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1633 old_array->set_unroll_block(NULL);
1634 delete old_info;
1635 delete old_array;
1636 }
1637
1638 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1639 if (deferred != NULL) {
1640 // This can only happen if thread is destroyed before deoptimization occurs.
1641 assert(deferred->length() != 0, "empty array!");
1642 do {
1643 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1644 deferred->remove_at(0);
1645 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1646 delete dlv;
1647 } while (deferred->length() != 0);
1648 delete deferred;
1649 }
1650
1651 // All Java related clean up happens in exit
1652 ThreadSafepointState::destroy(this);
1653 if (_thread_profiler != NULL) delete _thread_profiler;
1654 if (_thread_stat != NULL) delete _thread_stat;
1655
1656 #if INCLUDE_JVMCI
1657 if (JVMCICounterSize > 0) {
1658 if (jvmci_counters_include(this)) {
1659 for (int i = 0; i < JVMCICounterSize; i++) {
1660 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1661 }
1662 }
1663 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1664 }
1665 #endif // INCLUDE_JVMCI
1666 }
1667
1668
1669 // The first routine called by a new Java thread
1670 void JavaThread::run() {
1671 // initialize thread-local alloc buffer related fields
1672 this->initialize_tlab();
1673
1674 // used to test validity of stack trace backs
1675 this->record_base_of_stack_pointer();
1676
1677 // Record real stack base and size.
1678 this->record_stack_base_and_size();
1679
1680 this->create_stack_guard_pages();
1681
1682 this->cache_global_variables();
1683
1684 // Thread is now sufficient initialized to be handled by the safepoint code as being
1685 // in the VM. Change thread state from _thread_new to _thread_in_vm
1686 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1687
1688 assert(JavaThread::current() == this, "sanity check");
1689 assert(!Thread::current()->owns_locks(), "sanity check");
1690
1691 DTRACE_THREAD_PROBE(start, this);
1692
1693 // This operation might block. We call that after all safepoint checks for a new thread has
1694 // been completed.
1695 this->set_active_handles(JNIHandleBlock::allocate_block());
1696
1697 if (JvmtiExport::should_post_thread_life()) {
1698 JvmtiExport::post_thread_start(this);
1699 }
1700
1701 EventThreadStart event;
1702 if (event.should_commit()) {
1703 event.set_thread(THREAD_TRACE_ID(this));
1704 event.commit();
1705 }
1706
1707 // We call another function to do the rest so we are sure that the stack addresses used
1708 // from there will be lower than the stack base just computed
1709 thread_main_inner();
1710
1711 // Note, thread is no longer valid at this point!
1712 }
1713
1714
1715 void JavaThread::thread_main_inner() {
1716 assert(JavaThread::current() == this, "sanity check");
1717 assert(this->threadObj() != NULL, "just checking");
1718
1719 // Execute thread entry point unless this thread has a pending exception
1720 // or has been stopped before starting.
1721 // Note: Due to JVM_StopThread we can have pending exceptions already!
1722 if (!this->has_pending_exception() &&
1723 !java_lang_Thread::is_stillborn(this->threadObj())) {
1724 {
1725 ResourceMark rm(this);
1726 this->set_native_thread_name(this->get_thread_name());
1727 }
1728 HandleMark hm(this);
1729 this->entry_point()(this, this);
1730 }
1731
1732 DTRACE_THREAD_PROBE(stop, this);
1733
1734 this->exit(false);
1735 delete this;
1736 }
1737
1738
1739 static void ensure_join(JavaThread* thread) {
1740 // We do not need to grap the Threads_lock, since we are operating on ourself.
1741 Handle threadObj(thread, thread->threadObj());
1742 assert(threadObj.not_null(), "java thread object must exist");
1743 ObjectLocker lock(threadObj, thread);
1744 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1745 thread->clear_pending_exception();
1746 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1747 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1748 // Clear the native thread instance - this makes isAlive return false and allows the join()
1749 // to complete once we've done the notify_all below
1750 java_lang_Thread::set_thread(threadObj(), NULL);
1751 lock.notify_all(thread);
1752 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1753 thread->clear_pending_exception();
1754 }
1755
1756
1757 // For any new cleanup additions, please check to see if they need to be applied to
1758 // cleanup_failed_attach_current_thread as well.
1759 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1760 assert(this == JavaThread::current(), "thread consistency check");
1761
1762 HandleMark hm(this);
1763 Handle uncaught_exception(this, this->pending_exception());
1764 this->clear_pending_exception();
1765 Handle threadObj(this, this->threadObj());
1766 assert(threadObj.not_null(), "Java thread object should be created");
1767
1768 if (get_thread_profiler() != NULL) {
1769 get_thread_profiler()->disengage();
1770 ResourceMark rm;
1771 get_thread_profiler()->print(get_thread_name());
1772 }
1773
1774
1775 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1776 {
1777 EXCEPTION_MARK;
1778
1779 CLEAR_PENDING_EXCEPTION;
1780 }
1781 if (!destroy_vm) {
1782 if (uncaught_exception.not_null()) {
1783 EXCEPTION_MARK;
1784 // Call method Thread.dispatchUncaughtException().
1785 Klass* thread_klass = SystemDictionary::Thread_klass();
1786 JavaValue result(T_VOID);
1787 JavaCalls::call_virtual(&result,
1788 threadObj, thread_klass,
1789 vmSymbols::dispatchUncaughtException_name(),
1790 vmSymbols::throwable_void_signature(),
1791 uncaught_exception,
1792 THREAD);
1793 if (HAS_PENDING_EXCEPTION) {
1794 ResourceMark rm(this);
1795 jio_fprintf(defaultStream::error_stream(),
1796 "\nException: %s thrown from the UncaughtExceptionHandler"
1797 " in thread \"%s\"\n",
1798 pending_exception()->klass()->external_name(),
1799 get_thread_name());
1800 CLEAR_PENDING_EXCEPTION;
1801 }
1802 }
1803
1804 // Called before the java thread exit since we want to read info
1805 // from java_lang_Thread object
1806 EventThreadEnd event;
1807 if (event.should_commit()) {
1808 event.set_thread(THREAD_TRACE_ID(this));
1809 event.commit();
1810 }
1811
1812 // Call after last event on thread
1813 EVENT_THREAD_EXIT(this);
1814
1815 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1816 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1817 // is deprecated anyhow.
1818 if (!is_Compiler_thread()) {
1819 int count = 3;
1820 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1821 EXCEPTION_MARK;
1822 JavaValue result(T_VOID);
1823 Klass* thread_klass = SystemDictionary::Thread_klass();
1824 JavaCalls::call_virtual(&result,
1825 threadObj, thread_klass,
1826 vmSymbols::exit_method_name(),
1827 vmSymbols::void_method_signature(),
1828 THREAD);
1829 CLEAR_PENDING_EXCEPTION;
1830 }
1831 }
1832 // notify JVMTI
1833 if (JvmtiExport::should_post_thread_life()) {
1834 JvmtiExport::post_thread_end(this);
1835 }
1836
1837 // We have notified the agents that we are exiting, before we go on,
1838 // we must check for a pending external suspend request and honor it
1839 // in order to not surprise the thread that made the suspend request.
1840 while (true) {
1841 {
1842 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1843 if (!is_external_suspend()) {
1844 set_terminated(_thread_exiting);
1845 ThreadService::current_thread_exiting(this);
1846 break;
1847 }
1848 // Implied else:
1849 // Things get a little tricky here. We have a pending external
1850 // suspend request, but we are holding the SR_lock so we
1851 // can't just self-suspend. So we temporarily drop the lock
1852 // and then self-suspend.
1853 }
1854
1855 ThreadBlockInVM tbivm(this);
1856 java_suspend_self();
1857
1858 // We're done with this suspend request, but we have to loop around
1859 // and check again. Eventually we will get SR_lock without a pending
1860 // external suspend request and will be able to mark ourselves as
1861 // exiting.
1862 }
1863 // no more external suspends are allowed at this point
1864 } else {
1865 // before_exit() has already posted JVMTI THREAD_END events
1866 }
1867
1868 // Notify waiters on thread object. This has to be done after exit() is called
1869 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1870 // group should have the destroyed bit set before waiters are notified).
1871 ensure_join(this);
1872 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1873
1874 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1875 // held by this thread must be released. The spec does not distinguish
1876 // between JNI-acquired and regular Java monitors. We can only see
1877 // regular Java monitors here if monitor enter-exit matching is broken.
1878 //
1879 // Optionally release any monitors for regular JavaThread exits. This
1880 // is provided as a work around for any bugs in monitor enter-exit
1881 // matching. This can be expensive so it is not enabled by default.
1882 //
1883 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1884 // ObjectSynchronizer::release_monitors_owned_by_thread().
1885 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1886 // Sanity check even though JNI DetachCurrentThread() would have
1887 // returned JNI_ERR if there was a Java frame. JavaThread exit
1888 // should be done executing Java code by the time we get here.
1889 assert(!this->has_last_Java_frame(),
1890 "should not have a Java frame when detaching or exiting");
1891 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1892 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1893 }
1894
1895 // These things needs to be done while we are still a Java Thread. Make sure that thread
1896 // is in a consistent state, in case GC happens
1897 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1898
1899 if (active_handles() != NULL) {
1900 JNIHandleBlock* block = active_handles();
1901 set_active_handles(NULL);
1902 JNIHandleBlock::release_block(block);
1903 }
1904
1905 if (free_handle_block() != NULL) {
1906 JNIHandleBlock* block = free_handle_block();
1907 set_free_handle_block(NULL);
1908 JNIHandleBlock::release_block(block);
1909 }
1910
1911 // These have to be removed while this is still a valid thread.
1912 remove_stack_guard_pages();
1913
1914 if (UseTLAB) {
1915 tlab().make_parsable(true); // retire TLAB
1916 }
1917
1918 if (JvmtiEnv::environments_might_exist()) {
1919 JvmtiExport::cleanup_thread(this);
1920 }
1921
1922 // We must flush any deferred card marks before removing a thread from
1923 // the list of active threads.
1924 Universe::heap()->flush_deferred_store_barrier(this);
1925 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1926
1927 #if INCLUDE_ALL_GCS
1928 // We must flush the G1-related buffers before removing a thread
1929 // from the list of active threads. We must do this after any deferred
1930 // card marks have been flushed (above) so that any entries that are
1931 // added to the thread's dirty card queue as a result are not lost.
1932 if (UseG1GC) {
1933 flush_barrier_queues();
1934 }
1935 #endif // INCLUDE_ALL_GCS
1936
1937 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1938 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1939 os::current_thread_id());
1940
1941 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1942 Threads::remove(this);
1943 }
1944
1945 #if INCLUDE_ALL_GCS
1946 // Flush G1-related queues.
1947 void JavaThread::flush_barrier_queues() {
1948 satb_mark_queue().flush();
1949 dirty_card_queue().flush();
1950 }
1951
1952 void JavaThread::initialize_queues() {
1953 assert(!SafepointSynchronize::is_at_safepoint(),
1954 "we should not be at a safepoint");
1955
1956 SATBMarkQueue& satb_queue = satb_mark_queue();
1957 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1958 // The SATB queue should have been constructed with its active
1959 // field set to false.
1960 assert(!satb_queue.is_active(), "SATB queue should not be active");
1961 assert(satb_queue.is_empty(), "SATB queue should be empty");
1962 // If we are creating the thread during a marking cycle, we should
1963 // set the active field of the SATB queue to true.
1964 if (satb_queue_set.is_active()) {
1965 satb_queue.set_active(true);
1966 }
1967
1968 DirtyCardQueue& dirty_queue = dirty_card_queue();
1969 // The dirty card queue should have been constructed with its
1970 // active field set to true.
1971 assert(dirty_queue.is_active(), "dirty card queue should be active");
1972 }
1973 #endif // INCLUDE_ALL_GCS
1974
1975 void JavaThread::cleanup_failed_attach_current_thread() {
1976 if (get_thread_profiler() != NULL) {
1977 get_thread_profiler()->disengage();
1978 ResourceMark rm;
1979 get_thread_profiler()->print(get_thread_name());
1980 }
1981
1982 if (active_handles() != NULL) {
1983 JNIHandleBlock* block = active_handles();
1984 set_active_handles(NULL);
1985 JNIHandleBlock::release_block(block);
1986 }
1987
1988 if (free_handle_block() != NULL) {
1989 JNIHandleBlock* block = free_handle_block();
1990 set_free_handle_block(NULL);
1991 JNIHandleBlock::release_block(block);
1992 }
1993
1994 // These have to be removed while this is still a valid thread.
1995 remove_stack_guard_pages();
1996
1997 if (UseTLAB) {
1998 tlab().make_parsable(true); // retire TLAB, if any
1999 }
2000
2001 #if INCLUDE_ALL_GCS
2002 if (UseG1GC) {
2003 flush_barrier_queues();
2004 }
2005 #endif // INCLUDE_ALL_GCS
2006
2007 Threads::remove(this);
2008 delete this;
2009 }
2010
2011
2012
2013
2014 JavaThread* JavaThread::active() {
2015 Thread* thread = Thread::current();
2016 if (thread->is_Java_thread()) {
2017 return (JavaThread*) thread;
2018 } else {
2019 assert(thread->is_VM_thread(), "this must be a vm thread");
2020 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2021 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2022 assert(ret->is_Java_thread(), "must be a Java thread");
2023 return ret;
2024 }
2025 }
2026
2027 bool JavaThread::is_lock_owned(address adr) const {
2028 if (Thread::is_lock_owned(adr)) return true;
2029
2030 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2031 if (chunk->contains(adr)) return true;
2032 }
2033
2034 return false;
2035 }
2036
2037
2038 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2039 chunk->set_next(monitor_chunks());
2040 set_monitor_chunks(chunk);
2041 }
2042
2043 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2044 guarantee(monitor_chunks() != NULL, "must be non empty");
2045 if (monitor_chunks() == chunk) {
2046 set_monitor_chunks(chunk->next());
2047 } else {
2048 MonitorChunk* prev = monitor_chunks();
2049 while (prev->next() != chunk) prev = prev->next();
2050 prev->set_next(chunk->next());
2051 }
2052 }
2053
2054 // JVM support.
2055
2056 // Note: this function shouldn't block if it's called in
2057 // _thread_in_native_trans state (such as from
2058 // check_special_condition_for_native_trans()).
2059 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2060
2061 if (has_last_Java_frame() && has_async_condition()) {
2062 // If we are at a polling page safepoint (not a poll return)
2063 // then we must defer async exception because live registers
2064 // will be clobbered by the exception path. Poll return is
2065 // ok because the call we a returning from already collides
2066 // with exception handling registers and so there is no issue.
2067 // (The exception handling path kills call result registers but
2068 // this is ok since the exception kills the result anyway).
2069
2070 if (is_at_poll_safepoint()) {
2071 // if the code we are returning to has deoptimized we must defer
2072 // the exception otherwise live registers get clobbered on the
2073 // exception path before deoptimization is able to retrieve them.
2074 //
2075 RegisterMap map(this, false);
2076 frame caller_fr = last_frame().sender(&map);
2077 assert(caller_fr.is_compiled_frame(), "what?");
2078 if (caller_fr.is_deoptimized_frame()) {
2079 log_info(exceptions)("deferred async exception at compiled safepoint");
2080 return;
2081 }
2082 }
2083 }
2084
2085 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2086 if (condition == _no_async_condition) {
2087 // Conditions have changed since has_special_runtime_exit_condition()
2088 // was called:
2089 // - if we were here only because of an external suspend request,
2090 // then that was taken care of above (or cancelled) so we are done
2091 // - if we were here because of another async request, then it has
2092 // been cleared between the has_special_runtime_exit_condition()
2093 // and now so again we are done
2094 return;
2095 }
2096
2097 // Check for pending async. exception
2098 if (_pending_async_exception != NULL) {
2099 // Only overwrite an already pending exception, if it is not a threadDeath.
2100 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2101
2102 // We cannot call Exceptions::_throw(...) here because we cannot block
2103 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2104
2105 LogTarget(Info, exceptions) lt;
2106 if (lt.is_enabled()) {
2107 ResourceMark rm;
2108 LogStream ls(lt);
2109 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2110 if (has_last_Java_frame()) {
2111 frame f = last_frame();
2112 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2113 }
2114 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2115 }
2116 _pending_async_exception = NULL;
2117 clear_has_async_exception();
2118 }
2119 }
2120
2121 if (check_unsafe_error &&
2122 condition == _async_unsafe_access_error && !has_pending_exception()) {
2123 condition = _no_async_condition; // done
2124 switch (thread_state()) {
2125 case _thread_in_vm: {
2126 JavaThread* THREAD = this;
2127 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2128 }
2129 case _thread_in_native: {
2130 ThreadInVMfromNative tiv(this);
2131 JavaThread* THREAD = this;
2132 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2133 }
2134 case _thread_in_Java: {
2135 ThreadInVMfromJava tiv(this);
2136 JavaThread* THREAD = this;
2137 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2138 }
2139 default:
2140 ShouldNotReachHere();
2141 }
2142 }
2143
2144 assert(condition == _no_async_condition || has_pending_exception() ||
2145 (!check_unsafe_error && condition == _async_unsafe_access_error),
2146 "must have handled the async condition, if no exception");
2147 }
2148
2149 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2150 //
2151 // Check for pending external suspend. Internal suspend requests do
2152 // not use handle_special_runtime_exit_condition().
2153 // If JNIEnv proxies are allowed, don't self-suspend if the target
2154 // thread is not the current thread. In older versions of jdbx, jdbx
2155 // threads could call into the VM with another thread's JNIEnv so we
2156 // can be here operating on behalf of a suspended thread (4432884).
2157 bool do_self_suspend = is_external_suspend_with_lock();
2158 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2159 //
2160 // Because thread is external suspended the safepoint code will count
2161 // thread as at a safepoint. This can be odd because we can be here
2162 // as _thread_in_Java which would normally transition to _thread_blocked
2163 // at a safepoint. We would like to mark the thread as _thread_blocked
2164 // before calling java_suspend_self like all other callers of it but
2165 // we must then observe proper safepoint protocol. (We can't leave
2166 // _thread_blocked with a safepoint in progress). However we can be
2167 // here as _thread_in_native_trans so we can't use a normal transition
2168 // constructor/destructor pair because they assert on that type of
2169 // transition. We could do something like:
2170 //
2171 // JavaThreadState state = thread_state();
2172 // set_thread_state(_thread_in_vm);
2173 // {
2174 // ThreadBlockInVM tbivm(this);
2175 // java_suspend_self()
2176 // }
2177 // set_thread_state(_thread_in_vm_trans);
2178 // if (safepoint) block;
2179 // set_thread_state(state);
2180 //
2181 // but that is pretty messy. Instead we just go with the way the
2182 // code has worked before and note that this is the only path to
2183 // java_suspend_self that doesn't put the thread in _thread_blocked
2184 // mode.
2185
2186 frame_anchor()->make_walkable(this);
2187 java_suspend_self();
2188
2189 // We might be here for reasons in addition to the self-suspend request
2190 // so check for other async requests.
2191 }
2192
2193 if (check_asyncs) {
2194 check_and_handle_async_exceptions();
2195 }
2196 }
2197
2198 void JavaThread::send_thread_stop(oop java_throwable) {
2199 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2200 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2201 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2202
2203 // Do not throw asynchronous exceptions against the compiler thread
2204 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2205 if (!can_call_java()) return;
2206
2207 {
2208 // Actually throw the Throwable against the target Thread - however
2209 // only if there is no thread death exception installed already.
2210 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2211 // If the topmost frame is a runtime stub, then we are calling into
2212 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2213 // must deoptimize the caller before continuing, as the compiled exception handler table
2214 // may not be valid
2215 if (has_last_Java_frame()) {
2216 frame f = last_frame();
2217 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2218 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2219 RegisterMap reg_map(this, UseBiasedLocking);
2220 frame compiled_frame = f.sender(®_map);
2221 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2222 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2223 }
2224 }
2225 }
2226
2227 // Set async. pending exception in thread.
2228 set_pending_async_exception(java_throwable);
2229
2230 if (log_is_enabled(Info, exceptions)) {
2231 ResourceMark rm;
2232 log_info(exceptions)("Pending Async. exception installed of type: %s",
2233 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2234 }
2235 // for AbortVMOnException flag
2236 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2237 }
2238 }
2239
2240
2241 // Interrupt thread so it will wake up from a potential wait()
2242 Thread::interrupt(this);
2243 }
2244
2245 // External suspension mechanism.
2246 //
2247 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2248 // to any VM_locks and it is at a transition
2249 // Self-suspension will happen on the transition out of the vm.
2250 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2251 //
2252 // Guarantees on return:
2253 // + Target thread will not execute any new bytecode (that's why we need to
2254 // force a safepoint)
2255 // + Target thread will not enter any new monitors
2256 //
2257 void JavaThread::java_suspend() {
2258 { MutexLocker mu(Threads_lock);
2259 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2260 return;
2261 }
2262 }
2263
2264 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2265 if (!is_external_suspend()) {
2266 // a racing resume has cancelled us; bail out now
2267 return;
2268 }
2269
2270 // suspend is done
2271 uint32_t debug_bits = 0;
2272 // Warning: is_ext_suspend_completed() may temporarily drop the
2273 // SR_lock to allow the thread to reach a stable thread state if
2274 // it is currently in a transient thread state.
2275 if (is_ext_suspend_completed(false /* !called_by_wait */,
2276 SuspendRetryDelay, &debug_bits)) {
2277 return;
2278 }
2279 }
2280
2281 VM_ThreadSuspend vm_suspend;
2282 VMThread::execute(&vm_suspend);
2283 }
2284
2285 // Part II of external suspension.
2286 // A JavaThread self suspends when it detects a pending external suspend
2287 // request. This is usually on transitions. It is also done in places
2288 // where continuing to the next transition would surprise the caller,
2289 // e.g., monitor entry.
2290 //
2291 // Returns the number of times that the thread self-suspended.
2292 //
2293 // Note: DO NOT call java_suspend_self() when you just want to block current
2294 // thread. java_suspend_self() is the second stage of cooperative
2295 // suspension for external suspend requests and should only be used
2296 // to complete an external suspend request.
2297 //
2298 int JavaThread::java_suspend_self() {
2299 int ret = 0;
2300
2301 // we are in the process of exiting so don't suspend
2302 if (is_exiting()) {
2303 clear_external_suspend();
2304 return ret;
2305 }
2306
2307 assert(_anchor.walkable() ||
2308 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2309 "must have walkable stack");
2310
2311 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2312
2313 assert(!this->is_ext_suspended(),
2314 "a thread trying to self-suspend should not already be suspended");
2315
2316 if (this->is_suspend_equivalent()) {
2317 // If we are self-suspending as a result of the lifting of a
2318 // suspend equivalent condition, then the suspend_equivalent
2319 // flag is not cleared until we set the ext_suspended flag so
2320 // that wait_for_ext_suspend_completion() returns consistent
2321 // results.
2322 this->clear_suspend_equivalent();
2323 }
2324
2325 // A racing resume may have cancelled us before we grabbed SR_lock
2326 // above. Or another external suspend request could be waiting for us
2327 // by the time we return from SR_lock()->wait(). The thread
2328 // that requested the suspension may already be trying to walk our
2329 // stack and if we return now, we can change the stack out from under
2330 // it. This would be a "bad thing (TM)" and cause the stack walker
2331 // to crash. We stay self-suspended until there are no more pending
2332 // external suspend requests.
2333 while (is_external_suspend()) {
2334 ret++;
2335 this->set_ext_suspended();
2336
2337 // _ext_suspended flag is cleared by java_resume()
2338 while (is_ext_suspended()) {
2339 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2340 }
2341 }
2342
2343 return ret;
2344 }
2345
2346 #ifdef ASSERT
2347 // verify the JavaThread has not yet been published in the Threads::list, and
2348 // hence doesn't need protection from concurrent access at this stage
2349 void JavaThread::verify_not_published() {
2350 if (!Threads_lock->owned_by_self()) {
2351 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2352 assert(!Threads::includes(this),
2353 "java thread shouldn't have been published yet!");
2354 } else {
2355 assert(!Threads::includes(this),
2356 "java thread shouldn't have been published yet!");
2357 }
2358 }
2359 #endif
2360
2361 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2362 // progress or when _suspend_flags is non-zero.
2363 // Current thread needs to self-suspend if there is a suspend request and/or
2364 // block if a safepoint is in progress.
2365 // Async exception ISN'T checked.
2366 // Note only the ThreadInVMfromNative transition can call this function
2367 // directly and when thread state is _thread_in_native_trans
2368 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2369 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2370
2371 JavaThread *curJT = JavaThread::current();
2372 bool do_self_suspend = thread->is_external_suspend();
2373
2374 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2375
2376 // If JNIEnv proxies are allowed, don't self-suspend if the target
2377 // thread is not the current thread. In older versions of jdbx, jdbx
2378 // threads could call into the VM with another thread's JNIEnv so we
2379 // can be here operating on behalf of a suspended thread (4432884).
2380 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2381 JavaThreadState state = thread->thread_state();
2382
2383 // We mark this thread_blocked state as a suspend-equivalent so
2384 // that a caller to is_ext_suspend_completed() won't be confused.
2385 // The suspend-equivalent state is cleared by java_suspend_self().
2386 thread->set_suspend_equivalent();
2387
2388 // If the safepoint code sees the _thread_in_native_trans state, it will
2389 // wait until the thread changes to other thread state. There is no
2390 // guarantee on how soon we can obtain the SR_lock and complete the
2391 // self-suspend request. It would be a bad idea to let safepoint wait for
2392 // too long. Temporarily change the state to _thread_blocked to
2393 // let the VM thread know that this thread is ready for GC. The problem
2394 // of changing thread state is that safepoint could happen just after
2395 // java_suspend_self() returns after being resumed, and VM thread will
2396 // see the _thread_blocked state. We must check for safepoint
2397 // after restoring the state and make sure we won't leave while a safepoint
2398 // is in progress.
2399 thread->set_thread_state(_thread_blocked);
2400 thread->java_suspend_self();
2401 thread->set_thread_state(state);
2402 // Make sure new state is seen by VM thread
2403 if (os::is_MP()) {
2404 if (UseMembar) {
2405 // Force a fence between the write above and read below
2406 OrderAccess::fence();
2407 } else {
2408 // Must use this rather than serialization page in particular on Windows
2409 InterfaceSupport::serialize_memory(thread);
2410 }
2411 }
2412 }
2413
2414 if (SafepointSynchronize::do_call_back()) {
2415 // If we are safepointing, then block the caller which may not be
2416 // the same as the target thread (see above).
2417 SafepointSynchronize::block(curJT);
2418 }
2419
2420 if (thread->is_deopt_suspend()) {
2421 thread->clear_deopt_suspend();
2422 RegisterMap map(thread, false);
2423 frame f = thread->last_frame();
2424 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2425 f = f.sender(&map);
2426 }
2427 if (f.id() == thread->must_deopt_id()) {
2428 thread->clear_must_deopt_id();
2429 f.deoptimize(thread);
2430 } else {
2431 fatal("missed deoptimization!");
2432 }
2433 }
2434 }
2435
2436 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2437 // progress or when _suspend_flags is non-zero.
2438 // Current thread needs to self-suspend if there is a suspend request and/or
2439 // block if a safepoint is in progress.
2440 // Also check for pending async exception (not including unsafe access error).
2441 // Note only the native==>VM/Java barriers can call this function and when
2442 // thread state is _thread_in_native_trans.
2443 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2444 check_safepoint_and_suspend_for_native_trans(thread);
2445
2446 if (thread->has_async_exception()) {
2447 // We are in _thread_in_native_trans state, don't handle unsafe
2448 // access error since that may block.
2449 thread->check_and_handle_async_exceptions(false);
2450 }
2451 }
2452
2453 // This is a variant of the normal
2454 // check_special_condition_for_native_trans with slightly different
2455 // semantics for use by critical native wrappers. It does all the
2456 // normal checks but also performs the transition back into
2457 // thread_in_Java state. This is required so that critical natives
2458 // can potentially block and perform a GC if they are the last thread
2459 // exiting the GCLocker.
2460 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2461 check_special_condition_for_native_trans(thread);
2462
2463 // Finish the transition
2464 thread->set_thread_state(_thread_in_Java);
2465
2466 if (thread->do_critical_native_unlock()) {
2467 ThreadInVMfromJavaNoAsyncException tiv(thread);
2468 GCLocker::unlock_critical(thread);
2469 thread->clear_critical_native_unlock();
2470 }
2471 }
2472
2473 // We need to guarantee the Threads_lock here, since resumes are not
2474 // allowed during safepoint synchronization
2475 // Can only resume from an external suspension
2476 void JavaThread::java_resume() {
2477 assert_locked_or_safepoint(Threads_lock);
2478
2479 // Sanity check: thread is gone, has started exiting or the thread
2480 // was not externally suspended.
2481 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2482 return;
2483 }
2484
2485 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2486
2487 clear_external_suspend();
2488
2489 if (is_ext_suspended()) {
2490 clear_ext_suspended();
2491 SR_lock()->notify_all();
2492 }
2493 }
2494
2495 size_t JavaThread::_stack_red_zone_size = 0;
2496 size_t JavaThread::_stack_yellow_zone_size = 0;
2497 size_t JavaThread::_stack_reserved_zone_size = 0;
2498 size_t JavaThread::_stack_shadow_zone_size = 0;
2499
2500 void JavaThread::create_stack_guard_pages() {
2501 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2502 address low_addr = stack_end();
2503 size_t len = stack_guard_zone_size();
2504
2505 int must_commit = os::must_commit_stack_guard_pages();
2506 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2507
2508 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2509 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2510 return;
2511 }
2512
2513 if (os::guard_memory((char *) low_addr, len)) {
2514 _stack_guard_state = stack_guard_enabled;
2515 } else {
2516 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2517 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2518 if (os::uncommit_memory((char *) low_addr, len)) {
2519 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2520 }
2521 return;
2522 }
2523
2524 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2525 PTR_FORMAT "-" PTR_FORMAT ".",
2526 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2527 }
2528
2529 void JavaThread::remove_stack_guard_pages() {
2530 assert(Thread::current() == this, "from different thread");
2531 if (_stack_guard_state == stack_guard_unused) return;
2532 address low_addr = stack_end();
2533 size_t len = stack_guard_zone_size();
2534
2535 if (os::must_commit_stack_guard_pages()) {
2536 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2537 _stack_guard_state = stack_guard_unused;
2538 } else {
2539 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2540 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2541 return;
2542 }
2543 } else {
2544 if (_stack_guard_state == stack_guard_unused) return;
2545 if (os::unguard_memory((char *) low_addr, len)) {
2546 _stack_guard_state = stack_guard_unused;
2547 } else {
2548 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2549 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2550 return;
2551 }
2552 }
2553
2554 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2555 PTR_FORMAT "-" PTR_FORMAT ".",
2556 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2557 }
2558
2559 void JavaThread::enable_stack_reserved_zone() {
2560 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2561 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2562
2563 // The base notation is from the stack's point of view, growing downward.
2564 // We need to adjust it to work correctly with guard_memory()
2565 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2566
2567 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2568 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2569
2570 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2571 _stack_guard_state = stack_guard_enabled;
2572 } else {
2573 warning("Attempt to guard stack reserved zone failed.");
2574 }
2575 enable_register_stack_guard();
2576 }
2577
2578 void JavaThread::disable_stack_reserved_zone() {
2579 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2580 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2581
2582 // Simply return if called for a thread that does not use guard pages.
2583 if (_stack_guard_state == stack_guard_unused) return;
2584
2585 // The base notation is from the stack's point of view, growing downward.
2586 // We need to adjust it to work correctly with guard_memory()
2587 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2588
2589 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2590 _stack_guard_state = stack_guard_reserved_disabled;
2591 } else {
2592 warning("Attempt to unguard stack reserved zone failed.");
2593 }
2594 disable_register_stack_guard();
2595 }
2596
2597 void JavaThread::enable_stack_yellow_reserved_zone() {
2598 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2599 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2600
2601 // The base notation is from the stacks point of view, growing downward.
2602 // We need to adjust it to work correctly with guard_memory()
2603 address base = stack_red_zone_base();
2604
2605 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2606 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2607
2608 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2609 _stack_guard_state = stack_guard_enabled;
2610 } else {
2611 warning("Attempt to guard stack yellow zone failed.");
2612 }
2613 enable_register_stack_guard();
2614 }
2615
2616 void JavaThread::disable_stack_yellow_reserved_zone() {
2617 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2618 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2619
2620 // Simply return if called for a thread that does not use guard pages.
2621 if (_stack_guard_state == stack_guard_unused) return;
2622
2623 // The base notation is from the stacks point of view, growing downward.
2624 // We need to adjust it to work correctly with guard_memory()
2625 address base = stack_red_zone_base();
2626
2627 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2628 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2629 } else {
2630 warning("Attempt to unguard stack yellow zone failed.");
2631 }
2632 disable_register_stack_guard();
2633 }
2634
2635 void JavaThread::enable_stack_red_zone() {
2636 // The base notation is from the stacks point of view, growing downward.
2637 // We need to adjust it to work correctly with guard_memory()
2638 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2639 address base = stack_red_zone_base() - stack_red_zone_size();
2640
2641 guarantee(base < stack_base(), "Error calculating stack red zone");
2642 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2643
2644 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2645 warning("Attempt to guard stack red zone failed.");
2646 }
2647 }
2648
2649 void JavaThread::disable_stack_red_zone() {
2650 // The base notation is from the stacks point of view, growing downward.
2651 // We need to adjust it to work correctly with guard_memory()
2652 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2653 address base = stack_red_zone_base() - stack_red_zone_size();
2654 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2655 warning("Attempt to unguard stack red zone failed.");
2656 }
2657 }
2658
2659 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2660 // ignore is there is no stack
2661 if (!has_last_Java_frame()) return;
2662 // traverse the stack frames. Starts from top frame.
2663 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2664 frame* fr = fst.current();
2665 f(fr, fst.register_map());
2666 }
2667 }
2668
2669
2670 #ifndef PRODUCT
2671 // Deoptimization
2672 // Function for testing deoptimization
2673 void JavaThread::deoptimize() {
2674 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2675 StackFrameStream fst(this, UseBiasedLocking);
2676 bool deopt = false; // Dump stack only if a deopt actually happens.
2677 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2678 // Iterate over all frames in the thread and deoptimize
2679 for (; !fst.is_done(); fst.next()) {
2680 if (fst.current()->can_be_deoptimized()) {
2681
2682 if (only_at) {
2683 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2684 // consists of comma or carriage return separated numbers so
2685 // search for the current bci in that string.
2686 address pc = fst.current()->pc();
2687 nmethod* nm = (nmethod*) fst.current()->cb();
2688 ScopeDesc* sd = nm->scope_desc_at(pc);
2689 char buffer[8];
2690 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2691 size_t len = strlen(buffer);
2692 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2693 while (found != NULL) {
2694 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2695 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2696 // Check that the bci found is bracketed by terminators.
2697 break;
2698 }
2699 found = strstr(found + 1, buffer);
2700 }
2701 if (!found) {
2702 continue;
2703 }
2704 }
2705
2706 if (DebugDeoptimization && !deopt) {
2707 deopt = true; // One-time only print before deopt
2708 tty->print_cr("[BEFORE Deoptimization]");
2709 trace_frames();
2710 trace_stack();
2711 }
2712 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2713 }
2714 }
2715
2716 if (DebugDeoptimization && deopt) {
2717 tty->print_cr("[AFTER Deoptimization]");
2718 trace_frames();
2719 }
2720 }
2721
2722
2723 // Make zombies
2724 void JavaThread::make_zombies() {
2725 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2726 if (fst.current()->can_be_deoptimized()) {
2727 // it is a Java nmethod
2728 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2729 nm->make_not_entrant();
2730 }
2731 }
2732 }
2733 #endif // PRODUCT
2734
2735
2736 void JavaThread::deoptimized_wrt_marked_nmethods() {
2737 if (!has_last_Java_frame()) return;
2738 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2739 StackFrameStream fst(this, UseBiasedLocking);
2740 for (; !fst.is_done(); fst.next()) {
2741 if (fst.current()->should_be_deoptimized()) {
2742 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2743 }
2744 }
2745 }
2746
2747
2748 // If the caller is a NamedThread, then remember, in the current scope,
2749 // the given JavaThread in its _processed_thread field.
2750 class RememberProcessedThread: public StackObj {
2751 NamedThread* _cur_thr;
2752 public:
2753 RememberProcessedThread(JavaThread* jthr) {
2754 Thread* thread = Thread::current();
2755 if (thread->is_Named_thread()) {
2756 _cur_thr = (NamedThread *)thread;
2757 _cur_thr->set_processed_thread(jthr);
2758 } else {
2759 _cur_thr = NULL;
2760 }
2761 }
2762
2763 ~RememberProcessedThread() {
2764 if (_cur_thr) {
2765 _cur_thr->set_processed_thread(NULL);
2766 }
2767 }
2768 };
2769
2770 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2771 // Verify that the deferred card marks have been flushed.
2772 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2773
2774 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2775 // since there may be more than one thread using each ThreadProfiler.
2776
2777 // Traverse the GCHandles
2778 Thread::oops_do(f, cf);
2779
2780 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2781
2782 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2783 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2784
2785 if (has_last_Java_frame()) {
2786 // Record JavaThread to GC thread
2787 RememberProcessedThread rpt(this);
2788
2789 // Traverse the privileged stack
2790 if (_privileged_stack_top != NULL) {
2791 _privileged_stack_top->oops_do(f);
2792 }
2793
2794 // traverse the registered growable array
2795 if (_array_for_gc != NULL) {
2796 for (int index = 0; index < _array_for_gc->length(); index++) {
2797 f->do_oop(_array_for_gc->adr_at(index));
2798 }
2799 }
2800
2801 // Traverse the monitor chunks
2802 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2803 chunk->oops_do(f);
2804 }
2805
2806 // Traverse the execution stack
2807 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2808 fst.current()->oops_do(f, cf, fst.register_map());
2809 }
2810 }
2811
2812 // callee_target is never live across a gc point so NULL it here should
2813 // it still contain a methdOop.
2814
2815 set_callee_target(NULL);
2816
2817 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2818 // If we have deferred set_locals there might be oops waiting to be
2819 // written
2820 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2821 if (list != NULL) {
2822 for (int i = 0; i < list->length(); i++) {
2823 list->at(i)->oops_do(f);
2824 }
2825 }
2826
2827 // Traverse instance variables at the end since the GC may be moving things
2828 // around using this function
2829 f->do_oop((oop*) &_threadObj);
2830 f->do_oop((oop*) &_vm_result);
2831 f->do_oop((oop*) &_exception_oop);
2832 f->do_oop((oop*) &_pending_async_exception);
2833
2834 if (jvmti_thread_state() != NULL) {
2835 jvmti_thread_state()->oops_do(f);
2836 }
2837 }
2838
2839 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2840 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2841 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2842
2843 if (has_last_Java_frame()) {
2844 // Traverse the execution stack
2845 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2846 fst.current()->nmethods_do(cf);
2847 }
2848 }
2849 }
2850
2851 void JavaThread::metadata_do(void f(Metadata*)) {
2852 if (has_last_Java_frame()) {
2853 // Traverse the execution stack to call f() on the methods in the stack
2854 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2855 fst.current()->metadata_do(f);
2856 }
2857 } else if (is_Compiler_thread()) {
2858 // need to walk ciMetadata in current compile tasks to keep alive.
2859 CompilerThread* ct = (CompilerThread*)this;
2860 if (ct->env() != NULL) {
2861 ct->env()->metadata_do(f);
2862 }
2863 if (ct->task() != NULL) {
2864 ct->task()->metadata_do(f);
2865 }
2866 }
2867 }
2868
2869 // Printing
2870 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2871 switch (_thread_state) {
2872 case _thread_uninitialized: return "_thread_uninitialized";
2873 case _thread_new: return "_thread_new";
2874 case _thread_new_trans: return "_thread_new_trans";
2875 case _thread_in_native: return "_thread_in_native";
2876 case _thread_in_native_trans: return "_thread_in_native_trans";
2877 case _thread_in_vm: return "_thread_in_vm";
2878 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2879 case _thread_in_Java: return "_thread_in_Java";
2880 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2881 case _thread_blocked: return "_thread_blocked";
2882 case _thread_blocked_trans: return "_thread_blocked_trans";
2883 default: return "unknown thread state";
2884 }
2885 }
2886
2887 #ifndef PRODUCT
2888 void JavaThread::print_thread_state_on(outputStream *st) const {
2889 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2890 };
2891 void JavaThread::print_thread_state() const {
2892 print_thread_state_on(tty);
2893 }
2894 #endif // PRODUCT
2895
2896 // Called by Threads::print() for VM_PrintThreads operation
2897 void JavaThread::print_on(outputStream *st) const {
2898 st->print_raw("\"");
2899 st->print_raw(get_thread_name());
2900 st->print_raw("\" ");
2901 oop thread_oop = threadObj();
2902 if (thread_oop != NULL) {
2903 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2904 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2905 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2906 }
2907 Thread::print_on(st);
2908 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2909 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2910 if (thread_oop != NULL) {
2911 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2912 }
2913 #ifndef PRODUCT
2914 print_thread_state_on(st);
2915 _safepoint_state->print_on(st);
2916 #endif // PRODUCT
2917 if (is_Compiler_thread()) {
2918 CompilerThread* ct = (CompilerThread*)this;
2919 if (ct->task() != NULL) {
2920 st->print(" Compiling: ");
2921 ct->task()->print(st, NULL, true, false);
2922 } else {
2923 st->print(" No compile task");
2924 }
2925 st->cr();
2926 }
2927 }
2928
2929 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2930 st->print("%s", get_thread_name_string(buf, buflen));
2931 }
2932
2933 // Called by fatal error handler. The difference between this and
2934 // JavaThread::print() is that we can't grab lock or allocate memory.
2935 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2936 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2937 oop thread_obj = threadObj();
2938 if (thread_obj != NULL) {
2939 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2940 }
2941 st->print(" [");
2942 st->print("%s", _get_thread_state_name(_thread_state));
2943 if (osthread()) {
2944 st->print(", id=%d", osthread()->thread_id());
2945 }
2946 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2947 p2i(stack_end()), p2i(stack_base()));
2948 st->print("]");
2949 return;
2950 }
2951
2952 // Verification
2953
2954 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2955
2956 void JavaThread::verify() {
2957 // Verify oops in the thread.
2958 oops_do(&VerifyOopClosure::verify_oop, NULL);
2959
2960 // Verify the stack frames.
2961 frames_do(frame_verify);
2962 }
2963
2964 // CR 6300358 (sub-CR 2137150)
2965 // Most callers of this method assume that it can't return NULL but a
2966 // thread may not have a name whilst it is in the process of attaching to
2967 // the VM - see CR 6412693, and there are places where a JavaThread can be
2968 // seen prior to having it's threadObj set (eg JNI attaching threads and
2969 // if vm exit occurs during initialization). These cases can all be accounted
2970 // for such that this method never returns NULL.
2971 const char* JavaThread::get_thread_name() const {
2972 #ifdef ASSERT
2973 // early safepoints can hit while current thread does not yet have TLS
2974 if (!SafepointSynchronize::is_at_safepoint()) {
2975 Thread *cur = Thread::current();
2976 if (!(cur->is_Java_thread() && cur == this)) {
2977 // Current JavaThreads are allowed to get their own name without
2978 // the Threads_lock.
2979 assert_locked_or_safepoint(Threads_lock);
2980 }
2981 }
2982 #endif // ASSERT
2983 return get_thread_name_string();
2984 }
2985
2986 // Returns a non-NULL representation of this thread's name, or a suitable
2987 // descriptive string if there is no set name
2988 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2989 const char* name_str;
2990 oop thread_obj = threadObj();
2991 if (thread_obj != NULL) {
2992 oop name = java_lang_Thread::name(thread_obj);
2993 if (name != NULL) {
2994 if (buf == NULL) {
2995 name_str = java_lang_String::as_utf8_string(name);
2996 } else {
2997 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2998 }
2999 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3000 name_str = "<no-name - thread is attaching>";
3001 } else {
3002 name_str = Thread::name();
3003 }
3004 } else {
3005 name_str = Thread::name();
3006 }
3007 assert(name_str != NULL, "unexpected NULL thread name");
3008 return name_str;
3009 }
3010
3011
3012 const char* JavaThread::get_threadgroup_name() const {
3013 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3014 oop thread_obj = threadObj();
3015 if (thread_obj != NULL) {
3016 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3017 if (thread_group != NULL) {
3018 // ThreadGroup.name can be null
3019 return java_lang_ThreadGroup::name(thread_group);
3020 }
3021 }
3022 return NULL;
3023 }
3024
3025 const char* JavaThread::get_parent_name() const {
3026 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3027 oop thread_obj = threadObj();
3028 if (thread_obj != NULL) {
3029 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3030 if (thread_group != NULL) {
3031 oop parent = java_lang_ThreadGroup::parent(thread_group);
3032 if (parent != NULL) {
3033 // ThreadGroup.name can be null
3034 return java_lang_ThreadGroup::name(parent);
3035 }
3036 }
3037 }
3038 return NULL;
3039 }
3040
3041 ThreadPriority JavaThread::java_priority() const {
3042 oop thr_oop = threadObj();
3043 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3044 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3045 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3046 return priority;
3047 }
3048
3049 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3050
3051 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3052 // Link Java Thread object <-> C++ Thread
3053
3054 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3055 // and put it into a new Handle. The Handle "thread_oop" can then
3056 // be used to pass the C++ thread object to other methods.
3057
3058 // Set the Java level thread object (jthread) field of the
3059 // new thread (a JavaThread *) to C++ thread object using the
3060 // "thread_oop" handle.
3061
3062 // Set the thread field (a JavaThread *) of the
3063 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3064
3065 Handle thread_oop(Thread::current(),
3066 JNIHandles::resolve_non_null(jni_thread));
3067 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3068 "must be initialized");
3069 set_threadObj(thread_oop());
3070 java_lang_Thread::set_thread(thread_oop(), this);
3071
3072 if (prio == NoPriority) {
3073 prio = java_lang_Thread::priority(thread_oop());
3074 assert(prio != NoPriority, "A valid priority should be present");
3075 }
3076
3077 // Push the Java priority down to the native thread; needs Threads_lock
3078 Thread::set_priority(this, prio);
3079
3080 prepare_ext();
3081
3082 // Add the new thread to the Threads list and set it in motion.
3083 // We must have threads lock in order to call Threads::add.
3084 // It is crucial that we do not block before the thread is
3085 // added to the Threads list for if a GC happens, then the java_thread oop
3086 // will not be visited by GC.
3087 Threads::add(this);
3088 }
3089
3090 oop JavaThread::current_park_blocker() {
3091 // Support for JSR-166 locks
3092 oop thread_oop = threadObj();
3093 if (thread_oop != NULL &&
3094 JDK_Version::current().supports_thread_park_blocker()) {
3095 return java_lang_Thread::park_blocker(thread_oop);
3096 }
3097 return NULL;
3098 }
3099
3100
3101 void JavaThread::print_stack_on(outputStream* st) {
3102 if (!has_last_Java_frame()) return;
3103 ResourceMark rm;
3104 HandleMark hm;
3105
3106 RegisterMap reg_map(this);
3107 vframe* start_vf = last_java_vframe(®_map);
3108 int count = 0;
3109 for (vframe* f = start_vf; f; f = f->sender()) {
3110 if (f->is_java_frame()) {
3111 javaVFrame* jvf = javaVFrame::cast(f);
3112 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3113
3114 // Print out lock information
3115 if (JavaMonitorsInStackTrace) {
3116 jvf->print_lock_info_on(st, count);
3117 }
3118 } else {
3119 // Ignore non-Java frames
3120 }
3121
3122 // Bail-out case for too deep stacks
3123 count++;
3124 if (MaxJavaStackTraceDepth == count) return;
3125 }
3126 }
3127
3128
3129 // JVMTI PopFrame support
3130 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3131 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3132 if (in_bytes(size_in_bytes) != 0) {
3133 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3134 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3135 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3136 }
3137 }
3138
3139 void* JavaThread::popframe_preserved_args() {
3140 return _popframe_preserved_args;
3141 }
3142
3143 ByteSize JavaThread::popframe_preserved_args_size() {
3144 return in_ByteSize(_popframe_preserved_args_size);
3145 }
3146
3147 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3148 int sz = in_bytes(popframe_preserved_args_size());
3149 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3150 return in_WordSize(sz / wordSize);
3151 }
3152
3153 void JavaThread::popframe_free_preserved_args() {
3154 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3155 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3156 _popframe_preserved_args = NULL;
3157 _popframe_preserved_args_size = 0;
3158 }
3159
3160 #ifndef PRODUCT
3161
3162 void JavaThread::trace_frames() {
3163 tty->print_cr("[Describe stack]");
3164 int frame_no = 1;
3165 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3166 tty->print(" %d. ", frame_no++);
3167 fst.current()->print_value_on(tty, this);
3168 tty->cr();
3169 }
3170 }
3171
3172 class PrintAndVerifyOopClosure: public OopClosure {
3173 protected:
3174 template <class T> inline void do_oop_work(T* p) {
3175 oop obj = oopDesc::load_decode_heap_oop(p);
3176 if (obj == NULL) return;
3177 tty->print(INTPTR_FORMAT ": ", p2i(p));
3178 if (obj->is_oop_or_null()) {
3179 if (obj->is_objArray()) {
3180 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3181 } else {
3182 obj->print();
3183 }
3184 } else {
3185 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3186 }
3187 tty->cr();
3188 }
3189 public:
3190 virtual void do_oop(oop* p) { do_oop_work(p); }
3191 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3192 };
3193
3194
3195 static void oops_print(frame* f, const RegisterMap *map) {
3196 PrintAndVerifyOopClosure print;
3197 f->print_value();
3198 f->oops_do(&print, NULL, (RegisterMap*)map);
3199 }
3200
3201 // Print our all the locations that contain oops and whether they are
3202 // valid or not. This useful when trying to find the oldest frame
3203 // where an oop has gone bad since the frame walk is from youngest to
3204 // oldest.
3205 void JavaThread::trace_oops() {
3206 tty->print_cr("[Trace oops]");
3207 frames_do(oops_print);
3208 }
3209
3210
3211 #ifdef ASSERT
3212 // Print or validate the layout of stack frames
3213 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3214 ResourceMark rm;
3215 PRESERVE_EXCEPTION_MARK;
3216 FrameValues values;
3217 int frame_no = 0;
3218 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3219 fst.current()->describe(values, ++frame_no);
3220 if (depth == frame_no) break;
3221 }
3222 if (validate_only) {
3223 values.validate();
3224 } else {
3225 tty->print_cr("[Describe stack layout]");
3226 values.print(this);
3227 }
3228 }
3229 #endif
3230
3231 void JavaThread::trace_stack_from(vframe* start_vf) {
3232 ResourceMark rm;
3233 int vframe_no = 1;
3234 for (vframe* f = start_vf; f; f = f->sender()) {
3235 if (f->is_java_frame()) {
3236 javaVFrame::cast(f)->print_activation(vframe_no++);
3237 } else {
3238 f->print();
3239 }
3240 if (vframe_no > StackPrintLimit) {
3241 tty->print_cr("...<more frames>...");
3242 return;
3243 }
3244 }
3245 }
3246
3247
3248 void JavaThread::trace_stack() {
3249 if (!has_last_Java_frame()) return;
3250 ResourceMark rm;
3251 HandleMark hm;
3252 RegisterMap reg_map(this);
3253 trace_stack_from(last_java_vframe(®_map));
3254 }
3255
3256
3257 #endif // PRODUCT
3258
3259
3260 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3261 assert(reg_map != NULL, "a map must be given");
3262 frame f = last_frame();
3263 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3264 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3265 }
3266 return NULL;
3267 }
3268
3269
3270 Klass* JavaThread::security_get_caller_class(int depth) {
3271 vframeStream vfst(this);
3272 vfst.security_get_caller_frame(depth);
3273 if (!vfst.at_end()) {
3274 return vfst.method()->method_holder();
3275 }
3276 return NULL;
3277 }
3278
3279 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3280 assert(thread->is_Compiler_thread(), "must be compiler thread");
3281 CompileBroker::compiler_thread_loop();
3282 }
3283
3284 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3285 NMethodSweeper::sweeper_loop();
3286 }
3287
3288 // Create a CompilerThread
3289 CompilerThread::CompilerThread(CompileQueue* queue,
3290 CompilerCounters* counters)
3291 : JavaThread(&compiler_thread_entry) {
3292 _env = NULL;
3293 _log = NULL;
3294 _task = NULL;
3295 _queue = queue;
3296 _counters = counters;
3297 _buffer_blob = NULL;
3298 _compiler = NULL;
3299
3300 #ifndef PRODUCT
3301 _ideal_graph_printer = NULL;
3302 #endif
3303 }
3304
3305 bool CompilerThread::can_call_java() const {
3306 return _compiler != NULL && _compiler->is_jvmci();
3307 }
3308
3309 // Create sweeper thread
3310 CodeCacheSweeperThread::CodeCacheSweeperThread()
3311 : JavaThread(&sweeper_thread_entry) {
3312 _scanned_compiled_method = NULL;
3313 }
3314
3315 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3316 JavaThread::oops_do(f, cf);
3317 if (_scanned_compiled_method != NULL && cf != NULL) {
3318 // Safepoints can occur when the sweeper is scanning an nmethod so
3319 // process it here to make sure it isn't unloaded in the middle of
3320 // a scan.
3321 cf->do_code_blob(_scanned_compiled_method);
3322 }
3323 }
3324
3325 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3326 JavaThread::nmethods_do(cf);
3327 if (_scanned_compiled_method != NULL && cf != NULL) {
3328 // Safepoints can occur when the sweeper is scanning an nmethod so
3329 // process it here to make sure it isn't unloaded in the middle of
3330 // a scan.
3331 cf->do_code_blob(_scanned_compiled_method);
3332 }
3333 }
3334
3335
3336 // ======= Threads ========
3337
3338 // The Threads class links together all active threads, and provides
3339 // operations over all threads. It is protected by its own Mutex
3340 // lock, which is also used in other contexts to protect thread
3341 // operations from having the thread being operated on from exiting
3342 // and going away unexpectedly (e.g., safepoint synchronization)
3343
3344 JavaThread* Threads::_thread_list = NULL;
3345 int Threads::_number_of_threads = 0;
3346 int Threads::_number_of_non_daemon_threads = 0;
3347 int Threads::_return_code = 0;
3348 int Threads::_thread_claim_parity = 0;
3349 size_t JavaThread::_stack_size_at_create = 0;
3350 #ifdef ASSERT
3351 bool Threads::_vm_complete = false;
3352 #endif
3353
3354 // All JavaThreads
3355 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3356
3357 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3358 void Threads::threads_do(ThreadClosure* tc) {
3359 assert_locked_or_safepoint(Threads_lock);
3360 // ALL_JAVA_THREADS iterates through all JavaThreads
3361 ALL_JAVA_THREADS(p) {
3362 tc->do_thread(p);
3363 }
3364 // Someday we could have a table or list of all non-JavaThreads.
3365 // For now, just manually iterate through them.
3366 tc->do_thread(VMThread::vm_thread());
3367 Universe::heap()->gc_threads_do(tc);
3368 WatcherThread *wt = WatcherThread::watcher_thread();
3369 // Strictly speaking, the following NULL check isn't sufficient to make sure
3370 // the data for WatcherThread is still valid upon being examined. However,
3371 // considering that WatchThread terminates when the VM is on the way to
3372 // exit at safepoint, the chance of the above is extremely small. The right
3373 // way to prevent termination of WatcherThread would be to acquire
3374 // Terminator_lock, but we can't do that without violating the lock rank
3375 // checking in some cases.
3376 if (wt != NULL) {
3377 tc->do_thread(wt);
3378 }
3379
3380 // If CompilerThreads ever become non-JavaThreads, add them here
3381 }
3382
3383 // The system initialization in the library has three phases.
3384 //
3385 // Phase 1: java.lang.System class initialization
3386 // java.lang.System is a primordial class loaded and initialized
3387 // by the VM early during startup. java.lang.System.<clinit>
3388 // only does registerNatives and keeps the rest of the class
3389 // initialization work later until thread initialization completes.
3390 //
3391 // System.initPhase1 initializes the system properties, the static
3392 // fields in, out, and err. Set up java signal handlers, OS-specific
3393 // system settings, and thread group of the main thread.
3394 static void call_initPhase1(TRAPS) {
3395 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3396 JavaValue result(T_VOID);
3397 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3398 vmSymbols::void_method_signature(), CHECK);
3399 }
3400
3401 // Phase 2. Module system initialization
3402 // This will initialize the module system. Only java.base classes
3403 // can be loaded until phase 2 completes.
3404 //
3405 // Call System.initPhase2 after the compiler initialization and jsr292
3406 // classes get initialized because module initialization runs a lot of java
3407 // code, that for performance reasons, should be compiled. Also, this will
3408 // enable the startup code to use lambda and other language features in this
3409 // phase and onward.
3410 //
3411 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3412 static void call_initPhase2(TRAPS) {
3413 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3414
3415 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3416
3417 JavaValue result(T_INT);
3418 JavaCallArguments args;
3419 args.push_int(DisplayVMOutputToStderr);
3420 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3421 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3422 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3423 if (result.get_jint() != JNI_OK) {
3424 vm_exit_during_initialization(); // no message or exception
3425 }
3426
3427 universe_post_module_init();
3428 }
3429
3430 // Phase 3. final setup - set security manager, system class loader and TCCL
3431 //
3432 // This will instantiate and set the security manager, set the system class
3433 // loader as well as the thread context class loader. The security manager
3434 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3435 // other modules or the application's classpath.
3436 static void call_initPhase3(TRAPS) {
3437 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3438 JavaValue result(T_VOID);
3439 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3440 vmSymbols::void_method_signature(), CHECK);
3441 }
3442
3443 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3444 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3445
3446 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3447 create_vm_init_libraries();
3448 }
3449
3450 initialize_class(vmSymbols::java_lang_String(), CHECK);
3451
3452 // Inject CompactStrings value after the static initializers for String ran.
3453 java_lang_String::set_compact_strings(CompactStrings);
3454
3455 // Initialize java_lang.System (needed before creating the thread)
3456 initialize_class(vmSymbols::java_lang_System(), CHECK);
3457 // The VM creates & returns objects of this class. Make sure it's initialized.
3458 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3459 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3460 Handle thread_group = create_initial_thread_group(CHECK);
3461 Universe::set_main_thread_group(thread_group());
3462 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3463 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3464 main_thread->set_threadObj(thread_object);
3465 // Set thread status to running since main thread has
3466 // been started and running.
3467 java_lang_Thread::set_thread_status(thread_object,
3468 java_lang_Thread::RUNNABLE);
3469
3470 // The VM creates objects of this class.
3471 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3472
3473 // The VM preresolves methods to these classes. Make sure that they get initialized
3474 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3475 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3476
3477 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3478 call_initPhase1(CHECK);
3479
3480 // get the Java runtime name after java.lang.System is initialized
3481 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3482 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3483
3484 // an instance of OutOfMemory exception has been allocated earlier
3485 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3486 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3487 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3488 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3489 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3490 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3491 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3492 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3493 }
3494
3495 void Threads::initialize_jsr292_core_classes(TRAPS) {
3496 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3497
3498 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3499 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3500 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3501 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3502 }
3503
3504 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3505 extern void JDK_Version_init();
3506
3507 // Preinitialize version info.
3508 VM_Version::early_initialize();
3509
3510 // Check version
3511 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3512
3513 // Initialize library-based TLS
3514 ThreadLocalStorage::init();
3515
3516 // Initialize the output stream module
3517 ostream_init();
3518
3519 // Process java launcher properties.
3520 Arguments::process_sun_java_launcher_properties(args);
3521
3522 // Initialize the os module
3523 os::init();
3524
3525 // Record VM creation timing statistics
3526 TraceVmCreationTime create_vm_timer;
3527 create_vm_timer.start();
3528
3529 // Initialize system properties.
3530 Arguments::init_system_properties();
3531
3532 // So that JDK version can be used as a discriminator when parsing arguments
3533 JDK_Version_init();
3534
3535 // Update/Initialize System properties after JDK version number is known
3536 Arguments::init_version_specific_system_properties();
3537
3538 // Make sure to initialize log configuration *before* parsing arguments
3539 LogConfiguration::initialize(create_vm_timer.begin_time());
3540
3541 // Parse arguments
3542 jint parse_result = Arguments::parse(args);
3543 if (parse_result != JNI_OK) return parse_result;
3544
3545 os::init_before_ergo();
3546
3547 jint ergo_result = Arguments::apply_ergo();
3548 if (ergo_result != JNI_OK) return ergo_result;
3549
3550 // Final check of all ranges after ergonomics which may change values.
3551 if (!CommandLineFlagRangeList::check_ranges()) {
3552 return JNI_EINVAL;
3553 }
3554
3555 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3556 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3557 if (!constraint_result) {
3558 return JNI_EINVAL;
3559 }
3560
3561 CommandLineFlagWriteableList::mark_startup();
3562
3563 if (PauseAtStartup) {
3564 os::pause();
3565 }
3566
3567 HOTSPOT_VM_INIT_BEGIN();
3568
3569 // Timing (must come after argument parsing)
3570 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3571
3572 // Initialize the os module after parsing the args
3573 jint os_init_2_result = os::init_2();
3574 if (os_init_2_result != JNI_OK) return os_init_2_result;
3575
3576 jint adjust_after_os_result = Arguments::adjust_after_os();
3577 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3578
3579 // Initialize output stream logging
3580 ostream_init_log();
3581
3582 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3583 // Must be before create_vm_init_agents()
3584 if (Arguments::init_libraries_at_startup()) {
3585 convert_vm_init_libraries_to_agents();
3586 }
3587
3588 // Launch -agentlib/-agentpath and converted -Xrun agents
3589 if (Arguments::init_agents_at_startup()) {
3590 create_vm_init_agents();
3591 }
3592
3593 // Initialize Threads state
3594 _thread_list = NULL;
3595 _number_of_threads = 0;
3596 _number_of_non_daemon_threads = 0;
3597
3598 // Initialize global data structures and create system classes in heap
3599 vm_init_globals();
3600
3601 #if INCLUDE_JVMCI
3602 if (JVMCICounterSize > 0) {
3603 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3604 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3605 } else {
3606 JavaThread::_jvmci_old_thread_counters = NULL;
3607 }
3608 #endif // INCLUDE_JVMCI
3609
3610 // Attach the main thread to this os thread
3611 JavaThread* main_thread = new JavaThread();
3612 main_thread->set_thread_state(_thread_in_vm);
3613 main_thread->initialize_thread_current();
3614 // must do this before set_active_handles
3615 main_thread->record_stack_base_and_size();
3616 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3617
3618 if (!main_thread->set_as_starting_thread()) {
3619 vm_shutdown_during_initialization(
3620 "Failed necessary internal allocation. Out of swap space");
3621 delete main_thread;
3622 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3623 return JNI_ENOMEM;
3624 }
3625
3626 // Enable guard page *after* os::create_main_thread(), otherwise it would
3627 // crash Linux VM, see notes in os_linux.cpp.
3628 main_thread->create_stack_guard_pages();
3629
3630 // Initialize Java-Level synchronization subsystem
3631 ObjectMonitor::Initialize();
3632
3633 // Initialize global modules
3634 jint status = init_globals();
3635 if (status != JNI_OK) {
3636 delete main_thread;
3637 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3638 return status;
3639 }
3640
3641 if (TRACE_INITIALIZE() != JNI_OK) {
3642 vm_exit_during_initialization("Failed to initialize tracing backend");
3643 }
3644
3645 // Should be done after the heap is fully created
3646 main_thread->cache_global_variables();
3647
3648 HandleMark hm;
3649
3650 { MutexLocker mu(Threads_lock);
3651 Threads::add(main_thread);
3652 }
3653
3654 // Any JVMTI raw monitors entered in onload will transition into
3655 // real raw monitor. VM is setup enough here for raw monitor enter.
3656 JvmtiExport::transition_pending_onload_raw_monitors();
3657
3658 // Create the VMThread
3659 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3660
3661 VMThread::create();
3662 Thread* vmthread = VMThread::vm_thread();
3663
3664 if (!os::create_thread(vmthread, os::vm_thread)) {
3665 vm_exit_during_initialization("Cannot create VM thread. "
3666 "Out of system resources.");
3667 }
3668
3669 // Wait for the VM thread to become ready, and VMThread::run to initialize
3670 // Monitors can have spurious returns, must always check another state flag
3671 {
3672 MutexLocker ml(Notify_lock);
3673 os::start_thread(vmthread);
3674 while (vmthread->active_handles() == NULL) {
3675 Notify_lock->wait();
3676 }
3677 }
3678 }
3679
3680 assert(Universe::is_fully_initialized(), "not initialized");
3681 if (VerifyDuringStartup) {
3682 // Make sure we're starting with a clean slate.
3683 VM_Verify verify_op;
3684 VMThread::execute(&verify_op);
3685 }
3686
3687 Thread* THREAD = Thread::current();
3688
3689 // At this point, the Universe is initialized, but we have not executed
3690 // any byte code. Now is a good time (the only time) to dump out the
3691 // internal state of the JVM for sharing.
3692 if (DumpSharedSpaces) {
3693 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3694 ShouldNotReachHere();
3695 }
3696
3697 // Always call even when there are not JVMTI environments yet, since environments
3698 // may be attached late and JVMTI must track phases of VM execution
3699 JvmtiExport::enter_early_start_phase();
3700
3701 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3702 JvmtiExport::post_early_vm_start();
3703
3704 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3705
3706 // We need this for ClassDataSharing - the initial vm.info property is set
3707 // with the default value of CDS "sharing" which may be reset through
3708 // command line options.
3709 reset_vm_info_property(CHECK_JNI_ERR);
3710
3711 quicken_jni_functions();
3712
3713 // No more stub generation allowed after that point.
3714 StubCodeDesc::freeze();
3715
3716 // Set flag that basic initialization has completed. Used by exceptions and various
3717 // debug stuff, that does not work until all basic classes have been initialized.
3718 set_init_completed();
3719
3720 LogConfiguration::post_initialize();
3721 Metaspace::post_initialize();
3722
3723 HOTSPOT_VM_INIT_END();
3724
3725 // record VM initialization completion time
3726 #if INCLUDE_MANAGEMENT
3727 Management::record_vm_init_completed();
3728 #endif // INCLUDE_MANAGEMENT
3729
3730 // Signal Dispatcher needs to be started before VMInit event is posted
3731 os::signal_init(CHECK_JNI_ERR);
3732
3733 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3734 if (!DisableAttachMechanism) {
3735 AttachListener::vm_start();
3736 if (StartAttachListener || AttachListener::init_at_startup()) {
3737 AttachListener::init();
3738 }
3739 }
3740
3741 // Launch -Xrun agents
3742 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3743 // back-end can launch with -Xdebug -Xrunjdwp.
3744 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3745 create_vm_init_libraries();
3746 }
3747
3748 if (CleanChunkPoolAsync) {
3749 Chunk::start_chunk_pool_cleaner_task();
3750 }
3751
3752 // initialize compiler(s)
3753 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3754 CompileBroker::compilation_init(CHECK_JNI_ERR);
3755 #endif
3756
3757 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3758 // It is done after compilers are initialized, because otherwise compilations of
3759 // signature polymorphic MH intrinsics can be missed
3760 // (see SystemDictionary::find_method_handle_intrinsic).
3761 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3762
3763 // This will initialize the module system. Only java.base classes can be
3764 // loaded until phase 2 completes
3765 call_initPhase2(CHECK_JNI_ERR);
3766
3767 // Always call even when there are not JVMTI environments yet, since environments
3768 // may be attached late and JVMTI must track phases of VM execution
3769 JvmtiExport::enter_start_phase();
3770
3771 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3772 JvmtiExport::post_vm_start();
3773
3774 // Final system initialization including security manager and system class loader
3775 call_initPhase3(CHECK_JNI_ERR);
3776
3777 // cache the system class loader
3778 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3779
3780 #if INCLUDE_JVMCI
3781 if (EnableJVMCI) {
3782 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3783 // The JVMCI Java initialization code will read this flag and
3784 // do the printing if it's set.
3785 bool init = JVMCIPrintProperties;
3786
3787 if (!init) {
3788 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3789 // compilations via JVMCI will not actually block until JVMCI is initialized.
3790 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3791 }
3792
3793 if (init) {
3794 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3795 }
3796 }
3797 #endif
3798
3799 // Always call even when there are not JVMTI environments yet, since environments
3800 // may be attached late and JVMTI must track phases of VM execution
3801 JvmtiExport::enter_live_phase();
3802
3803 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3804 JvmtiExport::post_vm_initialized();
3805
3806 if (TRACE_START() != JNI_OK) {
3807 vm_exit_during_initialization("Failed to start tracing backend.");
3808 }
3809
3810 #if INCLUDE_MANAGEMENT
3811 Management::initialize(THREAD);
3812
3813 if (HAS_PENDING_EXCEPTION) {
3814 // management agent fails to start possibly due to
3815 // configuration problem and is responsible for printing
3816 // stack trace if appropriate. Simply exit VM.
3817 vm_exit(1);
3818 }
3819 #endif // INCLUDE_MANAGEMENT
3820
3821 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3822 if (MemProfiling) MemProfiler::engage();
3823 StatSampler::engage();
3824 if (CheckJNICalls) JniPeriodicChecker::engage();
3825
3826 BiasedLocking::init();
3827
3828 #if INCLUDE_RTM_OPT
3829 RTMLockingCounters::init();
3830 #endif
3831
3832 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3833 call_postVMInitHook(THREAD);
3834 // The Java side of PostVMInitHook.run must deal with all
3835 // exceptions and provide means of diagnosis.
3836 if (HAS_PENDING_EXCEPTION) {
3837 CLEAR_PENDING_EXCEPTION;
3838 }
3839 }
3840
3841 {
3842 MutexLocker ml(PeriodicTask_lock);
3843 // Make sure the WatcherThread can be started by WatcherThread::start()
3844 // or by dynamic enrollment.
3845 WatcherThread::make_startable();
3846 // Start up the WatcherThread if there are any periodic tasks
3847 // NOTE: All PeriodicTasks should be registered by now. If they
3848 // aren't, late joiners might appear to start slowly (we might
3849 // take a while to process their first tick).
3850 if (PeriodicTask::num_tasks() > 0) {
3851 WatcherThread::start();
3852 }
3853 }
3854
3855 create_vm_timer.end();
3856 #ifdef ASSERT
3857 _vm_complete = true;
3858 #endif
3859 return JNI_OK;
3860 }
3861
3862 // type for the Agent_OnLoad and JVM_OnLoad entry points
3863 extern "C" {
3864 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3865 }
3866 // Find a command line agent library and return its entry point for
3867 // -agentlib: -agentpath: -Xrun
3868 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3869 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3870 const char *on_load_symbols[],
3871 size_t num_symbol_entries) {
3872 OnLoadEntry_t on_load_entry = NULL;
3873 void *library = NULL;
3874
3875 if (!agent->valid()) {
3876 char buffer[JVM_MAXPATHLEN];
3877 char ebuf[1024] = "";
3878 const char *name = agent->name();
3879 const char *msg = "Could not find agent library ";
3880
3881 // First check to see if agent is statically linked into executable
3882 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3883 library = agent->os_lib();
3884 } else if (agent->is_absolute_path()) {
3885 library = os::dll_load(name, ebuf, sizeof ebuf);
3886 if (library == NULL) {
3887 const char *sub_msg = " in absolute 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 } else {
3896 // Try to load the agent from the standard dll directory
3897 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3898 name)) {
3899 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3900 }
3901 if (library == NULL) { // Try the local directory
3902 char ns[1] = {0};
3903 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3904 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3905 }
3906 if (library == NULL) {
3907 const char *sub_msg = " on the library path, with error: ";
3908 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3909 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3910 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3911 // If we can't find the agent, exit.
3912 vm_exit_during_initialization(buf, NULL);
3913 FREE_C_HEAP_ARRAY(char, buf);
3914 }
3915 }
3916 }
3917 agent->set_os_lib(library);
3918 agent->set_valid();
3919 }
3920
3921 // Find the OnLoad function.
3922 on_load_entry =
3923 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3924 false,
3925 on_load_symbols,
3926 num_symbol_entries));
3927 return on_load_entry;
3928 }
3929
3930 // Find the JVM_OnLoad entry point
3931 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3932 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3933 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3934 }
3935
3936 // Find the Agent_OnLoad entry point
3937 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3938 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3939 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3940 }
3941
3942 // For backwards compatibility with -Xrun
3943 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3944 // treated like -agentpath:
3945 // Must be called before agent libraries are created
3946 void Threads::convert_vm_init_libraries_to_agents() {
3947 AgentLibrary* agent;
3948 AgentLibrary* next;
3949
3950 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3951 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3952 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3953
3954 // If there is an JVM_OnLoad function it will get called later,
3955 // otherwise see if there is an Agent_OnLoad
3956 if (on_load_entry == NULL) {
3957 on_load_entry = lookup_agent_on_load(agent);
3958 if (on_load_entry != NULL) {
3959 // switch it to the agent list -- so that Agent_OnLoad will be called,
3960 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3961 Arguments::convert_library_to_agent(agent);
3962 } else {
3963 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3964 }
3965 }
3966 }
3967 }
3968
3969 // Create agents for -agentlib: -agentpath: and converted -Xrun
3970 // Invokes Agent_OnLoad
3971 // Called very early -- before JavaThreads exist
3972 void Threads::create_vm_init_agents() {
3973 extern struct JavaVM_ main_vm;
3974 AgentLibrary* agent;
3975
3976 JvmtiExport::enter_onload_phase();
3977
3978 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3979 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3980
3981 if (on_load_entry != NULL) {
3982 // Invoke the Agent_OnLoad function
3983 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3984 if (err != JNI_OK) {
3985 vm_exit_during_initialization("agent library failed to init", agent->name());
3986 }
3987 } else {
3988 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3989 }
3990 }
3991 JvmtiExport::enter_primordial_phase();
3992 }
3993
3994 extern "C" {
3995 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3996 }
3997
3998 void Threads::shutdown_vm_agents() {
3999 // Send any Agent_OnUnload notifications
4000 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4001 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4002 extern struct JavaVM_ main_vm;
4003 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4004
4005 // Find the Agent_OnUnload function.
4006 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4007 os::find_agent_function(agent,
4008 false,
4009 on_unload_symbols,
4010 num_symbol_entries));
4011
4012 // Invoke the Agent_OnUnload function
4013 if (unload_entry != NULL) {
4014 JavaThread* thread = JavaThread::current();
4015 ThreadToNativeFromVM ttn(thread);
4016 HandleMark hm(thread);
4017 (*unload_entry)(&main_vm);
4018 }
4019 }
4020 }
4021
4022 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4023 // Invokes JVM_OnLoad
4024 void Threads::create_vm_init_libraries() {
4025 extern struct JavaVM_ main_vm;
4026 AgentLibrary* agent;
4027
4028 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4029 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4030
4031 if (on_load_entry != NULL) {
4032 // Invoke the JVM_OnLoad function
4033 JavaThread* thread = JavaThread::current();
4034 ThreadToNativeFromVM ttn(thread);
4035 HandleMark hm(thread);
4036 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4037 if (err != JNI_OK) {
4038 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4039 }
4040 } else {
4041 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4042 }
4043 }
4044 }
4045
4046 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4047 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4048
4049 JavaThread* java_thread = NULL;
4050 // Sequential search for now. Need to do better optimization later.
4051 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4052 oop tobj = thread->threadObj();
4053 if (!thread->is_exiting() &&
4054 tobj != NULL &&
4055 java_tid == java_lang_Thread::thread_id(tobj)) {
4056 java_thread = thread;
4057 break;
4058 }
4059 }
4060 return java_thread;
4061 }
4062
4063
4064 // Last thread running calls java.lang.Shutdown.shutdown()
4065 void JavaThread::invoke_shutdown_hooks() {
4066 HandleMark hm(this);
4067
4068 // We could get here with a pending exception, if so clear it now.
4069 if (this->has_pending_exception()) {
4070 this->clear_pending_exception();
4071 }
4072
4073 EXCEPTION_MARK;
4074 Klass* shutdown_klass =
4075 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4076 THREAD);
4077 if (shutdown_klass != NULL) {
4078 // SystemDictionary::resolve_or_null will return null if there was
4079 // an exception. If we cannot load the Shutdown class, just don't
4080 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4081 // and finalizers (if runFinalizersOnExit is set) won't be run.
4082 // Note that if a shutdown hook was registered or runFinalizersOnExit
4083 // was called, the Shutdown class would have already been loaded
4084 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4085 JavaValue result(T_VOID);
4086 JavaCalls::call_static(&result,
4087 shutdown_klass,
4088 vmSymbols::shutdown_method_name(),
4089 vmSymbols::void_method_signature(),
4090 THREAD);
4091 }
4092 CLEAR_PENDING_EXCEPTION;
4093 }
4094
4095 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4096 // the program falls off the end of main(). Another VM exit path is through
4097 // vm_exit() when the program calls System.exit() to return a value or when
4098 // there is a serious error in VM. The two shutdown paths are not exactly
4099 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4100 // and VM_Exit op at VM level.
4101 //
4102 // Shutdown sequence:
4103 // + Shutdown native memory tracking if it is on
4104 // + Wait until we are the last non-daemon thread to execute
4105 // <-- every thing is still working at this moment -->
4106 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4107 // shutdown hooks, run finalizers if finalization-on-exit
4108 // + Call before_exit(), prepare for VM exit
4109 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4110 // currently the only user of this mechanism is File.deleteOnExit())
4111 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4112 // post thread end and vm death events to JVMTI,
4113 // stop signal thread
4114 // + Call JavaThread::exit(), it will:
4115 // > release JNI handle blocks, remove stack guard pages
4116 // > remove this thread from Threads list
4117 // <-- no more Java code from this thread after this point -->
4118 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4119 // the compiler threads at safepoint
4120 // <-- do not use anything that could get blocked by Safepoint -->
4121 // + Disable tracing at JNI/JVM barriers
4122 // + Set _vm_exited flag for threads that are still running native code
4123 // + Delete this thread
4124 // + Call exit_globals()
4125 // > deletes tty
4126 // > deletes PerfMemory resources
4127 // + Return to caller
4128
4129 bool Threads::destroy_vm() {
4130 JavaThread* thread = JavaThread::current();
4131
4132 #ifdef ASSERT
4133 _vm_complete = false;
4134 #endif
4135 // Wait until we are the last non-daemon thread to execute
4136 { MutexLocker nu(Threads_lock);
4137 while (Threads::number_of_non_daemon_threads() > 1)
4138 // This wait should make safepoint checks, wait without a timeout,
4139 // and wait as a suspend-equivalent condition.
4140 //
4141 // Note: If the FlatProfiler is running and this thread is waiting
4142 // for another non-daemon thread to finish, then the FlatProfiler
4143 // is waiting for the external suspend request on this thread to
4144 // complete. wait_for_ext_suspend_completion() will eventually
4145 // timeout, but that takes time. Making this wait a suspend-
4146 // equivalent condition solves that timeout problem.
4147 //
4148 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4149 Mutex::_as_suspend_equivalent_flag);
4150 }
4151
4152 // Hang forever on exit if we are reporting an error.
4153 if (ShowMessageBoxOnError && is_error_reported()) {
4154 os::infinite_sleep();
4155 }
4156 os::wait_for_keypress_at_exit();
4157
4158 // run Java level shutdown hooks
4159 thread->invoke_shutdown_hooks();
4160
4161 before_exit(thread);
4162
4163 thread->exit(true);
4164
4165 // Stop VM thread.
4166 {
4167 // 4945125 The vm thread comes to a safepoint during exit.
4168 // GC vm_operations can get caught at the safepoint, and the
4169 // heap is unparseable if they are caught. Grab the Heap_lock
4170 // to prevent this. The GC vm_operations will not be able to
4171 // queue until after the vm thread is dead. After this point,
4172 // we'll never emerge out of the safepoint before the VM exits.
4173
4174 MutexLocker ml(Heap_lock);
4175
4176 VMThread::wait_for_vm_thread_exit();
4177 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4178 VMThread::destroy();
4179 }
4180
4181 // clean up ideal graph printers
4182 #if defined(COMPILER2) && !defined(PRODUCT)
4183 IdealGraphPrinter::clean_up();
4184 #endif
4185
4186 // Now, all Java threads are gone except daemon threads. Daemon threads
4187 // running Java code or in VM are stopped by the Safepoint. However,
4188 // daemon threads executing native code are still running. But they
4189 // will be stopped at native=>Java/VM barriers. Note that we can't
4190 // simply kill or suspend them, as it is inherently deadlock-prone.
4191
4192 VM_Exit::set_vm_exited();
4193
4194 notify_vm_shutdown();
4195
4196 delete thread;
4197
4198 #if INCLUDE_JVMCI
4199 if (JVMCICounterSize > 0) {
4200 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4201 }
4202 #endif
4203
4204 // exit_globals() will delete tty
4205 exit_globals();
4206
4207 LogConfiguration::finalize();
4208
4209 return true;
4210 }
4211
4212
4213 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4214 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4215 return is_supported_jni_version(version);
4216 }
4217
4218
4219 jboolean Threads::is_supported_jni_version(jint version) {
4220 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4221 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4222 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4223 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4224 if (version == JNI_VERSION_9) return JNI_TRUE;
4225 return JNI_FALSE;
4226 }
4227
4228
4229 void Threads::add(JavaThread* p, bool force_daemon) {
4230 // The threads lock must be owned at this point
4231 assert_locked_or_safepoint(Threads_lock);
4232
4233 // See the comment for this method in thread.hpp for its purpose and
4234 // why it is called here.
4235 p->initialize_queues();
4236 p->set_next(_thread_list);
4237 _thread_list = p;
4238 _number_of_threads++;
4239 oop threadObj = p->threadObj();
4240 bool daemon = true;
4241 // Bootstrapping problem: threadObj can be null for initial
4242 // JavaThread (or for threads attached via JNI)
4243 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4244 _number_of_non_daemon_threads++;
4245 daemon = false;
4246 }
4247
4248 ThreadService::add_thread(p, daemon);
4249
4250 // Possible GC point.
4251 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4252 }
4253
4254 void Threads::remove(JavaThread* p) {
4255
4256 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4257 ObjectSynchronizer::omFlush(p);
4258
4259 // Extra scope needed for Thread_lock, so we can check
4260 // that we do not remove thread without safepoint code notice
4261 { MutexLocker ml(Threads_lock);
4262
4263 assert(includes(p), "p must be present");
4264
4265 JavaThread* current = _thread_list;
4266 JavaThread* prev = NULL;
4267
4268 while (current != p) {
4269 prev = current;
4270 current = current->next();
4271 }
4272
4273 if (prev) {
4274 prev->set_next(current->next());
4275 } else {
4276 _thread_list = p->next();
4277 }
4278 _number_of_threads--;
4279 oop threadObj = p->threadObj();
4280 bool daemon = true;
4281 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4282 _number_of_non_daemon_threads--;
4283 daemon = false;
4284
4285 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4286 // on destroy_vm will wake up.
4287 if (number_of_non_daemon_threads() == 1) {
4288 Threads_lock->notify_all();
4289 }
4290 }
4291 ThreadService::remove_thread(p, daemon);
4292
4293 // Make sure that safepoint code disregard this thread. This is needed since
4294 // the thread might mess around with locks after this point. This can cause it
4295 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4296 // of this thread since it is removed from the queue.
4297 p->set_terminated_value();
4298 } // unlock Threads_lock
4299
4300 // Since Events::log uses a lock, we grab it outside the Threads_lock
4301 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4302 }
4303
4304 // Threads_lock must be held when this is called (or must be called during a safepoint)
4305 bool Threads::includes(JavaThread* p) {
4306 assert(Threads_lock->is_locked(), "sanity check");
4307 ALL_JAVA_THREADS(q) {
4308 if (q == p) {
4309 return true;
4310 }
4311 }
4312 return false;
4313 }
4314
4315 // Operations on the Threads list for GC. These are not explicitly locked,
4316 // but the garbage collector must provide a safe context for them to run.
4317 // In particular, these things should never be called when the Threads_lock
4318 // is held by some other thread. (Note: the Safepoint abstraction also
4319 // uses the Threads_lock to guarantee this property. It also makes sure that
4320 // all threads gets blocked when exiting or starting).
4321
4322 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4323 ALL_JAVA_THREADS(p) {
4324 p->oops_do(f, cf);
4325 }
4326 VMThread::vm_thread()->oops_do(f, cf);
4327 }
4328
4329 void Threads::change_thread_claim_parity() {
4330 // Set the new claim parity.
4331 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4332 "Not in range.");
4333 _thread_claim_parity++;
4334 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4335 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4336 "Not in range.");
4337 }
4338
4339 #ifdef ASSERT
4340 void Threads::assert_all_threads_claimed() {
4341 ALL_JAVA_THREADS(p) {
4342 const int thread_parity = p->oops_do_parity();
4343 assert((thread_parity == _thread_claim_parity),
4344 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4345 }
4346 }
4347 #endif // ASSERT
4348
4349 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4350 int cp = Threads::thread_claim_parity();
4351 ALL_JAVA_THREADS(p) {
4352 if (p->claim_oops_do(is_par, cp)) {
4353 p->oops_do(f, cf);
4354 }
4355 }
4356 VMThread* vmt = VMThread::vm_thread();
4357 if (vmt->claim_oops_do(is_par, cp)) {
4358 vmt->oops_do(f, cf);
4359 }
4360 }
4361
4362 #if INCLUDE_ALL_GCS
4363 // Used by ParallelScavenge
4364 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4365 ALL_JAVA_THREADS(p) {
4366 q->enqueue(new ThreadRootsTask(p));
4367 }
4368 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4369 }
4370
4371 // Used by Parallel Old
4372 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4373 ALL_JAVA_THREADS(p) {
4374 q->enqueue(new ThreadRootsMarkingTask(p));
4375 }
4376 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4377 }
4378 #endif // INCLUDE_ALL_GCS
4379
4380 void Threads::nmethods_do(CodeBlobClosure* cf) {
4381 ALL_JAVA_THREADS(p) {
4382 // This is used by the code cache sweeper to mark nmethods that are active
4383 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4384 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4385 if(!p->is_Code_cache_sweeper_thread()) {
4386 p->nmethods_do(cf);
4387 }
4388 }
4389 }
4390
4391 void Threads::metadata_do(void f(Metadata*)) {
4392 ALL_JAVA_THREADS(p) {
4393 p->metadata_do(f);
4394 }
4395 }
4396
4397 class ThreadHandlesClosure : public ThreadClosure {
4398 void (*_f)(Metadata*);
4399 public:
4400 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4401 virtual void do_thread(Thread* thread) {
4402 thread->metadata_handles_do(_f);
4403 }
4404 };
4405
4406 void Threads::metadata_handles_do(void f(Metadata*)) {
4407 // Only walk the Handles in Thread.
4408 ThreadHandlesClosure handles_closure(f);
4409 threads_do(&handles_closure);
4410 }
4411
4412 void Threads::deoptimized_wrt_marked_nmethods() {
4413 ALL_JAVA_THREADS(p) {
4414 p->deoptimized_wrt_marked_nmethods();
4415 }
4416 }
4417
4418
4419 // Get count Java threads that are waiting to enter the specified monitor.
4420 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4421 address monitor,
4422 bool doLock) {
4423 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4424 "must grab Threads_lock or be at safepoint");
4425 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4426
4427 int i = 0;
4428 {
4429 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4430 ALL_JAVA_THREADS(p) {
4431 if (!p->can_call_java()) continue;
4432
4433 address pending = (address)p->current_pending_monitor();
4434 if (pending == monitor) { // found a match
4435 if (i < count) result->append(p); // save the first count matches
4436 i++;
4437 }
4438 }
4439 }
4440 return result;
4441 }
4442
4443
4444 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4445 bool doLock) {
4446 assert(doLock ||
4447 Threads_lock->owned_by_self() ||
4448 SafepointSynchronize::is_at_safepoint(),
4449 "must grab Threads_lock or be at safepoint");
4450
4451 // NULL owner means not locked so we can skip the search
4452 if (owner == NULL) return NULL;
4453
4454 {
4455 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4456 ALL_JAVA_THREADS(p) {
4457 // first, see if owner is the address of a Java thread
4458 if (owner == (address)p) return p;
4459 }
4460 }
4461 // Cannot assert on lack of success here since this function may be
4462 // used by code that is trying to report useful problem information
4463 // like deadlock detection.
4464 if (UseHeavyMonitors) return NULL;
4465
4466 // If we didn't find a matching Java thread and we didn't force use of
4467 // heavyweight monitors, then the owner is the stack address of the
4468 // Lock Word in the owning Java thread's stack.
4469 //
4470 JavaThread* the_owner = NULL;
4471 {
4472 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4473 ALL_JAVA_THREADS(q) {
4474 if (q->is_lock_owned(owner)) {
4475 the_owner = q;
4476 break;
4477 }
4478 }
4479 }
4480 // cannot assert on lack of success here; see above comment
4481 return the_owner;
4482 }
4483
4484 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4485 void Threads::print_on(outputStream* st, bool print_stacks,
4486 bool internal_format, bool print_concurrent_locks) {
4487 char buf[32];
4488 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4489
4490 st->print_cr("Full thread dump %s (%s %s):",
4491 Abstract_VM_Version::vm_name(),
4492 Abstract_VM_Version::vm_release(),
4493 Abstract_VM_Version::vm_info_string());
4494 st->cr();
4495
4496 #if INCLUDE_SERVICES
4497 // Dump concurrent locks
4498 ConcurrentLocksDump concurrent_locks;
4499 if (print_concurrent_locks) {
4500 concurrent_locks.dump_at_safepoint();
4501 }
4502 #endif // INCLUDE_SERVICES
4503
4504 ALL_JAVA_THREADS(p) {
4505 ResourceMark rm;
4506 p->print_on(st);
4507 if (print_stacks) {
4508 if (internal_format) {
4509 p->trace_stack();
4510 } else {
4511 p->print_stack_on(st);
4512 }
4513 }
4514 st->cr();
4515 #if INCLUDE_SERVICES
4516 if (print_concurrent_locks) {
4517 concurrent_locks.print_locks_on(p, st);
4518 }
4519 #endif // INCLUDE_SERVICES
4520 }
4521
4522 VMThread::vm_thread()->print_on(st);
4523 st->cr();
4524 Universe::heap()->print_gc_threads_on(st);
4525 WatcherThread* wt = WatcherThread::watcher_thread();
4526 if (wt != NULL) {
4527 wt->print_on(st);
4528 st->cr();
4529 }
4530 st->flush();
4531 }
4532
4533 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4534 int buflen, bool* found_current) {
4535 if (this_thread != NULL) {
4536 bool is_current = (current == this_thread);
4537 *found_current = *found_current || is_current;
4538 st->print("%s", is_current ? "=>" : " ");
4539
4540 st->print(PTR_FORMAT, p2i(this_thread));
4541 st->print(" ");
4542 this_thread->print_on_error(st, buf, buflen);
4543 st->cr();
4544 }
4545 }
4546
4547 class PrintOnErrorClosure : public ThreadClosure {
4548 outputStream* _st;
4549 Thread* _current;
4550 char* _buf;
4551 int _buflen;
4552 bool* _found_current;
4553 public:
4554 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4555 int buflen, bool* found_current) :
4556 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4557
4558 virtual void do_thread(Thread* thread) {
4559 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4560 }
4561 };
4562
4563 // Threads::print_on_error() is called by fatal error handler. It's possible
4564 // that VM is not at safepoint and/or current thread is inside signal handler.
4565 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4566 // memory (even in resource area), it might deadlock the error handler.
4567 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4568 int buflen) {
4569 bool found_current = false;
4570 st->print_cr("Java Threads: ( => current thread )");
4571 ALL_JAVA_THREADS(thread) {
4572 print_on_error(thread, st, current, buf, buflen, &found_current);
4573 }
4574 st->cr();
4575
4576 st->print_cr("Other Threads:");
4577 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4578 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4579
4580 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4581 Universe::heap()->gc_threads_do(&print_closure);
4582
4583 if (!found_current) {
4584 st->cr();
4585 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4586 current->print_on_error(st, buf, buflen);
4587 st->cr();
4588 }
4589 st->cr();
4590 st->print_cr("Threads with active compile tasks:");
4591 print_threads_compiling(st, buf, buflen);
4592 }
4593
4594 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4595 ALL_JAVA_THREADS(thread) {
4596 if (thread->is_Compiler_thread()) {
4597 CompilerThread* ct = (CompilerThread*) thread;
4598 if (ct->task() != NULL) {
4599 thread->print_name_on_error(st, buf, buflen);
4600 ct->task()->print(st, NULL, true, true);
4601 }
4602 }
4603 }
4604 }
4605
4606
4607 // Internal SpinLock and Mutex
4608 // Based on ParkEvent
4609
4610 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4611 //
4612 // We employ SpinLocks _only for low-contention, fixed-length
4613 // short-duration critical sections where we're concerned
4614 // about native mutex_t or HotSpot Mutex:: latency.
4615 // The mux construct provides a spin-then-block mutual exclusion
4616 // mechanism.
4617 //
4618 // Testing has shown that contention on the ListLock guarding gFreeList
4619 // is common. If we implement ListLock as a simple SpinLock it's common
4620 // for the JVM to devolve to yielding with little progress. This is true
4621 // despite the fact that the critical sections protected by ListLock are
4622 // extremely short.
4623 //
4624 // TODO-FIXME: ListLock should be of type SpinLock.
4625 // We should make this a 1st-class type, integrated into the lock
4626 // hierarchy as leaf-locks. Critically, the SpinLock structure
4627 // should have sufficient padding to avoid false-sharing and excessive
4628 // cache-coherency traffic.
4629
4630
4631 typedef volatile int SpinLockT;
4632
4633 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4634 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4635 return; // normal fast-path return
4636 }
4637
4638 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4639 TEVENT(SpinAcquire - ctx);
4640 int ctr = 0;
4641 int Yields = 0;
4642 for (;;) {
4643 while (*adr != 0) {
4644 ++ctr;
4645 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4646 if (Yields > 5) {
4647 os::naked_short_sleep(1);
4648 } else {
4649 os::naked_yield();
4650 ++Yields;
4651 }
4652 } else {
4653 SpinPause();
4654 }
4655 }
4656 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4657 }
4658 }
4659
4660 void Thread::SpinRelease(volatile int * adr) {
4661 assert(*adr != 0, "invariant");
4662 OrderAccess::fence(); // guarantee at least release consistency.
4663 // Roach-motel semantics.
4664 // It's safe if subsequent LDs and STs float "up" into the critical section,
4665 // but prior LDs and STs within the critical section can't be allowed
4666 // to reorder or float past the ST that releases the lock.
4667 // Loads and stores in the critical section - which appear in program
4668 // order before the store that releases the lock - must also appear
4669 // before the store that releases the lock in memory visibility order.
4670 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4671 // the ST of 0 into the lock-word which releases the lock, so fence
4672 // more than covers this on all platforms.
4673 *adr = 0;
4674 }
4675
4676 // muxAcquire and muxRelease:
4677 //
4678 // * muxAcquire and muxRelease support a single-word lock-word construct.
4679 // The LSB of the word is set IFF the lock is held.
4680 // The remainder of the word points to the head of a singly-linked list
4681 // of threads blocked on the lock.
4682 //
4683 // * The current implementation of muxAcquire-muxRelease uses its own
4684 // dedicated Thread._MuxEvent instance. If we're interested in
4685 // minimizing the peak number of extant ParkEvent instances then
4686 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4687 // as certain invariants were satisfied. Specifically, care would need
4688 // to be taken with regards to consuming unpark() "permits".
4689 // A safe rule of thumb is that a thread would never call muxAcquire()
4690 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4691 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4692 // consume an unpark() permit intended for monitorenter, for instance.
4693 // One way around this would be to widen the restricted-range semaphore
4694 // implemented in park(). Another alternative would be to provide
4695 // multiple instances of the PlatformEvent() for each thread. One
4696 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4697 //
4698 // * Usage:
4699 // -- Only as leaf locks
4700 // -- for short-term locking only as muxAcquire does not perform
4701 // thread state transitions.
4702 //
4703 // Alternatives:
4704 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4705 // but with parking or spin-then-park instead of pure spinning.
4706 // * Use Taura-Oyama-Yonenzawa locks.
4707 // * It's possible to construct a 1-0 lock if we encode the lockword as
4708 // (List,LockByte). Acquire will CAS the full lockword while Release
4709 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4710 // acquiring threads use timers (ParkTimed) to detect and recover from
4711 // the stranding window. Thread/Node structures must be aligned on 256-byte
4712 // boundaries by using placement-new.
4713 // * Augment MCS with advisory back-link fields maintained with CAS().
4714 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4715 // The validity of the backlinks must be ratified before we trust the value.
4716 // If the backlinks are invalid the exiting thread must back-track through the
4717 // the forward links, which are always trustworthy.
4718 // * Add a successor indication. The LockWord is currently encoded as
4719 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4720 // to provide the usual futile-wakeup optimization.
4721 // See RTStt for details.
4722 // * Consider schedctl.sc_nopreempt to cover the critical section.
4723 //
4724
4725
4726 typedef volatile intptr_t MutexT; // Mux Lock-word
4727 enum MuxBits { LOCKBIT = 1 };
4728
4729 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4730 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4731 if (w == 0) return;
4732 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4733 return;
4734 }
4735
4736 TEVENT(muxAcquire - Contention);
4737 ParkEvent * const Self = Thread::current()->_MuxEvent;
4738 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4739 for (;;) {
4740 int its = (os::is_MP() ? 100 : 0) + 1;
4741
4742 // Optional spin phase: spin-then-park strategy
4743 while (--its >= 0) {
4744 w = *Lock;
4745 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4746 return;
4747 }
4748 }
4749
4750 Self->reset();
4751 Self->OnList = intptr_t(Lock);
4752 // The following fence() isn't _strictly necessary as the subsequent
4753 // CAS() both serializes execution and ratifies the fetched *Lock value.
4754 OrderAccess::fence();
4755 for (;;) {
4756 w = *Lock;
4757 if ((w & LOCKBIT) == 0) {
4758 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4759 Self->OnList = 0; // hygiene - allows stronger asserts
4760 return;
4761 }
4762 continue; // Interference -- *Lock changed -- Just retry
4763 }
4764 assert(w & LOCKBIT, "invariant");
4765 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4766 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4767 }
4768
4769 while (Self->OnList != 0) {
4770 Self->park();
4771 }
4772 }
4773 }
4774
4775 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4776 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4777 if (w == 0) return;
4778 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4779 return;
4780 }
4781
4782 TEVENT(muxAcquire - Contention);
4783 ParkEvent * ReleaseAfter = NULL;
4784 if (ev == NULL) {
4785 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4786 }
4787 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4788 for (;;) {
4789 guarantee(ev->OnList == 0, "invariant");
4790 int its = (os::is_MP() ? 100 : 0) + 1;
4791
4792 // Optional spin phase: spin-then-park strategy
4793 while (--its >= 0) {
4794 w = *Lock;
4795 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4796 if (ReleaseAfter != NULL) {
4797 ParkEvent::Release(ReleaseAfter);
4798 }
4799 return;
4800 }
4801 }
4802
4803 ev->reset();
4804 ev->OnList = intptr_t(Lock);
4805 // The following fence() isn't _strictly necessary as the subsequent
4806 // CAS() both serializes execution and ratifies the fetched *Lock value.
4807 OrderAccess::fence();
4808 for (;;) {
4809 w = *Lock;
4810 if ((w & LOCKBIT) == 0) {
4811 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4812 ev->OnList = 0;
4813 // We call ::Release while holding the outer lock, thus
4814 // artificially lengthening the critical section.
4815 // Consider deferring the ::Release() until the subsequent unlock(),
4816 // after we've dropped the outer lock.
4817 if (ReleaseAfter != NULL) {
4818 ParkEvent::Release(ReleaseAfter);
4819 }
4820 return;
4821 }
4822 continue; // Interference -- *Lock changed -- Just retry
4823 }
4824 assert(w & LOCKBIT, "invariant");
4825 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4826 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4827 }
4828
4829 while (ev->OnList != 0) {
4830 ev->park();
4831 }
4832 }
4833 }
4834
4835 // Release() must extract a successor from the list and then wake that thread.
4836 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4837 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4838 // Release() would :
4839 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4840 // (B) Extract a successor from the private list "in-hand"
4841 // (C) attempt to CAS() the residual back into *Lock over null.
4842 // If there were any newly arrived threads and the CAS() would fail.
4843 // In that case Release() would detach the RATs, re-merge the list in-hand
4844 // with the RATs and repeat as needed. Alternately, Release() might
4845 // detach and extract a successor, but then pass the residual list to the wakee.
4846 // The wakee would be responsible for reattaching and remerging before it
4847 // competed for the lock.
4848 //
4849 // Both "pop" and DMR are immune from ABA corruption -- there can be
4850 // multiple concurrent pushers, but only one popper or detacher.
4851 // This implementation pops from the head of the list. This is unfair,
4852 // but tends to provide excellent throughput as hot threads remain hot.
4853 // (We wake recently run threads first).
4854 //
4855 // All paths through muxRelease() will execute a CAS.
4856 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4857 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4858 // executed within the critical section are complete and globally visible before the
4859 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4860 void Thread::muxRelease(volatile intptr_t * Lock) {
4861 for (;;) {
4862 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4863 assert(w & LOCKBIT, "invariant");
4864 if (w == LOCKBIT) return;
4865 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4866 assert(List != NULL, "invariant");
4867 assert(List->OnList == intptr_t(Lock), "invariant");
4868 ParkEvent * const nxt = List->ListNext;
4869 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4870
4871 // The following CAS() releases the lock and pops the head element.
4872 // The CAS() also ratifies the previously fetched lock-word value.
4873 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4874 continue;
4875 }
4876 List->OnList = 0;
4877 OrderAccess::fence();
4878 List->unpark();
4879 return;
4880 }
4881 }
4882
4883
4884 void Threads::verify() {
4885 ALL_JAVA_THREADS(p) {
4886 p->verify();
4887 }
4888 VMThread* thread = VMThread::vm_thread();
4889 if (thread != NULL) thread->verify();
4890 }