1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "compiler/compileTask.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/workgroup.hpp"
38 #include "interpreter/interpreter.hpp"
39 #include "interpreter/linkResolver.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "jvmtifiles/jvmtiEnv.hpp"
42 #include "logging/log.hpp"
43 #include "logging/logConfiguration.hpp"
44 #include "memory/metaspaceShared.hpp"
45 #include "memory/oopFactory.hpp"
46 #include "memory/resourceArea.hpp"
47 #include "memory/universe.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/objArrayOop.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/symbol.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "prims/jvm_misc.hpp"
54 #include "prims/jvmtiExport.hpp"
55 #include "prims/jvmtiThreadState.hpp"
56 #include "prims/privilegedStack.hpp"
57 #include "runtime/arguments.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/commandLineFlagConstraintList.hpp"
61 #include "runtime/commandLineFlagWriteableList.hpp"
62 #include "runtime/commandLineFlagRangeList.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/fprofiler.hpp"
65 #include "runtime/frame.inline.hpp"
66 #include "runtime/globals.hpp"
67 #include "runtime/init.hpp"
68 #include "runtime/interfaceSupport.hpp"
69 #include "runtime/java.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniPeriodicChecker.hpp"
72 #include "runtime/timerTrace.hpp"
73 #include "runtime/memprofiler.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/objectMonitor.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/osThread.hpp"
78 #include "runtime/safepoint.hpp"
79 #include "runtime/sharedRuntime.hpp"
80 #include "runtime/statSampler.hpp"
81 #include "runtime/stubRoutines.hpp"
82 #include "runtime/sweeper.hpp"
83 #include "runtime/task.hpp"
84 #include "runtime/thread.inline.hpp"
85 #include "runtime/threadCritical.hpp"
86 #include "runtime/vframe.hpp"
87 #include "runtime/vframeArray.hpp"
88 #include "runtime/vframe_hp.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "runtime/vm_operations.hpp"
91 #include "runtime/vm_version.hpp"
92 #include "services/attachListener.hpp"
93 #include "services/management.hpp"
94 #include "services/memTracker.hpp"
95 #include "services/threadService.hpp"
96 #include "trace/traceMacros.hpp"
97 #include "trace/tracing.hpp"
98 #include "utilities/defaultStream.hpp"
99 #include "utilities/dtrace.hpp"
100 #include "utilities/events.hpp"
101 #include "utilities/macros.hpp"
102 #include "utilities/preserveException.hpp"
103 #if INCLUDE_ALL_GCS
104 #include "gc/shenandoah/shenandoahConcurrentThread.hpp"
105 #include "gc/cms/concurrentMarkSweepThread.hpp"
106 #include "gc/g1/concurrentMarkThread.inline.hpp"
107 #include "gc/parallel/pcTasks.hpp"
108 #endif // INCLUDE_ALL_GCS
109 #if INCLUDE_JVMCI
110 #include "jvmci/jvmciCompiler.hpp"
111 #include "jvmci/jvmciRuntime.hpp"
112 #endif
113 #ifdef COMPILER1
114 #include "c1/c1_Compiler.hpp"
115 #endif
116 #ifdef COMPILER2
117 #include "opto/c2compiler.hpp"
118 #include "opto/idealGraphPrinter.hpp"
119 #endif
120 #if INCLUDE_RTM_OPT
121 #include "runtime/rtmLocking.hpp"
122 #endif
123
124 // Initialization after module runtime initialization
125 void universe_post_module_init(); // must happen after call_initPhase2
126
127 #ifdef DTRACE_ENABLED
128
129 // Only bother with this argument setup if dtrace is available
130
131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
133
134 #define DTRACE_THREAD_PROBE(probe, javathread) \
135 { \
136 ResourceMark rm(this); \
137 int len = 0; \
138 const char* name = (javathread)->get_thread_name(); \
139 len = strlen(name); \
140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
141 (char *) name, len, \
142 java_lang_Thread::thread_id((javathread)->threadObj()), \
143 (uintptr_t) (javathread)->osthread()->thread_id(), \
144 java_lang_Thread::is_daemon((javathread)->threadObj())); \
145 }
146
147 #else // ndef DTRACE_ENABLED
148
149 #define DTRACE_THREAD_PROBE(probe, javathread)
150
151 #endif // ndef DTRACE_ENABLED
152
153 #ifndef USE_LIBRARY_BASED_TLS_ONLY
154 // Current thread is maintained as a thread-local variable
155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
156 #endif
157 // Class hierarchy
158 // - Thread
159 // - VMThread
160 // - WatcherThread
161 // - ConcurrentMarkSweepThread
162 // - JavaThread
163 // - CompilerThread
164
165 // ======= Thread ========
166 // Support for forcing alignment of thread objects for biased locking
167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
168 if (UseBiasedLocking) {
169 const int alignment = markOopDesc::biased_lock_alignment;
170 size_t aligned_size = size + (alignment - sizeof(intptr_t));
171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
172 : AllocateHeap(aligned_size, flags, CURRENT_PC,
173 AllocFailStrategy::RETURN_NULL);
174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
177 "JavaThread alignment code overflowed allocated storage");
178 if (aligned_addr != real_malloc_addr) {
179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
180 p2i(real_malloc_addr),
181 p2i(aligned_addr));
182 }
183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
184 return aligned_addr;
185 } else {
186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
188 }
189 }
190
191 void Thread::operator delete(void* p) {
192 if (UseBiasedLocking) {
193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
194 FreeHeap(real_malloc_addr);
195 } else {
196 FreeHeap(p);
197 }
198 }
199
200
201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
202 // JavaThread
203
204
205 Thread::Thread() {
206 // stack and get_thread
207 set_stack_base(NULL);
208 set_stack_size(0);
209 set_self_raw_id(0);
210 set_lgrp_id(-1);
211 DEBUG_ONLY(clear_suspendible_thread();)
212
213 // allocated data structures
214 set_osthread(NULL);
215 set_resource_area(new (mtThread)ResourceArea());
216 DEBUG_ONLY(_current_resource_mark = NULL;)
217 set_handle_area(new (mtThread) HandleArea(NULL));
218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
219 set_active_handles(NULL);
220 set_free_handle_block(NULL);
221 set_last_handle_mark(NULL);
222
223 // This initial value ==> never claimed.
224 _oops_do_parity = 0;
225
226 // the handle mark links itself to last_handle_mark
227 new HandleMark(this);
228
229 // plain initialization
230 debug_only(_owned_locks = NULL;)
231 debug_only(_allow_allocation_count = 0;)
232 NOT_PRODUCT(_allow_safepoint_count = 0;)
233 NOT_PRODUCT(_skip_gcalot = false;)
234 _jvmti_env_iteration_count = 0;
235 set_allocated_bytes(0);
236 _vm_operation_started_count = 0;
237 _vm_operation_completed_count = 0;
238 _current_pending_monitor = NULL;
239 _current_pending_monitor_is_from_java = true;
240 _current_waiting_monitor = NULL;
241 _num_nested_signal = 0;
242 omFreeList = NULL;
243 omFreeCount = 0;
244 omFreeProvision = 32;
245 omInUseList = NULL;
246 omInUseCount = 0;
247
248 #ifdef ASSERT
249 _visited_for_critical_count = false;
250 #endif
251
252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
253 Monitor::_safepoint_check_sometimes);
254 _suspend_flags = 0;
255
256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
257 _hashStateX = os::random();
258 _hashStateY = 842502087;
259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
260 _hashStateW = 273326509;
261
262 _OnTrap = 0;
263 _schedctl = NULL;
264 _Stalled = 0;
265 _TypeTag = 0x2BAD;
266
267 // Many of the following fields are effectively final - immutable
268 // Note that nascent threads can't use the Native Monitor-Mutex
269 // construct until the _MutexEvent is initialized ...
270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
271 // we might instead use a stack of ParkEvents that we could provision on-demand.
272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
273 // and ::Release()
274 _ParkEvent = ParkEvent::Allocate(this);
275 _SleepEvent = ParkEvent::Allocate(this);
276 _MutexEvent = ParkEvent::Allocate(this);
277 _MuxEvent = ParkEvent::Allocate(this);
278
279 #ifdef CHECK_UNHANDLED_OOPS
280 if (CheckUnhandledOops) {
281 _unhandled_oops = new UnhandledOops(this);
282 }
283 #endif // CHECK_UNHANDLED_OOPS
284 #ifdef ASSERT
285 if (UseBiasedLocking) {
286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
287 assert(this == _real_malloc_address ||
288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
289 "bug in forced alignment of thread objects");
290 }
291 #endif // ASSERT
292 }
293
294 void Thread::initialize_thread_current() {
295 #ifndef USE_LIBRARY_BASED_TLS_ONLY
296 assert(_thr_current == NULL, "Thread::current already initialized");
297 _thr_current = this;
298 #endif
299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
300 ThreadLocalStorage::set_thread(this);
301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
302 }
303
304 void Thread::clear_thread_current() {
305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
306 #ifndef USE_LIBRARY_BASED_TLS_ONLY
307 _thr_current = NULL;
308 #endif
309 ThreadLocalStorage::set_thread(NULL);
310 }
311
312 void Thread::record_stack_base_and_size() {
313 set_stack_base(os::current_stack_base());
314 set_stack_size(os::current_stack_size());
315 // CR 7190089: on Solaris, primordial thread's stack is adjusted
316 // in initialize_thread(). Without the adjustment, stack size is
317 // incorrect if stack is set to unlimited (ulimit -s unlimited).
318 // So far, only Solaris has real implementation of initialize_thread().
319 //
320 // set up any platform-specific state.
321 os::initialize_thread(this);
322
323 // Set stack limits after thread is initialized.
324 if (is_Java_thread()) {
325 ((JavaThread*) this)->set_stack_overflow_limit();
326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
327 }
328 #if INCLUDE_NMT
329 // record thread's native stack, stack grows downward
330 MemTracker::record_thread_stack(stack_end(), stack_size());
331 #endif // INCLUDE_NMT
332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
334 os::current_thread_id(), p2i(stack_base() - stack_size()),
335 p2i(stack_base()), stack_size()/1024);
336 }
337
338
339 Thread::~Thread() {
340 EVENT_THREAD_DESTRUCT(this);
341
342 // stack_base can be NULL if the thread is never started or exited before
343 // record_stack_base_and_size called. Although, we would like to ensure
344 // that all started threads do call record_stack_base_and_size(), there is
345 // not proper way to enforce that.
346 #if INCLUDE_NMT
347 if (_stack_base != NULL) {
348 MemTracker::release_thread_stack(stack_end(), stack_size());
349 #ifdef ASSERT
350 set_stack_base(NULL);
351 #endif
352 }
353 #endif // INCLUDE_NMT
354
355 // deallocate data structures
356 delete resource_area();
357 // since the handle marks are using the handle area, we have to deallocated the root
358 // handle mark before deallocating the thread's handle area,
359 assert(last_handle_mark() != NULL, "check we have an element");
360 delete last_handle_mark();
361 assert(last_handle_mark() == NULL, "check we have reached the end");
362
363 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
364 // We NULL out the fields for good hygiene.
365 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
366 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
367 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
368 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
369
370 delete handle_area();
371 delete metadata_handles();
372
373 // SR_handler uses this as a termination indicator -
374 // needs to happen before os::free_thread()
375 delete _SR_lock;
376 _SR_lock = NULL;
377
378 // osthread() can be NULL, if creation of thread failed.
379 if (osthread() != NULL) os::free_thread(osthread());
380
381 // clear Thread::current if thread is deleting itself.
382 // Needed to ensure JNI correctly detects non-attached threads.
383 if (this == Thread::current()) {
384 clear_thread_current();
385 }
386
387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
388 }
389
390 // NOTE: dummy function for assertion purpose.
391 void Thread::run() {
392 ShouldNotReachHere();
393 }
394
395 #ifdef ASSERT
396 // Private method to check for dangling thread pointer
397 void check_for_dangling_thread_pointer(Thread *thread) {
398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
399 "possibility of dangling Thread pointer");
400 }
401 #endif
402
403 ThreadPriority Thread::get_priority(const Thread* const thread) {
404 ThreadPriority priority;
405 // Can return an error!
406 (void)os::get_priority(thread, priority);
407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
408 return priority;
409 }
410
411 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
412 debug_only(check_for_dangling_thread_pointer(thread);)
413 // Can return an error!
414 (void)os::set_priority(thread, priority);
415 }
416
417
418 void Thread::start(Thread* thread) {
419 // Start is different from resume in that its safety is guaranteed by context or
420 // being called from a Java method synchronized on the Thread object.
421 if (!DisableStartThread) {
422 if (thread->is_Java_thread()) {
423 // Initialize the thread state to RUNNABLE before starting this thread.
424 // Can not set it after the thread started because we do not know the
425 // exact thread state at that time. It could be in MONITOR_WAIT or
426 // in SLEEPING or some other state.
427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
428 java_lang_Thread::RUNNABLE);
429 }
430 os::start_thread(thread);
431 }
432 }
433
434 // Enqueue a VM_Operation to do the job for us - sometime later
435 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
437 VMThread::execute(vm_stop);
438 }
439
440
441 // Check if an external suspend request has completed (or has been
442 // cancelled). Returns true if the thread is externally suspended and
443 // false otherwise.
444 //
445 // The bits parameter returns information about the code path through
446 // the routine. Useful for debugging:
447 //
448 // set in is_ext_suspend_completed():
449 // 0x00000001 - routine was entered
450 // 0x00000010 - routine return false at end
451 // 0x00000100 - thread exited (return false)
452 // 0x00000200 - suspend request cancelled (return false)
453 // 0x00000400 - thread suspended (return true)
454 // 0x00001000 - thread is in a suspend equivalent state (return true)
455 // 0x00002000 - thread is native and walkable (return true)
456 // 0x00004000 - thread is native_trans and walkable (needed retry)
457 //
458 // set in wait_for_ext_suspend_completion():
459 // 0x00010000 - routine was entered
460 // 0x00020000 - suspend request cancelled before loop (return false)
461 // 0x00040000 - thread suspended before loop (return true)
462 // 0x00080000 - suspend request cancelled in loop (return false)
463 // 0x00100000 - thread suspended in loop (return true)
464 // 0x00200000 - suspend not completed during retry loop (return false)
465
466 // Helper class for tracing suspend wait debug bits.
467 //
468 // 0x00000100 indicates that the target thread exited before it could
469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
470 // 0x00080000 each indicate a cancelled suspend request so they don't
471 // count as wait failures either.
472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
473
474 class TraceSuspendDebugBits : public StackObj {
475 private:
476 JavaThread * jt;
477 bool is_wait;
478 bool called_by_wait; // meaningful when !is_wait
479 uint32_t * bits;
480
481 public:
482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
483 uint32_t *_bits) {
484 jt = _jt;
485 is_wait = _is_wait;
486 called_by_wait = _called_by_wait;
487 bits = _bits;
488 }
489
490 ~TraceSuspendDebugBits() {
491 if (!is_wait) {
492 #if 1
493 // By default, don't trace bits for is_ext_suspend_completed() calls.
494 // That trace is very chatty.
495 return;
496 #else
497 if (!called_by_wait) {
498 // If tracing for is_ext_suspend_completed() is enabled, then only
499 // trace calls to it from wait_for_ext_suspend_completion()
500 return;
501 }
502 #endif
503 }
504
505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
507 MutexLocker ml(Threads_lock); // needed for get_thread_name()
508 ResourceMark rm;
509
510 tty->print_cr(
511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
512 jt->get_thread_name(), *bits);
513
514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
515 }
516 }
517 }
518 };
519 #undef DEBUG_FALSE_BITS
520
521
522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
523 uint32_t *bits) {
524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
525
526 bool did_trans_retry = false; // only do thread_in_native_trans retry once
527 bool do_trans_retry; // flag to force the retry
528
529 *bits |= 0x00000001;
530
531 do {
532 do_trans_retry = false;
533
534 if (is_exiting()) {
535 // Thread is in the process of exiting. This is always checked
536 // first to reduce the risk of dereferencing a freed JavaThread.
537 *bits |= 0x00000100;
538 return false;
539 }
540
541 if (!is_external_suspend()) {
542 // Suspend request is cancelled. This is always checked before
543 // is_ext_suspended() to reduce the risk of a rogue resume
544 // confusing the thread that made the suspend request.
545 *bits |= 0x00000200;
546 return false;
547 }
548
549 if (is_ext_suspended()) {
550 // thread is suspended
551 *bits |= 0x00000400;
552 return true;
553 }
554
555 // Now that we no longer do hard suspends of threads running
556 // native code, the target thread can be changing thread state
557 // while we are in this routine:
558 //
559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
560 //
561 // We save a copy of the thread state as observed at this moment
562 // and make our decision about suspend completeness based on the
563 // copy. This closes the race where the thread state is seen as
564 // _thread_in_native_trans in the if-thread_blocked check, but is
565 // seen as _thread_blocked in if-thread_in_native_trans check.
566 JavaThreadState save_state = thread_state();
567
568 if (save_state == _thread_blocked && is_suspend_equivalent()) {
569 // If the thread's state is _thread_blocked and this blocking
570 // condition is known to be equivalent to a suspend, then we can
571 // consider the thread to be externally suspended. This means that
572 // the code that sets _thread_blocked has been modified to do
573 // self-suspension if the blocking condition releases. We also
574 // used to check for CONDVAR_WAIT here, but that is now covered by
575 // the _thread_blocked with self-suspension check.
576 //
577 // Return true since we wouldn't be here unless there was still an
578 // external suspend request.
579 *bits |= 0x00001000;
580 return true;
581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
582 // Threads running native code will self-suspend on native==>VM/Java
583 // transitions. If its stack is walkable (should always be the case
584 // unless this function is called before the actual java_suspend()
585 // call), then the wait is done.
586 *bits |= 0x00002000;
587 return true;
588 } else if (!called_by_wait && !did_trans_retry &&
589 save_state == _thread_in_native_trans &&
590 frame_anchor()->walkable()) {
591 // The thread is transitioning from thread_in_native to another
592 // thread state. check_safepoint_and_suspend_for_native_trans()
593 // will force the thread to self-suspend. If it hasn't gotten
594 // there yet we may have caught the thread in-between the native
595 // code check above and the self-suspend. Lucky us. If we were
596 // called by wait_for_ext_suspend_completion(), then it
597 // will be doing the retries so we don't have to.
598 //
599 // Since we use the saved thread state in the if-statement above,
600 // there is a chance that the thread has already transitioned to
601 // _thread_blocked by the time we get here. In that case, we will
602 // make a single unnecessary pass through the logic below. This
603 // doesn't hurt anything since we still do the trans retry.
604
605 *bits |= 0x00004000;
606
607 // Once the thread leaves thread_in_native_trans for another
608 // thread state, we break out of this retry loop. We shouldn't
609 // need this flag to prevent us from getting back here, but
610 // sometimes paranoia is good.
611 did_trans_retry = true;
612
613 // We wait for the thread to transition to a more usable state.
614 for (int i = 1; i <= SuspendRetryCount; i++) {
615 // We used to do an "os::yield_all(i)" call here with the intention
616 // that yielding would increase on each retry. However, the parameter
617 // is ignored on Linux which means the yield didn't scale up. Waiting
618 // on the SR_lock below provides a much more predictable scale up for
619 // the delay. It also provides a simple/direct point to check for any
620 // safepoint requests from the VMThread
621
622 // temporarily drops SR_lock while doing wait with safepoint check
623 // (if we're a JavaThread - the WatcherThread can also call this)
624 // and increase delay with each retry
625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
626
627 // check the actual thread state instead of what we saved above
628 if (thread_state() != _thread_in_native_trans) {
629 // the thread has transitioned to another thread state so
630 // try all the checks (except this one) one more time.
631 do_trans_retry = true;
632 break;
633 }
634 } // end retry loop
635
636
637 }
638 } while (do_trans_retry);
639
640 *bits |= 0x00000010;
641 return false;
642 }
643
644 // Wait for an external suspend request to complete (or be cancelled).
645 // Returns true if the thread is externally suspended and false otherwise.
646 //
647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
648 uint32_t *bits) {
649 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
650 false /* !called_by_wait */, bits);
651
652 // local flag copies to minimize SR_lock hold time
653 bool is_suspended;
654 bool pending;
655 uint32_t reset_bits;
656
657 // set a marker so is_ext_suspend_completed() knows we are the caller
658 *bits |= 0x00010000;
659
660 // We use reset_bits to reinitialize the bits value at the top of
661 // each retry loop. This allows the caller to make use of any
662 // unused bits for their own marking purposes.
663 reset_bits = *bits;
664
665 {
666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
668 delay, bits);
669 pending = is_external_suspend();
670 }
671 // must release SR_lock to allow suspension to complete
672
673 if (!pending) {
674 // A cancelled suspend request is the only false return from
675 // is_ext_suspend_completed() that keeps us from entering the
676 // retry loop.
677 *bits |= 0x00020000;
678 return false;
679 }
680
681 if (is_suspended) {
682 *bits |= 0x00040000;
683 return true;
684 }
685
686 for (int i = 1; i <= retries; i++) {
687 *bits = reset_bits; // reinit to only track last retry
688
689 // We used to do an "os::yield_all(i)" call here with the intention
690 // that yielding would increase on each retry. However, the parameter
691 // is ignored on Linux which means the yield didn't scale up. Waiting
692 // on the SR_lock below provides a much more predictable scale up for
693 // the delay. It also provides a simple/direct point to check for any
694 // safepoint requests from the VMThread
695
696 {
697 MutexLocker ml(SR_lock());
698 // wait with safepoint check (if we're a JavaThread - the WatcherThread
699 // can also call this) and increase delay with each retry
700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
701
702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
703 delay, bits);
704
705 // It is possible for the external suspend request to be cancelled
706 // (by a resume) before the actual suspend operation is completed.
707 // Refresh our local copy to see if we still need to wait.
708 pending = is_external_suspend();
709 }
710
711 if (!pending) {
712 // A cancelled suspend request is the only false return from
713 // is_ext_suspend_completed() that keeps us from staying in the
714 // retry loop.
715 *bits |= 0x00080000;
716 return false;
717 }
718
719 if (is_suspended) {
720 *bits |= 0x00100000;
721 return true;
722 }
723 } // end retry loop
724
725 // thread did not suspend after all our retries
726 *bits |= 0x00200000;
727 return false;
728 }
729
730 #ifndef PRODUCT
731 void JavaThread::record_jump(address target, address instr, const char* file,
732 int line) {
733
734 // This should not need to be atomic as the only way for simultaneous
735 // updates is via interrupts. Even then this should be rare or non-existent
736 // and we don't care that much anyway.
737
738 int index = _jmp_ring_index;
739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
740 _jmp_ring[index]._target = (intptr_t) target;
741 _jmp_ring[index]._instruction = (intptr_t) instr;
742 _jmp_ring[index]._file = file;
743 _jmp_ring[index]._line = line;
744 }
745 #endif // PRODUCT
746
747 // Called by flat profiler
748 // Callers have already called wait_for_ext_suspend_completion
749 // The assertion for that is currently too complex to put here:
750 bool JavaThread::profile_last_Java_frame(frame* _fr) {
751 bool gotframe = false;
752 // self suspension saves needed state.
753 if (has_last_Java_frame() && _anchor.walkable()) {
754 *_fr = pd_last_frame();
755 gotframe = true;
756 }
757 return gotframe;
758 }
759
760 void Thread::interrupt(Thread* thread) {
761 debug_only(check_for_dangling_thread_pointer(thread);)
762 os::interrupt(thread);
763 }
764
765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
766 debug_only(check_for_dangling_thread_pointer(thread);)
767 // Note: If clear_interrupted==false, this simply fetches and
768 // returns the value of the field osthread()->interrupted().
769 return os::is_interrupted(thread, clear_interrupted);
770 }
771
772
773 // GC Support
774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
775 jint thread_parity = _oops_do_parity;
776 if (thread_parity != strong_roots_parity) {
777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
778 if (res == thread_parity) {
779 return true;
780 } else {
781 guarantee(res == strong_roots_parity, "Or else what?");
782 return false;
783 }
784 }
785 return false;
786 }
787
788 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
789 active_handles()->oops_do(f);
790 // Do oop for ThreadShadow
791 f->do_oop((oop*)&_pending_exception);
792 handle_area()->oops_do(f);
793 if (MonitorInUseLists) {
794 VM_Operation* op = VMThread::vm_operation();
795 if (op != NULL && op->deflates_idle_monitors()) {
796 ObjectSynchronizer::deflate_idle_monitors_and_oops_do(this, f);
797 } else {
798 ObjectSynchronizer::thread_local_used_oops_do(this, f);
799 }
800 }
801 }
802
803 void Thread::metadata_handles_do(void f(Metadata*)) {
804 // Only walk the Handles in Thread.
805 if (metadata_handles() != NULL) {
806 for (int i = 0; i< metadata_handles()->length(); i++) {
807 f(metadata_handles()->at(i));
808 }
809 }
810 }
811
812 void Thread::print_on(outputStream* st) const {
813 // get_priority assumes osthread initialized
814 if (osthread() != NULL) {
815 int os_prio;
816 if (os::get_native_priority(this, &os_prio) == OS_OK) {
817 st->print("os_prio=%d ", os_prio);
818 }
819 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
820 ext().print_on(st);
821 osthread()->print_on(st);
822 }
823 debug_only(if (WizardMode) print_owned_locks_on(st);)
824 }
825
826 // Thread::print_on_error() is called by fatal error handler. Don't use
827 // any lock or allocate memory.
828 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
829 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
830
831 if (is_VM_thread()) { st->print("VMThread"); }
832 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
833 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
834 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
835 else { st->print("Thread"); }
836
837 if (is_Named_thread()) {
838 st->print(" \"%s\"", name());
839 }
840
841 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
842 p2i(stack_end()), p2i(stack_base()));
843
844 if (osthread()) {
845 st->print(" [id=%d]", osthread()->thread_id());
846 }
847 }
848
849 #ifdef ASSERT
850 void Thread::print_owned_locks_on(outputStream* st) const {
851 Monitor *cur = _owned_locks;
852 if (cur == NULL) {
853 st->print(" (no locks) ");
854 } else {
855 st->print_cr(" Locks owned:");
856 while (cur) {
857 cur->print_on(st);
858 cur = cur->next();
859 }
860 }
861 }
862
863 static int ref_use_count = 0;
864
865 bool Thread::owns_locks_but_compiled_lock() const {
866 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
867 if (cur != Compile_lock) return true;
868 }
869 return false;
870 }
871
872
873 #endif
874
875 #ifndef PRODUCT
876
877 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
878 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
879 // no threads which allow_vm_block's are held
880 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
881 // Check if current thread is allowed to block at a safepoint
882 if (!(_allow_safepoint_count == 0)) {
883 fatal("Possible safepoint reached by thread that does not allow it");
884 }
885 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
886 fatal("LEAF method calling lock?");
887 }
888
889 #ifdef ASSERT
890 if (potential_vm_operation && is_Java_thread()
891 && !Universe::is_bootstrapping()) {
892 // Make sure we do not hold any locks that the VM thread also uses.
893 // This could potentially lead to deadlocks
894 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
895 // Threads_lock is special, since the safepoint synchronization will not start before this is
896 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
897 // since it is used to transfer control between JavaThreads and the VMThread
898 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
899 if ((cur->allow_vm_block() &&
900 cur != Threads_lock &&
901 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
902 cur != VMOperationRequest_lock &&
903 cur != VMOperationQueue_lock) ||
904 cur->rank() == Mutex::special) {
905 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
906 }
907 }
908 }
909
910 if (GCALotAtAllSafepoints) {
911 // We could enter a safepoint here and thus have a gc
912 InterfaceSupport::check_gc_alot();
913 }
914 #endif
915 }
916 #endif
917
918 bool Thread::is_in_stack(address adr) const {
919 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
920 address end = os::current_stack_pointer();
921 // Allow non Java threads to call this without stack_base
922 if (_stack_base == NULL) return true;
923 if (stack_base() >= adr && adr >= end) return true;
924
925 return false;
926 }
927
928 bool Thread::is_in_usable_stack(address adr) const {
929 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
930 size_t usable_stack_size = _stack_size - stack_guard_size;
931
932 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
933 }
934
935
936 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
937 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
938 // used for compilation in the future. If that change is made, the need for these methods
939 // should be revisited, and they should be removed if possible.
940
941 bool Thread::is_lock_owned(address adr) const {
942 return on_local_stack(adr);
943 }
944
945 bool Thread::set_as_starting_thread() {
946 // NOTE: this must be called inside the main thread.
947 return os::create_main_thread((JavaThread*)this);
948 }
949
950 static void initialize_class(Symbol* class_name, TRAPS) {
951 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
952 InstanceKlass::cast(klass)->initialize(CHECK);
953 }
954
955
956 // Creates the initial ThreadGroup
957 static Handle create_initial_thread_group(TRAPS) {
958 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
959 instanceKlassHandle klass (THREAD, k);
960
961 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
962 {
963 JavaValue result(T_VOID);
964 JavaCalls::call_special(&result,
965 system_instance,
966 klass,
967 vmSymbols::object_initializer_name(),
968 vmSymbols::void_method_signature(),
969 CHECK_NH);
970 }
971 Universe::set_system_thread_group(system_instance());
972
973 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
974 {
975 JavaValue result(T_VOID);
976 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
977 JavaCalls::call_special(&result,
978 main_instance,
979 klass,
980 vmSymbols::object_initializer_name(),
981 vmSymbols::threadgroup_string_void_signature(),
982 system_instance,
983 string,
984 CHECK_NH);
985 }
986 return main_instance;
987 }
988
989 // Creates the initial Thread
990 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
991 TRAPS) {
992 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
993 instanceKlassHandle klass (THREAD, k);
994 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
995
996 java_lang_Thread::set_thread(thread_oop(), thread);
997 java_lang_Thread::set_priority(thread_oop(), NormPriority);
998 thread->set_threadObj(thread_oop());
999
1000 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1001
1002 JavaValue result(T_VOID);
1003 JavaCalls::call_special(&result, thread_oop,
1004 klass,
1005 vmSymbols::object_initializer_name(),
1006 vmSymbols::threadgroup_string_void_signature(),
1007 thread_group,
1008 string,
1009 CHECK_NULL);
1010 return thread_oop();
1011 }
1012
1013 char java_runtime_name[128] = "";
1014 char java_runtime_version[128] = "";
1015
1016 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1017 static const char* get_java_runtime_name(TRAPS) {
1018 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1019 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1020 fieldDescriptor fd;
1021 bool found = k != NULL &&
1022 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1023 vmSymbols::string_signature(), &fd);
1024 if (found) {
1025 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1026 if (name_oop == NULL) {
1027 return NULL;
1028 }
1029 const char* name = java_lang_String::as_utf8_string(name_oop,
1030 java_runtime_name,
1031 sizeof(java_runtime_name));
1032 return name;
1033 } else {
1034 return NULL;
1035 }
1036 }
1037
1038 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1039 static const char* get_java_runtime_version(TRAPS) {
1040 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1041 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1042 fieldDescriptor fd;
1043 bool found = k != NULL &&
1044 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1045 vmSymbols::string_signature(), &fd);
1046 if (found) {
1047 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1048 if (name_oop == NULL) {
1049 return NULL;
1050 }
1051 const char* name = java_lang_String::as_utf8_string(name_oop,
1052 java_runtime_version,
1053 sizeof(java_runtime_version));
1054 return name;
1055 } else {
1056 return NULL;
1057 }
1058 }
1059
1060 // General purpose hook into Java code, run once when the VM is initialized.
1061 // The Java library method itself may be changed independently from the VM.
1062 static void call_postVMInitHook(TRAPS) {
1063 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1064 instanceKlassHandle klass (THREAD, k);
1065 if (klass.not_null()) {
1066 JavaValue result(T_VOID);
1067 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1068 vmSymbols::void_method_signature(),
1069 CHECK);
1070 }
1071 }
1072
1073 static void reset_vm_info_property(TRAPS) {
1074 // the vm info string
1075 ResourceMark rm(THREAD);
1076 const char *vm_info = VM_Version::vm_info_string();
1077
1078 // java.lang.System class
1079 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1080 instanceKlassHandle klass (THREAD, k);
1081
1082 // setProperty arguments
1083 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1084 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1085
1086 // return value
1087 JavaValue r(T_OBJECT);
1088
1089 // public static String setProperty(String key, String value);
1090 JavaCalls::call_static(&r,
1091 klass,
1092 vmSymbols::setProperty_name(),
1093 vmSymbols::string_string_string_signature(),
1094 key_str,
1095 value_str,
1096 CHECK);
1097 }
1098
1099
1100 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1101 bool daemon, TRAPS) {
1102 assert(thread_group.not_null(), "thread group should be specified");
1103 assert(threadObj() == NULL, "should only create Java thread object once");
1104
1105 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1106 instanceKlassHandle klass (THREAD, k);
1107 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1108
1109 java_lang_Thread::set_thread(thread_oop(), this);
1110 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1111 set_threadObj(thread_oop());
1112
1113 JavaValue result(T_VOID);
1114 if (thread_name != NULL) {
1115 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1116 // Thread gets assigned specified name and null target
1117 JavaCalls::call_special(&result,
1118 thread_oop,
1119 klass,
1120 vmSymbols::object_initializer_name(),
1121 vmSymbols::threadgroup_string_void_signature(),
1122 thread_group, // Argument 1
1123 name, // Argument 2
1124 THREAD);
1125 } else {
1126 // Thread gets assigned name "Thread-nnn" and null target
1127 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1128 JavaCalls::call_special(&result,
1129 thread_oop,
1130 klass,
1131 vmSymbols::object_initializer_name(),
1132 vmSymbols::threadgroup_runnable_void_signature(),
1133 thread_group, // Argument 1
1134 Handle(), // Argument 2
1135 THREAD);
1136 }
1137
1138
1139 if (daemon) {
1140 java_lang_Thread::set_daemon(thread_oop());
1141 }
1142
1143 if (HAS_PENDING_EXCEPTION) {
1144 return;
1145 }
1146
1147 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1148 Handle threadObj(THREAD, this->threadObj());
1149
1150 JavaCalls::call_special(&result,
1151 thread_group,
1152 group,
1153 vmSymbols::add_method_name(),
1154 vmSymbols::thread_void_signature(),
1155 threadObj, // Arg 1
1156 THREAD);
1157 }
1158
1159 // NamedThread -- non-JavaThread subclasses with multiple
1160 // uniquely named instances should derive from this.
1161 NamedThread::NamedThread() : Thread() {
1162 _name = NULL;
1163 _processed_thread = NULL;
1164 _gc_id = GCId::undefined();
1165 }
1166
1167 NamedThread::~NamedThread() {
1168 if (_name != NULL) {
1169 FREE_C_HEAP_ARRAY(char, _name);
1170 _name = NULL;
1171 }
1172 }
1173
1174 void NamedThread::set_name(const char* format, ...) {
1175 guarantee(_name == NULL, "Only get to set name once.");
1176 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1177 guarantee(_name != NULL, "alloc failure");
1178 va_list ap;
1179 va_start(ap, format);
1180 jio_vsnprintf(_name, max_name_len, format, ap);
1181 va_end(ap);
1182 }
1183
1184 void NamedThread::initialize_named_thread() {
1185 set_native_thread_name(name());
1186 }
1187
1188 void NamedThread::print_on(outputStream* st) const {
1189 st->print("\"%s\" ", name());
1190 Thread::print_on(st);
1191 st->cr();
1192 }
1193
1194
1195 // ======= WatcherThread ========
1196
1197 // The watcher thread exists to simulate timer interrupts. It should
1198 // be replaced by an abstraction over whatever native support for
1199 // timer interrupts exists on the platform.
1200
1201 WatcherThread* WatcherThread::_watcher_thread = NULL;
1202 bool WatcherThread::_startable = false;
1203 volatile bool WatcherThread::_should_terminate = false;
1204
1205 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1206 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1207 if (os::create_thread(this, os::watcher_thread)) {
1208 _watcher_thread = this;
1209
1210 // WatcherThread needs GCLAB for cases when it writes to Java heap,
1211 // and needs the space to evacuate. Have to initialize here, because
1212 // WatcherThread is initialized before the Universe.
1213 if (UseShenandoahGC && UseTLAB) {
1214 gclab().initialize(true);
1215 }
1216
1217 // Set the watcher thread to the highest OS priority which should not be
1218 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1219 // is created. The only normal thread using this priority is the reference
1220 // handler thread, which runs for very short intervals only.
1221 // If the VMThread's priority is not lower than the WatcherThread profiling
1222 // will be inaccurate.
1223 os::set_priority(this, MaxPriority);
1224 if (!DisableStartThread) {
1225 os::start_thread(this);
1226 }
1227 }
1228 }
1229
1230 int WatcherThread::sleep() const {
1231 // The WatcherThread does not participate in the safepoint protocol
1232 // for the PeriodicTask_lock because it is not a JavaThread.
1233 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1234
1235 if (_should_terminate) {
1236 // check for termination before we do any housekeeping or wait
1237 return 0; // we did not sleep.
1238 }
1239
1240 // remaining will be zero if there are no tasks,
1241 // causing the WatcherThread to sleep until a task is
1242 // enrolled
1243 int remaining = PeriodicTask::time_to_wait();
1244 int time_slept = 0;
1245
1246 // we expect this to timeout - we only ever get unparked when
1247 // we should terminate or when a new task has been enrolled
1248 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1249
1250 jlong time_before_loop = os::javaTimeNanos();
1251
1252 while (true) {
1253 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1254 remaining);
1255 jlong now = os::javaTimeNanos();
1256
1257 if (remaining == 0) {
1258 // if we didn't have any tasks we could have waited for a long time
1259 // consider the time_slept zero and reset time_before_loop
1260 time_slept = 0;
1261 time_before_loop = now;
1262 } else {
1263 // need to recalculate since we might have new tasks in _tasks
1264 time_slept = (int) ((now - time_before_loop) / 1000000);
1265 }
1266
1267 // Change to task list or spurious wakeup of some kind
1268 if (timedout || _should_terminate) {
1269 break;
1270 }
1271
1272 remaining = PeriodicTask::time_to_wait();
1273 if (remaining == 0) {
1274 // Last task was just disenrolled so loop around and wait until
1275 // another task gets enrolled
1276 continue;
1277 }
1278
1279 remaining -= time_slept;
1280 if (remaining <= 0) {
1281 break;
1282 }
1283 }
1284
1285 return time_slept;
1286 }
1287
1288 void WatcherThread::run() {
1289 assert(this == watcher_thread(), "just checking");
1290
1291 this->record_stack_base_and_size();
1292 this->set_native_thread_name(this->name());
1293 this->set_active_handles(JNIHandleBlock::allocate_block());
1294 while (true) {
1295 assert(watcher_thread() == Thread::current(), "thread consistency check");
1296 assert(watcher_thread() == this, "thread consistency check");
1297
1298 // Calculate how long it'll be until the next PeriodicTask work
1299 // should be done, and sleep that amount of time.
1300 int time_waited = sleep();
1301
1302 if (is_error_reported()) {
1303 // A fatal error has happened, the error handler(VMError::report_and_die)
1304 // should abort JVM after creating an error log file. However in some
1305 // rare cases, the error handler itself might deadlock. Here we try to
1306 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1307 //
1308 // This code is in WatcherThread because WatcherThread wakes up
1309 // periodically so the fatal error handler doesn't need to do anything;
1310 // also because the WatcherThread is less likely to crash than other
1311 // threads.
1312
1313 for (;;) {
1314 if (!ShowMessageBoxOnError
1315 && (OnError == NULL || OnError[0] == '\0')
1316 && Arguments::abort_hook() == NULL) {
1317 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds
1318 fdStream err(defaultStream::output_fd());
1319 err.print_raw_cr("# [ timer expired, abort... ]");
1320 // skip atexit/vm_exit/vm_abort hooks
1321 os::die();
1322 }
1323
1324 // Wake up 5 seconds later, the fatal handler may reset OnError or
1325 // ShowMessageBoxOnError when it is ready to abort.
1326 os::sleep(this, 5 * 1000, false);
1327 }
1328 }
1329
1330 if (_should_terminate) {
1331 // check for termination before posting the next tick
1332 break;
1333 }
1334
1335 PeriodicTask::real_time_tick(time_waited);
1336 }
1337
1338 // Signal that it is terminated
1339 {
1340 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1341 _watcher_thread = NULL;
1342 Terminator_lock->notify();
1343 }
1344 }
1345
1346 void WatcherThread::start() {
1347 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1348
1349 if (watcher_thread() == NULL && _startable) {
1350 _should_terminate = false;
1351 // Create the single instance of WatcherThread
1352 new WatcherThread();
1353 }
1354 }
1355
1356 void WatcherThread::make_startable() {
1357 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1358 _startable = true;
1359 }
1360
1361 void WatcherThread::stop() {
1362 {
1363 // Follow normal safepoint aware lock enter protocol since the
1364 // WatcherThread is stopped by another JavaThread.
1365 MutexLocker ml(PeriodicTask_lock);
1366 _should_terminate = true;
1367
1368 WatcherThread* watcher = watcher_thread();
1369 if (watcher != NULL) {
1370 // unpark the WatcherThread so it can see that it should terminate
1371 watcher->unpark();
1372 }
1373 }
1374
1375 MutexLocker mu(Terminator_lock);
1376
1377 while (watcher_thread() != NULL) {
1378 // This wait should make safepoint checks, wait without a timeout,
1379 // and wait as a suspend-equivalent condition.
1380 //
1381 // Note: If the FlatProfiler is running, then this thread is waiting
1382 // for the WatcherThread to terminate and the WatcherThread, via the
1383 // FlatProfiler task, is waiting for the external suspend request on
1384 // this thread to complete. wait_for_ext_suspend_completion() will
1385 // eventually timeout, but that takes time. Making this wait a
1386 // suspend-equivalent condition solves that timeout problem.
1387 //
1388 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1389 Mutex::_as_suspend_equivalent_flag);
1390 }
1391 }
1392
1393 void WatcherThread::unpark() {
1394 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1395 PeriodicTask_lock->notify();
1396 }
1397
1398 void WatcherThread::print_on(outputStream* st) const {
1399 st->print("\"%s\" ", name());
1400 Thread::print_on(st);
1401 st->cr();
1402 }
1403
1404 // ======= JavaThread ========
1405
1406 #if INCLUDE_JVMCI
1407
1408 jlong* JavaThread::_jvmci_old_thread_counters;
1409
1410 bool jvmci_counters_include(JavaThread* thread) {
1411 oop threadObj = thread->threadObj();
1412 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1413 }
1414
1415 void JavaThread::collect_counters(typeArrayOop array) {
1416 if (JVMCICounterSize > 0) {
1417 MutexLocker tl(Threads_lock);
1418 for (int i = 0; i < array->length(); i++) {
1419 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1420 }
1421 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
1422 if (jvmci_counters_include(tp)) {
1423 for (int i = 0; i < array->length(); i++) {
1424 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1425 }
1426 }
1427 }
1428 }
1429 }
1430
1431 #endif // INCLUDE_JVMCI
1432
1433 // A JavaThread is a normal Java thread
1434
1435 void JavaThread::initialize() {
1436 // Initialize fields
1437
1438 set_saved_exception_pc(NULL);
1439 set_threadObj(NULL);
1440 _anchor.clear();
1441 set_entry_point(NULL);
1442 set_jni_functions(jni_functions());
1443 set_callee_target(NULL);
1444 set_vm_result(NULL);
1445 set_vm_result_2(NULL);
1446 set_vframe_array_head(NULL);
1447 set_vframe_array_last(NULL);
1448 set_deferred_locals(NULL);
1449 set_deopt_mark(NULL);
1450 set_deopt_compiled_method(NULL);
1451 clear_must_deopt_id();
1452 set_monitor_chunks(NULL);
1453 set_next(NULL);
1454 set_thread_state(_thread_new);
1455 _terminated = _not_terminated;
1456 _privileged_stack_top = NULL;
1457 _array_for_gc = NULL;
1458 _suspend_equivalent = false;
1459 _in_deopt_handler = 0;
1460 _doing_unsafe_access = false;
1461 _stack_guard_state = stack_guard_unused;
1462 #if INCLUDE_JVMCI
1463 _pending_monitorenter = false;
1464 _pending_deoptimization = -1;
1465 _pending_failed_speculation = NULL;
1466 _pending_transfer_to_interpreter = false;
1467 _adjusting_comp_level = false;
1468 _jvmci._alternate_call_target = NULL;
1469 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1470 if (JVMCICounterSize > 0) {
1471 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1472 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1473 } else {
1474 _jvmci_counters = NULL;
1475 }
1476 #endif // INCLUDE_JVMCI
1477 _reserved_stack_activation = NULL; // stack base not known yet
1478 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1479 _exception_pc = 0;
1480 _exception_handler_pc = 0;
1481 _is_method_handle_return = 0;
1482 _jvmti_thread_state= NULL;
1483 _should_post_on_exceptions_flag = JNI_FALSE;
1484 _jvmti_get_loaded_classes_closure = NULL;
1485 _interp_only_mode = 0;
1486 _special_runtime_exit_condition = _no_async_condition;
1487 _pending_async_exception = NULL;
1488 _thread_stat = NULL;
1489 _thread_stat = new ThreadStatistics();
1490 _blocked_on_compilation = false;
1491 _jni_active_critical = 0;
1492 _pending_jni_exception_check_fn = NULL;
1493 _do_not_unlock_if_synchronized = false;
1494 _cached_monitor_info = NULL;
1495 _parker = Parker::Allocate(this);
1496
1497 #ifndef PRODUCT
1498 _jmp_ring_index = 0;
1499 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1500 record_jump(NULL, NULL, NULL, 0);
1501 }
1502 #endif // PRODUCT
1503
1504 set_thread_profiler(NULL);
1505 if (FlatProfiler::is_active()) {
1506 // This is where we would decide to either give each thread it's own profiler
1507 // or use one global one from FlatProfiler,
1508 // or up to some count of the number of profiled threads, etc.
1509 ThreadProfiler* pp = new ThreadProfiler();
1510 pp->engage();
1511 set_thread_profiler(pp);
1512 }
1513
1514 // Setup safepoint state info for this thread
1515 ThreadSafepointState::create(this);
1516
1517 debug_only(_java_call_counter = 0);
1518
1519 // JVMTI PopFrame support
1520 _popframe_condition = popframe_inactive;
1521 _popframe_preserved_args = NULL;
1522 _popframe_preserved_args_size = 0;
1523 _frames_to_pop_failed_realloc = 0;
1524
1525 pd_initialize();
1526 }
1527
1528 #if INCLUDE_ALL_GCS
1529 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1530 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1531 bool JavaThread::_evacuation_in_progress_global = false;
1532 #endif // INCLUDE_ALL_GCS
1533
1534 JavaThread::JavaThread(bool is_attaching_via_jni) :
1535 Thread()
1536 #if INCLUDE_ALL_GCS
1537 , _satb_mark_queue(&_satb_mark_queue_set),
1538 _dirty_card_queue(&_dirty_card_queue_set),
1539 _evacuation_in_progress(_evacuation_in_progress_global)
1540 #endif // INCLUDE_ALL_GCS
1541 {
1542 initialize();
1543 if (is_attaching_via_jni) {
1544 _jni_attach_state = _attaching_via_jni;
1545 } else {
1546 _jni_attach_state = _not_attaching_via_jni;
1547 }
1548 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1549 }
1550
1551 bool JavaThread::reguard_stack(address cur_sp) {
1552 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1553 && _stack_guard_state != stack_guard_reserved_disabled) {
1554 return true; // Stack already guarded or guard pages not needed.
1555 }
1556
1557 if (register_stack_overflow()) {
1558 // For those architectures which have separate register and
1559 // memory stacks, we must check the register stack to see if
1560 // it has overflowed.
1561 return false;
1562 }
1563
1564 // Java code never executes within the yellow zone: the latter is only
1565 // there to provoke an exception during stack banging. If java code
1566 // is executing there, either StackShadowPages should be larger, or
1567 // some exception code in c1, c2 or the interpreter isn't unwinding
1568 // when it should.
1569 guarantee(cur_sp > stack_reserved_zone_base(),
1570 "not enough space to reguard - increase StackShadowPages");
1571 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1572 enable_stack_yellow_reserved_zone();
1573 if (reserved_stack_activation() != stack_base()) {
1574 set_reserved_stack_activation(stack_base());
1575 }
1576 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1577 set_reserved_stack_activation(stack_base());
1578 enable_stack_reserved_zone();
1579 }
1580 return true;
1581 }
1582
1583 bool JavaThread::reguard_stack(void) {
1584 return reguard_stack(os::current_stack_pointer());
1585 }
1586
1587
1588 void JavaThread::block_if_vm_exited() {
1589 if (_terminated == _vm_exited) {
1590 // _vm_exited is set at safepoint, and Threads_lock is never released
1591 // we will block here forever
1592 Threads_lock->lock_without_safepoint_check();
1593 ShouldNotReachHere();
1594 }
1595 }
1596
1597
1598 // Remove this ifdef when C1 is ported to the compiler interface.
1599 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1600 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1601
1602 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1603 Thread()
1604 #if INCLUDE_ALL_GCS
1605 , _satb_mark_queue(&_satb_mark_queue_set),
1606 _dirty_card_queue(&_dirty_card_queue_set),
1607 _evacuation_in_progress(_evacuation_in_progress_global)
1608 #endif // INCLUDE_ALL_GCS
1609 {
1610 initialize();
1611 _jni_attach_state = _not_attaching_via_jni;
1612 set_entry_point(entry_point);
1613 // Create the native thread itself.
1614 // %note runtime_23
1615 os::ThreadType thr_type = os::java_thread;
1616 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1617 os::java_thread;
1618 os::create_thread(this, thr_type, stack_sz);
1619 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1620 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1621 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1622 // the exception consists of creating the exception object & initializing it, initialization
1623 // will leave the VM via a JavaCall and then all locks must be unlocked).
1624 //
1625 // The thread is still suspended when we reach here. Thread must be explicit started
1626 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1627 // by calling Threads:add. The reason why this is not done here, is because the thread
1628 // object must be fully initialized (take a look at JVM_Start)
1629 }
1630
1631 JavaThread::~JavaThread() {
1632
1633 // JSR166 -- return the parker to the free list
1634 Parker::Release(_parker);
1635 _parker = NULL;
1636
1637 // Free any remaining previous UnrollBlock
1638 vframeArray* old_array = vframe_array_last();
1639
1640 if (old_array != NULL) {
1641 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1642 old_array->set_unroll_block(NULL);
1643 delete old_info;
1644 delete old_array;
1645 }
1646
1647 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1648 if (deferred != NULL) {
1649 // This can only happen if thread is destroyed before deoptimization occurs.
1650 assert(deferred->length() != 0, "empty array!");
1651 do {
1652 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1653 deferred->remove_at(0);
1654 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1655 delete dlv;
1656 } while (deferred->length() != 0);
1657 delete deferred;
1658 }
1659
1660 // All Java related clean up happens in exit
1661 ThreadSafepointState::destroy(this);
1662 if (_thread_profiler != NULL) delete _thread_profiler;
1663 if (_thread_stat != NULL) delete _thread_stat;
1664
1665 #if INCLUDE_JVMCI
1666 if (JVMCICounterSize > 0) {
1667 if (jvmci_counters_include(this)) {
1668 for (int i = 0; i < JVMCICounterSize; i++) {
1669 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1670 }
1671 }
1672 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1673 }
1674 #endif // INCLUDE_JVMCI
1675 }
1676
1677
1678 // The first routine called by a new Java thread
1679 void JavaThread::run() {
1680 // initialize thread-local alloc buffer related fields
1681 this->initialize_tlab();
1682
1683 // used to test validity of stack trace backs
1684 this->record_base_of_stack_pointer();
1685
1686 // Record real stack base and size.
1687 this->record_stack_base_and_size();
1688
1689 this->create_stack_guard_pages();
1690
1691 this->cache_global_variables();
1692
1693 // Thread is now sufficient initialized to be handled by the safepoint code as being
1694 // in the VM. Change thread state from _thread_new to _thread_in_vm
1695 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1696
1697 assert(JavaThread::current() == this, "sanity check");
1698 assert(!Thread::current()->owns_locks(), "sanity check");
1699
1700 DTRACE_THREAD_PROBE(start, this);
1701
1702 // This operation might block. We call that after all safepoint checks for a new thread has
1703 // been completed.
1704 this->set_active_handles(JNIHandleBlock::allocate_block());
1705
1706 if (JvmtiExport::should_post_thread_life()) {
1707 JvmtiExport::post_thread_start(this);
1708 }
1709
1710 EventThreadStart event;
1711 if (event.should_commit()) {
1712 event.set_thread(THREAD_TRACE_ID(this));
1713 event.commit();
1714 }
1715
1716 // We call another function to do the rest so we are sure that the stack addresses used
1717 // from there will be lower than the stack base just computed
1718 thread_main_inner();
1719
1720 // Note, thread is no longer valid at this point!
1721 }
1722
1723
1724 void JavaThread::thread_main_inner() {
1725 assert(JavaThread::current() == this, "sanity check");
1726 assert(this->threadObj() != NULL, "just checking");
1727
1728 // Execute thread entry point unless this thread has a pending exception
1729 // or has been stopped before starting.
1730 // Note: Due to JVM_StopThread we can have pending exceptions already!
1731 if (!this->has_pending_exception() &&
1732 !java_lang_Thread::is_stillborn(this->threadObj())) {
1733 {
1734 ResourceMark rm(this);
1735 this->set_native_thread_name(this->get_thread_name());
1736 }
1737 HandleMark hm(this);
1738 this->entry_point()(this, this);
1739 }
1740
1741 DTRACE_THREAD_PROBE(stop, this);
1742
1743 this->exit(false);
1744 delete this;
1745 }
1746
1747
1748 static void ensure_join(JavaThread* thread) {
1749 // We do not need to grap the Threads_lock, since we are operating on ourself.
1750 Handle threadObj(thread, thread->threadObj());
1751 assert(threadObj.not_null(), "java thread object must exist");
1752 ObjectLocker lock(threadObj, thread);
1753 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1754 thread->clear_pending_exception();
1755 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1756 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1757 // Clear the native thread instance - this makes isAlive return false and allows the join()
1758 // to complete once we've done the notify_all below
1759 java_lang_Thread::set_thread(threadObj(), NULL);
1760 lock.notify_all(thread);
1761 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1762 thread->clear_pending_exception();
1763 }
1764
1765
1766 // For any new cleanup additions, please check to see if they need to be applied to
1767 // cleanup_failed_attach_current_thread as well.
1768 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1769 assert(this == JavaThread::current(), "thread consistency check");
1770
1771 HandleMark hm(this);
1772 Handle uncaught_exception(this, this->pending_exception());
1773 this->clear_pending_exception();
1774 Handle threadObj(this, this->threadObj());
1775 assert(threadObj.not_null(), "Java thread object should be created");
1776
1777 if (get_thread_profiler() != NULL) {
1778 get_thread_profiler()->disengage();
1779 ResourceMark rm;
1780 get_thread_profiler()->print(get_thread_name());
1781 }
1782
1783
1784 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1785 {
1786 EXCEPTION_MARK;
1787
1788 CLEAR_PENDING_EXCEPTION;
1789 }
1790 if (!destroy_vm) {
1791 if (uncaught_exception.not_null()) {
1792 EXCEPTION_MARK;
1793 // Call method Thread.dispatchUncaughtException().
1794 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1795 JavaValue result(T_VOID);
1796 JavaCalls::call_virtual(&result,
1797 threadObj, thread_klass,
1798 vmSymbols::dispatchUncaughtException_name(),
1799 vmSymbols::throwable_void_signature(),
1800 uncaught_exception,
1801 THREAD);
1802 if (HAS_PENDING_EXCEPTION) {
1803 ResourceMark rm(this);
1804 jio_fprintf(defaultStream::error_stream(),
1805 "\nException: %s thrown from the UncaughtExceptionHandler"
1806 " in thread \"%s\"\n",
1807 pending_exception()->klass()->external_name(),
1808 get_thread_name());
1809 CLEAR_PENDING_EXCEPTION;
1810 }
1811 }
1812
1813 // Called before the java thread exit since we want to read info
1814 // from java_lang_Thread object
1815 EventThreadEnd event;
1816 if (event.should_commit()) {
1817 event.set_thread(THREAD_TRACE_ID(this));
1818 event.commit();
1819 }
1820
1821 // Call after last event on thread
1822 EVENT_THREAD_EXIT(this);
1823
1824 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1825 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1826 // is deprecated anyhow.
1827 if (!is_Compiler_thread()) {
1828 int count = 3;
1829 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1830 EXCEPTION_MARK;
1831 JavaValue result(T_VOID);
1832 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1833 JavaCalls::call_virtual(&result,
1834 threadObj, thread_klass,
1835 vmSymbols::exit_method_name(),
1836 vmSymbols::void_method_signature(),
1837 THREAD);
1838 CLEAR_PENDING_EXCEPTION;
1839 }
1840 }
1841 // notify JVMTI
1842 if (JvmtiExport::should_post_thread_life()) {
1843 JvmtiExport::post_thread_end(this);
1844 }
1845
1846 // We have notified the agents that we are exiting, before we go on,
1847 // we must check for a pending external suspend request and honor it
1848 // in order to not surprise the thread that made the suspend request.
1849 while (true) {
1850 {
1851 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1852 if (!is_external_suspend()) {
1853 set_terminated(_thread_exiting);
1854 ThreadService::current_thread_exiting(this);
1855 break;
1856 }
1857 // Implied else:
1858 // Things get a little tricky here. We have a pending external
1859 // suspend request, but we are holding the SR_lock so we
1860 // can't just self-suspend. So we temporarily drop the lock
1861 // and then self-suspend.
1862 }
1863
1864 ThreadBlockInVM tbivm(this);
1865 java_suspend_self();
1866
1867 // We're done with this suspend request, but we have to loop around
1868 // and check again. Eventually we will get SR_lock without a pending
1869 // external suspend request and will be able to mark ourselves as
1870 // exiting.
1871 }
1872 // no more external suspends are allowed at this point
1873 } else {
1874 // before_exit() has already posted JVMTI THREAD_END events
1875 }
1876
1877 // Notify waiters on thread object. This has to be done after exit() is called
1878 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1879 // group should have the destroyed bit set before waiters are notified).
1880 ensure_join(this);
1881 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1882
1883 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1884 // held by this thread must be released. The spec does not distinguish
1885 // between JNI-acquired and regular Java monitors. We can only see
1886 // regular Java monitors here if monitor enter-exit matching is broken.
1887 //
1888 // Optionally release any monitors for regular JavaThread exits. This
1889 // is provided as a work around for any bugs in monitor enter-exit
1890 // matching. This can be expensive so it is not enabled by default.
1891 //
1892 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1893 // ObjectSynchronizer::release_monitors_owned_by_thread().
1894 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1895 // Sanity check even though JNI DetachCurrentThread() would have
1896 // returned JNI_ERR if there was a Java frame. JavaThread exit
1897 // should be done executing Java code by the time we get here.
1898 assert(!this->has_last_Java_frame(),
1899 "should not have a Java frame when detaching or exiting");
1900 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1901 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1902 }
1903
1904 // These things needs to be done while we are still a Java Thread. Make sure that thread
1905 // is in a consistent state, in case GC happens
1906 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1907
1908 if (active_handles() != NULL) {
1909 JNIHandleBlock* block = active_handles();
1910 set_active_handles(NULL);
1911 JNIHandleBlock::release_block(block);
1912 }
1913
1914 if (free_handle_block() != NULL) {
1915 JNIHandleBlock* block = free_handle_block();
1916 set_free_handle_block(NULL);
1917 JNIHandleBlock::release_block(block);
1918 }
1919
1920 // These have to be removed while this is still a valid thread.
1921 remove_stack_guard_pages();
1922
1923 if (UseTLAB) {
1924 tlab().make_parsable(true); // retire TLAB
1925 }
1926
1927 if (JvmtiEnv::environments_might_exist()) {
1928 JvmtiExport::cleanup_thread(this);
1929 }
1930
1931 // We must flush any deferred card marks before removing a thread from
1932 // the list of active threads.
1933 Universe::heap()->flush_deferred_store_barrier(this);
1934 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1935
1936 #if INCLUDE_ALL_GCS
1937 // We must flush the G1-related buffers before removing a thread
1938 // from the list of active threads. We must do this after any deferred
1939 // card marks have been flushed (above) so that any entries that are
1940 // added to the thread's dirty card queue as a result are not lost.
1941 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
1942 flush_barrier_queues();
1943 }
1944 if (UseShenandoahGC && UseTLAB) {
1945 gclab().make_parsable(true);
1946 }
1947 #endif // INCLUDE_ALL_GCS
1948
1949 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
1950 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
1951 os::current_thread_id());
1952
1953 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1954 Threads::remove(this);
1955 }
1956
1957 #if INCLUDE_ALL_GCS
1958 // Flush G1-related queues.
1959 void JavaThread::flush_barrier_queues() {
1960 satb_mark_queue().flush();
1961 dirty_card_queue().flush();
1962 }
1963
1964 void JavaThread::initialize_queues() {
1965 assert(!SafepointSynchronize::is_at_safepoint(),
1966 "we should not be at a safepoint");
1967
1968 SATBMarkQueue& satb_queue = satb_mark_queue();
1969 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1970 // The SATB queue should have been constructed with its active
1971 // field set to false.
1972 assert(!satb_queue.is_active(), "SATB queue should not be active");
1973 assert(satb_queue.is_empty(), "SATB queue should be empty");
1974 // If we are creating the thread during a marking cycle, we should
1975 // set the active field of the SATB queue to true.
1976 if (satb_queue_set.is_active()) {
1977 satb_queue.set_active(true);
1978 }
1979
1980 DirtyCardQueue& dirty_queue = dirty_card_queue();
1981 // The dirty card queue should have been constructed with its
1982 // active field set to true.
1983 assert(dirty_queue.is_active(), "dirty card queue should be active");
1984
1985 _evacuation_in_progress = _evacuation_in_progress_global;
1986 }
1987
1988 bool JavaThread::evacuation_in_progress() const {
1989 return _evacuation_in_progress;
1990 }
1991
1992 void JavaThread::set_evacuation_in_progress(bool in_prog) {
1993 _evacuation_in_progress = in_prog;
1994 }
1995
1996 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) {
1997 assert_locked_or_safepoint(Threads_lock);
1998 _evacuation_in_progress_global = in_prog;
1999 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) {
2000 t->set_evacuation_in_progress(in_prog);
2001 }
2002 }
2003 #endif // INCLUDE_ALL_GCS
2004
2005 void JavaThread::cleanup_failed_attach_current_thread() {
2006 if (get_thread_profiler() != NULL) {
2007 get_thread_profiler()->disengage();
2008 ResourceMark rm;
2009 get_thread_profiler()->print(get_thread_name());
2010 }
2011
2012 if (active_handles() != NULL) {
2013 JNIHandleBlock* block = active_handles();
2014 set_active_handles(NULL);
2015 JNIHandleBlock::release_block(block);
2016 }
2017
2018 if (free_handle_block() != NULL) {
2019 JNIHandleBlock* block = free_handle_block();
2020 set_free_handle_block(NULL);
2021 JNIHandleBlock::release_block(block);
2022 }
2023
2024 // These have to be removed while this is still a valid thread.
2025 remove_stack_guard_pages();
2026
2027 if (UseTLAB) {
2028 tlab().make_parsable(true); // retire TLAB, if any
2029 }
2030
2031 #if INCLUDE_ALL_GCS
2032 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) {
2033 flush_barrier_queues();
2034 }
2035 if (UseShenandoahGC && UseTLAB) {
2036 gclab().make_parsable(true);
2037 }
2038 #endif // INCLUDE_ALL_GCS
2039
2040 Threads::remove(this);
2041 delete this;
2042 }
2043
2044
2045
2046
2047 JavaThread* JavaThread::active() {
2048 Thread* thread = Thread::current();
2049 if (thread->is_Java_thread()) {
2050 return (JavaThread*) thread;
2051 } else {
2052 assert(thread->is_VM_thread(), "this must be a vm thread");
2053 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2054 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2055 assert(ret->is_Java_thread(), "must be a Java thread");
2056 return ret;
2057 }
2058 }
2059
2060 bool JavaThread::is_lock_owned(address adr) const {
2061 if (Thread::is_lock_owned(adr)) return true;
2062
2063 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2064 if (chunk->contains(adr)) return true;
2065 }
2066
2067 return false;
2068 }
2069
2070
2071 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2072 chunk->set_next(monitor_chunks());
2073 set_monitor_chunks(chunk);
2074 }
2075
2076 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2077 guarantee(monitor_chunks() != NULL, "must be non empty");
2078 if (monitor_chunks() == chunk) {
2079 set_monitor_chunks(chunk->next());
2080 } else {
2081 MonitorChunk* prev = monitor_chunks();
2082 while (prev->next() != chunk) prev = prev->next();
2083 prev->set_next(chunk->next());
2084 }
2085 }
2086
2087 // JVM support.
2088
2089 // Note: this function shouldn't block if it's called in
2090 // _thread_in_native_trans state (such as from
2091 // check_special_condition_for_native_trans()).
2092 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2093
2094 if (has_last_Java_frame() && has_async_condition()) {
2095 // If we are at a polling page safepoint (not a poll return)
2096 // then we must defer async exception because live registers
2097 // will be clobbered by the exception path. Poll return is
2098 // ok because the call we a returning from already collides
2099 // with exception handling registers and so there is no issue.
2100 // (The exception handling path kills call result registers but
2101 // this is ok since the exception kills the result anyway).
2102
2103 if (is_at_poll_safepoint()) {
2104 // if the code we are returning to has deoptimized we must defer
2105 // the exception otherwise live registers get clobbered on the
2106 // exception path before deoptimization is able to retrieve them.
2107 //
2108 RegisterMap map(this, false);
2109 frame caller_fr = last_frame().sender(&map);
2110 assert(caller_fr.is_compiled_frame(), "what?");
2111 if (caller_fr.is_deoptimized_frame()) {
2112 log_info(exceptions)("deferred async exception at compiled safepoint");
2113 return;
2114 }
2115 }
2116 }
2117
2118 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2119 if (condition == _no_async_condition) {
2120 // Conditions have changed since has_special_runtime_exit_condition()
2121 // was called:
2122 // - if we were here only because of an external suspend request,
2123 // then that was taken care of above (or cancelled) so we are done
2124 // - if we were here because of another async request, then it has
2125 // been cleared between the has_special_runtime_exit_condition()
2126 // and now so again we are done
2127 return;
2128 }
2129
2130 // Check for pending async. exception
2131 if (_pending_async_exception != NULL) {
2132 // Only overwrite an already pending exception, if it is not a threadDeath.
2133 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2134
2135 // We cannot call Exceptions::_throw(...) here because we cannot block
2136 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2137
2138 if (log_is_enabled(Info, exceptions)) {
2139 ResourceMark rm;
2140 outputStream* logstream = Log(exceptions)::info_stream();
2141 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2142 if (has_last_Java_frame()) {
2143 frame f = last_frame();
2144 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2145 }
2146 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2147 }
2148 _pending_async_exception = NULL;
2149 clear_has_async_exception();
2150 }
2151 }
2152
2153 if (check_unsafe_error &&
2154 condition == _async_unsafe_access_error && !has_pending_exception()) {
2155 condition = _no_async_condition; // done
2156 switch (thread_state()) {
2157 case _thread_in_vm: {
2158 JavaThread* THREAD = this;
2159 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2160 }
2161 case _thread_in_native: {
2162 ThreadInVMfromNative tiv(this);
2163 JavaThread* THREAD = this;
2164 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2165 }
2166 case _thread_in_Java: {
2167 ThreadInVMfromJava tiv(this);
2168 JavaThread* THREAD = this;
2169 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2170 }
2171 default:
2172 ShouldNotReachHere();
2173 }
2174 }
2175
2176 assert(condition == _no_async_condition || has_pending_exception() ||
2177 (!check_unsafe_error && condition == _async_unsafe_access_error),
2178 "must have handled the async condition, if no exception");
2179 }
2180
2181 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2182 //
2183 // Check for pending external suspend. Internal suspend requests do
2184 // not use handle_special_runtime_exit_condition().
2185 // If JNIEnv proxies are allowed, don't self-suspend if the target
2186 // thread is not the current thread. In older versions of jdbx, jdbx
2187 // threads could call into the VM with another thread's JNIEnv so we
2188 // can be here operating on behalf of a suspended thread (4432884).
2189 bool do_self_suspend = is_external_suspend_with_lock();
2190 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2191 //
2192 // Because thread is external suspended the safepoint code will count
2193 // thread as at a safepoint. This can be odd because we can be here
2194 // as _thread_in_Java which would normally transition to _thread_blocked
2195 // at a safepoint. We would like to mark the thread as _thread_blocked
2196 // before calling java_suspend_self like all other callers of it but
2197 // we must then observe proper safepoint protocol. (We can't leave
2198 // _thread_blocked with a safepoint in progress). However we can be
2199 // here as _thread_in_native_trans so we can't use a normal transition
2200 // constructor/destructor pair because they assert on that type of
2201 // transition. We could do something like:
2202 //
2203 // JavaThreadState state = thread_state();
2204 // set_thread_state(_thread_in_vm);
2205 // {
2206 // ThreadBlockInVM tbivm(this);
2207 // java_suspend_self()
2208 // }
2209 // set_thread_state(_thread_in_vm_trans);
2210 // if (safepoint) block;
2211 // set_thread_state(state);
2212 //
2213 // but that is pretty messy. Instead we just go with the way the
2214 // code has worked before and note that this is the only path to
2215 // java_suspend_self that doesn't put the thread in _thread_blocked
2216 // mode.
2217
2218 frame_anchor()->make_walkable(this);
2219 java_suspend_self();
2220
2221 // We might be here for reasons in addition to the self-suspend request
2222 // so check for other async requests.
2223 }
2224
2225 if (check_asyncs) {
2226 check_and_handle_async_exceptions();
2227 }
2228 }
2229
2230 void JavaThread::send_thread_stop(oop java_throwable) {
2231 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2232 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2233 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2234
2235 // Do not throw asynchronous exceptions against the compiler thread
2236 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2237 if (!can_call_java()) return;
2238
2239 {
2240 // Actually throw the Throwable against the target Thread - however
2241 // only if there is no thread death exception installed already.
2242 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2243 // If the topmost frame is a runtime stub, then we are calling into
2244 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2245 // must deoptimize the caller before continuing, as the compiled exception handler table
2246 // may not be valid
2247 if (has_last_Java_frame()) {
2248 frame f = last_frame();
2249 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2250 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2251 RegisterMap reg_map(this, UseBiasedLocking);
2252 frame compiled_frame = f.sender(®_map);
2253 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2254 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2255 }
2256 }
2257 }
2258
2259 // Set async. pending exception in thread.
2260 set_pending_async_exception(java_throwable);
2261
2262 if (log_is_enabled(Info, exceptions)) {
2263 ResourceMark rm;
2264 log_info(exceptions)("Pending Async. exception installed of type: %s",
2265 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2266 }
2267 // for AbortVMOnException flag
2268 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2269 }
2270 }
2271
2272
2273 // Interrupt thread so it will wake up from a potential wait()
2274 Thread::interrupt(this);
2275 }
2276
2277 // External suspension mechanism.
2278 //
2279 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2280 // to any VM_locks and it is at a transition
2281 // Self-suspension will happen on the transition out of the vm.
2282 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2283 //
2284 // Guarantees on return:
2285 // + Target thread will not execute any new bytecode (that's why we need to
2286 // force a safepoint)
2287 // + Target thread will not enter any new monitors
2288 //
2289 void JavaThread::java_suspend() {
2290 { MutexLocker mu(Threads_lock);
2291 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2292 return;
2293 }
2294 }
2295
2296 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2297 if (!is_external_suspend()) {
2298 // a racing resume has cancelled us; bail out now
2299 return;
2300 }
2301
2302 // suspend is done
2303 uint32_t debug_bits = 0;
2304 // Warning: is_ext_suspend_completed() may temporarily drop the
2305 // SR_lock to allow the thread to reach a stable thread state if
2306 // it is currently in a transient thread state.
2307 if (is_ext_suspend_completed(false /* !called_by_wait */,
2308 SuspendRetryDelay, &debug_bits)) {
2309 return;
2310 }
2311 }
2312
2313 VM_ForceSafepoint vm_suspend;
2314 VMThread::execute(&vm_suspend);
2315 }
2316
2317 // Part II of external suspension.
2318 // A JavaThread self suspends when it detects a pending external suspend
2319 // request. This is usually on transitions. It is also done in places
2320 // where continuing to the next transition would surprise the caller,
2321 // e.g., monitor entry.
2322 //
2323 // Returns the number of times that the thread self-suspended.
2324 //
2325 // Note: DO NOT call java_suspend_self() when you just want to block current
2326 // thread. java_suspend_self() is the second stage of cooperative
2327 // suspension for external suspend requests and should only be used
2328 // to complete an external suspend request.
2329 //
2330 int JavaThread::java_suspend_self() {
2331 int ret = 0;
2332
2333 // we are in the process of exiting so don't suspend
2334 if (is_exiting()) {
2335 clear_external_suspend();
2336 return ret;
2337 }
2338
2339 assert(_anchor.walkable() ||
2340 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2341 "must have walkable stack");
2342
2343 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2344
2345 assert(!this->is_ext_suspended(),
2346 "a thread trying to self-suspend should not already be suspended");
2347
2348 if (this->is_suspend_equivalent()) {
2349 // If we are self-suspending as a result of the lifting of a
2350 // suspend equivalent condition, then the suspend_equivalent
2351 // flag is not cleared until we set the ext_suspended flag so
2352 // that wait_for_ext_suspend_completion() returns consistent
2353 // results.
2354 this->clear_suspend_equivalent();
2355 }
2356
2357 // A racing resume may have cancelled us before we grabbed SR_lock
2358 // above. Or another external suspend request could be waiting for us
2359 // by the time we return from SR_lock()->wait(). The thread
2360 // that requested the suspension may already be trying to walk our
2361 // stack and if we return now, we can change the stack out from under
2362 // it. This would be a "bad thing (TM)" and cause the stack walker
2363 // to crash. We stay self-suspended until there are no more pending
2364 // external suspend requests.
2365 while (is_external_suspend()) {
2366 ret++;
2367 this->set_ext_suspended();
2368
2369 // _ext_suspended flag is cleared by java_resume()
2370 while (is_ext_suspended()) {
2371 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2372 }
2373 }
2374
2375 return ret;
2376 }
2377
2378 #ifdef ASSERT
2379 // verify the JavaThread has not yet been published in the Threads::list, and
2380 // hence doesn't need protection from concurrent access at this stage
2381 void JavaThread::verify_not_published() {
2382 if (!Threads_lock->owned_by_self()) {
2383 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2384 assert(!Threads::includes(this),
2385 "java thread shouldn't have been published yet!");
2386 } else {
2387 assert(!Threads::includes(this),
2388 "java thread shouldn't have been published yet!");
2389 }
2390 }
2391 #endif
2392
2393 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2394 // progress or when _suspend_flags is non-zero.
2395 // Current thread needs to self-suspend if there is a suspend request and/or
2396 // block if a safepoint is in progress.
2397 // Async exception ISN'T checked.
2398 // Note only the ThreadInVMfromNative transition can call this function
2399 // directly and when thread state is _thread_in_native_trans
2400 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2401 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2402
2403 JavaThread *curJT = JavaThread::current();
2404 bool do_self_suspend = thread->is_external_suspend();
2405
2406 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2407
2408 // If JNIEnv proxies are allowed, don't self-suspend if the target
2409 // thread is not the current thread. In older versions of jdbx, jdbx
2410 // threads could call into the VM with another thread's JNIEnv so we
2411 // can be here operating on behalf of a suspended thread (4432884).
2412 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2413 JavaThreadState state = thread->thread_state();
2414
2415 // We mark this thread_blocked state as a suspend-equivalent so
2416 // that a caller to is_ext_suspend_completed() won't be confused.
2417 // The suspend-equivalent state is cleared by java_suspend_self().
2418 thread->set_suspend_equivalent();
2419
2420 // If the safepoint code sees the _thread_in_native_trans state, it will
2421 // wait until the thread changes to other thread state. There is no
2422 // guarantee on how soon we can obtain the SR_lock and complete the
2423 // self-suspend request. It would be a bad idea to let safepoint wait for
2424 // too long. Temporarily change the state to _thread_blocked to
2425 // let the VM thread know that this thread is ready for GC. The problem
2426 // of changing thread state is that safepoint could happen just after
2427 // java_suspend_self() returns after being resumed, and VM thread will
2428 // see the _thread_blocked state. We must check for safepoint
2429 // after restoring the state and make sure we won't leave while a safepoint
2430 // is in progress.
2431 thread->set_thread_state(_thread_blocked);
2432 thread->java_suspend_self();
2433 thread->set_thread_state(state);
2434 // Make sure new state is seen by VM thread
2435 if (os::is_MP()) {
2436 if (UseMembar) {
2437 // Force a fence between the write above and read below
2438 OrderAccess::fence();
2439 } else {
2440 // Must use this rather than serialization page in particular on Windows
2441 InterfaceSupport::serialize_memory(thread);
2442 }
2443 }
2444 }
2445
2446 if (SafepointSynchronize::do_call_back()) {
2447 // If we are safepointing, then block the caller which may not be
2448 // the same as the target thread (see above).
2449 SafepointSynchronize::block(curJT);
2450 }
2451
2452 if (thread->is_deopt_suspend()) {
2453 thread->clear_deopt_suspend();
2454 RegisterMap map(thread, false);
2455 frame f = thread->last_frame();
2456 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2457 f = f.sender(&map);
2458 }
2459 if (f.id() == thread->must_deopt_id()) {
2460 thread->clear_must_deopt_id();
2461 f.deoptimize(thread);
2462 } else {
2463 fatal("missed deoptimization!");
2464 }
2465 }
2466 }
2467
2468 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2469 // progress or when _suspend_flags is non-zero.
2470 // Current thread needs to self-suspend if there is a suspend request and/or
2471 // block if a safepoint is in progress.
2472 // Also check for pending async exception (not including unsafe access error).
2473 // Note only the native==>VM/Java barriers can call this function and when
2474 // thread state is _thread_in_native_trans.
2475 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2476 check_safepoint_and_suspend_for_native_trans(thread);
2477
2478 if (thread->has_async_exception()) {
2479 // We are in _thread_in_native_trans state, don't handle unsafe
2480 // access error since that may block.
2481 thread->check_and_handle_async_exceptions(false);
2482 }
2483 }
2484
2485 // This is a variant of the normal
2486 // check_special_condition_for_native_trans with slightly different
2487 // semantics for use by critical native wrappers. It does all the
2488 // normal checks but also performs the transition back into
2489 // thread_in_Java state. This is required so that critical natives
2490 // can potentially block and perform a GC if they are the last thread
2491 // exiting the GCLocker.
2492 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2493 check_special_condition_for_native_trans(thread);
2494
2495 // Finish the transition
2496 thread->set_thread_state(_thread_in_Java);
2497
2498 if (thread->do_critical_native_unlock()) {
2499 ThreadInVMfromJavaNoAsyncException tiv(thread);
2500 GCLocker::unlock_critical(thread);
2501 thread->clear_critical_native_unlock();
2502 }
2503 }
2504
2505 // We need to guarantee the Threads_lock here, since resumes are not
2506 // allowed during safepoint synchronization
2507 // Can only resume from an external suspension
2508 void JavaThread::java_resume() {
2509 assert_locked_or_safepoint(Threads_lock);
2510
2511 // Sanity check: thread is gone, has started exiting or the thread
2512 // was not externally suspended.
2513 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2514 return;
2515 }
2516
2517 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2518
2519 clear_external_suspend();
2520
2521 if (is_ext_suspended()) {
2522 clear_ext_suspended();
2523 SR_lock()->notify_all();
2524 }
2525 }
2526
2527 size_t JavaThread::_stack_red_zone_size = 0;
2528 size_t JavaThread::_stack_yellow_zone_size = 0;
2529 size_t JavaThread::_stack_reserved_zone_size = 0;
2530 size_t JavaThread::_stack_shadow_zone_size = 0;
2531
2532 void JavaThread::create_stack_guard_pages() {
2533 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; }
2534 address low_addr = stack_end();
2535 size_t len = stack_guard_zone_size();
2536
2537 int must_commit = os::must_commit_stack_guard_pages();
2538 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2539
2540 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2541 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2542 return;
2543 }
2544
2545 if (os::guard_memory((char *) low_addr, len)) {
2546 _stack_guard_state = stack_guard_enabled;
2547 } else {
2548 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2549 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2550 if (os::uncommit_memory((char *) low_addr, len)) {
2551 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2552 }
2553 return;
2554 }
2555
2556 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2557 PTR_FORMAT "-" PTR_FORMAT ".",
2558 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2559 }
2560
2561 void JavaThread::remove_stack_guard_pages() {
2562 assert(Thread::current() == this, "from different thread");
2563 if (_stack_guard_state == stack_guard_unused) return;
2564 address low_addr = stack_end();
2565 size_t len = stack_guard_zone_size();
2566
2567 if (os::must_commit_stack_guard_pages()) {
2568 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2569 _stack_guard_state = stack_guard_unused;
2570 } else {
2571 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2572 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2573 return;
2574 }
2575 } else {
2576 if (_stack_guard_state == stack_guard_unused) return;
2577 if (os::unguard_memory((char *) low_addr, len)) {
2578 _stack_guard_state = stack_guard_unused;
2579 } else {
2580 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2581 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2582 return;
2583 }
2584 }
2585
2586 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2587 PTR_FORMAT "-" PTR_FORMAT ".",
2588 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2589 }
2590
2591 void JavaThread::enable_stack_reserved_zone() {
2592 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2593 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2594
2595 // The base notation is from the stack's point of view, growing downward.
2596 // We need to adjust it to work correctly with guard_memory()
2597 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2598
2599 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2600 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2601
2602 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2603 _stack_guard_state = stack_guard_enabled;
2604 } else {
2605 warning("Attempt to guard stack reserved zone failed.");
2606 }
2607 enable_register_stack_guard();
2608 }
2609
2610 void JavaThread::disable_stack_reserved_zone() {
2611 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2612 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2613
2614 // Simply return if called for a thread that does not use guard pages.
2615 if (_stack_guard_state == stack_guard_unused) return;
2616
2617 // The base notation is from the stack's point of view, growing downward.
2618 // We need to adjust it to work correctly with guard_memory()
2619 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2620
2621 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2622 _stack_guard_state = stack_guard_reserved_disabled;
2623 } else {
2624 warning("Attempt to unguard stack reserved zone failed.");
2625 }
2626 disable_register_stack_guard();
2627 }
2628
2629 void JavaThread::enable_stack_yellow_reserved_zone() {
2630 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2631 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2632
2633 // The base notation is from the stacks point of view, growing downward.
2634 // We need to adjust it to work correctly with guard_memory()
2635 address base = stack_red_zone_base();
2636
2637 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2638 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2639
2640 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2641 _stack_guard_state = stack_guard_enabled;
2642 } else {
2643 warning("Attempt to guard stack yellow zone failed.");
2644 }
2645 enable_register_stack_guard();
2646 }
2647
2648 void JavaThread::disable_stack_yellow_reserved_zone() {
2649 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2650 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2651
2652 // Simply return if called for a thread that does not use guard pages.
2653 if (_stack_guard_state == stack_guard_unused) return;
2654
2655 // The base notation is from the stacks point of view, growing downward.
2656 // We need to adjust it to work correctly with guard_memory()
2657 address base = stack_red_zone_base();
2658
2659 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2660 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2661 } else {
2662 warning("Attempt to unguard stack yellow zone failed.");
2663 }
2664 disable_register_stack_guard();
2665 }
2666
2667 void JavaThread::enable_stack_red_zone() {
2668 // The base notation is from the stacks point of view, growing downward.
2669 // We need to adjust it to work correctly with guard_memory()
2670 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2671 address base = stack_red_zone_base() - stack_red_zone_size();
2672
2673 guarantee(base < stack_base(), "Error calculating stack red zone");
2674 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2675
2676 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2677 warning("Attempt to guard stack red zone failed.");
2678 }
2679 }
2680
2681 void JavaThread::disable_stack_red_zone() {
2682 // The base notation is from the stacks point of view, growing downward.
2683 // We need to adjust it to work correctly with guard_memory()
2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2685 address base = stack_red_zone_base() - stack_red_zone_size();
2686 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2687 warning("Attempt to unguard stack red zone failed.");
2688 }
2689 }
2690
2691 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2692 // ignore is there is no stack
2693 if (!has_last_Java_frame()) return;
2694 // traverse the stack frames. Starts from top frame.
2695 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2696 frame* fr = fst.current();
2697 f(fr, fst.register_map());
2698 }
2699 }
2700
2701
2702 #ifndef PRODUCT
2703 // Deoptimization
2704 // Function for testing deoptimization
2705 void JavaThread::deoptimize() {
2706 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2707 StackFrameStream fst(this, UseBiasedLocking);
2708 bool deopt = false; // Dump stack only if a deopt actually happens.
2709 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2710 // Iterate over all frames in the thread and deoptimize
2711 for (; !fst.is_done(); fst.next()) {
2712 if (fst.current()->can_be_deoptimized()) {
2713
2714 if (only_at) {
2715 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2716 // consists of comma or carriage return separated numbers so
2717 // search for the current bci in that string.
2718 address pc = fst.current()->pc();
2719 nmethod* nm = (nmethod*) fst.current()->cb();
2720 ScopeDesc* sd = nm->scope_desc_at(pc);
2721 char buffer[8];
2722 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2723 size_t len = strlen(buffer);
2724 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2725 while (found != NULL) {
2726 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2727 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2728 // Check that the bci found is bracketed by terminators.
2729 break;
2730 }
2731 found = strstr(found + 1, buffer);
2732 }
2733 if (!found) {
2734 continue;
2735 }
2736 }
2737
2738 if (DebugDeoptimization && !deopt) {
2739 deopt = true; // One-time only print before deopt
2740 tty->print_cr("[BEFORE Deoptimization]");
2741 trace_frames();
2742 trace_stack();
2743 }
2744 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2745 }
2746 }
2747
2748 if (DebugDeoptimization && deopt) {
2749 tty->print_cr("[AFTER Deoptimization]");
2750 trace_frames();
2751 }
2752 }
2753
2754
2755 // Make zombies
2756 void JavaThread::make_zombies() {
2757 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2758 if (fst.current()->can_be_deoptimized()) {
2759 // it is a Java nmethod
2760 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2761 nm->make_not_entrant();
2762 }
2763 }
2764 }
2765 #endif // PRODUCT
2766
2767
2768 void JavaThread::deoptimized_wrt_marked_nmethods() {
2769 if (!has_last_Java_frame()) return;
2770 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2771 StackFrameStream fst(this, UseBiasedLocking);
2772 for (; !fst.is_done(); fst.next()) {
2773 if (fst.current()->should_be_deoptimized()) {
2774 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2775 }
2776 }
2777 }
2778
2779
2780 // If the caller is a NamedThread, then remember, in the current scope,
2781 // the given JavaThread in its _processed_thread field.
2782 class RememberProcessedThread: public StackObj {
2783 NamedThread* _cur_thr;
2784 public:
2785 RememberProcessedThread(JavaThread* jthr) {
2786 Thread* thread = Thread::current();
2787 if (thread->is_Named_thread()) {
2788 _cur_thr = (NamedThread *)thread;
2789 _cur_thr->set_processed_thread(jthr);
2790 } else {
2791 _cur_thr = NULL;
2792 }
2793 }
2794
2795 ~RememberProcessedThread() {
2796 if (_cur_thr) {
2797 _cur_thr->set_processed_thread(NULL);
2798 }
2799 }
2800 };
2801
2802 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2803 // Verify that the deferred card marks have been flushed.
2804 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2805
2806 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2807 // since there may be more than one thread using each ThreadProfiler.
2808
2809 // Traverse the GCHandles
2810 Thread::oops_do(f, cf);
2811
2812 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2813
2814 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2815 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2816
2817 if (has_last_Java_frame()) {
2818 // Record JavaThread to GC thread
2819 RememberProcessedThread rpt(this);
2820
2821 // Traverse the privileged stack
2822 if (_privileged_stack_top != NULL) {
2823 _privileged_stack_top->oops_do(f);
2824 }
2825
2826 // traverse the registered growable array
2827 if (_array_for_gc != NULL) {
2828 for (int index = 0; index < _array_for_gc->length(); index++) {
2829 f->do_oop(_array_for_gc->adr_at(index));
2830 }
2831 }
2832
2833 // Traverse the monitor chunks
2834 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2835 chunk->oops_do(f);
2836 }
2837
2838 // Traverse the execution stack
2839 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2840 fst.current()->oops_do(f, cf, fst.register_map());
2841 }
2842 }
2843
2844 // callee_target is never live across a gc point so NULL it here should
2845 // it still contain a methdOop.
2846
2847 set_callee_target(NULL);
2848
2849 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2850 // If we have deferred set_locals there might be oops waiting to be
2851 // written
2852 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2853 if (list != NULL) {
2854 for (int i = 0; i < list->length(); i++) {
2855 list->at(i)->oops_do(f);
2856 }
2857 }
2858
2859 // Traverse instance variables at the end since the GC may be moving things
2860 // around using this function
2861 f->do_oop((oop*) &_threadObj);
2862 f->do_oop((oop*) &_vm_result);
2863 f->do_oop((oop*) &_exception_oop);
2864 f->do_oop((oop*) &_pending_async_exception);
2865
2866 if (jvmti_thread_state() != NULL) {
2867 jvmti_thread_state()->oops_do(f);
2868 }
2869 }
2870
2871 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2872 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2873 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2874
2875 if (has_last_Java_frame()) {
2876 // Traverse the execution stack
2877 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2878 fst.current()->nmethods_do(cf);
2879 }
2880 }
2881 }
2882
2883 void JavaThread::metadata_do(void f(Metadata*)) {
2884 if (has_last_Java_frame()) {
2885 // Traverse the execution stack to call f() on the methods in the stack
2886 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2887 fst.current()->metadata_do(f);
2888 }
2889 } else if (is_Compiler_thread()) {
2890 // need to walk ciMetadata in current compile tasks to keep alive.
2891 CompilerThread* ct = (CompilerThread*)this;
2892 if (ct->env() != NULL) {
2893 ct->env()->metadata_do(f);
2894 }
2895 if (ct->task() != NULL) {
2896 ct->task()->metadata_do(f);
2897 }
2898 }
2899 }
2900
2901 // Printing
2902 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2903 switch (_thread_state) {
2904 case _thread_uninitialized: return "_thread_uninitialized";
2905 case _thread_new: return "_thread_new";
2906 case _thread_new_trans: return "_thread_new_trans";
2907 case _thread_in_native: return "_thread_in_native";
2908 case _thread_in_native_trans: return "_thread_in_native_trans";
2909 case _thread_in_vm: return "_thread_in_vm";
2910 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2911 case _thread_in_Java: return "_thread_in_Java";
2912 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2913 case _thread_blocked: return "_thread_blocked";
2914 case _thread_blocked_trans: return "_thread_blocked_trans";
2915 default: return "unknown thread state";
2916 }
2917 }
2918
2919 #ifndef PRODUCT
2920 void JavaThread::print_thread_state_on(outputStream *st) const {
2921 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2922 };
2923 void JavaThread::print_thread_state() const {
2924 print_thread_state_on(tty);
2925 }
2926 #endif // PRODUCT
2927
2928 // Called by Threads::print() for VM_PrintThreads operation
2929 void JavaThread::print_on(outputStream *st) const {
2930 st->print_raw("\"");
2931 st->print_raw(get_thread_name());
2932 st->print_raw("\" ");
2933 oop thread_oop = threadObj();
2934 if (thread_oop != NULL) {
2935 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2936 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2937 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2938 }
2939 Thread::print_on(st);
2940 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2941 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2942 if (thread_oop != NULL) {
2943 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2944 }
2945 #ifndef PRODUCT
2946 print_thread_state_on(st);
2947 _safepoint_state->print_on(st);
2948 #endif // PRODUCT
2949 if (is_Compiler_thread()) {
2950 CompilerThread* ct = (CompilerThread*)this;
2951 if (ct->task() != NULL) {
2952 st->print(" Compiling: ");
2953 ct->task()->print(st, NULL, true, false);
2954 } else {
2955 st->print(" No compile task");
2956 }
2957 st->cr();
2958 }
2959 }
2960
2961 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2962 st->print("%s", get_thread_name_string(buf, buflen));
2963 }
2964
2965 // Called by fatal error handler. The difference between this and
2966 // JavaThread::print() is that we can't grab lock or allocate memory.
2967 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2968 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2969 oop thread_obj = threadObj();
2970 if (thread_obj != NULL) {
2971 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2972 }
2973 st->print(" [");
2974 st->print("%s", _get_thread_state_name(_thread_state));
2975 if (osthread()) {
2976 st->print(", id=%d", osthread()->thread_id());
2977 }
2978 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2979 p2i(stack_end()), p2i(stack_base()));
2980 st->print("]");
2981 return;
2982 }
2983
2984 // Verification
2985
2986 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2987
2988 void JavaThread::verify() {
2989 // Verify oops in the thread.
2990 oops_do(&VerifyOopClosure::verify_oop, NULL);
2991
2992 // Verify the stack frames.
2993 frames_do(frame_verify);
2994 }
2995
2996 // CR 6300358 (sub-CR 2137150)
2997 // Most callers of this method assume that it can't return NULL but a
2998 // thread may not have a name whilst it is in the process of attaching to
2999 // the VM - see CR 6412693, and there are places where a JavaThread can be
3000 // seen prior to having it's threadObj set (eg JNI attaching threads and
3001 // if vm exit occurs during initialization). These cases can all be accounted
3002 // for such that this method never returns NULL.
3003 const char* JavaThread::get_thread_name() const {
3004 #ifdef ASSERT
3005 // early safepoints can hit while current thread does not yet have TLS
3006 if (!SafepointSynchronize::is_at_safepoint()) {
3007 Thread *cur = Thread::current();
3008 if (!(cur->is_Java_thread() && cur == this)) {
3009 // Current JavaThreads are allowed to get their own name without
3010 // the Threads_lock.
3011 assert_locked_or_safepoint(Threads_lock);
3012 }
3013 }
3014 #endif // ASSERT
3015 return get_thread_name_string();
3016 }
3017
3018 // Returns a non-NULL representation of this thread's name, or a suitable
3019 // descriptive string if there is no set name
3020 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3021 const char* name_str;
3022 oop thread_obj = threadObj();
3023 if (thread_obj != NULL) {
3024 oop name = java_lang_Thread::name(thread_obj);
3025 if (name != NULL) {
3026 if (buf == NULL) {
3027 name_str = java_lang_String::as_utf8_string(name);
3028 } else {
3029 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3030 }
3031 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3032 name_str = "<no-name - thread is attaching>";
3033 } else {
3034 name_str = Thread::name();
3035 }
3036 } else {
3037 name_str = Thread::name();
3038 }
3039 assert(name_str != NULL, "unexpected NULL thread name");
3040 return name_str;
3041 }
3042
3043
3044 const char* JavaThread::get_threadgroup_name() const {
3045 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3046 oop thread_obj = threadObj();
3047 if (thread_obj != NULL) {
3048 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3049 if (thread_group != NULL) {
3050 // ThreadGroup.name can be null
3051 return java_lang_ThreadGroup::name(thread_group);
3052 }
3053 }
3054 return NULL;
3055 }
3056
3057 const char* JavaThread::get_parent_name() const {
3058 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3059 oop thread_obj = threadObj();
3060 if (thread_obj != NULL) {
3061 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3062 if (thread_group != NULL) {
3063 oop parent = java_lang_ThreadGroup::parent(thread_group);
3064 if (parent != NULL) {
3065 // ThreadGroup.name can be null
3066 return java_lang_ThreadGroup::name(parent);
3067 }
3068 }
3069 }
3070 return NULL;
3071 }
3072
3073 ThreadPriority JavaThread::java_priority() const {
3074 oop thr_oop = threadObj();
3075 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3076 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3077 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3078 return priority;
3079 }
3080
3081 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3082
3083 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3084 // Link Java Thread object <-> C++ Thread
3085
3086 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3087 // and put it into a new Handle. The Handle "thread_oop" can then
3088 // be used to pass the C++ thread object to other methods.
3089
3090 // Set the Java level thread object (jthread) field of the
3091 // new thread (a JavaThread *) to C++ thread object using the
3092 // "thread_oop" handle.
3093
3094 // Set the thread field (a JavaThread *) of the
3095 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3096
3097 Handle thread_oop(Thread::current(),
3098 JNIHandles::resolve_non_null(jni_thread));
3099 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3100 "must be initialized");
3101 set_threadObj(thread_oop());
3102 java_lang_Thread::set_thread(thread_oop(), this);
3103
3104 if (prio == NoPriority) {
3105 prio = java_lang_Thread::priority(thread_oop());
3106 assert(prio != NoPriority, "A valid priority should be present");
3107 }
3108
3109 // Push the Java priority down to the native thread; needs Threads_lock
3110 Thread::set_priority(this, prio);
3111
3112 prepare_ext();
3113
3114 // Add the new thread to the Threads list and set it in motion.
3115 // We must have threads lock in order to call Threads::add.
3116 // It is crucial that we do not block before the thread is
3117 // added to the Threads list for if a GC happens, then the java_thread oop
3118 // will not be visited by GC.
3119 Threads::add(this);
3120 }
3121
3122 oop JavaThread::current_park_blocker() {
3123 // Support for JSR-166 locks
3124 oop thread_oop = threadObj();
3125 if (thread_oop != NULL &&
3126 JDK_Version::current().supports_thread_park_blocker()) {
3127 return java_lang_Thread::park_blocker(thread_oop);
3128 }
3129 return NULL;
3130 }
3131
3132
3133 void JavaThread::print_stack_on(outputStream* st) {
3134 if (!has_last_Java_frame()) return;
3135 ResourceMark rm;
3136 HandleMark hm;
3137
3138 RegisterMap reg_map(this);
3139 vframe* start_vf = last_java_vframe(®_map);
3140 int count = 0;
3141 for (vframe* f = start_vf; f; f = f->sender()) {
3142 if (f->is_java_frame()) {
3143 javaVFrame* jvf = javaVFrame::cast(f);
3144 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3145
3146 // Print out lock information
3147 if (JavaMonitorsInStackTrace) {
3148 jvf->print_lock_info_on(st, count);
3149 }
3150 } else {
3151 // Ignore non-Java frames
3152 }
3153
3154 // Bail-out case for too deep stacks
3155 count++;
3156 if (MaxJavaStackTraceDepth == count) return;
3157 }
3158 }
3159
3160
3161 // JVMTI PopFrame support
3162 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3163 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3164 if (in_bytes(size_in_bytes) != 0) {
3165 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3166 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3167 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3168 }
3169 }
3170
3171 void* JavaThread::popframe_preserved_args() {
3172 return _popframe_preserved_args;
3173 }
3174
3175 ByteSize JavaThread::popframe_preserved_args_size() {
3176 return in_ByteSize(_popframe_preserved_args_size);
3177 }
3178
3179 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3180 int sz = in_bytes(popframe_preserved_args_size());
3181 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3182 return in_WordSize(sz / wordSize);
3183 }
3184
3185 void JavaThread::popframe_free_preserved_args() {
3186 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3187 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3188 _popframe_preserved_args = NULL;
3189 _popframe_preserved_args_size = 0;
3190 }
3191
3192 #ifndef PRODUCT
3193
3194 void JavaThread::trace_frames() {
3195 tty->print_cr("[Describe stack]");
3196 int frame_no = 1;
3197 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3198 tty->print(" %d. ", frame_no++);
3199 fst.current()->print_value_on(tty, this);
3200 tty->cr();
3201 }
3202 }
3203
3204 class PrintAndVerifyOopClosure: public OopClosure {
3205 protected:
3206 template <class T> inline void do_oop_work(T* p) {
3207 oop obj = oopDesc::load_decode_heap_oop(p);
3208 if (obj == NULL) return;
3209 tty->print(INTPTR_FORMAT ": ", p2i(p));
3210 if (obj->is_oop_or_null()) {
3211 if (obj->is_objArray()) {
3212 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3213 } else {
3214 obj->print();
3215 }
3216 } else {
3217 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3218 }
3219 tty->cr();
3220 }
3221 public:
3222 virtual void do_oop(oop* p) { do_oop_work(p); }
3223 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3224 };
3225
3226
3227 static void oops_print(frame* f, const RegisterMap *map) {
3228 PrintAndVerifyOopClosure print;
3229 f->print_value();
3230 f->oops_do(&print, NULL, (RegisterMap*)map);
3231 }
3232
3233 // Print our all the locations that contain oops and whether they are
3234 // valid or not. This useful when trying to find the oldest frame
3235 // where an oop has gone bad since the frame walk is from youngest to
3236 // oldest.
3237 void JavaThread::trace_oops() {
3238 tty->print_cr("[Trace oops]");
3239 frames_do(oops_print);
3240 }
3241
3242
3243 #ifdef ASSERT
3244 // Print or validate the layout of stack frames
3245 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3246 ResourceMark rm;
3247 PRESERVE_EXCEPTION_MARK;
3248 FrameValues values;
3249 int frame_no = 0;
3250 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3251 fst.current()->describe(values, ++frame_no);
3252 if (depth == frame_no) break;
3253 }
3254 if (validate_only) {
3255 values.validate();
3256 } else {
3257 tty->print_cr("[Describe stack layout]");
3258 values.print(this);
3259 }
3260 }
3261 #endif
3262
3263 void JavaThread::trace_stack_from(vframe* start_vf) {
3264 ResourceMark rm;
3265 int vframe_no = 1;
3266 for (vframe* f = start_vf; f; f = f->sender()) {
3267 if (f->is_java_frame()) {
3268 javaVFrame::cast(f)->print_activation(vframe_no++);
3269 } else {
3270 f->print();
3271 }
3272 if (vframe_no > StackPrintLimit) {
3273 tty->print_cr("...<more frames>...");
3274 return;
3275 }
3276 }
3277 }
3278
3279
3280 void JavaThread::trace_stack() {
3281 if (!has_last_Java_frame()) return;
3282 ResourceMark rm;
3283 HandleMark hm;
3284 RegisterMap reg_map(this);
3285 trace_stack_from(last_java_vframe(®_map));
3286 }
3287
3288
3289 #endif // PRODUCT
3290
3291
3292 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3293 assert(reg_map != NULL, "a map must be given");
3294 frame f = last_frame();
3295 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3296 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3297 }
3298 return NULL;
3299 }
3300
3301
3302 Klass* JavaThread::security_get_caller_class(int depth) {
3303 vframeStream vfst(this);
3304 vfst.security_get_caller_frame(depth);
3305 if (!vfst.at_end()) {
3306 return vfst.method()->method_holder();
3307 }
3308 return NULL;
3309 }
3310
3311 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3312 assert(thread->is_Compiler_thread(), "must be compiler thread");
3313 CompileBroker::compiler_thread_loop();
3314 }
3315
3316 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3317 NMethodSweeper::sweeper_loop();
3318 }
3319
3320 // Create a CompilerThread
3321 CompilerThread::CompilerThread(CompileQueue* queue,
3322 CompilerCounters* counters)
3323 : JavaThread(&compiler_thread_entry) {
3324 _env = NULL;
3325 _log = NULL;
3326 _task = NULL;
3327 _queue = queue;
3328 _counters = counters;
3329 _buffer_blob = NULL;
3330 _compiler = NULL;
3331
3332 #ifndef PRODUCT
3333 _ideal_graph_printer = NULL;
3334 #endif
3335 }
3336
3337 bool CompilerThread::can_call_java() const {
3338 return _compiler != NULL && _compiler->is_jvmci();
3339 }
3340
3341 // Create sweeper thread
3342 CodeCacheSweeperThread::CodeCacheSweeperThread()
3343 : JavaThread(&sweeper_thread_entry) {
3344 _scanned_compiled_method = NULL;
3345 }
3346
3347 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3348 JavaThread::oops_do(f, cf);
3349 if (_scanned_compiled_method != NULL && cf != NULL) {
3350 // Safepoints can occur when the sweeper is scanning an nmethod so
3351 // process it here to make sure it isn't unloaded in the middle of
3352 // a scan.
3353 cf->do_code_blob(_scanned_compiled_method);
3354 }
3355 }
3356
3357 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3358 JavaThread::nmethods_do(cf);
3359 if (_scanned_compiled_method != NULL && cf != NULL) {
3360 // Safepoints can occur when the sweeper is scanning an nmethod so
3361 // process it here to make sure it isn't unloaded in the middle of
3362 // a scan.
3363 cf->do_code_blob(_scanned_compiled_method);
3364 }
3365 }
3366
3367
3368 // ======= Threads ========
3369
3370 // The Threads class links together all active threads, and provides
3371 // operations over all threads. It is protected by its own Mutex
3372 // lock, which is also used in other contexts to protect thread
3373 // operations from having the thread being operated on from exiting
3374 // and going away unexpectedly (e.g., safepoint synchronization)
3375
3376 JavaThread* Threads::_thread_list = NULL;
3377 int Threads::_number_of_threads = 0;
3378 int Threads::_number_of_non_daemon_threads = 0;
3379 int Threads::_return_code = 0;
3380 int Threads::_thread_claim_parity = 0;
3381 size_t JavaThread::_stack_size_at_create = 0;
3382 #ifdef ASSERT
3383 bool Threads::_vm_complete = false;
3384 #endif
3385
3386 // All JavaThreads
3387 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3388
3389 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3390 void Threads::threads_do(ThreadClosure* tc) {
3391 assert_locked_or_safepoint(Threads_lock);
3392 // ALL_JAVA_THREADS iterates through all JavaThreads
3393 ALL_JAVA_THREADS(p) {
3394 tc->do_thread(p);
3395 }
3396 // Someday we could have a table or list of all non-JavaThreads.
3397 // For now, just manually iterate through them.
3398 tc->do_thread(VMThread::vm_thread());
3399 Universe::heap()->gc_threads_do(tc);
3400 WatcherThread *wt = WatcherThread::watcher_thread();
3401 // Strictly speaking, the following NULL check isn't sufficient to make sure
3402 // the data for WatcherThread is still valid upon being examined. However,
3403 // considering that WatchThread terminates when the VM is on the way to
3404 // exit at safepoint, the chance of the above is extremely small. The right
3405 // way to prevent termination of WatcherThread would be to acquire
3406 // Terminator_lock, but we can't do that without violating the lock rank
3407 // checking in some cases.
3408 if (wt != NULL) {
3409 tc->do_thread(wt);
3410 }
3411
3412 // If CompilerThreads ever become non-JavaThreads, add them here
3413 }
3414
3415 void Threads::parallel_java_threads_do(ThreadClosure* tc) {
3416 int cp = Threads::thread_claim_parity();
3417 ALL_JAVA_THREADS(p) {
3418 if (p->claim_oops_do(true, cp)) {
3419 tc->do_thread(p);
3420 }
3421 }
3422 }
3423
3424 // The system initialization in the library has three phases.
3425 //
3426 // Phase 1: java.lang.System class initialization
3427 // java.lang.System is a primordial class loaded and initialized
3428 // by the VM early during startup. java.lang.System.<clinit>
3429 // only does registerNatives and keeps the rest of the class
3430 // initialization work later until thread initialization completes.
3431 //
3432 // System.initPhase1 initializes the system properties, the static
3433 // fields in, out, and err. Set up java signal handlers, OS-specific
3434 // system settings, and thread group of the main thread.
3435 static void call_initPhase1(TRAPS) {
3436 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3437 instanceKlassHandle klass (THREAD, k);
3438
3439 JavaValue result(T_VOID);
3440 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3441 vmSymbols::void_method_signature(), CHECK);
3442 }
3443
3444 // Phase 2. Module system initialization
3445 // This will initialize the module system. Only java.base classes
3446 // can be loaded until phase 2 completes.
3447 //
3448 // Call System.initPhase2 after the compiler initialization and jsr292
3449 // classes get initialized because module initialization runs a lot of java
3450 // code, that for performance reasons, should be compiled. Also, this will
3451 // enable the startup code to use lambda and other language features in this
3452 // phase and onward.
3453 //
3454 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3455 static void call_initPhase2(TRAPS) {
3456 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
3457
3458 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3459 instanceKlassHandle klass (THREAD, k);
3460
3461 JavaValue result(T_INT);
3462 JavaCallArguments args;
3463 args.push_int(DisplayVMOutputToStderr);
3464 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3465 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3466 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3467 if (result.get_jint() != JNI_OK) {
3468 vm_exit_during_initialization(); // no message or exception
3469 }
3470
3471 universe_post_module_init();
3472 }
3473
3474 // Phase 3. final setup - set security manager, system class loader and TCCL
3475 //
3476 // This will instantiate and set the security manager, set the system class
3477 // loader as well as the thread context class loader. The security manager
3478 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3479 // other modules or the application's classpath.
3480 static void call_initPhase3(TRAPS) {
3481 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3482 instanceKlassHandle klass (THREAD, k);
3483
3484 JavaValue result(T_VOID);
3485 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3486 vmSymbols::void_method_signature(), CHECK);
3487 }
3488
3489 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3490 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3491
3492 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3493 create_vm_init_libraries();
3494 }
3495
3496 initialize_class(vmSymbols::java_lang_String(), CHECK);
3497
3498 // Inject CompactStrings value after the static initializers for String ran.
3499 java_lang_String::set_compact_strings(CompactStrings);
3500
3501 // Initialize java_lang.System (needed before creating the thread)
3502 initialize_class(vmSymbols::java_lang_System(), CHECK);
3503 // The VM creates & returns objects of this class. Make sure it's initialized.
3504 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3505 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3506 Handle thread_group = create_initial_thread_group(CHECK);
3507 Universe::set_main_thread_group(thread_group());
3508 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3509 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3510 main_thread->set_threadObj(thread_object);
3511 // Set thread status to running since main thread has
3512 // been started and running.
3513 java_lang_Thread::set_thread_status(thread_object,
3514 java_lang_Thread::RUNNABLE);
3515
3516 // The VM creates objects of this class.
3517 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3518
3519 // The VM preresolves methods to these classes. Make sure that they get initialized
3520 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3521 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3522
3523 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3524 call_initPhase1(CHECK);
3525
3526 // get the Java runtime name after java.lang.System is initialized
3527 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3528 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3529
3530 // an instance of OutOfMemory exception has been allocated earlier
3531 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3532 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3533 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3534 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3535 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3536 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3537 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3538 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3539 }
3540
3541 void Threads::initialize_jsr292_core_classes(TRAPS) {
3542 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3543
3544 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3545 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3546 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3547 }
3548
3549 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3550 extern void JDK_Version_init();
3551
3552 // Preinitialize version info.
3553 VM_Version::early_initialize();
3554
3555 // Check version
3556 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3557
3558 // Initialize library-based TLS
3559 ThreadLocalStorage::init();
3560
3561 // Initialize the output stream module
3562 ostream_init();
3563
3564 // Process java launcher properties.
3565 Arguments::process_sun_java_launcher_properties(args);
3566
3567 // Initialize the os module
3568 os::init();
3569
3570 // Record VM creation timing statistics
3571 TraceVmCreationTime create_vm_timer;
3572 create_vm_timer.start();
3573
3574 // Initialize system properties.
3575 Arguments::init_system_properties();
3576
3577 // So that JDK version can be used as a discriminator when parsing arguments
3578 JDK_Version_init();
3579
3580 // Update/Initialize System properties after JDK version number is known
3581 Arguments::init_version_specific_system_properties();
3582
3583 // Make sure to initialize log configuration *before* parsing arguments
3584 LogConfiguration::initialize(create_vm_timer.begin_time());
3585
3586 // Parse arguments
3587 jint parse_result = Arguments::parse(args);
3588 if (parse_result != JNI_OK) return parse_result;
3589
3590 os::init_before_ergo();
3591
3592 jint ergo_result = Arguments::apply_ergo();
3593 if (ergo_result != JNI_OK) return ergo_result;
3594
3595 // Final check of all ranges after ergonomics which may change values.
3596 if (!CommandLineFlagRangeList::check_ranges()) {
3597 return JNI_EINVAL;
3598 }
3599
3600 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3601 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3602 if (!constraint_result) {
3603 return JNI_EINVAL;
3604 }
3605
3606 CommandLineFlagWriteableList::mark_startup();
3607
3608 if (PauseAtStartup) {
3609 os::pause();
3610 }
3611
3612 HOTSPOT_VM_INIT_BEGIN();
3613
3614 // Timing (must come after argument parsing)
3615 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3616
3617 // Initialize the os module after parsing the args
3618 jint os_init_2_result = os::init_2();
3619 if (os_init_2_result != JNI_OK) return os_init_2_result;
3620
3621 jint adjust_after_os_result = Arguments::adjust_after_os();
3622 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3623
3624 // Initialize output stream logging
3625 ostream_init_log();
3626
3627 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3628 // Must be before create_vm_init_agents()
3629 if (Arguments::init_libraries_at_startup()) {
3630 convert_vm_init_libraries_to_agents();
3631 }
3632
3633 // Launch -agentlib/-agentpath and converted -Xrun agents
3634 if (Arguments::init_agents_at_startup()) {
3635 create_vm_init_agents();
3636 }
3637
3638 // Initialize Threads state
3639 _thread_list = NULL;
3640 _number_of_threads = 0;
3641 _number_of_non_daemon_threads = 0;
3642
3643 // Initialize global data structures and create system classes in heap
3644 vm_init_globals();
3645
3646 #if INCLUDE_JVMCI
3647 if (JVMCICounterSize > 0) {
3648 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3649 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3650 } else {
3651 JavaThread::_jvmci_old_thread_counters = NULL;
3652 }
3653 #endif // INCLUDE_JVMCI
3654
3655 // Attach the main thread to this os thread
3656 JavaThread* main_thread = new JavaThread();
3657 main_thread->set_thread_state(_thread_in_vm);
3658 main_thread->initialize_thread_current();
3659 // must do this before set_active_handles
3660 main_thread->record_stack_base_and_size();
3661 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3662
3663 if (!main_thread->set_as_starting_thread()) {
3664 vm_shutdown_during_initialization(
3665 "Failed necessary internal allocation. Out of swap space");
3666 delete main_thread;
3667 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3668 return JNI_ENOMEM;
3669 }
3670
3671 // Enable guard page *after* os::create_main_thread(), otherwise it would
3672 // crash Linux VM, see notes in os_linux.cpp.
3673 main_thread->create_stack_guard_pages();
3674
3675 // Initialize Java-Level synchronization subsystem
3676 ObjectMonitor::Initialize();
3677
3678 // Initialize global modules
3679 jint status = init_globals();
3680 if (status != JNI_OK) {
3681 delete main_thread;
3682 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3683 return status;
3684 }
3685
3686 if (TRACE_INITIALIZE() != JNI_OK) {
3687 vm_exit_during_initialization("Failed to initialize tracing backend");
3688 }
3689
3690 // Should be done after the heap is fully created
3691 main_thread->cache_global_variables();
3692
3693 HandleMark hm;
3694
3695 { MutexLocker mu(Threads_lock);
3696 Threads::add(main_thread);
3697 }
3698
3699 // Any JVMTI raw monitors entered in onload will transition into
3700 // real raw monitor. VM is setup enough here for raw monitor enter.
3701 JvmtiExport::transition_pending_onload_raw_monitors();
3702
3703 // Create the VMThread
3704 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3705
3706 VMThread::create();
3707 Thread* vmthread = VMThread::vm_thread();
3708
3709 if (!os::create_thread(vmthread, os::vm_thread)) {
3710 vm_exit_during_initialization("Cannot create VM thread. "
3711 "Out of system resources.");
3712 }
3713
3714 // Wait for the VM thread to become ready, and VMThread::run to initialize
3715 // Monitors can have spurious returns, must always check another state flag
3716 {
3717 MutexLocker ml(Notify_lock);
3718 os::start_thread(vmthread);
3719 while (vmthread->active_handles() == NULL) {
3720 Notify_lock->wait();
3721 }
3722 }
3723 }
3724
3725 assert(Universe::is_fully_initialized(), "not initialized");
3726 if (VerifyDuringStartup) {
3727 // Make sure we're starting with a clean slate.
3728 VM_Verify verify_op;
3729 VMThread::execute(&verify_op);
3730 }
3731
3732 Thread* THREAD = Thread::current();
3733
3734 // At this point, the Universe is initialized, but we have not executed
3735 // any byte code. Now is a good time (the only time) to dump out the
3736 // internal state of the JVM for sharing.
3737 if (DumpSharedSpaces) {
3738 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3739 ShouldNotReachHere();
3740 }
3741
3742 // Always call even when there are not JVMTI environments yet, since environments
3743 // may be attached late and JVMTI must track phases of VM execution
3744 JvmtiExport::enter_early_start_phase();
3745
3746 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3747 JvmtiExport::post_early_vm_start();
3748
3749 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3750
3751 // We need this for ClassDataSharing - the initial vm.info property is set
3752 // with the default value of CDS "sharing" which may be reset through
3753 // command line options.
3754 reset_vm_info_property(CHECK_JNI_ERR);
3755
3756 quicken_jni_functions();
3757
3758 // No more stub generation allowed after that point.
3759 StubCodeDesc::freeze();
3760
3761 // Set flag that basic initialization has completed. Used by exceptions and various
3762 // debug stuff, that does not work until all basic classes have been initialized.
3763 set_init_completed();
3764
3765 LogConfiguration::post_initialize();
3766 Metaspace::post_initialize();
3767
3768 HOTSPOT_VM_INIT_END();
3769
3770 // record VM initialization completion time
3771 #if INCLUDE_MANAGEMENT
3772 Management::record_vm_init_completed();
3773 #endif // INCLUDE_MANAGEMENT
3774
3775 // Signal Dispatcher needs to be started before VMInit event is posted
3776 os::signal_init();
3777
3778 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3779 if (!DisableAttachMechanism) {
3780 AttachListener::vm_start();
3781 if (StartAttachListener || AttachListener::init_at_startup()) {
3782 AttachListener::init();
3783 }
3784 }
3785
3786 // Launch -Xrun agents
3787 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3788 // back-end can launch with -Xdebug -Xrunjdwp.
3789 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3790 create_vm_init_libraries();
3791 }
3792
3793 if (CleanChunkPoolAsync) {
3794 Chunk::start_chunk_pool_cleaner_task();
3795 }
3796
3797 // initialize compiler(s)
3798 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI
3799 CompileBroker::compilation_init(CHECK_JNI_ERR);
3800 #endif
3801
3802 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3803 // It is done after compilers are initialized, because otherwise compilations of
3804 // signature polymorphic MH intrinsics can be missed
3805 // (see SystemDictionary::find_method_handle_intrinsic).
3806 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3807
3808 // This will initialize the module system. Only java.base classes can be
3809 // loaded until phase 2 completes
3810 call_initPhase2(CHECK_JNI_ERR);
3811
3812 // Always call even when there are not JVMTI environments yet, since environments
3813 // may be attached late and JVMTI must track phases of VM execution
3814 JvmtiExport::enter_start_phase();
3815
3816 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3817 JvmtiExport::post_vm_start();
3818
3819 // Final system initialization including security manager and system class loader
3820 call_initPhase3(CHECK_JNI_ERR);
3821
3822 // cache the system class loader
3823 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
3824
3825 #if INCLUDE_JVMCI
3826 if (EnableJVMCI) {
3827 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
3828 // The JVMCI Java initialization code will read this flag and
3829 // do the printing if it's set.
3830 bool init = JVMCIPrintProperties;
3831
3832 if (!init) {
3833 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3834 // compilations via JVMCI will not actually block until JVMCI is initialized.
3835 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3836 }
3837
3838 if (init) {
3839 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3840 }
3841 }
3842 #endif
3843
3844 // Always call even when there are not JVMTI environments yet, since environments
3845 // may be attached late and JVMTI must track phases of VM execution
3846 JvmtiExport::enter_live_phase();
3847
3848 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3849 JvmtiExport::post_vm_initialized();
3850
3851 if (TRACE_START() != JNI_OK) {
3852 vm_exit_during_initialization("Failed to start tracing backend.");
3853 }
3854
3855 #if INCLUDE_MANAGEMENT
3856 Management::initialize(THREAD);
3857
3858 if (HAS_PENDING_EXCEPTION) {
3859 // management agent fails to start possibly due to
3860 // configuration problem and is responsible for printing
3861 // stack trace if appropriate. Simply exit VM.
3862 vm_exit(1);
3863 }
3864 #endif // INCLUDE_MANAGEMENT
3865
3866 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3867 if (MemProfiling) MemProfiler::engage();
3868 StatSampler::engage();
3869 if (CheckJNICalls) JniPeriodicChecker::engage();
3870
3871 BiasedLocking::init();
3872
3873 #if INCLUDE_RTM_OPT
3874 RTMLockingCounters::init();
3875 #endif
3876
3877 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3878 call_postVMInitHook(THREAD);
3879 // The Java side of PostVMInitHook.run must deal with all
3880 // exceptions and provide means of diagnosis.
3881 if (HAS_PENDING_EXCEPTION) {
3882 CLEAR_PENDING_EXCEPTION;
3883 }
3884 }
3885
3886 {
3887 MutexLocker ml(PeriodicTask_lock);
3888 // Make sure the WatcherThread can be started by WatcherThread::start()
3889 // or by dynamic enrollment.
3890 WatcherThread::make_startable();
3891 // Start up the WatcherThread if there are any periodic tasks
3892 // NOTE: All PeriodicTasks should be registered by now. If they
3893 // aren't, late joiners might appear to start slowly (we might
3894 // take a while to process their first tick).
3895 if (PeriodicTask::num_tasks() > 0) {
3896 WatcherThread::start();
3897 }
3898 }
3899
3900 create_vm_timer.end();
3901 #ifdef ASSERT
3902 _vm_complete = true;
3903 #endif
3904 return JNI_OK;
3905 }
3906
3907 // type for the Agent_OnLoad and JVM_OnLoad entry points
3908 extern "C" {
3909 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3910 }
3911 // Find a command line agent library and return its entry point for
3912 // -agentlib: -agentpath: -Xrun
3913 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3914 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3915 const char *on_load_symbols[],
3916 size_t num_symbol_entries) {
3917 OnLoadEntry_t on_load_entry = NULL;
3918 void *library = NULL;
3919
3920 if (!agent->valid()) {
3921 char buffer[JVM_MAXPATHLEN];
3922 char ebuf[1024] = "";
3923 const char *name = agent->name();
3924 const char *msg = "Could not find agent library ";
3925
3926 // First check to see if agent is statically linked into executable
3927 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3928 library = agent->os_lib();
3929 } else if (agent->is_absolute_path()) {
3930 library = os::dll_load(name, ebuf, sizeof ebuf);
3931 if (library == NULL) {
3932 const char *sub_msg = " in absolute path, with error: ";
3933 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3934 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3935 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3936 // If we can't find the agent, exit.
3937 vm_exit_during_initialization(buf, NULL);
3938 FREE_C_HEAP_ARRAY(char, buf);
3939 }
3940 } else {
3941 // Try to load the agent from the standard dll directory
3942 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3943 name)) {
3944 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3945 }
3946 if (library == NULL) { // Try the local directory
3947 char ns[1] = {0};
3948 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3949 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3950 }
3951 if (library == NULL) {
3952 const char *sub_msg = " on the library path, with error: ";
3953 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3954 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3955 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3956 // If we can't find the agent, exit.
3957 vm_exit_during_initialization(buf, NULL);
3958 FREE_C_HEAP_ARRAY(char, buf);
3959 }
3960 }
3961 }
3962 agent->set_os_lib(library);
3963 agent->set_valid();
3964 }
3965
3966 // Find the OnLoad function.
3967 on_load_entry =
3968 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3969 false,
3970 on_load_symbols,
3971 num_symbol_entries));
3972 return on_load_entry;
3973 }
3974
3975 // Find the JVM_OnLoad entry point
3976 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3977 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3978 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3979 }
3980
3981 // Find the Agent_OnLoad entry point
3982 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3983 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3984 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3985 }
3986
3987 // For backwards compatibility with -Xrun
3988 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3989 // treated like -agentpath:
3990 // Must be called before agent libraries are created
3991 void Threads::convert_vm_init_libraries_to_agents() {
3992 AgentLibrary* agent;
3993 AgentLibrary* next;
3994
3995 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3996 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3997 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3998
3999 // If there is an JVM_OnLoad function it will get called later,
4000 // otherwise see if there is an Agent_OnLoad
4001 if (on_load_entry == NULL) {
4002 on_load_entry = lookup_agent_on_load(agent);
4003 if (on_load_entry != NULL) {
4004 // switch it to the agent list -- so that Agent_OnLoad will be called,
4005 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4006 Arguments::convert_library_to_agent(agent);
4007 } else {
4008 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4009 }
4010 }
4011 }
4012 }
4013
4014 // Create agents for -agentlib: -agentpath: and converted -Xrun
4015 // Invokes Agent_OnLoad
4016 // Called very early -- before JavaThreads exist
4017 void Threads::create_vm_init_agents() {
4018 extern struct JavaVM_ main_vm;
4019 AgentLibrary* agent;
4020
4021 JvmtiExport::enter_onload_phase();
4022
4023 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4024 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4025
4026 if (on_load_entry != NULL) {
4027 // Invoke the Agent_OnLoad function
4028 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4029 if (err != JNI_OK) {
4030 vm_exit_during_initialization("agent library failed to init", agent->name());
4031 }
4032 } else {
4033 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4034 }
4035 }
4036 JvmtiExport::enter_primordial_phase();
4037 }
4038
4039 extern "C" {
4040 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4041 }
4042
4043 void Threads::shutdown_vm_agents() {
4044 // Send any Agent_OnUnload notifications
4045 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4046 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4047 extern struct JavaVM_ main_vm;
4048 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4049
4050 // Find the Agent_OnUnload function.
4051 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4052 os::find_agent_function(agent,
4053 false,
4054 on_unload_symbols,
4055 num_symbol_entries));
4056
4057 // Invoke the Agent_OnUnload function
4058 if (unload_entry != NULL) {
4059 JavaThread* thread = JavaThread::current();
4060 ThreadToNativeFromVM ttn(thread);
4061 HandleMark hm(thread);
4062 (*unload_entry)(&main_vm);
4063 }
4064 }
4065 }
4066
4067 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4068 // Invokes JVM_OnLoad
4069 void Threads::create_vm_init_libraries() {
4070 extern struct JavaVM_ main_vm;
4071 AgentLibrary* agent;
4072
4073 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4074 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4075
4076 if (on_load_entry != NULL) {
4077 // Invoke the JVM_OnLoad function
4078 JavaThread* thread = JavaThread::current();
4079 ThreadToNativeFromVM ttn(thread);
4080 HandleMark hm(thread);
4081 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4082 if (err != JNI_OK) {
4083 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4084 }
4085 } else {
4086 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4087 }
4088 }
4089 }
4090
4091 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
4092 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
4093
4094 JavaThread* java_thread = NULL;
4095 // Sequential search for now. Need to do better optimization later.
4096 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
4097 oop tobj = thread->threadObj();
4098 if (!thread->is_exiting() &&
4099 tobj != NULL &&
4100 java_tid == java_lang_Thread::thread_id(tobj)) {
4101 java_thread = thread;
4102 break;
4103 }
4104 }
4105 return java_thread;
4106 }
4107
4108
4109 // Last thread running calls java.lang.Shutdown.shutdown()
4110 void JavaThread::invoke_shutdown_hooks() {
4111 HandleMark hm(this);
4112
4113 // We could get here with a pending exception, if so clear it now.
4114 if (this->has_pending_exception()) {
4115 this->clear_pending_exception();
4116 }
4117
4118 EXCEPTION_MARK;
4119 Klass* k =
4120 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4121 THREAD);
4122 if (k != NULL) {
4123 // SystemDictionary::resolve_or_null will return null if there was
4124 // an exception. If we cannot load the Shutdown class, just don't
4125 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4126 // and finalizers (if runFinalizersOnExit is set) won't be run.
4127 // Note that if a shutdown hook was registered or runFinalizersOnExit
4128 // was called, the Shutdown class would have already been loaded
4129 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
4130 instanceKlassHandle shutdown_klass (THREAD, k);
4131 JavaValue result(T_VOID);
4132 JavaCalls::call_static(&result,
4133 shutdown_klass,
4134 vmSymbols::shutdown_method_name(),
4135 vmSymbols::void_method_signature(),
4136 THREAD);
4137 }
4138 CLEAR_PENDING_EXCEPTION;
4139 }
4140
4141 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4142 // the program falls off the end of main(). Another VM exit path is through
4143 // vm_exit() when the program calls System.exit() to return a value or when
4144 // there is a serious error in VM. The two shutdown paths are not exactly
4145 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4146 // and VM_Exit op at VM level.
4147 //
4148 // Shutdown sequence:
4149 // + Shutdown native memory tracking if it is on
4150 // + Wait until we are the last non-daemon thread to execute
4151 // <-- every thing is still working at this moment -->
4152 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4153 // shutdown hooks, run finalizers if finalization-on-exit
4154 // + Call before_exit(), prepare for VM exit
4155 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4156 // currently the only user of this mechanism is File.deleteOnExit())
4157 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
4158 // post thread end and vm death events to JVMTI,
4159 // stop signal thread
4160 // + Call JavaThread::exit(), it will:
4161 // > release JNI handle blocks, remove stack guard pages
4162 // > remove this thread from Threads list
4163 // <-- no more Java code from this thread after this point -->
4164 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4165 // the compiler threads at safepoint
4166 // <-- do not use anything that could get blocked by Safepoint -->
4167 // + Disable tracing at JNI/JVM barriers
4168 // + Set _vm_exited flag for threads that are still running native code
4169 // + Delete this thread
4170 // + Call exit_globals()
4171 // > deletes tty
4172 // > deletes PerfMemory resources
4173 // + Return to caller
4174
4175 bool Threads::destroy_vm() {
4176 JavaThread* thread = JavaThread::current();
4177
4178 #ifdef ASSERT
4179 _vm_complete = false;
4180 #endif
4181 // Wait until we are the last non-daemon thread to execute
4182 { MutexLocker nu(Threads_lock);
4183 while (Threads::number_of_non_daemon_threads() > 1)
4184 // This wait should make safepoint checks, wait without a timeout,
4185 // and wait as a suspend-equivalent condition.
4186 //
4187 // Note: If the FlatProfiler is running and this thread is waiting
4188 // for another non-daemon thread to finish, then the FlatProfiler
4189 // is waiting for the external suspend request on this thread to
4190 // complete. wait_for_ext_suspend_completion() will eventually
4191 // timeout, but that takes time. Making this wait a suspend-
4192 // equivalent condition solves that timeout problem.
4193 //
4194 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4195 Mutex::_as_suspend_equivalent_flag);
4196 }
4197
4198 // Hang forever on exit if we are reporting an error.
4199 if (ShowMessageBoxOnError && is_error_reported()) {
4200 os::infinite_sleep();
4201 }
4202 os::wait_for_keypress_at_exit();
4203
4204 // run Java level shutdown hooks
4205 thread->invoke_shutdown_hooks();
4206
4207 before_exit(thread);
4208
4209 thread->exit(true);
4210
4211 // Stop VM thread.
4212 {
4213 // 4945125 The vm thread comes to a safepoint during exit.
4214 // GC vm_operations can get caught at the safepoint, and the
4215 // heap is unparseable if they are caught. Grab the Heap_lock
4216 // to prevent this. The GC vm_operations will not be able to
4217 // queue until after the vm thread is dead. After this point,
4218 // we'll never emerge out of the safepoint before the VM exits.
4219
4220 MutexLocker ml(Heap_lock);
4221
4222 VMThread::wait_for_vm_thread_exit();
4223 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4224 VMThread::destroy();
4225 }
4226
4227 // clean up ideal graph printers
4228 #if defined(COMPILER2) && !defined(PRODUCT)
4229 IdealGraphPrinter::clean_up();
4230 #endif
4231
4232 // Now, all Java threads are gone except daemon threads. Daemon threads
4233 // running Java code or in VM are stopped by the Safepoint. However,
4234 // daemon threads executing native code are still running. But they
4235 // will be stopped at native=>Java/VM barriers. Note that we can't
4236 // simply kill or suspend them, as it is inherently deadlock-prone.
4237
4238 VM_Exit::set_vm_exited();
4239
4240 notify_vm_shutdown();
4241
4242 delete thread;
4243
4244 #if INCLUDE_JVMCI
4245 if (JVMCICounterSize > 0) {
4246 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4247 }
4248 #endif
4249
4250 // exit_globals() will delete tty
4251 exit_globals();
4252
4253 LogConfiguration::finalize();
4254
4255 return true;
4256 }
4257
4258
4259 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4260 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4261 return is_supported_jni_version(version);
4262 }
4263
4264
4265 jboolean Threads::is_supported_jni_version(jint version) {
4266 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4267 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4268 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4269 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4270 if (version == JNI_VERSION_9) return JNI_TRUE;
4271 return JNI_FALSE;
4272 }
4273
4274
4275 void Threads::add(JavaThread* p, bool force_daemon) {
4276 // The threads lock must be owned at this point
4277 assert_locked_or_safepoint(Threads_lock);
4278
4279 // See the comment for this method in thread.hpp for its purpose and
4280 // why it is called here.
4281 p->initialize_queues();
4282 p->set_next(_thread_list);
4283 _thread_list = p;
4284 _number_of_threads++;
4285 oop threadObj = p->threadObj();
4286 bool daemon = true;
4287 // Bootstrapping problem: threadObj can be null for initial
4288 // JavaThread (or for threads attached via JNI)
4289 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4290 _number_of_non_daemon_threads++;
4291 daemon = false;
4292 }
4293
4294 ThreadService::add_thread(p, daemon);
4295
4296 // Possible GC point.
4297 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4298 }
4299
4300 void Threads::remove(JavaThread* p) {
4301
4302 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4303 ObjectSynchronizer::omFlush(p);
4304
4305 // Extra scope needed for Thread_lock, so we can check
4306 // that we do not remove thread without safepoint code notice
4307 { MutexLocker ml(Threads_lock);
4308
4309 assert(includes(p), "p must be present");
4310
4311 JavaThread* current = _thread_list;
4312 JavaThread* prev = NULL;
4313
4314 while (current != p) {
4315 prev = current;
4316 current = current->next();
4317 }
4318
4319 if (prev) {
4320 prev->set_next(current->next());
4321 } else {
4322 _thread_list = p->next();
4323 }
4324 _number_of_threads--;
4325 oop threadObj = p->threadObj();
4326 bool daemon = true;
4327 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4328 _number_of_non_daemon_threads--;
4329 daemon = false;
4330
4331 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4332 // on destroy_vm will wake up.
4333 if (number_of_non_daemon_threads() == 1) {
4334 Threads_lock->notify_all();
4335 }
4336 }
4337 ThreadService::remove_thread(p, daemon);
4338
4339 // Make sure that safepoint code disregard this thread. This is needed since
4340 // the thread might mess around with locks after this point. This can cause it
4341 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4342 // of this thread since it is removed from the queue.
4343 p->set_terminated_value();
4344 } // unlock Threads_lock
4345
4346 // Since Events::log uses a lock, we grab it outside the Threads_lock
4347 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4348 }
4349
4350 // Threads_lock must be held when this is called (or must be called during a safepoint)
4351 bool Threads::includes(JavaThread* p) {
4352 assert(Threads_lock->is_locked(), "sanity check");
4353 ALL_JAVA_THREADS(q) {
4354 if (q == p) {
4355 return true;
4356 }
4357 }
4358 return false;
4359 }
4360
4361 // Operations on the Threads list for GC. These are not explicitly locked,
4362 // but the garbage collector must provide a safe context for them to run.
4363 // In particular, these things should never be called when the Threads_lock
4364 // is held by some other thread. (Note: the Safepoint abstraction also
4365 // uses the Threads_lock to guarantee this property. It also makes sure that
4366 // all threads gets blocked when exiting or starting).
4367
4368 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4369 ALL_JAVA_THREADS(p) {
4370 p->oops_do(f, cf);
4371 }
4372 VMThread::vm_thread()->oops_do(f, cf);
4373 }
4374
4375 void Threads::change_thread_claim_parity() {
4376 // Set the new claim parity.
4377 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4378 "Not in range.");
4379 _thread_claim_parity++;
4380 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4381 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4382 "Not in range.");
4383 }
4384
4385 #ifdef ASSERT
4386 void Threads::assert_all_threads_claimed() {
4387 ALL_JAVA_THREADS(p) {
4388 const int thread_parity = p->oops_do_parity();
4389 assert((thread_parity == _thread_claim_parity),
4390 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4391 }
4392 }
4393 #endif // ASSERT
4394
4395 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf, CodeBlobClosure* nmethods_cl) {
4396 int cp = Threads::thread_claim_parity();
4397 ALL_JAVA_THREADS(p) {
4398 if (p->claim_oops_do(is_par, cp)) {
4399 p->oops_do(f, cf);
4400 if (nmethods_cl != NULL && ! p->is_Code_cache_sweeper_thread()) {
4401 p->nmethods_do(nmethods_cl);
4402 }
4403 }
4404 }
4405 VMThread* vmt = VMThread::vm_thread();
4406 if (vmt->claim_oops_do(is_par, cp)) {
4407 vmt->oops_do(f, cf);
4408 }
4409 }
4410
4411 #if INCLUDE_ALL_GCS
4412 // Used by ParallelScavenge
4413 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4414 ALL_JAVA_THREADS(p) {
4415 q->enqueue(new ThreadRootsTask(p));
4416 }
4417 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4418 }
4419
4420 // Used by Parallel Old
4421 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4422 ALL_JAVA_THREADS(p) {
4423 q->enqueue(new ThreadRootsMarkingTask(p));
4424 }
4425 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4426 }
4427 #endif // INCLUDE_ALL_GCS
4428
4429 void Threads::nmethods_do(CodeBlobClosure* cf) {
4430 ALL_JAVA_THREADS(p) {
4431 // This is used by the code cache sweeper to mark nmethods that are active
4432 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4433 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4434 if(!p->is_Code_cache_sweeper_thread()) {
4435 p->nmethods_do(cf);
4436 }
4437 }
4438 }
4439
4440 void Threads::metadata_do(void f(Metadata*)) {
4441 ALL_JAVA_THREADS(p) {
4442 p->metadata_do(f);
4443 }
4444 }
4445
4446 class ThreadHandlesClosure : public ThreadClosure {
4447 void (*_f)(Metadata*);
4448 public:
4449 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4450 virtual void do_thread(Thread* thread) {
4451 thread->metadata_handles_do(_f);
4452 }
4453 };
4454
4455 void Threads::metadata_handles_do(void f(Metadata*)) {
4456 // Only walk the Handles in Thread.
4457 ThreadHandlesClosure handles_closure(f);
4458 threads_do(&handles_closure);
4459 }
4460
4461 void Threads::deoptimized_wrt_marked_nmethods() {
4462 ALL_JAVA_THREADS(p) {
4463 p->deoptimized_wrt_marked_nmethods();
4464 }
4465 }
4466
4467
4468 // Get count Java threads that are waiting to enter the specified monitor.
4469 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4470 address monitor,
4471 bool doLock) {
4472 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4473 "must grab Threads_lock or be at safepoint");
4474 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4475
4476 int i = 0;
4477 {
4478 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4479 ALL_JAVA_THREADS(p) {
4480 if (!p->can_call_java()) continue;
4481
4482 address pending = (address)p->current_pending_monitor();
4483 if (pending == monitor) { // found a match
4484 if (i < count) result->append(p); // save the first count matches
4485 i++;
4486 }
4487 }
4488 }
4489 return result;
4490 }
4491
4492
4493 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4494 bool doLock) {
4495 assert(doLock ||
4496 Threads_lock->owned_by_self() ||
4497 SafepointSynchronize::is_at_safepoint(),
4498 "must grab Threads_lock or be at safepoint");
4499
4500 // NULL owner means not locked so we can skip the search
4501 if (owner == NULL) return NULL;
4502
4503 {
4504 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4505 ALL_JAVA_THREADS(p) {
4506 // first, see if owner is the address of a Java thread
4507 if (owner == (address)p) return p;
4508 }
4509 }
4510 // Cannot assert on lack of success here since this function may be
4511 // used by code that is trying to report useful problem information
4512 // like deadlock detection.
4513 if (UseHeavyMonitors) return NULL;
4514
4515 // If we didn't find a matching Java thread and we didn't force use of
4516 // heavyweight monitors, then the owner is the stack address of the
4517 // Lock Word in the owning Java thread's stack.
4518 //
4519 JavaThread* the_owner = NULL;
4520 {
4521 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4522 ALL_JAVA_THREADS(q) {
4523 if (q->is_lock_owned(owner)) {
4524 the_owner = q;
4525 break;
4526 }
4527 }
4528 }
4529 // cannot assert on lack of success here; see above comment
4530 return the_owner;
4531 }
4532
4533 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4534 void Threads::print_on(outputStream* st, bool print_stacks,
4535 bool internal_format, bool print_concurrent_locks) {
4536 char buf[32];
4537 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4538
4539 st->print_cr("Full thread dump %s (%s %s):",
4540 Abstract_VM_Version::vm_name(),
4541 Abstract_VM_Version::vm_release(),
4542 Abstract_VM_Version::vm_info_string());
4543 st->cr();
4544
4545 #if INCLUDE_SERVICES
4546 // Dump concurrent locks
4547 ConcurrentLocksDump concurrent_locks;
4548 if (print_concurrent_locks) {
4549 concurrent_locks.dump_at_safepoint();
4550 }
4551 #endif // INCLUDE_SERVICES
4552
4553 ALL_JAVA_THREADS(p) {
4554 ResourceMark rm;
4555 p->print_on(st);
4556 if (print_stacks) {
4557 if (internal_format) {
4558 p->trace_stack();
4559 } else {
4560 p->print_stack_on(st);
4561 }
4562 }
4563 st->cr();
4564 #if INCLUDE_SERVICES
4565 if (print_concurrent_locks) {
4566 concurrent_locks.print_locks_on(p, st);
4567 }
4568 #endif // INCLUDE_SERVICES
4569 }
4570
4571 VMThread::vm_thread()->print_on(st);
4572 st->cr();
4573 Universe::heap()->print_gc_threads_on(st);
4574 WatcherThread* wt = WatcherThread::watcher_thread();
4575 if (wt != NULL) {
4576 wt->print_on(st);
4577 st->cr();
4578 }
4579 st->flush();
4580 }
4581
4582 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4583 int buflen, bool* found_current) {
4584 if (this_thread != NULL) {
4585 bool is_current = (current == this_thread);
4586 *found_current = *found_current || is_current;
4587 st->print("%s", is_current ? "=>" : " ");
4588
4589 st->print(PTR_FORMAT, p2i(this_thread));
4590 st->print(" ");
4591 this_thread->print_on_error(st, buf, buflen);
4592 st->cr();
4593 }
4594 }
4595
4596 class PrintOnErrorClosure : public ThreadClosure {
4597 outputStream* _st;
4598 Thread* _current;
4599 char* _buf;
4600 int _buflen;
4601 bool* _found_current;
4602 public:
4603 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4604 int buflen, bool* found_current) :
4605 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4606
4607 virtual void do_thread(Thread* thread) {
4608 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4609 }
4610 };
4611
4612 // Threads::print_on_error() is called by fatal error handler. It's possible
4613 // that VM is not at safepoint and/or current thread is inside signal handler.
4614 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4615 // memory (even in resource area), it might deadlock the error handler.
4616 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4617 int buflen) {
4618 bool found_current = false;
4619 st->print_cr("Java Threads: ( => current thread )");
4620 ALL_JAVA_THREADS(thread) {
4621 print_on_error(thread, st, current, buf, buflen, &found_current);
4622 }
4623 st->cr();
4624
4625 st->print_cr("Other Threads:");
4626 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4627 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4628
4629 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4630 Universe::heap()->gc_threads_do(&print_closure);
4631
4632 if (!found_current) {
4633 st->cr();
4634 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4635 current->print_on_error(st, buf, buflen);
4636 st->cr();
4637 }
4638 st->cr();
4639 st->print_cr("Threads with active compile tasks:");
4640 print_threads_compiling(st, buf, buflen);
4641 }
4642
4643 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4644 ALL_JAVA_THREADS(thread) {
4645 if (thread->is_Compiler_thread()) {
4646 CompilerThread* ct = (CompilerThread*) thread;
4647 if (ct->task() != NULL) {
4648 thread->print_name_on_error(st, buf, buflen);
4649 ct->task()->print(st, NULL, true, true);
4650 }
4651 }
4652 }
4653 }
4654
4655
4656 // Internal SpinLock and Mutex
4657 // Based on ParkEvent
4658
4659 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4660 //
4661 // We employ SpinLocks _only for low-contention, fixed-length
4662 // short-duration critical sections where we're concerned
4663 // about native mutex_t or HotSpot Mutex:: latency.
4664 // The mux construct provides a spin-then-block mutual exclusion
4665 // mechanism.
4666 //
4667 // Testing has shown that contention on the ListLock guarding gFreeList
4668 // is common. If we implement ListLock as a simple SpinLock it's common
4669 // for the JVM to devolve to yielding with little progress. This is true
4670 // despite the fact that the critical sections protected by ListLock are
4671 // extremely short.
4672 //
4673 // TODO-FIXME: ListLock should be of type SpinLock.
4674 // We should make this a 1st-class type, integrated into the lock
4675 // hierarchy as leaf-locks. Critically, the SpinLock structure
4676 // should have sufficient padding to avoid false-sharing and excessive
4677 // cache-coherency traffic.
4678
4679
4680 typedef volatile int SpinLockT;
4681
4682 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4683 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4684 return; // normal fast-path return
4685 }
4686
4687 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4688 TEVENT(SpinAcquire - ctx);
4689 int ctr = 0;
4690 int Yields = 0;
4691 for (;;) {
4692 while (*adr != 0) {
4693 ++ctr;
4694 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4695 if (Yields > 5) {
4696 os::naked_short_sleep(1);
4697 } else {
4698 os::naked_yield();
4699 ++Yields;
4700 }
4701 } else {
4702 SpinPause();
4703 }
4704 }
4705 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4706 }
4707 }
4708
4709 void Thread::SpinRelease(volatile int * adr) {
4710 assert(*adr != 0, "invariant");
4711 OrderAccess::fence(); // guarantee at least release consistency.
4712 // Roach-motel semantics.
4713 // It's safe if subsequent LDs and STs float "up" into the critical section,
4714 // but prior LDs and STs within the critical section can't be allowed
4715 // to reorder or float past the ST that releases the lock.
4716 // Loads and stores in the critical section - which appear in program
4717 // order before the store that releases the lock - must also appear
4718 // before the store that releases the lock in memory visibility order.
4719 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4720 // the ST of 0 into the lock-word which releases the lock, so fence
4721 // more than covers this on all platforms.
4722 *adr = 0;
4723 }
4724
4725 // muxAcquire and muxRelease:
4726 //
4727 // * muxAcquire and muxRelease support a single-word lock-word construct.
4728 // The LSB of the word is set IFF the lock is held.
4729 // The remainder of the word points to the head of a singly-linked list
4730 // of threads blocked on the lock.
4731 //
4732 // * The current implementation of muxAcquire-muxRelease uses its own
4733 // dedicated Thread._MuxEvent instance. If we're interested in
4734 // minimizing the peak number of extant ParkEvent instances then
4735 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4736 // as certain invariants were satisfied. Specifically, care would need
4737 // to be taken with regards to consuming unpark() "permits".
4738 // A safe rule of thumb is that a thread would never call muxAcquire()
4739 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4740 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4741 // consume an unpark() permit intended for monitorenter, for instance.
4742 // One way around this would be to widen the restricted-range semaphore
4743 // implemented in park(). Another alternative would be to provide
4744 // multiple instances of the PlatformEvent() for each thread. One
4745 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4746 //
4747 // * Usage:
4748 // -- Only as leaf locks
4749 // -- for short-term locking only as muxAcquire does not perform
4750 // thread state transitions.
4751 //
4752 // Alternatives:
4753 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4754 // but with parking or spin-then-park instead of pure spinning.
4755 // * Use Taura-Oyama-Yonenzawa locks.
4756 // * It's possible to construct a 1-0 lock if we encode the lockword as
4757 // (List,LockByte). Acquire will CAS the full lockword while Release
4758 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4759 // acquiring threads use timers (ParkTimed) to detect and recover from
4760 // the stranding window. Thread/Node structures must be aligned on 256-byte
4761 // boundaries by using placement-new.
4762 // * Augment MCS with advisory back-link fields maintained with CAS().
4763 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4764 // The validity of the backlinks must be ratified before we trust the value.
4765 // If the backlinks are invalid the exiting thread must back-track through the
4766 // the forward links, which are always trustworthy.
4767 // * Add a successor indication. The LockWord is currently encoded as
4768 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4769 // to provide the usual futile-wakeup optimization.
4770 // See RTStt for details.
4771 // * Consider schedctl.sc_nopreempt to cover the critical section.
4772 //
4773
4774
4775 typedef volatile intptr_t MutexT; // Mux Lock-word
4776 enum MuxBits { LOCKBIT = 1 };
4777
4778 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4779 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4780 if (w == 0) return;
4781 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4782 return;
4783 }
4784
4785 TEVENT(muxAcquire - Contention);
4786 ParkEvent * const Self = Thread::current()->_MuxEvent;
4787 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4788 for (;;) {
4789 int its = (os::is_MP() ? 100 : 0) + 1;
4790
4791 // Optional spin phase: spin-then-park strategy
4792 while (--its >= 0) {
4793 w = *Lock;
4794 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4795 return;
4796 }
4797 }
4798
4799 Self->reset();
4800 Self->OnList = intptr_t(Lock);
4801 // The following fence() isn't _strictly necessary as the subsequent
4802 // CAS() both serializes execution and ratifies the fetched *Lock value.
4803 OrderAccess::fence();
4804 for (;;) {
4805 w = *Lock;
4806 if ((w & LOCKBIT) == 0) {
4807 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4808 Self->OnList = 0; // hygiene - allows stronger asserts
4809 return;
4810 }
4811 continue; // Interference -- *Lock changed -- Just retry
4812 }
4813 assert(w & LOCKBIT, "invariant");
4814 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4815 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4816 }
4817
4818 while (Self->OnList != 0) {
4819 Self->park();
4820 }
4821 }
4822 }
4823
4824 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4825 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4826 if (w == 0) return;
4827 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4828 return;
4829 }
4830
4831 TEVENT(muxAcquire - Contention);
4832 ParkEvent * ReleaseAfter = NULL;
4833 if (ev == NULL) {
4834 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4835 }
4836 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4837 for (;;) {
4838 guarantee(ev->OnList == 0, "invariant");
4839 int its = (os::is_MP() ? 100 : 0) + 1;
4840
4841 // Optional spin phase: spin-then-park strategy
4842 while (--its >= 0) {
4843 w = *Lock;
4844 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4845 if (ReleaseAfter != NULL) {
4846 ParkEvent::Release(ReleaseAfter);
4847 }
4848 return;
4849 }
4850 }
4851
4852 ev->reset();
4853 ev->OnList = intptr_t(Lock);
4854 // The following fence() isn't _strictly necessary as the subsequent
4855 // CAS() both serializes execution and ratifies the fetched *Lock value.
4856 OrderAccess::fence();
4857 for (;;) {
4858 w = *Lock;
4859 if ((w & LOCKBIT) == 0) {
4860 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4861 ev->OnList = 0;
4862 // We call ::Release while holding the outer lock, thus
4863 // artificially lengthening the critical section.
4864 // Consider deferring the ::Release() until the subsequent unlock(),
4865 // after we've dropped the outer lock.
4866 if (ReleaseAfter != NULL) {
4867 ParkEvent::Release(ReleaseAfter);
4868 }
4869 return;
4870 }
4871 continue; // Interference -- *Lock changed -- Just retry
4872 }
4873 assert(w & LOCKBIT, "invariant");
4874 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4875 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4876 }
4877
4878 while (ev->OnList != 0) {
4879 ev->park();
4880 }
4881 }
4882 }
4883
4884 // Release() must extract a successor from the list and then wake that thread.
4885 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4886 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4887 // Release() would :
4888 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4889 // (B) Extract a successor from the private list "in-hand"
4890 // (C) attempt to CAS() the residual back into *Lock over null.
4891 // If there were any newly arrived threads and the CAS() would fail.
4892 // In that case Release() would detach the RATs, re-merge the list in-hand
4893 // with the RATs and repeat as needed. Alternately, Release() might
4894 // detach and extract a successor, but then pass the residual list to the wakee.
4895 // The wakee would be responsible for reattaching and remerging before it
4896 // competed for the lock.
4897 //
4898 // Both "pop" and DMR are immune from ABA corruption -- there can be
4899 // multiple concurrent pushers, but only one popper or detacher.
4900 // This implementation pops from the head of the list. This is unfair,
4901 // but tends to provide excellent throughput as hot threads remain hot.
4902 // (We wake recently run threads first).
4903 //
4904 // All paths through muxRelease() will execute a CAS.
4905 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4906 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4907 // executed within the critical section are complete and globally visible before the
4908 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4909 void Thread::muxRelease(volatile intptr_t * Lock) {
4910 for (;;) {
4911 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4912 assert(w & LOCKBIT, "invariant");
4913 if (w == LOCKBIT) return;
4914 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4915 assert(List != NULL, "invariant");
4916 assert(List->OnList == intptr_t(Lock), "invariant");
4917 ParkEvent * const nxt = List->ListNext;
4918 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4919
4920 // The following CAS() releases the lock and pops the head element.
4921 // The CAS() also ratifies the previously fetched lock-word value.
4922 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4923 continue;
4924 }
4925 List->OnList = 0;
4926 OrderAccess::fence();
4927 List->unpark();
4928 return;
4929 }
4930 }
4931
4932
4933 void Threads::verify() {
4934 ALL_JAVA_THREADS(p) {
4935 p->verify();
4936 }
4937 VMThread* thread = VMThread::vm_thread();
4938 if (thread != NULL) thread->verify();
4939 }