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