1 /*
2 * Copyright (c) 1997, 2018, 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 "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jfr/support/jfrThreadId.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "prims/privilegedStack.hpp"
65 #include "runtime/arguments.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/biasedLocking.hpp"
68 #include "runtime/fieldDescriptor.inline.hpp"
69 #include "runtime/flags/jvmFlagConstraintList.hpp"
70 #include "runtime/flags/jvmFlagRangeList.hpp"
71 #include "runtime/flags/jvmFlagWriteableList.hpp"
72 #include "runtime/deoptimization.hpp"
73 #include "runtime/frame.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/sharedRuntime.hpp"
91 #include "runtime/statSampler.hpp"
92 #include "runtime/stubRoutines.hpp"
93 #include "runtime/sweeper.hpp"
94 #include "runtime/task.hpp"
95 #include "runtime/thread.inline.hpp"
96 #include "runtime/threadCritical.hpp"
97 #include "runtime/threadSMR.inline.hpp"
98 #include "runtime/threadStatisticalInfo.hpp"
99 #include "runtime/timer.hpp"
100 #include "runtime/timerTrace.hpp"
101 #include "runtime/vframe.inline.hpp"
102 #include "runtime/vframeArray.hpp"
103 #include "runtime/vframe_hp.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "runtime/vm_operations.hpp"
106 #include "runtime/vm_version.hpp"
107 #include "services/attachListener.hpp"
108 #include "services/management.hpp"
109 #include "services/memTracker.hpp"
110 #include "services/threadService.hpp"
111 #include "utilities/align.hpp"
112 #include "utilities/copy.hpp"
113 #include "utilities/defaultStream.hpp"
114 #include "utilities/dtrace.hpp"
115 #include "utilities/events.hpp"
116 #include "utilities/macros.hpp"
117 #include "utilities/preserveException.hpp"
118 #include "utilities/singleWriterSynchronizer.hpp"
119 #include "utilities/vmError.hpp"
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmciCompiler.hpp"
122 #include "jvmci/jvmciRuntime.hpp"
123 #include "logging/logHandle.hpp"
124 #endif
125 #ifdef COMPILER1
126 #include "c1/c1_Compiler.hpp"
127 #endif
128 #ifdef COMPILER2
129 #include "opto/c2compiler.hpp"
130 #include "opto/idealGraphPrinter.hpp"
131 #endif
132 #if INCLUDE_RTM_OPT
133 #include "runtime/rtmLocking.hpp"
134 #endif
135 #if INCLUDE_JFR
136 #include "jfr/jfr.hpp"
137 #endif
138
139 // Initialization after module runtime initialization
140 void universe_post_module_init(); // must happen after call_initPhase2
141
142 #ifdef DTRACE_ENABLED
143
144 // Only bother with this argument setup if dtrace is available
145
146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
148
149 #define DTRACE_THREAD_PROBE(probe, javathread) \
150 { \
151 ResourceMark rm(this); \
152 int len = 0; \
153 const char* name = (javathread)->get_thread_name(); \
154 len = strlen(name); \
155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
156 (char *) name, len, \
157 java_lang_Thread::thread_id((javathread)->threadObj()), \
158 (uintptr_t) (javathread)->osthread()->thread_id(), \
159 java_lang_Thread::is_daemon((javathread)->threadObj())); \
160 }
161
162 #else // ndef DTRACE_ENABLED
163
164 #define DTRACE_THREAD_PROBE(probe, javathread)
165
166 #endif // ndef DTRACE_ENABLED
167
168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
169 // Current thread is maintained as a thread-local variable
170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
171 #endif
172
173 // ======= Thread ========
174 // Support for forcing alignment of thread objects for biased locking
175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
176 if (UseBiasedLocking) {
177 const int alignment = markOopDesc::biased_lock_alignment;
178 size_t aligned_size = size + (alignment - sizeof(intptr_t));
179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
180 : AllocateHeap(aligned_size, flags, CURRENT_PC,
181 AllocFailStrategy::RETURN_NULL);
182 void* aligned_addr = align_up(real_malloc_addr, alignment);
183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
185 "JavaThread alignment code overflowed allocated storage");
186 if (aligned_addr != real_malloc_addr) {
187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
188 p2i(real_malloc_addr),
189 p2i(aligned_addr));
190 }
191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
192 return aligned_addr;
193 } else {
194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
196 }
197 }
198
199 void Thread::operator delete(void* p) {
200 if (UseBiasedLocking) {
201 FreeHeap(((Thread*) p)->_real_malloc_address);
202 } else {
203 FreeHeap(p);
204 }
205 }
206
207 void JavaThread::smr_delete() {
208 if (_on_thread_list) {
209 ThreadsSMRSupport::smr_delete(this);
210 } else {
211 delete this;
212 }
213 }
214
215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
216 // JavaThread
217
218
219 Thread::Thread() {
220 // stack and get_thread
221 set_stack_base(NULL);
222 set_stack_size(0);
223 set_self_raw_id(0);
224 set_lgrp_id(-1);
225 DEBUG_ONLY(clear_suspendible_thread();)
226
227 // allocated data structures
228 set_osthread(NULL);
229 set_resource_area(new (mtThread)ResourceArea());
230 DEBUG_ONLY(_current_resource_mark = NULL;)
231 set_handle_area(new (mtThread) HandleArea(NULL));
232 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
233 set_active_handles(NULL);
234 set_free_handle_block(NULL);
235 set_last_handle_mark(NULL);
236
237 // This initial value ==> never claimed.
238 _oops_do_parity = 0;
239 _threads_hazard_ptr = NULL;
240 _threads_list_ptr = NULL;
241 _nested_threads_hazard_ptr_cnt = 0;
242 _rcu_counter = 0;
243
244 // the handle mark links itself to last_handle_mark
245 new HandleMark(this);
246
247 // plain initialization
248 debug_only(_owned_locks = NULL;)
249 debug_only(_allow_allocation_count = 0;)
250 NOT_PRODUCT(_allow_safepoint_count = 0;)
251 NOT_PRODUCT(_skip_gcalot = false;)
252 _jvmti_env_iteration_count = 0;
253 set_allocated_bytes(0);
254 _vm_operation_started_count = 0;
255 _vm_operation_completed_count = 0;
256 _current_pending_monitor = NULL;
257 _current_pending_monitor_is_from_java = true;
258 _current_waiting_monitor = NULL;
259 _num_nested_signal = 0;
260 omFreeList = NULL;
261 omFreeCount = 0;
262 omFreeProvision = 32;
263 omInUseList = NULL;
264 omInUseCount = 0;
265
266 #ifdef ASSERT
267 _visited_for_critical_count = false;
268 #endif
269
270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
271 Monitor::_safepoint_check_sometimes);
272 _suspend_flags = 0;
273
274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
275 _hashStateX = os::random();
276 _hashStateY = 842502087;
277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
278 _hashStateW = 273326509;
279
280 _OnTrap = 0;
281 _Stalled = 0;
282 _TypeTag = 0x2BAD;
283
284 // Many of the following fields are effectively final - immutable
285 // Note that nascent threads can't use the Native Monitor-Mutex
286 // construct until the _MutexEvent is initialized ...
287 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
288 // we might instead use a stack of ParkEvents that we could provision on-demand.
289 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
290 // and ::Release()
291 _ParkEvent = ParkEvent::Allocate(this);
292 _SleepEvent = ParkEvent::Allocate(this);
293 _MutexEvent = ParkEvent::Allocate(this);
294 _MuxEvent = ParkEvent::Allocate(this);
295
296 #ifdef CHECK_UNHANDLED_OOPS
297 if (CheckUnhandledOops) {
298 _unhandled_oops = new UnhandledOops(this);
299 }
300 #endif // CHECK_UNHANDLED_OOPS
301 #ifdef ASSERT
302 if (UseBiasedLocking) {
303 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
304 assert(this == _real_malloc_address ||
305 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
306 "bug in forced alignment of thread objects");
307 }
308 #endif // ASSERT
309
310 // Notify the barrier set that a thread is being created. Note that some
311 // threads are created before a barrier set is available. The call to
312 // BarrierSet::on_thread_create() for these threads is therefore deferred
313 // to BarrierSet::set_barrier_set().
314 BarrierSet* const barrier_set = BarrierSet::barrier_set();
315 if (barrier_set != NULL) {
316 barrier_set->on_thread_create(this);
317 } else {
318 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
319 }
320 }
321
322 void Thread::initialize_thread_current() {
323 #ifndef USE_LIBRARY_BASED_TLS_ONLY
324 assert(_thr_current == NULL, "Thread::current already initialized");
325 _thr_current = this;
326 #endif
327 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
328 ThreadLocalStorage::set_thread(this);
329 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
330 }
331
332 void Thread::clear_thread_current() {
333 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
334 #ifndef USE_LIBRARY_BASED_TLS_ONLY
335 _thr_current = NULL;
336 #endif
337 ThreadLocalStorage::set_thread(NULL);
338 }
339
340 void Thread::record_stack_base_and_size() {
341 // Note: at this point, Thread object is not yet initialized. Do not rely on
342 // any members being initialized. Do not rely on Thread::current() being set.
343 // If possible, refrain from doing anything which may crash or assert since
344 // quite probably those crash dumps will be useless.
345 set_stack_base(os::current_stack_base());
346 set_stack_size(os::current_stack_size());
347
348 #ifdef SOLARIS
349 if (is_primordial_thread()) {
350 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
351 }
352 #endif
353
354 // Set stack limits after thread is initialized.
355 if (is_Java_thread()) {
356 ((JavaThread*) this)->set_stack_overflow_limit();
357 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
358 }
359 }
360
361 #if INCLUDE_NMT
362 void Thread::register_thread_stack_with_NMT() {
363 MemTracker::record_thread_stack(stack_end(), stack_size());
364 }
365 #endif // INCLUDE_NMT
366
367 void Thread::call_run() {
368 // At this point, Thread object should be fully initialized and
369 // Thread::current() should be set.
370
371 register_thread_stack_with_NMT();
372
373 log_info(os, thread)("Thread is alive (tid: " UINTX_FORMAT ").",
374 os::current_thread_id());
375 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
376 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
377 os::current_thread_id(), p2i(stack_base() - stack_size()),
378 p2i(stack_base()), stack_size()/1024);
379
380 this->run();
381
382 // Note: at this point the thread object may already have deleted itself.
383 // So from here on do not refer to this.
384
385 log_info(os, thread)("Thread finished (tid: " UINTX_FORMAT ").",
386 os::current_thread_id());
387 }
388
389 Thread::~Thread() {
390 JFR_ONLY(Jfr::on_thread_destruct(this);)
391
392 // Notify the barrier set that a thread is being destroyed. Note that a barrier
393 // set might not be available if we encountered errors during bootstrapping.
394 BarrierSet* const barrier_set = BarrierSet::barrier_set();
395 if (barrier_set != NULL) {
396 barrier_set->on_thread_destroy(this);
397 }
398
399
400 // stack_base can be NULL if the thread is never started or exited before
401 // record_stack_base_and_size called. Although, we would like to ensure
402 // that all started threads do call record_stack_base_and_size(), there is
403 // not proper way to enforce that.
404 #if INCLUDE_NMT
405 if (_stack_base != NULL) {
406 MemTracker::release_thread_stack(stack_end(), stack_size());
407 #ifdef ASSERT
408 set_stack_base(NULL);
409 #endif
410 }
411 #endif // INCLUDE_NMT
412
413 // deallocate data structures
414 delete resource_area();
415 // since the handle marks are using the handle area, we have to deallocated the root
416 // handle mark before deallocating the thread's handle area,
417 assert(last_handle_mark() != NULL, "check we have an element");
418 delete last_handle_mark();
419 assert(last_handle_mark() == NULL, "check we have reached the end");
420
421 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
422 // We NULL out the fields for good hygiene.
423 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
424 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
425 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
426 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
427
428 delete handle_area();
429 delete metadata_handles();
430
431 // SR_handler uses this as a termination indicator -
432 // needs to happen before os::free_thread()
433 delete _SR_lock;
434 _SR_lock = NULL;
435
436 // osthread() can be NULL, if creation of thread failed.
437 if (osthread() != NULL) os::free_thread(osthread());
438
439 // clear Thread::current if thread is deleting itself.
440 // Needed to ensure JNI correctly detects non-attached threads.
441 if (this == Thread::current()) {
442 clear_thread_current();
443 }
444
445 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
446 }
447
448 #ifdef ASSERT
449 // A JavaThread is considered "dangling" if it is not the current
450 // thread, has been added the Threads list, the system is not at a
451 // safepoint and the Thread is not "protected".
452 //
453 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
454 assert(!thread->is_Java_thread() || Thread::current() == thread ||
455 !((JavaThread *) thread)->on_thread_list() ||
456 SafepointSynchronize::is_at_safepoint() ||
457 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
458 "possibility of dangling Thread pointer");
459 }
460 #endif
461
462 ThreadPriority Thread::get_priority(const Thread* const thread) {
463 ThreadPriority priority;
464 // Can return an error!
465 (void)os::get_priority(thread, priority);
466 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
467 return priority;
468 }
469
470 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
471 debug_only(check_for_dangling_thread_pointer(thread);)
472 // Can return an error!
473 (void)os::set_priority(thread, priority);
474 }
475
476
477 void Thread::start(Thread* thread) {
478 // Start is different from resume in that its safety is guaranteed by context or
479 // being called from a Java method synchronized on the Thread object.
480 if (!DisableStartThread) {
481 if (thread->is_Java_thread()) {
482 // Initialize the thread state to RUNNABLE before starting this thread.
483 // Can not set it after the thread started because we do not know the
484 // exact thread state at that time. It could be in MONITOR_WAIT or
485 // in SLEEPING or some other state.
486 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
487 java_lang_Thread::RUNNABLE);
488 }
489 os::start_thread(thread);
490 }
491 }
492
493 // Enqueue a VM_Operation to do the job for us - sometime later
494 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
495 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
496 VMThread::execute(vm_stop);
497 }
498
499
500 // Check if an external suspend request has completed (or has been
501 // cancelled). Returns true if the thread is externally suspended and
502 // false otherwise.
503 //
504 // The bits parameter returns information about the code path through
505 // the routine. Useful for debugging:
506 //
507 // set in is_ext_suspend_completed():
508 // 0x00000001 - routine was entered
509 // 0x00000010 - routine return false at end
510 // 0x00000100 - thread exited (return false)
511 // 0x00000200 - suspend request cancelled (return false)
512 // 0x00000400 - thread suspended (return true)
513 // 0x00001000 - thread is in a suspend equivalent state (return true)
514 // 0x00002000 - thread is native and walkable (return true)
515 // 0x00004000 - thread is native_trans and walkable (needed retry)
516 //
517 // set in wait_for_ext_suspend_completion():
518 // 0x00010000 - routine was entered
519 // 0x00020000 - suspend request cancelled before loop (return false)
520 // 0x00040000 - thread suspended before loop (return true)
521 // 0x00080000 - suspend request cancelled in loop (return false)
522 // 0x00100000 - thread suspended in loop (return true)
523 // 0x00200000 - suspend not completed during retry loop (return false)
524
525 // Helper class for tracing suspend wait debug bits.
526 //
527 // 0x00000100 indicates that the target thread exited before it could
528 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
529 // 0x00080000 each indicate a cancelled suspend request so they don't
530 // count as wait failures either.
531 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
532
533 class TraceSuspendDebugBits : public StackObj {
534 private:
535 JavaThread * jt;
536 bool is_wait;
537 bool called_by_wait; // meaningful when !is_wait
538 uint32_t * bits;
539
540 public:
541 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
542 uint32_t *_bits) {
543 jt = _jt;
544 is_wait = _is_wait;
545 called_by_wait = _called_by_wait;
546 bits = _bits;
547 }
548
549 ~TraceSuspendDebugBits() {
550 if (!is_wait) {
551 #if 1
552 // By default, don't trace bits for is_ext_suspend_completed() calls.
553 // That trace is very chatty.
554 return;
555 #else
556 if (!called_by_wait) {
557 // If tracing for is_ext_suspend_completed() is enabled, then only
558 // trace calls to it from wait_for_ext_suspend_completion()
559 return;
560 }
561 #endif
562 }
563
564 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
565 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
566 MutexLocker ml(Threads_lock); // needed for get_thread_name()
567 ResourceMark rm;
568
569 tty->print_cr(
570 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
571 jt->get_thread_name(), *bits);
572
573 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
574 }
575 }
576 }
577 };
578 #undef DEBUG_FALSE_BITS
579
580
581 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
582 uint32_t *bits) {
583 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
584
585 bool did_trans_retry = false; // only do thread_in_native_trans retry once
586 bool do_trans_retry; // flag to force the retry
587
588 *bits |= 0x00000001;
589
590 do {
591 do_trans_retry = false;
592
593 if (is_exiting()) {
594 // Thread is in the process of exiting. This is always checked
595 // first to reduce the risk of dereferencing a freed JavaThread.
596 *bits |= 0x00000100;
597 return false;
598 }
599
600 if (!is_external_suspend()) {
601 // Suspend request is cancelled. This is always checked before
602 // is_ext_suspended() to reduce the risk of a rogue resume
603 // confusing the thread that made the suspend request.
604 *bits |= 0x00000200;
605 return false;
606 }
607
608 if (is_ext_suspended()) {
609 // thread is suspended
610 *bits |= 0x00000400;
611 return true;
612 }
613
614 // Now that we no longer do hard suspends of threads running
615 // native code, the target thread can be changing thread state
616 // while we are in this routine:
617 //
618 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
619 //
620 // We save a copy of the thread state as observed at this moment
621 // and make our decision about suspend completeness based on the
622 // copy. This closes the race where the thread state is seen as
623 // _thread_in_native_trans in the if-thread_blocked check, but is
624 // seen as _thread_blocked in if-thread_in_native_trans check.
625 JavaThreadState save_state = thread_state();
626
627 if (save_state == _thread_blocked && is_suspend_equivalent()) {
628 // If the thread's state is _thread_blocked and this blocking
629 // condition is known to be equivalent to a suspend, then we can
630 // consider the thread to be externally suspended. This means that
631 // the code that sets _thread_blocked has been modified to do
632 // self-suspension if the blocking condition releases. We also
633 // used to check for CONDVAR_WAIT here, but that is now covered by
634 // the _thread_blocked with self-suspension check.
635 //
636 // Return true since we wouldn't be here unless there was still an
637 // external suspend request.
638 *bits |= 0x00001000;
639 return true;
640 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
641 // Threads running native code will self-suspend on native==>VM/Java
642 // transitions. If its stack is walkable (should always be the case
643 // unless this function is called before the actual java_suspend()
644 // call), then the wait is done.
645 *bits |= 0x00002000;
646 return true;
647 } else if (!called_by_wait && !did_trans_retry &&
648 save_state == _thread_in_native_trans &&
649 frame_anchor()->walkable()) {
650 // The thread is transitioning from thread_in_native to another
651 // thread state. check_safepoint_and_suspend_for_native_trans()
652 // will force the thread to self-suspend. If it hasn't gotten
653 // there yet we may have caught the thread in-between the native
654 // code check above and the self-suspend. Lucky us. If we were
655 // called by wait_for_ext_suspend_completion(), then it
656 // will be doing the retries so we don't have to.
657 //
658 // Since we use the saved thread state in the if-statement above,
659 // there is a chance that the thread has already transitioned to
660 // _thread_blocked by the time we get here. In that case, we will
661 // make a single unnecessary pass through the logic below. This
662 // doesn't hurt anything since we still do the trans retry.
663
664 *bits |= 0x00004000;
665
666 // Once the thread leaves thread_in_native_trans for another
667 // thread state, we break out of this retry loop. We shouldn't
668 // need this flag to prevent us from getting back here, but
669 // sometimes paranoia is good.
670 did_trans_retry = true;
671
672 // We wait for the thread to transition to a more usable state.
673 for (int i = 1; i <= SuspendRetryCount; i++) {
674 // We used to do an "os::yield_all(i)" call here with the intention
675 // that yielding would increase on each retry. However, the parameter
676 // is ignored on Linux which means the yield didn't scale up. Waiting
677 // on the SR_lock below provides a much more predictable scale up for
678 // the delay. It also provides a simple/direct point to check for any
679 // safepoint requests from the VMThread
680
681 // temporarily drops SR_lock while doing wait with safepoint check
682 // (if we're a JavaThread - the WatcherThread can also call this)
683 // and increase delay with each retry
684 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
685
686 // check the actual thread state instead of what we saved above
687 if (thread_state() != _thread_in_native_trans) {
688 // the thread has transitioned to another thread state so
689 // try all the checks (except this one) one more time.
690 do_trans_retry = true;
691 break;
692 }
693 } // end retry loop
694
695
696 }
697 } while (do_trans_retry);
698
699 *bits |= 0x00000010;
700 return false;
701 }
702
703 // Wait for an external suspend request to complete (or be cancelled).
704 // Returns true if the thread is externally suspended and false otherwise.
705 //
706 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
707 uint32_t *bits) {
708 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
709 false /* !called_by_wait */, bits);
710
711 // local flag copies to minimize SR_lock hold time
712 bool is_suspended;
713 bool pending;
714 uint32_t reset_bits;
715
716 // set a marker so is_ext_suspend_completed() knows we are the caller
717 *bits |= 0x00010000;
718
719 // We use reset_bits to reinitialize the bits value at the top of
720 // each retry loop. This allows the caller to make use of any
721 // unused bits for their own marking purposes.
722 reset_bits = *bits;
723
724 {
725 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
727 delay, bits);
728 pending = is_external_suspend();
729 }
730 // must release SR_lock to allow suspension to complete
731
732 if (!pending) {
733 // A cancelled suspend request is the only false return from
734 // is_ext_suspend_completed() that keeps us from entering the
735 // retry loop.
736 *bits |= 0x00020000;
737 return false;
738 }
739
740 if (is_suspended) {
741 *bits |= 0x00040000;
742 return true;
743 }
744
745 for (int i = 1; i <= retries; i++) {
746 *bits = reset_bits; // reinit to only track last retry
747
748 // We used to do an "os::yield_all(i)" call here with the intention
749 // that yielding would increase on each retry. However, the parameter
750 // is ignored on Linux which means the yield didn't scale up. Waiting
751 // on the SR_lock below provides a much more predictable scale up for
752 // the delay. It also provides a simple/direct point to check for any
753 // safepoint requests from the VMThread
754
755 {
756 MutexLocker ml(SR_lock());
757 // wait with safepoint check (if we're a JavaThread - the WatcherThread
758 // can also call this) and increase delay with each retry
759 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
760
761 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
762 delay, bits);
763
764 // It is possible for the external suspend request to be cancelled
765 // (by a resume) before the actual suspend operation is completed.
766 // Refresh our local copy to see if we still need to wait.
767 pending = is_external_suspend();
768 }
769
770 if (!pending) {
771 // A cancelled suspend request is the only false return from
772 // is_ext_suspend_completed() that keeps us from staying in the
773 // retry loop.
774 *bits |= 0x00080000;
775 return false;
776 }
777
778 if (is_suspended) {
779 *bits |= 0x00100000;
780 return true;
781 }
782 } // end retry loop
783
784 // thread did not suspend after all our retries
785 *bits |= 0x00200000;
786 return false;
787 }
788
789 // Called from API entry points which perform stack walking. If the
790 // associated JavaThread is the current thread, then wait_for_suspend
791 // is not used. Otherwise, it determines if we should wait for the
792 // "other" thread to complete external suspension. (NOTE: in future
793 // releases the suspension mechanism should be reimplemented so this
794 // is not necessary.)
795 //
796 bool
797 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
798 if (this != JavaThread::current()) {
799 // "other" threads require special handling.
800 if (wait_for_suspend) {
801 // We are allowed to wait for the external suspend to complete
802 // so give the other thread a chance to get suspended.
803 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
804 SuspendRetryDelay, bits)) {
805 // Didn't make it so let the caller know.
806 return false;
807 }
808 }
809 // We aren't allowed to wait for the external suspend to complete
810 // so if the other thread isn't externally suspended we need to
811 // let the caller know.
812 else if (!is_ext_suspend_completed_with_lock(bits)) {
813 return false;
814 }
815 }
816
817 return true;
818 }
819
820 #ifndef PRODUCT
821 void JavaThread::record_jump(address target, address instr, const char* file,
822 int line) {
823
824 // This should not need to be atomic as the only way for simultaneous
825 // updates is via interrupts. Even then this should be rare or non-existent
826 // and we don't care that much anyway.
827
828 int index = _jmp_ring_index;
829 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
830 _jmp_ring[index]._target = (intptr_t) target;
831 _jmp_ring[index]._instruction = (intptr_t) instr;
832 _jmp_ring[index]._file = file;
833 _jmp_ring[index]._line = line;
834 }
835 #endif // PRODUCT
836
837 void Thread::interrupt(Thread* thread) {
838 debug_only(check_for_dangling_thread_pointer(thread);)
839 os::interrupt(thread);
840 }
841
842 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
843 debug_only(check_for_dangling_thread_pointer(thread);)
844 // Note: If clear_interrupted==false, this simply fetches and
845 // returns the value of the field osthread()->interrupted().
846 return os::is_interrupted(thread, clear_interrupted);
847 }
848
849
850 // GC Support
851 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
852 int thread_parity = _oops_do_parity;
853 if (thread_parity != strong_roots_parity) {
854 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
855 if (res == thread_parity) {
856 return true;
857 } else {
858 guarantee(res == strong_roots_parity, "Or else what?");
859 return false;
860 }
861 }
862 return false;
863 }
864
865 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
866 active_handles()->oops_do(f);
867 // Do oop for ThreadShadow
868 f->do_oop((oop*)&_pending_exception);
869 handle_area()->oops_do(f);
870
871 // We scan thread local monitor lists here, and the remaining global
872 // monitors in ObjectSynchronizer::oops_do().
873 ObjectSynchronizer::thread_local_used_oops_do(this, f);
874 }
875
876 void Thread::metadata_handles_do(void f(Metadata*)) {
877 // Only walk the Handles in Thread.
878 if (metadata_handles() != NULL) {
879 for (int i = 0; i< metadata_handles()->length(); i++) {
880 f(metadata_handles()->at(i));
881 }
882 }
883 }
884
885 void Thread::print_on(outputStream* st, bool print_extended_info) const {
886 // get_priority assumes osthread initialized
887 if (osthread() != NULL) {
888 int os_prio;
889 if (os::get_native_priority(this, &os_prio) == OS_OK) {
890 st->print("os_prio=%d ", os_prio);
891 }
892
893 st->print("cpu=%.2fms ",
894 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
895 );
896 st->print("elapsed=%.2fs ",
897 _statistical_info.getElapsedTime() / 1000.0
898 );
899 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
900 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
901 st->print("allocated=" SIZE_FORMAT "%s ",
902 byte_size_in_proper_unit(allocated_bytes),
903 proper_unit_for_byte_size(allocated_bytes)
904 );
905 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
906 }
907
908 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
909 osthread()->print_on(st);
910 }
911 ThreadsSMRSupport::print_info_on(this, st);
912 st->print(" ");
913 debug_only(if (WizardMode) print_owned_locks_on(st);)
914 }
915
916 // Thread::print_on_error() is called by fatal error handler. Don't use
917 // any lock or allocate memory.
918 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
919 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
920
921 if (is_VM_thread()) { st->print("VMThread"); }
922 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
923 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
924 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
925 else { st->print("Thread"); }
926
927 if (is_Named_thread()) {
928 st->print(" \"%s\"", name());
929 }
930
931 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
932 p2i(stack_end()), p2i(stack_base()));
933
934 if (osthread()) {
935 st->print(" [id=%d]", osthread()->thread_id());
936 }
937
938 ThreadsSMRSupport::print_info_on(this, st);
939 }
940
941 void Thread::print_value_on(outputStream* st) const {
942 if (is_Named_thread()) {
943 st->print(" \"%s\" ", name());
944 }
945 st->print(INTPTR_FORMAT, p2i(this)); // print address
946 }
947
948 #ifdef ASSERT
949 void Thread::print_owned_locks_on(outputStream* st) const {
950 Monitor *cur = _owned_locks;
951 if (cur == NULL) {
952 st->print(" (no locks) ");
953 } else {
954 st->print_cr(" Locks owned:");
955 while (cur) {
956 cur->print_on(st);
957 cur = cur->next();
958 }
959 }
960 }
961
962 static int ref_use_count = 0;
963
964 bool Thread::owns_locks_but_compiled_lock() const {
965 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
966 if (cur != Compile_lock) return true;
967 }
968 return false;
969 }
970
971
972 #endif
973
974 #ifndef PRODUCT
975
976 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
977 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
978 // no locks which allow_vm_block's are held
979 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
980 // Check if current thread is allowed to block at a safepoint
981 if (!(_allow_safepoint_count == 0)) {
982 fatal("Possible safepoint reached by thread that does not allow it");
983 }
984 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
985 fatal("LEAF method calling lock?");
986 }
987
988 #ifdef ASSERT
989 if (potential_vm_operation && is_Java_thread()
990 && !Universe::is_bootstrapping()) {
991 // Make sure we do not hold any locks that the VM thread also uses.
992 // This could potentially lead to deadlocks
993 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
994 // Threads_lock is special, since the safepoint synchronization will not start before this is
995 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
996 // since it is used to transfer control between JavaThreads and the VMThread
997 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
998 if ((cur->allow_vm_block() &&
999 cur != Threads_lock &&
1000 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1001 cur != VMOperationRequest_lock &&
1002 cur != VMOperationQueue_lock) ||
1003 cur->rank() == Mutex::special) {
1004 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1005 }
1006 }
1007 }
1008
1009 if (GCALotAtAllSafepoints) {
1010 // We could enter a safepoint here and thus have a gc
1011 InterfaceSupport::check_gc_alot();
1012 }
1013 #endif
1014 }
1015 #endif
1016
1017 bool Thread::is_in_stack(address adr) const {
1018 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1019 address end = os::current_stack_pointer();
1020 // Allow non Java threads to call this without stack_base
1021 if (_stack_base == NULL) return true;
1022 if (stack_base() >= adr && adr >= end) return true;
1023
1024 return false;
1025 }
1026
1027 bool Thread::is_in_usable_stack(address adr) const {
1028 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1029 size_t usable_stack_size = _stack_size - stack_guard_size;
1030
1031 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1032 }
1033
1034
1035 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1036 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1037 // used for compilation in the future. If that change is made, the need for these methods
1038 // should be revisited, and they should be removed if possible.
1039
1040 bool Thread::is_lock_owned(address adr) const {
1041 return on_local_stack(adr);
1042 }
1043
1044 bool Thread::set_as_starting_thread() {
1045 // NOTE: this must be called inside the main thread.
1046 return os::create_main_thread((JavaThread*)this);
1047 }
1048
1049 static void initialize_class(Symbol* class_name, TRAPS) {
1050 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1051 InstanceKlass::cast(klass)->initialize(CHECK);
1052 }
1053
1054
1055 // Creates the initial ThreadGroup
1056 static Handle create_initial_thread_group(TRAPS) {
1057 Handle system_instance = JavaCalls::construct_new_instance(
1058 SystemDictionary::ThreadGroup_klass(),
1059 vmSymbols::void_method_signature(),
1060 CHECK_NH);
1061 Universe::set_system_thread_group(system_instance());
1062
1063 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1064 Handle main_instance = JavaCalls::construct_new_instance(
1065 SystemDictionary::ThreadGroup_klass(),
1066 vmSymbols::threadgroup_string_void_signature(),
1067 system_instance,
1068 string,
1069 CHECK_NH);
1070 return main_instance;
1071 }
1072
1073 // Creates the initial Thread
1074 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1075 TRAPS) {
1076 InstanceKlass* ik = SystemDictionary::Thread_klass();
1077 assert(ik->is_initialized(), "must be");
1078 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1079
1080 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1081 // constructor calls Thread.current(), which must be set here for the
1082 // initial thread.
1083 java_lang_Thread::set_thread(thread_oop(), thread);
1084 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1085 thread->set_threadObj(thread_oop());
1086
1087 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1088
1089 JavaValue result(T_VOID);
1090 JavaCalls::call_special(&result, thread_oop,
1091 ik,
1092 vmSymbols::object_initializer_name(),
1093 vmSymbols::threadgroup_string_void_signature(),
1094 thread_group,
1095 string,
1096 CHECK_NULL);
1097 return thread_oop();
1098 }
1099
1100 char java_runtime_name[128] = "";
1101 char java_runtime_version[128] = "";
1102
1103 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1104 static const char* get_java_runtime_name(TRAPS) {
1105 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1106 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1107 fieldDescriptor fd;
1108 bool found = k != NULL &&
1109 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1110 vmSymbols::string_signature(), &fd);
1111 if (found) {
1112 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1113 if (name_oop == NULL) {
1114 return NULL;
1115 }
1116 const char* name = java_lang_String::as_utf8_string(name_oop,
1117 java_runtime_name,
1118 sizeof(java_runtime_name));
1119 return name;
1120 } else {
1121 return NULL;
1122 }
1123 }
1124
1125 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1126 static const char* get_java_runtime_version(TRAPS) {
1127 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1128 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1129 fieldDescriptor fd;
1130 bool found = k != NULL &&
1131 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1132 vmSymbols::string_signature(), &fd);
1133 if (found) {
1134 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1135 if (name_oop == NULL) {
1136 return NULL;
1137 }
1138 const char* name = java_lang_String::as_utf8_string(name_oop,
1139 java_runtime_version,
1140 sizeof(java_runtime_version));
1141 return name;
1142 } else {
1143 return NULL;
1144 }
1145 }
1146
1147 // General purpose hook into Java code, run once when the VM is initialized.
1148 // The Java library method itself may be changed independently from the VM.
1149 static void call_postVMInitHook(TRAPS) {
1150 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1151 if (klass != NULL) {
1152 JavaValue result(T_VOID);
1153 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1154 vmSymbols::void_method_signature(),
1155 CHECK);
1156 }
1157 }
1158
1159 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1160 bool daemon, TRAPS) {
1161 assert(thread_group.not_null(), "thread group should be specified");
1162 assert(threadObj() == NULL, "should only create Java thread object once");
1163
1164 InstanceKlass* ik = SystemDictionary::Thread_klass();
1165 assert(ik->is_initialized(), "must be");
1166 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1167
1168 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1169 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1170 // constructor calls Thread.current(), which must be set here.
1171 java_lang_Thread::set_thread(thread_oop(), this);
1172 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1173 set_threadObj(thread_oop());
1174
1175 JavaValue result(T_VOID);
1176 if (thread_name != NULL) {
1177 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1178 // Thread gets assigned specified name and null target
1179 JavaCalls::call_special(&result,
1180 thread_oop,
1181 ik,
1182 vmSymbols::object_initializer_name(),
1183 vmSymbols::threadgroup_string_void_signature(),
1184 thread_group,
1185 name,
1186 THREAD);
1187 } else {
1188 // Thread gets assigned name "Thread-nnn" and null target
1189 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1190 JavaCalls::call_special(&result,
1191 thread_oop,
1192 ik,
1193 vmSymbols::object_initializer_name(),
1194 vmSymbols::threadgroup_runnable_void_signature(),
1195 thread_group,
1196 Handle(),
1197 THREAD);
1198 }
1199
1200
1201 if (daemon) {
1202 java_lang_Thread::set_daemon(thread_oop());
1203 }
1204
1205 if (HAS_PENDING_EXCEPTION) {
1206 return;
1207 }
1208
1209 Klass* group = SystemDictionary::ThreadGroup_klass();
1210 Handle threadObj(THREAD, this->threadObj());
1211
1212 JavaCalls::call_special(&result,
1213 thread_group,
1214 group,
1215 vmSymbols::add_method_name(),
1216 vmSymbols::thread_void_signature(),
1217 threadObj, // Arg 1
1218 THREAD);
1219 }
1220
1221 // List of all NonJavaThreads and safe iteration over that list.
1222
1223 class NonJavaThread::List {
1224 public:
1225 NonJavaThread* volatile _head;
1226 SingleWriterSynchronizer _protect;
1227
1228 List() : _head(NULL), _protect() {}
1229 };
1230
1231 NonJavaThread::List NonJavaThread::_the_list;
1232
1233 NonJavaThread::Iterator::Iterator() :
1234 _protect_enter(_the_list._protect.enter()),
1235 _current(OrderAccess::load_acquire(&_the_list._head))
1236 {}
1237
1238 NonJavaThread::Iterator::~Iterator() {
1239 _the_list._protect.exit(_protect_enter);
1240 }
1241
1242 void NonJavaThread::Iterator::step() {
1243 assert(!end(), "precondition");
1244 _current = OrderAccess::load_acquire(&_current->_next);
1245 }
1246
1247 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1248 // Add this thread to _the_list.
1249 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1250 _next = _the_list._head;
1251 OrderAccess::release_store(&_the_list._head, this);
1252 }
1253
1254 NonJavaThread::~NonJavaThread() {
1255 // Remove this thread from _the_list.
1256 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1257 NonJavaThread* volatile* p = &_the_list._head;
1258 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1259 if (t == this) {
1260 *p = this->_next;
1261 // Wait for any in-progress iterators.
1262 _the_list._protect.synchronize();
1263 break;
1264 }
1265 }
1266 }
1267
1268 // NamedThread -- non-JavaThread subclasses with multiple
1269 // uniquely named instances should derive from this.
1270 NamedThread::NamedThread() :
1271 NonJavaThread(),
1272 _name(NULL),
1273 _processed_thread(NULL),
1274 _gc_id(GCId::undefined())
1275 {}
1276
1277 NamedThread::~NamedThread() {
1278 if (_name != NULL) {
1279 FREE_C_HEAP_ARRAY(char, _name);
1280 _name = NULL;
1281 }
1282 }
1283
1284 void NamedThread::set_name(const char* format, ...) {
1285 guarantee(_name == NULL, "Only get to set name once.");
1286 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1287 guarantee(_name != NULL, "alloc failure");
1288 va_list ap;
1289 va_start(ap, format);
1290 jio_vsnprintf(_name, max_name_len, format, ap);
1291 va_end(ap);
1292 }
1293
1294 void NamedThread::initialize_named_thread() {
1295 set_native_thread_name(name());
1296 }
1297
1298 void NamedThread::print_on(outputStream* st) const {
1299 st->print("\"%s\" ", name());
1300 Thread::print_on(st);
1301 st->cr();
1302 }
1303
1304
1305 // ======= WatcherThread ========
1306
1307 // The watcher thread exists to simulate timer interrupts. It should
1308 // be replaced by an abstraction over whatever native support for
1309 // timer interrupts exists on the platform.
1310
1311 WatcherThread* WatcherThread::_watcher_thread = NULL;
1312 bool WatcherThread::_startable = false;
1313 volatile bool WatcherThread::_should_terminate = false;
1314
1315 WatcherThread::WatcherThread() : NonJavaThread() {
1316 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1317 if (os::create_thread(this, os::watcher_thread)) {
1318 _watcher_thread = this;
1319
1320 // Set the watcher thread to the highest OS priority which should not be
1321 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1322 // is created. The only normal thread using this priority is the reference
1323 // handler thread, which runs for very short intervals only.
1324 // If the VMThread's priority is not lower than the WatcherThread profiling
1325 // will be inaccurate.
1326 os::set_priority(this, MaxPriority);
1327 if (!DisableStartThread) {
1328 os::start_thread(this);
1329 }
1330 }
1331 }
1332
1333 int WatcherThread::sleep() const {
1334 // The WatcherThread does not participate in the safepoint protocol
1335 // for the PeriodicTask_lock because it is not a JavaThread.
1336 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1337
1338 if (_should_terminate) {
1339 // check for termination before we do any housekeeping or wait
1340 return 0; // we did not sleep.
1341 }
1342
1343 // remaining will be zero if there are no tasks,
1344 // causing the WatcherThread to sleep until a task is
1345 // enrolled
1346 int remaining = PeriodicTask::time_to_wait();
1347 int time_slept = 0;
1348
1349 // we expect this to timeout - we only ever get unparked when
1350 // we should terminate or when a new task has been enrolled
1351 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1352
1353 jlong time_before_loop = os::javaTimeNanos();
1354
1355 while (true) {
1356 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1357 remaining);
1358 jlong now = os::javaTimeNanos();
1359
1360 if (remaining == 0) {
1361 // if we didn't have any tasks we could have waited for a long time
1362 // consider the time_slept zero and reset time_before_loop
1363 time_slept = 0;
1364 time_before_loop = now;
1365 } else {
1366 // need to recalculate since we might have new tasks in _tasks
1367 time_slept = (int) ((now - time_before_loop) / 1000000);
1368 }
1369
1370 // Change to task list or spurious wakeup of some kind
1371 if (timedout || _should_terminate) {
1372 break;
1373 }
1374
1375 remaining = PeriodicTask::time_to_wait();
1376 if (remaining == 0) {
1377 // Last task was just disenrolled so loop around and wait until
1378 // another task gets enrolled
1379 continue;
1380 }
1381
1382 remaining -= time_slept;
1383 if (remaining <= 0) {
1384 break;
1385 }
1386 }
1387
1388 return time_slept;
1389 }
1390
1391 void WatcherThread::run() {
1392 assert(this == watcher_thread(), "just checking");
1393
1394 this->set_native_thread_name(this->name());
1395 this->set_active_handles(JNIHandleBlock::allocate_block());
1396 while (true) {
1397 assert(watcher_thread() == Thread::current(), "thread consistency check");
1398 assert(watcher_thread() == this, "thread consistency check");
1399
1400 // Calculate how long it'll be until the next PeriodicTask work
1401 // should be done, and sleep that amount of time.
1402 int time_waited = sleep();
1403
1404 if (VMError::is_error_reported()) {
1405 // A fatal error has happened, the error handler(VMError::report_and_die)
1406 // should abort JVM after creating an error log file. However in some
1407 // rare cases, the error handler itself might deadlock. Here periodically
1408 // check for error reporting timeouts, and if it happens, just proceed to
1409 // abort the VM.
1410
1411 // This code is in WatcherThread because WatcherThread wakes up
1412 // periodically so the fatal error handler doesn't need to do anything;
1413 // also because the WatcherThread is less likely to crash than other
1414 // threads.
1415
1416 for (;;) {
1417 // Note: we use naked sleep in this loop because we want to avoid using
1418 // any kind of VM infrastructure which may be broken at this point.
1419 if (VMError::check_timeout()) {
1420 // We hit error reporting timeout. Error reporting was interrupted and
1421 // will be wrapping things up now (closing files etc). Give it some more
1422 // time, then quit the VM.
1423 os::naked_short_sleep(200);
1424 // Print a message to stderr.
1425 fdStream err(defaultStream::output_fd());
1426 err.print_raw_cr("# [ timer expired, abort... ]");
1427 // skip atexit/vm_exit/vm_abort hooks
1428 os::die();
1429 }
1430
1431 // Wait a second, then recheck for timeout.
1432 os::naked_short_sleep(999);
1433 }
1434 }
1435
1436 if (_should_terminate) {
1437 // check for termination before posting the next tick
1438 break;
1439 }
1440
1441 PeriodicTask::real_time_tick(time_waited);
1442 }
1443
1444 // Signal that it is terminated
1445 {
1446 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1447 _watcher_thread = NULL;
1448 Terminator_lock->notify();
1449 }
1450 }
1451
1452 void WatcherThread::start() {
1453 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1454
1455 if (watcher_thread() == NULL && _startable) {
1456 _should_terminate = false;
1457 // Create the single instance of WatcherThread
1458 new WatcherThread();
1459 }
1460 }
1461
1462 void WatcherThread::make_startable() {
1463 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1464 _startable = true;
1465 }
1466
1467 void WatcherThread::stop() {
1468 {
1469 // Follow normal safepoint aware lock enter protocol since the
1470 // WatcherThread is stopped by another JavaThread.
1471 MutexLocker ml(PeriodicTask_lock);
1472 _should_terminate = true;
1473
1474 WatcherThread* watcher = watcher_thread();
1475 if (watcher != NULL) {
1476 // unpark the WatcherThread so it can see that it should terminate
1477 watcher->unpark();
1478 }
1479 }
1480
1481 MutexLocker mu(Terminator_lock);
1482
1483 while (watcher_thread() != NULL) {
1484 // This wait should make safepoint checks, wait without a timeout,
1485 // and wait as a suspend-equivalent condition.
1486 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1487 Mutex::_as_suspend_equivalent_flag);
1488 }
1489 }
1490
1491 void WatcherThread::unpark() {
1492 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1493 PeriodicTask_lock->notify();
1494 }
1495
1496 void WatcherThread::print_on(outputStream* st) const {
1497 st->print("\"%s\" ", name());
1498 Thread::print_on(st);
1499 st->cr();
1500 }
1501
1502 // ======= JavaThread ========
1503
1504 #if INCLUDE_JVMCI
1505
1506 jlong* JavaThread::_jvmci_old_thread_counters;
1507
1508 bool jvmci_counters_include(JavaThread* thread) {
1509 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1510 }
1511
1512 void JavaThread::collect_counters(typeArrayOop array) {
1513 if (JVMCICounterSize > 0) {
1514 JavaThreadIteratorWithHandle jtiwh;
1515 for (int i = 0; i < array->length(); i++) {
1516 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1517 }
1518 for (; JavaThread *tp = jtiwh.next(); ) {
1519 if (jvmci_counters_include(tp)) {
1520 for (int i = 0; i < array->length(); i++) {
1521 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1522 }
1523 }
1524 }
1525 }
1526 }
1527
1528 #endif // INCLUDE_JVMCI
1529
1530 // A JavaThread is a normal Java thread
1531
1532 void JavaThread::initialize() {
1533 // Initialize fields
1534
1535 set_saved_exception_pc(NULL);
1536 set_threadObj(NULL);
1537 _anchor.clear();
1538 set_entry_point(NULL);
1539 set_jni_functions(jni_functions());
1540 set_callee_target(NULL);
1541 set_vm_result(NULL);
1542 set_vm_result_2(NULL);
1543 set_vframe_array_head(NULL);
1544 set_vframe_array_last(NULL);
1545 set_deferred_locals(NULL);
1546 set_deopt_mark(NULL);
1547 set_deopt_compiled_method(NULL);
1548 clear_must_deopt_id();
1549 set_monitor_chunks(NULL);
1550 set_next(NULL);
1551 _on_thread_list = false;
1552 set_thread_state(_thread_new);
1553 _terminated = _not_terminated;
1554 _privileged_stack_top = NULL;
1555 _array_for_gc = NULL;
1556 _suspend_equivalent = false;
1557 _in_deopt_handler = 0;
1558 _doing_unsafe_access = false;
1559 _stack_guard_state = stack_guard_unused;
1560 #if INCLUDE_JVMCI
1561 _pending_monitorenter = false;
1562 _pending_deoptimization = -1;
1563 _pending_failed_speculation = 0;
1564 _pending_transfer_to_interpreter = false;
1565 _adjusting_comp_level = false;
1566 _in_retryable_allocation = false;
1567 _jvmci._alternate_call_target = NULL;
1568 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1569 if (JVMCICounterSize > 0) {
1570 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1571 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1572 } else {
1573 _jvmci_counters = NULL;
1574 }
1575 #endif // INCLUDE_JVMCI
1576 _reserved_stack_activation = NULL; // stack base not known yet
1577 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1578 _exception_pc = 0;
1579 _exception_handler_pc = 0;
1580 _is_method_handle_return = 0;
1581 _jvmti_thread_state= NULL;
1582 _should_post_on_exceptions_flag = JNI_FALSE;
1583 _interp_only_mode = 0;
1584 _special_runtime_exit_condition = _no_async_condition;
1585 _pending_async_exception = NULL;
1586 _thread_stat = NULL;
1587 _thread_stat = new ThreadStatistics();
1588 _blocked_on_compilation = false;
1589 _jni_active_critical = 0;
1590 _pending_jni_exception_check_fn = NULL;
1591 _do_not_unlock_if_synchronized = false;
1592 _cached_monitor_info = NULL;
1593 _parker = Parker::Allocate(this);
1594
1595 #ifndef PRODUCT
1596 _jmp_ring_index = 0;
1597 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1598 record_jump(NULL, NULL, NULL, 0);
1599 }
1600 #endif // PRODUCT
1601
1602 // Setup safepoint state info for this thread
1603 ThreadSafepointState::create(this);
1604
1605 debug_only(_java_call_counter = 0);
1606
1607 // JVMTI PopFrame support
1608 _popframe_condition = popframe_inactive;
1609 _popframe_preserved_args = NULL;
1610 _popframe_preserved_args_size = 0;
1611 _frames_to_pop_failed_realloc = 0;
1612
1613 if (SafepointMechanism::uses_thread_local_poll()) {
1614 SafepointMechanism::initialize_header(this);
1615 }
1616
1617 pd_initialize();
1618 }
1619
1620 JavaThread::JavaThread(bool is_attaching_via_jni) :
1621 Thread() {
1622 initialize();
1623 if (is_attaching_via_jni) {
1624 _jni_attach_state = _attaching_via_jni;
1625 } else {
1626 _jni_attach_state = _not_attaching_via_jni;
1627 }
1628 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1629 }
1630
1631 bool JavaThread::reguard_stack(address cur_sp) {
1632 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1633 && _stack_guard_state != stack_guard_reserved_disabled) {
1634 return true; // Stack already guarded or guard pages not needed.
1635 }
1636
1637 if (register_stack_overflow()) {
1638 // For those architectures which have separate register and
1639 // memory stacks, we must check the register stack to see if
1640 // it has overflowed.
1641 return false;
1642 }
1643
1644 // Java code never executes within the yellow zone: the latter is only
1645 // there to provoke an exception during stack banging. If java code
1646 // is executing there, either StackShadowPages should be larger, or
1647 // some exception code in c1, c2 or the interpreter isn't unwinding
1648 // when it should.
1649 guarantee(cur_sp > stack_reserved_zone_base(),
1650 "not enough space to reguard - increase StackShadowPages");
1651 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1652 enable_stack_yellow_reserved_zone();
1653 if (reserved_stack_activation() != stack_base()) {
1654 set_reserved_stack_activation(stack_base());
1655 }
1656 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1657 set_reserved_stack_activation(stack_base());
1658 enable_stack_reserved_zone();
1659 }
1660 return true;
1661 }
1662
1663 bool JavaThread::reguard_stack(void) {
1664 return reguard_stack(os::current_stack_pointer());
1665 }
1666
1667
1668 void JavaThread::block_if_vm_exited() {
1669 if (_terminated == _vm_exited) {
1670 // _vm_exited is set at safepoint, and Threads_lock is never released
1671 // we will block here forever
1672 Threads_lock->lock_without_safepoint_check();
1673 ShouldNotReachHere();
1674 }
1675 }
1676
1677
1678 // Remove this ifdef when C1 is ported to the compiler interface.
1679 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1680 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1681
1682 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1683 Thread() {
1684 initialize();
1685 _jni_attach_state = _not_attaching_via_jni;
1686 set_entry_point(entry_point);
1687 // Create the native thread itself.
1688 // %note runtime_23
1689 os::ThreadType thr_type = os::java_thread;
1690 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1691 os::java_thread;
1692 os::create_thread(this, thr_type, stack_sz);
1693 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1694 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1695 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1696 // the exception consists of creating the exception object & initializing it, initialization
1697 // will leave the VM via a JavaCall and then all locks must be unlocked).
1698 //
1699 // The thread is still suspended when we reach here. Thread must be explicit started
1700 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1701 // by calling Threads:add. The reason why this is not done here, is because the thread
1702 // object must be fully initialized (take a look at JVM_Start)
1703 }
1704
1705 JavaThread::~JavaThread() {
1706
1707 // JSR166 -- return the parker to the free list
1708 Parker::Release(_parker);
1709 _parker = NULL;
1710
1711 // Free any remaining previous UnrollBlock
1712 vframeArray* old_array = vframe_array_last();
1713
1714 if (old_array != NULL) {
1715 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1716 old_array->set_unroll_block(NULL);
1717 delete old_info;
1718 delete old_array;
1719 }
1720
1721 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1722 if (deferred != NULL) {
1723 // This can only happen if thread is destroyed before deoptimization occurs.
1724 assert(deferred->length() != 0, "empty array!");
1725 do {
1726 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1727 deferred->remove_at(0);
1728 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1729 delete dlv;
1730 } while (deferred->length() != 0);
1731 delete deferred;
1732 }
1733
1734 // All Java related clean up happens in exit
1735 ThreadSafepointState::destroy(this);
1736 if (_thread_stat != NULL) delete _thread_stat;
1737
1738 #if INCLUDE_JVMCI
1739 if (JVMCICounterSize > 0) {
1740 if (jvmci_counters_include(this)) {
1741 for (int i = 0; i < JVMCICounterSize; i++) {
1742 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1743 }
1744 }
1745 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1746 }
1747 #endif // INCLUDE_JVMCI
1748 }
1749
1750
1751 // The first routine called by a new Java thread
1752 void JavaThread::run() {
1753 // initialize thread-local alloc buffer related fields
1754 this->initialize_tlab();
1755
1756 // used to test validity of stack trace backs
1757 this->record_base_of_stack_pointer();
1758
1759 this->create_stack_guard_pages();
1760
1761 this->cache_global_variables();
1762
1763 // Thread is now sufficient initialized to be handled by the safepoint code as being
1764 // in the VM. Change thread state from _thread_new to _thread_in_vm
1765 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1766
1767 assert(JavaThread::current() == this, "sanity check");
1768 assert(!Thread::current()->owns_locks(), "sanity check");
1769
1770 DTRACE_THREAD_PROBE(start, this);
1771
1772 // This operation might block. We call that after all safepoint checks for a new thread has
1773 // been completed.
1774 this->set_active_handles(JNIHandleBlock::allocate_block());
1775
1776 if (JvmtiExport::should_post_thread_life()) {
1777 JvmtiExport::post_thread_start(this);
1778 }
1779
1780 EventThreadStart event;
1781 if (event.should_commit()) {
1782 event.set_thread(JFR_THREAD_ID(this));
1783 event.commit();
1784 }
1785
1786 // We call another function to do the rest so we are sure that the stack addresses used
1787 // from there will be lower than the stack base just computed
1788 thread_main_inner();
1789
1790 // Note, thread is no longer valid at this point!
1791 }
1792
1793
1794 void JavaThread::thread_main_inner() {
1795 assert(JavaThread::current() == this, "sanity check");
1796 assert(this->threadObj() != NULL, "just checking");
1797
1798 // Execute thread entry point unless this thread has a pending exception
1799 // or has been stopped before starting.
1800 // Note: Due to JVM_StopThread we can have pending exceptions already!
1801 if (!this->has_pending_exception() &&
1802 !java_lang_Thread::is_stillborn(this->threadObj())) {
1803 {
1804 ResourceMark rm(this);
1805 this->set_native_thread_name(this->get_thread_name());
1806 }
1807 HandleMark hm(this);
1808 this->entry_point()(this, this);
1809 }
1810
1811 DTRACE_THREAD_PROBE(stop, this);
1812
1813 this->exit(false);
1814 this->smr_delete();
1815 }
1816
1817
1818 static void ensure_join(JavaThread* thread) {
1819 // We do not need to grab the Threads_lock, since we are operating on ourself.
1820 Handle threadObj(thread, thread->threadObj());
1821 assert(threadObj.not_null(), "java thread object must exist");
1822 ObjectLocker lock(threadObj, thread);
1823 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1824 thread->clear_pending_exception();
1825 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1826 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1827 // Clear the native thread instance - this makes isAlive return false and allows the join()
1828 // to complete once we've done the notify_all below
1829 java_lang_Thread::set_thread(threadObj(), NULL);
1830 lock.notify_all(thread);
1831 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1832 thread->clear_pending_exception();
1833 }
1834
1835
1836 // For any new cleanup additions, please check to see if they need to be applied to
1837 // cleanup_failed_attach_current_thread as well.
1838 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1839 assert(this == JavaThread::current(), "thread consistency check");
1840
1841 elapsedTimer _timer_exit_phase1;
1842 elapsedTimer _timer_exit_phase2;
1843 elapsedTimer _timer_exit_phase3;
1844 elapsedTimer _timer_exit_phase4;
1845
1846 if (log_is_enabled(Debug, os, thread, timer)) {
1847 _timer_exit_phase1.start();
1848 }
1849
1850 HandleMark hm(this);
1851 Handle uncaught_exception(this, this->pending_exception());
1852 this->clear_pending_exception();
1853 Handle threadObj(this, this->threadObj());
1854 assert(threadObj.not_null(), "Java thread object should be created");
1855
1856 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1857 {
1858 EXCEPTION_MARK;
1859
1860 CLEAR_PENDING_EXCEPTION;
1861 }
1862 if (!destroy_vm) {
1863 if (uncaught_exception.not_null()) {
1864 EXCEPTION_MARK;
1865 // Call method Thread.dispatchUncaughtException().
1866 Klass* thread_klass = SystemDictionary::Thread_klass();
1867 JavaValue result(T_VOID);
1868 JavaCalls::call_virtual(&result,
1869 threadObj, thread_klass,
1870 vmSymbols::dispatchUncaughtException_name(),
1871 vmSymbols::throwable_void_signature(),
1872 uncaught_exception,
1873 THREAD);
1874 if (HAS_PENDING_EXCEPTION) {
1875 ResourceMark rm(this);
1876 jio_fprintf(defaultStream::error_stream(),
1877 "\nException: %s thrown from the UncaughtExceptionHandler"
1878 " in thread \"%s\"\n",
1879 pending_exception()->klass()->external_name(),
1880 get_thread_name());
1881 CLEAR_PENDING_EXCEPTION;
1882 }
1883 }
1884
1885 // Called before the java thread exit since we want to read info
1886 // from java_lang_Thread object
1887 EventThreadEnd event;
1888 if (event.should_commit()) {
1889 event.set_thread(JFR_THREAD_ID(this));
1890 event.commit();
1891 }
1892
1893 // Call after last event on thread
1894 JFR_ONLY(Jfr::on_thread_exit(this);)
1895
1896 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1897 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1898 // is deprecated anyhow.
1899 if (!is_Compiler_thread()) {
1900 int count = 3;
1901 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1902 EXCEPTION_MARK;
1903 JavaValue result(T_VOID);
1904 Klass* thread_klass = SystemDictionary::Thread_klass();
1905 JavaCalls::call_virtual(&result,
1906 threadObj, thread_klass,
1907 vmSymbols::exit_method_name(),
1908 vmSymbols::void_method_signature(),
1909 THREAD);
1910 CLEAR_PENDING_EXCEPTION;
1911 }
1912 }
1913 // notify JVMTI
1914 if (JvmtiExport::should_post_thread_life()) {
1915 JvmtiExport::post_thread_end(this);
1916 }
1917
1918 // We have notified the agents that we are exiting, before we go on,
1919 // we must check for a pending external suspend request and honor it
1920 // in order to not surprise the thread that made the suspend request.
1921 while (true) {
1922 {
1923 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1924 if (!is_external_suspend()) {
1925 set_terminated(_thread_exiting);
1926 ThreadService::current_thread_exiting(this);
1927 break;
1928 }
1929 // Implied else:
1930 // Things get a little tricky here. We have a pending external
1931 // suspend request, but we are holding the SR_lock so we
1932 // can't just self-suspend. So we temporarily drop the lock
1933 // and then self-suspend.
1934 }
1935
1936 ThreadBlockInVM tbivm(this);
1937 java_suspend_self();
1938
1939 // We're done with this suspend request, but we have to loop around
1940 // and check again. Eventually we will get SR_lock without a pending
1941 // external suspend request and will be able to mark ourselves as
1942 // exiting.
1943 }
1944 // no more external suspends are allowed at this point
1945 } else {
1946 // before_exit() has already posted JVMTI THREAD_END events
1947 }
1948
1949 if (log_is_enabled(Debug, os, thread, timer)) {
1950 _timer_exit_phase1.stop();
1951 _timer_exit_phase2.start();
1952 }
1953 // Notify waiters on thread object. This has to be done after exit() is called
1954 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1955 // group should have the destroyed bit set before waiters are notified).
1956 ensure_join(this);
1957 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1958
1959 if (log_is_enabled(Debug, os, thread, timer)) {
1960 _timer_exit_phase2.stop();
1961 _timer_exit_phase3.start();
1962 }
1963 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1964 // held by this thread must be released. The spec does not distinguish
1965 // between JNI-acquired and regular Java monitors. We can only see
1966 // regular Java monitors here if monitor enter-exit matching is broken.
1967 //
1968 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1969 // ObjectSynchronizer::release_monitors_owned_by_thread().
1970 if (exit_type == jni_detach) {
1971 // Sanity check even though JNI DetachCurrentThread() would have
1972 // returned JNI_ERR if there was a Java frame. JavaThread exit
1973 // should be done executing Java code by the time we get here.
1974 assert(!this->has_last_Java_frame(),
1975 "should not have a Java frame when detaching or exiting");
1976 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1977 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1978 }
1979
1980 // These things needs to be done while we are still a Java Thread. Make sure that thread
1981 // is in a consistent state, in case GC happens
1982 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1983
1984 if (active_handles() != NULL) {
1985 JNIHandleBlock* block = active_handles();
1986 set_active_handles(NULL);
1987 JNIHandleBlock::release_block(block);
1988 }
1989
1990 if (free_handle_block() != NULL) {
1991 JNIHandleBlock* block = free_handle_block();
1992 set_free_handle_block(NULL);
1993 JNIHandleBlock::release_block(block);
1994 }
1995
1996 // These have to be removed while this is still a valid thread.
1997 remove_stack_guard_pages();
1998
1999 if (UseTLAB) {
2000 tlab().retire();
2001 }
2002
2003 if (JvmtiEnv::environments_might_exist()) {
2004 JvmtiExport::cleanup_thread(this);
2005 }
2006
2007 // We must flush any deferred card marks and other various GC barrier
2008 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2009 // before removing a thread from the list of active threads.
2010 BarrierSet::barrier_set()->on_thread_detach(this);
2011
2012 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2013 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2014 os::current_thread_id());
2015
2016 if (log_is_enabled(Debug, os, thread, timer)) {
2017 _timer_exit_phase3.stop();
2018 _timer_exit_phase4.start();
2019 }
2020 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2021 Threads::remove(this);
2022
2023 if (log_is_enabled(Debug, os, thread, timer)) {
2024 _timer_exit_phase4.stop();
2025 ResourceMark rm(this);
2026 log_debug(os, thread, timer)("name='%s'"
2027 ", exit-phase1=" JLONG_FORMAT
2028 ", exit-phase2=" JLONG_FORMAT
2029 ", exit-phase3=" JLONG_FORMAT
2030 ", exit-phase4=" JLONG_FORMAT,
2031 get_thread_name(),
2032 _timer_exit_phase1.milliseconds(),
2033 _timer_exit_phase2.milliseconds(),
2034 _timer_exit_phase3.milliseconds(),
2035 _timer_exit_phase4.milliseconds());
2036 }
2037 }
2038
2039 void JavaThread::cleanup_failed_attach_current_thread() {
2040 if (active_handles() != NULL) {
2041 JNIHandleBlock* block = active_handles();
2042 set_active_handles(NULL);
2043 JNIHandleBlock::release_block(block);
2044 }
2045
2046 if (free_handle_block() != NULL) {
2047 JNIHandleBlock* block = free_handle_block();
2048 set_free_handle_block(NULL);
2049 JNIHandleBlock::release_block(block);
2050 }
2051
2052 // These have to be removed while this is still a valid thread.
2053 remove_stack_guard_pages();
2054
2055 if (UseTLAB) {
2056 tlab().retire();
2057 }
2058
2059 BarrierSet::barrier_set()->on_thread_detach(this);
2060
2061 Threads::remove(this);
2062 this->smr_delete();
2063 }
2064
2065 JavaThread* JavaThread::active() {
2066 Thread* thread = Thread::current();
2067 if (thread->is_Java_thread()) {
2068 return (JavaThread*) thread;
2069 } else {
2070 assert(thread->is_VM_thread(), "this must be a vm thread");
2071 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2072 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2073 assert(ret->is_Java_thread(), "must be a Java thread");
2074 return ret;
2075 }
2076 }
2077
2078 bool JavaThread::is_lock_owned(address adr) const {
2079 if (Thread::is_lock_owned(adr)) return true;
2080
2081 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2082 if (chunk->contains(adr)) return true;
2083 }
2084
2085 return false;
2086 }
2087
2088
2089 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2090 chunk->set_next(monitor_chunks());
2091 set_monitor_chunks(chunk);
2092 }
2093
2094 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2095 guarantee(monitor_chunks() != NULL, "must be non empty");
2096 if (monitor_chunks() == chunk) {
2097 set_monitor_chunks(chunk->next());
2098 } else {
2099 MonitorChunk* prev = monitor_chunks();
2100 while (prev->next() != chunk) prev = prev->next();
2101 prev->set_next(chunk->next());
2102 }
2103 }
2104
2105 // JVM support.
2106
2107 // Note: this function shouldn't block if it's called in
2108 // _thread_in_native_trans state (such as from
2109 // check_special_condition_for_native_trans()).
2110 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2111
2112 if (has_last_Java_frame() && has_async_condition()) {
2113 // If we are at a polling page safepoint (not a poll return)
2114 // then we must defer async exception because live registers
2115 // will be clobbered by the exception path. Poll return is
2116 // ok because the call we a returning from already collides
2117 // with exception handling registers and so there is no issue.
2118 // (The exception handling path kills call result registers but
2119 // this is ok since the exception kills the result anyway).
2120
2121 if (is_at_poll_safepoint()) {
2122 // if the code we are returning to has deoptimized we must defer
2123 // the exception otherwise live registers get clobbered on the
2124 // exception path before deoptimization is able to retrieve them.
2125 //
2126 RegisterMap map(this, false);
2127 frame caller_fr = last_frame().sender(&map);
2128 assert(caller_fr.is_compiled_frame(), "what?");
2129 if (caller_fr.is_deoptimized_frame()) {
2130 log_info(exceptions)("deferred async exception at compiled safepoint");
2131 return;
2132 }
2133 }
2134 }
2135
2136 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2137 if (condition == _no_async_condition) {
2138 // Conditions have changed since has_special_runtime_exit_condition()
2139 // was called:
2140 // - if we were here only because of an external suspend request,
2141 // then that was taken care of above (or cancelled) so we are done
2142 // - if we were here because of another async request, then it has
2143 // been cleared between the has_special_runtime_exit_condition()
2144 // and now so again we are done
2145 return;
2146 }
2147
2148 // Check for pending async. exception
2149 if (_pending_async_exception != NULL) {
2150 // Only overwrite an already pending exception, if it is not a threadDeath.
2151 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2152
2153 // We cannot call Exceptions::_throw(...) here because we cannot block
2154 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2155
2156 LogTarget(Info, exceptions) lt;
2157 if (lt.is_enabled()) {
2158 ResourceMark rm;
2159 LogStream ls(lt);
2160 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2161 if (has_last_Java_frame()) {
2162 frame f = last_frame();
2163 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2164 }
2165 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2166 }
2167 _pending_async_exception = NULL;
2168 clear_has_async_exception();
2169 }
2170 }
2171
2172 if (check_unsafe_error &&
2173 condition == _async_unsafe_access_error && !has_pending_exception()) {
2174 condition = _no_async_condition; // done
2175 switch (thread_state()) {
2176 case _thread_in_vm: {
2177 JavaThread* THREAD = this;
2178 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2179 }
2180 case _thread_in_native: {
2181 ThreadInVMfromNative tiv(this);
2182 JavaThread* THREAD = this;
2183 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2184 }
2185 case _thread_in_Java: {
2186 ThreadInVMfromJava tiv(this);
2187 JavaThread* THREAD = this;
2188 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2189 }
2190 default:
2191 ShouldNotReachHere();
2192 }
2193 }
2194
2195 assert(condition == _no_async_condition || has_pending_exception() ||
2196 (!check_unsafe_error && condition == _async_unsafe_access_error),
2197 "must have handled the async condition, if no exception");
2198 }
2199
2200 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2201 //
2202 // Check for pending external suspend. Internal suspend requests do
2203 // not use handle_special_runtime_exit_condition().
2204 // If JNIEnv proxies are allowed, don't self-suspend if the target
2205 // thread is not the current thread. In older versions of jdbx, jdbx
2206 // threads could call into the VM with another thread's JNIEnv so we
2207 // can be here operating on behalf of a suspended thread (4432884).
2208 bool do_self_suspend = is_external_suspend_with_lock();
2209 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2210 //
2211 // Because thread is external suspended the safepoint code will count
2212 // thread as at a safepoint. This can be odd because we can be here
2213 // as _thread_in_Java which would normally transition to _thread_blocked
2214 // at a safepoint. We would like to mark the thread as _thread_blocked
2215 // before calling java_suspend_self like all other callers of it but
2216 // we must then observe proper safepoint protocol. (We can't leave
2217 // _thread_blocked with a safepoint in progress). However we can be
2218 // here as _thread_in_native_trans so we can't use a normal transition
2219 // constructor/destructor pair because they assert on that type of
2220 // transition. We could do something like:
2221 //
2222 // JavaThreadState state = thread_state();
2223 // set_thread_state(_thread_in_vm);
2224 // {
2225 // ThreadBlockInVM tbivm(this);
2226 // java_suspend_self()
2227 // }
2228 // set_thread_state(_thread_in_vm_trans);
2229 // if (safepoint) block;
2230 // set_thread_state(state);
2231 //
2232 // but that is pretty messy. Instead we just go with the way the
2233 // code has worked before and note that this is the only path to
2234 // java_suspend_self that doesn't put the thread in _thread_blocked
2235 // mode.
2236
2237 frame_anchor()->make_walkable(this);
2238 java_suspend_self();
2239
2240 // We might be here for reasons in addition to the self-suspend request
2241 // so check for other async requests.
2242 }
2243
2244 if (check_asyncs) {
2245 check_and_handle_async_exceptions();
2246 }
2247
2248 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2249 }
2250
2251 void JavaThread::send_thread_stop(oop java_throwable) {
2252 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2253 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2254 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2255
2256 // Do not throw asynchronous exceptions against the compiler thread
2257 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2258 if (!can_call_java()) return;
2259
2260 {
2261 // Actually throw the Throwable against the target Thread - however
2262 // only if there is no thread death exception installed already.
2263 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2264 // If the topmost frame is a runtime stub, then we are calling into
2265 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2266 // must deoptimize the caller before continuing, as the compiled exception handler table
2267 // may not be valid
2268 if (has_last_Java_frame()) {
2269 frame f = last_frame();
2270 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2271 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2272 RegisterMap reg_map(this, UseBiasedLocking);
2273 frame compiled_frame = f.sender(®_map);
2274 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2275 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2276 }
2277 }
2278 }
2279
2280 // Set async. pending exception in thread.
2281 set_pending_async_exception(java_throwable);
2282
2283 if (log_is_enabled(Info, exceptions)) {
2284 ResourceMark rm;
2285 log_info(exceptions)("Pending Async. exception installed of type: %s",
2286 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2287 }
2288 // for AbortVMOnException flag
2289 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2290 }
2291 }
2292
2293
2294 // Interrupt thread so it will wake up from a potential wait()
2295 Thread::interrupt(this);
2296 }
2297
2298 // External suspension mechanism.
2299 //
2300 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2301 // to any VM_locks and it is at a transition
2302 // Self-suspension will happen on the transition out of the vm.
2303 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2304 //
2305 // Guarantees on return:
2306 // + Target thread will not execute any new bytecode (that's why we need to
2307 // force a safepoint)
2308 // + Target thread will not enter any new monitors
2309 //
2310 void JavaThread::java_suspend() {
2311 ThreadsListHandle tlh;
2312 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2313 return;
2314 }
2315
2316 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2317 if (!is_external_suspend()) {
2318 // a racing resume has cancelled us; bail out now
2319 return;
2320 }
2321
2322 // suspend is done
2323 uint32_t debug_bits = 0;
2324 // Warning: is_ext_suspend_completed() may temporarily drop the
2325 // SR_lock to allow the thread to reach a stable thread state if
2326 // it is currently in a transient thread state.
2327 if (is_ext_suspend_completed(false /* !called_by_wait */,
2328 SuspendRetryDelay, &debug_bits)) {
2329 return;
2330 }
2331 }
2332
2333 VM_ThreadSuspend vm_suspend;
2334 VMThread::execute(&vm_suspend);
2335 }
2336
2337 // Part II of external suspension.
2338 // A JavaThread self suspends when it detects a pending external suspend
2339 // request. This is usually on transitions. It is also done in places
2340 // where continuing to the next transition would surprise the caller,
2341 // e.g., monitor entry.
2342 //
2343 // Returns the number of times that the thread self-suspended.
2344 //
2345 // Note: DO NOT call java_suspend_self() when you just want to block current
2346 // thread. java_suspend_self() is the second stage of cooperative
2347 // suspension for external suspend requests and should only be used
2348 // to complete an external suspend request.
2349 //
2350 int JavaThread::java_suspend_self() {
2351 int ret = 0;
2352
2353 // we are in the process of exiting so don't suspend
2354 if (is_exiting()) {
2355 clear_external_suspend();
2356 return ret;
2357 }
2358
2359 assert(_anchor.walkable() ||
2360 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2361 "must have walkable stack");
2362
2363 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2364
2365 assert(!this->is_ext_suspended(),
2366 "a thread trying to self-suspend should not already be suspended");
2367
2368 if (this->is_suspend_equivalent()) {
2369 // If we are self-suspending as a result of the lifting of a
2370 // suspend equivalent condition, then the suspend_equivalent
2371 // flag is not cleared until we set the ext_suspended flag so
2372 // that wait_for_ext_suspend_completion() returns consistent
2373 // results.
2374 this->clear_suspend_equivalent();
2375 }
2376
2377 // A racing resume may have cancelled us before we grabbed SR_lock
2378 // above. Or another external suspend request could be waiting for us
2379 // by the time we return from SR_lock()->wait(). The thread
2380 // that requested the suspension may already be trying to walk our
2381 // stack and if we return now, we can change the stack out from under
2382 // it. This would be a "bad thing (TM)" and cause the stack walker
2383 // to crash. We stay self-suspended until there are no more pending
2384 // external suspend requests.
2385 while (is_external_suspend()) {
2386 ret++;
2387 this->set_ext_suspended();
2388
2389 // _ext_suspended flag is cleared by java_resume()
2390 while (is_ext_suspended()) {
2391 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2392 }
2393 }
2394
2395 return ret;
2396 }
2397
2398 #ifdef ASSERT
2399 // Verify the JavaThread has not yet been published in the Threads::list, and
2400 // hence doesn't need protection from concurrent access at this stage.
2401 void JavaThread::verify_not_published() {
2402 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2403 // since an unpublished JavaThread doesn't participate in the
2404 // Thread-SMR protocol for keeping a ThreadsList alive.
2405 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2406 }
2407 #endif
2408
2409 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2410 // progress or when _suspend_flags is non-zero.
2411 // Current thread needs to self-suspend if there is a suspend request and/or
2412 // block if a safepoint is in progress.
2413 // Async exception ISN'T checked.
2414 // Note only the ThreadInVMfromNative transition can call this function
2415 // directly and when thread state is _thread_in_native_trans
2416 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2417 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2418
2419 JavaThread *curJT = JavaThread::current();
2420 bool do_self_suspend = thread->is_external_suspend();
2421
2422 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2423
2424 // If JNIEnv proxies are allowed, don't self-suspend if the target
2425 // thread is not the current thread. In older versions of jdbx, jdbx
2426 // threads could call into the VM with another thread's JNIEnv so we
2427 // can be here operating on behalf of a suspended thread (4432884).
2428 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2429 JavaThreadState state = thread->thread_state();
2430
2431 // We mark this thread_blocked state as a suspend-equivalent so
2432 // that a caller to is_ext_suspend_completed() won't be confused.
2433 // The suspend-equivalent state is cleared by java_suspend_self().
2434 thread->set_suspend_equivalent();
2435
2436 // If the safepoint code sees the _thread_in_native_trans state, it will
2437 // wait until the thread changes to other thread state. There is no
2438 // guarantee on how soon we can obtain the SR_lock and complete the
2439 // self-suspend request. It would be a bad idea to let safepoint wait for
2440 // too long. Temporarily change the state to _thread_blocked to
2441 // let the VM thread know that this thread is ready for GC. The problem
2442 // of changing thread state is that safepoint could happen just after
2443 // java_suspend_self() returns after being resumed, and VM thread will
2444 // see the _thread_blocked state. We must check for safepoint
2445 // after restoring the state and make sure we won't leave while a safepoint
2446 // is in progress.
2447 thread->set_thread_state(_thread_blocked);
2448 thread->java_suspend_self();
2449 thread->set_thread_state(state);
2450
2451 InterfaceSupport::serialize_thread_state_with_handler(thread);
2452 }
2453
2454 SafepointMechanism::block_if_requested(curJT);
2455
2456 if (thread->is_deopt_suspend()) {
2457 thread->clear_deopt_suspend();
2458 RegisterMap map(thread, false);
2459 frame f = thread->last_frame();
2460 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2461 f = f.sender(&map);
2462 }
2463 if (f.id() == thread->must_deopt_id()) {
2464 thread->clear_must_deopt_id();
2465 f.deoptimize(thread);
2466 } else {
2467 fatal("missed deoptimization!");
2468 }
2469 }
2470
2471 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2472 }
2473
2474 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2475 // progress or when _suspend_flags is non-zero.
2476 // Current thread needs to self-suspend if there is a suspend request and/or
2477 // block if a safepoint is in progress.
2478 // Also check for pending async exception (not including unsafe access error).
2479 // Note only the native==>VM/Java barriers can call this function and when
2480 // thread state is _thread_in_native_trans.
2481 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2482 check_safepoint_and_suspend_for_native_trans(thread);
2483
2484 if (thread->has_async_exception()) {
2485 // We are in _thread_in_native_trans state, don't handle unsafe
2486 // access error since that may block.
2487 thread->check_and_handle_async_exceptions(false);
2488 }
2489 }
2490
2491 // This is a variant of the normal
2492 // check_special_condition_for_native_trans with slightly different
2493 // semantics for use by critical native wrappers. It does all the
2494 // normal checks but also performs the transition back into
2495 // thread_in_Java state. This is required so that critical natives
2496 // can potentially block and perform a GC if they are the last thread
2497 // exiting the GCLocker.
2498 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2499 check_special_condition_for_native_trans(thread);
2500
2501 // Finish the transition
2502 thread->set_thread_state(_thread_in_Java);
2503
2504 if (thread->do_critical_native_unlock()) {
2505 ThreadInVMfromJavaNoAsyncException tiv(thread);
2506 GCLocker::unlock_critical(thread);
2507 thread->clear_critical_native_unlock();
2508 }
2509 }
2510
2511 // We need to guarantee the Threads_lock here, since resumes are not
2512 // allowed during safepoint synchronization
2513 // Can only resume from an external suspension
2514 void JavaThread::java_resume() {
2515 assert_locked_or_safepoint(Threads_lock);
2516
2517 // Sanity check: thread is gone, has started exiting or the thread
2518 // was not externally suspended.
2519 ThreadsListHandle tlh;
2520 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2521 return;
2522 }
2523
2524 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2525
2526 clear_external_suspend();
2527
2528 if (is_ext_suspended()) {
2529 clear_ext_suspended();
2530 SR_lock()->notify_all();
2531 }
2532 }
2533
2534 size_t JavaThread::_stack_red_zone_size = 0;
2535 size_t JavaThread::_stack_yellow_zone_size = 0;
2536 size_t JavaThread::_stack_reserved_zone_size = 0;
2537 size_t JavaThread::_stack_shadow_zone_size = 0;
2538
2539 void JavaThread::create_stack_guard_pages() {
2540 if (!os::uses_stack_guard_pages() ||
2541 _stack_guard_state != stack_guard_unused ||
2542 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2543 log_info(os, thread)("Stack guard page creation for thread "
2544 UINTX_FORMAT " disabled", os::current_thread_id());
2545 return;
2546 }
2547 address low_addr = stack_end();
2548 size_t len = stack_guard_zone_size();
2549
2550 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2551 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2552
2553 int must_commit = os::must_commit_stack_guard_pages();
2554 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2555
2556 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2557 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2558 return;
2559 }
2560
2561 if (os::guard_memory((char *) low_addr, len)) {
2562 _stack_guard_state = stack_guard_enabled;
2563 } else {
2564 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2565 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2566 if (os::uncommit_memory((char *) low_addr, len)) {
2567 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2568 }
2569 return;
2570 }
2571
2572 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2573 PTR_FORMAT "-" PTR_FORMAT ".",
2574 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2575 }
2576
2577 void JavaThread::remove_stack_guard_pages() {
2578 assert(Thread::current() == this, "from different thread");
2579 if (_stack_guard_state == stack_guard_unused) return;
2580 address low_addr = stack_end();
2581 size_t len = stack_guard_zone_size();
2582
2583 if (os::must_commit_stack_guard_pages()) {
2584 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2585 _stack_guard_state = stack_guard_unused;
2586 } else {
2587 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2588 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2589 return;
2590 }
2591 } else {
2592 if (_stack_guard_state == stack_guard_unused) return;
2593 if (os::unguard_memory((char *) low_addr, len)) {
2594 _stack_guard_state = stack_guard_unused;
2595 } else {
2596 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2597 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2598 return;
2599 }
2600 }
2601
2602 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2603 PTR_FORMAT "-" PTR_FORMAT ".",
2604 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2605 }
2606
2607 void JavaThread::enable_stack_reserved_zone() {
2608 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2609 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2610
2611 // The base notation is from the stack's point of view, growing downward.
2612 // We need to adjust it to work correctly with guard_memory()
2613 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2614
2615 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2616 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2617
2618 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2619 _stack_guard_state = stack_guard_enabled;
2620 } else {
2621 warning("Attempt to guard stack reserved zone failed.");
2622 }
2623 enable_register_stack_guard();
2624 }
2625
2626 void JavaThread::disable_stack_reserved_zone() {
2627 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2628 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2629
2630 // Simply return if called for a thread that does not use guard pages.
2631 if (_stack_guard_state == stack_guard_unused) return;
2632
2633 // The base notation is from the stack's point of view, growing downward.
2634 // We need to adjust it to work correctly with guard_memory()
2635 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2636
2637 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2638 _stack_guard_state = stack_guard_reserved_disabled;
2639 } else {
2640 warning("Attempt to unguard stack reserved zone failed.");
2641 }
2642 disable_register_stack_guard();
2643 }
2644
2645 void JavaThread::enable_stack_yellow_reserved_zone() {
2646 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2647 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2648
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 address base = stack_red_zone_base();
2652
2653 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2654 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2655
2656 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2657 _stack_guard_state = stack_guard_enabled;
2658 } else {
2659 warning("Attempt to guard stack yellow zone failed.");
2660 }
2661 enable_register_stack_guard();
2662 }
2663
2664 void JavaThread::disable_stack_yellow_reserved_zone() {
2665 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2666 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2667
2668 // Simply return if called for a thread that does not use guard pages.
2669 if (_stack_guard_state == stack_guard_unused) return;
2670
2671 // The base notation is from the stacks point of view, growing downward.
2672 // We need to adjust it to work correctly with guard_memory()
2673 address base = stack_red_zone_base();
2674
2675 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2676 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2677 } else {
2678 warning("Attempt to unguard stack yellow zone failed.");
2679 }
2680 disable_register_stack_guard();
2681 }
2682
2683 void JavaThread::enable_stack_red_zone() {
2684 // The base notation is from the stacks point of view, growing downward.
2685 // We need to adjust it to work correctly with guard_memory()
2686 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2687 address base = stack_red_zone_base() - stack_red_zone_size();
2688
2689 guarantee(base < stack_base(), "Error calculating stack red zone");
2690 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2691
2692 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2693 warning("Attempt to guard stack red zone failed.");
2694 }
2695 }
2696
2697 void JavaThread::disable_stack_red_zone() {
2698 // The base notation is from the stacks point of view, growing downward.
2699 // We need to adjust it to work correctly with guard_memory()
2700 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2701 address base = stack_red_zone_base() - stack_red_zone_size();
2702 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2703 warning("Attempt to unguard stack red zone failed.");
2704 }
2705 }
2706
2707 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2708 // ignore is there is no stack
2709 if (!has_last_Java_frame()) return;
2710 // traverse the stack frames. Starts from top frame.
2711 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2712 frame* fr = fst.current();
2713 f(fr, fst.register_map());
2714 }
2715 }
2716
2717
2718 #ifndef PRODUCT
2719 // Deoptimization
2720 // Function for testing deoptimization
2721 void JavaThread::deoptimize() {
2722 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2723 StackFrameStream fst(this, UseBiasedLocking);
2724 bool deopt = false; // Dump stack only if a deopt actually happens.
2725 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2726 // Iterate over all frames in the thread and deoptimize
2727 for (; !fst.is_done(); fst.next()) {
2728 if (fst.current()->can_be_deoptimized()) {
2729
2730 if (only_at) {
2731 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2732 // consists of comma or carriage return separated numbers so
2733 // search for the current bci in that string.
2734 address pc = fst.current()->pc();
2735 nmethod* nm = (nmethod*) fst.current()->cb();
2736 ScopeDesc* sd = nm->scope_desc_at(pc);
2737 char buffer[8];
2738 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2739 size_t len = strlen(buffer);
2740 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2741 while (found != NULL) {
2742 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2743 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2744 // Check that the bci found is bracketed by terminators.
2745 break;
2746 }
2747 found = strstr(found + 1, buffer);
2748 }
2749 if (!found) {
2750 continue;
2751 }
2752 }
2753
2754 if (DebugDeoptimization && !deopt) {
2755 deopt = true; // One-time only print before deopt
2756 tty->print_cr("[BEFORE Deoptimization]");
2757 trace_frames();
2758 trace_stack();
2759 }
2760 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2761 }
2762 }
2763
2764 if (DebugDeoptimization && deopt) {
2765 tty->print_cr("[AFTER Deoptimization]");
2766 trace_frames();
2767 }
2768 }
2769
2770
2771 // Make zombies
2772 void JavaThread::make_zombies() {
2773 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2774 if (fst.current()->can_be_deoptimized()) {
2775 // it is a Java nmethod
2776 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2777 nm->make_not_entrant();
2778 }
2779 }
2780 }
2781 #endif // PRODUCT
2782
2783
2784 void JavaThread::deoptimized_wrt_marked_nmethods() {
2785 if (!has_last_Java_frame()) return;
2786 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2787 StackFrameStream fst(this, UseBiasedLocking);
2788 for (; !fst.is_done(); fst.next()) {
2789 if (fst.current()->should_be_deoptimized()) {
2790 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2791 }
2792 }
2793 }
2794
2795
2796 // If the caller is a NamedThread, then remember, in the current scope,
2797 // the given JavaThread in its _processed_thread field.
2798 class RememberProcessedThread: public StackObj {
2799 NamedThread* _cur_thr;
2800 public:
2801 RememberProcessedThread(JavaThread* jthr) {
2802 Thread* thread = Thread::current();
2803 if (thread->is_Named_thread()) {
2804 _cur_thr = (NamedThread *)thread;
2805 _cur_thr->set_processed_thread(jthr);
2806 } else {
2807 _cur_thr = NULL;
2808 }
2809 }
2810
2811 ~RememberProcessedThread() {
2812 if (_cur_thr) {
2813 _cur_thr->set_processed_thread(NULL);
2814 }
2815 }
2816 };
2817
2818 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2819 // Verify that the deferred card marks have been flushed.
2820 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2821
2822 // Traverse the GCHandles
2823 Thread::oops_do(f, cf);
2824
2825 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2826 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2827
2828 if (has_last_Java_frame()) {
2829 // Record JavaThread to GC thread
2830 RememberProcessedThread rpt(this);
2831
2832 // Traverse the privileged stack
2833 if (_privileged_stack_top != NULL) {
2834 _privileged_stack_top->oops_do(f);
2835 }
2836
2837 // traverse the registered growable array
2838 if (_array_for_gc != NULL) {
2839 for (int index = 0; index < _array_for_gc->length(); index++) {
2840 f->do_oop(_array_for_gc->adr_at(index));
2841 }
2842 }
2843
2844 // Traverse the monitor chunks
2845 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2846 chunk->oops_do(f);
2847 }
2848
2849 // Traverse the execution stack
2850 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2851 fst.current()->oops_do(f, cf, fst.register_map());
2852 }
2853 }
2854
2855 // callee_target is never live across a gc point so NULL it here should
2856 // it still contain a methdOop.
2857
2858 set_callee_target(NULL);
2859
2860 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2861 // If we have deferred set_locals there might be oops waiting to be
2862 // written
2863 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2864 if (list != NULL) {
2865 for (int i = 0; i < list->length(); i++) {
2866 list->at(i)->oops_do(f);
2867 }
2868 }
2869
2870 // Traverse instance variables at the end since the GC may be moving things
2871 // around using this function
2872 f->do_oop((oop*) &_threadObj);
2873 f->do_oop((oop*) &_vm_result);
2874 f->do_oop((oop*) &_exception_oop);
2875 f->do_oop((oop*) &_pending_async_exception);
2876
2877 if (jvmti_thread_state() != NULL) {
2878 jvmti_thread_state()->oops_do(f);
2879 }
2880 }
2881
2882 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2883 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2884 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2885
2886 if (has_last_Java_frame()) {
2887 // Traverse the execution stack
2888 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2889 fst.current()->nmethods_do(cf);
2890 }
2891 }
2892 }
2893
2894 void JavaThread::metadata_do(void f(Metadata*)) {
2895 if (has_last_Java_frame()) {
2896 // Traverse the execution stack to call f() on the methods in the stack
2897 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2898 fst.current()->metadata_do(f);
2899 }
2900 } else if (is_Compiler_thread()) {
2901 // need to walk ciMetadata in current compile tasks to keep alive.
2902 CompilerThread* ct = (CompilerThread*)this;
2903 if (ct->env() != NULL) {
2904 ct->env()->metadata_do(f);
2905 }
2906 CompileTask* task = ct->task();
2907 if (task != NULL) {
2908 task->metadata_do(f);
2909 }
2910 }
2911 }
2912
2913 // Printing
2914 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2915 switch (_thread_state) {
2916 case _thread_uninitialized: return "_thread_uninitialized";
2917 case _thread_new: return "_thread_new";
2918 case _thread_new_trans: return "_thread_new_trans";
2919 case _thread_in_native: return "_thread_in_native";
2920 case _thread_in_native_trans: return "_thread_in_native_trans";
2921 case _thread_in_vm: return "_thread_in_vm";
2922 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2923 case _thread_in_Java: return "_thread_in_Java";
2924 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2925 case _thread_blocked: return "_thread_blocked";
2926 case _thread_blocked_trans: return "_thread_blocked_trans";
2927 default: return "unknown thread state";
2928 }
2929 }
2930
2931 #ifndef PRODUCT
2932 void JavaThread::print_thread_state_on(outputStream *st) const {
2933 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2934 };
2935 void JavaThread::print_thread_state() const {
2936 print_thread_state_on(tty);
2937 }
2938 #endif // PRODUCT
2939
2940 // Called by Threads::print() for VM_PrintThreads operation
2941 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2942 st->print_raw("\"");
2943 st->print_raw(get_thread_name());
2944 st->print_raw("\" ");
2945 oop thread_oop = threadObj();
2946 if (thread_oop != NULL) {
2947 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2948 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2949 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2950 }
2951 Thread::print_on(st, print_extended_info);
2952 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2953 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2954 if (thread_oop != NULL) {
2955 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2956 }
2957 #ifndef PRODUCT
2958 print_thread_state_on(st);
2959 _safepoint_state->print_on(st);
2960 #endif // PRODUCT
2961 if (is_Compiler_thread()) {
2962 CompileTask *task = ((CompilerThread*)this)->task();
2963 if (task != NULL) {
2964 st->print(" Compiling: ");
2965 task->print(st, NULL, true, false);
2966 } else {
2967 st->print(" No compile task");
2968 }
2969 st->cr();
2970 }
2971 }
2972
2973 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2974 st->print("%s", get_thread_name_string(buf, buflen));
2975 }
2976
2977 // Called by fatal error handler. The difference between this and
2978 // JavaThread::print() is that we can't grab lock or allocate memory.
2979 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2980 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2981 oop thread_obj = threadObj();
2982 if (thread_obj != NULL) {
2983 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2984 }
2985 st->print(" [");
2986 st->print("%s", _get_thread_state_name(_thread_state));
2987 if (osthread()) {
2988 st->print(", id=%d", osthread()->thread_id());
2989 }
2990 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2991 p2i(stack_end()), p2i(stack_base()));
2992 st->print("]");
2993
2994 ThreadsSMRSupport::print_info_on(this, st);
2995 return;
2996 }
2997
2998 // Verification
2999
3000 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3001
3002 void JavaThread::verify() {
3003 // Verify oops in the thread.
3004 oops_do(&VerifyOopClosure::verify_oop, NULL);
3005
3006 // Verify the stack frames.
3007 frames_do(frame_verify);
3008 }
3009
3010 // CR 6300358 (sub-CR 2137150)
3011 // Most callers of this method assume that it can't return NULL but a
3012 // thread may not have a name whilst it is in the process of attaching to
3013 // the VM - see CR 6412693, and there are places where a JavaThread can be
3014 // seen prior to having it's threadObj set (eg JNI attaching threads and
3015 // if vm exit occurs during initialization). These cases can all be accounted
3016 // for such that this method never returns NULL.
3017 const char* JavaThread::get_thread_name() const {
3018 #ifdef ASSERT
3019 // early safepoints can hit while current thread does not yet have TLS
3020 if (!SafepointSynchronize::is_at_safepoint()) {
3021 Thread *cur = Thread::current();
3022 if (!(cur->is_Java_thread() && cur == this)) {
3023 // Current JavaThreads are allowed to get their own name without
3024 // the Threads_lock.
3025 assert_locked_or_safepoint(Threads_lock);
3026 }
3027 }
3028 #endif // ASSERT
3029 return get_thread_name_string();
3030 }
3031
3032 // Returns a non-NULL representation of this thread's name, or a suitable
3033 // descriptive string if there is no set name
3034 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3035 const char* name_str;
3036 oop thread_obj = threadObj();
3037 if (thread_obj != NULL) {
3038 oop name = java_lang_Thread::name(thread_obj);
3039 if (name != NULL) {
3040 if (buf == NULL) {
3041 name_str = java_lang_String::as_utf8_string(name);
3042 } else {
3043 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3044 }
3045 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3046 name_str = "<no-name - thread is attaching>";
3047 } else {
3048 name_str = Thread::name();
3049 }
3050 } else {
3051 name_str = Thread::name();
3052 }
3053 assert(name_str != NULL, "unexpected NULL thread name");
3054 return name_str;
3055 }
3056
3057
3058 const char* JavaThread::get_threadgroup_name() const {
3059 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3060 oop thread_obj = threadObj();
3061 if (thread_obj != NULL) {
3062 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3063 if (thread_group != NULL) {
3064 // ThreadGroup.name can be null
3065 return java_lang_ThreadGroup::name(thread_group);
3066 }
3067 }
3068 return NULL;
3069 }
3070
3071 const char* JavaThread::get_parent_name() const {
3072 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3073 oop thread_obj = threadObj();
3074 if (thread_obj != NULL) {
3075 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3076 if (thread_group != NULL) {
3077 oop parent = java_lang_ThreadGroup::parent(thread_group);
3078 if (parent != NULL) {
3079 // ThreadGroup.name can be null
3080 return java_lang_ThreadGroup::name(parent);
3081 }
3082 }
3083 }
3084 return NULL;
3085 }
3086
3087 ThreadPriority JavaThread::java_priority() const {
3088 oop thr_oop = threadObj();
3089 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3090 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3091 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3092 return priority;
3093 }
3094
3095 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3096
3097 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3098 // Link Java Thread object <-> C++ Thread
3099
3100 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3101 // and put it into a new Handle. The Handle "thread_oop" can then
3102 // be used to pass the C++ thread object to other methods.
3103
3104 // Set the Java level thread object (jthread) field of the
3105 // new thread (a JavaThread *) to C++ thread object using the
3106 // "thread_oop" handle.
3107
3108 // Set the thread field (a JavaThread *) of the
3109 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3110
3111 Handle thread_oop(Thread::current(),
3112 JNIHandles::resolve_non_null(jni_thread));
3113 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3114 "must be initialized");
3115 set_threadObj(thread_oop());
3116 java_lang_Thread::set_thread(thread_oop(), this);
3117
3118 if (prio == NoPriority) {
3119 prio = java_lang_Thread::priority(thread_oop());
3120 assert(prio != NoPriority, "A valid priority should be present");
3121 }
3122
3123 // Push the Java priority down to the native thread; needs Threads_lock
3124 Thread::set_priority(this, prio);
3125
3126 // Add the new thread to the Threads list and set it in motion.
3127 // We must have threads lock in order to call Threads::add.
3128 // It is crucial that we do not block before the thread is
3129 // added to the Threads list for if a GC happens, then the java_thread oop
3130 // will not be visited by GC.
3131 Threads::add(this);
3132 }
3133
3134 oop JavaThread::current_park_blocker() {
3135 // Support for JSR-166 locks
3136 oop thread_oop = threadObj();
3137 if (thread_oop != NULL &&
3138 JDK_Version::current().supports_thread_park_blocker()) {
3139 return java_lang_Thread::park_blocker(thread_oop);
3140 }
3141 return NULL;
3142 }
3143
3144
3145 void JavaThread::print_stack_on(outputStream* st) {
3146 if (!has_last_Java_frame()) return;
3147 ResourceMark rm;
3148 HandleMark hm;
3149
3150 RegisterMap reg_map(this);
3151 vframe* start_vf = last_java_vframe(®_map);
3152 int count = 0;
3153 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3154 if (f->is_java_frame()) {
3155 javaVFrame* jvf = javaVFrame::cast(f);
3156 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3157
3158 // Print out lock information
3159 if (JavaMonitorsInStackTrace) {
3160 jvf->print_lock_info_on(st, count);
3161 }
3162 } else {
3163 // Ignore non-Java frames
3164 }
3165
3166 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3167 count++;
3168 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3169 }
3170 }
3171
3172
3173 // JVMTI PopFrame support
3174 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3175 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3176 if (in_bytes(size_in_bytes) != 0) {
3177 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3178 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3179 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3180 }
3181 }
3182
3183 void* JavaThread::popframe_preserved_args() {
3184 return _popframe_preserved_args;
3185 }
3186
3187 ByteSize JavaThread::popframe_preserved_args_size() {
3188 return in_ByteSize(_popframe_preserved_args_size);
3189 }
3190
3191 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3192 int sz = in_bytes(popframe_preserved_args_size());
3193 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3194 return in_WordSize(sz / wordSize);
3195 }
3196
3197 void JavaThread::popframe_free_preserved_args() {
3198 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3199 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3200 _popframe_preserved_args = NULL;
3201 _popframe_preserved_args_size = 0;
3202 }
3203
3204 #ifndef PRODUCT
3205
3206 void JavaThread::trace_frames() {
3207 tty->print_cr("[Describe stack]");
3208 int frame_no = 1;
3209 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3210 tty->print(" %d. ", frame_no++);
3211 fst.current()->print_value_on(tty, this);
3212 tty->cr();
3213 }
3214 }
3215
3216 class PrintAndVerifyOopClosure: public OopClosure {
3217 protected:
3218 template <class T> inline void do_oop_work(T* p) {
3219 oop obj = RawAccess<>::oop_load(p);
3220 if (obj == NULL) return;
3221 tty->print(INTPTR_FORMAT ": ", p2i(p));
3222 if (oopDesc::is_oop_or_null(obj)) {
3223 if (obj->is_objArray()) {
3224 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3225 } else {
3226 obj->print();
3227 }
3228 } else {
3229 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3230 }
3231 tty->cr();
3232 }
3233 public:
3234 virtual void do_oop(oop* p) { do_oop_work(p); }
3235 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3236 };
3237
3238
3239 static void oops_print(frame* f, const RegisterMap *map) {
3240 PrintAndVerifyOopClosure print;
3241 f->print_value();
3242 f->oops_do(&print, NULL, (RegisterMap*)map);
3243 }
3244
3245 // Print our all the locations that contain oops and whether they are
3246 // valid or not. This useful when trying to find the oldest frame
3247 // where an oop has gone bad since the frame walk is from youngest to
3248 // oldest.
3249 void JavaThread::trace_oops() {
3250 tty->print_cr("[Trace oops]");
3251 frames_do(oops_print);
3252 }
3253
3254
3255 #ifdef ASSERT
3256 // Print or validate the layout of stack frames
3257 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3258 ResourceMark rm;
3259 PRESERVE_EXCEPTION_MARK;
3260 FrameValues values;
3261 int frame_no = 0;
3262 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3263 fst.current()->describe(values, ++frame_no);
3264 if (depth == frame_no) break;
3265 }
3266 if (validate_only) {
3267 values.validate();
3268 } else {
3269 tty->print_cr("[Describe stack layout]");
3270 values.print(this);
3271 }
3272 }
3273 #endif
3274
3275 void JavaThread::trace_stack_from(vframe* start_vf) {
3276 ResourceMark rm;
3277 int vframe_no = 1;
3278 for (vframe* f = start_vf; f; f = f->sender()) {
3279 if (f->is_java_frame()) {
3280 javaVFrame::cast(f)->print_activation(vframe_no++);
3281 } else {
3282 f->print();
3283 }
3284 if (vframe_no > StackPrintLimit) {
3285 tty->print_cr("...<more frames>...");
3286 return;
3287 }
3288 }
3289 }
3290
3291
3292 void JavaThread::trace_stack() {
3293 if (!has_last_Java_frame()) return;
3294 ResourceMark rm;
3295 HandleMark hm;
3296 RegisterMap reg_map(this);
3297 trace_stack_from(last_java_vframe(®_map));
3298 }
3299
3300
3301 #endif // PRODUCT
3302
3303
3304 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3305 assert(reg_map != NULL, "a map must be given");
3306 frame f = last_frame();
3307 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3308 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3309 }
3310 return NULL;
3311 }
3312
3313
3314 Klass* JavaThread::security_get_caller_class(int depth) {
3315 vframeStream vfst(this);
3316 vfst.security_get_caller_frame(depth);
3317 if (!vfst.at_end()) {
3318 return vfst.method()->method_holder();
3319 }
3320 return NULL;
3321 }
3322
3323 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3324 assert(thread->is_Compiler_thread(), "must be compiler thread");
3325 CompileBroker::compiler_thread_loop();
3326 }
3327
3328 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3329 NMethodSweeper::sweeper_loop();
3330 }
3331
3332 // Create a CompilerThread
3333 CompilerThread::CompilerThread(CompileQueue* queue,
3334 CompilerCounters* counters)
3335 : JavaThread(&compiler_thread_entry) {
3336 _env = NULL;
3337 _log = NULL;
3338 _task = NULL;
3339 _queue = queue;
3340 _counters = counters;
3341 _buffer_blob = NULL;
3342 _compiler = NULL;
3343
3344 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3345 resource_area()->bias_to(mtCompiler);
3346
3347 #ifndef PRODUCT
3348 _ideal_graph_printer = NULL;
3349 #endif
3350 }
3351
3352 CompilerThread::~CompilerThread() {
3353 // Delete objects which were allocated on heap.
3354 delete _counters;
3355 }
3356
3357 bool CompilerThread::can_call_java() const {
3358 return _compiler != NULL && _compiler->is_jvmci();
3359 }
3360
3361 // Create sweeper thread
3362 CodeCacheSweeperThread::CodeCacheSweeperThread()
3363 : JavaThread(&sweeper_thread_entry) {
3364 _scanned_compiled_method = NULL;
3365 }
3366
3367 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3368 JavaThread::oops_do(f, cf);
3369 if (_scanned_compiled_method != NULL && cf != NULL) {
3370 // Safepoints can occur when the sweeper is scanning an nmethod so
3371 // process it here to make sure it isn't unloaded in the middle of
3372 // a scan.
3373 cf->do_code_blob(_scanned_compiled_method);
3374 }
3375 }
3376
3377 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3378 JavaThread::nmethods_do(cf);
3379 if (_scanned_compiled_method != NULL && cf != NULL) {
3380 // Safepoints can occur when the sweeper is scanning an nmethod so
3381 // process it here to make sure it isn't unloaded in the middle of
3382 // a scan.
3383 cf->do_code_blob(_scanned_compiled_method);
3384 }
3385 }
3386
3387
3388 // ======= Threads ========
3389
3390 // The Threads class links together all active threads, and provides
3391 // operations over all threads. It is protected by the Threads_lock,
3392 // which is also used in other global contexts like safepointing.
3393 // ThreadsListHandles are used to safely perform operations on one
3394 // or more threads without the risk of the thread exiting during the
3395 // operation.
3396 //
3397 // Note: The Threads_lock is currently more widely used than we
3398 // would like. We are actively migrating Threads_lock uses to other
3399 // mechanisms in order to reduce Threads_lock contention.
3400
3401 JavaThread* Threads::_thread_list = NULL;
3402 int Threads::_number_of_threads = 0;
3403 int Threads::_number_of_non_daemon_threads = 0;
3404 int Threads::_return_code = 0;
3405 int Threads::_thread_claim_parity = 0;
3406 size_t JavaThread::_stack_size_at_create = 0;
3407
3408 #ifdef ASSERT
3409 bool Threads::_vm_complete = false;
3410 size_t Threads::_threads_before_barrier_set = 0;
3411 #endif
3412
3413 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3414 Prefetch::read((void*)addr, prefetch_interval);
3415 return *addr;
3416 }
3417
3418 // Possibly the ugliest for loop the world has seen. C++ does not allow
3419 // multiple types in the declaration section of the for loop. In this case
3420 // we are only dealing with pointers and hence can cast them. It looks ugly
3421 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3422 #define DO_JAVA_THREADS(LIST, X) \
3423 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3424 *MACRO_list = (JavaThread*)(LIST), \
3425 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3426 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3427 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3428 MACRO_current_p != MACRO_end; \
3429 MACRO_current_p++, \
3430 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3431
3432 // All JavaThreads
3433 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3434
3435 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3436 void Threads::non_java_threads_do(ThreadClosure* tc) {
3437 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3438 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3439 tc->do_thread(njti.current());
3440 }
3441 }
3442
3443 // All JavaThreads
3444 void Threads::java_threads_do(ThreadClosure* tc) {
3445 assert_locked_or_safepoint(Threads_lock);
3446 // ALL_JAVA_THREADS iterates through all JavaThreads.
3447 ALL_JAVA_THREADS(p) {
3448 tc->do_thread(p);
3449 }
3450 }
3451
3452 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3453 assert_locked_or_safepoint(Threads_lock);
3454 java_threads_do(tc);
3455 tc->do_thread(VMThread::vm_thread());
3456 }
3457
3458 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3459 void Threads::threads_do(ThreadClosure* tc) {
3460 assert_locked_or_safepoint(Threads_lock);
3461 java_threads_do(tc);
3462 non_java_threads_do(tc);
3463 }
3464
3465 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3466 int cp = Threads::thread_claim_parity();
3467 ALL_JAVA_THREADS(p) {
3468 if (p->claim_oops_do(is_par, cp)) {
3469 tc->do_thread(p);
3470 }
3471 }
3472 VMThread* vmt = VMThread::vm_thread();
3473 if (vmt->claim_oops_do(is_par, cp)) {
3474 tc->do_thread(vmt);
3475 }
3476 }
3477
3478 // The system initialization in the library has three phases.
3479 //
3480 // Phase 1: java.lang.System class initialization
3481 // java.lang.System is a primordial class loaded and initialized
3482 // by the VM early during startup. java.lang.System.<clinit>
3483 // only does registerNatives and keeps the rest of the class
3484 // initialization work later until thread initialization completes.
3485 //
3486 // System.initPhase1 initializes the system properties, the static
3487 // fields in, out, and err. Set up java signal handlers, OS-specific
3488 // system settings, and thread group of the main thread.
3489 static void call_initPhase1(TRAPS) {
3490 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3491 JavaValue result(T_VOID);
3492 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3493 vmSymbols::void_method_signature(), CHECK);
3494 }
3495
3496 // Phase 2. Module system initialization
3497 // This will initialize the module system. Only java.base classes
3498 // can be loaded until phase 2 completes.
3499 //
3500 // Call System.initPhase2 after the compiler initialization and jsr292
3501 // classes get initialized because module initialization runs a lot of java
3502 // code, that for performance reasons, should be compiled. Also, this will
3503 // enable the startup code to use lambda and other language features in this
3504 // phase and onward.
3505 //
3506 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3507 static void call_initPhase2(TRAPS) {
3508 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3509
3510 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3511
3512 JavaValue result(T_INT);
3513 JavaCallArguments args;
3514 args.push_int(DisplayVMOutputToStderr);
3515 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3516 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3517 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3518 if (result.get_jint() != JNI_OK) {
3519 vm_exit_during_initialization(); // no message or exception
3520 }
3521
3522 universe_post_module_init();
3523 }
3524
3525 // Phase 3. final setup - set security manager, system class loader and TCCL
3526 //
3527 // This will instantiate and set the security manager, set the system class
3528 // loader as well as the thread context class loader. The security manager
3529 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3530 // other modules or the application's classpath.
3531 static void call_initPhase3(TRAPS) {
3532 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3533 JavaValue result(T_VOID);
3534 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3535 vmSymbols::void_method_signature(), CHECK);
3536 }
3537
3538 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3539 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3540
3541 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3542 create_vm_init_libraries();
3543 }
3544
3545 initialize_class(vmSymbols::java_lang_String(), CHECK);
3546
3547 // Inject CompactStrings value after the static initializers for String ran.
3548 java_lang_String::set_compact_strings(CompactStrings);
3549
3550 // Initialize java_lang.System (needed before creating the thread)
3551 initialize_class(vmSymbols::java_lang_System(), CHECK);
3552 // The VM creates & returns objects of this class. Make sure it's initialized.
3553 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3554 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3555 Handle thread_group = create_initial_thread_group(CHECK);
3556 Universe::set_main_thread_group(thread_group());
3557 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3558 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3559 main_thread->set_threadObj(thread_object);
3560 // Set thread status to running since main thread has
3561 // been started and running.
3562 java_lang_Thread::set_thread_status(thread_object,
3563 java_lang_Thread::RUNNABLE);
3564
3565 // The VM creates objects of this class.
3566 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3567
3568 // The VM preresolves methods to these classes. Make sure that they get initialized
3569 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3570 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3571
3572 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3573 call_initPhase1(CHECK);
3574
3575 // get the Java runtime name after java.lang.System is initialized
3576 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3577 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3578
3579 // an instance of OutOfMemory exception has been allocated earlier
3580 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3581 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3582 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3583 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3584 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3585 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3586 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3587 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3588 }
3589
3590 void Threads::initialize_jsr292_core_classes(TRAPS) {
3591 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3592
3593 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3594 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3595 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3596 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3597 }
3598
3599 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3600 extern void JDK_Version_init();
3601
3602 // Preinitialize version info.
3603 VM_Version::early_initialize();
3604
3605 // Check version
3606 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3607
3608 // Initialize library-based TLS
3609 ThreadLocalStorage::init();
3610
3611 // Initialize the output stream module
3612 ostream_init();
3613
3614 // Process java launcher properties.
3615 Arguments::process_sun_java_launcher_properties(args);
3616
3617 // Initialize the os module
3618 os::init();
3619
3620 // Record VM creation timing statistics
3621 TraceVmCreationTime create_vm_timer;
3622 create_vm_timer.start();
3623
3624 // Initialize system properties.
3625 Arguments::init_system_properties();
3626
3627 // So that JDK version can be used as a discriminator when parsing arguments
3628 JDK_Version_init();
3629
3630 // Update/Initialize System properties after JDK version number is known
3631 Arguments::init_version_specific_system_properties();
3632
3633 // Make sure to initialize log configuration *before* parsing arguments
3634 LogConfiguration::initialize(create_vm_timer.begin_time());
3635
3636 // Parse arguments
3637 // Note: this internally calls os::init_container_support()
3638 jint parse_result = Arguments::parse(args);
3639 if (parse_result != JNI_OK) return parse_result;
3640
3641 os::init_before_ergo();
3642
3643 jint ergo_result = Arguments::apply_ergo();
3644 if (ergo_result != JNI_OK) return ergo_result;
3645
3646 // Final check of all ranges after ergonomics which may change values.
3647 if (!JVMFlagRangeList::check_ranges()) {
3648 return JNI_EINVAL;
3649 }
3650
3651 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3652 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3653 if (!constraint_result) {
3654 return JNI_EINVAL;
3655 }
3656
3657 JVMFlagWriteableList::mark_startup();
3658
3659 if (PauseAtStartup) {
3660 os::pause();
3661 }
3662
3663 HOTSPOT_VM_INIT_BEGIN();
3664
3665 // Timing (must come after argument parsing)
3666 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3667
3668 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3669 // Initialize assert poison page mechanism.
3670 if (ShowRegistersOnAssert) {
3671 initialize_assert_poison();
3672 }
3673 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3674
3675 // Initialize the os module after parsing the args
3676 jint os_init_2_result = os::init_2();
3677 if (os_init_2_result != JNI_OK) return os_init_2_result;
3678
3679 SafepointMechanism::initialize();
3680
3681 jint adjust_after_os_result = Arguments::adjust_after_os();
3682 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3683
3684 // Initialize output stream logging
3685 ostream_init_log();
3686
3687 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3688 // Must be before create_vm_init_agents()
3689 if (Arguments::init_libraries_at_startup()) {
3690 convert_vm_init_libraries_to_agents();
3691 }
3692
3693 // Launch -agentlib/-agentpath and converted -Xrun agents
3694 if (Arguments::init_agents_at_startup()) {
3695 create_vm_init_agents();
3696 }
3697
3698 // Initialize Threads state
3699 _thread_list = NULL;
3700 _number_of_threads = 0;
3701 _number_of_non_daemon_threads = 0;
3702
3703 // Initialize global data structures and create system classes in heap
3704 vm_init_globals();
3705
3706 #if INCLUDE_JVMCI
3707 if (JVMCICounterSize > 0) {
3708 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3709 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3710 } else {
3711 JavaThread::_jvmci_old_thread_counters = NULL;
3712 }
3713 #endif // INCLUDE_JVMCI
3714
3715 // Attach the main thread to this os thread
3716 JavaThread* main_thread = new JavaThread();
3717 main_thread->set_thread_state(_thread_in_vm);
3718 main_thread->initialize_thread_current();
3719 // must do this before set_active_handles
3720 main_thread->record_stack_base_and_size();
3721 main_thread->register_thread_stack_with_NMT();
3722 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3723
3724 if (!main_thread->set_as_starting_thread()) {
3725 vm_shutdown_during_initialization(
3726 "Failed necessary internal allocation. Out of swap space");
3727 main_thread->smr_delete();
3728 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3729 return JNI_ENOMEM;
3730 }
3731
3732 // Enable guard page *after* os::create_main_thread(), otherwise it would
3733 // crash Linux VM, see notes in os_linux.cpp.
3734 main_thread->create_stack_guard_pages();
3735
3736 // Initialize Java-Level synchronization subsystem
3737 ObjectMonitor::Initialize();
3738
3739 // Initialize global modules
3740 jint status = init_globals();
3741 if (status != JNI_OK) {
3742 main_thread->smr_delete();
3743 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3744 return status;
3745 }
3746
3747 JFR_ONLY(Jfr::on_vm_init();)
3748
3749 // Should be done after the heap is fully created
3750 main_thread->cache_global_variables();
3751
3752 HandleMark hm;
3753
3754 { MutexLocker mu(Threads_lock);
3755 Threads::add(main_thread);
3756 }
3757
3758 // Any JVMTI raw monitors entered in onload will transition into
3759 // real raw monitor. VM is setup enough here for raw monitor enter.
3760 JvmtiExport::transition_pending_onload_raw_monitors();
3761
3762 // Create the VMThread
3763 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3764
3765 VMThread::create();
3766 Thread* vmthread = VMThread::vm_thread();
3767
3768 if (!os::create_thread(vmthread, os::vm_thread)) {
3769 vm_exit_during_initialization("Cannot create VM thread. "
3770 "Out of system resources.");
3771 }
3772
3773 // Wait for the VM thread to become ready, and VMThread::run to initialize
3774 // Monitors can have spurious returns, must always check another state flag
3775 {
3776 MutexLocker ml(Notify_lock);
3777 os::start_thread(vmthread);
3778 while (vmthread->active_handles() == NULL) {
3779 Notify_lock->wait();
3780 }
3781 }
3782 }
3783
3784 assert(Universe::is_fully_initialized(), "not initialized");
3785 if (VerifyDuringStartup) {
3786 // Make sure we're starting with a clean slate.
3787 VM_Verify verify_op;
3788 VMThread::execute(&verify_op);
3789 }
3790
3791 // We need this to update the java.vm.info property in case any flags used
3792 // to initially define it have been changed. This is needed for both CDS and
3793 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3794 // is initially computed. See Abstract_VM_Version::vm_info_string().
3795 // This update must happen before we initialize the java classes, but
3796 // after any initialization logic that might modify the flags.
3797 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3798
3799 Thread* THREAD = Thread::current();
3800
3801 // Always call even when there are not JVMTI environments yet, since environments
3802 // may be attached late and JVMTI must track phases of VM execution
3803 JvmtiExport::enter_early_start_phase();
3804
3805 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3806 JvmtiExport::post_early_vm_start();
3807
3808 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3809
3810 quicken_jni_functions();
3811
3812 // No more stub generation allowed after that point.
3813 StubCodeDesc::freeze();
3814
3815 // Set flag that basic initialization has completed. Used by exceptions and various
3816 // debug stuff, that does not work until all basic classes have been initialized.
3817 set_init_completed();
3818
3819 LogConfiguration::post_initialize();
3820 Metaspace::post_initialize();
3821
3822 HOTSPOT_VM_INIT_END();
3823
3824 // record VM initialization completion time
3825 #if INCLUDE_MANAGEMENT
3826 Management::record_vm_init_completed();
3827 #endif // INCLUDE_MANAGEMENT
3828
3829 // Signal Dispatcher needs to be started before VMInit event is posted
3830 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3831
3832 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3833 if (!DisableAttachMechanism) {
3834 AttachListener::vm_start();
3835 if (StartAttachListener || AttachListener::init_at_startup()) {
3836 AttachListener::init();
3837 }
3838 }
3839
3840 // Launch -Xrun agents
3841 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3842 // back-end can launch with -Xdebug -Xrunjdwp.
3843 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3844 create_vm_init_libraries();
3845 }
3846
3847 if (CleanChunkPoolAsync) {
3848 Chunk::start_chunk_pool_cleaner_task();
3849 }
3850
3851 // initialize compiler(s)
3852 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3853 #if INCLUDE_JVMCI
3854 bool force_JVMCI_intialization = false;
3855 if (EnableJVMCI) {
3856 // Initialize JVMCI eagerly when it is explicitly requested.
3857 // Or when JVMCIPrintProperties is enabled.
3858 // The JVMCI Java initialization code will read this flag and
3859 // do the printing if it's set.
3860 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3861
3862 if (!force_JVMCI_intialization) {
3863 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3864 // compilations via JVMCI will not actually block until JVMCI is initialized.
3865 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3866 }
3867 }
3868 #endif
3869 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3870 // Postpone completion of compiler initialization to after JVMCI
3871 // is initialized to avoid timeouts of blocking compilations.
3872 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3873 CompileBroker::compilation_init_phase2();
3874 }
3875 #endif
3876
3877 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3878 // It is done after compilers are initialized, because otherwise compilations of
3879 // signature polymorphic MH intrinsics can be missed
3880 // (see SystemDictionary::find_method_handle_intrinsic).
3881 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3882
3883 // This will initialize the module system. Only java.base classes can be
3884 // loaded until phase 2 completes
3885 call_initPhase2(CHECK_JNI_ERR);
3886
3887 // Always call even when there are not JVMTI environments yet, since environments
3888 // may be attached late and JVMTI must track phases of VM execution
3889 JvmtiExport::enter_start_phase();
3890
3891 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3892 JvmtiExport::post_vm_start();
3893
3894 // Final system initialization including security manager and system class loader
3895 call_initPhase3(CHECK_JNI_ERR);
3896
3897 // cache the system and platform class loaders
3898 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3899
3900 #if INCLUDE_CDS
3901 if (DumpSharedSpaces) {
3902 // capture the module path info from the ModuleEntryTable
3903 ClassLoader::initialize_module_path(THREAD);
3904 }
3905 #endif
3906
3907 #if INCLUDE_JVMCI
3908 if (force_JVMCI_intialization) {
3909 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3910 CompileBroker::compilation_init_phase2();
3911 }
3912 #endif
3913
3914 // Always call even when there are not JVMTI environments yet, since environments
3915 // may be attached late and JVMTI must track phases of VM execution
3916 JvmtiExport::enter_live_phase();
3917
3918 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3919 JvmtiExport::post_vm_initialized();
3920
3921 JFR_ONLY(Jfr::on_vm_start();)
3922
3923 #if INCLUDE_MANAGEMENT
3924 Management::initialize(THREAD);
3925
3926 if (HAS_PENDING_EXCEPTION) {
3927 // management agent fails to start possibly due to
3928 // configuration problem and is responsible for printing
3929 // stack trace if appropriate. Simply exit VM.
3930 vm_exit(1);
3931 }
3932 #endif // INCLUDE_MANAGEMENT
3933
3934 if (MemProfiling) MemProfiler::engage();
3935 StatSampler::engage();
3936 if (CheckJNICalls) JniPeriodicChecker::engage();
3937
3938 BiasedLocking::init();
3939
3940 #if INCLUDE_RTM_OPT
3941 RTMLockingCounters::init();
3942 #endif
3943
3944 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3945 call_postVMInitHook(THREAD);
3946 // The Java side of PostVMInitHook.run must deal with all
3947 // exceptions and provide means of diagnosis.
3948 if (HAS_PENDING_EXCEPTION) {
3949 CLEAR_PENDING_EXCEPTION;
3950 }
3951 }
3952
3953 {
3954 MutexLocker ml(PeriodicTask_lock);
3955 // Make sure the WatcherThread can be started by WatcherThread::start()
3956 // or by dynamic enrollment.
3957 WatcherThread::make_startable();
3958 // Start up the WatcherThread if there are any periodic tasks
3959 // NOTE: All PeriodicTasks should be registered by now. If they
3960 // aren't, late joiners might appear to start slowly (we might
3961 // take a while to process their first tick).
3962 if (PeriodicTask::num_tasks() > 0) {
3963 WatcherThread::start();
3964 }
3965 }
3966
3967 create_vm_timer.end();
3968 #ifdef ASSERT
3969 _vm_complete = true;
3970 #endif
3971
3972 if (DumpSharedSpaces) {
3973 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3974 ShouldNotReachHere();
3975 }
3976
3977 return JNI_OK;
3978 }
3979
3980 // type for the Agent_OnLoad and JVM_OnLoad entry points
3981 extern "C" {
3982 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3983 }
3984 // Find a command line agent library and return its entry point for
3985 // -agentlib: -agentpath: -Xrun
3986 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3987 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3988 const char *on_load_symbols[],
3989 size_t num_symbol_entries) {
3990 OnLoadEntry_t on_load_entry = NULL;
3991 void *library = NULL;
3992
3993 if (!agent->valid()) {
3994 char buffer[JVM_MAXPATHLEN];
3995 char ebuf[1024] = "";
3996 const char *name = agent->name();
3997 const char *msg = "Could not find agent library ";
3998
3999 // First check to see if agent is statically linked into executable
4000 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4001 library = agent->os_lib();
4002 } else if (agent->is_absolute_path()) {
4003 library = os::dll_load(name, ebuf, sizeof ebuf);
4004 if (library == NULL) {
4005 const char *sub_msg = " in absolute path, with error: ";
4006 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4007 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4008 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4009 // If we can't find the agent, exit.
4010 vm_exit_during_initialization(buf, NULL);
4011 FREE_C_HEAP_ARRAY(char, buf);
4012 }
4013 } else {
4014 // Try to load the agent from the standard dll directory
4015 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4016 name)) {
4017 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4018 }
4019 if (library == NULL) { // Try the library path directory.
4020 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4021 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4022 }
4023 if (library == NULL) {
4024 const char *sub_msg = " on the library path, with error: ";
4025 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4026
4027 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4028 strlen(ebuf) + strlen(sub_msg2) + 1;
4029 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4030 if (!agent->is_instrument_lib()) {
4031 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4032 } else {
4033 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4034 }
4035 // If we can't find the agent, exit.
4036 vm_exit_during_initialization(buf, NULL);
4037 FREE_C_HEAP_ARRAY(char, buf);
4038 }
4039 }
4040 }
4041 agent->set_os_lib(library);
4042 agent->set_valid();
4043 }
4044
4045 // Find the OnLoad function.
4046 on_load_entry =
4047 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4048 false,
4049 on_load_symbols,
4050 num_symbol_entries));
4051 return on_load_entry;
4052 }
4053
4054 // Find the JVM_OnLoad entry point
4055 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4056 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4057 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4058 }
4059
4060 // Find the Agent_OnLoad entry point
4061 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4062 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4063 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4064 }
4065
4066 // For backwards compatibility with -Xrun
4067 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4068 // treated like -agentpath:
4069 // Must be called before agent libraries are created
4070 void Threads::convert_vm_init_libraries_to_agents() {
4071 AgentLibrary* agent;
4072 AgentLibrary* next;
4073
4074 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4075 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4076 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4077
4078 // If there is an JVM_OnLoad function it will get called later,
4079 // otherwise see if there is an Agent_OnLoad
4080 if (on_load_entry == NULL) {
4081 on_load_entry = lookup_agent_on_load(agent);
4082 if (on_load_entry != NULL) {
4083 // switch it to the agent list -- so that Agent_OnLoad will be called,
4084 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4085 Arguments::convert_library_to_agent(agent);
4086 } else {
4087 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4088 }
4089 }
4090 }
4091 }
4092
4093 // Create agents for -agentlib: -agentpath: and converted -Xrun
4094 // Invokes Agent_OnLoad
4095 // Called very early -- before JavaThreads exist
4096 void Threads::create_vm_init_agents() {
4097 extern struct JavaVM_ main_vm;
4098 AgentLibrary* agent;
4099
4100 JvmtiExport::enter_onload_phase();
4101
4102 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4103 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4104
4105 if (on_load_entry != NULL) {
4106 // Invoke the Agent_OnLoad function
4107 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4108 if (err != JNI_OK) {
4109 vm_exit_during_initialization("agent library failed to init", agent->name());
4110 }
4111 } else {
4112 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4113 }
4114 }
4115 JvmtiExport::enter_primordial_phase();
4116 }
4117
4118 extern "C" {
4119 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4120 }
4121
4122 void Threads::shutdown_vm_agents() {
4123 // Send any Agent_OnUnload notifications
4124 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4125 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4126 extern struct JavaVM_ main_vm;
4127 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4128
4129 // Find the Agent_OnUnload function.
4130 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4131 os::find_agent_function(agent,
4132 false,
4133 on_unload_symbols,
4134 num_symbol_entries));
4135
4136 // Invoke the Agent_OnUnload function
4137 if (unload_entry != NULL) {
4138 JavaThread* thread = JavaThread::current();
4139 ThreadToNativeFromVM ttn(thread);
4140 HandleMark hm(thread);
4141 (*unload_entry)(&main_vm);
4142 }
4143 }
4144 }
4145
4146 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4147 // Invokes JVM_OnLoad
4148 void Threads::create_vm_init_libraries() {
4149 extern struct JavaVM_ main_vm;
4150 AgentLibrary* agent;
4151
4152 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4153 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4154
4155 if (on_load_entry != NULL) {
4156 // Invoke the JVM_OnLoad function
4157 JavaThread* thread = JavaThread::current();
4158 ThreadToNativeFromVM ttn(thread);
4159 HandleMark hm(thread);
4160 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4161 if (err != JNI_OK) {
4162 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4163 }
4164 } else {
4165 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4166 }
4167 }
4168 }
4169
4170
4171 // Last thread running calls java.lang.Shutdown.shutdown()
4172 void JavaThread::invoke_shutdown_hooks() {
4173 HandleMark hm(this);
4174
4175 // We could get here with a pending exception, if so clear it now.
4176 if (this->has_pending_exception()) {
4177 this->clear_pending_exception();
4178 }
4179
4180 EXCEPTION_MARK;
4181 Klass* shutdown_klass =
4182 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4183 THREAD);
4184 if (shutdown_klass != NULL) {
4185 // SystemDictionary::resolve_or_null will return null if there was
4186 // an exception. If we cannot load the Shutdown class, just don't
4187 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4188 // won't be run. Note that if a shutdown hook was registered,
4189 // the Shutdown class would have already been loaded
4190 // (Runtime.addShutdownHook will load it).
4191 JavaValue result(T_VOID);
4192 JavaCalls::call_static(&result,
4193 shutdown_klass,
4194 vmSymbols::shutdown_method_name(),
4195 vmSymbols::void_method_signature(),
4196 THREAD);
4197 }
4198 CLEAR_PENDING_EXCEPTION;
4199 }
4200
4201 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4202 // the program falls off the end of main(). Another VM exit path is through
4203 // vm_exit() when the program calls System.exit() to return a value or when
4204 // there is a serious error in VM. The two shutdown paths are not exactly
4205 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4206 // and VM_Exit op at VM level.
4207 //
4208 // Shutdown sequence:
4209 // + Shutdown native memory tracking if it is on
4210 // + Wait until we are the last non-daemon thread to execute
4211 // <-- every thing is still working at this moment -->
4212 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4213 // shutdown hooks
4214 // + Call before_exit(), prepare for VM exit
4215 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4216 // currently the only user of this mechanism is File.deleteOnExit())
4217 // > stop StatSampler, watcher thread, CMS threads,
4218 // post thread end and vm death events to JVMTI,
4219 // stop signal thread
4220 // + Call JavaThread::exit(), it will:
4221 // > release JNI handle blocks, remove stack guard pages
4222 // > remove this thread from Threads list
4223 // <-- no more Java code from this thread after this point -->
4224 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4225 // the compiler threads at safepoint
4226 // <-- do not use anything that could get blocked by Safepoint -->
4227 // + Disable tracing at JNI/JVM barriers
4228 // + Set _vm_exited flag for threads that are still running native code
4229 // + Call exit_globals()
4230 // > deletes tty
4231 // > deletes PerfMemory resources
4232 // + Delete this thread
4233 // + Return to caller
4234
4235 bool Threads::destroy_vm() {
4236 JavaThread* thread = JavaThread::current();
4237
4238 #ifdef ASSERT
4239 _vm_complete = false;
4240 #endif
4241 // Wait until we are the last non-daemon thread to execute
4242 { MutexLocker nu(Threads_lock);
4243 while (Threads::number_of_non_daemon_threads() > 1)
4244 // This wait should make safepoint checks, wait without a timeout,
4245 // and wait as a suspend-equivalent condition.
4246 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4247 Mutex::_as_suspend_equivalent_flag);
4248 }
4249
4250 EventShutdown e;
4251 if (e.should_commit()) {
4252 e.set_reason("No remaining non-daemon Java threads");
4253 e.commit();
4254 }
4255
4256 // Hang forever on exit if we are reporting an error.
4257 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4258 os::infinite_sleep();
4259 }
4260 os::wait_for_keypress_at_exit();
4261
4262 // run Java level shutdown hooks
4263 thread->invoke_shutdown_hooks();
4264
4265 before_exit(thread);
4266
4267 thread->exit(true);
4268 // thread will never call smr_delete, instead of implicit cancel
4269 // in wait_for_vm_thread_exit we do it explicit.
4270 thread->cancel_handshake();
4271
4272 // Stop VM thread.
4273 {
4274 // 4945125 The vm thread comes to a safepoint during exit.
4275 // GC vm_operations can get caught at the safepoint, and the
4276 // heap is unparseable if they are caught. Grab the Heap_lock
4277 // to prevent this. The GC vm_operations will not be able to
4278 // queue until after the vm thread is dead. After this point,
4279 // we'll never emerge out of the safepoint before the VM exits.
4280
4281 MutexLocker ml(Heap_lock);
4282
4283 VMThread::wait_for_vm_thread_exit();
4284 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4285 VMThread::destroy();
4286 }
4287
4288 // Now, all Java threads are gone except daemon threads. Daemon threads
4289 // running Java code or in VM are stopped by the Safepoint. However,
4290 // daemon threads executing native code are still running. But they
4291 // will be stopped at native=>Java/VM barriers. Note that we can't
4292 // simply kill or suspend them, as it is inherently deadlock-prone.
4293
4294 VM_Exit::set_vm_exited();
4295
4296 // Clean up ideal graph printers after the VMThread has started
4297 // the final safepoint which will block all the Compiler threads.
4298 // Note that this Thread has already logically exited so the
4299 // clean_up() function's use of a JavaThreadIteratorWithHandle
4300 // would be a problem except set_vm_exited() has remembered the
4301 // shutdown thread which is granted a policy exception.
4302 #if defined(COMPILER2) && !defined(PRODUCT)
4303 IdealGraphPrinter::clean_up();
4304 #endif
4305
4306 notify_vm_shutdown();
4307
4308 // exit_globals() will delete tty
4309 exit_globals();
4310
4311 // We are after VM_Exit::set_vm_exited() so we can't call
4312 // thread->smr_delete() or we will block on the Threads_lock.
4313 // Deleting the shutdown thread here is safe because another
4314 // JavaThread cannot have an active ThreadsListHandle for
4315 // this JavaThread.
4316 delete thread;
4317
4318 #if INCLUDE_JVMCI
4319 if (JVMCICounterSize > 0) {
4320 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4321 }
4322 #endif
4323
4324 LogConfiguration::finalize();
4325
4326 return true;
4327 }
4328
4329
4330 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4331 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4332 return is_supported_jni_version(version);
4333 }
4334
4335
4336 jboolean Threads::is_supported_jni_version(jint version) {
4337 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4338 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4339 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4340 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4341 if (version == JNI_VERSION_9) return JNI_TRUE;
4342 if (version == JNI_VERSION_10) return JNI_TRUE;
4343 return JNI_FALSE;
4344 }
4345
4346
4347 void Threads::add(JavaThread* p, bool force_daemon) {
4348 // The threads lock must be owned at this point
4349 assert_locked_or_safepoint(Threads_lock);
4350
4351 BarrierSet::barrier_set()->on_thread_attach(p);
4352
4353 p->set_next(_thread_list);
4354 _thread_list = p;
4355
4356 // Once a JavaThread is added to the Threads list, smr_delete() has
4357 // to be used to delete it. Otherwise we can just delete it directly.
4358 p->set_on_thread_list();
4359
4360 _number_of_threads++;
4361 oop threadObj = p->threadObj();
4362 bool daemon = true;
4363 // Bootstrapping problem: threadObj can be null for initial
4364 // JavaThread (or for threads attached via JNI)
4365 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4366 _number_of_non_daemon_threads++;
4367 daemon = false;
4368 }
4369
4370 ThreadService::add_thread(p, daemon);
4371
4372 // Maintain fast thread list
4373 ThreadsSMRSupport::add_thread(p);
4374
4375 // Possible GC point.
4376 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4377 }
4378
4379 void Threads::remove(JavaThread* p) {
4380
4381 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4382 ObjectSynchronizer::omFlush(p);
4383
4384 // Extra scope needed for Thread_lock, so we can check
4385 // that we do not remove thread without safepoint code notice
4386 { MutexLocker ml(Threads_lock);
4387
4388 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4389
4390 // Maintain fast thread list
4391 ThreadsSMRSupport::remove_thread(p);
4392
4393 JavaThread* current = _thread_list;
4394 JavaThread* prev = NULL;
4395
4396 while (current != p) {
4397 prev = current;
4398 current = current->next();
4399 }
4400
4401 if (prev) {
4402 prev->set_next(current->next());
4403 } else {
4404 _thread_list = p->next();
4405 }
4406
4407 _number_of_threads--;
4408 oop threadObj = p->threadObj();
4409 bool daemon = true;
4410 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4411 _number_of_non_daemon_threads--;
4412 daemon = false;
4413
4414 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4415 // on destroy_vm will wake up.
4416 if (number_of_non_daemon_threads() == 1) {
4417 Threads_lock->notify_all();
4418 }
4419 }
4420 ThreadService::remove_thread(p, daemon);
4421
4422 // Make sure that safepoint code disregard this thread. This is needed since
4423 // the thread might mess around with locks after this point. This can cause it
4424 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4425 // of this thread since it is removed from the queue.
4426 p->set_terminated_value();
4427 } // unlock Threads_lock
4428
4429 // Since Events::log uses a lock, we grab it outside the Threads_lock
4430 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4431 }
4432
4433 // Operations on the Threads list for GC. These are not explicitly locked,
4434 // but the garbage collector must provide a safe context for them to run.
4435 // In particular, these things should never be called when the Threads_lock
4436 // is held by some other thread. (Note: the Safepoint abstraction also
4437 // uses the Threads_lock to guarantee this property. It also makes sure that
4438 // all threads gets blocked when exiting or starting).
4439
4440 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4441 ALL_JAVA_THREADS(p) {
4442 p->oops_do(f, cf);
4443 }
4444 VMThread::vm_thread()->oops_do(f, cf);
4445 }
4446
4447 void Threads::change_thread_claim_parity() {
4448 // Set the new claim parity.
4449 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4450 "Not in range.");
4451 _thread_claim_parity++;
4452 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4453 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4454 "Not in range.");
4455 }
4456
4457 #ifdef ASSERT
4458 void Threads::assert_all_threads_claimed() {
4459 ALL_JAVA_THREADS(p) {
4460 const int thread_parity = p->oops_do_parity();
4461 assert((thread_parity == _thread_claim_parity),
4462 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4463 }
4464 VMThread* vmt = VMThread::vm_thread();
4465 const int thread_parity = vmt->oops_do_parity();
4466 assert((thread_parity == _thread_claim_parity),
4467 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4468 }
4469 #endif // ASSERT
4470
4471 class ParallelOopsDoThreadClosure : public ThreadClosure {
4472 private:
4473 OopClosure* _f;
4474 CodeBlobClosure* _cf;
4475 public:
4476 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4477 void do_thread(Thread* t) {
4478 t->oops_do(_f, _cf);
4479 }
4480 };
4481
4482 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4483 ParallelOopsDoThreadClosure tc(f, cf);
4484 possibly_parallel_threads_do(is_par, &tc);
4485 }
4486
4487 void Threads::nmethods_do(CodeBlobClosure* cf) {
4488 ALL_JAVA_THREADS(p) {
4489 // This is used by the code cache sweeper to mark nmethods that are active
4490 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4491 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4492 if(!p->is_Code_cache_sweeper_thread()) {
4493 p->nmethods_do(cf);
4494 }
4495 }
4496 }
4497
4498 void Threads::metadata_do(void f(Metadata*)) {
4499 ALL_JAVA_THREADS(p) {
4500 p->metadata_do(f);
4501 }
4502 }
4503
4504 class ThreadHandlesClosure : public ThreadClosure {
4505 void (*_f)(Metadata*);
4506 public:
4507 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4508 virtual void do_thread(Thread* thread) {
4509 thread->metadata_handles_do(_f);
4510 }
4511 };
4512
4513 void Threads::metadata_handles_do(void f(Metadata*)) {
4514 // Only walk the Handles in Thread.
4515 ThreadHandlesClosure handles_closure(f);
4516 threads_do(&handles_closure);
4517 }
4518
4519 void Threads::deoptimized_wrt_marked_nmethods() {
4520 ALL_JAVA_THREADS(p) {
4521 p->deoptimized_wrt_marked_nmethods();
4522 }
4523 }
4524
4525
4526 // Get count Java threads that are waiting to enter the specified monitor.
4527 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4528 int count,
4529 address monitor) {
4530 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4531
4532 int i = 0;
4533 DO_JAVA_THREADS(t_list, p) {
4534 if (!p->can_call_java()) continue;
4535
4536 address pending = (address)p->current_pending_monitor();
4537 if (pending == monitor) { // found a match
4538 if (i < count) result->append(p); // save the first count matches
4539 i++;
4540 }
4541 }
4542
4543 return result;
4544 }
4545
4546
4547 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4548 address owner) {
4549 // NULL owner means not locked so we can skip the search
4550 if (owner == NULL) return NULL;
4551
4552 DO_JAVA_THREADS(t_list, p) {
4553 // first, see if owner is the address of a Java thread
4554 if (owner == (address)p) return p;
4555 }
4556
4557 // Cannot assert on lack of success here since this function may be
4558 // used by code that is trying to report useful problem information
4559 // like deadlock detection.
4560 if (UseHeavyMonitors) return NULL;
4561
4562 // If we didn't find a matching Java thread and we didn't force use of
4563 // heavyweight monitors, then the owner is the stack address of the
4564 // Lock Word in the owning Java thread's stack.
4565 //
4566 JavaThread* the_owner = NULL;
4567 DO_JAVA_THREADS(t_list, q) {
4568 if (q->is_lock_owned(owner)) {
4569 the_owner = q;
4570 break;
4571 }
4572 }
4573
4574 // cannot assert on lack of success here; see above comment
4575 return the_owner;
4576 }
4577
4578 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4579 void Threads::print_on(outputStream* st, bool print_stacks,
4580 bool internal_format, bool print_concurrent_locks,
4581 bool print_extended_info) {
4582 char buf[32];
4583 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4584
4585 st->print_cr("Full thread dump %s (%s %s):",
4586 VM_Version::vm_name(),
4587 VM_Version::vm_release(),
4588 VM_Version::vm_info_string());
4589 st->cr();
4590
4591 #if INCLUDE_SERVICES
4592 // Dump concurrent locks
4593 ConcurrentLocksDump concurrent_locks;
4594 if (print_concurrent_locks) {
4595 concurrent_locks.dump_at_safepoint();
4596 }
4597 #endif // INCLUDE_SERVICES
4598
4599 ThreadsSMRSupport::print_info_on(st);
4600 st->cr();
4601
4602 ALL_JAVA_THREADS(p) {
4603 ResourceMark rm;
4604 p->print_on(st, print_extended_info);
4605 if (print_stacks) {
4606 if (internal_format) {
4607 p->trace_stack();
4608 } else {
4609 p->print_stack_on(st);
4610 }
4611 }
4612 st->cr();
4613 #if INCLUDE_SERVICES
4614 if (print_concurrent_locks) {
4615 concurrent_locks.print_locks_on(p, st);
4616 }
4617 #endif // INCLUDE_SERVICES
4618 }
4619
4620 VMThread::vm_thread()->print_on(st);
4621 st->cr();
4622 Universe::heap()->print_gc_threads_on(st);
4623 WatcherThread* wt = WatcherThread::watcher_thread();
4624 if (wt != NULL) {
4625 wt->print_on(st);
4626 st->cr();
4627 }
4628
4629 st->flush();
4630 }
4631
4632 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4633 int buflen, bool* found_current) {
4634 if (this_thread != NULL) {
4635 bool is_current = (current == this_thread);
4636 *found_current = *found_current || is_current;
4637 st->print("%s", is_current ? "=>" : " ");
4638
4639 st->print(PTR_FORMAT, p2i(this_thread));
4640 st->print(" ");
4641 this_thread->print_on_error(st, buf, buflen);
4642 st->cr();
4643 }
4644 }
4645
4646 class PrintOnErrorClosure : public ThreadClosure {
4647 outputStream* _st;
4648 Thread* _current;
4649 char* _buf;
4650 int _buflen;
4651 bool* _found_current;
4652 public:
4653 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4654 int buflen, bool* found_current) :
4655 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4656
4657 virtual void do_thread(Thread* thread) {
4658 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4659 }
4660 };
4661
4662 // Threads::print_on_error() is called by fatal error handler. It's possible
4663 // that VM is not at safepoint and/or current thread is inside signal handler.
4664 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4665 // memory (even in resource area), it might deadlock the error handler.
4666 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4667 int buflen) {
4668 ThreadsSMRSupport::print_info_on(st);
4669 st->cr();
4670
4671 bool found_current = false;
4672 st->print_cr("Java Threads: ( => current thread )");
4673 ALL_JAVA_THREADS(thread) {
4674 print_on_error(thread, st, current, buf, buflen, &found_current);
4675 }
4676 st->cr();
4677
4678 st->print_cr("Other Threads:");
4679 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4680 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4681
4682 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4683 Universe::heap()->gc_threads_do(&print_closure);
4684
4685 if (!found_current) {
4686 st->cr();
4687 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4688 current->print_on_error(st, buf, buflen);
4689 st->cr();
4690 }
4691 st->cr();
4692
4693 st->print_cr("Threads with active compile tasks:");
4694 print_threads_compiling(st, buf, buflen);
4695 }
4696
4697 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4698 ALL_JAVA_THREADS(thread) {
4699 if (thread->is_Compiler_thread()) {
4700 CompilerThread* ct = (CompilerThread*) thread;
4701
4702 // Keep task in local variable for NULL check.
4703 // ct->_task might be set to NULL by concurring compiler thread
4704 // because it completed the compilation. The task is never freed,
4705 // though, just returned to a free list.
4706 CompileTask* task = ct->task();
4707 if (task != NULL) {
4708 thread->print_name_on_error(st, buf, buflen);
4709 task->print(st, NULL, true, true);
4710 }
4711 }
4712 }
4713 }
4714
4715
4716 // Internal SpinLock and Mutex
4717 // Based on ParkEvent
4718
4719 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4720 //
4721 // We employ SpinLocks _only for low-contention, fixed-length
4722 // short-duration critical sections where we're concerned
4723 // about native mutex_t or HotSpot Mutex:: latency.
4724 // The mux construct provides a spin-then-block mutual exclusion
4725 // mechanism.
4726 //
4727 // Testing has shown that contention on the ListLock guarding gFreeList
4728 // is common. If we implement ListLock as a simple SpinLock it's common
4729 // for the JVM to devolve to yielding with little progress. This is true
4730 // despite the fact that the critical sections protected by ListLock are
4731 // extremely short.
4732 //
4733 // TODO-FIXME: ListLock should be of type SpinLock.
4734 // We should make this a 1st-class type, integrated into the lock
4735 // hierarchy as leaf-locks. Critically, the SpinLock structure
4736 // should have sufficient padding to avoid false-sharing and excessive
4737 // cache-coherency traffic.
4738
4739
4740 typedef volatile int SpinLockT;
4741
4742 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4743 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4744 return; // normal fast-path return
4745 }
4746
4747 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4748 int ctr = 0;
4749 int Yields = 0;
4750 for (;;) {
4751 while (*adr != 0) {
4752 ++ctr;
4753 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4754 if (Yields > 5) {
4755 os::naked_short_sleep(1);
4756 } else {
4757 os::naked_yield();
4758 ++Yields;
4759 }
4760 } else {
4761 SpinPause();
4762 }
4763 }
4764 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4765 }
4766 }
4767
4768 void Thread::SpinRelease(volatile int * adr) {
4769 assert(*adr != 0, "invariant");
4770 OrderAccess::fence(); // guarantee at least release consistency.
4771 // Roach-motel semantics.
4772 // It's safe if subsequent LDs and STs float "up" into the critical section,
4773 // but prior LDs and STs within the critical section can't be allowed
4774 // to reorder or float past the ST that releases the lock.
4775 // Loads and stores in the critical section - which appear in program
4776 // order before the store that releases the lock - must also appear
4777 // before the store that releases the lock in memory visibility order.
4778 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4779 // the ST of 0 into the lock-word which releases the lock, so fence
4780 // more than covers this on all platforms.
4781 *adr = 0;
4782 }
4783
4784 // muxAcquire and muxRelease:
4785 //
4786 // * muxAcquire and muxRelease support a single-word lock-word construct.
4787 // The LSB of the word is set IFF the lock is held.
4788 // The remainder of the word points to the head of a singly-linked list
4789 // of threads blocked on the lock.
4790 //
4791 // * The current implementation of muxAcquire-muxRelease uses its own
4792 // dedicated Thread._MuxEvent instance. If we're interested in
4793 // minimizing the peak number of extant ParkEvent instances then
4794 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4795 // as certain invariants were satisfied. Specifically, care would need
4796 // to be taken with regards to consuming unpark() "permits".
4797 // A safe rule of thumb is that a thread would never call muxAcquire()
4798 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4799 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4800 // consume an unpark() permit intended for monitorenter, for instance.
4801 // One way around this would be to widen the restricted-range semaphore
4802 // implemented in park(). Another alternative would be to provide
4803 // multiple instances of the PlatformEvent() for each thread. One
4804 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4805 //
4806 // * Usage:
4807 // -- Only as leaf locks
4808 // -- for short-term locking only as muxAcquire does not perform
4809 // thread state transitions.
4810 //
4811 // Alternatives:
4812 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4813 // but with parking or spin-then-park instead of pure spinning.
4814 // * Use Taura-Oyama-Yonenzawa locks.
4815 // * It's possible to construct a 1-0 lock if we encode the lockword as
4816 // (List,LockByte). Acquire will CAS the full lockword while Release
4817 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4818 // acquiring threads use timers (ParkTimed) to detect and recover from
4819 // the stranding window. Thread/Node structures must be aligned on 256-byte
4820 // boundaries by using placement-new.
4821 // * Augment MCS with advisory back-link fields maintained with CAS().
4822 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4823 // The validity of the backlinks must be ratified before we trust the value.
4824 // If the backlinks are invalid the exiting thread must back-track through the
4825 // the forward links, which are always trustworthy.
4826 // * Add a successor indication. The LockWord is currently encoded as
4827 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4828 // to provide the usual futile-wakeup optimization.
4829 // See RTStt for details.
4830 //
4831
4832
4833 const intptr_t LOCKBIT = 1;
4834
4835 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4836 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4837 if (w == 0) return;
4838 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4839 return;
4840 }
4841
4842 ParkEvent * const Self = Thread::current()->_MuxEvent;
4843 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4844 for (;;) {
4845 int its = (os::is_MP() ? 100 : 0) + 1;
4846
4847 // Optional spin phase: spin-then-park strategy
4848 while (--its >= 0) {
4849 w = *Lock;
4850 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4851 return;
4852 }
4853 }
4854
4855 Self->reset();
4856 Self->OnList = intptr_t(Lock);
4857 // The following fence() isn't _strictly necessary as the subsequent
4858 // CAS() both serializes execution and ratifies the fetched *Lock value.
4859 OrderAccess::fence();
4860 for (;;) {
4861 w = *Lock;
4862 if ((w & LOCKBIT) == 0) {
4863 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4864 Self->OnList = 0; // hygiene - allows stronger asserts
4865 return;
4866 }
4867 continue; // Interference -- *Lock changed -- Just retry
4868 }
4869 assert(w & LOCKBIT, "invariant");
4870 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4871 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4872 }
4873
4874 while (Self->OnList != 0) {
4875 Self->park();
4876 }
4877 }
4878 }
4879
4880 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4881 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4882 if (w == 0) return;
4883 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4884 return;
4885 }
4886
4887 ParkEvent * ReleaseAfter = NULL;
4888 if (ev == NULL) {
4889 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4890 }
4891 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4892 for (;;) {
4893 guarantee(ev->OnList == 0, "invariant");
4894 int its = (os::is_MP() ? 100 : 0) + 1;
4895
4896 // Optional spin phase: spin-then-park strategy
4897 while (--its >= 0) {
4898 w = *Lock;
4899 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4900 if (ReleaseAfter != NULL) {
4901 ParkEvent::Release(ReleaseAfter);
4902 }
4903 return;
4904 }
4905 }
4906
4907 ev->reset();
4908 ev->OnList = intptr_t(Lock);
4909 // The following fence() isn't _strictly necessary as the subsequent
4910 // CAS() both serializes execution and ratifies the fetched *Lock value.
4911 OrderAccess::fence();
4912 for (;;) {
4913 w = *Lock;
4914 if ((w & LOCKBIT) == 0) {
4915 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4916 ev->OnList = 0;
4917 // We call ::Release while holding the outer lock, thus
4918 // artificially lengthening the critical section.
4919 // Consider deferring the ::Release() until the subsequent unlock(),
4920 // after we've dropped the outer lock.
4921 if (ReleaseAfter != NULL) {
4922 ParkEvent::Release(ReleaseAfter);
4923 }
4924 return;
4925 }
4926 continue; // Interference -- *Lock changed -- Just retry
4927 }
4928 assert(w & LOCKBIT, "invariant");
4929 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4930 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4931 }
4932
4933 while (ev->OnList != 0) {
4934 ev->park();
4935 }
4936 }
4937 }
4938
4939 // Release() must extract a successor from the list and then wake that thread.
4940 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4941 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4942 // Release() would :
4943 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4944 // (B) Extract a successor from the private list "in-hand"
4945 // (C) attempt to CAS() the residual back into *Lock over null.
4946 // If there were any newly arrived threads and the CAS() would fail.
4947 // In that case Release() would detach the RATs, re-merge the list in-hand
4948 // with the RATs and repeat as needed. Alternately, Release() might
4949 // detach and extract a successor, but then pass the residual list to the wakee.
4950 // The wakee would be responsible for reattaching and remerging before it
4951 // competed for the lock.
4952 //
4953 // Both "pop" and DMR are immune from ABA corruption -- there can be
4954 // multiple concurrent pushers, but only one popper or detacher.
4955 // This implementation pops from the head of the list. This is unfair,
4956 // but tends to provide excellent throughput as hot threads remain hot.
4957 // (We wake recently run threads first).
4958 //
4959 // All paths through muxRelease() will execute a CAS.
4960 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4961 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4962 // executed within the critical section are complete and globally visible before the
4963 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4964 void Thread::muxRelease(volatile intptr_t * Lock) {
4965 for (;;) {
4966 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4967 assert(w & LOCKBIT, "invariant");
4968 if (w == LOCKBIT) return;
4969 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4970 assert(List != NULL, "invariant");
4971 assert(List->OnList == intptr_t(Lock), "invariant");
4972 ParkEvent * const nxt = List->ListNext;
4973 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4974
4975 // The following CAS() releases the lock and pops the head element.
4976 // The CAS() also ratifies the previously fetched lock-word value.
4977 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4978 continue;
4979 }
4980 List->OnList = 0;
4981 OrderAccess::fence();
4982 List->unpark();
4983 return;
4984 }
4985 }
4986
4987
4988 void Threads::verify() {
4989 ALL_JAVA_THREADS(p) {
4990 p->verify();
4991 }
4992 VMThread* thread = VMThread::vm_thread();
4993 if (thread != NULL) thread->verify();
4994 }