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 (os::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_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
374 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
375 os::current_thread_id(), p2i(stack_base() - stack_size()),
376 p2i(stack_base()), stack_size()/1024);
377
378 // Invoke <ChildClass>::run()
379 this->run();
380 // Returned from <ChildClass>::run(). Thread finished.
381
382 // Note: at this point the thread object may already have deleted itself.
383 // So from here on do not dereference *this*.
384
385 // If a thread has not deleted itself ("delete this") as part of its
386 // termination sequence, we have to ensure thread-local-storage is
387 // cleared before we actually terminate. No threads should ever be
388 // deleted asynchronously with respect to their termination.
389 if (Thread::current_or_null_safe() != NULL) {
390 assert(Thread::current_or_null_safe() == this, "current thread is wrong");
391 Thread::clear_thread_current();
392 }
393
394 }
395
396 Thread::~Thread() {
397 JFR_ONLY(Jfr::on_thread_destruct(this);)
398
399 // Notify the barrier set that a thread is being destroyed. Note that a barrier
400 // set might not be available if we encountered errors during bootstrapping.
401 BarrierSet* const barrier_set = BarrierSet::barrier_set();
402 if (barrier_set != NULL) {
403 barrier_set->on_thread_destroy(this);
404 }
405
406
407 // stack_base can be NULL if the thread is never started or exited before
408 // record_stack_base_and_size called. Although, we would like to ensure
409 // that all started threads do call record_stack_base_and_size(), there is
410 // not proper way to enforce that.
411 #if INCLUDE_NMT
412 if (_stack_base != NULL) {
413 MemTracker::release_thread_stack(stack_end(), stack_size());
414 #ifdef ASSERT
415 set_stack_base(NULL);
416 #endif
417 }
418 #endif // INCLUDE_NMT
419
420 // deallocate data structures
421 delete resource_area();
422 // since the handle marks are using the handle area, we have to deallocated the root
423 // handle mark before deallocating the thread's handle area,
424 assert(last_handle_mark() != NULL, "check we have an element");
425 delete last_handle_mark();
426 assert(last_handle_mark() == NULL, "check we have reached the end");
427
428 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
429 // We NULL out the fields for good hygiene.
430 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
431 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
432 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
433 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
434
435 delete handle_area();
436 delete metadata_handles();
437
438 // SR_handler uses this as a termination indicator -
439 // needs to happen before os::free_thread()
440 delete _SR_lock;
441 _SR_lock = NULL;
442
443 // osthread() can be NULL, if creation of thread failed.
444 if (osthread() != NULL) os::free_thread(osthread());
445
446 // clear Thread::current if thread is deleting itself.
447 // Needed to ensure JNI correctly detects non-attached threads.
448 if (this == Thread::current()) {
449 Thread::clear_thread_current();
450 }
451
452 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
453 }
454
455 #ifdef ASSERT
456 // A JavaThread is considered "dangling" if it is not the current
457 // thread, has been added the Threads list, the system is not at a
458 // safepoint and the Thread is not "protected".
459 //
460 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
461 assert(!thread->is_Java_thread() || Thread::current() == thread ||
462 !((JavaThread *) thread)->on_thread_list() ||
463 SafepointSynchronize::is_at_safepoint() ||
464 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
465 "possibility of dangling Thread pointer");
466 }
467 #endif
468
469 ThreadPriority Thread::get_priority(const Thread* const thread) {
470 ThreadPriority priority;
471 // Can return an error!
472 (void)os::get_priority(thread, priority);
473 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
474 return priority;
475 }
476
477 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
478 debug_only(check_for_dangling_thread_pointer(thread);)
479 // Can return an error!
480 (void)os::set_priority(thread, priority);
481 }
482
483
484 void Thread::start(Thread* thread) {
485 // Start is different from resume in that its safety is guaranteed by context or
486 // being called from a Java method synchronized on the Thread object.
487 if (!DisableStartThread) {
488 if (thread->is_Java_thread()) {
489 // Initialize the thread state to RUNNABLE before starting this thread.
490 // Can not set it after the thread started because we do not know the
491 // exact thread state at that time. It could be in MONITOR_WAIT or
492 // in SLEEPING or some other state.
493 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
494 java_lang_Thread::RUNNABLE);
495 }
496 os::start_thread(thread);
497 }
498 }
499
500 // Enqueue a VM_Operation to do the job for us - sometime later
501 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
502 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
503 VMThread::execute(vm_stop);
504 }
505
506
507 // Check if an external suspend request has completed (or has been
508 // cancelled). Returns true if the thread is externally suspended and
509 // false otherwise.
510 //
511 // The bits parameter returns information about the code path through
512 // the routine. Useful for debugging:
513 //
514 // set in is_ext_suspend_completed():
515 // 0x00000001 - routine was entered
516 // 0x00000010 - routine return false at end
517 // 0x00000100 - thread exited (return false)
518 // 0x00000200 - suspend request cancelled (return false)
519 // 0x00000400 - thread suspended (return true)
520 // 0x00001000 - thread is in a suspend equivalent state (return true)
521 // 0x00002000 - thread is native and walkable (return true)
522 // 0x00004000 - thread is native_trans and walkable (needed retry)
523 //
524 // set in wait_for_ext_suspend_completion():
525 // 0x00010000 - routine was entered
526 // 0x00020000 - suspend request cancelled before loop (return false)
527 // 0x00040000 - thread suspended before loop (return true)
528 // 0x00080000 - suspend request cancelled in loop (return false)
529 // 0x00100000 - thread suspended in loop (return true)
530 // 0x00200000 - suspend not completed during retry loop (return false)
531
532 // Helper class for tracing suspend wait debug bits.
533 //
534 // 0x00000100 indicates that the target thread exited before it could
535 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
536 // 0x00080000 each indicate a cancelled suspend request so they don't
537 // count as wait failures either.
538 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
539
540 class TraceSuspendDebugBits : public StackObj {
541 private:
542 JavaThread * jt;
543 bool is_wait;
544 bool called_by_wait; // meaningful when !is_wait
545 uint32_t * bits;
546
547 public:
548 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
549 uint32_t *_bits) {
550 jt = _jt;
551 is_wait = _is_wait;
552 called_by_wait = _called_by_wait;
553 bits = _bits;
554 }
555
556 ~TraceSuspendDebugBits() {
557 if (!is_wait) {
558 #if 1
559 // By default, don't trace bits for is_ext_suspend_completed() calls.
560 // That trace is very chatty.
561 return;
562 #else
563 if (!called_by_wait) {
564 // If tracing for is_ext_suspend_completed() is enabled, then only
565 // trace calls to it from wait_for_ext_suspend_completion()
566 return;
567 }
568 #endif
569 }
570
571 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
572 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
573 MutexLocker ml(Threads_lock); // needed for get_thread_name()
574 ResourceMark rm;
575
576 tty->print_cr(
577 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
578 jt->get_thread_name(), *bits);
579
580 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
581 }
582 }
583 }
584 };
585 #undef DEBUG_FALSE_BITS
586
587
588 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
589 uint32_t *bits) {
590 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
591
592 bool did_trans_retry = false; // only do thread_in_native_trans retry once
593 bool do_trans_retry; // flag to force the retry
594
595 *bits |= 0x00000001;
596
597 do {
598 do_trans_retry = false;
599
600 if (is_exiting()) {
601 // Thread is in the process of exiting. This is always checked
602 // first to reduce the risk of dereferencing a freed JavaThread.
603 *bits |= 0x00000100;
604 return false;
605 }
606
607 if (!is_external_suspend()) {
608 // Suspend request is cancelled. This is always checked before
609 // is_ext_suspended() to reduce the risk of a rogue resume
610 // confusing the thread that made the suspend request.
611 *bits |= 0x00000200;
612 return false;
613 }
614
615 if (is_ext_suspended()) {
616 // thread is suspended
617 *bits |= 0x00000400;
618 return true;
619 }
620
621 // Now that we no longer do hard suspends of threads running
622 // native code, the target thread can be changing thread state
623 // while we are in this routine:
624 //
625 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
626 //
627 // We save a copy of the thread state as observed at this moment
628 // and make our decision about suspend completeness based on the
629 // copy. This closes the race where the thread state is seen as
630 // _thread_in_native_trans in the if-thread_blocked check, but is
631 // seen as _thread_blocked in if-thread_in_native_trans check.
632 JavaThreadState save_state = thread_state();
633
634 if (save_state == _thread_blocked && is_suspend_equivalent()) {
635 // If the thread's state is _thread_blocked and this blocking
636 // condition is known to be equivalent to a suspend, then we can
637 // consider the thread to be externally suspended. This means that
638 // the code that sets _thread_blocked has been modified to do
639 // self-suspension if the blocking condition releases. We also
640 // used to check for CONDVAR_WAIT here, but that is now covered by
641 // the _thread_blocked with self-suspension check.
642 //
643 // Return true since we wouldn't be here unless there was still an
644 // external suspend request.
645 *bits |= 0x00001000;
646 return true;
647 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
648 // Threads running native code will self-suspend on native==>VM/Java
649 // transitions. If its stack is walkable (should always be the case
650 // unless this function is called before the actual java_suspend()
651 // call), then the wait is done.
652 *bits |= 0x00002000;
653 return true;
654 } else if (!called_by_wait && !did_trans_retry &&
655 save_state == _thread_in_native_trans &&
656 frame_anchor()->walkable()) {
657 // The thread is transitioning from thread_in_native to another
658 // thread state. check_safepoint_and_suspend_for_native_trans()
659 // will force the thread to self-suspend. If it hasn't gotten
660 // there yet we may have caught the thread in-between the native
661 // code check above and the self-suspend. Lucky us. If we were
662 // called by wait_for_ext_suspend_completion(), then it
663 // will be doing the retries so we don't have to.
664 //
665 // Since we use the saved thread state in the if-statement above,
666 // there is a chance that the thread has already transitioned to
667 // _thread_blocked by the time we get here. In that case, we will
668 // make a single unnecessary pass through the logic below. This
669 // doesn't hurt anything since we still do the trans retry.
670
671 *bits |= 0x00004000;
672
673 // Once the thread leaves thread_in_native_trans for another
674 // thread state, we break out of this retry loop. We shouldn't
675 // need this flag to prevent us from getting back here, but
676 // sometimes paranoia is good.
677 did_trans_retry = true;
678
679 // We wait for the thread to transition to a more usable state.
680 for (int i = 1; i <= SuspendRetryCount; i++) {
681 // We used to do an "os::yield_all(i)" call here with the intention
682 // that yielding would increase on each retry. However, the parameter
683 // is ignored on Linux which means the yield didn't scale up. Waiting
684 // on the SR_lock below provides a much more predictable scale up for
685 // the delay. It also provides a simple/direct point to check for any
686 // safepoint requests from the VMThread
687
688 // temporarily drops SR_lock while doing wait with safepoint check
689 // (if we're a JavaThread - the WatcherThread can also call this)
690 // and increase delay with each retry
691 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
692
693 // check the actual thread state instead of what we saved above
694 if (thread_state() != _thread_in_native_trans) {
695 // the thread has transitioned to another thread state so
696 // try all the checks (except this one) one more time.
697 do_trans_retry = true;
698 break;
699 }
700 } // end retry loop
701
702
703 }
704 } while (do_trans_retry);
705
706 *bits |= 0x00000010;
707 return false;
708 }
709
710 // Wait for an external suspend request to complete (or be cancelled).
711 // Returns true if the thread is externally suspended and false otherwise.
712 //
713 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
714 uint32_t *bits) {
715 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
716 false /* !called_by_wait */, bits);
717
718 // local flag copies to minimize SR_lock hold time
719 bool is_suspended;
720 bool pending;
721 uint32_t reset_bits;
722
723 // set a marker so is_ext_suspend_completed() knows we are the caller
724 *bits |= 0x00010000;
725
726 // We use reset_bits to reinitialize the bits value at the top of
727 // each retry loop. This allows the caller to make use of any
728 // unused bits for their own marking purposes.
729 reset_bits = *bits;
730
731 {
732 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
733 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
734 delay, bits);
735 pending = is_external_suspend();
736 }
737 // must release SR_lock to allow suspension to complete
738
739 if (!pending) {
740 // A cancelled suspend request is the only false return from
741 // is_ext_suspend_completed() that keeps us from entering the
742 // retry loop.
743 *bits |= 0x00020000;
744 return false;
745 }
746
747 if (is_suspended) {
748 *bits |= 0x00040000;
749 return true;
750 }
751
752 for (int i = 1; i <= retries; i++) {
753 *bits = reset_bits; // reinit to only track last retry
754
755 // We used to do an "os::yield_all(i)" call here with the intention
756 // that yielding would increase on each retry. However, the parameter
757 // is ignored on Linux which means the yield didn't scale up. Waiting
758 // on the SR_lock below provides a much more predictable scale up for
759 // the delay. It also provides a simple/direct point to check for any
760 // safepoint requests from the VMThread
761
762 {
763 MutexLocker ml(SR_lock());
764 // wait with safepoint check (if we're a JavaThread - the WatcherThread
765 // can also call this) and increase delay with each retry
766 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
767
768 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
769 delay, bits);
770
771 // It is possible for the external suspend request to be cancelled
772 // (by a resume) before the actual suspend operation is completed.
773 // Refresh our local copy to see if we still need to wait.
774 pending = is_external_suspend();
775 }
776
777 if (!pending) {
778 // A cancelled suspend request is the only false return from
779 // is_ext_suspend_completed() that keeps us from staying in the
780 // retry loop.
781 *bits |= 0x00080000;
782 return false;
783 }
784
785 if (is_suspended) {
786 *bits |= 0x00100000;
787 return true;
788 }
789 } // end retry loop
790
791 // thread did not suspend after all our retries
792 *bits |= 0x00200000;
793 return false;
794 }
795
796 // Called from API entry points which perform stack walking. If the
797 // associated JavaThread is the current thread, then wait_for_suspend
798 // is not used. Otherwise, it determines if we should wait for the
799 // "other" thread to complete external suspension. (NOTE: in future
800 // releases the suspension mechanism should be reimplemented so this
801 // is not necessary.)
802 //
803 bool
804 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
805 if (this != JavaThread::current()) {
806 // "other" threads require special handling.
807 if (wait_for_suspend) {
808 // We are allowed to wait for the external suspend to complete
809 // so give the other thread a chance to get suspended.
810 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
811 SuspendRetryDelay, bits)) {
812 // Didn't make it so let the caller know.
813 return false;
814 }
815 }
816 // We aren't allowed to wait for the external suspend to complete
817 // so if the other thread isn't externally suspended we need to
818 // let the caller know.
819 else if (!is_ext_suspend_completed_with_lock(bits)) {
820 return false;
821 }
822 }
823
824 return true;
825 }
826
827 #ifndef PRODUCT
828 void JavaThread::record_jump(address target, address instr, const char* file,
829 int line) {
830
831 // This should not need to be atomic as the only way for simultaneous
832 // updates is via interrupts. Even then this should be rare or non-existent
833 // and we don't care that much anyway.
834
835 int index = _jmp_ring_index;
836 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
837 _jmp_ring[index]._target = (intptr_t) target;
838 _jmp_ring[index]._instruction = (intptr_t) instr;
839 _jmp_ring[index]._file = file;
840 _jmp_ring[index]._line = line;
841 }
842 #endif // PRODUCT
843
844 void Thread::interrupt(Thread* thread) {
845 debug_only(check_for_dangling_thread_pointer(thread);)
846 os::interrupt(thread);
847 }
848
849 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
850 debug_only(check_for_dangling_thread_pointer(thread);)
851 // Note: If clear_interrupted==false, this simply fetches and
852 // returns the value of the field osthread()->interrupted().
853 return os::is_interrupted(thread, clear_interrupted);
854 }
855
856
857 // GC Support
858 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
859 int thread_parity = _oops_do_parity;
860 if (thread_parity != strong_roots_parity) {
861 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
862 if (res == thread_parity) {
863 return true;
864 } else {
865 guarantee(res == strong_roots_parity, "Or else what?");
866 return false;
867 }
868 }
869 return false;
870 }
871
872 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
873 active_handles()->oops_do(f);
874 // Do oop for ThreadShadow
875 f->do_oop((oop*)&_pending_exception);
876 handle_area()->oops_do(f);
877
878 // We scan thread local monitor lists here, and the remaining global
879 // monitors in ObjectSynchronizer::oops_do().
880 ObjectSynchronizer::thread_local_used_oops_do(this, f);
881 }
882
883 void Thread::metadata_handles_do(void f(Metadata*)) {
884 // Only walk the Handles in Thread.
885 if (metadata_handles() != NULL) {
886 for (int i = 0; i< metadata_handles()->length(); i++) {
887 f(metadata_handles()->at(i));
888 }
889 }
890 }
891
892 void Thread::print_on(outputStream* st, bool print_extended_info) const {
893 // get_priority assumes osthread initialized
894 if (osthread() != NULL) {
895 int os_prio;
896 if (os::get_native_priority(this, &os_prio) == OS_OK) {
897 st->print("os_prio=%d ", os_prio);
898 }
899
900 st->print("cpu=%.2fms ",
901 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
902 );
903 st->print("elapsed=%.2fs ",
904 _statistical_info.getElapsedTime() / 1000.0
905 );
906 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
907 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
908 st->print("allocated=" SIZE_FORMAT "%s ",
909 byte_size_in_proper_unit(allocated_bytes),
910 proper_unit_for_byte_size(allocated_bytes)
911 );
912 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
913 }
914
915 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
916 osthread()->print_on(st);
917 }
918 ThreadsSMRSupport::print_info_on(this, st);
919 st->print(" ");
920 debug_only(if (WizardMode) print_owned_locks_on(st);)
921 }
922
923 // Thread::print_on_error() is called by fatal error handler. Don't use
924 // any lock or allocate memory.
925 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
926 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
927
928 if (is_VM_thread()) { st->print("VMThread"); }
929 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
930 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
931 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
932 else { st->print("Thread"); }
933
934 if (is_Named_thread()) {
935 st->print(" \"%s\"", name());
936 }
937
938 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
939 p2i(stack_end()), p2i(stack_base()));
940
941 if (osthread()) {
942 st->print(" [id=%d]", osthread()->thread_id());
943 }
944
945 ThreadsSMRSupport::print_info_on(this, st);
946 }
947
948 void Thread::print_value_on(outputStream* st) const {
949 if (is_Named_thread()) {
950 st->print(" \"%s\" ", name());
951 }
952 st->print(INTPTR_FORMAT, p2i(this)); // print address
953 }
954
955 #ifdef ASSERT
956 void Thread::print_owned_locks_on(outputStream* st) const {
957 Monitor *cur = _owned_locks;
958 if (cur == NULL) {
959 st->print(" (no locks) ");
960 } else {
961 st->print_cr(" Locks owned:");
962 while (cur) {
963 cur->print_on(st);
964 cur = cur->next();
965 }
966 }
967 }
968
969 static int ref_use_count = 0;
970
971 bool Thread::owns_locks_but_compiled_lock() const {
972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
973 if (cur != Compile_lock) return true;
974 }
975 return false;
976 }
977
978
979 #endif
980
981 #ifndef PRODUCT
982
983 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
984 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
985 // no locks which allow_vm_block's are held
986 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
987 // Check if current thread is allowed to block at a safepoint
988 if (!(_allow_safepoint_count == 0)) {
989 fatal("Possible safepoint reached by thread that does not allow it");
990 }
991 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
992 fatal("LEAF method calling lock?");
993 }
994
995 #ifdef ASSERT
996 if (potential_vm_operation && is_Java_thread()
997 && !Universe::is_bootstrapping()) {
998 // Make sure we do not hold any locks that the VM thread also uses.
999 // This could potentially lead to deadlocks
1000 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1001 // Threads_lock is special, since the safepoint synchronization will not start before this is
1002 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1003 // since it is used to transfer control between JavaThreads and the VMThread
1004 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1005 if ((cur->allow_vm_block() &&
1006 cur != Threads_lock &&
1007 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1008 cur != VMOperationRequest_lock &&
1009 cur != VMOperationQueue_lock) ||
1010 cur->rank() == Mutex::special) {
1011 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1012 }
1013 }
1014 }
1015
1016 if (GCALotAtAllSafepoints) {
1017 // We could enter a safepoint here and thus have a gc
1018 InterfaceSupport::check_gc_alot();
1019 }
1020 #endif
1021 }
1022 #endif
1023
1024 bool Thread::is_in_stack(address adr) const {
1025 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1026 address end = os::current_stack_pointer();
1027 // Allow non Java threads to call this without stack_base
1028 if (_stack_base == NULL) return true;
1029 if (stack_base() >= adr && adr >= end) return true;
1030
1031 return false;
1032 }
1033
1034 bool Thread::is_in_usable_stack(address adr) const {
1035 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1036 size_t usable_stack_size = _stack_size - stack_guard_size;
1037
1038 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1039 }
1040
1041
1042 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1043 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1044 // used for compilation in the future. If that change is made, the need for these methods
1045 // should be revisited, and they should be removed if possible.
1046
1047 bool Thread::is_lock_owned(address adr) const {
1048 return on_local_stack(adr);
1049 }
1050
1051 bool Thread::set_as_starting_thread() {
1052 // NOTE: this must be called inside the main thread.
1053 return os::create_main_thread((JavaThread*)this);
1054 }
1055
1056 static void initialize_class(Symbol* class_name, TRAPS) {
1057 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1058 InstanceKlass::cast(klass)->initialize(CHECK);
1059 }
1060
1061
1062 // Creates the initial ThreadGroup
1063 static Handle create_initial_thread_group(TRAPS) {
1064 Handle system_instance = JavaCalls::construct_new_instance(
1065 SystemDictionary::ThreadGroup_klass(),
1066 vmSymbols::void_method_signature(),
1067 CHECK_NH);
1068 Universe::set_system_thread_group(system_instance());
1069
1070 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1071 Handle main_instance = JavaCalls::construct_new_instance(
1072 SystemDictionary::ThreadGroup_klass(),
1073 vmSymbols::threadgroup_string_void_signature(),
1074 system_instance,
1075 string,
1076 CHECK_NH);
1077 return main_instance;
1078 }
1079
1080 // Creates the initial Thread
1081 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1082 TRAPS) {
1083 InstanceKlass* ik = SystemDictionary::Thread_klass();
1084 assert(ik->is_initialized(), "must be");
1085 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1086
1087 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1088 // constructor calls Thread.current(), which must be set here for the
1089 // initial thread.
1090 java_lang_Thread::set_thread(thread_oop(), thread);
1091 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1092 thread->set_threadObj(thread_oop());
1093
1094 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1095
1096 JavaValue result(T_VOID);
1097 JavaCalls::call_special(&result, thread_oop,
1098 ik,
1099 vmSymbols::object_initializer_name(),
1100 vmSymbols::threadgroup_string_void_signature(),
1101 thread_group,
1102 string,
1103 CHECK_NULL);
1104 return thread_oop();
1105 }
1106
1107 char java_runtime_name[128] = "";
1108 char java_runtime_version[128] = "";
1109
1110 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1111 static const char* get_java_runtime_name(TRAPS) {
1112 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1113 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1114 fieldDescriptor fd;
1115 bool found = k != NULL &&
1116 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1117 vmSymbols::string_signature(), &fd);
1118 if (found) {
1119 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1120 if (name_oop == NULL) {
1121 return NULL;
1122 }
1123 const char* name = java_lang_String::as_utf8_string(name_oop,
1124 java_runtime_name,
1125 sizeof(java_runtime_name));
1126 return name;
1127 } else {
1128 return NULL;
1129 }
1130 }
1131
1132 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1133 static const char* get_java_runtime_version(TRAPS) {
1134 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1135 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1136 fieldDescriptor fd;
1137 bool found = k != NULL &&
1138 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1139 vmSymbols::string_signature(), &fd);
1140 if (found) {
1141 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1142 if (name_oop == NULL) {
1143 return NULL;
1144 }
1145 const char* name = java_lang_String::as_utf8_string(name_oop,
1146 java_runtime_version,
1147 sizeof(java_runtime_version));
1148 return name;
1149 } else {
1150 return NULL;
1151 }
1152 }
1153
1154 // General purpose hook into Java code, run once when the VM is initialized.
1155 // The Java library method itself may be changed independently from the VM.
1156 static void call_postVMInitHook(TRAPS) {
1157 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1158 if (klass != NULL) {
1159 JavaValue result(T_VOID);
1160 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1161 vmSymbols::void_method_signature(),
1162 CHECK);
1163 }
1164 }
1165
1166 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1167 bool daemon, TRAPS) {
1168 assert(thread_group.not_null(), "thread group should be specified");
1169 assert(threadObj() == NULL, "should only create Java thread object once");
1170
1171 InstanceKlass* ik = SystemDictionary::Thread_klass();
1172 assert(ik->is_initialized(), "must be");
1173 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1174
1175 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1176 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1177 // constructor calls Thread.current(), which must be set here.
1178 java_lang_Thread::set_thread(thread_oop(), this);
1179 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1180 set_threadObj(thread_oop());
1181
1182 JavaValue result(T_VOID);
1183 if (thread_name != NULL) {
1184 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1185 // Thread gets assigned specified name and null target
1186 JavaCalls::call_special(&result,
1187 thread_oop,
1188 ik,
1189 vmSymbols::object_initializer_name(),
1190 vmSymbols::threadgroup_string_void_signature(),
1191 thread_group,
1192 name,
1193 THREAD);
1194 } else {
1195 // Thread gets assigned name "Thread-nnn" and null target
1196 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1197 JavaCalls::call_special(&result,
1198 thread_oop,
1199 ik,
1200 vmSymbols::object_initializer_name(),
1201 vmSymbols::threadgroup_runnable_void_signature(),
1202 thread_group,
1203 Handle(),
1204 THREAD);
1205 }
1206
1207
1208 if (daemon) {
1209 java_lang_Thread::set_daemon(thread_oop());
1210 }
1211
1212 if (HAS_PENDING_EXCEPTION) {
1213 return;
1214 }
1215
1216 Klass* group = SystemDictionary::ThreadGroup_klass();
1217 Handle threadObj(THREAD, this->threadObj());
1218
1219 JavaCalls::call_special(&result,
1220 thread_group,
1221 group,
1222 vmSymbols::add_method_name(),
1223 vmSymbols::thread_void_signature(),
1224 threadObj, // Arg 1
1225 THREAD);
1226 }
1227
1228 // List of all NonJavaThreads and safe iteration over that list.
1229
1230 class NonJavaThread::List {
1231 public:
1232 NonJavaThread* volatile _head;
1233 SingleWriterSynchronizer _protect;
1234
1235 List() : _head(NULL), _protect() {}
1236 };
1237
1238 NonJavaThread::List NonJavaThread::_the_list;
1239
1240 NonJavaThread::Iterator::Iterator() :
1241 _protect_enter(_the_list._protect.enter()),
1242 _current(OrderAccess::load_acquire(&_the_list._head))
1243 {}
1244
1245 NonJavaThread::Iterator::~Iterator() {
1246 _the_list._protect.exit(_protect_enter);
1247 }
1248
1249 void NonJavaThread::Iterator::step() {
1250 assert(!end(), "precondition");
1251 _current = OrderAccess::load_acquire(&_current->_next);
1252 }
1253
1254 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1255 // Add this thread to _the_list.
1256 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1257 _next = _the_list._head;
1258 OrderAccess::release_store(&_the_list._head, this);
1259 }
1260
1261 NonJavaThread::~NonJavaThread() {
1262 // Remove this thread from _the_list.
1263 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1264 NonJavaThread* volatile* p = &_the_list._head;
1265 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1266 if (t == this) {
1267 *p = this->_next;
1268 // Wait for any in-progress iterators.
1269 _the_list._protect.synchronize();
1270 break;
1271 }
1272 }
1273 }
1274
1275 // NamedThread -- non-JavaThread subclasses with multiple
1276 // uniquely named instances should derive from this.
1277 NamedThread::NamedThread() :
1278 NonJavaThread(),
1279 _name(NULL),
1280 _processed_thread(NULL),
1281 _gc_id(GCId::undefined())
1282 {}
1283
1284 NamedThread::~NamedThread() {
1285 if (_name != NULL) {
1286 FREE_C_HEAP_ARRAY(char, _name);
1287 _name = NULL;
1288 }
1289 }
1290
1291 void NamedThread::set_name(const char* format, ...) {
1292 guarantee(_name == NULL, "Only get to set name once.");
1293 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1294 guarantee(_name != NULL, "alloc failure");
1295 va_list ap;
1296 va_start(ap, format);
1297 jio_vsnprintf(_name, max_name_len, format, ap);
1298 va_end(ap);
1299 }
1300
1301 void NamedThread::initialize_named_thread() {
1302 set_native_thread_name(name());
1303 }
1304
1305 void NamedThread::print_on(outputStream* st) const {
1306 st->print("\"%s\" ", name());
1307 Thread::print_on(st);
1308 st->cr();
1309 }
1310
1311
1312 // ======= WatcherThread ========
1313
1314 // The watcher thread exists to simulate timer interrupts. It should
1315 // be replaced by an abstraction over whatever native support for
1316 // timer interrupts exists on the platform.
1317
1318 WatcherThread* WatcherThread::_watcher_thread = NULL;
1319 bool WatcherThread::_startable = false;
1320 volatile bool WatcherThread::_should_terminate = false;
1321
1322 WatcherThread::WatcherThread() : NonJavaThread() {
1323 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1324 if (os::create_thread(this, os::watcher_thread)) {
1325 _watcher_thread = this;
1326
1327 // Set the watcher thread to the highest OS priority which should not be
1328 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1329 // is created. The only normal thread using this priority is the reference
1330 // handler thread, which runs for very short intervals only.
1331 // If the VMThread's priority is not lower than the WatcherThread profiling
1332 // will be inaccurate.
1333 os::set_priority(this, MaxPriority);
1334 if (!DisableStartThread) {
1335 os::start_thread(this);
1336 }
1337 }
1338 }
1339
1340 int WatcherThread::sleep() const {
1341 // The WatcherThread does not participate in the safepoint protocol
1342 // for the PeriodicTask_lock because it is not a JavaThread.
1343 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1344
1345 if (_should_terminate) {
1346 // check for termination before we do any housekeeping or wait
1347 return 0; // we did not sleep.
1348 }
1349
1350 // remaining will be zero if there are no tasks,
1351 // causing the WatcherThread to sleep until a task is
1352 // enrolled
1353 int remaining = PeriodicTask::time_to_wait();
1354 int time_slept = 0;
1355
1356 // we expect this to timeout - we only ever get unparked when
1357 // we should terminate or when a new task has been enrolled
1358 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1359
1360 jlong time_before_loop = os::javaTimeNanos();
1361
1362 while (true) {
1363 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1364 remaining);
1365 jlong now = os::javaTimeNanos();
1366
1367 if (remaining == 0) {
1368 // if we didn't have any tasks we could have waited for a long time
1369 // consider the time_slept zero and reset time_before_loop
1370 time_slept = 0;
1371 time_before_loop = now;
1372 } else {
1373 // need to recalculate since we might have new tasks in _tasks
1374 time_slept = (int) ((now - time_before_loop) / 1000000);
1375 }
1376
1377 // Change to task list or spurious wakeup of some kind
1378 if (timedout || _should_terminate) {
1379 break;
1380 }
1381
1382 remaining = PeriodicTask::time_to_wait();
1383 if (remaining == 0) {
1384 // Last task was just disenrolled so loop around and wait until
1385 // another task gets enrolled
1386 continue;
1387 }
1388
1389 remaining -= time_slept;
1390 if (remaining <= 0) {
1391 break;
1392 }
1393 }
1394
1395 return time_slept;
1396 }
1397
1398 void WatcherThread::run() {
1399 assert(this == watcher_thread(), "just checking");
1400
1401 this->set_native_thread_name(this->name());
1402 this->set_active_handles(JNIHandleBlock::allocate_block());
1403 while (true) {
1404 assert(watcher_thread() == Thread::current(), "thread consistency check");
1405 assert(watcher_thread() == this, "thread consistency check");
1406
1407 // Calculate how long it'll be until the next PeriodicTask work
1408 // should be done, and sleep that amount of time.
1409 int time_waited = sleep();
1410
1411 if (VMError::is_error_reported()) {
1412 // A fatal error has happened, the error handler(VMError::report_and_die)
1413 // should abort JVM after creating an error log file. However in some
1414 // rare cases, the error handler itself might deadlock. Here periodically
1415 // check for error reporting timeouts, and if it happens, just proceed to
1416 // abort the VM.
1417
1418 // This code is in WatcherThread because WatcherThread wakes up
1419 // periodically so the fatal error handler doesn't need to do anything;
1420 // also because the WatcherThread is less likely to crash than other
1421 // threads.
1422
1423 for (;;) {
1424 // Note: we use naked sleep in this loop because we want to avoid using
1425 // any kind of VM infrastructure which may be broken at this point.
1426 if (VMError::check_timeout()) {
1427 // We hit error reporting timeout. Error reporting was interrupted and
1428 // will be wrapping things up now (closing files etc). Give it some more
1429 // time, then quit the VM.
1430 os::naked_short_sleep(200);
1431 // Print a message to stderr.
1432 fdStream err(defaultStream::output_fd());
1433 err.print_raw_cr("# [ timer expired, abort... ]");
1434 // skip atexit/vm_exit/vm_abort hooks
1435 os::die();
1436 }
1437
1438 // Wait a second, then recheck for timeout.
1439 os::naked_short_sleep(999);
1440 }
1441 }
1442
1443 if (_should_terminate) {
1444 // check for termination before posting the next tick
1445 break;
1446 }
1447
1448 PeriodicTask::real_time_tick(time_waited);
1449 }
1450
1451 // Signal that it is terminated
1452 {
1453 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1454 _watcher_thread = NULL;
1455 Terminator_lock->notify();
1456 }
1457 }
1458
1459 void WatcherThread::start() {
1460 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1461
1462 if (watcher_thread() == NULL && _startable) {
1463 _should_terminate = false;
1464 // Create the single instance of WatcherThread
1465 new WatcherThread();
1466 }
1467 }
1468
1469 void WatcherThread::make_startable() {
1470 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1471 _startable = true;
1472 }
1473
1474 void WatcherThread::stop() {
1475 {
1476 // Follow normal safepoint aware lock enter protocol since the
1477 // WatcherThread is stopped by another JavaThread.
1478 MutexLocker ml(PeriodicTask_lock);
1479 _should_terminate = true;
1480
1481 WatcherThread* watcher = watcher_thread();
1482 if (watcher != NULL) {
1483 // unpark the WatcherThread so it can see that it should terminate
1484 watcher->unpark();
1485 }
1486 }
1487
1488 MutexLocker mu(Terminator_lock);
1489
1490 while (watcher_thread() != NULL) {
1491 // This wait should make safepoint checks, wait without a timeout,
1492 // and wait as a suspend-equivalent condition.
1493 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1494 Mutex::_as_suspend_equivalent_flag);
1495 }
1496 }
1497
1498 void WatcherThread::unpark() {
1499 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1500 PeriodicTask_lock->notify();
1501 }
1502
1503 void WatcherThread::print_on(outputStream* st) const {
1504 st->print("\"%s\" ", name());
1505 Thread::print_on(st);
1506 st->cr();
1507 }
1508
1509 // ======= JavaThread ========
1510
1511 #if INCLUDE_JVMCI
1512
1513 jlong* JavaThread::_jvmci_old_thread_counters;
1514
1515 bool jvmci_counters_include(JavaThread* thread) {
1516 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1517 }
1518
1519 void JavaThread::collect_counters(typeArrayOop array) {
1520 if (JVMCICounterSize > 0) {
1521 JavaThreadIteratorWithHandle jtiwh;
1522 for (int i = 0; i < array->length(); i++) {
1523 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1524 }
1525 for (; JavaThread *tp = jtiwh.next(); ) {
1526 if (jvmci_counters_include(tp)) {
1527 for (int i = 0; i < array->length(); i++) {
1528 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1529 }
1530 }
1531 }
1532 }
1533 }
1534
1535 #endif // INCLUDE_JVMCI
1536
1537 // A JavaThread is a normal Java thread
1538
1539 void JavaThread::initialize() {
1540 // Initialize fields
1541
1542 set_saved_exception_pc(NULL);
1543 set_threadObj(NULL);
1544 _anchor.clear();
1545 set_entry_point(NULL);
1546 set_jni_functions(jni_functions());
1547 set_callee_target(NULL);
1548 set_vm_result(NULL);
1549 set_vm_result_2(NULL);
1550 set_vframe_array_head(NULL);
1551 set_vframe_array_last(NULL);
1552 set_deferred_locals(NULL);
1553 set_deopt_mark(NULL);
1554 set_deopt_compiled_method(NULL);
1555 clear_must_deopt_id();
1556 set_monitor_chunks(NULL);
1557 set_next(NULL);
1558 _on_thread_list = false;
1559 set_thread_state(_thread_new);
1560 _terminated = _not_terminated;
1561 _privileged_stack_top = NULL;
1562 _array_for_gc = NULL;
1563 _suspend_equivalent = false;
1564 _in_deopt_handler = 0;
1565 _doing_unsafe_access = false;
1566 _stack_guard_state = stack_guard_unused;
1567 #if INCLUDE_JVMCI
1568 _pending_monitorenter = false;
1569 _pending_deoptimization = -1;
1570 _pending_failed_speculation = 0;
1571 _pending_transfer_to_interpreter = false;
1572 _adjusting_comp_level = false;
1573 _in_retryable_allocation = false;
1574 _jvmci._alternate_call_target = NULL;
1575 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1576 if (JVMCICounterSize > 0) {
1577 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1578 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1579 } else {
1580 _jvmci_counters = NULL;
1581 }
1582 #endif // INCLUDE_JVMCI
1583 _reserved_stack_activation = NULL; // stack base not known yet
1584 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1585 _exception_pc = 0;
1586 _exception_handler_pc = 0;
1587 _is_method_handle_return = 0;
1588 _jvmti_thread_state= NULL;
1589 _should_post_on_exceptions_flag = JNI_FALSE;
1590 _interp_only_mode = 0;
1591 _special_runtime_exit_condition = _no_async_condition;
1592 _pending_async_exception = NULL;
1593 _thread_stat = NULL;
1594 _thread_stat = new ThreadStatistics();
1595 _blocked_on_compilation = false;
1596 _jni_active_critical = 0;
1597 _pending_jni_exception_check_fn = NULL;
1598 _do_not_unlock_if_synchronized = false;
1599 _cached_monitor_info = NULL;
1600 _parker = Parker::Allocate(this);
1601
1602 #ifndef PRODUCT
1603 _jmp_ring_index = 0;
1604 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1605 record_jump(NULL, NULL, NULL, 0);
1606 }
1607 #endif // PRODUCT
1608
1609 // Setup safepoint state info for this thread
1610 ThreadSafepointState::create(this);
1611
1612 debug_only(_java_call_counter = 0);
1613
1614 // JVMTI PopFrame support
1615 _popframe_condition = popframe_inactive;
1616 _popframe_preserved_args = NULL;
1617 _popframe_preserved_args_size = 0;
1618 _frames_to_pop_failed_realloc = 0;
1619
1620 if (SafepointMechanism::uses_thread_local_poll()) {
1621 SafepointMechanism::initialize_header(this);
1622 }
1623
1624 pd_initialize();
1625 }
1626
1627 JavaThread::JavaThread(bool is_attaching_via_jni) :
1628 Thread() {
1629 initialize();
1630 if (is_attaching_via_jni) {
1631 _jni_attach_state = _attaching_via_jni;
1632 } else {
1633 _jni_attach_state = _not_attaching_via_jni;
1634 }
1635 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1636 }
1637
1638 bool JavaThread::reguard_stack(address cur_sp) {
1639 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1640 && _stack_guard_state != stack_guard_reserved_disabled) {
1641 return true; // Stack already guarded or guard pages not needed.
1642 }
1643
1644 if (register_stack_overflow()) {
1645 // For those architectures which have separate register and
1646 // memory stacks, we must check the register stack to see if
1647 // it has overflowed.
1648 return false;
1649 }
1650
1651 // Java code never executes within the yellow zone: the latter is only
1652 // there to provoke an exception during stack banging. If java code
1653 // is executing there, either StackShadowPages should be larger, or
1654 // some exception code in c1, c2 or the interpreter isn't unwinding
1655 // when it should.
1656 guarantee(cur_sp > stack_reserved_zone_base(),
1657 "not enough space to reguard - increase StackShadowPages");
1658 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1659 enable_stack_yellow_reserved_zone();
1660 if (reserved_stack_activation() != stack_base()) {
1661 set_reserved_stack_activation(stack_base());
1662 }
1663 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1664 set_reserved_stack_activation(stack_base());
1665 enable_stack_reserved_zone();
1666 }
1667 return true;
1668 }
1669
1670 bool JavaThread::reguard_stack(void) {
1671 return reguard_stack(os::current_stack_pointer());
1672 }
1673
1674
1675 void JavaThread::block_if_vm_exited() {
1676 if (_terminated == _vm_exited) {
1677 // _vm_exited is set at safepoint, and Threads_lock is never released
1678 // we will block here forever
1679 Threads_lock->lock_without_safepoint_check();
1680 ShouldNotReachHere();
1681 }
1682 }
1683
1684
1685 // Remove this ifdef when C1 is ported to the compiler interface.
1686 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1687 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1688
1689 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1690 Thread() {
1691 initialize();
1692 _jni_attach_state = _not_attaching_via_jni;
1693 set_entry_point(entry_point);
1694 // Create the native thread itself.
1695 // %note runtime_23
1696 os::ThreadType thr_type = os::java_thread;
1697 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1698 os::java_thread;
1699 os::create_thread(this, thr_type, stack_sz);
1700 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1701 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1702 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1703 // the exception consists of creating the exception object & initializing it, initialization
1704 // will leave the VM via a JavaCall and then all locks must be unlocked).
1705 //
1706 // The thread is still suspended when we reach here. Thread must be explicit started
1707 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1708 // by calling Threads:add. The reason why this is not done here, is because the thread
1709 // object must be fully initialized (take a look at JVM_Start)
1710 }
1711
1712 JavaThread::~JavaThread() {
1713
1714 // JSR166 -- return the parker to the free list
1715 Parker::Release(_parker);
1716 _parker = NULL;
1717
1718 // Free any remaining previous UnrollBlock
1719 vframeArray* old_array = vframe_array_last();
1720
1721 if (old_array != NULL) {
1722 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1723 old_array->set_unroll_block(NULL);
1724 delete old_info;
1725 delete old_array;
1726 }
1727
1728 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1729 if (deferred != NULL) {
1730 // This can only happen if thread is destroyed before deoptimization occurs.
1731 assert(deferred->length() != 0, "empty array!");
1732 do {
1733 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1734 deferred->remove_at(0);
1735 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1736 delete dlv;
1737 } while (deferred->length() != 0);
1738 delete deferred;
1739 }
1740
1741 // All Java related clean up happens in exit
1742 ThreadSafepointState::destroy(this);
1743 if (_thread_stat != NULL) delete _thread_stat;
1744
1745 #if INCLUDE_JVMCI
1746 if (JVMCICounterSize > 0) {
1747 if (jvmci_counters_include(this)) {
1748 for (int i = 0; i < JVMCICounterSize; i++) {
1749 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1750 }
1751 }
1752 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1753 }
1754 #endif // INCLUDE_JVMCI
1755 }
1756
1757
1758 // The first routine called by a new Java thread
1759 void JavaThread::run() {
1760 // initialize thread-local alloc buffer related fields
1761 this->initialize_tlab();
1762
1763 // used to test validity of stack trace backs
1764 this->record_base_of_stack_pointer();
1765
1766 this->create_stack_guard_pages();
1767
1768 this->cache_global_variables();
1769
1770 // Thread is now sufficient initialized to be handled by the safepoint code as being
1771 // in the VM. Change thread state from _thread_new to _thread_in_vm
1772 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1773
1774 assert(JavaThread::current() == this, "sanity check");
1775 assert(!Thread::current()->owns_locks(), "sanity check");
1776
1777 DTRACE_THREAD_PROBE(start, this);
1778
1779 // This operation might block. We call that after all safepoint checks for a new thread has
1780 // been completed.
1781 this->set_active_handles(JNIHandleBlock::allocate_block());
1782
1783 if (JvmtiExport::should_post_thread_life()) {
1784 JvmtiExport::post_thread_start(this);
1785 }
1786
1787 EventThreadStart event;
1788 if (event.should_commit()) {
1789 event.set_thread(JFR_THREAD_ID(this));
1790 event.commit();
1791 }
1792
1793 // We call another function to do the rest so we are sure that the stack addresses used
1794 // from there will be lower than the stack base just computed
1795 thread_main_inner();
1796
1797 // Note, thread is no longer valid at this point!
1798 }
1799
1800
1801 void JavaThread::thread_main_inner() {
1802 assert(JavaThread::current() == this, "sanity check");
1803 assert(this->threadObj() != NULL, "just checking");
1804
1805 // Execute thread entry point unless this thread has a pending exception
1806 // or has been stopped before starting.
1807 // Note: Due to JVM_StopThread we can have pending exceptions already!
1808 if (!this->has_pending_exception() &&
1809 !java_lang_Thread::is_stillborn(this->threadObj())) {
1810 {
1811 ResourceMark rm(this);
1812 this->set_native_thread_name(this->get_thread_name());
1813 }
1814 HandleMark hm(this);
1815 this->entry_point()(this, this);
1816 }
1817
1818 DTRACE_THREAD_PROBE(stop, this);
1819
1820 this->exit(false);
1821 this->smr_delete();
1822 }
1823
1824
1825 static void ensure_join(JavaThread* thread) {
1826 // We do not need to grab the Threads_lock, since we are operating on ourself.
1827 Handle threadObj(thread, thread->threadObj());
1828 assert(threadObj.not_null(), "java thread object must exist");
1829 ObjectLocker lock(threadObj, thread);
1830 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1831 thread->clear_pending_exception();
1832 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1833 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1834 // Clear the native thread instance - this makes isAlive return false and allows the join()
1835 // to complete once we've done the notify_all below
1836 java_lang_Thread::set_thread(threadObj(), NULL);
1837 lock.notify_all(thread);
1838 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1839 thread->clear_pending_exception();
1840 }
1841
1842 static bool is_daemon(oop threadObj) {
1843 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1844 }
1845
1846 // For any new cleanup additions, please check to see if they need to be applied to
1847 // cleanup_failed_attach_current_thread as well.
1848 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1849 assert(this == JavaThread::current(), "thread consistency check");
1850
1851 elapsedTimer _timer_exit_phase1;
1852 elapsedTimer _timer_exit_phase2;
1853 elapsedTimer _timer_exit_phase3;
1854 elapsedTimer _timer_exit_phase4;
1855
1856 if (log_is_enabled(Debug, os, thread, timer)) {
1857 _timer_exit_phase1.start();
1858 }
1859
1860 HandleMark hm(this);
1861 Handle uncaught_exception(this, this->pending_exception());
1862 this->clear_pending_exception();
1863 Handle threadObj(this, this->threadObj());
1864 assert(threadObj.not_null(), "Java thread object should be created");
1865
1866 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1867 {
1868 EXCEPTION_MARK;
1869
1870 CLEAR_PENDING_EXCEPTION;
1871 }
1872 if (!destroy_vm) {
1873 if (uncaught_exception.not_null()) {
1874 EXCEPTION_MARK;
1875 // Call method Thread.dispatchUncaughtException().
1876 Klass* thread_klass = SystemDictionary::Thread_klass();
1877 JavaValue result(T_VOID);
1878 JavaCalls::call_virtual(&result,
1879 threadObj, thread_klass,
1880 vmSymbols::dispatchUncaughtException_name(),
1881 vmSymbols::throwable_void_signature(),
1882 uncaught_exception,
1883 THREAD);
1884 if (HAS_PENDING_EXCEPTION) {
1885 ResourceMark rm(this);
1886 jio_fprintf(defaultStream::error_stream(),
1887 "\nException: %s thrown from the UncaughtExceptionHandler"
1888 " in thread \"%s\"\n",
1889 pending_exception()->klass()->external_name(),
1890 get_thread_name());
1891 CLEAR_PENDING_EXCEPTION;
1892 }
1893 }
1894
1895 // Called before the java thread exit since we want to read info
1896 // from java_lang_Thread object
1897 EventThreadEnd event;
1898 if (event.should_commit()) {
1899 event.set_thread(JFR_THREAD_ID(this));
1900 event.commit();
1901 }
1902
1903 // Call after last event on thread
1904 JFR_ONLY(Jfr::on_thread_exit(this);)
1905
1906 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1907 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1908 // is deprecated anyhow.
1909 if (!is_Compiler_thread()) {
1910 int count = 3;
1911 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1912 EXCEPTION_MARK;
1913 JavaValue result(T_VOID);
1914 Klass* thread_klass = SystemDictionary::Thread_klass();
1915 JavaCalls::call_virtual(&result,
1916 threadObj, thread_klass,
1917 vmSymbols::exit_method_name(),
1918 vmSymbols::void_method_signature(),
1919 THREAD);
1920 CLEAR_PENDING_EXCEPTION;
1921 }
1922 }
1923 // notify JVMTI
1924 if (JvmtiExport::should_post_thread_life()) {
1925 JvmtiExport::post_thread_end(this);
1926 }
1927
1928 // We have notified the agents that we are exiting, before we go on,
1929 // we must check for a pending external suspend request and honor it
1930 // in order to not surprise the thread that made the suspend request.
1931 while (true) {
1932 {
1933 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1934 if (!is_external_suspend()) {
1935 set_terminated(_thread_exiting);
1936 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1937 break;
1938 }
1939 // Implied else:
1940 // Things get a little tricky here. We have a pending external
1941 // suspend request, but we are holding the SR_lock so we
1942 // can't just self-suspend. So we temporarily drop the lock
1943 // and then self-suspend.
1944 }
1945
1946 ThreadBlockInVM tbivm(this);
1947 java_suspend_self();
1948
1949 // We're done with this suspend request, but we have to loop around
1950 // and check again. Eventually we will get SR_lock without a pending
1951 // external suspend request and will be able to mark ourselves as
1952 // exiting.
1953 }
1954 // no more external suspends are allowed at this point
1955 } else {
1956 assert(!is_terminated() && !is_exiting(), "must not be exiting");
1957 // before_exit() has already posted JVMTI THREAD_END events
1958 }
1959
1960 if (log_is_enabled(Debug, os, thread, timer)) {
1961 _timer_exit_phase1.stop();
1962 _timer_exit_phase2.start();
1963 }
1964 // Notify waiters on thread object. This has to be done after exit() is called
1965 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1966 // group should have the destroyed bit set before waiters are notified).
1967 ensure_join(this);
1968 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1969
1970 if (log_is_enabled(Debug, os, thread, timer)) {
1971 _timer_exit_phase2.stop();
1972 _timer_exit_phase3.start();
1973 }
1974 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1975 // held by this thread must be released. The spec does not distinguish
1976 // between JNI-acquired and regular Java monitors. We can only see
1977 // regular Java monitors here if monitor enter-exit matching is broken.
1978 //
1979 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1980 // ObjectSynchronizer::release_monitors_owned_by_thread().
1981 if (exit_type == jni_detach) {
1982 // Sanity check even though JNI DetachCurrentThread() would have
1983 // returned JNI_ERR if there was a Java frame. JavaThread exit
1984 // should be done executing Java code by the time we get here.
1985 assert(!this->has_last_Java_frame(),
1986 "should not have a Java frame when detaching or exiting");
1987 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1988 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1989 }
1990
1991 // These things needs to be done while we are still a Java Thread. Make sure that thread
1992 // is in a consistent state, in case GC happens
1993 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1994
1995 if (active_handles() != NULL) {
1996 JNIHandleBlock* block = active_handles();
1997 set_active_handles(NULL);
1998 JNIHandleBlock::release_block(block);
1999 }
2000
2001 if (free_handle_block() != NULL) {
2002 JNIHandleBlock* block = free_handle_block();
2003 set_free_handle_block(NULL);
2004 JNIHandleBlock::release_block(block);
2005 }
2006
2007 // These have to be removed while this is still a valid thread.
2008 remove_stack_guard_pages();
2009
2010 if (UseTLAB) {
2011 tlab().retire();
2012 }
2013
2014 if (JvmtiEnv::environments_might_exist()) {
2015 JvmtiExport::cleanup_thread(this);
2016 }
2017
2018 // We must flush any deferred card marks and other various GC barrier
2019 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2020 // before removing a thread from the list of active threads.
2021 BarrierSet::barrier_set()->on_thread_detach(this);
2022
2023 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2024 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2025 os::current_thread_id());
2026
2027 if (log_is_enabled(Debug, os, thread, timer)) {
2028 _timer_exit_phase3.stop();
2029 _timer_exit_phase4.start();
2030 }
2031 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2032 Threads::remove(this);
2033
2034 if (log_is_enabled(Debug, os, thread, timer)) {
2035 _timer_exit_phase4.stop();
2036 ResourceMark rm(this);
2037 log_debug(os, thread, timer)("name='%s'"
2038 ", exit-phase1=" JLONG_FORMAT
2039 ", exit-phase2=" JLONG_FORMAT
2040 ", exit-phase3=" JLONG_FORMAT
2041 ", exit-phase4=" JLONG_FORMAT,
2042 get_thread_name(),
2043 _timer_exit_phase1.milliseconds(),
2044 _timer_exit_phase2.milliseconds(),
2045 _timer_exit_phase3.milliseconds(),
2046 _timer_exit_phase4.milliseconds());
2047 }
2048 }
2049
2050 void JavaThread::cleanup_failed_attach_current_thread() {
2051 if (active_handles() != NULL) {
2052 JNIHandleBlock* block = active_handles();
2053 set_active_handles(NULL);
2054 JNIHandleBlock::release_block(block);
2055 }
2056
2057 if (free_handle_block() != NULL) {
2058 JNIHandleBlock* block = free_handle_block();
2059 set_free_handle_block(NULL);
2060 JNIHandleBlock::release_block(block);
2061 }
2062
2063 // These have to be removed while this is still a valid thread.
2064 remove_stack_guard_pages();
2065
2066 if (UseTLAB) {
2067 tlab().retire();
2068 }
2069
2070 BarrierSet::barrier_set()->on_thread_detach(this);
2071
2072 Threads::remove(this);
2073 this->smr_delete();
2074 }
2075
2076 JavaThread* JavaThread::active() {
2077 Thread* thread = Thread::current();
2078 if (thread->is_Java_thread()) {
2079 return (JavaThread*) thread;
2080 } else {
2081 assert(thread->is_VM_thread(), "this must be a vm thread");
2082 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2083 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2084 assert(ret->is_Java_thread(), "must be a Java thread");
2085 return ret;
2086 }
2087 }
2088
2089 bool JavaThread::is_lock_owned(address adr) const {
2090 if (Thread::is_lock_owned(adr)) return true;
2091
2092 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2093 if (chunk->contains(adr)) return true;
2094 }
2095
2096 return false;
2097 }
2098
2099
2100 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2101 chunk->set_next(monitor_chunks());
2102 set_monitor_chunks(chunk);
2103 }
2104
2105 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2106 guarantee(monitor_chunks() != NULL, "must be non empty");
2107 if (monitor_chunks() == chunk) {
2108 set_monitor_chunks(chunk->next());
2109 } else {
2110 MonitorChunk* prev = monitor_chunks();
2111 while (prev->next() != chunk) prev = prev->next();
2112 prev->set_next(chunk->next());
2113 }
2114 }
2115
2116 // JVM support.
2117
2118 // Note: this function shouldn't block if it's called in
2119 // _thread_in_native_trans state (such as from
2120 // check_special_condition_for_native_trans()).
2121 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2122
2123 if (has_last_Java_frame() && has_async_condition()) {
2124 // If we are at a polling page safepoint (not a poll return)
2125 // then we must defer async exception because live registers
2126 // will be clobbered by the exception path. Poll return is
2127 // ok because the call we a returning from already collides
2128 // with exception handling registers and so there is no issue.
2129 // (The exception handling path kills call result registers but
2130 // this is ok since the exception kills the result anyway).
2131
2132 if (is_at_poll_safepoint()) {
2133 // if the code we are returning to has deoptimized we must defer
2134 // the exception otherwise live registers get clobbered on the
2135 // exception path before deoptimization is able to retrieve them.
2136 //
2137 RegisterMap map(this, false);
2138 frame caller_fr = last_frame().sender(&map);
2139 assert(caller_fr.is_compiled_frame(), "what?");
2140 if (caller_fr.is_deoptimized_frame()) {
2141 log_info(exceptions)("deferred async exception at compiled safepoint");
2142 return;
2143 }
2144 }
2145 }
2146
2147 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2148 if (condition == _no_async_condition) {
2149 // Conditions have changed since has_special_runtime_exit_condition()
2150 // was called:
2151 // - if we were here only because of an external suspend request,
2152 // then that was taken care of above (or cancelled) so we are done
2153 // - if we were here because of another async request, then it has
2154 // been cleared between the has_special_runtime_exit_condition()
2155 // and now so again we are done
2156 return;
2157 }
2158
2159 // Check for pending async. exception
2160 if (_pending_async_exception != NULL) {
2161 // Only overwrite an already pending exception, if it is not a threadDeath.
2162 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2163
2164 // We cannot call Exceptions::_throw(...) here because we cannot block
2165 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2166
2167 LogTarget(Info, exceptions) lt;
2168 if (lt.is_enabled()) {
2169 ResourceMark rm;
2170 LogStream ls(lt);
2171 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2172 if (has_last_Java_frame()) {
2173 frame f = last_frame();
2174 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2175 }
2176 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2177 }
2178 _pending_async_exception = NULL;
2179 clear_has_async_exception();
2180 }
2181 }
2182
2183 if (check_unsafe_error &&
2184 condition == _async_unsafe_access_error && !has_pending_exception()) {
2185 condition = _no_async_condition; // done
2186 switch (thread_state()) {
2187 case _thread_in_vm: {
2188 JavaThread* THREAD = this;
2189 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2190 }
2191 case _thread_in_native: {
2192 ThreadInVMfromNative tiv(this);
2193 JavaThread* THREAD = this;
2194 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2195 }
2196 case _thread_in_Java: {
2197 ThreadInVMfromJava tiv(this);
2198 JavaThread* THREAD = this;
2199 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2200 }
2201 default:
2202 ShouldNotReachHere();
2203 }
2204 }
2205
2206 assert(condition == _no_async_condition || has_pending_exception() ||
2207 (!check_unsafe_error && condition == _async_unsafe_access_error),
2208 "must have handled the async condition, if no exception");
2209 }
2210
2211 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2212 //
2213 // Check for pending external suspend. Internal suspend requests do
2214 // not use handle_special_runtime_exit_condition().
2215 // If JNIEnv proxies are allowed, don't self-suspend if the target
2216 // thread is not the current thread. In older versions of jdbx, jdbx
2217 // threads could call into the VM with another thread's JNIEnv so we
2218 // can be here operating on behalf of a suspended thread (4432884).
2219 bool do_self_suspend = is_external_suspend_with_lock();
2220 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2221 //
2222 // Because thread is external suspended the safepoint code will count
2223 // thread as at a safepoint. This can be odd because we can be here
2224 // as _thread_in_Java which would normally transition to _thread_blocked
2225 // at a safepoint. We would like to mark the thread as _thread_blocked
2226 // before calling java_suspend_self like all other callers of it but
2227 // we must then observe proper safepoint protocol. (We can't leave
2228 // _thread_blocked with a safepoint in progress). However we can be
2229 // here as _thread_in_native_trans so we can't use a normal transition
2230 // constructor/destructor pair because they assert on that type of
2231 // transition. We could do something like:
2232 //
2233 // JavaThreadState state = thread_state();
2234 // set_thread_state(_thread_in_vm);
2235 // {
2236 // ThreadBlockInVM tbivm(this);
2237 // java_suspend_self()
2238 // }
2239 // set_thread_state(_thread_in_vm_trans);
2240 // if (safepoint) block;
2241 // set_thread_state(state);
2242 //
2243 // but that is pretty messy. Instead we just go with the way the
2244 // code has worked before and note that this is the only path to
2245 // java_suspend_self that doesn't put the thread in _thread_blocked
2246 // mode.
2247
2248 frame_anchor()->make_walkable(this);
2249 java_suspend_self();
2250
2251 // We might be here for reasons in addition to the self-suspend request
2252 // so check for other async requests.
2253 }
2254
2255 if (check_asyncs) {
2256 check_and_handle_async_exceptions();
2257 }
2258
2259 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2260 }
2261
2262 void JavaThread::send_thread_stop(oop java_throwable) {
2263 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2264 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2265 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2266
2267 // Do not throw asynchronous exceptions against the compiler thread
2268 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2269 if (!can_call_java()) return;
2270
2271 {
2272 // Actually throw the Throwable against the target Thread - however
2273 // only if there is no thread death exception installed already.
2274 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2275 // If the topmost frame is a runtime stub, then we are calling into
2276 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2277 // must deoptimize the caller before continuing, as the compiled exception handler table
2278 // may not be valid
2279 if (has_last_Java_frame()) {
2280 frame f = last_frame();
2281 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2282 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2283 RegisterMap reg_map(this, UseBiasedLocking);
2284 frame compiled_frame = f.sender(®_map);
2285 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2286 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2287 }
2288 }
2289 }
2290
2291 // Set async. pending exception in thread.
2292 set_pending_async_exception(java_throwable);
2293
2294 if (log_is_enabled(Info, exceptions)) {
2295 ResourceMark rm;
2296 log_info(exceptions)("Pending Async. exception installed of type: %s",
2297 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2298 }
2299 // for AbortVMOnException flag
2300 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2301 }
2302 }
2303
2304
2305 // Interrupt thread so it will wake up from a potential wait()
2306 Thread::interrupt(this);
2307 }
2308
2309 // External suspension mechanism.
2310 //
2311 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2312 // to any VM_locks and it is at a transition
2313 // Self-suspension will happen on the transition out of the vm.
2314 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2315 //
2316 // Guarantees on return:
2317 // + Target thread will not execute any new bytecode (that's why we need to
2318 // force a safepoint)
2319 // + Target thread will not enter any new monitors
2320 //
2321 void JavaThread::java_suspend() {
2322 ThreadsListHandle tlh;
2323 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2324 return;
2325 }
2326
2327 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2328 if (!is_external_suspend()) {
2329 // a racing resume has cancelled us; bail out now
2330 return;
2331 }
2332
2333 // suspend is done
2334 uint32_t debug_bits = 0;
2335 // Warning: is_ext_suspend_completed() may temporarily drop the
2336 // SR_lock to allow the thread to reach a stable thread state if
2337 // it is currently in a transient thread state.
2338 if (is_ext_suspend_completed(false /* !called_by_wait */,
2339 SuspendRetryDelay, &debug_bits)) {
2340 return;
2341 }
2342 }
2343
2344 VM_ThreadSuspend vm_suspend;
2345 VMThread::execute(&vm_suspend);
2346 }
2347
2348 // Part II of external suspension.
2349 // A JavaThread self suspends when it detects a pending external suspend
2350 // request. This is usually on transitions. It is also done in places
2351 // where continuing to the next transition would surprise the caller,
2352 // e.g., monitor entry.
2353 //
2354 // Returns the number of times that the thread self-suspended.
2355 //
2356 // Note: DO NOT call java_suspend_self() when you just want to block current
2357 // thread. java_suspend_self() is the second stage of cooperative
2358 // suspension for external suspend requests and should only be used
2359 // to complete an external suspend request.
2360 //
2361 int JavaThread::java_suspend_self() {
2362 int ret = 0;
2363
2364 // we are in the process of exiting so don't suspend
2365 if (is_exiting()) {
2366 clear_external_suspend();
2367 return ret;
2368 }
2369
2370 assert(_anchor.walkable() ||
2371 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2372 "must have walkable stack");
2373
2374 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2375
2376 assert(!this->is_ext_suspended(),
2377 "a thread trying to self-suspend should not already be suspended");
2378
2379 if (this->is_suspend_equivalent()) {
2380 // If we are self-suspending as a result of the lifting of a
2381 // suspend equivalent condition, then the suspend_equivalent
2382 // flag is not cleared until we set the ext_suspended flag so
2383 // that wait_for_ext_suspend_completion() returns consistent
2384 // results.
2385 this->clear_suspend_equivalent();
2386 }
2387
2388 // A racing resume may have cancelled us before we grabbed SR_lock
2389 // above. Or another external suspend request could be waiting for us
2390 // by the time we return from SR_lock()->wait(). The thread
2391 // that requested the suspension may already be trying to walk our
2392 // stack and if we return now, we can change the stack out from under
2393 // it. This would be a "bad thing (TM)" and cause the stack walker
2394 // to crash. We stay self-suspended until there are no more pending
2395 // external suspend requests.
2396 while (is_external_suspend()) {
2397 ret++;
2398 this->set_ext_suspended();
2399
2400 // _ext_suspended flag is cleared by java_resume()
2401 while (is_ext_suspended()) {
2402 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2403 }
2404 }
2405
2406 return ret;
2407 }
2408
2409 #ifdef ASSERT
2410 // Verify the JavaThread has not yet been published in the Threads::list, and
2411 // hence doesn't need protection from concurrent access at this stage.
2412 void JavaThread::verify_not_published() {
2413 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2414 // since an unpublished JavaThread doesn't participate in the
2415 // Thread-SMR protocol for keeping a ThreadsList alive.
2416 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2417 }
2418 #endif
2419
2420 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2421 // progress or when _suspend_flags is non-zero.
2422 // Current thread needs to self-suspend if there is a suspend request and/or
2423 // block if a safepoint is in progress.
2424 // Async exception ISN'T checked.
2425 // Note only the ThreadInVMfromNative transition can call this function
2426 // directly and when thread state is _thread_in_native_trans
2427 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2428 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2429
2430 JavaThread *curJT = JavaThread::current();
2431 bool do_self_suspend = thread->is_external_suspend();
2432
2433 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2434
2435 // If JNIEnv proxies are allowed, don't self-suspend if the target
2436 // thread is not the current thread. In older versions of jdbx, jdbx
2437 // threads could call into the VM with another thread's JNIEnv so we
2438 // can be here operating on behalf of a suspended thread (4432884).
2439 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2440 JavaThreadState state = thread->thread_state();
2441
2442 // We mark this thread_blocked state as a suspend-equivalent so
2443 // that a caller to is_ext_suspend_completed() won't be confused.
2444 // The suspend-equivalent state is cleared by java_suspend_self().
2445 thread->set_suspend_equivalent();
2446
2447 // If the safepoint code sees the _thread_in_native_trans state, it will
2448 // wait until the thread changes to other thread state. There is no
2449 // guarantee on how soon we can obtain the SR_lock and complete the
2450 // self-suspend request. It would be a bad idea to let safepoint wait for
2451 // too long. Temporarily change the state to _thread_blocked to
2452 // let the VM thread know that this thread is ready for GC. The problem
2453 // of changing thread state is that safepoint could happen just after
2454 // java_suspend_self() returns after being resumed, and VM thread will
2455 // see the _thread_blocked state. We must check for safepoint
2456 // after restoring the state and make sure we won't leave while a safepoint
2457 // is in progress.
2458 thread->set_thread_state(_thread_blocked);
2459 thread->java_suspend_self();
2460 thread->set_thread_state(state);
2461
2462 InterfaceSupport::serialize_thread_state_with_handler(thread);
2463 }
2464
2465 SafepointMechanism::block_if_requested(curJT);
2466
2467 if (thread->is_deopt_suspend()) {
2468 thread->clear_deopt_suspend();
2469 RegisterMap map(thread, false);
2470 frame f = thread->last_frame();
2471 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2472 f = f.sender(&map);
2473 }
2474 if (f.id() == thread->must_deopt_id()) {
2475 thread->clear_must_deopt_id();
2476 f.deoptimize(thread);
2477 } else {
2478 fatal("missed deoptimization!");
2479 }
2480 }
2481
2482 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2483 }
2484
2485 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2486 // progress or when _suspend_flags is non-zero.
2487 // Current thread needs to self-suspend if there is a suspend request and/or
2488 // block if a safepoint is in progress.
2489 // Also check for pending async exception (not including unsafe access error).
2490 // Note only the native==>VM/Java barriers can call this function and when
2491 // thread state is _thread_in_native_trans.
2492 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2493 check_safepoint_and_suspend_for_native_trans(thread);
2494
2495 if (thread->has_async_exception()) {
2496 // We are in _thread_in_native_trans state, don't handle unsafe
2497 // access error since that may block.
2498 thread->check_and_handle_async_exceptions(false);
2499 }
2500 }
2501
2502 // This is a variant of the normal
2503 // check_special_condition_for_native_trans with slightly different
2504 // semantics for use by critical native wrappers. It does all the
2505 // normal checks but also performs the transition back into
2506 // thread_in_Java state. This is required so that critical natives
2507 // can potentially block and perform a GC if they are the last thread
2508 // exiting the GCLocker.
2509 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2510 check_special_condition_for_native_trans(thread);
2511
2512 // Finish the transition
2513 thread->set_thread_state(_thread_in_Java);
2514
2515 if (thread->do_critical_native_unlock()) {
2516 ThreadInVMfromJavaNoAsyncException tiv(thread);
2517 GCLocker::unlock_critical(thread);
2518 thread->clear_critical_native_unlock();
2519 }
2520 }
2521
2522 // We need to guarantee the Threads_lock here, since resumes are not
2523 // allowed during safepoint synchronization
2524 // Can only resume from an external suspension
2525 void JavaThread::java_resume() {
2526 assert_locked_or_safepoint(Threads_lock);
2527
2528 // Sanity check: thread is gone, has started exiting or the thread
2529 // was not externally suspended.
2530 ThreadsListHandle tlh;
2531 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2532 return;
2533 }
2534
2535 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2536
2537 clear_external_suspend();
2538
2539 if (is_ext_suspended()) {
2540 clear_ext_suspended();
2541 SR_lock()->notify_all();
2542 }
2543 }
2544
2545 size_t JavaThread::_stack_red_zone_size = 0;
2546 size_t JavaThread::_stack_yellow_zone_size = 0;
2547 size_t JavaThread::_stack_reserved_zone_size = 0;
2548 size_t JavaThread::_stack_shadow_zone_size = 0;
2549
2550 void JavaThread::create_stack_guard_pages() {
2551 if (!os::uses_stack_guard_pages() ||
2552 _stack_guard_state != stack_guard_unused ||
2553 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2554 log_info(os, thread)("Stack guard page creation for thread "
2555 UINTX_FORMAT " disabled", os::current_thread_id());
2556 return;
2557 }
2558 address low_addr = stack_end();
2559 size_t len = stack_guard_zone_size();
2560
2561 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2562 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2563
2564 int must_commit = os::must_commit_stack_guard_pages();
2565 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2566
2567 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2568 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2569 return;
2570 }
2571
2572 if (os::guard_memory((char *) low_addr, len)) {
2573 _stack_guard_state = stack_guard_enabled;
2574 } else {
2575 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2576 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2577 if (os::uncommit_memory((char *) low_addr, len)) {
2578 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2579 }
2580 return;
2581 }
2582
2583 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2584 PTR_FORMAT "-" PTR_FORMAT ".",
2585 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2586 }
2587
2588 void JavaThread::remove_stack_guard_pages() {
2589 assert(Thread::current() == this, "from different thread");
2590 if (_stack_guard_state == stack_guard_unused) return;
2591 address low_addr = stack_end();
2592 size_t len = stack_guard_zone_size();
2593
2594 if (os::must_commit_stack_guard_pages()) {
2595 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2596 _stack_guard_state = stack_guard_unused;
2597 } else {
2598 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2599 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2600 return;
2601 }
2602 } else {
2603 if (_stack_guard_state == stack_guard_unused) return;
2604 if (os::unguard_memory((char *) low_addr, len)) {
2605 _stack_guard_state = stack_guard_unused;
2606 } else {
2607 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2608 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2609 return;
2610 }
2611 }
2612
2613 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2614 PTR_FORMAT "-" PTR_FORMAT ".",
2615 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2616 }
2617
2618 void JavaThread::enable_stack_reserved_zone() {
2619 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2620 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2621
2622 // The base notation is from the stack's point of view, growing downward.
2623 // We need to adjust it to work correctly with guard_memory()
2624 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2625
2626 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2627 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2628
2629 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2630 _stack_guard_state = stack_guard_enabled;
2631 } else {
2632 warning("Attempt to guard stack reserved zone failed.");
2633 }
2634 enable_register_stack_guard();
2635 }
2636
2637 void JavaThread::disable_stack_reserved_zone() {
2638 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2639 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2640
2641 // Simply return if called for a thread that does not use guard pages.
2642 if (_stack_guard_state == stack_guard_unused) return;
2643
2644 // The base notation is from the stack's point of view, growing downward.
2645 // We need to adjust it to work correctly with guard_memory()
2646 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2647
2648 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2649 _stack_guard_state = stack_guard_reserved_disabled;
2650 } else {
2651 warning("Attempt to unguard stack reserved zone failed.");
2652 }
2653 disable_register_stack_guard();
2654 }
2655
2656 void JavaThread::enable_stack_yellow_reserved_zone() {
2657 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2658 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2659
2660 // The base notation is from the stacks point of view, growing downward.
2661 // We need to adjust it to work correctly with guard_memory()
2662 address base = stack_red_zone_base();
2663
2664 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2665 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2666
2667 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2668 _stack_guard_state = stack_guard_enabled;
2669 } else {
2670 warning("Attempt to guard stack yellow zone failed.");
2671 }
2672 enable_register_stack_guard();
2673 }
2674
2675 void JavaThread::disable_stack_yellow_reserved_zone() {
2676 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2677 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2678
2679 // Simply return if called for a thread that does not use guard pages.
2680 if (_stack_guard_state == stack_guard_unused) return;
2681
2682 // The base notation is from the stacks point of view, growing downward.
2683 // We need to adjust it to work correctly with guard_memory()
2684 address base = stack_red_zone_base();
2685
2686 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2687 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2688 } else {
2689 warning("Attempt to unguard stack yellow zone failed.");
2690 }
2691 disable_register_stack_guard();
2692 }
2693
2694 void JavaThread::enable_stack_red_zone() {
2695 // The base notation is from the stacks point of view, growing downward.
2696 // We need to adjust it to work correctly with guard_memory()
2697 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2698 address base = stack_red_zone_base() - stack_red_zone_size();
2699
2700 guarantee(base < stack_base(), "Error calculating stack red zone");
2701 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2702
2703 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2704 warning("Attempt to guard stack red zone failed.");
2705 }
2706 }
2707
2708 void JavaThread::disable_stack_red_zone() {
2709 // The base notation is from the stacks point of view, growing downward.
2710 // We need to adjust it to work correctly with guard_memory()
2711 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2712 address base = stack_red_zone_base() - stack_red_zone_size();
2713 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2714 warning("Attempt to unguard stack red zone failed.");
2715 }
2716 }
2717
2718 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2719 // ignore is there is no stack
2720 if (!has_last_Java_frame()) return;
2721 // traverse the stack frames. Starts from top frame.
2722 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2723 frame* fr = fst.current();
2724 f(fr, fst.register_map());
2725 }
2726 }
2727
2728
2729 #ifndef PRODUCT
2730 // Deoptimization
2731 // Function for testing deoptimization
2732 void JavaThread::deoptimize() {
2733 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2734 StackFrameStream fst(this, UseBiasedLocking);
2735 bool deopt = false; // Dump stack only if a deopt actually happens.
2736 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2737 // Iterate over all frames in the thread and deoptimize
2738 for (; !fst.is_done(); fst.next()) {
2739 if (fst.current()->can_be_deoptimized()) {
2740
2741 if (only_at) {
2742 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2743 // consists of comma or carriage return separated numbers so
2744 // search for the current bci in that string.
2745 address pc = fst.current()->pc();
2746 nmethod* nm = (nmethod*) fst.current()->cb();
2747 ScopeDesc* sd = nm->scope_desc_at(pc);
2748 char buffer[8];
2749 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2750 size_t len = strlen(buffer);
2751 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2752 while (found != NULL) {
2753 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2754 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2755 // Check that the bci found is bracketed by terminators.
2756 break;
2757 }
2758 found = strstr(found + 1, buffer);
2759 }
2760 if (!found) {
2761 continue;
2762 }
2763 }
2764
2765 if (DebugDeoptimization && !deopt) {
2766 deopt = true; // One-time only print before deopt
2767 tty->print_cr("[BEFORE Deoptimization]");
2768 trace_frames();
2769 trace_stack();
2770 }
2771 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2772 }
2773 }
2774
2775 if (DebugDeoptimization && deopt) {
2776 tty->print_cr("[AFTER Deoptimization]");
2777 trace_frames();
2778 }
2779 }
2780
2781
2782 // Make zombies
2783 void JavaThread::make_zombies() {
2784 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2785 if (fst.current()->can_be_deoptimized()) {
2786 // it is a Java nmethod
2787 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2788 nm->make_not_entrant();
2789 }
2790 }
2791 }
2792 #endif // PRODUCT
2793
2794
2795 void JavaThread::deoptimized_wrt_marked_nmethods() {
2796 if (!has_last_Java_frame()) return;
2797 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2798 StackFrameStream fst(this, UseBiasedLocking);
2799 for (; !fst.is_done(); fst.next()) {
2800 if (fst.current()->should_be_deoptimized()) {
2801 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2802 }
2803 }
2804 }
2805
2806
2807 // If the caller is a NamedThread, then remember, in the current scope,
2808 // the given JavaThread in its _processed_thread field.
2809 class RememberProcessedThread: public StackObj {
2810 NamedThread* _cur_thr;
2811 public:
2812 RememberProcessedThread(JavaThread* jthr) {
2813 Thread* thread = Thread::current();
2814 if (thread->is_Named_thread()) {
2815 _cur_thr = (NamedThread *)thread;
2816 _cur_thr->set_processed_thread(jthr);
2817 } else {
2818 _cur_thr = NULL;
2819 }
2820 }
2821
2822 ~RememberProcessedThread() {
2823 if (_cur_thr) {
2824 _cur_thr->set_processed_thread(NULL);
2825 }
2826 }
2827 };
2828
2829 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2830 // Verify that the deferred card marks have been flushed.
2831 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2832
2833 // Traverse the GCHandles
2834 Thread::oops_do(f, cf);
2835
2836 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2837 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2838
2839 if (has_last_Java_frame()) {
2840 // Record JavaThread to GC thread
2841 RememberProcessedThread rpt(this);
2842
2843 // Traverse the privileged stack
2844 if (_privileged_stack_top != NULL) {
2845 _privileged_stack_top->oops_do(f);
2846 }
2847
2848 // traverse the registered growable array
2849 if (_array_for_gc != NULL) {
2850 for (int index = 0; index < _array_for_gc->length(); index++) {
2851 f->do_oop(_array_for_gc->adr_at(index));
2852 }
2853 }
2854
2855 // Traverse the monitor chunks
2856 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2857 chunk->oops_do(f);
2858 }
2859
2860 // Traverse the execution stack
2861 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2862 fst.current()->oops_do(f, cf, fst.register_map());
2863 }
2864 }
2865
2866 // callee_target is never live across a gc point so NULL it here should
2867 // it still contain a methdOop.
2868
2869 set_callee_target(NULL);
2870
2871 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2872 // If we have deferred set_locals there might be oops waiting to be
2873 // written
2874 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2875 if (list != NULL) {
2876 for (int i = 0; i < list->length(); i++) {
2877 list->at(i)->oops_do(f);
2878 }
2879 }
2880
2881 // Traverse instance variables at the end since the GC may be moving things
2882 // around using this function
2883 f->do_oop((oop*) &_threadObj);
2884 f->do_oop((oop*) &_vm_result);
2885 f->do_oop((oop*) &_exception_oop);
2886 f->do_oop((oop*) &_pending_async_exception);
2887
2888 if (jvmti_thread_state() != NULL) {
2889 jvmti_thread_state()->oops_do(f);
2890 }
2891 }
2892
2893 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2894 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2895 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2896
2897 if (has_last_Java_frame()) {
2898 // Traverse the execution stack
2899 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2900 fst.current()->nmethods_do(cf);
2901 }
2902 }
2903 }
2904
2905 void JavaThread::metadata_do(void f(Metadata*)) {
2906 if (has_last_Java_frame()) {
2907 // Traverse the execution stack to call f() on the methods in the stack
2908 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2909 fst.current()->metadata_do(f);
2910 }
2911 } else if (is_Compiler_thread()) {
2912 // need to walk ciMetadata in current compile tasks to keep alive.
2913 CompilerThread* ct = (CompilerThread*)this;
2914 if (ct->env() != NULL) {
2915 ct->env()->metadata_do(f);
2916 }
2917 CompileTask* task = ct->task();
2918 if (task != NULL) {
2919 task->metadata_do(f);
2920 }
2921 }
2922 }
2923
2924 // Printing
2925 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2926 switch (_thread_state) {
2927 case _thread_uninitialized: return "_thread_uninitialized";
2928 case _thread_new: return "_thread_new";
2929 case _thread_new_trans: return "_thread_new_trans";
2930 case _thread_in_native: return "_thread_in_native";
2931 case _thread_in_native_trans: return "_thread_in_native_trans";
2932 case _thread_in_vm: return "_thread_in_vm";
2933 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2934 case _thread_in_Java: return "_thread_in_Java";
2935 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2936 case _thread_blocked: return "_thread_blocked";
2937 case _thread_blocked_trans: return "_thread_blocked_trans";
2938 default: return "unknown thread state";
2939 }
2940 }
2941
2942 #ifndef PRODUCT
2943 void JavaThread::print_thread_state_on(outputStream *st) const {
2944 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2945 };
2946 void JavaThread::print_thread_state() const {
2947 print_thread_state_on(tty);
2948 }
2949 #endif // PRODUCT
2950
2951 // Called by Threads::print() for VM_PrintThreads operation
2952 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2953 st->print_raw("\"");
2954 st->print_raw(get_thread_name());
2955 st->print_raw("\" ");
2956 oop thread_oop = threadObj();
2957 if (thread_oop != NULL) {
2958 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2959 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2960 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2961 }
2962 Thread::print_on(st, print_extended_info);
2963 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2964 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2965 if (thread_oop != NULL) {
2966 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2967 }
2968 #ifndef PRODUCT
2969 print_thread_state_on(st);
2970 _safepoint_state->print_on(st);
2971 #endif // PRODUCT
2972 if (is_Compiler_thread()) {
2973 CompileTask *task = ((CompilerThread*)this)->task();
2974 if (task != NULL) {
2975 st->print(" Compiling: ");
2976 task->print(st, NULL, true, false);
2977 } else {
2978 st->print(" No compile task");
2979 }
2980 st->cr();
2981 }
2982 }
2983
2984 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2985 st->print("%s", get_thread_name_string(buf, buflen));
2986 }
2987
2988 // Called by fatal error handler. The difference between this and
2989 // JavaThread::print() is that we can't grab lock or allocate memory.
2990 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2991 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2992 oop thread_obj = threadObj();
2993 if (thread_obj != NULL) {
2994 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2995 }
2996 st->print(" [");
2997 st->print("%s", _get_thread_state_name(_thread_state));
2998 if (osthread()) {
2999 st->print(", id=%d", osthread()->thread_id());
3000 }
3001 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3002 p2i(stack_end()), p2i(stack_base()));
3003 st->print("]");
3004
3005 ThreadsSMRSupport::print_info_on(this, st);
3006 return;
3007 }
3008
3009 // Verification
3010
3011 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3012
3013 void JavaThread::verify() {
3014 // Verify oops in the thread.
3015 oops_do(&VerifyOopClosure::verify_oop, NULL);
3016
3017 // Verify the stack frames.
3018 frames_do(frame_verify);
3019 }
3020
3021 // CR 6300358 (sub-CR 2137150)
3022 // Most callers of this method assume that it can't return NULL but a
3023 // thread may not have a name whilst it is in the process of attaching to
3024 // the VM - see CR 6412693, and there are places where a JavaThread can be
3025 // seen prior to having it's threadObj set (eg JNI attaching threads and
3026 // if vm exit occurs during initialization). These cases can all be accounted
3027 // for such that this method never returns NULL.
3028 const char* JavaThread::get_thread_name() const {
3029 #ifdef ASSERT
3030 // early safepoints can hit while current thread does not yet have TLS
3031 if (!SafepointSynchronize::is_at_safepoint()) {
3032 Thread *cur = Thread::current();
3033 if (!(cur->is_Java_thread() && cur == this)) {
3034 // Current JavaThreads are allowed to get their own name without
3035 // the Threads_lock.
3036 assert_locked_or_safepoint(Threads_lock);
3037 }
3038 }
3039 #endif // ASSERT
3040 return get_thread_name_string();
3041 }
3042
3043 // Returns a non-NULL representation of this thread's name, or a suitable
3044 // descriptive string if there is no set name
3045 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3046 const char* name_str;
3047 oop thread_obj = threadObj();
3048 if (thread_obj != NULL) {
3049 oop name = java_lang_Thread::name(thread_obj);
3050 if (name != NULL) {
3051 if (buf == NULL) {
3052 name_str = java_lang_String::as_utf8_string(name);
3053 } else {
3054 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3055 }
3056 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3057 name_str = "<no-name - thread is attaching>";
3058 } else {
3059 name_str = Thread::name();
3060 }
3061 } else {
3062 name_str = Thread::name();
3063 }
3064 assert(name_str != NULL, "unexpected NULL thread name");
3065 return name_str;
3066 }
3067
3068
3069 const char* JavaThread::get_threadgroup_name() const {
3070 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3071 oop thread_obj = threadObj();
3072 if (thread_obj != NULL) {
3073 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3074 if (thread_group != NULL) {
3075 // ThreadGroup.name can be null
3076 return java_lang_ThreadGroup::name(thread_group);
3077 }
3078 }
3079 return NULL;
3080 }
3081
3082 const char* JavaThread::get_parent_name() const {
3083 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3084 oop thread_obj = threadObj();
3085 if (thread_obj != NULL) {
3086 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3087 if (thread_group != NULL) {
3088 oop parent = java_lang_ThreadGroup::parent(thread_group);
3089 if (parent != NULL) {
3090 // ThreadGroup.name can be null
3091 return java_lang_ThreadGroup::name(parent);
3092 }
3093 }
3094 }
3095 return NULL;
3096 }
3097
3098 ThreadPriority JavaThread::java_priority() const {
3099 oop thr_oop = threadObj();
3100 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3101 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3102 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3103 return priority;
3104 }
3105
3106 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3107
3108 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3109 // Link Java Thread object <-> C++ Thread
3110
3111 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3112 // and put it into a new Handle. The Handle "thread_oop" can then
3113 // be used to pass the C++ thread object to other methods.
3114
3115 // Set the Java level thread object (jthread) field of the
3116 // new thread (a JavaThread *) to C++ thread object using the
3117 // "thread_oop" handle.
3118
3119 // Set the thread field (a JavaThread *) of the
3120 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3121
3122 Handle thread_oop(Thread::current(),
3123 JNIHandles::resolve_non_null(jni_thread));
3124 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3125 "must be initialized");
3126 set_threadObj(thread_oop());
3127 java_lang_Thread::set_thread(thread_oop(), this);
3128
3129 if (prio == NoPriority) {
3130 prio = java_lang_Thread::priority(thread_oop());
3131 assert(prio != NoPriority, "A valid priority should be present");
3132 }
3133
3134 // Push the Java priority down to the native thread; needs Threads_lock
3135 Thread::set_priority(this, prio);
3136
3137 // Add the new thread to the Threads list and set it in motion.
3138 // We must have threads lock in order to call Threads::add.
3139 // It is crucial that we do not block before the thread is
3140 // added to the Threads list for if a GC happens, then the java_thread oop
3141 // will not be visited by GC.
3142 Threads::add(this);
3143 }
3144
3145 oop JavaThread::current_park_blocker() {
3146 // Support for JSR-166 locks
3147 oop thread_oop = threadObj();
3148 if (thread_oop != NULL &&
3149 JDK_Version::current().supports_thread_park_blocker()) {
3150 return java_lang_Thread::park_blocker(thread_oop);
3151 }
3152 return NULL;
3153 }
3154
3155
3156 void JavaThread::print_stack_on(outputStream* st) {
3157 if (!has_last_Java_frame()) return;
3158 ResourceMark rm;
3159 HandleMark hm;
3160
3161 RegisterMap reg_map(this);
3162 vframe* start_vf = last_java_vframe(®_map);
3163 int count = 0;
3164 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3165 if (f->is_java_frame()) {
3166 javaVFrame* jvf = javaVFrame::cast(f);
3167 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3168
3169 // Print out lock information
3170 if (JavaMonitorsInStackTrace) {
3171 jvf->print_lock_info_on(st, count);
3172 }
3173 } else {
3174 // Ignore non-Java frames
3175 }
3176
3177 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3178 count++;
3179 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3180 }
3181 }
3182
3183
3184 // JVMTI PopFrame support
3185 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3186 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3187 if (in_bytes(size_in_bytes) != 0) {
3188 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3189 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3190 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3191 }
3192 }
3193
3194 void* JavaThread::popframe_preserved_args() {
3195 return _popframe_preserved_args;
3196 }
3197
3198 ByteSize JavaThread::popframe_preserved_args_size() {
3199 return in_ByteSize(_popframe_preserved_args_size);
3200 }
3201
3202 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3203 int sz = in_bytes(popframe_preserved_args_size());
3204 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3205 return in_WordSize(sz / wordSize);
3206 }
3207
3208 void JavaThread::popframe_free_preserved_args() {
3209 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3210 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3211 _popframe_preserved_args = NULL;
3212 _popframe_preserved_args_size = 0;
3213 }
3214
3215 #ifndef PRODUCT
3216
3217 void JavaThread::trace_frames() {
3218 tty->print_cr("[Describe stack]");
3219 int frame_no = 1;
3220 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3221 tty->print(" %d. ", frame_no++);
3222 fst.current()->print_value_on(tty, this);
3223 tty->cr();
3224 }
3225 }
3226
3227 class PrintAndVerifyOopClosure: public OopClosure {
3228 protected:
3229 template <class T> inline void do_oop_work(T* p) {
3230 oop obj = RawAccess<>::oop_load(p);
3231 if (obj == NULL) return;
3232 tty->print(INTPTR_FORMAT ": ", p2i(p));
3233 if (oopDesc::is_oop_or_null(obj)) {
3234 if (obj->is_objArray()) {
3235 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3236 } else {
3237 obj->print();
3238 }
3239 } else {
3240 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3241 }
3242 tty->cr();
3243 }
3244 public:
3245 virtual void do_oop(oop* p) { do_oop_work(p); }
3246 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3247 };
3248
3249
3250 static void oops_print(frame* f, const RegisterMap *map) {
3251 PrintAndVerifyOopClosure print;
3252 f->print_value();
3253 f->oops_do(&print, NULL, (RegisterMap*)map);
3254 }
3255
3256 // Print our all the locations that contain oops and whether they are
3257 // valid or not. This useful when trying to find the oldest frame
3258 // where an oop has gone bad since the frame walk is from youngest to
3259 // oldest.
3260 void JavaThread::trace_oops() {
3261 tty->print_cr("[Trace oops]");
3262 frames_do(oops_print);
3263 }
3264
3265
3266 #ifdef ASSERT
3267 // Print or validate the layout of stack frames
3268 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3269 ResourceMark rm;
3270 PRESERVE_EXCEPTION_MARK;
3271 FrameValues values;
3272 int frame_no = 0;
3273 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3274 fst.current()->describe(values, ++frame_no);
3275 if (depth == frame_no) break;
3276 }
3277 if (validate_only) {
3278 values.validate();
3279 } else {
3280 tty->print_cr("[Describe stack layout]");
3281 values.print(this);
3282 }
3283 }
3284 #endif
3285
3286 void JavaThread::trace_stack_from(vframe* start_vf) {
3287 ResourceMark rm;
3288 int vframe_no = 1;
3289 for (vframe* f = start_vf; f; f = f->sender()) {
3290 if (f->is_java_frame()) {
3291 javaVFrame::cast(f)->print_activation(vframe_no++);
3292 } else {
3293 f->print();
3294 }
3295 if (vframe_no > StackPrintLimit) {
3296 tty->print_cr("...<more frames>...");
3297 return;
3298 }
3299 }
3300 }
3301
3302
3303 void JavaThread::trace_stack() {
3304 if (!has_last_Java_frame()) return;
3305 ResourceMark rm;
3306 HandleMark hm;
3307 RegisterMap reg_map(this);
3308 trace_stack_from(last_java_vframe(®_map));
3309 }
3310
3311
3312 #endif // PRODUCT
3313
3314
3315 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3316 assert(reg_map != NULL, "a map must be given");
3317 frame f = last_frame();
3318 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3319 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3320 }
3321 return NULL;
3322 }
3323
3324
3325 Klass* JavaThread::security_get_caller_class(int depth) {
3326 vframeStream vfst(this);
3327 vfst.security_get_caller_frame(depth);
3328 if (!vfst.at_end()) {
3329 return vfst.method()->method_holder();
3330 }
3331 return NULL;
3332 }
3333
3334 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3335 assert(thread->is_Compiler_thread(), "must be compiler thread");
3336 CompileBroker::compiler_thread_loop();
3337 }
3338
3339 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3340 NMethodSweeper::sweeper_loop();
3341 }
3342
3343 // Create a CompilerThread
3344 CompilerThread::CompilerThread(CompileQueue* queue,
3345 CompilerCounters* counters)
3346 : JavaThread(&compiler_thread_entry) {
3347 _env = NULL;
3348 _log = NULL;
3349 _task = NULL;
3350 _queue = queue;
3351 _counters = counters;
3352 _buffer_blob = NULL;
3353 _compiler = NULL;
3354
3355 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3356 resource_area()->bias_to(mtCompiler);
3357
3358 #ifndef PRODUCT
3359 _ideal_graph_printer = NULL;
3360 #endif
3361 }
3362
3363 CompilerThread::~CompilerThread() {
3364 // Delete objects which were allocated on heap.
3365 delete _counters;
3366 }
3367
3368 bool CompilerThread::can_call_java() const {
3369 return _compiler != NULL && _compiler->is_jvmci();
3370 }
3371
3372 // Create sweeper thread
3373 CodeCacheSweeperThread::CodeCacheSweeperThread()
3374 : JavaThread(&sweeper_thread_entry) {
3375 _scanned_compiled_method = NULL;
3376 }
3377
3378 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3379 JavaThread::oops_do(f, cf);
3380 if (_scanned_compiled_method != NULL && cf != NULL) {
3381 // Safepoints can occur when the sweeper is scanning an nmethod so
3382 // process it here to make sure it isn't unloaded in the middle of
3383 // a scan.
3384 cf->do_code_blob(_scanned_compiled_method);
3385 }
3386 }
3387
3388 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3389 JavaThread::nmethods_do(cf);
3390 if (_scanned_compiled_method != NULL && cf != NULL) {
3391 // Safepoints can occur when the sweeper is scanning an nmethod so
3392 // process it here to make sure it isn't unloaded in the middle of
3393 // a scan.
3394 cf->do_code_blob(_scanned_compiled_method);
3395 }
3396 }
3397
3398
3399 // ======= Threads ========
3400
3401 // The Threads class links together all active threads, and provides
3402 // operations over all threads. It is protected by the Threads_lock,
3403 // which is also used in other global contexts like safepointing.
3404 // ThreadsListHandles are used to safely perform operations on one
3405 // or more threads without the risk of the thread exiting during the
3406 // operation.
3407 //
3408 // Note: The Threads_lock is currently more widely used than we
3409 // would like. We are actively migrating Threads_lock uses to other
3410 // mechanisms in order to reduce Threads_lock contention.
3411
3412 JavaThread* Threads::_thread_list = NULL;
3413 int Threads::_number_of_threads = 0;
3414 int Threads::_number_of_non_daemon_threads = 0;
3415 int Threads::_return_code = 0;
3416 int Threads::_thread_claim_parity = 0;
3417 size_t JavaThread::_stack_size_at_create = 0;
3418
3419 #ifdef ASSERT
3420 bool Threads::_vm_complete = false;
3421 size_t Threads::_threads_before_barrier_set = 0;
3422 #endif
3423
3424 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3425 Prefetch::read((void*)addr, prefetch_interval);
3426 return *addr;
3427 }
3428
3429 // Possibly the ugliest for loop the world has seen. C++ does not allow
3430 // multiple types in the declaration section of the for loop. In this case
3431 // we are only dealing with pointers and hence can cast them. It looks ugly
3432 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3433 #define DO_JAVA_THREADS(LIST, X) \
3434 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3435 *MACRO_list = (JavaThread*)(LIST), \
3436 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3437 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3438 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3439 MACRO_current_p != MACRO_end; \
3440 MACRO_current_p++, \
3441 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3442
3443 // All JavaThreads
3444 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3445
3446 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3447 void Threads::non_java_threads_do(ThreadClosure* tc) {
3448 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3449 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3450 tc->do_thread(njti.current());
3451 }
3452 }
3453
3454 // All JavaThreads
3455 void Threads::java_threads_do(ThreadClosure* tc) {
3456 assert_locked_or_safepoint(Threads_lock);
3457 // ALL_JAVA_THREADS iterates through all JavaThreads.
3458 ALL_JAVA_THREADS(p) {
3459 tc->do_thread(p);
3460 }
3461 }
3462
3463 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3464 assert_locked_or_safepoint(Threads_lock);
3465 java_threads_do(tc);
3466 tc->do_thread(VMThread::vm_thread());
3467 }
3468
3469 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3470 void Threads::threads_do(ThreadClosure* tc) {
3471 assert_locked_or_safepoint(Threads_lock);
3472 java_threads_do(tc);
3473 non_java_threads_do(tc);
3474 }
3475
3476 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3477 int cp = Threads::thread_claim_parity();
3478 ALL_JAVA_THREADS(p) {
3479 if (p->claim_oops_do(is_par, cp)) {
3480 tc->do_thread(p);
3481 }
3482 }
3483 VMThread* vmt = VMThread::vm_thread();
3484 if (vmt->claim_oops_do(is_par, cp)) {
3485 tc->do_thread(vmt);
3486 }
3487 }
3488
3489 // The system initialization in the library has three phases.
3490 //
3491 // Phase 1: java.lang.System class initialization
3492 // java.lang.System is a primordial class loaded and initialized
3493 // by the VM early during startup. java.lang.System.<clinit>
3494 // only does registerNatives and keeps the rest of the class
3495 // initialization work later until thread initialization completes.
3496 //
3497 // System.initPhase1 initializes the system properties, the static
3498 // fields in, out, and err. Set up java signal handlers, OS-specific
3499 // system settings, and thread group of the main thread.
3500 static void call_initPhase1(TRAPS) {
3501 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3502 JavaValue result(T_VOID);
3503 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3504 vmSymbols::void_method_signature(), CHECK);
3505 }
3506
3507 // Phase 2. Module system initialization
3508 // This will initialize the module system. Only java.base classes
3509 // can be loaded until phase 2 completes.
3510 //
3511 // Call System.initPhase2 after the compiler initialization and jsr292
3512 // classes get initialized because module initialization runs a lot of java
3513 // code, that for performance reasons, should be compiled. Also, this will
3514 // enable the startup code to use lambda and other language features in this
3515 // phase and onward.
3516 //
3517 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3518 static void call_initPhase2(TRAPS) {
3519 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3520
3521 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3522
3523 JavaValue result(T_INT);
3524 JavaCallArguments args;
3525 args.push_int(DisplayVMOutputToStderr);
3526 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3527 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3528 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3529 if (result.get_jint() != JNI_OK) {
3530 vm_exit_during_initialization(); // no message or exception
3531 }
3532
3533 universe_post_module_init();
3534 }
3535
3536 // Phase 3. final setup - set security manager, system class loader and TCCL
3537 //
3538 // This will instantiate and set the security manager, set the system class
3539 // loader as well as the thread context class loader. The security manager
3540 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3541 // other modules or the application's classpath.
3542 static void call_initPhase3(TRAPS) {
3543 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3544 JavaValue result(T_VOID);
3545 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3546 vmSymbols::void_method_signature(), CHECK);
3547 }
3548
3549 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3550 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3551
3552 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3553 create_vm_init_libraries();
3554 }
3555
3556 initialize_class(vmSymbols::java_lang_String(), CHECK);
3557
3558 // Inject CompactStrings value after the static initializers for String ran.
3559 java_lang_String::set_compact_strings(CompactStrings);
3560
3561 // Initialize java_lang.System (needed before creating the thread)
3562 initialize_class(vmSymbols::java_lang_System(), CHECK);
3563 // The VM creates & returns objects of this class. Make sure it's initialized.
3564 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3565 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3566 Handle thread_group = create_initial_thread_group(CHECK);
3567 Universe::set_main_thread_group(thread_group());
3568 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3569 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3570 main_thread->set_threadObj(thread_object);
3571 // Set thread status to running since main thread has
3572 // been started and running.
3573 java_lang_Thread::set_thread_status(thread_object,
3574 java_lang_Thread::RUNNABLE);
3575
3576 // The VM creates objects of this class.
3577 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3578
3579 // The VM preresolves methods to these classes. Make sure that they get initialized
3580 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3581 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3582
3583 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3584 call_initPhase1(CHECK);
3585
3586 // get the Java runtime name after java.lang.System is initialized
3587 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3588 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3589
3590 // an instance of OutOfMemory exception has been allocated earlier
3591 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3592 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3593 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3594 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3595 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3596 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3597 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3598 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3599 }
3600
3601 void Threads::initialize_jsr292_core_classes(TRAPS) {
3602 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3603
3604 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3605 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3606 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3607 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3608 }
3609
3610 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3611 extern void JDK_Version_init();
3612
3613 // Preinitialize version info.
3614 VM_Version::early_initialize();
3615
3616 // Check version
3617 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3618
3619 // Initialize library-based TLS
3620 ThreadLocalStorage::init();
3621
3622 // Initialize the output stream module
3623 ostream_init();
3624
3625 // Process java launcher properties.
3626 Arguments::process_sun_java_launcher_properties(args);
3627
3628 // Initialize the os module
3629 os::init();
3630
3631 // Record VM creation timing statistics
3632 TraceVmCreationTime create_vm_timer;
3633 create_vm_timer.start();
3634
3635 // Initialize system properties.
3636 Arguments::init_system_properties();
3637
3638 // So that JDK version can be used as a discriminator when parsing arguments
3639 JDK_Version_init();
3640
3641 // Update/Initialize System properties after JDK version number is known
3642 Arguments::init_version_specific_system_properties();
3643
3644 // Make sure to initialize log configuration *before* parsing arguments
3645 LogConfiguration::initialize(create_vm_timer.begin_time());
3646
3647 // Parse arguments
3648 // Note: this internally calls os::init_container_support()
3649 jint parse_result = Arguments::parse(args);
3650 if (parse_result != JNI_OK) return parse_result;
3651
3652 os::init_before_ergo();
3653
3654 jint ergo_result = Arguments::apply_ergo();
3655 if (ergo_result != JNI_OK) return ergo_result;
3656
3657 // Final check of all ranges after ergonomics which may change values.
3658 if (!JVMFlagRangeList::check_ranges()) {
3659 return JNI_EINVAL;
3660 }
3661
3662 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3663 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3664 if (!constraint_result) {
3665 return JNI_EINVAL;
3666 }
3667
3668 JVMFlagWriteableList::mark_startup();
3669
3670 if (PauseAtStartup) {
3671 os::pause();
3672 }
3673
3674 HOTSPOT_VM_INIT_BEGIN();
3675
3676 // Timing (must come after argument parsing)
3677 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3678
3679 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3680 // Initialize assert poison page mechanism.
3681 if (ShowRegistersOnAssert) {
3682 initialize_assert_poison();
3683 }
3684 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3685
3686 // Initialize the os module after parsing the args
3687 jint os_init_2_result = os::init_2();
3688 if (os_init_2_result != JNI_OK) return os_init_2_result;
3689
3690 SafepointMechanism::initialize();
3691
3692 jint adjust_after_os_result = Arguments::adjust_after_os();
3693 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3694
3695 // Initialize output stream logging
3696 ostream_init_log();
3697
3698 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3699 // Must be before create_vm_init_agents()
3700 if (Arguments::init_libraries_at_startup()) {
3701 convert_vm_init_libraries_to_agents();
3702 }
3703
3704 // Launch -agentlib/-agentpath and converted -Xrun agents
3705 if (Arguments::init_agents_at_startup()) {
3706 create_vm_init_agents();
3707 }
3708
3709 // Initialize Threads state
3710 _thread_list = NULL;
3711 _number_of_threads = 0;
3712 _number_of_non_daemon_threads = 0;
3713
3714 // Initialize global data structures and create system classes in heap
3715 vm_init_globals();
3716
3717 #if INCLUDE_JVMCI
3718 if (JVMCICounterSize > 0) {
3719 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3720 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3721 } else {
3722 JavaThread::_jvmci_old_thread_counters = NULL;
3723 }
3724 #endif // INCLUDE_JVMCI
3725
3726 // Attach the main thread to this os thread
3727 JavaThread* main_thread = new JavaThread();
3728 main_thread->set_thread_state(_thread_in_vm);
3729 main_thread->initialize_thread_current();
3730 // must do this before set_active_handles
3731 main_thread->record_stack_base_and_size();
3732 main_thread->register_thread_stack_with_NMT();
3733 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3734
3735 if (!main_thread->set_as_starting_thread()) {
3736 vm_shutdown_during_initialization(
3737 "Failed necessary internal allocation. Out of swap space");
3738 main_thread->smr_delete();
3739 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3740 return JNI_ENOMEM;
3741 }
3742
3743 // Enable guard page *after* os::create_main_thread(), otherwise it would
3744 // crash Linux VM, see notes in os_linux.cpp.
3745 main_thread->create_stack_guard_pages();
3746
3747 // Initialize Java-Level synchronization subsystem
3748 ObjectMonitor::Initialize();
3749
3750 // Initialize global modules
3751 jint status = init_globals();
3752 if (status != JNI_OK) {
3753 main_thread->smr_delete();
3754 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3755 return status;
3756 }
3757
3758 JFR_ONLY(Jfr::on_vm_init();)
3759
3760 // Should be done after the heap is fully created
3761 main_thread->cache_global_variables();
3762
3763 HandleMark hm;
3764
3765 { MutexLocker mu(Threads_lock);
3766 Threads::add(main_thread);
3767 }
3768
3769 // Any JVMTI raw monitors entered in onload will transition into
3770 // real raw monitor. VM is setup enough here for raw monitor enter.
3771 JvmtiExport::transition_pending_onload_raw_monitors();
3772
3773 // Create the VMThread
3774 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3775
3776 VMThread::create();
3777 Thread* vmthread = VMThread::vm_thread();
3778
3779 if (!os::create_thread(vmthread, os::vm_thread)) {
3780 vm_exit_during_initialization("Cannot create VM thread. "
3781 "Out of system resources.");
3782 }
3783
3784 // Wait for the VM thread to become ready, and VMThread::run to initialize
3785 // Monitors can have spurious returns, must always check another state flag
3786 {
3787 MutexLocker ml(Notify_lock);
3788 os::start_thread(vmthread);
3789 while (vmthread->active_handles() == NULL) {
3790 Notify_lock->wait();
3791 }
3792 }
3793 }
3794
3795 assert(Universe::is_fully_initialized(), "not initialized");
3796 if (VerifyDuringStartup) {
3797 // Make sure we're starting with a clean slate.
3798 VM_Verify verify_op;
3799 VMThread::execute(&verify_op);
3800 }
3801
3802 // We need this to update the java.vm.info property in case any flags used
3803 // to initially define it have been changed. This is needed for both CDS and
3804 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3805 // is initially computed. See Abstract_VM_Version::vm_info_string().
3806 // This update must happen before we initialize the java classes, but
3807 // after any initialization logic that might modify the flags.
3808 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3809
3810 Thread* THREAD = Thread::current();
3811
3812 // Always call even when there are not JVMTI environments yet, since environments
3813 // may be attached late and JVMTI must track phases of VM execution
3814 JvmtiExport::enter_early_start_phase();
3815
3816 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3817 JvmtiExport::post_early_vm_start();
3818
3819 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3820
3821 quicken_jni_functions();
3822
3823 // No more stub generation allowed after that point.
3824 StubCodeDesc::freeze();
3825
3826 // Set flag that basic initialization has completed. Used by exceptions and various
3827 // debug stuff, that does not work until all basic classes have been initialized.
3828 set_init_completed();
3829
3830 LogConfiguration::post_initialize();
3831 Metaspace::post_initialize();
3832
3833 HOTSPOT_VM_INIT_END();
3834
3835 // record VM initialization completion time
3836 #if INCLUDE_MANAGEMENT
3837 Management::record_vm_init_completed();
3838 #endif // INCLUDE_MANAGEMENT
3839
3840 // Signal Dispatcher needs to be started before VMInit event is posted
3841 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3842
3843 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3844 if (!DisableAttachMechanism) {
3845 AttachListener::vm_start();
3846 if (StartAttachListener || AttachListener::init_at_startup()) {
3847 AttachListener::init();
3848 }
3849 }
3850
3851 // Launch -Xrun agents
3852 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3853 // back-end can launch with -Xdebug -Xrunjdwp.
3854 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3855 create_vm_init_libraries();
3856 }
3857
3858 if (CleanChunkPoolAsync) {
3859 Chunk::start_chunk_pool_cleaner_task();
3860 }
3861
3862 // initialize compiler(s)
3863 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3864 #if INCLUDE_JVMCI
3865 bool force_JVMCI_intialization = false;
3866 if (EnableJVMCI) {
3867 // Initialize JVMCI eagerly when it is explicitly requested.
3868 // Or when JVMCIPrintProperties is enabled.
3869 // The JVMCI Java initialization code will read this flag and
3870 // do the printing if it's set.
3871 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3872
3873 if (!force_JVMCI_intialization) {
3874 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3875 // compilations via JVMCI will not actually block until JVMCI is initialized.
3876 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3877 }
3878 }
3879 #endif
3880 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3881 // Postpone completion of compiler initialization to after JVMCI
3882 // is initialized to avoid timeouts of blocking compilations.
3883 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3884 CompileBroker::compilation_init_phase2();
3885 }
3886 #endif
3887
3888 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3889 // It is done after compilers are initialized, because otherwise compilations of
3890 // signature polymorphic MH intrinsics can be missed
3891 // (see SystemDictionary::find_method_handle_intrinsic).
3892 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3893
3894 // This will initialize the module system. Only java.base classes can be
3895 // loaded until phase 2 completes
3896 call_initPhase2(CHECK_JNI_ERR);
3897
3898 // Always call even when there are not JVMTI environments yet, since environments
3899 // may be attached late and JVMTI must track phases of VM execution
3900 JvmtiExport::enter_start_phase();
3901
3902 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3903 JvmtiExport::post_vm_start();
3904
3905 // Final system initialization including security manager and system class loader
3906 call_initPhase3(CHECK_JNI_ERR);
3907
3908 // cache the system and platform class loaders
3909 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3910
3911 #if INCLUDE_CDS
3912 if (DumpSharedSpaces) {
3913 // capture the module path info from the ModuleEntryTable
3914 ClassLoader::initialize_module_path(THREAD);
3915 }
3916 #endif
3917
3918 #if INCLUDE_JVMCI
3919 if (force_JVMCI_intialization) {
3920 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3921 CompileBroker::compilation_init_phase2();
3922 }
3923 #endif
3924
3925 // Always call even when there are not JVMTI environments yet, since environments
3926 // may be attached late and JVMTI must track phases of VM execution
3927 JvmtiExport::enter_live_phase();
3928
3929 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3930 JvmtiExport::post_vm_initialized();
3931
3932 JFR_ONLY(Jfr::on_vm_start();)
3933
3934 #if INCLUDE_MANAGEMENT
3935 Management::initialize(THREAD);
3936
3937 if (HAS_PENDING_EXCEPTION) {
3938 // management agent fails to start possibly due to
3939 // configuration problem and is responsible for printing
3940 // stack trace if appropriate. Simply exit VM.
3941 vm_exit(1);
3942 }
3943 #endif // INCLUDE_MANAGEMENT
3944
3945 if (MemProfiling) MemProfiler::engage();
3946 StatSampler::engage();
3947 if (CheckJNICalls) JniPeriodicChecker::engage();
3948
3949 BiasedLocking::init();
3950
3951 #if INCLUDE_RTM_OPT
3952 RTMLockingCounters::init();
3953 #endif
3954
3955 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3956 call_postVMInitHook(THREAD);
3957 // The Java side of PostVMInitHook.run must deal with all
3958 // exceptions and provide means of diagnosis.
3959 if (HAS_PENDING_EXCEPTION) {
3960 CLEAR_PENDING_EXCEPTION;
3961 }
3962 }
3963
3964 {
3965 MutexLocker ml(PeriodicTask_lock);
3966 // Make sure the WatcherThread can be started by WatcherThread::start()
3967 // or by dynamic enrollment.
3968 WatcherThread::make_startable();
3969 // Start up the WatcherThread if there are any periodic tasks
3970 // NOTE: All PeriodicTasks should be registered by now. If they
3971 // aren't, late joiners might appear to start slowly (we might
3972 // take a while to process their first tick).
3973 if (PeriodicTask::num_tasks() > 0) {
3974 WatcherThread::start();
3975 }
3976 }
3977
3978 create_vm_timer.end();
3979 #ifdef ASSERT
3980 _vm_complete = true;
3981 #endif
3982
3983 if (DumpSharedSpaces) {
3984 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3985 ShouldNotReachHere();
3986 }
3987
3988 return JNI_OK;
3989 }
3990
3991 // type for the Agent_OnLoad and JVM_OnLoad entry points
3992 extern "C" {
3993 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3994 }
3995 // Find a command line agent library and return its entry point for
3996 // -agentlib: -agentpath: -Xrun
3997 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3998 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3999 const char *on_load_symbols[],
4000 size_t num_symbol_entries) {
4001 OnLoadEntry_t on_load_entry = NULL;
4002 void *library = NULL;
4003
4004 if (!agent->valid()) {
4005 char buffer[JVM_MAXPATHLEN];
4006 char ebuf[1024] = "";
4007 const char *name = agent->name();
4008 const char *msg = "Could not find agent library ";
4009
4010 // First check to see if agent is statically linked into executable
4011 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4012 library = agent->os_lib();
4013 } else if (agent->is_absolute_path()) {
4014 library = os::dll_load(name, ebuf, sizeof ebuf);
4015 if (library == NULL) {
4016 const char *sub_msg = " in absolute path, with error: ";
4017 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4018 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4019 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4020 // If we can't find the agent, exit.
4021 vm_exit_during_initialization(buf, NULL);
4022 FREE_C_HEAP_ARRAY(char, buf);
4023 }
4024 } else {
4025 // Try to load the agent from the standard dll directory
4026 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4027 name)) {
4028 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4029 }
4030 if (library == NULL) { // Try the library path directory.
4031 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4032 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4033 }
4034 if (library == NULL) {
4035 const char *sub_msg = " on the library path, with error: ";
4036 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4037
4038 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4039 strlen(ebuf) + strlen(sub_msg2) + 1;
4040 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4041 if (!agent->is_instrument_lib()) {
4042 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4043 } else {
4044 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4045 }
4046 // If we can't find the agent, exit.
4047 vm_exit_during_initialization(buf, NULL);
4048 FREE_C_HEAP_ARRAY(char, buf);
4049 }
4050 }
4051 }
4052 agent->set_os_lib(library);
4053 agent->set_valid();
4054 }
4055
4056 // Find the OnLoad function.
4057 on_load_entry =
4058 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4059 false,
4060 on_load_symbols,
4061 num_symbol_entries));
4062 return on_load_entry;
4063 }
4064
4065 // Find the JVM_OnLoad entry point
4066 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4067 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4068 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4069 }
4070
4071 // Find the Agent_OnLoad entry point
4072 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4073 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4074 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4075 }
4076
4077 // For backwards compatibility with -Xrun
4078 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4079 // treated like -agentpath:
4080 // Must be called before agent libraries are created
4081 void Threads::convert_vm_init_libraries_to_agents() {
4082 AgentLibrary* agent;
4083 AgentLibrary* next;
4084
4085 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4086 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4087 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4088
4089 // If there is an JVM_OnLoad function it will get called later,
4090 // otherwise see if there is an Agent_OnLoad
4091 if (on_load_entry == NULL) {
4092 on_load_entry = lookup_agent_on_load(agent);
4093 if (on_load_entry != NULL) {
4094 // switch it to the agent list -- so that Agent_OnLoad will be called,
4095 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4096 Arguments::convert_library_to_agent(agent);
4097 } else {
4098 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4099 }
4100 }
4101 }
4102 }
4103
4104 // Create agents for -agentlib: -agentpath: and converted -Xrun
4105 // Invokes Agent_OnLoad
4106 // Called very early -- before JavaThreads exist
4107 void Threads::create_vm_init_agents() {
4108 extern struct JavaVM_ main_vm;
4109 AgentLibrary* agent;
4110
4111 JvmtiExport::enter_onload_phase();
4112
4113 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4114 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4115
4116 if (on_load_entry != NULL) {
4117 // Invoke the Agent_OnLoad function
4118 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4119 if (err != JNI_OK) {
4120 vm_exit_during_initialization("agent library failed to init", agent->name());
4121 }
4122 } else {
4123 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4124 }
4125 }
4126 JvmtiExport::enter_primordial_phase();
4127 }
4128
4129 extern "C" {
4130 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4131 }
4132
4133 void Threads::shutdown_vm_agents() {
4134 // Send any Agent_OnUnload notifications
4135 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4136 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4137 extern struct JavaVM_ main_vm;
4138 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4139
4140 // Find the Agent_OnUnload function.
4141 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4142 os::find_agent_function(agent,
4143 false,
4144 on_unload_symbols,
4145 num_symbol_entries));
4146
4147 // Invoke the Agent_OnUnload function
4148 if (unload_entry != NULL) {
4149 JavaThread* thread = JavaThread::current();
4150 ThreadToNativeFromVM ttn(thread);
4151 HandleMark hm(thread);
4152 (*unload_entry)(&main_vm);
4153 }
4154 }
4155 }
4156
4157 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4158 // Invokes JVM_OnLoad
4159 void Threads::create_vm_init_libraries() {
4160 extern struct JavaVM_ main_vm;
4161 AgentLibrary* agent;
4162
4163 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4164 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4165
4166 if (on_load_entry != NULL) {
4167 // Invoke the JVM_OnLoad function
4168 JavaThread* thread = JavaThread::current();
4169 ThreadToNativeFromVM ttn(thread);
4170 HandleMark hm(thread);
4171 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4172 if (err != JNI_OK) {
4173 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4174 }
4175 } else {
4176 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4177 }
4178 }
4179 }
4180
4181
4182 // Last thread running calls java.lang.Shutdown.shutdown()
4183 void JavaThread::invoke_shutdown_hooks() {
4184 HandleMark hm(this);
4185
4186 // We could get here with a pending exception, if so clear it now.
4187 if (this->has_pending_exception()) {
4188 this->clear_pending_exception();
4189 }
4190
4191 EXCEPTION_MARK;
4192 Klass* shutdown_klass =
4193 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4194 THREAD);
4195 if (shutdown_klass != NULL) {
4196 // SystemDictionary::resolve_or_null will return null if there was
4197 // an exception. If we cannot load the Shutdown class, just don't
4198 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4199 // won't be run. Note that if a shutdown hook was registered,
4200 // the Shutdown class would have already been loaded
4201 // (Runtime.addShutdownHook will load it).
4202 JavaValue result(T_VOID);
4203 JavaCalls::call_static(&result,
4204 shutdown_klass,
4205 vmSymbols::shutdown_method_name(),
4206 vmSymbols::void_method_signature(),
4207 THREAD);
4208 }
4209 CLEAR_PENDING_EXCEPTION;
4210 }
4211
4212 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4213 // the program falls off the end of main(). Another VM exit path is through
4214 // vm_exit() when the program calls System.exit() to return a value or when
4215 // there is a serious error in VM. The two shutdown paths are not exactly
4216 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4217 // and VM_Exit op at VM level.
4218 //
4219 // Shutdown sequence:
4220 // + Shutdown native memory tracking if it is on
4221 // + Wait until we are the last non-daemon thread to execute
4222 // <-- every thing is still working at this moment -->
4223 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4224 // shutdown hooks
4225 // + Call before_exit(), prepare for VM exit
4226 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4227 // currently the only user of this mechanism is File.deleteOnExit())
4228 // > stop StatSampler, watcher thread, CMS threads,
4229 // post thread end and vm death events to JVMTI,
4230 // stop signal thread
4231 // + Call JavaThread::exit(), it will:
4232 // > release JNI handle blocks, remove stack guard pages
4233 // > remove this thread from Threads list
4234 // <-- no more Java code from this thread after this point -->
4235 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4236 // the compiler threads at safepoint
4237 // <-- do not use anything that could get blocked by Safepoint -->
4238 // + Disable tracing at JNI/JVM barriers
4239 // + Set _vm_exited flag for threads that are still running native code
4240 // + Call exit_globals()
4241 // > deletes tty
4242 // > deletes PerfMemory resources
4243 // + Delete this thread
4244 // + Return to caller
4245
4246 bool Threads::destroy_vm() {
4247 JavaThread* thread = JavaThread::current();
4248
4249 #ifdef ASSERT
4250 _vm_complete = false;
4251 #endif
4252 // Wait until we are the last non-daemon thread to execute
4253 { MutexLocker nu(Threads_lock);
4254 while (Threads::number_of_non_daemon_threads() > 1)
4255 // This wait should make safepoint checks, wait without a timeout,
4256 // and wait as a suspend-equivalent condition.
4257 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4258 Mutex::_as_suspend_equivalent_flag);
4259 }
4260
4261 EventShutdown e;
4262 if (e.should_commit()) {
4263 e.set_reason("No remaining non-daemon Java threads");
4264 e.commit();
4265 }
4266
4267 // Hang forever on exit if we are reporting an error.
4268 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4269 os::infinite_sleep();
4270 }
4271 os::wait_for_keypress_at_exit();
4272
4273 // run Java level shutdown hooks
4274 thread->invoke_shutdown_hooks();
4275
4276 before_exit(thread);
4277
4278 thread->exit(true);
4279
4280 // Stop VM thread.
4281 {
4282 // 4945125 The vm thread comes to a safepoint during exit.
4283 // GC vm_operations can get caught at the safepoint, and the
4284 // heap is unparseable if they are caught. Grab the Heap_lock
4285 // to prevent this. The GC vm_operations will not be able to
4286 // queue until after the vm thread is dead. After this point,
4287 // we'll never emerge out of the safepoint before the VM exits.
4288
4289 MutexLocker ml(Heap_lock);
4290
4291 VMThread::wait_for_vm_thread_exit();
4292 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4293 VMThread::destroy();
4294 }
4295
4296 // Now, all Java threads are gone except daemon threads. Daemon threads
4297 // running Java code or in VM are stopped by the Safepoint. However,
4298 // daemon threads executing native code are still running. But they
4299 // will be stopped at native=>Java/VM barriers. Note that we can't
4300 // simply kill or suspend them, as it is inherently deadlock-prone.
4301
4302 VM_Exit::set_vm_exited();
4303
4304 // Clean up ideal graph printers after the VMThread has started
4305 // the final safepoint which will block all the Compiler threads.
4306 // Note that this Thread has already logically exited so the
4307 // clean_up() function's use of a JavaThreadIteratorWithHandle
4308 // would be a problem except set_vm_exited() has remembered the
4309 // shutdown thread which is granted a policy exception.
4310 #if defined(COMPILER2) && !defined(PRODUCT)
4311 IdealGraphPrinter::clean_up();
4312 #endif
4313
4314 notify_vm_shutdown();
4315
4316 // exit_globals() will delete tty
4317 exit_globals();
4318
4319 // We are after VM_Exit::set_vm_exited() so we can't call
4320 // thread->smr_delete() or we will block on the Threads_lock.
4321 // Deleting the shutdown thread here is safe because another
4322 // JavaThread cannot have an active ThreadsListHandle for
4323 // this JavaThread.
4324 delete thread;
4325
4326 #if INCLUDE_JVMCI
4327 if (JVMCICounterSize > 0) {
4328 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4329 }
4330 #endif
4331
4332 LogConfiguration::finalize();
4333
4334 return true;
4335 }
4336
4337
4338 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4339 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4340 return is_supported_jni_version(version);
4341 }
4342
4343
4344 jboolean Threads::is_supported_jni_version(jint version) {
4345 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4346 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4347 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4348 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4349 if (version == JNI_VERSION_9) return JNI_TRUE;
4350 if (version == JNI_VERSION_10) return JNI_TRUE;
4351 return JNI_FALSE;
4352 }
4353
4354
4355 void Threads::add(JavaThread* p, bool force_daemon) {
4356 // The threads lock must be owned at this point
4357 assert(Threads_lock->owned_by_self(), "must have threads lock");
4358
4359 BarrierSet::barrier_set()->on_thread_attach(p);
4360
4361 p->set_next(_thread_list);
4362 _thread_list = p;
4363
4364 // Once a JavaThread is added to the Threads list, smr_delete() has
4365 // to be used to delete it. Otherwise we can just delete it directly.
4366 p->set_on_thread_list();
4367
4368 _number_of_threads++;
4369 oop threadObj = p->threadObj();
4370 bool daemon = true;
4371 // Bootstrapping problem: threadObj can be null for initial
4372 // JavaThread (or for threads attached via JNI)
4373 if ((!force_daemon) && !is_daemon((threadObj))) {
4374 _number_of_non_daemon_threads++;
4375 daemon = false;
4376 }
4377
4378 ThreadService::add_thread(p, daemon);
4379
4380 // Maintain fast thread list
4381 ThreadsSMRSupport::add_thread(p);
4382
4383 // Possible GC point.
4384 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4385 }
4386
4387 void Threads::remove(JavaThread* p) {
4388
4389 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4390 ObjectSynchronizer::omFlush(p);
4391
4392 // Extra scope needed for Thread_lock, so we can check
4393 // that we do not remove thread without safepoint code notice
4394 { MutexLocker ml(Threads_lock);
4395
4396 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4397
4398 // Maintain fast thread list
4399 ThreadsSMRSupport::remove_thread(p);
4400
4401 JavaThread* current = _thread_list;
4402 JavaThread* prev = NULL;
4403
4404 while (current != p) {
4405 prev = current;
4406 current = current->next();
4407 }
4408
4409 if (prev) {
4410 prev->set_next(current->next());
4411 } else {
4412 _thread_list = p->next();
4413 }
4414
4415 _number_of_threads--;
4416 oop threadObj = p->threadObj();
4417 bool daemon = true;
4418 if (!is_daemon(threadObj)) {
4419 _number_of_non_daemon_threads--;
4420 daemon = false;
4421
4422 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4423 // on destroy_vm will wake up.
4424 if (number_of_non_daemon_threads() == 1) {
4425 Threads_lock->notify_all();
4426 }
4427 }
4428 ThreadService::remove_thread(p, daemon);
4429
4430 // Make sure that safepoint code disregard this thread. This is needed since
4431 // the thread might mess around with locks after this point. This can cause it
4432 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4433 // of this thread since it is removed from the queue.
4434 p->set_terminated_value();
4435 } // unlock Threads_lock
4436
4437 // Since Events::log uses a lock, we grab it outside the Threads_lock
4438 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4439 }
4440
4441 // Operations on the Threads list for GC. These are not explicitly locked,
4442 // but the garbage collector must provide a safe context for them to run.
4443 // In particular, these things should never be called when the Threads_lock
4444 // is held by some other thread. (Note: the Safepoint abstraction also
4445 // uses the Threads_lock to guarantee this property. It also makes sure that
4446 // all threads gets blocked when exiting or starting).
4447
4448 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4449 ALL_JAVA_THREADS(p) {
4450 p->oops_do(f, cf);
4451 }
4452 VMThread::vm_thread()->oops_do(f, cf);
4453 }
4454
4455 void Threads::change_thread_claim_parity() {
4456 // Set the new claim parity.
4457 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4458 "Not in range.");
4459 _thread_claim_parity++;
4460 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4461 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4462 "Not in range.");
4463 }
4464
4465 #ifdef ASSERT
4466 void Threads::assert_all_threads_claimed() {
4467 ALL_JAVA_THREADS(p) {
4468 const int thread_parity = p->oops_do_parity();
4469 assert((thread_parity == _thread_claim_parity),
4470 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4471 }
4472 VMThread* vmt = VMThread::vm_thread();
4473 const int thread_parity = vmt->oops_do_parity();
4474 assert((thread_parity == _thread_claim_parity),
4475 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4476 }
4477 #endif // ASSERT
4478
4479 class ParallelOopsDoThreadClosure : public ThreadClosure {
4480 private:
4481 OopClosure* _f;
4482 CodeBlobClosure* _cf;
4483 public:
4484 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4485 void do_thread(Thread* t) {
4486 t->oops_do(_f, _cf);
4487 }
4488 };
4489
4490 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4491 ParallelOopsDoThreadClosure tc(f, cf);
4492 possibly_parallel_threads_do(is_par, &tc);
4493 }
4494
4495 void Threads::nmethods_do(CodeBlobClosure* cf) {
4496 ALL_JAVA_THREADS(p) {
4497 // This is used by the code cache sweeper to mark nmethods that are active
4498 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4499 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4500 if(!p->is_Code_cache_sweeper_thread()) {
4501 p->nmethods_do(cf);
4502 }
4503 }
4504 }
4505
4506 void Threads::metadata_do(void f(Metadata*)) {
4507 ALL_JAVA_THREADS(p) {
4508 p->metadata_do(f);
4509 }
4510 }
4511
4512 class ThreadHandlesClosure : public ThreadClosure {
4513 void (*_f)(Metadata*);
4514 public:
4515 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4516 virtual void do_thread(Thread* thread) {
4517 thread->metadata_handles_do(_f);
4518 }
4519 };
4520
4521 void Threads::metadata_handles_do(void f(Metadata*)) {
4522 // Only walk the Handles in Thread.
4523 ThreadHandlesClosure handles_closure(f);
4524 threads_do(&handles_closure);
4525 }
4526
4527 void Threads::deoptimized_wrt_marked_nmethods() {
4528 ALL_JAVA_THREADS(p) {
4529 p->deoptimized_wrt_marked_nmethods();
4530 }
4531 }
4532
4533
4534 // Get count Java threads that are waiting to enter the specified monitor.
4535 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4536 int count,
4537 address monitor) {
4538 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4539
4540 int i = 0;
4541 DO_JAVA_THREADS(t_list, p) {
4542 if (!p->can_call_java()) continue;
4543
4544 address pending = (address)p->current_pending_monitor();
4545 if (pending == monitor) { // found a match
4546 if (i < count) result->append(p); // save the first count matches
4547 i++;
4548 }
4549 }
4550
4551 return result;
4552 }
4553
4554
4555 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4556 address owner) {
4557 // NULL owner means not locked so we can skip the search
4558 if (owner == NULL) return NULL;
4559
4560 DO_JAVA_THREADS(t_list, p) {
4561 // first, see if owner is the address of a Java thread
4562 if (owner == (address)p) return p;
4563 }
4564
4565 // Cannot assert on lack of success here since this function may be
4566 // used by code that is trying to report useful problem information
4567 // like deadlock detection.
4568 if (UseHeavyMonitors) return NULL;
4569
4570 // If we didn't find a matching Java thread and we didn't force use of
4571 // heavyweight monitors, then the owner is the stack address of the
4572 // Lock Word in the owning Java thread's stack.
4573 //
4574 JavaThread* the_owner = NULL;
4575 DO_JAVA_THREADS(t_list, q) {
4576 if (q->is_lock_owned(owner)) {
4577 the_owner = q;
4578 break;
4579 }
4580 }
4581
4582 // cannot assert on lack of success here; see above comment
4583 return the_owner;
4584 }
4585
4586 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4587 void Threads::print_on(outputStream* st, bool print_stacks,
4588 bool internal_format, bool print_concurrent_locks,
4589 bool print_extended_info) {
4590 char buf[32];
4591 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4592
4593 st->print_cr("Full thread dump %s (%s %s):",
4594 VM_Version::vm_name(),
4595 VM_Version::vm_release(),
4596 VM_Version::vm_info_string());
4597 st->cr();
4598
4599 #if INCLUDE_SERVICES
4600 // Dump concurrent locks
4601 ConcurrentLocksDump concurrent_locks;
4602 if (print_concurrent_locks) {
4603 concurrent_locks.dump_at_safepoint();
4604 }
4605 #endif // INCLUDE_SERVICES
4606
4607 ThreadsSMRSupport::print_info_on(st);
4608 st->cr();
4609
4610 ALL_JAVA_THREADS(p) {
4611 ResourceMark rm;
4612 p->print_on(st, print_extended_info);
4613 if (print_stacks) {
4614 if (internal_format) {
4615 p->trace_stack();
4616 } else {
4617 p->print_stack_on(st);
4618 }
4619 }
4620 st->cr();
4621 #if INCLUDE_SERVICES
4622 if (print_concurrent_locks) {
4623 concurrent_locks.print_locks_on(p, st);
4624 }
4625 #endif // INCLUDE_SERVICES
4626 }
4627
4628 VMThread::vm_thread()->print_on(st);
4629 st->cr();
4630 Universe::heap()->print_gc_threads_on(st);
4631 WatcherThread* wt = WatcherThread::watcher_thread();
4632 if (wt != NULL) {
4633 wt->print_on(st);
4634 st->cr();
4635 }
4636
4637 st->flush();
4638 }
4639
4640 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4641 int buflen, bool* found_current) {
4642 if (this_thread != NULL) {
4643 bool is_current = (current == this_thread);
4644 *found_current = *found_current || is_current;
4645 st->print("%s", is_current ? "=>" : " ");
4646
4647 st->print(PTR_FORMAT, p2i(this_thread));
4648 st->print(" ");
4649 this_thread->print_on_error(st, buf, buflen);
4650 st->cr();
4651 }
4652 }
4653
4654 class PrintOnErrorClosure : public ThreadClosure {
4655 outputStream* _st;
4656 Thread* _current;
4657 char* _buf;
4658 int _buflen;
4659 bool* _found_current;
4660 public:
4661 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4662 int buflen, bool* found_current) :
4663 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4664
4665 virtual void do_thread(Thread* thread) {
4666 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4667 }
4668 };
4669
4670 // Threads::print_on_error() is called by fatal error handler. It's possible
4671 // that VM is not at safepoint and/or current thread is inside signal handler.
4672 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4673 // memory (even in resource area), it might deadlock the error handler.
4674 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4675 int buflen) {
4676 ThreadsSMRSupport::print_info_on(st);
4677 st->cr();
4678
4679 bool found_current = false;
4680 st->print_cr("Java Threads: ( => current thread )");
4681 ALL_JAVA_THREADS(thread) {
4682 print_on_error(thread, st, current, buf, buflen, &found_current);
4683 }
4684 st->cr();
4685
4686 st->print_cr("Other Threads:");
4687 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4688 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4689
4690 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4691 Universe::heap()->gc_threads_do(&print_closure);
4692
4693 if (!found_current) {
4694 st->cr();
4695 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4696 current->print_on_error(st, buf, buflen);
4697 st->cr();
4698 }
4699 st->cr();
4700
4701 st->print_cr("Threads with active compile tasks:");
4702 print_threads_compiling(st, buf, buflen);
4703 }
4704
4705 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4706 ALL_JAVA_THREADS(thread) {
4707 if (thread->is_Compiler_thread()) {
4708 CompilerThread* ct = (CompilerThread*) thread;
4709
4710 // Keep task in local variable for NULL check.
4711 // ct->_task might be set to NULL by concurring compiler thread
4712 // because it completed the compilation. The task is never freed,
4713 // though, just returned to a free list.
4714 CompileTask* task = ct->task();
4715 if (task != NULL) {
4716 thread->print_name_on_error(st, buf, buflen);
4717 task->print(st, NULL, true, true);
4718 }
4719 }
4720 }
4721 }
4722
4723
4724 // Internal SpinLock and Mutex
4725 // Based on ParkEvent
4726
4727 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4728 //
4729 // We employ SpinLocks _only for low-contention, fixed-length
4730 // short-duration critical sections where we're concerned
4731 // about native mutex_t or HotSpot Mutex:: latency.
4732 // The mux construct provides a spin-then-block mutual exclusion
4733 // mechanism.
4734 //
4735 // Testing has shown that contention on the ListLock guarding gFreeList
4736 // is common. If we implement ListLock as a simple SpinLock it's common
4737 // for the JVM to devolve to yielding with little progress. This is true
4738 // despite the fact that the critical sections protected by ListLock are
4739 // extremely short.
4740 //
4741 // TODO-FIXME: ListLock should be of type SpinLock.
4742 // We should make this a 1st-class type, integrated into the lock
4743 // hierarchy as leaf-locks. Critically, the SpinLock structure
4744 // should have sufficient padding to avoid false-sharing and excessive
4745 // cache-coherency traffic.
4746
4747
4748 typedef volatile int SpinLockT;
4749
4750 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4751 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4752 return; // normal fast-path return
4753 }
4754
4755 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4756 int ctr = 0;
4757 int Yields = 0;
4758 for (;;) {
4759 while (*adr != 0) {
4760 ++ctr;
4761 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4762 if (Yields > 5) {
4763 os::naked_short_sleep(1);
4764 } else {
4765 os::naked_yield();
4766 ++Yields;
4767 }
4768 } else {
4769 SpinPause();
4770 }
4771 }
4772 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4773 }
4774 }
4775
4776 void Thread::SpinRelease(volatile int * adr) {
4777 assert(*adr != 0, "invariant");
4778 OrderAccess::fence(); // guarantee at least release consistency.
4779 // Roach-motel semantics.
4780 // It's safe if subsequent LDs and STs float "up" into the critical section,
4781 // but prior LDs and STs within the critical section can't be allowed
4782 // to reorder or float past the ST that releases the lock.
4783 // Loads and stores in the critical section - which appear in program
4784 // order before the store that releases the lock - must also appear
4785 // before the store that releases the lock in memory visibility order.
4786 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4787 // the ST of 0 into the lock-word which releases the lock, so fence
4788 // more than covers this on all platforms.
4789 *adr = 0;
4790 }
4791
4792 // muxAcquire and muxRelease:
4793 //
4794 // * muxAcquire and muxRelease support a single-word lock-word construct.
4795 // The LSB of the word is set IFF the lock is held.
4796 // The remainder of the word points to the head of a singly-linked list
4797 // of threads blocked on the lock.
4798 //
4799 // * The current implementation of muxAcquire-muxRelease uses its own
4800 // dedicated Thread._MuxEvent instance. If we're interested in
4801 // minimizing the peak number of extant ParkEvent instances then
4802 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4803 // as certain invariants were satisfied. Specifically, care would need
4804 // to be taken with regards to consuming unpark() "permits".
4805 // A safe rule of thumb is that a thread would never call muxAcquire()
4806 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4807 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4808 // consume an unpark() permit intended for monitorenter, for instance.
4809 // One way around this would be to widen the restricted-range semaphore
4810 // implemented in park(). Another alternative would be to provide
4811 // multiple instances of the PlatformEvent() for each thread. One
4812 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4813 //
4814 // * Usage:
4815 // -- Only as leaf locks
4816 // -- for short-term locking only as muxAcquire does not perform
4817 // thread state transitions.
4818 //
4819 // Alternatives:
4820 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4821 // but with parking or spin-then-park instead of pure spinning.
4822 // * Use Taura-Oyama-Yonenzawa locks.
4823 // * It's possible to construct a 1-0 lock if we encode the lockword as
4824 // (List,LockByte). Acquire will CAS the full lockword while Release
4825 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4826 // acquiring threads use timers (ParkTimed) to detect and recover from
4827 // the stranding window. Thread/Node structures must be aligned on 256-byte
4828 // boundaries by using placement-new.
4829 // * Augment MCS with advisory back-link fields maintained with CAS().
4830 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4831 // The validity of the backlinks must be ratified before we trust the value.
4832 // If the backlinks are invalid the exiting thread must back-track through the
4833 // the forward links, which are always trustworthy.
4834 // * Add a successor indication. The LockWord is currently encoded as
4835 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4836 // to provide the usual futile-wakeup optimization.
4837 // See RTStt for details.
4838 //
4839
4840
4841 const intptr_t LOCKBIT = 1;
4842
4843 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4844 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4845 if (w == 0) return;
4846 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4847 return;
4848 }
4849
4850 ParkEvent * const Self = Thread::current()->_MuxEvent;
4851 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4852 for (;;) {
4853 int its = (os::is_MP() ? 100 : 0) + 1;
4854
4855 // Optional spin phase: spin-then-park strategy
4856 while (--its >= 0) {
4857 w = *Lock;
4858 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4859 return;
4860 }
4861 }
4862
4863 Self->reset();
4864 Self->OnList = intptr_t(Lock);
4865 // The following fence() isn't _strictly necessary as the subsequent
4866 // CAS() both serializes execution and ratifies the fetched *Lock value.
4867 OrderAccess::fence();
4868 for (;;) {
4869 w = *Lock;
4870 if ((w & LOCKBIT) == 0) {
4871 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4872 Self->OnList = 0; // hygiene - allows stronger asserts
4873 return;
4874 }
4875 continue; // Interference -- *Lock changed -- Just retry
4876 }
4877 assert(w & LOCKBIT, "invariant");
4878 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4879 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4880 }
4881
4882 while (Self->OnList != 0) {
4883 Self->park();
4884 }
4885 }
4886 }
4887
4888 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4889 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4890 if (w == 0) return;
4891 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4892 return;
4893 }
4894
4895 ParkEvent * ReleaseAfter = NULL;
4896 if (ev == NULL) {
4897 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4898 }
4899 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4900 for (;;) {
4901 guarantee(ev->OnList == 0, "invariant");
4902 int its = (os::is_MP() ? 100 : 0) + 1;
4903
4904 // Optional spin phase: spin-then-park strategy
4905 while (--its >= 0) {
4906 w = *Lock;
4907 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4908 if (ReleaseAfter != NULL) {
4909 ParkEvent::Release(ReleaseAfter);
4910 }
4911 return;
4912 }
4913 }
4914
4915 ev->reset();
4916 ev->OnList = intptr_t(Lock);
4917 // The following fence() isn't _strictly necessary as the subsequent
4918 // CAS() both serializes execution and ratifies the fetched *Lock value.
4919 OrderAccess::fence();
4920 for (;;) {
4921 w = *Lock;
4922 if ((w & LOCKBIT) == 0) {
4923 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4924 ev->OnList = 0;
4925 // We call ::Release while holding the outer lock, thus
4926 // artificially lengthening the critical section.
4927 // Consider deferring the ::Release() until the subsequent unlock(),
4928 // after we've dropped the outer lock.
4929 if (ReleaseAfter != NULL) {
4930 ParkEvent::Release(ReleaseAfter);
4931 }
4932 return;
4933 }
4934 continue; // Interference -- *Lock changed -- Just retry
4935 }
4936 assert(w & LOCKBIT, "invariant");
4937 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4938 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4939 }
4940
4941 while (ev->OnList != 0) {
4942 ev->park();
4943 }
4944 }
4945 }
4946
4947 // Release() must extract a successor from the list and then wake that thread.
4948 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4949 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4950 // Release() would :
4951 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4952 // (B) Extract a successor from the private list "in-hand"
4953 // (C) attempt to CAS() the residual back into *Lock over null.
4954 // If there were any newly arrived threads and the CAS() would fail.
4955 // In that case Release() would detach the RATs, re-merge the list in-hand
4956 // with the RATs and repeat as needed. Alternately, Release() might
4957 // detach and extract a successor, but then pass the residual list to the wakee.
4958 // The wakee would be responsible for reattaching and remerging before it
4959 // competed for the lock.
4960 //
4961 // Both "pop" and DMR are immune from ABA corruption -- there can be
4962 // multiple concurrent pushers, but only one popper or detacher.
4963 // This implementation pops from the head of the list. This is unfair,
4964 // but tends to provide excellent throughput as hot threads remain hot.
4965 // (We wake recently run threads first).
4966 //
4967 // All paths through muxRelease() will execute a CAS.
4968 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4969 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4970 // executed within the critical section are complete and globally visible before the
4971 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4972 void Thread::muxRelease(volatile intptr_t * Lock) {
4973 for (;;) {
4974 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4975 assert(w & LOCKBIT, "invariant");
4976 if (w == LOCKBIT) return;
4977 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4978 assert(List != NULL, "invariant");
4979 assert(List->OnList == intptr_t(Lock), "invariant");
4980 ParkEvent * const nxt = List->ListNext;
4981 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4982
4983 // The following CAS() releases the lock and pops the head element.
4984 // The CAS() also ratifies the previously fetched lock-word value.
4985 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4986 continue;
4987 }
4988 List->OnList = 0;
4989 OrderAccess::fence();
4990 List->unpark();
4991 return;
4992 }
4993 }
4994
4995
4996 void Threads::verify() {
4997 ALL_JAVA_THREADS(p) {
4998 p->verify();
4999 }
5000 VMThread* thread = VMThread::vm_thread();
5001 if (thread != NULL) thread->verify();
5002 }