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 "jvmtifiles/jvmtiEnv.hpp"
45 #include "logging/log.hpp"
46 #include "logging/logConfiguration.hpp"
47 #include "logging/logStream.hpp"
48 #include "memory/allocation.inline.hpp"
49 #include "memory/metaspaceShared.hpp"
50 #include "memory/oopFactory.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "memory/universe.hpp"
53 #include "oops/access.inline.hpp"
54 #include "oops/instanceKlass.hpp"
55 #include "oops/objArrayOop.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/symbol.hpp"
58 #include "oops/typeArrayOop.inline.hpp"
59 #include "oops/verifyOopClosure.hpp"
60 #include "prims/jvm_misc.hpp"
61 #include "prims/jvmtiExport.hpp"
62 #include "prims/jvmtiThreadState.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/fieldDescriptor.inline.hpp"
67 #include "runtime/flags/jvmFlagConstraintList.hpp"
68 #include "runtime/flags/jvmFlagRangeList.hpp"
69 #include "runtime/flags/jvmFlagWriteableList.hpp"
70 #include "runtime/deoptimization.hpp"
71 #include "runtime/frame.inline.hpp"
72 #include "runtime/handshake.hpp"
73 #include "runtime/init.hpp"
74 #include "runtime/interfaceSupport.inline.hpp"
75 #include "runtime/java.hpp"
76 #include "runtime/javaCalls.hpp"
77 #include "runtime/jniHandles.inline.hpp"
78 #include "runtime/jniPeriodicChecker.hpp"
79 #include "runtime/memprofiler.hpp"
80 #include "runtime/mutexLocker.hpp"
81 #include "runtime/objectMonitor.hpp"
82 #include "runtime/orderAccess.hpp"
83 #include "runtime/osThread.hpp"
84 #include "runtime/prefetch.inline.hpp"
85 #include "runtime/safepoint.hpp"
86 #include "runtime/safepointMechanism.inline.hpp"
87 #include "runtime/safepointVerifiers.hpp"
88 #include "runtime/sharedRuntime.hpp"
89 #include "runtime/statSampler.hpp"
90 #include "runtime/stubRoutines.hpp"
91 #include "runtime/sweeper.hpp"
92 #include "runtime/task.hpp"
93 #include "runtime/thread.inline.hpp"
94 #include "runtime/threadCritical.hpp"
95 #include "runtime/threadSMR.inline.hpp"
96 #include "runtime/threadStatisticalInfo.hpp"
97 #include "runtime/timer.hpp"
98 #include "runtime/timerTrace.hpp"
99 #include "runtime/vframe.inline.hpp"
100 #include "runtime/vframeArray.hpp"
101 #include "runtime/vframe_hp.hpp"
102 #include "runtime/vmThread.hpp"
103 #include "runtime/vm_operations.hpp"
104 #include "runtime/vm_version.hpp"
105 #include "services/attachListener.hpp"
106 #include "services/management.hpp"
107 #include "services/memTracker.hpp"
108 #include "services/threadService.hpp"
109 #include "utilities/align.hpp"
110 #include "utilities/copy.hpp"
111 #include "utilities/defaultStream.hpp"
112 #include "utilities/dtrace.hpp"
113 #include "utilities/events.hpp"
114 #include "utilities/macros.hpp"
115 #include "utilities/preserveException.hpp"
116 #include "utilities/singleWriterSynchronizer.hpp"
117 #include "utilities/vmError.hpp"
118 #if INCLUDE_JVMCI
119 #include "jvmci/jvmciCompiler.hpp"
120 #include "jvmci/jvmciRuntime.hpp"
121 #include "logging/logHandle.hpp"
122 #endif
123 #ifdef COMPILER1
124 #include "c1/c1_Compiler.hpp"
125 #endif
126 #ifdef COMPILER2
127 #include "opto/c2compiler.hpp"
128 #include "opto/idealGraphPrinter.hpp"
129 #endif
130 #if INCLUDE_RTM_OPT
131 #include "runtime/rtmLocking.hpp"
132 #endif
133 #if INCLUDE_JFR
134 #include "jfr/jfr.hpp"
135 #endif
136
137 // Initialization after module runtime initialization
138 void universe_post_module_init(); // must happen after call_initPhase2
139
140 #ifdef DTRACE_ENABLED
141
142 // Only bother with this argument setup if dtrace is available
143
144 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
145 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
146
147 #define DTRACE_THREAD_PROBE(probe, javathread) \
148 { \
149 ResourceMark rm(this); \
150 int len = 0; \
151 const char* name = (javathread)->get_thread_name(); \
152 len = strlen(name); \
153 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
154 (char *) name, len, \
155 java_lang_Thread::thread_id((javathread)->threadObj()), \
156 (uintptr_t) (javathread)->osthread()->thread_id(), \
157 java_lang_Thread::is_daemon((javathread)->threadObj())); \
158 }
159
160 #else // ndef DTRACE_ENABLED
161
162 #define DTRACE_THREAD_PROBE(probe, javathread)
163
164 #endif // ndef DTRACE_ENABLED
165
166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
167 // Current thread is maintained as a thread-local variable
168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
169 #endif
170
171 // ======= Thread ========
172 // Support for forcing alignment of thread objects for biased locking
173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
174 if (UseBiasedLocking) {
175 const int alignment = markOopDesc::biased_lock_alignment;
176 size_t aligned_size = size + (alignment - sizeof(intptr_t));
177 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
178 : AllocateHeap(aligned_size, flags, CURRENT_PC,
179 AllocFailStrategy::RETURN_NULL);
180 void* aligned_addr = align_up(real_malloc_addr, alignment);
181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
183 "JavaThread alignment code overflowed allocated storage");
184 if (aligned_addr != real_malloc_addr) {
185 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
186 p2i(real_malloc_addr),
187 p2i(aligned_addr));
188 }
189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
190 return aligned_addr;
191 } else {
192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
193 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
194 }
195 }
196
197 void Thread::operator delete(void* p) {
198 if (UseBiasedLocking) {
199 FreeHeap(((Thread*) p)->_real_malloc_address);
200 } else {
201 FreeHeap(p);
202 }
203 }
204
205 void JavaThread::smr_delete() {
206 if (_on_thread_list) {
207 ThreadsSMRSupport::smr_delete(this);
208 } else {
209 delete this;
210 }
211 }
212
213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
214 // JavaThread
215
216
217 Thread::Thread() {
218 // stack and get_thread
219 set_stack_base(NULL);
220 set_stack_size(0);
221 set_self_raw_id(0);
222 set_lgrp_id(-1);
223 DEBUG_ONLY(clear_suspendible_thread();)
224
225 // allocated data structures
226 set_osthread(NULL);
227 set_resource_area(new (mtThread)ResourceArea());
228 DEBUG_ONLY(_current_resource_mark = NULL;)
229 set_handle_area(new (mtThread) HandleArea(NULL));
230 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
231 set_active_handles(NULL);
232 set_free_handle_block(NULL);
233 set_last_handle_mark(NULL);
234
235 // This initial value ==> never claimed.
236 _oops_do_parity = 0;
237 _threads_hazard_ptr = NULL;
238 _threads_list_ptr = NULL;
239 _nested_threads_hazard_ptr_cnt = 0;
240 _rcu_counter = 0;
241
242 // the handle mark links itself to last_handle_mark
243 new HandleMark(this);
244
245 // plain initialization
246 debug_only(_owned_locks = NULL;)
247 debug_only(_allow_allocation_count = 0;)
248 NOT_PRODUCT(_allow_safepoint_count = 0;)
249 NOT_PRODUCT(_skip_gcalot = false;)
250 _jvmti_env_iteration_count = 0;
251 set_allocated_bytes(0);
252 _vm_operation_started_count = 0;
253 _vm_operation_completed_count = 0;
254 _current_pending_monitor = NULL;
255 _current_pending_monitor_is_from_java = true;
256 _current_waiting_monitor = NULL;
257 _num_nested_signal = 0;
258 omFreeList = NULL;
259 omFreeCount = 0;
260 omFreeProvision = 32;
261 omInUseList = NULL;
262 omInUseCount = 0;
263
264 #ifdef ASSERT
265 _visited_for_critical_count = false;
266 #endif
267
268 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
269 Monitor::_safepoint_check_sometimes);
270 _suspend_flags = 0;
271
272 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
273 _hashStateX = os::random();
274 _hashStateY = 842502087;
275 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
276 _hashStateW = 273326509;
277
278 _OnTrap = 0;
279 _Stalled = 0;
280 _TypeTag = 0x2BAD;
281
282 // Many of the following fields are effectively final - immutable
283 // Note that nascent threads can't use the Native Monitor-Mutex
284 // construct until the _MutexEvent is initialized ...
285 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
286 // we might instead use a stack of ParkEvents that we could provision on-demand.
287 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
288 // and ::Release()
289 _ParkEvent = ParkEvent::Allocate(this);
290 _SleepEvent = ParkEvent::Allocate(this);
291 _MutexEvent = ParkEvent::Allocate(this);
292 _MuxEvent = ParkEvent::Allocate(this);
293
294 #ifdef CHECK_UNHANDLED_OOPS
295 if (CheckUnhandledOops) {
296 _unhandled_oops = new UnhandledOops(this);
297 }
298 #endif // CHECK_UNHANDLED_OOPS
299 #ifdef ASSERT
300 if (UseBiasedLocking) {
301 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
302 assert(this == _real_malloc_address ||
303 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
304 "bug in forced alignment of thread objects");
305 }
306 #endif // ASSERT
307
308 // Notify the barrier set that a thread is being created. Note that some
309 // threads are created before a barrier set is available. The call to
310 // BarrierSet::on_thread_create() for these threads is therefore deferred
311 // to BarrierSet::set_barrier_set().
312 BarrierSet* const barrier_set = BarrierSet::barrier_set();
313 if (barrier_set != NULL) {
314 barrier_set->on_thread_create(this);
315 } else {
316 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();)
317 }
318 }
319
320 void Thread::initialize_thread_current() {
321 #ifndef USE_LIBRARY_BASED_TLS_ONLY
322 assert(_thr_current == NULL, "Thread::current already initialized");
323 _thr_current = this;
324 #endif
325 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
326 ThreadLocalStorage::set_thread(this);
327 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
328 }
329
330 void Thread::clear_thread_current() {
331 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
332 #ifndef USE_LIBRARY_BASED_TLS_ONLY
333 _thr_current = NULL;
334 #endif
335 ThreadLocalStorage::set_thread(NULL);
336 }
337
338 void Thread::record_stack_base_and_size() {
339 // Note: at this point, Thread object is not yet initialized. Do not rely on
340 // any members being initialized. Do not rely on Thread::current() being set.
341 // If possible, refrain from doing anything which may crash or assert since
342 // quite probably those crash dumps will be useless.
343 set_stack_base(os::current_stack_base());
344 set_stack_size(os::current_stack_size());
345
346 #ifdef SOLARIS
347 if (os::is_primordial_thread()) {
348 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
349 }
350 #endif
351
352 // Set stack limits after thread is initialized.
353 if (is_Java_thread()) {
354 ((JavaThread*) this)->set_stack_overflow_limit();
355 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
356 }
357 }
358
359 #if INCLUDE_NMT
360 void Thread::register_thread_stack_with_NMT() {
361 MemTracker::record_thread_stack(stack_end(), stack_size());
362 }
363 #endif // INCLUDE_NMT
364
365 void Thread::call_run() {
366 // At this point, Thread object should be fully initialized and
367 // Thread::current() should be set.
368
369 register_thread_stack_with_NMT();
370
371 JFR_ONLY(Jfr::on_thread_start(this);)
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 // Notify the barrier set that a thread is being destroyed. Note that a barrier
398 // set might not be available if we encountered errors during bootstrapping.
399 BarrierSet* const barrier_set = BarrierSet::barrier_set();
400 if (barrier_set != NULL) {
401 barrier_set->on_thread_destroy(this);
402 }
403
404 // stack_base can be NULL if the thread is never started or exited before
405 // record_stack_base_and_size called. Although, we would like to ensure
406 // that all started threads do call record_stack_base_and_size(), there is
407 // not proper way to enforce that.
408 #if INCLUDE_NMT
409 if (_stack_base != NULL) {
410 MemTracker::release_thread_stack(stack_end(), stack_size());
411 #ifdef ASSERT
412 set_stack_base(NULL);
413 #endif
414 }
415 #endif // INCLUDE_NMT
416
417 // deallocate data structures
418 delete resource_area();
419 // since the handle marks are using the handle area, we have to deallocated the root
420 // handle mark before deallocating the thread's handle area,
421 assert(last_handle_mark() != NULL, "check we have an element");
422 delete last_handle_mark();
423 assert(last_handle_mark() == NULL, "check we have reached the end");
424
425 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
426 // We NULL out the fields for good hygiene.
427 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
428 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
429 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
430 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
431
432 delete handle_area();
433 delete metadata_handles();
434
435 // SR_handler uses this as a termination indicator -
436 // needs to happen before os::free_thread()
437 delete _SR_lock;
438 _SR_lock = NULL;
439
440 // osthread() can be NULL, if creation of thread failed.
441 if (osthread() != NULL) os::free_thread(osthread());
442
443 // clear Thread::current if thread is deleting itself.
444 // Needed to ensure JNI correctly detects non-attached threads.
445 if (this == Thread::current()) {
446 Thread::clear_thread_current();
447 }
448
449 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
450 }
451
452 #ifdef ASSERT
453 // A JavaThread is considered "dangling" if it is not the current
454 // thread, has been added the Threads list, the system is not at a
455 // safepoint and the Thread is not "protected".
456 //
457 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
458 assert(!thread->is_Java_thread() || Thread::current() == thread ||
459 !((JavaThread *) thread)->on_thread_list() ||
460 SafepointSynchronize::is_at_safepoint() ||
461 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
462 "possibility of dangling Thread pointer");
463 }
464 #endif
465
466 ThreadPriority Thread::get_priority(const Thread* const thread) {
467 ThreadPriority priority;
468 // Can return an error!
469 (void)os::get_priority(thread, priority);
470 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
471 return priority;
472 }
473
474 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
475 debug_only(check_for_dangling_thread_pointer(thread);)
476 // Can return an error!
477 (void)os::set_priority(thread, priority);
478 }
479
480
481 void Thread::start(Thread* thread) {
482 // Start is different from resume in that its safety is guaranteed by context or
483 // being called from a Java method synchronized on the Thread object.
484 if (!DisableStartThread) {
485 if (thread->is_Java_thread()) {
486 // Initialize the thread state to RUNNABLE before starting this thread.
487 // Can not set it after the thread started because we do not know the
488 // exact thread state at that time. It could be in MONITOR_WAIT or
489 // in SLEEPING or some other state.
490 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
491 java_lang_Thread::RUNNABLE);
492 }
493 os::start_thread(thread);
494 }
495 }
496
497 // Enqueue a VM_Operation to do the job for us - sometime later
498 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
499 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
500 VMThread::execute(vm_stop);
501 }
502
503
504 // Check if an external suspend request has completed (or has been
505 // cancelled). Returns true if the thread is externally suspended and
506 // false otherwise.
507 //
508 // The bits parameter returns information about the code path through
509 // the routine. Useful for debugging:
510 //
511 // set in is_ext_suspend_completed():
512 // 0x00000001 - routine was entered
513 // 0x00000010 - routine return false at end
514 // 0x00000100 - thread exited (return false)
515 // 0x00000200 - suspend request cancelled (return false)
516 // 0x00000400 - thread suspended (return true)
517 // 0x00001000 - thread is in a suspend equivalent state (return true)
518 // 0x00002000 - thread is native and walkable (return true)
519 // 0x00004000 - thread is native_trans and walkable (needed retry)
520 //
521 // set in wait_for_ext_suspend_completion():
522 // 0x00010000 - routine was entered
523 // 0x00020000 - suspend request cancelled before loop (return false)
524 // 0x00040000 - thread suspended before loop (return true)
525 // 0x00080000 - suspend request cancelled in loop (return false)
526 // 0x00100000 - thread suspended in loop (return true)
527 // 0x00200000 - suspend not completed during retry loop (return false)
528
529 // Helper class for tracing suspend wait debug bits.
530 //
531 // 0x00000100 indicates that the target thread exited before it could
532 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
533 // 0x00080000 each indicate a cancelled suspend request so they don't
534 // count as wait failures either.
535 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
536
537 class TraceSuspendDebugBits : public StackObj {
538 private:
539 JavaThread * jt;
540 bool is_wait;
541 bool called_by_wait; // meaningful when !is_wait
542 uint32_t * bits;
543
544 public:
545 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
546 uint32_t *_bits) {
547 jt = _jt;
548 is_wait = _is_wait;
549 called_by_wait = _called_by_wait;
550 bits = _bits;
551 }
552
553 ~TraceSuspendDebugBits() {
554 if (!is_wait) {
555 #if 1
556 // By default, don't trace bits for is_ext_suspend_completed() calls.
557 // That trace is very chatty.
558 return;
559 #else
560 if (!called_by_wait) {
561 // If tracing for is_ext_suspend_completed() is enabled, then only
562 // trace calls to it from wait_for_ext_suspend_completion()
563 return;
564 }
565 #endif
566 }
567
568 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
569 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
570 MutexLocker ml(Threads_lock); // needed for get_thread_name()
571 ResourceMark rm;
572
573 tty->print_cr(
574 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
575 jt->get_thread_name(), *bits);
576
577 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
578 }
579 }
580 }
581 };
582 #undef DEBUG_FALSE_BITS
583
584
585 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
586 uint32_t *bits) {
587 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
588
589 bool did_trans_retry = false; // only do thread_in_native_trans retry once
590 bool do_trans_retry; // flag to force the retry
591
592 *bits |= 0x00000001;
593
594 do {
595 do_trans_retry = false;
596
597 if (is_exiting()) {
598 // Thread is in the process of exiting. This is always checked
599 // first to reduce the risk of dereferencing a freed JavaThread.
600 *bits |= 0x00000100;
601 return false;
602 }
603
604 if (!is_external_suspend()) {
605 // Suspend request is cancelled. This is always checked before
606 // is_ext_suspended() to reduce the risk of a rogue resume
607 // confusing the thread that made the suspend request.
608 *bits |= 0x00000200;
609 return false;
610 }
611
612 if (is_ext_suspended()) {
613 // thread is suspended
614 *bits |= 0x00000400;
615 return true;
616 }
617
618 // Now that we no longer do hard suspends of threads running
619 // native code, the target thread can be changing thread state
620 // while we are in this routine:
621 //
622 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
623 //
624 // We save a copy of the thread state as observed at this moment
625 // and make our decision about suspend completeness based on the
626 // copy. This closes the race where the thread state is seen as
627 // _thread_in_native_trans in the if-thread_blocked check, but is
628 // seen as _thread_blocked in if-thread_in_native_trans check.
629 JavaThreadState save_state = thread_state();
630
631 if (save_state == _thread_blocked && is_suspend_equivalent()) {
632 // If the thread's state is _thread_blocked and this blocking
633 // condition is known to be equivalent to a suspend, then we can
634 // consider the thread to be externally suspended. This means that
635 // the code that sets _thread_blocked has been modified to do
636 // self-suspension if the blocking condition releases. We also
637 // used to check for CONDVAR_WAIT here, but that is now covered by
638 // the _thread_blocked with self-suspension check.
639 //
640 // Return true since we wouldn't be here unless there was still an
641 // external suspend request.
642 *bits |= 0x00001000;
643 return true;
644 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
645 // Threads running native code will self-suspend on native==>VM/Java
646 // transitions. If its stack is walkable (should always be the case
647 // unless this function is called before the actual java_suspend()
648 // call), then the wait is done.
649 *bits |= 0x00002000;
650 return true;
651 } else if (!called_by_wait && !did_trans_retry &&
652 save_state == _thread_in_native_trans &&
653 frame_anchor()->walkable()) {
654 // The thread is transitioning from thread_in_native to another
655 // thread state. check_safepoint_and_suspend_for_native_trans()
656 // will force the thread to self-suspend. If it hasn't gotten
657 // there yet we may have caught the thread in-between the native
658 // code check above and the self-suspend. Lucky us. If we were
659 // called by wait_for_ext_suspend_completion(), then it
660 // will be doing the retries so we don't have to.
661 //
662 // Since we use the saved thread state in the if-statement above,
663 // there is a chance that the thread has already transitioned to
664 // _thread_blocked by the time we get here. In that case, we will
665 // make a single unnecessary pass through the logic below. This
666 // doesn't hurt anything since we still do the trans retry.
667
668 *bits |= 0x00004000;
669
670 // Once the thread leaves thread_in_native_trans for another
671 // thread state, we break out of this retry loop. We shouldn't
672 // need this flag to prevent us from getting back here, but
673 // sometimes paranoia is good.
674 did_trans_retry = true;
675
676 // We wait for the thread to transition to a more usable state.
677 for (int i = 1; i <= SuspendRetryCount; i++) {
678 // We used to do an "os::yield_all(i)" call here with the intention
679 // that yielding would increase on each retry. However, the parameter
680 // is ignored on Linux which means the yield didn't scale up. Waiting
681 // on the SR_lock below provides a much more predictable scale up for
682 // the delay. It also provides a simple/direct point to check for any
683 // safepoint requests from the VMThread
684
685 // temporarily drops SR_lock while doing wait with safepoint check
686 // (if we're a JavaThread - the WatcherThread can also call this)
687 // and increase delay with each retry
688 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
689
690 // check the actual thread state instead of what we saved above
691 if (thread_state() != _thread_in_native_trans) {
692 // the thread has transitioned to another thread state so
693 // try all the checks (except this one) one more time.
694 do_trans_retry = true;
695 break;
696 }
697 } // end retry loop
698
699
700 }
701 } while (do_trans_retry);
702
703 *bits |= 0x00000010;
704 return false;
705 }
706
707 // Wait for an external suspend request to complete (or be cancelled).
708 // Returns true if the thread is externally suspended and false otherwise.
709 //
710 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
711 uint32_t *bits) {
712 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
713 false /* !called_by_wait */, bits);
714
715 // local flag copies to minimize SR_lock hold time
716 bool is_suspended;
717 bool pending;
718 uint32_t reset_bits;
719
720 // set a marker so is_ext_suspend_completed() knows we are the caller
721 *bits |= 0x00010000;
722
723 // We use reset_bits to reinitialize the bits value at the top of
724 // each retry loop. This allows the caller to make use of any
725 // unused bits for their own marking purposes.
726 reset_bits = *bits;
727
728 {
729 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
730 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
731 delay, bits);
732 pending = is_external_suspend();
733 }
734 // must release SR_lock to allow suspension to complete
735
736 if (!pending) {
737 // A cancelled suspend request is the only false return from
738 // is_ext_suspend_completed() that keeps us from entering the
739 // retry loop.
740 *bits |= 0x00020000;
741 return false;
742 }
743
744 if (is_suspended) {
745 *bits |= 0x00040000;
746 return true;
747 }
748
749 for (int i = 1; i <= retries; i++) {
750 *bits = reset_bits; // reinit to only track last retry
751
752 // We used to do an "os::yield_all(i)" call here with the intention
753 // that yielding would increase on each retry. However, the parameter
754 // is ignored on Linux which means the yield didn't scale up. Waiting
755 // on the SR_lock below provides a much more predictable scale up for
756 // the delay. It also provides a simple/direct point to check for any
757 // safepoint requests from the VMThread
758
759 {
760 MutexLocker ml(SR_lock());
761 // wait with safepoint check (if we're a JavaThread - the WatcherThread
762 // can also call this) and increase delay with each retry
763 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
764
765 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
766 delay, bits);
767
768 // It is possible for the external suspend request to be cancelled
769 // (by a resume) before the actual suspend operation is completed.
770 // Refresh our local copy to see if we still need to wait.
771 pending = is_external_suspend();
772 }
773
774 if (!pending) {
775 // A cancelled suspend request is the only false return from
776 // is_ext_suspend_completed() that keeps us from staying in the
777 // retry loop.
778 *bits |= 0x00080000;
779 return false;
780 }
781
782 if (is_suspended) {
783 *bits |= 0x00100000;
784 return true;
785 }
786 } // end retry loop
787
788 // thread did not suspend after all our retries
789 *bits |= 0x00200000;
790 return false;
791 }
792
793 // Called from API entry points which perform stack walking. If the
794 // associated JavaThread is the current thread, then wait_for_suspend
795 // is not used. Otherwise, it determines if we should wait for the
796 // "other" thread to complete external suspension. (NOTE: in future
797 // releases the suspension mechanism should be reimplemented so this
798 // is not necessary.)
799 //
800 bool
801 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
802 if (this != JavaThread::current()) {
803 // "other" threads require special handling.
804 if (wait_for_suspend) {
805 // We are allowed to wait for the external suspend to complete
806 // so give the other thread a chance to get suspended.
807 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
808 SuspendRetryDelay, bits)) {
809 // Didn't make it so let the caller know.
810 return false;
811 }
812 }
813 // We aren't allowed to wait for the external suspend to complete
814 // so if the other thread isn't externally suspended we need to
815 // let the caller know.
816 else if (!is_ext_suspend_completed_with_lock(bits)) {
817 return false;
818 }
819 }
820
821 return true;
822 }
823
824 #ifndef PRODUCT
825 void JavaThread::record_jump(address target, address instr, const char* file,
826 int line) {
827
828 // This should not need to be atomic as the only way for simultaneous
829 // updates is via interrupts. Even then this should be rare or non-existent
830 // and we don't care that much anyway.
831
832 int index = _jmp_ring_index;
833 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
834 _jmp_ring[index]._target = (intptr_t) target;
835 _jmp_ring[index]._instruction = (intptr_t) instr;
836 _jmp_ring[index]._file = file;
837 _jmp_ring[index]._line = line;
838 }
839 #endif // PRODUCT
840
841 void Thread::interrupt(Thread* thread) {
842 debug_only(check_for_dangling_thread_pointer(thread);)
843 os::interrupt(thread);
844 }
845
846 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
847 debug_only(check_for_dangling_thread_pointer(thread);)
848 // Note: If clear_interrupted==false, this simply fetches and
849 // returns the value of the field osthread()->interrupted().
850 return os::is_interrupted(thread, clear_interrupted);
851 }
852
853
854 // GC Support
855 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
856 int thread_parity = _oops_do_parity;
857 if (thread_parity != strong_roots_parity) {
858 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
859 if (res == thread_parity) {
860 return true;
861 } else {
862 guarantee(res == strong_roots_parity, "Or else what?");
863 return false;
864 }
865 }
866 return false;
867 }
868
869 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
870 active_handles()->oops_do(f);
871 // Do oop for ThreadShadow
872 f->do_oop((oop*)&_pending_exception);
873 handle_area()->oops_do(f);
874
875 // We scan thread local monitor lists here, and the remaining global
876 // monitors in ObjectSynchronizer::oops_do().
877 ObjectSynchronizer::thread_local_used_oops_do(this, f);
878 }
879
880 void Thread::metadata_handles_do(void f(Metadata*)) {
881 // Only walk the Handles in Thread.
882 if (metadata_handles() != NULL) {
883 for (int i = 0; i< metadata_handles()->length(); i++) {
884 f(metadata_handles()->at(i));
885 }
886 }
887 }
888
889 void Thread::print_on(outputStream* st, bool print_extended_info) const {
890 // get_priority assumes osthread initialized
891 if (osthread() != NULL) {
892 int os_prio;
893 if (os::get_native_priority(this, &os_prio) == OS_OK) {
894 st->print("os_prio=%d ", os_prio);
895 }
896
897 st->print("cpu=%.2fms ",
898 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
899 );
900 st->print("elapsed=%.2fs ",
901 _statistical_info.getElapsedTime() / 1000.0
902 );
903 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
904 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
905 st->print("allocated=" SIZE_FORMAT "%s ",
906 byte_size_in_proper_unit(allocated_bytes),
907 proper_unit_for_byte_size(allocated_bytes)
908 );
909 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
910 }
911
912 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
913 osthread()->print_on(st);
914 }
915 ThreadsSMRSupport::print_info_on(this, st);
916 st->print(" ");
917 debug_only(if (WizardMode) print_owned_locks_on(st);)
918 }
919
920 // Thread::print_on_error() is called by fatal error handler. Don't use
921 // any lock or allocate memory.
922 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
923 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
924
925 if (is_VM_thread()) { st->print("VMThread"); }
926 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
927 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
928 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
929 else { st->print("Thread"); }
930
931 if (is_Named_thread()) {
932 st->print(" \"%s\"", name());
933 }
934
935 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
936 p2i(stack_end()), p2i(stack_base()));
937
938 if (osthread()) {
939 st->print(" [id=%d]", osthread()->thread_id());
940 }
941
942 ThreadsSMRSupport::print_info_on(this, st);
943 }
944
945 void Thread::print_value_on(outputStream* st) const {
946 if (is_Named_thread()) {
947 st->print(" \"%s\" ", name());
948 }
949 st->print(INTPTR_FORMAT, p2i(this)); // print address
950 }
951
952 #ifdef ASSERT
953 void Thread::print_owned_locks_on(outputStream* st) const {
954 Monitor *cur = _owned_locks;
955 if (cur == NULL) {
956 st->print(" (no locks) ");
957 } else {
958 st->print_cr(" Locks owned:");
959 while (cur) {
960 cur->print_on(st);
961 cur = cur->next();
962 }
963 }
964 }
965
966 static int ref_use_count = 0;
967
968 bool Thread::owns_locks_but_compiled_lock() const {
969 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
970 if (cur != Compile_lock) return true;
971 }
972 return false;
973 }
974
975
976 #endif
977
978 #ifndef PRODUCT
979
980 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
981 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
982 // no locks which allow_vm_block's are held
983 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
984 // Check if current thread is allowed to block at a safepoint
985 if (!(_allow_safepoint_count == 0)) {
986 fatal("Possible safepoint reached by thread that does not allow it");
987 }
988 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
989 fatal("LEAF method calling lock?");
990 }
991
992 #ifdef ASSERT
993 if (potential_vm_operation && is_Java_thread()
994 && !Universe::is_bootstrapping()) {
995 // Make sure we do not hold any locks that the VM thread also uses.
996 // This could potentially lead to deadlocks
997 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
998 // Threads_lock is special, since the safepoint synchronization will not start before this is
999 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1000 // since it is used to transfer control between JavaThreads and the VMThread
1001 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1002 if ((cur->allow_vm_block() &&
1003 cur != Threads_lock &&
1004 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1005 cur != VMOperationRequest_lock &&
1006 cur != VMOperationQueue_lock) ||
1007 cur->rank() == Mutex::special) {
1008 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1009 }
1010 }
1011 }
1012
1013 if (GCALotAtAllSafepoints) {
1014 // We could enter a safepoint here and thus have a gc
1015 InterfaceSupport::check_gc_alot();
1016 }
1017 #endif
1018 }
1019 #endif
1020
1021 bool Thread::is_in_stack(address adr) const {
1022 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1023 address end = os::current_stack_pointer();
1024 // Allow non Java threads to call this without stack_base
1025 if (_stack_base == NULL) return true;
1026 if (stack_base() >= adr && adr >= end) return true;
1027
1028 return false;
1029 }
1030
1031 bool Thread::is_in_usable_stack(address adr) const {
1032 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1033 size_t usable_stack_size = _stack_size - stack_guard_size;
1034
1035 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1036 }
1037
1038
1039 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1040 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1041 // used for compilation in the future. If that change is made, the need for these methods
1042 // should be revisited, and they should be removed if possible.
1043
1044 bool Thread::is_lock_owned(address adr) const {
1045 return on_local_stack(adr);
1046 }
1047
1048 bool Thread::set_as_starting_thread() {
1049 // NOTE: this must be called inside the main thread.
1050 return os::create_main_thread((JavaThread*)this);
1051 }
1052
1053 static void initialize_class(Symbol* class_name, TRAPS) {
1054 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1055 InstanceKlass::cast(klass)->initialize(CHECK);
1056 }
1057
1058
1059 // Creates the initial ThreadGroup
1060 static Handle create_initial_thread_group(TRAPS) {
1061 Handle system_instance = JavaCalls::construct_new_instance(
1062 SystemDictionary::ThreadGroup_klass(),
1063 vmSymbols::void_method_signature(),
1064 CHECK_NH);
1065 Universe::set_system_thread_group(system_instance());
1066
1067 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1068 Handle main_instance = JavaCalls::construct_new_instance(
1069 SystemDictionary::ThreadGroup_klass(),
1070 vmSymbols::threadgroup_string_void_signature(),
1071 system_instance,
1072 string,
1073 CHECK_NH);
1074 return main_instance;
1075 }
1076
1077 // Creates the initial Thread
1078 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1079 TRAPS) {
1080 InstanceKlass* ik = SystemDictionary::Thread_klass();
1081 assert(ik->is_initialized(), "must be");
1082 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1083
1084 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1085 // constructor calls Thread.current(), which must be set here for the
1086 // initial thread.
1087 java_lang_Thread::set_thread(thread_oop(), thread);
1088 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1089 thread->set_threadObj(thread_oop());
1090
1091 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1092
1093 JavaValue result(T_VOID);
1094 JavaCalls::call_special(&result, thread_oop,
1095 ik,
1096 vmSymbols::object_initializer_name(),
1097 vmSymbols::threadgroup_string_void_signature(),
1098 thread_group,
1099 string,
1100 CHECK_NULL);
1101 return thread_oop();
1102 }
1103
1104 char java_runtime_name[128] = "";
1105 char java_runtime_version[128] = "";
1106
1107 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1108 static const char* get_java_runtime_name(TRAPS) {
1109 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1110 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1111 fieldDescriptor fd;
1112 bool found = k != NULL &&
1113 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1114 vmSymbols::string_signature(), &fd);
1115 if (found) {
1116 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1117 if (name_oop == NULL) {
1118 return NULL;
1119 }
1120 const char* name = java_lang_String::as_utf8_string(name_oop,
1121 java_runtime_name,
1122 sizeof(java_runtime_name));
1123 return name;
1124 } else {
1125 return NULL;
1126 }
1127 }
1128
1129 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1130 static const char* get_java_runtime_version(TRAPS) {
1131 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1132 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1133 fieldDescriptor fd;
1134 bool found = k != NULL &&
1135 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1136 vmSymbols::string_signature(), &fd);
1137 if (found) {
1138 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1139 if (name_oop == NULL) {
1140 return NULL;
1141 }
1142 const char* name = java_lang_String::as_utf8_string(name_oop,
1143 java_runtime_version,
1144 sizeof(java_runtime_version));
1145 return name;
1146 } else {
1147 return NULL;
1148 }
1149 }
1150
1151 // General purpose hook into Java code, run once when the VM is initialized.
1152 // The Java library method itself may be changed independently from the VM.
1153 static void call_postVMInitHook(TRAPS) {
1154 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1155 if (klass != NULL) {
1156 JavaValue result(T_VOID);
1157 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1158 vmSymbols::void_method_signature(),
1159 CHECK);
1160 }
1161 }
1162
1163 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1164 bool daemon, TRAPS) {
1165 assert(thread_group.not_null(), "thread group should be specified");
1166 assert(threadObj() == NULL, "should only create Java thread object once");
1167
1168 InstanceKlass* ik = SystemDictionary::Thread_klass();
1169 assert(ik->is_initialized(), "must be");
1170 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1171
1172 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1173 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1174 // constructor calls Thread.current(), which must be set here.
1175 java_lang_Thread::set_thread(thread_oop(), this);
1176 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1177 set_threadObj(thread_oop());
1178
1179 JavaValue result(T_VOID);
1180 if (thread_name != NULL) {
1181 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1182 // Thread gets assigned specified name and null target
1183 JavaCalls::call_special(&result,
1184 thread_oop,
1185 ik,
1186 vmSymbols::object_initializer_name(),
1187 vmSymbols::threadgroup_string_void_signature(),
1188 thread_group,
1189 name,
1190 THREAD);
1191 } else {
1192 // Thread gets assigned name "Thread-nnn" and null target
1193 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1194 JavaCalls::call_special(&result,
1195 thread_oop,
1196 ik,
1197 vmSymbols::object_initializer_name(),
1198 vmSymbols::threadgroup_runnable_void_signature(),
1199 thread_group,
1200 Handle(),
1201 THREAD);
1202 }
1203
1204
1205 if (daemon) {
1206 java_lang_Thread::set_daemon(thread_oop());
1207 }
1208
1209 if (HAS_PENDING_EXCEPTION) {
1210 return;
1211 }
1212
1213 Klass* group = SystemDictionary::ThreadGroup_klass();
1214 Handle threadObj(THREAD, this->threadObj());
1215
1216 JavaCalls::call_special(&result,
1217 thread_group,
1218 group,
1219 vmSymbols::add_method_name(),
1220 vmSymbols::thread_void_signature(),
1221 threadObj, // Arg 1
1222 THREAD);
1223 }
1224
1225 // List of all NonJavaThreads and safe iteration over that list.
1226
1227 class NonJavaThread::List {
1228 public:
1229 NonJavaThread* volatile _head;
1230 SingleWriterSynchronizer _protect;
1231
1232 List() : _head(NULL), _protect() {}
1233 };
1234
1235 NonJavaThread::List NonJavaThread::_the_list;
1236
1237 NonJavaThread::Iterator::Iterator() :
1238 _protect_enter(_the_list._protect.enter()),
1239 _current(OrderAccess::load_acquire(&_the_list._head))
1240 {}
1241
1242 NonJavaThread::Iterator::~Iterator() {
1243 _the_list._protect.exit(_protect_enter);
1244 }
1245
1246 void NonJavaThread::Iterator::step() {
1247 assert(!end(), "precondition");
1248 _current = OrderAccess::load_acquire(&_current->_next);
1249 }
1250
1251 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1252 // Add this thread to _the_list.
1253 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1254 _next = _the_list._head;
1255 OrderAccess::release_store(&_the_list._head, this);
1256 }
1257
1258 NonJavaThread::~NonJavaThread() {
1259 JFR_ONLY(Jfr::on_thread_exit(this);)
1260 // Remove this thread from _the_list.
1261 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1262 NonJavaThread* volatile* p = &_the_list._head;
1263 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1264 if (t == this) {
1265 *p = this->_next;
1266 // Wait for any in-progress iterators.
1267 _the_list._protect.synchronize();
1268 break;
1269 }
1270 }
1271 }
1272
1273 // NamedThread -- non-JavaThread subclasses with multiple
1274 // uniquely named instances should derive from this.
1275 NamedThread::NamedThread() :
1276 NonJavaThread(),
1277 _name(NULL),
1278 _processed_thread(NULL),
1279 _gc_id(GCId::undefined())
1280 {}
1281
1282 NamedThread::~NamedThread() {
1283 if (_name != NULL) {
1284 FREE_C_HEAP_ARRAY(char, _name);
1285 _name = NULL;
1286 }
1287 }
1288
1289 void NamedThread::set_name(const char* format, ...) {
1290 guarantee(_name == NULL, "Only get to set name once.");
1291 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1292 guarantee(_name != NULL, "alloc failure");
1293 va_list ap;
1294 va_start(ap, format);
1295 jio_vsnprintf(_name, max_name_len, format, ap);
1296 va_end(ap);
1297 }
1298
1299 void NamedThread::initialize_named_thread() {
1300 set_native_thread_name(name());
1301 }
1302
1303 void NamedThread::print_on(outputStream* st) const {
1304 st->print("\"%s\" ", name());
1305 Thread::print_on(st);
1306 st->cr();
1307 }
1308
1309
1310 // ======= WatcherThread ========
1311
1312 // The watcher thread exists to simulate timer interrupts. It should
1313 // be replaced by an abstraction over whatever native support for
1314 // timer interrupts exists on the platform.
1315
1316 WatcherThread* WatcherThread::_watcher_thread = NULL;
1317 bool WatcherThread::_startable = false;
1318 volatile bool WatcherThread::_should_terminate = false;
1319
1320 WatcherThread::WatcherThread() : NonJavaThread() {
1321 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1322 if (os::create_thread(this, os::watcher_thread)) {
1323 _watcher_thread = this;
1324
1325 // Set the watcher thread to the highest OS priority which should not be
1326 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1327 // is created. The only normal thread using this priority is the reference
1328 // handler thread, which runs for very short intervals only.
1329 // If the VMThread's priority is not lower than the WatcherThread profiling
1330 // will be inaccurate.
1331 os::set_priority(this, MaxPriority);
1332 if (!DisableStartThread) {
1333 os::start_thread(this);
1334 }
1335 }
1336 }
1337
1338 int WatcherThread::sleep() const {
1339 // The WatcherThread does not participate in the safepoint protocol
1340 // for the PeriodicTask_lock because it is not a JavaThread.
1341 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1342
1343 if (_should_terminate) {
1344 // check for termination before we do any housekeeping or wait
1345 return 0; // we did not sleep.
1346 }
1347
1348 // remaining will be zero if there are no tasks,
1349 // causing the WatcherThread to sleep until a task is
1350 // enrolled
1351 int remaining = PeriodicTask::time_to_wait();
1352 int time_slept = 0;
1353
1354 // we expect this to timeout - we only ever get unparked when
1355 // we should terminate or when a new task has been enrolled
1356 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1357
1358 jlong time_before_loop = os::javaTimeNanos();
1359
1360 while (true) {
1361 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1362 remaining);
1363 jlong now = os::javaTimeNanos();
1364
1365 if (remaining == 0) {
1366 // if we didn't have any tasks we could have waited for a long time
1367 // consider the time_slept zero and reset time_before_loop
1368 time_slept = 0;
1369 time_before_loop = now;
1370 } else {
1371 // need to recalculate since we might have new tasks in _tasks
1372 time_slept = (int) ((now - time_before_loop) / 1000000);
1373 }
1374
1375 // Change to task list or spurious wakeup of some kind
1376 if (timedout || _should_terminate) {
1377 break;
1378 }
1379
1380 remaining = PeriodicTask::time_to_wait();
1381 if (remaining == 0) {
1382 // Last task was just disenrolled so loop around and wait until
1383 // another task gets enrolled
1384 continue;
1385 }
1386
1387 remaining -= time_slept;
1388 if (remaining <= 0) {
1389 break;
1390 }
1391 }
1392
1393 return time_slept;
1394 }
1395
1396 void WatcherThread::run() {
1397 assert(this == watcher_thread(), "just checking");
1398
1399 this->set_native_thread_name(this->name());
1400 this->set_active_handles(JNIHandleBlock::allocate_block());
1401 while (true) {
1402 assert(watcher_thread() == Thread::current(), "thread consistency check");
1403 assert(watcher_thread() == this, "thread consistency check");
1404
1405 // Calculate how long it'll be until the next PeriodicTask work
1406 // should be done, and sleep that amount of time.
1407 int time_waited = sleep();
1408
1409 if (VMError::is_error_reported()) {
1410 // A fatal error has happened, the error handler(VMError::report_and_die)
1411 // should abort JVM after creating an error log file. However in some
1412 // rare cases, the error handler itself might deadlock. Here periodically
1413 // check for error reporting timeouts, and if it happens, just proceed to
1414 // abort the VM.
1415
1416 // This code is in WatcherThread because WatcherThread wakes up
1417 // periodically so the fatal error handler doesn't need to do anything;
1418 // also because the WatcherThread is less likely to crash than other
1419 // threads.
1420
1421 for (;;) {
1422 // Note: we use naked sleep in this loop because we want to avoid using
1423 // any kind of VM infrastructure which may be broken at this point.
1424 if (VMError::check_timeout()) {
1425 // We hit error reporting timeout. Error reporting was interrupted and
1426 // will be wrapping things up now (closing files etc). Give it some more
1427 // time, then quit the VM.
1428 os::naked_short_sleep(200);
1429 // Print a message to stderr.
1430 fdStream err(defaultStream::output_fd());
1431 err.print_raw_cr("# [ timer expired, abort... ]");
1432 // skip atexit/vm_exit/vm_abort hooks
1433 os::die();
1434 }
1435
1436 // Wait a second, then recheck for timeout.
1437 os::naked_short_sleep(999);
1438 }
1439 }
1440
1441 if (_should_terminate) {
1442 // check for termination before posting the next tick
1443 break;
1444 }
1445
1446 PeriodicTask::real_time_tick(time_waited);
1447 }
1448
1449 // Signal that it is terminated
1450 {
1451 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1452 _watcher_thread = NULL;
1453 Terminator_lock->notify();
1454 }
1455 }
1456
1457 void WatcherThread::start() {
1458 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1459
1460 if (watcher_thread() == NULL && _startable) {
1461 _should_terminate = false;
1462 // Create the single instance of WatcherThread
1463 new WatcherThread();
1464 }
1465 }
1466
1467 void WatcherThread::make_startable() {
1468 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1469 _startable = true;
1470 }
1471
1472 void WatcherThread::stop() {
1473 {
1474 // Follow normal safepoint aware lock enter protocol since the
1475 // WatcherThread is stopped by another JavaThread.
1476 MutexLocker ml(PeriodicTask_lock);
1477 _should_terminate = true;
1478
1479 WatcherThread* watcher = watcher_thread();
1480 if (watcher != NULL) {
1481 // unpark the WatcherThread so it can see that it should terminate
1482 watcher->unpark();
1483 }
1484 }
1485
1486 MutexLocker mu(Terminator_lock);
1487
1488 while (watcher_thread() != NULL) {
1489 // This wait should make safepoint checks, wait without a timeout,
1490 // and wait as a suspend-equivalent condition.
1491 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1492 Mutex::_as_suspend_equivalent_flag);
1493 }
1494 }
1495
1496 void WatcherThread::unpark() {
1497 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1498 PeriodicTask_lock->notify();
1499 }
1500
1501 void WatcherThread::print_on(outputStream* st) const {
1502 st->print("\"%s\" ", name());
1503 Thread::print_on(st);
1504 st->cr();
1505 }
1506
1507 // ======= JavaThread ========
1508
1509 #if INCLUDE_JVMCI
1510
1511 jlong* JavaThread::_jvmci_old_thread_counters;
1512
1513 bool jvmci_counters_include(JavaThread* thread) {
1514 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1515 }
1516
1517 void JavaThread::collect_counters(typeArrayOop array) {
1518 if (JVMCICounterSize > 0) {
1519 JavaThreadIteratorWithHandle jtiwh;
1520 for (int i = 0; i < array->length(); i++) {
1521 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1522 }
1523 for (; JavaThread *tp = jtiwh.next(); ) {
1524 if (jvmci_counters_include(tp)) {
1525 for (int i = 0; i < array->length(); i++) {
1526 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1527 }
1528 }
1529 }
1530 }
1531 }
1532
1533 #endif // INCLUDE_JVMCI
1534
1535 // A JavaThread is a normal Java thread
1536
1537 void JavaThread::initialize() {
1538 // Initialize fields
1539
1540 set_saved_exception_pc(NULL);
1541 set_threadObj(NULL);
1542 _anchor.clear();
1543 set_entry_point(NULL);
1544 set_jni_functions(jni_functions());
1545 set_callee_target(NULL);
1546 set_vm_result(NULL);
1547 set_vm_result_2(NULL);
1548 set_vframe_array_head(NULL);
1549 set_vframe_array_last(NULL);
1550 set_deferred_locals(NULL);
1551 set_deopt_mark(NULL);
1552 set_deopt_compiled_method(NULL);
1553 clear_must_deopt_id();
1554 set_monitor_chunks(NULL);
1555 set_next(NULL);
1556 _on_thread_list = false;
1557 set_thread_state(_thread_new);
1558 _terminated = _not_terminated;
1559 _array_for_gc = NULL;
1560 _suspend_equivalent = false;
1561 _in_deopt_handler = 0;
1562 _doing_unsafe_access = false;
1563 _stack_guard_state = stack_guard_unused;
1564 #if INCLUDE_JVMCI
1565 _pending_monitorenter = false;
1566 _pending_deoptimization = -1;
1567 _pending_failed_speculation = 0;
1568 _pending_transfer_to_interpreter = false;
1569 _adjusting_comp_level = false;
1570 _in_retryable_allocation = false;
1571 _jvmci._alternate_call_target = NULL;
1572 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1573 if (JVMCICounterSize > 0) {
1574 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1575 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1576 } else {
1577 _jvmci_counters = NULL;
1578 }
1579 #endif // INCLUDE_JVMCI
1580 _reserved_stack_activation = NULL; // stack base not known yet
1581 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1582 _exception_pc = 0;
1583 _exception_handler_pc = 0;
1584 _is_method_handle_return = 0;
1585 _jvmti_thread_state= NULL;
1586 _should_post_on_exceptions_flag = JNI_FALSE;
1587 _interp_only_mode = 0;
1588 _special_runtime_exit_condition = _no_async_condition;
1589 _pending_async_exception = NULL;
1590 _thread_stat = NULL;
1591 _thread_stat = new ThreadStatistics();
1592 _blocked_on_compilation = false;
1593 _jni_active_critical = 0;
1594 _pending_jni_exception_check_fn = NULL;
1595 _do_not_unlock_if_synchronized = false;
1596 _cached_monitor_info = NULL;
1597 _parker = Parker::Allocate(this);
1598
1599 #ifndef PRODUCT
1600 _jmp_ring_index = 0;
1601 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1602 record_jump(NULL, NULL, NULL, 0);
1603 }
1604 #endif // PRODUCT
1605
1606 // Setup safepoint state info for this thread
1607 ThreadSafepointState::create(this);
1608
1609 debug_only(_java_call_counter = 0);
1610
1611 // JVMTI PopFrame support
1612 _popframe_condition = popframe_inactive;
1613 _popframe_preserved_args = NULL;
1614 _popframe_preserved_args_size = 0;
1615 _frames_to_pop_failed_realloc = 0;
1616
1617 if (SafepointMechanism::uses_thread_local_poll()) {
1618 SafepointMechanism::initialize_header(this);
1619 }
1620
1621 pd_initialize();
1622 }
1623
1624 JavaThread::JavaThread(bool is_attaching_via_jni) :
1625 Thread() {
1626 initialize();
1627 if (is_attaching_via_jni) {
1628 _jni_attach_state = _attaching_via_jni;
1629 } else {
1630 _jni_attach_state = _not_attaching_via_jni;
1631 }
1632 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1633 }
1634
1635 bool JavaThread::reguard_stack(address cur_sp) {
1636 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1637 && _stack_guard_state != stack_guard_reserved_disabled) {
1638 return true; // Stack already guarded or guard pages not needed.
1639 }
1640
1641 if (register_stack_overflow()) {
1642 // For those architectures which have separate register and
1643 // memory stacks, we must check the register stack to see if
1644 // it has overflowed.
1645 return false;
1646 }
1647
1648 // Java code never executes within the yellow zone: the latter is only
1649 // there to provoke an exception during stack banging. If java code
1650 // is executing there, either StackShadowPages should be larger, or
1651 // some exception code in c1, c2 or the interpreter isn't unwinding
1652 // when it should.
1653 guarantee(cur_sp > stack_reserved_zone_base(),
1654 "not enough space to reguard - increase StackShadowPages");
1655 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1656 enable_stack_yellow_reserved_zone();
1657 if (reserved_stack_activation() != stack_base()) {
1658 set_reserved_stack_activation(stack_base());
1659 }
1660 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1661 set_reserved_stack_activation(stack_base());
1662 enable_stack_reserved_zone();
1663 }
1664 return true;
1665 }
1666
1667 bool JavaThread::reguard_stack(void) {
1668 return reguard_stack(os::current_stack_pointer());
1669 }
1670
1671
1672 void JavaThread::block_if_vm_exited() {
1673 if (_terminated == _vm_exited) {
1674 // _vm_exited is set at safepoint, and Threads_lock is never released
1675 // we will block here forever
1676 Threads_lock->lock_without_safepoint_check();
1677 ShouldNotReachHere();
1678 }
1679 }
1680
1681
1682 // Remove this ifdef when C1 is ported to the compiler interface.
1683 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1684 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1685
1686 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1687 Thread() {
1688 initialize();
1689 _jni_attach_state = _not_attaching_via_jni;
1690 set_entry_point(entry_point);
1691 // Create the native thread itself.
1692 // %note runtime_23
1693 os::ThreadType thr_type = os::java_thread;
1694 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1695 os::java_thread;
1696 os::create_thread(this, thr_type, stack_sz);
1697 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1698 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1699 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1700 // the exception consists of creating the exception object & initializing it, initialization
1701 // will leave the VM via a JavaCall and then all locks must be unlocked).
1702 //
1703 // The thread is still suspended when we reach here. Thread must be explicit started
1704 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1705 // by calling Threads:add. The reason why this is not done here, is because the thread
1706 // object must be fully initialized (take a look at JVM_Start)
1707 }
1708
1709 JavaThread::~JavaThread() {
1710
1711 // JSR166 -- return the parker to the free list
1712 Parker::Release(_parker);
1713 _parker = NULL;
1714
1715 // Free any remaining previous UnrollBlock
1716 vframeArray* old_array = vframe_array_last();
1717
1718 if (old_array != NULL) {
1719 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1720 old_array->set_unroll_block(NULL);
1721 delete old_info;
1722 delete old_array;
1723 }
1724
1725 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1726 if (deferred != NULL) {
1727 // This can only happen if thread is destroyed before deoptimization occurs.
1728 assert(deferred->length() != 0, "empty array!");
1729 do {
1730 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1731 deferred->remove_at(0);
1732 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1733 delete dlv;
1734 } while (deferred->length() != 0);
1735 delete deferred;
1736 }
1737
1738 // All Java related clean up happens in exit
1739 ThreadSafepointState::destroy(this);
1740 if (_thread_stat != NULL) delete _thread_stat;
1741
1742 #if INCLUDE_JVMCI
1743 if (JVMCICounterSize > 0) {
1744 if (jvmci_counters_include(this)) {
1745 for (int i = 0; i < JVMCICounterSize; i++) {
1746 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1747 }
1748 }
1749 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1750 }
1751 #endif // INCLUDE_JVMCI
1752 }
1753
1754
1755 // The first routine called by a new Java thread
1756 void JavaThread::run() {
1757 // initialize thread-local alloc buffer related fields
1758 this->initialize_tlab();
1759
1760 // used to test validity of stack trace backs
1761 this->record_base_of_stack_pointer();
1762
1763 this->create_stack_guard_pages();
1764
1765 this->cache_global_variables();
1766
1767 // Thread is now sufficient initialized to be handled by the safepoint code as being
1768 // in the VM. Change thread state from _thread_new to _thread_in_vm
1769 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1770
1771 assert(JavaThread::current() == this, "sanity check");
1772 assert(!Thread::current()->owns_locks(), "sanity check");
1773
1774 DTRACE_THREAD_PROBE(start, this);
1775
1776 // This operation might block. We call that after all safepoint checks for a new thread has
1777 // been completed.
1778 this->set_active_handles(JNIHandleBlock::allocate_block());
1779
1780 if (JvmtiExport::should_post_thread_life()) {
1781 JvmtiExport::post_thread_start(this);
1782
1783 }
1784
1785 // We call another function to do the rest so we are sure that the stack addresses used
1786 // from there will be lower than the stack base just computed
1787 thread_main_inner();
1788
1789 // Note, thread is no longer valid at this point!
1790 }
1791
1792
1793 void JavaThread::thread_main_inner() {
1794 assert(JavaThread::current() == this, "sanity check");
1795 assert(this->threadObj() != NULL, "just checking");
1796
1797 // Execute thread entry point unless this thread has a pending exception
1798 // or has been stopped before starting.
1799 // Note: Due to JVM_StopThread we can have pending exceptions already!
1800 if (!this->has_pending_exception() &&
1801 !java_lang_Thread::is_stillborn(this->threadObj())) {
1802 {
1803 ResourceMark rm(this);
1804 this->set_native_thread_name(this->get_thread_name());
1805 }
1806 HandleMark hm(this);
1807 this->entry_point()(this, this);
1808 }
1809
1810 DTRACE_THREAD_PROBE(stop, this);
1811
1812 this->exit(false);
1813 this->smr_delete();
1814 }
1815
1816
1817 static void ensure_join(JavaThread* thread) {
1818 // We do not need to grab the Threads_lock, since we are operating on ourself.
1819 Handle threadObj(thread, thread->threadObj());
1820 assert(threadObj.not_null(), "java thread object must exist");
1821 ObjectLocker lock(threadObj, thread);
1822 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1823 thread->clear_pending_exception();
1824 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1825 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1826 // Clear the native thread instance - this makes isAlive return false and allows the join()
1827 // to complete once we've done the notify_all below
1828 java_lang_Thread::set_thread(threadObj(), NULL);
1829 lock.notify_all(thread);
1830 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1831 thread->clear_pending_exception();
1832 }
1833
1834 static bool is_daemon(oop threadObj) {
1835 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1836 }
1837
1838 // For any new cleanup additions, please check to see if they need to be applied to
1839 // cleanup_failed_attach_current_thread as well.
1840 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1841 assert(this == JavaThread::current(), "thread consistency check");
1842
1843 elapsedTimer _timer_exit_phase1;
1844 elapsedTimer _timer_exit_phase2;
1845 elapsedTimer _timer_exit_phase3;
1846 elapsedTimer _timer_exit_phase4;
1847
1848 if (log_is_enabled(Debug, os, thread, timer)) {
1849 _timer_exit_phase1.start();
1850 }
1851
1852 HandleMark hm(this);
1853 Handle uncaught_exception(this, this->pending_exception());
1854 this->clear_pending_exception();
1855 Handle threadObj(this, this->threadObj());
1856 assert(threadObj.not_null(), "Java thread object should be created");
1857
1858 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1859 {
1860 EXCEPTION_MARK;
1861
1862 CLEAR_PENDING_EXCEPTION;
1863 }
1864 if (!destroy_vm) {
1865 if (uncaught_exception.not_null()) {
1866 EXCEPTION_MARK;
1867 // Call method Thread.dispatchUncaughtException().
1868 Klass* thread_klass = SystemDictionary::Thread_klass();
1869 JavaValue result(T_VOID);
1870 JavaCalls::call_virtual(&result,
1871 threadObj, thread_klass,
1872 vmSymbols::dispatchUncaughtException_name(),
1873 vmSymbols::throwable_void_signature(),
1874 uncaught_exception,
1875 THREAD);
1876 if (HAS_PENDING_EXCEPTION) {
1877 ResourceMark rm(this);
1878 jio_fprintf(defaultStream::error_stream(),
1879 "\nException: %s thrown from the UncaughtExceptionHandler"
1880 " in thread \"%s\"\n",
1881 pending_exception()->klass()->external_name(),
1882 get_thread_name());
1883 CLEAR_PENDING_EXCEPTION;
1884 }
1885 }
1886 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1887
1888 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1889 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1890 // is deprecated anyhow.
1891 if (!is_Compiler_thread()) {
1892 int count = 3;
1893 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1894 EXCEPTION_MARK;
1895 JavaValue result(T_VOID);
1896 Klass* thread_klass = SystemDictionary::Thread_klass();
1897 JavaCalls::call_virtual(&result,
1898 threadObj, thread_klass,
1899 vmSymbols::exit_method_name(),
1900 vmSymbols::void_method_signature(),
1901 THREAD);
1902 CLEAR_PENDING_EXCEPTION;
1903 }
1904 }
1905 // notify JVMTI
1906 if (JvmtiExport::should_post_thread_life()) {
1907 JvmtiExport::post_thread_end(this);
1908 }
1909
1910 // We have notified the agents that we are exiting, before we go on,
1911 // we must check for a pending external suspend request and honor it
1912 // in order to not surprise the thread that made the suspend request.
1913 while (true) {
1914 {
1915 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1916 if (!is_external_suspend()) {
1917 set_terminated(_thread_exiting);
1918 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1919 break;
1920 }
1921 // Implied else:
1922 // Things get a little tricky here. We have a pending external
1923 // suspend request, but we are holding the SR_lock so we
1924 // can't just self-suspend. So we temporarily drop the lock
1925 // and then self-suspend.
1926 }
1927
1928 ThreadBlockInVM tbivm(this);
1929 java_suspend_self();
1930
1931 // We're done with this suspend request, but we have to loop around
1932 // and check again. Eventually we will get SR_lock without a pending
1933 // external suspend request and will be able to mark ourselves as
1934 // exiting.
1935 }
1936 // no more external suspends are allowed at this point
1937 } else {
1938 assert(!is_terminated() && !is_exiting(), "must not be exiting");
1939 // before_exit() has already posted JVMTI THREAD_END events
1940 }
1941
1942 if (log_is_enabled(Debug, os, thread, timer)) {
1943 _timer_exit_phase1.stop();
1944 _timer_exit_phase2.start();
1945 }
1946 // Notify waiters on thread object. This has to be done after exit() is called
1947 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1948 // group should have the destroyed bit set before waiters are notified).
1949 ensure_join(this);
1950 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1951
1952 if (log_is_enabled(Debug, os, thread, timer)) {
1953 _timer_exit_phase2.stop();
1954 _timer_exit_phase3.start();
1955 }
1956 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1957 // held by this thread must be released. The spec does not distinguish
1958 // between JNI-acquired and regular Java monitors. We can only see
1959 // regular Java monitors here if monitor enter-exit matching is broken.
1960 //
1961 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1962 // ObjectSynchronizer::release_monitors_owned_by_thread().
1963 if (exit_type == jni_detach) {
1964 // Sanity check even though JNI DetachCurrentThread() would have
1965 // returned JNI_ERR if there was a Java frame. JavaThread exit
1966 // should be done executing Java code by the time we get here.
1967 assert(!this->has_last_Java_frame(),
1968 "should not have a Java frame when detaching or exiting");
1969 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1970 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1971 }
1972
1973 // These things needs to be done while we are still a Java Thread. Make sure that thread
1974 // is in a consistent state, in case GC happens
1975 JFR_ONLY(Jfr::on_thread_exit(this);)
1976
1977 if (active_handles() != NULL) {
1978 JNIHandleBlock* block = active_handles();
1979 set_active_handles(NULL);
1980 JNIHandleBlock::release_block(block);
1981 }
1982
1983 if (free_handle_block() != NULL) {
1984 JNIHandleBlock* block = free_handle_block();
1985 set_free_handle_block(NULL);
1986 JNIHandleBlock::release_block(block);
1987 }
1988
1989 // These have to be removed while this is still a valid thread.
1990 remove_stack_guard_pages();
1991
1992 if (UseTLAB) {
1993 tlab().retire();
1994 }
1995
1996 if (JvmtiEnv::environments_might_exist()) {
1997 JvmtiExport::cleanup_thread(this);
1998 }
1999
2000 // We must flush any deferred card marks and other various GC barrier
2001 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2002 // before removing a thread from the list of active threads.
2003 BarrierSet::barrier_set()->on_thread_detach(this);
2004
2005 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2006 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2007 os::current_thread_id());
2008
2009 if (log_is_enabled(Debug, os, thread, timer)) {
2010 _timer_exit_phase3.stop();
2011 _timer_exit_phase4.start();
2012 }
2013 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2014 Threads::remove(this);
2015
2016 if (log_is_enabled(Debug, os, thread, timer)) {
2017 _timer_exit_phase4.stop();
2018 ResourceMark rm(this);
2019 log_debug(os, thread, timer)("name='%s'"
2020 ", exit-phase1=" JLONG_FORMAT
2021 ", exit-phase2=" JLONG_FORMAT
2022 ", exit-phase3=" JLONG_FORMAT
2023 ", exit-phase4=" JLONG_FORMAT,
2024 get_thread_name(),
2025 _timer_exit_phase1.milliseconds(),
2026 _timer_exit_phase2.milliseconds(),
2027 _timer_exit_phase3.milliseconds(),
2028 _timer_exit_phase4.milliseconds());
2029 }
2030 }
2031
2032 void JavaThread::cleanup_failed_attach_current_thread() {
2033 if (active_handles() != NULL) {
2034 JNIHandleBlock* block = active_handles();
2035 set_active_handles(NULL);
2036 JNIHandleBlock::release_block(block);
2037 }
2038
2039 if (free_handle_block() != NULL) {
2040 JNIHandleBlock* block = free_handle_block();
2041 set_free_handle_block(NULL);
2042 JNIHandleBlock::release_block(block);
2043 }
2044
2045 // These have to be removed while this is still a valid thread.
2046 remove_stack_guard_pages();
2047
2048 if (UseTLAB) {
2049 tlab().retire();
2050 }
2051
2052 BarrierSet::barrier_set()->on_thread_detach(this);
2053
2054 Threads::remove(this);
2055 this->smr_delete();
2056 }
2057
2058 JavaThread* JavaThread::active() {
2059 Thread* thread = Thread::current();
2060 if (thread->is_Java_thread()) {
2061 return (JavaThread*) thread;
2062 } else {
2063 assert(thread->is_VM_thread(), "this must be a vm thread");
2064 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2065 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2066 assert(ret->is_Java_thread(), "must be a Java thread");
2067 return ret;
2068 }
2069 }
2070
2071 bool JavaThread::is_lock_owned(address adr) const {
2072 if (Thread::is_lock_owned(adr)) return true;
2073
2074 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2075 if (chunk->contains(adr)) return true;
2076 }
2077
2078 return false;
2079 }
2080
2081
2082 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2083 chunk->set_next(monitor_chunks());
2084 set_monitor_chunks(chunk);
2085 }
2086
2087 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2088 guarantee(monitor_chunks() != NULL, "must be non empty");
2089 if (monitor_chunks() == chunk) {
2090 set_monitor_chunks(chunk->next());
2091 } else {
2092 MonitorChunk* prev = monitor_chunks();
2093 while (prev->next() != chunk) prev = prev->next();
2094 prev->set_next(chunk->next());
2095 }
2096 }
2097
2098 // JVM support.
2099
2100 // Note: this function shouldn't block if it's called in
2101 // _thread_in_native_trans state (such as from
2102 // check_special_condition_for_native_trans()).
2103 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2104
2105 if (has_last_Java_frame() && has_async_condition()) {
2106 // If we are at a polling page safepoint (not a poll return)
2107 // then we must defer async exception because live registers
2108 // will be clobbered by the exception path. Poll return is
2109 // ok because the call we a returning from already collides
2110 // with exception handling registers and so there is no issue.
2111 // (The exception handling path kills call result registers but
2112 // this is ok since the exception kills the result anyway).
2113
2114 if (is_at_poll_safepoint()) {
2115 // if the code we are returning to has deoptimized we must defer
2116 // the exception otherwise live registers get clobbered on the
2117 // exception path before deoptimization is able to retrieve them.
2118 //
2119 RegisterMap map(this, false);
2120 frame caller_fr = last_frame().sender(&map);
2121 assert(caller_fr.is_compiled_frame(), "what?");
2122 if (caller_fr.is_deoptimized_frame()) {
2123 log_info(exceptions)("deferred async exception at compiled safepoint");
2124 return;
2125 }
2126 }
2127 }
2128
2129 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2130 if (condition == _no_async_condition) {
2131 // Conditions have changed since has_special_runtime_exit_condition()
2132 // was called:
2133 // - if we were here only because of an external suspend request,
2134 // then that was taken care of above (or cancelled) so we are done
2135 // - if we were here because of another async request, then it has
2136 // been cleared between the has_special_runtime_exit_condition()
2137 // and now so again we are done
2138 return;
2139 }
2140
2141 // Check for pending async. exception
2142 if (_pending_async_exception != NULL) {
2143 // Only overwrite an already pending exception, if it is not a threadDeath.
2144 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2145
2146 // We cannot call Exceptions::_throw(...) here because we cannot block
2147 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2148
2149 LogTarget(Info, exceptions) lt;
2150 if (lt.is_enabled()) {
2151 ResourceMark rm;
2152 LogStream ls(lt);
2153 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2154 if (has_last_Java_frame()) {
2155 frame f = last_frame();
2156 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2157 }
2158 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2159 }
2160 _pending_async_exception = NULL;
2161 clear_has_async_exception();
2162 }
2163 }
2164
2165 if (check_unsafe_error &&
2166 condition == _async_unsafe_access_error && !has_pending_exception()) {
2167 condition = _no_async_condition; // done
2168 switch (thread_state()) {
2169 case _thread_in_vm: {
2170 JavaThread* THREAD = this;
2171 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2172 }
2173 case _thread_in_native: {
2174 ThreadInVMfromNative tiv(this);
2175 JavaThread* THREAD = this;
2176 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2177 }
2178 case _thread_in_Java: {
2179 ThreadInVMfromJava tiv(this);
2180 JavaThread* THREAD = this;
2181 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2182 }
2183 default:
2184 ShouldNotReachHere();
2185 }
2186 }
2187
2188 assert(condition == _no_async_condition || has_pending_exception() ||
2189 (!check_unsafe_error && condition == _async_unsafe_access_error),
2190 "must have handled the async condition, if no exception");
2191 }
2192
2193 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2194 //
2195 // Check for pending external suspend. Internal suspend requests do
2196 // not use handle_special_runtime_exit_condition().
2197 // If JNIEnv proxies are allowed, don't self-suspend if the target
2198 // thread is not the current thread. In older versions of jdbx, jdbx
2199 // threads could call into the VM with another thread's JNIEnv so we
2200 // can be here operating on behalf of a suspended thread (4432884).
2201 bool do_self_suspend = is_external_suspend_with_lock();
2202 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2203 //
2204 // Because thread is external suspended the safepoint code will count
2205 // thread as at a safepoint. This can be odd because we can be here
2206 // as _thread_in_Java which would normally transition to _thread_blocked
2207 // at a safepoint. We would like to mark the thread as _thread_blocked
2208 // before calling java_suspend_self like all other callers of it but
2209 // we must then observe proper safepoint protocol. (We can't leave
2210 // _thread_blocked with a safepoint in progress). However we can be
2211 // here as _thread_in_native_trans so we can't use a normal transition
2212 // constructor/destructor pair because they assert on that type of
2213 // transition. We could do something like:
2214 //
2215 // JavaThreadState state = thread_state();
2216 // set_thread_state(_thread_in_vm);
2217 // {
2218 // ThreadBlockInVM tbivm(this);
2219 // java_suspend_self()
2220 // }
2221 // set_thread_state(_thread_in_vm_trans);
2222 // if (safepoint) block;
2223 // set_thread_state(state);
2224 //
2225 // but that is pretty messy. Instead we just go with the way the
2226 // code has worked before and note that this is the only path to
2227 // java_suspend_self that doesn't put the thread in _thread_blocked
2228 // mode.
2229
2230 frame_anchor()->make_walkable(this);
2231 java_suspend_self();
2232
2233 // We might be here for reasons in addition to the self-suspend request
2234 // so check for other async requests.
2235 }
2236
2237 if (check_asyncs) {
2238 check_and_handle_async_exceptions();
2239 }
2240
2241 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2242 }
2243
2244 void JavaThread::send_thread_stop(oop java_throwable) {
2245 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2246 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2247 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2248
2249 // Do not throw asynchronous exceptions against the compiler thread
2250 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2251 if (!can_call_java()) return;
2252
2253 {
2254 // Actually throw the Throwable against the target Thread - however
2255 // only if there is no thread death exception installed already.
2256 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2257 // If the topmost frame is a runtime stub, then we are calling into
2258 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2259 // must deoptimize the caller before continuing, as the compiled exception handler table
2260 // may not be valid
2261 if (has_last_Java_frame()) {
2262 frame f = last_frame();
2263 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2264 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2265 RegisterMap reg_map(this, UseBiasedLocking);
2266 frame compiled_frame = f.sender(®_map);
2267 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2268 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2269 }
2270 }
2271 }
2272
2273 // Set async. pending exception in thread.
2274 set_pending_async_exception(java_throwable);
2275
2276 if (log_is_enabled(Info, exceptions)) {
2277 ResourceMark rm;
2278 log_info(exceptions)("Pending Async. exception installed of type: %s",
2279 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2280 }
2281 // for AbortVMOnException flag
2282 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2283 }
2284 }
2285
2286
2287 // Interrupt thread so it will wake up from a potential wait()
2288 Thread::interrupt(this);
2289 }
2290
2291 // External suspension mechanism.
2292 //
2293 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2294 // to any VM_locks and it is at a transition
2295 // Self-suspension will happen on the transition out of the vm.
2296 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2297 //
2298 // Guarantees on return:
2299 // + Target thread will not execute any new bytecode (that's why we need to
2300 // force a safepoint)
2301 // + Target thread will not enter any new monitors
2302 //
2303 void JavaThread::java_suspend() {
2304 ThreadsListHandle tlh;
2305 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2306 return;
2307 }
2308
2309 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2310 if (!is_external_suspend()) {
2311 // a racing resume has cancelled us; bail out now
2312 return;
2313 }
2314
2315 // suspend is done
2316 uint32_t debug_bits = 0;
2317 // Warning: is_ext_suspend_completed() may temporarily drop the
2318 // SR_lock to allow the thread to reach a stable thread state if
2319 // it is currently in a transient thread state.
2320 if (is_ext_suspend_completed(false /* !called_by_wait */,
2321 SuspendRetryDelay, &debug_bits)) {
2322 return;
2323 }
2324 }
2325
2326 VM_ThreadSuspend vm_suspend;
2327 VMThread::execute(&vm_suspend);
2328 }
2329
2330 // Part II of external suspension.
2331 // A JavaThread self suspends when it detects a pending external suspend
2332 // request. This is usually on transitions. It is also done in places
2333 // where continuing to the next transition would surprise the caller,
2334 // e.g., monitor entry.
2335 //
2336 // Returns the number of times that the thread self-suspended.
2337 //
2338 // Note: DO NOT call java_suspend_self() when you just want to block current
2339 // thread. java_suspend_self() is the second stage of cooperative
2340 // suspension for external suspend requests and should only be used
2341 // to complete an external suspend request.
2342 //
2343 int JavaThread::java_suspend_self() {
2344 int ret = 0;
2345
2346 // we are in the process of exiting so don't suspend
2347 if (is_exiting()) {
2348 clear_external_suspend();
2349 return ret;
2350 }
2351
2352 assert(_anchor.walkable() ||
2353 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2354 "must have walkable stack");
2355
2356 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2357
2358 assert(!this->is_ext_suspended(),
2359 "a thread trying to self-suspend should not already be suspended");
2360
2361 if (this->is_suspend_equivalent()) {
2362 // If we are self-suspending as a result of the lifting of a
2363 // suspend equivalent condition, then the suspend_equivalent
2364 // flag is not cleared until we set the ext_suspended flag so
2365 // that wait_for_ext_suspend_completion() returns consistent
2366 // results.
2367 this->clear_suspend_equivalent();
2368 }
2369
2370 // A racing resume may have cancelled us before we grabbed SR_lock
2371 // above. Or another external suspend request could be waiting for us
2372 // by the time we return from SR_lock()->wait(). The thread
2373 // that requested the suspension may already be trying to walk our
2374 // stack and if we return now, we can change the stack out from under
2375 // it. This would be a "bad thing (TM)" and cause the stack walker
2376 // to crash. We stay self-suspended until there are no more pending
2377 // external suspend requests.
2378 while (is_external_suspend()) {
2379 ret++;
2380 this->set_ext_suspended();
2381
2382 // _ext_suspended flag is cleared by java_resume()
2383 while (is_ext_suspended()) {
2384 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2385 }
2386 }
2387
2388 return ret;
2389 }
2390
2391 #ifdef ASSERT
2392 // Verify the JavaThread has not yet been published in the Threads::list, and
2393 // hence doesn't need protection from concurrent access at this stage.
2394 void JavaThread::verify_not_published() {
2395 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2396 // since an unpublished JavaThread doesn't participate in the
2397 // Thread-SMR protocol for keeping a ThreadsList alive.
2398 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2399 }
2400 #endif
2401
2402 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2403 // progress or when _suspend_flags is non-zero.
2404 // Current thread needs to self-suspend if there is a suspend request and/or
2405 // block if a safepoint is in progress.
2406 // Async exception ISN'T checked.
2407 // Note only the ThreadInVMfromNative transition can call this function
2408 // directly and when thread state is _thread_in_native_trans
2409 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2410 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2411
2412 JavaThread *curJT = JavaThread::current();
2413 bool do_self_suspend = thread->is_external_suspend();
2414
2415 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2416
2417 // If JNIEnv proxies are allowed, don't self-suspend if the target
2418 // thread is not the current thread. In older versions of jdbx, jdbx
2419 // threads could call into the VM with another thread's JNIEnv so we
2420 // can be here operating on behalf of a suspended thread (4432884).
2421 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2422 JavaThreadState state = thread->thread_state();
2423
2424 // We mark this thread_blocked state as a suspend-equivalent so
2425 // that a caller to is_ext_suspend_completed() won't be confused.
2426 // The suspend-equivalent state is cleared by java_suspend_self().
2427 thread->set_suspend_equivalent();
2428
2429 // If the safepoint code sees the _thread_in_native_trans state, it will
2430 // wait until the thread changes to other thread state. There is no
2431 // guarantee on how soon we can obtain the SR_lock and complete the
2432 // self-suspend request. It would be a bad idea to let safepoint wait for
2433 // too long. Temporarily change the state to _thread_blocked to
2434 // let the VM thread know that this thread is ready for GC. The problem
2435 // of changing thread state is that safepoint could happen just after
2436 // java_suspend_self() returns after being resumed, and VM thread will
2437 // see the _thread_blocked state. We must check for safepoint
2438 // after restoring the state and make sure we won't leave while a safepoint
2439 // is in progress.
2440 thread->set_thread_state(_thread_blocked);
2441 thread->java_suspend_self();
2442 thread->set_thread_state(state);
2443
2444 InterfaceSupport::serialize_thread_state_with_handler(thread);
2445 }
2446
2447 SafepointMechanism::block_if_requested(curJT);
2448
2449 if (thread->is_deopt_suspend()) {
2450 thread->clear_deopt_suspend();
2451 RegisterMap map(thread, false);
2452 frame f = thread->last_frame();
2453 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2454 f = f.sender(&map);
2455 }
2456 if (f.id() == thread->must_deopt_id()) {
2457 thread->clear_must_deopt_id();
2458 f.deoptimize(thread);
2459 } else {
2460 fatal("missed deoptimization!");
2461 }
2462 }
2463
2464 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2465 }
2466
2467 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2468 // progress or when _suspend_flags is non-zero.
2469 // Current thread needs to self-suspend if there is a suspend request and/or
2470 // block if a safepoint is in progress.
2471 // Also check for pending async exception (not including unsafe access error).
2472 // Note only the native==>VM/Java barriers can call this function and when
2473 // thread state is _thread_in_native_trans.
2474 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2475 check_safepoint_and_suspend_for_native_trans(thread);
2476
2477 if (thread->has_async_exception()) {
2478 // We are in _thread_in_native_trans state, don't handle unsafe
2479 // access error since that may block.
2480 thread->check_and_handle_async_exceptions(false);
2481 }
2482 }
2483
2484 // This is a variant of the normal
2485 // check_special_condition_for_native_trans with slightly different
2486 // semantics for use by critical native wrappers. It does all the
2487 // normal checks but also performs the transition back into
2488 // thread_in_Java state. This is required so that critical natives
2489 // can potentially block and perform a GC if they are the last thread
2490 // exiting the GCLocker.
2491 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2492 check_special_condition_for_native_trans(thread);
2493
2494 // Finish the transition
2495 thread->set_thread_state(_thread_in_Java);
2496
2497 if (thread->do_critical_native_unlock()) {
2498 ThreadInVMfromJavaNoAsyncException tiv(thread);
2499 GCLocker::unlock_critical(thread);
2500 thread->clear_critical_native_unlock();
2501 }
2502 }
2503
2504 // We need to guarantee the Threads_lock here, since resumes are not
2505 // allowed during safepoint synchronization
2506 // Can only resume from an external suspension
2507 void JavaThread::java_resume() {
2508 assert_locked_or_safepoint(Threads_lock);
2509
2510 // Sanity check: thread is gone, has started exiting or the thread
2511 // was not externally suspended.
2512 ThreadsListHandle tlh;
2513 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2514 return;
2515 }
2516
2517 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2518
2519 clear_external_suspend();
2520
2521 if (is_ext_suspended()) {
2522 clear_ext_suspended();
2523 SR_lock()->notify_all();
2524 }
2525 }
2526
2527 size_t JavaThread::_stack_red_zone_size = 0;
2528 size_t JavaThread::_stack_yellow_zone_size = 0;
2529 size_t JavaThread::_stack_reserved_zone_size = 0;
2530 size_t JavaThread::_stack_shadow_zone_size = 0;
2531
2532 void JavaThread::create_stack_guard_pages() {
2533 if (!os::uses_stack_guard_pages() ||
2534 _stack_guard_state != stack_guard_unused ||
2535 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2536 log_info(os, thread)("Stack guard page creation for thread "
2537 UINTX_FORMAT " disabled", os::current_thread_id());
2538 return;
2539 }
2540 address low_addr = stack_end();
2541 size_t len = stack_guard_zone_size();
2542
2543 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2544 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2545
2546 int must_commit = os::must_commit_stack_guard_pages();
2547 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2548
2549 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2550 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2551 return;
2552 }
2553
2554 if (os::guard_memory((char *) low_addr, len)) {
2555 _stack_guard_state = stack_guard_enabled;
2556 } else {
2557 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2558 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2559 if (os::uncommit_memory((char *) low_addr, len)) {
2560 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2561 }
2562 return;
2563 }
2564
2565 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2566 PTR_FORMAT "-" PTR_FORMAT ".",
2567 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2568 }
2569
2570 void JavaThread::remove_stack_guard_pages() {
2571 assert(Thread::current() == this, "from different thread");
2572 if (_stack_guard_state == stack_guard_unused) return;
2573 address low_addr = stack_end();
2574 size_t len = stack_guard_zone_size();
2575
2576 if (os::must_commit_stack_guard_pages()) {
2577 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2578 _stack_guard_state = stack_guard_unused;
2579 } else {
2580 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2581 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2582 return;
2583 }
2584 } else {
2585 if (_stack_guard_state == stack_guard_unused) return;
2586 if (os::unguard_memory((char *) low_addr, len)) {
2587 _stack_guard_state = stack_guard_unused;
2588 } else {
2589 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2590 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2591 return;
2592 }
2593 }
2594
2595 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2596 PTR_FORMAT "-" PTR_FORMAT ".",
2597 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2598 }
2599
2600 void JavaThread::enable_stack_reserved_zone() {
2601 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2602 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2603
2604 // The base notation is from the stack's point of view, growing downward.
2605 // We need to adjust it to work correctly with guard_memory()
2606 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2607
2608 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2609 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2610
2611 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2612 _stack_guard_state = stack_guard_enabled;
2613 } else {
2614 warning("Attempt to guard stack reserved zone failed.");
2615 }
2616 enable_register_stack_guard();
2617 }
2618
2619 void JavaThread::disable_stack_reserved_zone() {
2620 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2621 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2622
2623 // Simply return if called for a thread that does not use guard pages.
2624 if (_stack_guard_state == stack_guard_unused) return;
2625
2626 // The base notation is from the stack's point of view, growing downward.
2627 // We need to adjust it to work correctly with guard_memory()
2628 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2629
2630 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2631 _stack_guard_state = stack_guard_reserved_disabled;
2632 } else {
2633 warning("Attempt to unguard stack reserved zone failed.");
2634 }
2635 disable_register_stack_guard();
2636 }
2637
2638 void JavaThread::enable_stack_yellow_reserved_zone() {
2639 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2640 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2641
2642 // The base notation is from the stacks point of view, growing downward.
2643 // We need to adjust it to work correctly with guard_memory()
2644 address base = stack_red_zone_base();
2645
2646 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2647 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2648
2649 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2650 _stack_guard_state = stack_guard_enabled;
2651 } else {
2652 warning("Attempt to guard stack yellow zone failed.");
2653 }
2654 enable_register_stack_guard();
2655 }
2656
2657 void JavaThread::disable_stack_yellow_reserved_zone() {
2658 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2659 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2660
2661 // Simply return if called for a thread that does not use guard pages.
2662 if (_stack_guard_state == stack_guard_unused) return;
2663
2664 // The base notation is from the stacks point of view, growing downward.
2665 // We need to adjust it to work correctly with guard_memory()
2666 address base = stack_red_zone_base();
2667
2668 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2669 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2670 } else {
2671 warning("Attempt to unguard stack yellow zone failed.");
2672 }
2673 disable_register_stack_guard();
2674 }
2675
2676 void JavaThread::enable_stack_red_zone() {
2677 // The base notation is from the stacks point of view, growing downward.
2678 // We need to adjust it to work correctly with guard_memory()
2679 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2680 address base = stack_red_zone_base() - stack_red_zone_size();
2681
2682 guarantee(base < stack_base(), "Error calculating stack red zone");
2683 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2684
2685 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2686 warning("Attempt to guard stack red zone failed.");
2687 }
2688 }
2689
2690 void JavaThread::disable_stack_red_zone() {
2691 // The base notation is from the stacks point of view, growing downward.
2692 // We need to adjust it to work correctly with guard_memory()
2693 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2694 address base = stack_red_zone_base() - stack_red_zone_size();
2695 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2696 warning("Attempt to unguard stack red zone failed.");
2697 }
2698 }
2699
2700 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2701 // ignore is there is no stack
2702 if (!has_last_Java_frame()) return;
2703 // traverse the stack frames. Starts from top frame.
2704 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2705 frame* fr = fst.current();
2706 f(fr, fst.register_map());
2707 }
2708 }
2709
2710
2711 #ifndef PRODUCT
2712 // Deoptimization
2713 // Function for testing deoptimization
2714 void JavaThread::deoptimize() {
2715 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2716 StackFrameStream fst(this, UseBiasedLocking);
2717 bool deopt = false; // Dump stack only if a deopt actually happens.
2718 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2719 // Iterate over all frames in the thread and deoptimize
2720 for (; !fst.is_done(); fst.next()) {
2721 if (fst.current()->can_be_deoptimized()) {
2722
2723 if (only_at) {
2724 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2725 // consists of comma or carriage return separated numbers so
2726 // search for the current bci in that string.
2727 address pc = fst.current()->pc();
2728 nmethod* nm = (nmethod*) fst.current()->cb();
2729 ScopeDesc* sd = nm->scope_desc_at(pc);
2730 char buffer[8];
2731 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2732 size_t len = strlen(buffer);
2733 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2734 while (found != NULL) {
2735 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2736 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2737 // Check that the bci found is bracketed by terminators.
2738 break;
2739 }
2740 found = strstr(found + 1, buffer);
2741 }
2742 if (!found) {
2743 continue;
2744 }
2745 }
2746
2747 if (DebugDeoptimization && !deopt) {
2748 deopt = true; // One-time only print before deopt
2749 tty->print_cr("[BEFORE Deoptimization]");
2750 trace_frames();
2751 trace_stack();
2752 }
2753 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2754 }
2755 }
2756
2757 if (DebugDeoptimization && deopt) {
2758 tty->print_cr("[AFTER Deoptimization]");
2759 trace_frames();
2760 }
2761 }
2762
2763
2764 // Make zombies
2765 void JavaThread::make_zombies() {
2766 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2767 if (fst.current()->can_be_deoptimized()) {
2768 // it is a Java nmethod
2769 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2770 nm->make_not_entrant();
2771 }
2772 }
2773 }
2774 #endif // PRODUCT
2775
2776
2777 void JavaThread::deoptimized_wrt_marked_nmethods() {
2778 if (!has_last_Java_frame()) return;
2779 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2780 StackFrameStream fst(this, UseBiasedLocking);
2781 for (; !fst.is_done(); fst.next()) {
2782 if (fst.current()->should_be_deoptimized()) {
2783 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2784 }
2785 }
2786 }
2787
2788
2789 // If the caller is a NamedThread, then remember, in the current scope,
2790 // the given JavaThread in its _processed_thread field.
2791 class RememberProcessedThread: public StackObj {
2792 NamedThread* _cur_thr;
2793 public:
2794 RememberProcessedThread(JavaThread* jthr) {
2795 Thread* thread = Thread::current();
2796 if (thread->is_Named_thread()) {
2797 _cur_thr = (NamedThread *)thread;
2798 _cur_thr->set_processed_thread(jthr);
2799 } else {
2800 _cur_thr = NULL;
2801 }
2802 }
2803
2804 ~RememberProcessedThread() {
2805 if (_cur_thr) {
2806 _cur_thr->set_processed_thread(NULL);
2807 }
2808 }
2809 };
2810
2811 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2812 // Verify that the deferred card marks have been flushed.
2813 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2814
2815 // Traverse the GCHandles
2816 Thread::oops_do(f, cf);
2817
2818 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2819 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2820
2821 if (has_last_Java_frame()) {
2822 // Record JavaThread to GC thread
2823 RememberProcessedThread rpt(this);
2824
2825 // traverse the registered growable array
2826 if (_array_for_gc != NULL) {
2827 for (int index = 0; index < _array_for_gc->length(); index++) {
2828 f->do_oop(_array_for_gc->adr_at(index));
2829 }
2830 }
2831
2832 // Traverse the monitor chunks
2833 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2834 chunk->oops_do(f);
2835 }
2836
2837 // Traverse the execution stack
2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2839 fst.current()->oops_do(f, cf, fst.register_map());
2840 }
2841 }
2842
2843 // callee_target is never live across a gc point so NULL it here should
2844 // it still contain a methdOop.
2845
2846 set_callee_target(NULL);
2847
2848 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2849 // If we have deferred set_locals there might be oops waiting to be
2850 // written
2851 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2852 if (list != NULL) {
2853 for (int i = 0; i < list->length(); i++) {
2854 list->at(i)->oops_do(f);
2855 }
2856 }
2857
2858 // Traverse instance variables at the end since the GC may be moving things
2859 // around using this function
2860 f->do_oop((oop*) &_threadObj);
2861 f->do_oop((oop*) &_vm_result);
2862 f->do_oop((oop*) &_exception_oop);
2863 f->do_oop((oop*) &_pending_async_exception);
2864
2865 if (jvmti_thread_state() != NULL) {
2866 jvmti_thread_state()->oops_do(f);
2867 }
2868 }
2869
2870 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2871 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2872 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2873
2874 if (has_last_Java_frame()) {
2875 // Traverse the execution stack
2876 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2877 fst.current()->nmethods_do(cf);
2878 }
2879 }
2880 }
2881
2882 void JavaThread::metadata_do(void f(Metadata*)) {
2883 if (has_last_Java_frame()) {
2884 // Traverse the execution stack to call f() on the methods in the stack
2885 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2886 fst.current()->metadata_do(f);
2887 }
2888 } else if (is_Compiler_thread()) {
2889 // need to walk ciMetadata in current compile tasks to keep alive.
2890 CompilerThread* ct = (CompilerThread*)this;
2891 if (ct->env() != NULL) {
2892 ct->env()->metadata_do(f);
2893 }
2894 CompileTask* task = ct->task();
2895 if (task != NULL) {
2896 task->metadata_do(f);
2897 }
2898 }
2899 }
2900
2901 // Printing
2902 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2903 switch (_thread_state) {
2904 case _thread_uninitialized: return "_thread_uninitialized";
2905 case _thread_new: return "_thread_new";
2906 case _thread_new_trans: return "_thread_new_trans";
2907 case _thread_in_native: return "_thread_in_native";
2908 case _thread_in_native_trans: return "_thread_in_native_trans";
2909 case _thread_in_vm: return "_thread_in_vm";
2910 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2911 case _thread_in_Java: return "_thread_in_Java";
2912 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2913 case _thread_blocked: return "_thread_blocked";
2914 case _thread_blocked_trans: return "_thread_blocked_trans";
2915 default: return "unknown thread state";
2916 }
2917 }
2918
2919 #ifndef PRODUCT
2920 void JavaThread::print_thread_state_on(outputStream *st) const {
2921 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2922 };
2923 void JavaThread::print_thread_state() const {
2924 print_thread_state_on(tty);
2925 }
2926 #endif // PRODUCT
2927
2928 // Called by Threads::print() for VM_PrintThreads operation
2929 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
2930 st->print_raw("\"");
2931 st->print_raw(get_thread_name());
2932 st->print_raw("\" ");
2933 oop thread_oop = threadObj();
2934 if (thread_oop != NULL) {
2935 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2936 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2937 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2938 }
2939 Thread::print_on(st, print_extended_info);
2940 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2941 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2942 if (thread_oop != NULL) {
2943 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2944 }
2945 #ifndef PRODUCT
2946 _safepoint_state->print_on(st);
2947 #endif // PRODUCT
2948 if (is_Compiler_thread()) {
2949 CompileTask *task = ((CompilerThread*)this)->task();
2950 if (task != NULL) {
2951 st->print(" Compiling: ");
2952 task->print(st, NULL, true, false);
2953 } else {
2954 st->print(" No compile task");
2955 }
2956 st->cr();
2957 }
2958 }
2959
2960 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2961 st->print("%s", get_thread_name_string(buf, buflen));
2962 }
2963
2964 // Called by fatal error handler. The difference between this and
2965 // JavaThread::print() is that we can't grab lock or allocate memory.
2966 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2967 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2968 oop thread_obj = threadObj();
2969 if (thread_obj != NULL) {
2970 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2971 }
2972 st->print(" [");
2973 st->print("%s", _get_thread_state_name(_thread_state));
2974 if (osthread()) {
2975 st->print(", id=%d", osthread()->thread_id());
2976 }
2977 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2978 p2i(stack_end()), p2i(stack_base()));
2979 st->print("]");
2980
2981 ThreadsSMRSupport::print_info_on(this, st);
2982 return;
2983 }
2984
2985 // Verification
2986
2987 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2988
2989 void JavaThread::verify() {
2990 // Verify oops in the thread.
2991 oops_do(&VerifyOopClosure::verify_oop, NULL);
2992
2993 // Verify the stack frames.
2994 frames_do(frame_verify);
2995 }
2996
2997 // CR 6300358 (sub-CR 2137150)
2998 // Most callers of this method assume that it can't return NULL but a
2999 // thread may not have a name whilst it is in the process of attaching to
3000 // the VM - see CR 6412693, and there are places where a JavaThread can be
3001 // seen prior to having it's threadObj set (eg JNI attaching threads and
3002 // if vm exit occurs during initialization). These cases can all be accounted
3003 // for such that this method never returns NULL.
3004 const char* JavaThread::get_thread_name() const {
3005 #ifdef ASSERT
3006 // early safepoints can hit while current thread does not yet have TLS
3007 if (!SafepointSynchronize::is_at_safepoint()) {
3008 Thread *cur = Thread::current();
3009 if (!(cur->is_Java_thread() && cur == this)) {
3010 // Current JavaThreads are allowed to get their own name without
3011 // the Threads_lock.
3012 assert_locked_or_safepoint(Threads_lock);
3013 }
3014 }
3015 #endif // ASSERT
3016 return get_thread_name_string();
3017 }
3018
3019 // Returns a non-NULL representation of this thread's name, or a suitable
3020 // descriptive string if there is no set name
3021 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3022 const char* name_str;
3023 oop thread_obj = threadObj();
3024 if (thread_obj != NULL) {
3025 oop name = java_lang_Thread::name(thread_obj);
3026 if (name != NULL) {
3027 if (buf == NULL) {
3028 name_str = java_lang_String::as_utf8_string(name);
3029 } else {
3030 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3031 }
3032 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3033 name_str = "<no-name - thread is attaching>";
3034 } else {
3035 name_str = Thread::name();
3036 }
3037 } else {
3038 name_str = Thread::name();
3039 }
3040 assert(name_str != NULL, "unexpected NULL thread name");
3041 return name_str;
3042 }
3043
3044
3045 const char* JavaThread::get_threadgroup_name() const {
3046 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3047 oop thread_obj = threadObj();
3048 if (thread_obj != NULL) {
3049 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3050 if (thread_group != NULL) {
3051 // ThreadGroup.name can be null
3052 return java_lang_ThreadGroup::name(thread_group);
3053 }
3054 }
3055 return NULL;
3056 }
3057
3058 const char* JavaThread::get_parent_name() const {
3059 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3060 oop thread_obj = threadObj();
3061 if (thread_obj != NULL) {
3062 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3063 if (thread_group != NULL) {
3064 oop parent = java_lang_ThreadGroup::parent(thread_group);
3065 if (parent != NULL) {
3066 // ThreadGroup.name can be null
3067 return java_lang_ThreadGroup::name(parent);
3068 }
3069 }
3070 }
3071 return NULL;
3072 }
3073
3074 ThreadPriority JavaThread::java_priority() const {
3075 oop thr_oop = threadObj();
3076 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3077 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3078 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3079 return priority;
3080 }
3081
3082 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3083
3084 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3085 // Link Java Thread object <-> C++ Thread
3086
3087 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3088 // and put it into a new Handle. The Handle "thread_oop" can then
3089 // be used to pass the C++ thread object to other methods.
3090
3091 // Set the Java level thread object (jthread) field of the
3092 // new thread (a JavaThread *) to C++ thread object using the
3093 // "thread_oop" handle.
3094
3095 // Set the thread field (a JavaThread *) of the
3096 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3097
3098 Handle thread_oop(Thread::current(),
3099 JNIHandles::resolve_non_null(jni_thread));
3100 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3101 "must be initialized");
3102 set_threadObj(thread_oop());
3103 java_lang_Thread::set_thread(thread_oop(), this);
3104
3105 if (prio == NoPriority) {
3106 prio = java_lang_Thread::priority(thread_oop());
3107 assert(prio != NoPriority, "A valid priority should be present");
3108 }
3109
3110 // Push the Java priority down to the native thread; needs Threads_lock
3111 Thread::set_priority(this, prio);
3112
3113 // Add the new thread to the Threads list and set it in motion.
3114 // We must have threads lock in order to call Threads::add.
3115 // It is crucial that we do not block before the thread is
3116 // added to the Threads list for if a GC happens, then the java_thread oop
3117 // will not be visited by GC.
3118 Threads::add(this);
3119 }
3120
3121 oop JavaThread::current_park_blocker() {
3122 // Support for JSR-166 locks
3123 oop thread_oop = threadObj();
3124 if (thread_oop != NULL &&
3125 JDK_Version::current().supports_thread_park_blocker()) {
3126 return java_lang_Thread::park_blocker(thread_oop);
3127 }
3128 return NULL;
3129 }
3130
3131
3132 void JavaThread::print_stack_on(outputStream* st) {
3133 if (!has_last_Java_frame()) return;
3134 ResourceMark rm;
3135 HandleMark hm;
3136
3137 RegisterMap reg_map(this);
3138 vframe* start_vf = last_java_vframe(®_map);
3139 int count = 0;
3140 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3141 if (f->is_java_frame()) {
3142 javaVFrame* jvf = javaVFrame::cast(f);
3143 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3144
3145 // Print out lock information
3146 if (JavaMonitorsInStackTrace) {
3147 jvf->print_lock_info_on(st, count);
3148 }
3149 } else {
3150 // Ignore non-Java frames
3151 }
3152
3153 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3154 count++;
3155 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3156 }
3157 }
3158
3159
3160 // JVMTI PopFrame support
3161 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3162 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3163 if (in_bytes(size_in_bytes) != 0) {
3164 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3165 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3166 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3167 }
3168 }
3169
3170 void* JavaThread::popframe_preserved_args() {
3171 return _popframe_preserved_args;
3172 }
3173
3174 ByteSize JavaThread::popframe_preserved_args_size() {
3175 return in_ByteSize(_popframe_preserved_args_size);
3176 }
3177
3178 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3179 int sz = in_bytes(popframe_preserved_args_size());
3180 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3181 return in_WordSize(sz / wordSize);
3182 }
3183
3184 void JavaThread::popframe_free_preserved_args() {
3185 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3186 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3187 _popframe_preserved_args = NULL;
3188 _popframe_preserved_args_size = 0;
3189 }
3190
3191 #ifndef PRODUCT
3192
3193 void JavaThread::trace_frames() {
3194 tty->print_cr("[Describe stack]");
3195 int frame_no = 1;
3196 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3197 tty->print(" %d. ", frame_no++);
3198 fst.current()->print_value_on(tty, this);
3199 tty->cr();
3200 }
3201 }
3202
3203 class PrintAndVerifyOopClosure: public OopClosure {
3204 protected:
3205 template <class T> inline void do_oop_work(T* p) {
3206 oop obj = RawAccess<>::oop_load(p);
3207 if (obj == NULL) return;
3208 tty->print(INTPTR_FORMAT ": ", p2i(p));
3209 if (oopDesc::is_oop_or_null(obj)) {
3210 if (obj->is_objArray()) {
3211 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3212 } else {
3213 obj->print();
3214 }
3215 } else {
3216 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3217 }
3218 tty->cr();
3219 }
3220 public:
3221 virtual void do_oop(oop* p) { do_oop_work(p); }
3222 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3223 };
3224
3225
3226 static void oops_print(frame* f, const RegisterMap *map) {
3227 PrintAndVerifyOopClosure print;
3228 f->print_value();
3229 f->oops_do(&print, NULL, (RegisterMap*)map);
3230 }
3231
3232 // Print our all the locations that contain oops and whether they are
3233 // valid or not. This useful when trying to find the oldest frame
3234 // where an oop has gone bad since the frame walk is from youngest to
3235 // oldest.
3236 void JavaThread::trace_oops() {
3237 tty->print_cr("[Trace oops]");
3238 frames_do(oops_print);
3239 }
3240
3241
3242 #ifdef ASSERT
3243 // Print or validate the layout of stack frames
3244 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3245 ResourceMark rm;
3246 PRESERVE_EXCEPTION_MARK;
3247 FrameValues values;
3248 int frame_no = 0;
3249 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3250 fst.current()->describe(values, ++frame_no);
3251 if (depth == frame_no) break;
3252 }
3253 if (validate_only) {
3254 values.validate();
3255 } else {
3256 tty->print_cr("[Describe stack layout]");
3257 values.print(this);
3258 }
3259 }
3260 #endif
3261
3262 void JavaThread::trace_stack_from(vframe* start_vf) {
3263 ResourceMark rm;
3264 int vframe_no = 1;
3265 for (vframe* f = start_vf; f; f = f->sender()) {
3266 if (f->is_java_frame()) {
3267 javaVFrame::cast(f)->print_activation(vframe_no++);
3268 } else {
3269 f->print();
3270 }
3271 if (vframe_no > StackPrintLimit) {
3272 tty->print_cr("...<more frames>...");
3273 return;
3274 }
3275 }
3276 }
3277
3278
3279 void JavaThread::trace_stack() {
3280 if (!has_last_Java_frame()) return;
3281 ResourceMark rm;
3282 HandleMark hm;
3283 RegisterMap reg_map(this);
3284 trace_stack_from(last_java_vframe(®_map));
3285 }
3286
3287
3288 #endif // PRODUCT
3289
3290
3291 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3292 assert(reg_map != NULL, "a map must be given");
3293 frame f = last_frame();
3294 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3295 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3296 }
3297 return NULL;
3298 }
3299
3300
3301 Klass* JavaThread::security_get_caller_class(int depth) {
3302 vframeStream vfst(this);
3303 vfst.security_get_caller_frame(depth);
3304 if (!vfst.at_end()) {
3305 return vfst.method()->method_holder();
3306 }
3307 return NULL;
3308 }
3309
3310 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3311 assert(thread->is_Compiler_thread(), "must be compiler thread");
3312 CompileBroker::compiler_thread_loop();
3313 }
3314
3315 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3316 NMethodSweeper::sweeper_loop();
3317 }
3318
3319 // Create a CompilerThread
3320 CompilerThread::CompilerThread(CompileQueue* queue,
3321 CompilerCounters* counters)
3322 : JavaThread(&compiler_thread_entry) {
3323 _env = NULL;
3324 _log = NULL;
3325 _task = NULL;
3326 _queue = queue;
3327 _counters = counters;
3328 _buffer_blob = NULL;
3329 _compiler = NULL;
3330
3331 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3332 resource_area()->bias_to(mtCompiler);
3333
3334 #ifndef PRODUCT
3335 _ideal_graph_printer = NULL;
3336 #endif
3337 }
3338
3339 CompilerThread::~CompilerThread() {
3340 // Delete objects which were allocated on heap.
3341 delete _counters;
3342 }
3343
3344 bool CompilerThread::can_call_java() const {
3345 return _compiler != NULL && _compiler->is_jvmci();
3346 }
3347
3348 // Create sweeper thread
3349 CodeCacheSweeperThread::CodeCacheSweeperThread()
3350 : JavaThread(&sweeper_thread_entry) {
3351 _scanned_compiled_method = NULL;
3352 }
3353
3354 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3355 JavaThread::oops_do(f, cf);
3356 if (_scanned_compiled_method != NULL && cf != NULL) {
3357 // Safepoints can occur when the sweeper is scanning an nmethod so
3358 // process it here to make sure it isn't unloaded in the middle of
3359 // a scan.
3360 cf->do_code_blob(_scanned_compiled_method);
3361 }
3362 }
3363
3364 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3365 JavaThread::nmethods_do(cf);
3366 if (_scanned_compiled_method != NULL && cf != NULL) {
3367 // Safepoints can occur when the sweeper is scanning an nmethod so
3368 // process it here to make sure it isn't unloaded in the middle of
3369 // a scan.
3370 cf->do_code_blob(_scanned_compiled_method);
3371 }
3372 }
3373
3374
3375 // ======= Threads ========
3376
3377 // The Threads class links together all active threads, and provides
3378 // operations over all threads. It is protected by the Threads_lock,
3379 // which is also used in other global contexts like safepointing.
3380 // ThreadsListHandles are used to safely perform operations on one
3381 // or more threads without the risk of the thread exiting during the
3382 // operation.
3383 //
3384 // Note: The Threads_lock is currently more widely used than we
3385 // would like. We are actively migrating Threads_lock uses to other
3386 // mechanisms in order to reduce Threads_lock contention.
3387
3388 JavaThread* Threads::_thread_list = NULL;
3389 int Threads::_number_of_threads = 0;
3390 int Threads::_number_of_non_daemon_threads = 0;
3391 int Threads::_return_code = 0;
3392 int Threads::_thread_claim_parity = 0;
3393 size_t JavaThread::_stack_size_at_create = 0;
3394
3395 #ifdef ASSERT
3396 bool Threads::_vm_complete = false;
3397 size_t Threads::_threads_before_barrier_set = 0;
3398 #endif
3399
3400 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3401 Prefetch::read((void*)addr, prefetch_interval);
3402 return *addr;
3403 }
3404
3405 // Possibly the ugliest for loop the world has seen. C++ does not allow
3406 // multiple types in the declaration section of the for loop. In this case
3407 // we are only dealing with pointers and hence can cast them. It looks ugly
3408 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3409 #define DO_JAVA_THREADS(LIST, X) \
3410 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3411 *MACRO_list = (JavaThread*)(LIST), \
3412 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3413 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3414 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3415 MACRO_current_p != MACRO_end; \
3416 MACRO_current_p++, \
3417 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3418
3419 // All JavaThreads
3420 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3421
3422 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3423 void Threads::non_java_threads_do(ThreadClosure* tc) {
3424 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3425 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3426 tc->do_thread(njti.current());
3427 }
3428 }
3429
3430 // All JavaThreads
3431 void Threads::java_threads_do(ThreadClosure* tc) {
3432 assert_locked_or_safepoint(Threads_lock);
3433 // ALL_JAVA_THREADS iterates through all JavaThreads.
3434 ALL_JAVA_THREADS(p) {
3435 tc->do_thread(p);
3436 }
3437 }
3438
3439 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3440 assert_locked_or_safepoint(Threads_lock);
3441 java_threads_do(tc);
3442 tc->do_thread(VMThread::vm_thread());
3443 }
3444
3445 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3446 void Threads::threads_do(ThreadClosure* tc) {
3447 assert_locked_or_safepoint(Threads_lock);
3448 java_threads_do(tc);
3449 non_java_threads_do(tc);
3450 }
3451
3452 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3453 int cp = Threads::thread_claim_parity();
3454 ALL_JAVA_THREADS(p) {
3455 if (p->claim_oops_do(is_par, cp)) {
3456 tc->do_thread(p);
3457 }
3458 }
3459 VMThread* vmt = VMThread::vm_thread();
3460 if (vmt->claim_oops_do(is_par, cp)) {
3461 tc->do_thread(vmt);
3462 }
3463 }
3464
3465 // The system initialization in the library has three phases.
3466 //
3467 // Phase 1: java.lang.System class initialization
3468 // java.lang.System is a primordial class loaded and initialized
3469 // by the VM early during startup. java.lang.System.<clinit>
3470 // only does registerNatives and keeps the rest of the class
3471 // initialization work later until thread initialization completes.
3472 //
3473 // System.initPhase1 initializes the system properties, the static
3474 // fields in, out, and err. Set up java signal handlers, OS-specific
3475 // system settings, and thread group of the main thread.
3476 static void call_initPhase1(TRAPS) {
3477 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3478 JavaValue result(T_VOID);
3479 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3480 vmSymbols::void_method_signature(), CHECK);
3481 }
3482
3483 // Phase 2. Module system initialization
3484 // This will initialize the module system. Only java.base classes
3485 // can be loaded until phase 2 completes.
3486 //
3487 // Call System.initPhase2 after the compiler initialization and jsr292
3488 // classes get initialized because module initialization runs a lot of java
3489 // code, that for performance reasons, should be compiled. Also, this will
3490 // enable the startup code to use lambda and other language features in this
3491 // phase and onward.
3492 //
3493 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3494 static void call_initPhase2(TRAPS) {
3495 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3496
3497 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3498
3499 JavaValue result(T_INT);
3500 JavaCallArguments args;
3501 args.push_int(DisplayVMOutputToStderr);
3502 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3503 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3504 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3505 if (result.get_jint() != JNI_OK) {
3506 vm_exit_during_initialization(); // no message or exception
3507 }
3508
3509 universe_post_module_init();
3510 }
3511
3512 // Phase 3. final setup - set security manager, system class loader and TCCL
3513 //
3514 // This will instantiate and set the security manager, set the system class
3515 // loader as well as the thread context class loader. The security manager
3516 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3517 // other modules or the application's classpath.
3518 static void call_initPhase3(TRAPS) {
3519 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3520 JavaValue result(T_VOID);
3521 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3522 vmSymbols::void_method_signature(), CHECK);
3523 }
3524
3525 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3526 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3527
3528 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3529 create_vm_init_libraries();
3530 }
3531
3532 initialize_class(vmSymbols::java_lang_String(), CHECK);
3533
3534 // Inject CompactStrings value after the static initializers for String ran.
3535 java_lang_String::set_compact_strings(CompactStrings);
3536
3537 // Initialize java_lang.System (needed before creating the thread)
3538 initialize_class(vmSymbols::java_lang_System(), CHECK);
3539 // The VM creates & returns objects of this class. Make sure it's initialized.
3540 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3541 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3542 Handle thread_group = create_initial_thread_group(CHECK);
3543 Universe::set_main_thread_group(thread_group());
3544 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3545 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3546 main_thread->set_threadObj(thread_object);
3547 // Set thread status to running since main thread has
3548 // been started and running.
3549 java_lang_Thread::set_thread_status(thread_object,
3550 java_lang_Thread::RUNNABLE);
3551
3552 // The VM creates objects of this class.
3553 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3554
3555 // The VM preresolves methods to these classes. Make sure that they get initialized
3556 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3557 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3558
3559 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3560 call_initPhase1(CHECK);
3561
3562 // get the Java runtime name after java.lang.System is initialized
3563 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3564 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3565
3566 // an instance of OutOfMemory exception has been allocated earlier
3567 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3568 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3569 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3570 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3571 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3572 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3573 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3574 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3575 }
3576
3577 void Threads::initialize_jsr292_core_classes(TRAPS) {
3578 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3579
3580 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3581 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3582 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3583 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3584 }
3585
3586 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3587 extern void JDK_Version_init();
3588
3589 // Preinitialize version info.
3590 VM_Version::early_initialize();
3591
3592 // Check version
3593 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3594
3595 // Initialize library-based TLS
3596 ThreadLocalStorage::init();
3597
3598 // Initialize the output stream module
3599 ostream_init();
3600
3601 // Process java launcher properties.
3602 Arguments::process_sun_java_launcher_properties(args);
3603
3604 // Initialize the os module
3605 os::init();
3606
3607 // Record VM creation timing statistics
3608 TraceVmCreationTime create_vm_timer;
3609 create_vm_timer.start();
3610
3611 // Initialize system properties.
3612 Arguments::init_system_properties();
3613
3614 // So that JDK version can be used as a discriminator when parsing arguments
3615 JDK_Version_init();
3616
3617 // Update/Initialize System properties after JDK version number is known
3618 Arguments::init_version_specific_system_properties();
3619
3620 // Make sure to initialize log configuration *before* parsing arguments
3621 LogConfiguration::initialize(create_vm_timer.begin_time());
3622
3623 // Parse arguments
3624 // Note: this internally calls os::init_container_support()
3625 jint parse_result = Arguments::parse(args);
3626 if (parse_result != JNI_OK) return parse_result;
3627
3628 os::init_before_ergo();
3629
3630 jint ergo_result = Arguments::apply_ergo();
3631 if (ergo_result != JNI_OK) return ergo_result;
3632
3633 // Final check of all ranges after ergonomics which may change values.
3634 if (!JVMFlagRangeList::check_ranges()) {
3635 return JNI_EINVAL;
3636 }
3637
3638 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3639 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3640 if (!constraint_result) {
3641 return JNI_EINVAL;
3642 }
3643
3644 JVMFlagWriteableList::mark_startup();
3645
3646 if (PauseAtStartup) {
3647 os::pause();
3648 }
3649
3650 HOTSPOT_VM_INIT_BEGIN();
3651
3652 // Timing (must come after argument parsing)
3653 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3654
3655 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3656 // Initialize assert poison page mechanism.
3657 if (ShowRegistersOnAssert) {
3658 initialize_assert_poison();
3659 }
3660 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3661
3662 // Initialize the os module after parsing the args
3663 jint os_init_2_result = os::init_2();
3664 if (os_init_2_result != JNI_OK) return os_init_2_result;
3665
3666 SafepointMechanism::initialize();
3667
3668 jint adjust_after_os_result = Arguments::adjust_after_os();
3669 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3670
3671 // Initialize output stream logging
3672 ostream_init_log();
3673
3674 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3675 // Must be before create_vm_init_agents()
3676 if (Arguments::init_libraries_at_startup()) {
3677 convert_vm_init_libraries_to_agents();
3678 }
3679
3680 // Launch -agentlib/-agentpath and converted -Xrun agents
3681 if (Arguments::init_agents_at_startup()) {
3682 create_vm_init_agents();
3683 }
3684
3685 // Initialize Threads state
3686 _thread_list = NULL;
3687 _number_of_threads = 0;
3688 _number_of_non_daemon_threads = 0;
3689
3690 // Initialize global data structures and create system classes in heap
3691 vm_init_globals();
3692
3693 #if INCLUDE_JVMCI
3694 if (JVMCICounterSize > 0) {
3695 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3696 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3697 } else {
3698 JavaThread::_jvmci_old_thread_counters = NULL;
3699 }
3700 #endif // INCLUDE_JVMCI
3701
3702 // Attach the main thread to this os thread
3703 JavaThread* main_thread = new JavaThread();
3704 main_thread->set_thread_state(_thread_in_vm);
3705 main_thread->initialize_thread_current();
3706 // must do this before set_active_handles
3707 main_thread->record_stack_base_and_size();
3708 main_thread->register_thread_stack_with_NMT();
3709 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3710
3711 if (!main_thread->set_as_starting_thread()) {
3712 vm_shutdown_during_initialization(
3713 "Failed necessary internal allocation. Out of swap space");
3714 main_thread->smr_delete();
3715 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3716 return JNI_ENOMEM;
3717 }
3718
3719 // Enable guard page *after* os::create_main_thread(), otherwise it would
3720 // crash Linux VM, see notes in os_linux.cpp.
3721 main_thread->create_stack_guard_pages();
3722
3723 // Initialize Java-Level synchronization subsystem
3724 ObjectMonitor::Initialize();
3725
3726 // Initialize global modules
3727 jint status = init_globals();
3728 if (status != JNI_OK) {
3729 main_thread->smr_delete();
3730 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3731 return status;
3732 }
3733
3734 JFR_ONLY(Jfr::on_vm_init();)
3735
3736 // Should be done after the heap is fully created
3737 main_thread->cache_global_variables();
3738
3739 HandleMark hm;
3740
3741 { MutexLocker mu(Threads_lock);
3742 Threads::add(main_thread);
3743 }
3744
3745 // Any JVMTI raw monitors entered in onload will transition into
3746 // real raw monitor. VM is setup enough here for raw monitor enter.
3747 JvmtiExport::transition_pending_onload_raw_monitors();
3748
3749 // Create the VMThread
3750 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3751
3752 VMThread::create();
3753 Thread* vmthread = VMThread::vm_thread();
3754
3755 if (!os::create_thread(vmthread, os::vm_thread)) {
3756 vm_exit_during_initialization("Cannot create VM thread. "
3757 "Out of system resources.");
3758 }
3759
3760 // Wait for the VM thread to become ready, and VMThread::run to initialize
3761 // Monitors can have spurious returns, must always check another state flag
3762 {
3763 MutexLocker ml(Notify_lock);
3764 os::start_thread(vmthread);
3765 while (vmthread->active_handles() == NULL) {
3766 Notify_lock->wait();
3767 }
3768 }
3769 }
3770
3771 assert(Universe::is_fully_initialized(), "not initialized");
3772 if (VerifyDuringStartup) {
3773 // Make sure we're starting with a clean slate.
3774 VM_Verify verify_op;
3775 VMThread::execute(&verify_op);
3776 }
3777
3778 // We need this to update the java.vm.info property in case any flags used
3779 // to initially define it have been changed. This is needed for both CDS and
3780 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3781 // is initially computed. See Abstract_VM_Version::vm_info_string().
3782 // This update must happen before we initialize the java classes, but
3783 // after any initialization logic that might modify the flags.
3784 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3785
3786 Thread* THREAD = Thread::current();
3787
3788 // Always call even when there are not JVMTI environments yet, since environments
3789 // may be attached late and JVMTI must track phases of VM execution
3790 JvmtiExport::enter_early_start_phase();
3791
3792 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3793 JvmtiExport::post_early_vm_start();
3794
3795 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3796
3797 quicken_jni_functions();
3798
3799 // No more stub generation allowed after that point.
3800 StubCodeDesc::freeze();
3801
3802 // Set flag that basic initialization has completed. Used by exceptions and various
3803 // debug stuff, that does not work until all basic classes have been initialized.
3804 set_init_completed();
3805
3806 LogConfiguration::post_initialize();
3807 Metaspace::post_initialize();
3808
3809 HOTSPOT_VM_INIT_END();
3810
3811 // record VM initialization completion time
3812 #if INCLUDE_MANAGEMENT
3813 Management::record_vm_init_completed();
3814 #endif // INCLUDE_MANAGEMENT
3815
3816 // Signal Dispatcher needs to be started before VMInit event is posted
3817 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3818
3819 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3820 if (!DisableAttachMechanism) {
3821 AttachListener::vm_start();
3822 if (StartAttachListener || AttachListener::init_at_startup()) {
3823 AttachListener::init();
3824 }
3825 }
3826
3827 // Launch -Xrun agents
3828 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3829 // back-end can launch with -Xdebug -Xrunjdwp.
3830 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3831 create_vm_init_libraries();
3832 }
3833
3834 if (CleanChunkPoolAsync) {
3835 Chunk::start_chunk_pool_cleaner_task();
3836 }
3837
3838 // initialize compiler(s)
3839 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3840 #if INCLUDE_JVMCI
3841 bool force_JVMCI_intialization = false;
3842 if (EnableJVMCI) {
3843 // Initialize JVMCI eagerly when it is explicitly requested.
3844 // Or when JVMCIPrintProperties is enabled.
3845 // The JVMCI Java initialization code will read this flag and
3846 // do the printing if it's set.
3847 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3848
3849 if (!force_JVMCI_intialization) {
3850 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3851 // compilations via JVMCI will not actually block until JVMCI is initialized.
3852 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3853 }
3854 }
3855 #endif
3856 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3857 // Postpone completion of compiler initialization to after JVMCI
3858 // is initialized to avoid timeouts of blocking compilations.
3859 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3860 CompileBroker::compilation_init_phase2();
3861 }
3862 #endif
3863
3864 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3865 // It is done after compilers are initialized, because otherwise compilations of
3866 // signature polymorphic MH intrinsics can be missed
3867 // (see SystemDictionary::find_method_handle_intrinsic).
3868 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3869
3870 // This will initialize the module system. Only java.base classes can be
3871 // loaded until phase 2 completes
3872 call_initPhase2(CHECK_JNI_ERR);
3873
3874 // Always call even when there are not JVMTI environments yet, since environments
3875 // may be attached late and JVMTI must track phases of VM execution
3876 JvmtiExport::enter_start_phase();
3877
3878 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3879 JvmtiExport::post_vm_start();
3880
3881 // Final system initialization including security manager and system class loader
3882 call_initPhase3(CHECK_JNI_ERR);
3883
3884 // cache the system and platform class loaders
3885 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3886
3887 #if INCLUDE_CDS
3888 if (DumpSharedSpaces) {
3889 // capture the module path info from the ModuleEntryTable
3890 ClassLoader::initialize_module_path(THREAD);
3891 }
3892 #endif
3893
3894 #if INCLUDE_JVMCI
3895 if (force_JVMCI_intialization) {
3896 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3897 CompileBroker::compilation_init_phase2();
3898 }
3899 #endif
3900
3901 // Always call even when there are not JVMTI environments yet, since environments
3902 // may be attached late and JVMTI must track phases of VM execution
3903 JvmtiExport::enter_live_phase();
3904
3905 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3906 JvmtiExport::post_vm_initialized();
3907
3908 JFR_ONLY(Jfr::on_vm_start();)
3909
3910 #if INCLUDE_MANAGEMENT
3911 Management::initialize(THREAD);
3912
3913 if (HAS_PENDING_EXCEPTION) {
3914 // management agent fails to start possibly due to
3915 // configuration problem and is responsible for printing
3916 // stack trace if appropriate. Simply exit VM.
3917 vm_exit(1);
3918 }
3919 #endif // INCLUDE_MANAGEMENT
3920
3921 if (MemProfiling) MemProfiler::engage();
3922 StatSampler::engage();
3923 if (CheckJNICalls) JniPeriodicChecker::engage();
3924
3925 BiasedLocking::init();
3926
3927 #if INCLUDE_RTM_OPT
3928 RTMLockingCounters::init();
3929 #endif
3930
3931 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3932 call_postVMInitHook(THREAD);
3933 // The Java side of PostVMInitHook.run must deal with all
3934 // exceptions and provide means of diagnosis.
3935 if (HAS_PENDING_EXCEPTION) {
3936 CLEAR_PENDING_EXCEPTION;
3937 }
3938 }
3939
3940 {
3941 MutexLocker ml(PeriodicTask_lock);
3942 // Make sure the WatcherThread can be started by WatcherThread::start()
3943 // or by dynamic enrollment.
3944 WatcherThread::make_startable();
3945 // Start up the WatcherThread if there are any periodic tasks
3946 // NOTE: All PeriodicTasks should be registered by now. If they
3947 // aren't, late joiners might appear to start slowly (we might
3948 // take a while to process their first tick).
3949 if (PeriodicTask::num_tasks() > 0) {
3950 WatcherThread::start();
3951 }
3952 }
3953
3954 create_vm_timer.end();
3955 #ifdef ASSERT
3956 _vm_complete = true;
3957 #endif
3958
3959 if (DumpSharedSpaces) {
3960 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3961 ShouldNotReachHere();
3962 }
3963
3964 return JNI_OK;
3965 }
3966
3967 // type for the Agent_OnLoad and JVM_OnLoad entry points
3968 extern "C" {
3969 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3970 }
3971 // Find a command line agent library and return its entry point for
3972 // -agentlib: -agentpath: -Xrun
3973 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3974 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3975 const char *on_load_symbols[],
3976 size_t num_symbol_entries) {
3977 OnLoadEntry_t on_load_entry = NULL;
3978 void *library = NULL;
3979
3980 if (!agent->valid()) {
3981 char buffer[JVM_MAXPATHLEN];
3982 char ebuf[1024] = "";
3983 const char *name = agent->name();
3984 const char *msg = "Could not find agent library ";
3985
3986 // First check to see if agent is statically linked into executable
3987 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3988 library = agent->os_lib();
3989 } else if (agent->is_absolute_path()) {
3990 library = os::dll_load(name, ebuf, sizeof ebuf);
3991 if (library == NULL) {
3992 const char *sub_msg = " in absolute path, with error: ";
3993 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3994 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3995 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3996 // If we can't find the agent, exit.
3997 vm_exit_during_initialization(buf, NULL);
3998 FREE_C_HEAP_ARRAY(char, buf);
3999 }
4000 } else {
4001 // Try to load the agent from the standard dll directory
4002 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4003 name)) {
4004 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4005 }
4006 if (library == NULL) { // Try the library path directory.
4007 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4008 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4009 }
4010 if (library == NULL) {
4011 const char *sub_msg = " on the library path, with error: ";
4012 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4013
4014 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4015 strlen(ebuf) + strlen(sub_msg2) + 1;
4016 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4017 if (!agent->is_instrument_lib()) {
4018 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4019 } else {
4020 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4021 }
4022 // If we can't find the agent, exit.
4023 vm_exit_during_initialization(buf, NULL);
4024 FREE_C_HEAP_ARRAY(char, buf);
4025 }
4026 }
4027 }
4028 agent->set_os_lib(library);
4029 agent->set_valid();
4030 }
4031
4032 // Find the OnLoad function.
4033 on_load_entry =
4034 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4035 false,
4036 on_load_symbols,
4037 num_symbol_entries));
4038 return on_load_entry;
4039 }
4040
4041 // Find the JVM_OnLoad entry point
4042 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4043 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4044 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4045 }
4046
4047 // Find the Agent_OnLoad entry point
4048 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4049 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4050 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4051 }
4052
4053 // For backwards compatibility with -Xrun
4054 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4055 // treated like -agentpath:
4056 // Must be called before agent libraries are created
4057 void Threads::convert_vm_init_libraries_to_agents() {
4058 AgentLibrary* agent;
4059 AgentLibrary* next;
4060
4061 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4062 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4063 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4064
4065 // If there is an JVM_OnLoad function it will get called later,
4066 // otherwise see if there is an Agent_OnLoad
4067 if (on_load_entry == NULL) {
4068 on_load_entry = lookup_agent_on_load(agent);
4069 if (on_load_entry != NULL) {
4070 // switch it to the agent list -- so that Agent_OnLoad will be called,
4071 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4072 Arguments::convert_library_to_agent(agent);
4073 } else {
4074 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4075 }
4076 }
4077 }
4078 }
4079
4080 // Create agents for -agentlib: -agentpath: and converted -Xrun
4081 // Invokes Agent_OnLoad
4082 // Called very early -- before JavaThreads exist
4083 void Threads::create_vm_init_agents() {
4084 extern struct JavaVM_ main_vm;
4085 AgentLibrary* agent;
4086
4087 JvmtiExport::enter_onload_phase();
4088
4089 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4090 // CDS dumping does not support native JVMTI agent.
4091 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4092 if (DumpSharedSpaces) {
4093 if(!agent->is_instrument_lib()) {
4094 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4095 } else if (!AllowArchivingWithJavaAgent) {
4096 vm_exit_during_cds_dumping(
4097 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4098 }
4099 }
4100
4101 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4102
4103 if (on_load_entry != NULL) {
4104 // Invoke the Agent_OnLoad function
4105 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4106 if (err != JNI_OK) {
4107 vm_exit_during_initialization("agent library failed to init", agent->name());
4108 }
4109 } else {
4110 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4111 }
4112 }
4113
4114 JvmtiExport::enter_primordial_phase();
4115 }
4116
4117 extern "C" {
4118 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4119 }
4120
4121 void Threads::shutdown_vm_agents() {
4122 // Send any Agent_OnUnload notifications
4123 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4124 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4125 extern struct JavaVM_ main_vm;
4126 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4127
4128 // Find the Agent_OnUnload function.
4129 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4130 os::find_agent_function(agent,
4131 false,
4132 on_unload_symbols,
4133 num_symbol_entries));
4134
4135 // Invoke the Agent_OnUnload function
4136 if (unload_entry != NULL) {
4137 JavaThread* thread = JavaThread::current();
4138 ThreadToNativeFromVM ttn(thread);
4139 HandleMark hm(thread);
4140 (*unload_entry)(&main_vm);
4141 }
4142 }
4143 }
4144
4145 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4146 // Invokes JVM_OnLoad
4147 void Threads::create_vm_init_libraries() {
4148 extern struct JavaVM_ main_vm;
4149 AgentLibrary* agent;
4150
4151 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4152 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4153
4154 if (on_load_entry != NULL) {
4155 // Invoke the JVM_OnLoad function
4156 JavaThread* thread = JavaThread::current();
4157 ThreadToNativeFromVM ttn(thread);
4158 HandleMark hm(thread);
4159 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4160 if (err != JNI_OK) {
4161 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4162 }
4163 } else {
4164 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4165 }
4166 }
4167 }
4168
4169
4170 // Last thread running calls java.lang.Shutdown.shutdown()
4171 void JavaThread::invoke_shutdown_hooks() {
4172 HandleMark hm(this);
4173
4174 // We could get here with a pending exception, if so clear it now.
4175 if (this->has_pending_exception()) {
4176 this->clear_pending_exception();
4177 }
4178
4179 EXCEPTION_MARK;
4180 Klass* shutdown_klass =
4181 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4182 THREAD);
4183 if (shutdown_klass != NULL) {
4184 // SystemDictionary::resolve_or_null will return null if there was
4185 // an exception. If we cannot load the Shutdown class, just don't
4186 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4187 // won't be run. Note that if a shutdown hook was registered,
4188 // the Shutdown class would have already been loaded
4189 // (Runtime.addShutdownHook will load it).
4190 JavaValue result(T_VOID);
4191 JavaCalls::call_static(&result,
4192 shutdown_klass,
4193 vmSymbols::shutdown_method_name(),
4194 vmSymbols::void_method_signature(),
4195 THREAD);
4196 }
4197 CLEAR_PENDING_EXCEPTION;
4198 }
4199
4200 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4201 // the program falls off the end of main(). Another VM exit path is through
4202 // vm_exit() when the program calls System.exit() to return a value or when
4203 // there is a serious error in VM. The two shutdown paths are not exactly
4204 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4205 // and VM_Exit op at VM level.
4206 //
4207 // Shutdown sequence:
4208 // + Shutdown native memory tracking if it is on
4209 // + Wait until we are the last non-daemon thread to execute
4210 // <-- every thing is still working at this moment -->
4211 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4212 // shutdown hooks
4213 // + Call before_exit(), prepare for VM exit
4214 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4215 // currently the only user of this mechanism is File.deleteOnExit())
4216 // > stop StatSampler, watcher thread, CMS threads,
4217 // post thread end and vm death events to JVMTI,
4218 // stop signal thread
4219 // + Call JavaThread::exit(), it will:
4220 // > release JNI handle blocks, remove stack guard pages
4221 // > remove this thread from Threads list
4222 // <-- no more Java code from this thread after this point -->
4223 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4224 // the compiler threads at safepoint
4225 // <-- do not use anything that could get blocked by Safepoint -->
4226 // + Disable tracing at JNI/JVM barriers
4227 // + Set _vm_exited flag for threads that are still running native code
4228 // + Call exit_globals()
4229 // > deletes tty
4230 // > deletes PerfMemory resources
4231 // + Delete this thread
4232 // + Return to caller
4233
4234 bool Threads::destroy_vm() {
4235 JavaThread* thread = JavaThread::current();
4236
4237 #ifdef ASSERT
4238 _vm_complete = false;
4239 #endif
4240 // Wait until we are the last non-daemon thread to execute
4241 { MutexLocker nu(Threads_lock);
4242 while (Threads::number_of_non_daemon_threads() > 1)
4243 // This wait should make safepoint checks, wait without a timeout,
4244 // and wait as a suspend-equivalent condition.
4245 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4246 Mutex::_as_suspend_equivalent_flag);
4247 }
4248
4249 EventShutdown e;
4250 if (e.should_commit()) {
4251 e.set_reason("No remaining non-daemon Java threads");
4252 e.commit();
4253 }
4254
4255 // Hang forever on exit if we are reporting an error.
4256 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4257 os::infinite_sleep();
4258 }
4259 os::wait_for_keypress_at_exit();
4260
4261 // run Java level shutdown hooks
4262 thread->invoke_shutdown_hooks();
4263
4264 before_exit(thread);
4265
4266 thread->exit(true);
4267
4268 // Stop VM thread.
4269 {
4270 // 4945125 The vm thread comes to a safepoint during exit.
4271 // GC vm_operations can get caught at the safepoint, and the
4272 // heap is unparseable if they are caught. Grab the Heap_lock
4273 // to prevent this. The GC vm_operations will not be able to
4274 // queue until after the vm thread is dead. After this point,
4275 // we'll never emerge out of the safepoint before the VM exits.
4276
4277 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4278
4279 VMThread::wait_for_vm_thread_exit();
4280 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4281 VMThread::destroy();
4282 }
4283
4284 // Now, all Java threads are gone except daemon threads. Daemon threads
4285 // running Java code or in VM are stopped by the Safepoint. However,
4286 // daemon threads executing native code are still running. But they
4287 // will be stopped at native=>Java/VM barriers. Note that we can't
4288 // simply kill or suspend them, as it is inherently deadlock-prone.
4289
4290 VM_Exit::set_vm_exited();
4291
4292 // Clean up ideal graph printers after the VMThread has started
4293 // the final safepoint which will block all the Compiler threads.
4294 // Note that this Thread has already logically exited so the
4295 // clean_up() function's use of a JavaThreadIteratorWithHandle
4296 // would be a problem except set_vm_exited() has remembered the
4297 // shutdown thread which is granted a policy exception.
4298 #if defined(COMPILER2) && !defined(PRODUCT)
4299 IdealGraphPrinter::clean_up();
4300 #endif
4301
4302 notify_vm_shutdown();
4303
4304 // exit_globals() will delete tty
4305 exit_globals();
4306
4307 // We are after VM_Exit::set_vm_exited() so we can't call
4308 // thread->smr_delete() or we will block on the Threads_lock.
4309 // Deleting the shutdown thread here is safe because another
4310 // JavaThread cannot have an active ThreadsListHandle for
4311 // this JavaThread.
4312 delete thread;
4313
4314 #if INCLUDE_JVMCI
4315 if (JVMCICounterSize > 0) {
4316 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4317 }
4318 #endif
4319
4320 LogConfiguration::finalize();
4321
4322 return true;
4323 }
4324
4325
4326 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4327 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4328 return is_supported_jni_version(version);
4329 }
4330
4331
4332 jboolean Threads::is_supported_jni_version(jint version) {
4333 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4334 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4335 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4336 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4337 if (version == JNI_VERSION_9) return JNI_TRUE;
4338 if (version == JNI_VERSION_10) return JNI_TRUE;
4339 return JNI_FALSE;
4340 }
4341
4342
4343 void Threads::add(JavaThread* p, bool force_daemon) {
4344 // The threads lock must be owned at this point
4345 assert(Threads_lock->owned_by_self(), "must have threads lock");
4346
4347 BarrierSet::barrier_set()->on_thread_attach(p);
4348
4349 p->set_next(_thread_list);
4350 _thread_list = p;
4351
4352 // Once a JavaThread is added to the Threads list, smr_delete() has
4353 // to be used to delete it. Otherwise we can just delete it directly.
4354 p->set_on_thread_list();
4355
4356 _number_of_threads++;
4357 oop threadObj = p->threadObj();
4358 bool daemon = true;
4359 // Bootstrapping problem: threadObj can be null for initial
4360 // JavaThread (or for threads attached via JNI)
4361 if ((!force_daemon) && !is_daemon((threadObj))) {
4362 _number_of_non_daemon_threads++;
4363 daemon = false;
4364 }
4365
4366 ThreadService::add_thread(p, daemon);
4367
4368 // Maintain fast thread list
4369 ThreadsSMRSupport::add_thread(p);
4370
4371 // Possible GC point.
4372 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4373 }
4374
4375 void Threads::remove(JavaThread* p) {
4376
4377 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4378 ObjectSynchronizer::omFlush(p);
4379
4380 // Extra scope needed for Thread_lock, so we can check
4381 // that we do not remove thread without safepoint code notice
4382 { MutexLocker ml(Threads_lock);
4383
4384 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4385
4386 // Maintain fast thread list
4387 ThreadsSMRSupport::remove_thread(p);
4388
4389 JavaThread* current = _thread_list;
4390 JavaThread* prev = NULL;
4391
4392 while (current != p) {
4393 prev = current;
4394 current = current->next();
4395 }
4396
4397 if (prev) {
4398 prev->set_next(current->next());
4399 } else {
4400 _thread_list = p->next();
4401 }
4402
4403 _number_of_threads--;
4404 oop threadObj = p->threadObj();
4405 bool daemon = true;
4406 if (!is_daemon(threadObj)) {
4407 _number_of_non_daemon_threads--;
4408 daemon = false;
4409
4410 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4411 // on destroy_vm will wake up.
4412 if (number_of_non_daemon_threads() == 1) {
4413 Threads_lock->notify_all();
4414 }
4415 }
4416 ThreadService::remove_thread(p, daemon);
4417
4418 // Make sure that safepoint code disregard this thread. This is needed since
4419 // the thread might mess around with locks after this point. This can cause it
4420 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4421 // of this thread since it is removed from the queue.
4422 p->set_terminated_value();
4423 } // unlock Threads_lock
4424
4425 // Since Events::log uses a lock, we grab it outside the Threads_lock
4426 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4427 }
4428
4429 // Operations on the Threads list for GC. These are not explicitly locked,
4430 // but the garbage collector must provide a safe context for them to run.
4431 // In particular, these things should never be called when the Threads_lock
4432 // is held by some other thread. (Note: the Safepoint abstraction also
4433 // uses the Threads_lock to guarantee this property. It also makes sure that
4434 // all threads gets blocked when exiting or starting).
4435
4436 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4437 ALL_JAVA_THREADS(p) {
4438 p->oops_do(f, cf);
4439 }
4440 VMThread::vm_thread()->oops_do(f, cf);
4441 }
4442
4443 void Threads::change_thread_claim_parity() {
4444 // Set the new claim parity.
4445 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4446 "Not in range.");
4447 _thread_claim_parity++;
4448 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4449 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4450 "Not in range.");
4451 }
4452
4453 #ifdef ASSERT
4454 void Threads::assert_all_threads_claimed() {
4455 ALL_JAVA_THREADS(p) {
4456 const int thread_parity = p->oops_do_parity();
4457 assert((thread_parity == _thread_claim_parity),
4458 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4459 }
4460 VMThread* vmt = VMThread::vm_thread();
4461 const int thread_parity = vmt->oops_do_parity();
4462 assert((thread_parity == _thread_claim_parity),
4463 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4464 }
4465 #endif // ASSERT
4466
4467 class ParallelOopsDoThreadClosure : public ThreadClosure {
4468 private:
4469 OopClosure* _f;
4470 CodeBlobClosure* _cf;
4471 public:
4472 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4473 void do_thread(Thread* t) {
4474 t->oops_do(_f, _cf);
4475 }
4476 };
4477
4478 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4479 ParallelOopsDoThreadClosure tc(f, cf);
4480 possibly_parallel_threads_do(is_par, &tc);
4481 }
4482
4483 void Threads::nmethods_do(CodeBlobClosure* cf) {
4484 ALL_JAVA_THREADS(p) {
4485 // This is used by the code cache sweeper to mark nmethods that are active
4486 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4487 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4488 if(!p->is_Code_cache_sweeper_thread()) {
4489 p->nmethods_do(cf);
4490 }
4491 }
4492 }
4493
4494 void Threads::metadata_do(void f(Metadata*)) {
4495 ALL_JAVA_THREADS(p) {
4496 p->metadata_do(f);
4497 }
4498 }
4499
4500 class ThreadHandlesClosure : public ThreadClosure {
4501 void (*_f)(Metadata*);
4502 public:
4503 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4504 virtual void do_thread(Thread* thread) {
4505 thread->metadata_handles_do(_f);
4506 }
4507 };
4508
4509 void Threads::metadata_handles_do(void f(Metadata*)) {
4510 // Only walk the Handles in Thread.
4511 ThreadHandlesClosure handles_closure(f);
4512 threads_do(&handles_closure);
4513 }
4514
4515 void Threads::deoptimized_wrt_marked_nmethods() {
4516 ALL_JAVA_THREADS(p) {
4517 p->deoptimized_wrt_marked_nmethods();
4518 }
4519 }
4520
4521
4522 // Get count Java threads that are waiting to enter the specified monitor.
4523 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4524 int count,
4525 address monitor) {
4526 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4527
4528 int i = 0;
4529 DO_JAVA_THREADS(t_list, p) {
4530 if (!p->can_call_java()) continue;
4531
4532 address pending = (address)p->current_pending_monitor();
4533 if (pending == monitor) { // found a match
4534 if (i < count) result->append(p); // save the first count matches
4535 i++;
4536 }
4537 }
4538
4539 return result;
4540 }
4541
4542
4543 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4544 address owner) {
4545 // NULL owner means not locked so we can skip the search
4546 if (owner == NULL) return NULL;
4547
4548 DO_JAVA_THREADS(t_list, p) {
4549 // first, see if owner is the address of a Java thread
4550 if (owner == (address)p) return p;
4551 }
4552
4553 // Cannot assert on lack of success here since this function may be
4554 // used by code that is trying to report useful problem information
4555 // like deadlock detection.
4556 if (UseHeavyMonitors) return NULL;
4557
4558 // If we didn't find a matching Java thread and we didn't force use of
4559 // heavyweight monitors, then the owner is the stack address of the
4560 // Lock Word in the owning Java thread's stack.
4561 //
4562 JavaThread* the_owner = NULL;
4563 DO_JAVA_THREADS(t_list, q) {
4564 if (q->is_lock_owned(owner)) {
4565 the_owner = q;
4566 break;
4567 }
4568 }
4569
4570 // cannot assert on lack of success here; see above comment
4571 return the_owner;
4572 }
4573
4574 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4575 void Threads::print_on(outputStream* st, bool print_stacks,
4576 bool internal_format, bool print_concurrent_locks,
4577 bool print_extended_info) {
4578 char buf[32];
4579 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4580
4581 st->print_cr("Full thread dump %s (%s %s):",
4582 VM_Version::vm_name(),
4583 VM_Version::vm_release(),
4584 VM_Version::vm_info_string());
4585 st->cr();
4586
4587 #if INCLUDE_SERVICES
4588 // Dump concurrent locks
4589 ConcurrentLocksDump concurrent_locks;
4590 if (print_concurrent_locks) {
4591 concurrent_locks.dump_at_safepoint();
4592 }
4593 #endif // INCLUDE_SERVICES
4594
4595 ThreadsSMRSupport::print_info_on(st);
4596 st->cr();
4597
4598 ALL_JAVA_THREADS(p) {
4599 ResourceMark rm;
4600 p->print_on(st, print_extended_info);
4601 if (print_stacks) {
4602 if (internal_format) {
4603 p->trace_stack();
4604 } else {
4605 p->print_stack_on(st);
4606 }
4607 }
4608 st->cr();
4609 #if INCLUDE_SERVICES
4610 if (print_concurrent_locks) {
4611 concurrent_locks.print_locks_on(p, st);
4612 }
4613 #endif // INCLUDE_SERVICES
4614 }
4615
4616 VMThread::vm_thread()->print_on(st);
4617 st->cr();
4618 Universe::heap()->print_gc_threads_on(st);
4619 WatcherThread* wt = WatcherThread::watcher_thread();
4620 if (wt != NULL) {
4621 wt->print_on(st);
4622 st->cr();
4623 }
4624
4625 st->flush();
4626 }
4627
4628 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4629 int buflen, bool* found_current) {
4630 if (this_thread != NULL) {
4631 bool is_current = (current == this_thread);
4632 *found_current = *found_current || is_current;
4633 st->print("%s", is_current ? "=>" : " ");
4634
4635 st->print(PTR_FORMAT, p2i(this_thread));
4636 st->print(" ");
4637 this_thread->print_on_error(st, buf, buflen);
4638 st->cr();
4639 }
4640 }
4641
4642 class PrintOnErrorClosure : public ThreadClosure {
4643 outputStream* _st;
4644 Thread* _current;
4645 char* _buf;
4646 int _buflen;
4647 bool* _found_current;
4648 public:
4649 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4650 int buflen, bool* found_current) :
4651 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4652
4653 virtual void do_thread(Thread* thread) {
4654 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4655 }
4656 };
4657
4658 // Threads::print_on_error() is called by fatal error handler. It's possible
4659 // that VM is not at safepoint and/or current thread is inside signal handler.
4660 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4661 // memory (even in resource area), it might deadlock the error handler.
4662 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4663 int buflen) {
4664 ThreadsSMRSupport::print_info_on(st);
4665 st->cr();
4666
4667 bool found_current = false;
4668 st->print_cr("Java Threads: ( => current thread )");
4669 ALL_JAVA_THREADS(thread) {
4670 print_on_error(thread, st, current, buf, buflen, &found_current);
4671 }
4672 st->cr();
4673
4674 st->print_cr("Other Threads:");
4675 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4676 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4677
4678 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4679 Universe::heap()->gc_threads_do(&print_closure);
4680
4681 if (!found_current) {
4682 st->cr();
4683 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4684 current->print_on_error(st, buf, buflen);
4685 st->cr();
4686 }
4687 st->cr();
4688
4689 st->print_cr("Threads with active compile tasks:");
4690 print_threads_compiling(st, buf, buflen);
4691 }
4692
4693 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4694 ALL_JAVA_THREADS(thread) {
4695 if (thread->is_Compiler_thread()) {
4696 CompilerThread* ct = (CompilerThread*) thread;
4697
4698 // Keep task in local variable for NULL check.
4699 // ct->_task might be set to NULL by concurring compiler thread
4700 // because it completed the compilation. The task is never freed,
4701 // though, just returned to a free list.
4702 CompileTask* task = ct->task();
4703 if (task != NULL) {
4704 thread->print_name_on_error(st, buf, buflen);
4705 st->print(" ");
4706 task->print(st, NULL, true, true);
4707 }
4708 }
4709 }
4710 }
4711
4712
4713 // Internal SpinLock and Mutex
4714 // Based on ParkEvent
4715
4716 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4717 //
4718 // We employ SpinLocks _only for low-contention, fixed-length
4719 // short-duration critical sections where we're concerned
4720 // about native mutex_t or HotSpot Mutex:: latency.
4721 // The mux construct provides a spin-then-block mutual exclusion
4722 // mechanism.
4723 //
4724 // Testing has shown that contention on the ListLock guarding gFreeList
4725 // is common. If we implement ListLock as a simple SpinLock it's common
4726 // for the JVM to devolve to yielding with little progress. This is true
4727 // despite the fact that the critical sections protected by ListLock are
4728 // extremely short.
4729 //
4730 // TODO-FIXME: ListLock should be of type SpinLock.
4731 // We should make this a 1st-class type, integrated into the lock
4732 // hierarchy as leaf-locks. Critically, the SpinLock structure
4733 // should have sufficient padding to avoid false-sharing and excessive
4734 // cache-coherency traffic.
4735
4736
4737 typedef volatile int SpinLockT;
4738
4739 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4740 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4741 return; // normal fast-path return
4742 }
4743
4744 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4745 int ctr = 0;
4746 int Yields = 0;
4747 for (;;) {
4748 while (*adr != 0) {
4749 ++ctr;
4750 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4751 if (Yields > 5) {
4752 os::naked_short_sleep(1);
4753 } else {
4754 os::naked_yield();
4755 ++Yields;
4756 }
4757 } else {
4758 SpinPause();
4759 }
4760 }
4761 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4762 }
4763 }
4764
4765 void Thread::SpinRelease(volatile int * adr) {
4766 assert(*adr != 0, "invariant");
4767 OrderAccess::fence(); // guarantee at least release consistency.
4768 // Roach-motel semantics.
4769 // It's safe if subsequent LDs and STs float "up" into the critical section,
4770 // but prior LDs and STs within the critical section can't be allowed
4771 // to reorder or float past the ST that releases the lock.
4772 // Loads and stores in the critical section - which appear in program
4773 // order before the store that releases the lock - must also appear
4774 // before the store that releases the lock in memory visibility order.
4775 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4776 // the ST of 0 into the lock-word which releases the lock, so fence
4777 // more than covers this on all platforms.
4778 *adr = 0;
4779 }
4780
4781 // muxAcquire and muxRelease:
4782 //
4783 // * muxAcquire and muxRelease support a single-word lock-word construct.
4784 // The LSB of the word is set IFF the lock is held.
4785 // The remainder of the word points to the head of a singly-linked list
4786 // of threads blocked on the lock.
4787 //
4788 // * The current implementation of muxAcquire-muxRelease uses its own
4789 // dedicated Thread._MuxEvent instance. If we're interested in
4790 // minimizing the peak number of extant ParkEvent instances then
4791 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4792 // as certain invariants were satisfied. Specifically, care would need
4793 // to be taken with regards to consuming unpark() "permits".
4794 // A safe rule of thumb is that a thread would never call muxAcquire()
4795 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4796 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4797 // consume an unpark() permit intended for monitorenter, for instance.
4798 // One way around this would be to widen the restricted-range semaphore
4799 // implemented in park(). Another alternative would be to provide
4800 // multiple instances of the PlatformEvent() for each thread. One
4801 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4802 //
4803 // * Usage:
4804 // -- Only as leaf locks
4805 // -- for short-term locking only as muxAcquire does not perform
4806 // thread state transitions.
4807 //
4808 // Alternatives:
4809 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4810 // but with parking or spin-then-park instead of pure spinning.
4811 // * Use Taura-Oyama-Yonenzawa locks.
4812 // * It's possible to construct a 1-0 lock if we encode the lockword as
4813 // (List,LockByte). Acquire will CAS the full lockword while Release
4814 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4815 // acquiring threads use timers (ParkTimed) to detect and recover from
4816 // the stranding window. Thread/Node structures must be aligned on 256-byte
4817 // boundaries by using placement-new.
4818 // * Augment MCS with advisory back-link fields maintained with CAS().
4819 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4820 // The validity of the backlinks must be ratified before we trust the value.
4821 // If the backlinks are invalid the exiting thread must back-track through the
4822 // the forward links, which are always trustworthy.
4823 // * Add a successor indication. The LockWord is currently encoded as
4824 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4825 // to provide the usual futile-wakeup optimization.
4826 // See RTStt for details.
4827 //
4828
4829
4830 const intptr_t LOCKBIT = 1;
4831
4832 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4833 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4834 if (w == 0) return;
4835 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4836 return;
4837 }
4838
4839 ParkEvent * const Self = Thread::current()->_MuxEvent;
4840 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4841 for (;;) {
4842 int its = (os::is_MP() ? 100 : 0) + 1;
4843
4844 // Optional spin phase: spin-then-park strategy
4845 while (--its >= 0) {
4846 w = *Lock;
4847 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4848 return;
4849 }
4850 }
4851
4852 Self->reset();
4853 Self->OnList = intptr_t(Lock);
4854 // The following fence() isn't _strictly necessary as the subsequent
4855 // CAS() both serializes execution and ratifies the fetched *Lock value.
4856 OrderAccess::fence();
4857 for (;;) {
4858 w = *Lock;
4859 if ((w & LOCKBIT) == 0) {
4860 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4861 Self->OnList = 0; // hygiene - allows stronger asserts
4862 return;
4863 }
4864 continue; // Interference -- *Lock changed -- Just retry
4865 }
4866 assert(w & LOCKBIT, "invariant");
4867 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4868 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4869 }
4870
4871 while (Self->OnList != 0) {
4872 Self->park();
4873 }
4874 }
4875 }
4876
4877 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4878 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4879 if (w == 0) return;
4880 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4881 return;
4882 }
4883
4884 ParkEvent * ReleaseAfter = NULL;
4885 if (ev == NULL) {
4886 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4887 }
4888 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4889 for (;;) {
4890 guarantee(ev->OnList == 0, "invariant");
4891 int its = (os::is_MP() ? 100 : 0) + 1;
4892
4893 // Optional spin phase: spin-then-park strategy
4894 while (--its >= 0) {
4895 w = *Lock;
4896 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4897 if (ReleaseAfter != NULL) {
4898 ParkEvent::Release(ReleaseAfter);
4899 }
4900 return;
4901 }
4902 }
4903
4904 ev->reset();
4905 ev->OnList = intptr_t(Lock);
4906 // The following fence() isn't _strictly necessary as the subsequent
4907 // CAS() both serializes execution and ratifies the fetched *Lock value.
4908 OrderAccess::fence();
4909 for (;;) {
4910 w = *Lock;
4911 if ((w & LOCKBIT) == 0) {
4912 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4913 ev->OnList = 0;
4914 // We call ::Release while holding the outer lock, thus
4915 // artificially lengthening the critical section.
4916 // Consider deferring the ::Release() until the subsequent unlock(),
4917 // after we've dropped the outer lock.
4918 if (ReleaseAfter != NULL) {
4919 ParkEvent::Release(ReleaseAfter);
4920 }
4921 return;
4922 }
4923 continue; // Interference -- *Lock changed -- Just retry
4924 }
4925 assert(w & LOCKBIT, "invariant");
4926 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4927 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4928 }
4929
4930 while (ev->OnList != 0) {
4931 ev->park();
4932 }
4933 }
4934 }
4935
4936 // Release() must extract a successor from the list and then wake that thread.
4937 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4938 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4939 // Release() would :
4940 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4941 // (B) Extract a successor from the private list "in-hand"
4942 // (C) attempt to CAS() the residual back into *Lock over null.
4943 // If there were any newly arrived threads and the CAS() would fail.
4944 // In that case Release() would detach the RATs, re-merge the list in-hand
4945 // with the RATs and repeat as needed. Alternately, Release() might
4946 // detach and extract a successor, but then pass the residual list to the wakee.
4947 // The wakee would be responsible for reattaching and remerging before it
4948 // competed for the lock.
4949 //
4950 // Both "pop" and DMR are immune from ABA corruption -- there can be
4951 // multiple concurrent pushers, but only one popper or detacher.
4952 // This implementation pops from the head of the list. This is unfair,
4953 // but tends to provide excellent throughput as hot threads remain hot.
4954 // (We wake recently run threads first).
4955 //
4956 // All paths through muxRelease() will execute a CAS.
4957 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4958 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4959 // executed within the critical section are complete and globally visible before the
4960 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4961 void Thread::muxRelease(volatile intptr_t * Lock) {
4962 for (;;) {
4963 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4964 assert(w & LOCKBIT, "invariant");
4965 if (w == LOCKBIT) return;
4966 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4967 assert(List != NULL, "invariant");
4968 assert(List->OnList == intptr_t(Lock), "invariant");
4969 ParkEvent * const nxt = List->ListNext;
4970 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4971
4972 // The following CAS() releases the lock and pops the head element.
4973 // The CAS() also ratifies the previously fetched lock-word value.
4974 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4975 continue;
4976 }
4977 List->OnList = 0;
4978 OrderAccess::fence();
4979 List->unpark();
4980 return;
4981 }
4982 }
4983
4984
4985 void Threads::verify() {
4986 ALL_JAVA_THREADS(p) {
4987 p->verify();
4988 }
4989 VMThread* thread = VMThread::vm_thread();
4990 if (thread != NULL) thread->verify();
4991 }