1 /*
2 * Copyright (c) 1997, 2020, 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 "aot/aotLoader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/javaClasses.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileBroker.hpp"
36 #include "compiler/compileTask.hpp"
37 #include "gc/shared/barrierSet.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/workgroup.hpp"
41 #include "interpreter/interpreter.hpp"
42 #include "interpreter/linkResolver.hpp"
43 #include "interpreter/oopMapCache.hpp"
44 #include "jfr/jfrEvents.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/iterator.hpp"
51 #include "memory/metaspaceShared.hpp"
52 #include "memory/oopFactory.hpp"
53 #include "memory/resourceArea.hpp"
54 #include "memory/universe.hpp"
55 #include "oops/access.inline.hpp"
56 #include "oops/instanceKlass.hpp"
57 #include "oops/objArrayOop.hpp"
58 #include "oops/oop.inline.hpp"
59 #include "oops/symbol.hpp"
60 #include "oops/typeArrayOop.inline.hpp"
61 #include "oops/verifyOopClosure.hpp"
62 #include "prims/jvm_misc.hpp"
63 #include "prims/jvmtiExport.hpp"
64 #include "prims/jvmtiThreadState.hpp"
65 #include "runtime/arguments.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/biasedLocking.hpp"
68 #include "runtime/fieldDescriptor.inline.hpp"
69 #include "runtime/flags/jvmFlagConstraintList.hpp"
70 #include "runtime/flags/jvmFlagRangeList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/serviceThread.hpp"
91 #include "runtime/sharedRuntime.hpp"
92 #include "runtime/statSampler.hpp"
93 #include "runtime/stubRoutines.hpp"
94 #include "runtime/sweeper.hpp"
95 #include "runtime/task.hpp"
96 #include "runtime/thread.inline.hpp"
97 #include "runtime/threadCritical.hpp"
98 #include "runtime/threadSMR.inline.hpp"
99 #include "runtime/threadStatisticalInfo.hpp"
100 #include "runtime/timer.hpp"
101 #include "runtime/timerTrace.hpp"
102 #include "runtime/vframe.inline.hpp"
103 #include "runtime/vframeArray.hpp"
104 #include "runtime/vframe_hp.hpp"
105 #include "runtime/vmThread.hpp"
106 #include "runtime/vmOperations.hpp"
107 #include "runtime/vm_version.hpp"
108 #include "services/attachListener.hpp"
109 #include "services/management.hpp"
110 #include "services/memTracker.hpp"
111 #include "services/threadService.hpp"
112 #include "utilities/align.hpp"
113 #include "utilities/copy.hpp"
114 #include "utilities/defaultStream.hpp"
115 #include "utilities/dtrace.hpp"
116 #include "utilities/events.hpp"
117 #include "utilities/macros.hpp"
118 #include "utilities/preserveException.hpp"
119 #include "utilities/singleWriterSynchronizer.hpp"
120 #include "utilities/vmError.hpp"
121 #if INCLUDE_JVMCI
122 #include "jvmci/jvmci.hpp"
123 #include "jvmci/jvmciEnv.hpp"
124 #endif
125 #ifdef COMPILER1
126 #include "c1/c1_Compiler.hpp"
127 #endif
128 #ifdef COMPILER2
129 #include "opto/c2compiler.hpp"
130 #include "opto/idealGraphPrinter.hpp"
131 #endif
132 #if INCLUDE_RTM_OPT
133 #include "runtime/rtmLocking.hpp"
134 #endif
135 #if INCLUDE_JFR
136 #include "jfr/jfr.hpp"
137 #endif
138
139 // Initialization after module runtime initialization
140 void universe_post_module_init(); // must happen after call_initPhase2
141
142 #ifdef DTRACE_ENABLED
143
144 // Only bother with this argument setup if dtrace is available
145
146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
148
149 #define DTRACE_THREAD_PROBE(probe, javathread) \
150 { \
151 ResourceMark rm(this); \
152 int len = 0; \
153 const char* name = (javathread)->get_thread_name(); \
154 len = strlen(name); \
155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
156 (char *) name, len, \
157 java_lang_Thread::thread_id((javathread)->threadObj()), \
158 (uintptr_t) (javathread)->osthread()->thread_id(), \
159 java_lang_Thread::is_daemon((javathread)->threadObj())); \
160 }
161
162 #else // ndef DTRACE_ENABLED
163
164 #define DTRACE_THREAD_PROBE(probe, javathread)
165
166 #endif // ndef DTRACE_ENABLED
167
168 #ifndef USE_LIBRARY_BASED_TLS_ONLY
169 // Current thread is maintained as a thread-local variable
170 THREAD_LOCAL Thread* Thread::_thr_current = NULL;
171 #endif
172
173 // ======= Thread ========
174 // Support for forcing alignment of thread objects for biased locking
175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
176 if (UseBiasedLocking) {
177 const size_t alignment = markWord::biased_lock_alignment;
178 size_t aligned_size = size + (alignment - sizeof(intptr_t));
179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
180 : AllocateHeap(aligned_size, flags, CURRENT_PC,
181 AllocFailStrategy::RETURN_NULL);
182 void* aligned_addr = align_up(real_malloc_addr, alignment);
183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
185 "JavaThread alignment code overflowed allocated storage");
186 if (aligned_addr != real_malloc_addr) {
187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
188 p2i(real_malloc_addr),
189 p2i(aligned_addr));
190 }
191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
192 return aligned_addr;
193 } else {
194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
196 }
197 }
198
199 void Thread::operator delete(void* p) {
200 if (UseBiasedLocking) {
201 FreeHeap(((Thread*) p)->_real_malloc_address);
202 } else {
203 FreeHeap(p);
204 }
205 }
206
207 void JavaThread::smr_delete() {
208 if (_on_thread_list) {
209 ThreadsSMRSupport::smr_delete(this);
210 } else {
211 delete this;
212 }
213 }
214
215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
216 // JavaThread
217
218 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
219
220 Thread::Thread() {
221
222 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
223
224 // stack and get_thread
225 set_stack_base(NULL);
226 set_stack_size(0);
227 set_lgrp_id(-1);
228 DEBUG_ONLY(clear_suspendible_thread();)
229
230 // allocated data structures
231 set_osthread(NULL);
232 set_resource_area(new (mtThread)ResourceArea());
233 DEBUG_ONLY(_current_resource_mark = NULL;)
234 set_handle_area(new (mtThread) HandleArea(NULL));
235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
236 set_active_handles(NULL);
237 set_free_handle_block(NULL);
238 set_last_handle_mark(NULL);
239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
240
241 // Initial value of zero ==> never claimed.
242 _threads_do_token = 0;
243 _threads_hazard_ptr = NULL;
244 _threads_list_ptr = NULL;
245 _nested_threads_hazard_ptr_cnt = 0;
246 _rcu_counter = 0;
247
248 // the handle mark links itself to last_handle_mark
249 new HandleMark(this);
250
251 // plain initialization
252 debug_only(_owned_locks = NULL;)
253 NOT_PRODUCT(_no_safepoint_count = 0;)
254 NOT_PRODUCT(_skip_gcalot = false;)
255 _jvmti_env_iteration_count = 0;
256 set_allocated_bytes(0);
257 _vm_operation_started_count = 0;
258 _vm_operation_completed_count = 0;
259 _current_pending_monitor = NULL;
260 _current_pending_monitor_is_from_java = true;
261 _current_waiting_monitor = NULL;
262 _current_pending_raw_monitor = NULL;
263 _num_nested_signal = 0;
264 om_free_list = NULL;
265 om_free_count = 0;
266 om_free_provision = 32;
267 om_in_use_list = NULL;
268 om_in_use_count = 0;
269
270 #ifdef ASSERT
271 _visited_for_critical_count = false;
272 #endif
273
274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
275 Monitor::_safepoint_check_sometimes);
276 _suspend_flags = 0;
277
278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
279 _hashStateX = os::random();
280 _hashStateY = 842502087;
281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
282 _hashStateW = 273326509;
283
284 _OnTrap = 0;
285 _Stalled = 0;
286 _TypeTag = 0x2BAD;
287
288 // Many of the following fields are effectively final - immutable
289 // Note that nascent threads can't use the Native Monitor-Mutex
290 // construct until the _MutexEvent is initialized ...
291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
292 // we might instead use a stack of ParkEvents that we could provision on-demand.
293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
294 // and ::Release()
295 _ParkEvent = ParkEvent::Allocate(this);
296 _MuxEvent = ParkEvent::Allocate(this);
297
298 #ifdef CHECK_UNHANDLED_OOPS
299 if (CheckUnhandledOops) {
300 _unhandled_oops = new UnhandledOops(this);
301 }
302 #endif // CHECK_UNHANDLED_OOPS
303 #ifdef ASSERT
304 if (UseBiasedLocking) {
305 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
306 assert(this == _real_malloc_address ||
307 this == align_up(_real_malloc_address, markWord::biased_lock_alignment),
308 "bug in forced alignment of thread objects");
309 }
310 #endif // ASSERT
311
312 // Notify the barrier set that a thread is being created. The initial
313 // thread is created before the barrier set is available. The call to
314 // BarrierSet::on_thread_create() for this thread is therefore deferred
315 // to BarrierSet::set_barrier_set().
316 BarrierSet* const barrier_set = BarrierSet::barrier_set();
317 if (barrier_set != NULL) {
318 barrier_set->on_thread_create(this);
319 } else {
320 // Only the main thread should be created before the barrier set
321 // and that happens just before Thread::current is set. No other thread
322 // can attach as the VM is not created yet, so they can't execute this code.
323 // If the main thread creates other threads before the barrier set that is an error.
324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
325 }
326 }
327
328 void Thread::initialize_thread_current() {
329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
330 assert(_thr_current == NULL, "Thread::current already initialized");
331 _thr_current = this;
332 #endif
333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
334 ThreadLocalStorage::set_thread(this);
335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
336 }
337
338 void Thread::clear_thread_current() {
339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
341 _thr_current = NULL;
342 #endif
343 ThreadLocalStorage::set_thread(NULL);
344 }
345
346 void Thread::record_stack_base_and_size() {
347 // Note: at this point, Thread object is not yet initialized. Do not rely on
348 // any members being initialized. Do not rely on Thread::current() being set.
349 // If possible, refrain from doing anything which may crash or assert since
350 // quite probably those crash dumps will be useless.
351 set_stack_base(os::current_stack_base());
352 set_stack_size(os::current_stack_size());
353
354 #ifdef SOLARIS
355 if (os::is_primordial_thread()) {
356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
357 }
358 #endif
359
360 // Set stack limits after thread is initialized.
361 if (is_Java_thread()) {
362 ((JavaThread*) this)->set_stack_overflow_limit();
363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
364 }
365 }
366
367 #if INCLUDE_NMT
368 void Thread::register_thread_stack_with_NMT() {
369 MemTracker::record_thread_stack(stack_end(), stack_size());
370 }
371 #endif // INCLUDE_NMT
372
373 void Thread::call_run() {
374 DEBUG_ONLY(_run_state = CALL_RUN;)
375
376 // At this point, Thread object should be fully initialized and
377 // Thread::current() should be set.
378
379 assert(Thread::current_or_null() != NULL, "current thread is unset");
380 assert(Thread::current_or_null() == this, "current thread is wrong");
381
382 // Perform common initialization actions
383
384 register_thread_stack_with_NMT();
385
386 JFR_ONLY(Jfr::on_thread_start(this);)
387
388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
390 os::current_thread_id(), p2i(stack_end()),
391 p2i(stack_base()), stack_size()/1024);
392
393 // Perform <ChildClass> initialization actions
394 DEBUG_ONLY(_run_state = PRE_RUN;)
395 this->pre_run();
396
397 // Invoke <ChildClass>::run()
398 DEBUG_ONLY(_run_state = RUN;)
399 this->run();
400 // Returned from <ChildClass>::run(). Thread finished.
401
402 // Perform common tear-down actions
403
404 assert(Thread::current_or_null() != NULL, "current thread is unset");
405 assert(Thread::current_or_null() == this, "current thread is wrong");
406
407 // Perform <ChildClass> tear-down actions
408 DEBUG_ONLY(_run_state = POST_RUN;)
409 this->post_run();
410
411 // Note: at this point the thread object may already have deleted itself,
412 // so from here on do not dereference *this*. Not all thread types currently
413 // delete themselves when they terminate. But no thread should ever be deleted
414 // asynchronously with respect to its termination - that is what _run_state can
415 // be used to check.
416
417 assert(Thread::current_or_null() == NULL, "current thread still present");
418 }
419
420 Thread::~Thread() {
421
422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
423 // get started due to errors etc. Any active thread should at least reach post_run
424 // before it is deleted (usually in post_run()).
425 assert(_run_state == PRE_CALL_RUN ||
426 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
427 "_run_state=%d", (int)_run_state);
428
429 // Notify the barrier set that a thread is being destroyed. Note that a barrier
430 // set might not be available if we encountered errors during bootstrapping.
431 BarrierSet* const barrier_set = BarrierSet::barrier_set();
432 if (barrier_set != NULL) {
433 barrier_set->on_thread_destroy(this);
434 }
435
436 // stack_base can be NULL if the thread is never started or exited before
437 // record_stack_base_and_size called. Although, we would like to ensure
438 // that all started threads do call record_stack_base_and_size(), there is
439 // not proper way to enforce that.
440 #if INCLUDE_NMT
441 if (_stack_base != NULL) {
442 MemTracker::release_thread_stack(stack_end(), stack_size());
443 #ifdef ASSERT
444 set_stack_base(NULL);
445 #endif
446 }
447 #endif // INCLUDE_NMT
448
449 // deallocate data structures
450 delete resource_area();
451 // since the handle marks are using the handle area, we have to deallocated the root
452 // handle mark before deallocating the thread's handle area,
453 assert(last_handle_mark() != NULL, "check we have an element");
454 delete last_handle_mark();
455 assert(last_handle_mark() == NULL, "check we have reached the end");
456
457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
458 // We NULL out the fields for good hygiene.
459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
460 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
461
462 delete handle_area();
463 delete metadata_handles();
464
465 // SR_handler uses this as a termination indicator -
466 // needs to happen before os::free_thread()
467 delete _SR_lock;
468 _SR_lock = NULL;
469
470 // osthread() can be NULL, if creation of thread failed.
471 if (osthread() != NULL) os::free_thread(osthread());
472
473 // Clear Thread::current if thread is deleting itself and it has not
474 // already been done. This must be done before the memory is deallocated.
475 // Needed to ensure JNI correctly detects non-attached threads.
476 if (this == Thread::current_or_null()) {
477 Thread::clear_thread_current();
478 }
479
480 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
481 }
482
483 #ifdef ASSERT
484 // A JavaThread is considered "dangling" if it is not the current
485 // thread, has been added the Threads list, the system is not at a
486 // safepoint and the Thread is not "protected".
487 //
488 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
489 assert(!thread->is_Java_thread() || Thread::current() == thread ||
490 !((JavaThread *) thread)->on_thread_list() ||
491 SafepointSynchronize::is_at_safepoint() ||
492 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
493 "possibility of dangling Thread pointer");
494 }
495 #endif
496
497 ThreadPriority Thread::get_priority(const Thread* const thread) {
498 ThreadPriority priority;
499 // Can return an error!
500 (void)os::get_priority(thread, priority);
501 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
502 return priority;
503 }
504
505 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
506 debug_only(check_for_dangling_thread_pointer(thread);)
507 // Can return an error!
508 (void)os::set_priority(thread, priority);
509 }
510
511
512 void Thread::start(Thread* thread) {
513 // Start is different from resume in that its safety is guaranteed by context or
514 // being called from a Java method synchronized on the Thread object.
515 if (!DisableStartThread) {
516 if (thread->is_Java_thread()) {
517 // Initialize the thread state to RUNNABLE before starting this thread.
518 // Can not set it after the thread started because we do not know the
519 // exact thread state at that time. It could be in MONITOR_WAIT or
520 // in SLEEPING or some other state.
521 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
522 java_lang_Thread::RUNNABLE);
523 }
524 os::start_thread(thread);
525 }
526 }
527
528 class InstallAsyncExceptionClosure : public HandshakeClosure {
529 Handle _throwable; // The Throwable thrown at the target Thread
530 public:
531 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
532
533 void do_thread(Thread* thr) {
534 JavaThread* target = (JavaThread*)thr;
535 // Note that this now allows multiple ThreadDeath exceptions to be
536 // thrown at a thread.
537 // The target thread has run and has not exited yet.
538 target->send_thread_stop(_throwable());
539 }
540 };
541
542 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
543 Handle throwable(Thread::current(), java_throwable);
544 JavaThread* target = java_lang_Thread::thread(java_thread);
545 InstallAsyncExceptionClosure vm_stop(throwable);
546 Handshake::execute(&vm_stop, target);
547 }
548
549
550 // Check if an external suspend request has completed (or has been
551 // cancelled). Returns true if the thread is externally suspended and
552 // false otherwise.
553 //
554 // The bits parameter returns information about the code path through
555 // the routine. Useful for debugging:
556 //
557 // set in is_ext_suspend_completed():
558 // 0x00000001 - routine was entered
559 // 0x00000010 - routine return false at end
560 // 0x00000100 - thread exited (return false)
561 // 0x00000200 - suspend request cancelled (return false)
562 // 0x00000400 - thread suspended (return true)
563 // 0x00001000 - thread is in a suspend equivalent state (return true)
564 // 0x00002000 - thread is native and walkable (return true)
565 // 0x00004000 - thread is native_trans and walkable (needed retry)
566 //
567 // set in wait_for_ext_suspend_completion():
568 // 0x00010000 - routine was entered
569 // 0x00020000 - suspend request cancelled before loop (return false)
570 // 0x00040000 - thread suspended before loop (return true)
571 // 0x00080000 - suspend request cancelled in loop (return false)
572 // 0x00100000 - thread suspended in loop (return true)
573 // 0x00200000 - suspend not completed during retry loop (return false)
574
575 // Helper class for tracing suspend wait debug bits.
576 //
577 // 0x00000100 indicates that the target thread exited before it could
578 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
579 // 0x00080000 each indicate a cancelled suspend request so they don't
580 // count as wait failures either.
581 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
582
583 class TraceSuspendDebugBits : public StackObj {
584 private:
585 JavaThread * jt;
586 bool is_wait;
587 bool called_by_wait; // meaningful when !is_wait
588 uint32_t * bits;
589
590 public:
591 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
592 uint32_t *_bits) {
593 jt = _jt;
594 is_wait = _is_wait;
595 called_by_wait = _called_by_wait;
596 bits = _bits;
597 }
598
599 ~TraceSuspendDebugBits() {
600 if (!is_wait) {
601 #if 1
602 // By default, don't trace bits for is_ext_suspend_completed() calls.
603 // That trace is very chatty.
604 return;
605 #else
606 if (!called_by_wait) {
607 // If tracing for is_ext_suspend_completed() is enabled, then only
608 // trace calls to it from wait_for_ext_suspend_completion()
609 return;
610 }
611 #endif
612 }
613
614 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
615 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
616 MutexLocker ml(Threads_lock); // needed for get_thread_name()
617 ResourceMark rm;
618
619 tty->print_cr(
620 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
621 jt->get_thread_name(), *bits);
622
623 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
624 }
625 }
626 }
627 };
628 #undef DEBUG_FALSE_BITS
629
630
631 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
632 uint32_t *bits) {
633 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
634
635 bool did_trans_retry = false; // only do thread_in_native_trans retry once
636 bool do_trans_retry; // flag to force the retry
637
638 *bits |= 0x00000001;
639
640 do {
641 do_trans_retry = false;
642
643 if (is_exiting()) {
644 // Thread is in the process of exiting. This is always checked
645 // first to reduce the risk of dereferencing a freed JavaThread.
646 *bits |= 0x00000100;
647 return false;
648 }
649
650 if (!is_external_suspend()) {
651 // Suspend request is cancelled. This is always checked before
652 // is_ext_suspended() to reduce the risk of a rogue resume
653 // confusing the thread that made the suspend request.
654 *bits |= 0x00000200;
655 return false;
656 }
657
658 if (is_ext_suspended()) {
659 // thread is suspended
660 *bits |= 0x00000400;
661 return true;
662 }
663
664 // Now that we no longer do hard suspends of threads running
665 // native code, the target thread can be changing thread state
666 // while we are in this routine:
667 //
668 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
669 //
670 // We save a copy of the thread state as observed at this moment
671 // and make our decision about suspend completeness based on the
672 // copy. This closes the race where the thread state is seen as
673 // _thread_in_native_trans in the if-thread_blocked check, but is
674 // seen as _thread_blocked in if-thread_in_native_trans check.
675 JavaThreadState save_state = thread_state();
676
677 if (save_state == _thread_blocked && is_suspend_equivalent()) {
678 // If the thread's state is _thread_blocked and this blocking
679 // condition is known to be equivalent to a suspend, then we can
680 // consider the thread to be externally suspended. This means that
681 // the code that sets _thread_blocked has been modified to do
682 // self-suspension if the blocking condition releases. We also
683 // used to check for CONDVAR_WAIT here, but that is now covered by
684 // the _thread_blocked with self-suspension check.
685 //
686 // Return true since we wouldn't be here unless there was still an
687 // external suspend request.
688 *bits |= 0x00001000;
689 return true;
690 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
691 // Threads running native code will self-suspend on native==>VM/Java
692 // transitions. If its stack is walkable (should always be the case
693 // unless this function is called before the actual java_suspend()
694 // call), then the wait is done.
695 *bits |= 0x00002000;
696 return true;
697 } else if (!called_by_wait && !did_trans_retry &&
698 save_state == _thread_in_native_trans &&
699 frame_anchor()->walkable()) {
700 // The thread is transitioning from thread_in_native to another
701 // thread state. check_safepoint_and_suspend_for_native_trans()
702 // will force the thread to self-suspend. If it hasn't gotten
703 // there yet we may have caught the thread in-between the native
704 // code check above and the self-suspend. Lucky us. If we were
705 // called by wait_for_ext_suspend_completion(), then it
706 // will be doing the retries so we don't have to.
707 //
708 // Since we use the saved thread state in the if-statement above,
709 // there is a chance that the thread has already transitioned to
710 // _thread_blocked by the time we get here. In that case, we will
711 // make a single unnecessary pass through the logic below. This
712 // doesn't hurt anything since we still do the trans retry.
713
714 *bits |= 0x00004000;
715
716 // Once the thread leaves thread_in_native_trans for another
717 // thread state, we break out of this retry loop. We shouldn't
718 // need this flag to prevent us from getting back here, but
719 // sometimes paranoia is good.
720 did_trans_retry = true;
721
722 // We wait for the thread to transition to a more usable state.
723 for (int i = 1; i <= SuspendRetryCount; i++) {
724 // We used to do an "os::yield_all(i)" call here with the intention
725 // that yielding would increase on each retry. However, the parameter
726 // is ignored on Linux which means the yield didn't scale up. Waiting
727 // on the SR_lock below provides a much more predictable scale up for
728 // the delay. It also provides a simple/direct point to check for any
729 // safepoint requests from the VMThread
730
731 // temporarily drops SR_lock while doing wait with safepoint check
732 // (if we're a JavaThread - the WatcherThread can also call this)
733 // and increase delay with each retry
734 if (Thread::current()->is_Java_thread()) {
735 SR_lock()->wait(i * delay);
736 } else {
737 SR_lock()->wait_without_safepoint_check(i * delay);
738 }
739
740 // check the actual thread state instead of what we saved above
741 if (thread_state() != _thread_in_native_trans) {
742 // the thread has transitioned to another thread state so
743 // try all the checks (except this one) one more time.
744 do_trans_retry = true;
745 break;
746 }
747 } // end retry loop
748
749
750 }
751 } while (do_trans_retry);
752
753 *bits |= 0x00000010;
754 return false;
755 }
756
757 // Wait for an external suspend request to complete (or be cancelled).
758 // Returns true if the thread is externally suspended and false otherwise.
759 //
760 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
761 uint32_t *bits) {
762 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
763 false /* !called_by_wait */, bits);
764
765 // local flag copies to minimize SR_lock hold time
766 bool is_suspended;
767 bool pending;
768 uint32_t reset_bits;
769
770 // set a marker so is_ext_suspend_completed() knows we are the caller
771 *bits |= 0x00010000;
772
773 // We use reset_bits to reinitialize the bits value at the top of
774 // each retry loop. This allows the caller to make use of any
775 // unused bits for their own marking purposes.
776 reset_bits = *bits;
777
778 {
779 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
780 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
781 delay, bits);
782 pending = is_external_suspend();
783 }
784 // must release SR_lock to allow suspension to complete
785
786 if (!pending) {
787 // A cancelled suspend request is the only false return from
788 // is_ext_suspend_completed() that keeps us from entering the
789 // retry loop.
790 *bits |= 0x00020000;
791 return false;
792 }
793
794 if (is_suspended) {
795 *bits |= 0x00040000;
796 return true;
797 }
798
799 for (int i = 1; i <= retries; i++) {
800 *bits = reset_bits; // reinit to only track last retry
801
802 // We used to do an "os::yield_all(i)" call here with the intention
803 // that yielding would increase on each retry. However, the parameter
804 // is ignored on Linux which means the yield didn't scale up. Waiting
805 // on the SR_lock below provides a much more predictable scale up for
806 // the delay. It also provides a simple/direct point to check for any
807 // safepoint requests from the VMThread
808
809 {
810 Thread* t = Thread::current();
811 MonitorLocker ml(SR_lock(),
812 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
813 // wait with safepoint check (if we're a JavaThread - the WatcherThread
814 // can also call this) and increase delay with each retry
815 ml.wait(i * delay);
816
817 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
818 delay, bits);
819
820 // It is possible for the external suspend request to be cancelled
821 // (by a resume) before the actual suspend operation is completed.
822 // Refresh our local copy to see if we still need to wait.
823 pending = is_external_suspend();
824 }
825
826 if (!pending) {
827 // A cancelled suspend request is the only false return from
828 // is_ext_suspend_completed() that keeps us from staying in the
829 // retry loop.
830 *bits |= 0x00080000;
831 return false;
832 }
833
834 if (is_suspended) {
835 *bits |= 0x00100000;
836 return true;
837 }
838 } // end retry loop
839
840 // thread did not suspend after all our retries
841 *bits |= 0x00200000;
842 return false;
843 }
844
845 // Called from API entry points which perform stack walking. If the
846 // associated JavaThread is the current thread, then wait_for_suspend
847 // is not used. Otherwise, it determines if we should wait for the
848 // "other" thread to complete external suspension. (NOTE: in future
849 // releases the suspension mechanism should be reimplemented so this
850 // is not necessary.)
851 //
852 bool
853 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
854 if (this != JavaThread::current()) {
855 // "other" threads require special handling.
856 if (wait_for_suspend) {
857 // We are allowed to wait for the external suspend to complete
858 // so give the other thread a chance to get suspended.
859 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
860 SuspendRetryDelay, bits)) {
861 // Didn't make it so let the caller know.
862 return false;
863 }
864 }
865 // We aren't allowed to wait for the external suspend to complete
866 // so if the other thread isn't externally suspended we need to
867 // let the caller know.
868 else if (!is_ext_suspend_completed_with_lock(bits)) {
869 return false;
870 }
871 }
872
873 return true;
874 }
875
876 // GC Support
877 bool Thread::claim_par_threads_do(uintx claim_token) {
878 uintx token = _threads_do_token;
879 if (token != claim_token) {
880 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
881 if (res == token) {
882 return true;
883 }
884 guarantee(res == claim_token, "invariant");
885 }
886 return false;
887 }
888
889 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
890 if (active_handles() != NULL) {
891 active_handles()->oops_do(f);
892 }
893 // Do oop for ThreadShadow
894 f->do_oop((oop*)&_pending_exception);
895 handle_area()->oops_do(f);
896
897 // We scan thread local monitor lists here, and the remaining global
898 // monitors in ObjectSynchronizer::oops_do().
899 ObjectSynchronizer::thread_local_used_oops_do(this, f);
900 }
901
902 void Thread::metadata_handles_do(void f(Metadata*)) {
903 // Only walk the Handles in Thread.
904 if (metadata_handles() != NULL) {
905 for (int i = 0; i< metadata_handles()->length(); i++) {
906 f(metadata_handles()->at(i));
907 }
908 }
909 }
910
911 void Thread::print_on(outputStream* st, bool print_extended_info) const {
912 // get_priority assumes osthread initialized
913 if (osthread() != NULL) {
914 int os_prio;
915 if (os::get_native_priority(this, &os_prio) == OS_OK) {
916 st->print("os_prio=%d ", os_prio);
917 }
918
919 st->print("cpu=%.2fms ",
920 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
921 );
922 st->print("elapsed=%.2fs ",
923 _statistical_info.getElapsedTime() / 1000.0
924 );
925 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
926 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
927 st->print("allocated=" SIZE_FORMAT "%s ",
928 byte_size_in_proper_unit(allocated_bytes),
929 proper_unit_for_byte_size(allocated_bytes)
930 );
931 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
932 }
933
934 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
935 osthread()->print_on(st);
936 }
937 ThreadsSMRSupport::print_info_on(this, st);
938 st->print(" ");
939 debug_only(if (WizardMode) print_owned_locks_on(st);)
940 }
941
942 void Thread::print() const { print_on(tty); }
943
944 // Thread::print_on_error() is called by fatal error handler. Don't use
945 // any lock or allocate memory.
946 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
947 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
948
949 if (is_VM_thread()) { st->print("VMThread"); }
950 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
951 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
952 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
953 else { st->print("Thread"); }
954
955 if (is_Named_thread()) {
956 st->print(" \"%s\"", name());
957 }
958
959 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
960 p2i(stack_end()), p2i(stack_base()));
961
962 if (osthread()) {
963 st->print(" [id=%d]", osthread()->thread_id());
964 }
965
966 ThreadsSMRSupport::print_info_on(this, st);
967 }
968
969 void Thread::print_value_on(outputStream* st) const {
970 if (is_Named_thread()) {
971 st->print(" \"%s\" ", name());
972 }
973 st->print(INTPTR_FORMAT, p2i(this)); // print address
974 }
975
976 #ifdef ASSERT
977 void Thread::print_owned_locks_on(outputStream* st) const {
978 Mutex* cur = _owned_locks;
979 if (cur == NULL) {
980 st->print(" (no locks) ");
981 } else {
982 st->print_cr(" Locks owned:");
983 while (cur) {
984 cur->print_on(st);
985 cur = cur->next();
986 }
987 }
988 }
989
990 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
991 void Thread::check_possible_safepoint() {
992 if (!is_Java_thread()) return;
993
994 if (_no_safepoint_count > 0) {
995 print_owned_locks();
996 fatal("Possible safepoint reached by thread that does not allow it");
997 }
998 #ifdef CHECK_UNHANDLED_OOPS
999 // Clear unhandled oops in JavaThreads so we get a crash right away.
1000 clear_unhandled_oops();
1001 #endif // CHECK_UNHANDLED_OOPS
1002 }
1003
1004 void Thread::check_for_valid_safepoint_state() {
1005 if (!is_Java_thread()) return;
1006
1007 // Check NoSafepointVerifier, which is implied by locks taken that can be
1008 // shared with the VM thread. This makes sure that no locks with allow_vm_block
1009 // are held.
1010 check_possible_safepoint();
1011
1012 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1013 fatal("LEAF method calling lock?");
1014 }
1015
1016 if (GCALotAtAllSafepoints) {
1017 // We could enter a safepoint here and thus have a gc
1018 InterfaceSupport::check_gc_alot();
1019 }
1020 }
1021 #endif // ASSERT
1022
1023 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1024 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1025 // used for compilation in the future. If that change is made, the need for these methods
1026 // should be revisited, and they should be removed if possible.
1027
1028 bool Thread::is_lock_owned(address adr) const {
1029 return is_in_full_stack(adr);
1030 }
1031
1032 bool Thread::set_as_starting_thread() {
1033 assert(_starting_thread == NULL, "already initialized: "
1034 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1035 // NOTE: this must be called inside the main thread.
1036 DEBUG_ONLY(_starting_thread = this;)
1037 return os::create_main_thread((JavaThread*)this);
1038 }
1039
1040 static void initialize_class(Symbol* class_name, TRAPS) {
1041 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1042 InstanceKlass::cast(klass)->initialize(CHECK);
1043 }
1044
1045
1046 // Creates the initial ThreadGroup
1047 static Handle create_initial_thread_group(TRAPS) {
1048 Handle system_instance = JavaCalls::construct_new_instance(
1049 SystemDictionary::ThreadGroup_klass(),
1050 vmSymbols::void_method_signature(),
1051 CHECK_NH);
1052 Universe::set_system_thread_group(system_instance());
1053
1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1055 Handle main_instance = JavaCalls::construct_new_instance(
1056 SystemDictionary::ThreadGroup_klass(),
1057 vmSymbols::threadgroup_string_void_signature(),
1058 system_instance,
1059 string,
1060 CHECK_NH);
1061 return main_instance;
1062 }
1063
1064 // Creates the initial Thread
1065 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1066 TRAPS) {
1067 InstanceKlass* ik = SystemDictionary::Thread_klass();
1068 assert(ik->is_initialized(), "must be");
1069 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1070
1071 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1072 // constructor calls Thread.current(), which must be set here for the
1073 // initial thread.
1074 java_lang_Thread::set_thread(thread_oop(), thread);
1075 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1076 thread->set_threadObj(thread_oop());
1077
1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1079
1080 JavaValue result(T_VOID);
1081 JavaCalls::call_special(&result, thread_oop,
1082 ik,
1083 vmSymbols::object_initializer_name(),
1084 vmSymbols::threadgroup_string_void_signature(),
1085 thread_group,
1086 string,
1087 CHECK_NULL);
1088 return thread_oop();
1089 }
1090
1091 char java_runtime_name[128] = "";
1092 char java_runtime_version[128] = "";
1093 char java_runtime_vendor_version[128] = "";
1094 char java_runtime_vendor_vm_bug_url[128] = "";
1095
1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1097 static const char* get_java_runtime_name(TRAPS) {
1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1100 fieldDescriptor fd;
1101 bool found = k != NULL &&
1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1103 vmSymbols::string_signature(), &fd);
1104 if (found) {
1105 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1106 if (name_oop == NULL) {
1107 return NULL;
1108 }
1109 const char* name = java_lang_String::as_utf8_string(name_oop,
1110 java_runtime_name,
1111 sizeof(java_runtime_name));
1112 return name;
1113 } else {
1114 return NULL;
1115 }
1116 }
1117
1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1119 static const char* get_java_runtime_version(TRAPS) {
1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1122 fieldDescriptor fd;
1123 bool found = k != NULL &&
1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1125 vmSymbols::string_signature(), &fd);
1126 if (found) {
1127 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1128 if (name_oop == NULL) {
1129 return NULL;
1130 }
1131 const char* name = java_lang_String::as_utf8_string(name_oop,
1132 java_runtime_version,
1133 sizeof(java_runtime_version));
1134 return name;
1135 } else {
1136 return NULL;
1137 }
1138 }
1139
1140 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1141 static const char* get_java_runtime_vendor_version(TRAPS) {
1142 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1143 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1144 fieldDescriptor fd;
1145 bool found = k != NULL &&
1146 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1147 vmSymbols::string_signature(), &fd);
1148 if (found) {
1149 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1150 if (name_oop == NULL) {
1151 return NULL;
1152 }
1153 const char* name = java_lang_String::as_utf8_string(name_oop,
1154 java_runtime_vendor_version,
1155 sizeof(java_runtime_vendor_version));
1156 return name;
1157 } else {
1158 return NULL;
1159 }
1160 }
1161
1162 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1163 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1164 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1165 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1166 fieldDescriptor fd;
1167 bool found = k != NULL &&
1168 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1169 vmSymbols::string_signature(), &fd);
1170 if (found) {
1171 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1172 if (name_oop == NULL) {
1173 return NULL;
1174 }
1175 const char* name = java_lang_String::as_utf8_string(name_oop,
1176 java_runtime_vendor_vm_bug_url,
1177 sizeof(java_runtime_vendor_vm_bug_url));
1178 return name;
1179 } else {
1180 return NULL;
1181 }
1182 }
1183
1184 // General purpose hook into Java code, run once when the VM is initialized.
1185 // The Java library method itself may be changed independently from the VM.
1186 static void call_postVMInitHook(TRAPS) {
1187 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1188 if (klass != NULL) {
1189 JavaValue result(T_VOID);
1190 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1191 vmSymbols::void_method_signature(),
1192 CHECK);
1193 }
1194 }
1195
1196 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1197 bool daemon, TRAPS) {
1198 assert(thread_group.not_null(), "thread group should be specified");
1199 assert(threadObj() == NULL, "should only create Java thread object once");
1200
1201 InstanceKlass* ik = SystemDictionary::Thread_klass();
1202 assert(ik->is_initialized(), "must be");
1203 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1204
1205 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1206 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1207 // constructor calls Thread.current(), which must be set here.
1208 java_lang_Thread::set_thread(thread_oop(), this);
1209 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1210 set_threadObj(thread_oop());
1211
1212 JavaValue result(T_VOID);
1213 if (thread_name != NULL) {
1214 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1215 // Thread gets assigned specified name and null target
1216 JavaCalls::call_special(&result,
1217 thread_oop,
1218 ik,
1219 vmSymbols::object_initializer_name(),
1220 vmSymbols::threadgroup_string_void_signature(),
1221 thread_group,
1222 name,
1223 THREAD);
1224 } else {
1225 // Thread gets assigned name "Thread-nnn" and null target
1226 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1227 JavaCalls::call_special(&result,
1228 thread_oop,
1229 ik,
1230 vmSymbols::object_initializer_name(),
1231 vmSymbols::threadgroup_runnable_void_signature(),
1232 thread_group,
1233 Handle(),
1234 THREAD);
1235 }
1236
1237
1238 if (daemon) {
1239 java_lang_Thread::set_daemon(thread_oop());
1240 }
1241
1242 if (HAS_PENDING_EXCEPTION) {
1243 return;
1244 }
1245
1246 Klass* group = SystemDictionary::ThreadGroup_klass();
1247 Handle threadObj(THREAD, this->threadObj());
1248
1249 JavaCalls::call_special(&result,
1250 thread_group,
1251 group,
1252 vmSymbols::add_method_name(),
1253 vmSymbols::thread_void_signature(),
1254 threadObj, // Arg 1
1255 THREAD);
1256 }
1257
1258 // List of all NonJavaThreads and safe iteration over that list.
1259
1260 class NonJavaThread::List {
1261 public:
1262 NonJavaThread* volatile _head;
1263 SingleWriterSynchronizer _protect;
1264
1265 List() : _head(NULL), _protect() {}
1266 };
1267
1268 NonJavaThread::List NonJavaThread::_the_list;
1269
1270 NonJavaThread::Iterator::Iterator() :
1271 _protect_enter(_the_list._protect.enter()),
1272 _current(Atomic::load_acquire(&_the_list._head))
1273 {}
1274
1275 NonJavaThread::Iterator::~Iterator() {
1276 _the_list._protect.exit(_protect_enter);
1277 }
1278
1279 void NonJavaThread::Iterator::step() {
1280 assert(!end(), "precondition");
1281 _current = Atomic::load_acquire(&_current->_next);
1282 }
1283
1284 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1285 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1286 }
1287
1288 NonJavaThread::~NonJavaThread() { }
1289
1290 void NonJavaThread::add_to_the_list() {
1291 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1292 // Initialize BarrierSet-related data before adding to list.
1293 BarrierSet::barrier_set()->on_thread_attach(this);
1294 Atomic::release_store(&_next, _the_list._head);
1295 Atomic::release_store(&_the_list._head, this);
1296 }
1297
1298 void NonJavaThread::remove_from_the_list() {
1299 {
1300 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1301 // Cleanup BarrierSet-related data before removing from list.
1302 BarrierSet::barrier_set()->on_thread_detach(this);
1303 NonJavaThread* volatile* p = &_the_list._head;
1304 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1305 if (t == this) {
1306 *p = _next;
1307 break;
1308 }
1309 }
1310 }
1311 // Wait for any in-progress iterators. Concurrent synchronize is not
1312 // allowed, so do it while holding a dedicated lock. Outside and distinct
1313 // from NJTList_lock in case an iteration attempts to lock it.
1314 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1315 _the_list._protect.synchronize();
1316 _next = NULL; // Safe to drop the link now.
1317 }
1318
1319 void NonJavaThread::pre_run() {
1320 add_to_the_list();
1321
1322 // This is slightly odd in that NamedThread is a subclass, but
1323 // in fact name() is defined in Thread
1324 assert(this->name() != NULL, "thread name was not set before it was started");
1325 this->set_native_thread_name(this->name());
1326 }
1327
1328 void NonJavaThread::post_run() {
1329 JFR_ONLY(Jfr::on_thread_exit(this);)
1330 remove_from_the_list();
1331 // Ensure thread-local-storage is cleared before termination.
1332 Thread::clear_thread_current();
1333 }
1334
1335 // NamedThread -- non-JavaThread subclasses with multiple
1336 // uniquely named instances should derive from this.
1337 NamedThread::NamedThread() :
1338 NonJavaThread(),
1339 _name(NULL),
1340 _processed_thread(NULL),
1341 _gc_id(GCId::undefined())
1342 {}
1343
1344 NamedThread::~NamedThread() {
1345 FREE_C_HEAP_ARRAY(char, _name);
1346 }
1347
1348 void NamedThread::set_name(const char* format, ...) {
1349 guarantee(_name == NULL, "Only get to set name once.");
1350 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1351 va_list ap;
1352 va_start(ap, format);
1353 jio_vsnprintf(_name, max_name_len, format, ap);
1354 va_end(ap);
1355 }
1356
1357 void NamedThread::print_on(outputStream* st) const {
1358 st->print("\"%s\" ", name());
1359 Thread::print_on(st);
1360 st->cr();
1361 }
1362
1363
1364 // ======= WatcherThread ========
1365
1366 // The watcher thread exists to simulate timer interrupts. It should
1367 // be replaced by an abstraction over whatever native support for
1368 // timer interrupts exists on the platform.
1369
1370 WatcherThread* WatcherThread::_watcher_thread = NULL;
1371 bool WatcherThread::_startable = false;
1372 volatile bool WatcherThread::_should_terminate = false;
1373
1374 WatcherThread::WatcherThread() : NonJavaThread() {
1375 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1376 if (os::create_thread(this, os::watcher_thread)) {
1377 _watcher_thread = this;
1378
1379 // Set the watcher thread to the highest OS priority which should not be
1380 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1381 // is created. The only normal thread using this priority is the reference
1382 // handler thread, which runs for very short intervals only.
1383 // If the VMThread's priority is not lower than the WatcherThread profiling
1384 // will be inaccurate.
1385 os::set_priority(this, MaxPriority);
1386 if (!DisableStartThread) {
1387 os::start_thread(this);
1388 }
1389 }
1390 }
1391
1392 int WatcherThread::sleep() const {
1393 // The WatcherThread does not participate in the safepoint protocol
1394 // for the PeriodicTask_lock because it is not a JavaThread.
1395 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1396
1397 if (_should_terminate) {
1398 // check for termination before we do any housekeeping or wait
1399 return 0; // we did not sleep.
1400 }
1401
1402 // remaining will be zero if there are no tasks,
1403 // causing the WatcherThread to sleep until a task is
1404 // enrolled
1405 int remaining = PeriodicTask::time_to_wait();
1406 int time_slept = 0;
1407
1408 // we expect this to timeout - we only ever get unparked when
1409 // we should terminate or when a new task has been enrolled
1410 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1411
1412 jlong time_before_loop = os::javaTimeNanos();
1413
1414 while (true) {
1415 bool timedout = ml.wait(remaining);
1416 jlong now = os::javaTimeNanos();
1417
1418 if (remaining == 0) {
1419 // if we didn't have any tasks we could have waited for a long time
1420 // consider the time_slept zero and reset time_before_loop
1421 time_slept = 0;
1422 time_before_loop = now;
1423 } else {
1424 // need to recalculate since we might have new tasks in _tasks
1425 time_slept = (int) ((now - time_before_loop) / 1000000);
1426 }
1427
1428 // Change to task list or spurious wakeup of some kind
1429 if (timedout || _should_terminate) {
1430 break;
1431 }
1432
1433 remaining = PeriodicTask::time_to_wait();
1434 if (remaining == 0) {
1435 // Last task was just disenrolled so loop around and wait until
1436 // another task gets enrolled
1437 continue;
1438 }
1439
1440 remaining -= time_slept;
1441 if (remaining <= 0) {
1442 break;
1443 }
1444 }
1445
1446 return time_slept;
1447 }
1448
1449 void WatcherThread::run() {
1450 assert(this == watcher_thread(), "just checking");
1451
1452 this->set_active_handles(JNIHandleBlock::allocate_block());
1453 while (true) {
1454 assert(watcher_thread() == Thread::current(), "thread consistency check");
1455 assert(watcher_thread() == this, "thread consistency check");
1456
1457 // Calculate how long it'll be until the next PeriodicTask work
1458 // should be done, and sleep that amount of time.
1459 int time_waited = sleep();
1460
1461 if (VMError::is_error_reported()) {
1462 // A fatal error has happened, the error handler(VMError::report_and_die)
1463 // should abort JVM after creating an error log file. However in some
1464 // rare cases, the error handler itself might deadlock. Here periodically
1465 // check for error reporting timeouts, and if it happens, just proceed to
1466 // abort the VM.
1467
1468 // This code is in WatcherThread because WatcherThread wakes up
1469 // periodically so the fatal error handler doesn't need to do anything;
1470 // also because the WatcherThread is less likely to crash than other
1471 // threads.
1472
1473 for (;;) {
1474 // Note: we use naked sleep in this loop because we want to avoid using
1475 // any kind of VM infrastructure which may be broken at this point.
1476 if (VMError::check_timeout()) {
1477 // We hit error reporting timeout. Error reporting was interrupted and
1478 // will be wrapping things up now (closing files etc). Give it some more
1479 // time, then quit the VM.
1480 os::naked_short_sleep(200);
1481 // Print a message to stderr.
1482 fdStream err(defaultStream::output_fd());
1483 err.print_raw_cr("# [ timer expired, abort... ]");
1484 // skip atexit/vm_exit/vm_abort hooks
1485 os::die();
1486 }
1487
1488 // Wait a second, then recheck for timeout.
1489 os::naked_short_sleep(999);
1490 }
1491 }
1492
1493 if (_should_terminate) {
1494 // check for termination before posting the next tick
1495 break;
1496 }
1497
1498 PeriodicTask::real_time_tick(time_waited);
1499 }
1500
1501 // Signal that it is terminated
1502 {
1503 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1504 _watcher_thread = NULL;
1505 Terminator_lock->notify_all();
1506 }
1507 }
1508
1509 void WatcherThread::start() {
1510 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1511
1512 if (watcher_thread() == NULL && _startable) {
1513 _should_terminate = false;
1514 // Create the single instance of WatcherThread
1515 new WatcherThread();
1516 }
1517 }
1518
1519 void WatcherThread::make_startable() {
1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1521 _startable = true;
1522 }
1523
1524 void WatcherThread::stop() {
1525 {
1526 // Follow normal safepoint aware lock enter protocol since the
1527 // WatcherThread is stopped by another JavaThread.
1528 MutexLocker ml(PeriodicTask_lock);
1529 _should_terminate = true;
1530
1531 WatcherThread* watcher = watcher_thread();
1532 if (watcher != NULL) {
1533 // unpark the WatcherThread so it can see that it should terminate
1534 watcher->unpark();
1535 }
1536 }
1537
1538 MonitorLocker mu(Terminator_lock);
1539
1540 while (watcher_thread() != NULL) {
1541 // This wait should make safepoint checks, wait without a timeout,
1542 // and wait as a suspend-equivalent condition.
1543 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1544 }
1545 }
1546
1547 void WatcherThread::unpark() {
1548 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1549 PeriodicTask_lock->notify();
1550 }
1551
1552 void WatcherThread::print_on(outputStream* st) const {
1553 st->print("\"%s\" ", name());
1554 Thread::print_on(st);
1555 st->cr();
1556 }
1557
1558 // ======= JavaThread ========
1559
1560 #if INCLUDE_JVMCI
1561
1562 jlong* JavaThread::_jvmci_old_thread_counters;
1563
1564 bool jvmci_counters_include(JavaThread* thread) {
1565 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1566 }
1567
1568 void JavaThread::collect_counters(jlong* array, int length) {
1569 assert(length == JVMCICounterSize, "wrong value");
1570 for (int i = 0; i < length; i++) {
1571 array[i] = _jvmci_old_thread_counters[i];
1572 }
1573 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1574 if (jvmci_counters_include(tp)) {
1575 for (int i = 0; i < length; i++) {
1576 array[i] += tp->_jvmci_counters[i];
1577 }
1578 }
1579 }
1580 }
1581
1582 // Attempt to enlarge the array for per thread counters.
1583 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1584 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1585 if (old_counters == NULL) {
1586 old_counters = new_counters;
1587 memset(old_counters, 0, sizeof(jlong) * new_size);
1588 } else {
1589 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1590 new_counters[i] = old_counters[i];
1591 }
1592 if (new_size > current_size) {
1593 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1594 }
1595 FREE_C_HEAP_ARRAY(jlong, old_counters);
1596 }
1597 return new_counters;
1598 }
1599
1600 // Attempt to enlarge the array for per thread counters.
1601 void JavaThread::resize_counters(int current_size, int new_size) {
1602 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1603 }
1604
1605 class VM_JVMCIResizeCounters : public VM_Operation {
1606 private:
1607 int _new_size;
1608
1609 public:
1610 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1611 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1612 bool allow_nested_vm_operations() const { return true; }
1613 void doit() {
1614 // Resize the old thread counters array
1615 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1616 JavaThread::_jvmci_old_thread_counters = new_counters;
1617
1618 // Now resize each threads array
1619 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1620 tp->resize_counters(JVMCICounterSize, _new_size);
1621 }
1622 JVMCICounterSize = _new_size;
1623 }
1624 };
1625
1626 void JavaThread::resize_all_jvmci_counters(int new_size) {
1627 VM_JVMCIResizeCounters op(new_size);
1628 VMThread::execute(&op);
1629 }
1630
1631 #endif // INCLUDE_JVMCI
1632
1633 // A JavaThread is a normal Java thread
1634
1635 void JavaThread::initialize() {
1636 // Initialize fields
1637
1638 set_saved_exception_pc(NULL);
1639 set_threadObj(NULL);
1640 _anchor.clear();
1641 set_entry_point(NULL);
1642 set_jni_functions(jni_functions());
1643 set_callee_target(NULL);
1644 set_vm_result(NULL);
1645 set_vm_result_2(NULL);
1646 set_vframe_array_head(NULL);
1647 set_vframe_array_last(NULL);
1648 set_deferred_locals(NULL);
1649 set_deopt_mark(NULL);
1650 set_deopt_compiled_method(NULL);
1651 set_monitor_chunks(NULL);
1652 _on_thread_list = false;
1653 _thread_state = _thread_new;
1654 _terminated = _not_terminated;
1655 _array_for_gc = NULL;
1656 _suspend_equivalent = false;
1657 _in_deopt_handler = 0;
1658 _doing_unsafe_access = false;
1659 _stack_guard_state = stack_guard_unused;
1660 #if INCLUDE_JVMCI
1661 _pending_monitorenter = false;
1662 _pending_deoptimization = -1;
1663 _pending_failed_speculation = 0;
1664 _pending_transfer_to_interpreter = false;
1665 _in_retryable_allocation = false;
1666 _jvmci._alternate_call_target = NULL;
1667 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1668 _jvmci_counters = NULL;
1669 if (JVMCICounterSize > 0) {
1670 resize_counters(0, (int) JVMCICounterSize);
1671 }
1672 #endif // INCLUDE_JVMCI
1673 _reserved_stack_activation = NULL; // stack base not known yet
1674 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1675 _exception_pc = 0;
1676 _exception_handler_pc = 0;
1677 _is_method_handle_return = 0;
1678 _jvmti_thread_state= NULL;
1679 _should_post_on_exceptions_flag = JNI_FALSE;
1680 _interp_only_mode = 0;
1681 _special_runtime_exit_condition = _no_async_condition;
1682 _pending_async_exception = NULL;
1683 _thread_stat = NULL;
1684 _thread_stat = new ThreadStatistics();
1685 _jni_active_critical = 0;
1686 _pending_jni_exception_check_fn = NULL;
1687 _do_not_unlock_if_synchronized = false;
1688 _cached_monitor_info = NULL;
1689 _parker = Parker::Allocate(this);
1690 _SleepEvent = ParkEvent::Allocate(this);
1691 // Setup safepoint state info for this thread
1692 ThreadSafepointState::create(this);
1693 _handshake.set_handshakee(this);
1694
1695 debug_only(_java_call_counter = 0);
1696
1697 // JVMTI PopFrame support
1698 _popframe_condition = popframe_inactive;
1699 _popframe_preserved_args = NULL;
1700 _popframe_preserved_args_size = 0;
1701 _frames_to_pop_failed_realloc = 0;
1702
1703 SafepointMechanism::initialize_header(this);
1704
1705 _class_to_be_initialized = NULL;
1706
1707 pd_initialize();
1708 }
1709
1710 JavaThread::JavaThread(bool is_attaching_via_jni) :
1711 Thread() {
1712 initialize();
1713 if (is_attaching_via_jni) {
1714 _jni_attach_state = _attaching_via_jni;
1715 } else {
1716 _jni_attach_state = _not_attaching_via_jni;
1717 }
1718 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1719 }
1720
1721
1722 // interrupt support
1723
1724 void JavaThread::interrupt() {
1725 debug_only(check_for_dangling_thread_pointer(this);)
1726
1727 // For Windows _interrupt_event
1728 osthread()->set_interrupted(true);
1729
1730 // For Thread.sleep
1731 _SleepEvent->unpark();
1732
1733 // For JSR166 LockSupport.park
1734 parker()->unpark();
1735
1736 // For ObjectMonitor and JvmtiRawMonitor
1737 _ParkEvent->unpark();
1738 }
1739
1740
1741 bool JavaThread::is_interrupted(bool clear_interrupted) {
1742 debug_only(check_for_dangling_thread_pointer(this);)
1743
1744 if (threadObj() == NULL) {
1745 // If there is no j.l.Thread then it is impossible to have
1746 // been interrupted. We can find NULL during VM initialization
1747 // or when a JNI thread is still in the process of attaching.
1748 // In such cases this must be the current thread.
1749 assert(this == Thread::current(), "invariant");
1750 return false;
1751 }
1752
1753 bool interrupted = java_lang_Thread::interrupted(threadObj());
1754
1755 // NOTE that since there is no "lock" around the interrupt and
1756 // is_interrupted operations, there is the possibility that the
1757 // interrupted flag will be "false" but that the
1758 // low-level events will be in the signaled state. This is
1759 // intentional. The effect of this is that Object.wait() and
1760 // LockSupport.park() will appear to have a spurious wakeup, which
1761 // is allowed and not harmful, and the possibility is so rare that
1762 // it is not worth the added complexity to add yet another lock.
1763 // For the sleep event an explicit reset is performed on entry
1764 // to JavaThread::sleep, so there is no early return. It has also been
1765 // recommended not to put the interrupted flag into the "event"
1766 // structure because it hides the issue.
1767 // Also, because there is no lock, we must only clear the interrupt
1768 // state if we are going to report that we were interrupted; otherwise
1769 // an interrupt that happens just after we read the field would be lost.
1770 if (interrupted && clear_interrupted) {
1771 assert(this == Thread::current(), "only the current thread can clear");
1772 java_lang_Thread::set_interrupted(threadObj(), false);
1773 osthread()->set_interrupted(false);
1774 }
1775
1776 return interrupted;
1777 }
1778
1779 bool JavaThread::reguard_stack(address cur_sp) {
1780 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1781 && _stack_guard_state != stack_guard_reserved_disabled) {
1782 return true; // Stack already guarded or guard pages not needed.
1783 }
1784
1785 if (register_stack_overflow()) {
1786 // For those architectures which have separate register and
1787 // memory stacks, we must check the register stack to see if
1788 // it has overflowed.
1789 return false;
1790 }
1791
1792 // Java code never executes within the yellow zone: the latter is only
1793 // there to provoke an exception during stack banging. If java code
1794 // is executing there, either StackShadowPages should be larger, or
1795 // some exception code in c1, c2 or the interpreter isn't unwinding
1796 // when it should.
1797 guarantee(cur_sp > stack_reserved_zone_base(),
1798 "not enough space to reguard - increase StackShadowPages");
1799 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1800 enable_stack_yellow_reserved_zone();
1801 if (reserved_stack_activation() != stack_base()) {
1802 set_reserved_stack_activation(stack_base());
1803 }
1804 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1805 set_reserved_stack_activation(stack_base());
1806 enable_stack_reserved_zone();
1807 }
1808 return true;
1809 }
1810
1811 bool JavaThread::reguard_stack(void) {
1812 return reguard_stack(os::current_stack_pointer());
1813 }
1814
1815 void JavaThread::block_if_vm_exited() {
1816 if (_terminated == _vm_exited) {
1817 // _vm_exited is set at safepoint, and Threads_lock is never released
1818 // we will block here forever.
1819 // Here we can be doing a jump from a safe state to an unsafe state without
1820 // proper transition, but it happens after the final safepoint has begun.
1821 set_thread_state(_thread_in_vm);
1822 Threads_lock->lock();
1823 ShouldNotReachHere();
1824 }
1825 }
1826
1827
1828 // Remove this ifdef when C1 is ported to the compiler interface.
1829 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1830 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1831
1832 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1833 Thread() {
1834 initialize();
1835 _jni_attach_state = _not_attaching_via_jni;
1836 set_entry_point(entry_point);
1837 // Create the native thread itself.
1838 // %note runtime_23
1839 os::ThreadType thr_type = os::java_thread;
1840 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1841 os::java_thread;
1842 os::create_thread(this, thr_type, stack_sz);
1843 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1844 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1845 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1846 // the exception consists of creating the exception object & initializing it, initialization
1847 // will leave the VM via a JavaCall and then all locks must be unlocked).
1848 //
1849 // The thread is still suspended when we reach here. Thread must be explicit started
1850 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1851 // by calling Threads:add. The reason why this is not done here, is because the thread
1852 // object must be fully initialized (take a look at JVM_Start)
1853 }
1854
1855 JavaThread::~JavaThread() {
1856
1857 // JSR166 -- return the parker to the free list
1858 Parker::Release(_parker);
1859 _parker = NULL;
1860
1861 // Return the sleep event to the free list
1862 ParkEvent::Release(_SleepEvent);
1863 _SleepEvent = NULL;
1864
1865 // Free any remaining previous UnrollBlock
1866 vframeArray* old_array = vframe_array_last();
1867
1868 if (old_array != NULL) {
1869 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1870 old_array->set_unroll_block(NULL);
1871 delete old_info;
1872 delete old_array;
1873 }
1874
1875 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1876 if (deferred != NULL) {
1877 // This can only happen if thread is destroyed before deoptimization occurs.
1878 assert(deferred->length() != 0, "empty array!");
1879 do {
1880 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1881 deferred->remove_at(0);
1882 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1883 delete dlv;
1884 } while (deferred->length() != 0);
1885 delete deferred;
1886 }
1887
1888 // All Java related clean up happens in exit
1889 ThreadSafepointState::destroy(this);
1890 if (_thread_stat != NULL) delete _thread_stat;
1891
1892 #if INCLUDE_JVMCI
1893 if (JVMCICounterSize > 0) {
1894 if (jvmci_counters_include(this)) {
1895 for (int i = 0; i < JVMCICounterSize; i++) {
1896 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1897 }
1898 }
1899 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1900 }
1901 #endif // INCLUDE_JVMCI
1902 }
1903
1904
1905 // First JavaThread specific code executed by a new Java thread.
1906 void JavaThread::pre_run() {
1907 // empty - see comments in run()
1908 }
1909
1910 // The main routine called by a new Java thread. This isn't overridden
1911 // by subclasses, instead different subclasses define a different "entry_point"
1912 // which defines the actual logic for that kind of thread.
1913 void JavaThread::run() {
1914 // initialize thread-local alloc buffer related fields
1915 this->initialize_tlab();
1916
1917 // Used to test validity of stack trace backs.
1918 // This can't be moved into pre_run() else we invalidate
1919 // the requirement that thread_main_inner is lower on
1920 // the stack. Consequently all the initialization logic
1921 // stays here in run() rather than pre_run().
1922 this->record_base_of_stack_pointer();
1923
1924 this->create_stack_guard_pages();
1925
1926 this->cache_global_variables();
1927
1928 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1929 // in the VM. Change thread state from _thread_new to _thread_in_vm
1930 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1931 // Before a thread is on the threads list it is always safe, so after leaving the
1932 // _thread_new we should emit a instruction barrier. The distance to modified code
1933 // from here is probably far enough, but this is consistent and safe.
1934 OrderAccess::cross_modify_fence();
1935
1936 assert(JavaThread::current() == this, "sanity check");
1937 assert(!Thread::current()->owns_locks(), "sanity check");
1938
1939 DTRACE_THREAD_PROBE(start, this);
1940
1941 // This operation might block. We call that after all safepoint checks for a new thread has
1942 // been completed.
1943 this->set_active_handles(JNIHandleBlock::allocate_block());
1944
1945 if (JvmtiExport::should_post_thread_life()) {
1946 JvmtiExport::post_thread_start(this);
1947
1948 }
1949
1950 // We call another function to do the rest so we are sure that the stack addresses used
1951 // from there will be lower than the stack base just computed.
1952 thread_main_inner();
1953 }
1954
1955 void JavaThread::thread_main_inner() {
1956 assert(JavaThread::current() == this, "sanity check");
1957 assert(this->threadObj() != NULL, "just checking");
1958
1959 // Execute thread entry point unless this thread has a pending exception
1960 // or has been stopped before starting.
1961 // Note: Due to JVM_StopThread we can have pending exceptions already!
1962 if (!this->has_pending_exception() &&
1963 !java_lang_Thread::is_stillborn(this->threadObj())) {
1964 {
1965 ResourceMark rm(this);
1966 this->set_native_thread_name(this->get_thread_name());
1967 }
1968 HandleMark hm(this);
1969 this->entry_point()(this, this);
1970 }
1971
1972 DTRACE_THREAD_PROBE(stop, this);
1973
1974 // Cleanup is handled in post_run()
1975 }
1976
1977 // Shared teardown for all JavaThreads
1978 void JavaThread::post_run() {
1979 this->exit(false);
1980 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1981 // for any shared tear-down.
1982 this->smr_delete();
1983 }
1984
1985 static void ensure_join(JavaThread* thread) {
1986 // We do not need to grab the Threads_lock, since we are operating on ourself.
1987 Handle threadObj(thread, thread->threadObj());
1988 assert(threadObj.not_null(), "java thread object must exist");
1989 ObjectLocker lock(threadObj, thread);
1990 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1991 thread->clear_pending_exception();
1992 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1993 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1994 // Clear the native thread instance - this makes isAlive return false and allows the join()
1995 // to complete once we've done the notify_all below
1996 java_lang_Thread::set_thread(threadObj(), NULL);
1997 lock.notify_all(thread);
1998 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1999 thread->clear_pending_exception();
2000 }
2001
2002 static bool is_daemon(oop threadObj) {
2003 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
2004 }
2005
2006 // For any new cleanup additions, please check to see if they need to be applied to
2007 // cleanup_failed_attach_current_thread as well.
2008 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2009 assert(this == JavaThread::current(), "thread consistency check");
2010
2011 elapsedTimer _timer_exit_phase1;
2012 elapsedTimer _timer_exit_phase2;
2013 elapsedTimer _timer_exit_phase3;
2014 elapsedTimer _timer_exit_phase4;
2015
2016 if (log_is_enabled(Debug, os, thread, timer)) {
2017 _timer_exit_phase1.start();
2018 }
2019
2020 HandleMark hm(this);
2021 Handle uncaught_exception(this, this->pending_exception());
2022 this->clear_pending_exception();
2023 Handle threadObj(this, this->threadObj());
2024 assert(threadObj.not_null(), "Java thread object should be created");
2025
2026 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2027 {
2028 EXCEPTION_MARK;
2029
2030 CLEAR_PENDING_EXCEPTION;
2031 }
2032 if (!destroy_vm) {
2033 if (uncaught_exception.not_null()) {
2034 EXCEPTION_MARK;
2035 // Call method Thread.dispatchUncaughtException().
2036 Klass* thread_klass = SystemDictionary::Thread_klass();
2037 JavaValue result(T_VOID);
2038 JavaCalls::call_virtual(&result,
2039 threadObj, thread_klass,
2040 vmSymbols::dispatchUncaughtException_name(),
2041 vmSymbols::throwable_void_signature(),
2042 uncaught_exception,
2043 THREAD);
2044 if (HAS_PENDING_EXCEPTION) {
2045 ResourceMark rm(this);
2046 jio_fprintf(defaultStream::error_stream(),
2047 "\nException: %s thrown from the UncaughtExceptionHandler"
2048 " in thread \"%s\"\n",
2049 pending_exception()->klass()->external_name(),
2050 get_thread_name());
2051 CLEAR_PENDING_EXCEPTION;
2052 }
2053 }
2054 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2055
2056 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2057 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2058 // is deprecated anyhow.
2059 if (!is_Compiler_thread()) {
2060 int count = 3;
2061 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2062 EXCEPTION_MARK;
2063 JavaValue result(T_VOID);
2064 Klass* thread_klass = SystemDictionary::Thread_klass();
2065 JavaCalls::call_virtual(&result,
2066 threadObj, thread_klass,
2067 vmSymbols::exit_method_name(),
2068 vmSymbols::void_method_signature(),
2069 THREAD);
2070 CLEAR_PENDING_EXCEPTION;
2071 }
2072 }
2073 // notify JVMTI
2074 if (JvmtiExport::should_post_thread_life()) {
2075 JvmtiExport::post_thread_end(this);
2076 }
2077
2078 // We have notified the agents that we are exiting, before we go on,
2079 // we must check for a pending external suspend request and honor it
2080 // in order to not surprise the thread that made the suspend request.
2081 while (true) {
2082 {
2083 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2084 if (!is_external_suspend()) {
2085 set_terminated(_thread_exiting);
2086 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2087 break;
2088 }
2089 // Implied else:
2090 // Things get a little tricky here. We have a pending external
2091 // suspend request, but we are holding the SR_lock so we
2092 // can't just self-suspend. So we temporarily drop the lock
2093 // and then self-suspend.
2094 }
2095
2096 ThreadBlockInVM tbivm(this);
2097 java_suspend_self();
2098
2099 // We're done with this suspend request, but we have to loop around
2100 // and check again. Eventually we will get SR_lock without a pending
2101 // external suspend request and will be able to mark ourselves as
2102 // exiting.
2103 }
2104 // no more external suspends are allowed at this point
2105 } else {
2106 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2107 // before_exit() has already posted JVMTI THREAD_END events
2108 }
2109
2110 if (log_is_enabled(Debug, os, thread, timer)) {
2111 _timer_exit_phase1.stop();
2112 _timer_exit_phase2.start();
2113 }
2114
2115 // Capture daemon status before the thread is marked as terminated.
2116 bool daemon = is_daemon(threadObj());
2117
2118 // Notify waiters on thread object. This has to be done after exit() is called
2119 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2120 // group should have the destroyed bit set before waiters are notified).
2121 ensure_join(this);
2122 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2123
2124 if (log_is_enabled(Debug, os, thread, timer)) {
2125 _timer_exit_phase2.stop();
2126 _timer_exit_phase3.start();
2127 }
2128 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2129 // held by this thread must be released. The spec does not distinguish
2130 // between JNI-acquired and regular Java monitors. We can only see
2131 // regular Java monitors here if monitor enter-exit matching is broken.
2132 //
2133 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2134 // ObjectSynchronizer::release_monitors_owned_by_thread().
2135 if (exit_type == jni_detach) {
2136 // Sanity check even though JNI DetachCurrentThread() would have
2137 // returned JNI_ERR if there was a Java frame. JavaThread exit
2138 // should be done executing Java code by the time we get here.
2139 assert(!this->has_last_Java_frame(),
2140 "should not have a Java frame when detaching or exiting");
2141 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2142 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2143 }
2144
2145 // These things needs to be done while we are still a Java Thread. Make sure that thread
2146 // is in a consistent state, in case GC happens
2147 JFR_ONLY(Jfr::on_thread_exit(this);)
2148
2149 if (active_handles() != NULL) {
2150 JNIHandleBlock* block = active_handles();
2151 set_active_handles(NULL);
2152 JNIHandleBlock::release_block(block);
2153 }
2154
2155 if (free_handle_block() != NULL) {
2156 JNIHandleBlock* block = free_handle_block();
2157 set_free_handle_block(NULL);
2158 JNIHandleBlock::release_block(block);
2159 }
2160
2161 // These have to be removed while this is still a valid thread.
2162 remove_stack_guard_pages();
2163
2164 if (UseTLAB) {
2165 tlab().retire();
2166 }
2167
2168 if (JvmtiEnv::environments_might_exist()) {
2169 JvmtiExport::cleanup_thread(this);
2170 }
2171
2172 // We must flush any deferred card marks and other various GC barrier
2173 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2174 // before removing a thread from the list of active threads.
2175 BarrierSet::barrier_set()->on_thread_detach(this);
2176
2177 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2178 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2179 os::current_thread_id());
2180
2181 if (log_is_enabled(Debug, os, thread, timer)) {
2182 _timer_exit_phase3.stop();
2183 _timer_exit_phase4.start();
2184 }
2185 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2186 Threads::remove(this, daemon);
2187
2188 if (log_is_enabled(Debug, os, thread, timer)) {
2189 _timer_exit_phase4.stop();
2190 ResourceMark rm(this);
2191 log_debug(os, thread, timer)("name='%s'"
2192 ", exit-phase1=" JLONG_FORMAT
2193 ", exit-phase2=" JLONG_FORMAT
2194 ", exit-phase3=" JLONG_FORMAT
2195 ", exit-phase4=" JLONG_FORMAT,
2196 get_thread_name(),
2197 _timer_exit_phase1.milliseconds(),
2198 _timer_exit_phase2.milliseconds(),
2199 _timer_exit_phase3.milliseconds(),
2200 _timer_exit_phase4.milliseconds());
2201 }
2202 }
2203
2204 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2205 if (active_handles() != NULL) {
2206 JNIHandleBlock* block = active_handles();
2207 set_active_handles(NULL);
2208 JNIHandleBlock::release_block(block);
2209 }
2210
2211 if (free_handle_block() != NULL) {
2212 JNIHandleBlock* block = free_handle_block();
2213 set_free_handle_block(NULL);
2214 JNIHandleBlock::release_block(block);
2215 }
2216
2217 // These have to be removed while this is still a valid thread.
2218 remove_stack_guard_pages();
2219
2220 if (UseTLAB) {
2221 tlab().retire();
2222 }
2223
2224 BarrierSet::barrier_set()->on_thread_detach(this);
2225
2226 Threads::remove(this, is_daemon);
2227 this->smr_delete();
2228 }
2229
2230 JavaThread* JavaThread::active() {
2231 Thread* thread = Thread::current();
2232 if (thread->is_Java_thread()) {
2233 return (JavaThread*) thread;
2234 } else {
2235 assert(thread->is_VM_thread(), "this must be a vm thread");
2236 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2237 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2238 assert(ret->is_Java_thread(), "must be a Java thread");
2239 return ret;
2240 }
2241 }
2242
2243 bool JavaThread::is_lock_owned(address adr) const {
2244 if (Thread::is_lock_owned(adr)) return true;
2245
2246 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2247 if (chunk->contains(adr)) return true;
2248 }
2249
2250 return false;
2251 }
2252
2253
2254 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2255 chunk->set_next(monitor_chunks());
2256 set_monitor_chunks(chunk);
2257 }
2258
2259 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2260 guarantee(monitor_chunks() != NULL, "must be non empty");
2261 if (monitor_chunks() == chunk) {
2262 set_monitor_chunks(chunk->next());
2263 } else {
2264 MonitorChunk* prev = monitor_chunks();
2265 while (prev->next() != chunk) prev = prev->next();
2266 prev->set_next(chunk->next());
2267 }
2268 }
2269
2270 // JVM support.
2271
2272 // Note: this function shouldn't block if it's called in
2273 // _thread_in_native_trans state (such as from
2274 // check_special_condition_for_native_trans()).
2275 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2276
2277 if (has_last_Java_frame() && has_async_condition()) {
2278 // If we are at a polling page safepoint (not a poll return)
2279 // then we must defer async exception because live registers
2280 // will be clobbered by the exception path. Poll return is
2281 // ok because the call we a returning from already collides
2282 // with exception handling registers and so there is no issue.
2283 // (The exception handling path kills call result registers but
2284 // this is ok since the exception kills the result anyway).
2285
2286 if (is_at_poll_safepoint()) {
2287 // if the code we are returning to has deoptimized we must defer
2288 // the exception otherwise live registers get clobbered on the
2289 // exception path before deoptimization is able to retrieve them.
2290 //
2291 RegisterMap map(this, false);
2292 frame caller_fr = last_frame().sender(&map);
2293 assert(caller_fr.is_compiled_frame(), "what?");
2294 if (caller_fr.is_deoptimized_frame()) {
2295 log_info(exceptions)("deferred async exception at compiled safepoint");
2296 return;
2297 }
2298 }
2299 }
2300
2301 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2302 if (condition == _no_async_condition) {
2303 // Conditions have changed since has_special_runtime_exit_condition()
2304 // was called:
2305 // - if we were here only because of an external suspend request,
2306 // then that was taken care of above (or cancelled) so we are done
2307 // - if we were here because of another async request, then it has
2308 // been cleared between the has_special_runtime_exit_condition()
2309 // and now so again we are done
2310 return;
2311 }
2312
2313 // Check for pending async. exception
2314 if (_pending_async_exception != NULL) {
2315 // Only overwrite an already pending exception, if it is not a threadDeath.
2316 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2317
2318 // We cannot call Exceptions::_throw(...) here because we cannot block
2319 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2320
2321 LogTarget(Info, exceptions) lt;
2322 if (lt.is_enabled()) {
2323 ResourceMark rm;
2324 LogStream ls(lt);
2325 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2326 if (has_last_Java_frame()) {
2327 frame f = last_frame();
2328 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2329 }
2330 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2331 }
2332 _pending_async_exception = NULL;
2333 clear_has_async_exception();
2334 }
2335 }
2336
2337 if (check_unsafe_error &&
2338 condition == _async_unsafe_access_error && !has_pending_exception()) {
2339 condition = _no_async_condition; // done
2340 switch (thread_state()) {
2341 case _thread_in_vm: {
2342 JavaThread* THREAD = this;
2343 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2344 }
2345 case _thread_in_native: {
2346 ThreadInVMfromNative tiv(this);
2347 JavaThread* THREAD = this;
2348 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2349 }
2350 case _thread_in_Java: {
2351 ThreadInVMfromJava tiv(this);
2352 JavaThread* THREAD = this;
2353 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2354 }
2355 default:
2356 ShouldNotReachHere();
2357 }
2358 }
2359
2360 assert(condition == _no_async_condition || has_pending_exception() ||
2361 (!check_unsafe_error && condition == _async_unsafe_access_error),
2362 "must have handled the async condition, if no exception");
2363 }
2364
2365 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2366
2367 // Check for pending external suspend.
2368 if (is_external_suspend_with_lock()) {
2369 frame_anchor()->make_walkable(this);
2370 java_suspend_self_with_safepoint_check();
2371 }
2372
2373 // We might be here for reasons in addition to the self-suspend request
2374 // so check for other async requests.
2375 if (check_asyncs) {
2376 check_and_handle_async_exceptions();
2377 }
2378
2379 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2380 }
2381
2382 void JavaThread::send_thread_stop(oop java_throwable) {
2383 ResourceMark rm;
2384 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread");
2385
2386 // Do not throw asynchronous exceptions against the compiler thread
2387 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2388 if (!can_call_java()) return;
2389
2390 {
2391 // Actually throw the Throwable against the target Thread - however
2392 // only if there is no thread death exception installed already.
2393 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2394 // If the topmost frame is a runtime stub, then we are calling into
2395 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2396 // must deoptimize the caller before continuing, as the compiled exception handler table
2397 // may not be valid
2398 if (has_last_Java_frame()) {
2399 frame f = last_frame();
2400 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2401 RegisterMap reg_map(this, false);
2402 frame compiled_frame = f.sender(®_map);
2403 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2404 Deoptimization::deoptimize(this, compiled_frame);
2405 }
2406 }
2407 }
2408
2409 // Set async. pending exception in thread.
2410 set_pending_async_exception(java_throwable);
2411
2412 if (log_is_enabled(Info, exceptions)) {
2413 ResourceMark rm;
2414 log_info(exceptions)("Pending Async. exception installed of type: %s",
2415 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2416 }
2417 // for AbortVMOnException flag
2418 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2419 }
2420 }
2421
2422
2423 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2424 java_lang_Thread::set_interrupted(threadObj(), true);
2425 this->interrupt();
2426 }
2427
2428 // External suspension mechanism.
2429 //
2430 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2431 // to any VM_locks and it is at a transition
2432 // Self-suspension will happen on the transition out of the vm.
2433 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2434 //
2435 // Guarantees on return:
2436 // + Target thread will not execute any new bytecode (that's why we need to
2437 // force a safepoint)
2438 // + Target thread will not enter any new monitors
2439 //
2440 void JavaThread::java_suspend() {
2441 ThreadsListHandle tlh;
2442 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2443 return;
2444 }
2445
2446 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2447 if (!is_external_suspend()) {
2448 // a racing resume has cancelled us; bail out now
2449 return;
2450 }
2451
2452 // suspend is done
2453 uint32_t debug_bits = 0;
2454 // Warning: is_ext_suspend_completed() may temporarily drop the
2455 // SR_lock to allow the thread to reach a stable thread state if
2456 // it is currently in a transient thread state.
2457 if (is_ext_suspend_completed(false /* !called_by_wait */,
2458 SuspendRetryDelay, &debug_bits)) {
2459 return;
2460 }
2461 }
2462
2463 if (Thread::current() == this) {
2464 // Safely self-suspend.
2465 // If we don't do this explicitly it will implicitly happen
2466 // before we transition back to Java, and on some other thread-state
2467 // transition paths, but not as we exit a JVM TI SuspendThread call.
2468 // As SuspendThread(current) must not return (until resumed) we must
2469 // self-suspend here.
2470 ThreadBlockInVM tbivm(this);
2471 java_suspend_self();
2472 } else {
2473 VM_ThreadSuspend vm_suspend;
2474 VMThread::execute(&vm_suspend);
2475 }
2476 }
2477
2478 // Part II of external suspension.
2479 // A JavaThread self suspends when it detects a pending external suspend
2480 // request. This is usually on transitions. It is also done in places
2481 // where continuing to the next transition would surprise the caller,
2482 // e.g., monitor entry.
2483 //
2484 // Returns the number of times that the thread self-suspended.
2485 //
2486 // Note: DO NOT call java_suspend_self() when you just want to block current
2487 // thread. java_suspend_self() is the second stage of cooperative
2488 // suspension for external suspend requests and should only be used
2489 // to complete an external suspend request.
2490 //
2491 int JavaThread::java_suspend_self() {
2492 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2493 int ret = 0;
2494
2495 // we are in the process of exiting so don't suspend
2496 if (is_exiting()) {
2497 clear_external_suspend();
2498 return ret;
2499 }
2500
2501 assert(_anchor.walkable() ||
2502 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2503 "must have walkable stack");
2504
2505 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2506
2507 assert(!this->is_ext_suspended(),
2508 "a thread trying to self-suspend should not already be suspended");
2509
2510 if (this->is_suspend_equivalent()) {
2511 // If we are self-suspending as a result of the lifting of a
2512 // suspend equivalent condition, then the suspend_equivalent
2513 // flag is not cleared until we set the ext_suspended flag so
2514 // that wait_for_ext_suspend_completion() returns consistent
2515 // results.
2516 this->clear_suspend_equivalent();
2517 }
2518
2519 // A racing resume may have cancelled us before we grabbed SR_lock
2520 // above. Or another external suspend request could be waiting for us
2521 // by the time we return from SR_lock()->wait(). The thread
2522 // that requested the suspension may already be trying to walk our
2523 // stack and if we return now, we can change the stack out from under
2524 // it. This would be a "bad thing (TM)" and cause the stack walker
2525 // to crash. We stay self-suspended until there are no more pending
2526 // external suspend requests.
2527 while (is_external_suspend()) {
2528 ret++;
2529 this->set_ext_suspended();
2530
2531 // _ext_suspended flag is cleared by java_resume()
2532 while (is_ext_suspended()) {
2533 ml.wait();
2534 }
2535 }
2536 return ret;
2537 }
2538
2539 // Helper routine to set up the correct thread state before calling java_suspend_self.
2540 // This is called when regular thread-state transition helpers can't be used because
2541 // we can be in various states, in particular _thread_in_native_trans.
2542 // Because this thread is external suspended the safepoint code will count it as at
2543 // a safepoint, regardless of what its actual current thread-state is. But
2544 // is_ext_suspend_completed() may be waiting to see a thread transition from
2545 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2546 // to _thread_blocked. The problem with setting thread state directly is that a
2547 // safepoint could happen just after java_suspend_self() returns after being resumed,
2548 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2549 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2550 // However, not all initial-states are allowed when performing a safepoint check, as we
2551 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2552 // only _thread_in_native is possible when executing this code (based on our two callers).
2553 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2554 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2555 // and so we don't need the explicit safepoint check.
2556
2557 void JavaThread::java_suspend_self_with_safepoint_check() {
2558 assert(this == Thread::current(), "invariant");
2559 JavaThreadState state = thread_state();
2560 set_thread_state(_thread_blocked);
2561 java_suspend_self();
2562 set_thread_state_fence(state);
2563 // Since we are not using a regular thread-state transition helper here,
2564 // we must manually emit the instruction barrier after leaving a safe state.
2565 OrderAccess::cross_modify_fence();
2566 if (state != _thread_in_native) {
2567 SafepointMechanism::block_if_requested(this);
2568 }
2569 }
2570
2571 #ifdef ASSERT
2572 // Verify the JavaThread has not yet been published in the Threads::list, and
2573 // hence doesn't need protection from concurrent access at this stage.
2574 void JavaThread::verify_not_published() {
2575 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2576 // since an unpublished JavaThread doesn't participate in the
2577 // Thread-SMR protocol for keeping a ThreadsList alive.
2578 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2579 }
2580 #endif
2581
2582 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2583 // progress or when _suspend_flags is non-zero.
2584 // Current thread needs to self-suspend if there is a suspend request and/or
2585 // block if a safepoint is in progress.
2586 // Async exception ISN'T checked.
2587 // Note only the ThreadInVMfromNative transition can call this function
2588 // directly and when thread state is _thread_in_native_trans
2589 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2590 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2591
2592 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2593
2594 if (thread->is_external_suspend()) {
2595 thread->java_suspend_self_with_safepoint_check();
2596 } else {
2597 SafepointMechanism::block_if_requested(thread);
2598 }
2599
2600 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2601 }
2602
2603 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2604 // progress or when _suspend_flags is non-zero.
2605 // Current thread needs to self-suspend if there is a suspend request and/or
2606 // block if a safepoint is in progress.
2607 // Also check for pending async exception (not including unsafe access error).
2608 // Note only the native==>VM/Java barriers can call this function and when
2609 // thread state is _thread_in_native_trans.
2610 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2611 check_safepoint_and_suspend_for_native_trans(thread);
2612
2613 if (thread->has_async_exception()) {
2614 // We are in _thread_in_native_trans state, don't handle unsafe
2615 // access error since that may block.
2616 thread->check_and_handle_async_exceptions(false);
2617 }
2618 }
2619
2620 // This is a variant of the normal
2621 // check_special_condition_for_native_trans with slightly different
2622 // semantics for use by critical native wrappers. It does all the
2623 // normal checks but also performs the transition back into
2624 // thread_in_Java state. This is required so that critical natives
2625 // can potentially block and perform a GC if they are the last thread
2626 // exiting the GCLocker.
2627 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2628 check_special_condition_for_native_trans(thread);
2629
2630 // Finish the transition
2631 thread->set_thread_state(_thread_in_Java);
2632
2633 if (thread->do_critical_native_unlock()) {
2634 ThreadInVMfromJavaNoAsyncException tiv(thread);
2635 GCLocker::unlock_critical(thread);
2636 thread->clear_critical_native_unlock();
2637 }
2638 }
2639
2640 // We need to guarantee the Threads_lock here, since resumes are not
2641 // allowed during safepoint synchronization
2642 // Can only resume from an external suspension
2643 void JavaThread::java_resume() {
2644 assert_locked_or_safepoint(Threads_lock);
2645
2646 // Sanity check: thread is gone, has started exiting or the thread
2647 // was not externally suspended.
2648 ThreadsListHandle tlh;
2649 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2650 return;
2651 }
2652
2653 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2654
2655 clear_external_suspend();
2656
2657 if (is_ext_suspended()) {
2658 clear_ext_suspended();
2659 SR_lock()->notify_all();
2660 }
2661 }
2662
2663 size_t JavaThread::_stack_red_zone_size = 0;
2664 size_t JavaThread::_stack_yellow_zone_size = 0;
2665 size_t JavaThread::_stack_reserved_zone_size = 0;
2666 size_t JavaThread::_stack_shadow_zone_size = 0;
2667
2668 void JavaThread::create_stack_guard_pages() {
2669 if (!os::uses_stack_guard_pages() ||
2670 _stack_guard_state != stack_guard_unused ||
2671 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2672 log_info(os, thread)("Stack guard page creation for thread "
2673 UINTX_FORMAT " disabled", os::current_thread_id());
2674 return;
2675 }
2676 address low_addr = stack_end();
2677 size_t len = stack_guard_zone_size();
2678
2679 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2680 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2681
2682 int must_commit = os::must_commit_stack_guard_pages();
2683 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2684
2685 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2686 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2687 return;
2688 }
2689
2690 if (os::guard_memory((char *) low_addr, len)) {
2691 _stack_guard_state = stack_guard_enabled;
2692 } else {
2693 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2694 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2695 if (os::uncommit_memory((char *) low_addr, len)) {
2696 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2697 }
2698 return;
2699 }
2700
2701 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2702 PTR_FORMAT "-" PTR_FORMAT ".",
2703 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2704 }
2705
2706 void JavaThread::remove_stack_guard_pages() {
2707 assert(Thread::current() == this, "from different thread");
2708 if (_stack_guard_state == stack_guard_unused) return;
2709 address low_addr = stack_end();
2710 size_t len = stack_guard_zone_size();
2711
2712 if (os::must_commit_stack_guard_pages()) {
2713 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2714 _stack_guard_state = stack_guard_unused;
2715 } else {
2716 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2717 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2718 return;
2719 }
2720 } else {
2721 if (_stack_guard_state == stack_guard_unused) return;
2722 if (os::unguard_memory((char *) low_addr, len)) {
2723 _stack_guard_state = stack_guard_unused;
2724 } else {
2725 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2726 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2727 return;
2728 }
2729 }
2730
2731 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2732 PTR_FORMAT "-" PTR_FORMAT ".",
2733 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2734 }
2735
2736 void JavaThread::enable_stack_reserved_zone() {
2737 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2738
2739 // The base notation is from the stack's point of view, growing downward.
2740 // We need to adjust it to work correctly with guard_memory()
2741 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2742
2743 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2744 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2745
2746 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2747 _stack_guard_state = stack_guard_enabled;
2748 } else {
2749 warning("Attempt to guard stack reserved zone failed.");
2750 }
2751 enable_register_stack_guard();
2752 }
2753
2754 void JavaThread::disable_stack_reserved_zone() {
2755 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2756
2757 // Simply return if called for a thread that does not use guard pages.
2758 if (_stack_guard_state != stack_guard_enabled) return;
2759
2760 // The base notation is from the stack's point of view, growing downward.
2761 // We need to adjust it to work correctly with guard_memory()
2762 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2763
2764 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2765 _stack_guard_state = stack_guard_reserved_disabled;
2766 } else {
2767 warning("Attempt to unguard stack reserved zone failed.");
2768 }
2769 disable_register_stack_guard();
2770 }
2771
2772 void JavaThread::enable_stack_yellow_reserved_zone() {
2773 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2774 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2775
2776 // The base notation is from the stacks point of view, growing downward.
2777 // We need to adjust it to work correctly with guard_memory()
2778 address base = stack_red_zone_base();
2779
2780 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2781 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2782
2783 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2784 _stack_guard_state = stack_guard_enabled;
2785 } else {
2786 warning("Attempt to guard stack yellow zone failed.");
2787 }
2788 enable_register_stack_guard();
2789 }
2790
2791 void JavaThread::disable_stack_yellow_reserved_zone() {
2792 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2793 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2794
2795 // Simply return if called for a thread that does not use guard pages.
2796 if (_stack_guard_state == stack_guard_unused) return;
2797
2798 // The base notation is from the stacks point of view, growing downward.
2799 // We need to adjust it to work correctly with guard_memory()
2800 address base = stack_red_zone_base();
2801
2802 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2803 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2804 } else {
2805 warning("Attempt to unguard stack yellow zone failed.");
2806 }
2807 disable_register_stack_guard();
2808 }
2809
2810 void JavaThread::enable_stack_red_zone() {
2811 // The base notation is from the stacks point of view, growing downward.
2812 // We need to adjust it to work correctly with guard_memory()
2813 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2814 address base = stack_red_zone_base() - stack_red_zone_size();
2815
2816 guarantee(base < stack_base(), "Error calculating stack red zone");
2817 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2818
2819 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2820 warning("Attempt to guard stack red zone failed.");
2821 }
2822 }
2823
2824 void JavaThread::disable_stack_red_zone() {
2825 // The base notation is from the stacks point of view, growing downward.
2826 // We need to adjust it to work correctly with guard_memory()
2827 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2828 address base = stack_red_zone_base() - stack_red_zone_size();
2829 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2830 warning("Attempt to unguard stack red zone failed.");
2831 }
2832 }
2833
2834 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2835 // ignore is there is no stack
2836 if (!has_last_Java_frame()) return;
2837 // traverse the stack frames. Starts from top frame.
2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2839 frame* fr = fst.current();
2840 f(fr, fst.register_map());
2841 }
2842 }
2843
2844
2845 #ifndef PRODUCT
2846 // Deoptimization
2847 // Function for testing deoptimization
2848 void JavaThread::deoptimize() {
2849 StackFrameStream fst(this, false);
2850 bool deopt = false; // Dump stack only if a deopt actually happens.
2851 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2852 // Iterate over all frames in the thread and deoptimize
2853 for (; !fst.is_done(); fst.next()) {
2854 if (fst.current()->can_be_deoptimized()) {
2855
2856 if (only_at) {
2857 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2858 // consists of comma or carriage return separated numbers so
2859 // search for the current bci in that string.
2860 address pc = fst.current()->pc();
2861 nmethod* nm = (nmethod*) fst.current()->cb();
2862 ScopeDesc* sd = nm->scope_desc_at(pc);
2863 char buffer[8];
2864 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2865 size_t len = strlen(buffer);
2866 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2867 while (found != NULL) {
2868 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2869 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2870 // Check that the bci found is bracketed by terminators.
2871 break;
2872 }
2873 found = strstr(found + 1, buffer);
2874 }
2875 if (!found) {
2876 continue;
2877 }
2878 }
2879
2880 if (DebugDeoptimization && !deopt) {
2881 deopt = true; // One-time only print before deopt
2882 tty->print_cr("[BEFORE Deoptimization]");
2883 trace_frames();
2884 trace_stack();
2885 }
2886 Deoptimization::deoptimize(this, *fst.current());
2887 }
2888 }
2889
2890 if (DebugDeoptimization && deopt) {
2891 tty->print_cr("[AFTER Deoptimization]");
2892 trace_frames();
2893 }
2894 }
2895
2896
2897 // Make zombies
2898 void JavaThread::make_zombies() {
2899 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2900 if (fst.current()->can_be_deoptimized()) {
2901 // it is a Java nmethod
2902 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2903 nm->make_not_entrant();
2904 }
2905 }
2906 }
2907 #endif // PRODUCT
2908
2909
2910 void JavaThread::deoptimize_marked_methods() {
2911 if (!has_last_Java_frame()) return;
2912 StackFrameStream fst(this, false);
2913 for (; !fst.is_done(); fst.next()) {
2914 if (fst.current()->should_be_deoptimized()) {
2915 Deoptimization::deoptimize(this, *fst.current());
2916 }
2917 }
2918 }
2919
2920 // If the caller is a NamedThread, then remember, in the current scope,
2921 // the given JavaThread in its _processed_thread field.
2922 class RememberProcessedThread: public StackObj {
2923 NamedThread* _cur_thr;
2924 public:
2925 RememberProcessedThread(JavaThread* jthr) {
2926 Thread* thread = Thread::current();
2927 if (thread->is_Named_thread()) {
2928 _cur_thr = (NamedThread *)thread;
2929 _cur_thr->set_processed_thread(jthr);
2930 } else {
2931 _cur_thr = NULL;
2932 }
2933 }
2934
2935 ~RememberProcessedThread() {
2936 if (_cur_thr) {
2937 _cur_thr->set_processed_thread(NULL);
2938 }
2939 }
2940 };
2941
2942 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2943 // Verify that the deferred card marks have been flushed.
2944 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2945
2946 // Traverse the GCHandles
2947 Thread::oops_do(f, cf);
2948
2949 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2950 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2951
2952 if (has_last_Java_frame()) {
2953 // Record JavaThread to GC thread
2954 RememberProcessedThread rpt(this);
2955
2956 // traverse the registered growable array
2957 if (_array_for_gc != NULL) {
2958 for (int index = 0; index < _array_for_gc->length(); index++) {
2959 f->do_oop(_array_for_gc->adr_at(index));
2960 }
2961 }
2962
2963 // Traverse the monitor chunks
2964 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2965 chunk->oops_do(f);
2966 }
2967
2968 // Traverse the execution stack
2969 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2970 fst.current()->oops_do(f, cf, fst.register_map());
2971 }
2972 }
2973
2974 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2975 // If we have deferred set_locals there might be oops waiting to be
2976 // written
2977 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2978 if (list != NULL) {
2979 for (int i = 0; i < list->length(); i++) {
2980 list->at(i)->oops_do(f);
2981 }
2982 }
2983
2984 // Traverse instance variables at the end since the GC may be moving things
2985 // around using this function
2986 f->do_oop((oop*) &_threadObj);
2987 f->do_oop((oop*) &_vm_result);
2988 f->do_oop((oop*) &_exception_oop);
2989 f->do_oop((oop*) &_pending_async_exception);
2990
2991 if (jvmti_thread_state() != NULL) {
2992 jvmti_thread_state()->oops_do(f, cf);
2993 }
2994 }
2995
2996 #ifdef ASSERT
2997 void JavaThread::verify_states_for_handshake() {
2998 // This checks that the thread has a correct frame state during a handshake.
2999 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3000 (has_last_Java_frame() && java_call_counter() > 0),
3001 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3002 has_last_Java_frame(), java_call_counter());
3003 }
3004 #endif
3005
3006 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3007 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3008 (has_last_Java_frame() && java_call_counter() > 0),
3009 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3010 has_last_Java_frame(), java_call_counter());
3011
3012 if (has_last_Java_frame()) {
3013 // Traverse the execution stack
3014 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3015 fst.current()->nmethods_do(cf);
3016 }
3017 }
3018
3019 if (jvmti_thread_state() != NULL) {
3020 jvmti_thread_state()->nmethods_do(cf);
3021 }
3022 }
3023
3024 void JavaThread::metadata_do(MetadataClosure* f) {
3025 if (has_last_Java_frame()) {
3026 // Traverse the execution stack to call f() on the methods in the stack
3027 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3028 fst.current()->metadata_do(f);
3029 }
3030 } else if (is_Compiler_thread()) {
3031 // need to walk ciMetadata in current compile tasks to keep alive.
3032 CompilerThread* ct = (CompilerThread*)this;
3033 if (ct->env() != NULL) {
3034 ct->env()->metadata_do(f);
3035 }
3036 CompileTask* task = ct->task();
3037 if (task != NULL) {
3038 task->metadata_do(f);
3039 }
3040 }
3041 }
3042
3043 // Printing
3044 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3045 switch (_thread_state) {
3046 case _thread_uninitialized: return "_thread_uninitialized";
3047 case _thread_new: return "_thread_new";
3048 case _thread_new_trans: return "_thread_new_trans";
3049 case _thread_in_native: return "_thread_in_native";
3050 case _thread_in_native_trans: return "_thread_in_native_trans";
3051 case _thread_in_vm: return "_thread_in_vm";
3052 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3053 case _thread_in_Java: return "_thread_in_Java";
3054 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3055 case _thread_blocked: return "_thread_blocked";
3056 case _thread_blocked_trans: return "_thread_blocked_trans";
3057 default: return "unknown thread state";
3058 }
3059 }
3060
3061 #ifndef PRODUCT
3062 void JavaThread::print_thread_state_on(outputStream *st) const {
3063 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3064 };
3065 #endif // PRODUCT
3066
3067 // Called by Threads::print() for VM_PrintThreads operation
3068 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3069 st->print_raw("\"");
3070 st->print_raw(get_thread_name());
3071 st->print_raw("\" ");
3072 oop thread_oop = threadObj();
3073 if (thread_oop != NULL) {
3074 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3075 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3076 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3077 }
3078 Thread::print_on(st, print_extended_info);
3079 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3080 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3081 if (thread_oop != NULL) {
3082 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3083 }
3084 #ifndef PRODUCT
3085 _safepoint_state->print_on(st);
3086 #endif // PRODUCT
3087 if (is_Compiler_thread()) {
3088 CompileTask *task = ((CompilerThread*)this)->task();
3089 if (task != NULL) {
3090 st->print(" Compiling: ");
3091 task->print(st, NULL, true, false);
3092 } else {
3093 st->print(" No compile task");
3094 }
3095 st->cr();
3096 }
3097 }
3098
3099 void JavaThread::print() const { print_on(tty); }
3100
3101 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3102 st->print("%s", get_thread_name_string(buf, buflen));
3103 }
3104
3105 // Called by fatal error handler. The difference between this and
3106 // JavaThread::print() is that we can't grab lock or allocate memory.
3107 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3108 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3109 oop thread_obj = threadObj();
3110 if (thread_obj != NULL) {
3111 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3112 }
3113 st->print(" [");
3114 st->print("%s", _get_thread_state_name(_thread_state));
3115 if (osthread()) {
3116 st->print(", id=%d", osthread()->thread_id());
3117 }
3118 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3119 p2i(stack_end()), p2i(stack_base()));
3120 st->print("]");
3121
3122 ThreadsSMRSupport::print_info_on(this, st);
3123 return;
3124 }
3125
3126 // Verification
3127
3128 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3129
3130 void JavaThread::verify() {
3131 // Verify oops in the thread.
3132 oops_do(&VerifyOopClosure::verify_oop, NULL);
3133
3134 // Verify the stack frames.
3135 frames_do(frame_verify);
3136 }
3137
3138 // CR 6300358 (sub-CR 2137150)
3139 // Most callers of this method assume that it can't return NULL but a
3140 // thread may not have a name whilst it is in the process of attaching to
3141 // the VM - see CR 6412693, and there are places where a JavaThread can be
3142 // seen prior to having it's threadObj set (eg JNI attaching threads and
3143 // if vm exit occurs during initialization). These cases can all be accounted
3144 // for such that this method never returns NULL.
3145 const char* JavaThread::get_thread_name() const {
3146 #ifdef ASSERT
3147 // early safepoints can hit while current thread does not yet have TLS
3148 if (!SafepointSynchronize::is_at_safepoint()) {
3149 Thread *cur = Thread::current();
3150 if (!(cur->is_Java_thread() && cur == this)) {
3151 // Current JavaThreads are allowed to get their own name without
3152 // the Threads_lock.
3153 assert_locked_or_safepoint_or_handshake(Threads_lock, this);
3154 }
3155 }
3156 #endif // ASSERT
3157 return get_thread_name_string();
3158 }
3159
3160 // Returns a non-NULL representation of this thread's name, or a suitable
3161 // descriptive string if there is no set name
3162 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3163 const char* name_str;
3164 oop thread_obj = threadObj();
3165 if (thread_obj != NULL) {
3166 oop name = java_lang_Thread::name(thread_obj);
3167 if (name != NULL) {
3168 if (buf == NULL) {
3169 name_str = java_lang_String::as_utf8_string(name);
3170 } else {
3171 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3172 }
3173 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3174 name_str = "<no-name - thread is attaching>";
3175 } else {
3176 name_str = Thread::name();
3177 }
3178 } else {
3179 name_str = Thread::name();
3180 }
3181 assert(name_str != NULL, "unexpected NULL thread name");
3182 return name_str;
3183 }
3184
3185 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3186
3187 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3188 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3189 // Link Java Thread object <-> C++ Thread
3190
3191 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3192 // and put it into a new Handle. The Handle "thread_oop" can then
3193 // be used to pass the C++ thread object to other methods.
3194
3195 // Set the Java level thread object (jthread) field of the
3196 // new thread (a JavaThread *) to C++ thread object using the
3197 // "thread_oop" handle.
3198
3199 // Set the thread field (a JavaThread *) of the
3200 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3201
3202 Handle thread_oop(Thread::current(),
3203 JNIHandles::resolve_non_null(jni_thread));
3204 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3205 "must be initialized");
3206 set_threadObj(thread_oop());
3207 java_lang_Thread::set_thread(thread_oop(), this);
3208
3209 if (prio == NoPriority) {
3210 prio = java_lang_Thread::priority(thread_oop());
3211 assert(prio != NoPriority, "A valid priority should be present");
3212 }
3213
3214 // Push the Java priority down to the native thread; needs Threads_lock
3215 Thread::set_priority(this, prio);
3216
3217 // Add the new thread to the Threads list and set it in motion.
3218 // We must have threads lock in order to call Threads::add.
3219 // It is crucial that we do not block before the thread is
3220 // added to the Threads list for if a GC happens, then the java_thread oop
3221 // will not be visited by GC.
3222 Threads::add(this);
3223 }
3224
3225 oop JavaThread::current_park_blocker() {
3226 // Support for JSR-166 locks
3227 oop thread_oop = threadObj();
3228 if (thread_oop != NULL) {
3229 return java_lang_Thread::park_blocker(thread_oop);
3230 }
3231 return NULL;
3232 }
3233
3234
3235 void JavaThread::print_stack_on(outputStream* st) {
3236 if (!has_last_Java_frame()) return;
3237 ResourceMark rm;
3238 HandleMark hm;
3239
3240 RegisterMap reg_map(this);
3241 vframe* start_vf = last_java_vframe(®_map);
3242 int count = 0;
3243 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3244 if (f->is_java_frame()) {
3245 javaVFrame* jvf = javaVFrame::cast(f);
3246 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3247
3248 // Print out lock information
3249 if (JavaMonitorsInStackTrace) {
3250 jvf->print_lock_info_on(st, count);
3251 }
3252 } else {
3253 // Ignore non-Java frames
3254 }
3255
3256 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3257 count++;
3258 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3259 }
3260 }
3261
3262
3263 // JVMTI PopFrame support
3264 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3265 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3266 if (in_bytes(size_in_bytes) != 0) {
3267 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3268 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3269 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3270 }
3271 }
3272
3273 void* JavaThread::popframe_preserved_args() {
3274 return _popframe_preserved_args;
3275 }
3276
3277 ByteSize JavaThread::popframe_preserved_args_size() {
3278 return in_ByteSize(_popframe_preserved_args_size);
3279 }
3280
3281 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3282 int sz = in_bytes(popframe_preserved_args_size());
3283 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3284 return in_WordSize(sz / wordSize);
3285 }
3286
3287 void JavaThread::popframe_free_preserved_args() {
3288 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3289 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3290 _popframe_preserved_args = NULL;
3291 _popframe_preserved_args_size = 0;
3292 }
3293
3294 #ifndef PRODUCT
3295
3296 void JavaThread::trace_frames() {
3297 tty->print_cr("[Describe stack]");
3298 int frame_no = 1;
3299 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3300 tty->print(" %d. ", frame_no++);
3301 fst.current()->print_value_on(tty, this);
3302 tty->cr();
3303 }
3304 }
3305
3306 class PrintAndVerifyOopClosure: public OopClosure {
3307 protected:
3308 template <class T> inline void do_oop_work(T* p) {
3309 oop obj = RawAccess<>::oop_load(p);
3310 if (obj == NULL) return;
3311 tty->print(INTPTR_FORMAT ": ", p2i(p));
3312 if (oopDesc::is_oop_or_null(obj)) {
3313 if (obj->is_objArray()) {
3314 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3315 } else {
3316 obj->print();
3317 }
3318 } else {
3319 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3320 }
3321 tty->cr();
3322 }
3323 public:
3324 virtual void do_oop(oop* p) { do_oop_work(p); }
3325 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3326 };
3327
3328 #ifdef ASSERT
3329 // Print or validate the layout of stack frames
3330 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3331 ResourceMark rm;
3332 PRESERVE_EXCEPTION_MARK;
3333 FrameValues values;
3334 int frame_no = 0;
3335 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3336 fst.current()->describe(values, ++frame_no);
3337 if (depth == frame_no) break;
3338 }
3339 if (validate_only) {
3340 values.validate();
3341 } else {
3342 tty->print_cr("[Describe stack layout]");
3343 values.print(this);
3344 }
3345 }
3346 #endif
3347
3348 void JavaThread::trace_stack_from(vframe* start_vf) {
3349 ResourceMark rm;
3350 int vframe_no = 1;
3351 for (vframe* f = start_vf; f; f = f->sender()) {
3352 if (f->is_java_frame()) {
3353 javaVFrame::cast(f)->print_activation(vframe_no++);
3354 } else {
3355 f->print();
3356 }
3357 if (vframe_no > StackPrintLimit) {
3358 tty->print_cr("...<more frames>...");
3359 return;
3360 }
3361 }
3362 }
3363
3364
3365 void JavaThread::trace_stack() {
3366 if (!has_last_Java_frame()) return;
3367 ResourceMark rm;
3368 HandleMark hm;
3369 RegisterMap reg_map(this);
3370 trace_stack_from(last_java_vframe(®_map));
3371 }
3372
3373
3374 #endif // PRODUCT
3375
3376
3377 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3378 assert(reg_map != NULL, "a map must be given");
3379 frame f = last_frame();
3380 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3381 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3382 }
3383 return NULL;
3384 }
3385
3386
3387 Klass* JavaThread::security_get_caller_class(int depth) {
3388 vframeStream vfst(this);
3389 vfst.security_get_caller_frame(depth);
3390 if (!vfst.at_end()) {
3391 return vfst.method()->method_holder();
3392 }
3393 return NULL;
3394 }
3395
3396 // java.lang.Thread.sleep support
3397 // Returns true if sleep time elapsed as expected, and false
3398 // if the thread was interrupted.
3399 bool JavaThread::sleep(jlong millis) {
3400 assert(this == Thread::current(), "thread consistency check");
3401
3402 ParkEvent * const slp = this->_SleepEvent;
3403 // Because there can be races with thread interruption sending an unpark()
3404 // to the event, we explicitly reset it here to avoid an immediate return.
3405 // The actual interrupt state will be checked before we park().
3406 slp->reset();
3407 // Thread interruption establishes a happens-before ordering in the
3408 // Java Memory Model, so we need to ensure we synchronize with the
3409 // interrupt state.
3410 OrderAccess::fence();
3411
3412 jlong prevtime = os::javaTimeNanos();
3413
3414 for (;;) {
3415 // interruption has precedence over timing out
3416 if (this->is_interrupted(true)) {
3417 return false;
3418 }
3419
3420 if (millis <= 0) {
3421 return true;
3422 }
3423
3424 {
3425 ThreadBlockInVM tbivm(this);
3426 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3427
3428 this->set_suspend_equivalent();
3429 // cleared by handle_special_suspend_equivalent_condition() or
3430 // java_suspend_self() via check_and_wait_while_suspended()
3431
3432 slp->park(millis);
3433
3434 // were we externally suspended while we were waiting?
3435 this->check_and_wait_while_suspended();
3436 }
3437
3438 // Update elapsed time tracking
3439 jlong newtime = os::javaTimeNanos();
3440 if (newtime - prevtime < 0) {
3441 // time moving backwards, should only happen if no monotonic clock
3442 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3443 assert(!os::supports_monotonic_clock(),
3444 "unexpected time moving backwards detected in JavaThread::sleep()");
3445 } else {
3446 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3447 }
3448 prevtime = newtime;
3449 }
3450 }
3451
3452 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3453 assert(thread->is_Compiler_thread(), "must be compiler thread");
3454 CompileBroker::compiler_thread_loop();
3455 }
3456
3457 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3458 NMethodSweeper::sweeper_loop();
3459 }
3460
3461 // Create a CompilerThread
3462 CompilerThread::CompilerThread(CompileQueue* queue,
3463 CompilerCounters* counters)
3464 : JavaThread(&compiler_thread_entry) {
3465 _env = NULL;
3466 _log = NULL;
3467 _task = NULL;
3468 _queue = queue;
3469 _counters = counters;
3470 _buffer_blob = NULL;
3471 _compiler = NULL;
3472
3473 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3474 resource_area()->bias_to(mtCompiler);
3475
3476 #ifndef PRODUCT
3477 _ideal_graph_printer = NULL;
3478 #endif
3479 }
3480
3481 CompilerThread::~CompilerThread() {
3482 // Delete objects which were allocated on heap.
3483 delete _counters;
3484 }
3485
3486 bool CompilerThread::can_call_java() const {
3487 return _compiler != NULL && _compiler->is_jvmci();
3488 }
3489
3490 // Create sweeper thread
3491 CodeCacheSweeperThread::CodeCacheSweeperThread()
3492 : JavaThread(&sweeper_thread_entry) {
3493 _scanned_compiled_method = NULL;
3494 }
3495
3496 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3497 JavaThread::oops_do(f, cf);
3498 if (_scanned_compiled_method != NULL && cf != NULL) {
3499 // Safepoints can occur when the sweeper is scanning an nmethod so
3500 // process it here to make sure it isn't unloaded in the middle of
3501 // a scan.
3502 cf->do_code_blob(_scanned_compiled_method);
3503 }
3504 }
3505
3506 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3507 JavaThread::nmethods_do(cf);
3508 if (_scanned_compiled_method != NULL && cf != NULL) {
3509 // Safepoints can occur when the sweeper is scanning an nmethod so
3510 // process it here to make sure it isn't unloaded in the middle of
3511 // a scan.
3512 cf->do_code_blob(_scanned_compiled_method);
3513 }
3514 }
3515
3516
3517 // ======= Threads ========
3518
3519 // The Threads class links together all active threads, and provides
3520 // operations over all threads. It is protected by the Threads_lock,
3521 // which is also used in other global contexts like safepointing.
3522 // ThreadsListHandles are used to safely perform operations on one
3523 // or more threads without the risk of the thread exiting during the
3524 // operation.
3525 //
3526 // Note: The Threads_lock is currently more widely used than we
3527 // would like. We are actively migrating Threads_lock uses to other
3528 // mechanisms in order to reduce Threads_lock contention.
3529
3530 int Threads::_number_of_threads = 0;
3531 int Threads::_number_of_non_daemon_threads = 0;
3532 int Threads::_return_code = 0;
3533 uintx Threads::_thread_claim_token = 1; // Never zero.
3534 size_t JavaThread::_stack_size_at_create = 0;
3535
3536 #ifdef ASSERT
3537 bool Threads::_vm_complete = false;
3538 #endif
3539
3540 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3541 Prefetch::read((void*)addr, prefetch_interval);
3542 return *addr;
3543 }
3544
3545 // Possibly the ugliest for loop the world has seen. C++ does not allow
3546 // multiple types in the declaration section of the for loop. In this case
3547 // we are only dealing with pointers and hence can cast them. It looks ugly
3548 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3549 #define DO_JAVA_THREADS(LIST, X) \
3550 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3551 *MACRO_list = (JavaThread*)(LIST), \
3552 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3553 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3554 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3555 MACRO_current_p != MACRO_end; \
3556 MACRO_current_p++, \
3557 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3558
3559 // All JavaThreads
3560 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3561
3562 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3563 void Threads::non_java_threads_do(ThreadClosure* tc) {
3564 NoSafepointVerifier nsv;
3565 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3566 tc->do_thread(njti.current());
3567 }
3568 }
3569
3570 // All JavaThreads
3571 void Threads::java_threads_do(ThreadClosure* tc) {
3572 assert_locked_or_safepoint(Threads_lock);
3573 // ALL_JAVA_THREADS iterates through all JavaThreads.
3574 ALL_JAVA_THREADS(p) {
3575 tc->do_thread(p);
3576 }
3577 }
3578
3579 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3580 assert_locked_or_safepoint(Threads_lock);
3581 java_threads_do(tc);
3582 tc->do_thread(VMThread::vm_thread());
3583 }
3584
3585 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3586 void Threads::threads_do(ThreadClosure* tc) {
3587 assert_locked_or_safepoint(Threads_lock);
3588 java_threads_do(tc);
3589 non_java_threads_do(tc);
3590 }
3591
3592 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3593 uintx claim_token = Threads::thread_claim_token();
3594 ALL_JAVA_THREADS(p) {
3595 if (p->claim_threads_do(is_par, claim_token)) {
3596 tc->do_thread(p);
3597 }
3598 }
3599 VMThread* vmt = VMThread::vm_thread();
3600 if (vmt->claim_threads_do(is_par, claim_token)) {
3601 tc->do_thread(vmt);
3602 }
3603 }
3604
3605 // The system initialization in the library has three phases.
3606 //
3607 // Phase 1: java.lang.System class initialization
3608 // java.lang.System is a primordial class loaded and initialized
3609 // by the VM early during startup. java.lang.System.<clinit>
3610 // only does registerNatives and keeps the rest of the class
3611 // initialization work later until thread initialization completes.
3612 //
3613 // System.initPhase1 initializes the system properties, the static
3614 // fields in, out, and err. Set up java signal handlers, OS-specific
3615 // system settings, and thread group of the main thread.
3616 static void call_initPhase1(TRAPS) {
3617 Klass* klass = SystemDictionary::System_klass();
3618 JavaValue result(T_VOID);
3619 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3620 vmSymbols::void_method_signature(), CHECK);
3621 }
3622
3623 // Phase 2. Module system initialization
3624 // This will initialize the module system. Only java.base classes
3625 // can be loaded until phase 2 completes.
3626 //
3627 // Call System.initPhase2 after the compiler initialization and jsr292
3628 // classes get initialized because module initialization runs a lot of java
3629 // code, that for performance reasons, should be compiled. Also, this will
3630 // enable the startup code to use lambda and other language features in this
3631 // phase and onward.
3632 //
3633 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3634 static void call_initPhase2(TRAPS) {
3635 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3636
3637 Klass* klass = SystemDictionary::System_klass();
3638
3639 JavaValue result(T_INT);
3640 JavaCallArguments args;
3641 args.push_int(DisplayVMOutputToStderr);
3642 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3643 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3644 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3645 if (result.get_jint() != JNI_OK) {
3646 vm_exit_during_initialization(); // no message or exception
3647 }
3648
3649 universe_post_module_init();
3650 }
3651
3652 // Phase 3. final setup - set security manager, system class loader and TCCL
3653 //
3654 // This will instantiate and set the security manager, set the system class
3655 // loader as well as the thread context class loader. The security manager
3656 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3657 // other modules or the application's classpath.
3658 static void call_initPhase3(TRAPS) {
3659 Klass* klass = SystemDictionary::System_klass();
3660 JavaValue result(T_VOID);
3661 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3662 vmSymbols::void_method_signature(), CHECK);
3663 }
3664
3665 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3666 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3667
3668 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3669 create_vm_init_libraries();
3670 }
3671
3672 initialize_class(vmSymbols::java_lang_String(), CHECK);
3673
3674 // Inject CompactStrings value after the static initializers for String ran.
3675 java_lang_String::set_compact_strings(CompactStrings);
3676
3677 // Initialize java_lang.System (needed before creating the thread)
3678 initialize_class(vmSymbols::java_lang_System(), CHECK);
3679 // The VM creates & returns objects of this class. Make sure it's initialized.
3680 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3681 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3682 Handle thread_group = create_initial_thread_group(CHECK);
3683 Universe::set_main_thread_group(thread_group());
3684 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3685 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3686 main_thread->set_threadObj(thread_object);
3687
3688 // Set thread status to running since main thread has
3689 // been started and running.
3690 java_lang_Thread::set_thread_status(thread_object,
3691 java_lang_Thread::RUNNABLE);
3692
3693 // The VM creates objects of this class.
3694 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3695
3696 #ifdef ASSERT
3697 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3698 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3699 #endif
3700
3701 // initialize the hardware-specific constants needed by Unsafe
3702 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3703 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3704
3705 // The VM preresolves methods to these classes. Make sure that they get initialized
3706 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3707 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3708
3709 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3710 call_initPhase1(CHECK);
3711
3712 // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3713 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3714 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3715 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3716 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3717
3718 // an instance of OutOfMemory exception has been allocated earlier
3719 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3720 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3721 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3722 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3723 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3724 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3725 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3726 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3727
3728 // Eager box cache initialization only if AOT is on and any library is loaded.
3729 AOTLoader::initialize_box_caches(CHECK);
3730 }
3731
3732 void Threads::initialize_jsr292_core_classes(TRAPS) {
3733 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3734
3735 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3736 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3737 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3738 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3739 }
3740
3741 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3742 extern void JDK_Version_init();
3743
3744 // Preinitialize version info.
3745 VM_Version::early_initialize();
3746
3747 // Check version
3748 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3749
3750 // Initialize library-based TLS
3751 ThreadLocalStorage::init();
3752
3753 // Initialize the output stream module
3754 ostream_init();
3755
3756 // Process java launcher properties.
3757 Arguments::process_sun_java_launcher_properties(args);
3758
3759 // Initialize the os module
3760 os::init();
3761
3762 // Record VM creation timing statistics
3763 TraceVmCreationTime create_vm_timer;
3764 create_vm_timer.start();
3765
3766 // Initialize system properties.
3767 Arguments::init_system_properties();
3768
3769 // So that JDK version can be used as a discriminator when parsing arguments
3770 JDK_Version_init();
3771
3772 // Update/Initialize System properties after JDK version number is known
3773 Arguments::init_version_specific_system_properties();
3774
3775 // Make sure to initialize log configuration *before* parsing arguments
3776 LogConfiguration::initialize(create_vm_timer.begin_time());
3777
3778 // Parse arguments
3779 // Note: this internally calls os::init_container_support()
3780 jint parse_result = Arguments::parse(args);
3781 if (parse_result != JNI_OK) return parse_result;
3782
3783 os::init_before_ergo();
3784
3785 jint ergo_result = Arguments::apply_ergo();
3786 if (ergo_result != JNI_OK) return ergo_result;
3787
3788 // Final check of all ranges after ergonomics which may change values.
3789 if (!JVMFlagRangeList::check_ranges()) {
3790 return JNI_EINVAL;
3791 }
3792
3793 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3794 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3795 if (!constraint_result) {
3796 return JNI_EINVAL;
3797 }
3798
3799 if (PauseAtStartup) {
3800 os::pause();
3801 }
3802
3803 HOTSPOT_VM_INIT_BEGIN();
3804
3805 // Timing (must come after argument parsing)
3806 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3807
3808 // Initialize the os module after parsing the args
3809 jint os_init_2_result = os::init_2();
3810 if (os_init_2_result != JNI_OK) return os_init_2_result;
3811
3812 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3813 // Initialize assert poison page mechanism.
3814 if (ShowRegistersOnAssert) {
3815 initialize_assert_poison();
3816 }
3817 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3818
3819 SafepointMechanism::initialize();
3820
3821 jint adjust_after_os_result = Arguments::adjust_after_os();
3822 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3823
3824 // Initialize output stream logging
3825 ostream_init_log();
3826
3827 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3828 // Must be before create_vm_init_agents()
3829 if (Arguments::init_libraries_at_startup()) {
3830 convert_vm_init_libraries_to_agents();
3831 }
3832
3833 // Launch -agentlib/-agentpath and converted -Xrun agents
3834 if (Arguments::init_agents_at_startup()) {
3835 create_vm_init_agents();
3836 }
3837
3838 // Initialize Threads state
3839 _number_of_threads = 0;
3840 _number_of_non_daemon_threads = 0;
3841
3842 // Initialize global data structures and create system classes in heap
3843 vm_init_globals();
3844
3845 #if INCLUDE_JVMCI
3846 if (JVMCICounterSize > 0) {
3847 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3848 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3849 } else {
3850 JavaThread::_jvmci_old_thread_counters = NULL;
3851 }
3852 #endif // INCLUDE_JVMCI
3853
3854 // Attach the main thread to this os thread
3855 JavaThread* main_thread = new JavaThread();
3856 main_thread->set_thread_state(_thread_in_vm);
3857 main_thread->initialize_thread_current();
3858 // must do this before set_active_handles
3859 main_thread->record_stack_base_and_size();
3860 main_thread->register_thread_stack_with_NMT();
3861 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3862
3863 if (!main_thread->set_as_starting_thread()) {
3864 vm_shutdown_during_initialization(
3865 "Failed necessary internal allocation. Out of swap space");
3866 main_thread->smr_delete();
3867 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3868 return JNI_ENOMEM;
3869 }
3870
3871 // Enable guard page *after* os::create_main_thread(), otherwise it would
3872 // crash Linux VM, see notes in os_linux.cpp.
3873 main_thread->create_stack_guard_pages();
3874
3875 // Initialize Java-Level synchronization subsystem
3876 ObjectMonitor::Initialize();
3877
3878 // Initialize global modules
3879 jint status = init_globals();
3880 if (status != JNI_OK) {
3881 main_thread->smr_delete();
3882 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3883 return status;
3884 }
3885
3886 JFR_ONLY(Jfr::on_create_vm_1();)
3887
3888 // Should be done after the heap is fully created
3889 main_thread->cache_global_variables();
3890
3891 HandleMark hm;
3892
3893 { MutexLocker mu(Threads_lock);
3894 Threads::add(main_thread);
3895 }
3896
3897 // Any JVMTI raw monitors entered in onload will transition into
3898 // real raw monitor. VM is setup enough here for raw monitor enter.
3899 JvmtiExport::transition_pending_onload_raw_monitors();
3900
3901 // Create the VMThread
3902 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3903
3904 VMThread::create();
3905 Thread* vmthread = VMThread::vm_thread();
3906
3907 if (!os::create_thread(vmthread, os::vm_thread)) {
3908 vm_exit_during_initialization("Cannot create VM thread. "
3909 "Out of system resources.");
3910 }
3911
3912 // Wait for the VM thread to become ready, and VMThread::run to initialize
3913 // Monitors can have spurious returns, must always check another state flag
3914 {
3915 MonitorLocker ml(Notify_lock);
3916 os::start_thread(vmthread);
3917 while (vmthread->active_handles() == NULL) {
3918 ml.wait();
3919 }
3920 }
3921 }
3922
3923 assert(Universe::is_fully_initialized(), "not initialized");
3924 if (VerifyDuringStartup) {
3925 // Make sure we're starting with a clean slate.
3926 VM_Verify verify_op;
3927 VMThread::execute(&verify_op);
3928 }
3929
3930 // We need this to update the java.vm.info property in case any flags used
3931 // to initially define it have been changed. This is needed for both CDS and
3932 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3933 // is initially computed. See Abstract_VM_Version::vm_info_string().
3934 // This update must happen before we initialize the java classes, but
3935 // after any initialization logic that might modify the flags.
3936 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3937
3938 Thread* THREAD = Thread::current();
3939
3940 // Always call even when there are not JVMTI environments yet, since environments
3941 // may be attached late and JVMTI must track phases of VM execution
3942 JvmtiExport::enter_early_start_phase();
3943
3944 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3945 JvmtiExport::post_early_vm_start();
3946
3947 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3948
3949 quicken_jni_functions();
3950
3951 // No more stub generation allowed after that point.
3952 StubCodeDesc::freeze();
3953
3954 // Set flag that basic initialization has completed. Used by exceptions and various
3955 // debug stuff, that does not work until all basic classes have been initialized.
3956 set_init_completed();
3957
3958 LogConfiguration::post_initialize();
3959 Metaspace::post_initialize();
3960
3961 HOTSPOT_VM_INIT_END();
3962
3963 // record VM initialization completion time
3964 #if INCLUDE_MANAGEMENT
3965 Management::record_vm_init_completed();
3966 #endif // INCLUDE_MANAGEMENT
3967
3968 // Signal Dispatcher needs to be started before VMInit event is posted
3969 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3970
3971 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3972 if (!DisableAttachMechanism) {
3973 AttachListener::vm_start();
3974 if (StartAttachListener || AttachListener::init_at_startup()) {
3975 AttachListener::init();
3976 }
3977 }
3978
3979 // Launch -Xrun agents
3980 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3981 // back-end can launch with -Xdebug -Xrunjdwp.
3982 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3983 create_vm_init_libraries();
3984 }
3985
3986 if (CleanChunkPoolAsync) {
3987 Chunk::start_chunk_pool_cleaner_task();
3988 }
3989
3990 // Start the service thread
3991 // The service thread enqueues JVMTI deferred events and does various hashtable
3992 // and other cleanups. Needs to start before the compilers start posting events.
3993 ServiceThread::initialize();
3994
3995 // initialize compiler(s)
3996 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3997 #if INCLUDE_JVMCI
3998 bool force_JVMCI_intialization = false;
3999 if (EnableJVMCI) {
4000 // Initialize JVMCI eagerly when it is explicitly requested.
4001 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4002 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4003
4004 if (!force_JVMCI_intialization) {
4005 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4006 // compilations via JVMCI will not actually block until JVMCI is initialized.
4007 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4008 }
4009 }
4010 #endif
4011 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4012 // Postpone completion of compiler initialization to after JVMCI
4013 // is initialized to avoid timeouts of blocking compilations.
4014 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4015 CompileBroker::compilation_init_phase2();
4016 }
4017 #endif
4018
4019 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4020 // It is done after compilers are initialized, because otherwise compilations of
4021 // signature polymorphic MH intrinsics can be missed
4022 // (see SystemDictionary::find_method_handle_intrinsic).
4023 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4024
4025 // This will initialize the module system. Only java.base classes can be
4026 // loaded until phase 2 completes
4027 call_initPhase2(CHECK_JNI_ERR);
4028
4029 JFR_ONLY(Jfr::on_create_vm_2();)
4030
4031 // Always call even when there are not JVMTI environments yet, since environments
4032 // may be attached late and JVMTI must track phases of VM execution
4033 JvmtiExport::enter_start_phase();
4034
4035 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4036 JvmtiExport::post_vm_start();
4037
4038 // Final system initialization including security manager and system class loader
4039 call_initPhase3(CHECK_JNI_ERR);
4040
4041 // cache the system and platform class loaders
4042 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4043
4044 #if INCLUDE_CDS
4045 // capture the module path info from the ModuleEntryTable
4046 ClassLoader::initialize_module_path(THREAD);
4047 #endif
4048
4049 #if INCLUDE_JVMCI
4050 if (force_JVMCI_intialization) {
4051 JVMCI::initialize_compiler(CHECK_JNI_ERR);
4052 CompileBroker::compilation_init_phase2();
4053 }
4054 #endif
4055
4056 // Always call even when there are not JVMTI environments yet, since environments
4057 // may be attached late and JVMTI must track phases of VM execution
4058 JvmtiExport::enter_live_phase();
4059
4060 // Make perfmemory accessible
4061 PerfMemory::set_accessible(true);
4062
4063 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4064 JvmtiExport::post_vm_initialized();
4065
4066 JFR_ONLY(Jfr::on_create_vm_3();)
4067
4068 #if INCLUDE_MANAGEMENT
4069 Management::initialize(THREAD);
4070
4071 if (HAS_PENDING_EXCEPTION) {
4072 // management agent fails to start possibly due to
4073 // configuration problem and is responsible for printing
4074 // stack trace if appropriate. Simply exit VM.
4075 vm_exit(1);
4076 }
4077 #endif // INCLUDE_MANAGEMENT
4078
4079 if (MemProfiling) MemProfiler::engage();
4080 StatSampler::engage();
4081 if (CheckJNICalls) JniPeriodicChecker::engage();
4082
4083 BiasedLocking::init();
4084
4085 #if INCLUDE_RTM_OPT
4086 RTMLockingCounters::init();
4087 #endif
4088
4089 call_postVMInitHook(THREAD);
4090 // The Java side of PostVMInitHook.run must deal with all
4091 // exceptions and provide means of diagnosis.
4092 if (HAS_PENDING_EXCEPTION) {
4093 CLEAR_PENDING_EXCEPTION;
4094 }
4095
4096 {
4097 MutexLocker ml(PeriodicTask_lock);
4098 // Make sure the WatcherThread can be started by WatcherThread::start()
4099 // or by dynamic enrollment.
4100 WatcherThread::make_startable();
4101 // Start up the WatcherThread if there are any periodic tasks
4102 // NOTE: All PeriodicTasks should be registered by now. If they
4103 // aren't, late joiners might appear to start slowly (we might
4104 // take a while to process their first tick).
4105 if (PeriodicTask::num_tasks() > 0) {
4106 WatcherThread::start();
4107 }
4108 }
4109
4110 create_vm_timer.end();
4111 #ifdef ASSERT
4112 _vm_complete = true;
4113 #endif
4114
4115 if (DumpSharedSpaces) {
4116 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4117 ShouldNotReachHere();
4118 }
4119
4120 return JNI_OK;
4121 }
4122
4123 // type for the Agent_OnLoad and JVM_OnLoad entry points
4124 extern "C" {
4125 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4126 }
4127 // Find a command line agent library and return its entry point for
4128 // -agentlib: -agentpath: -Xrun
4129 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4130 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4131 const char *on_load_symbols[],
4132 size_t num_symbol_entries) {
4133 OnLoadEntry_t on_load_entry = NULL;
4134 void *library = NULL;
4135
4136 if (!agent->valid()) {
4137 char buffer[JVM_MAXPATHLEN];
4138 char ebuf[1024] = "";
4139 const char *name = agent->name();
4140 const char *msg = "Could not find agent library ";
4141
4142 // First check to see if agent is statically linked into executable
4143 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4144 library = agent->os_lib();
4145 } else if (agent->is_absolute_path()) {
4146 library = os::dll_load(name, ebuf, sizeof ebuf);
4147 if (library == NULL) {
4148 const char *sub_msg = " in absolute path, with error: ";
4149 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4150 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4151 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4152 // If we can't find the agent, exit.
4153 vm_exit_during_initialization(buf, NULL);
4154 FREE_C_HEAP_ARRAY(char, buf);
4155 }
4156 } else {
4157 // Try to load the agent from the standard dll directory
4158 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4159 name)) {
4160 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4161 }
4162 if (library == NULL) { // Try the library path directory.
4163 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4164 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4165 }
4166 if (library == NULL) {
4167 const char *sub_msg = " on the library path, with error: ";
4168 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4169
4170 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4171 strlen(ebuf) + strlen(sub_msg2) + 1;
4172 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4173 if (!agent->is_instrument_lib()) {
4174 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4175 } else {
4176 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4177 }
4178 // If we can't find the agent, exit.
4179 vm_exit_during_initialization(buf, NULL);
4180 FREE_C_HEAP_ARRAY(char, buf);
4181 }
4182 }
4183 }
4184 agent->set_os_lib(library);
4185 agent->set_valid();
4186 }
4187
4188 // Find the OnLoad function.
4189 on_load_entry =
4190 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4191 false,
4192 on_load_symbols,
4193 num_symbol_entries));
4194 return on_load_entry;
4195 }
4196
4197 // Find the JVM_OnLoad entry point
4198 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4199 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4200 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4201 }
4202
4203 // Find the Agent_OnLoad entry point
4204 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4205 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4206 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4207 }
4208
4209 // For backwards compatibility with -Xrun
4210 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4211 // treated like -agentpath:
4212 // Must be called before agent libraries are created
4213 void Threads::convert_vm_init_libraries_to_agents() {
4214 AgentLibrary* agent;
4215 AgentLibrary* next;
4216
4217 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4218 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4219 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4220
4221 // If there is an JVM_OnLoad function it will get called later,
4222 // otherwise see if there is an Agent_OnLoad
4223 if (on_load_entry == NULL) {
4224 on_load_entry = lookup_agent_on_load(agent);
4225 if (on_load_entry != NULL) {
4226 // switch it to the agent list -- so that Agent_OnLoad will be called,
4227 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4228 Arguments::convert_library_to_agent(agent);
4229 } else {
4230 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4231 }
4232 }
4233 }
4234 }
4235
4236 // Create agents for -agentlib: -agentpath: and converted -Xrun
4237 // Invokes Agent_OnLoad
4238 // Called very early -- before JavaThreads exist
4239 void Threads::create_vm_init_agents() {
4240 extern struct JavaVM_ main_vm;
4241 AgentLibrary* agent;
4242
4243 JvmtiExport::enter_onload_phase();
4244
4245 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4246 // CDS dumping does not support native JVMTI agent.
4247 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4248 if (Arguments::is_dumping_archive()) {
4249 if(!agent->is_instrument_lib()) {
4250 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4251 } else if (!AllowArchivingWithJavaAgent) {
4252 vm_exit_during_cds_dumping(
4253 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4254 }
4255 }
4256
4257 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4258
4259 if (on_load_entry != NULL) {
4260 // Invoke the Agent_OnLoad function
4261 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4262 if (err != JNI_OK) {
4263 vm_exit_during_initialization("agent library failed to init", agent->name());
4264 }
4265 } else {
4266 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4267 }
4268 }
4269
4270 JvmtiExport::enter_primordial_phase();
4271 }
4272
4273 extern "C" {
4274 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4275 }
4276
4277 void Threads::shutdown_vm_agents() {
4278 // Send any Agent_OnUnload notifications
4279 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4280 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4281 extern struct JavaVM_ main_vm;
4282 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4283
4284 // Find the Agent_OnUnload function.
4285 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4286 os::find_agent_function(agent,
4287 false,
4288 on_unload_symbols,
4289 num_symbol_entries));
4290
4291 // Invoke the Agent_OnUnload function
4292 if (unload_entry != NULL) {
4293 JavaThread* thread = JavaThread::current();
4294 ThreadToNativeFromVM ttn(thread);
4295 HandleMark hm(thread);
4296 (*unload_entry)(&main_vm);
4297 }
4298 }
4299 }
4300
4301 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4302 // Invokes JVM_OnLoad
4303 void Threads::create_vm_init_libraries() {
4304 extern struct JavaVM_ main_vm;
4305 AgentLibrary* agent;
4306
4307 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4308 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4309
4310 if (on_load_entry != NULL) {
4311 // Invoke the JVM_OnLoad function
4312 JavaThread* thread = JavaThread::current();
4313 ThreadToNativeFromVM ttn(thread);
4314 HandleMark hm(thread);
4315 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4316 if (err != JNI_OK) {
4317 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4318 }
4319 } else {
4320 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4321 }
4322 }
4323 }
4324
4325
4326 // Last thread running calls java.lang.Shutdown.shutdown()
4327 void JavaThread::invoke_shutdown_hooks() {
4328 HandleMark hm(this);
4329
4330 // Link all classes for dynamic CDS dumping before vm exit.
4331 // Same operation is being done in JVM_BeforeHalt for handling the
4332 // case where the application calls System.exit().
4333 if (DynamicDumpSharedSpaces) {
4334 MetaspaceShared::link_and_cleanup_shared_classes(this);
4335 }
4336
4337 // We could get here with a pending exception, if so clear it now.
4338 if (this->has_pending_exception()) {
4339 this->clear_pending_exception();
4340 }
4341
4342 EXCEPTION_MARK;
4343 Klass* shutdown_klass =
4344 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4345 THREAD);
4346 if (shutdown_klass != NULL) {
4347 // SystemDictionary::resolve_or_null will return null if there was
4348 // an exception. If we cannot load the Shutdown class, just don't
4349 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4350 // won't be run. Note that if a shutdown hook was registered,
4351 // the Shutdown class would have already been loaded
4352 // (Runtime.addShutdownHook will load it).
4353 JavaValue result(T_VOID);
4354 JavaCalls::call_static(&result,
4355 shutdown_klass,
4356 vmSymbols::shutdown_name(),
4357 vmSymbols::void_method_signature(),
4358 THREAD);
4359 }
4360 CLEAR_PENDING_EXCEPTION;
4361 }
4362
4363 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4364 // the program falls off the end of main(). Another VM exit path is through
4365 // vm_exit() when the program calls System.exit() to return a value or when
4366 // there is a serious error in VM. The two shutdown paths are not exactly
4367 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4368 // and VM_Exit op at VM level.
4369 //
4370 // Shutdown sequence:
4371 // + Shutdown native memory tracking if it is on
4372 // + Wait until we are the last non-daemon thread to execute
4373 // <-- every thing is still working at this moment -->
4374 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4375 // shutdown hooks
4376 // + Call before_exit(), prepare for VM exit
4377 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4378 // currently the only user of this mechanism is File.deleteOnExit())
4379 // > stop StatSampler, watcher thread,
4380 // post thread end and vm death events to JVMTI,
4381 // stop signal thread
4382 // + Call JavaThread::exit(), it will:
4383 // > release JNI handle blocks, remove stack guard pages
4384 // > remove this thread from Threads list
4385 // <-- no more Java code from this thread after this point -->
4386 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4387 // the compiler threads at safepoint
4388 // <-- do not use anything that could get blocked by Safepoint -->
4389 // + Disable tracing at JNI/JVM barriers
4390 // + Set _vm_exited flag for threads that are still running native code
4391 // + Call exit_globals()
4392 // > deletes tty
4393 // > deletes PerfMemory resources
4394 // + Delete this thread
4395 // + Return to caller
4396
4397 bool Threads::destroy_vm() {
4398 JavaThread* thread = JavaThread::current();
4399
4400 #ifdef ASSERT
4401 _vm_complete = false;
4402 #endif
4403 // Wait until we are the last non-daemon thread to execute
4404 { MonitorLocker nu(Threads_lock);
4405 while (Threads::number_of_non_daemon_threads() > 1)
4406 // This wait should make safepoint checks, wait without a timeout,
4407 // and wait as a suspend-equivalent condition.
4408 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4409 }
4410
4411 EventShutdown e;
4412 if (e.should_commit()) {
4413 e.set_reason("No remaining non-daemon Java threads");
4414 e.commit();
4415 }
4416
4417 // Hang forever on exit if we are reporting an error.
4418 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4419 os::infinite_sleep();
4420 }
4421 os::wait_for_keypress_at_exit();
4422
4423 // run Java level shutdown hooks
4424 thread->invoke_shutdown_hooks();
4425
4426 before_exit(thread);
4427
4428 thread->exit(true);
4429
4430 // We are no longer on the main thread list but could still be in a
4431 // secondary list where another thread may try to interact with us.
4432 // So wait until all such interactions are complete before we bring
4433 // the VM to the termination safepoint. Normally this would be done
4434 // using thread->smr_delete() below where we delete the thread, but
4435 // we can't call that after the termination safepoint is active as
4436 // we will deadlock on the Threads_lock. Once all interactions are
4437 // complete it is safe to directly delete the thread at any time.
4438 ThreadsSMRSupport::wait_until_not_protected(thread);
4439
4440 // Stop VM thread.
4441 {
4442 // 4945125 The vm thread comes to a safepoint during exit.
4443 // GC vm_operations can get caught at the safepoint, and the
4444 // heap is unparseable if they are caught. Grab the Heap_lock
4445 // to prevent this. The GC vm_operations will not be able to
4446 // queue until after the vm thread is dead. After this point,
4447 // we'll never emerge out of the safepoint before the VM exits.
4448
4449 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4450
4451 VMThread::wait_for_vm_thread_exit();
4452 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4453 VMThread::destroy();
4454 }
4455
4456 // Now, all Java threads are gone except daemon threads. Daemon threads
4457 // running Java code or in VM are stopped by the Safepoint. However,
4458 // daemon threads executing native code are still running. But they
4459 // will be stopped at native=>Java/VM barriers. Note that we can't
4460 // simply kill or suspend them, as it is inherently deadlock-prone.
4461
4462 VM_Exit::set_vm_exited();
4463
4464 // Clean up ideal graph printers after the VMThread has started
4465 // the final safepoint which will block all the Compiler threads.
4466 // Note that this Thread has already logically exited so the
4467 // clean_up() function's use of a JavaThreadIteratorWithHandle
4468 // would be a problem except set_vm_exited() has remembered the
4469 // shutdown thread which is granted a policy exception.
4470 #if defined(COMPILER2) && !defined(PRODUCT)
4471 IdealGraphPrinter::clean_up();
4472 #endif
4473
4474 notify_vm_shutdown();
4475
4476 // exit_globals() will delete tty
4477 exit_globals();
4478
4479 // Deleting the shutdown thread here is safe. See comment on
4480 // wait_until_not_protected() above.
4481 delete thread;
4482
4483 #if INCLUDE_JVMCI
4484 if (JVMCICounterSize > 0) {
4485 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4486 }
4487 #endif
4488
4489 LogConfiguration::finalize();
4490
4491 return true;
4492 }
4493
4494
4495 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4496 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4497 return is_supported_jni_version(version);
4498 }
4499
4500
4501 jboolean Threads::is_supported_jni_version(jint version) {
4502 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4503 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4504 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4505 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4506 if (version == JNI_VERSION_9) return JNI_TRUE;
4507 if (version == JNI_VERSION_10) return JNI_TRUE;
4508 return JNI_FALSE;
4509 }
4510
4511
4512 void Threads::add(JavaThread* p, bool force_daemon) {
4513 // The threads lock must be owned at this point
4514 assert(Threads_lock->owned_by_self(), "must have threads lock");
4515
4516 BarrierSet::barrier_set()->on_thread_attach(p);
4517
4518 // Once a JavaThread is added to the Threads list, smr_delete() has
4519 // to be used to delete it. Otherwise we can just delete it directly.
4520 p->set_on_thread_list();
4521
4522 _number_of_threads++;
4523 oop threadObj = p->threadObj();
4524 bool daemon = true;
4525 // Bootstrapping problem: threadObj can be null for initial
4526 // JavaThread (or for threads attached via JNI)
4527 if ((!force_daemon) && !is_daemon((threadObj))) {
4528 _number_of_non_daemon_threads++;
4529 daemon = false;
4530 }
4531
4532 ThreadService::add_thread(p, daemon);
4533
4534 // Maintain fast thread list
4535 ThreadsSMRSupport::add_thread(p);
4536
4537 // Possible GC point.
4538 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4539 }
4540
4541 void Threads::remove(JavaThread* p, bool is_daemon) {
4542
4543 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4544 ObjectSynchronizer::om_flush(p);
4545
4546 // Extra scope needed for Thread_lock, so we can check
4547 // that we do not remove thread without safepoint code notice
4548 { MonitorLocker ml(Threads_lock);
4549
4550 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4551
4552 // Maintain fast thread list
4553 ThreadsSMRSupport::remove_thread(p);
4554
4555 _number_of_threads--;
4556 if (!is_daemon) {
4557 _number_of_non_daemon_threads--;
4558
4559 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4560 // on destroy_vm will wake up.
4561 if (number_of_non_daemon_threads() == 1) {
4562 ml.notify_all();
4563 }
4564 }
4565 ThreadService::remove_thread(p, is_daemon);
4566
4567 // Make sure that safepoint code disregard this thread. This is needed since
4568 // the thread might mess around with locks after this point. This can cause it
4569 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4570 // of this thread since it is removed from the queue.
4571 p->set_terminated_value();
4572 } // unlock Threads_lock
4573
4574 // Since Events::log uses a lock, we grab it outside the Threads_lock
4575 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4576 }
4577
4578 // Operations on the Threads list for GC. These are not explicitly locked,
4579 // but the garbage collector must provide a safe context for them to run.
4580 // In particular, these things should never be called when the Threads_lock
4581 // is held by some other thread. (Note: the Safepoint abstraction also
4582 // uses the Threads_lock to guarantee this property. It also makes sure that
4583 // all threads gets blocked when exiting or starting).
4584
4585 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4586 ALL_JAVA_THREADS(p) {
4587 p->oops_do(f, cf);
4588 }
4589 VMThread::vm_thread()->oops_do(f, cf);
4590 }
4591
4592 void Threads::change_thread_claim_token() {
4593 if (++_thread_claim_token == 0) {
4594 // On overflow of the token counter, there is a risk of future
4595 // collisions between a new global token value and a stale token
4596 // for a thread, because not all iterations visit all threads.
4597 // (Though it's pretty much a theoretical concern for non-trivial
4598 // token counter sizes.) To deal with the possibility, reset all
4599 // the thread tokens to zero on global token overflow.
4600 struct ResetClaims : public ThreadClosure {
4601 virtual void do_thread(Thread* t) {
4602 t->claim_threads_do(false, 0);
4603 }
4604 } reset_claims;
4605 Threads::threads_do(&reset_claims);
4606 // On overflow, update the global token to non-zero, to
4607 // avoid the special "never claimed" initial thread value.
4608 _thread_claim_token = 1;
4609 }
4610 }
4611
4612 #ifdef ASSERT
4613 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4614 const uintx token = t->threads_do_token();
4615 assert(token == expected,
4616 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4617 UINTX_FORMAT, kind, p2i(t), token, expected);
4618 }
4619
4620 void Threads::assert_all_threads_claimed() {
4621 ALL_JAVA_THREADS(p) {
4622 assert_thread_claimed("Thread", p, _thread_claim_token);
4623 }
4624 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4625 }
4626 #endif // ASSERT
4627
4628 class ParallelOopsDoThreadClosure : public ThreadClosure {
4629 private:
4630 OopClosure* _f;
4631 CodeBlobClosure* _cf;
4632 public:
4633 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4634 void do_thread(Thread* t) {
4635 t->oops_do(_f, _cf);
4636 }
4637 };
4638
4639 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4640 ParallelOopsDoThreadClosure tc(f, cf);
4641 possibly_parallel_threads_do(is_par, &tc);
4642 }
4643
4644 void Threads::nmethods_do(CodeBlobClosure* cf) {
4645 ALL_JAVA_THREADS(p) {
4646 // This is used by the code cache sweeper to mark nmethods that are active
4647 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4648 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4649 if(!p->is_Code_cache_sweeper_thread()) {
4650 p->nmethods_do(cf);
4651 }
4652 }
4653 }
4654
4655 void Threads::metadata_do(MetadataClosure* f) {
4656 ALL_JAVA_THREADS(p) {
4657 p->metadata_do(f);
4658 }
4659 }
4660
4661 class ThreadHandlesClosure : public ThreadClosure {
4662 void (*_f)(Metadata*);
4663 public:
4664 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4665 virtual void do_thread(Thread* thread) {
4666 thread->metadata_handles_do(_f);
4667 }
4668 };
4669
4670 void Threads::metadata_handles_do(void f(Metadata*)) {
4671 // Only walk the Handles in Thread.
4672 ThreadHandlesClosure handles_closure(f);
4673 threads_do(&handles_closure);
4674 }
4675
4676 // Get count Java threads that are waiting to enter the specified monitor.
4677 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4678 int count,
4679 address monitor) {
4680 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4681
4682 int i = 0;
4683 DO_JAVA_THREADS(t_list, p) {
4684 if (!p->can_call_java()) continue;
4685
4686 address pending = (address)p->current_pending_monitor();
4687 if (pending == monitor) { // found a match
4688 if (i < count) result->append(p); // save the first count matches
4689 i++;
4690 }
4691 }
4692
4693 return result;
4694 }
4695
4696
4697 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4698 address owner) {
4699 // NULL owner means not locked so we can skip the search
4700 if (owner == NULL) return NULL;
4701
4702 DO_JAVA_THREADS(t_list, p) {
4703 // first, see if owner is the address of a Java thread
4704 if (owner == (address)p) return p;
4705 }
4706
4707 // Cannot assert on lack of success here since this function may be
4708 // used by code that is trying to report useful problem information
4709 // like deadlock detection.
4710 if (UseHeavyMonitors) return NULL;
4711
4712 // If we didn't find a matching Java thread and we didn't force use of
4713 // heavyweight monitors, then the owner is the stack address of the
4714 // Lock Word in the owning Java thread's stack.
4715 //
4716 JavaThread* the_owner = NULL;
4717 DO_JAVA_THREADS(t_list, q) {
4718 if (q->is_lock_owned(owner)) {
4719 the_owner = q;
4720 break;
4721 }
4722 }
4723
4724 // cannot assert on lack of success here; see above comment
4725 return the_owner;
4726 }
4727
4728 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4729 void Threads::print_on(outputStream* st, bool print_stacks,
4730 bool internal_format, bool print_concurrent_locks,
4731 bool print_extended_info) {
4732 char buf[32];
4733 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4734
4735 st->print_cr("Full thread dump %s (%s %s):",
4736 VM_Version::vm_name(),
4737 VM_Version::vm_release(),
4738 VM_Version::vm_info_string());
4739 st->cr();
4740
4741 #if INCLUDE_SERVICES
4742 // Dump concurrent locks
4743 ConcurrentLocksDump concurrent_locks;
4744 if (print_concurrent_locks) {
4745 concurrent_locks.dump_at_safepoint();
4746 }
4747 #endif // INCLUDE_SERVICES
4748
4749 ThreadsSMRSupport::print_info_on(st);
4750 st->cr();
4751
4752 ALL_JAVA_THREADS(p) {
4753 ResourceMark rm;
4754 p->print_on(st, print_extended_info);
4755 if (print_stacks) {
4756 if (internal_format) {
4757 p->trace_stack();
4758 } else {
4759 p->print_stack_on(st);
4760 }
4761 }
4762 st->cr();
4763 #if INCLUDE_SERVICES
4764 if (print_concurrent_locks) {
4765 concurrent_locks.print_locks_on(p, st);
4766 }
4767 #endif // INCLUDE_SERVICES
4768 }
4769
4770 VMThread::vm_thread()->print_on(st);
4771 st->cr();
4772 Universe::heap()->print_gc_threads_on(st);
4773 WatcherThread* wt = WatcherThread::watcher_thread();
4774 if (wt != NULL) {
4775 wt->print_on(st);
4776 st->cr();
4777 }
4778
4779 st->flush();
4780 }
4781
4782 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4783 int buflen, bool* found_current) {
4784 if (this_thread != NULL) {
4785 bool is_current = (current == this_thread);
4786 *found_current = *found_current || is_current;
4787 st->print("%s", is_current ? "=>" : " ");
4788
4789 st->print(PTR_FORMAT, p2i(this_thread));
4790 st->print(" ");
4791 this_thread->print_on_error(st, buf, buflen);
4792 st->cr();
4793 }
4794 }
4795
4796 class PrintOnErrorClosure : public ThreadClosure {
4797 outputStream* _st;
4798 Thread* _current;
4799 char* _buf;
4800 int _buflen;
4801 bool* _found_current;
4802 public:
4803 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4804 int buflen, bool* found_current) :
4805 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4806
4807 virtual void do_thread(Thread* thread) {
4808 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4809 }
4810 };
4811
4812 // Threads::print_on_error() is called by fatal error handler. It's possible
4813 // that VM is not at safepoint and/or current thread is inside signal handler.
4814 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4815 // memory (even in resource area), it might deadlock the error handler.
4816 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4817 int buflen) {
4818 ThreadsSMRSupport::print_info_on(st);
4819 st->cr();
4820
4821 bool found_current = false;
4822 st->print_cr("Java Threads: ( => current thread )");
4823 ALL_JAVA_THREADS(thread) {
4824 print_on_error(thread, st, current, buf, buflen, &found_current);
4825 }
4826 st->cr();
4827
4828 st->print_cr("Other Threads:");
4829 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4830 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4831
4832 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4833 Universe::heap()->gc_threads_do(&print_closure);
4834
4835 if (!found_current) {
4836 st->cr();
4837 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4838 current->print_on_error(st, buf, buflen);
4839 st->cr();
4840 }
4841 st->cr();
4842
4843 st->print_cr("Threads with active compile tasks:");
4844 print_threads_compiling(st, buf, buflen);
4845 }
4846
4847 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4848 ALL_JAVA_THREADS(thread) {
4849 if (thread->is_Compiler_thread()) {
4850 CompilerThread* ct = (CompilerThread*) thread;
4851
4852 // Keep task in local variable for NULL check.
4853 // ct->_task might be set to NULL by concurring compiler thread
4854 // because it completed the compilation. The task is never freed,
4855 // though, just returned to a free list.
4856 CompileTask* task = ct->task();
4857 if (task != NULL) {
4858 thread->print_name_on_error(st, buf, buflen);
4859 st->print(" ");
4860 task->print(st, NULL, short_form, true);
4861 }
4862 }
4863 }
4864 }
4865
4866
4867 // Internal SpinLock and Mutex
4868 // Based on ParkEvent
4869
4870 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4871 //
4872 // We employ SpinLocks _only for low-contention, fixed-length
4873 // short-duration critical sections where we're concerned
4874 // about native mutex_t or HotSpot Mutex:: latency.
4875 // The mux construct provides a spin-then-block mutual exclusion
4876 // mechanism.
4877 //
4878 // Testing has shown that contention on the ListLock guarding gFreeList
4879 // is common. If we implement ListLock as a simple SpinLock it's common
4880 // for the JVM to devolve to yielding with little progress. This is true
4881 // despite the fact that the critical sections protected by ListLock are
4882 // extremely short.
4883 //
4884 // TODO-FIXME: ListLock should be of type SpinLock.
4885 // We should make this a 1st-class type, integrated into the lock
4886 // hierarchy as leaf-locks. Critically, the SpinLock structure
4887 // should have sufficient padding to avoid false-sharing and excessive
4888 // cache-coherency traffic.
4889
4890
4891 typedef volatile int SpinLockT;
4892
4893 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4894 if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4895 return; // normal fast-path return
4896 }
4897
4898 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4899 int ctr = 0;
4900 int Yields = 0;
4901 for (;;) {
4902 while (*adr != 0) {
4903 ++ctr;
4904 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4905 if (Yields > 5) {
4906 os::naked_short_sleep(1);
4907 } else {
4908 os::naked_yield();
4909 ++Yields;
4910 }
4911 } else {
4912 SpinPause();
4913 }
4914 }
4915 if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4916 }
4917 }
4918
4919 void Thread::SpinRelease(volatile int * adr) {
4920 assert(*adr != 0, "invariant");
4921 OrderAccess::fence(); // guarantee at least release consistency.
4922 // Roach-motel semantics.
4923 // It's safe if subsequent LDs and STs float "up" into the critical section,
4924 // but prior LDs and STs within the critical section can't be allowed
4925 // to reorder or float past the ST that releases the lock.
4926 // Loads and stores in the critical section - which appear in program
4927 // order before the store that releases the lock - must also appear
4928 // before the store that releases the lock in memory visibility order.
4929 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4930 // the ST of 0 into the lock-word which releases the lock, so fence
4931 // more than covers this on all platforms.
4932 *adr = 0;
4933 }
4934
4935 // muxAcquire and muxRelease:
4936 //
4937 // * muxAcquire and muxRelease support a single-word lock-word construct.
4938 // The LSB of the word is set IFF the lock is held.
4939 // The remainder of the word points to the head of a singly-linked list
4940 // of threads blocked on the lock.
4941 //
4942 // * The current implementation of muxAcquire-muxRelease uses its own
4943 // dedicated Thread._MuxEvent instance. If we're interested in
4944 // minimizing the peak number of extant ParkEvent instances then
4945 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4946 // as certain invariants were satisfied. Specifically, care would need
4947 // to be taken with regards to consuming unpark() "permits".
4948 // A safe rule of thumb is that a thread would never call muxAcquire()
4949 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4950 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4951 // consume an unpark() permit intended for monitorenter, for instance.
4952 // One way around this would be to widen the restricted-range semaphore
4953 // implemented in park(). Another alternative would be to provide
4954 // multiple instances of the PlatformEvent() for each thread. One
4955 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4956 //
4957 // * Usage:
4958 // -- Only as leaf locks
4959 // -- for short-term locking only as muxAcquire does not perform
4960 // thread state transitions.
4961 //
4962 // Alternatives:
4963 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4964 // but with parking or spin-then-park instead of pure spinning.
4965 // * Use Taura-Oyama-Yonenzawa locks.
4966 // * It's possible to construct a 1-0 lock if we encode the lockword as
4967 // (List,LockByte). Acquire will CAS the full lockword while Release
4968 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4969 // acquiring threads use timers (ParkTimed) to detect and recover from
4970 // the stranding window. Thread/Node structures must be aligned on 256-byte
4971 // boundaries by using placement-new.
4972 // * Augment MCS with advisory back-link fields maintained with CAS().
4973 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4974 // The validity of the backlinks must be ratified before we trust the value.
4975 // If the backlinks are invalid the exiting thread must back-track through the
4976 // the forward links, which are always trustworthy.
4977 // * Add a successor indication. The LockWord is currently encoded as
4978 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4979 // to provide the usual futile-wakeup optimization.
4980 // See RTStt for details.
4981 //
4982
4983
4984 const intptr_t LOCKBIT = 1;
4985
4986 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4987 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
4988 if (w == 0) return;
4989 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
4990 return;
4991 }
4992
4993 ParkEvent * const Self = Thread::current()->_MuxEvent;
4994 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4995 for (;;) {
4996 int its = (os::is_MP() ? 100 : 0) + 1;
4997
4998 // Optional spin phase: spin-then-park strategy
4999 while (--its >= 0) {
5000 w = *Lock;
5001 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5002 return;
5003 }
5004 }
5005
5006 Self->reset();
5007 Self->OnList = intptr_t(Lock);
5008 // The following fence() isn't _strictly necessary as the subsequent
5009 // CAS() both serializes execution and ratifies the fetched *Lock value.
5010 OrderAccess::fence();
5011 for (;;) {
5012 w = *Lock;
5013 if ((w & LOCKBIT) == 0) {
5014 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5015 Self->OnList = 0; // hygiene - allows stronger asserts
5016 return;
5017 }
5018 continue; // Interference -- *Lock changed -- Just retry
5019 }
5020 assert(w & LOCKBIT, "invariant");
5021 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5022 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5023 }
5024
5025 while (Self->OnList != 0) {
5026 Self->park();
5027 }
5028 }
5029 }
5030
5031 // Release() must extract a successor from the list and then wake that thread.
5032 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5033 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5034 // Release() would :
5035 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5036 // (B) Extract a successor from the private list "in-hand"
5037 // (C) attempt to CAS() the residual back into *Lock over null.
5038 // If there were any newly arrived threads and the CAS() would fail.
5039 // In that case Release() would detach the RATs, re-merge the list in-hand
5040 // with the RATs and repeat as needed. Alternately, Release() might
5041 // detach and extract a successor, but then pass the residual list to the wakee.
5042 // The wakee would be responsible for reattaching and remerging before it
5043 // competed for the lock.
5044 //
5045 // Both "pop" and DMR are immune from ABA corruption -- there can be
5046 // multiple concurrent pushers, but only one popper or detacher.
5047 // This implementation pops from the head of the list. This is unfair,
5048 // but tends to provide excellent throughput as hot threads remain hot.
5049 // (We wake recently run threads first).
5050 //
5051 // All paths through muxRelease() will execute a CAS.
5052 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5053 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5054 // executed within the critical section are complete and globally visible before the
5055 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5056 void Thread::muxRelease(volatile intptr_t * Lock) {
5057 for (;;) {
5058 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5059 assert(w & LOCKBIT, "invariant");
5060 if (w == LOCKBIT) return;
5061 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5062 assert(List != NULL, "invariant");
5063 assert(List->OnList == intptr_t(Lock), "invariant");
5064 ParkEvent * const nxt = List->ListNext;
5065 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5066
5067 // The following CAS() releases the lock and pops the head element.
5068 // The CAS() also ratifies the previously fetched lock-word value.
5069 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5070 continue;
5071 }
5072 List->OnList = 0;
5073 OrderAccess::fence();
5074 List->unpark();
5075 return;
5076 }
5077 }
5078
5079
5080 void Threads::verify() {
5081 ALL_JAVA_THREADS(p) {
5082 p->verify();
5083 }
5084 VMThread* thread = VMThread::vm_thread();
5085 if (thread != NULL) thread->verify();
5086 }