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, mtClass));
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 // Set stack limits after thread is initialized.
355 if (is_Java_thread()) {
356 ((JavaThread*) this)->set_stack_overflow_limit();
357 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
358 }
359 }
360
361 #if INCLUDE_NMT
362 void Thread::register_thread_stack_with_NMT() {
363 MemTracker::record_thread_stack(stack_end(), stack_size());
364 }
365 #endif // INCLUDE_NMT
366
367 void Thread::call_run() {
368 DEBUG_ONLY(_run_state = CALL_RUN;)
369
370 // At this point, Thread object should be fully initialized and
371 // Thread::current() should be set.
372
373 assert(Thread::current_or_null() != NULL, "current thread is unset");
374 assert(Thread::current_or_null() == this, "current thread is wrong");
375
376 // Perform common initialization actions
377
378 register_thread_stack_with_NMT();
379
380 JFR_ONLY(Jfr::on_thread_start(this);)
381
382 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
383 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
384 os::current_thread_id(), p2i(stack_end()),
385 p2i(stack_base()), stack_size()/1024);
386
387 // Perform <ChildClass> initialization actions
388 DEBUG_ONLY(_run_state = PRE_RUN;)
389 this->pre_run();
390
391 // Invoke <ChildClass>::run()
392 DEBUG_ONLY(_run_state = RUN;)
393 this->run();
394 // Returned from <ChildClass>::run(). Thread finished.
395
396 // Perform common tear-down actions
397
398 assert(Thread::current_or_null() != NULL, "current thread is unset");
399 assert(Thread::current_or_null() == this, "current thread is wrong");
400
401 // Perform <ChildClass> tear-down actions
402 DEBUG_ONLY(_run_state = POST_RUN;)
403 this->post_run();
404
405 // Note: at this point the thread object may already have deleted itself,
406 // so from here on do not dereference *this*. Not all thread types currently
407 // delete themselves when they terminate. But no thread should ever be deleted
408 // asynchronously with respect to its termination - that is what _run_state can
409 // be used to check.
410
411 assert(Thread::current_or_null() == NULL, "current thread still present");
412 }
413
414 Thread::~Thread() {
415
416 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
417 // get started due to errors etc. Any active thread should at least reach post_run
418 // before it is deleted (usually in post_run()).
419 assert(_run_state == PRE_CALL_RUN ||
420 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
421 "_run_state=%d", (int)_run_state);
422
423 // Notify the barrier set that a thread is being destroyed. Note that a barrier
424 // set might not be available if we encountered errors during bootstrapping.
425 BarrierSet* const barrier_set = BarrierSet::barrier_set();
426 if (barrier_set != NULL) {
427 barrier_set->on_thread_destroy(this);
428 }
429
430 // stack_base can be NULL if the thread is never started or exited before
431 // record_stack_base_and_size called. Although, we would like to ensure
432 // that all started threads do call record_stack_base_and_size(), there is
433 // not proper way to enforce that.
434 #if INCLUDE_NMT
435 if (_stack_base != NULL) {
436 MemTracker::release_thread_stack(stack_end(), stack_size());
437 #ifdef ASSERT
438 set_stack_base(NULL);
439 #endif
440 }
441 #endif // INCLUDE_NMT
442
443 // deallocate data structures
444 delete resource_area();
445 // since the handle marks are using the handle area, we have to deallocated the root
446 // handle mark before deallocating the thread's handle area,
447 assert(last_handle_mark() != NULL, "check we have an element");
448 delete last_handle_mark();
449 assert(last_handle_mark() == NULL, "check we have reached the end");
450
451 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
452 // We NULL out the fields for good hygiene.
453 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
454 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
455
456 delete handle_area();
457 delete metadata_handles();
458
459 // SR_handler uses this as a termination indicator -
460 // needs to happen before os::free_thread()
461 delete _SR_lock;
462 _SR_lock = NULL;
463
464 // osthread() can be NULL, if creation of thread failed.
465 if (osthread() != NULL) os::free_thread(osthread());
466
467 // Clear Thread::current if thread is deleting itself and it has not
468 // already been done. This must be done before the memory is deallocated.
469 // Needed to ensure JNI correctly detects non-attached threads.
470 if (this == Thread::current_or_null()) {
471 Thread::clear_thread_current();
472 }
473
474 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
475 }
476
477 #ifdef ASSERT
478 // A JavaThread is considered "dangling" if it is not the current
479 // thread, has been added the Threads list, the system is not at a
480 // safepoint and the Thread is not "protected".
481 //
482 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
483 assert(!thread->is_Java_thread() || Thread::current() == thread ||
484 !((JavaThread *) thread)->on_thread_list() ||
485 SafepointSynchronize::is_at_safepoint() ||
486 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
487 "possibility of dangling Thread pointer");
488 }
489 #endif
490
491 ThreadPriority Thread::get_priority(const Thread* const thread) {
492 ThreadPriority priority;
493 // Can return an error!
494 (void)os::get_priority(thread, priority);
495 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
496 return priority;
497 }
498
499 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
500 debug_only(check_for_dangling_thread_pointer(thread);)
501 // Can return an error!
502 (void)os::set_priority(thread, priority);
503 }
504
505
506 void Thread::start(Thread* thread) {
507 // Start is different from resume in that its safety is guaranteed by context or
508 // being called from a Java method synchronized on the Thread object.
509 if (!DisableStartThread) {
510 if (thread->is_Java_thread()) {
511 // Initialize the thread state to RUNNABLE before starting this thread.
512 // Can not set it after the thread started because we do not know the
513 // exact thread state at that time. It could be in MONITOR_WAIT or
514 // in SLEEPING or some other state.
515 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
516 java_lang_Thread::RUNNABLE);
517 }
518 os::start_thread(thread);
519 }
520 }
521
522 class InstallAsyncExceptionClosure : public HandshakeClosure {
523 Handle _throwable; // The Throwable thrown at the target Thread
524 public:
525 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {}
526
527 void do_thread(Thread* thr) {
528 JavaThread* target = (JavaThread*)thr;
529 // Note that this now allows multiple ThreadDeath exceptions to be
530 // thrown at a thread.
531 // The target thread has run and has not exited yet.
532 target->send_thread_stop(_throwable());
533 }
534 };
535
536 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
537 Handle throwable(Thread::current(), java_throwable);
538 JavaThread* target = java_lang_Thread::thread(java_thread);
539 InstallAsyncExceptionClosure vm_stop(throwable);
540 Handshake::execute(&vm_stop, target);
541 }
542
543
544 // Check if an external suspend request has completed (or has been
545 // cancelled). Returns true if the thread is externally suspended and
546 // false otherwise.
547 //
548 // The bits parameter returns information about the code path through
549 // the routine. Useful for debugging:
550 //
551 // set in is_ext_suspend_completed():
552 // 0x00000001 - routine was entered
553 // 0x00000010 - routine return false at end
554 // 0x00000100 - thread exited (return false)
555 // 0x00000200 - suspend request cancelled (return false)
556 // 0x00000400 - thread suspended (return true)
557 // 0x00001000 - thread is in a suspend equivalent state (return true)
558 // 0x00002000 - thread is native and walkable (return true)
559 // 0x00004000 - thread is native_trans and walkable (needed retry)
560 //
561 // set in wait_for_ext_suspend_completion():
562 // 0x00010000 - routine was entered
563 // 0x00020000 - suspend request cancelled before loop (return false)
564 // 0x00040000 - thread suspended before loop (return true)
565 // 0x00080000 - suspend request cancelled in loop (return false)
566 // 0x00100000 - thread suspended in loop (return true)
567 // 0x00200000 - suspend not completed during retry loop (return false)
568
569 // Helper class for tracing suspend wait debug bits.
570 //
571 // 0x00000100 indicates that the target thread exited before it could
572 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
573 // 0x00080000 each indicate a cancelled suspend request so they don't
574 // count as wait failures either.
575 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
576
577 class TraceSuspendDebugBits : public StackObj {
578 private:
579 JavaThread * jt;
580 bool is_wait;
581 bool called_by_wait; // meaningful when !is_wait
582 uint32_t * bits;
583
584 public:
585 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
586 uint32_t *_bits) {
587 jt = _jt;
588 is_wait = _is_wait;
589 called_by_wait = _called_by_wait;
590 bits = _bits;
591 }
592
593 ~TraceSuspendDebugBits() {
594 if (!is_wait) {
595 #if 1
596 // By default, don't trace bits for is_ext_suspend_completed() calls.
597 // That trace is very chatty.
598 return;
599 #else
600 if (!called_by_wait) {
601 // If tracing for is_ext_suspend_completed() is enabled, then only
602 // trace calls to it from wait_for_ext_suspend_completion()
603 return;
604 }
605 #endif
606 }
607
608 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
609 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
610 MutexLocker ml(Threads_lock); // needed for get_thread_name()
611 ResourceMark rm;
612
613 tty->print_cr(
614 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
615 jt->get_thread_name(), *bits);
616
617 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
618 }
619 }
620 }
621 };
622 #undef DEBUG_FALSE_BITS
623
624
625 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
626 uint32_t *bits) {
627 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
628
629 bool did_trans_retry = false; // only do thread_in_native_trans retry once
630 bool do_trans_retry; // flag to force the retry
631
632 *bits |= 0x00000001;
633
634 do {
635 do_trans_retry = false;
636
637 if (is_exiting()) {
638 // Thread is in the process of exiting. This is always checked
639 // first to reduce the risk of dereferencing a freed JavaThread.
640 *bits |= 0x00000100;
641 return false;
642 }
643
644 if (!is_external_suspend()) {
645 // Suspend request is cancelled. This is always checked before
646 // is_ext_suspended() to reduce the risk of a rogue resume
647 // confusing the thread that made the suspend request.
648 *bits |= 0x00000200;
649 return false;
650 }
651
652 if (is_ext_suspended()) {
653 // thread is suspended
654 *bits |= 0x00000400;
655 return true;
656 }
657
658 // Now that we no longer do hard suspends of threads running
659 // native code, the target thread can be changing thread state
660 // while we are in this routine:
661 //
662 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
663 //
664 // We save a copy of the thread state as observed at this moment
665 // and make our decision about suspend completeness based on the
666 // copy. This closes the race where the thread state is seen as
667 // _thread_in_native_trans in the if-thread_blocked check, but is
668 // seen as _thread_blocked in if-thread_in_native_trans check.
669 JavaThreadState save_state = thread_state();
670
671 if (save_state == _thread_blocked && is_suspend_equivalent()) {
672 // If the thread's state is _thread_blocked and this blocking
673 // condition is known to be equivalent to a suspend, then we can
674 // consider the thread to be externally suspended. This means that
675 // the code that sets _thread_blocked has been modified to do
676 // self-suspension if the blocking condition releases. We also
677 // used to check for CONDVAR_WAIT here, but that is now covered by
678 // the _thread_blocked with self-suspension check.
679 //
680 // Return true since we wouldn't be here unless there was still an
681 // external suspend request.
682 *bits |= 0x00001000;
683 return true;
684 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
685 // Threads running native code will self-suspend on native==>VM/Java
686 // transitions. If its stack is walkable (should always be the case
687 // unless this function is called before the actual java_suspend()
688 // call), then the wait is done.
689 *bits |= 0x00002000;
690 return true;
691 } else if (!called_by_wait && !did_trans_retry &&
692 save_state == _thread_in_native_trans &&
693 frame_anchor()->walkable()) {
694 // The thread is transitioning from thread_in_native to another
695 // thread state. check_safepoint_and_suspend_for_native_trans()
696 // will force the thread to self-suspend. If it hasn't gotten
697 // there yet we may have caught the thread in-between the native
698 // code check above and the self-suspend. Lucky us. If we were
699 // called by wait_for_ext_suspend_completion(), then it
700 // will be doing the retries so we don't have to.
701 //
702 // Since we use the saved thread state in the if-statement above,
703 // there is a chance that the thread has already transitioned to
704 // _thread_blocked by the time we get here. In that case, we will
705 // make a single unnecessary pass through the logic below. This
706 // doesn't hurt anything since we still do the trans retry.
707
708 *bits |= 0x00004000;
709
710 // Once the thread leaves thread_in_native_trans for another
711 // thread state, we break out of this retry loop. We shouldn't
712 // need this flag to prevent us from getting back here, but
713 // sometimes paranoia is good.
714 did_trans_retry = true;
715
716 // We wait for the thread to transition to a more usable state.
717 for (int i = 1; i <= SuspendRetryCount; i++) {
718 // We used to do an "os::yield_all(i)" call here with the intention
719 // that yielding would increase on each retry. However, the parameter
720 // is ignored on Linux which means the yield didn't scale up. Waiting
721 // on the SR_lock below provides a much more predictable scale up for
722 // the delay. It also provides a simple/direct point to check for any
723 // safepoint requests from the VMThread
724
725 // temporarily drops SR_lock while doing wait with safepoint check
726 // (if we're a JavaThread - the WatcherThread can also call this)
727 // and increase delay with each retry
728 if (Thread::current()->is_Java_thread()) {
729 SR_lock()->wait(i * delay);
730 } else {
731 SR_lock()->wait_without_safepoint_check(i * delay);
732 }
733
734 // check the actual thread state instead of what we saved above
735 if (thread_state() != _thread_in_native_trans) {
736 // the thread has transitioned to another thread state so
737 // try all the checks (except this one) one more time.
738 do_trans_retry = true;
739 break;
740 }
741 } // end retry loop
742
743
744 }
745 } while (do_trans_retry);
746
747 *bits |= 0x00000010;
748 return false;
749 }
750
751 // Wait for an external suspend request to complete (or be cancelled).
752 // Returns true if the thread is externally suspended and false otherwise.
753 //
754 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
755 uint32_t *bits) {
756 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
757 false /* !called_by_wait */, bits);
758
759 // local flag copies to minimize SR_lock hold time
760 bool is_suspended;
761 bool pending;
762 uint32_t reset_bits;
763
764 // set a marker so is_ext_suspend_completed() knows we are the caller
765 *bits |= 0x00010000;
766
767 // We use reset_bits to reinitialize the bits value at the top of
768 // each retry loop. This allows the caller to make use of any
769 // unused bits for their own marking purposes.
770 reset_bits = *bits;
771
772 {
773 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
774 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
775 delay, bits);
776 pending = is_external_suspend();
777 }
778 // must release SR_lock to allow suspension to complete
779
780 if (!pending) {
781 // A cancelled suspend request is the only false return from
782 // is_ext_suspend_completed() that keeps us from entering the
783 // retry loop.
784 *bits |= 0x00020000;
785 return false;
786 }
787
788 if (is_suspended) {
789 *bits |= 0x00040000;
790 return true;
791 }
792
793 for (int i = 1; i <= retries; i++) {
794 *bits = reset_bits; // reinit to only track last retry
795
796 // We used to do an "os::yield_all(i)" call here with the intention
797 // that yielding would increase on each retry. However, the parameter
798 // is ignored on Linux which means the yield didn't scale up. Waiting
799 // on the SR_lock below provides a much more predictable scale up for
800 // the delay. It also provides a simple/direct point to check for any
801 // safepoint requests from the VMThread
802
803 {
804 Thread* t = Thread::current();
805 MonitorLocker ml(SR_lock(),
806 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
807 // wait with safepoint check (if we're a JavaThread - the WatcherThread
808 // can also call this) and increase delay with each retry
809 ml.wait(i * delay);
810
811 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
812 delay, bits);
813
814 // It is possible for the external suspend request to be cancelled
815 // (by a resume) before the actual suspend operation is completed.
816 // Refresh our local copy to see if we still need to wait.
817 pending = is_external_suspend();
818 }
819
820 if (!pending) {
821 // A cancelled suspend request is the only false return from
822 // is_ext_suspend_completed() that keeps us from staying in the
823 // retry loop.
824 *bits |= 0x00080000;
825 return false;
826 }
827
828 if (is_suspended) {
829 *bits |= 0x00100000;
830 return true;
831 }
832 } // end retry loop
833
834 // thread did not suspend after all our retries
835 *bits |= 0x00200000;
836 return false;
837 }
838
839 // Called from API entry points which perform stack walking. If the
840 // associated JavaThread is the current thread, then wait_for_suspend
841 // is not used. Otherwise, it determines if we should wait for the
842 // "other" thread to complete external suspension. (NOTE: in future
843 // releases the suspension mechanism should be reimplemented so this
844 // is not necessary.)
845 //
846 bool
847 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
848 if (this != JavaThread::current()) {
849 // "other" threads require special handling.
850 if (wait_for_suspend) {
851 // We are allowed to wait for the external suspend to complete
852 // so give the other thread a chance to get suspended.
853 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
854 SuspendRetryDelay, bits)) {
855 // Didn't make it so let the caller know.
856 return false;
857 }
858 }
859 // We aren't allowed to wait for the external suspend to complete
860 // so if the other thread isn't externally suspended we need to
861 // let the caller know.
862 else if (!is_ext_suspend_completed_with_lock(bits)) {
863 return false;
864 }
865 }
866
867 return true;
868 }
869
870 // GC Support
871 bool Thread::claim_par_threads_do(uintx claim_token) {
872 uintx token = _threads_do_token;
873 if (token != claim_token) {
874 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token);
875 if (res == token) {
876 return true;
877 }
878 guarantee(res == claim_token, "invariant");
879 }
880 return false;
881 }
882
883 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
884 if (active_handles() != NULL) {
885 active_handles()->oops_do(f);
886 }
887 // Do oop for ThreadShadow
888 f->do_oop((oop*)&_pending_exception);
889 handle_area()->oops_do(f);
890
891 // We scan thread local monitor lists here, and the remaining global
892 // monitors in ObjectSynchronizer::oops_do().
893 ObjectSynchronizer::thread_local_used_oops_do(this, f);
894 }
895
896 void Thread::metadata_handles_do(void f(Metadata*)) {
897 // Only walk the Handles in Thread.
898 if (metadata_handles() != NULL) {
899 for (int i = 0; i< metadata_handles()->length(); i++) {
900 f(metadata_handles()->at(i));
901 }
902 }
903 }
904
905 void Thread::print_on(outputStream* st, bool print_extended_info) const {
906 // get_priority assumes osthread initialized
907 if (osthread() != NULL) {
908 int os_prio;
909 if (os::get_native_priority(this, &os_prio) == OS_OK) {
910 st->print("os_prio=%d ", os_prio);
911 }
912
913 st->print("cpu=%.2fms ",
914 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
915 );
916 st->print("elapsed=%.2fs ",
917 _statistical_info.getElapsedTime() / 1000.0
918 );
919 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
920 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
921 st->print("allocated=" SIZE_FORMAT "%s ",
922 byte_size_in_proper_unit(allocated_bytes),
923 proper_unit_for_byte_size(allocated_bytes)
924 );
925 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
926 }
927
928 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
929 osthread()->print_on(st);
930 }
931 ThreadsSMRSupport::print_info_on(this, st);
932 st->print(" ");
933 debug_only(if (WizardMode) print_owned_locks_on(st);)
934 }
935
936 void Thread::print() const { print_on(tty); }
937
938 // Thread::print_on_error() is called by fatal error handler. Don't use
939 // any lock or allocate memory.
940 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
941 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
942
943 if (is_VM_thread()) { st->print("VMThread"); }
944 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
945 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
946 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
947 else { st->print("Thread"); }
948
949 if (is_Named_thread()) {
950 st->print(" \"%s\"", name());
951 }
952
953 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
954 p2i(stack_end()), p2i(stack_base()));
955
956 if (osthread()) {
957 st->print(" [id=%d]", osthread()->thread_id());
958 }
959
960 ThreadsSMRSupport::print_info_on(this, st);
961 }
962
963 void Thread::print_value_on(outputStream* st) const {
964 if (is_Named_thread()) {
965 st->print(" \"%s\" ", name());
966 }
967 st->print(INTPTR_FORMAT, p2i(this)); // print address
968 }
969
970 #ifdef ASSERT
971 void Thread::print_owned_locks_on(outputStream* st) const {
972 Mutex* cur = _owned_locks;
973 if (cur == NULL) {
974 st->print(" (no locks) ");
975 } else {
976 st->print_cr(" Locks owned:");
977 while (cur) {
978 cur->print_on(st);
979 cur = cur->next();
980 }
981 }
982 }
983
984 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
985 void Thread::check_possible_safepoint() {
986 if (!is_Java_thread()) return;
987
988 if (_no_safepoint_count > 0) {
989 print_owned_locks();
990 fatal("Possible safepoint reached by thread that does not allow it");
991 }
992 #ifdef CHECK_UNHANDLED_OOPS
993 // Clear unhandled oops in JavaThreads so we get a crash right away.
994 clear_unhandled_oops();
995 #endif // CHECK_UNHANDLED_OOPS
996 }
997
998 void Thread::check_for_valid_safepoint_state() {
999 if (!is_Java_thread()) return;
1000
1001 // Check NoSafepointVerifier, which is implied by locks taken that can be
1002 // shared with the VM thread. This makes sure that no locks with allow_vm_block
1003 // are held.
1004 check_possible_safepoint();
1005
1006 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1007 fatal("LEAF method calling lock?");
1008 }
1009
1010 if (GCALotAtAllSafepoints) {
1011 // We could enter a safepoint here and thus have a gc
1012 InterfaceSupport::check_gc_alot();
1013 }
1014 }
1015 #endif // ASSERT
1016
1017 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1018 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1019 // used for compilation in the future. If that change is made, the need for these methods
1020 // should be revisited, and they should be removed if possible.
1021
1022 bool Thread::is_lock_owned(address adr) const {
1023 return is_in_full_stack(adr);
1024 }
1025
1026 bool Thread::set_as_starting_thread() {
1027 assert(_starting_thread == NULL, "already initialized: "
1028 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1029 // NOTE: this must be called inside the main thread.
1030 DEBUG_ONLY(_starting_thread = this;)
1031 return os::create_main_thread((JavaThread*)this);
1032 }
1033
1034 static void initialize_class(Symbol* class_name, TRAPS) {
1035 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1036 InstanceKlass::cast(klass)->initialize(CHECK);
1037 }
1038
1039
1040 // Creates the initial ThreadGroup
1041 static Handle create_initial_thread_group(TRAPS) {
1042 Handle system_instance = JavaCalls::construct_new_instance(
1043 SystemDictionary::ThreadGroup_klass(),
1044 vmSymbols::void_method_signature(),
1045 CHECK_NH);
1046 Universe::set_system_thread_group(system_instance());
1047
1048 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1049 Handle main_instance = JavaCalls::construct_new_instance(
1050 SystemDictionary::ThreadGroup_klass(),
1051 vmSymbols::threadgroup_string_void_signature(),
1052 system_instance,
1053 string,
1054 CHECK_NH);
1055 return main_instance;
1056 }
1057
1058 // Creates the initial Thread
1059 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1060 TRAPS) {
1061 InstanceKlass* ik = SystemDictionary::Thread_klass();
1062 assert(ik->is_initialized(), "must be");
1063 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1064
1065 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1066 // constructor calls Thread.current(), which must be set here for the
1067 // initial thread.
1068 java_lang_Thread::set_thread(thread_oop(), thread);
1069 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1070 thread->set_threadObj(thread_oop());
1071
1072 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1073
1074 JavaValue result(T_VOID);
1075 JavaCalls::call_special(&result, thread_oop,
1076 ik,
1077 vmSymbols::object_initializer_name(),
1078 vmSymbols::threadgroup_string_void_signature(),
1079 thread_group,
1080 string,
1081 CHECK_NULL);
1082 return thread_oop();
1083 }
1084
1085 char java_runtime_name[128] = "";
1086 char java_runtime_version[128] = "";
1087 char java_runtime_vendor_version[128] = "";
1088 char java_runtime_vendor_vm_bug_url[128] = "";
1089
1090 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1091 static const char* get_java_runtime_name(TRAPS) {
1092 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1093 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1094 fieldDescriptor fd;
1095 bool found = k != NULL &&
1096 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1097 vmSymbols::string_signature(), &fd);
1098 if (found) {
1099 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1100 if (name_oop == NULL) {
1101 return NULL;
1102 }
1103 const char* name = java_lang_String::as_utf8_string(name_oop,
1104 java_runtime_name,
1105 sizeof(java_runtime_name));
1106 return name;
1107 } else {
1108 return NULL;
1109 }
1110 }
1111
1112 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1113 static const char* get_java_runtime_version(TRAPS) {
1114 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1115 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1116 fieldDescriptor fd;
1117 bool found = k != NULL &&
1118 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1119 vmSymbols::string_signature(), &fd);
1120 if (found) {
1121 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1122 if (name_oop == NULL) {
1123 return NULL;
1124 }
1125 const char* name = java_lang_String::as_utf8_string(name_oop,
1126 java_runtime_version,
1127 sizeof(java_runtime_version));
1128 return name;
1129 } else {
1130 return NULL;
1131 }
1132 }
1133
1134 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION
1135 static const char* get_java_runtime_vendor_version(TRAPS) {
1136 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1137 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1138 fieldDescriptor fd;
1139 bool found = k != NULL &&
1140 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(),
1141 vmSymbols::string_signature(), &fd);
1142 if (found) {
1143 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1144 if (name_oop == NULL) {
1145 return NULL;
1146 }
1147 const char* name = java_lang_String::as_utf8_string(name_oop,
1148 java_runtime_vendor_version,
1149 sizeof(java_runtime_vendor_version));
1150 return name;
1151 } else {
1152 return NULL;
1153 }
1154 }
1155
1156 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG
1157 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) {
1158 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1159 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1160 fieldDescriptor fd;
1161 bool found = k != NULL &&
1162 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(),
1163 vmSymbols::string_signature(), &fd);
1164 if (found) {
1165 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1166 if (name_oop == NULL) {
1167 return NULL;
1168 }
1169 const char* name = java_lang_String::as_utf8_string(name_oop,
1170 java_runtime_vendor_vm_bug_url,
1171 sizeof(java_runtime_vendor_vm_bug_url));
1172 return name;
1173 } else {
1174 return NULL;
1175 }
1176 }
1177
1178 // General purpose hook into Java code, run once when the VM is initialized.
1179 // The Java library method itself may be changed independently from the VM.
1180 static void call_postVMInitHook(TRAPS) {
1181 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1182 if (klass != NULL) {
1183 JavaValue result(T_VOID);
1184 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1185 vmSymbols::void_method_signature(),
1186 CHECK);
1187 }
1188 }
1189
1190 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1191 bool daemon, TRAPS) {
1192 assert(thread_group.not_null(), "thread group should be specified");
1193 assert(threadObj() == NULL, "should only create Java thread object once");
1194
1195 InstanceKlass* ik = SystemDictionary::Thread_klass();
1196 assert(ik->is_initialized(), "must be");
1197 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1198
1199 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1200 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1201 // constructor calls Thread.current(), which must be set here.
1202 java_lang_Thread::set_thread(thread_oop(), this);
1203 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1204 set_threadObj(thread_oop());
1205
1206 JavaValue result(T_VOID);
1207 if (thread_name != NULL) {
1208 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1209 // Thread gets assigned specified name and null target
1210 JavaCalls::call_special(&result,
1211 thread_oop,
1212 ik,
1213 vmSymbols::object_initializer_name(),
1214 vmSymbols::threadgroup_string_void_signature(),
1215 thread_group,
1216 name,
1217 THREAD);
1218 } else {
1219 // Thread gets assigned name "Thread-nnn" and null target
1220 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1221 JavaCalls::call_special(&result,
1222 thread_oop,
1223 ik,
1224 vmSymbols::object_initializer_name(),
1225 vmSymbols::threadgroup_runnable_void_signature(),
1226 thread_group,
1227 Handle(),
1228 THREAD);
1229 }
1230
1231
1232 if (daemon) {
1233 java_lang_Thread::set_daemon(thread_oop());
1234 }
1235
1236 if (HAS_PENDING_EXCEPTION) {
1237 return;
1238 }
1239
1240 Klass* group = SystemDictionary::ThreadGroup_klass();
1241 Handle threadObj(THREAD, this->threadObj());
1242
1243 JavaCalls::call_special(&result,
1244 thread_group,
1245 group,
1246 vmSymbols::add_method_name(),
1247 vmSymbols::thread_void_signature(),
1248 threadObj, // Arg 1
1249 THREAD);
1250 }
1251
1252 // List of all NonJavaThreads and safe iteration over that list.
1253
1254 class NonJavaThread::List {
1255 public:
1256 NonJavaThread* volatile _head;
1257 SingleWriterSynchronizer _protect;
1258
1259 List() : _head(NULL), _protect() {}
1260 };
1261
1262 NonJavaThread::List NonJavaThread::_the_list;
1263
1264 NonJavaThread::Iterator::Iterator() :
1265 _protect_enter(_the_list._protect.enter()),
1266 _current(Atomic::load_acquire(&_the_list._head))
1267 {}
1268
1269 NonJavaThread::Iterator::~Iterator() {
1270 _the_list._protect.exit(_protect_enter);
1271 }
1272
1273 void NonJavaThread::Iterator::step() {
1274 assert(!end(), "precondition");
1275 _current = Atomic::load_acquire(&_current->_next);
1276 }
1277
1278 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1279 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1280 }
1281
1282 NonJavaThread::~NonJavaThread() { }
1283
1284 void NonJavaThread::add_to_the_list() {
1285 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1286 // Initialize BarrierSet-related data before adding to list.
1287 BarrierSet::barrier_set()->on_thread_attach(this);
1288 Atomic::release_store(&_next, _the_list._head);
1289 Atomic::release_store(&_the_list._head, this);
1290 }
1291
1292 void NonJavaThread::remove_from_the_list() {
1293 {
1294 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1295 // Cleanup BarrierSet-related data before removing from list.
1296 BarrierSet::barrier_set()->on_thread_detach(this);
1297 NonJavaThread* volatile* p = &_the_list._head;
1298 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1299 if (t == this) {
1300 *p = _next;
1301 break;
1302 }
1303 }
1304 }
1305 // Wait for any in-progress iterators. Concurrent synchronize is not
1306 // allowed, so do it while holding a dedicated lock. Outside and distinct
1307 // from NJTList_lock in case an iteration attempts to lock it.
1308 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1309 _the_list._protect.synchronize();
1310 _next = NULL; // Safe to drop the link now.
1311 }
1312
1313 void NonJavaThread::pre_run() {
1314 add_to_the_list();
1315
1316 // This is slightly odd in that NamedThread is a subclass, but
1317 // in fact name() is defined in Thread
1318 assert(this->name() != NULL, "thread name was not set before it was started");
1319 this->set_native_thread_name(this->name());
1320 }
1321
1322 void NonJavaThread::post_run() {
1323 JFR_ONLY(Jfr::on_thread_exit(this);)
1324 remove_from_the_list();
1325 // Ensure thread-local-storage is cleared before termination.
1326 Thread::clear_thread_current();
1327 }
1328
1329 // NamedThread -- non-JavaThread subclasses with multiple
1330 // uniquely named instances should derive from this.
1331 NamedThread::NamedThread() :
1332 NonJavaThread(),
1333 _name(NULL),
1334 _processed_thread(NULL),
1335 _gc_id(GCId::undefined())
1336 {}
1337
1338 NamedThread::~NamedThread() {
1339 FREE_C_HEAP_ARRAY(char, _name);
1340 }
1341
1342 void NamedThread::set_name(const char* format, ...) {
1343 guarantee(_name == NULL, "Only get to set name once.");
1344 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1345 va_list ap;
1346 va_start(ap, format);
1347 jio_vsnprintf(_name, max_name_len, format, ap);
1348 va_end(ap);
1349 }
1350
1351 void NamedThread::print_on(outputStream* st) const {
1352 st->print("\"%s\" ", name());
1353 Thread::print_on(st);
1354 st->cr();
1355 }
1356
1357
1358 // ======= WatcherThread ========
1359
1360 // The watcher thread exists to simulate timer interrupts. It should
1361 // be replaced by an abstraction over whatever native support for
1362 // timer interrupts exists on the platform.
1363
1364 WatcherThread* WatcherThread::_watcher_thread = NULL;
1365 bool WatcherThread::_startable = false;
1366 volatile bool WatcherThread::_should_terminate = false;
1367
1368 WatcherThread::WatcherThread() : NonJavaThread() {
1369 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1370 if (os::create_thread(this, os::watcher_thread)) {
1371 _watcher_thread = this;
1372
1373 // Set the watcher thread to the highest OS priority which should not be
1374 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1375 // is created. The only normal thread using this priority is the reference
1376 // handler thread, which runs for very short intervals only.
1377 // If the VMThread's priority is not lower than the WatcherThread profiling
1378 // will be inaccurate.
1379 os::set_priority(this, MaxPriority);
1380 if (!DisableStartThread) {
1381 os::start_thread(this);
1382 }
1383 }
1384 }
1385
1386 int WatcherThread::sleep() const {
1387 // The WatcherThread does not participate in the safepoint protocol
1388 // for the PeriodicTask_lock because it is not a JavaThread.
1389 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1390
1391 if (_should_terminate) {
1392 // check for termination before we do any housekeeping or wait
1393 return 0; // we did not sleep.
1394 }
1395
1396 // remaining will be zero if there are no tasks,
1397 // causing the WatcherThread to sleep until a task is
1398 // enrolled
1399 int remaining = PeriodicTask::time_to_wait();
1400 int time_slept = 0;
1401
1402 // we expect this to timeout - we only ever get unparked when
1403 // we should terminate or when a new task has been enrolled
1404 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1405
1406 jlong time_before_loop = os::javaTimeNanos();
1407
1408 while (true) {
1409 bool timedout = ml.wait(remaining);
1410 jlong now = os::javaTimeNanos();
1411
1412 if (remaining == 0) {
1413 // if we didn't have any tasks we could have waited for a long time
1414 // consider the time_slept zero and reset time_before_loop
1415 time_slept = 0;
1416 time_before_loop = now;
1417 } else {
1418 // need to recalculate since we might have new tasks in _tasks
1419 time_slept = (int) ((now - time_before_loop) / 1000000);
1420 }
1421
1422 // Change to task list or spurious wakeup of some kind
1423 if (timedout || _should_terminate) {
1424 break;
1425 }
1426
1427 remaining = PeriodicTask::time_to_wait();
1428 if (remaining == 0) {
1429 // Last task was just disenrolled so loop around and wait until
1430 // another task gets enrolled
1431 continue;
1432 }
1433
1434 remaining -= time_slept;
1435 if (remaining <= 0) {
1436 break;
1437 }
1438 }
1439
1440 return time_slept;
1441 }
1442
1443 void WatcherThread::run() {
1444 assert(this == watcher_thread(), "just checking");
1445
1446 this->set_active_handles(JNIHandleBlock::allocate_block());
1447 while (true) {
1448 assert(watcher_thread() == Thread::current(), "thread consistency check");
1449 assert(watcher_thread() == this, "thread consistency check");
1450
1451 // Calculate how long it'll be until the next PeriodicTask work
1452 // should be done, and sleep that amount of time.
1453 int time_waited = sleep();
1454
1455 if (VMError::is_error_reported()) {
1456 // A fatal error has happened, the error handler(VMError::report_and_die)
1457 // should abort JVM after creating an error log file. However in some
1458 // rare cases, the error handler itself might deadlock. Here periodically
1459 // check for error reporting timeouts, and if it happens, just proceed to
1460 // abort the VM.
1461
1462 // This code is in WatcherThread because WatcherThread wakes up
1463 // periodically so the fatal error handler doesn't need to do anything;
1464 // also because the WatcherThread is less likely to crash than other
1465 // threads.
1466
1467 for (;;) {
1468 // Note: we use naked sleep in this loop because we want to avoid using
1469 // any kind of VM infrastructure which may be broken at this point.
1470 if (VMError::check_timeout()) {
1471 // We hit error reporting timeout. Error reporting was interrupted and
1472 // will be wrapping things up now (closing files etc). Give it some more
1473 // time, then quit the VM.
1474 os::naked_short_sleep(200);
1475 // Print a message to stderr.
1476 fdStream err(defaultStream::output_fd());
1477 err.print_raw_cr("# [ timer expired, abort... ]");
1478 // skip atexit/vm_exit/vm_abort hooks
1479 os::die();
1480 }
1481
1482 // Wait a second, then recheck for timeout.
1483 os::naked_short_sleep(999);
1484 }
1485 }
1486
1487 if (_should_terminate) {
1488 // check for termination before posting the next tick
1489 break;
1490 }
1491
1492 PeriodicTask::real_time_tick(time_waited);
1493 }
1494
1495 // Signal that it is terminated
1496 {
1497 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1498 _watcher_thread = NULL;
1499 Terminator_lock->notify_all();
1500 }
1501 }
1502
1503 void WatcherThread::start() {
1504 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1505
1506 if (watcher_thread() == NULL && _startable) {
1507 _should_terminate = false;
1508 // Create the single instance of WatcherThread
1509 new WatcherThread();
1510 }
1511 }
1512
1513 void WatcherThread::make_startable() {
1514 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1515 _startable = true;
1516 }
1517
1518 void WatcherThread::stop() {
1519 {
1520 // Follow normal safepoint aware lock enter protocol since the
1521 // WatcherThread is stopped by another JavaThread.
1522 MutexLocker ml(PeriodicTask_lock);
1523 _should_terminate = true;
1524
1525 WatcherThread* watcher = watcher_thread();
1526 if (watcher != NULL) {
1527 // unpark the WatcherThread so it can see that it should terminate
1528 watcher->unpark();
1529 }
1530 }
1531
1532 MonitorLocker mu(Terminator_lock);
1533
1534 while (watcher_thread() != NULL) {
1535 // This wait should make safepoint checks, wait without a timeout,
1536 // and wait as a suspend-equivalent condition.
1537 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1538 }
1539 }
1540
1541 void WatcherThread::unpark() {
1542 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1543 PeriodicTask_lock->notify();
1544 }
1545
1546 void WatcherThread::print_on(outputStream* st) const {
1547 st->print("\"%s\" ", name());
1548 Thread::print_on(st);
1549 st->cr();
1550 }
1551
1552 // ======= JavaThread ========
1553
1554 #if INCLUDE_JVMCI
1555
1556 jlong* JavaThread::_jvmci_old_thread_counters;
1557
1558 bool jvmci_counters_include(JavaThread* thread) {
1559 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1560 }
1561
1562 void JavaThread::collect_counters(jlong* array, int length) {
1563 assert(length == JVMCICounterSize, "wrong value");
1564 for (int i = 0; i < length; i++) {
1565 array[i] = _jvmci_old_thread_counters[i];
1566 }
1567 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1568 if (jvmci_counters_include(tp)) {
1569 for (int i = 0; i < length; i++) {
1570 array[i] += tp->_jvmci_counters[i];
1571 }
1572 }
1573 }
1574 }
1575
1576 // Attempt to enlarge the array for per thread counters.
1577 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1578 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1579 if (old_counters == NULL) {
1580 old_counters = new_counters;
1581 memset(old_counters, 0, sizeof(jlong) * new_size);
1582 } else {
1583 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1584 new_counters[i] = old_counters[i];
1585 }
1586 if (new_size > current_size) {
1587 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1588 }
1589 FREE_C_HEAP_ARRAY(jlong, old_counters);
1590 }
1591 return new_counters;
1592 }
1593
1594 // Attempt to enlarge the array for per thread counters.
1595 void JavaThread::resize_counters(int current_size, int new_size) {
1596 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1597 }
1598
1599 class VM_JVMCIResizeCounters : public VM_Operation {
1600 private:
1601 int _new_size;
1602
1603 public:
1604 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { }
1605 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1606 bool allow_nested_vm_operations() const { return true; }
1607 void doit() {
1608 // Resize the old thread counters array
1609 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1610 JavaThread::_jvmci_old_thread_counters = new_counters;
1611
1612 // Now resize each threads array
1613 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1614 tp->resize_counters(JVMCICounterSize, _new_size);
1615 }
1616 JVMCICounterSize = _new_size;
1617 }
1618 };
1619
1620 void JavaThread::resize_all_jvmci_counters(int new_size) {
1621 VM_JVMCIResizeCounters op(new_size);
1622 VMThread::execute(&op);
1623 }
1624
1625 #endif // INCLUDE_JVMCI
1626
1627 // A JavaThread is a normal Java thread
1628
1629 void JavaThread::initialize() {
1630 // Initialize fields
1631
1632 set_saved_exception_pc(NULL);
1633 set_threadObj(NULL);
1634 _anchor.clear();
1635 set_entry_point(NULL);
1636 set_jni_functions(jni_functions());
1637 set_callee_target(NULL);
1638 set_vm_result(NULL);
1639 set_vm_result_2(NULL);
1640 set_vframe_array_head(NULL);
1641 set_vframe_array_last(NULL);
1642 set_deferred_updates(NULL);
1643 set_deopt_mark(NULL);
1644 set_deopt_compiled_method(NULL);
1645 set_monitor_chunks(NULL);
1646 _on_thread_list = false;
1647 _thread_state = _thread_new;
1648 _terminated = _not_terminated;
1649 _array_for_gc = NULL;
1650 _suspend_equivalent = false;
1651 _in_deopt_handler = 0;
1652 _doing_unsafe_access = false;
1653 _stack_guard_state = stack_guard_unused;
1654 #if INCLUDE_JVMCI
1655 _pending_monitorenter = false;
1656 _pending_deoptimization = -1;
1657 _pending_failed_speculation = 0;
1658 _pending_transfer_to_interpreter = false;
1659 _in_retryable_allocation = false;
1660 _jvmci._alternate_call_target = NULL;
1661 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1662 _jvmci_counters = NULL;
1663 if (JVMCICounterSize > 0) {
1664 resize_counters(0, (int) JVMCICounterSize);
1665 }
1666 #endif // INCLUDE_JVMCI
1667 _reserved_stack_activation = NULL; // stack base not known yet
1668 set_exception_oop(oop());
1669 _exception_pc = 0;
1670 _exception_handler_pc = 0;
1671 _is_method_handle_return = 0;
1672 _jvmti_thread_state= NULL;
1673 _should_post_on_exceptions_flag = JNI_FALSE;
1674 _interp_only_mode = 0;
1675 _special_runtime_exit_condition = _no_async_condition;
1676 _pending_async_exception = NULL;
1677 _thread_stat = NULL;
1678 _thread_stat = new ThreadStatistics();
1679 _jni_active_critical = 0;
1680 _pending_jni_exception_check_fn = NULL;
1681 _do_not_unlock_if_synchronized = false;
1682 _cached_monitor_info = NULL;
1683 _parker = Parker::Allocate(this);
1684 _SleepEvent = ParkEvent::Allocate(this);
1685 // Setup safepoint state info for this thread
1686 ThreadSafepointState::create(this);
1687 _handshake.set_handshakee(this);
1688
1689 debug_only(_java_call_counter = 0);
1690
1691 // JVMTI PopFrame support
1692 _popframe_condition = popframe_inactive;
1693 _popframe_preserved_args = NULL;
1694 _popframe_preserved_args_size = 0;
1695 _frames_to_pop_failed_realloc = 0;
1696
1697 SafepointMechanism::initialize_header(this);
1698
1699 _class_to_be_initialized = NULL;
1700
1701 pd_initialize();
1702 }
1703
1704 JavaThread::JavaThread(bool is_attaching_via_jni) :
1705 Thread() {
1706 initialize();
1707 if (is_attaching_via_jni) {
1708 _jni_attach_state = _attaching_via_jni;
1709 } else {
1710 _jni_attach_state = _not_attaching_via_jni;
1711 }
1712 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1713 }
1714
1715
1716 // interrupt support
1717
1718 void JavaThread::interrupt() {
1719 debug_only(check_for_dangling_thread_pointer(this);)
1720
1721 // For Windows _interrupt_event
1722 osthread()->set_interrupted(true);
1723
1724 // For Thread.sleep
1725 _SleepEvent->unpark();
1726
1727 // For JSR166 LockSupport.park
1728 parker()->unpark();
1729
1730 // For ObjectMonitor and JvmtiRawMonitor
1731 _ParkEvent->unpark();
1732 }
1733
1734
1735 bool JavaThread::is_interrupted(bool clear_interrupted) {
1736 debug_only(check_for_dangling_thread_pointer(this);)
1737
1738 if (threadObj() == NULL) {
1739 // If there is no j.l.Thread then it is impossible to have
1740 // been interrupted. We can find NULL during VM initialization
1741 // or when a JNI thread is still in the process of attaching.
1742 // In such cases this must be the current thread.
1743 assert(this == Thread::current(), "invariant");
1744 return false;
1745 }
1746
1747 bool interrupted = java_lang_Thread::interrupted(threadObj());
1748
1749 // NOTE that since there is no "lock" around the interrupt and
1750 // is_interrupted operations, there is the possibility that the
1751 // interrupted flag will be "false" but that the
1752 // low-level events will be in the signaled state. This is
1753 // intentional. The effect of this is that Object.wait() and
1754 // LockSupport.park() will appear to have a spurious wakeup, which
1755 // is allowed and not harmful, and the possibility is so rare that
1756 // it is not worth the added complexity to add yet another lock.
1757 // For the sleep event an explicit reset is performed on entry
1758 // to JavaThread::sleep, so there is no early return. It has also been
1759 // recommended not to put the interrupted flag into the "event"
1760 // structure because it hides the issue.
1761 // Also, because there is no lock, we must only clear the interrupt
1762 // state if we are going to report that we were interrupted; otherwise
1763 // an interrupt that happens just after we read the field would be lost.
1764 if (interrupted && clear_interrupted) {
1765 assert(this == Thread::current(), "only the current thread can clear");
1766 java_lang_Thread::set_interrupted(threadObj(), false);
1767 osthread()->set_interrupted(false);
1768 }
1769
1770 return interrupted;
1771 }
1772
1773 bool JavaThread::reguard_stack(address cur_sp) {
1774 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1775 && _stack_guard_state != stack_guard_reserved_disabled) {
1776 return true; // Stack already guarded or guard pages not needed.
1777 }
1778
1779 if (register_stack_overflow()) {
1780 // For those architectures which have separate register and
1781 // memory stacks, we must check the register stack to see if
1782 // it has overflowed.
1783 return false;
1784 }
1785
1786 // Java code never executes within the yellow zone: the latter is only
1787 // there to provoke an exception during stack banging. If java code
1788 // is executing there, either StackShadowPages should be larger, or
1789 // some exception code in c1, c2 or the interpreter isn't unwinding
1790 // when it should.
1791 guarantee(cur_sp > stack_reserved_zone_base(),
1792 "not enough space to reguard - increase StackShadowPages");
1793 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1794 enable_stack_yellow_reserved_zone();
1795 if (reserved_stack_activation() != stack_base()) {
1796 set_reserved_stack_activation(stack_base());
1797 }
1798 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1799 set_reserved_stack_activation(stack_base());
1800 enable_stack_reserved_zone();
1801 }
1802 return true;
1803 }
1804
1805 bool JavaThread::reguard_stack(void) {
1806 return reguard_stack(os::current_stack_pointer());
1807 }
1808
1809 void JavaThread::block_if_vm_exited() {
1810 if (_terminated == _vm_exited) {
1811 // _vm_exited is set at safepoint, and Threads_lock is never released
1812 // we will block here forever.
1813 // Here we can be doing a jump from a safe state to an unsafe state without
1814 // proper transition, but it happens after the final safepoint has begun.
1815 set_thread_state(_thread_in_vm);
1816 Threads_lock->lock();
1817 ShouldNotReachHere();
1818 }
1819 }
1820
1821
1822 // Remove this ifdef when C1 is ported to the compiler interface.
1823 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1824 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1825
1826 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1827 Thread() {
1828 initialize();
1829 _jni_attach_state = _not_attaching_via_jni;
1830 set_entry_point(entry_point);
1831 // Create the native thread itself.
1832 // %note runtime_23
1833 os::ThreadType thr_type = os::java_thread;
1834 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1835 os::java_thread;
1836 os::create_thread(this, thr_type, stack_sz);
1837 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1838 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1839 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1840 // the exception consists of creating the exception object & initializing it, initialization
1841 // will leave the VM via a JavaCall and then all locks must be unlocked).
1842 //
1843 // The thread is still suspended when we reach here. Thread must be explicit started
1844 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1845 // by calling Threads:add. The reason why this is not done here, is because the thread
1846 // object must be fully initialized (take a look at JVM_Start)
1847 }
1848
1849 JavaThread::~JavaThread() {
1850
1851 // JSR166 -- return the parker to the free list
1852 Parker::Release(_parker);
1853 _parker = NULL;
1854
1855 // Return the sleep event to the free list
1856 ParkEvent::Release(_SleepEvent);
1857 _SleepEvent = NULL;
1858
1859 // Free any remaining previous UnrollBlock
1860 vframeArray* old_array = vframe_array_last();
1861
1862 if (old_array != NULL) {
1863 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1864 old_array->set_unroll_block(NULL);
1865 delete old_info;
1866 delete old_array;
1867 }
1868
1869 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = JvmtiDeferredUpdates::deferred_locals(this);
1870 if (deferred != NULL) {
1871 // This can only happen if thread is destroyed before deoptimization occurs.
1872 assert(deferred->length() != 0, "empty array!");
1873 do {
1874 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1875 deferred->remove_at(0);
1876 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1877 delete dlv;
1878 } while (deferred->length() != 0);
1879 delete deferred_updates();
1880 }
1881
1882 // All Java related clean up happens in exit
1883 ThreadSafepointState::destroy(this);
1884 if (_thread_stat != NULL) delete _thread_stat;
1885
1886 #if INCLUDE_JVMCI
1887 if (JVMCICounterSize > 0) {
1888 if (jvmci_counters_include(this)) {
1889 for (int i = 0; i < JVMCICounterSize; i++) {
1890 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1891 }
1892 }
1893 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1894 }
1895 #endif // INCLUDE_JVMCI
1896 }
1897
1898
1899 // First JavaThread specific code executed by a new Java thread.
1900 void JavaThread::pre_run() {
1901 // empty - see comments in run()
1902 }
1903
1904 // The main routine called by a new Java thread. This isn't overridden
1905 // by subclasses, instead different subclasses define a different "entry_point"
1906 // which defines the actual logic for that kind of thread.
1907 void JavaThread::run() {
1908 // initialize thread-local alloc buffer related fields
1909 this->initialize_tlab();
1910
1911 // Used to test validity of stack trace backs.
1912 // This can't be moved into pre_run() else we invalidate
1913 // the requirement that thread_main_inner is lower on
1914 // the stack. Consequently all the initialization logic
1915 // stays here in run() rather than pre_run().
1916 this->record_base_of_stack_pointer();
1917
1918 this->create_stack_guard_pages();
1919
1920 this->cache_global_variables();
1921
1922 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1923 // in the VM. Change thread state from _thread_new to _thread_in_vm
1924 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1925 // Before a thread is on the threads list it is always safe, so after leaving the
1926 // _thread_new we should emit a instruction barrier. The distance to modified code
1927 // from here is probably far enough, but this is consistent and safe.
1928 OrderAccess::cross_modify_fence();
1929
1930 assert(JavaThread::current() == this, "sanity check");
1931 assert(!Thread::current()->owns_locks(), "sanity check");
1932
1933 DTRACE_THREAD_PROBE(start, this);
1934
1935 // This operation might block. We call that after all safepoint checks for a new thread has
1936 // been completed.
1937 this->set_active_handles(JNIHandleBlock::allocate_block());
1938
1939 if (JvmtiExport::should_post_thread_life()) {
1940 JvmtiExport::post_thread_start(this);
1941
1942 }
1943
1944 // We call another function to do the rest so we are sure that the stack addresses used
1945 // from there will be lower than the stack base just computed.
1946 thread_main_inner();
1947 }
1948
1949 void JavaThread::thread_main_inner() {
1950 assert(JavaThread::current() == this, "sanity check");
1951 assert(this->threadObj() != NULL, "just checking");
1952
1953 // Execute thread entry point unless this thread has a pending exception
1954 // or has been stopped before starting.
1955 // Note: Due to JVM_StopThread we can have pending exceptions already!
1956 if (!this->has_pending_exception() &&
1957 !java_lang_Thread::is_stillborn(this->threadObj())) {
1958 {
1959 ResourceMark rm(this);
1960 this->set_native_thread_name(this->get_thread_name());
1961 }
1962 HandleMark hm(this);
1963 this->entry_point()(this, this);
1964 }
1965
1966 DTRACE_THREAD_PROBE(stop, this);
1967
1968 // Cleanup is handled in post_run()
1969 }
1970
1971 // Shared teardown for all JavaThreads
1972 void JavaThread::post_run() {
1973 this->exit(false);
1974 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1975 // for any shared tear-down.
1976 this->smr_delete();
1977 }
1978
1979 static void ensure_join(JavaThread* thread) {
1980 // We do not need to grab the Threads_lock, since we are operating on ourself.
1981 Handle threadObj(thread, thread->threadObj());
1982 assert(threadObj.not_null(), "java thread object must exist");
1983 ObjectLocker lock(threadObj, thread);
1984 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1985 thread->clear_pending_exception();
1986 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1987 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1988 // Clear the native thread instance - this makes isAlive return false and allows the join()
1989 // to complete once we've done the notify_all below
1990 java_lang_Thread::set_thread(threadObj(), NULL);
1991 lock.notify_all(thread);
1992 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1993 thread->clear_pending_exception();
1994 }
1995
1996 static bool is_daemon(oop threadObj) {
1997 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1998 }
1999
2000 // For any new cleanup additions, please check to see if they need to be applied to
2001 // cleanup_failed_attach_current_thread as well.
2002 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
2003 assert(this == JavaThread::current(), "thread consistency check");
2004
2005 elapsedTimer _timer_exit_phase1;
2006 elapsedTimer _timer_exit_phase2;
2007 elapsedTimer _timer_exit_phase3;
2008 elapsedTimer _timer_exit_phase4;
2009
2010 if (log_is_enabled(Debug, os, thread, timer)) {
2011 _timer_exit_phase1.start();
2012 }
2013
2014 HandleMark hm(this);
2015 Handle uncaught_exception(this, this->pending_exception());
2016 this->clear_pending_exception();
2017 Handle threadObj(this, this->threadObj());
2018 assert(threadObj.not_null(), "Java thread object should be created");
2019
2020 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2021 {
2022 EXCEPTION_MARK;
2023
2024 CLEAR_PENDING_EXCEPTION;
2025 }
2026 if (!destroy_vm) {
2027 if (uncaught_exception.not_null()) {
2028 EXCEPTION_MARK;
2029 // Call method Thread.dispatchUncaughtException().
2030 Klass* thread_klass = SystemDictionary::Thread_klass();
2031 JavaValue result(T_VOID);
2032 JavaCalls::call_virtual(&result,
2033 threadObj, thread_klass,
2034 vmSymbols::dispatchUncaughtException_name(),
2035 vmSymbols::throwable_void_signature(),
2036 uncaught_exception,
2037 THREAD);
2038 if (HAS_PENDING_EXCEPTION) {
2039 ResourceMark rm(this);
2040 jio_fprintf(defaultStream::error_stream(),
2041 "\nException: %s thrown from the UncaughtExceptionHandler"
2042 " in thread \"%s\"\n",
2043 pending_exception()->klass()->external_name(),
2044 get_thread_name());
2045 CLEAR_PENDING_EXCEPTION;
2046 }
2047 }
2048
2049 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2050 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2051 // is deprecated anyhow.
2052 if (!is_Compiler_thread()) {
2053 int count = 3;
2054 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2055 EXCEPTION_MARK;
2056 JavaValue result(T_VOID);
2057 Klass* thread_klass = SystemDictionary::Thread_klass();
2058 JavaCalls::call_virtual(&result,
2059 threadObj, thread_klass,
2060 vmSymbols::exit_method_name(),
2061 vmSymbols::void_method_signature(),
2062 THREAD);
2063 CLEAR_PENDING_EXCEPTION;
2064 }
2065 }
2066 // notify JVMTI
2067 if (JvmtiExport::should_post_thread_life()) {
2068 JvmtiExport::post_thread_end(this);
2069 }
2070
2071 // We have notified the agents that we are exiting, before we go on,
2072 // we must check for a pending external suspend request and honor it
2073 // in order to not surprise the thread that made the suspend request.
2074 while (true) {
2075 {
2076 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2077 if (!is_external_suspend()) {
2078 set_terminated(_thread_exiting);
2079 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2080 break;
2081 }
2082 // Implied else:
2083 // Things get a little tricky here. We have a pending external
2084 // suspend request, but we are holding the SR_lock so we
2085 // can't just self-suspend. So we temporarily drop the lock
2086 // and then self-suspend.
2087 }
2088
2089 ThreadBlockInVM tbivm(this);
2090 java_suspend_self();
2091
2092 // We're done with this suspend request, but we have to loop around
2093 // and check again. Eventually we will get SR_lock without a pending
2094 // external suspend request and will be able to mark ourselves as
2095 // exiting.
2096 }
2097 // no more external suspends are allowed at this point
2098 } else {
2099 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2100 // before_exit() has already posted JVMTI THREAD_END events
2101 }
2102
2103 if (log_is_enabled(Debug, os, thread, timer)) {
2104 _timer_exit_phase1.stop();
2105 _timer_exit_phase2.start();
2106 }
2107
2108 // Capture daemon status before the thread is marked as terminated.
2109 bool daemon = is_daemon(threadObj());
2110
2111 // Notify waiters on thread object. This has to be done after exit() is called
2112 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2113 // group should have the destroyed bit set before waiters are notified).
2114 ensure_join(this);
2115 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2116
2117 if (log_is_enabled(Debug, os, thread, timer)) {
2118 _timer_exit_phase2.stop();
2119 _timer_exit_phase3.start();
2120 }
2121 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2122 // held by this thread must be released. The spec does not distinguish
2123 // between JNI-acquired and regular Java monitors. We can only see
2124 // regular Java monitors here if monitor enter-exit matching is broken.
2125 //
2126 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2127 // ObjectSynchronizer::release_monitors_owned_by_thread().
2128 if (exit_type == jni_detach) {
2129 // Sanity check even though JNI DetachCurrentThread() would have
2130 // returned JNI_ERR if there was a Java frame. JavaThread exit
2131 // should be done executing Java code by the time we get here.
2132 assert(!this->has_last_Java_frame(),
2133 "should not have a Java frame when detaching or exiting");
2134 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2135 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2136 }
2137
2138 // These things needs to be done while we are still a Java Thread. Make sure that thread
2139 // is in a consistent state, in case GC happens
2140 JFR_ONLY(Jfr::on_thread_exit(this);)
2141
2142 if (active_handles() != NULL) {
2143 JNIHandleBlock* block = active_handles();
2144 set_active_handles(NULL);
2145 JNIHandleBlock::release_block(block);
2146 }
2147
2148 if (free_handle_block() != NULL) {
2149 JNIHandleBlock* block = free_handle_block();
2150 set_free_handle_block(NULL);
2151 JNIHandleBlock::release_block(block);
2152 }
2153
2154 // These have to be removed while this is still a valid thread.
2155 remove_stack_guard_pages();
2156
2157 if (UseTLAB) {
2158 tlab().retire();
2159 }
2160
2161 if (JvmtiEnv::environments_might_exist()) {
2162 JvmtiExport::cleanup_thread(this);
2163 }
2164
2165 // We need to cache the thread name for logging purposes below as once
2166 // we have called on_thread_detach this thread must not access any oops.
2167 char* thread_name = NULL;
2168 if (log_is_enabled(Debug, os, thread, timer)) {
2169 ResourceMark rm(this);
2170 thread_name = os::strdup(get_thread_name());
2171 }
2172
2173 // We must flush any deferred card marks and other various GC barrier
2174 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2175 // before removing a thread from the list of active threads.
2176 BarrierSet::barrier_set()->on_thread_detach(this);
2177
2178 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2179 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2180 os::current_thread_id());
2181
2182 if (log_is_enabled(Debug, os, thread, timer)) {
2183 _timer_exit_phase3.stop();
2184 _timer_exit_phase4.start();
2185 }
2186 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2187 Threads::remove(this, daemon);
2188
2189 if (log_is_enabled(Debug, os, thread, timer)) {
2190 _timer_exit_phase4.stop();
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 thread_name,
2197 _timer_exit_phase1.milliseconds(),
2198 _timer_exit_phase2.milliseconds(),
2199 _timer_exit_phase3.milliseconds(),
2200 _timer_exit_phase4.milliseconds());
2201 os::free(thread_name);
2202 }
2203 }
2204
2205 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2206 if (active_handles() != NULL) {
2207 JNIHandleBlock* block = active_handles();
2208 set_active_handles(NULL);
2209 JNIHandleBlock::release_block(block);
2210 }
2211
2212 if (free_handle_block() != NULL) {
2213 JNIHandleBlock* block = free_handle_block();
2214 set_free_handle_block(NULL);
2215 JNIHandleBlock::release_block(block);
2216 }
2217
2218 // These have to be removed while this is still a valid thread.
2219 remove_stack_guard_pages();
2220
2221 if (UseTLAB) {
2222 tlab().retire();
2223 }
2224
2225 BarrierSet::barrier_set()->on_thread_detach(this);
2226
2227 Threads::remove(this, is_daemon);
2228 this->smr_delete();
2229 }
2230
2231 JavaThread* JavaThread::active() {
2232 Thread* thread = Thread::current();
2233 if (thread->is_Java_thread()) {
2234 return (JavaThread*) thread;
2235 } else {
2236 assert(thread->is_VM_thread(), "this must be a vm thread");
2237 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2238 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2239 assert(ret->is_Java_thread(), "must be a Java thread");
2240 return ret;
2241 }
2242 }
2243
2244 bool JavaThread::is_lock_owned(address adr) const {
2245 if (Thread::is_lock_owned(adr)) return true;
2246
2247 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2248 if (chunk->contains(adr)) return true;
2249 }
2250
2251 return false;
2252 }
2253
2254 oop JavaThread::exception_oop() const {
2255 return Atomic::load(&_exception_oop);
2256 }
2257
2258 void JavaThread::set_exception_oop(oop o) {
2259 Atomic::store(&_exception_oop, o);
2260 }
2261
2262 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2263 chunk->set_next(monitor_chunks());
2264 set_monitor_chunks(chunk);
2265 }
2266
2267 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2268 guarantee(monitor_chunks() != NULL, "must be non empty");
2269 if (monitor_chunks() == chunk) {
2270 set_monitor_chunks(chunk->next());
2271 } else {
2272 MonitorChunk* prev = monitor_chunks();
2273 while (prev->next() != chunk) prev = prev->next();
2274 prev->set_next(chunk->next());
2275 }
2276 }
2277
2278 // JVM support.
2279
2280 // Note: this function shouldn't block if it's called in
2281 // _thread_in_native_trans state (such as from
2282 // check_special_condition_for_native_trans()).
2283 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2284
2285 if (has_last_Java_frame() && has_async_condition()) {
2286 // If we are at a polling page safepoint (not a poll return)
2287 // then we must defer async exception because live registers
2288 // will be clobbered by the exception path. Poll return is
2289 // ok because the call we a returning from already collides
2290 // with exception handling registers and so there is no issue.
2291 // (The exception handling path kills call result registers but
2292 // this is ok since the exception kills the result anyway).
2293
2294 if (is_at_poll_safepoint()) {
2295 // if the code we are returning to has deoptimized we must defer
2296 // the exception otherwise live registers get clobbered on the
2297 // exception path before deoptimization is able to retrieve them.
2298 //
2299 RegisterMap map(this, false);
2300 frame caller_fr = last_frame().sender(&map);
2301 assert(caller_fr.is_compiled_frame(), "what?");
2302 if (caller_fr.is_deoptimized_frame()) {
2303 log_info(exceptions)("deferred async exception at compiled safepoint");
2304 return;
2305 }
2306 }
2307 }
2308
2309 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2310 if (condition == _no_async_condition) {
2311 // Conditions have changed since has_special_runtime_exit_condition()
2312 // was called:
2313 // - if we were here only because of an external suspend request,
2314 // then that was taken care of above (or cancelled) so we are done
2315 // - if we were here because of another async request, then it has
2316 // been cleared between the has_special_runtime_exit_condition()
2317 // and now so again we are done
2318 return;
2319 }
2320
2321 // Check for pending async. exception
2322 if (_pending_async_exception != NULL) {
2323 // Only overwrite an already pending exception, if it is not a threadDeath.
2324 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2325
2326 // We cannot call Exceptions::_throw(...) here because we cannot block
2327 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2328
2329 LogTarget(Info, exceptions) lt;
2330 if (lt.is_enabled()) {
2331 ResourceMark rm;
2332 LogStream ls(lt);
2333 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2334 if (has_last_Java_frame()) {
2335 frame f = last_frame();
2336 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2337 }
2338 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2339 }
2340 _pending_async_exception = NULL;
2341 clear_has_async_exception();
2342 }
2343 }
2344
2345 if (check_unsafe_error &&
2346 condition == _async_unsafe_access_error && !has_pending_exception()) {
2347 condition = _no_async_condition; // done
2348 switch (thread_state()) {
2349 case _thread_in_vm: {
2350 JavaThread* THREAD = this;
2351 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2352 }
2353 case _thread_in_native: {
2354 ThreadInVMfromNative tiv(this);
2355 JavaThread* THREAD = this;
2356 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2357 }
2358 case _thread_in_Java: {
2359 ThreadInVMfromJava tiv(this);
2360 JavaThread* THREAD = this;
2361 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2362 }
2363 default:
2364 ShouldNotReachHere();
2365 }
2366 }
2367
2368 assert(condition == _no_async_condition || has_pending_exception() ||
2369 (!check_unsafe_error && condition == _async_unsafe_access_error),
2370 "must have handled the async condition, if no exception");
2371 }
2372
2373 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2374
2375 // Check for pending external suspend.
2376 if (is_external_suspend_with_lock()) {
2377 frame_anchor()->make_walkable(this);
2378 java_suspend_self_with_safepoint_check();
2379 }
2380
2381 // We might be here for reasons in addition to the self-suspend request
2382 // so check for other async requests.
2383 if (check_asyncs) {
2384 check_and_handle_async_exceptions();
2385 }
2386
2387 if (is_ea_obj_deopt_suspend()) {
2388 frame_anchor()->make_walkable(this);
2389 wait_for_object_deoptimization();
2390 }
2391
2392 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2393 }
2394
2395 void JavaThread::send_thread_stop(oop java_throwable) {
2396 ResourceMark rm;
2397 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread");
2398
2399 // Do not throw asynchronous exceptions against the compiler thread
2400 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2401 if (!can_call_java()) return;
2402
2403 {
2404 // Actually throw the Throwable against the target Thread - however
2405 // only if there is no thread death exception installed already.
2406 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2407 // If the topmost frame is a runtime stub, then we are calling into
2408 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2409 // must deoptimize the caller before continuing, as the compiled exception handler table
2410 // may not be valid
2411 if (has_last_Java_frame()) {
2412 frame f = last_frame();
2413 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2414 RegisterMap reg_map(this, false);
2415 frame compiled_frame = f.sender(®_map);
2416 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2417 Deoptimization::deoptimize(this, compiled_frame);
2418 }
2419 }
2420 }
2421
2422 // Set async. pending exception in thread.
2423 set_pending_async_exception(java_throwable);
2424
2425 if (log_is_enabled(Info, exceptions)) {
2426 ResourceMark rm;
2427 log_info(exceptions)("Pending Async. exception installed of type: %s",
2428 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2429 }
2430 // for AbortVMOnException flag
2431 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2432 }
2433 }
2434
2435
2436 // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
2437 java_lang_Thread::set_interrupted(threadObj(), true);
2438 this->interrupt();
2439 }
2440
2441 // External suspension mechanism.
2442 //
2443 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2444 // to any VM_locks and it is at a transition
2445 // Self-suspension will happen on the transition out of the vm.
2446 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2447 //
2448 // Guarantees on return:
2449 // + Target thread will not execute any new bytecode (that's why we need to
2450 // force a safepoint)
2451 // + Target thread will not enter any new monitors
2452 //
2453 void JavaThread::java_suspend() {
2454 ThreadsListHandle tlh;
2455 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2456 return;
2457 }
2458
2459 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2460 if (!is_external_suspend()) {
2461 // a racing resume has cancelled us; bail out now
2462 return;
2463 }
2464
2465 // suspend is done
2466 uint32_t debug_bits = 0;
2467 // Warning: is_ext_suspend_completed() may temporarily drop the
2468 // SR_lock to allow the thread to reach a stable thread state if
2469 // it is currently in a transient thread state.
2470 if (is_ext_suspend_completed(false /* !called_by_wait */,
2471 SuspendRetryDelay, &debug_bits)) {
2472 return;
2473 }
2474 }
2475
2476 if (Thread::current() == this) {
2477 // Safely self-suspend.
2478 // If we don't do this explicitly it will implicitly happen
2479 // before we transition back to Java, and on some other thread-state
2480 // transition paths, but not as we exit a JVM TI SuspendThread call.
2481 // As SuspendThread(current) must not return (until resumed) we must
2482 // self-suspend here.
2483 ThreadBlockInVM tbivm(this);
2484 java_suspend_self();
2485 } else {
2486 VM_ThreadSuspend vm_suspend;
2487 VMThread::execute(&vm_suspend);
2488 }
2489 }
2490
2491 // Part II of external suspension.
2492 // A JavaThread self suspends when it detects a pending external suspend
2493 // request. This is usually on transitions. It is also done in places
2494 // where continuing to the next transition would surprise the caller,
2495 // e.g., monitor entry.
2496 //
2497 // Returns the number of times that the thread self-suspended.
2498 //
2499 // Note: DO NOT call java_suspend_self() when you just want to block current
2500 // thread. java_suspend_self() is the second stage of cooperative
2501 // suspension for external suspend requests and should only be used
2502 // to complete an external suspend request.
2503 //
2504 int JavaThread::java_suspend_self() {
2505 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2506 int ret = 0;
2507
2508 // we are in the process of exiting so don't suspend
2509 if (is_exiting()) {
2510 clear_external_suspend();
2511 return ret;
2512 }
2513
2514 assert(_anchor.walkable() ||
2515 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2516 "must have walkable stack");
2517
2518 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2519
2520 assert(!this->is_ext_suspended(),
2521 "a thread trying to self-suspend should not already be suspended");
2522
2523 if (this->is_suspend_equivalent()) {
2524 // If we are self-suspending as a result of the lifting of a
2525 // suspend equivalent condition, then the suspend_equivalent
2526 // flag is not cleared until we set the ext_suspended flag so
2527 // that wait_for_ext_suspend_completion() returns consistent
2528 // results.
2529 this->clear_suspend_equivalent();
2530 }
2531
2532 // A racing resume may have cancelled us before we grabbed SR_lock
2533 // above. Or another external suspend request could be waiting for us
2534 // by the time we return from SR_lock()->wait(). The thread
2535 // that requested the suspension may already be trying to walk our
2536 // stack and if we return now, we can change the stack out from under
2537 // it. This would be a "bad thing (TM)" and cause the stack walker
2538 // to crash. We stay self-suspended until there are no more pending
2539 // external suspend requests.
2540 while (is_external_suspend()) {
2541 ret++;
2542 this->set_ext_suspended();
2543
2544 // _ext_suspended flag is cleared by java_resume()
2545 while (is_ext_suspended()) {
2546 ml.wait();
2547 }
2548 }
2549 return ret;
2550 }
2551
2552 // Helper routine to set up the correct thread state before calling java_suspend_self.
2553 // This is called when regular thread-state transition helpers can't be used because
2554 // we can be in various states, in particular _thread_in_native_trans.
2555 // Because this thread is external suspended the safepoint code will count it as at
2556 // a safepoint, regardless of what its actual current thread-state is. But
2557 // is_ext_suspend_completed() may be waiting to see a thread transition from
2558 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2559 // to _thread_blocked. The problem with setting thread state directly is that a
2560 // safepoint could happen just after java_suspend_self() returns after being resumed,
2561 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2562 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2563 // However, not all initial-states are allowed when performing a safepoint check, as we
2564 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2565 // only _thread_in_native is possible when executing this code (based on our two callers).
2566 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2567 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2568 // and so we don't need the explicit safepoint check.
2569
2570 void JavaThread::java_suspend_self_with_safepoint_check() {
2571 assert(this == Thread::current(), "invariant");
2572 JavaThreadState state = thread_state();
2573 set_thread_state(_thread_blocked);
2574 java_suspend_self();
2575 set_thread_state_fence(state);
2576 // Since we are not using a regular thread-state transition helper here,
2577 // we must manually emit the instruction barrier after leaving a safe state.
2578 OrderAccess::cross_modify_fence();
2579 if (state != _thread_in_native) {
2580 SafepointMechanism::block_if_requested(this);
2581 }
2582 }
2583
2584 void JavaThread::wait_for_object_deoptimization() {
2585 assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
2586 assert(this == Thread::current(), "invariant");
2587 JavaThreadState state = thread_state();
2588
2589 do {
2590 set_thread_state(_thread_blocked);
2591 set_suspend_equivalent();
2592 MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
2593 if (is_ea_obj_deopt_suspend()) {
2594 ml.wait();
2595 }
2596 if (handle_special_suspend_equivalent_condition()) {
2597 MutexUnlocker mu(EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
2598 java_suspend_self();
2599 }
2600 set_thread_state_fence(state);
2601 } while (is_ea_obj_deopt_suspend());
2602
2603 // Since we are not using a regular thread-state transition helper here,
2604 // we must manually emit the instruction barrier after leaving a safe state.
2605 OrderAccess::cross_modify_fence();
2606 if (state != _thread_in_native) {
2607 SafepointMechanism::block_if_requested(this);
2608 }
2609 }
2610
2611 #ifdef ASSERT
2612 // Verify the JavaThread has not yet been published in the Threads::list, and
2613 // hence doesn't need protection from concurrent access at this stage.
2614 void JavaThread::verify_not_published() {
2615 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2616 // since an unpublished JavaThread doesn't participate in the
2617 // Thread-SMR protocol for keeping a ThreadsList alive.
2618 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2619 }
2620 #endif
2621
2622 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2623 // progress or when _suspend_flags is non-zero.
2624 // Current thread needs to self-suspend if there is a suspend request and/or
2625 // block if a safepoint is in progress.
2626 // Async exception ISN'T checked.
2627 // Note only the ThreadInVMfromNative transition can call this function
2628 // directly and when thread state is _thread_in_native_trans
2629 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2630 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2631
2632 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2633
2634 if (thread->is_external_suspend()) {
2635 thread->java_suspend_self_with_safepoint_check();
2636 } else {
2637 SafepointMechanism::block_if_requested(thread);
2638 }
2639
2640 if (thread->is_ea_obj_deopt_suspend()) {
2641 thread->wait_for_object_deoptimization();
2642 }
2643
2644 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2645 }
2646
2647 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2648 // progress or when _suspend_flags is non-zero.
2649 // Current thread needs to self-suspend if there is a suspend request and/or
2650 // block if a safepoint is in progress.
2651 // Also check for pending async exception (not including unsafe access error).
2652 // Note only the native==>VM/Java barriers can call this function and when
2653 // thread state is _thread_in_native_trans.
2654 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2655 check_safepoint_and_suspend_for_native_trans(thread);
2656
2657 if (thread->has_async_exception()) {
2658 // We are in _thread_in_native_trans state, don't handle unsafe
2659 // access error since that may block.
2660 thread->check_and_handle_async_exceptions(false);
2661 }
2662 }
2663
2664 // This is a variant of the normal
2665 // check_special_condition_for_native_trans with slightly different
2666 // semantics for use by critical native wrappers. It does all the
2667 // normal checks but also performs the transition back into
2668 // thread_in_Java state. This is required so that critical natives
2669 // can potentially block and perform a GC if they are the last thread
2670 // exiting the GCLocker.
2671 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2672 check_special_condition_for_native_trans(thread);
2673
2674 // Finish the transition
2675 thread->set_thread_state(_thread_in_Java);
2676
2677 if (thread->do_critical_native_unlock()) {
2678 ThreadInVMfromJavaNoAsyncException tiv(thread);
2679 GCLocker::unlock_critical(thread);
2680 thread->clear_critical_native_unlock();
2681 }
2682 }
2683
2684 // We need to guarantee the Threads_lock here, since resumes are not
2685 // allowed during safepoint synchronization
2686 // Can only resume from an external suspension
2687 void JavaThread::java_resume() {
2688 assert_locked_or_safepoint(Threads_lock);
2689
2690 // Sanity check: thread is gone, has started exiting or the thread
2691 // was not externally suspended.
2692 ThreadsListHandle tlh;
2693 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2694 return;
2695 }
2696
2697 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2698
2699 clear_external_suspend();
2700
2701 if (is_ext_suspended()) {
2702 clear_ext_suspended();
2703 SR_lock()->notify_all();
2704 }
2705 }
2706
2707 size_t JavaThread::_stack_red_zone_size = 0;
2708 size_t JavaThread::_stack_yellow_zone_size = 0;
2709 size_t JavaThread::_stack_reserved_zone_size = 0;
2710 size_t JavaThread::_stack_shadow_zone_size = 0;
2711
2712 void JavaThread::create_stack_guard_pages() {
2713 if (!os::uses_stack_guard_pages() ||
2714 _stack_guard_state != stack_guard_unused ||
2715 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2716 log_info(os, thread)("Stack guard page creation for thread "
2717 UINTX_FORMAT " disabled", os::current_thread_id());
2718 return;
2719 }
2720 address low_addr = stack_end();
2721 size_t len = stack_guard_zone_size();
2722
2723 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2724 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2725
2726 int must_commit = os::must_commit_stack_guard_pages();
2727 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2728
2729 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2730 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2731 return;
2732 }
2733
2734 if (os::guard_memory((char *) low_addr, len)) {
2735 _stack_guard_state = stack_guard_enabled;
2736 } else {
2737 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2738 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2739 if (os::uncommit_memory((char *) low_addr, len)) {
2740 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2741 }
2742 return;
2743 }
2744
2745 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2746 PTR_FORMAT "-" PTR_FORMAT ".",
2747 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2748 }
2749
2750 void JavaThread::remove_stack_guard_pages() {
2751 assert(Thread::current() == this, "from different thread");
2752 if (_stack_guard_state == stack_guard_unused) return;
2753 address low_addr = stack_end();
2754 size_t len = stack_guard_zone_size();
2755
2756 if (os::must_commit_stack_guard_pages()) {
2757 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2758 _stack_guard_state = stack_guard_unused;
2759 } else {
2760 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2761 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2762 return;
2763 }
2764 } else {
2765 if (_stack_guard_state == stack_guard_unused) return;
2766 if (os::unguard_memory((char *) low_addr, len)) {
2767 _stack_guard_state = stack_guard_unused;
2768 } else {
2769 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2770 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2771 return;
2772 }
2773 }
2774
2775 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2776 PTR_FORMAT "-" PTR_FORMAT ".",
2777 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2778 }
2779
2780 void JavaThread::enable_stack_reserved_zone() {
2781 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2782
2783 // The base notation is from the stack's point of view, growing downward.
2784 // We need to adjust it to work correctly with guard_memory()
2785 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2786
2787 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2788 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2789
2790 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2791 _stack_guard_state = stack_guard_enabled;
2792 } else {
2793 warning("Attempt to guard stack reserved zone failed.");
2794 }
2795 enable_register_stack_guard();
2796 }
2797
2798 void JavaThread::disable_stack_reserved_zone() {
2799 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2800
2801 // Simply return if called for a thread that does not use guard pages.
2802 if (_stack_guard_state != stack_guard_enabled) return;
2803
2804 // The base notation is from the stack's point of view, growing downward.
2805 // We need to adjust it to work correctly with guard_memory()
2806 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2807
2808 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2809 _stack_guard_state = stack_guard_reserved_disabled;
2810 } else {
2811 warning("Attempt to unguard stack reserved zone failed.");
2812 }
2813 disable_register_stack_guard();
2814 }
2815
2816 void JavaThread::enable_stack_yellow_reserved_zone() {
2817 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2818 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2819
2820 // The base notation is from the stacks point of view, growing downward.
2821 // We need to adjust it to work correctly with guard_memory()
2822 address base = stack_red_zone_base();
2823
2824 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2825 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2826
2827 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2828 _stack_guard_state = stack_guard_enabled;
2829 } else {
2830 warning("Attempt to guard stack yellow zone failed.");
2831 }
2832 enable_register_stack_guard();
2833 }
2834
2835 void JavaThread::disable_stack_yellow_reserved_zone() {
2836 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2837 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2838
2839 // Simply return if called for a thread that does not use guard pages.
2840 if (_stack_guard_state == stack_guard_unused) return;
2841
2842 // The base notation is from the stacks point of view, growing downward.
2843 // We need to adjust it to work correctly with guard_memory()
2844 address base = stack_red_zone_base();
2845
2846 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2847 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2848 } else {
2849 warning("Attempt to unguard stack yellow zone failed.");
2850 }
2851 disable_register_stack_guard();
2852 }
2853
2854 void JavaThread::enable_stack_red_zone() {
2855 // The base notation is from the stacks point of view, growing downward.
2856 // We need to adjust it to work correctly with guard_memory()
2857 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2858 address base = stack_red_zone_base() - stack_red_zone_size();
2859
2860 guarantee(base < stack_base(), "Error calculating stack red zone");
2861 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2862
2863 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2864 warning("Attempt to guard stack red zone failed.");
2865 }
2866 }
2867
2868 void JavaThread::disable_stack_red_zone() {
2869 // The base notation is from the stacks point of view, growing downward.
2870 // We need to adjust it to work correctly with guard_memory()
2871 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2872 address base = stack_red_zone_base() - stack_red_zone_size();
2873 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2874 warning("Attempt to unguard stack red zone failed.");
2875 }
2876 }
2877
2878 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2879 // ignore is there is no stack
2880 if (!has_last_Java_frame()) return;
2881 // traverse the stack frames. Starts from top frame.
2882 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2883 frame* fr = fst.current();
2884 f(fr, fst.register_map());
2885 }
2886 }
2887
2888
2889 #ifndef PRODUCT
2890 // Deoptimization
2891 // Function for testing deoptimization
2892 void JavaThread::deoptimize() {
2893 StackFrameStream fst(this, false);
2894 bool deopt = false; // Dump stack only if a deopt actually happens.
2895 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2896 // Iterate over all frames in the thread and deoptimize
2897 for (; !fst.is_done(); fst.next()) {
2898 if (fst.current()->can_be_deoptimized()) {
2899
2900 if (only_at) {
2901 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2902 // consists of comma or carriage return separated numbers so
2903 // search for the current bci in that string.
2904 address pc = fst.current()->pc();
2905 nmethod* nm = (nmethod*) fst.current()->cb();
2906 ScopeDesc* sd = nm->scope_desc_at(pc);
2907 char buffer[8];
2908 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2909 size_t len = strlen(buffer);
2910 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2911 while (found != NULL) {
2912 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2913 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2914 // Check that the bci found is bracketed by terminators.
2915 break;
2916 }
2917 found = strstr(found + 1, buffer);
2918 }
2919 if (!found) {
2920 continue;
2921 }
2922 }
2923
2924 if (DebugDeoptimization && !deopt) {
2925 deopt = true; // One-time only print before deopt
2926 tty->print_cr("[BEFORE Deoptimization]");
2927 trace_frames();
2928 trace_stack();
2929 }
2930 Deoptimization::deoptimize(this, *fst.current());
2931 }
2932 }
2933
2934 if (DebugDeoptimization && deopt) {
2935 tty->print_cr("[AFTER Deoptimization]");
2936 trace_frames();
2937 }
2938 }
2939
2940
2941 // Make zombies
2942 void JavaThread::make_zombies() {
2943 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2944 if (fst.current()->can_be_deoptimized()) {
2945 // it is a Java nmethod
2946 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2947 nm->make_not_entrant();
2948 }
2949 }
2950 }
2951 #endif // PRODUCT
2952
2953
2954 void JavaThread::deoptimize_marked_methods() {
2955 if (!has_last_Java_frame()) return;
2956 StackFrameStream fst(this, false);
2957 for (; !fst.is_done(); fst.next()) {
2958 if (fst.current()->should_be_deoptimized()) {
2959 Deoptimization::deoptimize(this, *fst.current());
2960 }
2961 }
2962 }
2963
2964 // If the caller is a NamedThread, then remember, in the current scope,
2965 // the given JavaThread in its _processed_thread field.
2966 class RememberProcessedThread: public StackObj {
2967 NamedThread* _cur_thr;
2968 public:
2969 RememberProcessedThread(JavaThread* jthr) {
2970 Thread* thread = Thread::current();
2971 if (thread->is_Named_thread()) {
2972 _cur_thr = (NamedThread *)thread;
2973 _cur_thr->set_processed_thread(jthr);
2974 } else {
2975 _cur_thr = NULL;
2976 }
2977 }
2978
2979 ~RememberProcessedThread() {
2980 if (_cur_thr) {
2981 _cur_thr->set_processed_thread(NULL);
2982 }
2983 }
2984 };
2985
2986 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2987 // Verify that the deferred card marks have been flushed.
2988 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2989
2990 // Traverse the GCHandles
2991 Thread::oops_do(f, cf);
2992
2993 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2994 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2995
2996 if (has_last_Java_frame()) {
2997 // Record JavaThread to GC thread
2998 RememberProcessedThread rpt(this);
2999
3000 // traverse the registered growable array
3001 if (_array_for_gc != NULL) {
3002 for (int index = 0; index < _array_for_gc->length(); index++) {
3003 f->do_oop(_array_for_gc->adr_at(index));
3004 }
3005 }
3006
3007 // Traverse the monitor chunks
3008 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
3009 chunk->oops_do(f);
3010 }
3011
3012 // Traverse the execution stack
3013 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3014 fst.current()->oops_do(f, cf, fst.register_map());
3015 }
3016 }
3017
3018 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
3019 // If we have deferred set_locals there might be oops waiting to be
3020 // written
3021 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
3022 if (list != NULL) {
3023 for (int i = 0; i < list->length(); i++) {
3024 list->at(i)->oops_do(f);
3025 }
3026 }
3027
3028 // Traverse instance variables at the end since the GC may be moving things
3029 // around using this function
3030 f->do_oop((oop*) &_threadObj);
3031 f->do_oop((oop*) &_vm_result);
3032 f->do_oop((oop*) &_exception_oop);
3033 f->do_oop((oop*) &_pending_async_exception);
3034
3035 if (jvmti_thread_state() != NULL) {
3036 jvmti_thread_state()->oops_do(f, cf);
3037 }
3038 }
3039
3040 #ifdef ASSERT
3041 void JavaThread::verify_states_for_handshake() {
3042 // This checks that the thread has a correct frame state during a handshake.
3043 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3044 (has_last_Java_frame() && java_call_counter() > 0),
3045 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3046 has_last_Java_frame(), java_call_counter());
3047 }
3048 #endif
3049
3050 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3051 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3052 (has_last_Java_frame() && java_call_counter() > 0),
3053 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3054 has_last_Java_frame(), java_call_counter());
3055
3056 if (has_last_Java_frame()) {
3057 // Traverse the execution stack
3058 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3059 fst.current()->nmethods_do(cf);
3060 }
3061 }
3062
3063 if (jvmti_thread_state() != NULL) {
3064 jvmti_thread_state()->nmethods_do(cf);
3065 }
3066 }
3067
3068 void JavaThread::metadata_do(MetadataClosure* f) {
3069 if (has_last_Java_frame()) {
3070 // Traverse the execution stack to call f() on the methods in the stack
3071 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3072 fst.current()->metadata_do(f);
3073 }
3074 } else if (is_Compiler_thread()) {
3075 // need to walk ciMetadata in current compile tasks to keep alive.
3076 CompilerThread* ct = (CompilerThread*)this;
3077 if (ct->env() != NULL) {
3078 ct->env()->metadata_do(f);
3079 }
3080 CompileTask* task = ct->task();
3081 if (task != NULL) {
3082 task->metadata_do(f);
3083 }
3084 }
3085 }
3086
3087 // Printing
3088 const char* _get_thread_state_name(JavaThreadState _thread_state) {
3089 switch (_thread_state) {
3090 case _thread_uninitialized: return "_thread_uninitialized";
3091 case _thread_new: return "_thread_new";
3092 case _thread_new_trans: return "_thread_new_trans";
3093 case _thread_in_native: return "_thread_in_native";
3094 case _thread_in_native_trans: return "_thread_in_native_trans";
3095 case _thread_in_vm: return "_thread_in_vm";
3096 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3097 case _thread_in_Java: return "_thread_in_Java";
3098 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3099 case _thread_blocked: return "_thread_blocked";
3100 case _thread_blocked_trans: return "_thread_blocked_trans";
3101 default: return "unknown thread state";
3102 }
3103 }
3104
3105 #ifndef PRODUCT
3106 void JavaThread::print_thread_state_on(outputStream *st) const {
3107 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3108 };
3109 #endif // PRODUCT
3110
3111 // Called by Threads::print() for VM_PrintThreads operation
3112 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3113 st->print_raw("\"");
3114 st->print_raw(get_thread_name());
3115 st->print_raw("\" ");
3116 oop thread_oop = threadObj();
3117 if (thread_oop != NULL) {
3118 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3119 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3120 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3121 }
3122 Thread::print_on(st, print_extended_info);
3123 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3124 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3125 if (thread_oop != NULL) {
3126 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3127 }
3128 #ifndef PRODUCT
3129 _safepoint_state->print_on(st);
3130 #endif // PRODUCT
3131 if (is_Compiler_thread()) {
3132 CompileTask *task = ((CompilerThread*)this)->task();
3133 if (task != NULL) {
3134 st->print(" Compiling: ");
3135 task->print(st, NULL, true, false);
3136 } else {
3137 st->print(" No compile task");
3138 }
3139 st->cr();
3140 }
3141 }
3142
3143 void JavaThread::print() const { print_on(tty); }
3144
3145 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3146 st->print("%s", get_thread_name_string(buf, buflen));
3147 }
3148
3149 // Called by fatal error handler. The difference between this and
3150 // JavaThread::print() is that we can't grab lock or allocate memory.
3151 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3152 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3153 oop thread_obj = threadObj();
3154 if (thread_obj != NULL) {
3155 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3156 }
3157 st->print(" [");
3158 st->print("%s", _get_thread_state_name(_thread_state));
3159 if (osthread()) {
3160 st->print(", id=%d", osthread()->thread_id());
3161 }
3162 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3163 p2i(stack_end()), p2i(stack_base()));
3164 st->print("]");
3165
3166 ThreadsSMRSupport::print_info_on(this, st);
3167 return;
3168 }
3169
3170 // Verification
3171
3172 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3173
3174 void JavaThread::verify() {
3175 // Verify oops in the thread.
3176 oops_do(&VerifyOopClosure::verify_oop, NULL);
3177
3178 // Verify the stack frames.
3179 frames_do(frame_verify);
3180 }
3181
3182 // CR 6300358 (sub-CR 2137150)
3183 // Most callers of this method assume that it can't return NULL but a
3184 // thread may not have a name whilst it is in the process of attaching to
3185 // the VM - see CR 6412693, and there are places where a JavaThread can be
3186 // seen prior to having it's threadObj set (eg JNI attaching threads and
3187 // if vm exit occurs during initialization). These cases can all be accounted
3188 // for such that this method never returns NULL.
3189 const char* JavaThread::get_thread_name() const {
3190 #ifdef ASSERT
3191 // early safepoints can hit while current thread does not yet have TLS
3192 if (!SafepointSynchronize::is_at_safepoint()) {
3193 Thread *cur = Thread::current();
3194 if (!(cur->is_Java_thread() && cur == this)) {
3195 // Current JavaThreads are allowed to get their own name without
3196 // the Threads_lock.
3197 assert_locked_or_safepoint_or_handshake(Threads_lock, this);
3198 }
3199 }
3200 #endif // ASSERT
3201 return get_thread_name_string();
3202 }
3203
3204 // Returns a non-NULL representation of this thread's name, or a suitable
3205 // descriptive string if there is no set name
3206 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3207 const char* name_str;
3208 oop thread_obj = threadObj();
3209 if (thread_obj != NULL) {
3210 oop name = java_lang_Thread::name(thread_obj);
3211 if (name != NULL) {
3212 if (buf == NULL) {
3213 name_str = java_lang_String::as_utf8_string(name);
3214 } else {
3215 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3216 }
3217 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3218 name_str = "<no-name - thread is attaching>";
3219 } else {
3220 name_str = Thread::name();
3221 }
3222 } else {
3223 name_str = Thread::name();
3224 }
3225 assert(name_str != NULL, "unexpected NULL thread name");
3226 return name_str;
3227 }
3228
3229 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3230
3231 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3232 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3233 // Link Java Thread object <-> C++ Thread
3234
3235 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3236 // and put it into a new Handle. The Handle "thread_oop" can then
3237 // be used to pass the C++ thread object to other methods.
3238
3239 // Set the Java level thread object (jthread) field of the
3240 // new thread (a JavaThread *) to C++ thread object using the
3241 // "thread_oop" handle.
3242
3243 // Set the thread field (a JavaThread *) of the
3244 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3245
3246 Handle thread_oop(Thread::current(),
3247 JNIHandles::resolve_non_null(jni_thread));
3248 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3249 "must be initialized");
3250 set_threadObj(thread_oop());
3251 java_lang_Thread::set_thread(thread_oop(), this);
3252
3253 if (prio == NoPriority) {
3254 prio = java_lang_Thread::priority(thread_oop());
3255 assert(prio != NoPriority, "A valid priority should be present");
3256 }
3257
3258 // Push the Java priority down to the native thread; needs Threads_lock
3259 Thread::set_priority(this, prio);
3260
3261 // Add the new thread to the Threads list and set it in motion.
3262 // We must have threads lock in order to call Threads::add.
3263 // It is crucial that we do not block before the thread is
3264 // added to the Threads list for if a GC happens, then the java_thread oop
3265 // will not be visited by GC.
3266 Threads::add(this);
3267 }
3268
3269 oop JavaThread::current_park_blocker() {
3270 // Support for JSR-166 locks
3271 oop thread_oop = threadObj();
3272 if (thread_oop != NULL) {
3273 return java_lang_Thread::park_blocker(thread_oop);
3274 }
3275 return NULL;
3276 }
3277
3278
3279 void JavaThread::print_stack_on(outputStream* st) {
3280 if (!has_last_Java_frame()) return;
3281 ResourceMark rm;
3282 HandleMark hm;
3283
3284 RegisterMap reg_map(this);
3285 vframe* start_vf = last_java_vframe(®_map);
3286 int count = 0;
3287 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3288 if (f->is_java_frame()) {
3289 javaVFrame* jvf = javaVFrame::cast(f);
3290 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3291
3292 // Print out lock information
3293 if (JavaMonitorsInStackTrace) {
3294 jvf->print_lock_info_on(st, count);
3295 }
3296 } else {
3297 // Ignore non-Java frames
3298 }
3299
3300 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3301 count++;
3302 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3303 }
3304 }
3305
3306
3307 // JVMTI PopFrame support
3308 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3309 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3310 if (in_bytes(size_in_bytes) != 0) {
3311 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3312 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3313 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3314 }
3315 }
3316
3317 void* JavaThread::popframe_preserved_args() {
3318 return _popframe_preserved_args;
3319 }
3320
3321 ByteSize JavaThread::popframe_preserved_args_size() {
3322 return in_ByteSize(_popframe_preserved_args_size);
3323 }
3324
3325 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3326 int sz = in_bytes(popframe_preserved_args_size());
3327 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3328 return in_WordSize(sz / wordSize);
3329 }
3330
3331 void JavaThread::popframe_free_preserved_args() {
3332 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3333 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3334 _popframe_preserved_args = NULL;
3335 _popframe_preserved_args_size = 0;
3336 }
3337
3338 #ifndef PRODUCT
3339
3340 void JavaThread::trace_frames() {
3341 tty->print_cr("[Describe stack]");
3342 int frame_no = 1;
3343 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3344 tty->print(" %d. ", frame_no++);
3345 fst.current()->print_value_on(tty, this);
3346 tty->cr();
3347 }
3348 }
3349
3350 class PrintAndVerifyOopClosure: public OopClosure {
3351 protected:
3352 template <class T> inline void do_oop_work(T* p) {
3353 oop obj = RawAccess<>::oop_load(p);
3354 if (obj == NULL) return;
3355 tty->print(INTPTR_FORMAT ": ", p2i(p));
3356 if (oopDesc::is_oop_or_null(obj)) {
3357 if (obj->is_objArray()) {
3358 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3359 } else {
3360 obj->print();
3361 }
3362 } else {
3363 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3364 }
3365 tty->cr();
3366 }
3367 public:
3368 virtual void do_oop(oop* p) { do_oop_work(p); }
3369 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3370 };
3371
3372 #ifdef ASSERT
3373 // Print or validate the layout of stack frames
3374 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3375 ResourceMark rm;
3376 PRESERVE_EXCEPTION_MARK;
3377 FrameValues values;
3378 int frame_no = 0;
3379 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3380 fst.current()->describe(values, ++frame_no);
3381 if (depth == frame_no) break;
3382 }
3383 if (validate_only) {
3384 values.validate();
3385 } else {
3386 tty->print_cr("[Describe stack layout]");
3387 values.print(this);
3388 }
3389 }
3390 #endif
3391
3392 void JavaThread::trace_stack_from(vframe* start_vf) {
3393 ResourceMark rm;
3394 int vframe_no = 1;
3395 for (vframe* f = start_vf; f; f = f->sender()) {
3396 if (f->is_java_frame()) {
3397 javaVFrame::cast(f)->print_activation(vframe_no++);
3398 } else {
3399 f->print();
3400 }
3401 if (vframe_no > StackPrintLimit) {
3402 tty->print_cr("...<more frames>...");
3403 return;
3404 }
3405 }
3406 }
3407
3408
3409 void JavaThread::trace_stack() {
3410 if (!has_last_Java_frame()) return;
3411 ResourceMark rm;
3412 HandleMark hm;
3413 RegisterMap reg_map(this);
3414 trace_stack_from(last_java_vframe(®_map));
3415 }
3416
3417
3418 #endif // PRODUCT
3419
3420
3421 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3422 assert(reg_map != NULL, "a map must be given");
3423 frame f = last_frame();
3424 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3425 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3426 }
3427 return NULL;
3428 }
3429
3430
3431 Klass* JavaThread::security_get_caller_class(int depth) {
3432 vframeStream vfst(this);
3433 vfst.security_get_caller_frame(depth);
3434 if (!vfst.at_end()) {
3435 return vfst.method()->method_holder();
3436 }
3437 return NULL;
3438 }
3439
3440 // java.lang.Thread.sleep support
3441 // Returns true if sleep time elapsed as expected, and false
3442 // if the thread was interrupted.
3443 bool JavaThread::sleep(jlong millis) {
3444 assert(this == Thread::current(), "thread consistency check");
3445
3446 ParkEvent * const slp = this->_SleepEvent;
3447 // Because there can be races with thread interruption sending an unpark()
3448 // to the event, we explicitly reset it here to avoid an immediate return.
3449 // The actual interrupt state will be checked before we park().
3450 slp->reset();
3451 // Thread interruption establishes a happens-before ordering in the
3452 // Java Memory Model, so we need to ensure we synchronize with the
3453 // interrupt state.
3454 OrderAccess::fence();
3455
3456 jlong prevtime = os::javaTimeNanos();
3457
3458 for (;;) {
3459 // interruption has precedence over timing out
3460 if (this->is_interrupted(true)) {
3461 return false;
3462 }
3463
3464 if (millis <= 0) {
3465 return true;
3466 }
3467
3468 {
3469 ThreadBlockInVM tbivm(this);
3470 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
3471
3472 this->set_suspend_equivalent();
3473 // cleared by handle_special_suspend_equivalent_condition() or
3474 // java_suspend_self() via check_and_wait_while_suspended()
3475
3476 slp->park(millis);
3477
3478 // were we externally suspended while we were waiting?
3479 this->check_and_wait_while_suspended();
3480 }
3481
3482 // Update elapsed time tracking
3483 jlong newtime = os::javaTimeNanos();
3484 if (newtime - prevtime < 0) {
3485 // time moving backwards, should only happen if no monotonic clock
3486 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3487 assert(!os::supports_monotonic_clock(),
3488 "unexpected time moving backwards detected in JavaThread::sleep()");
3489 } else {
3490 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3491 }
3492 prevtime = newtime;
3493 }
3494 }
3495
3496 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3497 assert(thread->is_Compiler_thread(), "must be compiler thread");
3498 CompileBroker::compiler_thread_loop();
3499 }
3500
3501 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3502 NMethodSweeper::sweeper_loop();
3503 }
3504
3505 // Create a CompilerThread
3506 CompilerThread::CompilerThread(CompileQueue* queue,
3507 CompilerCounters* counters)
3508 : JavaThread(&compiler_thread_entry) {
3509 _env = NULL;
3510 _log = NULL;
3511 _task = NULL;
3512 _queue = queue;
3513 _counters = counters;
3514 _buffer_blob = NULL;
3515 _compiler = NULL;
3516
3517 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3518 resource_area()->bias_to(mtCompiler);
3519
3520 #ifndef PRODUCT
3521 _ideal_graph_printer = NULL;
3522 #endif
3523 }
3524
3525 CompilerThread::~CompilerThread() {
3526 // Delete objects which were allocated on heap.
3527 delete _counters;
3528 }
3529
3530 bool CompilerThread::can_call_java() const {
3531 return _compiler != NULL && _compiler->is_jvmci();
3532 }
3533
3534 // Create sweeper thread
3535 CodeCacheSweeperThread::CodeCacheSweeperThread()
3536 : JavaThread(&sweeper_thread_entry) {
3537 _scanned_compiled_method = NULL;
3538 }
3539
3540 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3541 JavaThread::oops_do(f, cf);
3542 if (_scanned_compiled_method != NULL && cf != NULL) {
3543 // Safepoints can occur when the sweeper is scanning an nmethod so
3544 // process it here to make sure it isn't unloaded in the middle of
3545 // a scan.
3546 cf->do_code_blob(_scanned_compiled_method);
3547 }
3548 }
3549
3550 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3551 JavaThread::nmethods_do(cf);
3552 if (_scanned_compiled_method != NULL && cf != NULL) {
3553 // Safepoints can occur when the sweeper is scanning an nmethod so
3554 // process it here to make sure it isn't unloaded in the middle of
3555 // a scan.
3556 cf->do_code_blob(_scanned_compiled_method);
3557 }
3558 }
3559
3560
3561 // ======= Threads ========
3562
3563 // The Threads class links together all active threads, and provides
3564 // operations over all threads. It is protected by the Threads_lock,
3565 // which is also used in other global contexts like safepointing.
3566 // ThreadsListHandles are used to safely perform operations on one
3567 // or more threads without the risk of the thread exiting during the
3568 // operation.
3569 //
3570 // Note: The Threads_lock is currently more widely used than we
3571 // would like. We are actively migrating Threads_lock uses to other
3572 // mechanisms in order to reduce Threads_lock contention.
3573
3574 int Threads::_number_of_threads = 0;
3575 int Threads::_number_of_non_daemon_threads = 0;
3576 int Threads::_return_code = 0;
3577 uintx Threads::_thread_claim_token = 1; // Never zero.
3578 size_t JavaThread::_stack_size_at_create = 0;
3579
3580 #ifdef ASSERT
3581 bool Threads::_vm_complete = false;
3582 #endif
3583
3584 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3585 Prefetch::read((void*)addr, prefetch_interval);
3586 return *addr;
3587 }
3588
3589 // Possibly the ugliest for loop the world has seen. C++ does not allow
3590 // multiple types in the declaration section of the for loop. In this case
3591 // we are only dealing with pointers and hence can cast them. It looks ugly
3592 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3593 #define DO_JAVA_THREADS(LIST, X) \
3594 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3595 *MACRO_list = (JavaThread*)(LIST), \
3596 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3597 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3598 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3599 MACRO_current_p != MACRO_end; \
3600 MACRO_current_p++, \
3601 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3602
3603 // All JavaThreads
3604 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3605
3606 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3607 void Threads::non_java_threads_do(ThreadClosure* tc) {
3608 NoSafepointVerifier nsv;
3609 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3610 tc->do_thread(njti.current());
3611 }
3612 }
3613
3614 // All JavaThreads
3615 void Threads::java_threads_do(ThreadClosure* tc) {
3616 assert_locked_or_safepoint(Threads_lock);
3617 // ALL_JAVA_THREADS iterates through all JavaThreads.
3618 ALL_JAVA_THREADS(p) {
3619 tc->do_thread(p);
3620 }
3621 }
3622
3623 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3624 assert_locked_or_safepoint(Threads_lock);
3625 java_threads_do(tc);
3626 tc->do_thread(VMThread::vm_thread());
3627 }
3628
3629 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3630 void Threads::threads_do(ThreadClosure* tc) {
3631 assert_locked_or_safepoint(Threads_lock);
3632 java_threads_do(tc);
3633 non_java_threads_do(tc);
3634 }
3635
3636 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3637 uintx claim_token = Threads::thread_claim_token();
3638 ALL_JAVA_THREADS(p) {
3639 if (p->claim_threads_do(is_par, claim_token)) {
3640 tc->do_thread(p);
3641 }
3642 }
3643 VMThread* vmt = VMThread::vm_thread();
3644 if (vmt->claim_threads_do(is_par, claim_token)) {
3645 tc->do_thread(vmt);
3646 }
3647 }
3648
3649 // The system initialization in the library has three phases.
3650 //
3651 // Phase 1: java.lang.System class initialization
3652 // java.lang.System is a primordial class loaded and initialized
3653 // by the VM early during startup. java.lang.System.<clinit>
3654 // only does registerNatives and keeps the rest of the class
3655 // initialization work later until thread initialization completes.
3656 //
3657 // System.initPhase1 initializes the system properties, the static
3658 // fields in, out, and err. Set up java signal handlers, OS-specific
3659 // system settings, and thread group of the main thread.
3660 static void call_initPhase1(TRAPS) {
3661 Klass* klass = SystemDictionary::System_klass();
3662 JavaValue result(T_VOID);
3663 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3664 vmSymbols::void_method_signature(), CHECK);
3665 }
3666
3667 // Phase 2. Module system initialization
3668 // This will initialize the module system. Only java.base classes
3669 // can be loaded until phase 2 completes.
3670 //
3671 // Call System.initPhase2 after the compiler initialization and jsr292
3672 // classes get initialized because module initialization runs a lot of java
3673 // code, that for performance reasons, should be compiled. Also, this will
3674 // enable the startup code to use lambda and other language features in this
3675 // phase and onward.
3676 //
3677 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3678 static void call_initPhase2(TRAPS) {
3679 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3680
3681 Klass* klass = SystemDictionary::System_klass();
3682
3683 JavaValue result(T_INT);
3684 JavaCallArguments args;
3685 args.push_int(DisplayVMOutputToStderr);
3686 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3687 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3688 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3689 if (result.get_jint() != JNI_OK) {
3690 vm_exit_during_initialization(); // no message or exception
3691 }
3692
3693 universe_post_module_init();
3694 }
3695
3696 // Phase 3. final setup - set security manager, system class loader and TCCL
3697 //
3698 // This will instantiate and set the security manager, set the system class
3699 // loader as well as the thread context class loader. The security manager
3700 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3701 // other modules or the application's classpath.
3702 static void call_initPhase3(TRAPS) {
3703 Klass* klass = SystemDictionary::System_klass();
3704 JavaValue result(T_VOID);
3705 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3706 vmSymbols::void_method_signature(), CHECK);
3707 }
3708
3709 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3710 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3711
3712 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3713 create_vm_init_libraries();
3714 }
3715
3716 initialize_class(vmSymbols::java_lang_String(), CHECK);
3717
3718 // Inject CompactStrings value after the static initializers for String ran.
3719 java_lang_String::set_compact_strings(CompactStrings);
3720
3721 // Initialize java_lang.System (needed before creating the thread)
3722 initialize_class(vmSymbols::java_lang_System(), CHECK);
3723 // The VM creates & returns objects of this class. Make sure it's initialized.
3724 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3725 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3726 Handle thread_group = create_initial_thread_group(CHECK);
3727 Universe::set_main_thread_group(thread_group());
3728 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3729 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3730 main_thread->set_threadObj(thread_object);
3731
3732 // Set thread status to running since main thread has
3733 // been started and running.
3734 java_lang_Thread::set_thread_status(thread_object,
3735 java_lang_Thread::RUNNABLE);
3736
3737 // The VM creates objects of this class.
3738 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3739
3740 #ifdef ASSERT
3741 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3742 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3743 #endif
3744
3745 // initialize the hardware-specific constants needed by Unsafe
3746 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3747 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3748
3749 // The VM preresolves methods to these classes. Make sure that they get initialized
3750 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3751 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3752
3753 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3754 call_initPhase1(CHECK);
3755
3756 // get the Java runtime name, version, and vendor info after java.lang.System is initialized
3757 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3758 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3759 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD));
3760 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD));
3761
3762 // an instance of OutOfMemory exception has been allocated earlier
3763 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3764 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3765 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3766 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3767 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3768 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3769 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3770 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3771
3772 // Eager box cache initialization only if AOT is on and any library is loaded.
3773 AOTLoader::initialize_box_caches(CHECK);
3774 }
3775
3776 void Threads::initialize_jsr292_core_classes(TRAPS) {
3777 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3778
3779 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3780 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3781 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3782 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3783 }
3784
3785 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3786 extern void JDK_Version_init();
3787
3788 // Preinitialize version info.
3789 VM_Version::early_initialize();
3790
3791 // Check version
3792 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3793
3794 // Initialize library-based TLS
3795 ThreadLocalStorage::init();
3796
3797 // Initialize the output stream module
3798 ostream_init();
3799
3800 // Process java launcher properties.
3801 Arguments::process_sun_java_launcher_properties(args);
3802
3803 // Initialize the os module
3804 os::init();
3805
3806 // Record VM creation timing statistics
3807 TraceVmCreationTime create_vm_timer;
3808 create_vm_timer.start();
3809
3810 // Initialize system properties.
3811 Arguments::init_system_properties();
3812
3813 // So that JDK version can be used as a discriminator when parsing arguments
3814 JDK_Version_init();
3815
3816 // Update/Initialize System properties after JDK version number is known
3817 Arguments::init_version_specific_system_properties();
3818
3819 // Make sure to initialize log configuration *before* parsing arguments
3820 LogConfiguration::initialize(create_vm_timer.begin_time());
3821
3822 // Parse arguments
3823 // Note: this internally calls os::init_container_support()
3824 jint parse_result = Arguments::parse(args);
3825 if (parse_result != JNI_OK) return parse_result;
3826
3827 os::init_before_ergo();
3828
3829 jint ergo_result = Arguments::apply_ergo();
3830 if (ergo_result != JNI_OK) return ergo_result;
3831
3832 // Final check of all ranges after ergonomics which may change values.
3833 if (!JVMFlagRangeList::check_ranges()) {
3834 return JNI_EINVAL;
3835 }
3836
3837 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3838 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3839 if (!constraint_result) {
3840 return JNI_EINVAL;
3841 }
3842
3843 if (PauseAtStartup) {
3844 os::pause();
3845 }
3846
3847 HOTSPOT_VM_INIT_BEGIN();
3848
3849 // Timing (must come after argument parsing)
3850 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3851
3852 // Initialize the os module after parsing the args
3853 jint os_init_2_result = os::init_2();
3854 if (os_init_2_result != JNI_OK) return os_init_2_result;
3855
3856 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3857 // Initialize assert poison page mechanism.
3858 if (ShowRegistersOnAssert) {
3859 initialize_assert_poison();
3860 }
3861 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3862
3863 SafepointMechanism::initialize();
3864
3865 jint adjust_after_os_result = Arguments::adjust_after_os();
3866 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3867
3868 // Initialize output stream logging
3869 ostream_init_log();
3870
3871 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3872 // Must be before create_vm_init_agents()
3873 if (Arguments::init_libraries_at_startup()) {
3874 convert_vm_init_libraries_to_agents();
3875 }
3876
3877 // Launch -agentlib/-agentpath and converted -Xrun agents
3878 if (Arguments::init_agents_at_startup()) {
3879 create_vm_init_agents();
3880 }
3881
3882 // Initialize Threads state
3883 _number_of_threads = 0;
3884 _number_of_non_daemon_threads = 0;
3885
3886 // Initialize global data structures and create system classes in heap
3887 vm_init_globals();
3888
3889 #if INCLUDE_JVMCI
3890 if (JVMCICounterSize > 0) {
3891 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3892 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3893 } else {
3894 JavaThread::_jvmci_old_thread_counters = NULL;
3895 }
3896 #endif // INCLUDE_JVMCI
3897
3898 // Attach the main thread to this os thread
3899 JavaThread* main_thread = new JavaThread();
3900 main_thread->set_thread_state(_thread_in_vm);
3901 main_thread->initialize_thread_current();
3902 // must do this before set_active_handles
3903 main_thread->record_stack_base_and_size();
3904 main_thread->register_thread_stack_with_NMT();
3905 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3906
3907 if (!main_thread->set_as_starting_thread()) {
3908 vm_shutdown_during_initialization(
3909 "Failed necessary internal allocation. Out of swap space");
3910 main_thread->smr_delete();
3911 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3912 return JNI_ENOMEM;
3913 }
3914
3915 // Enable guard page *after* os::create_main_thread(), otherwise it would
3916 // crash Linux VM, see notes in os_linux.cpp.
3917 main_thread->create_stack_guard_pages();
3918
3919 // Initialize Java-Level synchronization subsystem
3920 ObjectMonitor::Initialize();
3921
3922 // Initialize global modules
3923 jint status = init_globals();
3924 if (status != JNI_OK) {
3925 main_thread->smr_delete();
3926 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3927 return status;
3928 }
3929
3930 JFR_ONLY(Jfr::on_create_vm_1();)
3931
3932 // Should be done after the heap is fully created
3933 main_thread->cache_global_variables();
3934
3935 HandleMark hm;
3936
3937 { MutexLocker mu(Threads_lock);
3938 Threads::add(main_thread);
3939 }
3940
3941 // Any JVMTI raw monitors entered in onload will transition into
3942 // real raw monitor. VM is setup enough here for raw monitor enter.
3943 JvmtiExport::transition_pending_onload_raw_monitors();
3944
3945 // Create the VMThread
3946 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3947
3948 VMThread::create();
3949 Thread* vmthread = VMThread::vm_thread();
3950
3951 if (!os::create_thread(vmthread, os::vm_thread)) {
3952 vm_exit_during_initialization("Cannot create VM thread. "
3953 "Out of system resources.");
3954 }
3955
3956 // Wait for the VM thread to become ready, and VMThread::run to initialize
3957 // Monitors can have spurious returns, must always check another state flag
3958 {
3959 MonitorLocker ml(Notify_lock);
3960 os::start_thread(vmthread);
3961 while (vmthread->active_handles() == NULL) {
3962 ml.wait();
3963 }
3964 }
3965 }
3966
3967 assert(Universe::is_fully_initialized(), "not initialized");
3968 if (VerifyDuringStartup) {
3969 // Make sure we're starting with a clean slate.
3970 VM_Verify verify_op;
3971 VMThread::execute(&verify_op);
3972 }
3973
3974 // We need this to update the java.vm.info property in case any flags used
3975 // to initially define it have been changed. This is needed for both CDS and
3976 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3977 // is initially computed. See Abstract_VM_Version::vm_info_string().
3978 // This update must happen before we initialize the java classes, but
3979 // after any initialization logic that might modify the flags.
3980 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3981
3982 Thread* THREAD = Thread::current();
3983
3984 // Always call even when there are not JVMTI environments yet, since environments
3985 // may be attached late and JVMTI must track phases of VM execution
3986 JvmtiExport::enter_early_start_phase();
3987
3988 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3989 JvmtiExport::post_early_vm_start();
3990
3991 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3992
3993 quicken_jni_functions();
3994
3995 // No more stub generation allowed after that point.
3996 StubCodeDesc::freeze();
3997
3998 // Set flag that basic initialization has completed. Used by exceptions and various
3999 // debug stuff, that does not work until all basic classes have been initialized.
4000 set_init_completed();
4001
4002 LogConfiguration::post_initialize();
4003 Metaspace::post_initialize();
4004
4005 HOTSPOT_VM_INIT_END();
4006
4007 // record VM initialization completion time
4008 #if INCLUDE_MANAGEMENT
4009 Management::record_vm_init_completed();
4010 #endif // INCLUDE_MANAGEMENT
4011
4012 // Signal Dispatcher needs to be started before VMInit event is posted
4013 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
4014
4015 // Start Attach Listener if +StartAttachListener or it can't be started lazily
4016 if (!DisableAttachMechanism) {
4017 AttachListener::vm_start();
4018 if (StartAttachListener || AttachListener::init_at_startup()) {
4019 AttachListener::init();
4020 }
4021 }
4022
4023 // Launch -Xrun agents
4024 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
4025 // back-end can launch with -Xdebug -Xrunjdwp.
4026 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
4027 create_vm_init_libraries();
4028 }
4029
4030 if (CleanChunkPoolAsync) {
4031 Chunk::start_chunk_pool_cleaner_task();
4032 }
4033
4034 // Start the service thread
4035 // The service thread enqueues JVMTI deferred events and does various hashtable
4036 // and other cleanups. Needs to start before the compilers start posting events.
4037 ServiceThread::initialize();
4038
4039 // initialize compiler(s)
4040 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
4041 #if INCLUDE_JVMCI
4042 bool force_JVMCI_intialization = false;
4043 if (EnableJVMCI) {
4044 // Initialize JVMCI eagerly when it is explicitly requested.
4045 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
4046 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
4047
4048 if (!force_JVMCI_intialization) {
4049 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4050 // compilations via JVMCI will not actually block until JVMCI is initialized.
4051 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4052 }
4053 }
4054 #endif
4055 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4056 // Postpone completion of compiler initialization to after JVMCI
4057 // is initialized to avoid timeouts of blocking compilations.
4058 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4059 CompileBroker::compilation_init_phase2();
4060 }
4061 #endif
4062
4063 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4064 // It is done after compilers are initialized, because otherwise compilations of
4065 // signature polymorphic MH intrinsics can be missed
4066 // (see SystemDictionary::find_method_handle_intrinsic).
4067 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4068
4069 // This will initialize the module system. Only java.base classes can be
4070 // loaded until phase 2 completes
4071 call_initPhase2(CHECK_JNI_ERR);
4072
4073 JFR_ONLY(Jfr::on_create_vm_2();)
4074
4075 // Always call even when there are not JVMTI environments yet, since environments
4076 // may be attached late and JVMTI must track phases of VM execution
4077 JvmtiExport::enter_start_phase();
4078
4079 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4080 JvmtiExport::post_vm_start();
4081
4082 // Final system initialization including security manager and system class loader
4083 call_initPhase3(CHECK_JNI_ERR);
4084
4085 // cache the system and platform class loaders
4086 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4087
4088 #if INCLUDE_CDS
4089 // capture the module path info from the ModuleEntryTable
4090 ClassLoader::initialize_module_path(THREAD);
4091 #endif
4092
4093 #if INCLUDE_JVMCI
4094 if (force_JVMCI_intialization) {
4095 JVMCI::initialize_compiler(CHECK_JNI_ERR);
4096 CompileBroker::compilation_init_phase2();
4097 }
4098 #endif
4099
4100 // Always call even when there are not JVMTI environments yet, since environments
4101 // may be attached late and JVMTI must track phases of VM execution
4102 JvmtiExport::enter_live_phase();
4103
4104 // Make perfmemory accessible
4105 PerfMemory::set_accessible(true);
4106
4107 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4108 JvmtiExport::post_vm_initialized();
4109
4110 JFR_ONLY(Jfr::on_create_vm_3();)
4111
4112 #if INCLUDE_MANAGEMENT
4113 Management::initialize(THREAD);
4114
4115 if (HAS_PENDING_EXCEPTION) {
4116 // management agent fails to start possibly due to
4117 // configuration problem and is responsible for printing
4118 // stack trace if appropriate. Simply exit VM.
4119 vm_exit(1);
4120 }
4121 #endif // INCLUDE_MANAGEMENT
4122
4123 if (MemProfiling) MemProfiler::engage();
4124 StatSampler::engage();
4125 if (CheckJNICalls) JniPeriodicChecker::engage();
4126
4127 BiasedLocking::init();
4128
4129 #if INCLUDE_RTM_OPT
4130 RTMLockingCounters::init();
4131 #endif
4132
4133 call_postVMInitHook(THREAD);
4134 // The Java side of PostVMInitHook.run must deal with all
4135 // exceptions and provide means of diagnosis.
4136 if (HAS_PENDING_EXCEPTION) {
4137 CLEAR_PENDING_EXCEPTION;
4138 }
4139
4140 {
4141 MutexLocker ml(PeriodicTask_lock);
4142 // Make sure the WatcherThread can be started by WatcherThread::start()
4143 // or by dynamic enrollment.
4144 WatcherThread::make_startable();
4145 // Start up the WatcherThread if there are any periodic tasks
4146 // NOTE: All PeriodicTasks should be registered by now. If they
4147 // aren't, late joiners might appear to start slowly (we might
4148 // take a while to process their first tick).
4149 if (PeriodicTask::num_tasks() > 0) {
4150 WatcherThread::start();
4151 }
4152 }
4153
4154 create_vm_timer.end();
4155 #ifdef ASSERT
4156 _vm_complete = true;
4157 #endif
4158
4159 if (DumpSharedSpaces) {
4160 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4161 ShouldNotReachHere();
4162 }
4163
4164 return JNI_OK;
4165 }
4166
4167 // type for the Agent_OnLoad and JVM_OnLoad entry points
4168 extern "C" {
4169 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4170 }
4171 // Find a command line agent library and return its entry point for
4172 // -agentlib: -agentpath: -Xrun
4173 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4174 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4175 const char *on_load_symbols[],
4176 size_t num_symbol_entries) {
4177 OnLoadEntry_t on_load_entry = NULL;
4178 void *library = NULL;
4179
4180 if (!agent->valid()) {
4181 char buffer[JVM_MAXPATHLEN];
4182 char ebuf[1024] = "";
4183 const char *name = agent->name();
4184 const char *msg = "Could not find agent library ";
4185
4186 // First check to see if agent is statically linked into executable
4187 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4188 library = agent->os_lib();
4189 } else if (agent->is_absolute_path()) {
4190 library = os::dll_load(name, ebuf, sizeof ebuf);
4191 if (library == NULL) {
4192 const char *sub_msg = " in absolute path, with error: ";
4193 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4194 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4195 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4196 // If we can't find the agent, exit.
4197 vm_exit_during_initialization(buf, NULL);
4198 FREE_C_HEAP_ARRAY(char, buf);
4199 }
4200 } else {
4201 // Try to load the agent from the standard dll directory
4202 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4203 name)) {
4204 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4205 }
4206 if (library == NULL) { // Try the library path directory.
4207 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4208 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4209 }
4210 if (library == NULL) {
4211 const char *sub_msg = " on the library path, with error: ";
4212 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4213
4214 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4215 strlen(ebuf) + strlen(sub_msg2) + 1;
4216 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4217 if (!agent->is_instrument_lib()) {
4218 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4219 } else {
4220 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4221 }
4222 // If we can't find the agent, exit.
4223 vm_exit_during_initialization(buf, NULL);
4224 FREE_C_HEAP_ARRAY(char, buf);
4225 }
4226 }
4227 }
4228 agent->set_os_lib(library);
4229 agent->set_valid();
4230 }
4231
4232 // Find the OnLoad function.
4233 on_load_entry =
4234 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4235 false,
4236 on_load_symbols,
4237 num_symbol_entries));
4238 return on_load_entry;
4239 }
4240
4241 // Find the JVM_OnLoad entry point
4242 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4243 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4244 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4245 }
4246
4247 // Find the Agent_OnLoad entry point
4248 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4249 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4250 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4251 }
4252
4253 // For backwards compatibility with -Xrun
4254 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4255 // treated like -agentpath:
4256 // Must be called before agent libraries are created
4257 void Threads::convert_vm_init_libraries_to_agents() {
4258 AgentLibrary* agent;
4259 AgentLibrary* next;
4260
4261 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4262 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4263 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4264
4265 // If there is an JVM_OnLoad function it will get called later,
4266 // otherwise see if there is an Agent_OnLoad
4267 if (on_load_entry == NULL) {
4268 on_load_entry = lookup_agent_on_load(agent);
4269 if (on_load_entry != NULL) {
4270 // switch it to the agent list -- so that Agent_OnLoad will be called,
4271 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4272 Arguments::convert_library_to_agent(agent);
4273 } else {
4274 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4275 }
4276 }
4277 }
4278 }
4279
4280 // Create agents for -agentlib: -agentpath: and converted -Xrun
4281 // Invokes Agent_OnLoad
4282 // Called very early -- before JavaThreads exist
4283 void Threads::create_vm_init_agents() {
4284 extern struct JavaVM_ main_vm;
4285 AgentLibrary* agent;
4286
4287 JvmtiExport::enter_onload_phase();
4288
4289 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4290 // CDS dumping does not support native JVMTI agent.
4291 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4292 if (Arguments::is_dumping_archive()) {
4293 if(!agent->is_instrument_lib()) {
4294 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4295 } else if (!AllowArchivingWithJavaAgent) {
4296 vm_exit_during_cds_dumping(
4297 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4298 }
4299 }
4300
4301 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4302
4303 if (on_load_entry != NULL) {
4304 // Invoke the Agent_OnLoad function
4305 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4306 if (err != JNI_OK) {
4307 vm_exit_during_initialization("agent library failed to init", agent->name());
4308 }
4309 } else {
4310 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4311 }
4312 }
4313
4314 JvmtiExport::enter_primordial_phase();
4315 }
4316
4317 extern "C" {
4318 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4319 }
4320
4321 void Threads::shutdown_vm_agents() {
4322 // Send any Agent_OnUnload notifications
4323 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4324 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4325 extern struct JavaVM_ main_vm;
4326 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4327
4328 // Find the Agent_OnUnload function.
4329 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4330 os::find_agent_function(agent,
4331 false,
4332 on_unload_symbols,
4333 num_symbol_entries));
4334
4335 // Invoke the Agent_OnUnload function
4336 if (unload_entry != NULL) {
4337 JavaThread* thread = JavaThread::current();
4338 ThreadToNativeFromVM ttn(thread);
4339 HandleMark hm(thread);
4340 (*unload_entry)(&main_vm);
4341 }
4342 }
4343 }
4344
4345 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4346 // Invokes JVM_OnLoad
4347 void Threads::create_vm_init_libraries() {
4348 extern struct JavaVM_ main_vm;
4349 AgentLibrary* agent;
4350
4351 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4352 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4353
4354 if (on_load_entry != NULL) {
4355 // Invoke the JVM_OnLoad function
4356 JavaThread* thread = JavaThread::current();
4357 ThreadToNativeFromVM ttn(thread);
4358 HandleMark hm(thread);
4359 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4360 if (err != JNI_OK) {
4361 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4362 }
4363 } else {
4364 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4365 }
4366 }
4367 }
4368
4369
4370 // Last thread running calls java.lang.Shutdown.shutdown()
4371 void JavaThread::invoke_shutdown_hooks() {
4372 HandleMark hm(this);
4373
4374 // Link all classes for dynamic CDS dumping before vm exit.
4375 // Same operation is being done in JVM_BeforeHalt for handling the
4376 // case where the application calls System.exit().
4377 if (DynamicDumpSharedSpaces) {
4378 MetaspaceShared::link_and_cleanup_shared_classes(this);
4379 }
4380
4381 // We could get here with a pending exception, if so clear it now.
4382 if (this->has_pending_exception()) {
4383 this->clear_pending_exception();
4384 }
4385
4386 EXCEPTION_MARK;
4387 Klass* shutdown_klass =
4388 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4389 THREAD);
4390 if (shutdown_klass != NULL) {
4391 // SystemDictionary::resolve_or_null will return null if there was
4392 // an exception. If we cannot load the Shutdown class, just don't
4393 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4394 // won't be run. Note that if a shutdown hook was registered,
4395 // the Shutdown class would have already been loaded
4396 // (Runtime.addShutdownHook will load it).
4397 JavaValue result(T_VOID);
4398 JavaCalls::call_static(&result,
4399 shutdown_klass,
4400 vmSymbols::shutdown_name(),
4401 vmSymbols::void_method_signature(),
4402 THREAD);
4403 }
4404 CLEAR_PENDING_EXCEPTION;
4405 }
4406
4407 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4408 // the program falls off the end of main(). Another VM exit path is through
4409 // vm_exit() when the program calls System.exit() to return a value or when
4410 // there is a serious error in VM. The two shutdown paths are not exactly
4411 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4412 // and VM_Exit op at VM level.
4413 //
4414 // Shutdown sequence:
4415 // + Shutdown native memory tracking if it is on
4416 // + Wait until we are the last non-daemon thread to execute
4417 // <-- every thing is still working at this moment -->
4418 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4419 // shutdown hooks
4420 // + Call before_exit(), prepare for VM exit
4421 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4422 // currently the only user of this mechanism is File.deleteOnExit())
4423 // > stop StatSampler, watcher thread,
4424 // post thread end and vm death events to JVMTI,
4425 // stop signal thread
4426 // + Call JavaThread::exit(), it will:
4427 // > release JNI handle blocks, remove stack guard pages
4428 // > remove this thread from Threads list
4429 // <-- no more Java code from this thread after this point -->
4430 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4431 // the compiler threads at safepoint
4432 // <-- do not use anything that could get blocked by Safepoint -->
4433 // + Disable tracing at JNI/JVM barriers
4434 // + Set _vm_exited flag for threads that are still running native code
4435 // + Call exit_globals()
4436 // > deletes tty
4437 // > deletes PerfMemory resources
4438 // + Delete this thread
4439 // + Return to caller
4440
4441 bool Threads::destroy_vm() {
4442 JavaThread* thread = JavaThread::current();
4443
4444 #ifdef ASSERT
4445 _vm_complete = false;
4446 #endif
4447 // Wait until we are the last non-daemon thread to execute
4448 { MonitorLocker nu(Threads_lock);
4449 while (Threads::number_of_non_daemon_threads() > 1)
4450 // This wait should make safepoint checks, wait without a timeout,
4451 // and wait as a suspend-equivalent condition.
4452 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4453 }
4454
4455 EventShutdown e;
4456 if (e.should_commit()) {
4457 e.set_reason("No remaining non-daemon Java threads");
4458 e.commit();
4459 }
4460
4461 // Hang forever on exit if we are reporting an error.
4462 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4463 os::infinite_sleep();
4464 }
4465 os::wait_for_keypress_at_exit();
4466
4467 // run Java level shutdown hooks
4468 thread->invoke_shutdown_hooks();
4469
4470 before_exit(thread);
4471
4472 thread->exit(true);
4473
4474 // We are no longer on the main thread list but could still be in a
4475 // secondary list where another thread may try to interact with us.
4476 // So wait until all such interactions are complete before we bring
4477 // the VM to the termination safepoint. Normally this would be done
4478 // using thread->smr_delete() below where we delete the thread, but
4479 // we can't call that after the termination safepoint is active as
4480 // we will deadlock on the Threads_lock. Once all interactions are
4481 // complete it is safe to directly delete the thread at any time.
4482 ThreadsSMRSupport::wait_until_not_protected(thread);
4483
4484 // Stop VM thread.
4485 {
4486 // 4945125 The vm thread comes to a safepoint during exit.
4487 // GC vm_operations can get caught at the safepoint, and the
4488 // heap is unparseable if they are caught. Grab the Heap_lock
4489 // to prevent this. The GC vm_operations will not be able to
4490 // queue until after the vm thread is dead. After this point,
4491 // we'll never emerge out of the safepoint before the VM exits.
4492
4493 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4494
4495 VMThread::wait_for_vm_thread_exit();
4496 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4497 VMThread::destroy();
4498 }
4499
4500 // Now, all Java threads are gone except daemon threads. Daemon threads
4501 // running Java code or in VM are stopped by the Safepoint. However,
4502 // daemon threads executing native code are still running. But they
4503 // will be stopped at native=>Java/VM barriers. Note that we can't
4504 // simply kill or suspend them, as it is inherently deadlock-prone.
4505
4506 VM_Exit::set_vm_exited();
4507
4508 // Clean up ideal graph printers after the VMThread has started
4509 // the final safepoint which will block all the Compiler threads.
4510 // Note that this Thread has already logically exited so the
4511 // clean_up() function's use of a JavaThreadIteratorWithHandle
4512 // would be a problem except set_vm_exited() has remembered the
4513 // shutdown thread which is granted a policy exception.
4514 #if defined(COMPILER2) && !defined(PRODUCT)
4515 IdealGraphPrinter::clean_up();
4516 #endif
4517
4518 notify_vm_shutdown();
4519
4520 // exit_globals() will delete tty
4521 exit_globals();
4522
4523 // Deleting the shutdown thread here is safe. See comment on
4524 // wait_until_not_protected() above.
4525 delete thread;
4526
4527 #if INCLUDE_JVMCI
4528 if (JVMCICounterSize > 0) {
4529 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4530 }
4531 #endif
4532
4533 LogConfiguration::finalize();
4534
4535 return true;
4536 }
4537
4538
4539 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4540 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4541 return is_supported_jni_version(version);
4542 }
4543
4544
4545 jboolean Threads::is_supported_jni_version(jint version) {
4546 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4547 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4548 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4549 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4550 if (version == JNI_VERSION_9) return JNI_TRUE;
4551 if (version == JNI_VERSION_10) return JNI_TRUE;
4552 return JNI_FALSE;
4553 }
4554
4555
4556 void Threads::add(JavaThread* p, bool force_daemon) {
4557 // The threads lock must be owned at this point
4558 assert(Threads_lock->owned_by_self(), "must have threads lock");
4559
4560 BarrierSet::barrier_set()->on_thread_attach(p);
4561
4562 // Once a JavaThread is added to the Threads list, smr_delete() has
4563 // to be used to delete it. Otherwise we can just delete it directly.
4564 p->set_on_thread_list();
4565
4566 _number_of_threads++;
4567 oop threadObj = p->threadObj();
4568 bool daemon = true;
4569 // Bootstrapping problem: threadObj can be null for initial
4570 // JavaThread (or for threads attached via JNI)
4571 if ((!force_daemon) && !is_daemon((threadObj))) {
4572 _number_of_non_daemon_threads++;
4573 daemon = false;
4574 }
4575
4576 ThreadService::add_thread(p, daemon);
4577
4578 // Maintain fast thread list
4579 ThreadsSMRSupport::add_thread(p);
4580
4581 // Possible GC point.
4582 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4583
4584 // Make new thread known to active EscapeBarrier
4585 EscapeBarrier::thread_added(p);
4586 }
4587
4588 void Threads::remove(JavaThread* p, bool is_daemon) {
4589
4590 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4591 ObjectSynchronizer::om_flush(p);
4592
4593 // Extra scope needed for Thread_lock, so we can check
4594 // that we do not remove thread without safepoint code notice
4595 { MonitorLocker ml(Threads_lock);
4596
4597 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4598
4599 // Maintain fast thread list
4600 ThreadsSMRSupport::remove_thread(p);
4601
4602 _number_of_threads--;
4603 if (!is_daemon) {
4604 _number_of_non_daemon_threads--;
4605
4606 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4607 // on destroy_vm will wake up.
4608 if (number_of_non_daemon_threads() == 1) {
4609 ml.notify_all();
4610 }
4611 }
4612 ThreadService::remove_thread(p, is_daemon);
4613
4614 // Make sure that safepoint code disregard this thread. This is needed since
4615 // the thread might mess around with locks after this point. This can cause it
4616 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4617 // of this thread since it is removed from the queue.
4618 p->set_terminated_value();
4619 } // unlock Threads_lock
4620
4621 // Since Events::log uses a lock, we grab it outside the Threads_lock
4622 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4623 }
4624
4625 // Operations on the Threads list for GC. These are not explicitly locked,
4626 // but the garbage collector must provide a safe context for them to run.
4627 // In particular, these things should never be called when the Threads_lock
4628 // is held by some other thread. (Note: the Safepoint abstraction also
4629 // uses the Threads_lock to guarantee this property. It also makes sure that
4630 // all threads gets blocked when exiting or starting).
4631
4632 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4633 ALL_JAVA_THREADS(p) {
4634 p->oops_do(f, cf);
4635 }
4636 VMThread::vm_thread()->oops_do(f, cf);
4637 }
4638
4639 void Threads::change_thread_claim_token() {
4640 if (++_thread_claim_token == 0) {
4641 // On overflow of the token counter, there is a risk of future
4642 // collisions between a new global token value and a stale token
4643 // for a thread, because not all iterations visit all threads.
4644 // (Though it's pretty much a theoretical concern for non-trivial
4645 // token counter sizes.) To deal with the possibility, reset all
4646 // the thread tokens to zero on global token overflow.
4647 struct ResetClaims : public ThreadClosure {
4648 virtual void do_thread(Thread* t) {
4649 t->claim_threads_do(false, 0);
4650 }
4651 } reset_claims;
4652 Threads::threads_do(&reset_claims);
4653 // On overflow, update the global token to non-zero, to
4654 // avoid the special "never claimed" initial thread value.
4655 _thread_claim_token = 1;
4656 }
4657 }
4658
4659 #ifdef ASSERT
4660 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4661 const uintx token = t->threads_do_token();
4662 assert(token == expected,
4663 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4664 UINTX_FORMAT, kind, p2i(t), token, expected);
4665 }
4666
4667 void Threads::assert_all_threads_claimed() {
4668 ALL_JAVA_THREADS(p) {
4669 assert_thread_claimed("Thread", p, _thread_claim_token);
4670 }
4671 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4672 }
4673 #endif // ASSERT
4674
4675 class ParallelOopsDoThreadClosure : public ThreadClosure {
4676 private:
4677 OopClosure* _f;
4678 CodeBlobClosure* _cf;
4679 public:
4680 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4681 void do_thread(Thread* t) {
4682 t->oops_do(_f, _cf);
4683 }
4684 };
4685
4686 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4687 ParallelOopsDoThreadClosure tc(f, cf);
4688 possibly_parallel_threads_do(is_par, &tc);
4689 }
4690
4691 void Threads::nmethods_do(CodeBlobClosure* cf) {
4692 ALL_JAVA_THREADS(p) {
4693 // This is used by the code cache sweeper to mark nmethods that are active
4694 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4695 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4696 if(!p->is_Code_cache_sweeper_thread()) {
4697 p->nmethods_do(cf);
4698 }
4699 }
4700 }
4701
4702 void Threads::metadata_do(MetadataClosure* f) {
4703 ALL_JAVA_THREADS(p) {
4704 p->metadata_do(f);
4705 }
4706 }
4707
4708 class ThreadHandlesClosure : public ThreadClosure {
4709 void (*_f)(Metadata*);
4710 public:
4711 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4712 virtual void do_thread(Thread* thread) {
4713 thread->metadata_handles_do(_f);
4714 }
4715 };
4716
4717 void Threads::metadata_handles_do(void f(Metadata*)) {
4718 // Only walk the Handles in Thread.
4719 ThreadHandlesClosure handles_closure(f);
4720 threads_do(&handles_closure);
4721 }
4722
4723 // Get count Java threads that are waiting to enter the specified monitor.
4724 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4725 int count,
4726 address monitor) {
4727 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4728
4729 int i = 0;
4730 DO_JAVA_THREADS(t_list, p) {
4731 if (!p->can_call_java()) continue;
4732
4733 // The first stage of async deflation does not affect any field
4734 // used by this comparison so the ObjectMonitor* is usable here.
4735 address pending = (address)p->current_pending_monitor();
4736 if (pending == monitor) { // found a match
4737 if (i < count) result->append(p); // save the first count matches
4738 i++;
4739 }
4740 }
4741
4742 return result;
4743 }
4744
4745
4746 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4747 address owner) {
4748 // NULL owner means not locked so we can skip the search
4749 if (owner == NULL) return NULL;
4750
4751 DO_JAVA_THREADS(t_list, p) {
4752 // first, see if owner is the address of a Java thread
4753 if (owner == (address)p) return p;
4754 }
4755
4756 // Cannot assert on lack of success here since this function may be
4757 // used by code that is trying to report useful problem information
4758 // like deadlock detection.
4759 if (UseHeavyMonitors) return NULL;
4760
4761 // If we didn't find a matching Java thread and we didn't force use of
4762 // heavyweight monitors, then the owner is the stack address of the
4763 // Lock Word in the owning Java thread's stack.
4764 //
4765 JavaThread* the_owner = NULL;
4766 DO_JAVA_THREADS(t_list, q) {
4767 if (q->is_lock_owned(owner)) {
4768 the_owner = q;
4769 break;
4770 }
4771 }
4772
4773 // cannot assert on lack of success here; see above comment
4774 return the_owner;
4775 }
4776
4777 class PrintOnClosure : public ThreadClosure {
4778 private:
4779 outputStream* _st;
4780
4781 public:
4782 PrintOnClosure(outputStream* st) :
4783 _st(st) {}
4784
4785 virtual void do_thread(Thread* thread) {
4786 if (thread != NULL) {
4787 thread->print_on(_st);
4788 _st->cr();
4789 }
4790 }
4791 };
4792
4793 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4794 void Threads::print_on(outputStream* st, bool print_stacks,
4795 bool internal_format, bool print_concurrent_locks,
4796 bool print_extended_info) {
4797 char buf[32];
4798 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4799
4800 st->print_cr("Full thread dump %s (%s %s):",
4801 VM_Version::vm_name(),
4802 VM_Version::vm_release(),
4803 VM_Version::vm_info_string());
4804 st->cr();
4805
4806 #if INCLUDE_SERVICES
4807 // Dump concurrent locks
4808 ConcurrentLocksDump concurrent_locks;
4809 if (print_concurrent_locks) {
4810 concurrent_locks.dump_at_safepoint();
4811 }
4812 #endif // INCLUDE_SERVICES
4813
4814 ThreadsSMRSupport::print_info_on(st);
4815 st->cr();
4816
4817 ALL_JAVA_THREADS(p) {
4818 ResourceMark rm;
4819 p->print_on(st, print_extended_info);
4820 if (print_stacks) {
4821 if (internal_format) {
4822 p->trace_stack();
4823 } else {
4824 p->print_stack_on(st);
4825 }
4826 }
4827 st->cr();
4828 #if INCLUDE_SERVICES
4829 if (print_concurrent_locks) {
4830 concurrent_locks.print_locks_on(p, st);
4831 }
4832 #endif // INCLUDE_SERVICES
4833 }
4834
4835 PrintOnClosure cl(st);
4836 cl.do_thread(VMThread::vm_thread());
4837 Universe::heap()->gc_threads_do(&cl);
4838 cl.do_thread(WatcherThread::watcher_thread());
4839
4840 st->flush();
4841 }
4842
4843 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4844 int buflen, bool* found_current) {
4845 if (this_thread != NULL) {
4846 bool is_current = (current == this_thread);
4847 *found_current = *found_current || is_current;
4848 st->print("%s", is_current ? "=>" : " ");
4849
4850 st->print(PTR_FORMAT, p2i(this_thread));
4851 st->print(" ");
4852 this_thread->print_on_error(st, buf, buflen);
4853 st->cr();
4854 }
4855 }
4856
4857 class PrintOnErrorClosure : public ThreadClosure {
4858 outputStream* _st;
4859 Thread* _current;
4860 char* _buf;
4861 int _buflen;
4862 bool* _found_current;
4863 public:
4864 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4865 int buflen, bool* found_current) :
4866 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4867
4868 virtual void do_thread(Thread* thread) {
4869 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4870 }
4871 };
4872
4873 // Threads::print_on_error() is called by fatal error handler. It's possible
4874 // that VM is not at safepoint and/or current thread is inside signal handler.
4875 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4876 // memory (even in resource area), it might deadlock the error handler.
4877 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4878 int buflen) {
4879 ThreadsSMRSupport::print_info_on(st);
4880 st->cr();
4881
4882 bool found_current = false;
4883 st->print_cr("Java Threads: ( => current thread )");
4884 ALL_JAVA_THREADS(thread) {
4885 print_on_error(thread, st, current, buf, buflen, &found_current);
4886 }
4887 st->cr();
4888
4889 st->print_cr("Other Threads:");
4890 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4891 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4892
4893 if (Universe::heap() != NULL) {
4894 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4895 Universe::heap()->gc_threads_do(&print_closure);
4896 }
4897
4898 if (!found_current) {
4899 st->cr();
4900 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4901 current->print_on_error(st, buf, buflen);
4902 st->cr();
4903 }
4904 st->cr();
4905
4906 st->print_cr("Threads with active compile tasks:");
4907 print_threads_compiling(st, buf, buflen);
4908 }
4909
4910 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4911 ALL_JAVA_THREADS(thread) {
4912 if (thread->is_Compiler_thread()) {
4913 CompilerThread* ct = (CompilerThread*) thread;
4914
4915 // Keep task in local variable for NULL check.
4916 // ct->_task might be set to NULL by concurring compiler thread
4917 // because it completed the compilation. The task is never freed,
4918 // though, just returned to a free list.
4919 CompileTask* task = ct->task();
4920 if (task != NULL) {
4921 thread->print_name_on_error(st, buf, buflen);
4922 st->print(" ");
4923 task->print(st, NULL, short_form, true);
4924 }
4925 }
4926 }
4927 }
4928
4929
4930 // Internal SpinLock and Mutex
4931 // Based on ParkEvent
4932
4933 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4934 //
4935 // We employ SpinLocks _only for low-contention, fixed-length
4936 // short-duration critical sections where we're concerned
4937 // about native mutex_t or HotSpot Mutex:: latency.
4938 // The mux construct provides a spin-then-block mutual exclusion
4939 // mechanism.
4940 //
4941 // Testing has shown that contention on the ListLock guarding gFreeList
4942 // is common. If we implement ListLock as a simple SpinLock it's common
4943 // for the JVM to devolve to yielding with little progress. This is true
4944 // despite the fact that the critical sections protected by ListLock are
4945 // extremely short.
4946 //
4947 // TODO-FIXME: ListLock should be of type SpinLock.
4948 // We should make this a 1st-class type, integrated into the lock
4949 // hierarchy as leaf-locks. Critically, the SpinLock structure
4950 // should have sufficient padding to avoid false-sharing and excessive
4951 // cache-coherency traffic.
4952
4953
4954 typedef volatile int SpinLockT;
4955
4956 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4957 if (Atomic::cmpxchg(adr, 0, 1) == 0) {
4958 return; // normal fast-path return
4959 }
4960
4961 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4962 int ctr = 0;
4963 int Yields = 0;
4964 for (;;) {
4965 while (*adr != 0) {
4966 ++ctr;
4967 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4968 if (Yields > 5) {
4969 os::naked_short_sleep(1);
4970 } else {
4971 os::naked_yield();
4972 ++Yields;
4973 }
4974 } else {
4975 SpinPause();
4976 }
4977 }
4978 if (Atomic::cmpxchg(adr, 0, 1) == 0) return;
4979 }
4980 }
4981
4982 void Thread::SpinRelease(volatile int * adr) {
4983 assert(*adr != 0, "invariant");
4984 OrderAccess::fence(); // guarantee at least release consistency.
4985 // Roach-motel semantics.
4986 // It's safe if subsequent LDs and STs float "up" into the critical section,
4987 // but prior LDs and STs within the critical section can't be allowed
4988 // to reorder or float past the ST that releases the lock.
4989 // Loads and stores in the critical section - which appear in program
4990 // order before the store that releases the lock - must also appear
4991 // before the store that releases the lock in memory visibility order.
4992 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4993 // the ST of 0 into the lock-word which releases the lock, so fence
4994 // more than covers this on all platforms.
4995 *adr = 0;
4996 }
4997
4998 // muxAcquire and muxRelease:
4999 //
5000 // * muxAcquire and muxRelease support a single-word lock-word construct.
5001 // The LSB of the word is set IFF the lock is held.
5002 // The remainder of the word points to the head of a singly-linked list
5003 // of threads blocked on the lock.
5004 //
5005 // * The current implementation of muxAcquire-muxRelease uses its own
5006 // dedicated Thread._MuxEvent instance. If we're interested in
5007 // minimizing the peak number of extant ParkEvent instances then
5008 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
5009 // as certain invariants were satisfied. Specifically, care would need
5010 // to be taken with regards to consuming unpark() "permits".
5011 // A safe rule of thumb is that a thread would never call muxAcquire()
5012 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
5013 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
5014 // consume an unpark() permit intended for monitorenter, for instance.
5015 // One way around this would be to widen the restricted-range semaphore
5016 // implemented in park(). Another alternative would be to provide
5017 // multiple instances of the PlatformEvent() for each thread. One
5018 // instance would be dedicated to muxAcquire-muxRelease, for instance.
5019 //
5020 // * Usage:
5021 // -- Only as leaf locks
5022 // -- for short-term locking only as muxAcquire does not perform
5023 // thread state transitions.
5024 //
5025 // Alternatives:
5026 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
5027 // but with parking or spin-then-park instead of pure spinning.
5028 // * Use Taura-Oyama-Yonenzawa locks.
5029 // * It's possible to construct a 1-0 lock if we encode the lockword as
5030 // (List,LockByte). Acquire will CAS the full lockword while Release
5031 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
5032 // acquiring threads use timers (ParkTimed) to detect and recover from
5033 // the stranding window. Thread/Node structures must be aligned on 256-byte
5034 // boundaries by using placement-new.
5035 // * Augment MCS with advisory back-link fields maintained with CAS().
5036 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
5037 // The validity of the backlinks must be ratified before we trust the value.
5038 // If the backlinks are invalid the exiting thread must back-track through the
5039 // the forward links, which are always trustworthy.
5040 // * Add a successor indication. The LockWord is currently encoded as
5041 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
5042 // to provide the usual futile-wakeup optimization.
5043 // See RTStt for details.
5044 //
5045
5046
5047 const intptr_t LOCKBIT = 1;
5048
5049 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
5050 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT);
5051 if (w == 0) return;
5052 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5053 return;
5054 }
5055
5056 ParkEvent * const Self = Thread::current()->_MuxEvent;
5057 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
5058 for (;;) {
5059 int its = (os::is_MP() ? 100 : 0) + 1;
5060
5061 // Optional spin phase: spin-then-park strategy
5062 while (--its >= 0) {
5063 w = *Lock;
5064 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5065 return;
5066 }
5067 }
5068
5069 Self->reset();
5070 Self->OnList = intptr_t(Lock);
5071 // The following fence() isn't _strictly necessary as the subsequent
5072 // CAS() both serializes execution and ratifies the fetched *Lock value.
5073 OrderAccess::fence();
5074 for (;;) {
5075 w = *Lock;
5076 if ((w & LOCKBIT) == 0) {
5077 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) {
5078 Self->OnList = 0; // hygiene - allows stronger asserts
5079 return;
5080 }
5081 continue; // Interference -- *Lock changed -- Just retry
5082 }
5083 assert(w & LOCKBIT, "invariant");
5084 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5085 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break;
5086 }
5087
5088 while (Self->OnList != 0) {
5089 Self->park();
5090 }
5091 }
5092 }
5093
5094 // Release() must extract a successor from the list and then wake that thread.
5095 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5096 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5097 // Release() would :
5098 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5099 // (B) Extract a successor from the private list "in-hand"
5100 // (C) attempt to CAS() the residual back into *Lock over null.
5101 // If there were any newly arrived threads and the CAS() would fail.
5102 // In that case Release() would detach the RATs, re-merge the list in-hand
5103 // with the RATs and repeat as needed. Alternately, Release() might
5104 // detach and extract a successor, but then pass the residual list to the wakee.
5105 // The wakee would be responsible for reattaching and remerging before it
5106 // competed for the lock.
5107 //
5108 // Both "pop" and DMR are immune from ABA corruption -- there can be
5109 // multiple concurrent pushers, but only one popper or detacher.
5110 // This implementation pops from the head of the list. This is unfair,
5111 // but tends to provide excellent throughput as hot threads remain hot.
5112 // (We wake recently run threads first).
5113 //
5114 // All paths through muxRelease() will execute a CAS.
5115 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5116 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5117 // executed within the critical section are complete and globally visible before the
5118 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5119 void Thread::muxRelease(volatile intptr_t * Lock) {
5120 for (;;) {
5121 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0);
5122 assert(w & LOCKBIT, "invariant");
5123 if (w == LOCKBIT) return;
5124 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5125 assert(List != NULL, "invariant");
5126 assert(List->OnList == intptr_t(Lock), "invariant");
5127 ParkEvent * const nxt = List->ListNext;
5128 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5129
5130 // The following CAS() releases the lock and pops the head element.
5131 // The CAS() also ratifies the previously fetched lock-word value.
5132 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) {
5133 continue;
5134 }
5135 List->OnList = 0;
5136 OrderAccess::fence();
5137 List->unpark();
5138 return;
5139 }
5140 }
5141
5142
5143 void Threads::verify() {
5144 ALL_JAVA_THREADS(p) {
5145 p->verify();
5146 }
5147 VMThread* thread = VMThread::vm_thread();
5148 if (thread != NULL) thread->verify();
5149 }