1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jvmtifiles/jvmtiEnv.hpp"
45 #include "logging/log.hpp"
46 #include "logging/logConfiguration.hpp"
47 #include "logging/logStream.hpp"
48 #include "memory/allocation.inline.hpp"
49 #include "memory/metaspaceShared.hpp"
50 #include "memory/oopFactory.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "memory/universe.hpp"
53 #include "oops/access.inline.hpp"
54 #include "oops/instanceKlass.hpp"
55 #include "oops/objArrayOop.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/symbol.hpp"
58 #include "oops/typeArrayOop.inline.hpp"
59 #include "oops/verifyOopClosure.hpp"
60 #include "prims/jvm_misc.hpp"
61 #include "prims/jvmtiExport.hpp"
62 #include "prims/jvmtiThreadState.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/fieldDescriptor.inline.hpp"
67 #include "runtime/flags/jvmFlagConstraintList.hpp"
68 #include "runtime/flags/jvmFlagRangeList.hpp"
69 #include "runtime/flags/jvmFlagWriteableList.hpp"
70 #include "runtime/deoptimization.hpp"
71 #include "runtime/frame.inline.hpp"
72 #include "runtime/handles.inline.hpp"
73 #include "runtime/handshake.hpp"
74 #include "runtime/init.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/jniHandles.inline.hpp"
79 #include "runtime/jniPeriodicChecker.hpp"
80 #include "runtime/memprofiler.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/objectMonitor.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/osThread.hpp"
85 #include "runtime/prefetch.inline.hpp"
86 #include "runtime/safepoint.hpp"
87 #include "runtime/safepointMechanism.inline.hpp"
88 #include "runtime/safepointVerifiers.hpp"
89 #include "runtime/sharedRuntime.hpp"
90 #include "runtime/statSampler.hpp"
91 #include "runtime/stubRoutines.hpp"
92 #include "runtime/sweeper.hpp"
93 #include "runtime/task.hpp"
94 #include "runtime/thread.inline.hpp"
95 #include "runtime/threadCritical.hpp"
96 #include "runtime/threadSMR.inline.hpp"
97 #include "runtime/threadStatisticalInfo.hpp"
98 #include "runtime/timer.hpp"
99 #include "runtime/timerTrace.hpp"
100 #include "runtime/vframe.inline.hpp"
101 #include "runtime/vframeArray.hpp"
102 #include "runtime/vframe_hp.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "runtime/vmOperations.hpp"
105 #include "runtime/vm_version.hpp"
106 #include "services/attachListener.hpp"
107 #include "services/management.hpp"
108 #include "services/memTracker.hpp"
109 #include "services/threadService.hpp"
110 #include "utilities/align.hpp"
111 #include "utilities/copy.hpp"
112 #include "utilities/defaultStream.hpp"
113 #include "utilities/dtrace.hpp"
114 #include "utilities/events.hpp"
115 #include "utilities/macros.hpp"
116 #include "utilities/preserveException.hpp"
117 #include "utilities/singleWriterSynchronizer.hpp"
118 #include "utilities/vmError.hpp"
119 #if INCLUDE_JVMCI
120 #include "jvmci/jvmci.hpp"
121 #include "jvmci/jvmciEnv.hpp"
122 #endif
123 #ifdef COMPILER1
124 #include "c1/c1_Compiler.hpp"
125 #endif
126 #ifdef COMPILER2
127 #include "opto/c2compiler.hpp"
128 #include "opto/idealGraphPrinter.hpp"
129 #endif
130 #if INCLUDE_RTM_OPT
131 #include "runtime/rtmLocking.hpp"
132 #endif
133 #if INCLUDE_JFR
134 #include "jfr/jfr.hpp"
135 #endif
136
137 // Initialization after module runtime initialization
138 void universe_post_module_init(); // must happen after call_initPhase2
139
140 #ifdef DTRACE_ENABLED
141
142 // Only bother with this argument setup if dtrace is available
143
144 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
145 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
146
147 #define DTRACE_THREAD_PROBE(probe, javathread) \
148 { \
149 ResourceMark rm(this); \
150 int len = 0; \
151 const char* name = (javathread)->get_thread_name(); \
152 len = strlen(name); \
153 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
154 (char *) name, len, \
155 java_lang_Thread::thread_id((javathread)->threadObj()), \
156 (uintptr_t) (javathread)->osthread()->thread_id(), \
157 java_lang_Thread::is_daemon((javathread)->threadObj())); \
158 }
159
160 #else // ndef DTRACE_ENABLED
161
162 #define DTRACE_THREAD_PROBE(probe, javathread)
163
164 #endif // ndef DTRACE_ENABLED
165
166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
167 // Current thread is maintained as a thread-local variable
168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
169 #endif
170
171 // ======= Thread ========
172 // Support for forcing alignment of thread objects for biased locking
173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
174 if (UseBiasedLocking) {
175 const int alignment = markOopDesc::biased_lock_alignment;
176 size_t aligned_size = size + (alignment - sizeof(intptr_t));
177 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
178 : AllocateHeap(aligned_size, flags, CURRENT_PC,
179 AllocFailStrategy::RETURN_NULL);
180 void* aligned_addr = align_up(real_malloc_addr, alignment);
181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
183 "JavaThread alignment code overflowed allocated storage");
184 if (aligned_addr != real_malloc_addr) {
185 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
186 p2i(real_malloc_addr),
187 p2i(aligned_addr));
188 }
189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
190 return aligned_addr;
191 } else {
192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
193 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
194 }
195 }
196
197 void Thread::operator delete(void* p) {
198 if (UseBiasedLocking) {
199 FreeHeap(((Thread*) p)->_real_malloc_address);
200 } else {
201 FreeHeap(p);
202 }
203 }
204
205 void JavaThread::smr_delete() {
206 if (_on_thread_list) {
207 ThreadsSMRSupport::smr_delete(this);
208 } else {
209 delete this;
210 }
211 }
212
213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
214 // JavaThread
215
216 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
217
218 Thread::Thread() {
219
220 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
221
222 // stack and get_thread
223 set_stack_base(NULL);
224 set_stack_size(0);
225 set_self_raw_id(0);
226 set_lgrp_id(-1);
227 DEBUG_ONLY(clear_suspendible_thread();)
228
229 // allocated data structures
230 set_osthread(NULL);
231 set_resource_area(new (mtThread)ResourceArea());
232 DEBUG_ONLY(_current_resource_mark = NULL;)
233 set_handle_area(new (mtThread) HandleArea(NULL));
234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
235 set_active_handles(NULL);
236 set_free_handle_block(NULL);
237 set_last_handle_mark(NULL);
238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
239
240 // Initial value of zero ==> never claimed.
241 _threads_do_token = 0;
242 _threads_hazard_ptr = NULL;
243 _threads_list_ptr = NULL;
244 _nested_threads_hazard_ptr_cnt = 0;
245 _rcu_counter = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 debug_only(_allow_allocation_count = 0;)
253 NOT_PRODUCT(_allow_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 _num_nested_signal = 0;
263 omFreeList = NULL;
264 omFreeCount = 0;
265 omFreeProvision = 32;
266 omInUseList = NULL;
267 omInUseCount = 0;
268
269 #ifdef ASSERT
270 _visited_for_critical_count = false;
271 #endif
272
273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
274 Monitor::_safepoint_check_sometimes);
275 _suspend_flags = 0;
276
277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
278 _hashStateX = os::random();
279 _hashStateY = 842502087;
280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
281 _hashStateW = 273326509;
282
283 _OnTrap = 0;
284 _Stalled = 0;
285 _TypeTag = 0x2BAD;
286
287 // Many of the following fields are effectively final - immutable
288 // Note that nascent threads can't use the Native Monitor-Mutex
289 // construct until the _MutexEvent is initialized ...
290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
291 // we might instead use a stack of ParkEvents that we could provision on-demand.
292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
293 // and ::Release()
294 _ParkEvent = ParkEvent::Allocate(this);
295 _SleepEvent = 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((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
306 assert(this == _real_malloc_address ||
307 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
308 "bug in forced alignment of thread objects");
309 }
310 #endif // ASSERT
311
312 // Notify the barrier set that a thread is being created. The initial
313 // thread is created before the barrier set is available. The call to
314 // BarrierSet::on_thread_create() for this thread is therefore deferred
315 // to BarrierSet::set_barrier_set().
316 BarrierSet* const barrier_set = BarrierSet::barrier_set();
317 if (barrier_set != NULL) {
318 barrier_set->on_thread_create(this);
319 } else {
320 // Only the main thread should be created before the barrier set
321 // and that happens just before Thread::current is set. No other thread
322 // can attach as the VM is not created yet, so they can't execute this code.
323 // If the main thread creates other threads before the barrier set that is an error.
324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
325 }
326 }
327
328 void Thread::initialize_thread_current() {
329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
330 assert(_thr_current == NULL, "Thread::current already initialized");
331 _thr_current = this;
332 #endif
333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
334 ThreadLocalStorage::set_thread(this);
335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
336 }
337
338 void Thread::clear_thread_current() {
339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
341 _thr_current = NULL;
342 #endif
343 ThreadLocalStorage::set_thread(NULL);
344 }
345
346 void Thread::record_stack_base_and_size() {
347 // Note: at this point, Thread object is not yet initialized. Do not rely on
348 // any members being initialized. Do not rely on Thread::current() being set.
349 // If possible, refrain from doing anything which may crash or assert since
350 // quite probably those crash dumps will be useless.
351 set_stack_base(os::current_stack_base());
352 set_stack_size(os::current_stack_size());
353
354 #ifdef SOLARIS
355 if (os::is_primordial_thread()) {
356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
357 }
358 #endif
359
360 // Set stack limits after thread is initialized.
361 if (is_Java_thread()) {
362 ((JavaThread*) this)->set_stack_overflow_limit();
363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
364 }
365 }
366
367 #if INCLUDE_NMT
368 void Thread::register_thread_stack_with_NMT() {
369 MemTracker::record_thread_stack(stack_end(), stack_size());
370 }
371 #endif // INCLUDE_NMT
372
373 void Thread::call_run() {
374 DEBUG_ONLY(_run_state = CALL_RUN;)
375
376 // At this point, Thread object should be fully initialized and
377 // Thread::current() should be set.
378
379 assert(Thread::current_or_null() != NULL, "current thread is unset");
380 assert(Thread::current_or_null() == this, "current thread is wrong");
381
382 // Perform common initialization actions
383
384 register_thread_stack_with_NMT();
385
386 JFR_ONLY(Jfr::on_thread_start(this);)
387
388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
390 os::current_thread_id(), p2i(stack_base() - stack_size()),
391 p2i(stack_base()), stack_size()/1024);
392
393 // Perform <ChildClass> initialization actions
394 DEBUG_ONLY(_run_state = PRE_RUN;)
395 this->pre_run();
396
397 // Invoke <ChildClass>::run()
398 DEBUG_ONLY(_run_state = RUN;)
399 this->run();
400 // Returned from <ChildClass>::run(). Thread finished.
401
402 // Perform common tear-down actions
403
404 assert(Thread::current_or_null() != NULL, "current thread is unset");
405 assert(Thread::current_or_null() == this, "current thread is wrong");
406
407 // Perform <ChildClass> tear-down actions
408 DEBUG_ONLY(_run_state = POST_RUN;)
409 this->post_run();
410
411 // Note: at this point the thread object may already have deleted itself,
412 // so from here on do not dereference *this*. Not all thread types currently
413 // delete themselves when they terminate. But no thread should ever be deleted
414 // asynchronously with respect to its termination - that is what _run_state can
415 // be used to check.
416
417 assert(Thread::current_or_null() == NULL, "current thread still present");
418 }
419
420 Thread::~Thread() {
421
422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
423 // get started due to errors etc. Any active thread should at least reach post_run
424 // before it is deleted (usually in post_run()).
425 assert(_run_state == PRE_CALL_RUN ||
426 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
427 "_run_state=%d", (int)_run_state);
428
429 // Notify the barrier set that a thread is being destroyed. Note that a barrier
430 // set might not be available if we encountered errors during bootstrapping.
431 BarrierSet* const barrier_set = BarrierSet::barrier_set();
432 if (barrier_set != NULL) {
433 barrier_set->on_thread_destroy(this);
434 }
435
436 // stack_base can be NULL if the thread is never started or exited before
437 // record_stack_base_and_size called. Although, we would like to ensure
438 // that all started threads do call record_stack_base_and_size(), there is
439 // not proper way to enforce that.
440 #if INCLUDE_NMT
441 if (_stack_base != NULL) {
442 MemTracker::release_thread_stack(stack_end(), stack_size());
443 #ifdef ASSERT
444 set_stack_base(NULL);
445 #endif
446 }
447 #endif // INCLUDE_NMT
448
449 // deallocate data structures
450 delete resource_area();
451 // since the handle marks are using the handle area, we have to deallocated the root
452 // handle mark before deallocating the thread's handle area,
453 assert(last_handle_mark() != NULL, "check we have an element");
454 delete last_handle_mark();
455 assert(last_handle_mark() == NULL, "check we have reached the end");
456
457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
458 // We NULL out the fields for good hygiene.
459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
460 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
461 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
462
463 delete handle_area();
464 delete metadata_handles();
465
466 // SR_handler uses this as a termination indicator -
467 // needs to happen before os::free_thread()
468 delete _SR_lock;
469 _SR_lock = NULL;
470
471 // osthread() can be NULL, if creation of thread failed.
472 if (osthread() != NULL) os::free_thread(osthread());
473
474 // Clear Thread::current if thread is deleting itself and it has not
475 // already been done. This must be done before the memory is deallocated.
476 // Needed to ensure JNI correctly detects non-attached threads.
477 if (this == Thread::current_or_null()) {
478 Thread::clear_thread_current();
479 }
480
481 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
482 }
483
484 #ifdef ASSERT
485 // A JavaThread is considered "dangling" if it is not the current
486 // thread, has been added the Threads list, the system is not at a
487 // safepoint and the Thread is not "protected".
488 //
489 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
490 assert(!thread->is_Java_thread() || Thread::current() == thread ||
491 !((JavaThread *) thread)->on_thread_list() ||
492 SafepointSynchronize::is_at_safepoint() ||
493 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
494 "possibility of dangling Thread pointer");
495 }
496 #endif
497
498 ThreadPriority Thread::get_priority(const Thread* const thread) {
499 ThreadPriority priority;
500 // Can return an error!
501 (void)os::get_priority(thread, priority);
502 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
503 return priority;
504 }
505
506 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
507 debug_only(check_for_dangling_thread_pointer(thread);)
508 // Can return an error!
509 (void)os::set_priority(thread, priority);
510 }
511
512
513 void Thread::start(Thread* thread) {
514 // Start is different from resume in that its safety is guaranteed by context or
515 // being called from a Java method synchronized on the Thread object.
516 if (!DisableStartThread) {
517 if (thread->is_Java_thread()) {
518 // Initialize the thread state to RUNNABLE before starting this thread.
519 // Can not set it after the thread started because we do not know the
520 // exact thread state at that time. It could be in MONITOR_WAIT or
521 // in SLEEPING or some other state.
522 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
523 java_lang_Thread::RUNNABLE);
524 }
525 os::start_thread(thread);
526 }
527 }
528
529 // Enqueue a VM_Operation to do the job for us - sometime later
530 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
531 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
532 VMThread::execute(vm_stop);
533 }
534
535
536 // Check if an external suspend request has completed (or has been
537 // cancelled). Returns true if the thread is externally suspended and
538 // false otherwise.
539 //
540 // The bits parameter returns information about the code path through
541 // the routine. Useful for debugging:
542 //
543 // set in is_ext_suspend_completed():
544 // 0x00000001 - routine was entered
545 // 0x00000010 - routine return false at end
546 // 0x00000100 - thread exited (return false)
547 // 0x00000200 - suspend request cancelled (return false)
548 // 0x00000400 - thread suspended (return true)
549 // 0x00001000 - thread is in a suspend equivalent state (return true)
550 // 0x00002000 - thread is native and walkable (return true)
551 // 0x00004000 - thread is native_trans and walkable (needed retry)
552 //
553 // set in wait_for_ext_suspend_completion():
554 // 0x00010000 - routine was entered
555 // 0x00020000 - suspend request cancelled before loop (return false)
556 // 0x00040000 - thread suspended before loop (return true)
557 // 0x00080000 - suspend request cancelled in loop (return false)
558 // 0x00100000 - thread suspended in loop (return true)
559 // 0x00200000 - suspend not completed during retry loop (return false)
560
561 // Helper class for tracing suspend wait debug bits.
562 //
563 // 0x00000100 indicates that the target thread exited before it could
564 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
565 // 0x00080000 each indicate a cancelled suspend request so they don't
566 // count as wait failures either.
567 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
568
569 class TraceSuspendDebugBits : public StackObj {
570 private:
571 JavaThread * jt;
572 bool is_wait;
573 bool called_by_wait; // meaningful when !is_wait
574 uint32_t * bits;
575
576 public:
577 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
578 uint32_t *_bits) {
579 jt = _jt;
580 is_wait = _is_wait;
581 called_by_wait = _called_by_wait;
582 bits = _bits;
583 }
584
585 ~TraceSuspendDebugBits() {
586 if (!is_wait) {
587 #if 1
588 // By default, don't trace bits for is_ext_suspend_completed() calls.
589 // That trace is very chatty.
590 return;
591 #else
592 if (!called_by_wait) {
593 // If tracing for is_ext_suspend_completed() is enabled, then only
594 // trace calls to it from wait_for_ext_suspend_completion()
595 return;
596 }
597 #endif
598 }
599
600 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
601 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
602 MutexLocker ml(Threads_lock); // needed for get_thread_name()
603 ResourceMark rm;
604
605 tty->print_cr(
606 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
607 jt->get_thread_name(), *bits);
608
609 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
610 }
611 }
612 }
613 };
614 #undef DEBUG_FALSE_BITS
615
616
617 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
618 uint32_t *bits) {
619 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
620
621 bool did_trans_retry = false; // only do thread_in_native_trans retry once
622 bool do_trans_retry; // flag to force the retry
623
624 *bits |= 0x00000001;
625
626 do {
627 do_trans_retry = false;
628
629 if (is_exiting()) {
630 // Thread is in the process of exiting. This is always checked
631 // first to reduce the risk of dereferencing a freed JavaThread.
632 *bits |= 0x00000100;
633 return false;
634 }
635
636 if (!is_external_suspend()) {
637 // Suspend request is cancelled. This is always checked before
638 // is_ext_suspended() to reduce the risk of a rogue resume
639 // confusing the thread that made the suspend request.
640 *bits |= 0x00000200;
641 return false;
642 }
643
644 if (is_ext_suspended()) {
645 // thread is suspended
646 *bits |= 0x00000400;
647 return true;
648 }
649
650 // Now that we no longer do hard suspends of threads running
651 // native code, the target thread can be changing thread state
652 // while we are in this routine:
653 //
654 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
655 //
656 // We save a copy of the thread state as observed at this moment
657 // and make our decision about suspend completeness based on the
658 // copy. This closes the race where the thread state is seen as
659 // _thread_in_native_trans in the if-thread_blocked check, but is
660 // seen as _thread_blocked in if-thread_in_native_trans check.
661 JavaThreadState save_state = thread_state();
662
663 if (save_state == _thread_blocked && is_suspend_equivalent()) {
664 // If the thread's state is _thread_blocked and this blocking
665 // condition is known to be equivalent to a suspend, then we can
666 // consider the thread to be externally suspended. This means that
667 // the code that sets _thread_blocked has been modified to do
668 // self-suspension if the blocking condition releases. We also
669 // used to check for CONDVAR_WAIT here, but that is now covered by
670 // the _thread_blocked with self-suspension check.
671 //
672 // Return true since we wouldn't be here unless there was still an
673 // external suspend request.
674 *bits |= 0x00001000;
675 return true;
676 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
677 // Threads running native code will self-suspend on native==>VM/Java
678 // transitions. If its stack is walkable (should always be the case
679 // unless this function is called before the actual java_suspend()
680 // call), then the wait is done.
681 *bits |= 0x00002000;
682 return true;
683 } else if (!called_by_wait && !did_trans_retry &&
684 save_state == _thread_in_native_trans &&
685 frame_anchor()->walkable()) {
686 // The thread is transitioning from thread_in_native to another
687 // thread state. check_safepoint_and_suspend_for_native_trans()
688 // will force the thread to self-suspend. If it hasn't gotten
689 // there yet we may have caught the thread in-between the native
690 // code check above and the self-suspend. Lucky us. If we were
691 // called by wait_for_ext_suspend_completion(), then it
692 // will be doing the retries so we don't have to.
693 //
694 // Since we use the saved thread state in the if-statement above,
695 // there is a chance that the thread has already transitioned to
696 // _thread_blocked by the time we get here. In that case, we will
697 // make a single unnecessary pass through the logic below. This
698 // doesn't hurt anything since we still do the trans retry.
699
700 *bits |= 0x00004000;
701
702 // Once the thread leaves thread_in_native_trans for another
703 // thread state, we break out of this retry loop. We shouldn't
704 // need this flag to prevent us from getting back here, but
705 // sometimes paranoia is good.
706 did_trans_retry = true;
707
708 // We wait for the thread to transition to a more usable state.
709 for (int i = 1; i <= SuspendRetryCount; i++) {
710 // We used to do an "os::yield_all(i)" call here with the intention
711 // that yielding would increase on each retry. However, the parameter
712 // is ignored on Linux which means the yield didn't scale up. Waiting
713 // on the SR_lock below provides a much more predictable scale up for
714 // the delay. It also provides a simple/direct point to check for any
715 // safepoint requests from the VMThread
716
717 // temporarily drops SR_lock while doing wait with safepoint check
718 // (if we're a JavaThread - the WatcherThread can also call this)
719 // and increase delay with each retry
720 if (Thread::current()->is_Java_thread()) {
721 SR_lock()->wait(i * delay);
722 } else {
723 SR_lock()->wait_without_safepoint_check(i * delay);
724 }
725
726 // check the actual thread state instead of what we saved above
727 if (thread_state() != _thread_in_native_trans) {
728 // the thread has transitioned to another thread state so
729 // try all the checks (except this one) one more time.
730 do_trans_retry = true;
731 break;
732 }
733 } // end retry loop
734
735
736 }
737 } while (do_trans_retry);
738
739 *bits |= 0x00000010;
740 return false;
741 }
742
743 // Wait for an external suspend request to complete (or be cancelled).
744 // Returns true if the thread is externally suspended and false otherwise.
745 //
746 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
747 uint32_t *bits) {
748 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
749 false /* !called_by_wait */, bits);
750
751 // local flag copies to minimize SR_lock hold time
752 bool is_suspended;
753 bool pending;
754 uint32_t reset_bits;
755
756 // set a marker so is_ext_suspend_completed() knows we are the caller
757 *bits |= 0x00010000;
758
759 // We use reset_bits to reinitialize the bits value at the top of
760 // each retry loop. This allows the caller to make use of any
761 // unused bits for their own marking purposes.
762 reset_bits = *bits;
763
764 {
765 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
766 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
767 delay, bits);
768 pending = is_external_suspend();
769 }
770 // must release SR_lock to allow suspension to complete
771
772 if (!pending) {
773 // A cancelled suspend request is the only false return from
774 // is_ext_suspend_completed() that keeps us from entering the
775 // retry loop.
776 *bits |= 0x00020000;
777 return false;
778 }
779
780 if (is_suspended) {
781 *bits |= 0x00040000;
782 return true;
783 }
784
785 for (int i = 1; i <= retries; i++) {
786 *bits = reset_bits; // reinit to only track last retry
787
788 // We used to do an "os::yield_all(i)" call here with the intention
789 // that yielding would increase on each retry. However, the parameter
790 // is ignored on Linux which means the yield didn't scale up. Waiting
791 // on the SR_lock below provides a much more predictable scale up for
792 // the delay. It also provides a simple/direct point to check for any
793 // safepoint requests from the VMThread
794
795 {
796 Thread* t = Thread::current();
797 MonitorLocker ml(SR_lock(),
798 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
799 // wait with safepoint check (if we're a JavaThread - the WatcherThread
800 // can also call this) and increase delay with each retry
801 ml.wait(i * delay);
802
803 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
804 delay, bits);
805
806 // It is possible for the external suspend request to be cancelled
807 // (by a resume) before the actual suspend operation is completed.
808 // Refresh our local copy to see if we still need to wait.
809 pending = is_external_suspend();
810 }
811
812 if (!pending) {
813 // A cancelled suspend request is the only false return from
814 // is_ext_suspend_completed() that keeps us from staying in the
815 // retry loop.
816 *bits |= 0x00080000;
817 return false;
818 }
819
820 if (is_suspended) {
821 *bits |= 0x00100000;
822 return true;
823 }
824 } // end retry loop
825
826 // thread did not suspend after all our retries
827 *bits |= 0x00200000;
828 return false;
829 }
830
831 // Called from API entry points which perform stack walking. If the
832 // associated JavaThread is the current thread, then wait_for_suspend
833 // is not used. Otherwise, it determines if we should wait for the
834 // "other" thread to complete external suspension. (NOTE: in future
835 // releases the suspension mechanism should be reimplemented so this
836 // is not necessary.)
837 //
838 bool
839 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
840 if (this != JavaThread::current()) {
841 // "other" threads require special handling.
842 if (wait_for_suspend) {
843 // We are allowed to wait for the external suspend to complete
844 // so give the other thread a chance to get suspended.
845 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
846 SuspendRetryDelay, bits)) {
847 // Didn't make it so let the caller know.
848 return false;
849 }
850 }
851 // We aren't allowed to wait for the external suspend to complete
852 // so if the other thread isn't externally suspended we need to
853 // let the caller know.
854 else if (!is_ext_suspend_completed_with_lock(bits)) {
855 return false;
856 }
857 }
858
859 return true;
860 }
861
862 #ifndef PRODUCT
863 void JavaThread::record_jump(address target, address instr, const char* file,
864 int line) {
865
866 // This should not need to be atomic as the only way for simultaneous
867 // updates is via interrupts. Even then this should be rare or non-existent
868 // and we don't care that much anyway.
869
870 int index = _jmp_ring_index;
871 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
872 _jmp_ring[index]._target = (intptr_t) target;
873 _jmp_ring[index]._instruction = (intptr_t) instr;
874 _jmp_ring[index]._file = file;
875 _jmp_ring[index]._line = line;
876 }
877 #endif // PRODUCT
878
879 void Thread::interrupt(Thread* thread) {
880 debug_only(check_for_dangling_thread_pointer(thread);)
881 os::interrupt(thread);
882 }
883
884 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
885 debug_only(check_for_dangling_thread_pointer(thread);)
886 // Note: If clear_interrupted==false, this simply fetches and
887 // returns the value of the field osthread()->interrupted().
888 return os::is_interrupted(thread, clear_interrupted);
889 }
890
891
892 // GC Support
893 bool Thread::claim_par_threads_do(uintx claim_token) {
894 uintx token = _threads_do_token;
895 if (token != claim_token) {
896 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
897 if (res == token) {
898 return true;
899 }
900 guarantee(res == claim_token, "invariant");
901 }
902 return false;
903 }
904
905 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
906 active_handles()->oops_do(f);
907 // Do oop for ThreadShadow
908 f->do_oop((oop*)&_pending_exception);
909 handle_area()->oops_do(f);
910
911 // We scan thread local monitor lists here, and the remaining global
912 // monitors in ObjectSynchronizer::oops_do().
913 ObjectSynchronizer::thread_local_used_oops_do(this, f);
914 }
915
916 void Thread::metadata_handles_do(void f(Metadata*)) {
917 // Only walk the Handles in Thread.
918 if (metadata_handles() != NULL) {
919 for (int i = 0; i< metadata_handles()->length(); i++) {
920 f(metadata_handles()->at(i));
921 }
922 }
923 }
924
925 void Thread::print_on(outputStream* st, bool print_extended_info) const {
926 // get_priority assumes osthread initialized
927 if (osthread() != NULL) {
928 int os_prio;
929 if (os::get_native_priority(this, &os_prio) == OS_OK) {
930 st->print("os_prio=%d ", os_prio);
931 }
932
933 st->print("cpu=%.2fms ",
934 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
935 );
936 st->print("elapsed=%.2fs ",
937 _statistical_info.getElapsedTime() / 1000.0
938 );
939 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
940 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
941 st->print("allocated=" SIZE_FORMAT "%s ",
942 byte_size_in_proper_unit(allocated_bytes),
943 proper_unit_for_byte_size(allocated_bytes)
944 );
945 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
946 }
947
948 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
949 osthread()->print_on(st);
950 }
951 ThreadsSMRSupport::print_info_on(this, st);
952 st->print(" ");
953 debug_only(if (WizardMode) print_owned_locks_on(st);)
954 }
955
956 // Thread::print_on_error() is called by fatal error handler. Don't use
957 // any lock or allocate memory.
958 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
959 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
960
961 if (is_VM_thread()) { st->print("VMThread"); }
962 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
963 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
964 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
965 else { st->print("Thread"); }
966
967 if (is_Named_thread()) {
968 st->print(" \"%s\"", name());
969 }
970
971 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
972 p2i(stack_end()), p2i(stack_base()));
973
974 if (osthread()) {
975 st->print(" [id=%d]", osthread()->thread_id());
976 }
977
978 ThreadsSMRSupport::print_info_on(this, st);
979 }
980
981 void Thread::print_value_on(outputStream* st) const {
982 if (is_Named_thread()) {
983 st->print(" \"%s\" ", name());
984 }
985 st->print(INTPTR_FORMAT, p2i(this)); // print address
986 }
987
988 #ifdef ASSERT
989 void Thread::print_owned_locks_on(outputStream* st) const {
990 Monitor *cur = _owned_locks;
991 if (cur == NULL) {
992 st->print(" (no locks) ");
993 } else {
994 st->print_cr(" Locks owned:");
995 while (cur) {
996 cur->print_on(st);
997 cur = cur->next();
998 }
999 }
1000 }
1001
1002 static int ref_use_count = 0;
1003
1004 bool Thread::owns_locks_but_compiled_lock() const {
1005 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1006 if (cur != Compile_lock) return true;
1007 }
1008 return false;
1009 }
1010
1011
1012 #endif
1013
1014 #ifndef PRODUCT
1015
1016 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1017 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1018 // no locks which allow_vm_block's are held
1019 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1020 // Check if current thread is allowed to block at a safepoint
1021 if (!(_allow_safepoint_count == 0)) {
1022 fatal("Possible safepoint reached by thread that does not allow it");
1023 }
1024 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1025 fatal("LEAF method calling lock?");
1026 }
1027
1028 #ifdef ASSERT
1029 if (potential_vm_operation && is_Java_thread()
1030 && !Universe::is_bootstrapping()) {
1031 // Make sure we do not hold any locks that the VM thread also uses.
1032 // This could potentially lead to deadlocks
1033 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1034 // Threads_lock is special, since the safepoint synchronization will not start before this is
1035 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1036 // since it is used to transfer control between JavaThreads and the VMThread
1037 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1038 if ((cur->allow_vm_block() &&
1039 cur != Threads_lock &&
1040 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1041 cur != VMOperationRequest_lock &&
1042 cur != VMOperationQueue_lock) ||
1043 cur->rank() == Mutex::special) {
1044 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1045 }
1046 }
1047 }
1048
1049 if (GCALotAtAllSafepoints) {
1050 // We could enter a safepoint here and thus have a gc
1051 InterfaceSupport::check_gc_alot();
1052 }
1053 #endif
1054 }
1055 #endif
1056
1057 bool Thread::is_in_stack(address adr) const {
1058 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1059 address end = os::current_stack_pointer();
1060 // Allow non Java threads to call this without stack_base
1061 if (_stack_base == NULL) return true;
1062 if (stack_base() >= adr && adr >= end) return true;
1063
1064 return false;
1065 }
1066
1067 bool Thread::is_in_usable_stack(address adr) const {
1068 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1069 size_t usable_stack_size = _stack_size - stack_guard_size;
1070
1071 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1072 }
1073
1074
1075 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1076 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1077 // used for compilation in the future. If that change is made, the need for these methods
1078 // should be revisited, and they should be removed if possible.
1079
1080 bool Thread::is_lock_owned(address adr) const {
1081 return on_local_stack(adr);
1082 }
1083
1084 bool Thread::set_as_starting_thread() {
1085 assert(_starting_thread == NULL, "already initialized: "
1086 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1087 // NOTE: this must be called inside the main thread.
1088 DEBUG_ONLY(_starting_thread = this;)
1089 return os::create_main_thread((JavaThread*)this);
1090 }
1091
1092 static void initialize_class(Symbol* class_name, TRAPS) {
1093 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1094 InstanceKlass::cast(klass)->initialize(CHECK);
1095 }
1096
1097
1098 // Creates the initial ThreadGroup
1099 static Handle create_initial_thread_group(TRAPS) {
1100 Handle system_instance = JavaCalls::construct_new_instance(
1101 SystemDictionary::ThreadGroup_klass(),
1102 vmSymbols::void_method_signature(),
1103 CHECK_NH);
1104 Universe::set_system_thread_group(system_instance());
1105
1106 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1107 Handle main_instance = JavaCalls::construct_new_instance(
1108 SystemDictionary::ThreadGroup_klass(),
1109 vmSymbols::threadgroup_string_void_signature(),
1110 system_instance,
1111 string,
1112 CHECK_NH);
1113 return main_instance;
1114 }
1115
1116 // Creates the initial Thread
1117 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1118 TRAPS) {
1119 InstanceKlass* ik = SystemDictionary::Thread_klass();
1120 assert(ik->is_initialized(), "must be");
1121 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1122
1123 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1124 // constructor calls Thread.current(), which must be set here for the
1125 // initial thread.
1126 java_lang_Thread::set_thread(thread_oop(), thread);
1127 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1128 thread->set_threadObj(thread_oop());
1129
1130 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1131
1132 JavaValue result(T_VOID);
1133 JavaCalls::call_special(&result, thread_oop,
1134 ik,
1135 vmSymbols::object_initializer_name(),
1136 vmSymbols::threadgroup_string_void_signature(),
1137 thread_group,
1138 string,
1139 CHECK_NULL);
1140 return thread_oop();
1141 }
1142
1143 char java_runtime_name[128] = "";
1144 char java_runtime_version[128] = "";
1145
1146 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1147 static const char* get_java_runtime_name(TRAPS) {
1148 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1149 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1150 fieldDescriptor fd;
1151 bool found = k != NULL &&
1152 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1153 vmSymbols::string_signature(), &fd);
1154 if (found) {
1155 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1156 if (name_oop == NULL) {
1157 return NULL;
1158 }
1159 const char* name = java_lang_String::as_utf8_string(name_oop,
1160 java_runtime_name,
1161 sizeof(java_runtime_name));
1162 return name;
1163 } else {
1164 return NULL;
1165 }
1166 }
1167
1168 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1169 static const char* get_java_runtime_version(TRAPS) {
1170 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1171 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1172 fieldDescriptor fd;
1173 bool found = k != NULL &&
1174 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1175 vmSymbols::string_signature(), &fd);
1176 if (found) {
1177 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1178 if (name_oop == NULL) {
1179 return NULL;
1180 }
1181 const char* name = java_lang_String::as_utf8_string(name_oop,
1182 java_runtime_version,
1183 sizeof(java_runtime_version));
1184 return name;
1185 } else {
1186 return NULL;
1187 }
1188 }
1189
1190 // General purpose hook into Java code, run once when the VM is initialized.
1191 // The Java library method itself may be changed independently from the VM.
1192 static void call_postVMInitHook(TRAPS) {
1193 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1194 if (klass != NULL) {
1195 JavaValue result(T_VOID);
1196 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1197 vmSymbols::void_method_signature(),
1198 CHECK);
1199 }
1200 }
1201
1202 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1203 bool daemon, TRAPS) {
1204 assert(thread_group.not_null(), "thread group should be specified");
1205 assert(threadObj() == NULL, "should only create Java thread object once");
1206
1207 InstanceKlass* ik = SystemDictionary::Thread_klass();
1208 assert(ik->is_initialized(), "must be");
1209 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1210
1211 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1212 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1213 // constructor calls Thread.current(), which must be set here.
1214 java_lang_Thread::set_thread(thread_oop(), this);
1215 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1216 set_threadObj(thread_oop());
1217
1218 JavaValue result(T_VOID);
1219 if (thread_name != NULL) {
1220 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1221 // Thread gets assigned specified name and null target
1222 JavaCalls::call_special(&result,
1223 thread_oop,
1224 ik,
1225 vmSymbols::object_initializer_name(),
1226 vmSymbols::threadgroup_string_void_signature(),
1227 thread_group,
1228 name,
1229 THREAD);
1230 } else {
1231 // Thread gets assigned name "Thread-nnn" and null target
1232 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1233 JavaCalls::call_special(&result,
1234 thread_oop,
1235 ik,
1236 vmSymbols::object_initializer_name(),
1237 vmSymbols::threadgroup_runnable_void_signature(),
1238 thread_group,
1239 Handle(),
1240 THREAD);
1241 }
1242
1243
1244 if (daemon) {
1245 java_lang_Thread::set_daemon(thread_oop());
1246 }
1247
1248 if (HAS_PENDING_EXCEPTION) {
1249 return;
1250 }
1251
1252 Klass* group = SystemDictionary::ThreadGroup_klass();
1253 Handle threadObj(THREAD, this->threadObj());
1254
1255 JavaCalls::call_special(&result,
1256 thread_group,
1257 group,
1258 vmSymbols::add_method_name(),
1259 vmSymbols::thread_void_signature(),
1260 threadObj, // Arg 1
1261 THREAD);
1262 }
1263
1264 // List of all NonJavaThreads and safe iteration over that list.
1265
1266 class NonJavaThread::List {
1267 public:
1268 NonJavaThread* volatile _head;
1269 SingleWriterSynchronizer _protect;
1270
1271 List() : _head(NULL), _protect() {}
1272 };
1273
1274 NonJavaThread::List NonJavaThread::_the_list;
1275
1276 NonJavaThread::Iterator::Iterator() :
1277 _protect_enter(_the_list._protect.enter()),
1278 _current(OrderAccess::load_acquire(&_the_list._head))
1279 {}
1280
1281 NonJavaThread::Iterator::~Iterator() {
1282 _the_list._protect.exit(_protect_enter);
1283 }
1284
1285 void NonJavaThread::Iterator::step() {
1286 assert(!end(), "precondition");
1287 _current = OrderAccess::load_acquire(&_current->_next);
1288 }
1289
1290 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1291 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1292 }
1293
1294 NonJavaThread::~NonJavaThread() { }
1295
1296 void NonJavaThread::add_to_the_list() {
1297 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1298 // Initialize BarrierSet-related data before adding to list.
1299 BarrierSet::barrier_set()->on_thread_attach(this);
1300 OrderAccess::release_store(&_next, _the_list._head);
1301 OrderAccess::release_store(&_the_list._head, this);
1302 }
1303
1304 void NonJavaThread::remove_from_the_list() {
1305 {
1306 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1307 // Cleanup BarrierSet-related data before removing from list.
1308 BarrierSet::barrier_set()->on_thread_detach(this);
1309 NonJavaThread* volatile* p = &_the_list._head;
1310 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1311 if (t == this) {
1312 *p = _next;
1313 break;
1314 }
1315 }
1316 }
1317 // Wait for any in-progress iterators. Concurrent synchronize is not
1318 // allowed, so do it while holding a dedicated lock. Outside and distinct
1319 // from NJTList_lock in case an iteration attempts to lock it.
1320 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1321 _the_list._protect.synchronize();
1322 _next = NULL; // Safe to drop the link now.
1323 }
1324
1325 void NonJavaThread::pre_run() {
1326 add_to_the_list();
1327
1328 // This is slightly odd in that NamedThread is a subclass, but
1329 // in fact name() is defined in Thread
1330 assert(this->name() != NULL, "thread name was not set before it was started");
1331 this->set_native_thread_name(this->name());
1332 }
1333
1334 void NonJavaThread::post_run() {
1335 JFR_ONLY(Jfr::on_thread_exit(this);)
1336 remove_from_the_list();
1337 // Ensure thread-local-storage is cleared before termination.
1338 Thread::clear_thread_current();
1339 }
1340
1341 // NamedThread -- non-JavaThread subclasses with multiple
1342 // uniquely named instances should derive from this.
1343 NamedThread::NamedThread() :
1344 NonJavaThread(),
1345 _name(NULL),
1346 _processed_thread(NULL),
1347 _gc_id(GCId::undefined())
1348 {}
1349
1350 NamedThread::~NamedThread() {
1351 if (_name != NULL) {
1352 FREE_C_HEAP_ARRAY(char, _name);
1353 _name = NULL;
1354 }
1355 }
1356
1357 void NamedThread::set_name(const char* format, ...) {
1358 guarantee(_name == NULL, "Only get to set name once.");
1359 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1360 guarantee(_name != NULL, "alloc failure");
1361 va_list ap;
1362 va_start(ap, format);
1363 jio_vsnprintf(_name, max_name_len, format, ap);
1364 va_end(ap);
1365 }
1366
1367 void NamedThread::print_on(outputStream* st) const {
1368 st->print("\"%s\" ", name());
1369 Thread::print_on(st);
1370 st->cr();
1371 }
1372
1373
1374 // ======= WatcherThread ========
1375
1376 // The watcher thread exists to simulate timer interrupts. It should
1377 // be replaced by an abstraction over whatever native support for
1378 // timer interrupts exists on the platform.
1379
1380 WatcherThread* WatcherThread::_watcher_thread = NULL;
1381 bool WatcherThread::_startable = false;
1382 volatile bool WatcherThread::_should_terminate = false;
1383
1384 WatcherThread::WatcherThread() : NonJavaThread() {
1385 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1386 if (os::create_thread(this, os::watcher_thread)) {
1387 _watcher_thread = this;
1388
1389 // Set the watcher thread to the highest OS priority which should not be
1390 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1391 // is created. The only normal thread using this priority is the reference
1392 // handler thread, which runs for very short intervals only.
1393 // If the VMThread's priority is not lower than the WatcherThread profiling
1394 // will be inaccurate.
1395 os::set_priority(this, MaxPriority);
1396 if (!DisableStartThread) {
1397 os::start_thread(this);
1398 }
1399 }
1400 }
1401
1402 int WatcherThread::sleep() const {
1403 // The WatcherThread does not participate in the safepoint protocol
1404 // for the PeriodicTask_lock because it is not a JavaThread.
1405 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1406
1407 if (_should_terminate) {
1408 // check for termination before we do any housekeeping or wait
1409 return 0; // we did not sleep.
1410 }
1411
1412 // remaining will be zero if there are no tasks,
1413 // causing the WatcherThread to sleep until a task is
1414 // enrolled
1415 int remaining = PeriodicTask::time_to_wait();
1416 int time_slept = 0;
1417
1418 // we expect this to timeout - we only ever get unparked when
1419 // we should terminate or when a new task has been enrolled
1420 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1421
1422 jlong time_before_loop = os::javaTimeNanos();
1423
1424 while (true) {
1425 bool timedout = ml.wait(remaining);
1426 jlong now = os::javaTimeNanos();
1427
1428 if (remaining == 0) {
1429 // if we didn't have any tasks we could have waited for a long time
1430 // consider the time_slept zero and reset time_before_loop
1431 time_slept = 0;
1432 time_before_loop = now;
1433 } else {
1434 // need to recalculate since we might have new tasks in _tasks
1435 time_slept = (int) ((now - time_before_loop) / 1000000);
1436 }
1437
1438 // Change to task list or spurious wakeup of some kind
1439 if (timedout || _should_terminate) {
1440 break;
1441 }
1442
1443 remaining = PeriodicTask::time_to_wait();
1444 if (remaining == 0) {
1445 // Last task was just disenrolled so loop around and wait until
1446 // another task gets enrolled
1447 continue;
1448 }
1449
1450 remaining -= time_slept;
1451 if (remaining <= 0) {
1452 break;
1453 }
1454 }
1455
1456 return time_slept;
1457 }
1458
1459 void WatcherThread::run() {
1460 assert(this == watcher_thread(), "just checking");
1461
1462 this->set_active_handles(JNIHandleBlock::allocate_block());
1463 while (true) {
1464 assert(watcher_thread() == Thread::current(), "thread consistency check");
1465 assert(watcher_thread() == this, "thread consistency check");
1466
1467 // Calculate how long it'll be until the next PeriodicTask work
1468 // should be done, and sleep that amount of time.
1469 int time_waited = sleep();
1470
1471 if (VMError::is_error_reported()) {
1472 // A fatal error has happened, the error handler(VMError::report_and_die)
1473 // should abort JVM after creating an error log file. However in some
1474 // rare cases, the error handler itself might deadlock. Here periodically
1475 // check for error reporting timeouts, and if it happens, just proceed to
1476 // abort the VM.
1477
1478 // This code is in WatcherThread because WatcherThread wakes up
1479 // periodically so the fatal error handler doesn't need to do anything;
1480 // also because the WatcherThread is less likely to crash than other
1481 // threads.
1482
1483 for (;;) {
1484 // Note: we use naked sleep in this loop because we want to avoid using
1485 // any kind of VM infrastructure which may be broken at this point.
1486 if (VMError::check_timeout()) {
1487 // We hit error reporting timeout. Error reporting was interrupted and
1488 // will be wrapping things up now (closing files etc). Give it some more
1489 // time, then quit the VM.
1490 os::naked_short_sleep(200);
1491 // Print a message to stderr.
1492 fdStream err(defaultStream::output_fd());
1493 err.print_raw_cr("# [ timer expired, abort... ]");
1494 // skip atexit/vm_exit/vm_abort hooks
1495 os::die();
1496 }
1497
1498 // Wait a second, then recheck for timeout.
1499 os::naked_short_sleep(999);
1500 }
1501 }
1502
1503 if (_should_terminate) {
1504 // check for termination before posting the next tick
1505 break;
1506 }
1507
1508 PeriodicTask::real_time_tick(time_waited);
1509 }
1510
1511 // Signal that it is terminated
1512 {
1513 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1514 _watcher_thread = NULL;
1515 Terminator_lock->notify_all();
1516 }
1517 }
1518
1519 void WatcherThread::start() {
1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1521
1522 if (watcher_thread() == NULL && _startable) {
1523 _should_terminate = false;
1524 // Create the single instance of WatcherThread
1525 new WatcherThread();
1526 }
1527 }
1528
1529 void WatcherThread::make_startable() {
1530 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1531 _startable = true;
1532 }
1533
1534 void WatcherThread::stop() {
1535 {
1536 // Follow normal safepoint aware lock enter protocol since the
1537 // WatcherThread is stopped by another JavaThread.
1538 MutexLocker ml(PeriodicTask_lock);
1539 _should_terminate = true;
1540
1541 WatcherThread* watcher = watcher_thread();
1542 if (watcher != NULL) {
1543 // unpark the WatcherThread so it can see that it should terminate
1544 watcher->unpark();
1545 }
1546 }
1547
1548 MonitorLocker mu(Terminator_lock);
1549
1550 while (watcher_thread() != NULL) {
1551 // This wait should make safepoint checks, wait without a timeout,
1552 // and wait as a suspend-equivalent condition.
1553 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1554 }
1555 }
1556
1557 void WatcherThread::unpark() {
1558 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1559 PeriodicTask_lock->notify();
1560 }
1561
1562 void WatcherThread::print_on(outputStream* st) const {
1563 st->print("\"%s\" ", name());
1564 Thread::print_on(st);
1565 st->cr();
1566 }
1567
1568 // ======= JavaThread ========
1569
1570 #if INCLUDE_JVMCI
1571
1572 jlong* JavaThread::_jvmci_old_thread_counters;
1573
1574 bool jvmci_counters_include(JavaThread* thread) {
1575 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1576 }
1577
1578 void JavaThread::collect_counters(JVMCIEnv* jvmci_env, JVMCIPrimitiveArray array) {
1579 if (JVMCICounterSize > 0) {
1580 JavaThreadIteratorWithHandle jtiwh;
1581 int len = jvmci_env->get_length(array);
1582 for (int i = 0; i < len; i++) {
1583 jvmci_env->put_long_at(array, i, _jvmci_old_thread_counters[i]);
1584 }
1585 for (; JavaThread *tp = jtiwh.next(); ) {
1586 if (jvmci_counters_include(tp)) {
1587 for (int i = 0; i < len; i++) {
1588 jvmci_env->put_long_at(array, i, jvmci_env->get_long_at(array, i) + tp->_jvmci_counters[i]);
1589 }
1590 }
1591 }
1592 }
1593 }
1594
1595 #endif // INCLUDE_JVMCI
1596
1597 // A JavaThread is a normal Java thread
1598
1599 void JavaThread::initialize() {
1600 // Initialize fields
1601
1602 set_saved_exception_pc(NULL);
1603 set_threadObj(NULL);
1604 _anchor.clear();
1605 set_entry_point(NULL);
1606 set_jni_functions(jni_functions());
1607 set_callee_target(NULL);
1608 set_vm_result(NULL);
1609 set_vm_result_2(NULL);
1610 set_vframe_array_head(NULL);
1611 set_vframe_array_last(NULL);
1612 set_deferred_locals(NULL);
1613 set_deopt_mark(NULL);
1614 set_deopt_compiled_method(NULL);
1615 clear_must_deopt_id();
1616 set_monitor_chunks(NULL);
1617 set_next(NULL);
1618 _on_thread_list = false;
1619 set_thread_state(_thread_new);
1620 _terminated = _not_terminated;
1621 _array_for_gc = NULL;
1622 _suspend_equivalent = false;
1623 _in_deopt_handler = 0;
1624 _doing_unsafe_access = false;
1625 _stack_guard_state = stack_guard_unused;
1626 #if INCLUDE_JVMCI
1627 _pending_monitorenter = false;
1628 _pending_deoptimization = -1;
1629 _pending_failed_speculation = 0;
1630 _pending_transfer_to_interpreter = false;
1631 _in_retryable_allocation = false;
1632 _jvmci._alternate_call_target = NULL;
1633 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1634 if (JVMCICounterSize > 0) {
1635 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1636 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1637 } else {
1638 _jvmci_counters = NULL;
1639 }
1640 #endif // INCLUDE_JVMCI
1641 _reserved_stack_activation = NULL; // stack base not known yet
1642 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1643 _exception_pc = 0;
1644 _exception_handler_pc = 0;
1645 _is_method_handle_return = 0;
1646 _jvmti_thread_state= NULL;
1647 _should_post_on_exceptions_flag = JNI_FALSE;
1648 _interp_only_mode = 0;
1649 _special_runtime_exit_condition = _no_async_condition;
1650 _pending_async_exception = NULL;
1651 _thread_stat = NULL;
1652 _thread_stat = new ThreadStatistics();
1653 _blocked_on_compilation = false;
1654 _jni_active_critical = 0;
1655 _pending_jni_exception_check_fn = NULL;
1656 _do_not_unlock_if_synchronized = false;
1657 _cached_monitor_info = NULL;
1658 _parker = Parker::Allocate(this);
1659
1660 #ifndef PRODUCT
1661 _jmp_ring_index = 0;
1662 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1663 record_jump(NULL, NULL, NULL, 0);
1664 }
1665 #endif // PRODUCT
1666
1667 // Setup safepoint state info for this thread
1668 ThreadSafepointState::create(this);
1669
1670 debug_only(_java_call_counter = 0);
1671
1672 // JVMTI PopFrame support
1673 _popframe_condition = popframe_inactive;
1674 _popframe_preserved_args = NULL;
1675 _popframe_preserved_args_size = 0;
1676 _frames_to_pop_failed_realloc = 0;
1677
1678 if (SafepointMechanism::uses_thread_local_poll()) {
1679 SafepointMechanism::initialize_header(this);
1680 }
1681
1682 _class_to_be_initialized = NULL;
1683
1684 pd_initialize();
1685 }
1686
1687 JavaThread::JavaThread(bool is_attaching_via_jni) :
1688 Thread() {
1689 initialize();
1690 if (is_attaching_via_jni) {
1691 _jni_attach_state = _attaching_via_jni;
1692 } else {
1693 _jni_attach_state = _not_attaching_via_jni;
1694 }
1695 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1696 }
1697
1698 bool JavaThread::reguard_stack(address cur_sp) {
1699 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1700 && _stack_guard_state != stack_guard_reserved_disabled) {
1701 return true; // Stack already guarded or guard pages not needed.
1702 }
1703
1704 if (register_stack_overflow()) {
1705 // For those architectures which have separate register and
1706 // memory stacks, we must check the register stack to see if
1707 // it has overflowed.
1708 return false;
1709 }
1710
1711 // Java code never executes within the yellow zone: the latter is only
1712 // there to provoke an exception during stack banging. If java code
1713 // is executing there, either StackShadowPages should be larger, or
1714 // some exception code in c1, c2 or the interpreter isn't unwinding
1715 // when it should.
1716 guarantee(cur_sp > stack_reserved_zone_base(),
1717 "not enough space to reguard - increase StackShadowPages");
1718 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1719 enable_stack_yellow_reserved_zone();
1720 if (reserved_stack_activation() != stack_base()) {
1721 set_reserved_stack_activation(stack_base());
1722 }
1723 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1724 set_reserved_stack_activation(stack_base());
1725 enable_stack_reserved_zone();
1726 }
1727 return true;
1728 }
1729
1730 bool JavaThread::reguard_stack(void) {
1731 return reguard_stack(os::current_stack_pointer());
1732 }
1733
1734
1735 void JavaThread::block_if_vm_exited() {
1736 if (_terminated == _vm_exited) {
1737 // _vm_exited is set at safepoint, and Threads_lock is never released
1738 // we will block here forever
1739 Threads_lock->lock_without_safepoint_check();
1740 ShouldNotReachHere();
1741 }
1742 }
1743
1744
1745 // Remove this ifdef when C1 is ported to the compiler interface.
1746 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1747 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1748
1749 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1750 Thread() {
1751 initialize();
1752 _jni_attach_state = _not_attaching_via_jni;
1753 set_entry_point(entry_point);
1754 // Create the native thread itself.
1755 // %note runtime_23
1756 os::ThreadType thr_type = os::java_thread;
1757 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1758 os::java_thread;
1759 os::create_thread(this, thr_type, stack_sz);
1760 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1761 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1762 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1763 // the exception consists of creating the exception object & initializing it, initialization
1764 // will leave the VM via a JavaCall and then all locks must be unlocked).
1765 //
1766 // The thread is still suspended when we reach here. Thread must be explicit started
1767 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1768 // by calling Threads:add. The reason why this is not done here, is because the thread
1769 // object must be fully initialized (take a look at JVM_Start)
1770 }
1771
1772 JavaThread::~JavaThread() {
1773
1774 // JSR166 -- return the parker to the free list
1775 Parker::Release(_parker);
1776 _parker = NULL;
1777
1778 // Free any remaining previous UnrollBlock
1779 vframeArray* old_array = vframe_array_last();
1780
1781 if (old_array != NULL) {
1782 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1783 old_array->set_unroll_block(NULL);
1784 delete old_info;
1785 delete old_array;
1786 }
1787
1788 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1789 if (deferred != NULL) {
1790 // This can only happen if thread is destroyed before deoptimization occurs.
1791 assert(deferred->length() != 0, "empty array!");
1792 do {
1793 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1794 deferred->remove_at(0);
1795 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1796 delete dlv;
1797 } while (deferred->length() != 0);
1798 delete deferred;
1799 }
1800
1801 // All Java related clean up happens in exit
1802 ThreadSafepointState::destroy(this);
1803 if (_thread_stat != NULL) delete _thread_stat;
1804
1805 #if INCLUDE_JVMCI
1806 if (JVMCICounterSize > 0) {
1807 if (jvmci_counters_include(this)) {
1808 for (int i = 0; i < JVMCICounterSize; i++) {
1809 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1810 }
1811 }
1812 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1813 }
1814 #endif // INCLUDE_JVMCI
1815 }
1816
1817
1818 // First JavaThread specific code executed by a new Java thread.
1819 void JavaThread::pre_run() {
1820 // empty - see comments in run()
1821 }
1822
1823 // The main routine called by a new Java thread. This isn't overridden
1824 // by subclasses, instead different subclasses define a different "entry_point"
1825 // which defines the actual logic for that kind of thread.
1826 void JavaThread::run() {
1827 // initialize thread-local alloc buffer related fields
1828 this->initialize_tlab();
1829
1830 // Used to test validity of stack trace backs.
1831 // This can't be moved into pre_run() else we invalidate
1832 // the requirement that thread_main_inner is lower on
1833 // the stack. Consequently all the initialization logic
1834 // stays here in run() rather than pre_run().
1835 this->record_base_of_stack_pointer();
1836
1837 this->create_stack_guard_pages();
1838
1839 this->cache_global_variables();
1840
1841 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1842 // in the VM. Change thread state from _thread_new to _thread_in_vm
1843 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1844 // Before a thread is on the threads list it is always safe, so after leaving the
1845 // _thread_new we should emit a instruction barrier. The distance to modified code
1846 // from here is probably far enough, but this is consistent and safe.
1847 OrderAccess::cross_modify_fence();
1848
1849 assert(JavaThread::current() == this, "sanity check");
1850 assert(!Thread::current()->owns_locks(), "sanity check");
1851
1852 DTRACE_THREAD_PROBE(start, this);
1853
1854 // This operation might block. We call that after all safepoint checks for a new thread has
1855 // been completed.
1856 this->set_active_handles(JNIHandleBlock::allocate_block());
1857
1858 if (JvmtiExport::should_post_thread_life()) {
1859 JvmtiExport::post_thread_start(this);
1860
1861 }
1862
1863 // We call another function to do the rest so we are sure that the stack addresses used
1864 // from there will be lower than the stack base just computed.
1865 thread_main_inner();
1866 }
1867
1868 void JavaThread::thread_main_inner() {
1869 assert(JavaThread::current() == this, "sanity check");
1870 assert(this->threadObj() != NULL, "just checking");
1871
1872 // Execute thread entry point unless this thread has a pending exception
1873 // or has been stopped before starting.
1874 // Note: Due to JVM_StopThread we can have pending exceptions already!
1875 if (!this->has_pending_exception() &&
1876 !java_lang_Thread::is_stillborn(this->threadObj())) {
1877 {
1878 ResourceMark rm(this);
1879 this->set_native_thread_name(this->get_thread_name());
1880 }
1881 HandleMark hm(this);
1882 this->entry_point()(this, this);
1883 }
1884
1885 DTRACE_THREAD_PROBE(stop, this);
1886
1887 // Cleanup is handled in post_run()
1888 }
1889
1890 // Shared teardown for all JavaThreads
1891 void JavaThread::post_run() {
1892 this->exit(false);
1893 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1894 // for any shared tear-down.
1895 this->smr_delete();
1896 }
1897
1898 static void ensure_join(JavaThread* thread) {
1899 // We do not need to grab the Threads_lock, since we are operating on ourself.
1900 Handle threadObj(thread, thread->threadObj());
1901 assert(threadObj.not_null(), "java thread object must exist");
1902 ObjectLocker lock(threadObj, thread);
1903 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1904 thread->clear_pending_exception();
1905 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1906 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1907 // Clear the native thread instance - this makes isAlive return false and allows the join()
1908 // to complete once we've done the notify_all below
1909 java_lang_Thread::set_thread(threadObj(), NULL);
1910 lock.notify_all(thread);
1911 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1912 thread->clear_pending_exception();
1913 }
1914
1915 static bool is_daemon(oop threadObj) {
1916 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1917 }
1918
1919 // For any new cleanup additions, please check to see if they need to be applied to
1920 // cleanup_failed_attach_current_thread as well.
1921 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1922 assert(this == JavaThread::current(), "thread consistency check");
1923
1924 elapsedTimer _timer_exit_phase1;
1925 elapsedTimer _timer_exit_phase2;
1926 elapsedTimer _timer_exit_phase3;
1927 elapsedTimer _timer_exit_phase4;
1928
1929 if (log_is_enabled(Debug, os, thread, timer)) {
1930 _timer_exit_phase1.start();
1931 }
1932
1933 HandleMark hm(this);
1934 Handle uncaught_exception(this, this->pending_exception());
1935 this->clear_pending_exception();
1936 Handle threadObj(this, this->threadObj());
1937 assert(threadObj.not_null(), "Java thread object should be created");
1938
1939 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1940 {
1941 EXCEPTION_MARK;
1942
1943 CLEAR_PENDING_EXCEPTION;
1944 }
1945 if (!destroy_vm) {
1946 if (uncaught_exception.not_null()) {
1947 EXCEPTION_MARK;
1948 // Call method Thread.dispatchUncaughtException().
1949 Klass* thread_klass = SystemDictionary::Thread_klass();
1950 JavaValue result(T_VOID);
1951 JavaCalls::call_virtual(&result,
1952 threadObj, thread_klass,
1953 vmSymbols::dispatchUncaughtException_name(),
1954 vmSymbols::throwable_void_signature(),
1955 uncaught_exception,
1956 THREAD);
1957 if (HAS_PENDING_EXCEPTION) {
1958 ResourceMark rm(this);
1959 jio_fprintf(defaultStream::error_stream(),
1960 "\nException: %s thrown from the UncaughtExceptionHandler"
1961 " in thread \"%s\"\n",
1962 pending_exception()->klass()->external_name(),
1963 get_thread_name());
1964 CLEAR_PENDING_EXCEPTION;
1965 }
1966 }
1967 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1968
1969 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1970 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1971 // is deprecated anyhow.
1972 if (!is_Compiler_thread()) {
1973 int count = 3;
1974 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1975 EXCEPTION_MARK;
1976 JavaValue result(T_VOID);
1977 Klass* thread_klass = SystemDictionary::Thread_klass();
1978 JavaCalls::call_virtual(&result,
1979 threadObj, thread_klass,
1980 vmSymbols::exit_method_name(),
1981 vmSymbols::void_method_signature(),
1982 THREAD);
1983 CLEAR_PENDING_EXCEPTION;
1984 }
1985 }
1986 // notify JVMTI
1987 if (JvmtiExport::should_post_thread_life()) {
1988 JvmtiExport::post_thread_end(this);
1989 }
1990
1991 // We have notified the agents that we are exiting, before we go on,
1992 // we must check for a pending external suspend request and honor it
1993 // in order to not surprise the thread that made the suspend request.
1994 while (true) {
1995 {
1996 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1997 if (!is_external_suspend()) {
1998 set_terminated(_thread_exiting);
1999 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2000 break;
2001 }
2002 // Implied else:
2003 // Things get a little tricky here. We have a pending external
2004 // suspend request, but we are holding the SR_lock so we
2005 // can't just self-suspend. So we temporarily drop the lock
2006 // and then self-suspend.
2007 }
2008
2009 ThreadBlockInVM tbivm(this);
2010 java_suspend_self();
2011
2012 // We're done with this suspend request, but we have to loop around
2013 // and check again. Eventually we will get SR_lock without a pending
2014 // external suspend request and will be able to mark ourselves as
2015 // exiting.
2016 }
2017 // no more external suspends are allowed at this point
2018 } else {
2019 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2020 // before_exit() has already posted JVMTI THREAD_END events
2021 }
2022
2023 if (log_is_enabled(Debug, os, thread, timer)) {
2024 _timer_exit_phase1.stop();
2025 _timer_exit_phase2.start();
2026 }
2027
2028 // Capture daemon status before the thread is marked as terminated.
2029 bool daemon = is_daemon(threadObj());
2030
2031 // Notify waiters on thread object. This has to be done after exit() is called
2032 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2033 // group should have the destroyed bit set before waiters are notified).
2034 ensure_join(this);
2035 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2036
2037 if (log_is_enabled(Debug, os, thread, timer)) {
2038 _timer_exit_phase2.stop();
2039 _timer_exit_phase3.start();
2040 }
2041 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2042 // held by this thread must be released. The spec does not distinguish
2043 // between JNI-acquired and regular Java monitors. We can only see
2044 // regular Java monitors here if monitor enter-exit matching is broken.
2045 //
2046 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2047 // ObjectSynchronizer::release_monitors_owned_by_thread().
2048 if (exit_type == jni_detach) {
2049 // Sanity check even though JNI DetachCurrentThread() would have
2050 // returned JNI_ERR if there was a Java frame. JavaThread exit
2051 // should be done executing Java code by the time we get here.
2052 assert(!this->has_last_Java_frame(),
2053 "should not have a Java frame when detaching or exiting");
2054 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2055 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2056 }
2057
2058 // These things needs to be done while we are still a Java Thread. Make sure that thread
2059 // is in a consistent state, in case GC happens
2060 JFR_ONLY(Jfr::on_thread_exit(this);)
2061
2062 if (active_handles() != NULL) {
2063 JNIHandleBlock* block = active_handles();
2064 set_active_handles(NULL);
2065 JNIHandleBlock::release_block(block);
2066 }
2067
2068 if (free_handle_block() != NULL) {
2069 JNIHandleBlock* block = free_handle_block();
2070 set_free_handle_block(NULL);
2071 JNIHandleBlock::release_block(block);
2072 }
2073
2074 // These have to be removed while this is still a valid thread.
2075 remove_stack_guard_pages();
2076
2077 if (UseTLAB) {
2078 tlab().retire();
2079 }
2080
2081 if (JvmtiEnv::environments_might_exist()) {
2082 JvmtiExport::cleanup_thread(this);
2083 }
2084
2085 // We must flush any deferred card marks and other various GC barrier
2086 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2087 // before removing a thread from the list of active threads.
2088 BarrierSet::barrier_set()->on_thread_detach(this);
2089
2090 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2091 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2092 os::current_thread_id());
2093
2094 if (log_is_enabled(Debug, os, thread, timer)) {
2095 _timer_exit_phase3.stop();
2096 _timer_exit_phase4.start();
2097 }
2098 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2099 Threads::remove(this, daemon);
2100
2101 if (log_is_enabled(Debug, os, thread, timer)) {
2102 _timer_exit_phase4.stop();
2103 ResourceMark rm(this);
2104 log_debug(os, thread, timer)("name='%s'"
2105 ", exit-phase1=" JLONG_FORMAT
2106 ", exit-phase2=" JLONG_FORMAT
2107 ", exit-phase3=" JLONG_FORMAT
2108 ", exit-phase4=" JLONG_FORMAT,
2109 get_thread_name(),
2110 _timer_exit_phase1.milliseconds(),
2111 _timer_exit_phase2.milliseconds(),
2112 _timer_exit_phase3.milliseconds(),
2113 _timer_exit_phase4.milliseconds());
2114 }
2115 }
2116
2117 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2118 if (active_handles() != NULL) {
2119 JNIHandleBlock* block = active_handles();
2120 set_active_handles(NULL);
2121 JNIHandleBlock::release_block(block);
2122 }
2123
2124 if (free_handle_block() != NULL) {
2125 JNIHandleBlock* block = free_handle_block();
2126 set_free_handle_block(NULL);
2127 JNIHandleBlock::release_block(block);
2128 }
2129
2130 // These have to be removed while this is still a valid thread.
2131 remove_stack_guard_pages();
2132
2133 if (UseTLAB) {
2134 tlab().retire();
2135 }
2136
2137 BarrierSet::barrier_set()->on_thread_detach(this);
2138
2139 Threads::remove(this, is_daemon);
2140 this->smr_delete();
2141 }
2142
2143 JavaThread* JavaThread::active() {
2144 Thread* thread = Thread::current();
2145 if (thread->is_Java_thread()) {
2146 return (JavaThread*) thread;
2147 } else {
2148 assert(thread->is_VM_thread(), "this must be a vm thread");
2149 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2150 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2151 assert(ret->is_Java_thread(), "must be a Java thread");
2152 return ret;
2153 }
2154 }
2155
2156 bool JavaThread::is_lock_owned(address adr) const {
2157 if (Thread::is_lock_owned(adr)) return true;
2158
2159 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2160 if (chunk->contains(adr)) return true;
2161 }
2162
2163 return false;
2164 }
2165
2166
2167 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2168 chunk->set_next(monitor_chunks());
2169 set_monitor_chunks(chunk);
2170 }
2171
2172 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2173 guarantee(monitor_chunks() != NULL, "must be non empty");
2174 if (monitor_chunks() == chunk) {
2175 set_monitor_chunks(chunk->next());
2176 } else {
2177 MonitorChunk* prev = monitor_chunks();
2178 while (prev->next() != chunk) prev = prev->next();
2179 prev->set_next(chunk->next());
2180 }
2181 }
2182
2183 // JVM support.
2184
2185 // Note: this function shouldn't block if it's called in
2186 // _thread_in_native_trans state (such as from
2187 // check_special_condition_for_native_trans()).
2188 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2189
2190 if (has_last_Java_frame() && has_async_condition()) {
2191 // If we are at a polling page safepoint (not a poll return)
2192 // then we must defer async exception because live registers
2193 // will be clobbered by the exception path. Poll return is
2194 // ok because the call we a returning from already collides
2195 // with exception handling registers and so there is no issue.
2196 // (The exception handling path kills call result registers but
2197 // this is ok since the exception kills the result anyway).
2198
2199 if (is_at_poll_safepoint()) {
2200 // if the code we are returning to has deoptimized we must defer
2201 // the exception otherwise live registers get clobbered on the
2202 // exception path before deoptimization is able to retrieve them.
2203 //
2204 RegisterMap map(this, false);
2205 frame caller_fr = last_frame().sender(&map);
2206 assert(caller_fr.is_compiled_frame(), "what?");
2207 if (caller_fr.is_deoptimized_frame()) {
2208 log_info(exceptions)("deferred async exception at compiled safepoint");
2209 return;
2210 }
2211 }
2212 }
2213
2214 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2215 if (condition == _no_async_condition) {
2216 // Conditions have changed since has_special_runtime_exit_condition()
2217 // was called:
2218 // - if we were here only because of an external suspend request,
2219 // then that was taken care of above (or cancelled) so we are done
2220 // - if we were here because of another async request, then it has
2221 // been cleared between the has_special_runtime_exit_condition()
2222 // and now so again we are done
2223 return;
2224 }
2225
2226 // Check for pending async. exception
2227 if (_pending_async_exception != NULL) {
2228 // Only overwrite an already pending exception, if it is not a threadDeath.
2229 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2230
2231 // We cannot call Exceptions::_throw(...) here because we cannot block
2232 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2233
2234 LogTarget(Info, exceptions) lt;
2235 if (lt.is_enabled()) {
2236 ResourceMark rm;
2237 LogStream ls(lt);
2238 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2239 if (has_last_Java_frame()) {
2240 frame f = last_frame();
2241 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2242 }
2243 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2244 }
2245 _pending_async_exception = NULL;
2246 clear_has_async_exception();
2247 }
2248 }
2249
2250 if (check_unsafe_error &&
2251 condition == _async_unsafe_access_error && !has_pending_exception()) {
2252 condition = _no_async_condition; // done
2253 switch (thread_state()) {
2254 case _thread_in_vm: {
2255 JavaThread* THREAD = this;
2256 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2257 }
2258 case _thread_in_native: {
2259 ThreadInVMfromNative tiv(this);
2260 JavaThread* THREAD = this;
2261 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2262 }
2263 case _thread_in_Java: {
2264 ThreadInVMfromJava tiv(this);
2265 JavaThread* THREAD = this;
2266 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2267 }
2268 default:
2269 ShouldNotReachHere();
2270 }
2271 }
2272
2273 assert(condition == _no_async_condition || has_pending_exception() ||
2274 (!check_unsafe_error && condition == _async_unsafe_access_error),
2275 "must have handled the async condition, if no exception");
2276 }
2277
2278 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2279 //
2280 // Check for pending external suspend.
2281 // If JNIEnv proxies are allowed, don't self-suspend if the target
2282 // thread is not the current thread. In older versions of jdbx, jdbx
2283 // threads could call into the VM with another thread's JNIEnv so we
2284 // can be here operating on behalf of a suspended thread (4432884).
2285 bool do_self_suspend = is_external_suspend_with_lock();
2286 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2287 frame_anchor()->make_walkable(this);
2288 java_suspend_self_with_safepoint_check();
2289 }
2290
2291 // We might be here for reasons in addition to the self-suspend request
2292 // so check for other async requests.
2293 if (check_asyncs) {
2294 check_and_handle_async_exceptions();
2295 }
2296
2297 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2298 }
2299
2300 void JavaThread::send_thread_stop(oop java_throwable) {
2301 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2302 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2303 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2304
2305 // Do not throw asynchronous exceptions against the compiler thread
2306 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2307 if (!can_call_java()) return;
2308
2309 {
2310 // Actually throw the Throwable against the target Thread - however
2311 // only if there is no thread death exception installed already.
2312 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2313 // If the topmost frame is a runtime stub, then we are calling into
2314 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2315 // must deoptimize the caller before continuing, as the compiled exception handler table
2316 // may not be valid
2317 if (has_last_Java_frame()) {
2318 frame f = last_frame();
2319 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2320 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2321 RegisterMap reg_map(this, UseBiasedLocking);
2322 frame compiled_frame = f.sender(®_map);
2323 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2324 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2325 }
2326 }
2327 }
2328
2329 // Set async. pending exception in thread.
2330 set_pending_async_exception(java_throwable);
2331
2332 if (log_is_enabled(Info, exceptions)) {
2333 ResourceMark rm;
2334 log_info(exceptions)("Pending Async. exception installed of type: %s",
2335 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2336 }
2337 // for AbortVMOnException flag
2338 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2339 }
2340 }
2341
2342
2343 // Interrupt thread so it will wake up from a potential wait()
2344 Thread::interrupt(this);
2345 }
2346
2347 // External suspension mechanism.
2348 //
2349 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2350 // to any VM_locks and it is at a transition
2351 // Self-suspension will happen on the transition out of the vm.
2352 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2353 //
2354 // Guarantees on return:
2355 // + Target thread will not execute any new bytecode (that's why we need to
2356 // force a safepoint)
2357 // + Target thread will not enter any new monitors
2358 //
2359 void JavaThread::java_suspend() {
2360 ThreadsListHandle tlh;
2361 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2362 return;
2363 }
2364
2365 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2366 if (!is_external_suspend()) {
2367 // a racing resume has cancelled us; bail out now
2368 return;
2369 }
2370
2371 // suspend is done
2372 uint32_t debug_bits = 0;
2373 // Warning: is_ext_suspend_completed() may temporarily drop the
2374 // SR_lock to allow the thread to reach a stable thread state if
2375 // it is currently in a transient thread state.
2376 if (is_ext_suspend_completed(false /* !called_by_wait */,
2377 SuspendRetryDelay, &debug_bits)) {
2378 return;
2379 }
2380 }
2381
2382 if (Thread::current() == this) {
2383 // Safely self-suspend.
2384 // If we don't do this explicitly it will implicitly happen
2385 // before we transition back to Java, and on some other thread-state
2386 // transition paths, but not as we exit a JVM TI SuspendThread call.
2387 // As SuspendThread(current) must not return (until resumed) we must
2388 // self-suspend here.
2389 ThreadBlockInVM tbivm(this);
2390 java_suspend_self();
2391 } else {
2392 VM_ThreadSuspend vm_suspend;
2393 VMThread::execute(&vm_suspend);
2394 }
2395 }
2396
2397 // Part II of external suspension.
2398 // A JavaThread self suspends when it detects a pending external suspend
2399 // request. This is usually on transitions. It is also done in places
2400 // where continuing to the next transition would surprise the caller,
2401 // e.g., monitor entry.
2402 //
2403 // Returns the number of times that the thread self-suspended.
2404 //
2405 // Note: DO NOT call java_suspend_self() when you just want to block current
2406 // thread. java_suspend_self() is the second stage of cooperative
2407 // suspension for external suspend requests and should only be used
2408 // to complete an external suspend request.
2409 //
2410 int JavaThread::java_suspend_self() {
2411 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2412 int ret = 0;
2413
2414 // we are in the process of exiting so don't suspend
2415 if (is_exiting()) {
2416 clear_external_suspend();
2417 return ret;
2418 }
2419
2420 assert(_anchor.walkable() ||
2421 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2422 "must have walkable stack");
2423
2424 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2425
2426 assert(!this->is_ext_suspended(),
2427 "a thread trying to self-suspend should not already be suspended");
2428
2429 if (this->is_suspend_equivalent()) {
2430 // If we are self-suspending as a result of the lifting of a
2431 // suspend equivalent condition, then the suspend_equivalent
2432 // flag is not cleared until we set the ext_suspended flag so
2433 // that wait_for_ext_suspend_completion() returns consistent
2434 // results.
2435 this->clear_suspend_equivalent();
2436 }
2437
2438 // A racing resume may have cancelled us before we grabbed SR_lock
2439 // above. Or another external suspend request could be waiting for us
2440 // by the time we return from SR_lock()->wait(). The thread
2441 // that requested the suspension may already be trying to walk our
2442 // stack and if we return now, we can change the stack out from under
2443 // it. This would be a "bad thing (TM)" and cause the stack walker
2444 // to crash. We stay self-suspended until there are no more pending
2445 // external suspend requests.
2446 while (is_external_suspend()) {
2447 ret++;
2448 this->set_ext_suspended();
2449
2450 // _ext_suspended flag is cleared by java_resume()
2451 while (is_ext_suspended()) {
2452 ml.wait();
2453 }
2454 }
2455 return ret;
2456 }
2457
2458 // Helper routine to set up the correct thread state before calling java_suspend_self.
2459 // This is called when regular thread-state transition helpers can't be used because
2460 // we can be in various states, in particular _thread_in_native_trans.
2461 // Because this thread is external suspended the safepoint code will count it as at
2462 // a safepoint, regardless of what its actual current thread-state is. But
2463 // is_ext_suspend_completed() may be waiting to see a thread transition from
2464 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2465 // to _thread_blocked. The problem with setting thread state directly is that a
2466 // safepoint could happen just after java_suspend_self() returns after being resumed,
2467 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2468 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2469 // However, not all initial-states are allowed when performing a safepoint check, as we
2470 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2471 // only _thread_in_native is possible when executing this code (based on our two callers).
2472 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2473 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2474 // and so we don't need the explicit safepoint check.
2475
2476 void JavaThread::java_suspend_self_with_safepoint_check() {
2477 assert(this == Thread::current(), "invariant");
2478 JavaThreadState state = thread_state();
2479 set_thread_state(_thread_blocked);
2480 java_suspend_self();
2481 set_thread_state_fence(state);
2482 // Since we are not using a regular thread-state transition helper here,
2483 // we must manually emit the instruction barrier after leaving a safe state.
2484 OrderAccess::cross_modify_fence();
2485 if (state != _thread_in_native) {
2486 SafepointMechanism::block_if_requested(this);
2487 }
2488 }
2489
2490 #ifdef ASSERT
2491 // Verify the JavaThread has not yet been published in the Threads::list, and
2492 // hence doesn't need protection from concurrent access at this stage.
2493 void JavaThread::verify_not_published() {
2494 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2495 // since an unpublished JavaThread doesn't participate in the
2496 // Thread-SMR protocol for keeping a ThreadsList alive.
2497 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2498 }
2499 #endif
2500
2501 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2502 // progress or when _suspend_flags is non-zero.
2503 // Current thread needs to self-suspend if there is a suspend request and/or
2504 // block if a safepoint is in progress.
2505 // Async exception ISN'T checked.
2506 // Note only the ThreadInVMfromNative transition can call this function
2507 // directly and when thread state is _thread_in_native_trans
2508 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2509 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2510
2511 JavaThread *curJT = JavaThread::current();
2512 bool do_self_suspend = thread->is_external_suspend();
2513
2514 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2515
2516 // If JNIEnv proxies are allowed, don't self-suspend if the target
2517 // thread is not the current thread. In older versions of jdbx, jdbx
2518 // threads could call into the VM with another thread's JNIEnv so we
2519 // can be here operating on behalf of a suspended thread (4432884).
2520 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2521 thread->java_suspend_self_with_safepoint_check();
2522 } else {
2523 SafepointMechanism::block_if_requested(curJT);
2524 }
2525
2526 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2527 }
2528
2529 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2530 // progress or when _suspend_flags is non-zero.
2531 // Current thread needs to self-suspend if there is a suspend request and/or
2532 // block if a safepoint is in progress.
2533 // Also check for pending async exception (not including unsafe access error).
2534 // Note only the native==>VM/Java barriers can call this function and when
2535 // thread state is _thread_in_native_trans.
2536 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2537 check_safepoint_and_suspend_for_native_trans(thread);
2538
2539 if (thread->has_async_exception()) {
2540 // We are in _thread_in_native_trans state, don't handle unsafe
2541 // access error since that may block.
2542 thread->check_and_handle_async_exceptions(false);
2543 }
2544 }
2545
2546 // This is a variant of the normal
2547 // check_special_condition_for_native_trans with slightly different
2548 // semantics for use by critical native wrappers. It does all the
2549 // normal checks but also performs the transition back into
2550 // thread_in_Java state. This is required so that critical natives
2551 // can potentially block and perform a GC if they are the last thread
2552 // exiting the GCLocker.
2553 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2554 check_special_condition_for_native_trans(thread);
2555
2556 // Finish the transition
2557 thread->set_thread_state(_thread_in_Java);
2558
2559 if (thread->do_critical_native_unlock()) {
2560 ThreadInVMfromJavaNoAsyncException tiv(thread);
2561 GCLocker::unlock_critical(thread);
2562 thread->clear_critical_native_unlock();
2563 }
2564 }
2565
2566 // We need to guarantee the Threads_lock here, since resumes are not
2567 // allowed during safepoint synchronization
2568 // Can only resume from an external suspension
2569 void JavaThread::java_resume() {
2570 assert_locked_or_safepoint(Threads_lock);
2571
2572 // Sanity check: thread is gone, has started exiting or the thread
2573 // was not externally suspended.
2574 ThreadsListHandle tlh;
2575 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2576 return;
2577 }
2578
2579 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2580
2581 clear_external_suspend();
2582
2583 if (is_ext_suspended()) {
2584 clear_ext_suspended();
2585 SR_lock()->notify_all();
2586 }
2587 }
2588
2589 size_t JavaThread::_stack_red_zone_size = 0;
2590 size_t JavaThread::_stack_yellow_zone_size = 0;
2591 size_t JavaThread::_stack_reserved_zone_size = 0;
2592 size_t JavaThread::_stack_shadow_zone_size = 0;
2593
2594 void JavaThread::create_stack_guard_pages() {
2595 if (!os::uses_stack_guard_pages() ||
2596 _stack_guard_state != stack_guard_unused ||
2597 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2598 log_info(os, thread)("Stack guard page creation for thread "
2599 UINTX_FORMAT " disabled", os::current_thread_id());
2600 return;
2601 }
2602 address low_addr = stack_end();
2603 size_t len = stack_guard_zone_size();
2604
2605 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2606 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2607
2608 int must_commit = os::must_commit_stack_guard_pages();
2609 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2610
2611 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2612 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2613 return;
2614 }
2615
2616 if (os::guard_memory((char *) low_addr, len)) {
2617 _stack_guard_state = stack_guard_enabled;
2618 } else {
2619 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2620 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2621 if (os::uncommit_memory((char *) low_addr, len)) {
2622 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2623 }
2624 return;
2625 }
2626
2627 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2628 PTR_FORMAT "-" PTR_FORMAT ".",
2629 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2630 }
2631
2632 void JavaThread::remove_stack_guard_pages() {
2633 assert(Thread::current() == this, "from different thread");
2634 if (_stack_guard_state == stack_guard_unused) return;
2635 address low_addr = stack_end();
2636 size_t len = stack_guard_zone_size();
2637
2638 if (os::must_commit_stack_guard_pages()) {
2639 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2640 _stack_guard_state = stack_guard_unused;
2641 } else {
2642 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2643 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2644 return;
2645 }
2646 } else {
2647 if (_stack_guard_state == stack_guard_unused) return;
2648 if (os::unguard_memory((char *) low_addr, len)) {
2649 _stack_guard_state = stack_guard_unused;
2650 } else {
2651 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2652 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2653 return;
2654 }
2655 }
2656
2657 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2658 PTR_FORMAT "-" PTR_FORMAT ".",
2659 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2660 }
2661
2662 void JavaThread::enable_stack_reserved_zone() {
2663 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2664
2665 // The base notation is from the stack's point of view, growing downward.
2666 // We need to adjust it to work correctly with guard_memory()
2667 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2668
2669 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2670 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2671
2672 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2673 _stack_guard_state = stack_guard_enabled;
2674 } else {
2675 warning("Attempt to guard stack reserved zone failed.");
2676 }
2677 enable_register_stack_guard();
2678 }
2679
2680 void JavaThread::disable_stack_reserved_zone() {
2681 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2682
2683 // Simply return if called for a thread that does not use guard pages.
2684 if (_stack_guard_state != stack_guard_enabled) return;
2685
2686 // The base notation is from the stack's point of view, growing downward.
2687 // We need to adjust it to work correctly with guard_memory()
2688 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2689
2690 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2691 _stack_guard_state = stack_guard_reserved_disabled;
2692 } else {
2693 warning("Attempt to unguard stack reserved zone failed.");
2694 }
2695 disable_register_stack_guard();
2696 }
2697
2698 void JavaThread::enable_stack_yellow_reserved_zone() {
2699 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2700 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2701
2702 // The base notation is from the stacks point of view, growing downward.
2703 // We need to adjust it to work correctly with guard_memory()
2704 address base = stack_red_zone_base();
2705
2706 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2707 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2708
2709 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2710 _stack_guard_state = stack_guard_enabled;
2711 } else {
2712 warning("Attempt to guard stack yellow zone failed.");
2713 }
2714 enable_register_stack_guard();
2715 }
2716
2717 void JavaThread::disable_stack_yellow_reserved_zone() {
2718 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2719 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2720
2721 // Simply return if called for a thread that does not use guard pages.
2722 if (_stack_guard_state == stack_guard_unused) return;
2723
2724 // The base notation is from the stacks point of view, growing downward.
2725 // We need to adjust it to work correctly with guard_memory()
2726 address base = stack_red_zone_base();
2727
2728 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2729 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2730 } else {
2731 warning("Attempt to unguard stack yellow zone failed.");
2732 }
2733 disable_register_stack_guard();
2734 }
2735
2736 void JavaThread::enable_stack_red_zone() {
2737 // The base notation is from the stacks point of view, growing downward.
2738 // We need to adjust it to work correctly with guard_memory()
2739 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2740 address base = stack_red_zone_base() - stack_red_zone_size();
2741
2742 guarantee(base < stack_base(), "Error calculating stack red zone");
2743 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2744
2745 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2746 warning("Attempt to guard stack red zone failed.");
2747 }
2748 }
2749
2750 void JavaThread::disable_stack_red_zone() {
2751 // The base notation is from the stacks point of view, growing downward.
2752 // We need to adjust it to work correctly with guard_memory()
2753 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2754 address base = stack_red_zone_base() - stack_red_zone_size();
2755 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2756 warning("Attempt to unguard stack red zone failed.");
2757 }
2758 }
2759
2760 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2761 // ignore is there is no stack
2762 if (!has_last_Java_frame()) return;
2763 // traverse the stack frames. Starts from top frame.
2764 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2765 frame* fr = fst.current();
2766 f(fr, fst.register_map());
2767 }
2768 }
2769
2770
2771 #ifndef PRODUCT
2772 // Deoptimization
2773 // Function for testing deoptimization
2774 void JavaThread::deoptimize() {
2775 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2776 StackFrameStream fst(this, UseBiasedLocking);
2777 bool deopt = false; // Dump stack only if a deopt actually happens.
2778 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2779 // Iterate over all frames in the thread and deoptimize
2780 for (; !fst.is_done(); fst.next()) {
2781 if (fst.current()->can_be_deoptimized()) {
2782
2783 if (only_at) {
2784 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2785 // consists of comma or carriage return separated numbers so
2786 // search for the current bci in that string.
2787 address pc = fst.current()->pc();
2788 nmethod* nm = (nmethod*) fst.current()->cb();
2789 ScopeDesc* sd = nm->scope_desc_at(pc);
2790 char buffer[8];
2791 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2792 size_t len = strlen(buffer);
2793 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2794 while (found != NULL) {
2795 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2796 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2797 // Check that the bci found is bracketed by terminators.
2798 break;
2799 }
2800 found = strstr(found + 1, buffer);
2801 }
2802 if (!found) {
2803 continue;
2804 }
2805 }
2806
2807 if (DebugDeoptimization && !deopt) {
2808 deopt = true; // One-time only print before deopt
2809 tty->print_cr("[BEFORE Deoptimization]");
2810 trace_frames();
2811 trace_stack();
2812 }
2813 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2814 }
2815 }
2816
2817 if (DebugDeoptimization && deopt) {
2818 tty->print_cr("[AFTER Deoptimization]");
2819 trace_frames();
2820 }
2821 }
2822
2823
2824 // Make zombies
2825 void JavaThread::make_zombies() {
2826 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2827 if (fst.current()->can_be_deoptimized()) {
2828 // it is a Java nmethod
2829 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2830 nm->make_not_entrant();
2831 }
2832 }
2833 }
2834 #endif // PRODUCT
2835
2836
2837 void JavaThread::deoptimize_marked_methods(bool in_handshake) {
2838 if (!has_last_Java_frame()) return;
2839 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2840 StackFrameStream fst(this, UseBiasedLocking);
2841 for (; !fst.is_done(); fst.next()) {
2842 if (fst.current()->should_be_deoptimized()) {
2843 Deoptimization::deoptimize(this, *fst.current(), fst.register_map(), in_handshake);
2844 }
2845 }
2846 }
2847
2848 // If the caller is a NamedThread, then remember, in the current scope,
2849 // the given JavaThread in its _processed_thread field.
2850 class RememberProcessedThread: public StackObj {
2851 NamedThread* _cur_thr;
2852 public:
2853 RememberProcessedThread(JavaThread* jthr) {
2854 Thread* thread = Thread::current();
2855 if (thread->is_Named_thread()) {
2856 _cur_thr = (NamedThread *)thread;
2857 _cur_thr->set_processed_thread(jthr);
2858 } else {
2859 _cur_thr = NULL;
2860 }
2861 }
2862
2863 ~RememberProcessedThread() {
2864 if (_cur_thr) {
2865 _cur_thr->set_processed_thread(NULL);
2866 }
2867 }
2868 };
2869
2870 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2871 // Verify that the deferred card marks have been flushed.
2872 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2873
2874 // Traverse the GCHandles
2875 Thread::oops_do(f, cf);
2876
2877 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2878 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2879
2880 if (has_last_Java_frame()) {
2881 // Record JavaThread to GC thread
2882 RememberProcessedThread rpt(this);
2883
2884 // traverse the registered growable array
2885 if (_array_for_gc != NULL) {
2886 for (int index = 0; index < _array_for_gc->length(); index++) {
2887 f->do_oop(_array_for_gc->adr_at(index));
2888 }
2889 }
2890
2891 // Traverse the monitor chunks
2892 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2893 chunk->oops_do(f);
2894 }
2895
2896 // Traverse the execution stack
2897 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2898 fst.current()->oops_do(f, cf, fst.register_map());
2899 }
2900 }
2901
2902 // callee_target is never live across a gc point so NULL it here should
2903 // it still contain a methdOop.
2904
2905 set_callee_target(NULL);
2906
2907 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2908 // If we have deferred set_locals there might be oops waiting to be
2909 // written
2910 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2911 if (list != NULL) {
2912 for (int i = 0; i < list->length(); i++) {
2913 list->at(i)->oops_do(f);
2914 }
2915 }
2916
2917 // Traverse instance variables at the end since the GC may be moving things
2918 // around using this function
2919 f->do_oop((oop*) &_threadObj);
2920 f->do_oop((oop*) &_vm_result);
2921 f->do_oop((oop*) &_exception_oop);
2922 f->do_oop((oop*) &_pending_async_exception);
2923
2924 if (jvmti_thread_state() != NULL) {
2925 jvmti_thread_state()->oops_do(f);
2926 }
2927 }
2928
2929 #ifdef ASSERT
2930 void JavaThread::verify_states_for_handshake() {
2931 // This checks that the thread has a correct frame state during a handshake.
2932 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2933 (has_last_Java_frame() && java_call_counter() > 0),
2934 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2935 has_last_Java_frame(), java_call_counter());
2936 }
2937 #endif
2938
2939 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2940 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2941 (has_last_Java_frame() && java_call_counter() > 0),
2942 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2943 has_last_Java_frame(), java_call_counter());
2944
2945 if (has_last_Java_frame()) {
2946 // Traverse the execution stack
2947 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2948 fst.current()->nmethods_do(cf);
2949 }
2950 }
2951 }
2952
2953 void JavaThread::metadata_do(MetadataClosure* f) {
2954 if (has_last_Java_frame()) {
2955 // Traverse the execution stack to call f() on the methods in the stack
2956 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2957 fst.current()->metadata_do(f);
2958 }
2959 } else if (is_Compiler_thread()) {
2960 // need to walk ciMetadata in current compile tasks to keep alive.
2961 CompilerThread* ct = (CompilerThread*)this;
2962 if (ct->env() != NULL) {
2963 ct->env()->metadata_do(f);
2964 }
2965 CompileTask* task = ct->task();
2966 if (task != NULL) {
2967 task->metadata_do(f);
2968 }
2969 }
2970 }
2971
2972 // Printing
2973 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2974 switch (_thread_state) {
2975 case _thread_uninitialized: return "_thread_uninitialized";
2976 case _thread_new: return "_thread_new";
2977 case _thread_new_trans: return "_thread_new_trans";
2978 case _thread_in_native: return "_thread_in_native";
2979 case _thread_in_native_trans: return "_thread_in_native_trans";
2980 case _thread_in_vm: return "_thread_in_vm";
2981 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2982 case _thread_in_Java: return "_thread_in_Java";
2983 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2984 case _thread_blocked: return "_thread_blocked";
2985 case _thread_blocked_trans: return "_thread_blocked_trans";
2986 default: return "unknown thread state";
2987 }
2988 }
2989
2990 #ifndef PRODUCT
2991 void JavaThread::print_thread_state_on(outputStream *st) const {
2992 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2993 };
2994 void JavaThread::print_thread_state() const {
2995 print_thread_state_on(tty);
2996 }
2997 #endif // PRODUCT
2998
2999 // Called by Threads::print() for VM_PrintThreads operation
3000 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3001 st->print_raw("\"");
3002 st->print_raw(get_thread_name());
3003 st->print_raw("\" ");
3004 oop thread_oop = threadObj();
3005 if (thread_oop != NULL) {
3006 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3007 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3008 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3009 }
3010 Thread::print_on(st, print_extended_info);
3011 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3012 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3013 if (thread_oop != NULL) {
3014 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3015 }
3016 #ifndef PRODUCT
3017 _safepoint_state->print_on(st);
3018 #endif // PRODUCT
3019 if (is_Compiler_thread()) {
3020 CompileTask *task = ((CompilerThread*)this)->task();
3021 if (task != NULL) {
3022 st->print(" Compiling: ");
3023 task->print(st, NULL, true, false);
3024 } else {
3025 st->print(" No compile task");
3026 }
3027 st->cr();
3028 }
3029 }
3030
3031 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3032 st->print("%s", get_thread_name_string(buf, buflen));
3033 }
3034
3035 // Called by fatal error handler. The difference between this and
3036 // JavaThread::print() is that we can't grab lock or allocate memory.
3037 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3038 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3039 oop thread_obj = threadObj();
3040 if (thread_obj != NULL) {
3041 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3042 }
3043 st->print(" [");
3044 st->print("%s", _get_thread_state_name(_thread_state));
3045 if (osthread()) {
3046 st->print(", id=%d", osthread()->thread_id());
3047 }
3048 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3049 p2i(stack_end()), p2i(stack_base()));
3050 st->print("]");
3051
3052 ThreadsSMRSupport::print_info_on(this, st);
3053 return;
3054 }
3055
3056 // Verification
3057
3058 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3059
3060 void JavaThread::verify() {
3061 // Verify oops in the thread.
3062 oops_do(&VerifyOopClosure::verify_oop, NULL);
3063
3064 // Verify the stack frames.
3065 frames_do(frame_verify);
3066 }
3067
3068 // CR 6300358 (sub-CR 2137150)
3069 // Most callers of this method assume that it can't return NULL but a
3070 // thread may not have a name whilst it is in the process of attaching to
3071 // the VM - see CR 6412693, and there are places where a JavaThread can be
3072 // seen prior to having it's threadObj set (eg JNI attaching threads and
3073 // if vm exit occurs during initialization). These cases can all be accounted
3074 // for such that this method never returns NULL.
3075 const char* JavaThread::get_thread_name() const {
3076 #ifdef ASSERT
3077 // early safepoints can hit while current thread does not yet have TLS
3078 if (!SafepointSynchronize::is_at_safepoint()) {
3079 Thread *cur = Thread::current();
3080 if (!(cur->is_Java_thread() && cur == this)) {
3081 // Current JavaThreads are allowed to get their own name without
3082 // the Threads_lock.
3083 assert_locked_or_safepoint(Threads_lock);
3084 }
3085 }
3086 #endif // ASSERT
3087 return get_thread_name_string();
3088 }
3089
3090 // Returns a non-NULL representation of this thread's name, or a suitable
3091 // descriptive string if there is no set name
3092 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3093 const char* name_str;
3094 oop thread_obj = threadObj();
3095 if (thread_obj != NULL) {
3096 oop name = java_lang_Thread::name(thread_obj);
3097 if (name != NULL) {
3098 if (buf == NULL) {
3099 name_str = java_lang_String::as_utf8_string(name);
3100 } else {
3101 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3102 }
3103 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3104 name_str = "<no-name - thread is attaching>";
3105 } else {
3106 name_str = Thread::name();
3107 }
3108 } else {
3109 name_str = Thread::name();
3110 }
3111 assert(name_str != NULL, "unexpected NULL thread name");
3112 return name_str;
3113 }
3114
3115
3116 const char* JavaThread::get_threadgroup_name() const {
3117 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3118 oop thread_obj = threadObj();
3119 if (thread_obj != NULL) {
3120 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3121 if (thread_group != NULL) {
3122 // ThreadGroup.name can be null
3123 return java_lang_ThreadGroup::name(thread_group);
3124 }
3125 }
3126 return NULL;
3127 }
3128
3129 const char* JavaThread::get_parent_name() const {
3130 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3131 oop thread_obj = threadObj();
3132 if (thread_obj != NULL) {
3133 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3134 if (thread_group != NULL) {
3135 oop parent = java_lang_ThreadGroup::parent(thread_group);
3136 if (parent != NULL) {
3137 // ThreadGroup.name can be null
3138 return java_lang_ThreadGroup::name(parent);
3139 }
3140 }
3141 }
3142 return NULL;
3143 }
3144
3145 ThreadPriority JavaThread::java_priority() const {
3146 oop thr_oop = threadObj();
3147 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3148 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3149 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3150 return priority;
3151 }
3152
3153 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3154
3155 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3156 // Link Java Thread object <-> C++ Thread
3157
3158 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3159 // and put it into a new Handle. The Handle "thread_oop" can then
3160 // be used to pass the C++ thread object to other methods.
3161
3162 // Set the Java level thread object (jthread) field of the
3163 // new thread (a JavaThread *) to C++ thread object using the
3164 // "thread_oop" handle.
3165
3166 // Set the thread field (a JavaThread *) of the
3167 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3168
3169 Handle thread_oop(Thread::current(),
3170 JNIHandles::resolve_non_null(jni_thread));
3171 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3172 "must be initialized");
3173 set_threadObj(thread_oop());
3174 java_lang_Thread::set_thread(thread_oop(), this);
3175
3176 if (prio == NoPriority) {
3177 prio = java_lang_Thread::priority(thread_oop());
3178 assert(prio != NoPriority, "A valid priority should be present");
3179 }
3180
3181 // Push the Java priority down to the native thread; needs Threads_lock
3182 Thread::set_priority(this, prio);
3183
3184 // Add the new thread to the Threads list and set it in motion.
3185 // We must have threads lock in order to call Threads::add.
3186 // It is crucial that we do not block before the thread is
3187 // added to the Threads list for if a GC happens, then the java_thread oop
3188 // will not be visited by GC.
3189 Threads::add(this);
3190 }
3191
3192 oop JavaThread::current_park_blocker() {
3193 // Support for JSR-166 locks
3194 oop thread_oop = threadObj();
3195 if (thread_oop != NULL &&
3196 JDK_Version::current().supports_thread_park_blocker()) {
3197 return java_lang_Thread::park_blocker(thread_oop);
3198 }
3199 return NULL;
3200 }
3201
3202
3203 void JavaThread::print_stack_on(outputStream* st) {
3204 if (!has_last_Java_frame()) return;
3205 ResourceMark rm;
3206 HandleMark hm;
3207
3208 RegisterMap reg_map(this);
3209 vframe* start_vf = last_java_vframe(®_map);
3210 int count = 0;
3211 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3212 if (f->is_java_frame()) {
3213 javaVFrame* jvf = javaVFrame::cast(f);
3214 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3215
3216 // Print out lock information
3217 if (JavaMonitorsInStackTrace) {
3218 jvf->print_lock_info_on(st, count);
3219 }
3220 } else {
3221 // Ignore non-Java frames
3222 }
3223
3224 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3225 count++;
3226 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3227 }
3228 }
3229
3230
3231 // JVMTI PopFrame support
3232 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3233 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3234 if (in_bytes(size_in_bytes) != 0) {
3235 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3236 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3237 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3238 }
3239 }
3240
3241 void* JavaThread::popframe_preserved_args() {
3242 return _popframe_preserved_args;
3243 }
3244
3245 ByteSize JavaThread::popframe_preserved_args_size() {
3246 return in_ByteSize(_popframe_preserved_args_size);
3247 }
3248
3249 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3250 int sz = in_bytes(popframe_preserved_args_size());
3251 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3252 return in_WordSize(sz / wordSize);
3253 }
3254
3255 void JavaThread::popframe_free_preserved_args() {
3256 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3257 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3258 _popframe_preserved_args = NULL;
3259 _popframe_preserved_args_size = 0;
3260 }
3261
3262 #ifndef PRODUCT
3263
3264 void JavaThread::trace_frames() {
3265 tty->print_cr("[Describe stack]");
3266 int frame_no = 1;
3267 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3268 tty->print(" %d. ", frame_no++);
3269 fst.current()->print_value_on(tty, this);
3270 tty->cr();
3271 }
3272 }
3273
3274 class PrintAndVerifyOopClosure: public OopClosure {
3275 protected:
3276 template <class T> inline void do_oop_work(T* p) {
3277 oop obj = RawAccess<>::oop_load(p);
3278 if (obj == NULL) return;
3279 tty->print(INTPTR_FORMAT ": ", p2i(p));
3280 if (oopDesc::is_oop_or_null(obj)) {
3281 if (obj->is_objArray()) {
3282 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3283 } else {
3284 obj->print();
3285 }
3286 } else {
3287 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3288 }
3289 tty->cr();
3290 }
3291 public:
3292 virtual void do_oop(oop* p) { do_oop_work(p); }
3293 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3294 };
3295
3296
3297 static void oops_print(frame* f, const RegisterMap *map) {
3298 PrintAndVerifyOopClosure print;
3299 f->print_value();
3300 f->oops_do(&print, NULL, (RegisterMap*)map);
3301 }
3302
3303 // Print our all the locations that contain oops and whether they are
3304 // valid or not. This useful when trying to find the oldest frame
3305 // where an oop has gone bad since the frame walk is from youngest to
3306 // oldest.
3307 void JavaThread::trace_oops() {
3308 tty->print_cr("[Trace oops]");
3309 frames_do(oops_print);
3310 }
3311
3312
3313 #ifdef ASSERT
3314 // Print or validate the layout of stack frames
3315 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3316 ResourceMark rm;
3317 PRESERVE_EXCEPTION_MARK;
3318 FrameValues values;
3319 int frame_no = 0;
3320 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3321 fst.current()->describe(values, ++frame_no);
3322 if (depth == frame_no) break;
3323 }
3324 if (validate_only) {
3325 values.validate();
3326 } else {
3327 tty->print_cr("[Describe stack layout]");
3328 values.print(this);
3329 }
3330 }
3331 #endif
3332
3333 void JavaThread::trace_stack_from(vframe* start_vf) {
3334 ResourceMark rm;
3335 int vframe_no = 1;
3336 for (vframe* f = start_vf; f; f = f->sender()) {
3337 if (f->is_java_frame()) {
3338 javaVFrame::cast(f)->print_activation(vframe_no++);
3339 } else {
3340 f->print();
3341 }
3342 if (vframe_no > StackPrintLimit) {
3343 tty->print_cr("...<more frames>...");
3344 return;
3345 }
3346 }
3347 }
3348
3349
3350 void JavaThread::trace_stack() {
3351 if (!has_last_Java_frame()) return;
3352 ResourceMark rm;
3353 HandleMark hm;
3354 RegisterMap reg_map(this);
3355 trace_stack_from(last_java_vframe(®_map));
3356 }
3357
3358
3359 #endif // PRODUCT
3360
3361
3362 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3363 assert(reg_map != NULL, "a map must be given");
3364 frame f = last_frame();
3365 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3366 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3367 }
3368 return NULL;
3369 }
3370
3371
3372 Klass* JavaThread::security_get_caller_class(int depth) {
3373 vframeStream vfst(this);
3374 vfst.security_get_caller_frame(depth);
3375 if (!vfst.at_end()) {
3376 return vfst.method()->method_holder();
3377 }
3378 return NULL;
3379 }
3380
3381 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3382 assert(thread->is_Compiler_thread(), "must be compiler thread");
3383 CompileBroker::compiler_thread_loop();
3384 }
3385
3386 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3387 NMethodSweeper::sweeper_loop();
3388 }
3389
3390 // Create a CompilerThread
3391 CompilerThread::CompilerThread(CompileQueue* queue,
3392 CompilerCounters* counters)
3393 : JavaThread(&compiler_thread_entry) {
3394 _env = NULL;
3395 _log = NULL;
3396 _task = NULL;
3397 _queue = queue;
3398 _counters = counters;
3399 _buffer_blob = NULL;
3400 _compiler = NULL;
3401
3402 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3403 resource_area()->bias_to(mtCompiler);
3404
3405 #ifndef PRODUCT
3406 _ideal_graph_printer = NULL;
3407 #endif
3408 }
3409
3410 CompilerThread::~CompilerThread() {
3411 // Delete objects which were allocated on heap.
3412 delete _counters;
3413 }
3414
3415 bool CompilerThread::can_call_java() const {
3416 return _compiler != NULL && _compiler->is_jvmci();
3417 }
3418
3419 // Create sweeper thread
3420 CodeCacheSweeperThread::CodeCacheSweeperThread()
3421 : JavaThread(&sweeper_thread_entry) {
3422 _scanned_compiled_method = NULL;
3423 }
3424
3425 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3426 JavaThread::oops_do(f, cf);
3427 if (_scanned_compiled_method != NULL && cf != NULL) {
3428 // Safepoints can occur when the sweeper is scanning an nmethod so
3429 // process it here to make sure it isn't unloaded in the middle of
3430 // a scan.
3431 cf->do_code_blob(_scanned_compiled_method);
3432 }
3433 }
3434
3435 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3436 JavaThread::nmethods_do(cf);
3437 if (_scanned_compiled_method != NULL && cf != NULL) {
3438 // Safepoints can occur when the sweeper is scanning an nmethod so
3439 // process it here to make sure it isn't unloaded in the middle of
3440 // a scan.
3441 cf->do_code_blob(_scanned_compiled_method);
3442 }
3443 }
3444
3445
3446 // ======= Threads ========
3447
3448 // The Threads class links together all active threads, and provides
3449 // operations over all threads. It is protected by the Threads_lock,
3450 // which is also used in other global contexts like safepointing.
3451 // ThreadsListHandles are used to safely perform operations on one
3452 // or more threads without the risk of the thread exiting during the
3453 // operation.
3454 //
3455 // Note: The Threads_lock is currently more widely used than we
3456 // would like. We are actively migrating Threads_lock uses to other
3457 // mechanisms in order to reduce Threads_lock contention.
3458
3459 JavaThread* Threads::_thread_list = NULL;
3460 int Threads::_number_of_threads = 0;
3461 int Threads::_number_of_non_daemon_threads = 0;
3462 int Threads::_return_code = 0;
3463 uintx Threads::_thread_claim_token = 1; // Never zero.
3464 size_t JavaThread::_stack_size_at_create = 0;
3465
3466 #ifdef ASSERT
3467 bool Threads::_vm_complete = false;
3468 #endif
3469
3470 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3471 Prefetch::read((void*)addr, prefetch_interval);
3472 return *addr;
3473 }
3474
3475 // Possibly the ugliest for loop the world has seen. C++ does not allow
3476 // multiple types in the declaration section of the for loop. In this case
3477 // we are only dealing with pointers and hence can cast them. It looks ugly
3478 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3479 #define DO_JAVA_THREADS(LIST, X) \
3480 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3481 *MACRO_list = (JavaThread*)(LIST), \
3482 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3483 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3484 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3485 MACRO_current_p != MACRO_end; \
3486 MACRO_current_p++, \
3487 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3488
3489 // All JavaThreads
3490 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3491
3492 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3493 void Threads::non_java_threads_do(ThreadClosure* tc) {
3494 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3495 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3496 tc->do_thread(njti.current());
3497 }
3498 }
3499
3500 // All JavaThreads
3501 void Threads::java_threads_do(ThreadClosure* tc) {
3502 assert_locked_or_safepoint(Threads_lock);
3503 // ALL_JAVA_THREADS iterates through all JavaThreads.
3504 ALL_JAVA_THREADS(p) {
3505 tc->do_thread(p);
3506 }
3507 }
3508
3509 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3510 assert_locked_or_safepoint(Threads_lock);
3511 java_threads_do(tc);
3512 tc->do_thread(VMThread::vm_thread());
3513 }
3514
3515 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3516 void Threads::threads_do(ThreadClosure* tc) {
3517 assert_locked_or_safepoint(Threads_lock);
3518 java_threads_do(tc);
3519 non_java_threads_do(tc);
3520 }
3521
3522 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3523 uintx claim_token = Threads::thread_claim_token();
3524 ALL_JAVA_THREADS(p) {
3525 if (p->claim_threads_do(is_par, claim_token)) {
3526 tc->do_thread(p);
3527 }
3528 }
3529 VMThread* vmt = VMThread::vm_thread();
3530 if (vmt->claim_threads_do(is_par, claim_token)) {
3531 tc->do_thread(vmt);
3532 }
3533 }
3534
3535 // The system initialization in the library has three phases.
3536 //
3537 // Phase 1: java.lang.System class initialization
3538 // java.lang.System is a primordial class loaded and initialized
3539 // by the VM early during startup. java.lang.System.<clinit>
3540 // only does registerNatives and keeps the rest of the class
3541 // initialization work later until thread initialization completes.
3542 //
3543 // System.initPhase1 initializes the system properties, the static
3544 // fields in, out, and err. Set up java signal handlers, OS-specific
3545 // system settings, and thread group of the main thread.
3546 static void call_initPhase1(TRAPS) {
3547 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3548 JavaValue result(T_VOID);
3549 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3550 vmSymbols::void_method_signature(), CHECK);
3551 }
3552
3553 // Phase 2. Module system initialization
3554 // This will initialize the module system. Only java.base classes
3555 // can be loaded until phase 2 completes.
3556 //
3557 // Call System.initPhase2 after the compiler initialization and jsr292
3558 // classes get initialized because module initialization runs a lot of java
3559 // code, that for performance reasons, should be compiled. Also, this will
3560 // enable the startup code to use lambda and other language features in this
3561 // phase and onward.
3562 //
3563 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3564 static void call_initPhase2(TRAPS) {
3565 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3566
3567 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3568
3569 JavaValue result(T_INT);
3570 JavaCallArguments args;
3571 args.push_int(DisplayVMOutputToStderr);
3572 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3573 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3574 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3575 if (result.get_jint() != JNI_OK) {
3576 vm_exit_during_initialization(); // no message or exception
3577 }
3578
3579 universe_post_module_init();
3580 }
3581
3582 // Phase 3. final setup - set security manager, system class loader and TCCL
3583 //
3584 // This will instantiate and set the security manager, set the system class
3585 // loader as well as the thread context class loader. The security manager
3586 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3587 // other modules or the application's classpath.
3588 static void call_initPhase3(TRAPS) {
3589 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3590 JavaValue result(T_VOID);
3591 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3592 vmSymbols::void_method_signature(), CHECK);
3593 }
3594
3595 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3596 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3597
3598 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3599 create_vm_init_libraries();
3600 }
3601
3602 initialize_class(vmSymbols::java_lang_String(), CHECK);
3603
3604 // Inject CompactStrings value after the static initializers for String ran.
3605 java_lang_String::set_compact_strings(CompactStrings);
3606
3607 // Initialize java_lang.System (needed before creating the thread)
3608 initialize_class(vmSymbols::java_lang_System(), CHECK);
3609 // The VM creates & returns objects of this class. Make sure it's initialized.
3610 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3611 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3612 Handle thread_group = create_initial_thread_group(CHECK);
3613 Universe::set_main_thread_group(thread_group());
3614 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3615 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3616 main_thread->set_threadObj(thread_object);
3617
3618 // Set thread status to running since main thread has
3619 // been started and running.
3620 java_lang_Thread::set_thread_status(thread_object,
3621 java_lang_Thread::RUNNABLE);
3622
3623 // The VM creates objects of this class.
3624 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3625
3626 #ifdef ASSERT
3627 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3628 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3629 #endif
3630
3631 // initialize the hardware-specific constants needed by Unsafe
3632 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3633 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3634
3635 // The VM preresolves methods to these classes. Make sure that they get initialized
3636 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3637 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3638
3639 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3640 call_initPhase1(CHECK);
3641
3642 // get the Java runtime name after java.lang.System is initialized
3643 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3644 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3645
3646 // an instance of OutOfMemory exception has been allocated earlier
3647 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3648 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3649 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3650 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3651 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3652 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3653 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3654 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3655 }
3656
3657 void Threads::initialize_jsr292_core_classes(TRAPS) {
3658 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3659
3660 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3661 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3662 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3663 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3664 }
3665
3666 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3667 extern void JDK_Version_init();
3668
3669 // Preinitialize version info.
3670 VM_Version::early_initialize();
3671
3672 // Check version
3673 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3674
3675 // Initialize library-based TLS
3676 ThreadLocalStorage::init();
3677
3678 // Initialize the output stream module
3679 ostream_init();
3680
3681 // Process java launcher properties.
3682 Arguments::process_sun_java_launcher_properties(args);
3683
3684 // Initialize the os module
3685 os::init();
3686
3687 // Record VM creation timing statistics
3688 TraceVmCreationTime create_vm_timer;
3689 create_vm_timer.start();
3690
3691 // Initialize system properties.
3692 Arguments::init_system_properties();
3693
3694 // So that JDK version can be used as a discriminator when parsing arguments
3695 JDK_Version_init();
3696
3697 // Update/Initialize System properties after JDK version number is known
3698 Arguments::init_version_specific_system_properties();
3699
3700 // Make sure to initialize log configuration *before* parsing arguments
3701 LogConfiguration::initialize(create_vm_timer.begin_time());
3702
3703 // Parse arguments
3704 // Note: this internally calls os::init_container_support()
3705 jint parse_result = Arguments::parse(args);
3706 if (parse_result != JNI_OK) return parse_result;
3707
3708 os::init_before_ergo();
3709
3710 jint ergo_result = Arguments::apply_ergo();
3711 if (ergo_result != JNI_OK) return ergo_result;
3712
3713 // Final check of all ranges after ergonomics which may change values.
3714 if (!JVMFlagRangeList::check_ranges()) {
3715 return JNI_EINVAL;
3716 }
3717
3718 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3719 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3720 if (!constraint_result) {
3721 return JNI_EINVAL;
3722 }
3723
3724 JVMFlagWriteableList::mark_startup();
3725
3726 if (PauseAtStartup) {
3727 os::pause();
3728 }
3729
3730 HOTSPOT_VM_INIT_BEGIN();
3731
3732 // Timing (must come after argument parsing)
3733 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3734
3735 // Initialize the os module after parsing the args
3736 jint os_init_2_result = os::init_2();
3737 if (os_init_2_result != JNI_OK) return os_init_2_result;
3738
3739 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3740 // Initialize assert poison page mechanism.
3741 if (ShowRegistersOnAssert) {
3742 initialize_assert_poison();
3743 }
3744 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3745
3746 SafepointMechanism::initialize();
3747
3748 jint adjust_after_os_result = Arguments::adjust_after_os();
3749 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3750
3751 // Initialize output stream logging
3752 ostream_init_log();
3753
3754 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3755 // Must be before create_vm_init_agents()
3756 if (Arguments::init_libraries_at_startup()) {
3757 convert_vm_init_libraries_to_agents();
3758 }
3759
3760 // Launch -agentlib/-agentpath and converted -Xrun agents
3761 if (Arguments::init_agents_at_startup()) {
3762 create_vm_init_agents();
3763 }
3764
3765 // Initialize Threads state
3766 _thread_list = NULL;
3767 _number_of_threads = 0;
3768 _number_of_non_daemon_threads = 0;
3769
3770 // Initialize global data structures and create system classes in heap
3771 vm_init_globals();
3772
3773 #if INCLUDE_JVMCI
3774 if (JVMCICounterSize > 0) {
3775 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3776 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3777 } else {
3778 JavaThread::_jvmci_old_thread_counters = NULL;
3779 }
3780 #endif // INCLUDE_JVMCI
3781
3782 // Attach the main thread to this os thread
3783 JavaThread* main_thread = new JavaThread();
3784 main_thread->set_thread_state(_thread_in_vm);
3785 main_thread->initialize_thread_current();
3786 // must do this before set_active_handles
3787 main_thread->record_stack_base_and_size();
3788 main_thread->register_thread_stack_with_NMT();
3789 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3790
3791 if (!main_thread->set_as_starting_thread()) {
3792 vm_shutdown_during_initialization(
3793 "Failed necessary internal allocation. Out of swap space");
3794 main_thread->smr_delete();
3795 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3796 return JNI_ENOMEM;
3797 }
3798
3799 // Enable guard page *after* os::create_main_thread(), otherwise it would
3800 // crash Linux VM, see notes in os_linux.cpp.
3801 main_thread->create_stack_guard_pages();
3802
3803 // Initialize Java-Level synchronization subsystem
3804 ObjectMonitor::Initialize();
3805
3806 // Initialize global modules
3807 jint status = init_globals();
3808 if (status != JNI_OK) {
3809 main_thread->smr_delete();
3810 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3811 return status;
3812 }
3813
3814 JFR_ONLY(Jfr::on_vm_init();)
3815
3816 // Should be done after the heap is fully created
3817 main_thread->cache_global_variables();
3818
3819 HandleMark hm;
3820
3821 { MutexLocker mu(Threads_lock);
3822 Threads::add(main_thread);
3823 }
3824
3825 // Any JVMTI raw monitors entered in onload will transition into
3826 // real raw monitor. VM is setup enough here for raw monitor enter.
3827 JvmtiExport::transition_pending_onload_raw_monitors();
3828
3829 // Create the VMThread
3830 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3831
3832 VMThread::create();
3833 Thread* vmthread = VMThread::vm_thread();
3834
3835 if (!os::create_thread(vmthread, os::vm_thread)) {
3836 vm_exit_during_initialization("Cannot create VM thread. "
3837 "Out of system resources.");
3838 }
3839
3840 // Wait for the VM thread to become ready, and VMThread::run to initialize
3841 // Monitors can have spurious returns, must always check another state flag
3842 {
3843 MonitorLocker ml(Notify_lock);
3844 os::start_thread(vmthread);
3845 while (vmthread->active_handles() == NULL) {
3846 ml.wait();
3847 }
3848 }
3849 }
3850
3851 assert(Universe::is_fully_initialized(), "not initialized");
3852 if (VerifyDuringStartup) {
3853 // Make sure we're starting with a clean slate.
3854 VM_Verify verify_op;
3855 VMThread::execute(&verify_op);
3856 }
3857
3858 // We need this to update the java.vm.info property in case any flags used
3859 // to initially define it have been changed. This is needed for both CDS and
3860 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3861 // is initially computed. See Abstract_VM_Version::vm_info_string().
3862 // This update must happen before we initialize the java classes, but
3863 // after any initialization logic that might modify the flags.
3864 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3865
3866 Thread* THREAD = Thread::current();
3867
3868 // Always call even when there are not JVMTI environments yet, since environments
3869 // may be attached late and JVMTI must track phases of VM execution
3870 JvmtiExport::enter_early_start_phase();
3871
3872 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3873 JvmtiExport::post_early_vm_start();
3874
3875 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3876
3877 quicken_jni_functions();
3878
3879 // No more stub generation allowed after that point.
3880 StubCodeDesc::freeze();
3881
3882 // Set flag that basic initialization has completed. Used by exceptions and various
3883 // debug stuff, that does not work until all basic classes have been initialized.
3884 set_init_completed();
3885
3886 LogConfiguration::post_initialize();
3887 Metaspace::post_initialize();
3888
3889 HOTSPOT_VM_INIT_END();
3890
3891 // record VM initialization completion time
3892 #if INCLUDE_MANAGEMENT
3893 Management::record_vm_init_completed();
3894 #endif // INCLUDE_MANAGEMENT
3895
3896 // Signal Dispatcher needs to be started before VMInit event is posted
3897 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3898
3899 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3900 if (!DisableAttachMechanism) {
3901 AttachListener::vm_start();
3902 if (StartAttachListener || AttachListener::init_at_startup()) {
3903 AttachListener::init();
3904 }
3905 }
3906
3907 // Launch -Xrun agents
3908 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3909 // back-end can launch with -Xdebug -Xrunjdwp.
3910 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3911 create_vm_init_libraries();
3912 }
3913
3914 if (CleanChunkPoolAsync) {
3915 Chunk::start_chunk_pool_cleaner_task();
3916 }
3917
3918 // initialize compiler(s)
3919 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3920 #if INCLUDE_JVMCI
3921 bool force_JVMCI_intialization = false;
3922 if (EnableJVMCI) {
3923 // Initialize JVMCI eagerly when it is explicitly requested.
3924 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3925 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3926
3927 if (!force_JVMCI_intialization) {
3928 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3929 // compilations via JVMCI will not actually block until JVMCI is initialized.
3930 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3931 }
3932 }
3933 #endif
3934 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3935 // Postpone completion of compiler initialization to after JVMCI
3936 // is initialized to avoid timeouts of blocking compilations.
3937 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3938 CompileBroker::compilation_init_phase2();
3939 }
3940 #endif
3941
3942 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3943 // It is done after compilers are initialized, because otherwise compilations of
3944 // signature polymorphic MH intrinsics can be missed
3945 // (see SystemDictionary::find_method_handle_intrinsic).
3946 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3947
3948 // This will initialize the module system. Only java.base classes can be
3949 // loaded until phase 2 completes
3950 call_initPhase2(CHECK_JNI_ERR);
3951
3952 // Always call even when there are not JVMTI environments yet, since environments
3953 // may be attached late and JVMTI must track phases of VM execution
3954 JvmtiExport::enter_start_phase();
3955
3956 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3957 JvmtiExport::post_vm_start();
3958
3959 // Final system initialization including security manager and system class loader
3960 call_initPhase3(CHECK_JNI_ERR);
3961
3962 // cache the system and platform class loaders
3963 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3964
3965 #if INCLUDE_CDS
3966 if (DumpSharedSpaces) {
3967 // capture the module path info from the ModuleEntryTable
3968 ClassLoader::initialize_module_path(THREAD);
3969 }
3970 #endif
3971
3972 #if INCLUDE_JVMCI
3973 if (force_JVMCI_intialization) {
3974 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3975 CompileBroker::compilation_init_phase2();
3976 }
3977 #endif
3978
3979 // Always call even when there are not JVMTI environments yet, since environments
3980 // may be attached late and JVMTI must track phases of VM execution
3981 JvmtiExport::enter_live_phase();
3982
3983 // Make perfmemory accessible
3984 PerfMemory::set_accessible(true);
3985
3986 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3987 JvmtiExport::post_vm_initialized();
3988
3989 JFR_ONLY(Jfr::on_vm_start();)
3990
3991 #if INCLUDE_MANAGEMENT
3992 Management::initialize(THREAD);
3993
3994 if (HAS_PENDING_EXCEPTION) {
3995 // management agent fails to start possibly due to
3996 // configuration problem and is responsible for printing
3997 // stack trace if appropriate. Simply exit VM.
3998 vm_exit(1);
3999 }
4000 #endif // INCLUDE_MANAGEMENT
4001
4002 if (MemProfiling) MemProfiler::engage();
4003 StatSampler::engage();
4004 if (CheckJNICalls) JniPeriodicChecker::engage();
4005
4006 BiasedLocking::init();
4007
4008 #if INCLUDE_RTM_OPT
4009 RTMLockingCounters::init();
4010 #endif
4011
4012 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4013 call_postVMInitHook(THREAD);
4014 // The Java side of PostVMInitHook.run must deal with all
4015 // exceptions and provide means of diagnosis.
4016 if (HAS_PENDING_EXCEPTION) {
4017 CLEAR_PENDING_EXCEPTION;
4018 }
4019 }
4020
4021 {
4022 MutexLocker ml(PeriodicTask_lock);
4023 // Make sure the WatcherThread can be started by WatcherThread::start()
4024 // or by dynamic enrollment.
4025 WatcherThread::make_startable();
4026 // Start up the WatcherThread if there are any periodic tasks
4027 // NOTE: All PeriodicTasks should be registered by now. If they
4028 // aren't, late joiners might appear to start slowly (we might
4029 // take a while to process their first tick).
4030 if (PeriodicTask::num_tasks() > 0) {
4031 WatcherThread::start();
4032 }
4033 }
4034
4035 create_vm_timer.end();
4036 #ifdef ASSERT
4037 _vm_complete = true;
4038 #endif
4039
4040 if (DumpSharedSpaces) {
4041 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4042 ShouldNotReachHere();
4043 }
4044
4045 return JNI_OK;
4046 }
4047
4048 // type for the Agent_OnLoad and JVM_OnLoad entry points
4049 extern "C" {
4050 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4051 }
4052 // Find a command line agent library and return its entry point for
4053 // -agentlib: -agentpath: -Xrun
4054 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4055 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4056 const char *on_load_symbols[],
4057 size_t num_symbol_entries) {
4058 OnLoadEntry_t on_load_entry = NULL;
4059 void *library = NULL;
4060
4061 if (!agent->valid()) {
4062 char buffer[JVM_MAXPATHLEN];
4063 char ebuf[1024] = "";
4064 const char *name = agent->name();
4065 const char *msg = "Could not find agent library ";
4066
4067 // First check to see if agent is statically linked into executable
4068 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4069 library = agent->os_lib();
4070 } else if (agent->is_absolute_path()) {
4071 library = os::dll_load(name, ebuf, sizeof ebuf);
4072 if (library == NULL) {
4073 const char *sub_msg = " in absolute path, with error: ";
4074 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4075 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4076 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4077 // If we can't find the agent, exit.
4078 vm_exit_during_initialization(buf, NULL);
4079 FREE_C_HEAP_ARRAY(char, buf);
4080 }
4081 } else {
4082 // Try to load the agent from the standard dll directory
4083 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4084 name)) {
4085 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4086 }
4087 if (library == NULL) { // Try the library path directory.
4088 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4089 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4090 }
4091 if (library == NULL) {
4092 const char *sub_msg = " on the library path, with error: ";
4093 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4094
4095 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4096 strlen(ebuf) + strlen(sub_msg2) + 1;
4097 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4098 if (!agent->is_instrument_lib()) {
4099 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4100 } else {
4101 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4102 }
4103 // If we can't find the agent, exit.
4104 vm_exit_during_initialization(buf, NULL);
4105 FREE_C_HEAP_ARRAY(char, buf);
4106 }
4107 }
4108 }
4109 agent->set_os_lib(library);
4110 agent->set_valid();
4111 }
4112
4113 // Find the OnLoad function.
4114 on_load_entry =
4115 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4116 false,
4117 on_load_symbols,
4118 num_symbol_entries));
4119 return on_load_entry;
4120 }
4121
4122 // Find the JVM_OnLoad entry point
4123 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4124 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4125 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4126 }
4127
4128 // Find the Agent_OnLoad entry point
4129 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4130 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4131 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4132 }
4133
4134 // For backwards compatibility with -Xrun
4135 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4136 // treated like -agentpath:
4137 // Must be called before agent libraries are created
4138 void Threads::convert_vm_init_libraries_to_agents() {
4139 AgentLibrary* agent;
4140 AgentLibrary* next;
4141
4142 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4143 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4144 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4145
4146 // If there is an JVM_OnLoad function it will get called later,
4147 // otherwise see if there is an Agent_OnLoad
4148 if (on_load_entry == NULL) {
4149 on_load_entry = lookup_agent_on_load(agent);
4150 if (on_load_entry != NULL) {
4151 // switch it to the agent list -- so that Agent_OnLoad will be called,
4152 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4153 Arguments::convert_library_to_agent(agent);
4154 } else {
4155 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4156 }
4157 }
4158 }
4159 }
4160
4161 // Create agents for -agentlib: -agentpath: and converted -Xrun
4162 // Invokes Agent_OnLoad
4163 // Called very early -- before JavaThreads exist
4164 void Threads::create_vm_init_agents() {
4165 extern struct JavaVM_ main_vm;
4166 AgentLibrary* agent;
4167
4168 JvmtiExport::enter_onload_phase();
4169
4170 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4171 // CDS dumping does not support native JVMTI agent.
4172 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4173 if (DumpSharedSpaces) {
4174 if(!agent->is_instrument_lib()) {
4175 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4176 } else if (!AllowArchivingWithJavaAgent) {
4177 vm_exit_during_cds_dumping(
4178 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4179 }
4180 }
4181
4182 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4183
4184 if (on_load_entry != NULL) {
4185 // Invoke the Agent_OnLoad function
4186 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4187 if (err != JNI_OK) {
4188 vm_exit_during_initialization("agent library failed to init", agent->name());
4189 }
4190 } else {
4191 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4192 }
4193 }
4194
4195 JvmtiExport::enter_primordial_phase();
4196 }
4197
4198 extern "C" {
4199 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4200 }
4201
4202 void Threads::shutdown_vm_agents() {
4203 // Send any Agent_OnUnload notifications
4204 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4205 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4206 extern struct JavaVM_ main_vm;
4207 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4208
4209 // Find the Agent_OnUnload function.
4210 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4211 os::find_agent_function(agent,
4212 false,
4213 on_unload_symbols,
4214 num_symbol_entries));
4215
4216 // Invoke the Agent_OnUnload function
4217 if (unload_entry != NULL) {
4218 JavaThread* thread = JavaThread::current();
4219 ThreadToNativeFromVM ttn(thread);
4220 HandleMark hm(thread);
4221 (*unload_entry)(&main_vm);
4222 }
4223 }
4224 }
4225
4226 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4227 // Invokes JVM_OnLoad
4228 void Threads::create_vm_init_libraries() {
4229 extern struct JavaVM_ main_vm;
4230 AgentLibrary* agent;
4231
4232 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4233 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4234
4235 if (on_load_entry != NULL) {
4236 // Invoke the JVM_OnLoad function
4237 JavaThread* thread = JavaThread::current();
4238 ThreadToNativeFromVM ttn(thread);
4239 HandleMark hm(thread);
4240 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4241 if (err != JNI_OK) {
4242 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4243 }
4244 } else {
4245 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4246 }
4247 }
4248 }
4249
4250
4251 // Last thread running calls java.lang.Shutdown.shutdown()
4252 void JavaThread::invoke_shutdown_hooks() {
4253 HandleMark hm(this);
4254
4255 // We could get here with a pending exception, if so clear it now.
4256 if (this->has_pending_exception()) {
4257 this->clear_pending_exception();
4258 }
4259
4260 EXCEPTION_MARK;
4261 Klass* shutdown_klass =
4262 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4263 THREAD);
4264 if (shutdown_klass != NULL) {
4265 // SystemDictionary::resolve_or_null will return null if there was
4266 // an exception. If we cannot load the Shutdown class, just don't
4267 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4268 // won't be run. Note that if a shutdown hook was registered,
4269 // the Shutdown class would have already been loaded
4270 // (Runtime.addShutdownHook will load it).
4271 JavaValue result(T_VOID);
4272 JavaCalls::call_static(&result,
4273 shutdown_klass,
4274 vmSymbols::shutdown_name(),
4275 vmSymbols::void_method_signature(),
4276 THREAD);
4277 }
4278 CLEAR_PENDING_EXCEPTION;
4279 }
4280
4281 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4282 // the program falls off the end of main(). Another VM exit path is through
4283 // vm_exit() when the program calls System.exit() to return a value or when
4284 // there is a serious error in VM. The two shutdown paths are not exactly
4285 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4286 // and VM_Exit op at VM level.
4287 //
4288 // Shutdown sequence:
4289 // + Shutdown native memory tracking if it is on
4290 // + Wait until we are the last non-daemon thread to execute
4291 // <-- every thing is still working at this moment -->
4292 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4293 // shutdown hooks
4294 // + Call before_exit(), prepare for VM exit
4295 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4296 // currently the only user of this mechanism is File.deleteOnExit())
4297 // > stop StatSampler, watcher thread, CMS threads,
4298 // post thread end and vm death events to JVMTI,
4299 // stop signal thread
4300 // + Call JavaThread::exit(), it will:
4301 // > release JNI handle blocks, remove stack guard pages
4302 // > remove this thread from Threads list
4303 // <-- no more Java code from this thread after this point -->
4304 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4305 // the compiler threads at safepoint
4306 // <-- do not use anything that could get blocked by Safepoint -->
4307 // + Disable tracing at JNI/JVM barriers
4308 // + Set _vm_exited flag for threads that are still running native code
4309 // + Call exit_globals()
4310 // > deletes tty
4311 // > deletes PerfMemory resources
4312 // + Delete this thread
4313 // + Return to caller
4314
4315 bool Threads::destroy_vm() {
4316 JavaThread* thread = JavaThread::current();
4317
4318 #ifdef ASSERT
4319 _vm_complete = false;
4320 #endif
4321 // Wait until we are the last non-daemon thread to execute
4322 { MonitorLocker nu(Threads_lock);
4323 while (Threads::number_of_non_daemon_threads() > 1)
4324 // This wait should make safepoint checks, wait without a timeout,
4325 // and wait as a suspend-equivalent condition.
4326 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4327 }
4328
4329 EventShutdown e;
4330 if (e.should_commit()) {
4331 e.set_reason("No remaining non-daemon Java threads");
4332 e.commit();
4333 }
4334
4335 // Hang forever on exit if we are reporting an error.
4336 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4337 os::infinite_sleep();
4338 }
4339 os::wait_for_keypress_at_exit();
4340
4341 // run Java level shutdown hooks
4342 thread->invoke_shutdown_hooks();
4343
4344 before_exit(thread);
4345
4346 thread->exit(true);
4347
4348 // Stop VM thread.
4349 {
4350 // 4945125 The vm thread comes to a safepoint during exit.
4351 // GC vm_operations can get caught at the safepoint, and the
4352 // heap is unparseable if they are caught. Grab the Heap_lock
4353 // to prevent this. The GC vm_operations will not be able to
4354 // queue until after the vm thread is dead. After this point,
4355 // we'll never emerge out of the safepoint before the VM exits.
4356
4357 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4358
4359 VMThread::wait_for_vm_thread_exit();
4360 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4361 VMThread::destroy();
4362 }
4363
4364 // Now, all Java threads are gone except daemon threads. Daemon threads
4365 // running Java code or in VM are stopped by the Safepoint. However,
4366 // daemon threads executing native code are still running. But they
4367 // will be stopped at native=>Java/VM barriers. Note that we can't
4368 // simply kill or suspend them, as it is inherently deadlock-prone.
4369
4370 VM_Exit::set_vm_exited();
4371
4372 // Clean up ideal graph printers after the VMThread has started
4373 // the final safepoint which will block all the Compiler threads.
4374 // Note that this Thread has already logically exited so the
4375 // clean_up() function's use of a JavaThreadIteratorWithHandle
4376 // would be a problem except set_vm_exited() has remembered the
4377 // shutdown thread which is granted a policy exception.
4378 #if defined(COMPILER2) && !defined(PRODUCT)
4379 IdealGraphPrinter::clean_up();
4380 #endif
4381
4382 notify_vm_shutdown();
4383
4384 // exit_globals() will delete tty
4385 exit_globals();
4386
4387 // We are after VM_Exit::set_vm_exited() so we can't call
4388 // thread->smr_delete() or we will block on the Threads_lock.
4389 // Deleting the shutdown thread here is safe because another
4390 // JavaThread cannot have an active ThreadsListHandle for
4391 // this JavaThread.
4392 delete thread;
4393
4394 #if INCLUDE_JVMCI
4395 if (JVMCICounterSize > 0) {
4396 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4397 }
4398 #endif
4399
4400 LogConfiguration::finalize();
4401
4402 return true;
4403 }
4404
4405
4406 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4407 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4408 return is_supported_jni_version(version);
4409 }
4410
4411
4412 jboolean Threads::is_supported_jni_version(jint version) {
4413 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4414 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4415 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4416 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4417 if (version == JNI_VERSION_9) return JNI_TRUE;
4418 if (version == JNI_VERSION_10) return JNI_TRUE;
4419 return JNI_FALSE;
4420 }
4421
4422
4423 void Threads::add(JavaThread* p, bool force_daemon) {
4424 // The threads lock must be owned at this point
4425 assert(Threads_lock->owned_by_self(), "must have threads lock");
4426
4427 BarrierSet::barrier_set()->on_thread_attach(p);
4428
4429 p->set_next(_thread_list);
4430 _thread_list = p;
4431
4432 // Once a JavaThread is added to the Threads list, smr_delete() has
4433 // to be used to delete it. Otherwise we can just delete it directly.
4434 p->set_on_thread_list();
4435
4436 _number_of_threads++;
4437 oop threadObj = p->threadObj();
4438 bool daemon = true;
4439 // Bootstrapping problem: threadObj can be null for initial
4440 // JavaThread (or for threads attached via JNI)
4441 if ((!force_daemon) && !is_daemon((threadObj))) {
4442 _number_of_non_daemon_threads++;
4443 daemon = false;
4444 }
4445
4446 ThreadService::add_thread(p, daemon);
4447
4448 // Maintain fast thread list
4449 ThreadsSMRSupport::add_thread(p);
4450
4451 // Possible GC point.
4452 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4453 }
4454
4455 void Threads::remove(JavaThread* p, bool is_daemon) {
4456
4457 // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4458 ObjectSynchronizer::omFlush(p);
4459
4460 // Extra scope needed for Thread_lock, so we can check
4461 // that we do not remove thread without safepoint code notice
4462 { MonitorLocker ml(Threads_lock);
4463
4464 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4465
4466 // Maintain fast thread list
4467 ThreadsSMRSupport::remove_thread(p);
4468
4469 JavaThread* current = _thread_list;
4470 JavaThread* prev = NULL;
4471
4472 while (current != p) {
4473 prev = current;
4474 current = current->next();
4475 }
4476
4477 if (prev) {
4478 prev->set_next(current->next());
4479 } else {
4480 _thread_list = p->next();
4481 }
4482
4483 _number_of_threads--;
4484 if (!is_daemon) {
4485 _number_of_non_daemon_threads--;
4486
4487 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4488 // on destroy_vm will wake up.
4489 if (number_of_non_daemon_threads() == 1) {
4490 ml.notify_all();
4491 }
4492 }
4493 ThreadService::remove_thread(p, is_daemon);
4494
4495 // Make sure that safepoint code disregard this thread. This is needed since
4496 // the thread might mess around with locks after this point. This can cause it
4497 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4498 // of this thread since it is removed from the queue.
4499 p->set_terminated_value();
4500 } // unlock Threads_lock
4501
4502 // Since Events::log uses a lock, we grab it outside the Threads_lock
4503 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4504 }
4505
4506 // Operations on the Threads list for GC. These are not explicitly locked,
4507 // but the garbage collector must provide a safe context for them to run.
4508 // In particular, these things should never be called when the Threads_lock
4509 // is held by some other thread. (Note: the Safepoint abstraction also
4510 // uses the Threads_lock to guarantee this property. It also makes sure that
4511 // all threads gets blocked when exiting or starting).
4512
4513 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4514 ALL_JAVA_THREADS(p) {
4515 p->oops_do(f, cf);
4516 }
4517 VMThread::vm_thread()->oops_do(f, cf);
4518 }
4519
4520 void Threads::change_thread_claim_token() {
4521 if (++_thread_claim_token == 0) {
4522 // On overflow of the token counter, there is a risk of future
4523 // collisions between a new global token value and a stale token
4524 // for a thread, because not all iterations visit all threads.
4525 // (Though it's pretty much a theoretical concern for non-trivial
4526 // token counter sizes.) To deal with the possibility, reset all
4527 // the thread tokens to zero on global token overflow.
4528 struct ResetClaims : public ThreadClosure {
4529 virtual void do_thread(Thread* t) {
4530 t->claim_threads_do(false, 0);
4531 }
4532 } reset_claims;
4533 Threads::threads_do(&reset_claims);
4534 // On overflow, update the global token to non-zero, to
4535 // avoid the special "never claimed" initial thread value.
4536 _thread_claim_token = 1;
4537 }
4538 }
4539
4540 #ifdef ASSERT
4541 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4542 const uintx token = t->threads_do_token();
4543 assert(token == expected,
4544 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4545 UINTX_FORMAT, kind, p2i(t), token, expected);
4546 }
4547
4548 void Threads::assert_all_threads_claimed() {
4549 ALL_JAVA_THREADS(p) {
4550 assert_thread_claimed("Thread", p, _thread_claim_token);
4551 }
4552 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4553 }
4554 #endif // ASSERT
4555
4556 class ParallelOopsDoThreadClosure : public ThreadClosure {
4557 private:
4558 OopClosure* _f;
4559 CodeBlobClosure* _cf;
4560 public:
4561 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4562 void do_thread(Thread* t) {
4563 t->oops_do(_f, _cf);
4564 }
4565 };
4566
4567 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4568 ParallelOopsDoThreadClosure tc(f, cf);
4569 possibly_parallel_threads_do(is_par, &tc);
4570 }
4571
4572 void Threads::nmethods_do(CodeBlobClosure* cf) {
4573 ALL_JAVA_THREADS(p) {
4574 // This is used by the code cache sweeper to mark nmethods that are active
4575 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4576 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4577 if(!p->is_Code_cache_sweeper_thread()) {
4578 p->nmethods_do(cf);
4579 }
4580 }
4581 }
4582
4583 void Threads::metadata_do(MetadataClosure* f) {
4584 ALL_JAVA_THREADS(p) {
4585 p->metadata_do(f);
4586 }
4587 }
4588
4589 class ThreadHandlesClosure : public ThreadClosure {
4590 void (*_f)(Metadata*);
4591 public:
4592 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4593 virtual void do_thread(Thread* thread) {
4594 thread->metadata_handles_do(_f);
4595 }
4596 };
4597
4598 void Threads::metadata_handles_do(void f(Metadata*)) {
4599 // Only walk the Handles in Thread.
4600 ThreadHandlesClosure handles_closure(f);
4601 threads_do(&handles_closure);
4602 }
4603
4604 // Get count Java threads that are waiting to enter the specified monitor.
4605 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4606 int count,
4607 address monitor) {
4608 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4609
4610 int i = 0;
4611 DO_JAVA_THREADS(t_list, p) {
4612 if (!p->can_call_java()) continue;
4613
4614 address pending = (address)p->current_pending_monitor();
4615 if (pending == monitor) { // found a match
4616 if (i < count) result->append(p); // save the first count matches
4617 i++;
4618 }
4619 }
4620
4621 return result;
4622 }
4623
4624
4625 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4626 address owner) {
4627 // NULL owner means not locked so we can skip the search
4628 if (owner == NULL) return NULL;
4629
4630 DO_JAVA_THREADS(t_list, p) {
4631 // first, see if owner is the address of a Java thread
4632 if (owner == (address)p) return p;
4633 }
4634
4635 // Cannot assert on lack of success here since this function may be
4636 // used by code that is trying to report useful problem information
4637 // like deadlock detection.
4638 if (UseHeavyMonitors) return NULL;
4639
4640 // If we didn't find a matching Java thread and we didn't force use of
4641 // heavyweight monitors, then the owner is the stack address of the
4642 // Lock Word in the owning Java thread's stack.
4643 //
4644 JavaThread* the_owner = NULL;
4645 DO_JAVA_THREADS(t_list, q) {
4646 if (q->is_lock_owned(owner)) {
4647 the_owner = q;
4648 break;
4649 }
4650 }
4651
4652 // cannot assert on lack of success here; see above comment
4653 return the_owner;
4654 }
4655
4656 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4657 void Threads::print_on(outputStream* st, bool print_stacks,
4658 bool internal_format, bool print_concurrent_locks,
4659 bool print_extended_info) {
4660 char buf[32];
4661 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4662
4663 st->print_cr("Full thread dump %s (%s %s):",
4664 VM_Version::vm_name(),
4665 VM_Version::vm_release(),
4666 VM_Version::vm_info_string());
4667 st->cr();
4668
4669 #if INCLUDE_SERVICES
4670 // Dump concurrent locks
4671 ConcurrentLocksDump concurrent_locks;
4672 if (print_concurrent_locks) {
4673 concurrent_locks.dump_at_safepoint();
4674 }
4675 #endif // INCLUDE_SERVICES
4676
4677 ThreadsSMRSupport::print_info_on(st);
4678 st->cr();
4679
4680 ALL_JAVA_THREADS(p) {
4681 ResourceMark rm;
4682 p->print_on(st, print_extended_info);
4683 if (print_stacks) {
4684 if (internal_format) {
4685 p->trace_stack();
4686 } else {
4687 p->print_stack_on(st);
4688 }
4689 }
4690 st->cr();
4691 #if INCLUDE_SERVICES
4692 if (print_concurrent_locks) {
4693 concurrent_locks.print_locks_on(p, st);
4694 }
4695 #endif // INCLUDE_SERVICES
4696 }
4697
4698 VMThread::vm_thread()->print_on(st);
4699 st->cr();
4700 Universe::heap()->print_gc_threads_on(st);
4701 WatcherThread* wt = WatcherThread::watcher_thread();
4702 if (wt != NULL) {
4703 wt->print_on(st);
4704 st->cr();
4705 }
4706
4707 st->flush();
4708 }
4709
4710 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4711 int buflen, bool* found_current) {
4712 if (this_thread != NULL) {
4713 bool is_current = (current == this_thread);
4714 *found_current = *found_current || is_current;
4715 st->print("%s", is_current ? "=>" : " ");
4716
4717 st->print(PTR_FORMAT, p2i(this_thread));
4718 st->print(" ");
4719 this_thread->print_on_error(st, buf, buflen);
4720 st->cr();
4721 }
4722 }
4723
4724 class PrintOnErrorClosure : public ThreadClosure {
4725 outputStream* _st;
4726 Thread* _current;
4727 char* _buf;
4728 int _buflen;
4729 bool* _found_current;
4730 public:
4731 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4732 int buflen, bool* found_current) :
4733 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4734
4735 virtual void do_thread(Thread* thread) {
4736 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4737 }
4738 };
4739
4740 // Threads::print_on_error() is called by fatal error handler. It's possible
4741 // that VM is not at safepoint and/or current thread is inside signal handler.
4742 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4743 // memory (even in resource area), it might deadlock the error handler.
4744 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4745 int buflen) {
4746 ThreadsSMRSupport::print_info_on(st);
4747 st->cr();
4748
4749 bool found_current = false;
4750 st->print_cr("Java Threads: ( => current thread )");
4751 ALL_JAVA_THREADS(thread) {
4752 print_on_error(thread, st, current, buf, buflen, &found_current);
4753 }
4754 st->cr();
4755
4756 st->print_cr("Other Threads:");
4757 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4758 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4759
4760 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4761 Universe::heap()->gc_threads_do(&print_closure);
4762
4763 if (!found_current) {
4764 st->cr();
4765 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4766 current->print_on_error(st, buf, buflen);
4767 st->cr();
4768 }
4769 st->cr();
4770
4771 st->print_cr("Threads with active compile tasks:");
4772 print_threads_compiling(st, buf, buflen);
4773 }
4774
4775 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4776 ALL_JAVA_THREADS(thread) {
4777 if (thread->is_Compiler_thread()) {
4778 CompilerThread* ct = (CompilerThread*) thread;
4779
4780 // Keep task in local variable for NULL check.
4781 // ct->_task might be set to NULL by concurring compiler thread
4782 // because it completed the compilation. The task is never freed,
4783 // though, just returned to a free list.
4784 CompileTask* task = ct->task();
4785 if (task != NULL) {
4786 thread->print_name_on_error(st, buf, buflen);
4787 st->print(" ");
4788 task->print(st, NULL, short_form, true);
4789 }
4790 }
4791 }
4792 }
4793
4794
4795 // Internal SpinLock and Mutex
4796 // Based on ParkEvent
4797
4798 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4799 //
4800 // We employ SpinLocks _only for low-contention, fixed-length
4801 // short-duration critical sections where we're concerned
4802 // about native mutex_t or HotSpot Mutex:: latency.
4803 // The mux construct provides a spin-then-block mutual exclusion
4804 // mechanism.
4805 //
4806 // Testing has shown that contention on the ListLock guarding gFreeList
4807 // is common. If we implement ListLock as a simple SpinLock it's common
4808 // for the JVM to devolve to yielding with little progress. This is true
4809 // despite the fact that the critical sections protected by ListLock are
4810 // extremely short.
4811 //
4812 // TODO-FIXME: ListLock should be of type SpinLock.
4813 // We should make this a 1st-class type, integrated into the lock
4814 // hierarchy as leaf-locks. Critically, the SpinLock structure
4815 // should have sufficient padding to avoid false-sharing and excessive
4816 // cache-coherency traffic.
4817
4818
4819 typedef volatile int SpinLockT;
4820
4821 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4822 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4823 return; // normal fast-path return
4824 }
4825
4826 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4827 int ctr = 0;
4828 int Yields = 0;
4829 for (;;) {
4830 while (*adr != 0) {
4831 ++ctr;
4832 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4833 if (Yields > 5) {
4834 os::naked_short_sleep(1);
4835 } else {
4836 os::naked_yield();
4837 ++Yields;
4838 }
4839 } else {
4840 SpinPause();
4841 }
4842 }
4843 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4844 }
4845 }
4846
4847 void Thread::SpinRelease(volatile int * adr) {
4848 assert(*adr != 0, "invariant");
4849 OrderAccess::fence(); // guarantee at least release consistency.
4850 // Roach-motel semantics.
4851 // It's safe if subsequent LDs and STs float "up" into the critical section,
4852 // but prior LDs and STs within the critical section can't be allowed
4853 // to reorder or float past the ST that releases the lock.
4854 // Loads and stores in the critical section - which appear in program
4855 // order before the store that releases the lock - must also appear
4856 // before the store that releases the lock in memory visibility order.
4857 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4858 // the ST of 0 into the lock-word which releases the lock, so fence
4859 // more than covers this on all platforms.
4860 *adr = 0;
4861 }
4862
4863 // muxAcquire and muxRelease:
4864 //
4865 // * muxAcquire and muxRelease support a single-word lock-word construct.
4866 // The LSB of the word is set IFF the lock is held.
4867 // The remainder of the word points to the head of a singly-linked list
4868 // of threads blocked on the lock.
4869 //
4870 // * The current implementation of muxAcquire-muxRelease uses its own
4871 // dedicated Thread._MuxEvent instance. If we're interested in
4872 // minimizing the peak number of extant ParkEvent instances then
4873 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4874 // as certain invariants were satisfied. Specifically, care would need
4875 // to be taken with regards to consuming unpark() "permits".
4876 // A safe rule of thumb is that a thread would never call muxAcquire()
4877 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4878 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4879 // consume an unpark() permit intended for monitorenter, for instance.
4880 // One way around this would be to widen the restricted-range semaphore
4881 // implemented in park(). Another alternative would be to provide
4882 // multiple instances of the PlatformEvent() for each thread. One
4883 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4884 //
4885 // * Usage:
4886 // -- Only as leaf locks
4887 // -- for short-term locking only as muxAcquire does not perform
4888 // thread state transitions.
4889 //
4890 // Alternatives:
4891 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4892 // but with parking or spin-then-park instead of pure spinning.
4893 // * Use Taura-Oyama-Yonenzawa locks.
4894 // * It's possible to construct a 1-0 lock if we encode the lockword as
4895 // (List,LockByte). Acquire will CAS the full lockword while Release
4896 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4897 // acquiring threads use timers (ParkTimed) to detect and recover from
4898 // the stranding window. Thread/Node structures must be aligned on 256-byte
4899 // boundaries by using placement-new.
4900 // * Augment MCS with advisory back-link fields maintained with CAS().
4901 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4902 // The validity of the backlinks must be ratified before we trust the value.
4903 // If the backlinks are invalid the exiting thread must back-track through the
4904 // the forward links, which are always trustworthy.
4905 // * Add a successor indication. The LockWord is currently encoded as
4906 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4907 // to provide the usual futile-wakeup optimization.
4908 // See RTStt for details.
4909 //
4910
4911
4912 const intptr_t LOCKBIT = 1;
4913
4914 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4915 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4916 if (w == 0) return;
4917 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4918 return;
4919 }
4920
4921 ParkEvent * const Self = Thread::current()->_MuxEvent;
4922 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4923 for (;;) {
4924 int its = (os::is_MP() ? 100 : 0) + 1;
4925
4926 // Optional spin phase: spin-then-park strategy
4927 while (--its >= 0) {
4928 w = *Lock;
4929 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4930 return;
4931 }
4932 }
4933
4934 Self->reset();
4935 Self->OnList = intptr_t(Lock);
4936 // The following fence() isn't _strictly necessary as the subsequent
4937 // CAS() both serializes execution and ratifies the fetched *Lock value.
4938 OrderAccess::fence();
4939 for (;;) {
4940 w = *Lock;
4941 if ((w & LOCKBIT) == 0) {
4942 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4943 Self->OnList = 0; // hygiene - allows stronger asserts
4944 return;
4945 }
4946 continue; // Interference -- *Lock changed -- Just retry
4947 }
4948 assert(w & LOCKBIT, "invariant");
4949 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4950 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4951 }
4952
4953 while (Self->OnList != 0) {
4954 Self->park();
4955 }
4956 }
4957 }
4958
4959 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4960 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4961 if (w == 0) return;
4962 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4963 return;
4964 }
4965
4966 ParkEvent * ReleaseAfter = NULL;
4967 if (ev == NULL) {
4968 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4969 }
4970 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4971 for (;;) {
4972 guarantee(ev->OnList == 0, "invariant");
4973 int its = (os::is_MP() ? 100 : 0) + 1;
4974
4975 // Optional spin phase: spin-then-park strategy
4976 while (--its >= 0) {
4977 w = *Lock;
4978 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4979 if (ReleaseAfter != NULL) {
4980 ParkEvent::Release(ReleaseAfter);
4981 }
4982 return;
4983 }
4984 }
4985
4986 ev->reset();
4987 ev->OnList = intptr_t(Lock);
4988 // The following fence() isn't _strictly necessary as the subsequent
4989 // CAS() both serializes execution and ratifies the fetched *Lock value.
4990 OrderAccess::fence();
4991 for (;;) {
4992 w = *Lock;
4993 if ((w & LOCKBIT) == 0) {
4994 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4995 ev->OnList = 0;
4996 // We call ::Release while holding the outer lock, thus
4997 // artificially lengthening the critical section.
4998 // Consider deferring the ::Release() until the subsequent unlock(),
4999 // after we've dropped the outer lock.
5000 if (ReleaseAfter != NULL) {
5001 ParkEvent::Release(ReleaseAfter);
5002 }
5003 return;
5004 }
5005 continue; // Interference -- *Lock changed -- Just retry
5006 }
5007 assert(w & LOCKBIT, "invariant");
5008 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5009 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5010 }
5011
5012 while (ev->OnList != 0) {
5013 ev->park();
5014 }
5015 }
5016 }
5017
5018 // Release() must extract a successor from the list and then wake that thread.
5019 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5020 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5021 // Release() would :
5022 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5023 // (B) Extract a successor from the private list "in-hand"
5024 // (C) attempt to CAS() the residual back into *Lock over null.
5025 // If there were any newly arrived threads and the CAS() would fail.
5026 // In that case Release() would detach the RATs, re-merge the list in-hand
5027 // with the RATs and repeat as needed. Alternately, Release() might
5028 // detach and extract a successor, but then pass the residual list to the wakee.
5029 // The wakee would be responsible for reattaching and remerging before it
5030 // competed for the lock.
5031 //
5032 // Both "pop" and DMR are immune from ABA corruption -- there can be
5033 // multiple concurrent pushers, but only one popper or detacher.
5034 // This implementation pops from the head of the list. This is unfair,
5035 // but tends to provide excellent throughput as hot threads remain hot.
5036 // (We wake recently run threads first).
5037 //
5038 // All paths through muxRelease() will execute a CAS.
5039 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5040 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5041 // executed within the critical section are complete and globally visible before the
5042 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5043 void Thread::muxRelease(volatile intptr_t * Lock) {
5044 for (;;) {
5045 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5046 assert(w & LOCKBIT, "invariant");
5047 if (w == LOCKBIT) return;
5048 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5049 assert(List != NULL, "invariant");
5050 assert(List->OnList == intptr_t(Lock), "invariant");
5051 ParkEvent * const nxt = List->ListNext;
5052 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5053
5054 // The following CAS() releases the lock and pops the head element.
5055 // The CAS() also ratifies the previously fetched lock-word value.
5056 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5057 continue;
5058 }
5059 List->OnList = 0;
5060 OrderAccess::fence();
5061 List->unpark();
5062 return;
5063 }
5064 }
5065
5066
5067 void Threads::verify() {
5068 ALL_JAVA_THREADS(p) {
5069 p->verify();
5070 }
5071 VMThread* thread = VMThread::vm_thread();
5072 if (thread != NULL) thread->verify();
5073 }