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