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 size_t 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 om_free_list = NULL;
263 om_free_count = 0;
264 om_free_provision = 32;
265 om_in_use_list = NULL;
266 om_in_use_count = 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(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed");
305 assert(this == _real_malloc_address ||
306 this == align_up(_real_malloc_address, 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 FREE_C_HEAP_ARRAY(char, _name);
1332 _name = NULL;
1333 }
1334
1335 void NamedThread::set_name(const char* format, ...) {
1336 guarantee(_name == NULL, "Only get to set name once.");
1337 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1338 va_list ap;
1339 va_start(ap, format);
1340 jio_vsnprintf(_name, max_name_len, format, ap);
1341 va_end(ap);
1342 }
1343
1344 void NamedThread::print_on(outputStream* st) const {
1345 st->print("\"%s\" ", name());
1346 Thread::print_on(st);
1347 st->cr();
1348 }
1349
1350
1351 // ======= WatcherThread ========
1352
1353 // The watcher thread exists to simulate timer interrupts. It should
1354 // be replaced by an abstraction over whatever native support for
1355 // timer interrupts exists on the platform.
1356
1357 WatcherThread* WatcherThread::_watcher_thread = NULL;
1358 bool WatcherThread::_startable = false;
1359 volatile bool WatcherThread::_should_terminate = false;
1360
1361 WatcherThread::WatcherThread() : NonJavaThread() {
1362 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1363 if (os::create_thread(this, os::watcher_thread)) {
1364 _watcher_thread = this;
1365
1366 // Set the watcher thread to the highest OS priority which should not be
1367 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1368 // is created. The only normal thread using this priority is the reference
1369 // handler thread, which runs for very short intervals only.
1370 // If the VMThread's priority is not lower than the WatcherThread profiling
1371 // will be inaccurate.
1372 os::set_priority(this, MaxPriority);
1373 if (!DisableStartThread) {
1374 os::start_thread(this);
1375 }
1376 }
1377 }
1378
1379 int WatcherThread::sleep() const {
1380 // The WatcherThread does not participate in the safepoint protocol
1381 // for the PeriodicTask_lock because it is not a JavaThread.
1382 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1383
1384 if (_should_terminate) {
1385 // check for termination before we do any housekeeping or wait
1386 return 0; // we did not sleep.
1387 }
1388
1389 // remaining will be zero if there are no tasks,
1390 // causing the WatcherThread to sleep until a task is
1391 // enrolled
1392 int remaining = PeriodicTask::time_to_wait();
1393 int time_slept = 0;
1394
1395 // we expect this to timeout - we only ever get unparked when
1396 // we should terminate or when a new task has been enrolled
1397 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1398
1399 jlong time_before_loop = os::javaTimeNanos();
1400
1401 while (true) {
1402 bool timedout = ml.wait(remaining);
1403 jlong now = os::javaTimeNanos();
1404
1405 if (remaining == 0) {
1406 // if we didn't have any tasks we could have waited for a long time
1407 // consider the time_slept zero and reset time_before_loop
1408 time_slept = 0;
1409 time_before_loop = now;
1410 } else {
1411 // need to recalculate since we might have new tasks in _tasks
1412 time_slept = (int) ((now - time_before_loop) / 1000000);
1413 }
1414
1415 // Change to task list or spurious wakeup of some kind
1416 if (timedout || _should_terminate) {
1417 break;
1418 }
1419
1420 remaining = PeriodicTask::time_to_wait();
1421 if (remaining == 0) {
1422 // Last task was just disenrolled so loop around and wait until
1423 // another task gets enrolled
1424 continue;
1425 }
1426
1427 remaining -= time_slept;
1428 if (remaining <= 0) {
1429 break;
1430 }
1431 }
1432
1433 return time_slept;
1434 }
1435
1436 void WatcherThread::run() {
1437 assert(this == watcher_thread(), "just checking");
1438
1439 this->set_active_handles(JNIHandleBlock::allocate_block());
1440 while (true) {
1441 assert(watcher_thread() == Thread::current(), "thread consistency check");
1442 assert(watcher_thread() == this, "thread consistency check");
1443
1444 // Calculate how long it'll be until the next PeriodicTask work
1445 // should be done, and sleep that amount of time.
1446 int time_waited = sleep();
1447
1448 if (VMError::is_error_reported()) {
1449 // A fatal error has happened, the error handler(VMError::report_and_die)
1450 // should abort JVM after creating an error log file. However in some
1451 // rare cases, the error handler itself might deadlock. Here periodically
1452 // check for error reporting timeouts, and if it happens, just proceed to
1453 // abort the VM.
1454
1455 // This code is in WatcherThread because WatcherThread wakes up
1456 // periodically so the fatal error handler doesn't need to do anything;
1457 // also because the WatcherThread is less likely to crash than other
1458 // threads.
1459
1460 for (;;) {
1461 // Note: we use naked sleep in this loop because we want to avoid using
1462 // any kind of VM infrastructure which may be broken at this point.
1463 if (VMError::check_timeout()) {
1464 // We hit error reporting timeout. Error reporting was interrupted and
1465 // will be wrapping things up now (closing files etc). Give it some more
1466 // time, then quit the VM.
1467 os::naked_short_sleep(200);
1468 // Print a message to stderr.
1469 fdStream err(defaultStream::output_fd());
1470 err.print_raw_cr("# [ timer expired, abort... ]");
1471 // skip atexit/vm_exit/vm_abort hooks
1472 os::die();
1473 }
1474
1475 // Wait a second, then recheck for timeout.
1476 os::naked_short_sleep(999);
1477 }
1478 }
1479
1480 if (_should_terminate) {
1481 // check for termination before posting the next tick
1482 break;
1483 }
1484
1485 PeriodicTask::real_time_tick(time_waited);
1486 }
1487
1488 // Signal that it is terminated
1489 {
1490 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1491 _watcher_thread = NULL;
1492 Terminator_lock->notify_all();
1493 }
1494 }
1495
1496 void WatcherThread::start() {
1497 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1498
1499 if (watcher_thread() == NULL && _startable) {
1500 _should_terminate = false;
1501 // Create the single instance of WatcherThread
1502 new WatcherThread();
1503 }
1504 }
1505
1506 void WatcherThread::make_startable() {
1507 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1508 _startable = true;
1509 }
1510
1511 void WatcherThread::stop() {
1512 {
1513 // Follow normal safepoint aware lock enter protocol since the
1514 // WatcherThread is stopped by another JavaThread.
1515 MutexLocker ml(PeriodicTask_lock);
1516 _should_terminate = true;
1517
1518 WatcherThread* watcher = watcher_thread();
1519 if (watcher != NULL) {
1520 // unpark the WatcherThread so it can see that it should terminate
1521 watcher->unpark();
1522 }
1523 }
1524
1525 MonitorLocker mu(Terminator_lock);
1526
1527 while (watcher_thread() != NULL) {
1528 // This wait should make safepoint checks, wait without a timeout,
1529 // and wait as a suspend-equivalent condition.
1530 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1531 }
1532 }
1533
1534 void WatcherThread::unpark() {
1535 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1536 PeriodicTask_lock->notify();
1537 }
1538
1539 void WatcherThread::print_on(outputStream* st) const {
1540 st->print("\"%s\" ", name());
1541 Thread::print_on(st);
1542 st->cr();
1543 }
1544
1545 // ======= JavaThread ========
1546
1547 #if INCLUDE_JVMCI
1548
1549 jlong* JavaThread::_jvmci_old_thread_counters;
1550
1551 bool jvmci_counters_include(JavaThread* thread) {
1552 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1553 }
1554
1555 void JavaThread::collect_counters(jlong* array, int length) {
1556 assert(length == JVMCICounterSize, "wrong value");
1557 for (int i = 0; i < length; i++) {
1558 array[i] = _jvmci_old_thread_counters[i];
1559 }
1560 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1561 if (jvmci_counters_include(tp)) {
1562 for (int i = 0; i < length; i++) {
1563 array[i] += tp->_jvmci_counters[i];
1564 }
1565 }
1566 }
1567 }
1568
1569 // Attempt to enlarge the array for per thread counters.
1570 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1571 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1572 if (new_counters == NULL) {
1573 return NULL;
1574 }
1575 if (old_counters == NULL) {
1576 old_counters = new_counters;
1577 memset(old_counters, 0, sizeof(jlong) * new_size);
1578 } else {
1579 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1580 new_counters[i] = old_counters[i];
1581 }
1582 if (new_size > current_size) {
1583 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1584 }
1585 FREE_C_HEAP_ARRAY(jlong, old_counters);
1586 }
1587 return new_counters;
1588 }
1589
1590 // Attempt to enlarge the array for per thread counters.
1591 bool JavaThread::resize_counters(int current_size, int new_size) {
1592 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1593 if (new_counters == NULL) {
1594 return false;
1595 } else {
1596 _jvmci_counters = new_counters;
1597 return true;
1598 }
1599 }
1600
1601 class VM_JVMCIResizeCounters : public VM_Operation {
1602 private:
1603 int _new_size;
1604 bool _failed;
1605
1606 public:
1607 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1608 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1609 bool allow_nested_vm_operations() const { return true; }
1610 void doit() {
1611 // Resize the old thread counters array
1612 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1613 if (new_counters == NULL) {
1614 _failed = true;
1615 return;
1616 } else {
1617 JavaThread::_jvmci_old_thread_counters = new_counters;
1618 }
1619
1620 // Now resize each threads array
1621 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1622 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1623 _failed = true;
1624 break;
1625 }
1626 }
1627 if (!_failed) {
1628 JVMCICounterSize = _new_size;
1629 }
1630 }
1631
1632 bool failed() { return _failed; }
1633 };
1634
1635 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1636 VM_JVMCIResizeCounters op(new_size);
1637 VMThread::execute(&op);
1638 return !op.failed();
1639 }
1640
1641 #endif // INCLUDE_JVMCI
1642
1643 // A JavaThread is a normal Java thread
1644
1645 void JavaThread::initialize() {
1646 // Initialize fields
1647
1648 set_saved_exception_pc(NULL);
1649 set_threadObj(NULL);
1650 _anchor.clear();
1651 set_entry_point(NULL);
1652 set_jni_functions(jni_functions());
1653 set_callee_target(NULL);
1654 set_vm_result(NULL);
1655 set_vm_result_2(NULL);
1656 set_vframe_array_head(NULL);
1657 set_vframe_array_last(NULL);
1658 set_deferred_locals(NULL);
1659 set_deopt_mark(NULL);
1660 set_deopt_compiled_method(NULL);
1661 set_monitor_chunks(NULL);
1662 _on_thread_list = false;
1663 set_thread_state(_thread_new);
1664 _terminated = _not_terminated;
1665 _array_for_gc = NULL;
1666 _suspend_equivalent = false;
1667 _in_deopt_handler = 0;
1668 _doing_unsafe_access = false;
1669 _stack_guard_state = stack_guard_unused;
1670 #if INCLUDE_JVMCI
1671 _pending_monitorenter = false;
1672 _pending_deoptimization = -1;
1673 _pending_failed_speculation = 0;
1674 _pending_transfer_to_interpreter = false;
1675 _in_retryable_allocation = false;
1676 _jvmci._alternate_call_target = NULL;
1677 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1678 _jvmci_counters = NULL;
1679 if (JVMCICounterSize > 0) {
1680 resize_counters(0, (int) JVMCICounterSize);
1681 }
1682 #endif // INCLUDE_JVMCI
1683 _reserved_stack_activation = NULL; // stack base not known yet
1684 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1685 _exception_pc = 0;
1686 _exception_handler_pc = 0;
1687 _is_method_handle_return = 0;
1688 _jvmti_thread_state= NULL;
1689 _should_post_on_exceptions_flag = JNI_FALSE;
1690 _interp_only_mode = 0;
1691 _special_runtime_exit_condition = _no_async_condition;
1692 _pending_async_exception = NULL;
1693 _thread_stat = NULL;
1694 _thread_stat = new ThreadStatistics();
1695 _jni_active_critical = 0;
1696 _pending_jni_exception_check_fn = NULL;
1697 _do_not_unlock_if_synchronized = false;
1698 _cached_monitor_info = NULL;
1699 _parker = Parker::Allocate(this);
1700
1701 // Setup safepoint state info for this thread
1702 ThreadSafepointState::create(this);
1703
1704 debug_only(_java_call_counter = 0);
1705
1706 // JVMTI PopFrame support
1707 _popframe_condition = popframe_inactive;
1708 _popframe_preserved_args = NULL;
1709 _popframe_preserved_args_size = 0;
1710 _frames_to_pop_failed_realloc = 0;
1711
1712 if (SafepointMechanism::uses_thread_local_poll()) {
1713 SafepointMechanism::initialize_header(this);
1714 }
1715
1716 _class_to_be_initialized = NULL;
1717
1718 pd_initialize();
1719 }
1720
1721 JavaThread::JavaThread(bool is_attaching_via_jni) :
1722 Thread() {
1723 initialize();
1724 if (is_attaching_via_jni) {
1725 _jni_attach_state = _attaching_via_jni;
1726 } else {
1727 _jni_attach_state = _not_attaching_via_jni;
1728 }
1729 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1730 }
1731
1732 bool JavaThread::reguard_stack(address cur_sp) {
1733 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1734 && _stack_guard_state != stack_guard_reserved_disabled) {
1735 return true; // Stack already guarded or guard pages not needed.
1736 }
1737
1738 if (register_stack_overflow()) {
1739 // For those architectures which have separate register and
1740 // memory stacks, we must check the register stack to see if
1741 // it has overflowed.
1742 return false;
1743 }
1744
1745 // Java code never executes within the yellow zone: the latter is only
1746 // there to provoke an exception during stack banging. If java code
1747 // is executing there, either StackShadowPages should be larger, or
1748 // some exception code in c1, c2 or the interpreter isn't unwinding
1749 // when it should.
1750 guarantee(cur_sp > stack_reserved_zone_base(),
1751 "not enough space to reguard - increase StackShadowPages");
1752 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1753 enable_stack_yellow_reserved_zone();
1754 if (reserved_stack_activation() != stack_base()) {
1755 set_reserved_stack_activation(stack_base());
1756 }
1757 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1758 set_reserved_stack_activation(stack_base());
1759 enable_stack_reserved_zone();
1760 }
1761 return true;
1762 }
1763
1764 bool JavaThread::reguard_stack(void) {
1765 return reguard_stack(os::current_stack_pointer());
1766 }
1767
1768
1769 void JavaThread::block_if_vm_exited() {
1770 if (_terminated == _vm_exited) {
1771 // _vm_exited is set at safepoint, and Threads_lock is never released
1772 // we will block here forever
1773 Threads_lock->lock();
1774 ShouldNotReachHere();
1775 }
1776 }
1777
1778
1779 // Remove this ifdef when C1 is ported to the compiler interface.
1780 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1781 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1782
1783 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1784 Thread() {
1785 initialize();
1786 _jni_attach_state = _not_attaching_via_jni;
1787 set_entry_point(entry_point);
1788 // Create the native thread itself.
1789 // %note runtime_23
1790 os::ThreadType thr_type = os::java_thread;
1791 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1792 os::java_thread;
1793 os::create_thread(this, thr_type, stack_sz);
1794 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1795 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1796 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1797 // the exception consists of creating the exception object & initializing it, initialization
1798 // will leave the VM via a JavaCall and then all locks must be unlocked).
1799 //
1800 // The thread is still suspended when we reach here. Thread must be explicit started
1801 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1802 // by calling Threads:add. The reason why this is not done here, is because the thread
1803 // object must be fully initialized (take a look at JVM_Start)
1804 }
1805
1806 JavaThread::~JavaThread() {
1807
1808 // JSR166 -- return the parker to the free list
1809 Parker::Release(_parker);
1810 _parker = NULL;
1811
1812 // Free any remaining previous UnrollBlock
1813 vframeArray* old_array = vframe_array_last();
1814
1815 if (old_array != NULL) {
1816 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1817 old_array->set_unroll_block(NULL);
1818 delete old_info;
1819 delete old_array;
1820 }
1821
1822 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1823 if (deferred != NULL) {
1824 // This can only happen if thread is destroyed before deoptimization occurs.
1825 assert(deferred->length() != 0, "empty array!");
1826 do {
1827 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1828 deferred->remove_at(0);
1829 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1830 delete dlv;
1831 } while (deferred->length() != 0);
1832 delete deferred;
1833 }
1834
1835 // All Java related clean up happens in exit
1836 ThreadSafepointState::destroy(this);
1837 if (_thread_stat != NULL) delete _thread_stat;
1838
1839 #if INCLUDE_JVMCI
1840 if (JVMCICounterSize > 0) {
1841 if (jvmci_counters_include(this)) {
1842 for (int i = 0; i < JVMCICounterSize; i++) {
1843 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1844 }
1845 }
1846 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1847 }
1848 #endif // INCLUDE_JVMCI
1849 }
1850
1851
1852 // First JavaThread specific code executed by a new Java thread.
1853 void JavaThread::pre_run() {
1854 // empty - see comments in run()
1855 }
1856
1857 // The main routine called by a new Java thread. This isn't overridden
1858 // by subclasses, instead different subclasses define a different "entry_point"
1859 // which defines the actual logic for that kind of thread.
1860 void JavaThread::run() {
1861 // initialize thread-local alloc buffer related fields
1862 this->initialize_tlab();
1863
1864 // Used to test validity of stack trace backs.
1865 // This can't be moved into pre_run() else we invalidate
1866 // the requirement that thread_main_inner is lower on
1867 // the stack. Consequently all the initialization logic
1868 // stays here in run() rather than pre_run().
1869 this->record_base_of_stack_pointer();
1870
1871 this->create_stack_guard_pages();
1872
1873 this->cache_global_variables();
1874
1875 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1876 // in the VM. Change thread state from _thread_new to _thread_in_vm
1877 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1878 // Before a thread is on the threads list it is always safe, so after leaving the
1879 // _thread_new we should emit a instruction barrier. The distance to modified code
1880 // from here is probably far enough, but this is consistent and safe.
1881 OrderAccess::cross_modify_fence();
1882
1883 assert(JavaThread::current() == this, "sanity check");
1884 assert(!Thread::current()->owns_locks(), "sanity check");
1885
1886 DTRACE_THREAD_PROBE(start, this);
1887
1888 // This operation might block. We call that after all safepoint checks for a new thread has
1889 // been completed.
1890 this->set_active_handles(JNIHandleBlock::allocate_block());
1891
1892 if (JvmtiExport::should_post_thread_life()) {
1893 JvmtiExport::post_thread_start(this);
1894
1895 }
1896
1897 // We call another function to do the rest so we are sure that the stack addresses used
1898 // from there will be lower than the stack base just computed.
1899 thread_main_inner();
1900 }
1901
1902 void JavaThread::thread_main_inner() {
1903 assert(JavaThread::current() == this, "sanity check");
1904 assert(this->threadObj() != NULL, "just checking");
1905
1906 // Execute thread entry point unless this thread has a pending exception
1907 // or has been stopped before starting.
1908 // Note: Due to JVM_StopThread we can have pending exceptions already!
1909 if (!this->has_pending_exception() &&
1910 !java_lang_Thread::is_stillborn(this->threadObj())) {
1911 {
1912 ResourceMark rm(this);
1913 this->set_native_thread_name(this->get_thread_name());
1914 }
1915 HandleMark hm(this);
1916 this->entry_point()(this, this);
1917 }
1918
1919 DTRACE_THREAD_PROBE(stop, this);
1920
1921 // Cleanup is handled in post_run()
1922 }
1923
1924 // Shared teardown for all JavaThreads
1925 void JavaThread::post_run() {
1926 this->exit(false);
1927 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1928 // for any shared tear-down.
1929 this->smr_delete();
1930 }
1931
1932 static void ensure_join(JavaThread* thread) {
1933 // We do not need to grab the Threads_lock, since we are operating on ourself.
1934 Handle threadObj(thread, thread->threadObj());
1935 assert(threadObj.not_null(), "java thread object must exist");
1936 ObjectLocker lock(threadObj, thread);
1937 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1938 thread->clear_pending_exception();
1939 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1940 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1941 // Clear the native thread instance - this makes isAlive return false and allows the join()
1942 // to complete once we've done the notify_all below
1943 java_lang_Thread::set_thread(threadObj(), NULL);
1944 lock.notify_all(thread);
1945 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1946 thread->clear_pending_exception();
1947 }
1948
1949 static bool is_daemon(oop threadObj) {
1950 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1951 }
1952
1953 // For any new cleanup additions, please check to see if they need to be applied to
1954 // cleanup_failed_attach_current_thread as well.
1955 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1956 assert(this == JavaThread::current(), "thread consistency check");
1957
1958 elapsedTimer _timer_exit_phase1;
1959 elapsedTimer _timer_exit_phase2;
1960 elapsedTimer _timer_exit_phase3;
1961 elapsedTimer _timer_exit_phase4;
1962
1963 if (log_is_enabled(Debug, os, thread, timer)) {
1964 _timer_exit_phase1.start();
1965 }
1966
1967 HandleMark hm(this);
1968 Handle uncaught_exception(this, this->pending_exception());
1969 this->clear_pending_exception();
1970 Handle threadObj(this, this->threadObj());
1971 assert(threadObj.not_null(), "Java thread object should be created");
1972
1973 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1974 {
1975 EXCEPTION_MARK;
1976
1977 CLEAR_PENDING_EXCEPTION;
1978 }
1979 if (!destroy_vm) {
1980 if (uncaught_exception.not_null()) {
1981 EXCEPTION_MARK;
1982 // Call method Thread.dispatchUncaughtException().
1983 Klass* thread_klass = SystemDictionary::Thread_klass();
1984 JavaValue result(T_VOID);
1985 JavaCalls::call_virtual(&result,
1986 threadObj, thread_klass,
1987 vmSymbols::dispatchUncaughtException_name(),
1988 vmSymbols::throwable_void_signature(),
1989 uncaught_exception,
1990 THREAD);
1991 if (HAS_PENDING_EXCEPTION) {
1992 ResourceMark rm(this);
1993 jio_fprintf(defaultStream::error_stream(),
1994 "\nException: %s thrown from the UncaughtExceptionHandler"
1995 " in thread \"%s\"\n",
1996 pending_exception()->klass()->external_name(),
1997 get_thread_name());
1998 CLEAR_PENDING_EXCEPTION;
1999 }
2000 }
2001 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2002
2003 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2004 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2005 // is deprecated anyhow.
2006 if (!is_Compiler_thread()) {
2007 int count = 3;
2008 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2009 EXCEPTION_MARK;
2010 JavaValue result(T_VOID);
2011 Klass* thread_klass = SystemDictionary::Thread_klass();
2012 JavaCalls::call_virtual(&result,
2013 threadObj, thread_klass,
2014 vmSymbols::exit_method_name(),
2015 vmSymbols::void_method_signature(),
2016 THREAD);
2017 CLEAR_PENDING_EXCEPTION;
2018 }
2019 }
2020 // notify JVMTI
2021 if (JvmtiExport::should_post_thread_life()) {
2022 JvmtiExport::post_thread_end(this);
2023 }
2024
2025 // We have notified the agents that we are exiting, before we go on,
2026 // we must check for a pending external suspend request and honor it
2027 // in order to not surprise the thread that made the suspend request.
2028 while (true) {
2029 {
2030 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2031 if (!is_external_suspend()) {
2032 set_terminated(_thread_exiting);
2033 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2034 break;
2035 }
2036 // Implied else:
2037 // Things get a little tricky here. We have a pending external
2038 // suspend request, but we are holding the SR_lock so we
2039 // can't just self-suspend. So we temporarily drop the lock
2040 // and then self-suspend.
2041 }
2042
2043 ThreadBlockInVM tbivm(this);
2044 java_suspend_self();
2045
2046 // We're done with this suspend request, but we have to loop around
2047 // and check again. Eventually we will get SR_lock without a pending
2048 // external suspend request and will be able to mark ourselves as
2049 // exiting.
2050 }
2051 // no more external suspends are allowed at this point
2052 } else {
2053 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2054 // before_exit() has already posted JVMTI THREAD_END events
2055 }
2056
2057 if (log_is_enabled(Debug, os, thread, timer)) {
2058 _timer_exit_phase1.stop();
2059 _timer_exit_phase2.start();
2060 }
2061
2062 // Capture daemon status before the thread is marked as terminated.
2063 bool daemon = is_daemon(threadObj());
2064
2065 // Notify waiters on thread object. This has to be done after exit() is called
2066 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2067 // group should have the destroyed bit set before waiters are notified).
2068 ensure_join(this);
2069 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2070
2071 if (log_is_enabled(Debug, os, thread, timer)) {
2072 _timer_exit_phase2.stop();
2073 _timer_exit_phase3.start();
2074 }
2075 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2076 // held by this thread must be released. The spec does not distinguish
2077 // between JNI-acquired and regular Java monitors. We can only see
2078 // regular Java monitors here if monitor enter-exit matching is broken.
2079 //
2080 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2081 // ObjectSynchronizer::release_monitors_owned_by_thread().
2082 if (exit_type == jni_detach) {
2083 // Sanity check even though JNI DetachCurrentThread() would have
2084 // returned JNI_ERR if there was a Java frame. JavaThread exit
2085 // should be done executing Java code by the time we get here.
2086 assert(!this->has_last_Java_frame(),
2087 "should not have a Java frame when detaching or exiting");
2088 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2089 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2090 }
2091
2092 // These things needs to be done while we are still a Java Thread. Make sure that thread
2093 // is in a consistent state, in case GC happens
2094 JFR_ONLY(Jfr::on_thread_exit(this);)
2095
2096 if (active_handles() != NULL) {
2097 JNIHandleBlock* block = active_handles();
2098 set_active_handles(NULL);
2099 JNIHandleBlock::release_block(block);
2100 }
2101
2102 if (free_handle_block() != NULL) {
2103 JNIHandleBlock* block = free_handle_block();
2104 set_free_handle_block(NULL);
2105 JNIHandleBlock::release_block(block);
2106 }
2107
2108 // These have to be removed while this is still a valid thread.
2109 remove_stack_guard_pages();
2110
2111 if (UseTLAB) {
2112 tlab().retire();
2113 }
2114
2115 if (JvmtiEnv::environments_might_exist()) {
2116 JvmtiExport::cleanup_thread(this);
2117 }
2118
2119 // We must flush any deferred card marks and other various GC barrier
2120 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2121 // before removing a thread from the list of active threads.
2122 BarrierSet::barrier_set()->on_thread_detach(this);
2123
2124 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2125 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2126 os::current_thread_id());
2127
2128 if (log_is_enabled(Debug, os, thread, timer)) {
2129 _timer_exit_phase3.stop();
2130 _timer_exit_phase4.start();
2131 }
2132 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2133 Threads::remove(this, daemon);
2134
2135 if (log_is_enabled(Debug, os, thread, timer)) {
2136 _timer_exit_phase4.stop();
2137 ResourceMark rm(this);
2138 log_debug(os, thread, timer)("name='%s'"
2139 ", exit-phase1=" JLONG_FORMAT
2140 ", exit-phase2=" JLONG_FORMAT
2141 ", exit-phase3=" JLONG_FORMAT
2142 ", exit-phase4=" JLONG_FORMAT,
2143 get_thread_name(),
2144 _timer_exit_phase1.milliseconds(),
2145 _timer_exit_phase2.milliseconds(),
2146 _timer_exit_phase3.milliseconds(),
2147 _timer_exit_phase4.milliseconds());
2148 }
2149 }
2150
2151 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2152 if (active_handles() != NULL) {
2153 JNIHandleBlock* block = active_handles();
2154 set_active_handles(NULL);
2155 JNIHandleBlock::release_block(block);
2156 }
2157
2158 if (free_handle_block() != NULL) {
2159 JNIHandleBlock* block = free_handle_block();
2160 set_free_handle_block(NULL);
2161 JNIHandleBlock::release_block(block);
2162 }
2163
2164 // These have to be removed while this is still a valid thread.
2165 remove_stack_guard_pages();
2166
2167 if (UseTLAB) {
2168 tlab().retire();
2169 }
2170
2171 BarrierSet::barrier_set()->on_thread_detach(this);
2172
2173 Threads::remove(this, is_daemon);
2174 this->smr_delete();
2175 }
2176
2177 JavaThread* JavaThread::active() {
2178 Thread* thread = Thread::current();
2179 if (thread->is_Java_thread()) {
2180 return (JavaThread*) thread;
2181 } else {
2182 assert(thread->is_VM_thread(), "this must be a vm thread");
2183 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2184 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2185 assert(ret->is_Java_thread(), "must be a Java thread");
2186 return ret;
2187 }
2188 }
2189
2190 bool JavaThread::is_lock_owned(address adr) const {
2191 if (Thread::is_lock_owned(adr)) return true;
2192
2193 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2194 if (chunk->contains(adr)) return true;
2195 }
2196
2197 return false;
2198 }
2199
2200
2201 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2202 chunk->set_next(monitor_chunks());
2203 set_monitor_chunks(chunk);
2204 }
2205
2206 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2207 guarantee(monitor_chunks() != NULL, "must be non empty");
2208 if (monitor_chunks() == chunk) {
2209 set_monitor_chunks(chunk->next());
2210 } else {
2211 MonitorChunk* prev = monitor_chunks();
2212 while (prev->next() != chunk) prev = prev->next();
2213 prev->set_next(chunk->next());
2214 }
2215 }
2216
2217 // JVM support.
2218
2219 // Note: this function shouldn't block if it's called in
2220 // _thread_in_native_trans state (such as from
2221 // check_special_condition_for_native_trans()).
2222 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2223
2224 if (has_last_Java_frame() && has_async_condition()) {
2225 // If we are at a polling page safepoint (not a poll return)
2226 // then we must defer async exception because live registers
2227 // will be clobbered by the exception path. Poll return is
2228 // ok because the call we a returning from already collides
2229 // with exception handling registers and so there is no issue.
2230 // (The exception handling path kills call result registers but
2231 // this is ok since the exception kills the result anyway).
2232
2233 if (is_at_poll_safepoint()) {
2234 // if the code we are returning to has deoptimized we must defer
2235 // the exception otherwise live registers get clobbered on the
2236 // exception path before deoptimization is able to retrieve them.
2237 //
2238 RegisterMap map(this, false);
2239 frame caller_fr = last_frame().sender(&map);
2240 assert(caller_fr.is_compiled_frame(), "what?");
2241 if (caller_fr.is_deoptimized_frame()) {
2242 log_info(exceptions)("deferred async exception at compiled safepoint");
2243 return;
2244 }
2245 }
2246 }
2247
2248 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2249 if (condition == _no_async_condition) {
2250 // Conditions have changed since has_special_runtime_exit_condition()
2251 // was called:
2252 // - if we were here only because of an external suspend request,
2253 // then that was taken care of above (or cancelled) so we are done
2254 // - if we were here because of another async request, then it has
2255 // been cleared between the has_special_runtime_exit_condition()
2256 // and now so again we are done
2257 return;
2258 }
2259
2260 // Check for pending async. exception
2261 if (_pending_async_exception != NULL) {
2262 // Only overwrite an already pending exception, if it is not a threadDeath.
2263 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2264
2265 // We cannot call Exceptions::_throw(...) here because we cannot block
2266 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2267
2268 LogTarget(Info, exceptions) lt;
2269 if (lt.is_enabled()) {
2270 ResourceMark rm;
2271 LogStream ls(lt);
2272 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2273 if (has_last_Java_frame()) {
2274 frame f = last_frame();
2275 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2276 }
2277 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2278 }
2279 _pending_async_exception = NULL;
2280 clear_has_async_exception();
2281 }
2282 }
2283
2284 if (check_unsafe_error &&
2285 condition == _async_unsafe_access_error && !has_pending_exception()) {
2286 condition = _no_async_condition; // done
2287 switch (thread_state()) {
2288 case _thread_in_vm: {
2289 JavaThread* THREAD = this;
2290 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2291 }
2292 case _thread_in_native: {
2293 ThreadInVMfromNative tiv(this);
2294 JavaThread* THREAD = this;
2295 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2296 }
2297 case _thread_in_Java: {
2298 ThreadInVMfromJava tiv(this);
2299 JavaThread* THREAD = this;
2300 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2301 }
2302 default:
2303 ShouldNotReachHere();
2304 }
2305 }
2306
2307 assert(condition == _no_async_condition || has_pending_exception() ||
2308 (!check_unsafe_error && condition == _async_unsafe_access_error),
2309 "must have handled the async condition, if no exception");
2310 }
2311
2312 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2313
2314 // Check for pending external suspend.
2315 if (is_external_suspend_with_lock()) {
2316 frame_anchor()->make_walkable(this);
2317 java_suspend_self_with_safepoint_check();
2318 }
2319
2320 // We might be here for reasons in addition to the self-suspend request
2321 // so check for other async requests.
2322 if (check_asyncs) {
2323 check_and_handle_async_exceptions();
2324 }
2325
2326 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2327 }
2328
2329 void JavaThread::send_thread_stop(oop java_throwable) {
2330 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2331 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2332 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2333
2334 // Do not throw asynchronous exceptions against the compiler thread
2335 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2336 if (!can_call_java()) return;
2337
2338 {
2339 // Actually throw the Throwable against the target Thread - however
2340 // only if there is no thread death exception installed already.
2341 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2342 // If the topmost frame is a runtime stub, then we are calling into
2343 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2344 // must deoptimize the caller before continuing, as the compiled exception handler table
2345 // may not be valid
2346 if (has_last_Java_frame()) {
2347 frame f = last_frame();
2348 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2349 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2350 RegisterMap reg_map(this, UseBiasedLocking);
2351 frame compiled_frame = f.sender(®_map);
2352 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2353 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2354 }
2355 }
2356 }
2357
2358 // Set async. pending exception in thread.
2359 set_pending_async_exception(java_throwable);
2360
2361 if (log_is_enabled(Info, exceptions)) {
2362 ResourceMark rm;
2363 log_info(exceptions)("Pending Async. exception installed of type: %s",
2364 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2365 }
2366 // for AbortVMOnException flag
2367 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2368 }
2369 }
2370
2371
2372 // Interrupt thread so it will wake up from a potential wait()
2373 Thread::interrupt(this);
2374 }
2375
2376 // External suspension mechanism.
2377 //
2378 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2379 // to any VM_locks and it is at a transition
2380 // Self-suspension will happen on the transition out of the vm.
2381 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2382 //
2383 // Guarantees on return:
2384 // + Target thread will not execute any new bytecode (that's why we need to
2385 // force a safepoint)
2386 // + Target thread will not enter any new monitors
2387 //
2388 void JavaThread::java_suspend() {
2389 ThreadsListHandle tlh;
2390 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2391 return;
2392 }
2393
2394 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2395 if (!is_external_suspend()) {
2396 // a racing resume has cancelled us; bail out now
2397 return;
2398 }
2399
2400 // suspend is done
2401 uint32_t debug_bits = 0;
2402 // Warning: is_ext_suspend_completed() may temporarily drop the
2403 // SR_lock to allow the thread to reach a stable thread state if
2404 // it is currently in a transient thread state.
2405 if (is_ext_suspend_completed(false /* !called_by_wait */,
2406 SuspendRetryDelay, &debug_bits)) {
2407 return;
2408 }
2409 }
2410
2411 if (Thread::current() == this) {
2412 // Safely self-suspend.
2413 // If we don't do this explicitly it will implicitly happen
2414 // before we transition back to Java, and on some other thread-state
2415 // transition paths, but not as we exit a JVM TI SuspendThread call.
2416 // As SuspendThread(current) must not return (until resumed) we must
2417 // self-suspend here.
2418 ThreadBlockInVM tbivm(this);
2419 java_suspend_self();
2420 } else {
2421 VM_ThreadSuspend vm_suspend;
2422 VMThread::execute(&vm_suspend);
2423 }
2424 }
2425
2426 // Part II of external suspension.
2427 // A JavaThread self suspends when it detects a pending external suspend
2428 // request. This is usually on transitions. It is also done in places
2429 // where continuing to the next transition would surprise the caller,
2430 // e.g., monitor entry.
2431 //
2432 // Returns the number of times that the thread self-suspended.
2433 //
2434 // Note: DO NOT call java_suspend_self() when you just want to block current
2435 // thread. java_suspend_self() is the second stage of cooperative
2436 // suspension for external suspend requests and should only be used
2437 // to complete an external suspend request.
2438 //
2439 int JavaThread::java_suspend_self() {
2440 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2441 int ret = 0;
2442
2443 // we are in the process of exiting so don't suspend
2444 if (is_exiting()) {
2445 clear_external_suspend();
2446 return ret;
2447 }
2448
2449 assert(_anchor.walkable() ||
2450 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2451 "must have walkable stack");
2452
2453 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2454
2455 assert(!this->is_ext_suspended(),
2456 "a thread trying to self-suspend should not already be suspended");
2457
2458 if (this->is_suspend_equivalent()) {
2459 // If we are self-suspending as a result of the lifting of a
2460 // suspend equivalent condition, then the suspend_equivalent
2461 // flag is not cleared until we set the ext_suspended flag so
2462 // that wait_for_ext_suspend_completion() returns consistent
2463 // results.
2464 this->clear_suspend_equivalent();
2465 }
2466
2467 // A racing resume may have cancelled us before we grabbed SR_lock
2468 // above. Or another external suspend request could be waiting for us
2469 // by the time we return from SR_lock()->wait(). The thread
2470 // that requested the suspension may already be trying to walk our
2471 // stack and if we return now, we can change the stack out from under
2472 // it. This would be a "bad thing (TM)" and cause the stack walker
2473 // to crash. We stay self-suspended until there are no more pending
2474 // external suspend requests.
2475 while (is_external_suspend()) {
2476 ret++;
2477 this->set_ext_suspended();
2478
2479 // _ext_suspended flag is cleared by java_resume()
2480 while (is_ext_suspended()) {
2481 ml.wait();
2482 }
2483 }
2484 return ret;
2485 }
2486
2487 // Helper routine to set up the correct thread state before calling java_suspend_self.
2488 // This is called when regular thread-state transition helpers can't be used because
2489 // we can be in various states, in particular _thread_in_native_trans.
2490 // Because this thread is external suspended the safepoint code will count it as at
2491 // a safepoint, regardless of what its actual current thread-state is. But
2492 // is_ext_suspend_completed() may be waiting to see a thread transition from
2493 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2494 // to _thread_blocked. The problem with setting thread state directly is that a
2495 // safepoint could happen just after java_suspend_self() returns after being resumed,
2496 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2497 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2498 // However, not all initial-states are allowed when performing a safepoint check, as we
2499 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2500 // only _thread_in_native is possible when executing this code (based on our two callers).
2501 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2502 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2503 // and so we don't need the explicit safepoint check.
2504
2505 void JavaThread::java_suspend_self_with_safepoint_check() {
2506 assert(this == Thread::current(), "invariant");
2507 JavaThreadState state = thread_state();
2508 set_thread_state(_thread_blocked);
2509 java_suspend_self();
2510 set_thread_state_fence(state);
2511 // Since we are not using a regular thread-state transition helper here,
2512 // we must manually emit the instruction barrier after leaving a safe state.
2513 OrderAccess::cross_modify_fence();
2514 if (state != _thread_in_native) {
2515 SafepointMechanism::block_if_requested(this);
2516 }
2517 }
2518
2519 #ifdef ASSERT
2520 // Verify the JavaThread has not yet been published in the Threads::list, and
2521 // hence doesn't need protection from concurrent access at this stage.
2522 void JavaThread::verify_not_published() {
2523 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2524 // since an unpublished JavaThread doesn't participate in the
2525 // Thread-SMR protocol for keeping a ThreadsList alive.
2526 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2527 }
2528 #endif
2529
2530 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2531 // progress or when _suspend_flags is non-zero.
2532 // Current thread needs to self-suspend if there is a suspend request and/or
2533 // block if a safepoint is in progress.
2534 // Async exception ISN'T checked.
2535 // Note only the ThreadInVMfromNative transition can call this function
2536 // directly and when thread state is _thread_in_native_trans
2537 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2538 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2539
2540 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2541
2542 if (thread->is_external_suspend()) {
2543 thread->java_suspend_self_with_safepoint_check();
2544 } else {
2545 SafepointMechanism::block_if_requested(thread);
2546 }
2547
2548 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2549 }
2550
2551 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2552 // progress or when _suspend_flags is non-zero.
2553 // Current thread needs to self-suspend if there is a suspend request and/or
2554 // block if a safepoint is in progress.
2555 // Also check for pending async exception (not including unsafe access error).
2556 // Note only the native==>VM/Java barriers can call this function and when
2557 // thread state is _thread_in_native_trans.
2558 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2559 check_safepoint_and_suspend_for_native_trans(thread);
2560
2561 if (thread->has_async_exception()) {
2562 // We are in _thread_in_native_trans state, don't handle unsafe
2563 // access error since that may block.
2564 thread->check_and_handle_async_exceptions(false);
2565 }
2566 }
2567
2568 // This is a variant of the normal
2569 // check_special_condition_for_native_trans with slightly different
2570 // semantics for use by critical native wrappers. It does all the
2571 // normal checks but also performs the transition back into
2572 // thread_in_Java state. This is required so that critical natives
2573 // can potentially block and perform a GC if they are the last thread
2574 // exiting the GCLocker.
2575 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2576 check_special_condition_for_native_trans(thread);
2577
2578 // Finish the transition
2579 thread->set_thread_state(_thread_in_Java);
2580
2581 if (thread->do_critical_native_unlock()) {
2582 ThreadInVMfromJavaNoAsyncException tiv(thread);
2583 GCLocker::unlock_critical(thread);
2584 thread->clear_critical_native_unlock();
2585 }
2586 }
2587
2588 // We need to guarantee the Threads_lock here, since resumes are not
2589 // allowed during safepoint synchronization
2590 // Can only resume from an external suspension
2591 void JavaThread::java_resume() {
2592 assert_locked_or_safepoint(Threads_lock);
2593
2594 // Sanity check: thread is gone, has started exiting or the thread
2595 // was not externally suspended.
2596 ThreadsListHandle tlh;
2597 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2598 return;
2599 }
2600
2601 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2602
2603 clear_external_suspend();
2604
2605 if (is_ext_suspended()) {
2606 clear_ext_suspended();
2607 SR_lock()->notify_all();
2608 }
2609 }
2610
2611 size_t JavaThread::_stack_red_zone_size = 0;
2612 size_t JavaThread::_stack_yellow_zone_size = 0;
2613 size_t JavaThread::_stack_reserved_zone_size = 0;
2614 size_t JavaThread::_stack_shadow_zone_size = 0;
2615
2616 void JavaThread::create_stack_guard_pages() {
2617 if (!os::uses_stack_guard_pages() ||
2618 _stack_guard_state != stack_guard_unused ||
2619 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2620 log_info(os, thread)("Stack guard page creation for thread "
2621 UINTX_FORMAT " disabled", os::current_thread_id());
2622 return;
2623 }
2624 address low_addr = stack_end();
2625 size_t len = stack_guard_zone_size();
2626
2627 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2628 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2629
2630 int must_commit = os::must_commit_stack_guard_pages();
2631 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2632
2633 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2634 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2635 return;
2636 }
2637
2638 if (os::guard_memory((char *) low_addr, len)) {
2639 _stack_guard_state = stack_guard_enabled;
2640 } else {
2641 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2642 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2643 if (os::uncommit_memory((char *) low_addr, len)) {
2644 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2645 }
2646 return;
2647 }
2648
2649 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2650 PTR_FORMAT "-" PTR_FORMAT ".",
2651 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2652 }
2653
2654 void JavaThread::remove_stack_guard_pages() {
2655 assert(Thread::current() == this, "from different thread");
2656 if (_stack_guard_state == stack_guard_unused) return;
2657 address low_addr = stack_end();
2658 size_t len = stack_guard_zone_size();
2659
2660 if (os::must_commit_stack_guard_pages()) {
2661 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2662 _stack_guard_state = stack_guard_unused;
2663 } else {
2664 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2665 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2666 return;
2667 }
2668 } else {
2669 if (_stack_guard_state == stack_guard_unused) return;
2670 if (os::unguard_memory((char *) low_addr, len)) {
2671 _stack_guard_state = stack_guard_unused;
2672 } else {
2673 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2674 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2675 return;
2676 }
2677 }
2678
2679 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2680 PTR_FORMAT "-" PTR_FORMAT ".",
2681 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2682 }
2683
2684 void JavaThread::enable_stack_reserved_zone() {
2685 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2686
2687 // The base notation is from the stack's point of view, growing downward.
2688 // We need to adjust it to work correctly with guard_memory()
2689 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2690
2691 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2692 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2693
2694 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2695 _stack_guard_state = stack_guard_enabled;
2696 } else {
2697 warning("Attempt to guard stack reserved zone failed.");
2698 }
2699 enable_register_stack_guard();
2700 }
2701
2702 void JavaThread::disable_stack_reserved_zone() {
2703 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2704
2705 // Simply return if called for a thread that does not use guard pages.
2706 if (_stack_guard_state != stack_guard_enabled) return;
2707
2708 // The base notation is from the stack's point of view, growing downward.
2709 // We need to adjust it to work correctly with guard_memory()
2710 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2711
2712 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2713 _stack_guard_state = stack_guard_reserved_disabled;
2714 } else {
2715 warning("Attempt to unguard stack reserved zone failed.");
2716 }
2717 disable_register_stack_guard();
2718 }
2719
2720 void JavaThread::enable_stack_yellow_reserved_zone() {
2721 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2722 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2723
2724 // The base notation is from the stacks point of view, growing downward.
2725 // We need to adjust it to work correctly with guard_memory()
2726 address base = stack_red_zone_base();
2727
2728 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2729 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2730
2731 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2732 _stack_guard_state = stack_guard_enabled;
2733 } else {
2734 warning("Attempt to guard stack yellow zone failed.");
2735 }
2736 enable_register_stack_guard();
2737 }
2738
2739 void JavaThread::disable_stack_yellow_reserved_zone() {
2740 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2741 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2742
2743 // Simply return if called for a thread that does not use guard pages.
2744 if (_stack_guard_state == stack_guard_unused) return;
2745
2746 // The base notation is from the stacks point of view, growing downward.
2747 // We need to adjust it to work correctly with guard_memory()
2748 address base = stack_red_zone_base();
2749
2750 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2751 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2752 } else {
2753 warning("Attempt to unguard stack yellow zone failed.");
2754 }
2755 disable_register_stack_guard();
2756 }
2757
2758 void JavaThread::enable_stack_red_zone() {
2759 // The base notation is from the stacks point of view, growing downward.
2760 // We need to adjust it to work correctly with guard_memory()
2761 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2762 address base = stack_red_zone_base() - stack_red_zone_size();
2763
2764 guarantee(base < stack_base(), "Error calculating stack red zone");
2765 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2766
2767 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2768 warning("Attempt to guard stack red zone failed.");
2769 }
2770 }
2771
2772 void JavaThread::disable_stack_red_zone() {
2773 // The base notation is from the stacks point of view, growing downward.
2774 // We need to adjust it to work correctly with guard_memory()
2775 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2776 address base = stack_red_zone_base() - stack_red_zone_size();
2777 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2778 warning("Attempt to unguard stack red zone failed.");
2779 }
2780 }
2781
2782 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2783 // ignore is there is no stack
2784 if (!has_last_Java_frame()) return;
2785 // traverse the stack frames. Starts from top frame.
2786 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2787 frame* fr = fst.current();
2788 f(fr, fst.register_map());
2789 }
2790 }
2791
2792
2793 #ifndef PRODUCT
2794 // Deoptimization
2795 // Function for testing deoptimization
2796 void JavaThread::deoptimize() {
2797 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2798 StackFrameStream fst(this, UseBiasedLocking);
2799 bool deopt = false; // Dump stack only if a deopt actually happens.
2800 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2801 // Iterate over all frames in the thread and deoptimize
2802 for (; !fst.is_done(); fst.next()) {
2803 if (fst.current()->can_be_deoptimized()) {
2804
2805 if (only_at) {
2806 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2807 // consists of comma or carriage return separated numbers so
2808 // search for the current bci in that string.
2809 address pc = fst.current()->pc();
2810 nmethod* nm = (nmethod*) fst.current()->cb();
2811 ScopeDesc* sd = nm->scope_desc_at(pc);
2812 char buffer[8];
2813 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2814 size_t len = strlen(buffer);
2815 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2816 while (found != NULL) {
2817 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2818 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2819 // Check that the bci found is bracketed by terminators.
2820 break;
2821 }
2822 found = strstr(found + 1, buffer);
2823 }
2824 if (!found) {
2825 continue;
2826 }
2827 }
2828
2829 if (DebugDeoptimization && !deopt) {
2830 deopt = true; // One-time only print before deopt
2831 tty->print_cr("[BEFORE Deoptimization]");
2832 trace_frames();
2833 trace_stack();
2834 }
2835 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2836 }
2837 }
2838
2839 if (DebugDeoptimization && deopt) {
2840 tty->print_cr("[AFTER Deoptimization]");
2841 trace_frames();
2842 }
2843 }
2844
2845
2846 // Make zombies
2847 void JavaThread::make_zombies() {
2848 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2849 if (fst.current()->can_be_deoptimized()) {
2850 // it is a Java nmethod
2851 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2852 nm->make_not_entrant();
2853 }
2854 }
2855 }
2856 #endif // PRODUCT
2857
2858
2859 void JavaThread::deoptimized_wrt_marked_nmethods() {
2860 if (!has_last_Java_frame()) return;
2861 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2862 StackFrameStream fst(this, UseBiasedLocking);
2863 for (; !fst.is_done(); fst.next()) {
2864 if (fst.current()->should_be_deoptimized()) {
2865 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2866 }
2867 }
2868 }
2869
2870
2871 // If the caller is a NamedThread, then remember, in the current scope,
2872 // the given JavaThread in its _processed_thread field.
2873 class RememberProcessedThread: public StackObj {
2874 NamedThread* _cur_thr;
2875 public:
2876 RememberProcessedThread(JavaThread* jthr) {
2877 Thread* thread = Thread::current();
2878 if (thread->is_Named_thread()) {
2879 _cur_thr = (NamedThread *)thread;
2880 _cur_thr->set_processed_thread(jthr);
2881 } else {
2882 _cur_thr = NULL;
2883 }
2884 }
2885
2886 ~RememberProcessedThread() {
2887 if (_cur_thr) {
2888 _cur_thr->set_processed_thread(NULL);
2889 }
2890 }
2891 };
2892
2893 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2894 // Verify that the deferred card marks have been flushed.
2895 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2896
2897 // Traverse the GCHandles
2898 Thread::oops_do(f, cf);
2899
2900 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2901 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2902
2903 if (has_last_Java_frame()) {
2904 // Record JavaThread to GC thread
2905 RememberProcessedThread rpt(this);
2906
2907 // traverse the registered growable array
2908 if (_array_for_gc != NULL) {
2909 for (int index = 0; index < _array_for_gc->length(); index++) {
2910 f->do_oop(_array_for_gc->adr_at(index));
2911 }
2912 }
2913
2914 // Traverse the monitor chunks
2915 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2916 chunk->oops_do(f);
2917 }
2918
2919 // Traverse the execution stack
2920 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2921 fst.current()->oops_do(f, cf, fst.register_map());
2922 }
2923 }
2924
2925 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2926 // If we have deferred set_locals there might be oops waiting to be
2927 // written
2928 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2929 if (list != NULL) {
2930 for (int i = 0; i < list->length(); i++) {
2931 list->at(i)->oops_do(f);
2932 }
2933 }
2934
2935 // Traverse instance variables at the end since the GC may be moving things
2936 // around using this function
2937 f->do_oop((oop*) &_threadObj);
2938 f->do_oop((oop*) &_vm_result);
2939 f->do_oop((oop*) &_exception_oop);
2940 f->do_oop((oop*) &_pending_async_exception);
2941
2942 if (jvmti_thread_state() != NULL) {
2943 jvmti_thread_state()->oops_do(f);
2944 }
2945 }
2946
2947 #ifdef ASSERT
2948 void JavaThread::verify_states_for_handshake() {
2949 // This checks that the thread has a correct frame state during a handshake.
2950 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2951 (has_last_Java_frame() && java_call_counter() > 0),
2952 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2953 has_last_Java_frame(), java_call_counter());
2954 }
2955 #endif
2956
2957 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2958 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2959 (has_last_Java_frame() && java_call_counter() > 0),
2960 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2961 has_last_Java_frame(), java_call_counter());
2962
2963 if (has_last_Java_frame()) {
2964 // Traverse the execution stack
2965 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2966 fst.current()->nmethods_do(cf);
2967 }
2968 }
2969 }
2970
2971 void JavaThread::metadata_do(MetadataClosure* f) {
2972 if (has_last_Java_frame()) {
2973 // Traverse the execution stack to call f() on the methods in the stack
2974 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2975 fst.current()->metadata_do(f);
2976 }
2977 } else if (is_Compiler_thread()) {
2978 // need to walk ciMetadata in current compile tasks to keep alive.
2979 CompilerThread* ct = (CompilerThread*)this;
2980 if (ct->env() != NULL) {
2981 ct->env()->metadata_do(f);
2982 }
2983 CompileTask* task = ct->task();
2984 if (task != NULL) {
2985 task->metadata_do(f);
2986 }
2987 }
2988 }
2989
2990 // Printing
2991 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2992 switch (_thread_state) {
2993 case _thread_uninitialized: return "_thread_uninitialized";
2994 case _thread_new: return "_thread_new";
2995 case _thread_new_trans: return "_thread_new_trans";
2996 case _thread_in_native: return "_thread_in_native";
2997 case _thread_in_native_trans: return "_thread_in_native_trans";
2998 case _thread_in_vm: return "_thread_in_vm";
2999 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3000 case _thread_in_Java: return "_thread_in_Java";
3001 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3002 case _thread_blocked: return "_thread_blocked";
3003 case _thread_blocked_trans: return "_thread_blocked_trans";
3004 default: return "unknown thread state";
3005 }
3006 }
3007
3008 #ifndef PRODUCT
3009 void JavaThread::print_thread_state_on(outputStream *st) const {
3010 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3011 };
3012 #endif // PRODUCT
3013
3014 // Called by Threads::print() for VM_PrintThreads operation
3015 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3016 st->print_raw("\"");
3017 st->print_raw(get_thread_name());
3018 st->print_raw("\" ");
3019 oop thread_oop = threadObj();
3020 if (thread_oop != NULL) {
3021 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3022 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3023 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3024 }
3025 Thread::print_on(st, print_extended_info);
3026 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3027 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3028 if (thread_oop != NULL) {
3029 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3030 }
3031 #ifndef PRODUCT
3032 _safepoint_state->print_on(st);
3033 #endif // PRODUCT
3034 if (is_Compiler_thread()) {
3035 CompileTask *task = ((CompilerThread*)this)->task();
3036 if (task != NULL) {
3037 st->print(" Compiling: ");
3038 task->print(st, NULL, true, false);
3039 } else {
3040 st->print(" No compile task");
3041 }
3042 st->cr();
3043 }
3044 }
3045
3046 void JavaThread::print() const { print_on(tty); }
3047
3048 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3049 st->print("%s", get_thread_name_string(buf, buflen));
3050 }
3051
3052 // Called by fatal error handler. The difference between this and
3053 // JavaThread::print() is that we can't grab lock or allocate memory.
3054 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3055 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3056 oop thread_obj = threadObj();
3057 if (thread_obj != NULL) {
3058 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3059 }
3060 st->print(" [");
3061 st->print("%s", _get_thread_state_name(_thread_state));
3062 if (osthread()) {
3063 st->print(", id=%d", osthread()->thread_id());
3064 }
3065 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3066 p2i(stack_end()), p2i(stack_base()));
3067 st->print("]");
3068
3069 ThreadsSMRSupport::print_info_on(this, st);
3070 return;
3071 }
3072
3073 // Verification
3074
3075 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3076
3077 void JavaThread::verify() {
3078 // Verify oops in the thread.
3079 oops_do(&VerifyOopClosure::verify_oop, NULL);
3080
3081 // Verify the stack frames.
3082 frames_do(frame_verify);
3083 }
3084
3085 // CR 6300358 (sub-CR 2137150)
3086 // Most callers of this method assume that it can't return NULL but a
3087 // thread may not have a name whilst it is in the process of attaching to
3088 // the VM - see CR 6412693, and there are places where a JavaThread can be
3089 // seen prior to having it's threadObj set (eg JNI attaching threads and
3090 // if vm exit occurs during initialization). These cases can all be accounted
3091 // for such that this method never returns NULL.
3092 const char* JavaThread::get_thread_name() const {
3093 #ifdef ASSERT
3094 // early safepoints can hit while current thread does not yet have TLS
3095 if (!SafepointSynchronize::is_at_safepoint()) {
3096 Thread *cur = Thread::current();
3097 if (!(cur->is_Java_thread() && cur == this)) {
3098 // Current JavaThreads are allowed to get their own name without
3099 // the Threads_lock.
3100 assert_locked_or_safepoint(Threads_lock);
3101 }
3102 }
3103 #endif // ASSERT
3104 return get_thread_name_string();
3105 }
3106
3107 // Returns a non-NULL representation of this thread's name, or a suitable
3108 // descriptive string if there is no set name
3109 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3110 const char* name_str;
3111 oop thread_obj = threadObj();
3112 if (thread_obj != NULL) {
3113 oop name = java_lang_Thread::name(thread_obj);
3114 if (name != NULL) {
3115 if (buf == NULL) {
3116 name_str = java_lang_String::as_utf8_string(name);
3117 } else {
3118 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3119 }
3120 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3121 name_str = "<no-name - thread is attaching>";
3122 } else {
3123 name_str = Thread::name();
3124 }
3125 } else {
3126 name_str = Thread::name();
3127 }
3128 assert(name_str != NULL, "unexpected NULL thread name");
3129 return name_str;
3130 }
3131
3132 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3133
3134 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3135 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3136 // Link Java Thread object <-> C++ Thread
3137
3138 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3139 // and put it into a new Handle. The Handle "thread_oop" can then
3140 // be used to pass the C++ thread object to other methods.
3141
3142 // Set the Java level thread object (jthread) field of the
3143 // new thread (a JavaThread *) to C++ thread object using the
3144 // "thread_oop" handle.
3145
3146 // Set the thread field (a JavaThread *) of the
3147 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3148
3149 Handle thread_oop(Thread::current(),
3150 JNIHandles::resolve_non_null(jni_thread));
3151 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3152 "must be initialized");
3153 set_threadObj(thread_oop());
3154 java_lang_Thread::set_thread(thread_oop(), this);
3155
3156 if (prio == NoPriority) {
3157 prio = java_lang_Thread::priority(thread_oop());
3158 assert(prio != NoPriority, "A valid priority should be present");
3159 }
3160
3161 // Push the Java priority down to the native thread; needs Threads_lock
3162 Thread::set_priority(this, prio);
3163
3164 // Add the new thread to the Threads list and set it in motion.
3165 // We must have threads lock in order to call Threads::add.
3166 // It is crucial that we do not block before the thread is
3167 // added to the Threads list for if a GC happens, then the java_thread oop
3168 // will not be visited by GC.
3169 Threads::add(this);
3170 }
3171
3172 oop JavaThread::current_park_blocker() {
3173 // Support for JSR-166 locks
3174 oop thread_oop = threadObj();
3175 if (thread_oop != NULL) {
3176 return java_lang_Thread::park_blocker(thread_oop);
3177 }
3178 return NULL;
3179 }
3180
3181
3182 void JavaThread::print_stack_on(outputStream* st) {
3183 if (!has_last_Java_frame()) return;
3184 ResourceMark rm;
3185 HandleMark hm;
3186
3187 RegisterMap reg_map(this);
3188 vframe* start_vf = last_java_vframe(®_map);
3189 int count = 0;
3190 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3191 if (f->is_java_frame()) {
3192 javaVFrame* jvf = javaVFrame::cast(f);
3193 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3194
3195 // Print out lock information
3196 if (JavaMonitorsInStackTrace) {
3197 jvf->print_lock_info_on(st, count);
3198 }
3199 } else {
3200 // Ignore non-Java frames
3201 }
3202
3203 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3204 count++;
3205 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3206 }
3207 }
3208
3209
3210 // JVMTI PopFrame support
3211 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3212 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3213 if (in_bytes(size_in_bytes) != 0) {
3214 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3215 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3216 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3217 }
3218 }
3219
3220 void* JavaThread::popframe_preserved_args() {
3221 return _popframe_preserved_args;
3222 }
3223
3224 ByteSize JavaThread::popframe_preserved_args_size() {
3225 return in_ByteSize(_popframe_preserved_args_size);
3226 }
3227
3228 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3229 int sz = in_bytes(popframe_preserved_args_size());
3230 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3231 return in_WordSize(sz / wordSize);
3232 }
3233
3234 void JavaThread::popframe_free_preserved_args() {
3235 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3236 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
3237 _popframe_preserved_args = NULL;
3238 _popframe_preserved_args_size = 0;
3239 }
3240
3241 #ifndef PRODUCT
3242
3243 void JavaThread::trace_frames() {
3244 tty->print_cr("[Describe stack]");
3245 int frame_no = 1;
3246 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3247 tty->print(" %d. ", frame_no++);
3248 fst.current()->print_value_on(tty, this);
3249 tty->cr();
3250 }
3251 }
3252
3253 class PrintAndVerifyOopClosure: public OopClosure {
3254 protected:
3255 template <class T> inline void do_oop_work(T* p) {
3256 oop obj = RawAccess<>::oop_load(p);
3257 if (obj == NULL) return;
3258 tty->print(INTPTR_FORMAT ": ", p2i(p));
3259 if (oopDesc::is_oop_or_null(obj)) {
3260 if (obj->is_objArray()) {
3261 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3262 } else {
3263 obj->print();
3264 }
3265 } else {
3266 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3267 }
3268 tty->cr();
3269 }
3270 public:
3271 virtual void do_oop(oop* p) { do_oop_work(p); }
3272 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3273 };
3274
3275 #ifdef ASSERT
3276 // Print or validate the layout of stack frames
3277 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3278 ResourceMark rm;
3279 PRESERVE_EXCEPTION_MARK;
3280 FrameValues values;
3281 int frame_no = 0;
3282 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3283 fst.current()->describe(values, ++frame_no);
3284 if (depth == frame_no) break;
3285 }
3286 if (validate_only) {
3287 values.validate();
3288 } else {
3289 tty->print_cr("[Describe stack layout]");
3290 values.print(this);
3291 }
3292 }
3293 #endif
3294
3295 void JavaThread::trace_stack_from(vframe* start_vf) {
3296 ResourceMark rm;
3297 int vframe_no = 1;
3298 for (vframe* f = start_vf; f; f = f->sender()) {
3299 if (f->is_java_frame()) {
3300 javaVFrame::cast(f)->print_activation(vframe_no++);
3301 } else {
3302 f->print();
3303 }
3304 if (vframe_no > StackPrintLimit) {
3305 tty->print_cr("...<more frames>...");
3306 return;
3307 }
3308 }
3309 }
3310
3311
3312 void JavaThread::trace_stack() {
3313 if (!has_last_Java_frame()) return;
3314 ResourceMark rm;
3315 HandleMark hm;
3316 RegisterMap reg_map(this);
3317 trace_stack_from(last_java_vframe(®_map));
3318 }
3319
3320
3321 #endif // PRODUCT
3322
3323
3324 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3325 assert(reg_map != NULL, "a map must be given");
3326 frame f = last_frame();
3327 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3328 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3329 }
3330 return NULL;
3331 }
3332
3333
3334 Klass* JavaThread::security_get_caller_class(int depth) {
3335 vframeStream vfst(this);
3336 vfst.security_get_caller_frame(depth);
3337 if (!vfst.at_end()) {
3338 return vfst.method()->method_holder();
3339 }
3340 return NULL;
3341 }
3342
3343 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3344 assert(thread->is_Compiler_thread(), "must be compiler thread");
3345 CompileBroker::compiler_thread_loop();
3346 }
3347
3348 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3349 NMethodSweeper::sweeper_loop();
3350 }
3351
3352 // Create a CompilerThread
3353 CompilerThread::CompilerThread(CompileQueue* queue,
3354 CompilerCounters* counters)
3355 : JavaThread(&compiler_thread_entry) {
3356 _env = NULL;
3357 _log = NULL;
3358 _task = NULL;
3359 _queue = queue;
3360 _counters = counters;
3361 _buffer_blob = NULL;
3362 _compiler = NULL;
3363
3364 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3365 resource_area()->bias_to(mtCompiler);
3366
3367 #ifndef PRODUCT
3368 _ideal_graph_printer = NULL;
3369 #endif
3370 }
3371
3372 CompilerThread::~CompilerThread() {
3373 // Delete objects which were allocated on heap.
3374 delete _counters;
3375 }
3376
3377 bool CompilerThread::can_call_java() const {
3378 return _compiler != NULL && _compiler->is_jvmci();
3379 }
3380
3381 // Create sweeper thread
3382 CodeCacheSweeperThread::CodeCacheSweeperThread()
3383 : JavaThread(&sweeper_thread_entry) {
3384 _scanned_compiled_method = NULL;
3385 }
3386
3387 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3388 JavaThread::oops_do(f, cf);
3389 if (_scanned_compiled_method != NULL && cf != NULL) {
3390 // Safepoints can occur when the sweeper is scanning an nmethod so
3391 // process it here to make sure it isn't unloaded in the middle of
3392 // a scan.
3393 cf->do_code_blob(_scanned_compiled_method);
3394 }
3395 }
3396
3397 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3398 JavaThread::nmethods_do(cf);
3399 if (_scanned_compiled_method != NULL && cf != NULL) {
3400 // Safepoints can occur when the sweeper is scanning an nmethod so
3401 // process it here to make sure it isn't unloaded in the middle of
3402 // a scan.
3403 cf->do_code_blob(_scanned_compiled_method);
3404 }
3405 }
3406
3407
3408 // ======= Threads ========
3409
3410 // The Threads class links together all active threads, and provides
3411 // operations over all threads. It is protected by the Threads_lock,
3412 // which is also used in other global contexts like safepointing.
3413 // ThreadsListHandles are used to safely perform operations on one
3414 // or more threads without the risk of the thread exiting during the
3415 // operation.
3416 //
3417 // Note: The Threads_lock is currently more widely used than we
3418 // would like. We are actively migrating Threads_lock uses to other
3419 // mechanisms in order to reduce Threads_lock contention.
3420
3421 int Threads::_number_of_threads = 0;
3422 int Threads::_number_of_non_daemon_threads = 0;
3423 int Threads::_return_code = 0;
3424 uintx Threads::_thread_claim_token = 1; // Never zero.
3425 size_t JavaThread::_stack_size_at_create = 0;
3426
3427 #ifdef ASSERT
3428 bool Threads::_vm_complete = false;
3429 #endif
3430
3431 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3432 Prefetch::read((void*)addr, prefetch_interval);
3433 return *addr;
3434 }
3435
3436 // Possibly the ugliest for loop the world has seen. C++ does not allow
3437 // multiple types in the declaration section of the for loop. In this case
3438 // we are only dealing with pointers and hence can cast them. It looks ugly
3439 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3440 #define DO_JAVA_THREADS(LIST, X) \
3441 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3442 *MACRO_list = (JavaThread*)(LIST), \
3443 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3444 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3445 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3446 MACRO_current_p != MACRO_end; \
3447 MACRO_current_p++, \
3448 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3449
3450 // All JavaThreads
3451 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3452
3453 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3454 void Threads::non_java_threads_do(ThreadClosure* tc) {
3455 NoSafepointVerifier nsv;
3456 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3457 tc->do_thread(njti.current());
3458 }
3459 }
3460
3461 // All JavaThreads
3462 void Threads::java_threads_do(ThreadClosure* tc) {
3463 assert_locked_or_safepoint(Threads_lock);
3464 // ALL_JAVA_THREADS iterates through all JavaThreads.
3465 ALL_JAVA_THREADS(p) {
3466 tc->do_thread(p);
3467 }
3468 }
3469
3470 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3471 assert_locked_or_safepoint(Threads_lock);
3472 java_threads_do(tc);
3473 tc->do_thread(VMThread::vm_thread());
3474 }
3475
3476 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3477 void Threads::threads_do(ThreadClosure* tc) {
3478 assert_locked_or_safepoint(Threads_lock);
3479 java_threads_do(tc);
3480 non_java_threads_do(tc);
3481 }
3482
3483 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3484 uintx claim_token = Threads::thread_claim_token();
3485 ALL_JAVA_THREADS(p) {
3486 if (p->claim_threads_do(is_par, claim_token)) {
3487 tc->do_thread(p);
3488 }
3489 }
3490 VMThread* vmt = VMThread::vm_thread();
3491 if (vmt->claim_threads_do(is_par, claim_token)) {
3492 tc->do_thread(vmt);
3493 }
3494 }
3495
3496 // The system initialization in the library has three phases.
3497 //
3498 // Phase 1: java.lang.System class initialization
3499 // java.lang.System is a primordial class loaded and initialized
3500 // by the VM early during startup. java.lang.System.<clinit>
3501 // only does registerNatives and keeps the rest of the class
3502 // initialization work later until thread initialization completes.
3503 //
3504 // System.initPhase1 initializes the system properties, the static
3505 // fields in, out, and err. Set up java signal handlers, OS-specific
3506 // system settings, and thread group of the main thread.
3507 static void call_initPhase1(TRAPS) {
3508 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3509 JavaValue result(T_VOID);
3510 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3511 vmSymbols::void_method_signature(), CHECK);
3512 }
3513
3514 // Phase 2. Module system initialization
3515 // This will initialize the module system. Only java.base classes
3516 // can be loaded until phase 2 completes.
3517 //
3518 // Call System.initPhase2 after the compiler initialization and jsr292
3519 // classes get initialized because module initialization runs a lot of java
3520 // code, that for performance reasons, should be compiled. Also, this will
3521 // enable the startup code to use lambda and other language features in this
3522 // phase and onward.
3523 //
3524 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3525 static void call_initPhase2(TRAPS) {
3526 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3527
3528 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3529
3530 JavaValue result(T_INT);
3531 JavaCallArguments args;
3532 args.push_int(DisplayVMOutputToStderr);
3533 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3534 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3535 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3536 if (result.get_jint() != JNI_OK) {
3537 vm_exit_during_initialization(); // no message or exception
3538 }
3539
3540 universe_post_module_init();
3541 }
3542
3543 // Phase 3. final setup - set security manager, system class loader and TCCL
3544 //
3545 // This will instantiate and set the security manager, set the system class
3546 // loader as well as the thread context class loader. The security manager
3547 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3548 // other modules or the application's classpath.
3549 static void call_initPhase3(TRAPS) {
3550 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3551 JavaValue result(T_VOID);
3552 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3553 vmSymbols::void_method_signature(), CHECK);
3554 }
3555
3556 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3557 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3558
3559 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3560 create_vm_init_libraries();
3561 }
3562
3563 initialize_class(vmSymbols::java_lang_String(), CHECK);
3564
3565 // Inject CompactStrings value after the static initializers for String ran.
3566 java_lang_String::set_compact_strings(CompactStrings);
3567
3568 // Initialize java_lang.System (needed before creating the thread)
3569 initialize_class(vmSymbols::java_lang_System(), CHECK);
3570 // The VM creates & returns objects of this class. Make sure it's initialized.
3571 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3572 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3573 Handle thread_group = create_initial_thread_group(CHECK);
3574 Universe::set_main_thread_group(thread_group());
3575 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3576 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3577 main_thread->set_threadObj(thread_object);
3578
3579 // Set thread status to running since main thread has
3580 // been started and running.
3581 java_lang_Thread::set_thread_status(thread_object,
3582 java_lang_Thread::RUNNABLE);
3583
3584 // The VM creates objects of this class.
3585 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3586
3587 #ifdef ASSERT
3588 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3589 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3590 #endif
3591
3592 // initialize the hardware-specific constants needed by Unsafe
3593 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3594 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3595
3596 // The VM preresolves methods to these classes. Make sure that they get initialized
3597 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3598 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3599
3600 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3601 call_initPhase1(CHECK);
3602
3603 // get the Java runtime name after java.lang.System is initialized
3604 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3605 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3606
3607 // an instance of OutOfMemory exception has been allocated earlier
3608 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3609 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3610 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3611 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3612 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3613 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3614 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3615 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3616
3617 // Eager box cache initialization only if AOT is on and any library is loaded.
3618 AOTLoader::initialize_box_caches(CHECK);
3619 }
3620
3621 void Threads::initialize_jsr292_core_classes(TRAPS) {
3622 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3623
3624 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3625 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3626 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3627 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3628 }
3629
3630 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3631 extern void JDK_Version_init();
3632
3633 // Preinitialize version info.
3634 VM_Version::early_initialize();
3635
3636 // Check version
3637 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3638
3639 // Initialize library-based TLS
3640 ThreadLocalStorage::init();
3641
3642 // Initialize the output stream module
3643 ostream_init();
3644
3645 // Process java launcher properties.
3646 Arguments::process_sun_java_launcher_properties(args);
3647
3648 // Initialize the os module
3649 os::init();
3650
3651 // Record VM creation timing statistics
3652 TraceVmCreationTime create_vm_timer;
3653 create_vm_timer.start();
3654
3655 // Initialize system properties.
3656 Arguments::init_system_properties();
3657
3658 // So that JDK version can be used as a discriminator when parsing arguments
3659 JDK_Version_init();
3660
3661 // Update/Initialize System properties after JDK version number is known
3662 Arguments::init_version_specific_system_properties();
3663
3664 // Make sure to initialize log configuration *before* parsing arguments
3665 LogConfiguration::initialize(create_vm_timer.begin_time());
3666
3667 // Parse arguments
3668 // Note: this internally calls os::init_container_support()
3669 jint parse_result = Arguments::parse(args);
3670 if (parse_result != JNI_OK) return parse_result;
3671
3672 os::init_before_ergo();
3673
3674 jint ergo_result = Arguments::apply_ergo();
3675 if (ergo_result != JNI_OK) return ergo_result;
3676
3677 // Final check of all ranges after ergonomics which may change values.
3678 if (!JVMFlagRangeList::check_ranges()) {
3679 return JNI_EINVAL;
3680 }
3681
3682 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3683 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3684 if (!constraint_result) {
3685 return JNI_EINVAL;
3686 }
3687
3688 JVMFlagWriteableList::mark_startup();
3689
3690 if (PauseAtStartup) {
3691 os::pause();
3692 }
3693
3694 HOTSPOT_VM_INIT_BEGIN();
3695
3696 // Timing (must come after argument parsing)
3697 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3698
3699 // Initialize the os module after parsing the args
3700 jint os_init_2_result = os::init_2();
3701 if (os_init_2_result != JNI_OK) return os_init_2_result;
3702
3703 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3704 // Initialize assert poison page mechanism.
3705 if (ShowRegistersOnAssert) {
3706 initialize_assert_poison();
3707 }
3708 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3709
3710 SafepointMechanism::initialize();
3711
3712 jint adjust_after_os_result = Arguments::adjust_after_os();
3713 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3714
3715 // Initialize output stream logging
3716 ostream_init_log();
3717
3718 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3719 // Must be before create_vm_init_agents()
3720 if (Arguments::init_libraries_at_startup()) {
3721 convert_vm_init_libraries_to_agents();
3722 }
3723
3724 // Launch -agentlib/-agentpath and converted -Xrun agents
3725 if (Arguments::init_agents_at_startup()) {
3726 create_vm_init_agents();
3727 }
3728
3729 // Initialize Threads state
3730 _number_of_threads = 0;
3731 _number_of_non_daemon_threads = 0;
3732
3733 // Initialize global data structures and create system classes in heap
3734 vm_init_globals();
3735
3736 #if INCLUDE_JVMCI
3737 if (JVMCICounterSize > 0) {
3738 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3739 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3740 } else {
3741 JavaThread::_jvmci_old_thread_counters = NULL;
3742 }
3743 #endif // INCLUDE_JVMCI
3744
3745 // Attach the main thread to this os thread
3746 JavaThread* main_thread = new JavaThread();
3747 main_thread->set_thread_state(_thread_in_vm);
3748 main_thread->initialize_thread_current();
3749 // must do this before set_active_handles
3750 main_thread->record_stack_base_and_size();
3751 main_thread->register_thread_stack_with_NMT();
3752 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3753
3754 if (!main_thread->set_as_starting_thread()) {
3755 vm_shutdown_during_initialization(
3756 "Failed necessary internal allocation. Out of swap space");
3757 main_thread->smr_delete();
3758 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3759 return JNI_ENOMEM;
3760 }
3761
3762 // Enable guard page *after* os::create_main_thread(), otherwise it would
3763 // crash Linux VM, see notes in os_linux.cpp.
3764 main_thread->create_stack_guard_pages();
3765
3766 // Initialize Java-Level synchronization subsystem
3767 ObjectMonitor::Initialize();
3768
3769 // Initialize global modules
3770 jint status = init_globals();
3771 if (status != JNI_OK) {
3772 main_thread->smr_delete();
3773 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3774 return status;
3775 }
3776
3777 JFR_ONLY(Jfr::on_vm_init();)
3778
3779 // Should be done after the heap is fully created
3780 main_thread->cache_global_variables();
3781
3782 HandleMark hm;
3783
3784 { MutexLocker mu(Threads_lock);
3785 Threads::add(main_thread);
3786 }
3787
3788 // Any JVMTI raw monitors entered in onload will transition into
3789 // real raw monitor. VM is setup enough here for raw monitor enter.
3790 JvmtiExport::transition_pending_onload_raw_monitors();
3791
3792 // Create the VMThread
3793 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3794
3795 VMThread::create();
3796 Thread* vmthread = VMThread::vm_thread();
3797
3798 if (!os::create_thread(vmthread, os::vm_thread)) {
3799 vm_exit_during_initialization("Cannot create VM thread. "
3800 "Out of system resources.");
3801 }
3802
3803 // Wait for the VM thread to become ready, and VMThread::run to initialize
3804 // Monitors can have spurious returns, must always check another state flag
3805 {
3806 MonitorLocker ml(Notify_lock);
3807 os::start_thread(vmthread);
3808 while (vmthread->active_handles() == NULL) {
3809 ml.wait();
3810 }
3811 }
3812 }
3813
3814 assert(Universe::is_fully_initialized(), "not initialized");
3815 if (VerifyDuringStartup) {
3816 // Make sure we're starting with a clean slate.
3817 VM_Verify verify_op;
3818 VMThread::execute(&verify_op);
3819 }
3820
3821 // We need this to update the java.vm.info property in case any flags used
3822 // to initially define it have been changed. This is needed for both CDS and
3823 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3824 // is initially computed. See Abstract_VM_Version::vm_info_string().
3825 // This update must happen before we initialize the java classes, but
3826 // after any initialization logic that might modify the flags.
3827 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3828
3829 Thread* THREAD = Thread::current();
3830
3831 // Always call even when there are not JVMTI environments yet, since environments
3832 // may be attached late and JVMTI must track phases of VM execution
3833 JvmtiExport::enter_early_start_phase();
3834
3835 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3836 JvmtiExport::post_early_vm_start();
3837
3838 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3839
3840 quicken_jni_functions();
3841
3842 // No more stub generation allowed after that point.
3843 StubCodeDesc::freeze();
3844
3845 // Set flag that basic initialization has completed. Used by exceptions and various
3846 // debug stuff, that does not work until all basic classes have been initialized.
3847 set_init_completed();
3848
3849 LogConfiguration::post_initialize();
3850 Metaspace::post_initialize();
3851
3852 HOTSPOT_VM_INIT_END();
3853
3854 // record VM initialization completion time
3855 #if INCLUDE_MANAGEMENT
3856 Management::record_vm_init_completed();
3857 #endif // INCLUDE_MANAGEMENT
3858
3859 // Signal Dispatcher needs to be started before VMInit event is posted
3860 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3861
3862 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3863 if (!DisableAttachMechanism) {
3864 AttachListener::vm_start();
3865 if (StartAttachListener || AttachListener::init_at_startup()) {
3866 AttachListener::init();
3867 }
3868 }
3869
3870 // Launch -Xrun agents
3871 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3872 // back-end can launch with -Xdebug -Xrunjdwp.
3873 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3874 create_vm_init_libraries();
3875 }
3876
3877 if (CleanChunkPoolAsync) {
3878 Chunk::start_chunk_pool_cleaner_task();
3879 }
3880
3881
3882 // initialize compiler(s)
3883 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3884 #if INCLUDE_JVMCI
3885 bool force_JVMCI_intialization = false;
3886 if (EnableJVMCI) {
3887 // Initialize JVMCI eagerly when it is explicitly requested.
3888 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3889 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3890
3891 if (!force_JVMCI_intialization) {
3892 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3893 // compilations via JVMCI will not actually block until JVMCI is initialized.
3894 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3895 }
3896 }
3897 #endif
3898 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3899 // Postpone completion of compiler initialization to after JVMCI
3900 // is initialized to avoid timeouts of blocking compilations.
3901 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3902 CompileBroker::compilation_init_phase2();
3903 }
3904 #endif
3905
3906 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3907 // It is done after compilers are initialized, because otherwise compilations of
3908 // signature polymorphic MH intrinsics can be missed
3909 // (see SystemDictionary::find_method_handle_intrinsic).
3910 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3911
3912 // This will initialize the module system. Only java.base classes can be
3913 // loaded until phase 2 completes
3914 call_initPhase2(CHECK_JNI_ERR);
3915
3916 // Always call even when there are not JVMTI environments yet, since environments
3917 // may be attached late and JVMTI must track phases of VM execution
3918 JvmtiExport::enter_start_phase();
3919
3920 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3921 JvmtiExport::post_vm_start();
3922
3923 // Final system initialization including security manager and system class loader
3924 call_initPhase3(CHECK_JNI_ERR);
3925
3926 // cache the system and platform class loaders
3927 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3928
3929 #if INCLUDE_CDS
3930 // capture the module path info from the ModuleEntryTable
3931 ClassLoader::initialize_module_path(THREAD);
3932 #endif
3933
3934 #if INCLUDE_JVMCI
3935 if (force_JVMCI_intialization) {
3936 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3937 CompileBroker::compilation_init_phase2();
3938 }
3939 #endif
3940
3941 // Always call even when there are not JVMTI environments yet, since environments
3942 // may be attached late and JVMTI must track phases of VM execution
3943 JvmtiExport::enter_live_phase();
3944
3945 // Make perfmemory accessible
3946 PerfMemory::set_accessible(true);
3947
3948 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3949 JvmtiExport::post_vm_initialized();
3950
3951 JFR_ONLY(Jfr::on_vm_start();)
3952
3953 #if INCLUDE_MANAGEMENT
3954 Management::initialize(THREAD);
3955
3956 if (HAS_PENDING_EXCEPTION) {
3957 // management agent fails to start possibly due to
3958 // configuration problem and is responsible for printing
3959 // stack trace if appropriate. Simply exit VM.
3960 vm_exit(1);
3961 }
3962 #endif // INCLUDE_MANAGEMENT
3963
3964 if (MemProfiling) MemProfiler::engage();
3965 StatSampler::engage();
3966 if (CheckJNICalls) JniPeriodicChecker::engage();
3967
3968 BiasedLocking::init();
3969
3970 #if INCLUDE_RTM_OPT
3971 RTMLockingCounters::init();
3972 #endif
3973
3974 call_postVMInitHook(THREAD);
3975 // The Java side of PostVMInitHook.run must deal with all
3976 // exceptions and provide means of diagnosis.
3977 if (HAS_PENDING_EXCEPTION) {
3978 CLEAR_PENDING_EXCEPTION;
3979 }
3980
3981 {
3982 MutexLocker ml(PeriodicTask_lock);
3983 // Make sure the WatcherThread can be started by WatcherThread::start()
3984 // or by dynamic enrollment.
3985 WatcherThread::make_startable();
3986 // Start up the WatcherThread if there are any periodic tasks
3987 // NOTE: All PeriodicTasks should be registered by now. If they
3988 // aren't, late joiners might appear to start slowly (we might
3989 // take a while to process their first tick).
3990 if (PeriodicTask::num_tasks() > 0) {
3991 WatcherThread::start();
3992 }
3993 }
3994
3995 create_vm_timer.end();
3996 #ifdef ASSERT
3997 _vm_complete = true;
3998 #endif
3999
4000 if (DumpSharedSpaces) {
4001 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4002 ShouldNotReachHere();
4003 }
4004
4005 return JNI_OK;
4006 }
4007
4008 // type for the Agent_OnLoad and JVM_OnLoad entry points
4009 extern "C" {
4010 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4011 }
4012 // Find a command line agent library and return its entry point for
4013 // -agentlib: -agentpath: -Xrun
4014 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4015 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4016 const char *on_load_symbols[],
4017 size_t num_symbol_entries) {
4018 OnLoadEntry_t on_load_entry = NULL;
4019 void *library = NULL;
4020
4021 if (!agent->valid()) {
4022 char buffer[JVM_MAXPATHLEN];
4023 char ebuf[1024] = "";
4024 const char *name = agent->name();
4025 const char *msg = "Could not find agent library ";
4026
4027 // First check to see if agent is statically linked into executable
4028 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4029 library = agent->os_lib();
4030 } else if (agent->is_absolute_path()) {
4031 library = os::dll_load(name, ebuf, sizeof ebuf);
4032 if (library == NULL) {
4033 const char *sub_msg = " in absolute path, with error: ";
4034 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4035 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4036 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4037 // If we can't find the agent, exit.
4038 vm_exit_during_initialization(buf, NULL);
4039 FREE_C_HEAP_ARRAY(char, buf);
4040 }
4041 } else {
4042 // Try to load the agent from the standard dll directory
4043 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4044 name)) {
4045 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4046 }
4047 if (library == NULL) { // Try the library path directory.
4048 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4049 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4050 }
4051 if (library == NULL) {
4052 const char *sub_msg = " on the library path, with error: ";
4053 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4054
4055 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4056 strlen(ebuf) + strlen(sub_msg2) + 1;
4057 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4058 if (!agent->is_instrument_lib()) {
4059 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4060 } else {
4061 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4062 }
4063 // If we can't find the agent, exit.
4064 vm_exit_during_initialization(buf, NULL);
4065 FREE_C_HEAP_ARRAY(char, buf);
4066 }
4067 }
4068 }
4069 agent->set_os_lib(library);
4070 agent->set_valid();
4071 }
4072
4073 // Find the OnLoad function.
4074 on_load_entry =
4075 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4076 false,
4077 on_load_symbols,
4078 num_symbol_entries));
4079 return on_load_entry;
4080 }
4081
4082 // Find the JVM_OnLoad entry point
4083 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4084 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4085 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4086 }
4087
4088 // Find the Agent_OnLoad entry point
4089 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4090 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4091 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4092 }
4093
4094 // For backwards compatibility with -Xrun
4095 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4096 // treated like -agentpath:
4097 // Must be called before agent libraries are created
4098 void Threads::convert_vm_init_libraries_to_agents() {
4099 AgentLibrary* agent;
4100 AgentLibrary* next;
4101
4102 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4103 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4104 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4105
4106 // If there is an JVM_OnLoad function it will get called later,
4107 // otherwise see if there is an Agent_OnLoad
4108 if (on_load_entry == NULL) {
4109 on_load_entry = lookup_agent_on_load(agent);
4110 if (on_load_entry != NULL) {
4111 // switch it to the agent list -- so that Agent_OnLoad will be called,
4112 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4113 Arguments::convert_library_to_agent(agent);
4114 } else {
4115 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4116 }
4117 }
4118 }
4119 }
4120
4121 // Create agents for -agentlib: -agentpath: and converted -Xrun
4122 // Invokes Agent_OnLoad
4123 // Called very early -- before JavaThreads exist
4124 void Threads::create_vm_init_agents() {
4125 extern struct JavaVM_ main_vm;
4126 AgentLibrary* agent;
4127
4128 JvmtiExport::enter_onload_phase();
4129
4130 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4131 // CDS dumping does not support native JVMTI agent.
4132 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4133 if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4134 if(!agent->is_instrument_lib()) {
4135 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4136 } else if (!AllowArchivingWithJavaAgent) {
4137 vm_exit_during_cds_dumping(
4138 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4139 }
4140 }
4141
4142 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4143
4144 if (on_load_entry != NULL) {
4145 // Invoke the Agent_OnLoad function
4146 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4147 if (err != JNI_OK) {
4148 vm_exit_during_initialization("agent library failed to init", agent->name());
4149 }
4150 } else {
4151 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4152 }
4153 }
4154
4155 JvmtiExport::enter_primordial_phase();
4156 }
4157
4158 extern "C" {
4159 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4160 }
4161
4162 void Threads::shutdown_vm_agents() {
4163 // Send any Agent_OnUnload notifications
4164 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4165 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4166 extern struct JavaVM_ main_vm;
4167 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4168
4169 // Find the Agent_OnUnload function.
4170 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4171 os::find_agent_function(agent,
4172 false,
4173 on_unload_symbols,
4174 num_symbol_entries));
4175
4176 // Invoke the Agent_OnUnload function
4177 if (unload_entry != NULL) {
4178 JavaThread* thread = JavaThread::current();
4179 ThreadToNativeFromVM ttn(thread);
4180 HandleMark hm(thread);
4181 (*unload_entry)(&main_vm);
4182 }
4183 }
4184 }
4185
4186 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4187 // Invokes JVM_OnLoad
4188 void Threads::create_vm_init_libraries() {
4189 extern struct JavaVM_ main_vm;
4190 AgentLibrary* agent;
4191
4192 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4193 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4194
4195 if (on_load_entry != NULL) {
4196 // Invoke the JVM_OnLoad function
4197 JavaThread* thread = JavaThread::current();
4198 ThreadToNativeFromVM ttn(thread);
4199 HandleMark hm(thread);
4200 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4201 if (err != JNI_OK) {
4202 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4203 }
4204 } else {
4205 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4206 }
4207 }
4208 }
4209
4210
4211 // Last thread running calls java.lang.Shutdown.shutdown()
4212 void JavaThread::invoke_shutdown_hooks() {
4213 HandleMark hm(this);
4214
4215 // We could get here with a pending exception, if so clear it now.
4216 if (this->has_pending_exception()) {
4217 this->clear_pending_exception();
4218 }
4219
4220 EXCEPTION_MARK;
4221 Klass* shutdown_klass =
4222 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4223 THREAD);
4224 if (shutdown_klass != NULL) {
4225 // SystemDictionary::resolve_or_null will return null if there was
4226 // an exception. If we cannot load the Shutdown class, just don't
4227 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4228 // won't be run. Note that if a shutdown hook was registered,
4229 // the Shutdown class would have already been loaded
4230 // (Runtime.addShutdownHook will load it).
4231 JavaValue result(T_VOID);
4232 JavaCalls::call_static(&result,
4233 shutdown_klass,
4234 vmSymbols::shutdown_name(),
4235 vmSymbols::void_method_signature(),
4236 THREAD);
4237 }
4238 CLEAR_PENDING_EXCEPTION;
4239 }
4240
4241 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4242 // the program falls off the end of main(). Another VM exit path is through
4243 // vm_exit() when the program calls System.exit() to return a value or when
4244 // there is a serious error in VM. The two shutdown paths are not exactly
4245 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4246 // and VM_Exit op at VM level.
4247 //
4248 // Shutdown sequence:
4249 // + Shutdown native memory tracking if it is on
4250 // + Wait until we are the last non-daemon thread to execute
4251 // <-- every thing is still working at this moment -->
4252 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4253 // shutdown hooks
4254 // + Call before_exit(), prepare for VM exit
4255 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4256 // currently the only user of this mechanism is File.deleteOnExit())
4257 // > stop StatSampler, watcher thread, CMS threads,
4258 // post thread end and vm death events to JVMTI,
4259 // stop signal thread
4260 // + Call JavaThread::exit(), it will:
4261 // > release JNI handle blocks, remove stack guard pages
4262 // > remove this thread from Threads list
4263 // <-- no more Java code from this thread after this point -->
4264 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4265 // the compiler threads at safepoint
4266 // <-- do not use anything that could get blocked by Safepoint -->
4267 // + Disable tracing at JNI/JVM barriers
4268 // + Set _vm_exited flag for threads that are still running native code
4269 // + Call exit_globals()
4270 // > deletes tty
4271 // > deletes PerfMemory resources
4272 // + Delete this thread
4273 // + Return to caller
4274
4275 bool Threads::destroy_vm() {
4276 JavaThread* thread = JavaThread::current();
4277
4278 #ifdef ASSERT
4279 _vm_complete = false;
4280 #endif
4281 // Wait until we are the last non-daemon thread to execute
4282 { MonitorLocker nu(Threads_lock);
4283 while (Threads::number_of_non_daemon_threads() > 1)
4284 // This wait should make safepoint checks, wait without a timeout,
4285 // and wait as a suspend-equivalent condition.
4286 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4287 }
4288
4289 EventShutdown e;
4290 if (e.should_commit()) {
4291 e.set_reason("No remaining non-daemon Java threads");
4292 e.commit();
4293 }
4294
4295 // Hang forever on exit if we are reporting an error.
4296 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4297 os::infinite_sleep();
4298 }
4299 os::wait_for_keypress_at_exit();
4300
4301 // run Java level shutdown hooks
4302 thread->invoke_shutdown_hooks();
4303
4304 before_exit(thread);
4305
4306 thread->exit(true);
4307
4308 // Stop VM thread.
4309 {
4310 // 4945125 The vm thread comes to a safepoint during exit.
4311 // GC vm_operations can get caught at the safepoint, and the
4312 // heap is unparseable if they are caught. Grab the Heap_lock
4313 // to prevent this. The GC vm_operations will not be able to
4314 // queue until after the vm thread is dead. After this point,
4315 // we'll never emerge out of the safepoint before the VM exits.
4316
4317 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4318
4319 VMThread::wait_for_vm_thread_exit();
4320 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4321 VMThread::destroy();
4322 }
4323
4324 // Now, all Java threads are gone except daemon threads. Daemon threads
4325 // running Java code or in VM are stopped by the Safepoint. However,
4326 // daemon threads executing native code are still running. But they
4327 // will be stopped at native=>Java/VM barriers. Note that we can't
4328 // simply kill or suspend them, as it is inherently deadlock-prone.
4329
4330 VM_Exit::set_vm_exited();
4331
4332 // Clean up ideal graph printers after the VMThread has started
4333 // the final safepoint which will block all the Compiler threads.
4334 // Note that this Thread has already logically exited so the
4335 // clean_up() function's use of a JavaThreadIteratorWithHandle
4336 // would be a problem except set_vm_exited() has remembered the
4337 // shutdown thread which is granted a policy exception.
4338 #if defined(COMPILER2) && !defined(PRODUCT)
4339 IdealGraphPrinter::clean_up();
4340 #endif
4341
4342 notify_vm_shutdown();
4343
4344 // exit_globals() will delete tty
4345 exit_globals();
4346
4347 // We are after VM_Exit::set_vm_exited() so we can't call
4348 // thread->smr_delete() or we will block on the Threads_lock.
4349 // Deleting the shutdown thread here is safe because another
4350 // JavaThread cannot have an active ThreadsListHandle for
4351 // this JavaThread.
4352 delete thread;
4353
4354 #if INCLUDE_JVMCI
4355 if (JVMCICounterSize > 0) {
4356 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4357 }
4358 #endif
4359
4360 LogConfiguration::finalize();
4361
4362 return true;
4363 }
4364
4365
4366 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4367 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4368 return is_supported_jni_version(version);
4369 }
4370
4371
4372 jboolean Threads::is_supported_jni_version(jint version) {
4373 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4374 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4375 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4376 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4377 if (version == JNI_VERSION_9) return JNI_TRUE;
4378 if (version == JNI_VERSION_10) return JNI_TRUE;
4379 return JNI_FALSE;
4380 }
4381
4382
4383 void Threads::add(JavaThread* p, bool force_daemon) {
4384 // The threads lock must be owned at this point
4385 assert(Threads_lock->owned_by_self(), "must have threads lock");
4386
4387 BarrierSet::barrier_set()->on_thread_attach(p);
4388
4389 // Once a JavaThread is added to the Threads list, smr_delete() has
4390 // to be used to delete it. Otherwise we can just delete it directly.
4391 p->set_on_thread_list();
4392
4393 _number_of_threads++;
4394 oop threadObj = p->threadObj();
4395 bool daemon = true;
4396 // Bootstrapping problem: threadObj can be null for initial
4397 // JavaThread (or for threads attached via JNI)
4398 if ((!force_daemon) && !is_daemon((threadObj))) {
4399 _number_of_non_daemon_threads++;
4400 daemon = false;
4401 }
4402
4403 ThreadService::add_thread(p, daemon);
4404
4405 // Maintain fast thread list
4406 ThreadsSMRSupport::add_thread(p);
4407
4408 // Possible GC point.
4409 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4410 }
4411
4412 void Threads::remove(JavaThread* p, bool is_daemon) {
4413
4414 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4415 ObjectSynchronizer::om_flush(p);
4416
4417 // Extra scope needed for Thread_lock, so we can check
4418 // that we do not remove thread without safepoint code notice
4419 { MonitorLocker ml(Threads_lock);
4420
4421 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4422
4423 // Maintain fast thread list
4424 ThreadsSMRSupport::remove_thread(p);
4425
4426 _number_of_threads--;
4427 if (!is_daemon) {
4428 _number_of_non_daemon_threads--;
4429
4430 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4431 // on destroy_vm will wake up.
4432 if (number_of_non_daemon_threads() == 1) {
4433 ml.notify_all();
4434 }
4435 }
4436 ThreadService::remove_thread(p, is_daemon);
4437
4438 // Make sure that safepoint code disregard this thread. This is needed since
4439 // the thread might mess around with locks after this point. This can cause it
4440 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4441 // of this thread since it is removed from the queue.
4442 p->set_terminated_value();
4443 } // unlock Threads_lock
4444
4445 // Since Events::log uses a lock, we grab it outside the Threads_lock
4446 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4447 }
4448
4449 // Operations on the Threads list for GC. These are not explicitly locked,
4450 // but the garbage collector must provide a safe context for them to run.
4451 // In particular, these things should never be called when the Threads_lock
4452 // is held by some other thread. (Note: the Safepoint abstraction also
4453 // uses the Threads_lock to guarantee this property. It also makes sure that
4454 // all threads gets blocked when exiting or starting).
4455
4456 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4457 ALL_JAVA_THREADS(p) {
4458 p->oops_do(f, cf);
4459 }
4460 VMThread::vm_thread()->oops_do(f, cf);
4461 }
4462
4463 void Threads::change_thread_claim_token() {
4464 if (++_thread_claim_token == 0) {
4465 // On overflow of the token counter, there is a risk of future
4466 // collisions between a new global token value and a stale token
4467 // for a thread, because not all iterations visit all threads.
4468 // (Though it's pretty much a theoretical concern for non-trivial
4469 // token counter sizes.) To deal with the possibility, reset all
4470 // the thread tokens to zero on global token overflow.
4471 struct ResetClaims : public ThreadClosure {
4472 virtual void do_thread(Thread* t) {
4473 t->claim_threads_do(false, 0);
4474 }
4475 } reset_claims;
4476 Threads::threads_do(&reset_claims);
4477 // On overflow, update the global token to non-zero, to
4478 // avoid the special "never claimed" initial thread value.
4479 _thread_claim_token = 1;
4480 }
4481 }
4482
4483 #ifdef ASSERT
4484 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4485 const uintx token = t->threads_do_token();
4486 assert(token == expected,
4487 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4488 UINTX_FORMAT, kind, p2i(t), token, expected);
4489 }
4490
4491 void Threads::assert_all_threads_claimed() {
4492 ALL_JAVA_THREADS(p) {
4493 assert_thread_claimed("Thread", p, _thread_claim_token);
4494 }
4495 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4496 }
4497 #endif // ASSERT
4498
4499 class ParallelOopsDoThreadClosure : public ThreadClosure {
4500 private:
4501 OopClosure* _f;
4502 CodeBlobClosure* _cf;
4503 public:
4504 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4505 void do_thread(Thread* t) {
4506 t->oops_do(_f, _cf);
4507 }
4508 };
4509
4510 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4511 ParallelOopsDoThreadClosure tc(f, cf);
4512 possibly_parallel_threads_do(is_par, &tc);
4513 }
4514
4515 void Threads::nmethods_do(CodeBlobClosure* cf) {
4516 ALL_JAVA_THREADS(p) {
4517 // This is used by the code cache sweeper to mark nmethods that are active
4518 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4519 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4520 if(!p->is_Code_cache_sweeper_thread()) {
4521 p->nmethods_do(cf);
4522 }
4523 }
4524 }
4525
4526 void Threads::metadata_do(MetadataClosure* f) {
4527 ALL_JAVA_THREADS(p) {
4528 p->metadata_do(f);
4529 }
4530 }
4531
4532 class ThreadHandlesClosure : public ThreadClosure {
4533 void (*_f)(Metadata*);
4534 public:
4535 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4536 virtual void do_thread(Thread* thread) {
4537 thread->metadata_handles_do(_f);
4538 }
4539 };
4540
4541 void Threads::metadata_handles_do(void f(Metadata*)) {
4542 // Only walk the Handles in Thread.
4543 ThreadHandlesClosure handles_closure(f);
4544 threads_do(&handles_closure);
4545 }
4546
4547 void Threads::deoptimized_wrt_marked_nmethods() {
4548 ALL_JAVA_THREADS(p) {
4549 p->deoptimized_wrt_marked_nmethods();
4550 }
4551 }
4552
4553
4554 // Get count Java threads that are waiting to enter the specified monitor.
4555 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4556 int count,
4557 address monitor) {
4558 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4559
4560 int i = 0;
4561 DO_JAVA_THREADS(t_list, p) {
4562 if (!p->can_call_java()) continue;
4563
4564 address pending = (address)p->current_pending_monitor();
4565 if (pending == monitor) { // found a match
4566 if (i < count) result->append(p); // save the first count matches
4567 i++;
4568 }
4569 }
4570
4571 return result;
4572 }
4573
4574
4575 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4576 address owner) {
4577 // NULL owner means not locked so we can skip the search
4578 if (owner == NULL) return NULL;
4579
4580 DO_JAVA_THREADS(t_list, p) {
4581 // first, see if owner is the address of a Java thread
4582 if (owner == (address)p) return p;
4583 }
4584
4585 // Cannot assert on lack of success here since this function may be
4586 // used by code that is trying to report useful problem information
4587 // like deadlock detection.
4588 if (UseHeavyMonitors) return NULL;
4589
4590 // If we didn't find a matching Java thread and we didn't force use of
4591 // heavyweight monitors, then the owner is the stack address of the
4592 // Lock Word in the owning Java thread's stack.
4593 //
4594 JavaThread* the_owner = NULL;
4595 DO_JAVA_THREADS(t_list, q) {
4596 if (q->is_lock_owned(owner)) {
4597 the_owner = q;
4598 break;
4599 }
4600 }
4601
4602 // cannot assert on lack of success here; see above comment
4603 return the_owner;
4604 }
4605
4606 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4607 void Threads::print_on(outputStream* st, bool print_stacks,
4608 bool internal_format, bool print_concurrent_locks,
4609 bool print_extended_info) {
4610 char buf[32];
4611 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4612
4613 st->print_cr("Full thread dump %s (%s %s):",
4614 VM_Version::vm_name(),
4615 VM_Version::vm_release(),
4616 VM_Version::vm_info_string());
4617 st->cr();
4618
4619 #if INCLUDE_SERVICES
4620 // Dump concurrent locks
4621 ConcurrentLocksDump concurrent_locks;
4622 if (print_concurrent_locks) {
4623 concurrent_locks.dump_at_safepoint();
4624 }
4625 #endif // INCLUDE_SERVICES
4626
4627 ThreadsSMRSupport::print_info_on(st);
4628 st->cr();
4629
4630 ALL_JAVA_THREADS(p) {
4631 ResourceMark rm;
4632 p->print_on(st, print_extended_info);
4633 if (print_stacks) {
4634 if (internal_format) {
4635 p->trace_stack();
4636 } else {
4637 p->print_stack_on(st);
4638 }
4639 }
4640 st->cr();
4641 #if INCLUDE_SERVICES
4642 if (print_concurrent_locks) {
4643 concurrent_locks.print_locks_on(p, st);
4644 }
4645 #endif // INCLUDE_SERVICES
4646 }
4647
4648 VMThread::vm_thread()->print_on(st);
4649 st->cr();
4650 Universe::heap()->print_gc_threads_on(st);
4651 WatcherThread* wt = WatcherThread::watcher_thread();
4652 if (wt != NULL) {
4653 wt->print_on(st);
4654 st->cr();
4655 }
4656
4657 st->flush();
4658 }
4659
4660 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4661 int buflen, bool* found_current) {
4662 if (this_thread != NULL) {
4663 bool is_current = (current == this_thread);
4664 *found_current = *found_current || is_current;
4665 st->print("%s", is_current ? "=>" : " ");
4666
4667 st->print(PTR_FORMAT, p2i(this_thread));
4668 st->print(" ");
4669 this_thread->print_on_error(st, buf, buflen);
4670 st->cr();
4671 }
4672 }
4673
4674 class PrintOnErrorClosure : public ThreadClosure {
4675 outputStream* _st;
4676 Thread* _current;
4677 char* _buf;
4678 int _buflen;
4679 bool* _found_current;
4680 public:
4681 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4682 int buflen, bool* found_current) :
4683 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4684
4685 virtual void do_thread(Thread* thread) {
4686 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4687 }
4688 };
4689
4690 // Threads::print_on_error() is called by fatal error handler. It's possible
4691 // that VM is not at safepoint and/or current thread is inside signal handler.
4692 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4693 // memory (even in resource area), it might deadlock the error handler.
4694 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4695 int buflen) {
4696 ThreadsSMRSupport::print_info_on(st);
4697 st->cr();
4698
4699 bool found_current = false;
4700 st->print_cr("Java Threads: ( => current thread )");
4701 ALL_JAVA_THREADS(thread) {
4702 print_on_error(thread, st, current, buf, buflen, &found_current);
4703 }
4704 st->cr();
4705
4706 st->print_cr("Other Threads:");
4707 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4708 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4709
4710 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4711 Universe::heap()->gc_threads_do(&print_closure);
4712
4713 if (!found_current) {
4714 st->cr();
4715 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4716 current->print_on_error(st, buf, buflen);
4717 st->cr();
4718 }
4719 st->cr();
4720
4721 st->print_cr("Threads with active compile tasks:");
4722 print_threads_compiling(st, buf, buflen);
4723 }
4724
4725 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4726 ALL_JAVA_THREADS(thread) {
4727 if (thread->is_Compiler_thread()) {
4728 CompilerThread* ct = (CompilerThread*) thread;
4729
4730 // Keep task in local variable for NULL check.
4731 // ct->_task might be set to NULL by concurring compiler thread
4732 // because it completed the compilation. The task is never freed,
4733 // though, just returned to a free list.
4734 CompileTask* task = ct->task();
4735 if (task != NULL) {
4736 thread->print_name_on_error(st, buf, buflen);
4737 st->print(" ");
4738 task->print(st, NULL, short_form, true);
4739 }
4740 }
4741 }
4742 }
4743
4744
4745 // Internal SpinLock and Mutex
4746 // Based on ParkEvent
4747
4748 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4749 //
4750 // We employ SpinLocks _only for low-contention, fixed-length
4751 // short-duration critical sections where we're concerned
4752 // about native mutex_t or HotSpot Mutex:: latency.
4753 // The mux construct provides a spin-then-block mutual exclusion
4754 // mechanism.
4755 //
4756 // Testing has shown that contention on the ListLock guarding gFreeList
4757 // is common. If we implement ListLock as a simple SpinLock it's common
4758 // for the JVM to devolve to yielding with little progress. This is true
4759 // despite the fact that the critical sections protected by ListLock are
4760 // extremely short.
4761 //
4762 // TODO-FIXME: ListLock should be of type SpinLock.
4763 // We should make this a 1st-class type, integrated into the lock
4764 // hierarchy as leaf-locks. Critically, the SpinLock structure
4765 // should have sufficient padding to avoid false-sharing and excessive
4766 // cache-coherency traffic.
4767
4768
4769 typedef volatile int SpinLockT;
4770
4771 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4772 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4773 return; // normal fast-path return
4774 }
4775
4776 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4777 int ctr = 0;
4778 int Yields = 0;
4779 for (;;) {
4780 while (*adr != 0) {
4781 ++ctr;
4782 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4783 if (Yields > 5) {
4784 os::naked_short_sleep(1);
4785 } else {
4786 os::naked_yield();
4787 ++Yields;
4788 }
4789 } else {
4790 SpinPause();
4791 }
4792 }
4793 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4794 }
4795 }
4796
4797 void Thread::SpinRelease(volatile int * adr) {
4798 assert(*adr != 0, "invariant");
4799 OrderAccess::fence(); // guarantee at least release consistency.
4800 // Roach-motel semantics.
4801 // It's safe if subsequent LDs and STs float "up" into the critical section,
4802 // but prior LDs and STs within the critical section can't be allowed
4803 // to reorder or float past the ST that releases the lock.
4804 // Loads and stores in the critical section - which appear in program
4805 // order before the store that releases the lock - must also appear
4806 // before the store that releases the lock in memory visibility order.
4807 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4808 // the ST of 0 into the lock-word which releases the lock, so fence
4809 // more than covers this on all platforms.
4810 *adr = 0;
4811 }
4812
4813 // muxAcquire and muxRelease:
4814 //
4815 // * muxAcquire and muxRelease support a single-word lock-word construct.
4816 // The LSB of the word is set IFF the lock is held.
4817 // The remainder of the word points to the head of a singly-linked list
4818 // of threads blocked on the lock.
4819 //
4820 // * The current implementation of muxAcquire-muxRelease uses its own
4821 // dedicated Thread._MuxEvent instance. If we're interested in
4822 // minimizing the peak number of extant ParkEvent instances then
4823 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4824 // as certain invariants were satisfied. Specifically, care would need
4825 // to be taken with regards to consuming unpark() "permits".
4826 // A safe rule of thumb is that a thread would never call muxAcquire()
4827 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4828 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4829 // consume an unpark() permit intended for monitorenter, for instance.
4830 // One way around this would be to widen the restricted-range semaphore
4831 // implemented in park(). Another alternative would be to provide
4832 // multiple instances of the PlatformEvent() for each thread. One
4833 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4834 //
4835 // * Usage:
4836 // -- Only as leaf locks
4837 // -- for short-term locking only as muxAcquire does not perform
4838 // thread state transitions.
4839 //
4840 // Alternatives:
4841 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4842 // but with parking or spin-then-park instead of pure spinning.
4843 // * Use Taura-Oyama-Yonenzawa locks.
4844 // * It's possible to construct a 1-0 lock if we encode the lockword as
4845 // (List,LockByte). Acquire will CAS the full lockword while Release
4846 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4847 // acquiring threads use timers (ParkTimed) to detect and recover from
4848 // the stranding window. Thread/Node structures must be aligned on 256-byte
4849 // boundaries by using placement-new.
4850 // * Augment MCS with advisory back-link fields maintained with CAS().
4851 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4852 // The validity of the backlinks must be ratified before we trust the value.
4853 // If the backlinks are invalid the exiting thread must back-track through the
4854 // the forward links, which are always trustworthy.
4855 // * Add a successor indication. The LockWord is currently encoded as
4856 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4857 // to provide the usual futile-wakeup optimization.
4858 // See RTStt for details.
4859 //
4860
4861
4862 const intptr_t LOCKBIT = 1;
4863
4864 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4865 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4866 if (w == 0) return;
4867 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4868 return;
4869 }
4870
4871 ParkEvent * const Self = Thread::current()->_MuxEvent;
4872 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4873 for (;;) {
4874 int its = (os::is_MP() ? 100 : 0) + 1;
4875
4876 // Optional spin phase: spin-then-park strategy
4877 while (--its >= 0) {
4878 w = *Lock;
4879 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4880 return;
4881 }
4882 }
4883
4884 Self->reset();
4885 Self->OnList = intptr_t(Lock);
4886 // The following fence() isn't _strictly necessary as the subsequent
4887 // CAS() both serializes execution and ratifies the fetched *Lock value.
4888 OrderAccess::fence();
4889 for (;;) {
4890 w = *Lock;
4891 if ((w & LOCKBIT) == 0) {
4892 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4893 Self->OnList = 0; // hygiene - allows stronger asserts
4894 return;
4895 }
4896 continue; // Interference -- *Lock changed -- Just retry
4897 }
4898 assert(w & LOCKBIT, "invariant");
4899 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4900 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4901 }
4902
4903 while (Self->OnList != 0) {
4904 Self->park();
4905 }
4906 }
4907 }
4908
4909 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4910 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4911 if (w == 0) return;
4912 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4913 return;
4914 }
4915
4916 ParkEvent * ReleaseAfter = NULL;
4917 if (ev == NULL) {
4918 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4919 }
4920 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4921 for (;;) {
4922 guarantee(ev->OnList == 0, "invariant");
4923 int its = (os::is_MP() ? 100 : 0) + 1;
4924
4925 // Optional spin phase: spin-then-park strategy
4926 while (--its >= 0) {
4927 w = *Lock;
4928 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4929 if (ReleaseAfter != NULL) {
4930 ParkEvent::Release(ReleaseAfter);
4931 }
4932 return;
4933 }
4934 }
4935
4936 ev->reset();
4937 ev->OnList = intptr_t(Lock);
4938 // The following fence() isn't _strictly necessary as the subsequent
4939 // CAS() both serializes execution and ratifies the fetched *Lock value.
4940 OrderAccess::fence();
4941 for (;;) {
4942 w = *Lock;
4943 if ((w & LOCKBIT) == 0) {
4944 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4945 ev->OnList = 0;
4946 // We call ::Release while holding the outer lock, thus
4947 // artificially lengthening the critical section.
4948 // Consider deferring the ::Release() until the subsequent unlock(),
4949 // after we've dropped the outer lock.
4950 if (ReleaseAfter != NULL) {
4951 ParkEvent::Release(ReleaseAfter);
4952 }
4953 return;
4954 }
4955 continue; // Interference -- *Lock changed -- Just retry
4956 }
4957 assert(w & LOCKBIT, "invariant");
4958 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4959 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4960 }
4961
4962 while (ev->OnList != 0) {
4963 ev->park();
4964 }
4965 }
4966 }
4967
4968 // Release() must extract a successor from the list and then wake that thread.
4969 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4970 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4971 // Release() would :
4972 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4973 // (B) Extract a successor from the private list "in-hand"
4974 // (C) attempt to CAS() the residual back into *Lock over null.
4975 // If there were any newly arrived threads and the CAS() would fail.
4976 // In that case Release() would detach the RATs, re-merge the list in-hand
4977 // with the RATs and repeat as needed. Alternately, Release() might
4978 // detach and extract a successor, but then pass the residual list to the wakee.
4979 // The wakee would be responsible for reattaching and remerging before it
4980 // competed for the lock.
4981 //
4982 // Both "pop" and DMR are immune from ABA corruption -- there can be
4983 // multiple concurrent pushers, but only one popper or detacher.
4984 // This implementation pops from the head of the list. This is unfair,
4985 // but tends to provide excellent throughput as hot threads remain hot.
4986 // (We wake recently run threads first).
4987 //
4988 // All paths through muxRelease() will execute a CAS.
4989 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4990 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4991 // executed within the critical section are complete and globally visible before the
4992 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4993 void Thread::muxRelease(volatile intptr_t * Lock) {
4994 for (;;) {
4995 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4996 assert(w & LOCKBIT, "invariant");
4997 if (w == LOCKBIT) return;
4998 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4999 assert(List != NULL, "invariant");
5000 assert(List->OnList == intptr_t(Lock), "invariant");
5001 ParkEvent * const nxt = List->ListNext;
5002 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5003
5004 // The following CAS() releases the lock and pops the head element.
5005 // The CAS() also ratifies the previously fetched lock-word value.
5006 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5007 continue;
5008 }
5009 List->OnList = 0;
5010 OrderAccess::fence();
5011 List->unpark();
5012 return;
5013 }
5014 }
5015
5016
5017 void Threads::verify() {
5018 ALL_JAVA_THREADS(p) {
5019 p->verify();
5020 }
5021 VMThread* thread = VMThread::vm_thread();
5022 if (thread != NULL) thread->verify();
5023 }