1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "aot/aotLoader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/javaClasses.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/scopeDesc.hpp"
35 #include "compiler/compileBroker.hpp"
36 #include "compiler/compileTask.hpp"
37 #include "gc/shared/barrierSet.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/workgroup.hpp"
41 #include "interpreter/interpreter.hpp"
42 #include "interpreter/linkResolver.hpp"
43 #include "interpreter/oopMapCache.hpp"
44 #include "jfr/jfrEvents.hpp"
45 #include "jvmtifiles/jvmtiEnv.hpp"
46 #include "logging/log.hpp"
47 #include "logging/logConfiguration.hpp"
48 #include "logging/logStream.hpp"
49 #include "memory/allocation.inline.hpp"
50 #include "memory/metaspaceShared.hpp"
51 #include "memory/oopFactory.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "memory/universe.hpp"
54 #include "oops/access.inline.hpp"
55 #include "oops/instanceKlass.hpp"
56 #include "oops/objArrayOop.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/symbol.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "oops/verifyOopClosure.hpp"
61 #include "prims/jvm_misc.hpp"
62 #include "prims/jvmtiExport.hpp"
63 #include "prims/jvmtiThreadState.hpp"
64 #include "runtime/arguments.hpp"
65 #include "runtime/atomic.hpp"
66 #include "runtime/biasedLocking.hpp"
67 #include "runtime/fieldDescriptor.inline.hpp"
68 #include "runtime/flags/jvmFlagConstraintList.hpp"
69 #include "runtime/flags/jvmFlagRangeList.hpp"
70 #include "runtime/flags/jvmFlagWriteableList.hpp"
71 #include "runtime/deoptimization.hpp"
72 #include "runtime/frame.inline.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/handshake.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/jniHandles.inline.hpp"
80 #include "runtime/jniPeriodicChecker.hpp"
81 #include "runtime/memprofiler.hpp"
82 #include "runtime/mutexLocker.hpp"
83 #include "runtime/objectMonitor.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/osThread.hpp"
86 #include "runtime/prefetch.inline.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/safepointMechanism.inline.hpp"
89 #include "runtime/safepointVerifiers.hpp"
90 #include "runtime/sharedRuntime.hpp"
91 #include "runtime/statSampler.hpp"
92 #include "runtime/stubRoutines.hpp"
93 #include "runtime/sweeper.hpp"
94 #include "runtime/task.hpp"
95 #include "runtime/thread.inline.hpp"
96 #include "runtime/threadCritical.hpp"
97 #include "runtime/threadSMR.inline.hpp"
98 #include "runtime/threadStatisticalInfo.hpp"
99 #include "runtime/timer.hpp"
100 #include "runtime/timerTrace.hpp"
101 #include "runtime/vframe.inline.hpp"
102 #include "runtime/vframeArray.hpp"
103 #include "runtime/vframe_hp.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "runtime/vmOperations.hpp"
106 #include "runtime/vm_version.hpp"
107 #include "services/attachListener.hpp"
108 #include "services/management.hpp"
109 #include "services/memTracker.hpp"
110 #include "services/threadService.hpp"
111 #include "utilities/align.hpp"
112 #include "utilities/copy.hpp"
113 #include "utilities/defaultStream.hpp"
114 #include "utilities/dtrace.hpp"
115 #include "utilities/events.hpp"
116 #include "utilities/macros.hpp"
117 #include "utilities/preserveException.hpp"
118 #include "utilities/singleWriterSynchronizer.hpp"
119 #include "utilities/vmError.hpp"
120 #if INCLUDE_JVMCI
121 #include "jvmci/jvmci.hpp"
122 #include "jvmci/jvmciEnv.hpp"
123 #endif
124 #ifdef COMPILER1
125 #include "c1/c1_Compiler.hpp"
126 #endif
127 #ifdef COMPILER2
128 #include "opto/c2compiler.hpp"
129 #include "opto/idealGraphPrinter.hpp"
130 #endif
131 #if INCLUDE_RTM_OPT
132 #include "runtime/rtmLocking.hpp"
133 #endif
134 #if INCLUDE_JFR
135 #include "jfr/jfr.hpp"
136 #endif
137
138 // Initialization after module runtime initialization
139 void universe_post_module_init(); // must happen after call_initPhase2
140
141 #ifdef DTRACE_ENABLED
142
143 // Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161 #else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165 #endif // ndef DTRACE_ENABLED
166
167 #ifndef USE_LIBRARY_BASED_TLS_ONLY
168 // Current thread is maintained as a thread-local variable
169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
170 #endif
171
172 // ======= Thread ========
173 // Support for forcing alignment of thread objects for biased locking
174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const int alignment = markWord::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : AllocateHeap(aligned_size, flags, CURRENT_PC,
180 AllocFailStrategy::RETURN_NULL);
181 void* aligned_addr = align_up(real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (aligned_addr != real_malloc_addr) {
186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 p2i(real_malloc_addr),
188 p2i(aligned_addr));
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
195 }
196 }
197
198 void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 FreeHeap(((Thread*) p)->_real_malloc_address);
201 } else {
202 FreeHeap(p);
203 }
204 }
205
206 void JavaThread::smr_delete() {
207 if (_on_thread_list) {
208 ThreadsSMRSupport::smr_delete(this);
209 } else {
210 delete this;
211 }
212 }
213
214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
215 // JavaThread
216
217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
218
219 Thread::Thread() {
220
221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
222
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_lgrp_id(-1);
227 DEBUG_ONLY(clear_suspendible_thread();)
228
229 // allocated data structures
230 set_osthread(NULL);
231 set_resource_area(new (mtThread)ResourceArea());
232 DEBUG_ONLY(_current_resource_mark = NULL;)
233 set_handle_area(new (mtThread) HandleArea(NULL));
234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
235 set_active_handles(NULL);
236 set_free_handle_block(NULL);
237 set_last_handle_mark(NULL);
238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
239
240 // Initial value of zero ==> never claimed.
241 _threads_do_token = 0;
242 _threads_hazard_ptr = NULL;
243 _threads_list_ptr = NULL;
244 _nested_threads_hazard_ptr_cnt = 0;
245 _rcu_counter = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 NOT_PRODUCT(_no_safepoint_count = 0;)
253 NOT_PRODUCT(_skip_gcalot = false;)
254 _jvmti_env_iteration_count = 0;
255 set_allocated_bytes(0);
256 _vm_operation_started_count = 0;
257 _vm_operation_completed_count = 0;
258 _current_pending_monitor = NULL;
259 _current_pending_monitor_is_from_java = true;
260 _current_waiting_monitor = NULL;
261 _num_nested_signal = 0;
262 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 om_request_deflation = false;
268
269 #ifdef ASSERT
270 _visited_for_critical_count = false;
271 #endif
272
273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
274 Monitor::_safepoint_check_sometimes);
275 _suspend_flags = 0;
276
277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
278 _hashStateX = os::random();
279 _hashStateY = 842502087;
280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
281 _hashStateW = 273326509;
282
283 _OnTrap = 0;
284 _Stalled = 0;
285 _TypeTag = 0x2BAD;
286
287 // Many of the following fields are effectively final - immutable
288 // Note that nascent threads can't use the Native Monitor-Mutex
289 // construct until the _MutexEvent is initialized ...
290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
291 // we might instead use a stack of ParkEvents that we could provision on-demand.
292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
293 // and ::Release()
294 _ParkEvent = ParkEvent::Allocate(this);
295 _SleepEvent = ParkEvent::Allocate(this);
296 _MuxEvent = ParkEvent::Allocate(this);
297
298 #ifdef CHECK_UNHANDLED_OOPS
299 if (CheckUnhandledOops) {
300 _unhandled_oops = new UnhandledOops(this);
301 }
302 #endif // CHECK_UNHANDLED_OOPS
303 #ifdef ASSERT
304 if (UseBiasedLocking) {
305 assert((((uintptr_t) this) & (markWord::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
306 assert(this == _real_malloc_address ||
307 this == align_up(_real_malloc_address, (int)markWord::biased_lock_alignment),
308 "bug in forced alignment of thread objects");
309 }
310 #endif // ASSERT
311
312 // Notify the barrier set that a thread is being created. The initial
313 // thread is created before the barrier set is available. The call to
314 // BarrierSet::on_thread_create() for this thread is therefore deferred
315 // to BarrierSet::set_barrier_set().
316 BarrierSet* const barrier_set = BarrierSet::barrier_set();
317 if (barrier_set != NULL) {
318 barrier_set->on_thread_create(this);
319 } else {
320 // Only the main thread should be created before the barrier set
321 // and that happens just before Thread::current is set. No other thread
322 // can attach as the VM is not created yet, so they can't execute this code.
323 // If the main thread creates other threads before the barrier set that is an error.
324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
325 }
326 }
327
328 void Thread::initialize_thread_current() {
329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
330 assert(_thr_current == NULL, "Thread::current already initialized");
331 _thr_current = this;
332 #endif
333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
334 ThreadLocalStorage::set_thread(this);
335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
336 }
337
338 void Thread::clear_thread_current() {
339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
341 _thr_current = NULL;
342 #endif
343 ThreadLocalStorage::set_thread(NULL);
344 }
345
346 void Thread::record_stack_base_and_size() {
347 // Note: at this point, Thread object is not yet initialized. Do not rely on
348 // any members being initialized. Do not rely on Thread::current() being set.
349 // If possible, refrain from doing anything which may crash or assert since
350 // quite probably those crash dumps will be useless.
351 set_stack_base(os::current_stack_base());
352 set_stack_size(os::current_stack_size());
353
354 #ifdef SOLARIS
355 if (os::is_primordial_thread()) {
356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
357 }
358 #endif
359
360 // Set stack limits after thread is initialized.
361 if (is_Java_thread()) {
362 ((JavaThread*) this)->set_stack_overflow_limit();
363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
364 }
365 }
366
367 #if INCLUDE_NMT
368 void Thread::register_thread_stack_with_NMT() {
369 MemTracker::record_thread_stack(stack_end(), stack_size());
370 }
371 #endif // INCLUDE_NMT
372
373 void Thread::call_run() {
374 DEBUG_ONLY(_run_state = CALL_RUN;)
375
376 // At this point, Thread object should be fully initialized and
377 // Thread::current() should be set.
378
379 assert(Thread::current_or_null() != NULL, "current thread is unset");
380 assert(Thread::current_or_null() == this, "current thread is wrong");
381
382 // Perform common initialization actions
383
384 register_thread_stack_with_NMT();
385
386 JFR_ONLY(Jfr::on_thread_start(this);)
387
388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
390 os::current_thread_id(), p2i(stack_base() - stack_size()),
391 p2i(stack_base()), stack_size()/1024);
392
393 // Perform <ChildClass> initialization actions
394 DEBUG_ONLY(_run_state = PRE_RUN;)
395 this->pre_run();
396
397 // Invoke <ChildClass>::run()
398 DEBUG_ONLY(_run_state = RUN;)
399 this->run();
400 // Returned from <ChildClass>::run(). Thread finished.
401
402 // Perform common tear-down actions
403
404 assert(Thread::current_or_null() != NULL, "current thread is unset");
405 assert(Thread::current_or_null() == this, "current thread is wrong");
406
407 // Perform <ChildClass> tear-down actions
408 DEBUG_ONLY(_run_state = POST_RUN;)
409 this->post_run();
410
411 // Note: at this point the thread object may already have deleted itself,
412 // so from here on do not dereference *this*. Not all thread types currently
413 // delete themselves when they terminate. But no thread should ever be deleted
414 // asynchronously with respect to its termination - that is what _run_state can
415 // be used to check.
416
417 assert(Thread::current_or_null() == NULL, "current thread still present");
418 }
419
420 Thread::~Thread() {
421
422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
423 // get started due to errors etc. Any active thread should at least reach post_run
424 // before it is deleted (usually in post_run()).
425 assert(_run_state == PRE_CALL_RUN ||
426 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
427 "_run_state=%d", (int)_run_state);
428
429 // Notify the barrier set that a thread is being destroyed. Note that a barrier
430 // set might not be available if we encountered errors during bootstrapping.
431 BarrierSet* const barrier_set = BarrierSet::barrier_set();
432 if (barrier_set != NULL) {
433 barrier_set->on_thread_destroy(this);
434 }
435
436 // stack_base can be NULL if the thread is never started or exited before
437 // record_stack_base_and_size called. Although, we would like to ensure
438 // that all started threads do call record_stack_base_and_size(), there is
439 // not proper way to enforce that.
440 #if INCLUDE_NMT
441 if (_stack_base != NULL) {
442 MemTracker::release_thread_stack(stack_end(), stack_size());
443 #ifdef ASSERT
444 set_stack_base(NULL);
445 #endif
446 }
447 #endif // INCLUDE_NMT
448
449 // deallocate data structures
450 delete resource_area();
451 // since the handle marks are using the handle area, we have to deallocated the root
452 // handle mark before deallocating the thread's handle area,
453 assert(last_handle_mark() != NULL, "check we have an element");
454 delete last_handle_mark();
455 assert(last_handle_mark() == NULL, "check we have reached the end");
456
457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
458 // We NULL out the fields for good hygiene.
459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
460 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
461 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
462
463 delete handle_area();
464 delete metadata_handles();
465
466 // SR_handler uses this as a termination indicator -
467 // needs to happen before os::free_thread()
468 delete _SR_lock;
469 _SR_lock = NULL;
470
471 // osthread() can be NULL, if creation of thread failed.
472 if (osthread() != NULL) os::free_thread(osthread());
473
474 // Clear Thread::current if thread is deleting itself and it has not
475 // already been done. This must be done before the memory is deallocated.
476 // Needed to ensure JNI correctly detects non-attached threads.
477 if (this == Thread::current_or_null()) {
478 Thread::clear_thread_current();
479 }
480
481 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
482 }
483
484 #ifdef ASSERT
485 // A JavaThread is considered "dangling" if it is not the current
486 // thread, has been added the Threads list, the system is not at a
487 // safepoint and the Thread is not "protected".
488 //
489 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
490 assert(!thread->is_Java_thread() || Thread::current() == thread ||
491 !((JavaThread *) thread)->on_thread_list() ||
492 SafepointSynchronize::is_at_safepoint() ||
493 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
494 "possibility of dangling Thread pointer");
495 }
496 #endif
497
498 ThreadPriority Thread::get_priority(const Thread* const thread) {
499 ThreadPriority priority;
500 // Can return an error!
501 (void)os::get_priority(thread, priority);
502 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
503 return priority;
504 }
505
506 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
507 debug_only(check_for_dangling_thread_pointer(thread);)
508 // Can return an error!
509 (void)os::set_priority(thread, priority);
510 }
511
512
513 void Thread::start(Thread* thread) {
514 // Start is different from resume in that its safety is guaranteed by context or
515 // being called from a Java method synchronized on the Thread object.
516 if (!DisableStartThread) {
517 if (thread->is_Java_thread()) {
518 // Initialize the thread state to RUNNABLE before starting this thread.
519 // Can not set it after the thread started because we do not know the
520 // exact thread state at that time. It could be in MONITOR_WAIT or
521 // in SLEEPING or some other state.
522 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
523 java_lang_Thread::RUNNABLE);
524 }
525 os::start_thread(thread);
526 }
527 }
528
529 // Enqueue a VM_Operation to do the job for us - sometime later
530 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
531 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
532 VMThread::execute(vm_stop);
533 }
534
535
536 // Check if an external suspend request has completed (or has been
537 // cancelled). Returns true if the thread is externally suspended and
538 // false otherwise.
539 //
540 // The bits parameter returns information about the code path through
541 // the routine. Useful for debugging:
542 //
543 // set in is_ext_suspend_completed():
544 // 0x00000001 - routine was entered
545 // 0x00000010 - routine return false at end
546 // 0x00000100 - thread exited (return false)
547 // 0x00000200 - suspend request cancelled (return false)
548 // 0x00000400 - thread suspended (return true)
549 // 0x00001000 - thread is in a suspend equivalent state (return true)
550 // 0x00002000 - thread is native and walkable (return true)
551 // 0x00004000 - thread is native_trans and walkable (needed retry)
552 //
553 // set in wait_for_ext_suspend_completion():
554 // 0x00010000 - routine was entered
555 // 0x00020000 - suspend request cancelled before loop (return false)
556 // 0x00040000 - thread suspended before loop (return true)
557 // 0x00080000 - suspend request cancelled in loop (return false)
558 // 0x00100000 - thread suspended in loop (return true)
559 // 0x00200000 - suspend not completed during retry loop (return false)
560
561 // Helper class for tracing suspend wait debug bits.
562 //
563 // 0x00000100 indicates that the target thread exited before it could
564 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
565 // 0x00080000 each indicate a cancelled suspend request so they don't
566 // count as wait failures either.
567 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
568
569 class TraceSuspendDebugBits : public StackObj {
570 private:
571 JavaThread * jt;
572 bool is_wait;
573 bool called_by_wait; // meaningful when !is_wait
574 uint32_t * bits;
575
576 public:
577 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
578 uint32_t *_bits) {
579 jt = _jt;
580 is_wait = _is_wait;
581 called_by_wait = _called_by_wait;
582 bits = _bits;
583 }
584
585 ~TraceSuspendDebugBits() {
586 if (!is_wait) {
587 #if 1
588 // By default, don't trace bits for is_ext_suspend_completed() calls.
589 // That trace is very chatty.
590 return;
591 #else
592 if (!called_by_wait) {
593 // If tracing for is_ext_suspend_completed() is enabled, then only
594 // trace calls to it from wait_for_ext_suspend_completion()
595 return;
596 }
597 #endif
598 }
599
600 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
601 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
602 MutexLocker ml(Threads_lock); // needed for get_thread_name()
603 ResourceMark rm;
604
605 tty->print_cr(
606 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
607 jt->get_thread_name(), *bits);
608
609 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
610 }
611 }
612 }
613 };
614 #undef DEBUG_FALSE_BITS
615
616
617 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
618 uint32_t *bits) {
619 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
620
621 bool did_trans_retry = false; // only do thread_in_native_trans retry once
622 bool do_trans_retry; // flag to force the retry
623
624 *bits |= 0x00000001;
625
626 do {
627 do_trans_retry = false;
628
629 if (is_exiting()) {
630 // Thread is in the process of exiting. This is always checked
631 // first to reduce the risk of dereferencing a freed JavaThread.
632 *bits |= 0x00000100;
633 return false;
634 }
635
636 if (!is_external_suspend()) {
637 // Suspend request is cancelled. This is always checked before
638 // is_ext_suspended() to reduce the risk of a rogue resume
639 // confusing the thread that made the suspend request.
640 *bits |= 0x00000200;
641 return false;
642 }
643
644 if (is_ext_suspended()) {
645 // thread is suspended
646 *bits |= 0x00000400;
647 return true;
648 }
649
650 // Now that we no longer do hard suspends of threads running
651 // native code, the target thread can be changing thread state
652 // while we are in this routine:
653 //
654 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
655 //
656 // We save a copy of the thread state as observed at this moment
657 // and make our decision about suspend completeness based on the
658 // copy. This closes the race where the thread state is seen as
659 // _thread_in_native_trans in the if-thread_blocked check, but is
660 // seen as _thread_blocked in if-thread_in_native_trans check.
661 JavaThreadState save_state = thread_state();
662
663 if (save_state == _thread_blocked && is_suspend_equivalent()) {
664 // If the thread's state is _thread_blocked and this blocking
665 // condition is known to be equivalent to a suspend, then we can
666 // consider the thread to be externally suspended. This means that
667 // the code that sets _thread_blocked has been modified to do
668 // self-suspension if the blocking condition releases. We also
669 // used to check for CONDVAR_WAIT here, but that is now covered by
670 // the _thread_blocked with self-suspension check.
671 //
672 // Return true since we wouldn't be here unless there was still an
673 // external suspend request.
674 *bits |= 0x00001000;
675 return true;
676 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
677 // Threads running native code will self-suspend on native==>VM/Java
678 // transitions. If its stack is walkable (should always be the case
679 // unless this function is called before the actual java_suspend()
680 // call), then the wait is done.
681 *bits |= 0x00002000;
682 return true;
683 } else if (!called_by_wait && !did_trans_retry &&
684 save_state == _thread_in_native_trans &&
685 frame_anchor()->walkable()) {
686 // The thread is transitioning from thread_in_native to another
687 // thread state. check_safepoint_and_suspend_for_native_trans()
688 // will force the thread to self-suspend. If it hasn't gotten
689 // there yet we may have caught the thread in-between the native
690 // code check above and the self-suspend. Lucky us. If we were
691 // called by wait_for_ext_suspend_completion(), then it
692 // will be doing the retries so we don't have to.
693 //
694 // Since we use the saved thread state in the if-statement above,
695 // there is a chance that the thread has already transitioned to
696 // _thread_blocked by the time we get here. In that case, we will
697 // make a single unnecessary pass through the logic below. This
698 // doesn't hurt anything since we still do the trans retry.
699
700 *bits |= 0x00004000;
701
702 // Once the thread leaves thread_in_native_trans for another
703 // thread state, we break out of this retry loop. We shouldn't
704 // need this flag to prevent us from getting back here, but
705 // sometimes paranoia is good.
706 did_trans_retry = true;
707
708 // We wait for the thread to transition to a more usable state.
709 for (int i = 1; i <= SuspendRetryCount; i++) {
710 // We used to do an "os::yield_all(i)" call here with the intention
711 // that yielding would increase on each retry. However, the parameter
712 // is ignored on Linux which means the yield didn't scale up. Waiting
713 // on the SR_lock below provides a much more predictable scale up for
714 // the delay. It also provides a simple/direct point to check for any
715 // safepoint requests from the VMThread
716
717 // temporarily drops SR_lock while doing wait with safepoint check
718 // (if we're a JavaThread - the WatcherThread can also call this)
719 // and increase delay with each retry
720 if (Thread::current()->is_Java_thread()) {
721 SR_lock()->wait(i * delay);
722 } else {
723 SR_lock()->wait_without_safepoint_check(i * delay);
724 }
725
726 // check the actual thread state instead of what we saved above
727 if (thread_state() != _thread_in_native_trans) {
728 // the thread has transitioned to another thread state so
729 // try all the checks (except this one) one more time.
730 do_trans_retry = true;
731 break;
732 }
733 } // end retry loop
734
735
736 }
737 } while (do_trans_retry);
738
739 *bits |= 0x00000010;
740 return false;
741 }
742
743 // Wait for an external suspend request to complete (or be cancelled).
744 // Returns true if the thread is externally suspended and false otherwise.
745 //
746 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
747 uint32_t *bits) {
748 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
749 false /* !called_by_wait */, bits);
750
751 // local flag copies to minimize SR_lock hold time
752 bool is_suspended;
753 bool pending;
754 uint32_t reset_bits;
755
756 // set a marker so is_ext_suspend_completed() knows we are the caller
757 *bits |= 0x00010000;
758
759 // We use reset_bits to reinitialize the bits value at the top of
760 // each retry loop. This allows the caller to make use of any
761 // unused bits for their own marking purposes.
762 reset_bits = *bits;
763
764 {
765 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
766 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
767 delay, bits);
768 pending = is_external_suspend();
769 }
770 // must release SR_lock to allow suspension to complete
771
772 if (!pending) {
773 // A cancelled suspend request is the only false return from
774 // is_ext_suspend_completed() that keeps us from entering the
775 // retry loop.
776 *bits |= 0x00020000;
777 return false;
778 }
779
780 if (is_suspended) {
781 *bits |= 0x00040000;
782 return true;
783 }
784
785 for (int i = 1; i <= retries; i++) {
786 *bits = reset_bits; // reinit to only track last retry
787
788 // We used to do an "os::yield_all(i)" call here with the intention
789 // that yielding would increase on each retry. However, the parameter
790 // is ignored on Linux which means the yield didn't scale up. Waiting
791 // on the SR_lock below provides a much more predictable scale up for
792 // the delay. It also provides a simple/direct point to check for any
793 // safepoint requests from the VMThread
794
795 {
796 Thread* t = Thread::current();
797 MonitorLocker ml(SR_lock(),
798 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
799 // wait with safepoint check (if we're a JavaThread - the WatcherThread
800 // can also call this) and increase delay with each retry
801 ml.wait(i * delay);
802
803 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
804 delay, bits);
805
806 // It is possible for the external suspend request to be cancelled
807 // (by a resume) before the actual suspend operation is completed.
808 // Refresh our local copy to see if we still need to wait.
809 pending = is_external_suspend();
810 }
811
812 if (!pending) {
813 // A cancelled suspend request is the only false return from
814 // is_ext_suspend_completed() that keeps us from staying in the
815 // retry loop.
816 *bits |= 0x00080000;
817 return false;
818 }
819
820 if (is_suspended) {
821 *bits |= 0x00100000;
822 return true;
823 }
824 } // end retry loop
825
826 // thread did not suspend after all our retries
827 *bits |= 0x00200000;
828 return false;
829 }
830
831 // Called from API entry points which perform stack walking. If the
832 // associated JavaThread is the current thread, then wait_for_suspend
833 // is not used. Otherwise, it determines if we should wait for the
834 // "other" thread to complete external suspension. (NOTE: in future
835 // releases the suspension mechanism should be reimplemented so this
836 // is not necessary.)
837 //
838 bool
839 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
840 if (this != JavaThread::current()) {
841 // "other" threads require special handling.
842 if (wait_for_suspend) {
843 // We are allowed to wait for the external suspend to complete
844 // so give the other thread a chance to get suspended.
845 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
846 SuspendRetryDelay, bits)) {
847 // Didn't make it so let the caller know.
848 return false;
849 }
850 }
851 // We aren't allowed to wait for the external suspend to complete
852 // so if the other thread isn't externally suspended we need to
853 // let the caller know.
854 else if (!is_ext_suspend_completed_with_lock(bits)) {
855 return false;
856 }
857 }
858
859 return true;
860 }
861
862 void Thread::interrupt(Thread* thread) {
863 debug_only(check_for_dangling_thread_pointer(thread);)
864 os::interrupt(thread);
865 }
866
867 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
868 debug_only(check_for_dangling_thread_pointer(thread);)
869 // Note: If clear_interrupted==false, this simply fetches and
870 // returns the value of the field osthread()->interrupted().
871 return os::is_interrupted(thread, clear_interrupted);
872 }
873
874
875 // GC Support
876 bool Thread::claim_par_threads_do(uintx claim_token) {
877 uintx token = _threads_do_token;
878 if (token != claim_token) {
879 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
880 if (res == token) {
881 return true;
882 }
883 guarantee(res == claim_token, "invariant");
884 }
885 return false;
886 }
887
888 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
889 active_handles()->oops_do(f);
890 // Do oop for ThreadShadow
891 f->do_oop((oop*)&_pending_exception);
892 handle_area()->oops_do(f);
893
894 // We scan thread local monitor lists here, and the remaining global
895 // monitors in ObjectSynchronizer::oops_do().
896 ObjectSynchronizer::thread_local_used_oops_do(this, f);
897 }
898
899 void Thread::metadata_handles_do(void f(Metadata*)) {
900 // Only walk the Handles in Thread.
901 if (metadata_handles() != NULL) {
902 for (int i = 0; i< metadata_handles()->length(); i++) {
903 f(metadata_handles()->at(i));
904 }
905 }
906 }
907
908 void Thread::print_on(outputStream* st, bool print_extended_info) const {
909 // get_priority assumes osthread initialized
910 if (osthread() != NULL) {
911 int os_prio;
912 if (os::get_native_priority(this, &os_prio) == OS_OK) {
913 st->print("os_prio=%d ", os_prio);
914 }
915
916 st->print("cpu=%.2fms ",
917 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
918 );
919 st->print("elapsed=%.2fs ",
920 _statistical_info.getElapsedTime() / 1000.0
921 );
922 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
923 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
924 st->print("allocated=" SIZE_FORMAT "%s ",
925 byte_size_in_proper_unit(allocated_bytes),
926 proper_unit_for_byte_size(allocated_bytes)
927 );
928 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
929 }
930
931 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
932 osthread()->print_on(st);
933 }
934 ThreadsSMRSupport::print_info_on(this, st);
935 st->print(" ");
936 debug_only(if (WizardMode) print_owned_locks_on(st);)
937 }
938
939 void Thread::print() const { print_on(tty); }
940
941 // Thread::print_on_error() is called by fatal error handler. Don't use
942 // any lock or allocate memory.
943 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
944 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
945
946 if (is_VM_thread()) { st->print("VMThread"); }
947 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
948 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
949 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
950 else { st->print("Thread"); }
951
952 if (is_Named_thread()) {
953 st->print(" \"%s\"", name());
954 }
955
956 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
957 p2i(stack_end()), p2i(stack_base()));
958
959 if (osthread()) {
960 st->print(" [id=%d]", osthread()->thread_id());
961 }
962
963 ThreadsSMRSupport::print_info_on(this, st);
964 }
965
966 void Thread::print_value_on(outputStream* st) const {
967 if (is_Named_thread()) {
968 st->print(" \"%s\" ", name());
969 }
970 st->print(INTPTR_FORMAT, p2i(this)); // print address
971 }
972
973 #ifdef ASSERT
974 void Thread::print_owned_locks_on(outputStream* st) const {
975 Monitor *cur = _owned_locks;
976 if (cur == NULL) {
977 st->print(" (no locks) ");
978 } else {
979 st->print_cr(" Locks owned:");
980 while (cur) {
981 cur->print_on(st);
982 cur = cur->next();
983 }
984 }
985 }
986
987 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
988 void Thread::check_possible_safepoint() {
989 if (!is_Java_thread()) return;
990
991 if (_no_safepoint_count > 0) {
992 fatal("Possible safepoint reached by thread that does not allow it");
993 }
994 #ifdef CHECK_UNHANDLED_OOPS
995 // Clear unhandled oops in JavaThreads so we get a crash right away.
996 clear_unhandled_oops();
997 #endif // CHECK_UNHANDLED_OOPS
998 }
999
1000 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1001 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1002 // no locks which allow_vm_block's are held
1003 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1004 if (!is_Java_thread()) return;
1005
1006 check_possible_safepoint();
1007
1008 if (((JavaThread*)this)->thread_state() != _thread_in_vm) {
1009 fatal("LEAF method calling lock?");
1010 }
1011
1012 if (potential_vm_operation && !Universe::is_bootstrapping()) {
1013 // Make sure we do not hold any locks that the VM thread also uses.
1014 // This could potentially lead to deadlocks
1015 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1016 // Threads_lock is special, since the safepoint synchronization will not start before this is
1017 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1018 // since it is used to transfer control between JavaThreads and the VMThread
1019 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1020 if ((cur->allow_vm_block() &&
1021 cur != Threads_lock &&
1022 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1023 cur != VMOperationRequest_lock &&
1024 cur != VMOperationQueue_lock) ||
1025 cur->rank() == Mutex::special) {
1026 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1027 }
1028 }
1029 }
1030
1031 if (GCALotAtAllSafepoints) {
1032 // We could enter a safepoint here and thus have a gc
1033 InterfaceSupport::check_gc_alot();
1034 }
1035 }
1036 #endif // ASSERT
1037
1038 bool Thread::is_in_stack(address adr) const {
1039 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1040 address end = os::current_stack_pointer();
1041 // Allow non Java threads to call this without stack_base
1042 if (_stack_base == NULL) return true;
1043 if (stack_base() >= adr && adr >= end) return true;
1044
1045 return false;
1046 }
1047
1048 bool Thread::is_in_usable_stack(address adr) const {
1049 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1050 size_t usable_stack_size = _stack_size - stack_guard_size;
1051
1052 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1053 }
1054
1055
1056 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1057 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1058 // used for compilation in the future. If that change is made, the need for these methods
1059 // should be revisited, and they should be removed if possible.
1060
1061 bool Thread::is_lock_owned(address adr) const {
1062 return on_local_stack(adr);
1063 }
1064
1065 bool Thread::set_as_starting_thread() {
1066 assert(_starting_thread == NULL, "already initialized: "
1067 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1068 // NOTE: this must be called inside the main thread.
1069 DEBUG_ONLY(_starting_thread = this;)
1070 return os::create_main_thread((JavaThread*)this);
1071 }
1072
1073 static void initialize_class(Symbol* class_name, TRAPS) {
1074 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1075 InstanceKlass::cast(klass)->initialize(CHECK);
1076 }
1077
1078
1079 // Creates the initial ThreadGroup
1080 static Handle create_initial_thread_group(TRAPS) {
1081 Handle system_instance = JavaCalls::construct_new_instance(
1082 SystemDictionary::ThreadGroup_klass(),
1083 vmSymbols::void_method_signature(),
1084 CHECK_NH);
1085 Universe::set_system_thread_group(system_instance());
1086
1087 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1088 Handle main_instance = JavaCalls::construct_new_instance(
1089 SystemDictionary::ThreadGroup_klass(),
1090 vmSymbols::threadgroup_string_void_signature(),
1091 system_instance,
1092 string,
1093 CHECK_NH);
1094 return main_instance;
1095 }
1096
1097 // Creates the initial Thread
1098 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1099 TRAPS) {
1100 InstanceKlass* ik = SystemDictionary::Thread_klass();
1101 assert(ik->is_initialized(), "must be");
1102 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1103
1104 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1105 // constructor calls Thread.current(), which must be set here for the
1106 // initial thread.
1107 java_lang_Thread::set_thread(thread_oop(), thread);
1108 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1109 thread->set_threadObj(thread_oop());
1110
1111 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1112
1113 JavaValue result(T_VOID);
1114 JavaCalls::call_special(&result, thread_oop,
1115 ik,
1116 vmSymbols::object_initializer_name(),
1117 vmSymbols::threadgroup_string_void_signature(),
1118 thread_group,
1119 string,
1120 CHECK_NULL);
1121 return thread_oop();
1122 }
1123
1124 char java_runtime_name[128] = "";
1125 char java_runtime_version[128] = "";
1126
1127 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1128 static const char* get_java_runtime_name(TRAPS) {
1129 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1130 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1131 fieldDescriptor fd;
1132 bool found = k != NULL &&
1133 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1134 vmSymbols::string_signature(), &fd);
1135 if (found) {
1136 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1137 if (name_oop == NULL) {
1138 return NULL;
1139 }
1140 const char* name = java_lang_String::as_utf8_string(name_oop,
1141 java_runtime_name,
1142 sizeof(java_runtime_name));
1143 return name;
1144 } else {
1145 return NULL;
1146 }
1147 }
1148
1149 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1150 static const char* get_java_runtime_version(TRAPS) {
1151 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1152 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1153 fieldDescriptor fd;
1154 bool found = k != NULL &&
1155 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1156 vmSymbols::string_signature(), &fd);
1157 if (found) {
1158 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1159 if (name_oop == NULL) {
1160 return NULL;
1161 }
1162 const char* name = java_lang_String::as_utf8_string(name_oop,
1163 java_runtime_version,
1164 sizeof(java_runtime_version));
1165 return name;
1166 } else {
1167 return NULL;
1168 }
1169 }
1170
1171 // General purpose hook into Java code, run once when the VM is initialized.
1172 // The Java library method itself may be changed independently from the VM.
1173 static void call_postVMInitHook(TRAPS) {
1174 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1175 if (klass != NULL) {
1176 JavaValue result(T_VOID);
1177 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1178 vmSymbols::void_method_signature(),
1179 CHECK);
1180 }
1181 }
1182
1183 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1184 bool daemon, TRAPS) {
1185 assert(thread_group.not_null(), "thread group should be specified");
1186 assert(threadObj() == NULL, "should only create Java thread object once");
1187
1188 InstanceKlass* ik = SystemDictionary::Thread_klass();
1189 assert(ik->is_initialized(), "must be");
1190 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1191
1192 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1193 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1194 // constructor calls Thread.current(), which must be set here.
1195 java_lang_Thread::set_thread(thread_oop(), this);
1196 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1197 set_threadObj(thread_oop());
1198
1199 JavaValue result(T_VOID);
1200 if (thread_name != NULL) {
1201 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1202 // Thread gets assigned specified name and null target
1203 JavaCalls::call_special(&result,
1204 thread_oop,
1205 ik,
1206 vmSymbols::object_initializer_name(),
1207 vmSymbols::threadgroup_string_void_signature(),
1208 thread_group,
1209 name,
1210 THREAD);
1211 } else {
1212 // Thread gets assigned name "Thread-nnn" and null target
1213 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1214 JavaCalls::call_special(&result,
1215 thread_oop,
1216 ik,
1217 vmSymbols::object_initializer_name(),
1218 vmSymbols::threadgroup_runnable_void_signature(),
1219 thread_group,
1220 Handle(),
1221 THREAD);
1222 }
1223
1224
1225 if (daemon) {
1226 java_lang_Thread::set_daemon(thread_oop());
1227 }
1228
1229 if (HAS_PENDING_EXCEPTION) {
1230 return;
1231 }
1232
1233 Klass* group = SystemDictionary::ThreadGroup_klass();
1234 Handle threadObj(THREAD, this->threadObj());
1235
1236 JavaCalls::call_special(&result,
1237 thread_group,
1238 group,
1239 vmSymbols::add_method_name(),
1240 vmSymbols::thread_void_signature(),
1241 threadObj, // Arg 1
1242 THREAD);
1243 }
1244
1245 // List of all NonJavaThreads and safe iteration over that list.
1246
1247 class NonJavaThread::List {
1248 public:
1249 NonJavaThread* volatile _head;
1250 SingleWriterSynchronizer _protect;
1251
1252 List() : _head(NULL), _protect() {}
1253 };
1254
1255 NonJavaThread::List NonJavaThread::_the_list;
1256
1257 NonJavaThread::Iterator::Iterator() :
1258 _protect_enter(_the_list._protect.enter()),
1259 _current(OrderAccess::load_acquire(&_the_list._head))
1260 {}
1261
1262 NonJavaThread::Iterator::~Iterator() {
1263 _the_list._protect.exit(_protect_enter);
1264 }
1265
1266 void NonJavaThread::Iterator::step() {
1267 assert(!end(), "precondition");
1268 _current = OrderAccess::load_acquire(&_current->_next);
1269 }
1270
1271 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1272 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1273 }
1274
1275 NonJavaThread::~NonJavaThread() { }
1276
1277 void NonJavaThread::add_to_the_list() {
1278 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1279 // Initialize BarrierSet-related data before adding to list.
1280 BarrierSet::barrier_set()->on_thread_attach(this);
1281 OrderAccess::release_store(&_next, _the_list._head);
1282 OrderAccess::release_store(&_the_list._head, this);
1283 }
1284
1285 void NonJavaThread::remove_from_the_list() {
1286 {
1287 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1288 // Cleanup BarrierSet-related data before removing from list.
1289 BarrierSet::barrier_set()->on_thread_detach(this);
1290 NonJavaThread* volatile* p = &_the_list._head;
1291 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1292 if (t == this) {
1293 *p = _next;
1294 break;
1295 }
1296 }
1297 }
1298 // Wait for any in-progress iterators. Concurrent synchronize is not
1299 // allowed, so do it while holding a dedicated lock. Outside and distinct
1300 // from NJTList_lock in case an iteration attempts to lock it.
1301 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1302 _the_list._protect.synchronize();
1303 _next = NULL; // Safe to drop the link now.
1304 }
1305
1306 void NonJavaThread::pre_run() {
1307 add_to_the_list();
1308
1309 // This is slightly odd in that NamedThread is a subclass, but
1310 // in fact name() is defined in Thread
1311 assert(this->name() != NULL, "thread name was not set before it was started");
1312 this->set_native_thread_name(this->name());
1313 }
1314
1315 void NonJavaThread::post_run() {
1316 JFR_ONLY(Jfr::on_thread_exit(this);)
1317 remove_from_the_list();
1318 // Ensure thread-local-storage is cleared before termination.
1319 Thread::clear_thread_current();
1320 }
1321
1322 // NamedThread -- non-JavaThread subclasses with multiple
1323 // uniquely named instances should derive from this.
1324 NamedThread::NamedThread() :
1325 NonJavaThread(),
1326 _name(NULL),
1327 _processed_thread(NULL),
1328 _gc_id(GCId::undefined())
1329 {}
1330
1331 NamedThread::~NamedThread() {
1332 if (_name != NULL) {
1333 FREE_C_HEAP_ARRAY(char, _name);
1334 _name = NULL;
1335 }
1336 }
1337
1338 void NamedThread::set_name(const char* format, ...) {
1339 guarantee(_name == NULL, "Only get to set name once.");
1340 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1341 guarantee(_name != NULL, "alloc failure");
1342 va_list ap;
1343 va_start(ap, format);
1344 jio_vsnprintf(_name, max_name_len, format, ap);
1345 va_end(ap);
1346 }
1347
1348 void NamedThread::print_on(outputStream* st) const {
1349 st->print("\"%s\" ", name());
1350 Thread::print_on(st);
1351 st->cr();
1352 }
1353
1354
1355 // ======= WatcherThread ========
1356
1357 // The watcher thread exists to simulate timer interrupts. It should
1358 // be replaced by an abstraction over whatever native support for
1359 // timer interrupts exists on the platform.
1360
1361 WatcherThread* WatcherThread::_watcher_thread = NULL;
1362 bool WatcherThread::_startable = false;
1363 volatile bool WatcherThread::_should_terminate = false;
1364
1365 WatcherThread::WatcherThread() : NonJavaThread() {
1366 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1367 if (os::create_thread(this, os::watcher_thread)) {
1368 _watcher_thread = this;
1369
1370 // Set the watcher thread to the highest OS priority which should not be
1371 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1372 // is created. The only normal thread using this priority is the reference
1373 // handler thread, which runs for very short intervals only.
1374 // If the VMThread's priority is not lower than the WatcherThread profiling
1375 // will be inaccurate.
1376 os::set_priority(this, MaxPriority);
1377 if (!DisableStartThread) {
1378 os::start_thread(this);
1379 }
1380 }
1381 }
1382
1383 int WatcherThread::sleep() const {
1384 // The WatcherThread does not participate in the safepoint protocol
1385 // for the PeriodicTask_lock because it is not a JavaThread.
1386 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1387
1388 if (_should_terminate) {
1389 // check for termination before we do any housekeeping or wait
1390 return 0; // we did not sleep.
1391 }
1392
1393 // remaining will be zero if there are no tasks,
1394 // causing the WatcherThread to sleep until a task is
1395 // enrolled
1396 int remaining = PeriodicTask::time_to_wait();
1397 int time_slept = 0;
1398
1399 // we expect this to timeout - we only ever get unparked when
1400 // we should terminate or when a new task has been enrolled
1401 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1402
1403 jlong time_before_loop = os::javaTimeNanos();
1404
1405 while (true) {
1406 bool timedout = ml.wait(remaining);
1407 jlong now = os::javaTimeNanos();
1408
1409 if (remaining == 0) {
1410 // if we didn't have any tasks we could have waited for a long time
1411 // consider the time_slept zero and reset time_before_loop
1412 time_slept = 0;
1413 time_before_loop = now;
1414 } else {
1415 // need to recalculate since we might have new tasks in _tasks
1416 time_slept = (int) ((now - time_before_loop) / 1000000);
1417 }
1418
1419 // Change to task list or spurious wakeup of some kind
1420 if (timedout || _should_terminate) {
1421 break;
1422 }
1423
1424 remaining = PeriodicTask::time_to_wait();
1425 if (remaining == 0) {
1426 // Last task was just disenrolled so loop around and wait until
1427 // another task gets enrolled
1428 continue;
1429 }
1430
1431 remaining -= time_slept;
1432 if (remaining <= 0) {
1433 break;
1434 }
1435 }
1436
1437 return time_slept;
1438 }
1439
1440 void WatcherThread::run() {
1441 assert(this == watcher_thread(), "just checking");
1442
1443 this->set_active_handles(JNIHandleBlock::allocate_block());
1444 while (true) {
1445 assert(watcher_thread() == Thread::current(), "thread consistency check");
1446 assert(watcher_thread() == this, "thread consistency check");
1447
1448 // Calculate how long it'll be until the next PeriodicTask work
1449 // should be done, and sleep that amount of time.
1450 int time_waited = sleep();
1451
1452 if (VMError::is_error_reported()) {
1453 // A fatal error has happened, the error handler(VMError::report_and_die)
1454 // should abort JVM after creating an error log file. However in some
1455 // rare cases, the error handler itself might deadlock. Here periodically
1456 // check for error reporting timeouts, and if it happens, just proceed to
1457 // abort the VM.
1458
1459 // This code is in WatcherThread because WatcherThread wakes up
1460 // periodically so the fatal error handler doesn't need to do anything;
1461 // also because the WatcherThread is less likely to crash than other
1462 // threads.
1463
1464 for (;;) {
1465 // Note: we use naked sleep in this loop because we want to avoid using
1466 // any kind of VM infrastructure which may be broken at this point.
1467 if (VMError::check_timeout()) {
1468 // We hit error reporting timeout. Error reporting was interrupted and
1469 // will be wrapping things up now (closing files etc). Give it some more
1470 // time, then quit the VM.
1471 os::naked_short_sleep(200);
1472 // Print a message to stderr.
1473 fdStream err(defaultStream::output_fd());
1474 err.print_raw_cr("# [ timer expired, abort... ]");
1475 // skip atexit/vm_exit/vm_abort hooks
1476 os::die();
1477 }
1478
1479 // Wait a second, then recheck for timeout.
1480 os::naked_short_sleep(999);
1481 }
1482 }
1483
1484 if (_should_terminate) {
1485 // check for termination before posting the next tick
1486 break;
1487 }
1488
1489 PeriodicTask::real_time_tick(time_waited);
1490 }
1491
1492 // Signal that it is terminated
1493 {
1494 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1495 _watcher_thread = NULL;
1496 Terminator_lock->notify_all();
1497 }
1498 }
1499
1500 void WatcherThread::start() {
1501 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1502
1503 if (watcher_thread() == NULL && _startable) {
1504 _should_terminate = false;
1505 // Create the single instance of WatcherThread
1506 new WatcherThread();
1507 }
1508 }
1509
1510 void WatcherThread::make_startable() {
1511 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1512 _startable = true;
1513 }
1514
1515 void WatcherThread::stop() {
1516 {
1517 // Follow normal safepoint aware lock enter protocol since the
1518 // WatcherThread is stopped by another JavaThread.
1519 MutexLocker ml(PeriodicTask_lock);
1520 _should_terminate = true;
1521
1522 WatcherThread* watcher = watcher_thread();
1523 if (watcher != NULL) {
1524 // unpark the WatcherThread so it can see that it should terminate
1525 watcher->unpark();
1526 }
1527 }
1528
1529 MonitorLocker mu(Terminator_lock);
1530
1531 while (watcher_thread() != NULL) {
1532 // This wait should make safepoint checks, wait without a timeout,
1533 // and wait as a suspend-equivalent condition.
1534 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1535 }
1536 }
1537
1538 void WatcherThread::unpark() {
1539 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1540 PeriodicTask_lock->notify();
1541 }
1542
1543 void WatcherThread::print_on(outputStream* st) const {
1544 st->print("\"%s\" ", name());
1545 Thread::print_on(st);
1546 st->cr();
1547 }
1548
1549 // ======= JavaThread ========
1550
1551 #if INCLUDE_JVMCI
1552
1553 jlong* JavaThread::_jvmci_old_thread_counters;
1554
1555 bool jvmci_counters_include(JavaThread* thread) {
1556 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1557 }
1558
1559 void JavaThread::collect_counters(jlong* array, int length) {
1560 assert(length == JVMCICounterSize, "wrong value");
1561 for (int i = 0; i < length; i++) {
1562 array[i] = _jvmci_old_thread_counters[i];
1563 }
1564 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1565 if (jvmci_counters_include(tp)) {
1566 for (int i = 0; i < length; i++) {
1567 array[i] += tp->_jvmci_counters[i];
1568 }
1569 }
1570 }
1571 }
1572
1573 // Attempt to enlarge the array for per thread counters.
1574 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1575 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1576 if (new_counters == NULL) {
1577 return NULL;
1578 }
1579 if (old_counters == NULL) {
1580 old_counters = new_counters;
1581 memset(old_counters, 0, sizeof(jlong) * new_size);
1582 } else {
1583 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1584 new_counters[i] = old_counters[i];
1585 }
1586 if (new_size > current_size) {
1587 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1588 }
1589 FREE_C_HEAP_ARRAY(jlong, old_counters);
1590 }
1591 return new_counters;
1592 }
1593
1594 // Attempt to enlarge the array for per thread counters.
1595 bool JavaThread::resize_counters(int current_size, int new_size) {
1596 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1597 if (new_counters == NULL) {
1598 return false;
1599 } else {
1600 _jvmci_counters = new_counters;
1601 return true;
1602 }
1603 }
1604
1605 class VM_JVMCIResizeCounters : public VM_Operation {
1606 private:
1607 int _new_size;
1608 bool _failed;
1609
1610 public:
1611 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1612 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1613 bool allow_nested_vm_operations() const { return true; }
1614 void doit() {
1615 // Resize the old thread counters array
1616 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1617 if (new_counters == NULL) {
1618 _failed = true;
1619 return;
1620 } else {
1621 JavaThread::_jvmci_old_thread_counters = new_counters;
1622 }
1623
1624 // Now resize each threads array
1625 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1626 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1627 _failed = true;
1628 break;
1629 }
1630 }
1631 if (!_failed) {
1632 JVMCICounterSize = _new_size;
1633 }
1634 }
1635
1636 bool failed() { return _failed; }
1637 };
1638
1639 bool JavaThread::resize_all_jvmci_counters(int new_size) {
1640 VM_JVMCIResizeCounters op(new_size);
1641 VMThread::execute(&op);
1642 return !op.failed();
1643 }
1644
1645 #endif // INCLUDE_JVMCI
1646
1647 // A JavaThread is a normal Java thread
1648
1649 void JavaThread::initialize() {
1650 // Initialize fields
1651
1652 set_saved_exception_pc(NULL);
1653 set_threadObj(NULL);
1654 _anchor.clear();
1655 set_entry_point(NULL);
1656 set_jni_functions(jni_functions());
1657 set_callee_target(NULL);
1658 set_vm_result(NULL);
1659 set_vm_result_2(NULL);
1660 set_vframe_array_head(NULL);
1661 set_vframe_array_last(NULL);
1662 set_deferred_locals(NULL);
1663 set_deopt_mark(NULL);
1664 set_deopt_compiled_method(NULL);
1665 set_monitor_chunks(NULL);
1666 _on_thread_list = false;
1667 set_thread_state(_thread_new);
1668 _terminated = _not_terminated;
1669 _array_for_gc = NULL;
1670 _suspend_equivalent = false;
1671 _in_deopt_handler = 0;
1672 _doing_unsafe_access = false;
1673 _stack_guard_state = stack_guard_unused;
1674 #if INCLUDE_JVMCI
1675 _pending_monitorenter = false;
1676 _pending_deoptimization = -1;
1677 _pending_failed_speculation = 0;
1678 _pending_transfer_to_interpreter = false;
1679 _in_retryable_allocation = false;
1680 _jvmci._alternate_call_target = NULL;
1681 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1682 _jvmci_counters = NULL;
1683 if (JVMCICounterSize > 0) {
1684 resize_counters(0, (int) JVMCICounterSize);
1685 }
1686 #endif // INCLUDE_JVMCI
1687 _reserved_stack_activation = NULL; // stack base not known yet
1688 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1689 _exception_pc = 0;
1690 _exception_handler_pc = 0;
1691 _is_method_handle_return = 0;
1692 _jvmti_thread_state= NULL;
1693 _should_post_on_exceptions_flag = JNI_FALSE;
1694 _interp_only_mode = 0;
1695 _special_runtime_exit_condition = _no_async_condition;
1696 _pending_async_exception = NULL;
1697 _thread_stat = NULL;
1698 _thread_stat = new ThreadStatistics();
1699 _jni_active_critical = 0;
1700 _pending_jni_exception_check_fn = NULL;
1701 _do_not_unlock_if_synchronized = false;
1702 _cached_monitor_info = NULL;
1703 _parker = Parker::Allocate(this);
1704
1705 // Setup safepoint state info for this thread
1706 ThreadSafepointState::create(this);
1707
1708 debug_only(_java_call_counter = 0);
1709
1710 // JVMTI PopFrame support
1711 _popframe_condition = popframe_inactive;
1712 _popframe_preserved_args = NULL;
1713 _popframe_preserved_args_size = 0;
1714 _frames_to_pop_failed_realloc = 0;
1715
1716 if (SafepointMechanism::uses_thread_local_poll()) {
1717 SafepointMechanism::initialize_header(this);
1718 }
1719
1720 _class_to_be_initialized = NULL;
1721
1722 pd_initialize();
1723 }
1724
1725 JavaThread::JavaThread(bool is_attaching_via_jni) :
1726 Thread() {
1727 initialize();
1728 if (is_attaching_via_jni) {
1729 _jni_attach_state = _attaching_via_jni;
1730 } else {
1731 _jni_attach_state = _not_attaching_via_jni;
1732 }
1733 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1734 }
1735
1736 bool JavaThread::reguard_stack(address cur_sp) {
1737 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1738 && _stack_guard_state != stack_guard_reserved_disabled) {
1739 return true; // Stack already guarded or guard pages not needed.
1740 }
1741
1742 if (register_stack_overflow()) {
1743 // For those architectures which have separate register and
1744 // memory stacks, we must check the register stack to see if
1745 // it has overflowed.
1746 return false;
1747 }
1748
1749 // Java code never executes within the yellow zone: the latter is only
1750 // there to provoke an exception during stack banging. If java code
1751 // is executing there, either StackShadowPages should be larger, or
1752 // some exception code in c1, c2 or the interpreter isn't unwinding
1753 // when it should.
1754 guarantee(cur_sp > stack_reserved_zone_base(),
1755 "not enough space to reguard - increase StackShadowPages");
1756 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1757 enable_stack_yellow_reserved_zone();
1758 if (reserved_stack_activation() != stack_base()) {
1759 set_reserved_stack_activation(stack_base());
1760 }
1761 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1762 set_reserved_stack_activation(stack_base());
1763 enable_stack_reserved_zone();
1764 }
1765 return true;
1766 }
1767
1768 bool JavaThread::reguard_stack(void) {
1769 return reguard_stack(os::current_stack_pointer());
1770 }
1771
1772
1773 void JavaThread::block_if_vm_exited() {
1774 if (_terminated == _vm_exited) {
1775 // _vm_exited is set at safepoint, and Threads_lock is never released
1776 // we will block here forever
1777 Threads_lock->lock();
1778 ShouldNotReachHere();
1779 }
1780 }
1781
1782
1783 // Remove this ifdef when C1 is ported to the compiler interface.
1784 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1785 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1786
1787 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1788 Thread() {
1789 initialize();
1790 _jni_attach_state = _not_attaching_via_jni;
1791 set_entry_point(entry_point);
1792 // Create the native thread itself.
1793 // %note runtime_23
1794 os::ThreadType thr_type = os::java_thread;
1795 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1796 os::java_thread;
1797 os::create_thread(this, thr_type, stack_sz);
1798 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1799 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1800 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1801 // the exception consists of creating the exception object & initializing it, initialization
1802 // will leave the VM via a JavaCall and then all locks must be unlocked).
1803 //
1804 // The thread is still suspended when we reach here. Thread must be explicit started
1805 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1806 // by calling Threads:add. The reason why this is not done here, is because the thread
1807 // object must be fully initialized (take a look at JVM_Start)
1808 }
1809
1810 JavaThread::~JavaThread() {
1811
1812 // JSR166 -- return the parker to the free list
1813 Parker::Release(_parker);
1814 _parker = NULL;
1815
1816 // Free any remaining previous UnrollBlock
1817 vframeArray* old_array = vframe_array_last();
1818
1819 if (old_array != NULL) {
1820 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1821 old_array->set_unroll_block(NULL);
1822 delete old_info;
1823 delete old_array;
1824 }
1825
1826 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1827 if (deferred != NULL) {
1828 // This can only happen if thread is destroyed before deoptimization occurs.
1829 assert(deferred->length() != 0, "empty array!");
1830 do {
1831 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1832 deferred->remove_at(0);
1833 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1834 delete dlv;
1835 } while (deferred->length() != 0);
1836 delete deferred;
1837 }
1838
1839 // All Java related clean up happens in exit
1840 ThreadSafepointState::destroy(this);
1841 if (_thread_stat != NULL) delete _thread_stat;
1842
1843 #if INCLUDE_JVMCI
1844 if (JVMCICounterSize > 0) {
1845 if (jvmci_counters_include(this)) {
1846 for (int i = 0; i < JVMCICounterSize; i++) {
1847 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1848 }
1849 }
1850 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1851 }
1852 #endif // INCLUDE_JVMCI
1853 }
1854
1855
1856 // First JavaThread specific code executed by a new Java thread.
1857 void JavaThread::pre_run() {
1858 // empty - see comments in run()
1859 }
1860
1861 // The main routine called by a new Java thread. This isn't overridden
1862 // by subclasses, instead different subclasses define a different "entry_point"
1863 // which defines the actual logic for that kind of thread.
1864 void JavaThread::run() {
1865 // initialize thread-local alloc buffer related fields
1866 this->initialize_tlab();
1867
1868 // Used to test validity of stack trace backs.
1869 // This can't be moved into pre_run() else we invalidate
1870 // the requirement that thread_main_inner is lower on
1871 // the stack. Consequently all the initialization logic
1872 // stays here in run() rather than pre_run().
1873 this->record_base_of_stack_pointer();
1874
1875 this->create_stack_guard_pages();
1876
1877 this->cache_global_variables();
1878
1879 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1880 // in the VM. Change thread state from _thread_new to _thread_in_vm
1881 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1882 // Before a thread is on the threads list it is always safe, so after leaving the
1883 // _thread_new we should emit a instruction barrier. The distance to modified code
1884 // from here is probably far enough, but this is consistent and safe.
1885 OrderAccess::cross_modify_fence();
1886
1887 assert(JavaThread::current() == this, "sanity check");
1888 assert(!Thread::current()->owns_locks(), "sanity check");
1889
1890 DTRACE_THREAD_PROBE(start, this);
1891
1892 // This operation might block. We call that after all safepoint checks for a new thread has
1893 // been completed.
1894 this->set_active_handles(JNIHandleBlock::allocate_block());
1895
1896 if (JvmtiExport::should_post_thread_life()) {
1897 JvmtiExport::post_thread_start(this);
1898
1899 }
1900
1901 // We call another function to do the rest so we are sure that the stack addresses used
1902 // from there will be lower than the stack base just computed.
1903 thread_main_inner();
1904 }
1905
1906 void JavaThread::thread_main_inner() {
1907 assert(JavaThread::current() == this, "sanity check");
1908 assert(this->threadObj() != NULL, "just checking");
1909
1910 // Execute thread entry point unless this thread has a pending exception
1911 // or has been stopped before starting.
1912 // Note: Due to JVM_StopThread we can have pending exceptions already!
1913 if (!this->has_pending_exception() &&
1914 !java_lang_Thread::is_stillborn(this->threadObj())) {
1915 {
1916 ResourceMark rm(this);
1917 this->set_native_thread_name(this->get_thread_name());
1918 }
1919 HandleMark hm(this);
1920 this->entry_point()(this, this);
1921 }
1922
1923 DTRACE_THREAD_PROBE(stop, this);
1924
1925 // Cleanup is handled in post_run()
1926 }
1927
1928 // Shared teardown for all JavaThreads
1929 void JavaThread::post_run() {
1930 this->exit(false);
1931 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1932 // for any shared tear-down.
1933 this->smr_delete();
1934 }
1935
1936 static void ensure_join(JavaThread* thread) {
1937 // We do not need to grab the Threads_lock, since we are operating on ourself.
1938 Handle threadObj(thread, thread->threadObj());
1939 assert(threadObj.not_null(), "java thread object must exist");
1940 ObjectLocker lock(threadObj, thread);
1941 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1942 thread->clear_pending_exception();
1943 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1944 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1945 // Clear the native thread instance - this makes isAlive return false and allows the join()
1946 // to complete once we've done the notify_all below
1947 java_lang_Thread::set_thread(threadObj(), NULL);
1948 lock.notify_all(thread);
1949 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1950 thread->clear_pending_exception();
1951 }
1952
1953 static bool is_daemon(oop threadObj) {
1954 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1955 }
1956
1957 // For any new cleanup additions, please check to see if they need to be applied to
1958 // cleanup_failed_attach_current_thread as well.
1959 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1960 assert(this == JavaThread::current(), "thread consistency check");
1961
1962 elapsedTimer _timer_exit_phase1;
1963 elapsedTimer _timer_exit_phase2;
1964 elapsedTimer _timer_exit_phase3;
1965 elapsedTimer _timer_exit_phase4;
1966
1967 if (log_is_enabled(Debug, os, thread, timer)) {
1968 _timer_exit_phase1.start();
1969 }
1970
1971 HandleMark hm(this);
1972 Handle uncaught_exception(this, this->pending_exception());
1973 this->clear_pending_exception();
1974 Handle threadObj(this, this->threadObj());
1975 assert(threadObj.not_null(), "Java thread object should be created");
1976
1977 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1978 {
1979 EXCEPTION_MARK;
1980
1981 CLEAR_PENDING_EXCEPTION;
1982 }
1983 if (!destroy_vm) {
1984 if (uncaught_exception.not_null()) {
1985 EXCEPTION_MARK;
1986 // Call method Thread.dispatchUncaughtException().
1987 Klass* thread_klass = SystemDictionary::Thread_klass();
1988 JavaValue result(T_VOID);
1989 JavaCalls::call_virtual(&result,
1990 threadObj, thread_klass,
1991 vmSymbols::dispatchUncaughtException_name(),
1992 vmSymbols::throwable_void_signature(),
1993 uncaught_exception,
1994 THREAD);
1995 if (HAS_PENDING_EXCEPTION) {
1996 ResourceMark rm(this);
1997 jio_fprintf(defaultStream::error_stream(),
1998 "\nException: %s thrown from the UncaughtExceptionHandler"
1999 " in thread \"%s\"\n",
2000 pending_exception()->klass()->external_name(),
2001 get_thread_name());
2002 CLEAR_PENDING_EXCEPTION;
2003 }
2004 }
2005 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2006
2007 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2008 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2009 // is deprecated anyhow.
2010 if (!is_Compiler_thread()) {
2011 int count = 3;
2012 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2013 EXCEPTION_MARK;
2014 JavaValue result(T_VOID);
2015 Klass* thread_klass = SystemDictionary::Thread_klass();
2016 JavaCalls::call_virtual(&result,
2017 threadObj, thread_klass,
2018 vmSymbols::exit_method_name(),
2019 vmSymbols::void_method_signature(),
2020 THREAD);
2021 CLEAR_PENDING_EXCEPTION;
2022 }
2023 }
2024 // notify JVMTI
2025 if (JvmtiExport::should_post_thread_life()) {
2026 JvmtiExport::post_thread_end(this);
2027 }
2028
2029 // We have notified the agents that we are exiting, before we go on,
2030 // we must check for a pending external suspend request and honor it
2031 // in order to not surprise the thread that made the suspend request.
2032 while (true) {
2033 {
2034 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2035 if (!is_external_suspend()) {
2036 set_terminated(_thread_exiting);
2037 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2038 break;
2039 }
2040 // Implied else:
2041 // Things get a little tricky here. We have a pending external
2042 // suspend request, but we are holding the SR_lock so we
2043 // can't just self-suspend. So we temporarily drop the lock
2044 // and then self-suspend.
2045 }
2046
2047 ThreadBlockInVM tbivm(this);
2048 java_suspend_self();
2049
2050 // We're done with this suspend request, but we have to loop around
2051 // and check again. Eventually we will get SR_lock without a pending
2052 // external suspend request and will be able to mark ourselves as
2053 // exiting.
2054 }
2055 // no more external suspends are allowed at this point
2056 } else {
2057 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2058 // before_exit() has already posted JVMTI THREAD_END events
2059 }
2060
2061 if (log_is_enabled(Debug, os, thread, timer)) {
2062 _timer_exit_phase1.stop();
2063 _timer_exit_phase2.start();
2064 }
2065
2066 // Capture daemon status before the thread is marked as terminated.
2067 bool daemon = is_daemon(threadObj());
2068
2069 // Notify waiters on thread object. This has to be done after exit() is called
2070 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2071 // group should have the destroyed bit set before waiters are notified).
2072 ensure_join(this);
2073 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2074
2075 if (log_is_enabled(Debug, os, thread, timer)) {
2076 _timer_exit_phase2.stop();
2077 _timer_exit_phase3.start();
2078 }
2079 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2080 // held by this thread must be released. The spec does not distinguish
2081 // between JNI-acquired and regular Java monitors. We can only see
2082 // regular Java monitors here if monitor enter-exit matching is broken.
2083 //
2084 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2085 // ObjectSynchronizer::release_monitors_owned_by_thread().
2086 if (exit_type == jni_detach) {
2087 // Sanity check even though JNI DetachCurrentThread() would have
2088 // returned JNI_ERR if there was a Java frame. JavaThread exit
2089 // should be done executing Java code by the time we get here.
2090 assert(!this->has_last_Java_frame(),
2091 "should not have a Java frame when detaching or exiting");
2092 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2093 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2094 }
2095
2096 // These things needs to be done while we are still a Java Thread. Make sure that thread
2097 // is in a consistent state, in case GC happens
2098 JFR_ONLY(Jfr::on_thread_exit(this);)
2099
2100 if (active_handles() != NULL) {
2101 JNIHandleBlock* block = active_handles();
2102 set_active_handles(NULL);
2103 JNIHandleBlock::release_block(block);
2104 }
2105
2106 if (free_handle_block() != NULL) {
2107 JNIHandleBlock* block = free_handle_block();
2108 set_free_handle_block(NULL);
2109 JNIHandleBlock::release_block(block);
2110 }
2111
2112 // These have to be removed while this is still a valid thread.
2113 remove_stack_guard_pages();
2114
2115 if (UseTLAB) {
2116 tlab().retire();
2117 }
2118
2119 if (JvmtiEnv::environments_might_exist()) {
2120 JvmtiExport::cleanup_thread(this);
2121 }
2122
2123 // We must flush any deferred card marks and other various GC barrier
2124 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2125 // before removing a thread from the list of active threads.
2126 BarrierSet::barrier_set()->on_thread_detach(this);
2127
2128 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2129 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2130 os::current_thread_id());
2131
2132 if (log_is_enabled(Debug, os, thread, timer)) {
2133 _timer_exit_phase3.stop();
2134 _timer_exit_phase4.start();
2135 }
2136 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2137 Threads::remove(this, daemon);
2138
2139 if (log_is_enabled(Debug, os, thread, timer)) {
2140 _timer_exit_phase4.stop();
2141 ResourceMark rm(this);
2142 log_debug(os, thread, timer)("name='%s'"
2143 ", exit-phase1=" JLONG_FORMAT
2144 ", exit-phase2=" JLONG_FORMAT
2145 ", exit-phase3=" JLONG_FORMAT
2146 ", exit-phase4=" JLONG_FORMAT,
2147 get_thread_name(),
2148 _timer_exit_phase1.milliseconds(),
2149 _timer_exit_phase2.milliseconds(),
2150 _timer_exit_phase3.milliseconds(),
2151 _timer_exit_phase4.milliseconds());
2152 }
2153 }
2154
2155 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2156 if (active_handles() != NULL) {
2157 JNIHandleBlock* block = active_handles();
2158 set_active_handles(NULL);
2159 JNIHandleBlock::release_block(block);
2160 }
2161
2162 if (free_handle_block() != NULL) {
2163 JNIHandleBlock* block = free_handle_block();
2164 set_free_handle_block(NULL);
2165 JNIHandleBlock::release_block(block);
2166 }
2167
2168 // These have to be removed while this is still a valid thread.
2169 remove_stack_guard_pages();
2170
2171 if (UseTLAB) {
2172 tlab().retire();
2173 }
2174
2175 BarrierSet::barrier_set()->on_thread_detach(this);
2176
2177 Threads::remove(this, is_daemon);
2178 this->smr_delete();
2179 }
2180
2181 JavaThread* JavaThread::active() {
2182 Thread* thread = Thread::current();
2183 if (thread->is_Java_thread()) {
2184 return (JavaThread*) thread;
2185 } else {
2186 assert(thread->is_VM_thread(), "this must be a vm thread");
2187 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2188 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2189 assert(ret->is_Java_thread(), "must be a Java thread");
2190 return ret;
2191 }
2192 }
2193
2194 bool JavaThread::is_lock_owned(address adr) const {
2195 if (Thread::is_lock_owned(adr)) return true;
2196
2197 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2198 if (chunk->contains(adr)) return true;
2199 }
2200
2201 return false;
2202 }
2203
2204
2205 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2206 chunk->set_next(monitor_chunks());
2207 set_monitor_chunks(chunk);
2208 }
2209
2210 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2211 guarantee(monitor_chunks() != NULL, "must be non empty");
2212 if (monitor_chunks() == chunk) {
2213 set_monitor_chunks(chunk->next());
2214 } else {
2215 MonitorChunk* prev = monitor_chunks();
2216 while (prev->next() != chunk) prev = prev->next();
2217 prev->set_next(chunk->next());
2218 }
2219 }
2220
2221 // JVM support.
2222
2223 // Note: this function shouldn't block if it's called in
2224 // _thread_in_native_trans state (such as from
2225 // check_special_condition_for_native_trans()).
2226 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2227
2228 if (has_last_Java_frame() && has_async_condition()) {
2229 // If we are at a polling page safepoint (not a poll return)
2230 // then we must defer async exception because live registers
2231 // will be clobbered by the exception path. Poll return is
2232 // ok because the call we a returning from already collides
2233 // with exception handling registers and so there is no issue.
2234 // (The exception handling path kills call result registers but
2235 // this is ok since the exception kills the result anyway).
2236
2237 if (is_at_poll_safepoint()) {
2238 // if the code we are returning to has deoptimized we must defer
2239 // the exception otherwise live registers get clobbered on the
2240 // exception path before deoptimization is able to retrieve them.
2241 //
2242 RegisterMap map(this, false);
2243 frame caller_fr = last_frame().sender(&map);
2244 assert(caller_fr.is_compiled_frame(), "what?");
2245 if (caller_fr.is_deoptimized_frame()) {
2246 log_info(exceptions)("deferred async exception at compiled safepoint");
2247 return;
2248 }
2249 }
2250 }
2251
2252 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2253 if (condition == _no_async_condition) {
2254 // Conditions have changed since has_special_runtime_exit_condition()
2255 // was called:
2256 // - if we were here only because of an external suspend request,
2257 // then that was taken care of above (or cancelled) so we are done
2258 // - if we were here because of another async request, then it has
2259 // been cleared between the has_special_runtime_exit_condition()
2260 // and now so again we are done
2261 return;
2262 }
2263
2264 // Check for pending async. exception
2265 if (_pending_async_exception != NULL) {
2266 // Only overwrite an already pending exception, if it is not a threadDeath.
2267 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2268
2269 // We cannot call Exceptions::_throw(...) here because we cannot block
2270 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2271
2272 LogTarget(Info, exceptions) lt;
2273 if (lt.is_enabled()) {
2274 ResourceMark rm;
2275 LogStream ls(lt);
2276 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2277 if (has_last_Java_frame()) {
2278 frame f = last_frame();
2279 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2280 }
2281 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2282 }
2283 _pending_async_exception = NULL;
2284 clear_has_async_exception();
2285 }
2286 }
2287
2288 if (check_unsafe_error &&
2289 condition == _async_unsafe_access_error && !has_pending_exception()) {
2290 condition = _no_async_condition; // done
2291 switch (thread_state()) {
2292 case _thread_in_vm: {
2293 JavaThread* THREAD = this;
2294 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2295 }
2296 case _thread_in_native: {
2297 ThreadInVMfromNative tiv(this);
2298 JavaThread* THREAD = this;
2299 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2300 }
2301 case _thread_in_Java: {
2302 ThreadInVMfromJava tiv(this);
2303 JavaThread* THREAD = this;
2304 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2305 }
2306 default:
2307 ShouldNotReachHere();
2308 }
2309 }
2310
2311 assert(condition == _no_async_condition || has_pending_exception() ||
2312 (!check_unsafe_error && condition == _async_unsafe_access_error),
2313 "must have handled the async condition, if no exception");
2314 }
2315
2316 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2317
2318 // Check for pending external suspend.
2319 if (is_external_suspend_with_lock()) {
2320 frame_anchor()->make_walkable(this);
2321 java_suspend_self_with_safepoint_check();
2322 }
2323
2324 // We might be here for reasons in addition to the self-suspend request
2325 // so check for other async requests.
2326 if (check_asyncs) {
2327 check_and_handle_async_exceptions();
2328 }
2329
2330 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2331 }
2332
2333 void JavaThread::send_thread_stop(oop java_throwable) {
2334 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2335 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2336 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2337
2338 // Do not throw asynchronous exceptions against the compiler thread
2339 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2340 if (!can_call_java()) return;
2341
2342 {
2343 // Actually throw the Throwable against the target Thread - however
2344 // only if there is no thread death exception installed already.
2345 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2346 // If the topmost frame is a runtime stub, then we are calling into
2347 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2348 // must deoptimize the caller before continuing, as the compiled exception handler table
2349 // may not be valid
2350 if (has_last_Java_frame()) {
2351 frame f = last_frame();
2352 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2353 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2354 RegisterMap reg_map(this, UseBiasedLocking);
2355 frame compiled_frame = f.sender(®_map);
2356 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2357 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2358 }
2359 }
2360 }
2361
2362 // Set async. pending exception in thread.
2363 set_pending_async_exception(java_throwable);
2364
2365 if (log_is_enabled(Info, exceptions)) {
2366 ResourceMark rm;
2367 log_info(exceptions)("Pending Async. exception installed of type: %s",
2368 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2369 }
2370 // for AbortVMOnException flag
2371 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2372 }
2373 }
2374
2375
2376 // Interrupt thread so it will wake up from a potential wait()
2377 Thread::interrupt(this);
2378 }
2379
2380 // External suspension mechanism.
2381 //
2382 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2383 // to any VM_locks and it is at a transition
2384 // Self-suspension will happen on the transition out of the vm.
2385 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2386 //
2387 // Guarantees on return:
2388 // + Target thread will not execute any new bytecode (that's why we need to
2389 // force a safepoint)
2390 // + Target thread will not enter any new monitors
2391 //
2392 void JavaThread::java_suspend() {
2393 ThreadsListHandle tlh;
2394 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2395 return;
2396 }
2397
2398 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2399 if (!is_external_suspend()) {
2400 // a racing resume has cancelled us; bail out now
2401 return;
2402 }
2403
2404 // suspend is done
2405 uint32_t debug_bits = 0;
2406 // Warning: is_ext_suspend_completed() may temporarily drop the
2407 // SR_lock to allow the thread to reach a stable thread state if
2408 // it is currently in a transient thread state.
2409 if (is_ext_suspend_completed(false /* !called_by_wait */,
2410 SuspendRetryDelay, &debug_bits)) {
2411 return;
2412 }
2413 }
2414
2415 if (Thread::current() == this) {
2416 // Safely self-suspend.
2417 // If we don't do this explicitly it will implicitly happen
2418 // before we transition back to Java, and on some other thread-state
2419 // transition paths, but not as we exit a JVM TI SuspendThread call.
2420 // As SuspendThread(current) must not return (until resumed) we must
2421 // self-suspend here.
2422 ThreadBlockInVM tbivm(this);
2423 java_suspend_self();
2424 } else {
2425 VM_ThreadSuspend vm_suspend;
2426 VMThread::execute(&vm_suspend);
2427 }
2428 }
2429
2430 // Part II of external suspension.
2431 // A JavaThread self suspends when it detects a pending external suspend
2432 // request. This is usually on transitions. It is also done in places
2433 // where continuing to the next transition would surprise the caller,
2434 // e.g., monitor entry.
2435 //
2436 // Returns the number of times that the thread self-suspended.
2437 //
2438 // Note: DO NOT call java_suspend_self() when you just want to block current
2439 // thread. java_suspend_self() is the second stage of cooperative
2440 // suspension for external suspend requests and should only be used
2441 // to complete an external suspend request.
2442 //
2443 int JavaThread::java_suspend_self() {
2444 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2445 int ret = 0;
2446
2447 // we are in the process of exiting so don't suspend
2448 if (is_exiting()) {
2449 clear_external_suspend();
2450 return ret;
2451 }
2452
2453 assert(_anchor.walkable() ||
2454 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2455 "must have walkable stack");
2456
2457 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2458
2459 assert(!this->is_ext_suspended(),
2460 "a thread trying to self-suspend should not already be suspended");
2461
2462 if (this->is_suspend_equivalent()) {
2463 // If we are self-suspending as a result of the lifting of a
2464 // suspend equivalent condition, then the suspend_equivalent
2465 // flag is not cleared until we set the ext_suspended flag so
2466 // that wait_for_ext_suspend_completion() returns consistent
2467 // results.
2468 this->clear_suspend_equivalent();
2469 }
2470
2471 // A racing resume may have cancelled us before we grabbed SR_lock
2472 // above. Or another external suspend request could be waiting for us
2473 // by the time we return from SR_lock()->wait(). The thread
2474 // that requested the suspension may already be trying to walk our
2475 // stack and if we return now, we can change the stack out from under
2476 // it. This would be a "bad thing (TM)" and cause the stack walker
2477 // to crash. We stay self-suspended until there are no more pending
2478 // external suspend requests.
2479 while (is_external_suspend()) {
2480 ret++;
2481 this->set_ext_suspended();
2482
2483 // _ext_suspended flag is cleared by java_resume()
2484 while (is_ext_suspended()) {
2485 ml.wait();
2486 }
2487 }
2488 return ret;
2489 }
2490
2491 // Helper routine to set up the correct thread state before calling java_suspend_self.
2492 // This is called when regular thread-state transition helpers can't be used because
2493 // we can be in various states, in particular _thread_in_native_trans.
2494 // Because this thread is external suspended the safepoint code will count it as at
2495 // a safepoint, regardless of what its actual current thread-state is. But
2496 // is_ext_suspend_completed() may be waiting to see a thread transition from
2497 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2498 // to _thread_blocked. The problem with setting thread state directly is that a
2499 // safepoint could happen just after java_suspend_self() returns after being resumed,
2500 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2501 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2502 // However, not all initial-states are allowed when performing a safepoint check, as we
2503 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2504 // only _thread_in_native is possible when executing this code (based on our two callers).
2505 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2506 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2507 // and so we don't need the explicit safepoint check.
2508
2509 void JavaThread::java_suspend_self_with_safepoint_check() {
2510 assert(this == Thread::current(), "invariant");
2511 JavaThreadState state = thread_state();
2512 set_thread_state(_thread_blocked);
2513 java_suspend_self();
2514 set_thread_state_fence(state);
2515 // Since we are not using a regular thread-state transition helper here,
2516 // we must manually emit the instruction barrier after leaving a safe state.
2517 OrderAccess::cross_modify_fence();
2518 if (state != _thread_in_native) {
2519 SafepointMechanism::block_if_requested(this);
2520 }
2521 }
2522
2523 #ifdef ASSERT
2524 // Verify the JavaThread has not yet been published in the Threads::list, and
2525 // hence doesn't need protection from concurrent access at this stage.
2526 void JavaThread::verify_not_published() {
2527 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2528 // since an unpublished JavaThread doesn't participate in the
2529 // Thread-SMR protocol for keeping a ThreadsList alive.
2530 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2531 }
2532 #endif
2533
2534 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2535 // progress or when _suspend_flags is non-zero.
2536 // Current thread needs to self-suspend if there is a suspend request and/or
2537 // block if a safepoint is in progress.
2538 // Async exception ISN'T checked.
2539 // Note only the ThreadInVMfromNative transition can call this function
2540 // directly and when thread state is _thread_in_native_trans
2541 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2542 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2543
2544 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2545
2546 if (thread->is_external_suspend()) {
2547 thread->java_suspend_self_with_safepoint_check();
2548 } else {
2549 SafepointMechanism::block_if_requested(thread);
2550 }
2551
2552 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2553 }
2554
2555 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2556 // progress or when _suspend_flags is non-zero.
2557 // Current thread needs to self-suspend if there is a suspend request and/or
2558 // block if a safepoint is in progress.
2559 // Also check for pending async exception (not including unsafe access error).
2560 // Note only the native==>VM/Java barriers can call this function and when
2561 // thread state is _thread_in_native_trans.
2562 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2563 check_safepoint_and_suspend_for_native_trans(thread);
2564
2565 if (thread->has_async_exception()) {
2566 // We are in _thread_in_native_trans state, don't handle unsafe
2567 // access error since that may block.
2568 thread->check_and_handle_async_exceptions(false);
2569 }
2570 }
2571
2572 // This is a variant of the normal
2573 // check_special_condition_for_native_trans with slightly different
2574 // semantics for use by critical native wrappers. It does all the
2575 // normal checks but also performs the transition back into
2576 // thread_in_Java state. This is required so that critical natives
2577 // can potentially block and perform a GC if they are the last thread
2578 // exiting the GCLocker.
2579 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2580 check_special_condition_for_native_trans(thread);
2581
2582 // Finish the transition
2583 thread->set_thread_state(_thread_in_Java);
2584
2585 if (thread->do_critical_native_unlock()) {
2586 ThreadInVMfromJavaNoAsyncException tiv(thread);
2587 GCLocker::unlock_critical(thread);
2588 thread->clear_critical_native_unlock();
2589 }
2590 }
2591
2592 // We need to guarantee the Threads_lock here, since resumes are not
2593 // allowed during safepoint synchronization
2594 // Can only resume from an external suspension
2595 void JavaThread::java_resume() {
2596 assert_locked_or_safepoint(Threads_lock);
2597
2598 // Sanity check: thread is gone, has started exiting or the thread
2599 // was not externally suspended.
2600 ThreadsListHandle tlh;
2601 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2602 return;
2603 }
2604
2605 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2606
2607 clear_external_suspend();
2608
2609 if (is_ext_suspended()) {
2610 clear_ext_suspended();
2611 SR_lock()->notify_all();
2612 }
2613 }
2614
2615 size_t JavaThread::_stack_red_zone_size = 0;
2616 size_t JavaThread::_stack_yellow_zone_size = 0;
2617 size_t JavaThread::_stack_reserved_zone_size = 0;
2618 size_t JavaThread::_stack_shadow_zone_size = 0;
2619
2620 void JavaThread::create_stack_guard_pages() {
2621 if (!os::uses_stack_guard_pages() ||
2622 _stack_guard_state != stack_guard_unused ||
2623 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2624 log_info(os, thread)("Stack guard page creation for thread "
2625 UINTX_FORMAT " disabled", os::current_thread_id());
2626 return;
2627 }
2628 address low_addr = stack_end();
2629 size_t len = stack_guard_zone_size();
2630
2631 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2632 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2633
2634 int must_commit = os::must_commit_stack_guard_pages();
2635 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2636
2637 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2638 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2639 return;
2640 }
2641
2642 if (os::guard_memory((char *) low_addr, len)) {
2643 _stack_guard_state = stack_guard_enabled;
2644 } else {
2645 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2646 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2647 if (os::uncommit_memory((char *) low_addr, len)) {
2648 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2649 }
2650 return;
2651 }
2652
2653 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2654 PTR_FORMAT "-" PTR_FORMAT ".",
2655 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2656 }
2657
2658 void JavaThread::remove_stack_guard_pages() {
2659 assert(Thread::current() == this, "from different thread");
2660 if (_stack_guard_state == stack_guard_unused) return;
2661 address low_addr = stack_end();
2662 size_t len = stack_guard_zone_size();
2663
2664 if (os::must_commit_stack_guard_pages()) {
2665 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2666 _stack_guard_state = stack_guard_unused;
2667 } else {
2668 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2669 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2670 return;
2671 }
2672 } else {
2673 if (_stack_guard_state == stack_guard_unused) return;
2674 if (os::unguard_memory((char *) low_addr, len)) {
2675 _stack_guard_state = stack_guard_unused;
2676 } else {
2677 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2678 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2679 return;
2680 }
2681 }
2682
2683 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2684 PTR_FORMAT "-" PTR_FORMAT ".",
2685 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2686 }
2687
2688 void JavaThread::enable_stack_reserved_zone() {
2689 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2690
2691 // The base notation is from the stack's point of view, growing downward.
2692 // We need to adjust it to work correctly with guard_memory()
2693 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2694
2695 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2696 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2697
2698 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2699 _stack_guard_state = stack_guard_enabled;
2700 } else {
2701 warning("Attempt to guard stack reserved zone failed.");
2702 }
2703 enable_register_stack_guard();
2704 }
2705
2706 void JavaThread::disable_stack_reserved_zone() {
2707 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2708
2709 // Simply return if called for a thread that does not use guard pages.
2710 if (_stack_guard_state != stack_guard_enabled) return;
2711
2712 // The base notation is from the stack's point of view, growing downward.
2713 // We need to adjust it to work correctly with guard_memory()
2714 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2715
2716 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2717 _stack_guard_state = stack_guard_reserved_disabled;
2718 } else {
2719 warning("Attempt to unguard stack reserved zone failed.");
2720 }
2721 disable_register_stack_guard();
2722 }
2723
2724 void JavaThread::enable_stack_yellow_reserved_zone() {
2725 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2726 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2727
2728 // The base notation is from the stacks point of view, growing downward.
2729 // We need to adjust it to work correctly with guard_memory()
2730 address base = stack_red_zone_base();
2731
2732 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2733 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2734
2735 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2736 _stack_guard_state = stack_guard_enabled;
2737 } else {
2738 warning("Attempt to guard stack yellow zone failed.");
2739 }
2740 enable_register_stack_guard();
2741 }
2742
2743 void JavaThread::disable_stack_yellow_reserved_zone() {
2744 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2745 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2746
2747 // Simply return if called for a thread that does not use guard pages.
2748 if (_stack_guard_state == stack_guard_unused) return;
2749
2750 // The base notation is from the stacks point of view, growing downward.
2751 // We need to adjust it to work correctly with guard_memory()
2752 address base = stack_red_zone_base();
2753
2754 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2755 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2756 } else {
2757 warning("Attempt to unguard stack yellow zone failed.");
2758 }
2759 disable_register_stack_guard();
2760 }
2761
2762 void JavaThread::enable_stack_red_zone() {
2763 // The base notation is from the stacks point of view, growing downward.
2764 // We need to adjust it to work correctly with guard_memory()
2765 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2766 address base = stack_red_zone_base() - stack_red_zone_size();
2767
2768 guarantee(base < stack_base(), "Error calculating stack red zone");
2769 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2770
2771 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2772 warning("Attempt to guard stack red zone failed.");
2773 }
2774 }
2775
2776 void JavaThread::disable_stack_red_zone() {
2777 // The base notation is from the stacks point of view, growing downward.
2778 // We need to adjust it to work correctly with guard_memory()
2779 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2780 address base = stack_red_zone_base() - stack_red_zone_size();
2781 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2782 warning("Attempt to unguard stack red zone failed.");
2783 }
2784 }
2785
2786 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2787 // ignore is there is no stack
2788 if (!has_last_Java_frame()) return;
2789 // traverse the stack frames. Starts from top frame.
2790 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2791 frame* fr = fst.current();
2792 f(fr, fst.register_map());
2793 }
2794 }
2795
2796
2797 #ifndef PRODUCT
2798 // Deoptimization
2799 // Function for testing deoptimization
2800 void JavaThread::deoptimize() {
2801 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2802 StackFrameStream fst(this, UseBiasedLocking);
2803 bool deopt = false; // Dump stack only if a deopt actually happens.
2804 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2805 // Iterate over all frames in the thread and deoptimize
2806 for (; !fst.is_done(); fst.next()) {
2807 if (fst.current()->can_be_deoptimized()) {
2808
2809 if (only_at) {
2810 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2811 // consists of comma or carriage return separated numbers so
2812 // search for the current bci in that string.
2813 address pc = fst.current()->pc();
2814 nmethod* nm = (nmethod*) fst.current()->cb();
2815 ScopeDesc* sd = nm->scope_desc_at(pc);
2816 char buffer[8];
2817 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2818 size_t len = strlen(buffer);
2819 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2820 while (found != NULL) {
2821 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2822 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2823 // Check that the bci found is bracketed by terminators.
2824 break;
2825 }
2826 found = strstr(found + 1, buffer);
2827 }
2828 if (!found) {
2829 continue;
2830 }
2831 }
2832
2833 if (DebugDeoptimization && !deopt) {
2834 deopt = true; // One-time only print before deopt
2835 tty->print_cr("[BEFORE Deoptimization]");
2836 trace_frames();
2837 trace_stack();
2838 }
2839 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2840 }
2841 }
2842
2843 if (DebugDeoptimization && deopt) {
2844 tty->print_cr("[AFTER Deoptimization]");
2845 trace_frames();
2846 }
2847 }
2848
2849
2850 // Make zombies
2851 void JavaThread::make_zombies() {
2852 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2853 if (fst.current()->can_be_deoptimized()) {
2854 // it is a Java nmethod
2855 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2856 nm->make_not_entrant();
2857 }
2858 }
2859 }
2860 #endif // PRODUCT
2861
2862
2863 void JavaThread::deoptimized_wrt_marked_nmethods() {
2864 if (!has_last_Java_frame()) return;
2865 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2866 StackFrameStream fst(this, UseBiasedLocking);
2867 for (; !fst.is_done(); fst.next()) {
2868 if (fst.current()->should_be_deoptimized()) {
2869 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2870 }
2871 }
2872 }
2873
2874
2875 // If the caller is a NamedThread, then remember, in the current scope,
2876 // the given JavaThread in its _processed_thread field.
2877 class RememberProcessedThread: public StackObj {
2878 NamedThread* _cur_thr;
2879 public:
2880 RememberProcessedThread(JavaThread* jthr) {
2881 Thread* thread = Thread::current();
2882 if (thread->is_Named_thread()) {
2883 _cur_thr = (NamedThread *)thread;
2884 _cur_thr->set_processed_thread(jthr);
2885 } else {
2886 _cur_thr = NULL;
2887 }
2888 }
2889
2890 ~RememberProcessedThread() {
2891 if (_cur_thr) {
2892 _cur_thr->set_processed_thread(NULL);
2893 }
2894 }
2895 };
2896
2897 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2898 // Verify that the deferred card marks have been flushed.
2899 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2900
2901 // Traverse the GCHandles
2902 Thread::oops_do(f, cf);
2903
2904 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2905 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2906
2907 if (has_last_Java_frame()) {
2908 // Record JavaThread to GC thread
2909 RememberProcessedThread rpt(this);
2910
2911 // traverse the registered growable array
2912 if (_array_for_gc != NULL) {
2913 for (int index = 0; index < _array_for_gc->length(); index++) {
2914 f->do_oop(_array_for_gc->adr_at(index));
2915 }
2916 }
2917
2918 // Traverse the monitor chunks
2919 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2920 chunk->oops_do(f);
2921 }
2922
2923 // Traverse the execution stack
2924 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2925 fst.current()->oops_do(f, cf, fst.register_map());
2926 }
2927 }
2928
2929 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2930 // If we have deferred set_locals there might be oops waiting to be
2931 // written
2932 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2933 if (list != NULL) {
2934 for (int i = 0; i < list->length(); i++) {
2935 list->at(i)->oops_do(f);
2936 }
2937 }
2938
2939 // Traverse instance variables at the end since the GC may be moving things
2940 // around using this function
2941 f->do_oop((oop*) &_threadObj);
2942 f->do_oop((oop*) &_vm_result);
2943 f->do_oop((oop*) &_exception_oop);
2944 f->do_oop((oop*) &_pending_async_exception);
2945
2946 if (jvmti_thread_state() != NULL) {
2947 jvmti_thread_state()->oops_do(f);
2948 }
2949 }
2950
2951 #ifdef ASSERT
2952 void JavaThread::verify_states_for_handshake() {
2953 // This checks that the thread has a correct frame state during a handshake.
2954 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2955 (has_last_Java_frame() && java_call_counter() > 0),
2956 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2957 has_last_Java_frame(), java_call_counter());
2958 }
2959 #endif
2960
2961 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2962 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2963 (has_last_Java_frame() && java_call_counter() > 0),
2964 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2965 has_last_Java_frame(), java_call_counter());
2966
2967 if (has_last_Java_frame()) {
2968 // Traverse the execution stack
2969 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2970 fst.current()->nmethods_do(cf);
2971 }
2972 }
2973 }
2974
2975 void JavaThread::metadata_do(MetadataClosure* f) {
2976 if (has_last_Java_frame()) {
2977 // Traverse the execution stack to call f() on the methods in the stack
2978 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2979 fst.current()->metadata_do(f);
2980 }
2981 } else if (is_Compiler_thread()) {
2982 // need to walk ciMetadata in current compile tasks to keep alive.
2983 CompilerThread* ct = (CompilerThread*)this;
2984 if (ct->env() != NULL) {
2985 ct->env()->metadata_do(f);
2986 }
2987 CompileTask* task = ct->task();
2988 if (task != NULL) {
2989 task->metadata_do(f);
2990 }
2991 }
2992 }
2993
2994 // Printing
2995 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2996 switch (_thread_state) {
2997 case _thread_uninitialized: return "_thread_uninitialized";
2998 case _thread_new: return "_thread_new";
2999 case _thread_new_trans: return "_thread_new_trans";
3000 case _thread_in_native: return "_thread_in_native";
3001 case _thread_in_native_trans: return "_thread_in_native_trans";
3002 case _thread_in_vm: return "_thread_in_vm";
3003 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3004 case _thread_in_Java: return "_thread_in_Java";
3005 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3006 case _thread_blocked: return "_thread_blocked";
3007 case _thread_blocked_trans: return "_thread_blocked_trans";
3008 default: return "unknown thread state";
3009 }
3010 }
3011
3012 #ifndef PRODUCT
3013 void JavaThread::print_thread_state_on(outputStream *st) const {
3014 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3015 };
3016 #endif // PRODUCT
3017
3018 // Called by Threads::print() for VM_PrintThreads operation
3019 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3020 st->print_raw("\"");
3021 st->print_raw(get_thread_name());
3022 st->print_raw("\" ");
3023 oop thread_oop = threadObj();
3024 if (thread_oop != NULL) {
3025 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3026 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3027 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3028 }
3029 Thread::print_on(st, print_extended_info);
3030 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3031 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3032 if (thread_oop != NULL) {
3033 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3034 }
3035 #ifndef PRODUCT
3036 _safepoint_state->print_on(st);
3037 #endif // PRODUCT
3038 if (is_Compiler_thread()) {
3039 CompileTask *task = ((CompilerThread*)this)->task();
3040 if (task != NULL) {
3041 st->print(" Compiling: ");
3042 task->print(st, NULL, true, false);
3043 } else {
3044 st->print(" No compile task");
3045 }
3046 st->cr();
3047 }
3048 }
3049
3050 void JavaThread::print() const { print_on(tty); }
3051
3052 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3053 st->print("%s", get_thread_name_string(buf, buflen));
3054 }
3055
3056 // Called by fatal error handler. The difference between this and
3057 // JavaThread::print() is that we can't grab lock or allocate memory.
3058 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3059 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3060 oop thread_obj = threadObj();
3061 if (thread_obj != NULL) {
3062 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3063 }
3064 st->print(" [");
3065 st->print("%s", _get_thread_state_name(_thread_state));
3066 if (osthread()) {
3067 st->print(", id=%d", osthread()->thread_id());
3068 }
3069 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3070 p2i(stack_end()), p2i(stack_base()));
3071 st->print("]");
3072
3073 ThreadsSMRSupport::print_info_on(this, st);
3074 return;
3075 }
3076
3077 // Verification
3078
3079 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3080
3081 void JavaThread::verify() {
3082 // Verify oops in the thread.
3083 oops_do(&VerifyOopClosure::verify_oop, NULL);
3084
3085 // Verify the stack frames.
3086 frames_do(frame_verify);
3087 }
3088
3089 // CR 6300358 (sub-CR 2137150)
3090 // Most callers of this method assume that it can't return NULL but a
3091 // thread may not have a name whilst it is in the process of attaching to
3092 // the VM - see CR 6412693, and there are places where a JavaThread can be
3093 // seen prior to having it's threadObj set (eg JNI attaching threads and
3094 // if vm exit occurs during initialization). These cases can all be accounted
3095 // for such that this method never returns NULL.
3096 const char* JavaThread::get_thread_name() const {
3097 #ifdef ASSERT
3098 // early safepoints can hit while current thread does not yet have TLS
3099 if (!SafepointSynchronize::is_at_safepoint()) {
3100 Thread *cur = Thread::current();
3101 if (!(cur->is_Java_thread() && cur == this)) {
3102 // Current JavaThreads are allowed to get their own name without
3103 // the Threads_lock.
3104 assert_locked_or_safepoint(Threads_lock);
3105 }
3106 }
3107 #endif // ASSERT
3108 return get_thread_name_string();
3109 }
3110
3111 // Returns a non-NULL representation of this thread's name, or a suitable
3112 // descriptive string if there is no set name
3113 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3114 const char* name_str;
3115 oop thread_obj = threadObj();
3116 if (thread_obj != NULL) {
3117 oop name = java_lang_Thread::name(thread_obj);
3118 if (name != NULL) {
3119 if (buf == NULL) {
3120 name_str = java_lang_String::as_utf8_string(name);
3121 } else {
3122 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3123 }
3124 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3125 name_str = "<no-name - thread is attaching>";
3126 } else {
3127 name_str = Thread::name();
3128 }
3129 } else {
3130 name_str = Thread::name();
3131 }
3132 assert(name_str != NULL, "unexpected NULL thread name");
3133 return name_str;
3134 }
3135
3136 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3137
3138 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3139 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
3140 // Link Java Thread object <-> C++ Thread
3141
3142 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3143 // and put it into a new Handle. The Handle "thread_oop" can then
3144 // be used to pass the C++ thread object to other methods.
3145
3146 // Set the Java level thread object (jthread) field of the
3147 // new thread (a JavaThread *) to C++ thread object using the
3148 // "thread_oop" handle.
3149
3150 // Set the thread field (a JavaThread *) of the
3151 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3152
3153 Handle thread_oop(Thread::current(),
3154 JNIHandles::resolve_non_null(jni_thread));
3155 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3156 "must be initialized");
3157 set_threadObj(thread_oop());
3158 java_lang_Thread::set_thread(thread_oop(), this);
3159
3160 if (prio == NoPriority) {
3161 prio = java_lang_Thread::priority(thread_oop());
3162 assert(prio != NoPriority, "A valid priority should be present");
3163 }
3164
3165 // Push the Java priority down to the native thread; needs Threads_lock
3166 Thread::set_priority(this, prio);
3167
3168 // Add the new thread to the Threads list and set it in motion.
3169 // We must have threads lock in order to call Threads::add.
3170 // It is crucial that we do not block before the thread is
3171 // added to the Threads list for if a GC happens, then the java_thread oop
3172 // will not be visited by GC.
3173 Threads::add(this);
3174 }
3175
3176 oop JavaThread::current_park_blocker() {
3177 // Support for JSR-166 locks
3178 oop thread_oop = threadObj();
3179 if (thread_oop != NULL) {
3180 return java_lang_Thread::park_blocker(thread_oop);
3181 }
3182 return NULL;
3183 }
3184
3185
3186 void JavaThread::print_stack_on(outputStream* st) {
3187 if (!has_last_Java_frame()) return;
3188 ResourceMark rm;
3189 HandleMark hm;
3190
3191 RegisterMap reg_map(this);
3192 vframe* start_vf = last_java_vframe(®_map);
3193 int count = 0;
3194 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3195 if (f->is_java_frame()) {
3196 javaVFrame* jvf = javaVFrame::cast(f);
3197 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3198
3199 // Print out lock information
3200 if (JavaMonitorsInStackTrace) {
3201 jvf->print_lock_info_on(st, count);
3202 }
3203 } else {
3204 // Ignore non-Java frames
3205 }
3206
3207 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3208 count++;
3209 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3210 }
3211 }
3212
3213
3214 // JVMTI PopFrame support
3215 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3216 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3217 if (in_bytes(size_in_bytes) != 0) {
3218 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3219 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3220 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3221 }
3222 }
3223
3224 void* JavaThread::popframe_preserved_args() {
3225 return _popframe_preserved_args;
3226 }
3227
3228 ByteSize JavaThread::popframe_preserved_args_size() {
3229 return in_ByteSize(_popframe_preserved_args_size);
3230 }
3231
3232 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3233 int sz = in_bytes(popframe_preserved_args_size());
3234 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3235 return in_WordSize(sz / wordSize);
3236 }
3237
3238 void JavaThread::popframe_free_preserved_args() {
3239 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3240 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3241 _popframe_preserved_args = NULL;
3242 _popframe_preserved_args_size = 0;
3243 }
3244
3245 #ifndef PRODUCT
3246
3247 void JavaThread::trace_frames() {
3248 tty->print_cr("[Describe stack]");
3249 int frame_no = 1;
3250 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3251 tty->print(" %d. ", frame_no++);
3252 fst.current()->print_value_on(tty, this);
3253 tty->cr();
3254 }
3255 }
3256
3257 class PrintAndVerifyOopClosure: public OopClosure {
3258 protected:
3259 template <class T> inline void do_oop_work(T* p) {
3260 oop obj = RawAccess<>::oop_load(p);
3261 if (obj == NULL) return;
3262 tty->print(INTPTR_FORMAT ": ", p2i(p));
3263 if (oopDesc::is_oop_or_null(obj)) {
3264 if (obj->is_objArray()) {
3265 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3266 } else {
3267 obj->print();
3268 }
3269 } else {
3270 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3271 }
3272 tty->cr();
3273 }
3274 public:
3275 virtual void do_oop(oop* p) { do_oop_work(p); }
3276 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3277 };
3278
3279 #ifdef ASSERT
3280 // Print or validate the layout of stack frames
3281 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3282 ResourceMark rm;
3283 PRESERVE_EXCEPTION_MARK;
3284 FrameValues values;
3285 int frame_no = 0;
3286 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3287 fst.current()->describe(values, ++frame_no);
3288 if (depth == frame_no) break;
3289 }
3290 if (validate_only) {
3291 values.validate();
3292 } else {
3293 tty->print_cr("[Describe stack layout]");
3294 values.print(this);
3295 }
3296 }
3297 #endif
3298
3299 void JavaThread::trace_stack_from(vframe* start_vf) {
3300 ResourceMark rm;
3301 int vframe_no = 1;
3302 for (vframe* f = start_vf; f; f = f->sender()) {
3303 if (f->is_java_frame()) {
3304 javaVFrame::cast(f)->print_activation(vframe_no++);
3305 } else {
3306 f->print();
3307 }
3308 if (vframe_no > StackPrintLimit) {
3309 tty->print_cr("...<more frames>...");
3310 return;
3311 }
3312 }
3313 }
3314
3315
3316 void JavaThread::trace_stack() {
3317 if (!has_last_Java_frame()) return;
3318 ResourceMark rm;
3319 HandleMark hm;
3320 RegisterMap reg_map(this);
3321 trace_stack_from(last_java_vframe(®_map));
3322 }
3323
3324
3325 #endif // PRODUCT
3326
3327
3328 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3329 assert(reg_map != NULL, "a map must be given");
3330 frame f = last_frame();
3331 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3332 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3333 }
3334 return NULL;
3335 }
3336
3337
3338 Klass* JavaThread::security_get_caller_class(int depth) {
3339 vframeStream vfst(this);
3340 vfst.security_get_caller_frame(depth);
3341 if (!vfst.at_end()) {
3342 return vfst.method()->method_holder();
3343 }
3344 return NULL;
3345 }
3346
3347 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3348 assert(thread->is_Compiler_thread(), "must be compiler thread");
3349 CompileBroker::compiler_thread_loop();
3350 }
3351
3352 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3353 NMethodSweeper::sweeper_loop();
3354 }
3355
3356 // Create a CompilerThread
3357 CompilerThread::CompilerThread(CompileQueue* queue,
3358 CompilerCounters* counters)
3359 : JavaThread(&compiler_thread_entry) {
3360 _env = NULL;
3361 _log = NULL;
3362 _task = NULL;
3363 _queue = queue;
3364 _counters = counters;
3365 _buffer_blob = NULL;
3366 _compiler = NULL;
3367
3368 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3369 resource_area()->bias_to(mtCompiler);
3370
3371 #ifndef PRODUCT
3372 _ideal_graph_printer = NULL;
3373 #endif
3374 }
3375
3376 CompilerThread::~CompilerThread() {
3377 // Delete objects which were allocated on heap.
3378 delete _counters;
3379 }
3380
3381 bool CompilerThread::can_call_java() const {
3382 return _compiler != NULL && _compiler->is_jvmci();
3383 }
3384
3385 // Create sweeper thread
3386 CodeCacheSweeperThread::CodeCacheSweeperThread()
3387 : JavaThread(&sweeper_thread_entry) {
3388 _scanned_compiled_method = NULL;
3389 }
3390
3391 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3392 JavaThread::oops_do(f, cf);
3393 if (_scanned_compiled_method != NULL && cf != NULL) {
3394 // Safepoints can occur when the sweeper is scanning an nmethod so
3395 // process it here to make sure it isn't unloaded in the middle of
3396 // a scan.
3397 cf->do_code_blob(_scanned_compiled_method);
3398 }
3399 }
3400
3401 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3402 JavaThread::nmethods_do(cf);
3403 if (_scanned_compiled_method != NULL && cf != NULL) {
3404 // Safepoints can occur when the sweeper is scanning an nmethod so
3405 // process it here to make sure it isn't unloaded in the middle of
3406 // a scan.
3407 cf->do_code_blob(_scanned_compiled_method);
3408 }
3409 }
3410
3411
3412 // ======= Threads ========
3413
3414 // The Threads class links together all active threads, and provides
3415 // operations over all threads. It is protected by the Threads_lock,
3416 // which is also used in other global contexts like safepointing.
3417 // ThreadsListHandles are used to safely perform operations on one
3418 // or more threads without the risk of the thread exiting during the
3419 // operation.
3420 //
3421 // Note: The Threads_lock is currently more widely used than we
3422 // would like. We are actively migrating Threads_lock uses to other
3423 // mechanisms in order to reduce Threads_lock contention.
3424
3425 int Threads::_number_of_threads = 0;
3426 int Threads::_number_of_non_daemon_threads = 0;
3427 int Threads::_return_code = 0;
3428 uintx Threads::_thread_claim_token = 1; // Never zero.
3429 size_t JavaThread::_stack_size_at_create = 0;
3430
3431 #ifdef ASSERT
3432 bool Threads::_vm_complete = false;
3433 #endif
3434
3435 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3436 Prefetch::read((void*)addr, prefetch_interval);
3437 return *addr;
3438 }
3439
3440 // Possibly the ugliest for loop the world has seen. C++ does not allow
3441 // multiple types in the declaration section of the for loop. In this case
3442 // we are only dealing with pointers and hence can cast them. It looks ugly
3443 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3444 #define DO_JAVA_THREADS(LIST, X) \
3445 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3446 *MACRO_list = (JavaThread*)(LIST), \
3447 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3448 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3449 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3450 MACRO_current_p != MACRO_end; \
3451 MACRO_current_p++, \
3452 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3453
3454 // All JavaThreads
3455 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3456
3457 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3458 void Threads::non_java_threads_do(ThreadClosure* tc) {
3459 NoSafepointVerifier nsv;
3460 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3461 tc->do_thread(njti.current());
3462 }
3463 }
3464
3465 // All JavaThreads
3466 void Threads::java_threads_do(ThreadClosure* tc) {
3467 assert_locked_or_safepoint(Threads_lock);
3468 // ALL_JAVA_THREADS iterates through all JavaThreads.
3469 ALL_JAVA_THREADS(p) {
3470 tc->do_thread(p);
3471 }
3472 }
3473
3474 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3475 assert_locked_or_safepoint(Threads_lock);
3476 java_threads_do(tc);
3477 tc->do_thread(VMThread::vm_thread());
3478 }
3479
3480 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3481 void Threads::threads_do(ThreadClosure* tc) {
3482 assert_locked_or_safepoint(Threads_lock);
3483 java_threads_do(tc);
3484 non_java_threads_do(tc);
3485 }
3486
3487 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3488 uintx claim_token = Threads::thread_claim_token();
3489 ALL_JAVA_THREADS(p) {
3490 if (p->claim_threads_do(is_par, claim_token)) {
3491 tc->do_thread(p);
3492 }
3493 }
3494 VMThread* vmt = VMThread::vm_thread();
3495 if (vmt->claim_threads_do(is_par, claim_token)) {
3496 tc->do_thread(vmt);
3497 }
3498 }
3499
3500 // The system initialization in the library has three phases.
3501 //
3502 // Phase 1: java.lang.System class initialization
3503 // java.lang.System is a primordial class loaded and initialized
3504 // by the VM early during startup. java.lang.System.<clinit>
3505 // only does registerNatives and keeps the rest of the class
3506 // initialization work later until thread initialization completes.
3507 //
3508 // System.initPhase1 initializes the system properties, the static
3509 // fields in, out, and err. Set up java signal handlers, OS-specific
3510 // system settings, and thread group of the main thread.
3511 static void call_initPhase1(TRAPS) {
3512 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3513 JavaValue result(T_VOID);
3514 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3515 vmSymbols::void_method_signature(), CHECK);
3516 }
3517
3518 // Phase 2. Module system initialization
3519 // This will initialize the module system. Only java.base classes
3520 // can be loaded until phase 2 completes.
3521 //
3522 // Call System.initPhase2 after the compiler initialization and jsr292
3523 // classes get initialized because module initialization runs a lot of java
3524 // code, that for performance reasons, should be compiled. Also, this will
3525 // enable the startup code to use lambda and other language features in this
3526 // phase and onward.
3527 //
3528 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3529 static void call_initPhase2(TRAPS) {
3530 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3531
3532 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3533
3534 JavaValue result(T_INT);
3535 JavaCallArguments args;
3536 args.push_int(DisplayVMOutputToStderr);
3537 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3538 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3539 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3540 if (result.get_jint() != JNI_OK) {
3541 vm_exit_during_initialization(); // no message or exception
3542 }
3543
3544 universe_post_module_init();
3545 }
3546
3547 // Phase 3. final setup - set security manager, system class loader and TCCL
3548 //
3549 // This will instantiate and set the security manager, set the system class
3550 // loader as well as the thread context class loader. The security manager
3551 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3552 // other modules or the application's classpath.
3553 static void call_initPhase3(TRAPS) {
3554 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3555 JavaValue result(T_VOID);
3556 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3557 vmSymbols::void_method_signature(), CHECK);
3558 }
3559
3560 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3561 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3562
3563 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3564 create_vm_init_libraries();
3565 }
3566
3567 initialize_class(vmSymbols::java_lang_String(), CHECK);
3568
3569 // Inject CompactStrings value after the static initializers for String ran.
3570 java_lang_String::set_compact_strings(CompactStrings);
3571
3572 // Initialize java_lang.System (needed before creating the thread)
3573 initialize_class(vmSymbols::java_lang_System(), CHECK);
3574 // The VM creates & returns objects of this class. Make sure it's initialized.
3575 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3576 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3577 Handle thread_group = create_initial_thread_group(CHECK);
3578 Universe::set_main_thread_group(thread_group());
3579 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3580 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3581 main_thread->set_threadObj(thread_object);
3582
3583 // Set thread status to running since main thread has
3584 // been started and running.
3585 java_lang_Thread::set_thread_status(thread_object,
3586 java_lang_Thread::RUNNABLE);
3587
3588 // The VM creates objects of this class.
3589 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3590
3591 #ifdef ASSERT
3592 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3593 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3594 #endif
3595
3596 // initialize the hardware-specific constants needed by Unsafe
3597 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3598 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3599
3600 // The VM preresolves methods to these classes. Make sure that they get initialized
3601 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3602 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3603
3604 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3605 call_initPhase1(CHECK);
3606
3607 // get the Java runtime name after java.lang.System is initialized
3608 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3609 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3610
3611 // an instance of OutOfMemory exception has been allocated earlier
3612 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3613 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3614 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3615 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3616 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3617 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3618 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3619 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3620
3621 // Eager box cache initialization only if AOT is on and any library is loaded.
3622 AOTLoader::initialize_box_caches(CHECK);
3623 }
3624
3625 void Threads::initialize_jsr292_core_classes(TRAPS) {
3626 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3627
3628 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3629 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3630 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3631 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3632 }
3633
3634 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3635 extern void JDK_Version_init();
3636
3637 // Preinitialize version info.
3638 VM_Version::early_initialize();
3639
3640 // Check version
3641 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3642
3643 // Initialize library-based TLS
3644 ThreadLocalStorage::init();
3645
3646 // Initialize the output stream module
3647 ostream_init();
3648
3649 // Process java launcher properties.
3650 Arguments::process_sun_java_launcher_properties(args);
3651
3652 // Initialize the os module
3653 os::init();
3654
3655 // Record VM creation timing statistics
3656 TraceVmCreationTime create_vm_timer;
3657 create_vm_timer.start();
3658
3659 // Initialize system properties.
3660 Arguments::init_system_properties();
3661
3662 // So that JDK version can be used as a discriminator when parsing arguments
3663 JDK_Version_init();
3664
3665 // Update/Initialize System properties after JDK version number is known
3666 Arguments::init_version_specific_system_properties();
3667
3668 // Make sure to initialize log configuration *before* parsing arguments
3669 LogConfiguration::initialize(create_vm_timer.begin_time());
3670
3671 // Parse arguments
3672 // Note: this internally calls os::init_container_support()
3673 jint parse_result = Arguments::parse(args);
3674 if (parse_result != JNI_OK) return parse_result;
3675
3676 os::init_before_ergo();
3677
3678 jint ergo_result = Arguments::apply_ergo();
3679 if (ergo_result != JNI_OK) return ergo_result;
3680
3681 // Final check of all ranges after ergonomics which may change values.
3682 if (!JVMFlagRangeList::check_ranges()) {
3683 return JNI_EINVAL;
3684 }
3685
3686 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3687 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3688 if (!constraint_result) {
3689 return JNI_EINVAL;
3690 }
3691
3692 JVMFlagWriteableList::mark_startup();
3693
3694 if (PauseAtStartup) {
3695 os::pause();
3696 }
3697
3698 HOTSPOT_VM_INIT_BEGIN();
3699
3700 // Timing (must come after argument parsing)
3701 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3702
3703 // Initialize the os module after parsing the args
3704 jint os_init_2_result = os::init_2();
3705 if (os_init_2_result != JNI_OK) return os_init_2_result;
3706
3707 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3708 // Initialize assert poison page mechanism.
3709 if (ShowRegistersOnAssert) {
3710 initialize_assert_poison();
3711 }
3712 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3713
3714 SafepointMechanism::initialize();
3715
3716 jint adjust_after_os_result = Arguments::adjust_after_os();
3717 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3718
3719 // Initialize output stream logging
3720 ostream_init_log();
3721
3722 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3723 // Must be before create_vm_init_agents()
3724 if (Arguments::init_libraries_at_startup()) {
3725 convert_vm_init_libraries_to_agents();
3726 }
3727
3728 // Launch -agentlib/-agentpath and converted -Xrun agents
3729 if (Arguments::init_agents_at_startup()) {
3730 create_vm_init_agents();
3731 }
3732
3733 // Initialize Threads state
3734 _number_of_threads = 0;
3735 _number_of_non_daemon_threads = 0;
3736
3737 // Initialize global data structures and create system classes in heap
3738 vm_init_globals();
3739
3740 #if INCLUDE_JVMCI
3741 if (JVMCICounterSize > 0) {
3742 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3743 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3744 } else {
3745 JavaThread::_jvmci_old_thread_counters = NULL;
3746 }
3747 #endif // INCLUDE_JVMCI
3748
3749 // Attach the main thread to this os thread
3750 JavaThread* main_thread = new JavaThread();
3751 main_thread->set_thread_state(_thread_in_vm);
3752 main_thread->initialize_thread_current();
3753 // must do this before set_active_handles
3754 main_thread->record_stack_base_and_size();
3755 main_thread->register_thread_stack_with_NMT();
3756 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3757
3758 if (!main_thread->set_as_starting_thread()) {
3759 vm_shutdown_during_initialization(
3760 "Failed necessary internal allocation. Out of swap space");
3761 main_thread->smr_delete();
3762 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3763 return JNI_ENOMEM;
3764 }
3765
3766 // Enable guard page *after* os::create_main_thread(), otherwise it would
3767 // crash Linux VM, see notes in os_linux.cpp.
3768 main_thread->create_stack_guard_pages();
3769
3770 // Initialize Java-Level synchronization subsystem
3771 ObjectMonitor::Initialize();
3772
3773 // Initialize global modules
3774 jint status = init_globals();
3775 if (status != JNI_OK) {
3776 main_thread->smr_delete();
3777 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3778 return status;
3779 }
3780
3781 JFR_ONLY(Jfr::on_vm_init();)
3782
3783 // Should be done after the heap is fully created
3784 main_thread->cache_global_variables();
3785
3786 HandleMark hm;
3787
3788 { MutexLocker mu(Threads_lock);
3789 Threads::add(main_thread);
3790 }
3791
3792 // Any JVMTI raw monitors entered in onload will transition into
3793 // real raw monitor. VM is setup enough here for raw monitor enter.
3794 JvmtiExport::transition_pending_onload_raw_monitors();
3795
3796 // Create the VMThread
3797 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3798
3799 VMThread::create();
3800 Thread* vmthread = VMThread::vm_thread();
3801
3802 if (!os::create_thread(vmthread, os::vm_thread)) {
3803 vm_exit_during_initialization("Cannot create VM thread. "
3804 "Out of system resources.");
3805 }
3806
3807 // Wait for the VM thread to become ready, and VMThread::run to initialize
3808 // Monitors can have spurious returns, must always check another state flag
3809 {
3810 MonitorLocker ml(Notify_lock);
3811 os::start_thread(vmthread);
3812 while (vmthread->active_handles() == NULL) {
3813 ml.wait();
3814 }
3815 }
3816 }
3817
3818 assert(Universe::is_fully_initialized(), "not initialized");
3819 if (VerifyDuringStartup) {
3820 // Make sure we're starting with a clean slate.
3821 VM_Verify verify_op;
3822 VMThread::execute(&verify_op);
3823 }
3824
3825 // We need this to update the java.vm.info property in case any flags used
3826 // to initially define it have been changed. This is needed for both CDS and
3827 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3828 // is initially computed. See Abstract_VM_Version::vm_info_string().
3829 // This update must happen before we initialize the java classes, but
3830 // after any initialization logic that might modify the flags.
3831 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3832
3833 Thread* THREAD = Thread::current();
3834
3835 // Always call even when there are not JVMTI environments yet, since environments
3836 // may be attached late and JVMTI must track phases of VM execution
3837 JvmtiExport::enter_early_start_phase();
3838
3839 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3840 JvmtiExport::post_early_vm_start();
3841
3842 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3843
3844 quicken_jni_functions();
3845
3846 // No more stub generation allowed after that point.
3847 StubCodeDesc::freeze();
3848
3849 // Set flag that basic initialization has completed. Used by exceptions and various
3850 // debug stuff, that does not work until all basic classes have been initialized.
3851 set_init_completed();
3852
3853 LogConfiguration::post_initialize();
3854 Metaspace::post_initialize();
3855
3856 HOTSPOT_VM_INIT_END();
3857
3858 // record VM initialization completion time
3859 #if INCLUDE_MANAGEMENT
3860 Management::record_vm_init_completed();
3861 #endif // INCLUDE_MANAGEMENT
3862
3863 // Signal Dispatcher needs to be started before VMInit event is posted
3864 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3865
3866 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3867 if (!DisableAttachMechanism) {
3868 AttachListener::vm_start();
3869 if (StartAttachListener || AttachListener::init_at_startup()) {
3870 AttachListener::init();
3871 }
3872 }
3873
3874 // Launch -Xrun agents
3875 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3876 // back-end can launch with -Xdebug -Xrunjdwp.
3877 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3878 create_vm_init_libraries();
3879 }
3880
3881 if (CleanChunkPoolAsync) {
3882 Chunk::start_chunk_pool_cleaner_task();
3883 }
3884
3885
3886 // initialize compiler(s)
3887 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3888 #if INCLUDE_JVMCI
3889 bool force_JVMCI_intialization = false;
3890 if (EnableJVMCI) {
3891 // Initialize JVMCI eagerly when it is explicitly requested.
3892 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3893 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3894
3895 if (!force_JVMCI_intialization) {
3896 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3897 // compilations via JVMCI will not actually block until JVMCI is initialized.
3898 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3899 }
3900 }
3901 #endif
3902 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3903 // Postpone completion of compiler initialization to after JVMCI
3904 // is initialized to avoid timeouts of blocking compilations.
3905 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3906 CompileBroker::compilation_init_phase2();
3907 }
3908 #endif
3909
3910 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3911 // It is done after compilers are initialized, because otherwise compilations of
3912 // signature polymorphic MH intrinsics can be missed
3913 // (see SystemDictionary::find_method_handle_intrinsic).
3914 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3915
3916 // This will initialize the module system. Only java.base classes can be
3917 // loaded until phase 2 completes
3918 call_initPhase2(CHECK_JNI_ERR);
3919
3920 // Always call even when there are not JVMTI environments yet, since environments
3921 // may be attached late and JVMTI must track phases of VM execution
3922 JvmtiExport::enter_start_phase();
3923
3924 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3925 JvmtiExport::post_vm_start();
3926
3927 // Final system initialization including security manager and system class loader
3928 call_initPhase3(CHECK_JNI_ERR);
3929
3930 // cache the system and platform class loaders
3931 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3932
3933 #if INCLUDE_CDS
3934 // capture the module path info from the ModuleEntryTable
3935 ClassLoader::initialize_module_path(THREAD);
3936 #endif
3937
3938 #if INCLUDE_JVMCI
3939 if (force_JVMCI_intialization) {
3940 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3941 CompileBroker::compilation_init_phase2();
3942 }
3943 #endif
3944
3945 // Always call even when there are not JVMTI environments yet, since environments
3946 // may be attached late and JVMTI must track phases of VM execution
3947 JvmtiExport::enter_live_phase();
3948
3949 // Make perfmemory accessible
3950 PerfMemory::set_accessible(true);
3951
3952 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3953 JvmtiExport::post_vm_initialized();
3954
3955 JFR_ONLY(Jfr::on_vm_start();)
3956
3957 #if INCLUDE_MANAGEMENT
3958 Management::initialize(THREAD);
3959
3960 if (HAS_PENDING_EXCEPTION) {
3961 // management agent fails to start possibly due to
3962 // configuration problem and is responsible for printing
3963 // stack trace if appropriate. Simply exit VM.
3964 vm_exit(1);
3965 }
3966 #endif // INCLUDE_MANAGEMENT
3967
3968 if (MemProfiling) MemProfiler::engage();
3969 StatSampler::engage();
3970 if (CheckJNICalls) JniPeriodicChecker::engage();
3971
3972 BiasedLocking::init();
3973
3974 #if INCLUDE_RTM_OPT
3975 RTMLockingCounters::init();
3976 #endif
3977
3978 call_postVMInitHook(THREAD);
3979 // The Java side of PostVMInitHook.run must deal with all
3980 // exceptions and provide means of diagnosis.
3981 if (HAS_PENDING_EXCEPTION) {
3982 CLEAR_PENDING_EXCEPTION;
3983 }
3984
3985 {
3986 MutexLocker ml(PeriodicTask_lock);
3987 // Make sure the WatcherThread can be started by WatcherThread::start()
3988 // or by dynamic enrollment.
3989 WatcherThread::make_startable();
3990 // Start up the WatcherThread if there are any periodic tasks
3991 // NOTE: All PeriodicTasks should be registered by now. If they
3992 // aren't, late joiners might appear to start slowly (we might
3993 // take a while to process their first tick).
3994 if (PeriodicTask::num_tasks() > 0) {
3995 WatcherThread::start();
3996 }
3997 }
3998
3999 create_vm_timer.end();
4000 #ifdef ASSERT
4001 _vm_complete = true;
4002 #endif
4003
4004 if (DumpSharedSpaces) {
4005 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4006 ShouldNotReachHere();
4007 }
4008
4009 return JNI_OK;
4010 }
4011
4012 // type for the Agent_OnLoad and JVM_OnLoad entry points
4013 extern "C" {
4014 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4015 }
4016 // Find a command line agent library and return its entry point for
4017 // -agentlib: -agentpath: -Xrun
4018 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4019 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4020 const char *on_load_symbols[],
4021 size_t num_symbol_entries) {
4022 OnLoadEntry_t on_load_entry = NULL;
4023 void *library = NULL;
4024
4025 if (!agent->valid()) {
4026 char buffer[JVM_MAXPATHLEN];
4027 char ebuf[1024] = "";
4028 const char *name = agent->name();
4029 const char *msg = "Could not find agent library ";
4030
4031 // First check to see if agent is statically linked into executable
4032 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4033 library = agent->os_lib();
4034 } else if (agent->is_absolute_path()) {
4035 library = os::dll_load(name, ebuf, sizeof ebuf);
4036 if (library == NULL) {
4037 const char *sub_msg = " in absolute path, with error: ";
4038 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4039 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4040 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4041 // If we can't find the agent, exit.
4042 vm_exit_during_initialization(buf, NULL);
4043 FREE_C_HEAP_ARRAY(char, buf);
4044 }
4045 } else {
4046 // Try to load the agent from the standard dll directory
4047 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4048 name)) {
4049 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4050 }
4051 if (library == NULL) { // Try the library path directory.
4052 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4053 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4054 }
4055 if (library == NULL) {
4056 const char *sub_msg = " on the library path, with error: ";
4057 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4058
4059 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4060 strlen(ebuf) + strlen(sub_msg2) + 1;
4061 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4062 if (!agent->is_instrument_lib()) {
4063 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4064 } else {
4065 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4066 }
4067 // If we can't find the agent, exit.
4068 vm_exit_during_initialization(buf, NULL);
4069 FREE_C_HEAP_ARRAY(char, buf);
4070 }
4071 }
4072 }
4073 agent->set_os_lib(library);
4074 agent->set_valid();
4075 }
4076
4077 // Find the OnLoad function.
4078 on_load_entry =
4079 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4080 false,
4081 on_load_symbols,
4082 num_symbol_entries));
4083 return on_load_entry;
4084 }
4085
4086 // Find the JVM_OnLoad entry point
4087 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4088 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4089 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4090 }
4091
4092 // Find the Agent_OnLoad entry point
4093 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4094 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4095 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4096 }
4097
4098 // For backwards compatibility with -Xrun
4099 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4100 // treated like -agentpath:
4101 // Must be called before agent libraries are created
4102 void Threads::convert_vm_init_libraries_to_agents() {
4103 AgentLibrary* agent;
4104 AgentLibrary* next;
4105
4106 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4107 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4108 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4109
4110 // If there is an JVM_OnLoad function it will get called later,
4111 // otherwise see if there is an Agent_OnLoad
4112 if (on_load_entry == NULL) {
4113 on_load_entry = lookup_agent_on_load(agent);
4114 if (on_load_entry != NULL) {
4115 // switch it to the agent list -- so that Agent_OnLoad will be called,
4116 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4117 Arguments::convert_library_to_agent(agent);
4118 } else {
4119 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4120 }
4121 }
4122 }
4123 }
4124
4125 // Create agents for -agentlib: -agentpath: and converted -Xrun
4126 // Invokes Agent_OnLoad
4127 // Called very early -- before JavaThreads exist
4128 void Threads::create_vm_init_agents() {
4129 extern struct JavaVM_ main_vm;
4130 AgentLibrary* agent;
4131
4132 JvmtiExport::enter_onload_phase();
4133
4134 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4135 // CDS dumping does not support native JVMTI agent.
4136 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4137 if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4138 if(!agent->is_instrument_lib()) {
4139 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4140 } else if (!AllowArchivingWithJavaAgent) {
4141 vm_exit_during_cds_dumping(
4142 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4143 }
4144 }
4145
4146 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4147
4148 if (on_load_entry != NULL) {
4149 // Invoke the Agent_OnLoad function
4150 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4151 if (err != JNI_OK) {
4152 vm_exit_during_initialization("agent library failed to init", agent->name());
4153 }
4154 } else {
4155 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4156 }
4157 }
4158
4159 JvmtiExport::enter_primordial_phase();
4160 }
4161
4162 extern "C" {
4163 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4164 }
4165
4166 void Threads::shutdown_vm_agents() {
4167 // Send any Agent_OnUnload notifications
4168 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4169 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4170 extern struct JavaVM_ main_vm;
4171 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4172
4173 // Find the Agent_OnUnload function.
4174 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4175 os::find_agent_function(agent,
4176 false,
4177 on_unload_symbols,
4178 num_symbol_entries));
4179
4180 // Invoke the Agent_OnUnload function
4181 if (unload_entry != NULL) {
4182 JavaThread* thread = JavaThread::current();
4183 ThreadToNativeFromVM ttn(thread);
4184 HandleMark hm(thread);
4185 (*unload_entry)(&main_vm);
4186 }
4187 }
4188 }
4189
4190 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4191 // Invokes JVM_OnLoad
4192 void Threads::create_vm_init_libraries() {
4193 extern struct JavaVM_ main_vm;
4194 AgentLibrary* agent;
4195
4196 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4197 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4198
4199 if (on_load_entry != NULL) {
4200 // Invoke the JVM_OnLoad function
4201 JavaThread* thread = JavaThread::current();
4202 ThreadToNativeFromVM ttn(thread);
4203 HandleMark hm(thread);
4204 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4205 if (err != JNI_OK) {
4206 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4207 }
4208 } else {
4209 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4210 }
4211 }
4212 }
4213
4214
4215 // Last thread running calls java.lang.Shutdown.shutdown()
4216 void JavaThread::invoke_shutdown_hooks() {
4217 HandleMark hm(this);
4218
4219 // We could get here with a pending exception, if so clear it now.
4220 if (this->has_pending_exception()) {
4221 this->clear_pending_exception();
4222 }
4223
4224 EXCEPTION_MARK;
4225 Klass* shutdown_klass =
4226 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4227 THREAD);
4228 if (shutdown_klass != NULL) {
4229 // SystemDictionary::resolve_or_null will return null if there was
4230 // an exception. If we cannot load the Shutdown class, just don't
4231 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4232 // won't be run. Note that if a shutdown hook was registered,
4233 // the Shutdown class would have already been loaded
4234 // (Runtime.addShutdownHook will load it).
4235 JavaValue result(T_VOID);
4236 JavaCalls::call_static(&result,
4237 shutdown_klass,
4238 vmSymbols::shutdown_name(),
4239 vmSymbols::void_method_signature(),
4240 THREAD);
4241 }
4242 CLEAR_PENDING_EXCEPTION;
4243 }
4244
4245 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4246 // the program falls off the end of main(). Another VM exit path is through
4247 // vm_exit() when the program calls System.exit() to return a value or when
4248 // there is a serious error in VM. The two shutdown paths are not exactly
4249 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4250 // and VM_Exit op at VM level.
4251 //
4252 // Shutdown sequence:
4253 // + Shutdown native memory tracking if it is on
4254 // + Wait until we are the last non-daemon thread to execute
4255 // <-- every thing is still working at this moment -->
4256 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4257 // shutdown hooks
4258 // + Call before_exit(), prepare for VM exit
4259 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4260 // currently the only user of this mechanism is File.deleteOnExit())
4261 // > stop StatSampler, watcher thread, CMS threads,
4262 // post thread end and vm death events to JVMTI,
4263 // stop signal thread
4264 // + Call JavaThread::exit(), it will:
4265 // > release JNI handle blocks, remove stack guard pages
4266 // > remove this thread from Threads list
4267 // <-- no more Java code from this thread after this point -->
4268 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4269 // the compiler threads at safepoint
4270 // <-- do not use anything that could get blocked by Safepoint -->
4271 // + Disable tracing at JNI/JVM barriers
4272 // + Set _vm_exited flag for threads that are still running native code
4273 // + Call exit_globals()
4274 // > deletes tty
4275 // > deletes PerfMemory resources
4276 // + Delete this thread
4277 // + Return to caller
4278
4279 bool Threads::destroy_vm() {
4280 JavaThread* thread = JavaThread::current();
4281
4282 #ifdef ASSERT
4283 _vm_complete = false;
4284 #endif
4285 // Wait until we are the last non-daemon thread to execute
4286 { MonitorLocker nu(Threads_lock);
4287 while (Threads::number_of_non_daemon_threads() > 1)
4288 // This wait should make safepoint checks, wait without a timeout,
4289 // and wait as a suspend-equivalent condition.
4290 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4291 }
4292
4293 EventShutdown e;
4294 if (e.should_commit()) {
4295 e.set_reason("No remaining non-daemon Java threads");
4296 e.commit();
4297 }
4298
4299 // Hang forever on exit if we are reporting an error.
4300 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4301 os::infinite_sleep();
4302 }
4303 os::wait_for_keypress_at_exit();
4304
4305 // run Java level shutdown hooks
4306 thread->invoke_shutdown_hooks();
4307
4308 before_exit(thread);
4309
4310 thread->exit(true);
4311
4312 // Stop VM thread.
4313 {
4314 // 4945125 The vm thread comes to a safepoint during exit.
4315 // GC vm_operations can get caught at the safepoint, and the
4316 // heap is unparseable if they are caught. Grab the Heap_lock
4317 // to prevent this. The GC vm_operations will not be able to
4318 // queue until after the vm thread is dead. After this point,
4319 // we'll never emerge out of the safepoint before the VM exits.
4320
4321 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4322
4323 VMThread::wait_for_vm_thread_exit();
4324 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4325 VMThread::destroy();
4326 }
4327
4328 // Now, all Java threads are gone except daemon threads. Daemon threads
4329 // running Java code or in VM are stopped by the Safepoint. However,
4330 // daemon threads executing native code are still running. But they
4331 // will be stopped at native=>Java/VM barriers. Note that we can't
4332 // simply kill or suspend them, as it is inherently deadlock-prone.
4333
4334 VM_Exit::set_vm_exited();
4335
4336 // Clean up ideal graph printers after the VMThread has started
4337 // the final safepoint which will block all the Compiler threads.
4338 // Note that this Thread has already logically exited so the
4339 // clean_up() function's use of a JavaThreadIteratorWithHandle
4340 // would be a problem except set_vm_exited() has remembered the
4341 // shutdown thread which is granted a policy exception.
4342 #if defined(COMPILER2) && !defined(PRODUCT)
4343 IdealGraphPrinter::clean_up();
4344 #endif
4345
4346 notify_vm_shutdown();
4347
4348 // exit_globals() will delete tty
4349 exit_globals();
4350
4351 // We are after VM_Exit::set_vm_exited() so we can't call
4352 // thread->smr_delete() or we will block on the Threads_lock.
4353 // Deleting the shutdown thread here is safe because another
4354 // JavaThread cannot have an active ThreadsListHandle for
4355 // this JavaThread.
4356 delete thread;
4357
4358 #if INCLUDE_JVMCI
4359 if (JVMCICounterSize > 0) {
4360 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4361 }
4362 #endif
4363
4364 LogConfiguration::finalize();
4365
4366 return true;
4367 }
4368
4369
4370 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4371 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4372 return is_supported_jni_version(version);
4373 }
4374
4375
4376 jboolean Threads::is_supported_jni_version(jint version) {
4377 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4378 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4379 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4380 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4381 if (version == JNI_VERSION_9) return JNI_TRUE;
4382 if (version == JNI_VERSION_10) return JNI_TRUE;
4383 return JNI_FALSE;
4384 }
4385
4386
4387 void Threads::add(JavaThread* p, bool force_daemon) {
4388 // The threads lock must be owned at this point
4389 assert(Threads_lock->owned_by_self(), "must have threads lock");
4390
4391 BarrierSet::barrier_set()->on_thread_attach(p);
4392
4393 // Once a JavaThread is added to the Threads list, smr_delete() has
4394 // to be used to delete it. Otherwise we can just delete it directly.
4395 p->set_on_thread_list();
4396
4397 _number_of_threads++;
4398 oop threadObj = p->threadObj();
4399 bool daemon = true;
4400 // Bootstrapping problem: threadObj can be null for initial
4401 // JavaThread (or for threads attached via JNI)
4402 if ((!force_daemon) && !is_daemon((threadObj))) {
4403 _number_of_non_daemon_threads++;
4404 daemon = false;
4405 }
4406
4407 ThreadService::add_thread(p, daemon);
4408
4409 // Maintain fast thread list
4410 ThreadsSMRSupport::add_thread(p);
4411
4412 // Possible GC point.
4413 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4414 }
4415
4416 void Threads::remove(JavaThread* p, bool is_daemon) {
4417
4418 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread.
4419 ObjectSynchronizer::om_flush(p);
4420
4421 // Extra scope needed for Thread_lock, so we can check
4422 // that we do not remove thread without safepoint code notice
4423 { MonitorLocker ml(Threads_lock);
4424
4425 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4426
4427 // Maintain fast thread list
4428 ThreadsSMRSupport::remove_thread(p);
4429
4430 _number_of_threads--;
4431 if (!is_daemon) {
4432 _number_of_non_daemon_threads--;
4433
4434 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4435 // on destroy_vm will wake up.
4436 if (number_of_non_daemon_threads() == 1) {
4437 ml.notify_all();
4438 }
4439 }
4440 ThreadService::remove_thread(p, is_daemon);
4441
4442 // Make sure that safepoint code disregard this thread. This is needed since
4443 // the thread might mess around with locks after this point. This can cause it
4444 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4445 // of this thread since it is removed from the queue.
4446 p->set_terminated_value();
4447 } // unlock Threads_lock
4448
4449 // Since Events::log uses a lock, we grab it outside the Threads_lock
4450 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4451 }
4452
4453 // Operations on the Threads list for GC. These are not explicitly locked,
4454 // but the garbage collector must provide a safe context for them to run.
4455 // In particular, these things should never be called when the Threads_lock
4456 // is held by some other thread. (Note: the Safepoint abstraction also
4457 // uses the Threads_lock to guarantee this property. It also makes sure that
4458 // all threads gets blocked when exiting or starting).
4459
4460 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4461 ALL_JAVA_THREADS(p) {
4462 p->oops_do(f, cf);
4463 }
4464 VMThread::vm_thread()->oops_do(f, cf);
4465 }
4466
4467 void Threads::change_thread_claim_token() {
4468 if (++_thread_claim_token == 0) {
4469 // On overflow of the token counter, there is a risk of future
4470 // collisions between a new global token value and a stale token
4471 // for a thread, because not all iterations visit all threads.
4472 // (Though it's pretty much a theoretical concern for non-trivial
4473 // token counter sizes.) To deal with the possibility, reset all
4474 // the thread tokens to zero on global token overflow.
4475 struct ResetClaims : public ThreadClosure {
4476 virtual void do_thread(Thread* t) {
4477 t->claim_threads_do(false, 0);
4478 }
4479 } reset_claims;
4480 Threads::threads_do(&reset_claims);
4481 // On overflow, update the global token to non-zero, to
4482 // avoid the special "never claimed" initial thread value.
4483 _thread_claim_token = 1;
4484 }
4485 }
4486
4487 #ifdef ASSERT
4488 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4489 const uintx token = t->threads_do_token();
4490 assert(token == expected,
4491 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4492 UINTX_FORMAT, kind, p2i(t), token, expected);
4493 }
4494
4495 void Threads::assert_all_threads_claimed() {
4496 ALL_JAVA_THREADS(p) {
4497 assert_thread_claimed("Thread", p, _thread_claim_token);
4498 }
4499 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4500 }
4501 #endif // ASSERT
4502
4503 class ParallelOopsDoThreadClosure : public ThreadClosure {
4504 private:
4505 OopClosure* _f;
4506 CodeBlobClosure* _cf;
4507 public:
4508 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4509 void do_thread(Thread* t) {
4510 t->oops_do(_f, _cf);
4511 }
4512 };
4513
4514 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4515 ParallelOopsDoThreadClosure tc(f, cf);
4516 possibly_parallel_threads_do(is_par, &tc);
4517 }
4518
4519 void Threads::nmethods_do(CodeBlobClosure* cf) {
4520 ALL_JAVA_THREADS(p) {
4521 // This is used by the code cache sweeper to mark nmethods that are active
4522 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4523 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4524 if(!p->is_Code_cache_sweeper_thread()) {
4525 p->nmethods_do(cf);
4526 }
4527 }
4528 }
4529
4530 void Threads::metadata_do(MetadataClosure* f) {
4531 ALL_JAVA_THREADS(p) {
4532 p->metadata_do(f);
4533 }
4534 }
4535
4536 class ThreadHandlesClosure : public ThreadClosure {
4537 void (*_f)(Metadata*);
4538 public:
4539 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4540 virtual void do_thread(Thread* thread) {
4541 thread->metadata_handles_do(_f);
4542 }
4543 };
4544
4545 void Threads::metadata_handles_do(void f(Metadata*)) {
4546 // Only walk the Handles in Thread.
4547 ThreadHandlesClosure handles_closure(f);
4548 threads_do(&handles_closure);
4549 }
4550
4551 void Threads::deoptimized_wrt_marked_nmethods() {
4552 ALL_JAVA_THREADS(p) {
4553 p->deoptimized_wrt_marked_nmethods();
4554 }
4555 }
4556
4557
4558 // Get count Java threads that are waiting to enter the specified monitor.
4559 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4560 int count,
4561 address monitor) {
4562 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4563
4564 int i = 0;
4565 DO_JAVA_THREADS(t_list, p) {
4566 if (!p->can_call_java()) continue;
4567
4568 address pending = (address)p->current_pending_monitor();
4569 if (pending == monitor) { // found a match
4570 if (i < count) result->append(p); // save the first count matches
4571 i++;
4572 }
4573 }
4574
4575 return result;
4576 }
4577
4578
4579 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4580 address owner) {
4581 // NULL owner means not locked so we can skip the search
4582 if (owner == NULL) return NULL;
4583
4584 DO_JAVA_THREADS(t_list, p) {
4585 // first, see if owner is the address of a Java thread
4586 if (owner == (address)p) return p;
4587 }
4588
4589 // Cannot assert on lack of success here since this function may be
4590 // used by code that is trying to report useful problem information
4591 // like deadlock detection.
4592 if (UseHeavyMonitors) return NULL;
4593
4594 // If we didn't find a matching Java thread and we didn't force use of
4595 // heavyweight monitors, then the owner is the stack address of the
4596 // Lock Word in the owning Java thread's stack.
4597 //
4598 JavaThread* the_owner = NULL;
4599 DO_JAVA_THREADS(t_list, q) {
4600 if (q->is_lock_owned(owner)) {
4601 the_owner = q;
4602 break;
4603 }
4604 }
4605
4606 // cannot assert on lack of success here; see above comment
4607 return the_owner;
4608 }
4609
4610 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4611 void Threads::print_on(outputStream* st, bool print_stacks,
4612 bool internal_format, bool print_concurrent_locks,
4613 bool print_extended_info) {
4614 char buf[32];
4615 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4616
4617 st->print_cr("Full thread dump %s (%s %s):",
4618 VM_Version::vm_name(),
4619 VM_Version::vm_release(),
4620 VM_Version::vm_info_string());
4621 st->cr();
4622
4623 #if INCLUDE_SERVICES
4624 // Dump concurrent locks
4625 ConcurrentLocksDump concurrent_locks;
4626 if (print_concurrent_locks) {
4627 concurrent_locks.dump_at_safepoint();
4628 }
4629 #endif // INCLUDE_SERVICES
4630
4631 ThreadsSMRSupport::print_info_on(st);
4632 st->cr();
4633
4634 ALL_JAVA_THREADS(p) {
4635 ResourceMark rm;
4636 p->print_on(st, print_extended_info);
4637 if (print_stacks) {
4638 if (internal_format) {
4639 p->trace_stack();
4640 } else {
4641 p->print_stack_on(st);
4642 }
4643 }
4644 st->cr();
4645 #if INCLUDE_SERVICES
4646 if (print_concurrent_locks) {
4647 concurrent_locks.print_locks_on(p, st);
4648 }
4649 #endif // INCLUDE_SERVICES
4650 }
4651
4652 VMThread::vm_thread()->print_on(st);
4653 st->cr();
4654 Universe::heap()->print_gc_threads_on(st);
4655 WatcherThread* wt = WatcherThread::watcher_thread();
4656 if (wt != NULL) {
4657 wt->print_on(st);
4658 st->cr();
4659 }
4660
4661 st->flush();
4662 }
4663
4664 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4665 int buflen, bool* found_current) {
4666 if (this_thread != NULL) {
4667 bool is_current = (current == this_thread);
4668 *found_current = *found_current || is_current;
4669 st->print("%s", is_current ? "=>" : " ");
4670
4671 st->print(PTR_FORMAT, p2i(this_thread));
4672 st->print(" ");
4673 this_thread->print_on_error(st, buf, buflen);
4674 st->cr();
4675 }
4676 }
4677
4678 class PrintOnErrorClosure : public ThreadClosure {
4679 outputStream* _st;
4680 Thread* _current;
4681 char* _buf;
4682 int _buflen;
4683 bool* _found_current;
4684 public:
4685 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4686 int buflen, bool* found_current) :
4687 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4688
4689 virtual void do_thread(Thread* thread) {
4690 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4691 }
4692 };
4693
4694 // Threads::print_on_error() is called by fatal error handler. It's possible
4695 // that VM is not at safepoint and/or current thread is inside signal handler.
4696 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4697 // memory (even in resource area), it might deadlock the error handler.
4698 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4699 int buflen) {
4700 ThreadsSMRSupport::print_info_on(st);
4701 st->cr();
4702
4703 bool found_current = false;
4704 st->print_cr("Java Threads: ( => current thread )");
4705 ALL_JAVA_THREADS(thread) {
4706 print_on_error(thread, st, current, buf, buflen, &found_current);
4707 }
4708 st->cr();
4709
4710 st->print_cr("Other Threads:");
4711 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4712 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4713
4714 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4715 Universe::heap()->gc_threads_do(&print_closure);
4716
4717 if (!found_current) {
4718 st->cr();
4719 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4720 current->print_on_error(st, buf, buflen);
4721 st->cr();
4722 }
4723 st->cr();
4724
4725 st->print_cr("Threads with active compile tasks:");
4726 print_threads_compiling(st, buf, buflen);
4727 }
4728
4729 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4730 ALL_JAVA_THREADS(thread) {
4731 if (thread->is_Compiler_thread()) {
4732 CompilerThread* ct = (CompilerThread*) thread;
4733
4734 // Keep task in local variable for NULL check.
4735 // ct->_task might be set to NULL by concurring compiler thread
4736 // because it completed the compilation. The task is never freed,
4737 // though, just returned to a free list.
4738 CompileTask* task = ct->task();
4739 if (task != NULL) {
4740 thread->print_name_on_error(st, buf, buflen);
4741 st->print(" ");
4742 task->print(st, NULL, short_form, true);
4743 }
4744 }
4745 }
4746 }
4747
4748
4749 // Internal SpinLock and Mutex
4750 // Based on ParkEvent
4751
4752 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4753 //
4754 // We employ SpinLocks _only for low-contention, fixed-length
4755 // short-duration critical sections where we're concerned
4756 // about native mutex_t or HotSpot Mutex:: latency.
4757 // The mux construct provides a spin-then-block mutual exclusion
4758 // mechanism.
4759 //
4760 // Testing has shown that contention on the ListLock guarding gFreeList
4761 // is common. If we implement ListLock as a simple SpinLock it's common
4762 // for the JVM to devolve to yielding with little progress. This is true
4763 // despite the fact that the critical sections protected by ListLock are
4764 // extremely short.
4765 //
4766 // TODO-FIXME: ListLock should be of type SpinLock.
4767 // We should make this a 1st-class type, integrated into the lock
4768 // hierarchy as leaf-locks. Critically, the SpinLock structure
4769 // should have sufficient padding to avoid false-sharing and excessive
4770 // cache-coherency traffic.
4771
4772
4773 typedef volatile int SpinLockT;
4774
4775 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4776 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4777 return; // normal fast-path return
4778 }
4779
4780 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4781 int ctr = 0;
4782 int Yields = 0;
4783 for (;;) {
4784 while (*adr != 0) {
4785 ++ctr;
4786 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4787 if (Yields > 5) {
4788 os::naked_short_sleep(1);
4789 } else {
4790 os::naked_yield();
4791 ++Yields;
4792 }
4793 } else {
4794 SpinPause();
4795 }
4796 }
4797 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4798 }
4799 }
4800
4801 void Thread::SpinRelease(volatile int * adr) {
4802 assert(*adr != 0, "invariant");
4803 OrderAccess::fence(); // guarantee at least release consistency.
4804 // Roach-motel semantics.
4805 // It's safe if subsequent LDs and STs float "up" into the critical section,
4806 // but prior LDs and STs within the critical section can't be allowed
4807 // to reorder or float past the ST that releases the lock.
4808 // Loads and stores in the critical section - which appear in program
4809 // order before the store that releases the lock - must also appear
4810 // before the store that releases the lock in memory visibility order.
4811 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4812 // the ST of 0 into the lock-word which releases the lock, so fence
4813 // more than covers this on all platforms.
4814 *adr = 0;
4815 }
4816
4817 // muxAcquire and muxRelease:
4818 //
4819 // * muxAcquire and muxRelease support a single-word lock-word construct.
4820 // The LSB of the word is set IFF the lock is held.
4821 // The remainder of the word points to the head of a singly-linked list
4822 // of threads blocked on the lock.
4823 //
4824 // * The current implementation of muxAcquire-muxRelease uses its own
4825 // dedicated Thread._MuxEvent instance. If we're interested in
4826 // minimizing the peak number of extant ParkEvent instances then
4827 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4828 // as certain invariants were satisfied. Specifically, care would need
4829 // to be taken with regards to consuming unpark() "permits".
4830 // A safe rule of thumb is that a thread would never call muxAcquire()
4831 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4832 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4833 // consume an unpark() permit intended for monitorenter, for instance.
4834 // One way around this would be to widen the restricted-range semaphore
4835 // implemented in park(). Another alternative would be to provide
4836 // multiple instances of the PlatformEvent() for each thread. One
4837 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4838 //
4839 // * Usage:
4840 // -- Only as leaf locks
4841 // -- for short-term locking only as muxAcquire does not perform
4842 // thread state transitions.
4843 //
4844 // Alternatives:
4845 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4846 // but with parking or spin-then-park instead of pure spinning.
4847 // * Use Taura-Oyama-Yonenzawa locks.
4848 // * It's possible to construct a 1-0 lock if we encode the lockword as
4849 // (List,LockByte). Acquire will CAS the full lockword while Release
4850 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4851 // acquiring threads use timers (ParkTimed) to detect and recover from
4852 // the stranding window. Thread/Node structures must be aligned on 256-byte
4853 // boundaries by using placement-new.
4854 // * Augment MCS with advisory back-link fields maintained with CAS().
4855 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4856 // The validity of the backlinks must be ratified before we trust the value.
4857 // If the backlinks are invalid the exiting thread must back-track through the
4858 // the forward links, which are always trustworthy.
4859 // * Add a successor indication. The LockWord is currently encoded as
4860 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4861 // to provide the usual futile-wakeup optimization.
4862 // See RTStt for details.
4863 //
4864
4865
4866 const intptr_t LOCKBIT = 1;
4867
4868 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4869 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4870 if (w == 0) return;
4871 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4872 return;
4873 }
4874
4875 ParkEvent * const Self = Thread::current()->_MuxEvent;
4876 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4877 for (;;) {
4878 int its = (os::is_MP() ? 100 : 0) + 1;
4879
4880 // Optional spin phase: spin-then-park strategy
4881 while (--its >= 0) {
4882 w = *Lock;
4883 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4884 return;
4885 }
4886 }
4887
4888 Self->reset();
4889 Self->OnList = intptr_t(Lock);
4890 // The following fence() isn't _strictly necessary as the subsequent
4891 // CAS() both serializes execution and ratifies the fetched *Lock value.
4892 OrderAccess::fence();
4893 for (;;) {
4894 w = *Lock;
4895 if ((w & LOCKBIT) == 0) {
4896 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4897 Self->OnList = 0; // hygiene - allows stronger asserts
4898 return;
4899 }
4900 continue; // Interference -- *Lock changed -- Just retry
4901 }
4902 assert(w & LOCKBIT, "invariant");
4903 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4904 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4905 }
4906
4907 while (Self->OnList != 0) {
4908 Self->park();
4909 }
4910 }
4911 }
4912
4913 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4914 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4915 if (w == 0) return;
4916 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4917 return;
4918 }
4919
4920 ParkEvent * ReleaseAfter = NULL;
4921 if (ev == NULL) {
4922 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4923 }
4924 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4925 for (;;) {
4926 guarantee(ev->OnList == 0, "invariant");
4927 int its = (os::is_MP() ? 100 : 0) + 1;
4928
4929 // Optional spin phase: spin-then-park strategy
4930 while (--its >= 0) {
4931 w = *Lock;
4932 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4933 if (ReleaseAfter != NULL) {
4934 ParkEvent::Release(ReleaseAfter);
4935 }
4936 return;
4937 }
4938 }
4939
4940 ev->reset();
4941 ev->OnList = intptr_t(Lock);
4942 // The following fence() isn't _strictly necessary as the subsequent
4943 // CAS() both serializes execution and ratifies the fetched *Lock value.
4944 OrderAccess::fence();
4945 for (;;) {
4946 w = *Lock;
4947 if ((w & LOCKBIT) == 0) {
4948 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4949 ev->OnList = 0;
4950 // We call ::Release while holding the outer lock, thus
4951 // artificially lengthening the critical section.
4952 // Consider deferring the ::Release() until the subsequent unlock(),
4953 // after we've dropped the outer lock.
4954 if (ReleaseAfter != NULL) {
4955 ParkEvent::Release(ReleaseAfter);
4956 }
4957 return;
4958 }
4959 continue; // Interference -- *Lock changed -- Just retry
4960 }
4961 assert(w & LOCKBIT, "invariant");
4962 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4963 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4964 }
4965
4966 while (ev->OnList != 0) {
4967 ev->park();
4968 }
4969 }
4970 }
4971
4972 // Release() must extract a successor from the list and then wake that thread.
4973 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4974 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4975 // Release() would :
4976 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4977 // (B) Extract a successor from the private list "in-hand"
4978 // (C) attempt to CAS() the residual back into *Lock over null.
4979 // If there were any newly arrived threads and the CAS() would fail.
4980 // In that case Release() would detach the RATs, re-merge the list in-hand
4981 // with the RATs and repeat as needed. Alternately, Release() might
4982 // detach and extract a successor, but then pass the residual list to the wakee.
4983 // The wakee would be responsible for reattaching and remerging before it
4984 // competed for the lock.
4985 //
4986 // Both "pop" and DMR are immune from ABA corruption -- there can be
4987 // multiple concurrent pushers, but only one popper or detacher.
4988 // This implementation pops from the head of the list. This is unfair,
4989 // but tends to provide excellent throughput as hot threads remain hot.
4990 // (We wake recently run threads first).
4991 //
4992 // All paths through muxRelease() will execute a CAS.
4993 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4994 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4995 // executed within the critical section are complete and globally visible before the
4996 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4997 void Thread::muxRelease(volatile intptr_t * Lock) {
4998 for (;;) {
4999 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5000 assert(w & LOCKBIT, "invariant");
5001 if (w == LOCKBIT) return;
5002 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5003 assert(List != NULL, "invariant");
5004 assert(List->OnList == intptr_t(Lock), "invariant");
5005 ParkEvent * const nxt = List->ListNext;
5006 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5007
5008 // The following CAS() releases the lock and pops the head element.
5009 // The CAS() also ratifies the previously fetched lock-word value.
5010 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5011 continue;
5012 }
5013 List->OnList = 0;
5014 OrderAccess::fence();
5015 List->unpark();
5016 return;
5017 }
5018 }
5019
5020
5021 void Threads::verify() {
5022 ALL_JAVA_THREADS(p) {
5023 p->verify();
5024 }
5025 VMThread* thread = VMThread::vm_thread();
5026 if (thread != NULL) thread->verify();
5027 }