1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jvmtifiles/jvmtiEnv.hpp"
45 #include "logging/log.hpp"
46 #include "logging/logConfiguration.hpp"
47 #include "logging/logStream.hpp"
48 #include "memory/allocation.inline.hpp"
49 #include "memory/metaspaceShared.hpp"
50 #include "memory/oopFactory.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "memory/universe.hpp"
53 #include "oops/access.inline.hpp"
54 #include "oops/instanceKlass.hpp"
55 #include "oops/objArrayOop.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/symbol.hpp"
58 #include "oops/typeArrayOop.inline.hpp"
59 #include "oops/verifyOopClosure.hpp"
60 #include "prims/jvm_misc.hpp"
61 #include "prims/jvmtiExport.hpp"
62 #include "prims/jvmtiThreadState.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/fieldDescriptor.inline.hpp"
67 #include "runtime/flags/jvmFlagConstraintList.hpp"
68 #include "runtime/flags/jvmFlagRangeList.hpp"
69 #include "runtime/flags/jvmFlagWriteableList.hpp"
70 #include "runtime/deoptimization.hpp"
71 #include "runtime/frame.inline.hpp"
72 #include "runtime/handles.inline.hpp"
73 #include "runtime/handshake.hpp"
74 #include "runtime/init.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/jniHandles.inline.hpp"
79 #include "runtime/jniPeriodicChecker.hpp"
80 #include "runtime/memprofiler.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/objectMonitor.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/osThread.hpp"
85 #include "runtime/prefetch.inline.hpp"
86 #include "runtime/safepoint.hpp"
87 #include "runtime/safepointMechanism.inline.hpp"
88 #include "runtime/safepointVerifiers.hpp"
89 #include "runtime/sharedRuntime.hpp"
90 #include "runtime/statSampler.hpp"
91 #include "runtime/stubRoutines.hpp"
92 #include "runtime/sweeper.hpp"
93 #include "runtime/task.hpp"
94 #include "runtime/thread.inline.hpp"
95 #include "runtime/threadCritical.hpp"
96 #include "runtime/threadSMR.inline.hpp"
97 #include "runtime/threadStatisticalInfo.hpp"
98 #include "runtime/timer.hpp"
99 #include "runtime/timerTrace.hpp"
100 #include "runtime/vframe.inline.hpp"
101 #include "runtime/vframeArray.hpp"
102 #include "runtime/vframe_hp.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "runtime/vmOperations.hpp"
105 #include "runtime/vm_version.hpp"
106 #include "services/attachListener.hpp"
107 #include "services/management.hpp"
108 #include "services/memTracker.hpp"
109 #include "services/threadService.hpp"
110 #include "utilities/align.hpp"
111 #include "utilities/copy.hpp"
112 #include "utilities/defaultStream.hpp"
113 #include "utilities/dtrace.hpp"
114 #include "utilities/events.hpp"
115 #include "utilities/macros.hpp"
116 #include "utilities/preserveException.hpp"
117 #include "utilities/singleWriterSynchronizer.hpp"
118 #include "utilities/vmError.hpp"
119 #if INCLUDE_JVMCI
120 #include "jvmci/jvmciCompiler.hpp"
121 #include "jvmci/jvmciRuntime.hpp"
122 #include "logging/logHandle.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 = markOopDesc::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_self_raw_id(0);
227 set_lgrp_id(-1);
228 DEBUG_ONLY(clear_suspendible_thread();)
229
230 // allocated data structures
231 set_osthread(NULL);
232 set_resource_area(new (mtThread)ResourceArea());
233 DEBUG_ONLY(_current_resource_mark = NULL;)
234 set_handle_area(new (mtThread) HandleArea(NULL));
235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
236 set_active_handles(NULL);
237 set_free_handle_block(NULL);
238 set_last_handle_mark(NULL);
239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
240
241 // This initial value ==> never claimed.
242 _oops_do_parity = 0;
243 _threads_hazard_ptr = NULL;
244 _threads_list_ptr = NULL;
245 _nested_threads_hazard_ptr_cnt = 0;
246 _rcu_counter = 0;
247
248 // the handle mark links itself to last_handle_mark
249 new HandleMark(this);
250
251 // plain initialization
252 debug_only(_owned_locks = NULL;)
253 debug_only(_allow_allocation_count = 0;)
254 NOT_PRODUCT(_allow_safepoint_count = 0;)
255 NOT_PRODUCT(_skip_gcalot = false;)
256 _jvmti_env_iteration_count = 0;
257 set_allocated_bytes(0);
258 _vm_operation_started_count = 0;
259 _vm_operation_completed_count = 0;
260 _current_pending_monitor = NULL;
261 _current_pending_monitor_is_from_java = true;
262 _current_waiting_monitor = NULL;
263 _num_nested_signal = 0;
264 omFreeList = NULL;
265 omFreeCount = 0;
266 omFreeProvision = 32;
267 omInUseList = NULL;
268 omInUseCount = 0;
269
270 #ifdef ASSERT
271 _visited_for_critical_count = false;
272 #endif
273
274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
275 Monitor::_safepoint_check_sometimes);
276 _suspend_flags = 0;
277
278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
279 _hashStateX = os::random();
280 _hashStateY = 842502087;
281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
282 _hashStateW = 273326509;
283
284 _OnTrap = 0;
285 _Stalled = 0;
286 _TypeTag = 0x2BAD;
287
288 // Many of the following fields are effectively final - immutable
289 // Note that nascent threads can't use the Native Monitor-Mutex
290 // construct until the _MutexEvent is initialized ...
291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
292 // we might instead use a stack of ParkEvents that we could provision on-demand.
293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
294 // and ::Release()
295 _ParkEvent = ParkEvent::Allocate(this);
296 _SleepEvent = ParkEvent::Allocate(this);
297 _MuxEvent = ParkEvent::Allocate(this);
298
299 #ifdef CHECK_UNHANDLED_OOPS
300 if (CheckUnhandledOops) {
301 _unhandled_oops = new UnhandledOops(this);
302 }
303 #endif // CHECK_UNHANDLED_OOPS
304 #ifdef ASSERT
305 if (UseBiasedLocking) {
306 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
307 assert(this == _real_malloc_address ||
308 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
309 "bug in forced alignment of thread objects");
310 }
311 #endif // ASSERT
312
313 // Notify the barrier set that a thread is being created. The initial
314 // thread is created before the barrier set is available. The call to
315 // BarrierSet::on_thread_create() for this thread is therefore deferred
316 // to BarrierSet::set_barrier_set().
317 BarrierSet* const barrier_set = BarrierSet::barrier_set();
318 if (barrier_set != NULL) {
319 barrier_set->on_thread_create(this);
320 } else {
321 // Only the main thread should be created before the barrier set
322 // and that happens just before Thread::current is set. No other thread
323 // can attach as the VM is not created yet, so they can't execute this code.
324 // If the main thread creates other threads before the barrier set that is an error.
325 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
326 }
327 }
328
329 void Thread::initialize_thread_current() {
330 #ifndef USE_LIBRARY_BASED_TLS_ONLY
331 assert(_thr_current == NULL, "Thread::current already initialized");
332 _thr_current = this;
333 #endif
334 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
335 ThreadLocalStorage::set_thread(this);
336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
337 }
338
339 void Thread::clear_thread_current() {
340 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
341 #ifndef USE_LIBRARY_BASED_TLS_ONLY
342 _thr_current = NULL;
343 #endif
344 ThreadLocalStorage::set_thread(NULL);
345 }
346
347 void Thread::record_stack_base_and_size() {
348 // Note: at this point, Thread object is not yet initialized. Do not rely on
349 // any members being initialized. Do not rely on Thread::current() being set.
350 // If possible, refrain from doing anything which may crash or assert since
351 // quite probably those crash dumps will be useless.
352 set_stack_base(os::current_stack_base());
353 set_stack_size(os::current_stack_size());
354
355 #ifdef SOLARIS
356 if (os::is_primordial_thread()) {
357 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
358 }
359 #endif
360
361 // Set stack limits after thread is initialized.
362 if (is_Java_thread()) {
363 ((JavaThread*) this)->set_stack_overflow_limit();
364 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
365 }
366 }
367
368 #if INCLUDE_NMT
369 void Thread::register_thread_stack_with_NMT() {
370 MemTracker::record_thread_stack(stack_end(), stack_size());
371 }
372 #endif // INCLUDE_NMT
373
374 void Thread::call_run() {
375 DEBUG_ONLY(_run_state = CALL_RUN;)
376
377 // At this point, Thread object should be fully initialized and
378 // Thread::current() should be set.
379
380 assert(Thread::current_or_null() != NULL, "current thread is unset");
381 assert(Thread::current_or_null() == this, "current thread is wrong");
382
383 // Perform common initialization actions
384
385 register_thread_stack_with_NMT();
386
387 JFR_ONLY(Jfr::on_thread_start(this);)
388
389 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
390 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
391 os::current_thread_id(), p2i(stack_base() - stack_size()),
392 p2i(stack_base()), stack_size()/1024);
393
394 // Perform <ChildClass> initialization actions
395 DEBUG_ONLY(_run_state = PRE_RUN;)
396 this->pre_run();
397
398 // Invoke <ChildClass>::run()
399 DEBUG_ONLY(_run_state = RUN;)
400 this->run();
401 // Returned from <ChildClass>::run(). Thread finished.
402
403 // Perform common tear-down actions
404
405 assert(Thread::current_or_null() != NULL, "current thread is unset");
406 assert(Thread::current_or_null() == this, "current thread is wrong");
407
408 // Perform <ChildClass> tear-down actions
409 DEBUG_ONLY(_run_state = POST_RUN;)
410 this->post_run();
411
412 // Note: at this point the thread object may already have deleted itself,
413 // so from here on do not dereference *this*. Not all thread types currently
414 // delete themselves when they terminate. But no thread should ever be deleted
415 // asynchronously with respect to its termination - that is what _run_state can
416 // be used to check.
417
418 assert(Thread::current_or_null() == NULL, "current thread still present");
419 }
420
421 Thread::~Thread() {
422
423 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
424 // get started due to errors etc. Any active thread should at least reach post_run
425 // before it is deleted (usually in post_run()).
426 assert(_run_state == PRE_CALL_RUN ||
427 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
428 "_run_state=%d", (int)_run_state);
429
430 // Notify the barrier set that a thread is being destroyed. Note that a barrier
431 // set might not be available if we encountered errors during bootstrapping.
432 BarrierSet* const barrier_set = BarrierSet::barrier_set();
433 if (barrier_set != NULL) {
434 barrier_set->on_thread_destroy(this);
435 }
436
437 // stack_base can be NULL if the thread is never started or exited before
438 // record_stack_base_and_size called. Although, we would like to ensure
439 // that all started threads do call record_stack_base_and_size(), there is
440 // not proper way to enforce that.
441 #if INCLUDE_NMT
442 if (_stack_base != NULL) {
443 MemTracker::release_thread_stack(stack_end(), stack_size());
444 #ifdef ASSERT
445 set_stack_base(NULL);
446 #endif
447 }
448 #endif // INCLUDE_NMT
449
450 // deallocate data structures
451 delete resource_area();
452 // since the handle marks are using the handle area, we have to deallocated the root
453 // handle mark before deallocating the thread's handle area,
454 assert(last_handle_mark() != NULL, "check we have an element");
455 delete last_handle_mark();
456 assert(last_handle_mark() == NULL, "check we have reached the end");
457
458 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
459 // We NULL out the fields for good hygiene.
460 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
461 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
462 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
463
464 delete handle_area();
465 delete metadata_handles();
466
467 // SR_handler uses this as a termination indicator -
468 // needs to happen before os::free_thread()
469 delete _SR_lock;
470 _SR_lock = NULL;
471
472 // osthread() can be NULL, if creation of thread failed.
473 if (osthread() != NULL) os::free_thread(osthread());
474
475 // Clear Thread::current if thread is deleting itself and it has not
476 // already been done. This must be done before the memory is deallocated.
477 // Needed to ensure JNI correctly detects non-attached threads.
478 if (this == Thread::current_or_null()) {
479 Thread::clear_thread_current();
480 }
481
482 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
483 }
484
485 #ifdef ASSERT
486 // A JavaThread is considered "dangling" if it is not the current
487 // thread, has been added the Threads list, the system is not at a
488 // safepoint and the Thread is not "protected".
489 //
490 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
491 assert(!thread->is_Java_thread() || Thread::current() == thread ||
492 !((JavaThread *) thread)->on_thread_list() ||
493 SafepointSynchronize::is_at_safepoint() ||
494 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
495 "possibility of dangling Thread pointer");
496 }
497 #endif
498
499 ThreadPriority Thread::get_priority(const Thread* const thread) {
500 ThreadPriority priority;
501 // Can return an error!
502 (void)os::get_priority(thread, priority);
503 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
504 return priority;
505 }
506
507 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
508 debug_only(check_for_dangling_thread_pointer(thread);)
509 // Can return an error!
510 (void)os::set_priority(thread, priority);
511 }
512
513
514 void Thread::start(Thread* thread) {
515 // Start is different from resume in that its safety is guaranteed by context or
516 // being called from a Java method synchronized on the Thread object.
517 if (!DisableStartThread) {
518 if (thread->is_Java_thread()) {
519 // Initialize the thread state to RUNNABLE before starting this thread.
520 // Can not set it after the thread started because we do not know the
521 // exact thread state at that time. It could be in MONITOR_WAIT or
522 // in SLEEPING or some other state.
523 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
524 java_lang_Thread::RUNNABLE);
525 }
526 os::start_thread(thread);
527 }
528 }
529
530 // Enqueue a VM_Operation to do the job for us - sometime later
531 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
532 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
533 VMThread::execute(vm_stop);
534 }
535
536
537 // Check if an external suspend request has completed (or has been
538 // cancelled). Returns true if the thread is externally suspended and
539 // false otherwise.
540 //
541 // The bits parameter returns information about the code path through
542 // the routine. Useful for debugging:
543 //
544 // set in is_ext_suspend_completed():
545 // 0x00000001 - routine was entered
546 // 0x00000010 - routine return false at end
547 // 0x00000100 - thread exited (return false)
548 // 0x00000200 - suspend request cancelled (return false)
549 // 0x00000400 - thread suspended (return true)
550 // 0x00001000 - thread is in a suspend equivalent state (return true)
551 // 0x00002000 - thread is native and walkable (return true)
552 // 0x00004000 - thread is native_trans and walkable (needed retry)
553 //
554 // set in wait_for_ext_suspend_completion():
555 // 0x00010000 - routine was entered
556 // 0x00020000 - suspend request cancelled before loop (return false)
557 // 0x00040000 - thread suspended before loop (return true)
558 // 0x00080000 - suspend request cancelled in loop (return false)
559 // 0x00100000 - thread suspended in loop (return true)
560 // 0x00200000 - suspend not completed during retry loop (return false)
561
562 // Helper class for tracing suspend wait debug bits.
563 //
564 // 0x00000100 indicates that the target thread exited before it could
565 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
566 // 0x00080000 each indicate a cancelled suspend request so they don't
567 // count as wait failures either.
568 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
569
570 class TraceSuspendDebugBits : public StackObj {
571 private:
572 JavaThread * jt;
573 bool is_wait;
574 bool called_by_wait; // meaningful when !is_wait
575 uint32_t * bits;
576
577 public:
578 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
579 uint32_t *_bits) {
580 jt = _jt;
581 is_wait = _is_wait;
582 called_by_wait = _called_by_wait;
583 bits = _bits;
584 }
585
586 ~TraceSuspendDebugBits() {
587 if (!is_wait) {
588 #if 1
589 // By default, don't trace bits for is_ext_suspend_completed() calls.
590 // That trace is very chatty.
591 return;
592 #else
593 if (!called_by_wait) {
594 // If tracing for is_ext_suspend_completed() is enabled, then only
595 // trace calls to it from wait_for_ext_suspend_completion()
596 return;
597 }
598 #endif
599 }
600
601 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
602 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
603 MutexLocker ml(Threads_lock); // needed for get_thread_name()
604 ResourceMark rm;
605
606 tty->print_cr(
607 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
608 jt->get_thread_name(), *bits);
609
610 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
611 }
612 }
613 }
614 };
615 #undef DEBUG_FALSE_BITS
616
617
618 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
619 uint32_t *bits) {
620 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
621
622 bool did_trans_retry = false; // only do thread_in_native_trans retry once
623 bool do_trans_retry; // flag to force the retry
624
625 *bits |= 0x00000001;
626
627 do {
628 do_trans_retry = false;
629
630 if (is_exiting()) {
631 // Thread is in the process of exiting. This is always checked
632 // first to reduce the risk of dereferencing a freed JavaThread.
633 *bits |= 0x00000100;
634 return false;
635 }
636
637 if (!is_external_suspend()) {
638 // Suspend request is cancelled. This is always checked before
639 // is_ext_suspended() to reduce the risk of a rogue resume
640 // confusing the thread that made the suspend request.
641 *bits |= 0x00000200;
642 return false;
643 }
644
645 if (is_ext_suspended()) {
646 // thread is suspended
647 *bits |= 0x00000400;
648 return true;
649 }
650
651 // Now that we no longer do hard suspends of threads running
652 // native code, the target thread can be changing thread state
653 // while we are in this routine:
654 //
655 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
656 //
657 // We save a copy of the thread state as observed at this moment
658 // and make our decision about suspend completeness based on the
659 // copy. This closes the race where the thread state is seen as
660 // _thread_in_native_trans in the if-thread_blocked check, but is
661 // seen as _thread_blocked in if-thread_in_native_trans check.
662 JavaThreadState save_state = thread_state();
663
664 if (save_state == _thread_blocked && is_suspend_equivalent()) {
665 // If the thread's state is _thread_blocked and this blocking
666 // condition is known to be equivalent to a suspend, then we can
667 // consider the thread to be externally suspended. This means that
668 // the code that sets _thread_blocked has been modified to do
669 // self-suspension if the blocking condition releases. We also
670 // used to check for CONDVAR_WAIT here, but that is now covered by
671 // the _thread_blocked with self-suspension check.
672 //
673 // Return true since we wouldn't be here unless there was still an
674 // external suspend request.
675 *bits |= 0x00001000;
676 return true;
677 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
678 // Threads running native code will self-suspend on native==>VM/Java
679 // transitions. If its stack is walkable (should always be the case
680 // unless this function is called before the actual java_suspend()
681 // call), then the wait is done.
682 *bits |= 0x00002000;
683 return true;
684 } else if (!called_by_wait && !did_trans_retry &&
685 save_state == _thread_in_native_trans &&
686 frame_anchor()->walkable()) {
687 // The thread is transitioning from thread_in_native to another
688 // thread state. check_safepoint_and_suspend_for_native_trans()
689 // will force the thread to self-suspend. If it hasn't gotten
690 // there yet we may have caught the thread in-between the native
691 // code check above and the self-suspend. Lucky us. If we were
692 // called by wait_for_ext_suspend_completion(), then it
693 // will be doing the retries so we don't have to.
694 //
695 // Since we use the saved thread state in the if-statement above,
696 // there is a chance that the thread has already transitioned to
697 // _thread_blocked by the time we get here. In that case, we will
698 // make a single unnecessary pass through the logic below. This
699 // doesn't hurt anything since we still do the trans retry.
700
701 *bits |= 0x00004000;
702
703 // Once the thread leaves thread_in_native_trans for another
704 // thread state, we break out of this retry loop. We shouldn't
705 // need this flag to prevent us from getting back here, but
706 // sometimes paranoia is good.
707 did_trans_retry = true;
708
709 // We wait for the thread to transition to a more usable state.
710 for (int i = 1; i <= SuspendRetryCount; i++) {
711 // We used to do an "os::yield_all(i)" call here with the intention
712 // that yielding would increase on each retry. However, the parameter
713 // is ignored on Linux which means the yield didn't scale up. Waiting
714 // on the SR_lock below provides a much more predictable scale up for
715 // the delay. It also provides a simple/direct point to check for any
716 // safepoint requests from the VMThread
717
718 // temporarily drops SR_lock while doing wait with safepoint check
719 // (if we're a JavaThread - the WatcherThread can also call this)
720 // and increase delay with each retry
721 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
722
723 // check the actual thread state instead of what we saved above
724 if (thread_state() != _thread_in_native_trans) {
725 // the thread has transitioned to another thread state so
726 // try all the checks (except this one) one more time.
727 do_trans_retry = true;
728 break;
729 }
730 } // end retry loop
731
732
733 }
734 } while (do_trans_retry);
735
736 *bits |= 0x00000010;
737 return false;
738 }
739
740 // Wait for an external suspend request to complete (or be cancelled).
741 // Returns true if the thread is externally suspended and false otherwise.
742 //
743 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
744 uint32_t *bits) {
745 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
746 false /* !called_by_wait */, bits);
747
748 // local flag copies to minimize SR_lock hold time
749 bool is_suspended;
750 bool pending;
751 uint32_t reset_bits;
752
753 // set a marker so is_ext_suspend_completed() knows we are the caller
754 *bits |= 0x00010000;
755
756 // We use reset_bits to reinitialize the bits value at the top of
757 // each retry loop. This allows the caller to make use of any
758 // unused bits for their own marking purposes.
759 reset_bits = *bits;
760
761 {
762 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
763 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
764 delay, bits);
765 pending = is_external_suspend();
766 }
767 // must release SR_lock to allow suspension to complete
768
769 if (!pending) {
770 // A cancelled suspend request is the only false return from
771 // is_ext_suspend_completed() that keeps us from entering the
772 // retry loop.
773 *bits |= 0x00020000;
774 return false;
775 }
776
777 if (is_suspended) {
778 *bits |= 0x00040000;
779 return true;
780 }
781
782 for (int i = 1; i <= retries; i++) {
783 *bits = reset_bits; // reinit to only track last retry
784
785 // We used to do an "os::yield_all(i)" call here with the intention
786 // that yielding would increase on each retry. However, the parameter
787 // is ignored on Linux which means the yield didn't scale up. Waiting
788 // on the SR_lock below provides a much more predictable scale up for
789 // the delay. It also provides a simple/direct point to check for any
790 // safepoint requests from the VMThread
791
792 {
793 MutexLocker ml(SR_lock());
794 // wait with safepoint check (if we're a JavaThread - the WatcherThread
795 // can also call this) and increase delay with each retry
796 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
797
798 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
799 delay, bits);
800
801 // It is possible for the external suspend request to be cancelled
802 // (by a resume) before the actual suspend operation is completed.
803 // Refresh our local copy to see if we still need to wait.
804 pending = is_external_suspend();
805 }
806
807 if (!pending) {
808 // A cancelled suspend request is the only false return from
809 // is_ext_suspend_completed() that keeps us from staying in the
810 // retry loop.
811 *bits |= 0x00080000;
812 return false;
813 }
814
815 if (is_suspended) {
816 *bits |= 0x00100000;
817 return true;
818 }
819 } // end retry loop
820
821 // thread did not suspend after all our retries
822 *bits |= 0x00200000;
823 return false;
824 }
825
826 // Called from API entry points which perform stack walking. If the
827 // associated JavaThread is the current thread, then wait_for_suspend
828 // is not used. Otherwise, it determines if we should wait for the
829 // "other" thread to complete external suspension. (NOTE: in future
830 // releases the suspension mechanism should be reimplemented so this
831 // is not necessary.)
832 //
833 bool
834 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
835 if (this != JavaThread::current()) {
836 // "other" threads require special handling.
837 if (wait_for_suspend) {
838 // We are allowed to wait for the external suspend to complete
839 // so give the other thread a chance to get suspended.
840 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
841 SuspendRetryDelay, bits)) {
842 // Didn't make it so let the caller know.
843 return false;
844 }
845 }
846 // We aren't allowed to wait for the external suspend to complete
847 // so if the other thread isn't externally suspended we need to
848 // let the caller know.
849 else if (!is_ext_suspend_completed_with_lock(bits)) {
850 return false;
851 }
852 }
853
854 return true;
855 }
856
857 #ifndef PRODUCT
858 void JavaThread::record_jump(address target, address instr, const char* file,
859 int line) {
860
861 // This should not need to be atomic as the only way for simultaneous
862 // updates is via interrupts. Even then this should be rare or non-existent
863 // and we don't care that much anyway.
864
865 int index = _jmp_ring_index;
866 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
867 _jmp_ring[index]._target = (intptr_t) target;
868 _jmp_ring[index]._instruction = (intptr_t) instr;
869 _jmp_ring[index]._file = file;
870 _jmp_ring[index]._line = line;
871 }
872 #endif // PRODUCT
873
874 void Thread::interrupt(Thread* thread) {
875 debug_only(check_for_dangling_thread_pointer(thread);)
876 os::interrupt(thread);
877 }
878
879 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
880 debug_only(check_for_dangling_thread_pointer(thread);)
881 // Note: If clear_interrupted==false, this simply fetches and
882 // returns the value of the field osthread()->interrupted().
883 return os::is_interrupted(thread, clear_interrupted);
884 }
885
886
887 // GC Support
888 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
889 int thread_parity = _oops_do_parity;
890 if (thread_parity != strong_roots_parity) {
891 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
892 if (res == thread_parity) {
893 return true;
894 } else {
895 guarantee(res == strong_roots_parity, "Or else what?");
896 return false;
897 }
898 }
899 return false;
900 }
901
902 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
903 active_handles()->oops_do(f);
904 // Do oop for ThreadShadow
905 f->do_oop((oop*)&_pending_exception);
906 handle_area()->oops_do(f);
907
908 // We scan thread local monitor lists here, and the remaining global
909 // monitors in ObjectSynchronizer::oops_do().
910 ObjectSynchronizer::thread_local_used_oops_do(this, f);
911 }
912
913 void Thread::metadata_handles_do(void f(Metadata*)) {
914 // Only walk the Handles in Thread.
915 if (metadata_handles() != NULL) {
916 for (int i = 0; i< metadata_handles()->length(); i++) {
917 f(metadata_handles()->at(i));
918 }
919 }
920 }
921
922 void Thread::print_on(outputStream* st, bool print_extended_info) const {
923 // get_priority assumes osthread initialized
924 if (osthread() != NULL) {
925 int os_prio;
926 if (os::get_native_priority(this, &os_prio) == OS_OK) {
927 st->print("os_prio=%d ", os_prio);
928 }
929
930 st->print("cpu=%.2fms ",
931 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
932 );
933 st->print("elapsed=%.2fs ",
934 _statistical_info.getElapsedTime() / 1000.0
935 );
936 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
937 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
938 st->print("allocated=" SIZE_FORMAT "%s ",
939 byte_size_in_proper_unit(allocated_bytes),
940 proper_unit_for_byte_size(allocated_bytes)
941 );
942 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
943 }
944
945 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
946 osthread()->print_on(st);
947 }
948 ThreadsSMRSupport::print_info_on(this, st);
949 st->print(" ");
950 debug_only(if (WizardMode) print_owned_locks_on(st);)
951 }
952
953 // Thread::print_on_error() is called by fatal error handler. Don't use
954 // any lock or allocate memory.
955 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
956 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
957
958 if (is_VM_thread()) { st->print("VMThread"); }
959 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
960 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
961 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
962 else { st->print("Thread"); }
963
964 if (is_Named_thread()) {
965 st->print(" \"%s\"", name());
966 }
967
968 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
969 p2i(stack_end()), p2i(stack_base()));
970
971 if (osthread()) {
972 st->print(" [id=%d]", osthread()->thread_id());
973 }
974
975 ThreadsSMRSupport::print_info_on(this, st);
976 }
977
978 void Thread::print_value_on(outputStream* st) const {
979 if (is_Named_thread()) {
980 st->print(" \"%s\" ", name());
981 }
982 st->print(INTPTR_FORMAT, p2i(this)); // print address
983 }
984
985 #ifdef ASSERT
986 void Thread::print_owned_locks_on(outputStream* st) const {
987 Monitor *cur = _owned_locks;
988 if (cur == NULL) {
989 st->print(" (no locks) ");
990 } else {
991 st->print_cr(" Locks owned:");
992 while (cur) {
993 cur->print_on(st);
994 cur = cur->next();
995 }
996 }
997 }
998
999 static int ref_use_count = 0;
1000
1001 bool Thread::owns_locks_but_compiled_lock() const {
1002 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1003 if (cur != Compile_lock) return true;
1004 }
1005 return false;
1006 }
1007
1008
1009 #endif
1010
1011 #ifndef PRODUCT
1012
1013 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1014 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1015 // no locks which allow_vm_block's are held
1016 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1017 // Check if current thread is allowed to block at a safepoint
1018 if (!(_allow_safepoint_count == 0)) {
1019 fatal("Possible safepoint reached by thread that does not allow it");
1020 }
1021 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1022 fatal("LEAF method calling lock?");
1023 }
1024
1025 #ifdef ASSERT
1026 if (potential_vm_operation && is_Java_thread()
1027 && !Universe::is_bootstrapping()) {
1028 // Make sure we do not hold any locks that the VM thread also uses.
1029 // This could potentially lead to deadlocks
1030 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1031 // Threads_lock is special, since the safepoint synchronization will not start before this is
1032 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1033 // since it is used to transfer control between JavaThreads and the VMThread
1034 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1035 if ((cur->allow_vm_block() &&
1036 cur != Threads_lock &&
1037 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1038 cur != VMOperationRequest_lock &&
1039 cur != VMOperationQueue_lock) ||
1040 cur->rank() == Mutex::special) {
1041 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1042 }
1043 }
1044 }
1045
1046 if (GCALotAtAllSafepoints) {
1047 // We could enter a safepoint here and thus have a gc
1048 InterfaceSupport::check_gc_alot();
1049 }
1050 #endif
1051 }
1052 #endif
1053
1054 bool Thread::is_in_stack(address adr) const {
1055 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1056 address end = os::current_stack_pointer();
1057 // Allow non Java threads to call this without stack_base
1058 if (_stack_base == NULL) return true;
1059 if (stack_base() >= adr && adr >= end) return true;
1060
1061 return false;
1062 }
1063
1064 bool Thread::is_in_usable_stack(address adr) const {
1065 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1066 size_t usable_stack_size = _stack_size - stack_guard_size;
1067
1068 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1069 }
1070
1071
1072 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1073 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1074 // used for compilation in the future. If that change is made, the need for these methods
1075 // should be revisited, and they should be removed if possible.
1076
1077 bool Thread::is_lock_owned(address adr) const {
1078 return on_local_stack(adr);
1079 }
1080
1081 bool Thread::set_as_starting_thread() {
1082 assert(_starting_thread == NULL, "already initialized: "
1083 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1084 // NOTE: this must be called inside the main thread.
1085 DEBUG_ONLY(_starting_thread = this;)
1086 return os::create_main_thread((JavaThread*)this);
1087 }
1088
1089 static void initialize_class(Symbol* class_name, TRAPS) {
1090 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1091 InstanceKlass::cast(klass)->initialize(CHECK);
1092 }
1093
1094
1095 // Creates the initial ThreadGroup
1096 static Handle create_initial_thread_group(TRAPS) {
1097 Handle system_instance = JavaCalls::construct_new_instance(
1098 SystemDictionary::ThreadGroup_klass(),
1099 vmSymbols::void_method_signature(),
1100 CHECK_NH);
1101 Universe::set_system_thread_group(system_instance());
1102
1103 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1104 Handle main_instance = JavaCalls::construct_new_instance(
1105 SystemDictionary::ThreadGroup_klass(),
1106 vmSymbols::threadgroup_string_void_signature(),
1107 system_instance,
1108 string,
1109 CHECK_NH);
1110 return main_instance;
1111 }
1112
1113 // Creates the initial Thread
1114 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1115 TRAPS) {
1116 InstanceKlass* ik = SystemDictionary::Thread_klass();
1117 assert(ik->is_initialized(), "must be");
1118 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1119
1120 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1121 // constructor calls Thread.current(), which must be set here for the
1122 // initial thread.
1123 java_lang_Thread::set_thread(thread_oop(), thread);
1124 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1125 thread->set_threadObj(thread_oop());
1126
1127 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1128
1129 JavaValue result(T_VOID);
1130 JavaCalls::call_special(&result, thread_oop,
1131 ik,
1132 vmSymbols::object_initializer_name(),
1133 vmSymbols::threadgroup_string_void_signature(),
1134 thread_group,
1135 string,
1136 CHECK_NULL);
1137 return thread_oop();
1138 }
1139
1140 char java_runtime_name[128] = "";
1141 char java_runtime_version[128] = "";
1142
1143 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1144 static const char* get_java_runtime_name(TRAPS) {
1145 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1146 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1147 fieldDescriptor fd;
1148 bool found = k != NULL &&
1149 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1150 vmSymbols::string_signature(), &fd);
1151 if (found) {
1152 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1153 if (name_oop == NULL) {
1154 return NULL;
1155 }
1156 const char* name = java_lang_String::as_utf8_string(name_oop,
1157 java_runtime_name,
1158 sizeof(java_runtime_name));
1159 return name;
1160 } else {
1161 return NULL;
1162 }
1163 }
1164
1165 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1166 static const char* get_java_runtime_version(TRAPS) {
1167 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1168 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1169 fieldDescriptor fd;
1170 bool found = k != NULL &&
1171 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1172 vmSymbols::string_signature(), &fd);
1173 if (found) {
1174 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1175 if (name_oop == NULL) {
1176 return NULL;
1177 }
1178 const char* name = java_lang_String::as_utf8_string(name_oop,
1179 java_runtime_version,
1180 sizeof(java_runtime_version));
1181 return name;
1182 } else {
1183 return NULL;
1184 }
1185 }
1186
1187 // General purpose hook into Java code, run once when the VM is initialized.
1188 // The Java library method itself may be changed independently from the VM.
1189 static void call_postVMInitHook(TRAPS) {
1190 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1191 if (klass != NULL) {
1192 JavaValue result(T_VOID);
1193 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1194 vmSymbols::void_method_signature(),
1195 CHECK);
1196 }
1197 }
1198
1199 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1200 bool daemon, TRAPS) {
1201 assert(thread_group.not_null(), "thread group should be specified");
1202 assert(threadObj() == NULL, "should only create Java thread object once");
1203
1204 InstanceKlass* ik = SystemDictionary::Thread_klass();
1205 assert(ik->is_initialized(), "must be");
1206 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1207
1208 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1209 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1210 // constructor calls Thread.current(), which must be set here.
1211 java_lang_Thread::set_thread(thread_oop(), this);
1212 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1213 set_threadObj(thread_oop());
1214
1215 JavaValue result(T_VOID);
1216 if (thread_name != NULL) {
1217 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1218 // Thread gets assigned specified name and null target
1219 JavaCalls::call_special(&result,
1220 thread_oop,
1221 ik,
1222 vmSymbols::object_initializer_name(),
1223 vmSymbols::threadgroup_string_void_signature(),
1224 thread_group,
1225 name,
1226 THREAD);
1227 } else {
1228 // Thread gets assigned name "Thread-nnn" and null target
1229 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1230 JavaCalls::call_special(&result,
1231 thread_oop,
1232 ik,
1233 vmSymbols::object_initializer_name(),
1234 vmSymbols::threadgroup_runnable_void_signature(),
1235 thread_group,
1236 Handle(),
1237 THREAD);
1238 }
1239
1240
1241 if (daemon) {
1242 java_lang_Thread::set_daemon(thread_oop());
1243 }
1244
1245 if (HAS_PENDING_EXCEPTION) {
1246 return;
1247 }
1248
1249 Klass* group = SystemDictionary::ThreadGroup_klass();
1250 Handle threadObj(THREAD, this->threadObj());
1251
1252 JavaCalls::call_special(&result,
1253 thread_group,
1254 group,
1255 vmSymbols::add_method_name(),
1256 vmSymbols::thread_void_signature(),
1257 threadObj, // Arg 1
1258 THREAD);
1259 }
1260
1261 // List of all NonJavaThreads and safe iteration over that list.
1262
1263 class NonJavaThread::List {
1264 public:
1265 NonJavaThread* volatile _head;
1266 SingleWriterSynchronizer _protect;
1267
1268 List() : _head(NULL), _protect() {}
1269 };
1270
1271 NonJavaThread::List NonJavaThread::_the_list;
1272
1273 NonJavaThread::Iterator::Iterator() :
1274 _protect_enter(_the_list._protect.enter()),
1275 _current(OrderAccess::load_acquire(&_the_list._head))
1276 {}
1277
1278 NonJavaThread::Iterator::~Iterator() {
1279 _the_list._protect.exit(_protect_enter);
1280 }
1281
1282 void NonJavaThread::Iterator::step() {
1283 assert(!end(), "precondition");
1284 _current = OrderAccess::load_acquire(&_current->_next);
1285 }
1286
1287 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1288 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1289 }
1290
1291 NonJavaThread::~NonJavaThread() { }
1292
1293 void NonJavaThread::add_to_the_list() {
1294 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1295 _next = _the_list._head;
1296 OrderAccess::release_store(&_the_list._head, this);
1297 }
1298
1299 void NonJavaThread::remove_from_the_list() {
1300 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1301 NonJavaThread* volatile* p = &_the_list._head;
1302 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1303 if (t == this) {
1304 *p = this->_next;
1305 // Wait for any in-progress iterators. Concurrent synchronize is
1306 // not allowed, so do it while holding the list lock.
1307 _the_list._protect.synchronize();
1308 break;
1309 }
1310 }
1311 }
1312
1313 void NonJavaThread::pre_run() {
1314 // Initialize BarrierSet-related data before adding to list.
1315 assert(BarrierSet::barrier_set() != NULL, "invariant");
1316 BarrierSet::barrier_set()->on_thread_attach(this);
1317 add_to_the_list();
1318
1319 // This is slightly odd in that NamedThread is a subclass, but
1320 // in fact name() is defined in Thread
1321 assert(this->name() != NULL, "thread name was not set before it was started");
1322 this->set_native_thread_name(this->name());
1323 }
1324
1325 void NonJavaThread::post_run() {
1326 JFR_ONLY(Jfr::on_thread_exit(this);)
1327 // Clean up BarrierSet data before removing from list.
1328 BarrierSet::barrier_set()->on_thread_detach(this);
1329 remove_from_the_list();
1330 // Ensure thread-local-storage is cleared before termination.
1331 Thread::clear_thread_current();
1332 }
1333
1334 // NamedThread -- non-JavaThread subclasses with multiple
1335 // uniquely named instances should derive from this.
1336 NamedThread::NamedThread() :
1337 NonJavaThread(),
1338 _name(NULL),
1339 _processed_thread(NULL),
1340 _gc_id(GCId::undefined())
1341 {}
1342
1343 NamedThread::~NamedThread() {
1344 if (_name != NULL) {
1345 FREE_C_HEAP_ARRAY(char, _name);
1346 _name = NULL;
1347 }
1348 }
1349
1350 void NamedThread::set_name(const char* format, ...) {
1351 guarantee(_name == NULL, "Only get to set name once.");
1352 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1353 guarantee(_name != NULL, "alloc failure");
1354 va_list ap;
1355 va_start(ap, format);
1356 jio_vsnprintf(_name, max_name_len, format, ap);
1357 va_end(ap);
1358 }
1359
1360 void NamedThread::print_on(outputStream* st) const {
1361 st->print("\"%s\" ", name());
1362 Thread::print_on(st);
1363 st->cr();
1364 }
1365
1366
1367 // ======= WatcherThread ========
1368
1369 // The watcher thread exists to simulate timer interrupts. It should
1370 // be replaced by an abstraction over whatever native support for
1371 // timer interrupts exists on the platform.
1372
1373 WatcherThread* WatcherThread::_watcher_thread = NULL;
1374 bool WatcherThread::_startable = false;
1375 volatile bool WatcherThread::_should_terminate = false;
1376
1377 WatcherThread::WatcherThread() : NonJavaThread() {
1378 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1379 if (os::create_thread(this, os::watcher_thread)) {
1380 _watcher_thread = this;
1381
1382 // Set the watcher thread to the highest OS priority which should not be
1383 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1384 // is created. The only normal thread using this priority is the reference
1385 // handler thread, which runs for very short intervals only.
1386 // If the VMThread's priority is not lower than the WatcherThread profiling
1387 // will be inaccurate.
1388 os::set_priority(this, MaxPriority);
1389 if (!DisableStartThread) {
1390 os::start_thread(this);
1391 }
1392 }
1393 }
1394
1395 int WatcherThread::sleep() const {
1396 // The WatcherThread does not participate in the safepoint protocol
1397 // for the PeriodicTask_lock because it is not a JavaThread.
1398 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1399
1400 if (_should_terminate) {
1401 // check for termination before we do any housekeeping or wait
1402 return 0; // we did not sleep.
1403 }
1404
1405 // remaining will be zero if there are no tasks,
1406 // causing the WatcherThread to sleep until a task is
1407 // enrolled
1408 int remaining = PeriodicTask::time_to_wait();
1409 int time_slept = 0;
1410
1411 // we expect this to timeout - we only ever get unparked when
1412 // we should terminate or when a new task has been enrolled
1413 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1414
1415 jlong time_before_loop = os::javaTimeNanos();
1416
1417 while (true) {
1418 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1419 remaining);
1420 jlong now = os::javaTimeNanos();
1421
1422 if (remaining == 0) {
1423 // if we didn't have any tasks we could have waited for a long time
1424 // consider the time_slept zero and reset time_before_loop
1425 time_slept = 0;
1426 time_before_loop = now;
1427 } else {
1428 // need to recalculate since we might have new tasks in _tasks
1429 time_slept = (int) ((now - time_before_loop) / 1000000);
1430 }
1431
1432 // Change to task list or spurious wakeup of some kind
1433 if (timedout || _should_terminate) {
1434 break;
1435 }
1436
1437 remaining = PeriodicTask::time_to_wait();
1438 if (remaining == 0) {
1439 // Last task was just disenrolled so loop around and wait until
1440 // another task gets enrolled
1441 continue;
1442 }
1443
1444 remaining -= time_slept;
1445 if (remaining <= 0) {
1446 break;
1447 }
1448 }
1449
1450 return time_slept;
1451 }
1452
1453 void WatcherThread::run() {
1454 assert(this == watcher_thread(), "just checking");
1455
1456 this->set_active_handles(JNIHandleBlock::allocate_block());
1457 while (true) {
1458 assert(watcher_thread() == Thread::current(), "thread consistency check");
1459 assert(watcher_thread() == this, "thread consistency check");
1460
1461 // Calculate how long it'll be until the next PeriodicTask work
1462 // should be done, and sleep that amount of time.
1463 int time_waited = sleep();
1464
1465 if (VMError::is_error_reported()) {
1466 // A fatal error has happened, the error handler(VMError::report_and_die)
1467 // should abort JVM after creating an error log file. However in some
1468 // rare cases, the error handler itself might deadlock. Here periodically
1469 // check for error reporting timeouts, and if it happens, just proceed to
1470 // abort the VM.
1471
1472 // This code is in WatcherThread because WatcherThread wakes up
1473 // periodically so the fatal error handler doesn't need to do anything;
1474 // also because the WatcherThread is less likely to crash than other
1475 // threads.
1476
1477 for (;;) {
1478 // Note: we use naked sleep in this loop because we want to avoid using
1479 // any kind of VM infrastructure which may be broken at this point.
1480 if (VMError::check_timeout()) {
1481 // We hit error reporting timeout. Error reporting was interrupted and
1482 // will be wrapping things up now (closing files etc). Give it some more
1483 // time, then quit the VM.
1484 os::naked_short_sleep(200);
1485 // Print a message to stderr.
1486 fdStream err(defaultStream::output_fd());
1487 err.print_raw_cr("# [ timer expired, abort... ]");
1488 // skip atexit/vm_exit/vm_abort hooks
1489 os::die();
1490 }
1491
1492 // Wait a second, then recheck for timeout.
1493 os::naked_short_sleep(999);
1494 }
1495 }
1496
1497 if (_should_terminate) {
1498 // check for termination before posting the next tick
1499 break;
1500 }
1501
1502 PeriodicTask::real_time_tick(time_waited);
1503 }
1504
1505 // Signal that it is terminated
1506 {
1507 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1508 _watcher_thread = NULL;
1509 Terminator_lock->notify_all();
1510 }
1511 }
1512
1513 void WatcherThread::start() {
1514 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1515
1516 if (watcher_thread() == NULL && _startable) {
1517 _should_terminate = false;
1518 // Create the single instance of WatcherThread
1519 new WatcherThread();
1520 }
1521 }
1522
1523 void WatcherThread::make_startable() {
1524 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1525 _startable = true;
1526 }
1527
1528 void WatcherThread::stop() {
1529 {
1530 // Follow normal safepoint aware lock enter protocol since the
1531 // WatcherThread is stopped by another JavaThread.
1532 MutexLocker ml(PeriodicTask_lock);
1533 _should_terminate = true;
1534
1535 WatcherThread* watcher = watcher_thread();
1536 if (watcher != NULL) {
1537 // unpark the WatcherThread so it can see that it should terminate
1538 watcher->unpark();
1539 }
1540 }
1541
1542 MutexLocker mu(Terminator_lock);
1543
1544 while (watcher_thread() != NULL) {
1545 // This wait should make safepoint checks, wait without a timeout,
1546 // and wait as a suspend-equivalent condition.
1547 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1548 Mutex::_as_suspend_equivalent_flag);
1549 }
1550 }
1551
1552 void WatcherThread::unpark() {
1553 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1554 PeriodicTask_lock->notify();
1555 }
1556
1557 void WatcherThread::print_on(outputStream* st) const {
1558 st->print("\"%s\" ", name());
1559 Thread::print_on(st);
1560 st->cr();
1561 }
1562
1563 // ======= JavaThread ========
1564
1565 #if INCLUDE_JVMCI
1566
1567 jlong* JavaThread::_jvmci_old_thread_counters;
1568
1569 bool jvmci_counters_include(JavaThread* thread) {
1570 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1571 }
1572
1573 void JavaThread::collect_counters(typeArrayOop array) {
1574 if (JVMCICounterSize > 0) {
1575 JavaThreadIteratorWithHandle jtiwh;
1576 for (int i = 0; i < array->length(); i++) {
1577 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1578 }
1579 for (; JavaThread *tp = jtiwh.next(); ) {
1580 if (jvmci_counters_include(tp)) {
1581 for (int i = 0; i < array->length(); i++) {
1582 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1583 }
1584 }
1585 }
1586 }
1587 }
1588
1589 #endif // INCLUDE_JVMCI
1590
1591 // A JavaThread is a normal Java thread
1592
1593 void JavaThread::initialize() {
1594 // Initialize fields
1595
1596 set_saved_exception_pc(NULL);
1597 set_threadObj(NULL);
1598 _anchor.clear();
1599 set_entry_point(NULL);
1600 set_jni_functions(jni_functions());
1601 set_callee_target(NULL);
1602 set_vm_result(NULL);
1603 set_vm_result_2(NULL);
1604 set_vframe_array_head(NULL);
1605 set_vframe_array_last(NULL);
1606 set_deferred_locals(NULL);
1607 set_deopt_mark(NULL);
1608 set_deopt_compiled_method(NULL);
1609 clear_must_deopt_id();
1610 set_monitor_chunks(NULL);
1611 set_next(NULL);
1612 _on_thread_list = false;
1613 set_thread_state(_thread_new);
1614 _terminated = _not_terminated;
1615 _array_for_gc = NULL;
1616 _suspend_equivalent = false;
1617 _in_deopt_handler = 0;
1618 _doing_unsafe_access = false;
1619 _stack_guard_state = stack_guard_unused;
1620 #if INCLUDE_JVMCI
1621 _pending_monitorenter = false;
1622 _pending_deoptimization = -1;
1623 _pending_failed_speculation = 0;
1624 _pending_transfer_to_interpreter = false;
1625 _adjusting_comp_level = false;
1626 _in_retryable_allocation = false;
1627 _jvmci._alternate_call_target = NULL;
1628 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1629 if (JVMCICounterSize > 0) {
1630 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1631 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1632 } else {
1633 _jvmci_counters = NULL;
1634 }
1635 #endif // INCLUDE_JVMCI
1636 _reserved_stack_activation = NULL; // stack base not known yet
1637 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1638 _exception_pc = 0;
1639 _exception_handler_pc = 0;
1640 _is_method_handle_return = 0;
1641 _jvmti_thread_state= NULL;
1642 _should_post_on_exceptions_flag = JNI_FALSE;
1643 _interp_only_mode = 0;
1644 _special_runtime_exit_condition = _no_async_condition;
1645 _pending_async_exception = NULL;
1646 _thread_stat = NULL;
1647 _thread_stat = new ThreadStatistics();
1648 _blocked_on_compilation = false;
1649 _jni_active_critical = 0;
1650 _pending_jni_exception_check_fn = NULL;
1651 _do_not_unlock_if_synchronized = false;
1652 _cached_monitor_info = NULL;
1653 _parker = Parker::Allocate(this);
1654
1655 #ifndef PRODUCT
1656 _jmp_ring_index = 0;
1657 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1658 record_jump(NULL, NULL, NULL, 0);
1659 }
1660 #endif // PRODUCT
1661
1662 // Setup safepoint state info for this thread
1663 ThreadSafepointState::create(this);
1664
1665 debug_only(_java_call_counter = 0);
1666
1667 // JVMTI PopFrame support
1668 _popframe_condition = popframe_inactive;
1669 _popframe_preserved_args = NULL;
1670 _popframe_preserved_args_size = 0;
1671 _frames_to_pop_failed_realloc = 0;
1672
1673 if (SafepointMechanism::uses_thread_local_poll()) {
1674 SafepointMechanism::initialize_header(this);
1675 }
1676
1677 _class_to_be_initialized = NULL;
1678
1679 pd_initialize();
1680 }
1681
1682 JavaThread::JavaThread(bool is_attaching_via_jni) :
1683 Thread() {
1684 initialize();
1685 if (is_attaching_via_jni) {
1686 _jni_attach_state = _attaching_via_jni;
1687 } else {
1688 _jni_attach_state = _not_attaching_via_jni;
1689 }
1690 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1691 }
1692
1693 bool JavaThread::reguard_stack(address cur_sp) {
1694 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1695 && _stack_guard_state != stack_guard_reserved_disabled) {
1696 return true; // Stack already guarded or guard pages not needed.
1697 }
1698
1699 if (register_stack_overflow()) {
1700 // For those architectures which have separate register and
1701 // memory stacks, we must check the register stack to see if
1702 // it has overflowed.
1703 return false;
1704 }
1705
1706 // Java code never executes within the yellow zone: the latter is only
1707 // there to provoke an exception during stack banging. If java code
1708 // is executing there, either StackShadowPages should be larger, or
1709 // some exception code in c1, c2 or the interpreter isn't unwinding
1710 // when it should.
1711 guarantee(cur_sp > stack_reserved_zone_base(),
1712 "not enough space to reguard - increase StackShadowPages");
1713 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1714 enable_stack_yellow_reserved_zone();
1715 if (reserved_stack_activation() != stack_base()) {
1716 set_reserved_stack_activation(stack_base());
1717 }
1718 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1719 set_reserved_stack_activation(stack_base());
1720 enable_stack_reserved_zone();
1721 }
1722 return true;
1723 }
1724
1725 bool JavaThread::reguard_stack(void) {
1726 return reguard_stack(os::current_stack_pointer());
1727 }
1728
1729
1730 void JavaThread::block_if_vm_exited() {
1731 if (_terminated == _vm_exited) {
1732 // _vm_exited is set at safepoint, and Threads_lock is never released
1733 // we will block here forever
1734 Threads_lock->lock_without_safepoint_check();
1735 ShouldNotReachHere();
1736 }
1737 }
1738
1739
1740 // Remove this ifdef when C1 is ported to the compiler interface.
1741 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1742 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1743
1744 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1745 Thread() {
1746 initialize();
1747 _jni_attach_state = _not_attaching_via_jni;
1748 set_entry_point(entry_point);
1749 // Create the native thread itself.
1750 // %note runtime_23
1751 os::ThreadType thr_type = os::java_thread;
1752 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1753 os::java_thread;
1754 os::create_thread(this, thr_type, stack_sz);
1755 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1756 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1757 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1758 // the exception consists of creating the exception object & initializing it, initialization
1759 // will leave the VM via a JavaCall and then all locks must be unlocked).
1760 //
1761 // The thread is still suspended when we reach here. Thread must be explicit started
1762 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1763 // by calling Threads:add. The reason why this is not done here, is because the thread
1764 // object must be fully initialized (take a look at JVM_Start)
1765 }
1766
1767 JavaThread::~JavaThread() {
1768
1769 // JSR166 -- return the parker to the free list
1770 Parker::Release(_parker);
1771 _parker = NULL;
1772
1773 // Free any remaining previous UnrollBlock
1774 vframeArray* old_array = vframe_array_last();
1775
1776 if (old_array != NULL) {
1777 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1778 old_array->set_unroll_block(NULL);
1779 delete old_info;
1780 delete old_array;
1781 }
1782
1783 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1784 if (deferred != NULL) {
1785 // This can only happen if thread is destroyed before deoptimization occurs.
1786 assert(deferred->length() != 0, "empty array!");
1787 do {
1788 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1789 deferred->remove_at(0);
1790 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1791 delete dlv;
1792 } while (deferred->length() != 0);
1793 delete deferred;
1794 }
1795
1796 // All Java related clean up happens in exit
1797 ThreadSafepointState::destroy(this);
1798 if (_thread_stat != NULL) delete _thread_stat;
1799
1800 #if INCLUDE_JVMCI
1801 if (JVMCICounterSize > 0) {
1802 if (jvmci_counters_include(this)) {
1803 for (int i = 0; i < JVMCICounterSize; i++) {
1804 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1805 }
1806 }
1807 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1808 }
1809 #endif // INCLUDE_JVMCI
1810 }
1811
1812
1813 // First JavaThread specific code executed by a new Java thread.
1814 void JavaThread::pre_run() {
1815 // empty - see comments in run()
1816 }
1817
1818 // The main routine called by a new Java thread. This isn't overridden
1819 // by subclasses, instead different subclasses define a different "entry_point"
1820 // which defines the actual logic for that kind of thread.
1821 void JavaThread::run() {
1822 // initialize thread-local alloc buffer related fields
1823 this->initialize_tlab();
1824
1825 // Used to test validity of stack trace backs.
1826 // This can't be moved into pre_run() else we invalidate
1827 // the requirement that thread_main_inner is lower on
1828 // the stack. Consequently all the initialization logic
1829 // stays here in run() rather than pre_run().
1830 this->record_base_of_stack_pointer();
1831
1832 this->create_stack_guard_pages();
1833
1834 this->cache_global_variables();
1835
1836 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1837 // in the VM. Change thread state from _thread_new to _thread_in_vm
1838 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1839
1840 assert(JavaThread::current() == this, "sanity check");
1841 assert(!Thread::current()->owns_locks(), "sanity check");
1842
1843 DTRACE_THREAD_PROBE(start, this);
1844
1845 // This operation might block. We call that after all safepoint checks for a new thread has
1846 // been completed.
1847 this->set_active_handles(JNIHandleBlock::allocate_block());
1848
1849 if (JvmtiExport::should_post_thread_life()) {
1850 JvmtiExport::post_thread_start(this);
1851
1852 }
1853
1854 // We call another function to do the rest so we are sure that the stack addresses used
1855 // from there will be lower than the stack base just computed.
1856 thread_main_inner();
1857 }
1858
1859 void JavaThread::thread_main_inner() {
1860 assert(JavaThread::current() == this, "sanity check");
1861 assert(this->threadObj() != NULL, "just checking");
1862
1863 // Execute thread entry point unless this thread has a pending exception
1864 // or has been stopped before starting.
1865 // Note: Due to JVM_StopThread we can have pending exceptions already!
1866 if (!this->has_pending_exception() &&
1867 !java_lang_Thread::is_stillborn(this->threadObj())) {
1868 {
1869 ResourceMark rm(this);
1870 this->set_native_thread_name(this->get_thread_name());
1871 }
1872 HandleMark hm(this);
1873 this->entry_point()(this, this);
1874 }
1875
1876 DTRACE_THREAD_PROBE(stop, this);
1877
1878 // Cleanup is handled in post_run()
1879 }
1880
1881 // Shared teardown for all JavaThreads
1882 void JavaThread::post_run() {
1883 this->exit(false);
1884 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1885 // for any shared tear-down.
1886 this->smr_delete();
1887 }
1888
1889 static void ensure_join(JavaThread* thread) {
1890 // We do not need to grab the Threads_lock, since we are operating on ourself.
1891 Handle threadObj(thread, thread->threadObj());
1892 assert(threadObj.not_null(), "java thread object must exist");
1893 ObjectLocker lock(threadObj, thread);
1894 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1895 thread->clear_pending_exception();
1896 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1897 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1898 // Clear the native thread instance - this makes isAlive return false and allows the join()
1899 // to complete once we've done the notify_all below
1900 java_lang_Thread::set_thread(threadObj(), NULL);
1901 lock.notify_all(thread);
1902 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1903 thread->clear_pending_exception();
1904 }
1905
1906 static bool is_daemon(oop threadObj) {
1907 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1908 }
1909
1910 // For any new cleanup additions, please check to see if they need to be applied to
1911 // cleanup_failed_attach_current_thread as well.
1912 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1913 assert(this == JavaThread::current(), "thread consistency check");
1914
1915 elapsedTimer _timer_exit_phase1;
1916 elapsedTimer _timer_exit_phase2;
1917 elapsedTimer _timer_exit_phase3;
1918 elapsedTimer _timer_exit_phase4;
1919
1920 if (log_is_enabled(Debug, os, thread, timer)) {
1921 _timer_exit_phase1.start();
1922 }
1923
1924 HandleMark hm(this);
1925 Handle uncaught_exception(this, this->pending_exception());
1926 this->clear_pending_exception();
1927 Handle threadObj(this, this->threadObj());
1928 assert(threadObj.not_null(), "Java thread object should be created");
1929
1930 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1931 {
1932 EXCEPTION_MARK;
1933
1934 CLEAR_PENDING_EXCEPTION;
1935 }
1936 if (!destroy_vm) {
1937 if (uncaught_exception.not_null()) {
1938 EXCEPTION_MARK;
1939 // Call method Thread.dispatchUncaughtException().
1940 Klass* thread_klass = SystemDictionary::Thread_klass();
1941 JavaValue result(T_VOID);
1942 JavaCalls::call_virtual(&result,
1943 threadObj, thread_klass,
1944 vmSymbols::dispatchUncaughtException_name(),
1945 vmSymbols::throwable_void_signature(),
1946 uncaught_exception,
1947 THREAD);
1948 if (HAS_PENDING_EXCEPTION) {
1949 ResourceMark rm(this);
1950 jio_fprintf(defaultStream::error_stream(),
1951 "\nException: %s thrown from the UncaughtExceptionHandler"
1952 " in thread \"%s\"\n",
1953 pending_exception()->klass()->external_name(),
1954 get_thread_name());
1955 CLEAR_PENDING_EXCEPTION;
1956 }
1957 }
1958 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1959
1960 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1961 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1962 // is deprecated anyhow.
1963 if (!is_Compiler_thread()) {
1964 int count = 3;
1965 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1966 EXCEPTION_MARK;
1967 JavaValue result(T_VOID);
1968 Klass* thread_klass = SystemDictionary::Thread_klass();
1969 JavaCalls::call_virtual(&result,
1970 threadObj, thread_klass,
1971 vmSymbols::exit_method_name(),
1972 vmSymbols::void_method_signature(),
1973 THREAD);
1974 CLEAR_PENDING_EXCEPTION;
1975 }
1976 }
1977 // notify JVMTI
1978 if (JvmtiExport::should_post_thread_life()) {
1979 JvmtiExport::post_thread_end(this);
1980 }
1981
1982 // We have notified the agents that we are exiting, before we go on,
1983 // we must check for a pending external suspend request and honor it
1984 // in order to not surprise the thread that made the suspend request.
1985 while (true) {
1986 {
1987 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1988 if (!is_external_suspend()) {
1989 set_terminated(_thread_exiting);
1990 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1991 break;
1992 }
1993 // Implied else:
1994 // Things get a little tricky here. We have a pending external
1995 // suspend request, but we are holding the SR_lock so we
1996 // can't just self-suspend. So we temporarily drop the lock
1997 // and then self-suspend.
1998 }
1999
2000 ThreadBlockInVM tbivm(this);
2001 java_suspend_self();
2002
2003 // We're done with this suspend request, but we have to loop around
2004 // and check again. Eventually we will get SR_lock without a pending
2005 // external suspend request and will be able to mark ourselves as
2006 // exiting.
2007 }
2008 // no more external suspends are allowed at this point
2009 } else {
2010 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2011 // before_exit() has already posted JVMTI THREAD_END events
2012 }
2013
2014 if (log_is_enabled(Debug, os, thread, timer)) {
2015 _timer_exit_phase1.stop();
2016 _timer_exit_phase2.start();
2017 }
2018 // Notify waiters on thread object. This has to be done after exit() is called
2019 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2020 // group should have the destroyed bit set before waiters are notified).
2021 ensure_join(this);
2022 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2023
2024 if (log_is_enabled(Debug, os, thread, timer)) {
2025 _timer_exit_phase2.stop();
2026 _timer_exit_phase3.start();
2027 }
2028 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2029 // held by this thread must be released. The spec does not distinguish
2030 // between JNI-acquired and regular Java monitors. We can only see
2031 // regular Java monitors here if monitor enter-exit matching is broken.
2032 //
2033 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2034 // ObjectSynchronizer::release_monitors_owned_by_thread().
2035 if (exit_type == jni_detach) {
2036 // Sanity check even though JNI DetachCurrentThread() would have
2037 // returned JNI_ERR if there was a Java frame. JavaThread exit
2038 // should be done executing Java code by the time we get here.
2039 assert(!this->has_last_Java_frame(),
2040 "should not have a Java frame when detaching or exiting");
2041 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2042 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2043 }
2044
2045 // These things needs to be done while we are still a Java Thread. Make sure that thread
2046 // is in a consistent state, in case GC happens
2047 JFR_ONLY(Jfr::on_thread_exit(this);)
2048
2049 if (active_handles() != NULL) {
2050 JNIHandleBlock* block = active_handles();
2051 set_active_handles(NULL);
2052 JNIHandleBlock::release_block(block);
2053 }
2054
2055 if (free_handle_block() != NULL) {
2056 JNIHandleBlock* block = free_handle_block();
2057 set_free_handle_block(NULL);
2058 JNIHandleBlock::release_block(block);
2059 }
2060
2061 // These have to be removed while this is still a valid thread.
2062 remove_stack_guard_pages();
2063
2064 if (UseTLAB) {
2065 tlab().retire();
2066 }
2067
2068 if (JvmtiEnv::environments_might_exist()) {
2069 JvmtiExport::cleanup_thread(this);
2070 }
2071
2072 // We must flush any deferred card marks and other various GC barrier
2073 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2074 // before removing a thread from the list of active threads.
2075 BarrierSet::barrier_set()->on_thread_detach(this);
2076
2077 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2078 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2079 os::current_thread_id());
2080
2081 if (log_is_enabled(Debug, os, thread, timer)) {
2082 _timer_exit_phase3.stop();
2083 _timer_exit_phase4.start();
2084 }
2085 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2086 Threads::remove(this);
2087
2088 if (log_is_enabled(Debug, os, thread, timer)) {
2089 _timer_exit_phase4.stop();
2090 ResourceMark rm(this);
2091 log_debug(os, thread, timer)("name='%s'"
2092 ", exit-phase1=" JLONG_FORMAT
2093 ", exit-phase2=" JLONG_FORMAT
2094 ", exit-phase3=" JLONG_FORMAT
2095 ", exit-phase4=" JLONG_FORMAT,
2096 get_thread_name(),
2097 _timer_exit_phase1.milliseconds(),
2098 _timer_exit_phase2.milliseconds(),
2099 _timer_exit_phase3.milliseconds(),
2100 _timer_exit_phase4.milliseconds());
2101 }
2102 }
2103
2104 void JavaThread::cleanup_failed_attach_current_thread() {
2105 if (active_handles() != NULL) {
2106 JNIHandleBlock* block = active_handles();
2107 set_active_handles(NULL);
2108 JNIHandleBlock::release_block(block);
2109 }
2110
2111 if (free_handle_block() != NULL) {
2112 JNIHandleBlock* block = free_handle_block();
2113 set_free_handle_block(NULL);
2114 JNIHandleBlock::release_block(block);
2115 }
2116
2117 // These have to be removed while this is still a valid thread.
2118 remove_stack_guard_pages();
2119
2120 if (UseTLAB) {
2121 tlab().retire();
2122 }
2123
2124 BarrierSet::barrier_set()->on_thread_detach(this);
2125
2126 Threads::remove(this);
2127 this->smr_delete();
2128 }
2129
2130 JavaThread* JavaThread::active() {
2131 Thread* thread = Thread::current();
2132 if (thread->is_Java_thread()) {
2133 return (JavaThread*) thread;
2134 } else {
2135 assert(thread->is_VM_thread(), "this must be a vm thread");
2136 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2137 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2138 assert(ret->is_Java_thread(), "must be a Java thread");
2139 return ret;
2140 }
2141 }
2142
2143 bool JavaThread::is_lock_owned(address adr) const {
2144 if (Thread::is_lock_owned(adr)) return true;
2145
2146 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2147 if (chunk->contains(adr)) return true;
2148 }
2149
2150 return false;
2151 }
2152
2153
2154 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2155 chunk->set_next(monitor_chunks());
2156 set_monitor_chunks(chunk);
2157 }
2158
2159 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2160 guarantee(monitor_chunks() != NULL, "must be non empty");
2161 if (monitor_chunks() == chunk) {
2162 set_monitor_chunks(chunk->next());
2163 } else {
2164 MonitorChunk* prev = monitor_chunks();
2165 while (prev->next() != chunk) prev = prev->next();
2166 prev->set_next(chunk->next());
2167 }
2168 }
2169
2170 // JVM support.
2171
2172 // Note: this function shouldn't block if it's called in
2173 // _thread_in_native_trans state (such as from
2174 // check_special_condition_for_native_trans()).
2175 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2176
2177 if (has_last_Java_frame() && has_async_condition()) {
2178 // If we are at a polling page safepoint (not a poll return)
2179 // then we must defer async exception because live registers
2180 // will be clobbered by the exception path. Poll return is
2181 // ok because the call we a returning from already collides
2182 // with exception handling registers and so there is no issue.
2183 // (The exception handling path kills call result registers but
2184 // this is ok since the exception kills the result anyway).
2185
2186 if (is_at_poll_safepoint()) {
2187 // if the code we are returning to has deoptimized we must defer
2188 // the exception otherwise live registers get clobbered on the
2189 // exception path before deoptimization is able to retrieve them.
2190 //
2191 RegisterMap map(this, false);
2192 frame caller_fr = last_frame().sender(&map);
2193 assert(caller_fr.is_compiled_frame(), "what?");
2194 if (caller_fr.is_deoptimized_frame()) {
2195 log_info(exceptions)("deferred async exception at compiled safepoint");
2196 return;
2197 }
2198 }
2199 }
2200
2201 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2202 if (condition == _no_async_condition) {
2203 // Conditions have changed since has_special_runtime_exit_condition()
2204 // was called:
2205 // - if we were here only because of an external suspend request,
2206 // then that was taken care of above (or cancelled) so we are done
2207 // - if we were here because of another async request, then it has
2208 // been cleared between the has_special_runtime_exit_condition()
2209 // and now so again we are done
2210 return;
2211 }
2212
2213 // Check for pending async. exception
2214 if (_pending_async_exception != NULL) {
2215 // Only overwrite an already pending exception, if it is not a threadDeath.
2216 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2217
2218 // We cannot call Exceptions::_throw(...) here because we cannot block
2219 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2220
2221 LogTarget(Info, exceptions) lt;
2222 if (lt.is_enabled()) {
2223 ResourceMark rm;
2224 LogStream ls(lt);
2225 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2226 if (has_last_Java_frame()) {
2227 frame f = last_frame();
2228 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2229 }
2230 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2231 }
2232 _pending_async_exception = NULL;
2233 clear_has_async_exception();
2234 }
2235 }
2236
2237 if (check_unsafe_error &&
2238 condition == _async_unsafe_access_error && !has_pending_exception()) {
2239 condition = _no_async_condition; // done
2240 switch (thread_state()) {
2241 case _thread_in_vm: {
2242 JavaThread* THREAD = this;
2243 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2244 }
2245 case _thread_in_native: {
2246 ThreadInVMfromNative tiv(this);
2247 JavaThread* THREAD = this;
2248 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2249 }
2250 case _thread_in_Java: {
2251 ThreadInVMfromJava tiv(this);
2252 JavaThread* THREAD = this;
2253 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2254 }
2255 default:
2256 ShouldNotReachHere();
2257 }
2258 }
2259
2260 assert(condition == _no_async_condition || has_pending_exception() ||
2261 (!check_unsafe_error && condition == _async_unsafe_access_error),
2262 "must have handled the async condition, if no exception");
2263 }
2264
2265 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2266 //
2267 // Check for pending external suspend.
2268 // If JNIEnv proxies are allowed, don't self-suspend if the target
2269 // thread is not the current thread. In older versions of jdbx, jdbx
2270 // threads could call into the VM with another thread's JNIEnv so we
2271 // can be here operating on behalf of a suspended thread (4432884).
2272 bool do_self_suspend = is_external_suspend_with_lock();
2273 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2274 frame_anchor()->make_walkable(this);
2275 java_suspend_self_with_safepoint_check();
2276 }
2277
2278 // We might be here for reasons in addition to the self-suspend request
2279 // so check for other async requests.
2280 if (check_asyncs) {
2281 check_and_handle_async_exceptions();
2282 }
2283
2284 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2285 }
2286
2287 void JavaThread::send_thread_stop(oop java_throwable) {
2288 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2289 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2290 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2291
2292 // Do not throw asynchronous exceptions against the compiler thread
2293 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2294 if (!can_call_java()) return;
2295
2296 {
2297 // Actually throw the Throwable against the target Thread - however
2298 // only if there is no thread death exception installed already.
2299 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2300 // If the topmost frame is a runtime stub, then we are calling into
2301 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2302 // must deoptimize the caller before continuing, as the compiled exception handler table
2303 // may not be valid
2304 if (has_last_Java_frame()) {
2305 frame f = last_frame();
2306 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2307 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2308 RegisterMap reg_map(this, UseBiasedLocking);
2309 frame compiled_frame = f.sender(®_map);
2310 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2311 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2312 }
2313 }
2314 }
2315
2316 // Set async. pending exception in thread.
2317 set_pending_async_exception(java_throwable);
2318
2319 if (log_is_enabled(Info, exceptions)) {
2320 ResourceMark rm;
2321 log_info(exceptions)("Pending Async. exception installed of type: %s",
2322 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2323 }
2324 // for AbortVMOnException flag
2325 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2326 }
2327 }
2328
2329
2330 // Interrupt thread so it will wake up from a potential wait()
2331 Thread::interrupt(this);
2332 }
2333
2334 // External suspension mechanism.
2335 //
2336 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2337 // to any VM_locks and it is at a transition
2338 // Self-suspension will happen on the transition out of the vm.
2339 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2340 //
2341 // Guarantees on return:
2342 // + Target thread will not execute any new bytecode (that's why we need to
2343 // force a safepoint)
2344 // + Target thread will not enter any new monitors
2345 //
2346 void JavaThread::java_suspend() {
2347 ThreadsListHandle tlh;
2348 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2349 return;
2350 }
2351
2352 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2353 if (!is_external_suspend()) {
2354 // a racing resume has cancelled us; bail out now
2355 return;
2356 }
2357
2358 // suspend is done
2359 uint32_t debug_bits = 0;
2360 // Warning: is_ext_suspend_completed() may temporarily drop the
2361 // SR_lock to allow the thread to reach a stable thread state if
2362 // it is currently in a transient thread state.
2363 if (is_ext_suspend_completed(false /* !called_by_wait */,
2364 SuspendRetryDelay, &debug_bits)) {
2365 return;
2366 }
2367 }
2368
2369 if (Thread::current() == this) {
2370 // Safely self-suspend.
2371 // If we don't do this explicitly it will implicitly happen
2372 // before we transition back to Java, and on some other thread-state
2373 // transition paths, but not as we exit a JVM TI SuspendThread call.
2374 // As SuspendThread(current) must not return (until resumed) we must
2375 // self-suspend here.
2376 ThreadBlockInVM tbivm(this);
2377 java_suspend_self();
2378 } else {
2379 VM_ThreadSuspend vm_suspend;
2380 VMThread::execute(&vm_suspend);
2381 }
2382 }
2383
2384 // Part II of external suspension.
2385 // A JavaThread self suspends when it detects a pending external suspend
2386 // request. This is usually on transitions. It is also done in places
2387 // where continuing to the next transition would surprise the caller,
2388 // e.g., monitor entry.
2389 //
2390 // Returns the number of times that the thread self-suspended.
2391 //
2392 // Note: DO NOT call java_suspend_self() when you just want to block current
2393 // thread. java_suspend_self() is the second stage of cooperative
2394 // suspension for external suspend requests and should only be used
2395 // to complete an external suspend request.
2396 //
2397 int JavaThread::java_suspend_self() {
2398 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2399 int ret = 0;
2400
2401 // we are in the process of exiting so don't suspend
2402 if (is_exiting()) {
2403 clear_external_suspend();
2404 return ret;
2405 }
2406
2407 assert(_anchor.walkable() ||
2408 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2409 "must have walkable stack");
2410
2411 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2412
2413 assert(!this->is_ext_suspended(),
2414 "a thread trying to self-suspend should not already be suspended");
2415
2416 if (this->is_suspend_equivalent()) {
2417 // If we are self-suspending as a result of the lifting of a
2418 // suspend equivalent condition, then the suspend_equivalent
2419 // flag is not cleared until we set the ext_suspended flag so
2420 // that wait_for_ext_suspend_completion() returns consistent
2421 // results.
2422 this->clear_suspend_equivalent();
2423 }
2424
2425 // A racing resume may have cancelled us before we grabbed SR_lock
2426 // above. Or another external suspend request could be waiting for us
2427 // by the time we return from SR_lock()->wait(). The thread
2428 // that requested the suspension may already be trying to walk our
2429 // stack and if we return now, we can change the stack out from under
2430 // it. This would be a "bad thing (TM)" and cause the stack walker
2431 // to crash. We stay self-suspended until there are no more pending
2432 // external suspend requests.
2433 while (is_external_suspend()) {
2434 ret++;
2435 this->set_ext_suspended();
2436
2437 // _ext_suspended flag is cleared by java_resume()
2438 while (is_ext_suspended()) {
2439 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2440 }
2441 }
2442
2443 return ret;
2444 }
2445
2446 // Helper routine to set up the correct thread state before calling java_suspend_self.
2447 // This is called when regular thread-state transition helpers can't be used because
2448 // we can be in various states, in particular _thread_in_native_trans.
2449 // Because this thread is external suspended the safepoint code will count it as at
2450 // a safepoint, regardless of what its actual current thread-state is. But
2451 // is_ext_suspend_completed() may be waiting to see a thread transition from
2452 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2453 // to _thread_blocked. The problem with setting thread state directly is that a
2454 // safepoint could happen just after java_suspend_self() returns after being resumed,
2455 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2456 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2457 // However, not all initial-states are allowed when performing a safepoint check, as we
2458 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2459 // only _thread_in_native is possible when executing this code (based on our two callers).
2460 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2461 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2462 // and so we don't need the explicit safepoint check.
2463
2464 void JavaThread::java_suspend_self_with_safepoint_check() {
2465 assert(this == Thread::current(), "invariant");
2466 JavaThreadState state = thread_state();
2467 set_thread_state(_thread_blocked);
2468 java_suspend_self();
2469 set_thread_state(state);
2470 InterfaceSupport::serialize_thread_state_with_handler(this);
2471 if (state != _thread_in_native) {
2472 SafepointMechanism::block_if_requested(this);
2473 }
2474 }
2475
2476 #ifdef ASSERT
2477 // Verify the JavaThread has not yet been published in the Threads::list, and
2478 // hence doesn't need protection from concurrent access at this stage.
2479 void JavaThread::verify_not_published() {
2480 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2481 // since an unpublished JavaThread doesn't participate in the
2482 // Thread-SMR protocol for keeping a ThreadsList alive.
2483 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2484 }
2485 #endif
2486
2487 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2488 // progress or when _suspend_flags is non-zero.
2489 // Current thread needs to self-suspend if there is a suspend request and/or
2490 // block if a safepoint is in progress.
2491 // Async exception ISN'T checked.
2492 // Note only the ThreadInVMfromNative transition can call this function
2493 // directly and when thread state is _thread_in_native_trans
2494 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2495 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2496
2497 JavaThread *curJT = JavaThread::current();
2498 bool do_self_suspend = thread->is_external_suspend();
2499
2500 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2501
2502 // If JNIEnv proxies are allowed, don't self-suspend if the target
2503 // thread is not the current thread. In older versions of jdbx, jdbx
2504 // threads could call into the VM with another thread's JNIEnv so we
2505 // can be here operating on behalf of a suspended thread (4432884).
2506 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2507 thread->java_suspend_self_with_safepoint_check();
2508 } else {
2509 SafepointMechanism::block_if_requested(curJT);
2510 }
2511
2512 if (thread->is_deopt_suspend()) {
2513 thread->clear_deopt_suspend();
2514 RegisterMap map(thread, false);
2515 frame f = thread->last_frame();
2516 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2517 f = f.sender(&map);
2518 }
2519 if (f.id() == thread->must_deopt_id()) {
2520 thread->clear_must_deopt_id();
2521 f.deoptimize(thread);
2522 } else {
2523 fatal("missed deoptimization!");
2524 }
2525 }
2526
2527 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2528 }
2529
2530 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2531 // progress or when _suspend_flags is non-zero.
2532 // Current thread needs to self-suspend if there is a suspend request and/or
2533 // block if a safepoint is in progress.
2534 // Also check for pending async exception (not including unsafe access error).
2535 // Note only the native==>VM/Java barriers can call this function and when
2536 // thread state is _thread_in_native_trans.
2537 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2538 check_safepoint_and_suspend_for_native_trans(thread);
2539
2540 if (thread->has_async_exception()) {
2541 // We are in _thread_in_native_trans state, don't handle unsafe
2542 // access error since that may block.
2543 thread->check_and_handle_async_exceptions(false);
2544 }
2545 }
2546
2547 // This is a variant of the normal
2548 // check_special_condition_for_native_trans with slightly different
2549 // semantics for use by critical native wrappers. It does all the
2550 // normal checks but also performs the transition back into
2551 // thread_in_Java state. This is required so that critical natives
2552 // can potentially block and perform a GC if they are the last thread
2553 // exiting the GCLocker.
2554 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2555 check_special_condition_for_native_trans(thread);
2556
2557 // Finish the transition
2558 thread->set_thread_state(_thread_in_Java);
2559
2560 if (thread->do_critical_native_unlock()) {
2561 ThreadInVMfromJavaNoAsyncException tiv(thread);
2562 GCLocker::unlock_critical(thread);
2563 thread->clear_critical_native_unlock();
2564 }
2565 }
2566
2567 // We need to guarantee the Threads_lock here, since resumes are not
2568 // allowed during safepoint synchronization
2569 // Can only resume from an external suspension
2570 void JavaThread::java_resume() {
2571 assert_locked_or_safepoint(Threads_lock);
2572
2573 // Sanity check: thread is gone, has started exiting or the thread
2574 // was not externally suspended.
2575 ThreadsListHandle tlh;
2576 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2577 return;
2578 }
2579
2580 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2581
2582 clear_external_suspend();
2583
2584 if (is_ext_suspended()) {
2585 clear_ext_suspended();
2586 SR_lock()->notify_all();
2587 }
2588 }
2589
2590 size_t JavaThread::_stack_red_zone_size = 0;
2591 size_t JavaThread::_stack_yellow_zone_size = 0;
2592 size_t JavaThread::_stack_reserved_zone_size = 0;
2593 size_t JavaThread::_stack_shadow_zone_size = 0;
2594
2595 void JavaThread::create_stack_guard_pages() {
2596 if (!os::uses_stack_guard_pages() ||
2597 _stack_guard_state != stack_guard_unused ||
2598 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2599 log_info(os, thread)("Stack guard page creation for thread "
2600 UINTX_FORMAT " disabled", os::current_thread_id());
2601 return;
2602 }
2603 address low_addr = stack_end();
2604 size_t len = stack_guard_zone_size();
2605
2606 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2607 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2608
2609 int must_commit = os::must_commit_stack_guard_pages();
2610 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2611
2612 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2613 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2614 return;
2615 }
2616
2617 if (os::guard_memory((char *) low_addr, len)) {
2618 _stack_guard_state = stack_guard_enabled;
2619 } else {
2620 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2621 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2622 if (os::uncommit_memory((char *) low_addr, len)) {
2623 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2624 }
2625 return;
2626 }
2627
2628 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2629 PTR_FORMAT "-" PTR_FORMAT ".",
2630 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2631 }
2632
2633 void JavaThread::remove_stack_guard_pages() {
2634 assert(Thread::current() == this, "from different thread");
2635 if (_stack_guard_state == stack_guard_unused) return;
2636 address low_addr = stack_end();
2637 size_t len = stack_guard_zone_size();
2638
2639 if (os::must_commit_stack_guard_pages()) {
2640 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2641 _stack_guard_state = stack_guard_unused;
2642 } else {
2643 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2644 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2645 return;
2646 }
2647 } else {
2648 if (_stack_guard_state == stack_guard_unused) return;
2649 if (os::unguard_memory((char *) low_addr, len)) {
2650 _stack_guard_state = stack_guard_unused;
2651 } else {
2652 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2653 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2654 return;
2655 }
2656 }
2657
2658 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2659 PTR_FORMAT "-" PTR_FORMAT ".",
2660 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2661 }
2662
2663 void JavaThread::enable_stack_reserved_zone() {
2664 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2665
2666 // The base notation is from the stack's point of view, growing downward.
2667 // We need to adjust it to work correctly with guard_memory()
2668 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2669
2670 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2671 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2672
2673 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2674 _stack_guard_state = stack_guard_enabled;
2675 } else {
2676 warning("Attempt to guard stack reserved zone failed.");
2677 }
2678 enable_register_stack_guard();
2679 }
2680
2681 void JavaThread::disable_stack_reserved_zone() {
2682 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2683
2684 // Simply return if called for a thread that does not use guard pages.
2685 if (_stack_guard_state != stack_guard_enabled) return;
2686
2687 // The base notation is from the stack's point of view, growing downward.
2688 // We need to adjust it to work correctly with guard_memory()
2689 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2690
2691 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2692 _stack_guard_state = stack_guard_reserved_disabled;
2693 } else {
2694 warning("Attempt to unguard stack reserved zone failed.");
2695 }
2696 disable_register_stack_guard();
2697 }
2698
2699 void JavaThread::enable_stack_yellow_reserved_zone() {
2700 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2701 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2702
2703 // The base notation is from the stacks point of view, growing downward.
2704 // We need to adjust it to work correctly with guard_memory()
2705 address base = stack_red_zone_base();
2706
2707 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2708 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2709
2710 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2711 _stack_guard_state = stack_guard_enabled;
2712 } else {
2713 warning("Attempt to guard stack yellow zone failed.");
2714 }
2715 enable_register_stack_guard();
2716 }
2717
2718 void JavaThread::disable_stack_yellow_reserved_zone() {
2719 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2720 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2721
2722 // Simply return if called for a thread that does not use guard pages.
2723 if (_stack_guard_state == stack_guard_unused) return;
2724
2725 // The base notation is from the stacks point of view, growing downward.
2726 // We need to adjust it to work correctly with guard_memory()
2727 address base = stack_red_zone_base();
2728
2729 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2730 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2731 } else {
2732 warning("Attempt to unguard stack yellow zone failed.");
2733 }
2734 disable_register_stack_guard();
2735 }
2736
2737 void JavaThread::enable_stack_red_zone() {
2738 // The base notation is from the stacks point of view, growing downward.
2739 // We need to adjust it to work correctly with guard_memory()
2740 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2741 address base = stack_red_zone_base() - stack_red_zone_size();
2742
2743 guarantee(base < stack_base(), "Error calculating stack red zone");
2744 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2745
2746 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2747 warning("Attempt to guard stack red zone failed.");
2748 }
2749 }
2750
2751 void JavaThread::disable_stack_red_zone() {
2752 // The base notation is from the stacks point of view, growing downward.
2753 // We need to adjust it to work correctly with guard_memory()
2754 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2755 address base = stack_red_zone_base() - stack_red_zone_size();
2756 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2757 warning("Attempt to unguard stack red zone failed.");
2758 }
2759 }
2760
2761 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2762 // ignore is there is no stack
2763 if (!has_last_Java_frame()) return;
2764 // traverse the stack frames. Starts from top frame.
2765 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2766 frame* fr = fst.current();
2767 f(fr, fst.register_map());
2768 }
2769 }
2770
2771
2772 #ifndef PRODUCT
2773 // Deoptimization
2774 // Function for testing deoptimization
2775 void JavaThread::deoptimize() {
2776 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2777 StackFrameStream fst(this, UseBiasedLocking);
2778 bool deopt = false; // Dump stack only if a deopt actually happens.
2779 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2780 // Iterate over all frames in the thread and deoptimize
2781 for (; !fst.is_done(); fst.next()) {
2782 if (fst.current()->can_be_deoptimized()) {
2783
2784 if (only_at) {
2785 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2786 // consists of comma or carriage return separated numbers so
2787 // search for the current bci in that string.
2788 address pc = fst.current()->pc();
2789 nmethod* nm = (nmethod*) fst.current()->cb();
2790 ScopeDesc* sd = nm->scope_desc_at(pc);
2791 char buffer[8];
2792 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2793 size_t len = strlen(buffer);
2794 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2795 while (found != NULL) {
2796 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2797 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2798 // Check that the bci found is bracketed by terminators.
2799 break;
2800 }
2801 found = strstr(found + 1, buffer);
2802 }
2803 if (!found) {
2804 continue;
2805 }
2806 }
2807
2808 if (DebugDeoptimization && !deopt) {
2809 deopt = true; // One-time only print before deopt
2810 tty->print_cr("[BEFORE Deoptimization]");
2811 trace_frames();
2812 trace_stack();
2813 }
2814 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2815 }
2816 }
2817
2818 if (DebugDeoptimization && deopt) {
2819 tty->print_cr("[AFTER Deoptimization]");
2820 trace_frames();
2821 }
2822 }
2823
2824
2825 // Make zombies
2826 void JavaThread::make_zombies() {
2827 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2828 if (fst.current()->can_be_deoptimized()) {
2829 // it is a Java nmethod
2830 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2831 nm->make_not_entrant();
2832 }
2833 }
2834 }
2835 #endif // PRODUCT
2836
2837
2838 void JavaThread::deoptimized_wrt_marked_nmethods() {
2839 if (!has_last_Java_frame()) return;
2840 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2841 StackFrameStream fst(this, UseBiasedLocking);
2842 for (; !fst.is_done(); fst.next()) {
2843 if (fst.current()->should_be_deoptimized()) {
2844 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2845 }
2846 }
2847 }
2848
2849
2850 // If the caller is a NamedThread, then remember, in the current scope,
2851 // the given JavaThread in its _processed_thread field.
2852 class RememberProcessedThread: public StackObj {
2853 NamedThread* _cur_thr;
2854 public:
2855 RememberProcessedThread(JavaThread* jthr) {
2856 Thread* thread = Thread::current();
2857 if (thread->is_Named_thread()) {
2858 _cur_thr = (NamedThread *)thread;
2859 _cur_thr->set_processed_thread(jthr);
2860 } else {
2861 _cur_thr = NULL;
2862 }
2863 }
2864
2865 ~RememberProcessedThread() {
2866 if (_cur_thr) {
2867 _cur_thr->set_processed_thread(NULL);
2868 }
2869 }
2870 };
2871
2872 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2873 // Verify that the deferred card marks have been flushed.
2874 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2875
2876 // Traverse the GCHandles
2877 Thread::oops_do(f, cf);
2878
2879 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2880 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2881
2882 if (has_last_Java_frame()) {
2883 // Record JavaThread to GC thread
2884 RememberProcessedThread rpt(this);
2885
2886 // traverse the registered growable array
2887 if (_array_for_gc != NULL) {
2888 for (int index = 0; index < _array_for_gc->length(); index++) {
2889 f->do_oop(_array_for_gc->adr_at(index));
2890 }
2891 }
2892
2893 // Traverse the monitor chunks
2894 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2895 chunk->oops_do(f);
2896 }
2897
2898 // Traverse the execution stack
2899 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2900 fst.current()->oops_do(f, cf, fst.register_map());
2901 }
2902 }
2903
2904 // callee_target is never live across a gc point so NULL it here should
2905 // it still contain a methdOop.
2906
2907 set_callee_target(NULL);
2908
2909 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2910 // If we have deferred set_locals there might be oops waiting to be
2911 // written
2912 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2913 if (list != NULL) {
2914 for (int i = 0; i < list->length(); i++) {
2915 list->at(i)->oops_do(f);
2916 }
2917 }
2918
2919 // Traverse instance variables at the end since the GC may be moving things
2920 // around using this function
2921 f->do_oop((oop*) &_threadObj);
2922 f->do_oop((oop*) &_vm_result);
2923 f->do_oop((oop*) &_exception_oop);
2924 f->do_oop((oop*) &_pending_async_exception);
2925
2926 if (jvmti_thread_state() != NULL) {
2927 jvmti_thread_state()->oops_do(f);
2928 }
2929 }
2930
2931 #ifdef ASSERT
2932 void JavaThread::verify_states_for_handshake() {
2933 // This checks that the thread has a correct frame state during a handshake.
2934 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2935 (has_last_Java_frame() && java_call_counter() > 0),
2936 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2937 has_last_Java_frame(), java_call_counter());
2938 }
2939 #endif
2940
2941 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2942 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2943 (has_last_Java_frame() && java_call_counter() > 0),
2944 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2945 has_last_Java_frame(), java_call_counter());
2946
2947 if (has_last_Java_frame()) {
2948 // Traverse the execution stack
2949 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2950 fst.current()->nmethods_do(cf);
2951 }
2952 }
2953 }
2954
2955 void JavaThread::metadata_do(MetadataClosure* f) {
2956 if (has_last_Java_frame()) {
2957 // Traverse the execution stack to call f() on the methods in the stack
2958 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2959 fst.current()->metadata_do(f);
2960 }
2961 } else if (is_Compiler_thread()) {
2962 // need to walk ciMetadata in current compile tasks to keep alive.
2963 CompilerThread* ct = (CompilerThread*)this;
2964 if (ct->env() != NULL) {
2965 ct->env()->metadata_do(f);
2966 }
2967 CompileTask* task = ct->task();
2968 if (task != NULL) {
2969 task->metadata_do(f);
2970 }
2971 }
2972 }
2973
2974 // Printing
2975 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2976 switch (_thread_state) {
2977 case _thread_uninitialized: return "_thread_uninitialized";
2978 case _thread_new: return "_thread_new";
2979 case _thread_new_trans: return "_thread_new_trans";
2980 case _thread_in_native: return "_thread_in_native";
2981 case _thread_in_native_trans: return "_thread_in_native_trans";
2982 case _thread_in_vm: return "_thread_in_vm";
2983 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2984 case _thread_in_Java: return "_thread_in_Java";
2985 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2986 case _thread_blocked: return "_thread_blocked";
2987 case _thread_blocked_trans: return "_thread_blocked_trans";
2988 default: return "unknown thread state";
2989 }
2990 }
2991
2992 #ifndef PRODUCT
2993 void JavaThread::print_thread_state_on(outputStream *st) const {
2994 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2995 };
2996 void JavaThread::print_thread_state() const {
2997 print_thread_state_on(tty);
2998 }
2999 #endif // PRODUCT
3000
3001 // Called by Threads::print() for VM_PrintThreads operation
3002 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3003 st->print_raw("\"");
3004 st->print_raw(get_thread_name());
3005 st->print_raw("\" ");
3006 oop thread_oop = threadObj();
3007 if (thread_oop != NULL) {
3008 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3009 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3010 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3011 }
3012 Thread::print_on(st, print_extended_info);
3013 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3014 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3015 if (thread_oop != NULL) {
3016 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3017 }
3018 #ifndef PRODUCT
3019 _safepoint_state->print_on(st);
3020 #endif // PRODUCT
3021 if (is_Compiler_thread()) {
3022 CompileTask *task = ((CompilerThread*)this)->task();
3023 if (task != NULL) {
3024 st->print(" Compiling: ");
3025 task->print(st, NULL, true, false);
3026 } else {
3027 st->print(" No compile task");
3028 }
3029 st->cr();
3030 }
3031 }
3032
3033 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3034 st->print("%s", get_thread_name_string(buf, buflen));
3035 }
3036
3037 // Called by fatal error handler. The difference between this and
3038 // JavaThread::print() is that we can't grab lock or allocate memory.
3039 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3040 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3041 oop thread_obj = threadObj();
3042 if (thread_obj != NULL) {
3043 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3044 }
3045 st->print(" [");
3046 st->print("%s", _get_thread_state_name(_thread_state));
3047 if (osthread()) {
3048 st->print(", id=%d", osthread()->thread_id());
3049 }
3050 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3051 p2i(stack_end()), p2i(stack_base()));
3052 st->print("]");
3053
3054 ThreadsSMRSupport::print_info_on(this, st);
3055 return;
3056 }
3057
3058 // Verification
3059
3060 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3061
3062 void JavaThread::verify() {
3063 // Verify oops in the thread.
3064 oops_do(&VerifyOopClosure::verify_oop, NULL);
3065
3066 // Verify the stack frames.
3067 frames_do(frame_verify);
3068 }
3069
3070 // CR 6300358 (sub-CR 2137150)
3071 // Most callers of this method assume that it can't return NULL but a
3072 // thread may not have a name whilst it is in the process of attaching to
3073 // the VM - see CR 6412693, and there are places where a JavaThread can be
3074 // seen prior to having it's threadObj set (eg JNI attaching threads and
3075 // if vm exit occurs during initialization). These cases can all be accounted
3076 // for such that this method never returns NULL.
3077 const char* JavaThread::get_thread_name() const {
3078 #ifdef ASSERT
3079 // early safepoints can hit while current thread does not yet have TLS
3080 if (!SafepointSynchronize::is_at_safepoint()) {
3081 Thread *cur = Thread::current();
3082 if (!(cur->is_Java_thread() && cur == this)) {
3083 // Current JavaThreads are allowed to get their own name without
3084 // the Threads_lock.
3085 assert_locked_or_safepoint(Threads_lock);
3086 }
3087 }
3088 #endif // ASSERT
3089 return get_thread_name_string();
3090 }
3091
3092 // Returns a non-NULL representation of this thread's name, or a suitable
3093 // descriptive string if there is no set name
3094 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3095 const char* name_str;
3096 oop thread_obj = threadObj();
3097 if (thread_obj != NULL) {
3098 oop name = java_lang_Thread::name(thread_obj);
3099 if (name != NULL) {
3100 if (buf == NULL) {
3101 name_str = java_lang_String::as_utf8_string(name);
3102 } else {
3103 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3104 }
3105 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3106 name_str = "<no-name - thread is attaching>";
3107 } else {
3108 name_str = Thread::name();
3109 }
3110 } else {
3111 name_str = Thread::name();
3112 }
3113 assert(name_str != NULL, "unexpected NULL thread name");
3114 return name_str;
3115 }
3116
3117
3118 const char* JavaThread::get_threadgroup_name() const {
3119 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3120 oop thread_obj = threadObj();
3121 if (thread_obj != NULL) {
3122 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3123 if (thread_group != NULL) {
3124 // ThreadGroup.name can be null
3125 return java_lang_ThreadGroup::name(thread_group);
3126 }
3127 }
3128 return NULL;
3129 }
3130
3131 const char* JavaThread::get_parent_name() const {
3132 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3133 oop thread_obj = threadObj();
3134 if (thread_obj != NULL) {
3135 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3136 if (thread_group != NULL) {
3137 oop parent = java_lang_ThreadGroup::parent(thread_group);
3138 if (parent != NULL) {
3139 // ThreadGroup.name can be null
3140 return java_lang_ThreadGroup::name(parent);
3141 }
3142 }
3143 }
3144 return NULL;
3145 }
3146
3147 ThreadPriority JavaThread::java_priority() const {
3148 oop thr_oop = threadObj();
3149 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3150 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3151 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3152 return priority;
3153 }
3154
3155 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3156
3157 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3158 // Link Java Thread object <-> C++ Thread
3159
3160 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3161 // and put it into a new Handle. The Handle "thread_oop" can then
3162 // be used to pass the C++ thread object to other methods.
3163
3164 // Set the Java level thread object (jthread) field of the
3165 // new thread (a JavaThread *) to C++ thread object using the
3166 // "thread_oop" handle.
3167
3168 // Set the thread field (a JavaThread *) of the
3169 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3170
3171 Handle thread_oop(Thread::current(),
3172 JNIHandles::resolve_non_null(jni_thread));
3173 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3174 "must be initialized");
3175 set_threadObj(thread_oop());
3176 java_lang_Thread::set_thread(thread_oop(), this);
3177
3178 if (prio == NoPriority) {
3179 prio = java_lang_Thread::priority(thread_oop());
3180 assert(prio != NoPriority, "A valid priority should be present");
3181 }
3182
3183 // Push the Java priority down to the native thread; needs Threads_lock
3184 Thread::set_priority(this, prio);
3185
3186 // Add the new thread to the Threads list and set it in motion.
3187 // We must have threads lock in order to call Threads::add.
3188 // It is crucial that we do not block before the thread is
3189 // added to the Threads list for if a GC happens, then the java_thread oop
3190 // will not be visited by GC.
3191 Threads::add(this);
3192 }
3193
3194 oop JavaThread::current_park_blocker() {
3195 // Support for JSR-166 locks
3196 oop thread_oop = threadObj();
3197 if (thread_oop != NULL &&
3198 JDK_Version::current().supports_thread_park_blocker()) {
3199 return java_lang_Thread::park_blocker(thread_oop);
3200 }
3201 return NULL;
3202 }
3203
3204
3205 void JavaThread::print_stack_on(outputStream* st) {
3206 if (!has_last_Java_frame()) return;
3207 ResourceMark rm;
3208 HandleMark hm;
3209
3210 RegisterMap reg_map(this);
3211 vframe* start_vf = last_java_vframe(®_map);
3212 int count = 0;
3213 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3214 if (f->is_java_frame()) {
3215 javaVFrame* jvf = javaVFrame::cast(f);
3216 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3217
3218 // Print out lock information
3219 if (JavaMonitorsInStackTrace) {
3220 jvf->print_lock_info_on(st, count);
3221 }
3222 } else {
3223 // Ignore non-Java frames
3224 }
3225
3226 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3227 count++;
3228 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3229 }
3230 }
3231
3232
3233 // JVMTI PopFrame support
3234 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3235 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3236 if (in_bytes(size_in_bytes) != 0) {
3237 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3238 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3239 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3240 }
3241 }
3242
3243 void* JavaThread::popframe_preserved_args() {
3244 return _popframe_preserved_args;
3245 }
3246
3247 ByteSize JavaThread::popframe_preserved_args_size() {
3248 return in_ByteSize(_popframe_preserved_args_size);
3249 }
3250
3251 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3252 int sz = in_bytes(popframe_preserved_args_size());
3253 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3254 return in_WordSize(sz / wordSize);
3255 }
3256
3257 void JavaThread::popframe_free_preserved_args() {
3258 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3259 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3260 _popframe_preserved_args = NULL;
3261 _popframe_preserved_args_size = 0;
3262 }
3263
3264 #ifndef PRODUCT
3265
3266 void JavaThread::trace_frames() {
3267 tty->print_cr("[Describe stack]");
3268 int frame_no = 1;
3269 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3270 tty->print(" %d. ", frame_no++);
3271 fst.current()->print_value_on(tty, this);
3272 tty->cr();
3273 }
3274 }
3275
3276 class PrintAndVerifyOopClosure: public OopClosure {
3277 protected:
3278 template <class T> inline void do_oop_work(T* p) {
3279 oop obj = RawAccess<>::oop_load(p);
3280 if (obj == NULL) return;
3281 tty->print(INTPTR_FORMAT ": ", p2i(p));
3282 if (oopDesc::is_oop_or_null(obj)) {
3283 if (obj->is_objArray()) {
3284 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3285 } else {
3286 obj->print();
3287 }
3288 } else {
3289 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3290 }
3291 tty->cr();
3292 }
3293 public:
3294 virtual void do_oop(oop* p) { do_oop_work(p); }
3295 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3296 };
3297
3298
3299 static void oops_print(frame* f, const RegisterMap *map) {
3300 PrintAndVerifyOopClosure print;
3301 f->print_value();
3302 f->oops_do(&print, NULL, (RegisterMap*)map);
3303 }
3304
3305 // Print our all the locations that contain oops and whether they are
3306 // valid or not. This useful when trying to find the oldest frame
3307 // where an oop has gone bad since the frame walk is from youngest to
3308 // oldest.
3309 void JavaThread::trace_oops() {
3310 tty->print_cr("[Trace oops]");
3311 frames_do(oops_print);
3312 }
3313
3314
3315 #ifdef ASSERT
3316 // Print or validate the layout of stack frames
3317 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3318 ResourceMark rm;
3319 PRESERVE_EXCEPTION_MARK;
3320 FrameValues values;
3321 int frame_no = 0;
3322 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3323 fst.current()->describe(values, ++frame_no);
3324 if (depth == frame_no) break;
3325 }
3326 if (validate_only) {
3327 values.validate();
3328 } else {
3329 tty->print_cr("[Describe stack layout]");
3330 values.print(this);
3331 }
3332 }
3333 #endif
3334
3335 void JavaThread::trace_stack_from(vframe* start_vf) {
3336 ResourceMark rm;
3337 int vframe_no = 1;
3338 for (vframe* f = start_vf; f; f = f->sender()) {
3339 if (f->is_java_frame()) {
3340 javaVFrame::cast(f)->print_activation(vframe_no++);
3341 } else {
3342 f->print();
3343 }
3344 if (vframe_no > StackPrintLimit) {
3345 tty->print_cr("...<more frames>...");
3346 return;
3347 }
3348 }
3349 }
3350
3351
3352 void JavaThread::trace_stack() {
3353 if (!has_last_Java_frame()) return;
3354 ResourceMark rm;
3355 HandleMark hm;
3356 RegisterMap reg_map(this);
3357 trace_stack_from(last_java_vframe(®_map));
3358 }
3359
3360
3361 #endif // PRODUCT
3362
3363
3364 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3365 assert(reg_map != NULL, "a map must be given");
3366 frame f = last_frame();
3367 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3368 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3369 }
3370 return NULL;
3371 }
3372
3373
3374 Klass* JavaThread::security_get_caller_class(int depth) {
3375 vframeStream vfst(this);
3376 vfst.security_get_caller_frame(depth);
3377 if (!vfst.at_end()) {
3378 return vfst.method()->method_holder();
3379 }
3380 return NULL;
3381 }
3382
3383 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3384 assert(thread->is_Compiler_thread(), "must be compiler thread");
3385 CompileBroker::compiler_thread_loop();
3386 }
3387
3388 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3389 NMethodSweeper::sweeper_loop();
3390 }
3391
3392 // Create a CompilerThread
3393 CompilerThread::CompilerThread(CompileQueue* queue,
3394 CompilerCounters* counters)
3395 : JavaThread(&compiler_thread_entry) {
3396 _env = NULL;
3397 _log = NULL;
3398 _task = NULL;
3399 _queue = queue;
3400 _counters = counters;
3401 _buffer_blob = NULL;
3402 _compiler = NULL;
3403
3404 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3405 resource_area()->bias_to(mtCompiler);
3406
3407 #ifndef PRODUCT
3408 _ideal_graph_printer = NULL;
3409 #endif
3410 }
3411
3412 CompilerThread::~CompilerThread() {
3413 // Delete objects which were allocated on heap.
3414 delete _counters;
3415 }
3416
3417 bool CompilerThread::can_call_java() const {
3418 return _compiler != NULL && _compiler->is_jvmci();
3419 }
3420
3421 // Create sweeper thread
3422 CodeCacheSweeperThread::CodeCacheSweeperThread()
3423 : JavaThread(&sweeper_thread_entry) {
3424 _scanned_compiled_method = NULL;
3425 }
3426
3427 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3428 JavaThread::oops_do(f, cf);
3429 if (_scanned_compiled_method != NULL && cf != NULL) {
3430 // Safepoints can occur when the sweeper is scanning an nmethod so
3431 // process it here to make sure it isn't unloaded in the middle of
3432 // a scan.
3433 cf->do_code_blob(_scanned_compiled_method);
3434 }
3435 }
3436
3437 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3438 JavaThread::nmethods_do(cf);
3439 if (_scanned_compiled_method != NULL && cf != NULL) {
3440 // Safepoints can occur when the sweeper is scanning an nmethod so
3441 // process it here to make sure it isn't unloaded in the middle of
3442 // a scan.
3443 cf->do_code_blob(_scanned_compiled_method);
3444 }
3445 }
3446
3447
3448 // ======= Threads ========
3449
3450 // The Threads class links together all active threads, and provides
3451 // operations over all threads. It is protected by the Threads_lock,
3452 // which is also used in other global contexts like safepointing.
3453 // ThreadsListHandles are used to safely perform operations on one
3454 // or more threads without the risk of the thread exiting during the
3455 // operation.
3456 //
3457 // Note: The Threads_lock is currently more widely used than we
3458 // would like. We are actively migrating Threads_lock uses to other
3459 // mechanisms in order to reduce Threads_lock contention.
3460
3461 JavaThread* Threads::_thread_list = NULL;
3462 int Threads::_number_of_threads = 0;
3463 int Threads::_number_of_non_daemon_threads = 0;
3464 int Threads::_return_code = 0;
3465 int Threads::_thread_claim_parity = 0;
3466 size_t JavaThread::_stack_size_at_create = 0;
3467
3468 #ifdef ASSERT
3469 bool Threads::_vm_complete = false;
3470 #endif
3471
3472 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3473 Prefetch::read((void*)addr, prefetch_interval);
3474 return *addr;
3475 }
3476
3477 // Possibly the ugliest for loop the world has seen. C++ does not allow
3478 // multiple types in the declaration section of the for loop. In this case
3479 // we are only dealing with pointers and hence can cast them. It looks ugly
3480 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3481 #define DO_JAVA_THREADS(LIST, X) \
3482 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3483 *MACRO_list = (JavaThread*)(LIST), \
3484 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3485 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3486 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3487 MACRO_current_p != MACRO_end; \
3488 MACRO_current_p++, \
3489 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3490
3491 // All JavaThreads
3492 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3493
3494 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3495 void Threads::non_java_threads_do(ThreadClosure* tc) {
3496 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3497 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3498 tc->do_thread(njti.current());
3499 }
3500 }
3501
3502 // All JavaThreads
3503 void Threads::java_threads_do(ThreadClosure* tc) {
3504 assert_locked_or_safepoint(Threads_lock);
3505 // ALL_JAVA_THREADS iterates through all JavaThreads.
3506 ALL_JAVA_THREADS(p) {
3507 tc->do_thread(p);
3508 }
3509 }
3510
3511 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3512 assert_locked_or_safepoint(Threads_lock);
3513 java_threads_do(tc);
3514 tc->do_thread(VMThread::vm_thread());
3515 }
3516
3517 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3518 void Threads::threads_do(ThreadClosure* tc) {
3519 assert_locked_or_safepoint(Threads_lock);
3520 java_threads_do(tc);
3521 non_java_threads_do(tc);
3522 }
3523
3524 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3525 int cp = Threads::thread_claim_parity();
3526 ALL_JAVA_THREADS(p) {
3527 if (p->claim_oops_do(is_par, cp)) {
3528 tc->do_thread(p);
3529 }
3530 }
3531 VMThread* vmt = VMThread::vm_thread();
3532 if (vmt->claim_oops_do(is_par, cp)) {
3533 tc->do_thread(vmt);
3534 }
3535 }
3536
3537 // The system initialization in the library has three phases.
3538 //
3539 // Phase 1: java.lang.System class initialization
3540 // java.lang.System is a primordial class loaded and initialized
3541 // by the VM early during startup. java.lang.System.<clinit>
3542 // only does registerNatives and keeps the rest of the class
3543 // initialization work later until thread initialization completes.
3544 //
3545 // System.initPhase1 initializes the system properties, the static
3546 // fields in, out, and err. Set up java signal handlers, OS-specific
3547 // system settings, and thread group of the main thread.
3548 static void call_initPhase1(TRAPS) {
3549 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3550 JavaValue result(T_VOID);
3551 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3552 vmSymbols::void_method_signature(), CHECK);
3553 }
3554
3555 // Phase 2. Module system initialization
3556 // This will initialize the module system. Only java.base classes
3557 // can be loaded until phase 2 completes.
3558 //
3559 // Call System.initPhase2 after the compiler initialization and jsr292
3560 // classes get initialized because module initialization runs a lot of java
3561 // code, that for performance reasons, should be compiled. Also, this will
3562 // enable the startup code to use lambda and other language features in this
3563 // phase and onward.
3564 //
3565 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3566 static void call_initPhase2(TRAPS) {
3567 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3568
3569 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3570
3571 JavaValue result(T_INT);
3572 JavaCallArguments args;
3573 args.push_int(DisplayVMOutputToStderr);
3574 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3575 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3576 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3577 if (result.get_jint() != JNI_OK) {
3578 vm_exit_during_initialization(); // no message or exception
3579 }
3580
3581 universe_post_module_init();
3582 }
3583
3584 // Phase 3. final setup - set security manager, system class loader and TCCL
3585 //
3586 // This will instantiate and set the security manager, set the system class
3587 // loader as well as the thread context class loader. The security manager
3588 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3589 // other modules or the application's classpath.
3590 static void call_initPhase3(TRAPS) {
3591 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3592 JavaValue result(T_VOID);
3593 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3594 vmSymbols::void_method_signature(), CHECK);
3595 }
3596
3597 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3598 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3599
3600 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3601 create_vm_init_libraries();
3602 }
3603
3604 initialize_class(vmSymbols::java_lang_String(), CHECK);
3605
3606 // Inject CompactStrings value after the static initializers for String ran.
3607 java_lang_String::set_compact_strings(CompactStrings);
3608
3609 // Initialize java_lang.System (needed before creating the thread)
3610 initialize_class(vmSymbols::java_lang_System(), CHECK);
3611 // The VM creates & returns objects of this class. Make sure it's initialized.
3612 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3613 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3614 Handle thread_group = create_initial_thread_group(CHECK);
3615 Universe::set_main_thread_group(thread_group());
3616 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3617 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3618 main_thread->set_threadObj(thread_object);
3619 // Set thread status to running since main thread has
3620 // been started and running.
3621 java_lang_Thread::set_thread_status(thread_object,
3622 java_lang_Thread::RUNNABLE);
3623
3624 // The VM creates objects of this class.
3625 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3626
3627 // The VM preresolves methods to these classes. Make sure that they get initialized
3628 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3629 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3630
3631 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3632 call_initPhase1(CHECK);
3633
3634 // get the Java runtime name after java.lang.System is initialized
3635 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3636 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3637
3638 // an instance of OutOfMemory exception has been allocated earlier
3639 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3640 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3641 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3642 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3643 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3644 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3645 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3646 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3647 }
3648
3649 void Threads::initialize_jsr292_core_classes(TRAPS) {
3650 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3651
3652 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3653 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3654 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3655 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3656 }
3657
3658 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3659 extern void JDK_Version_init();
3660
3661 // Preinitialize version info.
3662 VM_Version::early_initialize();
3663
3664 // Check version
3665 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3666
3667 // Initialize library-based TLS
3668 ThreadLocalStorage::init();
3669
3670 // Initialize the output stream module
3671 ostream_init();
3672
3673 // Process java launcher properties.
3674 Arguments::process_sun_java_launcher_properties(args);
3675
3676 // Initialize the os module
3677 os::init();
3678
3679 // Record VM creation timing statistics
3680 TraceVmCreationTime create_vm_timer;
3681 create_vm_timer.start();
3682
3683 // Initialize system properties.
3684 Arguments::init_system_properties();
3685
3686 // So that JDK version can be used as a discriminator when parsing arguments
3687 JDK_Version_init();
3688
3689 // Update/Initialize System properties after JDK version number is known
3690 Arguments::init_version_specific_system_properties();
3691
3692 // Make sure to initialize log configuration *before* parsing arguments
3693 LogConfiguration::initialize(create_vm_timer.begin_time());
3694
3695 // Parse arguments
3696 // Note: this internally calls os::init_container_support()
3697 jint parse_result = Arguments::parse(args);
3698 if (parse_result != JNI_OK) return parse_result;
3699
3700 os::init_before_ergo();
3701
3702 jint ergo_result = Arguments::apply_ergo();
3703 if (ergo_result != JNI_OK) return ergo_result;
3704
3705 // Final check of all ranges after ergonomics which may change values.
3706 if (!JVMFlagRangeList::check_ranges()) {
3707 return JNI_EINVAL;
3708 }
3709
3710 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3711 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3712 if (!constraint_result) {
3713 return JNI_EINVAL;
3714 }
3715
3716 JVMFlagWriteableList::mark_startup();
3717
3718 if (PauseAtStartup) {
3719 os::pause();
3720 }
3721
3722 HOTSPOT_VM_INIT_BEGIN();
3723
3724 // Timing (must come after argument parsing)
3725 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3726
3727 // Initialize the os module after parsing the args
3728 jint os_init_2_result = os::init_2();
3729 if (os_init_2_result != JNI_OK) return os_init_2_result;
3730
3731 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3732 // Initialize assert poison page mechanism.
3733 if (ShowRegistersOnAssert) {
3734 initialize_assert_poison();
3735 }
3736 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3737
3738 SafepointMechanism::initialize();
3739
3740 jint adjust_after_os_result = Arguments::adjust_after_os();
3741 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3742
3743 // Initialize output stream logging
3744 ostream_init_log();
3745
3746 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3747 // Must be before create_vm_init_agents()
3748 if (Arguments::init_libraries_at_startup()) {
3749 convert_vm_init_libraries_to_agents();
3750 }
3751
3752 // Launch -agentlib/-agentpath and converted -Xrun agents
3753 if (Arguments::init_agents_at_startup()) {
3754 create_vm_init_agents();
3755 }
3756
3757 // Initialize Threads state
3758 _thread_list = NULL;
3759 _number_of_threads = 0;
3760 _number_of_non_daemon_threads = 0;
3761
3762 // Initialize global data structures and create system classes in heap
3763 vm_init_globals();
3764
3765 #if INCLUDE_JVMCI
3766 if (JVMCICounterSize > 0) {
3767 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3768 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3769 } else {
3770 JavaThread::_jvmci_old_thread_counters = NULL;
3771 }
3772 #endif // INCLUDE_JVMCI
3773
3774 // Attach the main thread to this os thread
3775 JavaThread* main_thread = new JavaThread();
3776 main_thread->set_thread_state(_thread_in_vm);
3777 main_thread->initialize_thread_current();
3778 // must do this before set_active_handles
3779 main_thread->record_stack_base_and_size();
3780 main_thread->register_thread_stack_with_NMT();
3781 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3782
3783 if (!main_thread->set_as_starting_thread()) {
3784 vm_shutdown_during_initialization(
3785 "Failed necessary internal allocation. Out of swap space");
3786 main_thread->smr_delete();
3787 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3788 return JNI_ENOMEM;
3789 }
3790
3791 // Enable guard page *after* os::create_main_thread(), otherwise it would
3792 // crash Linux VM, see notes in os_linux.cpp.
3793 main_thread->create_stack_guard_pages();
3794
3795 // Initialize Java-Level synchronization subsystem
3796 ObjectMonitor::Initialize();
3797
3798 // Initialize global modules
3799 jint status = init_globals();
3800 if (status != JNI_OK) {
3801 main_thread->smr_delete();
3802 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3803 return status;
3804 }
3805
3806 JFR_ONLY(Jfr::on_vm_init();)
3807
3808 // Should be done after the heap is fully created
3809 main_thread->cache_global_variables();
3810
3811 HandleMark hm;
3812
3813 { MutexLocker mu(Threads_lock);
3814 Threads::add(main_thread);
3815 }
3816
3817 // Any JVMTI raw monitors entered in onload will transition into
3818 // real raw monitor. VM is setup enough here for raw monitor enter.
3819 JvmtiExport::transition_pending_onload_raw_monitors();
3820
3821 // Create the VMThread
3822 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3823
3824 VMThread::create();
3825 Thread* vmthread = VMThread::vm_thread();
3826
3827 if (!os::create_thread(vmthread, os::vm_thread)) {
3828 vm_exit_during_initialization("Cannot create VM thread. "
3829 "Out of system resources.");
3830 }
3831
3832 // Wait for the VM thread to become ready, and VMThread::run to initialize
3833 // Monitors can have spurious returns, must always check another state flag
3834 {
3835 MutexLocker ml(Notify_lock);
3836 os::start_thread(vmthread);
3837 while (vmthread->active_handles() == NULL) {
3838 Notify_lock->wait();
3839 }
3840 }
3841 }
3842
3843 assert(Universe::is_fully_initialized(), "not initialized");
3844 if (VerifyDuringStartup) {
3845 // Make sure we're starting with a clean slate.
3846 VM_Verify verify_op;
3847 VMThread::execute(&verify_op);
3848 }
3849
3850 // We need this to update the java.vm.info property in case any flags used
3851 // to initially define it have been changed. This is needed for both CDS and
3852 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3853 // is initially computed. See Abstract_VM_Version::vm_info_string().
3854 // This update must happen before we initialize the java classes, but
3855 // after any initialization logic that might modify the flags.
3856 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3857
3858 Thread* THREAD = Thread::current();
3859
3860 // Always call even when there are not JVMTI environments yet, since environments
3861 // may be attached late and JVMTI must track phases of VM execution
3862 JvmtiExport::enter_early_start_phase();
3863
3864 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3865 JvmtiExport::post_early_vm_start();
3866
3867 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3868
3869 quicken_jni_functions();
3870
3871 // No more stub generation allowed after that point.
3872 StubCodeDesc::freeze();
3873
3874 // Set flag that basic initialization has completed. Used by exceptions and various
3875 // debug stuff, that does not work until all basic classes have been initialized.
3876 set_init_completed();
3877
3878 LogConfiguration::post_initialize();
3879 Metaspace::post_initialize();
3880
3881 HOTSPOT_VM_INIT_END();
3882
3883 // record VM initialization completion time
3884 #if INCLUDE_MANAGEMENT
3885 Management::record_vm_init_completed();
3886 #endif // INCLUDE_MANAGEMENT
3887
3888 // Signal Dispatcher needs to be started before VMInit event is posted
3889 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3890
3891 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3892 if (!DisableAttachMechanism) {
3893 AttachListener::vm_start();
3894 if (StartAttachListener || AttachListener::init_at_startup()) {
3895 AttachListener::init();
3896 }
3897 }
3898
3899 // Launch -Xrun agents
3900 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3901 // back-end can launch with -Xdebug -Xrunjdwp.
3902 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3903 create_vm_init_libraries();
3904 }
3905
3906 if (CleanChunkPoolAsync) {
3907 Chunk::start_chunk_pool_cleaner_task();
3908 }
3909
3910 // initialize compiler(s)
3911 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3912 #if INCLUDE_JVMCI
3913 bool force_JVMCI_intialization = false;
3914 if (EnableJVMCI) {
3915 // Initialize JVMCI eagerly when it is explicitly requested.
3916 // Or when JVMCIPrintProperties is enabled.
3917 // The JVMCI Java initialization code will read this flag and
3918 // do the printing if it's set.
3919 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3920
3921 if (!force_JVMCI_intialization) {
3922 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3923 // compilations via JVMCI will not actually block until JVMCI is initialized.
3924 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3925 }
3926 }
3927 #endif
3928 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3929 // Postpone completion of compiler initialization to after JVMCI
3930 // is initialized to avoid timeouts of blocking compilations.
3931 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3932 CompileBroker::compilation_init_phase2();
3933 }
3934 #endif
3935
3936 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3937 // It is done after compilers are initialized, because otherwise compilations of
3938 // signature polymorphic MH intrinsics can be missed
3939 // (see SystemDictionary::find_method_handle_intrinsic).
3940 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3941
3942 // This will initialize the module system. Only java.base classes can be
3943 // loaded until phase 2 completes
3944 call_initPhase2(CHECK_JNI_ERR);
3945
3946 // Always call even when there are not JVMTI environments yet, since environments
3947 // may be attached late and JVMTI must track phases of VM execution
3948 JvmtiExport::enter_start_phase();
3949
3950 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3951 JvmtiExport::post_vm_start();
3952
3953 // Final system initialization including security manager and system class loader
3954 call_initPhase3(CHECK_JNI_ERR);
3955
3956 // cache the system and platform class loaders
3957 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3958
3959 #if INCLUDE_CDS
3960 if (DumpSharedSpaces) {
3961 // capture the module path info from the ModuleEntryTable
3962 ClassLoader::initialize_module_path(THREAD);
3963 }
3964 #endif
3965
3966 #if INCLUDE_JVMCI
3967 if (force_JVMCI_intialization) {
3968 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3969 CompileBroker::compilation_init_phase2();
3970 }
3971 #endif
3972
3973 // Always call even when there are not JVMTI environments yet, since environments
3974 // may be attached late and JVMTI must track phases of VM execution
3975 JvmtiExport::enter_live_phase();
3976
3977 // Make perfmemory accessible
3978 PerfMemory::set_accessible(true);
3979
3980 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3981 JvmtiExport::post_vm_initialized();
3982
3983 JFR_ONLY(Jfr::on_vm_start();)
3984
3985 #if INCLUDE_MANAGEMENT
3986 Management::initialize(THREAD);
3987
3988 if (HAS_PENDING_EXCEPTION) {
3989 // management agent fails to start possibly due to
3990 // configuration problem and is responsible for printing
3991 // stack trace if appropriate. Simply exit VM.
3992 vm_exit(1);
3993 }
3994 #endif // INCLUDE_MANAGEMENT
3995
3996 if (MemProfiling) MemProfiler::engage();
3997 StatSampler::engage();
3998 if (CheckJNICalls) JniPeriodicChecker::engage();
3999
4000 BiasedLocking::init();
4001
4002 #if INCLUDE_RTM_OPT
4003 RTMLockingCounters::init();
4004 #endif
4005
4006 if (JDK_Version::current().post_vm_init_hook_enabled()) {
4007 call_postVMInitHook(THREAD);
4008 // The Java side of PostVMInitHook.run must deal with all
4009 // exceptions and provide means of diagnosis.
4010 if (HAS_PENDING_EXCEPTION) {
4011 CLEAR_PENDING_EXCEPTION;
4012 }
4013 }
4014
4015 {
4016 MutexLocker ml(PeriodicTask_lock);
4017 // Make sure the WatcherThread can be started by WatcherThread::start()
4018 // or by dynamic enrollment.
4019 WatcherThread::make_startable();
4020 // Start up the WatcherThread if there are any periodic tasks
4021 // NOTE: All PeriodicTasks should be registered by now. If they
4022 // aren't, late joiners might appear to start slowly (we might
4023 // take a while to process their first tick).
4024 if (PeriodicTask::num_tasks() > 0) {
4025 WatcherThread::start();
4026 }
4027 }
4028
4029 create_vm_timer.end();
4030 #ifdef ASSERT
4031 _vm_complete = true;
4032 #endif
4033
4034 if (DumpSharedSpaces) {
4035 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4036 ShouldNotReachHere();
4037 }
4038
4039 return JNI_OK;
4040 }
4041
4042 // type for the Agent_OnLoad and JVM_OnLoad entry points
4043 extern "C" {
4044 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4045 }
4046 // Find a command line agent library and return its entry point for
4047 // -agentlib: -agentpath: -Xrun
4048 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4049 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4050 const char *on_load_symbols[],
4051 size_t num_symbol_entries) {
4052 OnLoadEntry_t on_load_entry = NULL;
4053 void *library = NULL;
4054
4055 if (!agent->valid()) {
4056 char buffer[JVM_MAXPATHLEN];
4057 char ebuf[1024] = "";
4058 const char *name = agent->name();
4059 const char *msg = "Could not find agent library ";
4060
4061 // First check to see if agent is statically linked into executable
4062 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4063 library = agent->os_lib();
4064 } else if (agent->is_absolute_path()) {
4065 library = os::dll_load(name, ebuf, sizeof ebuf);
4066 if (library == NULL) {
4067 const char *sub_msg = " in absolute path, with error: ";
4068 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4069 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4070 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4071 // If we can't find the agent, exit.
4072 vm_exit_during_initialization(buf, NULL);
4073 FREE_C_HEAP_ARRAY(char, buf);
4074 }
4075 } else {
4076 // Try to load the agent from the standard dll directory
4077 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4078 name)) {
4079 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4080 }
4081 if (library == NULL) { // Try the library path directory.
4082 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4083 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4084 }
4085 if (library == NULL) {
4086 const char *sub_msg = " on the library path, with error: ";
4087 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4088
4089 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4090 strlen(ebuf) + strlen(sub_msg2) + 1;
4091 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4092 if (!agent->is_instrument_lib()) {
4093 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4094 } else {
4095 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4096 }
4097 // If we can't find the agent, exit.
4098 vm_exit_during_initialization(buf, NULL);
4099 FREE_C_HEAP_ARRAY(char, buf);
4100 }
4101 }
4102 }
4103 agent->set_os_lib(library);
4104 agent->set_valid();
4105 }
4106
4107 // Find the OnLoad function.
4108 on_load_entry =
4109 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4110 false,
4111 on_load_symbols,
4112 num_symbol_entries));
4113 return on_load_entry;
4114 }
4115
4116 // Find the JVM_OnLoad entry point
4117 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4118 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4119 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4120 }
4121
4122 // Find the Agent_OnLoad entry point
4123 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4124 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4125 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4126 }
4127
4128 // For backwards compatibility with -Xrun
4129 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4130 // treated like -agentpath:
4131 // Must be called before agent libraries are created
4132 void Threads::convert_vm_init_libraries_to_agents() {
4133 AgentLibrary* agent;
4134 AgentLibrary* next;
4135
4136 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4137 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4138 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4139
4140 // If there is an JVM_OnLoad function it will get called later,
4141 // otherwise see if there is an Agent_OnLoad
4142 if (on_load_entry == NULL) {
4143 on_load_entry = lookup_agent_on_load(agent);
4144 if (on_load_entry != NULL) {
4145 // switch it to the agent list -- so that Agent_OnLoad will be called,
4146 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4147 Arguments::convert_library_to_agent(agent);
4148 } else {
4149 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4150 }
4151 }
4152 }
4153 }
4154
4155 // Create agents for -agentlib: -agentpath: and converted -Xrun
4156 // Invokes Agent_OnLoad
4157 // Called very early -- before JavaThreads exist
4158 void Threads::create_vm_init_agents() {
4159 extern struct JavaVM_ main_vm;
4160 AgentLibrary* agent;
4161
4162 JvmtiExport::enter_onload_phase();
4163
4164 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4165 // CDS dumping does not support native JVMTI agent.
4166 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4167 if (DumpSharedSpaces) {
4168 if(!agent->is_instrument_lib()) {
4169 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4170 } else if (!AllowArchivingWithJavaAgent) {
4171 vm_exit_during_cds_dumping(
4172 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4173 }
4174 }
4175
4176 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4177
4178 if (on_load_entry != NULL) {
4179 // Invoke the Agent_OnLoad function
4180 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4181 if (err != JNI_OK) {
4182 vm_exit_during_initialization("agent library failed to init", agent->name());
4183 }
4184 } else {
4185 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4186 }
4187 }
4188
4189 JvmtiExport::enter_primordial_phase();
4190 }
4191
4192 extern "C" {
4193 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4194 }
4195
4196 void Threads::shutdown_vm_agents() {
4197 // Send any Agent_OnUnload notifications
4198 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4199 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4200 extern struct JavaVM_ main_vm;
4201 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4202
4203 // Find the Agent_OnUnload function.
4204 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4205 os::find_agent_function(agent,
4206 false,
4207 on_unload_symbols,
4208 num_symbol_entries));
4209
4210 // Invoke the Agent_OnUnload function
4211 if (unload_entry != NULL) {
4212 JavaThread* thread = JavaThread::current();
4213 ThreadToNativeFromVM ttn(thread);
4214 HandleMark hm(thread);
4215 (*unload_entry)(&main_vm);
4216 }
4217 }
4218 }
4219
4220 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4221 // Invokes JVM_OnLoad
4222 void Threads::create_vm_init_libraries() {
4223 extern struct JavaVM_ main_vm;
4224 AgentLibrary* agent;
4225
4226 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4227 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4228
4229 if (on_load_entry != NULL) {
4230 // Invoke the JVM_OnLoad function
4231 JavaThread* thread = JavaThread::current();
4232 ThreadToNativeFromVM ttn(thread);
4233 HandleMark hm(thread);
4234 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4235 if (err != JNI_OK) {
4236 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4237 }
4238 } else {
4239 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4240 }
4241 }
4242 }
4243
4244
4245 // Last thread running calls java.lang.Shutdown.shutdown()
4246 void JavaThread::invoke_shutdown_hooks() {
4247 HandleMark hm(this);
4248
4249 // We could get here with a pending exception, if so clear it now.
4250 if (this->has_pending_exception()) {
4251 this->clear_pending_exception();
4252 }
4253
4254 EXCEPTION_MARK;
4255 Klass* shutdown_klass =
4256 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4257 THREAD);
4258 if (shutdown_klass != NULL) {
4259 // SystemDictionary::resolve_or_null will return null if there was
4260 // an exception. If we cannot load the Shutdown class, just don't
4261 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4262 // won't be run. Note that if a shutdown hook was registered,
4263 // the Shutdown class would have already been loaded
4264 // (Runtime.addShutdownHook will load it).
4265 JavaValue result(T_VOID);
4266 JavaCalls::call_static(&result,
4267 shutdown_klass,
4268 vmSymbols::shutdown_method_name(),
4269 vmSymbols::void_method_signature(),
4270 THREAD);
4271 }
4272 CLEAR_PENDING_EXCEPTION;
4273 }
4274
4275 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4276 // the program falls off the end of main(). Another VM exit path is through
4277 // vm_exit() when the program calls System.exit() to return a value or when
4278 // there is a serious error in VM. The two shutdown paths are not exactly
4279 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4280 // and VM_Exit op at VM level.
4281 //
4282 // Shutdown sequence:
4283 // + Shutdown native memory tracking if it is on
4284 // + Wait until we are the last non-daemon thread to execute
4285 // <-- every thing is still working at this moment -->
4286 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4287 // shutdown hooks
4288 // + Call before_exit(), prepare for VM exit
4289 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4290 // currently the only user of this mechanism is File.deleteOnExit())
4291 // > stop StatSampler, watcher thread, CMS threads,
4292 // post thread end and vm death events to JVMTI,
4293 // stop signal thread
4294 // + Call JavaThread::exit(), it will:
4295 // > release JNI handle blocks, remove stack guard pages
4296 // > remove this thread from Threads list
4297 // <-- no more Java code from this thread after this point -->
4298 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4299 // the compiler threads at safepoint
4300 // <-- do not use anything that could get blocked by Safepoint -->
4301 // + Disable tracing at JNI/JVM barriers
4302 // + Set _vm_exited flag for threads that are still running native code
4303 // + Call exit_globals()
4304 // > deletes tty
4305 // > deletes PerfMemory resources
4306 // + Delete this thread
4307 // + Return to caller
4308
4309 bool Threads::destroy_vm() {
4310 JavaThread* thread = JavaThread::current();
4311
4312 #ifdef ASSERT
4313 _vm_complete = false;
4314 #endif
4315 // Wait until we are the last non-daemon thread to execute
4316 { MutexLocker nu(Threads_lock);
4317 while (Threads::number_of_non_daemon_threads() > 1)
4318 // This wait should make safepoint checks, wait without a timeout,
4319 // and wait as a suspend-equivalent condition.
4320 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4321 Mutex::_as_suspend_equivalent_flag);
4322 }
4323
4324 EventShutdown e;
4325 if (e.should_commit()) {
4326 e.set_reason("No remaining non-daemon Java threads");
4327 e.commit();
4328 }
4329
4330 // Hang forever on exit if we are reporting an error.
4331 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4332 os::infinite_sleep();
4333 }
4334 os::wait_for_keypress_at_exit();
4335
4336 // run Java level shutdown hooks
4337 thread->invoke_shutdown_hooks();
4338
4339 before_exit(thread);
4340
4341 thread->exit(true);
4342
4343 // Stop VM thread.
4344 {
4345 // 4945125 The vm thread comes to a safepoint during exit.
4346 // GC vm_operations can get caught at the safepoint, and the
4347 // heap is unparseable if they are caught. Grab the Heap_lock
4348 // to prevent this. The GC vm_operations will not be able to
4349 // queue until after the vm thread is dead. After this point,
4350 // we'll never emerge out of the safepoint before the VM exits.
4351
4352 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4353
4354 VMThread::wait_for_vm_thread_exit();
4355 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4356 VMThread::destroy();
4357 }
4358
4359 // Now, all Java threads are gone except daemon threads. Daemon threads
4360 // running Java code or in VM are stopped by the Safepoint. However,
4361 // daemon threads executing native code are still running. But they
4362 // will be stopped at native=>Java/VM barriers. Note that we can't
4363 // simply kill or suspend them, as it is inherently deadlock-prone.
4364
4365 VM_Exit::set_vm_exited();
4366
4367 // Clean up ideal graph printers after the VMThread has started
4368 // the final safepoint which will block all the Compiler threads.
4369 // Note that this Thread has already logically exited so the
4370 // clean_up() function's use of a JavaThreadIteratorWithHandle
4371 // would be a problem except set_vm_exited() has remembered the
4372 // shutdown thread which is granted a policy exception.
4373 #if defined(COMPILER2) && !defined(PRODUCT)
4374 IdealGraphPrinter::clean_up();
4375 #endif
4376
4377 notify_vm_shutdown();
4378
4379 // exit_globals() will delete tty
4380 exit_globals();
4381
4382 // We are after VM_Exit::set_vm_exited() so we can't call
4383 // thread->smr_delete() or we will block on the Threads_lock.
4384 // Deleting the shutdown thread here is safe because another
4385 // JavaThread cannot have an active ThreadsListHandle for
4386 // this JavaThread.
4387 delete thread;
4388
4389 #if INCLUDE_JVMCI
4390 if (JVMCICounterSize > 0) {
4391 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4392 }
4393 #endif
4394
4395 LogConfiguration::finalize();
4396
4397 return true;
4398 }
4399
4400
4401 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4402 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4403 return is_supported_jni_version(version);
4404 }
4405
4406
4407 jboolean Threads::is_supported_jni_version(jint version) {
4408 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4409 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4410 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4411 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4412 if (version == JNI_VERSION_9) return JNI_TRUE;
4413 if (version == JNI_VERSION_10) return JNI_TRUE;
4414 return JNI_FALSE;
4415 }
4416
4417
4418 void Threads::add(JavaThread* p, bool force_daemon) {
4419 // The threads lock must be owned at this point
4420 assert(Threads_lock->owned_by_self(), "must have threads lock");
4421
4422 BarrierSet::barrier_set()->on_thread_attach(p);
4423
4424 p->set_next(_thread_list);
4425 _thread_list = p;
4426
4427 // Once a JavaThread is added to the Threads list, smr_delete() has
4428 // to be used to delete it. Otherwise we can just delete it directly.
4429 p->set_on_thread_list();
4430
4431 _number_of_threads++;
4432 oop threadObj = p->threadObj();
4433 bool daemon = true;
4434 // Bootstrapping problem: threadObj can be null for initial
4435 // JavaThread (or for threads attached via JNI)
4436 if ((!force_daemon) && !is_daemon((threadObj))) {
4437 _number_of_non_daemon_threads++;
4438 daemon = false;
4439 }
4440
4441 ThreadService::add_thread(p, daemon);
4442
4443 // Maintain fast thread list
4444 ThreadsSMRSupport::add_thread(p);
4445
4446 // Possible GC point.
4447 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4448 }
4449
4450 void Threads::remove(JavaThread* p) {
4451
4452 // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4453 ObjectSynchronizer::omFlush(p);
4454
4455 // Extra scope needed for Thread_lock, so we can check
4456 // that we do not remove thread without safepoint code notice
4457 { MutexLocker ml(Threads_lock);
4458
4459 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4460
4461 // Maintain fast thread list
4462 ThreadsSMRSupport::remove_thread(p);
4463
4464 JavaThread* current = _thread_list;
4465 JavaThread* prev = NULL;
4466
4467 while (current != p) {
4468 prev = current;
4469 current = current->next();
4470 }
4471
4472 if (prev) {
4473 prev->set_next(current->next());
4474 } else {
4475 _thread_list = p->next();
4476 }
4477
4478 _number_of_threads--;
4479 oop threadObj = p->threadObj();
4480 bool daemon = true;
4481 if (!is_daemon(threadObj)) {
4482 _number_of_non_daemon_threads--;
4483 daemon = false;
4484
4485 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4486 // on destroy_vm will wake up.
4487 if (number_of_non_daemon_threads() == 1) {
4488 Threads_lock->notify_all();
4489 }
4490 }
4491 ThreadService::remove_thread(p, daemon);
4492
4493 // Make sure that safepoint code disregard this thread. This is needed since
4494 // the thread might mess around with locks after this point. This can cause it
4495 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4496 // of this thread since it is removed from the queue.
4497 p->set_terminated_value();
4498 } // unlock Threads_lock
4499
4500 // Since Events::log uses a lock, we grab it outside the Threads_lock
4501 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4502 }
4503
4504 // Operations on the Threads list for GC. These are not explicitly locked,
4505 // but the garbage collector must provide a safe context for them to run.
4506 // In particular, these things should never be called when the Threads_lock
4507 // is held by some other thread. (Note: the Safepoint abstraction also
4508 // uses the Threads_lock to guarantee this property. It also makes sure that
4509 // all threads gets blocked when exiting or starting).
4510
4511 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4512 ALL_JAVA_THREADS(p) {
4513 p->oops_do(f, cf);
4514 }
4515 VMThread::vm_thread()->oops_do(f, cf);
4516 }
4517
4518 void Threads::change_thread_claim_parity() {
4519 // Set the new claim parity.
4520 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4521 "Not in range.");
4522 _thread_claim_parity++;
4523 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4524 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4525 "Not in range.");
4526 }
4527
4528 #ifdef ASSERT
4529 void Threads::assert_all_threads_claimed() {
4530 ALL_JAVA_THREADS(p) {
4531 const int thread_parity = p->oops_do_parity();
4532 assert((thread_parity == _thread_claim_parity),
4533 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4534 }
4535 VMThread* vmt = VMThread::vm_thread();
4536 const int thread_parity = vmt->oops_do_parity();
4537 assert((thread_parity == _thread_claim_parity),
4538 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4539 }
4540 #endif // ASSERT
4541
4542 class ParallelOopsDoThreadClosure : public ThreadClosure {
4543 private:
4544 OopClosure* _f;
4545 CodeBlobClosure* _cf;
4546 public:
4547 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4548 void do_thread(Thread* t) {
4549 t->oops_do(_f, _cf);
4550 }
4551 };
4552
4553 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4554 ParallelOopsDoThreadClosure tc(f, cf);
4555 possibly_parallel_threads_do(is_par, &tc);
4556 }
4557
4558 void Threads::nmethods_do(CodeBlobClosure* cf) {
4559 ALL_JAVA_THREADS(p) {
4560 // This is used by the code cache sweeper to mark nmethods that are active
4561 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4562 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4563 if(!p->is_Code_cache_sweeper_thread()) {
4564 p->nmethods_do(cf);
4565 }
4566 }
4567 }
4568
4569 void Threads::metadata_do(MetadataClosure* f) {
4570 ALL_JAVA_THREADS(p) {
4571 p->metadata_do(f);
4572 }
4573 }
4574
4575 class ThreadHandlesClosure : public ThreadClosure {
4576 void (*_f)(Metadata*);
4577 public:
4578 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4579 virtual void do_thread(Thread* thread) {
4580 thread->metadata_handles_do(_f);
4581 }
4582 };
4583
4584 void Threads::metadata_handles_do(void f(Metadata*)) {
4585 // Only walk the Handles in Thread.
4586 ThreadHandlesClosure handles_closure(f);
4587 threads_do(&handles_closure);
4588 }
4589
4590 void Threads::deoptimized_wrt_marked_nmethods() {
4591 ALL_JAVA_THREADS(p) {
4592 p->deoptimized_wrt_marked_nmethods();
4593 }
4594 }
4595
4596
4597 // Get count Java threads that are waiting to enter the specified monitor.
4598 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4599 int count,
4600 address monitor) {
4601 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4602
4603 int i = 0;
4604 DO_JAVA_THREADS(t_list, p) {
4605 if (!p->can_call_java()) continue;
4606
4607 address pending = (address)p->current_pending_monitor();
4608 if (pending == monitor) { // found a match
4609 if (i < count) result->append(p); // save the first count matches
4610 i++;
4611 }
4612 }
4613
4614 return result;
4615 }
4616
4617
4618 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4619 address owner) {
4620 // NULL owner means not locked so we can skip the search
4621 if (owner == NULL) return NULL;
4622
4623 DO_JAVA_THREADS(t_list, p) {
4624 // first, see if owner is the address of a Java thread
4625 if (owner == (address)p) return p;
4626 }
4627
4628 // Cannot assert on lack of success here since this function may be
4629 // used by code that is trying to report useful problem information
4630 // like deadlock detection.
4631 if (UseHeavyMonitors) return NULL;
4632
4633 // If we didn't find a matching Java thread and we didn't force use of
4634 // heavyweight monitors, then the owner is the stack address of the
4635 // Lock Word in the owning Java thread's stack.
4636 //
4637 JavaThread* the_owner = NULL;
4638 DO_JAVA_THREADS(t_list, q) {
4639 if (q->is_lock_owned(owner)) {
4640 the_owner = q;
4641 break;
4642 }
4643 }
4644
4645 // cannot assert on lack of success here; see above comment
4646 return the_owner;
4647 }
4648
4649 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4650 void Threads::print_on(outputStream* st, bool print_stacks,
4651 bool internal_format, bool print_concurrent_locks,
4652 bool print_extended_info) {
4653 char buf[32];
4654 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4655
4656 st->print_cr("Full thread dump %s (%s %s):",
4657 VM_Version::vm_name(),
4658 VM_Version::vm_release(),
4659 VM_Version::vm_info_string());
4660 st->cr();
4661
4662 #if INCLUDE_SERVICES
4663 // Dump concurrent locks
4664 ConcurrentLocksDump concurrent_locks;
4665 if (print_concurrent_locks) {
4666 concurrent_locks.dump_at_safepoint();
4667 }
4668 #endif // INCLUDE_SERVICES
4669
4670 ThreadsSMRSupport::print_info_on(st);
4671 st->cr();
4672
4673 ALL_JAVA_THREADS(p) {
4674 ResourceMark rm;
4675 p->print_on(st, print_extended_info);
4676 if (print_stacks) {
4677 if (internal_format) {
4678 p->trace_stack();
4679 } else {
4680 p->print_stack_on(st);
4681 }
4682 }
4683 st->cr();
4684 #if INCLUDE_SERVICES
4685 if (print_concurrent_locks) {
4686 concurrent_locks.print_locks_on(p, st);
4687 }
4688 #endif // INCLUDE_SERVICES
4689 }
4690
4691 VMThread::vm_thread()->print_on(st);
4692 st->cr();
4693 Universe::heap()->print_gc_threads_on(st);
4694 WatcherThread* wt = WatcherThread::watcher_thread();
4695 if (wt != NULL) {
4696 wt->print_on(st);
4697 st->cr();
4698 }
4699
4700 st->flush();
4701 }
4702
4703 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4704 int buflen, bool* found_current) {
4705 if (this_thread != NULL) {
4706 bool is_current = (current == this_thread);
4707 *found_current = *found_current || is_current;
4708 st->print("%s", is_current ? "=>" : " ");
4709
4710 st->print(PTR_FORMAT, p2i(this_thread));
4711 st->print(" ");
4712 this_thread->print_on_error(st, buf, buflen);
4713 st->cr();
4714 }
4715 }
4716
4717 class PrintOnErrorClosure : public ThreadClosure {
4718 outputStream* _st;
4719 Thread* _current;
4720 char* _buf;
4721 int _buflen;
4722 bool* _found_current;
4723 public:
4724 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4725 int buflen, bool* found_current) :
4726 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4727
4728 virtual void do_thread(Thread* thread) {
4729 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4730 }
4731 };
4732
4733 // Threads::print_on_error() is called by fatal error handler. It's possible
4734 // that VM is not at safepoint and/or current thread is inside signal handler.
4735 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4736 // memory (even in resource area), it might deadlock the error handler.
4737 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4738 int buflen) {
4739 ThreadsSMRSupport::print_info_on(st);
4740 st->cr();
4741
4742 bool found_current = false;
4743 st->print_cr("Java Threads: ( => current thread )");
4744 ALL_JAVA_THREADS(thread) {
4745 print_on_error(thread, st, current, buf, buflen, &found_current);
4746 }
4747 st->cr();
4748
4749 st->print_cr("Other Threads:");
4750 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4751 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4752
4753 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4754 Universe::heap()->gc_threads_do(&print_closure);
4755
4756 if (!found_current) {
4757 st->cr();
4758 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4759 current->print_on_error(st, buf, buflen);
4760 st->cr();
4761 }
4762 st->cr();
4763
4764 st->print_cr("Threads with active compile tasks:");
4765 print_threads_compiling(st, buf, buflen);
4766 }
4767
4768 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4769 ALL_JAVA_THREADS(thread) {
4770 if (thread->is_Compiler_thread()) {
4771 CompilerThread* ct = (CompilerThread*) thread;
4772
4773 // Keep task in local variable for NULL check.
4774 // ct->_task might be set to NULL by concurring compiler thread
4775 // because it completed the compilation. The task is never freed,
4776 // though, just returned to a free list.
4777 CompileTask* task = ct->task();
4778 if (task != NULL) {
4779 thread->print_name_on_error(st, buf, buflen);
4780 st->print(" ");
4781 task->print(st, NULL, short_form, true);
4782 }
4783 }
4784 }
4785 }
4786
4787
4788 // Internal SpinLock and Mutex
4789 // Based on ParkEvent
4790
4791 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4792 //
4793 // We employ SpinLocks _only for low-contention, fixed-length
4794 // short-duration critical sections where we're concerned
4795 // about native mutex_t or HotSpot Mutex:: latency.
4796 // The mux construct provides a spin-then-block mutual exclusion
4797 // mechanism.
4798 //
4799 // Testing has shown that contention on the ListLock guarding gFreeList
4800 // is common. If we implement ListLock as a simple SpinLock it's common
4801 // for the JVM to devolve to yielding with little progress. This is true
4802 // despite the fact that the critical sections protected by ListLock are
4803 // extremely short.
4804 //
4805 // TODO-FIXME: ListLock should be of type SpinLock.
4806 // We should make this a 1st-class type, integrated into the lock
4807 // hierarchy as leaf-locks. Critically, the SpinLock structure
4808 // should have sufficient padding to avoid false-sharing and excessive
4809 // cache-coherency traffic.
4810
4811
4812 typedef volatile int SpinLockT;
4813
4814 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4815 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4816 return; // normal fast-path return
4817 }
4818
4819 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4820 int ctr = 0;
4821 int Yields = 0;
4822 for (;;) {
4823 while (*adr != 0) {
4824 ++ctr;
4825 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4826 if (Yields > 5) {
4827 os::naked_short_sleep(1);
4828 } else {
4829 os::naked_yield();
4830 ++Yields;
4831 }
4832 } else {
4833 SpinPause();
4834 }
4835 }
4836 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4837 }
4838 }
4839
4840 void Thread::SpinRelease(volatile int * adr) {
4841 assert(*adr != 0, "invariant");
4842 OrderAccess::fence(); // guarantee at least release consistency.
4843 // Roach-motel semantics.
4844 // It's safe if subsequent LDs and STs float "up" into the critical section,
4845 // but prior LDs and STs within the critical section can't be allowed
4846 // to reorder or float past the ST that releases the lock.
4847 // Loads and stores in the critical section - which appear in program
4848 // order before the store that releases the lock - must also appear
4849 // before the store that releases the lock in memory visibility order.
4850 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4851 // the ST of 0 into the lock-word which releases the lock, so fence
4852 // more than covers this on all platforms.
4853 *adr = 0;
4854 }
4855
4856 // muxAcquire and muxRelease:
4857 //
4858 // * muxAcquire and muxRelease support a single-word lock-word construct.
4859 // The LSB of the word is set IFF the lock is held.
4860 // The remainder of the word points to the head of a singly-linked list
4861 // of threads blocked on the lock.
4862 //
4863 // * The current implementation of muxAcquire-muxRelease uses its own
4864 // dedicated Thread._MuxEvent instance. If we're interested in
4865 // minimizing the peak number of extant ParkEvent instances then
4866 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4867 // as certain invariants were satisfied. Specifically, care would need
4868 // to be taken with regards to consuming unpark() "permits".
4869 // A safe rule of thumb is that a thread would never call muxAcquire()
4870 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4871 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4872 // consume an unpark() permit intended for monitorenter, for instance.
4873 // One way around this would be to widen the restricted-range semaphore
4874 // implemented in park(). Another alternative would be to provide
4875 // multiple instances of the PlatformEvent() for each thread. One
4876 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4877 //
4878 // * Usage:
4879 // -- Only as leaf locks
4880 // -- for short-term locking only as muxAcquire does not perform
4881 // thread state transitions.
4882 //
4883 // Alternatives:
4884 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4885 // but with parking or spin-then-park instead of pure spinning.
4886 // * Use Taura-Oyama-Yonenzawa locks.
4887 // * It's possible to construct a 1-0 lock if we encode the lockword as
4888 // (List,LockByte). Acquire will CAS the full lockword while Release
4889 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4890 // acquiring threads use timers (ParkTimed) to detect and recover from
4891 // the stranding window. Thread/Node structures must be aligned on 256-byte
4892 // boundaries by using placement-new.
4893 // * Augment MCS with advisory back-link fields maintained with CAS().
4894 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4895 // The validity of the backlinks must be ratified before we trust the value.
4896 // If the backlinks are invalid the exiting thread must back-track through the
4897 // the forward links, which are always trustworthy.
4898 // * Add a successor indication. The LockWord is currently encoded as
4899 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4900 // to provide the usual futile-wakeup optimization.
4901 // See RTStt for details.
4902 //
4903
4904
4905 const intptr_t LOCKBIT = 1;
4906
4907 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4908 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4909 if (w == 0) return;
4910 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4911 return;
4912 }
4913
4914 ParkEvent * const Self = Thread::current()->_MuxEvent;
4915 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4916 for (;;) {
4917 int its = (os::is_MP() ? 100 : 0) + 1;
4918
4919 // Optional spin phase: spin-then-park strategy
4920 while (--its >= 0) {
4921 w = *Lock;
4922 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4923 return;
4924 }
4925 }
4926
4927 Self->reset();
4928 Self->OnList = intptr_t(Lock);
4929 // The following fence() isn't _strictly necessary as the subsequent
4930 // CAS() both serializes execution and ratifies the fetched *Lock value.
4931 OrderAccess::fence();
4932 for (;;) {
4933 w = *Lock;
4934 if ((w & LOCKBIT) == 0) {
4935 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4936 Self->OnList = 0; // hygiene - allows stronger asserts
4937 return;
4938 }
4939 continue; // Interference -- *Lock changed -- Just retry
4940 }
4941 assert(w & LOCKBIT, "invariant");
4942 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4943 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4944 }
4945
4946 while (Self->OnList != 0) {
4947 Self->park();
4948 }
4949 }
4950 }
4951
4952 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4953 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4954 if (w == 0) return;
4955 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4956 return;
4957 }
4958
4959 ParkEvent * ReleaseAfter = NULL;
4960 if (ev == NULL) {
4961 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4962 }
4963 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4964 for (;;) {
4965 guarantee(ev->OnList == 0, "invariant");
4966 int its = (os::is_MP() ? 100 : 0) + 1;
4967
4968 // Optional spin phase: spin-then-park strategy
4969 while (--its >= 0) {
4970 w = *Lock;
4971 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4972 if (ReleaseAfter != NULL) {
4973 ParkEvent::Release(ReleaseAfter);
4974 }
4975 return;
4976 }
4977 }
4978
4979 ev->reset();
4980 ev->OnList = intptr_t(Lock);
4981 // The following fence() isn't _strictly necessary as the subsequent
4982 // CAS() both serializes execution and ratifies the fetched *Lock value.
4983 OrderAccess::fence();
4984 for (;;) {
4985 w = *Lock;
4986 if ((w & LOCKBIT) == 0) {
4987 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4988 ev->OnList = 0;
4989 // We call ::Release while holding the outer lock, thus
4990 // artificially lengthening the critical section.
4991 // Consider deferring the ::Release() until the subsequent unlock(),
4992 // after we've dropped the outer lock.
4993 if (ReleaseAfter != NULL) {
4994 ParkEvent::Release(ReleaseAfter);
4995 }
4996 return;
4997 }
4998 continue; // Interference -- *Lock changed -- Just retry
4999 }
5000 assert(w & LOCKBIT, "invariant");
5001 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5002 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5003 }
5004
5005 while (ev->OnList != 0) {
5006 ev->park();
5007 }
5008 }
5009 }
5010
5011 // Release() must extract a successor from the list and then wake that thread.
5012 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5013 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5014 // Release() would :
5015 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5016 // (B) Extract a successor from the private list "in-hand"
5017 // (C) attempt to CAS() the residual back into *Lock over null.
5018 // If there were any newly arrived threads and the CAS() would fail.
5019 // In that case Release() would detach the RATs, re-merge the list in-hand
5020 // with the RATs and repeat as needed. Alternately, Release() might
5021 // detach and extract a successor, but then pass the residual list to the wakee.
5022 // The wakee would be responsible for reattaching and remerging before it
5023 // competed for the lock.
5024 //
5025 // Both "pop" and DMR are immune from ABA corruption -- there can be
5026 // multiple concurrent pushers, but only one popper or detacher.
5027 // This implementation pops from the head of the list. This is unfair,
5028 // but tends to provide excellent throughput as hot threads remain hot.
5029 // (We wake recently run threads first).
5030 //
5031 // All paths through muxRelease() will execute a CAS.
5032 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5033 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5034 // executed within the critical section are complete and globally visible before the
5035 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5036 void Thread::muxRelease(volatile intptr_t * Lock) {
5037 for (;;) {
5038 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5039 assert(w & LOCKBIT, "invariant");
5040 if (w == LOCKBIT) return;
5041 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5042 assert(List != NULL, "invariant");
5043 assert(List->OnList == intptr_t(Lock), "invariant");
5044 ParkEvent * const nxt = List->ListNext;
5045 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5046
5047 // The following CAS() releases the lock and pops the head element.
5048 // The CAS() also ratifies the previously fetched lock-word value.
5049 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5050 continue;
5051 }
5052 List->OnList = 0;
5053 OrderAccess::fence();
5054 List->unpark();
5055 return;
5056 }
5057 }
5058
5059
5060 void Threads::verify() {
5061 ALL_JAVA_THREADS(p) {
5062 p->verify();
5063 }
5064 VMThread* thread = VMThread::vm_thread();
5065 if (thread != NULL) thread->verify();
5066 }