1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/scopeDesc.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "compiler/compileTask.hpp"
36 #include "gc/shared/barrierSet.hpp"
37 #include "gc/shared/gcId.hpp"
38 #include "gc/shared/gcLocker.inline.hpp"
39 #include "gc/shared/workgroup.hpp"
40 #include "interpreter/interpreter.hpp"
41 #include "interpreter/linkResolver.hpp"
42 #include "interpreter/oopMapCache.hpp"
43 #include "jfr/jfrEvents.hpp"
44 #include "jvmtifiles/jvmtiEnv.hpp"
45 #include "logging/log.hpp"
46 #include "logging/logConfiguration.hpp"
47 #include "logging/logStream.hpp"
48 #include "memory/allocation.inline.hpp"
49 #include "memory/metaspaceShared.hpp"
50 #include "memory/oopFactory.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "memory/universe.hpp"
53 #include "oops/access.inline.hpp"
54 #include "oops/instanceKlass.hpp"
55 #include "oops/objArrayOop.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/symbol.hpp"
58 #include "oops/typeArrayOop.inline.hpp"
59 #include "oops/verifyOopClosure.hpp"
60 #include "prims/jvm_misc.hpp"
61 #include "prims/jvmtiExport.hpp"
62 #include "prims/jvmtiThreadState.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/fieldDescriptor.inline.hpp"
67 #include "runtime/flags/jvmFlagConstraintList.hpp"
68 #include "runtime/flags/jvmFlagRangeList.hpp"
69 #include "runtime/flags/jvmFlagWriteableList.hpp"
70 #include "runtime/deoptimization.hpp"
71 #include "runtime/frame.inline.hpp"
72 #include "runtime/handles.inline.hpp"
73 #include "runtime/handshake.hpp"
74 #include "runtime/init.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/jniHandles.inline.hpp"
79 #include "runtime/jniPeriodicChecker.hpp"
80 #include "runtime/memprofiler.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/objectMonitor.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/osThread.hpp"
85 #include "runtime/prefetch.inline.hpp"
86 #include "runtime/safepoint.hpp"
87 #include "runtime/safepointMechanism.inline.hpp"
88 #include "runtime/safepointVerifiers.hpp"
89 #include "runtime/sharedRuntime.hpp"
90 #include "runtime/statSampler.hpp"
91 #include "runtime/stubRoutines.hpp"
92 #include "runtime/sweeper.hpp"
93 #include "runtime/task.hpp"
94 #include "runtime/thread.inline.hpp"
95 #include "runtime/threadCritical.hpp"
96 #include "runtime/threadSMR.inline.hpp"
97 #include "runtime/threadStatisticalInfo.hpp"
98 #include "runtime/timer.hpp"
99 #include "runtime/timerTrace.hpp"
100 #include "runtime/vframe.inline.hpp"
101 #include "runtime/vframeArray.hpp"
102 #include "runtime/vframe_hp.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "runtime/vmOperations.hpp"
105 #include "runtime/vm_version.hpp"
106 #include "services/attachListener.hpp"
107 #include "services/management.hpp"
108 #include "services/memTracker.hpp"
109 #include "services/threadService.hpp"
110 #include "utilities/align.hpp"
111 #include "utilities/copy.hpp"
112 #include "utilities/defaultStream.hpp"
113 #include "utilities/dtrace.hpp"
114 #include "utilities/events.hpp"
115 #include "utilities/macros.hpp"
116 #include "utilities/preserveException.hpp"
117 #include "utilities/singleWriterSynchronizer.hpp"
118 #include "utilities/vmError.hpp"
119 #if INCLUDE_JVMCI
120 #include "jvmci/jvmci.hpp"
121 #include "jvmci/jvmciEnv.hpp"
122 #endif
123 #ifdef COMPILER1
124 #include "c1/c1_Compiler.hpp"
125 #endif
126 #ifdef COMPILER2
127 #include "opto/c2compiler.hpp"
128 #include "opto/idealGraphPrinter.hpp"
129 #endif
130 #if INCLUDE_RTM_OPT
131 #include "runtime/rtmLocking.hpp"
132 #endif
133 #if INCLUDE_JFR
134 #include "jfr/jfr.hpp"
135 #endif
136
137 // Initialization after module runtime initialization
138 void universe_post_module_init(); // must happen after call_initPhase2
139
140 #ifdef DTRACE_ENABLED
141
142 // Only bother with this argument setup if dtrace is available
143
144 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
145 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
146
147 #define DTRACE_THREAD_PROBE(probe, javathread) \
148 { \
149 ResourceMark rm(this); \
150 int len = 0; \
151 const char* name = (javathread)->get_thread_name(); \
152 len = strlen(name); \
153 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
154 (char *) name, len, \
155 java_lang_Thread::thread_id((javathread)->threadObj()), \
156 (uintptr_t) (javathread)->osthread()->thread_id(), \
157 java_lang_Thread::is_daemon((javathread)->threadObj())); \
158 }
159
160 #else // ndef DTRACE_ENABLED
161
162 #define DTRACE_THREAD_PROBE(probe, javathread)
163
164 #endif // ndef DTRACE_ENABLED
165
166 #ifndef USE_LIBRARY_BASED_TLS_ONLY
167 // Current thread is maintained as a thread-local variable
168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
169 #endif
170
171 // ======= Thread ========
172 // Support for forcing alignment of thread objects for biased locking
173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
174 if (UseBiasedLocking) {
175 const int alignment = markOopDesc::biased_lock_alignment;
176 size_t aligned_size = size + (alignment - sizeof(intptr_t));
177 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
178 : AllocateHeap(aligned_size, flags, CURRENT_PC,
179 AllocFailStrategy::RETURN_NULL);
180 void* aligned_addr = align_up(real_malloc_addr, alignment);
181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
183 "JavaThread alignment code overflowed allocated storage");
184 if (aligned_addr != real_malloc_addr) {
185 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
186 p2i(real_malloc_addr),
187 p2i(aligned_addr));
188 }
189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
190 return aligned_addr;
191 } else {
192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
193 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
194 }
195 }
196
197 void Thread::operator delete(void* p) {
198 if (UseBiasedLocking) {
199 FreeHeap(((Thread*) p)->_real_malloc_address);
200 } else {
201 FreeHeap(p);
202 }
203 }
204
205 void JavaThread::smr_delete() {
206 if (_on_thread_list) {
207 ThreadsSMRSupport::smr_delete(this);
208 } else {
209 delete this;
210 }
211 }
212
213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
214 // JavaThread
215
216 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
217
218 Thread::Thread() {
219
220 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
221
222 // stack and get_thread
223 set_stack_base(NULL);
224 set_stack_size(0);
225 set_self_raw_id(0);
226 set_lgrp_id(-1);
227 DEBUG_ONLY(clear_suspendible_thread();)
228
229 // allocated data structures
230 set_osthread(NULL);
231 set_resource_area(new (mtThread)ResourceArea());
232 DEBUG_ONLY(_current_resource_mark = NULL;)
233 set_handle_area(new (mtThread) HandleArea(NULL));
234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
235 set_active_handles(NULL);
236 set_free_handle_block(NULL);
237 set_last_handle_mark(NULL);
238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
239
240 // Initial value of zero ==> never claimed.
241 _threads_do_token = 0;
242 _threads_hazard_ptr = NULL;
243 _threads_list_ptr = NULL;
244 _nested_threads_hazard_ptr_cnt = 0;
245 _rcu_counter = 0;
246
247 // the handle mark links itself to last_handle_mark
248 new HandleMark(this);
249
250 // plain initialization
251 debug_only(_owned_locks = NULL;)
252 debug_only(_allow_allocation_count = 0;)
253 NOT_PRODUCT(_allow_safepoint_count = 0;)
254 NOT_PRODUCT(_skip_gcalot = false;)
255 _jvmti_env_iteration_count = 0;
256 set_allocated_bytes(0);
257 _vm_operation_started_count = 0;
258 _vm_operation_completed_count = 0;
259 _current_pending_monitor = NULL;
260 _current_pending_monitor_is_from_java = true;
261 _current_waiting_monitor = NULL;
262 _num_nested_signal = 0;
263 omFreeList = NULL;
264 omFreeCount = 0;
265 omFreeProvision = 32;
266 omInUseList = NULL;
267 omInUseCount = 0;
268
269 #ifdef ASSERT
270 _visited_for_critical_count = false;
271 #endif
272
273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
274 Monitor::_safepoint_check_sometimes);
275 _suspend_flags = 0;
276
277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
278 _hashStateX = os::random();
279 _hashStateY = 842502087;
280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
281 _hashStateW = 273326509;
282
283 _OnTrap = 0;
284 _Stalled = 0;
285 _TypeTag = 0x2BAD;
286
287 // Many of the following fields are effectively final - immutable
288 // Note that nascent threads can't use the Native Monitor-Mutex
289 // construct until the _MutexEvent is initialized ...
290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
291 // we might instead use a stack of ParkEvents that we could provision on-demand.
292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
293 // and ::Release()
294 _ParkEvent = ParkEvent::Allocate(this);
295 _SleepEvent = ParkEvent::Allocate(this);
296 _MuxEvent = ParkEvent::Allocate(this);
297
298 #ifdef CHECK_UNHANDLED_OOPS
299 if (CheckUnhandledOops) {
300 _unhandled_oops = new UnhandledOops(this);
301 }
302 #endif // CHECK_UNHANDLED_OOPS
303 #ifdef ASSERT
304 if (UseBiasedLocking) {
305 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
306 assert(this == _real_malloc_address ||
307 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
308 "bug in forced alignment of thread objects");
309 }
310 #endif // ASSERT
311
312 // Notify the barrier set that a thread is being created. The initial
313 // thread is created before the barrier set is available. The call to
314 // BarrierSet::on_thread_create() for this thread is therefore deferred
315 // to BarrierSet::set_barrier_set().
316 BarrierSet* const barrier_set = BarrierSet::barrier_set();
317 if (barrier_set != NULL) {
318 barrier_set->on_thread_create(this);
319 } else {
320 // Only the main thread should be created before the barrier set
321 // and that happens just before Thread::current is set. No other thread
322 // can attach as the VM is not created yet, so they can't execute this code.
323 // If the main thread creates other threads before the barrier set that is an error.
324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
325 }
326 }
327
328 void Thread::initialize_thread_current() {
329 #ifndef USE_LIBRARY_BASED_TLS_ONLY
330 assert(_thr_current == NULL, "Thread::current already initialized");
331 _thr_current = this;
332 #endif
333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
334 ThreadLocalStorage::set_thread(this);
335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
336 }
337
338 void Thread::clear_thread_current() {
339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
340 #ifndef USE_LIBRARY_BASED_TLS_ONLY
341 _thr_current = NULL;
342 #endif
343 ThreadLocalStorage::set_thread(NULL);
344 }
345
346 void Thread::record_stack_base_and_size() {
347 // Note: at this point, Thread object is not yet initialized. Do not rely on
348 // any members being initialized. Do not rely on Thread::current() being set.
349 // If possible, refrain from doing anything which may crash or assert since
350 // quite probably those crash dumps will be useless.
351 set_stack_base(os::current_stack_base());
352 set_stack_size(os::current_stack_size());
353
354 #ifdef SOLARIS
355 if (os::is_primordial_thread()) {
356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
357 }
358 #endif
359
360 // Set stack limits after thread is initialized.
361 if (is_Java_thread()) {
362 ((JavaThread*) this)->set_stack_overflow_limit();
363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
364 }
365 }
366
367 #if INCLUDE_NMT
368 void Thread::register_thread_stack_with_NMT() {
369 MemTracker::record_thread_stack(stack_end(), stack_size());
370 }
371 #endif // INCLUDE_NMT
372
373 void Thread::call_run() {
374 DEBUG_ONLY(_run_state = CALL_RUN;)
375
376 // At this point, Thread object should be fully initialized and
377 // Thread::current() should be set.
378
379 assert(Thread::current_or_null() != NULL, "current thread is unset");
380 assert(Thread::current_or_null() == this, "current thread is wrong");
381
382 // Perform common initialization actions
383
384 register_thread_stack_with_NMT();
385
386 JFR_ONLY(Jfr::on_thread_start(this);)
387
388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
390 os::current_thread_id(), p2i(stack_base() - stack_size()),
391 p2i(stack_base()), stack_size()/1024);
392
393 // Perform <ChildClass> initialization actions
394 DEBUG_ONLY(_run_state = PRE_RUN;)
395 this->pre_run();
396
397 // Invoke <ChildClass>::run()
398 DEBUG_ONLY(_run_state = RUN;)
399 this->run();
400 // Returned from <ChildClass>::run(). Thread finished.
401
402 // Perform common tear-down actions
403
404 assert(Thread::current_or_null() != NULL, "current thread is unset");
405 assert(Thread::current_or_null() == this, "current thread is wrong");
406
407 // Perform <ChildClass> tear-down actions
408 DEBUG_ONLY(_run_state = POST_RUN;)
409 this->post_run();
410
411 // Note: at this point the thread object may already have deleted itself,
412 // so from here on do not dereference *this*. Not all thread types currently
413 // delete themselves when they terminate. But no thread should ever be deleted
414 // asynchronously with respect to its termination - that is what _run_state can
415 // be used to check.
416
417 assert(Thread::current_or_null() == NULL, "current thread still present");
418 }
419
420 Thread::~Thread() {
421
422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
423 // get started due to errors etc. Any active thread should at least reach post_run
424 // before it is deleted (usually in post_run()).
425 assert(_run_state == PRE_CALL_RUN ||
426 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
427 "_run_state=%d", (int)_run_state);
428
429 // Notify the barrier set that a thread is being destroyed. Note that a barrier
430 // set might not be available if we encountered errors during bootstrapping.
431 BarrierSet* const barrier_set = BarrierSet::barrier_set();
432 if (barrier_set != NULL) {
433 barrier_set->on_thread_destroy(this);
434 }
435
436 // stack_base can be NULL if the thread is never started or exited before
437 // record_stack_base_and_size called. Although, we would like to ensure
438 // that all started threads do call record_stack_base_and_size(), there is
439 // not proper way to enforce that.
440 #if INCLUDE_NMT
441 if (_stack_base != NULL) {
442 MemTracker::release_thread_stack(stack_end(), stack_size());
443 #ifdef ASSERT
444 set_stack_base(NULL);
445 #endif
446 }
447 #endif // INCLUDE_NMT
448
449 // deallocate data structures
450 delete resource_area();
451 // since the handle marks are using the handle area, we have to deallocated the root
452 // handle mark before deallocating the thread's handle area,
453 assert(last_handle_mark() != NULL, "check we have an element");
454 delete last_handle_mark();
455 assert(last_handle_mark() == NULL, "check we have reached the end");
456
457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
458 // We NULL out the fields for good hygiene.
459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
460 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
461 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
462
463 delete handle_area();
464 delete metadata_handles();
465
466 // SR_handler uses this as a termination indicator -
467 // needs to happen before os::free_thread()
468 delete _SR_lock;
469 _SR_lock = NULL;
470
471 // osthread() can be NULL, if creation of thread failed.
472 if (osthread() != NULL) os::free_thread(osthread());
473
474 // Clear Thread::current if thread is deleting itself and it has not
475 // already been done. This must be done before the memory is deallocated.
476 // Needed to ensure JNI correctly detects non-attached threads.
477 if (this == Thread::current_or_null()) {
478 Thread::clear_thread_current();
479 }
480
481 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
482 }
483
484 #ifdef ASSERT
485 // A JavaThread is considered "dangling" if it is not the current
486 // thread, has been added the Threads list, the system is not at a
487 // safepoint and the Thread is not "protected".
488 //
489 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
490 assert(!thread->is_Java_thread() || Thread::current() == thread ||
491 !((JavaThread *) thread)->on_thread_list() ||
492 SafepointSynchronize::is_at_safepoint() ||
493 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
494 "possibility of dangling Thread pointer");
495 }
496 #endif
497
498 ThreadPriority Thread::get_priority(const Thread* const thread) {
499 ThreadPriority priority;
500 // Can return an error!
501 (void)os::get_priority(thread, priority);
502 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
503 return priority;
504 }
505
506 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
507 debug_only(check_for_dangling_thread_pointer(thread);)
508 // Can return an error!
509 (void)os::set_priority(thread, priority);
510 }
511
512
513 void Thread::start(Thread* thread) {
514 // Start is different from resume in that its safety is guaranteed by context or
515 // being called from a Java method synchronized on the Thread object.
516 if (!DisableStartThread) {
517 if (thread->is_Java_thread()) {
518 // Initialize the thread state to RUNNABLE before starting this thread.
519 // Can not set it after the thread started because we do not know the
520 // exact thread state at that time. It could be in MONITOR_WAIT or
521 // in SLEEPING or some other state.
522 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
523 java_lang_Thread::RUNNABLE);
524 }
525 os::start_thread(thread);
526 }
527 }
528
529 // Enqueue a VM_Operation to do the job for us - sometime later
530 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
531 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
532 VMThread::execute(vm_stop);
533 }
534
535
536 // Check if an external suspend request has completed (or has been
537 // cancelled). Returns true if the thread is externally suspended and
538 // false otherwise.
539 //
540 // The bits parameter returns information about the code path through
541 // the routine. Useful for debugging:
542 //
543 // set in is_ext_suspend_completed():
544 // 0x00000001 - routine was entered
545 // 0x00000010 - routine return false at end
546 // 0x00000100 - thread exited (return false)
547 // 0x00000200 - suspend request cancelled (return false)
548 // 0x00000400 - thread suspended (return true)
549 // 0x00001000 - thread is in a suspend equivalent state (return true)
550 // 0x00002000 - thread is native and walkable (return true)
551 // 0x00004000 - thread is native_trans and walkable (needed retry)
552 //
553 // set in wait_for_ext_suspend_completion():
554 // 0x00010000 - routine was entered
555 // 0x00020000 - suspend request cancelled before loop (return false)
556 // 0x00040000 - thread suspended before loop (return true)
557 // 0x00080000 - suspend request cancelled in loop (return false)
558 // 0x00100000 - thread suspended in loop (return true)
559 // 0x00200000 - suspend not completed during retry loop (return false)
560
561 // Helper class for tracing suspend wait debug bits.
562 //
563 // 0x00000100 indicates that the target thread exited before it could
564 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
565 // 0x00080000 each indicate a cancelled suspend request so they don't
566 // count as wait failures either.
567 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
568
569 class TraceSuspendDebugBits : public StackObj {
570 private:
571 JavaThread * jt;
572 bool is_wait;
573 bool called_by_wait; // meaningful when !is_wait
574 uint32_t * bits;
575
576 public:
577 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
578 uint32_t *_bits) {
579 jt = _jt;
580 is_wait = _is_wait;
581 called_by_wait = _called_by_wait;
582 bits = _bits;
583 }
584
585 ~TraceSuspendDebugBits() {
586 if (!is_wait) {
587 #if 1
588 // By default, don't trace bits for is_ext_suspend_completed() calls.
589 // That trace is very chatty.
590 return;
591 #else
592 if (!called_by_wait) {
593 // If tracing for is_ext_suspend_completed() is enabled, then only
594 // trace calls to it from wait_for_ext_suspend_completion()
595 return;
596 }
597 #endif
598 }
599
600 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
601 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
602 MutexLocker ml(Threads_lock); // needed for get_thread_name()
603 ResourceMark rm;
604
605 tty->print_cr(
606 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
607 jt->get_thread_name(), *bits);
608
609 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
610 }
611 }
612 }
613 };
614 #undef DEBUG_FALSE_BITS
615
616
617 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
618 uint32_t *bits) {
619 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
620
621 bool did_trans_retry = false; // only do thread_in_native_trans retry once
622 bool do_trans_retry; // flag to force the retry
623
624 *bits |= 0x00000001;
625
626 do {
627 do_trans_retry = false;
628
629 if (is_exiting()) {
630 // Thread is in the process of exiting. This is always checked
631 // first to reduce the risk of dereferencing a freed JavaThread.
632 *bits |= 0x00000100;
633 return false;
634 }
635
636 if (!is_external_suspend()) {
637 // Suspend request is cancelled. This is always checked before
638 // is_ext_suspended() to reduce the risk of a rogue resume
639 // confusing the thread that made the suspend request.
640 *bits |= 0x00000200;
641 return false;
642 }
643
644 if (is_ext_suspended()) {
645 // thread is suspended
646 *bits |= 0x00000400;
647 return true;
648 }
649
650 // Now that we no longer do hard suspends of threads running
651 // native code, the target thread can be changing thread state
652 // while we are in this routine:
653 //
654 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
655 //
656 // We save a copy of the thread state as observed at this moment
657 // and make our decision about suspend completeness based on the
658 // copy. This closes the race where the thread state is seen as
659 // _thread_in_native_trans in the if-thread_blocked check, but is
660 // seen as _thread_blocked in if-thread_in_native_trans check.
661 JavaThreadState save_state = thread_state();
662
663 if (save_state == _thread_blocked && is_suspend_equivalent()) {
664 // If the thread's state is _thread_blocked and this blocking
665 // condition is known to be equivalent to a suspend, then we can
666 // consider the thread to be externally suspended. This means that
667 // the code that sets _thread_blocked has been modified to do
668 // self-suspension if the blocking condition releases. We also
669 // used to check for CONDVAR_WAIT here, but that is now covered by
670 // the _thread_blocked with self-suspension check.
671 //
672 // Return true since we wouldn't be here unless there was still an
673 // external suspend request.
674 *bits |= 0x00001000;
675 return true;
676 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
677 // Threads running native code will self-suspend on native==>VM/Java
678 // transitions. If its stack is walkable (should always be the case
679 // unless this function is called before the actual java_suspend()
680 // call), then the wait is done.
681 *bits |= 0x00002000;
682 return true;
683 } else if (!called_by_wait && !did_trans_retry &&
684 save_state == _thread_in_native_trans &&
685 frame_anchor()->walkable()) {
686 // The thread is transitioning from thread_in_native to another
687 // thread state. check_safepoint_and_suspend_for_native_trans()
688 // will force the thread to self-suspend. If it hasn't gotten
689 // there yet we may have caught the thread in-between the native
690 // code check above and the self-suspend. Lucky us. If we were
691 // called by wait_for_ext_suspend_completion(), then it
692 // will be doing the retries so we don't have to.
693 //
694 // Since we use the saved thread state in the if-statement above,
695 // there is a chance that the thread has already transitioned to
696 // _thread_blocked by the time we get here. In that case, we will
697 // make a single unnecessary pass through the logic below. This
698 // doesn't hurt anything since we still do the trans retry.
699
700 *bits |= 0x00004000;
701
702 // Once the thread leaves thread_in_native_trans for another
703 // thread state, we break out of this retry loop. We shouldn't
704 // need this flag to prevent us from getting back here, but
705 // sometimes paranoia is good.
706 did_trans_retry = true;
707
708 // We wait for the thread to transition to a more usable state.
709 for (int i = 1; i <= SuspendRetryCount; i++) {
710 // We used to do an "os::yield_all(i)" call here with the intention
711 // that yielding would increase on each retry. However, the parameter
712 // is ignored on Linux which means the yield didn't scale up. Waiting
713 // on the SR_lock below provides a much more predictable scale up for
714 // the delay. It also provides a simple/direct point to check for any
715 // safepoint requests from the VMThread
716
717 // temporarily drops SR_lock while doing wait with safepoint check
718 // (if we're a JavaThread - the WatcherThread can also call this)
719 // and increase delay with each retry
720 if (Thread::current()->is_Java_thread()) {
721 SR_lock()->wait(i * delay);
722 } else {
723 SR_lock()->wait_without_safepoint_check(i * delay);
724 }
725
726 // check the actual thread state instead of what we saved above
727 if (thread_state() != _thread_in_native_trans) {
728 // the thread has transitioned to another thread state so
729 // try all the checks (except this one) one more time.
730 do_trans_retry = true;
731 break;
732 }
733 } // end retry loop
734
735
736 }
737 } while (do_trans_retry);
738
739 *bits |= 0x00000010;
740 return false;
741 }
742
743 // Wait for an external suspend request to complete (or be cancelled).
744 // Returns true if the thread is externally suspended and false otherwise.
745 //
746 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
747 uint32_t *bits) {
748 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
749 false /* !called_by_wait */, bits);
750
751 // local flag copies to minimize SR_lock hold time
752 bool is_suspended;
753 bool pending;
754 uint32_t reset_bits;
755
756 // set a marker so is_ext_suspend_completed() knows we are the caller
757 *bits |= 0x00010000;
758
759 // We use reset_bits to reinitialize the bits value at the top of
760 // each retry loop. This allows the caller to make use of any
761 // unused bits for their own marking purposes.
762 reset_bits = *bits;
763
764 {
765 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
766 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
767 delay, bits);
768 pending = is_external_suspend();
769 }
770 // must release SR_lock to allow suspension to complete
771
772 if (!pending) {
773 // A cancelled suspend request is the only false return from
774 // is_ext_suspend_completed() that keeps us from entering the
775 // retry loop.
776 *bits |= 0x00020000;
777 return false;
778 }
779
780 if (is_suspended) {
781 *bits |= 0x00040000;
782 return true;
783 }
784
785 for (int i = 1; i <= retries; i++) {
786 *bits = reset_bits; // reinit to only track last retry
787
788 // We used to do an "os::yield_all(i)" call here with the intention
789 // that yielding would increase on each retry. However, the parameter
790 // is ignored on Linux which means the yield didn't scale up. Waiting
791 // on the SR_lock below provides a much more predictable scale up for
792 // the delay. It also provides a simple/direct point to check for any
793 // safepoint requests from the VMThread
794
795 {
796 Thread* t = Thread::current();
797 MonitorLocker ml(SR_lock(),
798 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
799 // wait with safepoint check (if we're a JavaThread - the WatcherThread
800 // can also call this) and increase delay with each retry
801 ml.wait(i * delay);
802
803 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
804 delay, bits);
805
806 // It is possible for the external suspend request to be cancelled
807 // (by a resume) before the actual suspend operation is completed.
808 // Refresh our local copy to see if we still need to wait.
809 pending = is_external_suspend();
810 }
811
812 if (!pending) {
813 // A cancelled suspend request is the only false return from
814 // is_ext_suspend_completed() that keeps us from staying in the
815 // retry loop.
816 *bits |= 0x00080000;
817 return false;
818 }
819
820 if (is_suspended) {
821 *bits |= 0x00100000;
822 return true;
823 }
824 } // end retry loop
825
826 // thread did not suspend after all our retries
827 *bits |= 0x00200000;
828 return false;
829 }
830
831 // Called from API entry points which perform stack walking. If the
832 // associated JavaThread is the current thread, then wait_for_suspend
833 // is not used. Otherwise, it determines if we should wait for the
834 // "other" thread to complete external suspension. (NOTE: in future
835 // releases the suspension mechanism should be reimplemented so this
836 // is not necessary.)
837 //
838 bool
839 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
840 if (this != JavaThread::current()) {
841 // "other" threads require special handling.
842 if (wait_for_suspend) {
843 // We are allowed to wait for the external suspend to complete
844 // so give the other thread a chance to get suspended.
845 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
846 SuspendRetryDelay, bits)) {
847 // Didn't make it so let the caller know.
848 return false;
849 }
850 }
851 // We aren't allowed to wait for the external suspend to complete
852 // so if the other thread isn't externally suspended we need to
853 // let the caller know.
854 else if (!is_ext_suspend_completed_with_lock(bits)) {
855 return false;
856 }
857 }
858
859 return true;
860 }
861
862 #ifndef PRODUCT
863 void JavaThread::record_jump(address target, address instr, const char* file,
864 int line) {
865
866 // This should not need to be atomic as the only way for simultaneous
867 // updates is via interrupts. Even then this should be rare or non-existent
868 // and we don't care that much anyway.
869
870 int index = _jmp_ring_index;
871 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
872 _jmp_ring[index]._target = (intptr_t) target;
873 _jmp_ring[index]._instruction = (intptr_t) instr;
874 _jmp_ring[index]._file = file;
875 _jmp_ring[index]._line = line;
876 }
877 #endif // PRODUCT
878
879 void Thread::interrupt(Thread* thread) {
880 debug_only(check_for_dangling_thread_pointer(thread);)
881 os::interrupt(thread);
882 }
883
884 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
885 debug_only(check_for_dangling_thread_pointer(thread);)
886 // Note: If clear_interrupted==false, this simply fetches and
887 // returns the value of the field osthread()->interrupted().
888 return os::is_interrupted(thread, clear_interrupted);
889 }
890
891
892 // GC Support
893 bool Thread::claim_par_threads_do(uintx claim_token) {
894 uintx token = _threads_do_token;
895 if (token != claim_token) {
896 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
897 if (res == token) {
898 return true;
899 }
900 guarantee(res == claim_token, "invariant");
901 }
902 return false;
903 }
904
905 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
906 active_handles()->oops_do(f);
907 // Do oop for ThreadShadow
908 f->do_oop((oop*)&_pending_exception);
909 handle_area()->oops_do(f);
910
911 // We scan thread local monitor lists here, and the remaining global
912 // monitors in ObjectSynchronizer::oops_do().
913 ObjectSynchronizer::thread_local_used_oops_do(this, f);
914 }
915
916 void Thread::metadata_handles_do(void f(Metadata*)) {
917 // Only walk the Handles in Thread.
918 if (metadata_handles() != NULL) {
919 for (int i = 0; i< metadata_handles()->length(); i++) {
920 f(metadata_handles()->at(i));
921 }
922 }
923 }
924
925 void Thread::print_on(outputStream* st, bool print_extended_info) const {
926 // get_priority assumes osthread initialized
927 if (osthread() != NULL) {
928 int os_prio;
929 if (os::get_native_priority(this, &os_prio) == OS_OK) {
930 st->print("os_prio=%d ", os_prio);
931 }
932
933 st->print("cpu=%.2fms ",
934 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
935 );
936 st->print("elapsed=%.2fs ",
937 _statistical_info.getElapsedTime() / 1000.0
938 );
939 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
940 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
941 st->print("allocated=" SIZE_FORMAT "%s ",
942 byte_size_in_proper_unit(allocated_bytes),
943 proper_unit_for_byte_size(allocated_bytes)
944 );
945 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
946 }
947
948 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
949 osthread()->print_on(st);
950 }
951 ThreadsSMRSupport::print_info_on(this, st);
952 st->print(" ");
953 debug_only(if (WizardMode) print_owned_locks_on(st);)
954 }
955
956 void Thread::print() const { print_on(tty); }
957
958 // Thread::print_on_error() is called by fatal error handler. Don't use
959 // any lock or allocate memory.
960 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
961 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
962
963 if (is_VM_thread()) { st->print("VMThread"); }
964 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
965 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
966 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
967 else { st->print("Thread"); }
968
969 if (is_Named_thread()) {
970 st->print(" \"%s\"", name());
971 }
972
973 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
974 p2i(stack_end()), p2i(stack_base()));
975
976 if (osthread()) {
977 st->print(" [id=%d]", osthread()->thread_id());
978 }
979
980 ThreadsSMRSupport::print_info_on(this, st);
981 }
982
983 void Thread::print_value_on(outputStream* st) const {
984 if (is_Named_thread()) {
985 st->print(" \"%s\" ", name());
986 }
987 st->print(INTPTR_FORMAT, p2i(this)); // print address
988 }
989
990 #ifdef ASSERT
991 void Thread::print_owned_locks_on(outputStream* st) const {
992 Monitor *cur = _owned_locks;
993 if (cur == NULL) {
994 st->print(" (no locks) ");
995 } else {
996 st->print_cr(" Locks owned:");
997 while (cur) {
998 cur->print_on(st);
999 cur = cur->next();
1000 }
1001 }
1002 }
1003
1004 static int ref_use_count = 0;
1005
1006 bool Thread::owns_locks_but_compiled_lock() const {
1007 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1008 if (cur != Compile_lock) return true;
1009 }
1010 return false;
1011 }
1012
1013
1014 #endif
1015
1016 #ifndef PRODUCT
1017
1018 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1019 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1020 // no locks which allow_vm_block's are held
1021 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1022 // Check if current thread is allowed to block at a safepoint
1023 if (!(_allow_safepoint_count == 0)) {
1024 fatal("Possible safepoint reached by thread that does not allow it");
1025 }
1026 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1027 fatal("LEAF method calling lock?");
1028 }
1029
1030 #ifdef ASSERT
1031 if (potential_vm_operation && is_Java_thread()
1032 && !Universe::is_bootstrapping()) {
1033 // Make sure we do not hold any locks that the VM thread also uses.
1034 // This could potentially lead to deadlocks
1035 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1036 // Threads_lock is special, since the safepoint synchronization will not start before this is
1037 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1038 // since it is used to transfer control between JavaThreads and the VMThread
1039 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1040 if ((cur->allow_vm_block() &&
1041 cur != Threads_lock &&
1042 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1043 cur != VMOperationRequest_lock &&
1044 cur != VMOperationQueue_lock) ||
1045 cur->rank() == Mutex::special) {
1046 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1047 }
1048 }
1049 }
1050
1051 if (GCALotAtAllSafepoints) {
1052 // We could enter a safepoint here and thus have a gc
1053 InterfaceSupport::check_gc_alot();
1054 }
1055 #endif
1056 }
1057 #endif
1058
1059 bool Thread::is_in_stack(address adr) const {
1060 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1061 address end = os::current_stack_pointer();
1062 // Allow non Java threads to call this without stack_base
1063 if (_stack_base == NULL) return true;
1064 if (stack_base() >= adr && adr >= end) return true;
1065
1066 return false;
1067 }
1068
1069 bool Thread::is_in_usable_stack(address adr) const {
1070 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1071 size_t usable_stack_size = _stack_size - stack_guard_size;
1072
1073 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1074 }
1075
1076
1077 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1078 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1079 // used for compilation in the future. If that change is made, the need for these methods
1080 // should be revisited, and they should be removed if possible.
1081
1082 bool Thread::is_lock_owned(address adr) const {
1083 return on_local_stack(adr);
1084 }
1085
1086 bool Thread::set_as_starting_thread() {
1087 assert(_starting_thread == NULL, "already initialized: "
1088 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1089 // NOTE: this must be called inside the main thread.
1090 DEBUG_ONLY(_starting_thread = this;)
1091 return os::create_main_thread((JavaThread*)this);
1092 }
1093
1094 static void initialize_class(Symbol* class_name, TRAPS) {
1095 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1096 InstanceKlass::cast(klass)->initialize(CHECK);
1097 }
1098
1099
1100 // Creates the initial ThreadGroup
1101 static Handle create_initial_thread_group(TRAPS) {
1102 Handle system_instance = JavaCalls::construct_new_instance(
1103 SystemDictionary::ThreadGroup_klass(),
1104 vmSymbols::void_method_signature(),
1105 CHECK_NH);
1106 Universe::set_system_thread_group(system_instance());
1107
1108 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1109 Handle main_instance = JavaCalls::construct_new_instance(
1110 SystemDictionary::ThreadGroup_klass(),
1111 vmSymbols::threadgroup_string_void_signature(),
1112 system_instance,
1113 string,
1114 CHECK_NH);
1115 return main_instance;
1116 }
1117
1118 // Creates the initial Thread
1119 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1120 TRAPS) {
1121 InstanceKlass* ik = SystemDictionary::Thread_klass();
1122 assert(ik->is_initialized(), "must be");
1123 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1124
1125 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1126 // constructor calls Thread.current(), which must be set here for the
1127 // initial thread.
1128 java_lang_Thread::set_thread(thread_oop(), thread);
1129 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1130 thread->set_threadObj(thread_oop());
1131
1132 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1133
1134 JavaValue result(T_VOID);
1135 JavaCalls::call_special(&result, thread_oop,
1136 ik,
1137 vmSymbols::object_initializer_name(),
1138 vmSymbols::threadgroup_string_void_signature(),
1139 thread_group,
1140 string,
1141 CHECK_NULL);
1142 return thread_oop();
1143 }
1144
1145 char java_runtime_name[128] = "";
1146 char java_runtime_version[128] = "";
1147
1148 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1149 static const char* get_java_runtime_name(TRAPS) {
1150 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1151 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1152 fieldDescriptor fd;
1153 bool found = k != NULL &&
1154 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1155 vmSymbols::string_signature(), &fd);
1156 if (found) {
1157 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1158 if (name_oop == NULL) {
1159 return NULL;
1160 }
1161 const char* name = java_lang_String::as_utf8_string(name_oop,
1162 java_runtime_name,
1163 sizeof(java_runtime_name));
1164 return name;
1165 } else {
1166 return NULL;
1167 }
1168 }
1169
1170 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1171 static const char* get_java_runtime_version(TRAPS) {
1172 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1173 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1174 fieldDescriptor fd;
1175 bool found = k != NULL &&
1176 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1177 vmSymbols::string_signature(), &fd);
1178 if (found) {
1179 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1180 if (name_oop == NULL) {
1181 return NULL;
1182 }
1183 const char* name = java_lang_String::as_utf8_string(name_oop,
1184 java_runtime_version,
1185 sizeof(java_runtime_version));
1186 return name;
1187 } else {
1188 return NULL;
1189 }
1190 }
1191
1192 // General purpose hook into Java code, run once when the VM is initialized.
1193 // The Java library method itself may be changed independently from the VM.
1194 static void call_postVMInitHook(TRAPS) {
1195 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1196 if (klass != NULL) {
1197 JavaValue result(T_VOID);
1198 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1199 vmSymbols::void_method_signature(),
1200 CHECK);
1201 }
1202 }
1203
1204 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1205 bool daemon, TRAPS) {
1206 assert(thread_group.not_null(), "thread group should be specified");
1207 assert(threadObj() == NULL, "should only create Java thread object once");
1208
1209 InstanceKlass* ik = SystemDictionary::Thread_klass();
1210 assert(ik->is_initialized(), "must be");
1211 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1212
1213 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1214 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1215 // constructor calls Thread.current(), which must be set here.
1216 java_lang_Thread::set_thread(thread_oop(), this);
1217 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1218 set_threadObj(thread_oop());
1219
1220 JavaValue result(T_VOID);
1221 if (thread_name != NULL) {
1222 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1223 // Thread gets assigned specified name and null target
1224 JavaCalls::call_special(&result,
1225 thread_oop,
1226 ik,
1227 vmSymbols::object_initializer_name(),
1228 vmSymbols::threadgroup_string_void_signature(),
1229 thread_group,
1230 name,
1231 THREAD);
1232 } else {
1233 // Thread gets assigned name "Thread-nnn" and null target
1234 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1235 JavaCalls::call_special(&result,
1236 thread_oop,
1237 ik,
1238 vmSymbols::object_initializer_name(),
1239 vmSymbols::threadgroup_runnable_void_signature(),
1240 thread_group,
1241 Handle(),
1242 THREAD);
1243 }
1244
1245
1246 if (daemon) {
1247 java_lang_Thread::set_daemon(thread_oop());
1248 }
1249
1250 if (HAS_PENDING_EXCEPTION) {
1251 return;
1252 }
1253
1254 Klass* group = SystemDictionary::ThreadGroup_klass();
1255 Handle threadObj(THREAD, this->threadObj());
1256
1257 JavaCalls::call_special(&result,
1258 thread_group,
1259 group,
1260 vmSymbols::add_method_name(),
1261 vmSymbols::thread_void_signature(),
1262 threadObj, // Arg 1
1263 THREAD);
1264 }
1265
1266 // List of all NonJavaThreads and safe iteration over that list.
1267
1268 class NonJavaThread::List {
1269 public:
1270 NonJavaThread* volatile _head;
1271 SingleWriterSynchronizer _protect;
1272
1273 List() : _head(NULL), _protect() {}
1274 };
1275
1276 NonJavaThread::List NonJavaThread::_the_list;
1277
1278 NonJavaThread::Iterator::Iterator() :
1279 _protect_enter(_the_list._protect.enter()),
1280 _current(OrderAccess::load_acquire(&_the_list._head))
1281 {}
1282
1283 NonJavaThread::Iterator::~Iterator() {
1284 _the_list._protect.exit(_protect_enter);
1285 }
1286
1287 void NonJavaThread::Iterator::step() {
1288 assert(!end(), "precondition");
1289 _current = OrderAccess::load_acquire(&_current->_next);
1290 }
1291
1292 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1293 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1294 }
1295
1296 NonJavaThread::~NonJavaThread() { }
1297
1298 void NonJavaThread::add_to_the_list() {
1299 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1300 // Initialize BarrierSet-related data before adding to list.
1301 BarrierSet::barrier_set()->on_thread_attach(this);
1302 OrderAccess::release_store(&_next, _the_list._head);
1303 OrderAccess::release_store(&_the_list._head, this);
1304 }
1305
1306 void NonJavaThread::remove_from_the_list() {
1307 {
1308 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1309 // Cleanup BarrierSet-related data before removing from list.
1310 BarrierSet::barrier_set()->on_thread_detach(this);
1311 NonJavaThread* volatile* p = &_the_list._head;
1312 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1313 if (t == this) {
1314 *p = _next;
1315 break;
1316 }
1317 }
1318 }
1319 // Wait for any in-progress iterators. Concurrent synchronize is not
1320 // allowed, so do it while holding a dedicated lock. Outside and distinct
1321 // from NJTList_lock in case an iteration attempts to lock it.
1322 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1323 _the_list._protect.synchronize();
1324 _next = NULL; // Safe to drop the link now.
1325 }
1326
1327 void NonJavaThread::pre_run() {
1328 add_to_the_list();
1329
1330 // This is slightly odd in that NamedThread is a subclass, but
1331 // in fact name() is defined in Thread
1332 assert(this->name() != NULL, "thread name was not set before it was started");
1333 this->set_native_thread_name(this->name());
1334 }
1335
1336 void NonJavaThread::post_run() {
1337 JFR_ONLY(Jfr::on_thread_exit(this);)
1338 remove_from_the_list();
1339 // Ensure thread-local-storage is cleared before termination.
1340 Thread::clear_thread_current();
1341 }
1342
1343 // NamedThread -- non-JavaThread subclasses with multiple
1344 // uniquely named instances should derive from this.
1345 NamedThread::NamedThread() :
1346 NonJavaThread(),
1347 _name(NULL),
1348 _processed_thread(NULL),
1349 _gc_id(GCId::undefined())
1350 {}
1351
1352 NamedThread::~NamedThread() {
1353 if (_name != NULL) {
1354 FREE_C_HEAP_ARRAY(char, _name);
1355 _name = NULL;
1356 }
1357 }
1358
1359 void NamedThread::set_name(const char* format, ...) {
1360 guarantee(_name == NULL, "Only get to set name once.");
1361 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1362 guarantee(_name != NULL, "alloc failure");
1363 va_list ap;
1364 va_start(ap, format);
1365 jio_vsnprintf(_name, max_name_len, format, ap);
1366 va_end(ap);
1367 }
1368
1369 void NamedThread::print_on(outputStream* st) const {
1370 st->print("\"%s\" ", name());
1371 Thread::print_on(st);
1372 st->cr();
1373 }
1374
1375
1376 // ======= WatcherThread ========
1377
1378 // The watcher thread exists to simulate timer interrupts. It should
1379 // be replaced by an abstraction over whatever native support for
1380 // timer interrupts exists on the platform.
1381
1382 WatcherThread* WatcherThread::_watcher_thread = NULL;
1383 bool WatcherThread::_startable = false;
1384 volatile bool WatcherThread::_should_terminate = false;
1385
1386 WatcherThread::WatcherThread() : NonJavaThread() {
1387 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1388 if (os::create_thread(this, os::watcher_thread)) {
1389 _watcher_thread = this;
1390
1391 // Set the watcher thread to the highest OS priority which should not be
1392 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1393 // is created. The only normal thread using this priority is the reference
1394 // handler thread, which runs for very short intervals only.
1395 // If the VMThread's priority is not lower than the WatcherThread profiling
1396 // will be inaccurate.
1397 os::set_priority(this, MaxPriority);
1398 if (!DisableStartThread) {
1399 os::start_thread(this);
1400 }
1401 }
1402 }
1403
1404 int WatcherThread::sleep() const {
1405 // The WatcherThread does not participate in the safepoint protocol
1406 // for the PeriodicTask_lock because it is not a JavaThread.
1407 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1408
1409 if (_should_terminate) {
1410 // check for termination before we do any housekeeping or wait
1411 return 0; // we did not sleep.
1412 }
1413
1414 // remaining will be zero if there are no tasks,
1415 // causing the WatcherThread to sleep until a task is
1416 // enrolled
1417 int remaining = PeriodicTask::time_to_wait();
1418 int time_slept = 0;
1419
1420 // we expect this to timeout - we only ever get unparked when
1421 // we should terminate or when a new task has been enrolled
1422 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1423
1424 jlong time_before_loop = os::javaTimeNanos();
1425
1426 while (true) {
1427 bool timedout = ml.wait(remaining);
1428 jlong now = os::javaTimeNanos();
1429
1430 if (remaining == 0) {
1431 // if we didn't have any tasks we could have waited for a long time
1432 // consider the time_slept zero and reset time_before_loop
1433 time_slept = 0;
1434 time_before_loop = now;
1435 } else {
1436 // need to recalculate since we might have new tasks in _tasks
1437 time_slept = (int) ((now - time_before_loop) / 1000000);
1438 }
1439
1440 // Change to task list or spurious wakeup of some kind
1441 if (timedout || _should_terminate) {
1442 break;
1443 }
1444
1445 remaining = PeriodicTask::time_to_wait();
1446 if (remaining == 0) {
1447 // Last task was just disenrolled so loop around and wait until
1448 // another task gets enrolled
1449 continue;
1450 }
1451
1452 remaining -= time_slept;
1453 if (remaining <= 0) {
1454 break;
1455 }
1456 }
1457
1458 return time_slept;
1459 }
1460
1461 void WatcherThread::run() {
1462 assert(this == watcher_thread(), "just checking");
1463
1464 this->set_active_handles(JNIHandleBlock::allocate_block());
1465 while (true) {
1466 assert(watcher_thread() == Thread::current(), "thread consistency check");
1467 assert(watcher_thread() == this, "thread consistency check");
1468
1469 // Calculate how long it'll be until the next PeriodicTask work
1470 // should be done, and sleep that amount of time.
1471 int time_waited = sleep();
1472
1473 if (VMError::is_error_reported()) {
1474 // A fatal error has happened, the error handler(VMError::report_and_die)
1475 // should abort JVM after creating an error log file. However in some
1476 // rare cases, the error handler itself might deadlock. Here periodically
1477 // check for error reporting timeouts, and if it happens, just proceed to
1478 // abort the VM.
1479
1480 // This code is in WatcherThread because WatcherThread wakes up
1481 // periodically so the fatal error handler doesn't need to do anything;
1482 // also because the WatcherThread is less likely to crash than other
1483 // threads.
1484
1485 for (;;) {
1486 // Note: we use naked sleep in this loop because we want to avoid using
1487 // any kind of VM infrastructure which may be broken at this point.
1488 if (VMError::check_timeout()) {
1489 // We hit error reporting timeout. Error reporting was interrupted and
1490 // will be wrapping things up now (closing files etc). Give it some more
1491 // time, then quit the VM.
1492 os::naked_short_sleep(200);
1493 // Print a message to stderr.
1494 fdStream err(defaultStream::output_fd());
1495 err.print_raw_cr("# [ timer expired, abort... ]");
1496 // skip atexit/vm_exit/vm_abort hooks
1497 os::die();
1498 }
1499
1500 // Wait a second, then recheck for timeout.
1501 os::naked_short_sleep(999);
1502 }
1503 }
1504
1505 if (_should_terminate) {
1506 // check for termination before posting the next tick
1507 break;
1508 }
1509
1510 PeriodicTask::real_time_tick(time_waited);
1511 }
1512
1513 // Signal that it is terminated
1514 {
1515 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1516 _watcher_thread = NULL;
1517 Terminator_lock->notify_all();
1518 }
1519 }
1520
1521 void WatcherThread::start() {
1522 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1523
1524 if (watcher_thread() == NULL && _startable) {
1525 _should_terminate = false;
1526 // Create the single instance of WatcherThread
1527 new WatcherThread();
1528 }
1529 }
1530
1531 void WatcherThread::make_startable() {
1532 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1533 _startable = true;
1534 }
1535
1536 void WatcherThread::stop() {
1537 {
1538 // Follow normal safepoint aware lock enter protocol since the
1539 // WatcherThread is stopped by another JavaThread.
1540 MutexLocker ml(PeriodicTask_lock);
1541 _should_terminate = true;
1542
1543 WatcherThread* watcher = watcher_thread();
1544 if (watcher != NULL) {
1545 // unpark the WatcherThread so it can see that it should terminate
1546 watcher->unpark();
1547 }
1548 }
1549
1550 MonitorLocker mu(Terminator_lock);
1551
1552 while (watcher_thread() != NULL) {
1553 // This wait should make safepoint checks, wait without a timeout,
1554 // and wait as a suspend-equivalent condition.
1555 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1556 }
1557 }
1558
1559 void WatcherThread::unpark() {
1560 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1561 PeriodicTask_lock->notify();
1562 }
1563
1564 void WatcherThread::print_on(outputStream* st) const {
1565 st->print("\"%s\" ", name());
1566 Thread::print_on(st);
1567 st->cr();
1568 }
1569
1570 // ======= JavaThread ========
1571
1572 #if INCLUDE_JVMCI
1573
1574 jlong* JavaThread::_jvmci_old_thread_counters;
1575
1576 bool jvmci_counters_include(JavaThread* thread) {
1577 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1578 }
1579
1580 void JavaThread::collect_counters(jlong* array, int length) {
1581 assert(length == JVMCICounterSize, "wrong value");
1582 for (int i = 0; i < length; i++) {
1583 array[i] = _jvmci_old_thread_counters[i];
1584 }
1585 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1586 if (jvmci_counters_include(tp)) {
1587 for (int i = 0; i < length; i++) {
1588 array[i] += tp->_jvmci_counters[i];
1589 }
1590 }
1591 }
1592 }
1593
1594 #endif // INCLUDE_JVMCI
1595
1596 // A JavaThread is a normal Java thread
1597
1598 void JavaThread::initialize() {
1599 // Initialize fields
1600
1601 set_saved_exception_pc(NULL);
1602 set_threadObj(NULL);
1603 _anchor.clear();
1604 set_entry_point(NULL);
1605 set_jni_functions(jni_functions());
1606 set_callee_target(NULL);
1607 set_vm_result(NULL);
1608 set_vm_result_2(NULL);
1609 set_vframe_array_head(NULL);
1610 set_vframe_array_last(NULL);
1611 set_deferred_locals(NULL);
1612 set_deopt_mark(NULL);
1613 set_deopt_compiled_method(NULL);
1614 clear_must_deopt_id();
1615 set_monitor_chunks(NULL);
1616 _on_thread_list = false;
1617 set_thread_state(_thread_new);
1618 _terminated = _not_terminated;
1619 _array_for_gc = NULL;
1620 _suspend_equivalent = false;
1621 _in_deopt_handler = 0;
1622 _doing_unsafe_access = false;
1623 _stack_guard_state = stack_guard_unused;
1624 #if INCLUDE_JVMCI
1625 _pending_monitorenter = false;
1626 _pending_deoptimization = -1;
1627 _pending_failed_speculation = 0;
1628 _pending_transfer_to_interpreter = false;
1629 _in_retryable_allocation = false;
1630 _jvmci._alternate_call_target = NULL;
1631 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1632 if (JVMCICounterSize > 0) {
1633 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1634 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1635 } else {
1636 _jvmci_counters = NULL;
1637 }
1638 #endif // INCLUDE_JVMCI
1639 _reserved_stack_activation = NULL; // stack base not known yet
1640 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1641 _exception_pc = 0;
1642 _exception_handler_pc = 0;
1643 _is_method_handle_return = 0;
1644 _jvmti_thread_state= NULL;
1645 _should_post_on_exceptions_flag = JNI_FALSE;
1646 _interp_only_mode = 0;
1647 _special_runtime_exit_condition = _no_async_condition;
1648 _pending_async_exception = NULL;
1649 _thread_stat = NULL;
1650 _thread_stat = new ThreadStatistics();
1651 _blocked_on_compilation = false;
1652 _jni_active_critical = 0;
1653 _pending_jni_exception_check_fn = NULL;
1654 _do_not_unlock_if_synchronized = false;
1655 _cached_monitor_info = NULL;
1656 _parker = Parker::Allocate(this);
1657
1658 #ifndef PRODUCT
1659 _jmp_ring_index = 0;
1660 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1661 record_jump(NULL, NULL, NULL, 0);
1662 }
1663 #endif // PRODUCT
1664
1665 // Setup safepoint state info for this thread
1666 ThreadSafepointState::create(this);
1667
1668 debug_only(_java_call_counter = 0);
1669
1670 // JVMTI PopFrame support
1671 _popframe_condition = popframe_inactive;
1672 _popframe_preserved_args = NULL;
1673 _popframe_preserved_args_size = 0;
1674 _frames_to_pop_failed_realloc = 0;
1675
1676 if (SafepointMechanism::uses_thread_local_poll()) {
1677 SafepointMechanism::initialize_header(this);
1678 }
1679
1680 _class_to_be_initialized = NULL;
1681
1682 pd_initialize();
1683 }
1684
1685 JavaThread::JavaThread(bool is_attaching_via_jni) :
1686 Thread() {
1687 initialize();
1688 if (is_attaching_via_jni) {
1689 _jni_attach_state = _attaching_via_jni;
1690 } else {
1691 _jni_attach_state = _not_attaching_via_jni;
1692 }
1693 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1694 }
1695
1696 bool JavaThread::reguard_stack(address cur_sp) {
1697 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1698 && _stack_guard_state != stack_guard_reserved_disabled) {
1699 return true; // Stack already guarded or guard pages not needed.
1700 }
1701
1702 if (register_stack_overflow()) {
1703 // For those architectures which have separate register and
1704 // memory stacks, we must check the register stack to see if
1705 // it has overflowed.
1706 return false;
1707 }
1708
1709 // Java code never executes within the yellow zone: the latter is only
1710 // there to provoke an exception during stack banging. If java code
1711 // is executing there, either StackShadowPages should be larger, or
1712 // some exception code in c1, c2 or the interpreter isn't unwinding
1713 // when it should.
1714 guarantee(cur_sp > stack_reserved_zone_base(),
1715 "not enough space to reguard - increase StackShadowPages");
1716 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1717 enable_stack_yellow_reserved_zone();
1718 if (reserved_stack_activation() != stack_base()) {
1719 set_reserved_stack_activation(stack_base());
1720 }
1721 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1722 set_reserved_stack_activation(stack_base());
1723 enable_stack_reserved_zone();
1724 }
1725 return true;
1726 }
1727
1728 bool JavaThread::reguard_stack(void) {
1729 return reguard_stack(os::current_stack_pointer());
1730 }
1731
1732
1733 void JavaThread::block_if_vm_exited() {
1734 if (_terminated == _vm_exited) {
1735 // _vm_exited is set at safepoint, and Threads_lock is never released
1736 // we will block here forever
1737 Threads_lock->lock_without_safepoint_check();
1738 ShouldNotReachHere();
1739 }
1740 }
1741
1742
1743 // Remove this ifdef when C1 is ported to the compiler interface.
1744 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1745 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1746
1747 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1748 Thread() {
1749 initialize();
1750 _jni_attach_state = _not_attaching_via_jni;
1751 set_entry_point(entry_point);
1752 // Create the native thread itself.
1753 // %note runtime_23
1754 os::ThreadType thr_type = os::java_thread;
1755 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1756 os::java_thread;
1757 os::create_thread(this, thr_type, stack_sz);
1758 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1759 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1760 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1761 // the exception consists of creating the exception object & initializing it, initialization
1762 // will leave the VM via a JavaCall and then all locks must be unlocked).
1763 //
1764 // The thread is still suspended when we reach here. Thread must be explicit started
1765 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1766 // by calling Threads:add. The reason why this is not done here, is because the thread
1767 // object must be fully initialized (take a look at JVM_Start)
1768 }
1769
1770 JavaThread::~JavaThread() {
1771
1772 // JSR166 -- return the parker to the free list
1773 Parker::Release(_parker);
1774 _parker = NULL;
1775
1776 // Free any remaining previous UnrollBlock
1777 vframeArray* old_array = vframe_array_last();
1778
1779 if (old_array != NULL) {
1780 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1781 old_array->set_unroll_block(NULL);
1782 delete old_info;
1783 delete old_array;
1784 }
1785
1786 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1787 if (deferred != NULL) {
1788 // This can only happen if thread is destroyed before deoptimization occurs.
1789 assert(deferred->length() != 0, "empty array!");
1790 do {
1791 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1792 deferred->remove_at(0);
1793 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1794 delete dlv;
1795 } while (deferred->length() != 0);
1796 delete deferred;
1797 }
1798
1799 // All Java related clean up happens in exit
1800 ThreadSafepointState::destroy(this);
1801 if (_thread_stat != NULL) delete _thread_stat;
1802
1803 #if INCLUDE_JVMCI
1804 if (JVMCICounterSize > 0) {
1805 if (jvmci_counters_include(this)) {
1806 for (int i = 0; i < JVMCICounterSize; i++) {
1807 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1808 }
1809 }
1810 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1811 }
1812 #endif // INCLUDE_JVMCI
1813 }
1814
1815
1816 // First JavaThread specific code executed by a new Java thread.
1817 void JavaThread::pre_run() {
1818 // empty - see comments in run()
1819 }
1820
1821 // The main routine called by a new Java thread. This isn't overridden
1822 // by subclasses, instead different subclasses define a different "entry_point"
1823 // which defines the actual logic for that kind of thread.
1824 void JavaThread::run() {
1825 // initialize thread-local alloc buffer related fields
1826 this->initialize_tlab();
1827
1828 // Used to test validity of stack trace backs.
1829 // This can't be moved into pre_run() else we invalidate
1830 // the requirement that thread_main_inner is lower on
1831 // the stack. Consequently all the initialization logic
1832 // stays here in run() rather than pre_run().
1833 this->record_base_of_stack_pointer();
1834
1835 this->create_stack_guard_pages();
1836
1837 this->cache_global_variables();
1838
1839 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1840 // in the VM. Change thread state from _thread_new to _thread_in_vm
1841 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1842 // Before a thread is on the threads list it is always safe, so after leaving the
1843 // _thread_new we should emit a instruction barrier. The distance to modified code
1844 // from here is probably far enough, but this is consistent and safe.
1845 OrderAccess::cross_modify_fence();
1846
1847 assert(JavaThread::current() == this, "sanity check");
1848 assert(!Thread::current()->owns_locks(), "sanity check");
1849
1850 DTRACE_THREAD_PROBE(start, this);
1851
1852 // This operation might block. We call that after all safepoint checks for a new thread has
1853 // been completed.
1854 this->set_active_handles(JNIHandleBlock::allocate_block());
1855
1856 if (JvmtiExport::should_post_thread_life()) {
1857 JvmtiExport::post_thread_start(this);
1858
1859 }
1860
1861 // We call another function to do the rest so we are sure that the stack addresses used
1862 // from there will be lower than the stack base just computed.
1863 thread_main_inner();
1864 }
1865
1866 void JavaThread::thread_main_inner() {
1867 assert(JavaThread::current() == this, "sanity check");
1868 assert(this->threadObj() != NULL, "just checking");
1869
1870 // Execute thread entry point unless this thread has a pending exception
1871 // or has been stopped before starting.
1872 // Note: Due to JVM_StopThread we can have pending exceptions already!
1873 if (!this->has_pending_exception() &&
1874 !java_lang_Thread::is_stillborn(this->threadObj())) {
1875 {
1876 ResourceMark rm(this);
1877 this->set_native_thread_name(this->get_thread_name());
1878 }
1879 HandleMark hm(this);
1880 this->entry_point()(this, this);
1881 }
1882
1883 DTRACE_THREAD_PROBE(stop, this);
1884
1885 // Cleanup is handled in post_run()
1886 }
1887
1888 // Shared teardown for all JavaThreads
1889 void JavaThread::post_run() {
1890 this->exit(false);
1891 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1892 // for any shared tear-down.
1893 this->smr_delete();
1894 }
1895
1896 static void ensure_join(JavaThread* thread) {
1897 // We do not need to grab the Threads_lock, since we are operating on ourself.
1898 Handle threadObj(thread, thread->threadObj());
1899 assert(threadObj.not_null(), "java thread object must exist");
1900 ObjectLocker lock(threadObj, thread);
1901 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1902 thread->clear_pending_exception();
1903 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1904 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1905 // Clear the native thread instance - this makes isAlive return false and allows the join()
1906 // to complete once we've done the notify_all below
1907 java_lang_Thread::set_thread(threadObj(), NULL);
1908 lock.notify_all(thread);
1909 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1910 thread->clear_pending_exception();
1911 }
1912
1913 static bool is_daemon(oop threadObj) {
1914 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1915 }
1916
1917 // For any new cleanup additions, please check to see if they need to be applied to
1918 // cleanup_failed_attach_current_thread as well.
1919 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1920 assert(this == JavaThread::current(), "thread consistency check");
1921
1922 elapsedTimer _timer_exit_phase1;
1923 elapsedTimer _timer_exit_phase2;
1924 elapsedTimer _timer_exit_phase3;
1925 elapsedTimer _timer_exit_phase4;
1926
1927 if (log_is_enabled(Debug, os, thread, timer)) {
1928 _timer_exit_phase1.start();
1929 }
1930
1931 HandleMark hm(this);
1932 Handle uncaught_exception(this, this->pending_exception());
1933 this->clear_pending_exception();
1934 Handle threadObj(this, this->threadObj());
1935 assert(threadObj.not_null(), "Java thread object should be created");
1936
1937 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1938 {
1939 EXCEPTION_MARK;
1940
1941 CLEAR_PENDING_EXCEPTION;
1942 }
1943 if (!destroy_vm) {
1944 if (uncaught_exception.not_null()) {
1945 EXCEPTION_MARK;
1946 // Call method Thread.dispatchUncaughtException().
1947 Klass* thread_klass = SystemDictionary::Thread_klass();
1948 JavaValue result(T_VOID);
1949 JavaCalls::call_virtual(&result,
1950 threadObj, thread_klass,
1951 vmSymbols::dispatchUncaughtException_name(),
1952 vmSymbols::throwable_void_signature(),
1953 uncaught_exception,
1954 THREAD);
1955 if (HAS_PENDING_EXCEPTION) {
1956 ResourceMark rm(this);
1957 jio_fprintf(defaultStream::error_stream(),
1958 "\nException: %s thrown from the UncaughtExceptionHandler"
1959 " in thread \"%s\"\n",
1960 pending_exception()->klass()->external_name(),
1961 get_thread_name());
1962 CLEAR_PENDING_EXCEPTION;
1963 }
1964 }
1965 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
1966
1967 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1968 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1969 // is deprecated anyhow.
1970 if (!is_Compiler_thread()) {
1971 int count = 3;
1972 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1973 EXCEPTION_MARK;
1974 JavaValue result(T_VOID);
1975 Klass* thread_klass = SystemDictionary::Thread_klass();
1976 JavaCalls::call_virtual(&result,
1977 threadObj, thread_klass,
1978 vmSymbols::exit_method_name(),
1979 vmSymbols::void_method_signature(),
1980 THREAD);
1981 CLEAR_PENDING_EXCEPTION;
1982 }
1983 }
1984 // notify JVMTI
1985 if (JvmtiExport::should_post_thread_life()) {
1986 JvmtiExport::post_thread_end(this);
1987 }
1988
1989 // We have notified the agents that we are exiting, before we go on,
1990 // we must check for a pending external suspend request and honor it
1991 // in order to not surprise the thread that made the suspend request.
1992 while (true) {
1993 {
1994 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1995 if (!is_external_suspend()) {
1996 set_terminated(_thread_exiting);
1997 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
1998 break;
1999 }
2000 // Implied else:
2001 // Things get a little tricky here. We have a pending external
2002 // suspend request, but we are holding the SR_lock so we
2003 // can't just self-suspend. So we temporarily drop the lock
2004 // and then self-suspend.
2005 }
2006
2007 ThreadBlockInVM tbivm(this);
2008 java_suspend_self();
2009
2010 // We're done with this suspend request, but we have to loop around
2011 // and check again. Eventually we will get SR_lock without a pending
2012 // external suspend request and will be able to mark ourselves as
2013 // exiting.
2014 }
2015 // no more external suspends are allowed at this point
2016 } else {
2017 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2018 // before_exit() has already posted JVMTI THREAD_END events
2019 }
2020
2021 if (log_is_enabled(Debug, os, thread, timer)) {
2022 _timer_exit_phase1.stop();
2023 _timer_exit_phase2.start();
2024 }
2025
2026 // Capture daemon status before the thread is marked as terminated.
2027 bool daemon = is_daemon(threadObj());
2028
2029 // Notify waiters on thread object. This has to be done after exit() is called
2030 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2031 // group should have the destroyed bit set before waiters are notified).
2032 ensure_join(this);
2033 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2034
2035 if (log_is_enabled(Debug, os, thread, timer)) {
2036 _timer_exit_phase2.stop();
2037 _timer_exit_phase3.start();
2038 }
2039 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2040 // held by this thread must be released. The spec does not distinguish
2041 // between JNI-acquired and regular Java monitors. We can only see
2042 // regular Java monitors here if monitor enter-exit matching is broken.
2043 //
2044 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2045 // ObjectSynchronizer::release_monitors_owned_by_thread().
2046 if (exit_type == jni_detach) {
2047 // Sanity check even though JNI DetachCurrentThread() would have
2048 // returned JNI_ERR if there was a Java frame. JavaThread exit
2049 // should be done executing Java code by the time we get here.
2050 assert(!this->has_last_Java_frame(),
2051 "should not have a Java frame when detaching or exiting");
2052 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2053 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2054 }
2055
2056 // These things needs to be done while we are still a Java Thread. Make sure that thread
2057 // is in a consistent state, in case GC happens
2058 JFR_ONLY(Jfr::on_thread_exit(this);)
2059
2060 if (active_handles() != NULL) {
2061 JNIHandleBlock* block = active_handles();
2062 set_active_handles(NULL);
2063 JNIHandleBlock::release_block(block);
2064 }
2065
2066 if (free_handle_block() != NULL) {
2067 JNIHandleBlock* block = free_handle_block();
2068 set_free_handle_block(NULL);
2069 JNIHandleBlock::release_block(block);
2070 }
2071
2072 // These have to be removed while this is still a valid thread.
2073 remove_stack_guard_pages();
2074
2075 if (UseTLAB) {
2076 tlab().retire();
2077 }
2078
2079 if (JvmtiEnv::environments_might_exist()) {
2080 JvmtiExport::cleanup_thread(this);
2081 }
2082
2083 // We must flush any deferred card marks and other various GC barrier
2084 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2085 // before removing a thread from the list of active threads.
2086 BarrierSet::barrier_set()->on_thread_detach(this);
2087
2088 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2089 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2090 os::current_thread_id());
2091
2092 if (log_is_enabled(Debug, os, thread, timer)) {
2093 _timer_exit_phase3.stop();
2094 _timer_exit_phase4.start();
2095 }
2096 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2097 Threads::remove(this, daemon);
2098
2099 if (log_is_enabled(Debug, os, thread, timer)) {
2100 _timer_exit_phase4.stop();
2101 ResourceMark rm(this);
2102 log_debug(os, thread, timer)("name='%s'"
2103 ", exit-phase1=" JLONG_FORMAT
2104 ", exit-phase2=" JLONG_FORMAT
2105 ", exit-phase3=" JLONG_FORMAT
2106 ", exit-phase4=" JLONG_FORMAT,
2107 get_thread_name(),
2108 _timer_exit_phase1.milliseconds(),
2109 _timer_exit_phase2.milliseconds(),
2110 _timer_exit_phase3.milliseconds(),
2111 _timer_exit_phase4.milliseconds());
2112 }
2113 }
2114
2115 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2116 if (active_handles() != NULL) {
2117 JNIHandleBlock* block = active_handles();
2118 set_active_handles(NULL);
2119 JNIHandleBlock::release_block(block);
2120 }
2121
2122 if (free_handle_block() != NULL) {
2123 JNIHandleBlock* block = free_handle_block();
2124 set_free_handle_block(NULL);
2125 JNIHandleBlock::release_block(block);
2126 }
2127
2128 // These have to be removed while this is still a valid thread.
2129 remove_stack_guard_pages();
2130
2131 if (UseTLAB) {
2132 tlab().retire();
2133 }
2134
2135 BarrierSet::barrier_set()->on_thread_detach(this);
2136
2137 Threads::remove(this, is_daemon);
2138 this->smr_delete();
2139 }
2140
2141 JavaThread* JavaThread::active() {
2142 Thread* thread = Thread::current();
2143 if (thread->is_Java_thread()) {
2144 return (JavaThread*) thread;
2145 } else {
2146 assert(thread->is_VM_thread(), "this must be a vm thread");
2147 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2148 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2149 assert(ret->is_Java_thread(), "must be a Java thread");
2150 return ret;
2151 }
2152 }
2153
2154 bool JavaThread::is_lock_owned(address adr) const {
2155 if (Thread::is_lock_owned(adr)) return true;
2156
2157 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2158 if (chunk->contains(adr)) return true;
2159 }
2160
2161 return false;
2162 }
2163
2164
2165 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2166 chunk->set_next(monitor_chunks());
2167 set_monitor_chunks(chunk);
2168 }
2169
2170 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2171 guarantee(monitor_chunks() != NULL, "must be non empty");
2172 if (monitor_chunks() == chunk) {
2173 set_monitor_chunks(chunk->next());
2174 } else {
2175 MonitorChunk* prev = monitor_chunks();
2176 while (prev->next() != chunk) prev = prev->next();
2177 prev->set_next(chunk->next());
2178 }
2179 }
2180
2181 // JVM support.
2182
2183 // Note: this function shouldn't block if it's called in
2184 // _thread_in_native_trans state (such as from
2185 // check_special_condition_for_native_trans()).
2186 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2187
2188 if (has_last_Java_frame() && has_async_condition()) {
2189 // If we are at a polling page safepoint (not a poll return)
2190 // then we must defer async exception because live registers
2191 // will be clobbered by the exception path. Poll return is
2192 // ok because the call we a returning from already collides
2193 // with exception handling registers and so there is no issue.
2194 // (The exception handling path kills call result registers but
2195 // this is ok since the exception kills the result anyway).
2196
2197 if (is_at_poll_safepoint()) {
2198 // if the code we are returning to has deoptimized we must defer
2199 // the exception otherwise live registers get clobbered on the
2200 // exception path before deoptimization is able to retrieve them.
2201 //
2202 RegisterMap map(this, false);
2203 frame caller_fr = last_frame().sender(&map);
2204 assert(caller_fr.is_compiled_frame(), "what?");
2205 if (caller_fr.is_deoptimized_frame()) {
2206 log_info(exceptions)("deferred async exception at compiled safepoint");
2207 return;
2208 }
2209 }
2210 }
2211
2212 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2213 if (condition == _no_async_condition) {
2214 // Conditions have changed since has_special_runtime_exit_condition()
2215 // was called:
2216 // - if we were here only because of an external suspend request,
2217 // then that was taken care of above (or cancelled) so we are done
2218 // - if we were here because of another async request, then it has
2219 // been cleared between the has_special_runtime_exit_condition()
2220 // and now so again we are done
2221 return;
2222 }
2223
2224 // Check for pending async. exception
2225 if (_pending_async_exception != NULL) {
2226 // Only overwrite an already pending exception, if it is not a threadDeath.
2227 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2228
2229 // We cannot call Exceptions::_throw(...) here because we cannot block
2230 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2231
2232 LogTarget(Info, exceptions) lt;
2233 if (lt.is_enabled()) {
2234 ResourceMark rm;
2235 LogStream ls(lt);
2236 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2237 if (has_last_Java_frame()) {
2238 frame f = last_frame();
2239 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2240 }
2241 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2242 }
2243 _pending_async_exception = NULL;
2244 clear_has_async_exception();
2245 }
2246 }
2247
2248 if (check_unsafe_error &&
2249 condition == _async_unsafe_access_error && !has_pending_exception()) {
2250 condition = _no_async_condition; // done
2251 switch (thread_state()) {
2252 case _thread_in_vm: {
2253 JavaThread* THREAD = this;
2254 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2255 }
2256 case _thread_in_native: {
2257 ThreadInVMfromNative tiv(this);
2258 JavaThread* THREAD = this;
2259 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2260 }
2261 case _thread_in_Java: {
2262 ThreadInVMfromJava tiv(this);
2263 JavaThread* THREAD = this;
2264 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2265 }
2266 default:
2267 ShouldNotReachHere();
2268 }
2269 }
2270
2271 assert(condition == _no_async_condition || has_pending_exception() ||
2272 (!check_unsafe_error && condition == _async_unsafe_access_error),
2273 "must have handled the async condition, if no exception");
2274 }
2275
2276 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2277 //
2278 // Check for pending external suspend.
2279 // If JNIEnv proxies are allowed, don't self-suspend if the target
2280 // thread is not the current thread. In older versions of jdbx, jdbx
2281 // threads could call into the VM with another thread's JNIEnv so we
2282 // can be here operating on behalf of a suspended thread (4432884).
2283 bool do_self_suspend = is_external_suspend_with_lock();
2284 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2285 frame_anchor()->make_walkable(this);
2286 java_suspend_self_with_safepoint_check();
2287 }
2288
2289 // We might be here for reasons in addition to the self-suspend request
2290 // so check for other async requests.
2291 if (check_asyncs) {
2292 check_and_handle_async_exceptions();
2293 }
2294
2295 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2296 }
2297
2298 void JavaThread::send_thread_stop(oop java_throwable) {
2299 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2300 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2301 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2302
2303 // Do not throw asynchronous exceptions against the compiler thread
2304 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2305 if (!can_call_java()) return;
2306
2307 {
2308 // Actually throw the Throwable against the target Thread - however
2309 // only if there is no thread death exception installed already.
2310 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2311 // If the topmost frame is a runtime stub, then we are calling into
2312 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2313 // must deoptimize the caller before continuing, as the compiled exception handler table
2314 // may not be valid
2315 if (has_last_Java_frame()) {
2316 frame f = last_frame();
2317 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2318 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2319 RegisterMap reg_map(this, UseBiasedLocking);
2320 frame compiled_frame = f.sender(®_map);
2321 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2322 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2323 }
2324 }
2325 }
2326
2327 // Set async. pending exception in thread.
2328 set_pending_async_exception(java_throwable);
2329
2330 if (log_is_enabled(Info, exceptions)) {
2331 ResourceMark rm;
2332 log_info(exceptions)("Pending Async. exception installed of type: %s",
2333 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2334 }
2335 // for AbortVMOnException flag
2336 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2337 }
2338 }
2339
2340
2341 // Interrupt thread so it will wake up from a potential wait()
2342 Thread::interrupt(this);
2343 }
2344
2345 // External suspension mechanism.
2346 //
2347 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2348 // to any VM_locks and it is at a transition
2349 // Self-suspension will happen on the transition out of the vm.
2350 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2351 //
2352 // Guarantees on return:
2353 // + Target thread will not execute any new bytecode (that's why we need to
2354 // force a safepoint)
2355 // + Target thread will not enter any new monitors
2356 //
2357 void JavaThread::java_suspend() {
2358 ThreadsListHandle tlh;
2359 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2360 return;
2361 }
2362
2363 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2364 if (!is_external_suspend()) {
2365 // a racing resume has cancelled us; bail out now
2366 return;
2367 }
2368
2369 // suspend is done
2370 uint32_t debug_bits = 0;
2371 // Warning: is_ext_suspend_completed() may temporarily drop the
2372 // SR_lock to allow the thread to reach a stable thread state if
2373 // it is currently in a transient thread state.
2374 if (is_ext_suspend_completed(false /* !called_by_wait */,
2375 SuspendRetryDelay, &debug_bits)) {
2376 return;
2377 }
2378 }
2379
2380 if (Thread::current() == this) {
2381 // Safely self-suspend.
2382 // If we don't do this explicitly it will implicitly happen
2383 // before we transition back to Java, and on some other thread-state
2384 // transition paths, but not as we exit a JVM TI SuspendThread call.
2385 // As SuspendThread(current) must not return (until resumed) we must
2386 // self-suspend here.
2387 ThreadBlockInVM tbivm(this);
2388 java_suspend_self();
2389 } else {
2390 VM_ThreadSuspend vm_suspend;
2391 VMThread::execute(&vm_suspend);
2392 }
2393 }
2394
2395 // Part II of external suspension.
2396 // A JavaThread self suspends when it detects a pending external suspend
2397 // request. This is usually on transitions. It is also done in places
2398 // where continuing to the next transition would surprise the caller,
2399 // e.g., monitor entry.
2400 //
2401 // Returns the number of times that the thread self-suspended.
2402 //
2403 // Note: DO NOT call java_suspend_self() when you just want to block current
2404 // thread. java_suspend_self() is the second stage of cooperative
2405 // suspension for external suspend requests and should only be used
2406 // to complete an external suspend request.
2407 //
2408 int JavaThread::java_suspend_self() {
2409 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2410 int ret = 0;
2411
2412 // we are in the process of exiting so don't suspend
2413 if (is_exiting()) {
2414 clear_external_suspend();
2415 return ret;
2416 }
2417
2418 assert(_anchor.walkable() ||
2419 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2420 "must have walkable stack");
2421
2422 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2423
2424 assert(!this->is_ext_suspended(),
2425 "a thread trying to self-suspend should not already be suspended");
2426
2427 if (this->is_suspend_equivalent()) {
2428 // If we are self-suspending as a result of the lifting of a
2429 // suspend equivalent condition, then the suspend_equivalent
2430 // flag is not cleared until we set the ext_suspended flag so
2431 // that wait_for_ext_suspend_completion() returns consistent
2432 // results.
2433 this->clear_suspend_equivalent();
2434 }
2435
2436 // A racing resume may have cancelled us before we grabbed SR_lock
2437 // above. Or another external suspend request could be waiting for us
2438 // by the time we return from SR_lock()->wait(). The thread
2439 // that requested the suspension may already be trying to walk our
2440 // stack and if we return now, we can change the stack out from under
2441 // it. This would be a "bad thing (TM)" and cause the stack walker
2442 // to crash. We stay self-suspended until there are no more pending
2443 // external suspend requests.
2444 while (is_external_suspend()) {
2445 ret++;
2446 this->set_ext_suspended();
2447
2448 // _ext_suspended flag is cleared by java_resume()
2449 while (is_ext_suspended()) {
2450 ml.wait();
2451 }
2452 }
2453 return ret;
2454 }
2455
2456 // Helper routine to set up the correct thread state before calling java_suspend_self.
2457 // This is called when regular thread-state transition helpers can't be used because
2458 // we can be in various states, in particular _thread_in_native_trans.
2459 // Because this thread is external suspended the safepoint code will count it as at
2460 // a safepoint, regardless of what its actual current thread-state is. But
2461 // is_ext_suspend_completed() may be waiting to see a thread transition from
2462 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2463 // to _thread_blocked. The problem with setting thread state directly is that a
2464 // safepoint could happen just after java_suspend_self() returns after being resumed,
2465 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2466 // after restoring the state to make sure we won't leave while a safepoint is in progress.
2467 // However, not all initial-states are allowed when performing a safepoint check, as we
2468 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2469 // only _thread_in_native is possible when executing this code (based on our two callers).
2470 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2471 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2472 // and so we don't need the explicit safepoint check.
2473
2474 void JavaThread::java_suspend_self_with_safepoint_check() {
2475 assert(this == Thread::current(), "invariant");
2476 JavaThreadState state = thread_state();
2477 set_thread_state(_thread_blocked);
2478 java_suspend_self();
2479 set_thread_state_fence(state);
2480 // Since we are not using a regular thread-state transition helper here,
2481 // we must manually emit the instruction barrier after leaving a safe state.
2482 OrderAccess::cross_modify_fence();
2483 if (state != _thread_in_native) {
2484 SafepointMechanism::block_if_requested(this);
2485 }
2486 }
2487
2488 #ifdef ASSERT
2489 // Verify the JavaThread has not yet been published in the Threads::list, and
2490 // hence doesn't need protection from concurrent access at this stage.
2491 void JavaThread::verify_not_published() {
2492 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2493 // since an unpublished JavaThread doesn't participate in the
2494 // Thread-SMR protocol for keeping a ThreadsList alive.
2495 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2496 }
2497 #endif
2498
2499 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2500 // progress or when _suspend_flags is non-zero.
2501 // Current thread needs to self-suspend if there is a suspend request and/or
2502 // block if a safepoint is in progress.
2503 // Async exception ISN'T checked.
2504 // Note only the ThreadInVMfromNative transition can call this function
2505 // directly and when thread state is _thread_in_native_trans
2506 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2507 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2508
2509 JavaThread *curJT = JavaThread::current();
2510 bool do_self_suspend = thread->is_external_suspend();
2511
2512 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2513
2514 // If JNIEnv proxies are allowed, don't self-suspend if the target
2515 // thread is not the current thread. In older versions of jdbx, jdbx
2516 // threads could call into the VM with another thread's JNIEnv so we
2517 // can be here operating on behalf of a suspended thread (4432884).
2518 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2519 thread->java_suspend_self_with_safepoint_check();
2520 } else {
2521 SafepointMechanism::block_if_requested(curJT);
2522 }
2523
2524 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2525 }
2526
2527 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2528 // progress or when _suspend_flags is non-zero.
2529 // Current thread needs to self-suspend if there is a suspend request and/or
2530 // block if a safepoint is in progress.
2531 // Also check for pending async exception (not including unsafe access error).
2532 // Note only the native==>VM/Java barriers can call this function and when
2533 // thread state is _thread_in_native_trans.
2534 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2535 check_safepoint_and_suspend_for_native_trans(thread);
2536
2537 if (thread->has_async_exception()) {
2538 // We are in _thread_in_native_trans state, don't handle unsafe
2539 // access error since that may block.
2540 thread->check_and_handle_async_exceptions(false);
2541 }
2542 }
2543
2544 // This is a variant of the normal
2545 // check_special_condition_for_native_trans with slightly different
2546 // semantics for use by critical native wrappers. It does all the
2547 // normal checks but also performs the transition back into
2548 // thread_in_Java state. This is required so that critical natives
2549 // can potentially block and perform a GC if they are the last thread
2550 // exiting the GCLocker.
2551 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2552 check_special_condition_for_native_trans(thread);
2553
2554 // Finish the transition
2555 thread->set_thread_state(_thread_in_Java);
2556
2557 if (thread->do_critical_native_unlock()) {
2558 ThreadInVMfromJavaNoAsyncException tiv(thread);
2559 GCLocker::unlock_critical(thread);
2560 thread->clear_critical_native_unlock();
2561 }
2562 }
2563
2564 // We need to guarantee the Threads_lock here, since resumes are not
2565 // allowed during safepoint synchronization
2566 // Can only resume from an external suspension
2567 void JavaThread::java_resume() {
2568 assert_locked_or_safepoint(Threads_lock);
2569
2570 // Sanity check: thread is gone, has started exiting or the thread
2571 // was not externally suspended.
2572 ThreadsListHandle tlh;
2573 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2574 return;
2575 }
2576
2577 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2578
2579 clear_external_suspend();
2580
2581 if (is_ext_suspended()) {
2582 clear_ext_suspended();
2583 SR_lock()->notify_all();
2584 }
2585 }
2586
2587 size_t JavaThread::_stack_red_zone_size = 0;
2588 size_t JavaThread::_stack_yellow_zone_size = 0;
2589 size_t JavaThread::_stack_reserved_zone_size = 0;
2590 size_t JavaThread::_stack_shadow_zone_size = 0;
2591
2592 void JavaThread::create_stack_guard_pages() {
2593 if (!os::uses_stack_guard_pages() ||
2594 _stack_guard_state != stack_guard_unused ||
2595 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2596 log_info(os, thread)("Stack guard page creation for thread "
2597 UINTX_FORMAT " disabled", os::current_thread_id());
2598 return;
2599 }
2600 address low_addr = stack_end();
2601 size_t len = stack_guard_zone_size();
2602
2603 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2604 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2605
2606 int must_commit = os::must_commit_stack_guard_pages();
2607 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2608
2609 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2610 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2611 return;
2612 }
2613
2614 if (os::guard_memory((char *) low_addr, len)) {
2615 _stack_guard_state = stack_guard_enabled;
2616 } else {
2617 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2618 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2619 if (os::uncommit_memory((char *) low_addr, len)) {
2620 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2621 }
2622 return;
2623 }
2624
2625 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2626 PTR_FORMAT "-" PTR_FORMAT ".",
2627 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2628 }
2629
2630 void JavaThread::remove_stack_guard_pages() {
2631 assert(Thread::current() == this, "from different thread");
2632 if (_stack_guard_state == stack_guard_unused) return;
2633 address low_addr = stack_end();
2634 size_t len = stack_guard_zone_size();
2635
2636 if (os::must_commit_stack_guard_pages()) {
2637 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2638 _stack_guard_state = stack_guard_unused;
2639 } else {
2640 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2641 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2642 return;
2643 }
2644 } else {
2645 if (_stack_guard_state == stack_guard_unused) return;
2646 if (os::unguard_memory((char *) low_addr, len)) {
2647 _stack_guard_state = stack_guard_unused;
2648 } else {
2649 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2650 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2651 return;
2652 }
2653 }
2654
2655 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2656 PTR_FORMAT "-" PTR_FORMAT ".",
2657 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2658 }
2659
2660 void JavaThread::enable_stack_reserved_zone() {
2661 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2662
2663 // The base notation is from the stack's point of view, growing downward.
2664 // We need to adjust it to work correctly with guard_memory()
2665 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2666
2667 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2668 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2669
2670 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2671 _stack_guard_state = stack_guard_enabled;
2672 } else {
2673 warning("Attempt to guard stack reserved zone failed.");
2674 }
2675 enable_register_stack_guard();
2676 }
2677
2678 void JavaThread::disable_stack_reserved_zone() {
2679 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2680
2681 // Simply return if called for a thread that does not use guard pages.
2682 if (_stack_guard_state != stack_guard_enabled) return;
2683
2684 // The base notation is from the stack's point of view, growing downward.
2685 // We need to adjust it to work correctly with guard_memory()
2686 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2687
2688 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2689 _stack_guard_state = stack_guard_reserved_disabled;
2690 } else {
2691 warning("Attempt to unguard stack reserved zone failed.");
2692 }
2693 disable_register_stack_guard();
2694 }
2695
2696 void JavaThread::enable_stack_yellow_reserved_zone() {
2697 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2698 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2699
2700 // The base notation is from the stacks point of view, growing downward.
2701 // We need to adjust it to work correctly with guard_memory()
2702 address base = stack_red_zone_base();
2703
2704 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2705 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2706
2707 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2708 _stack_guard_state = stack_guard_enabled;
2709 } else {
2710 warning("Attempt to guard stack yellow zone failed.");
2711 }
2712 enable_register_stack_guard();
2713 }
2714
2715 void JavaThread::disable_stack_yellow_reserved_zone() {
2716 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2717 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2718
2719 // Simply return if called for a thread that does not use guard pages.
2720 if (_stack_guard_state == stack_guard_unused) return;
2721
2722 // The base notation is from the stacks point of view, growing downward.
2723 // We need to adjust it to work correctly with guard_memory()
2724 address base = stack_red_zone_base();
2725
2726 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2727 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2728 } else {
2729 warning("Attempt to unguard stack yellow zone failed.");
2730 }
2731 disable_register_stack_guard();
2732 }
2733
2734 void JavaThread::enable_stack_red_zone() {
2735 // The base notation is from the stacks point of view, growing downward.
2736 // We need to adjust it to work correctly with guard_memory()
2737 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2738 address base = stack_red_zone_base() - stack_red_zone_size();
2739
2740 guarantee(base < stack_base(), "Error calculating stack red zone");
2741 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2742
2743 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2744 warning("Attempt to guard stack red zone failed.");
2745 }
2746 }
2747
2748 void JavaThread::disable_stack_red_zone() {
2749 // The base notation is from the stacks point of view, growing downward.
2750 // We need to adjust it to work correctly with guard_memory()
2751 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2752 address base = stack_red_zone_base() - stack_red_zone_size();
2753 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2754 warning("Attempt to unguard stack red zone failed.");
2755 }
2756 }
2757
2758 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2759 // ignore is there is no stack
2760 if (!has_last_Java_frame()) return;
2761 // traverse the stack frames. Starts from top frame.
2762 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2763 frame* fr = fst.current();
2764 f(fr, fst.register_map());
2765 }
2766 }
2767
2768
2769 #ifndef PRODUCT
2770 // Deoptimization
2771 // Function for testing deoptimization
2772 void JavaThread::deoptimize() {
2773 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2774 StackFrameStream fst(this, UseBiasedLocking);
2775 bool deopt = false; // Dump stack only if a deopt actually happens.
2776 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2777 // Iterate over all frames in the thread and deoptimize
2778 for (; !fst.is_done(); fst.next()) {
2779 if (fst.current()->can_be_deoptimized()) {
2780
2781 if (only_at) {
2782 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2783 // consists of comma or carriage return separated numbers so
2784 // search for the current bci in that string.
2785 address pc = fst.current()->pc();
2786 nmethod* nm = (nmethod*) fst.current()->cb();
2787 ScopeDesc* sd = nm->scope_desc_at(pc);
2788 char buffer[8];
2789 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2790 size_t len = strlen(buffer);
2791 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2792 while (found != NULL) {
2793 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2794 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2795 // Check that the bci found is bracketed by terminators.
2796 break;
2797 }
2798 found = strstr(found + 1, buffer);
2799 }
2800 if (!found) {
2801 continue;
2802 }
2803 }
2804
2805 if (DebugDeoptimization && !deopt) {
2806 deopt = true; // One-time only print before deopt
2807 tty->print_cr("[BEFORE Deoptimization]");
2808 trace_frames();
2809 trace_stack();
2810 }
2811 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2812 }
2813 }
2814
2815 if (DebugDeoptimization && deopt) {
2816 tty->print_cr("[AFTER Deoptimization]");
2817 trace_frames();
2818 }
2819 }
2820
2821
2822 // Make zombies
2823 void JavaThread::make_zombies() {
2824 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2825 if (fst.current()->can_be_deoptimized()) {
2826 // it is a Java nmethod
2827 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2828 nm->make_not_entrant();
2829 }
2830 }
2831 }
2832 #endif // PRODUCT
2833
2834
2835 void JavaThread::deoptimized_wrt_marked_nmethods() {
2836 if (!has_last_Java_frame()) return;
2837 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2838 StackFrameStream fst(this, UseBiasedLocking);
2839 for (; !fst.is_done(); fst.next()) {
2840 if (fst.current()->should_be_deoptimized()) {
2841 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2842 }
2843 }
2844 }
2845
2846
2847 // If the caller is a NamedThread, then remember, in the current scope,
2848 // the given JavaThread in its _processed_thread field.
2849 class RememberProcessedThread: public StackObj {
2850 NamedThread* _cur_thr;
2851 public:
2852 RememberProcessedThread(JavaThread* jthr) {
2853 Thread* thread = Thread::current();
2854 if (thread->is_Named_thread()) {
2855 _cur_thr = (NamedThread *)thread;
2856 _cur_thr->set_processed_thread(jthr);
2857 } else {
2858 _cur_thr = NULL;
2859 }
2860 }
2861
2862 ~RememberProcessedThread() {
2863 if (_cur_thr) {
2864 _cur_thr->set_processed_thread(NULL);
2865 }
2866 }
2867 };
2868
2869 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2870 // Verify that the deferred card marks have been flushed.
2871 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2872
2873 // Traverse the GCHandles
2874 Thread::oops_do(f, cf);
2875
2876 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2877 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2878
2879 if (has_last_Java_frame()) {
2880 // Record JavaThread to GC thread
2881 RememberProcessedThread rpt(this);
2882
2883 // traverse the registered growable array
2884 if (_array_for_gc != NULL) {
2885 for (int index = 0; index < _array_for_gc->length(); index++) {
2886 f->do_oop(_array_for_gc->adr_at(index));
2887 }
2888 }
2889
2890 // Traverse the monitor chunks
2891 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2892 chunk->oops_do(f);
2893 }
2894
2895 // Traverse the execution stack
2896 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2897 fst.current()->oops_do(f, cf, fst.register_map());
2898 }
2899 }
2900
2901 // callee_target is never live across a gc point so NULL it here should
2902 // it still contain a methdOop.
2903
2904 set_callee_target(NULL);
2905
2906 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2907 // If we have deferred set_locals there might be oops waiting to be
2908 // written
2909 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2910 if (list != NULL) {
2911 for (int i = 0; i < list->length(); i++) {
2912 list->at(i)->oops_do(f);
2913 }
2914 }
2915
2916 // Traverse instance variables at the end since the GC may be moving things
2917 // around using this function
2918 f->do_oop((oop*) &_threadObj);
2919 f->do_oop((oop*) &_vm_result);
2920 f->do_oop((oop*) &_exception_oop);
2921 f->do_oop((oop*) &_pending_async_exception);
2922
2923 if (jvmti_thread_state() != NULL) {
2924 jvmti_thread_state()->oops_do(f);
2925 }
2926 }
2927
2928 #ifdef ASSERT
2929 void JavaThread::verify_states_for_handshake() {
2930 // This checks that the thread has a correct frame state during a handshake.
2931 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2932 (has_last_Java_frame() && java_call_counter() > 0),
2933 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2934 has_last_Java_frame(), java_call_counter());
2935 }
2936 #endif
2937
2938 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2939 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2940 (has_last_Java_frame() && java_call_counter() > 0),
2941 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
2942 has_last_Java_frame(), java_call_counter());
2943
2944 if (has_last_Java_frame()) {
2945 // Traverse the execution stack
2946 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2947 fst.current()->nmethods_do(cf);
2948 }
2949 }
2950 }
2951
2952 void JavaThread::metadata_do(MetadataClosure* f) {
2953 if (has_last_Java_frame()) {
2954 // Traverse the execution stack to call f() on the methods in the stack
2955 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2956 fst.current()->metadata_do(f);
2957 }
2958 } else if (is_Compiler_thread()) {
2959 // need to walk ciMetadata in current compile tasks to keep alive.
2960 CompilerThread* ct = (CompilerThread*)this;
2961 if (ct->env() != NULL) {
2962 ct->env()->metadata_do(f);
2963 }
2964 CompileTask* task = ct->task();
2965 if (task != NULL) {
2966 task->metadata_do(f);
2967 }
2968 }
2969 }
2970
2971 // Printing
2972 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2973 switch (_thread_state) {
2974 case _thread_uninitialized: return "_thread_uninitialized";
2975 case _thread_new: return "_thread_new";
2976 case _thread_new_trans: return "_thread_new_trans";
2977 case _thread_in_native: return "_thread_in_native";
2978 case _thread_in_native_trans: return "_thread_in_native_trans";
2979 case _thread_in_vm: return "_thread_in_vm";
2980 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2981 case _thread_in_Java: return "_thread_in_Java";
2982 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2983 case _thread_blocked: return "_thread_blocked";
2984 case _thread_blocked_trans: return "_thread_blocked_trans";
2985 default: return "unknown thread state";
2986 }
2987 }
2988
2989 #ifndef PRODUCT
2990 void JavaThread::print_thread_state_on(outputStream *st) const {
2991 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2992 };
2993 void JavaThread::print_thread_state() const {
2994 print_thread_state_on(tty);
2995 }
2996 #endif // PRODUCT
2997
2998 // Called by Threads::print() for VM_PrintThreads operation
2999 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3000 st->print_raw("\"");
3001 st->print_raw(get_thread_name());
3002 st->print_raw("\" ");
3003 oop thread_oop = threadObj();
3004 if (thread_oop != NULL) {
3005 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3006 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3007 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3008 }
3009 Thread::print_on(st, print_extended_info);
3010 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3011 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3012 if (thread_oop != NULL) {
3013 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3014 }
3015 #ifndef PRODUCT
3016 _safepoint_state->print_on(st);
3017 #endif // PRODUCT
3018 if (is_Compiler_thread()) {
3019 CompileTask *task = ((CompilerThread*)this)->task();
3020 if (task != NULL) {
3021 st->print(" Compiling: ");
3022 task->print(st, NULL, true, false);
3023 } else {
3024 st->print(" No compile task");
3025 }
3026 st->cr();
3027 }
3028 }
3029
3030 void JavaThread::print() const { print_on(tty); }
3031
3032 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3033 st->print("%s", get_thread_name_string(buf, buflen));
3034 }
3035
3036 // Called by fatal error handler. The difference between this and
3037 // JavaThread::print() is that we can't grab lock or allocate memory.
3038 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3039 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3040 oop thread_obj = threadObj();
3041 if (thread_obj != NULL) {
3042 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3043 }
3044 st->print(" [");
3045 st->print("%s", _get_thread_state_name(_thread_state));
3046 if (osthread()) {
3047 st->print(", id=%d", osthread()->thread_id());
3048 }
3049 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3050 p2i(stack_end()), p2i(stack_base()));
3051 st->print("]");
3052
3053 ThreadsSMRSupport::print_info_on(this, st);
3054 return;
3055 }
3056
3057 // Verification
3058
3059 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3060
3061 void JavaThread::verify() {
3062 // Verify oops in the thread.
3063 oops_do(&VerifyOopClosure::verify_oop, NULL);
3064
3065 // Verify the stack frames.
3066 frames_do(frame_verify);
3067 }
3068
3069 // CR 6300358 (sub-CR 2137150)
3070 // Most callers of this method assume that it can't return NULL but a
3071 // thread may not have a name whilst it is in the process of attaching to
3072 // the VM - see CR 6412693, and there are places where a JavaThread can be
3073 // seen prior to having it's threadObj set (eg JNI attaching threads and
3074 // if vm exit occurs during initialization). These cases can all be accounted
3075 // for such that this method never returns NULL.
3076 const char* JavaThread::get_thread_name() const {
3077 #ifdef ASSERT
3078 // early safepoints can hit while current thread does not yet have TLS
3079 if (!SafepointSynchronize::is_at_safepoint()) {
3080 Thread *cur = Thread::current();
3081 if (!(cur->is_Java_thread() && cur == this)) {
3082 // Current JavaThreads are allowed to get their own name without
3083 // the Threads_lock.
3084 assert_locked_or_safepoint(Threads_lock);
3085 }
3086 }
3087 #endif // ASSERT
3088 return get_thread_name_string();
3089 }
3090
3091 // Returns a non-NULL representation of this thread's name, or a suitable
3092 // descriptive string if there is no set name
3093 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3094 const char* name_str;
3095 oop thread_obj = threadObj();
3096 if (thread_obj != NULL) {
3097 oop name = java_lang_Thread::name(thread_obj);
3098 if (name != NULL) {
3099 if (buf == NULL) {
3100 name_str = java_lang_String::as_utf8_string(name);
3101 } else {
3102 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3103 }
3104 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3105 name_str = "<no-name - thread is attaching>";
3106 } else {
3107 name_str = Thread::name();
3108 }
3109 } else {
3110 name_str = Thread::name();
3111 }
3112 assert(name_str != NULL, "unexpected NULL thread name");
3113 return name_str;
3114 }
3115
3116
3117 const char* JavaThread::get_threadgroup_name() const {
3118 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3119 oop thread_obj = threadObj();
3120 if (thread_obj != NULL) {
3121 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3122 if (thread_group != NULL) {
3123 // ThreadGroup.name can be null
3124 return java_lang_ThreadGroup::name(thread_group);
3125 }
3126 }
3127 return NULL;
3128 }
3129
3130 const char* JavaThread::get_parent_name() const {
3131 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3132 oop thread_obj = threadObj();
3133 if (thread_obj != NULL) {
3134 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3135 if (thread_group != NULL) {
3136 oop parent = java_lang_ThreadGroup::parent(thread_group);
3137 if (parent != NULL) {
3138 // ThreadGroup.name can be null
3139 return java_lang_ThreadGroup::name(parent);
3140 }
3141 }
3142 }
3143 return NULL;
3144 }
3145
3146 ThreadPriority JavaThread::java_priority() const {
3147 oop thr_oop = threadObj();
3148 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3149 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3150 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3151 return priority;
3152 }
3153
3154 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3155
3156 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3157 // Link Java Thread object <-> C++ Thread
3158
3159 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3160 // and put it into a new Handle. The Handle "thread_oop" can then
3161 // be used to pass the C++ thread object to other methods.
3162
3163 // Set the Java level thread object (jthread) field of the
3164 // new thread (a JavaThread *) to C++ thread object using the
3165 // "thread_oop" handle.
3166
3167 // Set the thread field (a JavaThread *) of the
3168 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3169
3170 Handle thread_oop(Thread::current(),
3171 JNIHandles::resolve_non_null(jni_thread));
3172 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3173 "must be initialized");
3174 set_threadObj(thread_oop());
3175 java_lang_Thread::set_thread(thread_oop(), this);
3176
3177 if (prio == NoPriority) {
3178 prio = java_lang_Thread::priority(thread_oop());
3179 assert(prio != NoPriority, "A valid priority should be present");
3180 }
3181
3182 // Push the Java priority down to the native thread; needs Threads_lock
3183 Thread::set_priority(this, prio);
3184
3185 // Add the new thread to the Threads list and set it in motion.
3186 // We must have threads lock in order to call Threads::add.
3187 // It is crucial that we do not block before the thread is
3188 // added to the Threads list for if a GC happens, then the java_thread oop
3189 // will not be visited by GC.
3190 Threads::add(this);
3191 }
3192
3193 oop JavaThread::current_park_blocker() {
3194 // Support for JSR-166 locks
3195 oop thread_oop = threadObj();
3196 if (thread_oop != NULL) {
3197 return java_lang_Thread::park_blocker(thread_oop);
3198 }
3199 return NULL;
3200 }
3201
3202
3203 void JavaThread::print_stack_on(outputStream* st) {
3204 if (!has_last_Java_frame()) return;
3205 ResourceMark rm;
3206 HandleMark hm;
3207
3208 RegisterMap reg_map(this);
3209 vframe* start_vf = last_java_vframe(®_map);
3210 int count = 0;
3211 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3212 if (f->is_java_frame()) {
3213 javaVFrame* jvf = javaVFrame::cast(f);
3214 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3215
3216 // Print out lock information
3217 if (JavaMonitorsInStackTrace) {
3218 jvf->print_lock_info_on(st, count);
3219 }
3220 } else {
3221 // Ignore non-Java frames
3222 }
3223
3224 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3225 count++;
3226 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3227 }
3228 }
3229
3230
3231 // JVMTI PopFrame support
3232 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3233 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3234 if (in_bytes(size_in_bytes) != 0) {
3235 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3236 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3237 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3238 }
3239 }
3240
3241 void* JavaThread::popframe_preserved_args() {
3242 return _popframe_preserved_args;
3243 }
3244
3245 ByteSize JavaThread::popframe_preserved_args_size() {
3246 return in_ByteSize(_popframe_preserved_args_size);
3247 }
3248
3249 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3250 int sz = in_bytes(popframe_preserved_args_size());
3251 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3252 return in_WordSize(sz / wordSize);
3253 }
3254
3255 void JavaThread::popframe_free_preserved_args() {
3256 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3257 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3258 _popframe_preserved_args = NULL;
3259 _popframe_preserved_args_size = 0;
3260 }
3261
3262 #ifndef PRODUCT
3263
3264 void JavaThread::trace_frames() {
3265 tty->print_cr("[Describe stack]");
3266 int frame_no = 1;
3267 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3268 tty->print(" %d. ", frame_no++);
3269 fst.current()->print_value_on(tty, this);
3270 tty->cr();
3271 }
3272 }
3273
3274 class PrintAndVerifyOopClosure: public OopClosure {
3275 protected:
3276 template <class T> inline void do_oop_work(T* p) {
3277 oop obj = RawAccess<>::oop_load(p);
3278 if (obj == NULL) return;
3279 tty->print(INTPTR_FORMAT ": ", p2i(p));
3280 if (oopDesc::is_oop_or_null(obj)) {
3281 if (obj->is_objArray()) {
3282 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3283 } else {
3284 obj->print();
3285 }
3286 } else {
3287 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3288 }
3289 tty->cr();
3290 }
3291 public:
3292 virtual void do_oop(oop* p) { do_oop_work(p); }
3293 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3294 };
3295
3296
3297 static void oops_print(frame* f, const RegisterMap *map) {
3298 PrintAndVerifyOopClosure print;
3299 f->print_value();
3300 f->oops_do(&print, NULL, (RegisterMap*)map);
3301 }
3302
3303 // Print our all the locations that contain oops and whether they are
3304 // valid or not. This useful when trying to find the oldest frame
3305 // where an oop has gone bad since the frame walk is from youngest to
3306 // oldest.
3307 void JavaThread::trace_oops() {
3308 tty->print_cr("[Trace oops]");
3309 frames_do(oops_print);
3310 }
3311
3312
3313 #ifdef ASSERT
3314 // Print or validate the layout of stack frames
3315 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3316 ResourceMark rm;
3317 PRESERVE_EXCEPTION_MARK;
3318 FrameValues values;
3319 int frame_no = 0;
3320 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3321 fst.current()->describe(values, ++frame_no);
3322 if (depth == frame_no) break;
3323 }
3324 if (validate_only) {
3325 values.validate();
3326 } else {
3327 tty->print_cr("[Describe stack layout]");
3328 values.print(this);
3329 }
3330 }
3331 #endif
3332
3333 void JavaThread::trace_stack_from(vframe* start_vf) {
3334 ResourceMark rm;
3335 int vframe_no = 1;
3336 for (vframe* f = start_vf; f; f = f->sender()) {
3337 if (f->is_java_frame()) {
3338 javaVFrame::cast(f)->print_activation(vframe_no++);
3339 } else {
3340 f->print();
3341 }
3342 if (vframe_no > StackPrintLimit) {
3343 tty->print_cr("...<more frames>...");
3344 return;
3345 }
3346 }
3347 }
3348
3349
3350 void JavaThread::trace_stack() {
3351 if (!has_last_Java_frame()) return;
3352 ResourceMark rm;
3353 HandleMark hm;
3354 RegisterMap reg_map(this);
3355 trace_stack_from(last_java_vframe(®_map));
3356 }
3357
3358
3359 #endif // PRODUCT
3360
3361
3362 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3363 assert(reg_map != NULL, "a map must be given");
3364 frame f = last_frame();
3365 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3366 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3367 }
3368 return NULL;
3369 }
3370
3371
3372 Klass* JavaThread::security_get_caller_class(int depth) {
3373 vframeStream vfst(this);
3374 vfst.security_get_caller_frame(depth);
3375 if (!vfst.at_end()) {
3376 return vfst.method()->method_holder();
3377 }
3378 return NULL;
3379 }
3380
3381 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3382 assert(thread->is_Compiler_thread(), "must be compiler thread");
3383 CompileBroker::compiler_thread_loop();
3384 }
3385
3386 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3387 NMethodSweeper::sweeper_loop();
3388 }
3389
3390 // Create a CompilerThread
3391 CompilerThread::CompilerThread(CompileQueue* queue,
3392 CompilerCounters* counters)
3393 : JavaThread(&compiler_thread_entry) {
3394 _env = NULL;
3395 _log = NULL;
3396 _task = NULL;
3397 _queue = queue;
3398 _counters = counters;
3399 _buffer_blob = NULL;
3400 _compiler = NULL;
3401
3402 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3403 resource_area()->bias_to(mtCompiler);
3404
3405 #ifndef PRODUCT
3406 _ideal_graph_printer = NULL;
3407 #endif
3408 }
3409
3410 CompilerThread::~CompilerThread() {
3411 // Delete objects which were allocated on heap.
3412 delete _counters;
3413 }
3414
3415 bool CompilerThread::can_call_java() const {
3416 return _compiler != NULL && _compiler->is_jvmci();
3417 }
3418
3419 // Create sweeper thread
3420 CodeCacheSweeperThread::CodeCacheSweeperThread()
3421 : JavaThread(&sweeper_thread_entry) {
3422 _scanned_compiled_method = NULL;
3423 }
3424
3425 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3426 JavaThread::oops_do(f, cf);
3427 if (_scanned_compiled_method != NULL && cf != NULL) {
3428 // Safepoints can occur when the sweeper is scanning an nmethod so
3429 // process it here to make sure it isn't unloaded in the middle of
3430 // a scan.
3431 cf->do_code_blob(_scanned_compiled_method);
3432 }
3433 }
3434
3435 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3436 JavaThread::nmethods_do(cf);
3437 if (_scanned_compiled_method != NULL && cf != NULL) {
3438 // Safepoints can occur when the sweeper is scanning an nmethod so
3439 // process it here to make sure it isn't unloaded in the middle of
3440 // a scan.
3441 cf->do_code_blob(_scanned_compiled_method);
3442 }
3443 }
3444
3445
3446 // ======= Threads ========
3447
3448 // The Threads class links together all active threads, and provides
3449 // operations over all threads. It is protected by the Threads_lock,
3450 // which is also used in other global contexts like safepointing.
3451 // ThreadsListHandles are used to safely perform operations on one
3452 // or more threads without the risk of the thread exiting during the
3453 // operation.
3454 //
3455 // Note: The Threads_lock is currently more widely used than we
3456 // would like. We are actively migrating Threads_lock uses to other
3457 // mechanisms in order to reduce Threads_lock contention.
3458
3459 int Threads::_number_of_threads = 0;
3460 int Threads::_number_of_non_daemon_threads = 0;
3461 int Threads::_return_code = 0;
3462 uintx Threads::_thread_claim_token = 1; // Never zero.
3463 size_t JavaThread::_stack_size_at_create = 0;
3464
3465 #ifdef ASSERT
3466 bool Threads::_vm_complete = false;
3467 #endif
3468
3469 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3470 Prefetch::read((void*)addr, prefetch_interval);
3471 return *addr;
3472 }
3473
3474 // Possibly the ugliest for loop the world has seen. C++ does not allow
3475 // multiple types in the declaration section of the for loop. In this case
3476 // we are only dealing with pointers and hence can cast them. It looks ugly
3477 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3478 #define DO_JAVA_THREADS(LIST, X) \
3479 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3480 *MACRO_list = (JavaThread*)(LIST), \
3481 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3482 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3483 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3484 MACRO_current_p != MACRO_end; \
3485 MACRO_current_p++, \
3486 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3487
3488 // All JavaThreads
3489 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3490
3491 // All NonJavaThreads (i.e., every non-JavaThread in the system).
3492 void Threads::non_java_threads_do(ThreadClosure* tc) {
3493 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3494 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3495 tc->do_thread(njti.current());
3496 }
3497 }
3498
3499 // All JavaThreads
3500 void Threads::java_threads_do(ThreadClosure* tc) {
3501 assert_locked_or_safepoint(Threads_lock);
3502 // ALL_JAVA_THREADS iterates through all JavaThreads.
3503 ALL_JAVA_THREADS(p) {
3504 tc->do_thread(p);
3505 }
3506 }
3507
3508 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3509 assert_locked_or_safepoint(Threads_lock);
3510 java_threads_do(tc);
3511 tc->do_thread(VMThread::vm_thread());
3512 }
3513
3514 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3515 void Threads::threads_do(ThreadClosure* tc) {
3516 assert_locked_or_safepoint(Threads_lock);
3517 java_threads_do(tc);
3518 non_java_threads_do(tc);
3519 }
3520
3521 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3522 uintx claim_token = Threads::thread_claim_token();
3523 ALL_JAVA_THREADS(p) {
3524 if (p->claim_threads_do(is_par, claim_token)) {
3525 tc->do_thread(p);
3526 }
3527 }
3528 VMThread* vmt = VMThread::vm_thread();
3529 if (vmt->claim_threads_do(is_par, claim_token)) {
3530 tc->do_thread(vmt);
3531 }
3532 }
3533
3534 // The system initialization in the library has three phases.
3535 //
3536 // Phase 1: java.lang.System class initialization
3537 // java.lang.System is a primordial class loaded and initialized
3538 // by the VM early during startup. java.lang.System.<clinit>
3539 // only does registerNatives and keeps the rest of the class
3540 // initialization work later until thread initialization completes.
3541 //
3542 // System.initPhase1 initializes the system properties, the static
3543 // fields in, out, and err. Set up java signal handlers, OS-specific
3544 // system settings, and thread group of the main thread.
3545 static void call_initPhase1(TRAPS) {
3546 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3547 JavaValue result(T_VOID);
3548 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3549 vmSymbols::void_method_signature(), CHECK);
3550 }
3551
3552 // Phase 2. Module system initialization
3553 // This will initialize the module system. Only java.base classes
3554 // can be loaded until phase 2 completes.
3555 //
3556 // Call System.initPhase2 after the compiler initialization and jsr292
3557 // classes get initialized because module initialization runs a lot of java
3558 // code, that for performance reasons, should be compiled. Also, this will
3559 // enable the startup code to use lambda and other language features in this
3560 // phase and onward.
3561 //
3562 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3563 static void call_initPhase2(TRAPS) {
3564 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3565
3566 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3567
3568 JavaValue result(T_INT);
3569 JavaCallArguments args;
3570 args.push_int(DisplayVMOutputToStderr);
3571 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3572 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3573 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3574 if (result.get_jint() != JNI_OK) {
3575 vm_exit_during_initialization(); // no message or exception
3576 }
3577
3578 universe_post_module_init();
3579 }
3580
3581 // Phase 3. final setup - set security manager, system class loader and TCCL
3582 //
3583 // This will instantiate and set the security manager, set the system class
3584 // loader as well as the thread context class loader. The security manager
3585 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3586 // other modules or the application's classpath.
3587 static void call_initPhase3(TRAPS) {
3588 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3589 JavaValue result(T_VOID);
3590 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3591 vmSymbols::void_method_signature(), CHECK);
3592 }
3593
3594 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3595 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3596
3597 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3598 create_vm_init_libraries();
3599 }
3600
3601 initialize_class(vmSymbols::java_lang_String(), CHECK);
3602
3603 // Inject CompactStrings value after the static initializers for String ran.
3604 java_lang_String::set_compact_strings(CompactStrings);
3605
3606 // Initialize java_lang.System (needed before creating the thread)
3607 initialize_class(vmSymbols::java_lang_System(), CHECK);
3608 // The VM creates & returns objects of this class. Make sure it's initialized.
3609 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3610 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3611 Handle thread_group = create_initial_thread_group(CHECK);
3612 Universe::set_main_thread_group(thread_group());
3613 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3614 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3615 main_thread->set_threadObj(thread_object);
3616
3617 // Set thread status to running since main thread has
3618 // been started and running.
3619 java_lang_Thread::set_thread_status(thread_object,
3620 java_lang_Thread::RUNNABLE);
3621
3622 // The VM creates objects of this class.
3623 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3624
3625 #ifdef ASSERT
3626 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3627 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3628 #endif
3629
3630 // initialize the hardware-specific constants needed by Unsafe
3631 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3632 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3633
3634 // The VM preresolves methods to these classes. Make sure that they get initialized
3635 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3636 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3637
3638 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3639 call_initPhase1(CHECK);
3640
3641 // get the Java runtime name after java.lang.System is initialized
3642 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3643 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3644
3645 // an instance of OutOfMemory exception has been allocated earlier
3646 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3647 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3648 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3649 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3650 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3651 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3652 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3653 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3654 }
3655
3656 void Threads::initialize_jsr292_core_classes(TRAPS) {
3657 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3658
3659 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3660 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3661 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3662 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3663 }
3664
3665 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3666 extern void JDK_Version_init();
3667
3668 // Preinitialize version info.
3669 VM_Version::early_initialize();
3670
3671 // Check version
3672 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3673
3674 // Initialize library-based TLS
3675 ThreadLocalStorage::init();
3676
3677 // Initialize the output stream module
3678 ostream_init();
3679
3680 // Process java launcher properties.
3681 Arguments::process_sun_java_launcher_properties(args);
3682
3683 // Initialize the os module
3684 os::init();
3685
3686 // Record VM creation timing statistics
3687 TraceVmCreationTime create_vm_timer;
3688 create_vm_timer.start();
3689
3690 // Initialize system properties.
3691 Arguments::init_system_properties();
3692
3693 // So that JDK version can be used as a discriminator when parsing arguments
3694 JDK_Version_init();
3695
3696 // Update/Initialize System properties after JDK version number is known
3697 Arguments::init_version_specific_system_properties();
3698
3699 // Make sure to initialize log configuration *before* parsing arguments
3700 LogConfiguration::initialize(create_vm_timer.begin_time());
3701
3702 // Parse arguments
3703 // Note: this internally calls os::init_container_support()
3704 jint parse_result = Arguments::parse(args);
3705 if (parse_result != JNI_OK) return parse_result;
3706
3707 os::init_before_ergo();
3708
3709 jint ergo_result = Arguments::apply_ergo();
3710 if (ergo_result != JNI_OK) return ergo_result;
3711
3712 // Final check of all ranges after ergonomics which may change values.
3713 if (!JVMFlagRangeList::check_ranges()) {
3714 return JNI_EINVAL;
3715 }
3716
3717 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3718 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3719 if (!constraint_result) {
3720 return JNI_EINVAL;
3721 }
3722
3723 JVMFlagWriteableList::mark_startup();
3724
3725 if (PauseAtStartup) {
3726 os::pause();
3727 }
3728
3729 HOTSPOT_VM_INIT_BEGIN();
3730
3731 // Timing (must come after argument parsing)
3732 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3733
3734 // Initialize the os module after parsing the args
3735 jint os_init_2_result = os::init_2();
3736 if (os_init_2_result != JNI_OK) return os_init_2_result;
3737
3738 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3739 // Initialize assert poison page mechanism.
3740 if (ShowRegistersOnAssert) {
3741 initialize_assert_poison();
3742 }
3743 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3744
3745 SafepointMechanism::initialize();
3746
3747 jint adjust_after_os_result = Arguments::adjust_after_os();
3748 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3749
3750 // Initialize output stream logging
3751 ostream_init_log();
3752
3753 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3754 // Must be before create_vm_init_agents()
3755 if (Arguments::init_libraries_at_startup()) {
3756 convert_vm_init_libraries_to_agents();
3757 }
3758
3759 // Launch -agentlib/-agentpath and converted -Xrun agents
3760 if (Arguments::init_agents_at_startup()) {
3761 create_vm_init_agents();
3762 }
3763
3764 // Initialize Threads state
3765 _number_of_threads = 0;
3766 _number_of_non_daemon_threads = 0;
3767
3768 // Initialize global data structures and create system classes in heap
3769 vm_init_globals();
3770
3771 #if INCLUDE_JVMCI
3772 if (JVMCICounterSize > 0) {
3773 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3774 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3775 } else {
3776 JavaThread::_jvmci_old_thread_counters = NULL;
3777 }
3778 #endif // INCLUDE_JVMCI
3779
3780 // Attach the main thread to this os thread
3781 JavaThread* main_thread = new JavaThread();
3782 main_thread->set_thread_state(_thread_in_vm);
3783 main_thread->initialize_thread_current();
3784 // must do this before set_active_handles
3785 main_thread->record_stack_base_and_size();
3786 main_thread->register_thread_stack_with_NMT();
3787 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3788
3789 if (!main_thread->set_as_starting_thread()) {
3790 vm_shutdown_during_initialization(
3791 "Failed necessary internal allocation. Out of swap space");
3792 main_thread->smr_delete();
3793 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3794 return JNI_ENOMEM;
3795 }
3796
3797 // Enable guard page *after* os::create_main_thread(), otherwise it would
3798 // crash Linux VM, see notes in os_linux.cpp.
3799 main_thread->create_stack_guard_pages();
3800
3801 // Initialize Java-Level synchronization subsystem
3802 ObjectMonitor::Initialize();
3803
3804 // Initialize global modules
3805 jint status = init_globals();
3806 if (status != JNI_OK) {
3807 main_thread->smr_delete();
3808 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3809 return status;
3810 }
3811
3812 JFR_ONLY(Jfr::on_vm_init();)
3813
3814 // Should be done after the heap is fully created
3815 main_thread->cache_global_variables();
3816
3817 HandleMark hm;
3818
3819 { MutexLocker mu(Threads_lock);
3820 Threads::add(main_thread);
3821 }
3822
3823 // Any JVMTI raw monitors entered in onload will transition into
3824 // real raw monitor. VM is setup enough here for raw monitor enter.
3825 JvmtiExport::transition_pending_onload_raw_monitors();
3826
3827 // Create the VMThread
3828 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3829
3830 VMThread::create();
3831 Thread* vmthread = VMThread::vm_thread();
3832
3833 if (!os::create_thread(vmthread, os::vm_thread)) {
3834 vm_exit_during_initialization("Cannot create VM thread. "
3835 "Out of system resources.");
3836 }
3837
3838 // Wait for the VM thread to become ready, and VMThread::run to initialize
3839 // Monitors can have spurious returns, must always check another state flag
3840 {
3841 MonitorLocker ml(Notify_lock);
3842 os::start_thread(vmthread);
3843 while (vmthread->active_handles() == NULL) {
3844 ml.wait();
3845 }
3846 }
3847 }
3848
3849 assert(Universe::is_fully_initialized(), "not initialized");
3850 if (VerifyDuringStartup) {
3851 // Make sure we're starting with a clean slate.
3852 VM_Verify verify_op;
3853 VMThread::execute(&verify_op);
3854 }
3855
3856 // We need this to update the java.vm.info property in case any flags used
3857 // to initially define it have been changed. This is needed for both CDS and
3858 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3859 // is initially computed. See Abstract_VM_Version::vm_info_string().
3860 // This update must happen before we initialize the java classes, but
3861 // after any initialization logic that might modify the flags.
3862 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3863
3864 Thread* THREAD = Thread::current();
3865
3866 // Always call even when there are not JVMTI environments yet, since environments
3867 // may be attached late and JVMTI must track phases of VM execution
3868 JvmtiExport::enter_early_start_phase();
3869
3870 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3871 JvmtiExport::post_early_vm_start();
3872
3873 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3874
3875 quicken_jni_functions();
3876
3877 // No more stub generation allowed after that point.
3878 StubCodeDesc::freeze();
3879
3880 // Set flag that basic initialization has completed. Used by exceptions and various
3881 // debug stuff, that does not work until all basic classes have been initialized.
3882 set_init_completed();
3883
3884 LogConfiguration::post_initialize();
3885 Metaspace::post_initialize();
3886
3887 HOTSPOT_VM_INIT_END();
3888
3889 // record VM initialization completion time
3890 #if INCLUDE_MANAGEMENT
3891 Management::record_vm_init_completed();
3892 #endif // INCLUDE_MANAGEMENT
3893
3894 // Signal Dispatcher needs to be started before VMInit event is posted
3895 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3896
3897 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3898 if (!DisableAttachMechanism) {
3899 AttachListener::vm_start();
3900 if (StartAttachListener || AttachListener::init_at_startup()) {
3901 AttachListener::init();
3902 }
3903 }
3904
3905 // Launch -Xrun agents
3906 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3907 // back-end can launch with -Xdebug -Xrunjdwp.
3908 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3909 create_vm_init_libraries();
3910 }
3911
3912 if (CleanChunkPoolAsync) {
3913 Chunk::start_chunk_pool_cleaner_task();
3914 }
3915
3916 // initialize compiler(s)
3917 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3918 #if INCLUDE_JVMCI
3919 bool force_JVMCI_intialization = false;
3920 if (EnableJVMCI) {
3921 // Initialize JVMCI eagerly when it is explicitly requested.
3922 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3923 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3924
3925 if (!force_JVMCI_intialization) {
3926 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3927 // compilations via JVMCI will not actually block until JVMCI is initialized.
3928 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3929 }
3930 }
3931 #endif
3932 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3933 // Postpone completion of compiler initialization to after JVMCI
3934 // is initialized to avoid timeouts of blocking compilations.
3935 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3936 CompileBroker::compilation_init_phase2();
3937 }
3938 #endif
3939
3940 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3941 // It is done after compilers are initialized, because otherwise compilations of
3942 // signature polymorphic MH intrinsics can be missed
3943 // (see SystemDictionary::find_method_handle_intrinsic).
3944 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3945
3946 // This will initialize the module system. Only java.base classes can be
3947 // loaded until phase 2 completes
3948 call_initPhase2(CHECK_JNI_ERR);
3949
3950 // Always call even when there are not JVMTI environments yet, since environments
3951 // may be attached late and JVMTI must track phases of VM execution
3952 JvmtiExport::enter_start_phase();
3953
3954 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3955 JvmtiExport::post_vm_start();
3956
3957 // Final system initialization including security manager and system class loader
3958 call_initPhase3(CHECK_JNI_ERR);
3959
3960 // cache the system and platform class loaders
3961 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3962
3963 #if INCLUDE_CDS
3964 // capture the module path info from the ModuleEntryTable
3965 ClassLoader::initialize_module_path(THREAD);
3966 #endif
3967
3968 #if INCLUDE_JVMCI
3969 if (force_JVMCI_intialization) {
3970 JVMCI::initialize_compiler(CHECK_JNI_ERR);
3971 CompileBroker::compilation_init_phase2();
3972 }
3973 #endif
3974
3975 // Always call even when there are not JVMTI environments yet, since environments
3976 // may be attached late and JVMTI must track phases of VM execution
3977 JvmtiExport::enter_live_phase();
3978
3979 // Make perfmemory accessible
3980 PerfMemory::set_accessible(true);
3981
3982 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3983 JvmtiExport::post_vm_initialized();
3984
3985 JFR_ONLY(Jfr::on_vm_start();)
3986
3987 #if INCLUDE_MANAGEMENT
3988 Management::initialize(THREAD);
3989
3990 if (HAS_PENDING_EXCEPTION) {
3991 // management agent fails to start possibly due to
3992 // configuration problem and is responsible for printing
3993 // stack trace if appropriate. Simply exit VM.
3994 vm_exit(1);
3995 }
3996 #endif // INCLUDE_MANAGEMENT
3997
3998 if (MemProfiling) MemProfiler::engage();
3999 StatSampler::engage();
4000 if (CheckJNICalls) JniPeriodicChecker::engage();
4001
4002 BiasedLocking::init();
4003
4004 #if INCLUDE_RTM_OPT
4005 RTMLockingCounters::init();
4006 #endif
4007
4008 call_postVMInitHook(THREAD);
4009 // The Java side of PostVMInitHook.run must deal with all
4010 // exceptions and provide means of diagnosis.
4011 if (HAS_PENDING_EXCEPTION) {
4012 CLEAR_PENDING_EXCEPTION;
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 || DynamicDumpSharedSpaces) {
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_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 { MonitorLocker 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 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4321 }
4322
4323 EventShutdown e;
4324 if (e.should_commit()) {
4325 e.set_reason("No remaining non-daemon Java threads");
4326 e.commit();
4327 }
4328
4329 // Hang forever on exit if we are reporting an error.
4330 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4331 os::infinite_sleep();
4332 }
4333 os::wait_for_keypress_at_exit();
4334
4335 // run Java level shutdown hooks
4336 thread->invoke_shutdown_hooks();
4337
4338 before_exit(thread);
4339
4340 thread->exit(true);
4341
4342 // Stop VM thread.
4343 {
4344 // 4945125 The vm thread comes to a safepoint during exit.
4345 // GC vm_operations can get caught at the safepoint, and the
4346 // heap is unparseable if they are caught. Grab the Heap_lock
4347 // to prevent this. The GC vm_operations will not be able to
4348 // queue until after the vm thread is dead. After this point,
4349 // we'll never emerge out of the safepoint before the VM exits.
4350
4351 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4352
4353 VMThread::wait_for_vm_thread_exit();
4354 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4355 VMThread::destroy();
4356 }
4357
4358 // Now, all Java threads are gone except daemon threads. Daemon threads
4359 // running Java code or in VM are stopped by the Safepoint. However,
4360 // daemon threads executing native code are still running. But they
4361 // will be stopped at native=>Java/VM barriers. Note that we can't
4362 // simply kill or suspend them, as it is inherently deadlock-prone.
4363
4364 VM_Exit::set_vm_exited();
4365
4366 // Clean up ideal graph printers after the VMThread has started
4367 // the final safepoint which will block all the Compiler threads.
4368 // Note that this Thread has already logically exited so the
4369 // clean_up() function's use of a JavaThreadIteratorWithHandle
4370 // would be a problem except set_vm_exited() has remembered the
4371 // shutdown thread which is granted a policy exception.
4372 #if defined(COMPILER2) && !defined(PRODUCT)
4373 IdealGraphPrinter::clean_up();
4374 #endif
4375
4376 notify_vm_shutdown();
4377
4378 // exit_globals() will delete tty
4379 exit_globals();
4380
4381 // We are after VM_Exit::set_vm_exited() so we can't call
4382 // thread->smr_delete() or we will block on the Threads_lock.
4383 // Deleting the shutdown thread here is safe because another
4384 // JavaThread cannot have an active ThreadsListHandle for
4385 // this JavaThread.
4386 delete thread;
4387
4388 #if INCLUDE_JVMCI
4389 if (JVMCICounterSize > 0) {
4390 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4391 }
4392 #endif
4393
4394 LogConfiguration::finalize();
4395
4396 return true;
4397 }
4398
4399
4400 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4401 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4402 return is_supported_jni_version(version);
4403 }
4404
4405
4406 jboolean Threads::is_supported_jni_version(jint version) {
4407 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4408 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4409 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4410 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4411 if (version == JNI_VERSION_9) return JNI_TRUE;
4412 if (version == JNI_VERSION_10) return JNI_TRUE;
4413 return JNI_FALSE;
4414 }
4415
4416
4417 void Threads::add(JavaThread* p, bool force_daemon) {
4418 // The threads lock must be owned at this point
4419 assert(Threads_lock->owned_by_self(), "must have threads lock");
4420
4421 BarrierSet::barrier_set()->on_thread_attach(p);
4422
4423 // Once a JavaThread is added to the Threads list, smr_delete() has
4424 // to be used to delete it. Otherwise we can just delete it directly.
4425 p->set_on_thread_list();
4426
4427 _number_of_threads++;
4428 oop threadObj = p->threadObj();
4429 bool daemon = true;
4430 // Bootstrapping problem: threadObj can be null for initial
4431 // JavaThread (or for threads attached via JNI)
4432 if ((!force_daemon) && !is_daemon((threadObj))) {
4433 _number_of_non_daemon_threads++;
4434 daemon = false;
4435 }
4436
4437 ThreadService::add_thread(p, daemon);
4438
4439 // Maintain fast thread list
4440 ThreadsSMRSupport::add_thread(p);
4441
4442 // Possible GC point.
4443 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4444 }
4445
4446 void Threads::remove(JavaThread* p, bool is_daemon) {
4447
4448 // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4449 ObjectSynchronizer::omFlush(p);
4450
4451 // Extra scope needed for Thread_lock, so we can check
4452 // that we do not remove thread without safepoint code notice
4453 { MonitorLocker ml(Threads_lock);
4454
4455 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4456
4457 // Maintain fast thread list
4458 ThreadsSMRSupport::remove_thread(p);
4459
4460 _number_of_threads--;
4461 if (!is_daemon) {
4462 _number_of_non_daemon_threads--;
4463
4464 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4465 // on destroy_vm will wake up.
4466 if (number_of_non_daemon_threads() == 1) {
4467 ml.notify_all();
4468 }
4469 }
4470 ThreadService::remove_thread(p, is_daemon);
4471
4472 // Make sure that safepoint code disregard this thread. This is needed since
4473 // the thread might mess around with locks after this point. This can cause it
4474 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4475 // of this thread since it is removed from the queue.
4476 p->set_terminated_value();
4477 } // unlock Threads_lock
4478
4479 // Since Events::log uses a lock, we grab it outside the Threads_lock
4480 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4481 }
4482
4483 // Operations on the Threads list for GC. These are not explicitly locked,
4484 // but the garbage collector must provide a safe context for them to run.
4485 // In particular, these things should never be called when the Threads_lock
4486 // is held by some other thread. (Note: the Safepoint abstraction also
4487 // uses the Threads_lock to guarantee this property. It also makes sure that
4488 // all threads gets blocked when exiting or starting).
4489
4490 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4491 ALL_JAVA_THREADS(p) {
4492 p->oops_do(f, cf);
4493 }
4494 VMThread::vm_thread()->oops_do(f, cf);
4495 }
4496
4497 void Threads::change_thread_claim_token() {
4498 if (++_thread_claim_token == 0) {
4499 // On overflow of the token counter, there is a risk of future
4500 // collisions between a new global token value and a stale token
4501 // for a thread, because not all iterations visit all threads.
4502 // (Though it's pretty much a theoretical concern for non-trivial
4503 // token counter sizes.) To deal with the possibility, reset all
4504 // the thread tokens to zero on global token overflow.
4505 struct ResetClaims : public ThreadClosure {
4506 virtual void do_thread(Thread* t) {
4507 t->claim_threads_do(false, 0);
4508 }
4509 } reset_claims;
4510 Threads::threads_do(&reset_claims);
4511 // On overflow, update the global token to non-zero, to
4512 // avoid the special "never claimed" initial thread value.
4513 _thread_claim_token = 1;
4514 }
4515 }
4516
4517 #ifdef ASSERT
4518 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4519 const uintx token = t->threads_do_token();
4520 assert(token == expected,
4521 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4522 UINTX_FORMAT, kind, p2i(t), token, expected);
4523 }
4524
4525 void Threads::assert_all_threads_claimed() {
4526 ALL_JAVA_THREADS(p) {
4527 assert_thread_claimed("Thread", p, _thread_claim_token);
4528 }
4529 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4530 }
4531 #endif // ASSERT
4532
4533 class ParallelOopsDoThreadClosure : public ThreadClosure {
4534 private:
4535 OopClosure* _f;
4536 CodeBlobClosure* _cf;
4537 public:
4538 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4539 void do_thread(Thread* t) {
4540 t->oops_do(_f, _cf);
4541 }
4542 };
4543
4544 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4545 ParallelOopsDoThreadClosure tc(f, cf);
4546 possibly_parallel_threads_do(is_par, &tc);
4547 }
4548
4549 void Threads::nmethods_do(CodeBlobClosure* cf) {
4550 ALL_JAVA_THREADS(p) {
4551 // This is used by the code cache sweeper to mark nmethods that are active
4552 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4553 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4554 if(!p->is_Code_cache_sweeper_thread()) {
4555 p->nmethods_do(cf);
4556 }
4557 }
4558 }
4559
4560 void Threads::metadata_do(MetadataClosure* f) {
4561 ALL_JAVA_THREADS(p) {
4562 p->metadata_do(f);
4563 }
4564 }
4565
4566 class ThreadHandlesClosure : public ThreadClosure {
4567 void (*_f)(Metadata*);
4568 public:
4569 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4570 virtual void do_thread(Thread* thread) {
4571 thread->metadata_handles_do(_f);
4572 }
4573 };
4574
4575 void Threads::metadata_handles_do(void f(Metadata*)) {
4576 // Only walk the Handles in Thread.
4577 ThreadHandlesClosure handles_closure(f);
4578 threads_do(&handles_closure);
4579 }
4580
4581 void Threads::deoptimized_wrt_marked_nmethods() {
4582 ALL_JAVA_THREADS(p) {
4583 p->deoptimized_wrt_marked_nmethods();
4584 }
4585 }
4586
4587
4588 // Get count Java threads that are waiting to enter the specified monitor.
4589 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4590 int count,
4591 address monitor) {
4592 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4593
4594 int i = 0;
4595 DO_JAVA_THREADS(t_list, p) {
4596 if (!p->can_call_java()) continue;
4597
4598 address pending = (address)p->current_pending_monitor();
4599 if (pending == monitor) { // found a match
4600 if (i < count) result->append(p); // save the first count matches
4601 i++;
4602 }
4603 }
4604
4605 return result;
4606 }
4607
4608
4609 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4610 address owner) {
4611 // NULL owner means not locked so we can skip the search
4612 if (owner == NULL) return NULL;
4613
4614 DO_JAVA_THREADS(t_list, p) {
4615 // first, see if owner is the address of a Java thread
4616 if (owner == (address)p) return p;
4617 }
4618
4619 // Cannot assert on lack of success here since this function may be
4620 // used by code that is trying to report useful problem information
4621 // like deadlock detection.
4622 if (UseHeavyMonitors) return NULL;
4623
4624 // If we didn't find a matching Java thread and we didn't force use of
4625 // heavyweight monitors, then the owner is the stack address of the
4626 // Lock Word in the owning Java thread's stack.
4627 //
4628 JavaThread* the_owner = NULL;
4629 DO_JAVA_THREADS(t_list, q) {
4630 if (q->is_lock_owned(owner)) {
4631 the_owner = q;
4632 break;
4633 }
4634 }
4635
4636 // cannot assert on lack of success here; see above comment
4637 return the_owner;
4638 }
4639
4640 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4641 void Threads::print_on(outputStream* st, bool print_stacks,
4642 bool internal_format, bool print_concurrent_locks,
4643 bool print_extended_info) {
4644 char buf[32];
4645 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4646
4647 st->print_cr("Full thread dump %s (%s %s):",
4648 VM_Version::vm_name(),
4649 VM_Version::vm_release(),
4650 VM_Version::vm_info_string());
4651 st->cr();
4652
4653 #if INCLUDE_SERVICES
4654 // Dump concurrent locks
4655 ConcurrentLocksDump concurrent_locks;
4656 if (print_concurrent_locks) {
4657 concurrent_locks.dump_at_safepoint();
4658 }
4659 #endif // INCLUDE_SERVICES
4660
4661 ThreadsSMRSupport::print_info_on(st);
4662 st->cr();
4663
4664 ALL_JAVA_THREADS(p) {
4665 ResourceMark rm;
4666 p->print_on(st, print_extended_info);
4667 if (print_stacks) {
4668 if (internal_format) {
4669 p->trace_stack();
4670 } else {
4671 p->print_stack_on(st);
4672 }
4673 }
4674 st->cr();
4675 #if INCLUDE_SERVICES
4676 if (print_concurrent_locks) {
4677 concurrent_locks.print_locks_on(p, st);
4678 }
4679 #endif // INCLUDE_SERVICES
4680 }
4681
4682 VMThread::vm_thread()->print_on(st);
4683 st->cr();
4684 Universe::heap()->print_gc_threads_on(st);
4685 WatcherThread* wt = WatcherThread::watcher_thread();
4686 if (wt != NULL) {
4687 wt->print_on(st);
4688 st->cr();
4689 }
4690
4691 st->flush();
4692 }
4693
4694 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4695 int buflen, bool* found_current) {
4696 if (this_thread != NULL) {
4697 bool is_current = (current == this_thread);
4698 *found_current = *found_current || is_current;
4699 st->print("%s", is_current ? "=>" : " ");
4700
4701 st->print(PTR_FORMAT, p2i(this_thread));
4702 st->print(" ");
4703 this_thread->print_on_error(st, buf, buflen);
4704 st->cr();
4705 }
4706 }
4707
4708 class PrintOnErrorClosure : public ThreadClosure {
4709 outputStream* _st;
4710 Thread* _current;
4711 char* _buf;
4712 int _buflen;
4713 bool* _found_current;
4714 public:
4715 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4716 int buflen, bool* found_current) :
4717 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4718
4719 virtual void do_thread(Thread* thread) {
4720 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4721 }
4722 };
4723
4724 // Threads::print_on_error() is called by fatal error handler. It's possible
4725 // that VM is not at safepoint and/or current thread is inside signal handler.
4726 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4727 // memory (even in resource area), it might deadlock the error handler.
4728 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4729 int buflen) {
4730 ThreadsSMRSupport::print_info_on(st);
4731 st->cr();
4732
4733 bool found_current = false;
4734 st->print_cr("Java Threads: ( => current thread )");
4735 ALL_JAVA_THREADS(thread) {
4736 print_on_error(thread, st, current, buf, buflen, &found_current);
4737 }
4738 st->cr();
4739
4740 st->print_cr("Other Threads:");
4741 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4742 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4743
4744 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4745 Universe::heap()->gc_threads_do(&print_closure);
4746
4747 if (!found_current) {
4748 st->cr();
4749 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4750 current->print_on_error(st, buf, buflen);
4751 st->cr();
4752 }
4753 st->cr();
4754
4755 st->print_cr("Threads with active compile tasks:");
4756 print_threads_compiling(st, buf, buflen);
4757 }
4758
4759 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4760 ALL_JAVA_THREADS(thread) {
4761 if (thread->is_Compiler_thread()) {
4762 CompilerThread* ct = (CompilerThread*) thread;
4763
4764 // Keep task in local variable for NULL check.
4765 // ct->_task might be set to NULL by concurring compiler thread
4766 // because it completed the compilation. The task is never freed,
4767 // though, just returned to a free list.
4768 CompileTask* task = ct->task();
4769 if (task != NULL) {
4770 thread->print_name_on_error(st, buf, buflen);
4771 st->print(" ");
4772 task->print(st, NULL, short_form, true);
4773 }
4774 }
4775 }
4776 }
4777
4778
4779 // Internal SpinLock and Mutex
4780 // Based on ParkEvent
4781
4782 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4783 //
4784 // We employ SpinLocks _only for low-contention, fixed-length
4785 // short-duration critical sections where we're concerned
4786 // about native mutex_t or HotSpot Mutex:: latency.
4787 // The mux construct provides a spin-then-block mutual exclusion
4788 // mechanism.
4789 //
4790 // Testing has shown that contention on the ListLock guarding gFreeList
4791 // is common. If we implement ListLock as a simple SpinLock it's common
4792 // for the JVM to devolve to yielding with little progress. This is true
4793 // despite the fact that the critical sections protected by ListLock are
4794 // extremely short.
4795 //
4796 // TODO-FIXME: ListLock should be of type SpinLock.
4797 // We should make this a 1st-class type, integrated into the lock
4798 // hierarchy as leaf-locks. Critically, the SpinLock structure
4799 // should have sufficient padding to avoid false-sharing and excessive
4800 // cache-coherency traffic.
4801
4802
4803 typedef volatile int SpinLockT;
4804
4805 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4806 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4807 return; // normal fast-path return
4808 }
4809
4810 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4811 int ctr = 0;
4812 int Yields = 0;
4813 for (;;) {
4814 while (*adr != 0) {
4815 ++ctr;
4816 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4817 if (Yields > 5) {
4818 os::naked_short_sleep(1);
4819 } else {
4820 os::naked_yield();
4821 ++Yields;
4822 }
4823 } else {
4824 SpinPause();
4825 }
4826 }
4827 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4828 }
4829 }
4830
4831 void Thread::SpinRelease(volatile int * adr) {
4832 assert(*adr != 0, "invariant");
4833 OrderAccess::fence(); // guarantee at least release consistency.
4834 // Roach-motel semantics.
4835 // It's safe if subsequent LDs and STs float "up" into the critical section,
4836 // but prior LDs and STs within the critical section can't be allowed
4837 // to reorder or float past the ST that releases the lock.
4838 // Loads and stores in the critical section - which appear in program
4839 // order before the store that releases the lock - must also appear
4840 // before the store that releases the lock in memory visibility order.
4841 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4842 // the ST of 0 into the lock-word which releases the lock, so fence
4843 // more than covers this on all platforms.
4844 *adr = 0;
4845 }
4846
4847 // muxAcquire and muxRelease:
4848 //
4849 // * muxAcquire and muxRelease support a single-word lock-word construct.
4850 // The LSB of the word is set IFF the lock is held.
4851 // The remainder of the word points to the head of a singly-linked list
4852 // of threads blocked on the lock.
4853 //
4854 // * The current implementation of muxAcquire-muxRelease uses its own
4855 // dedicated Thread._MuxEvent instance. If we're interested in
4856 // minimizing the peak number of extant ParkEvent instances then
4857 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4858 // as certain invariants were satisfied. Specifically, care would need
4859 // to be taken with regards to consuming unpark() "permits".
4860 // A safe rule of thumb is that a thread would never call muxAcquire()
4861 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4862 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4863 // consume an unpark() permit intended for monitorenter, for instance.
4864 // One way around this would be to widen the restricted-range semaphore
4865 // implemented in park(). Another alternative would be to provide
4866 // multiple instances of the PlatformEvent() for each thread. One
4867 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4868 //
4869 // * Usage:
4870 // -- Only as leaf locks
4871 // -- for short-term locking only as muxAcquire does not perform
4872 // thread state transitions.
4873 //
4874 // Alternatives:
4875 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4876 // but with parking or spin-then-park instead of pure spinning.
4877 // * Use Taura-Oyama-Yonenzawa locks.
4878 // * It's possible to construct a 1-0 lock if we encode the lockword as
4879 // (List,LockByte). Acquire will CAS the full lockword while Release
4880 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4881 // acquiring threads use timers (ParkTimed) to detect and recover from
4882 // the stranding window. Thread/Node structures must be aligned on 256-byte
4883 // boundaries by using placement-new.
4884 // * Augment MCS with advisory back-link fields maintained with CAS().
4885 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4886 // The validity of the backlinks must be ratified before we trust the value.
4887 // If the backlinks are invalid the exiting thread must back-track through the
4888 // the forward links, which are always trustworthy.
4889 // * Add a successor indication. The LockWord is currently encoded as
4890 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4891 // to provide the usual futile-wakeup optimization.
4892 // See RTStt for details.
4893 //
4894
4895
4896 const intptr_t LOCKBIT = 1;
4897
4898 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4899 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4900 if (w == 0) return;
4901 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4902 return;
4903 }
4904
4905 ParkEvent * const Self = Thread::current()->_MuxEvent;
4906 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4907 for (;;) {
4908 int its = (os::is_MP() ? 100 : 0) + 1;
4909
4910 // Optional spin phase: spin-then-park strategy
4911 while (--its >= 0) {
4912 w = *Lock;
4913 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4914 return;
4915 }
4916 }
4917
4918 Self->reset();
4919 Self->OnList = intptr_t(Lock);
4920 // The following fence() isn't _strictly necessary as the subsequent
4921 // CAS() both serializes execution and ratifies the fetched *Lock value.
4922 OrderAccess::fence();
4923 for (;;) {
4924 w = *Lock;
4925 if ((w & LOCKBIT) == 0) {
4926 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4927 Self->OnList = 0; // hygiene - allows stronger asserts
4928 return;
4929 }
4930 continue; // Interference -- *Lock changed -- Just retry
4931 }
4932 assert(w & LOCKBIT, "invariant");
4933 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4934 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4935 }
4936
4937 while (Self->OnList != 0) {
4938 Self->park();
4939 }
4940 }
4941 }
4942
4943 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4944 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4945 if (w == 0) return;
4946 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4947 return;
4948 }
4949
4950 ParkEvent * ReleaseAfter = NULL;
4951 if (ev == NULL) {
4952 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4953 }
4954 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4955 for (;;) {
4956 guarantee(ev->OnList == 0, "invariant");
4957 int its = (os::is_MP() ? 100 : 0) + 1;
4958
4959 // Optional spin phase: spin-then-park strategy
4960 while (--its >= 0) {
4961 w = *Lock;
4962 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4963 if (ReleaseAfter != NULL) {
4964 ParkEvent::Release(ReleaseAfter);
4965 }
4966 return;
4967 }
4968 }
4969
4970 ev->reset();
4971 ev->OnList = intptr_t(Lock);
4972 // The following fence() isn't _strictly necessary as the subsequent
4973 // CAS() both serializes execution and ratifies the fetched *Lock value.
4974 OrderAccess::fence();
4975 for (;;) {
4976 w = *Lock;
4977 if ((w & LOCKBIT) == 0) {
4978 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4979 ev->OnList = 0;
4980 // We call ::Release while holding the outer lock, thus
4981 // artificially lengthening the critical section.
4982 // Consider deferring the ::Release() until the subsequent unlock(),
4983 // after we've dropped the outer lock.
4984 if (ReleaseAfter != NULL) {
4985 ParkEvent::Release(ReleaseAfter);
4986 }
4987 return;
4988 }
4989 continue; // Interference -- *Lock changed -- Just retry
4990 }
4991 assert(w & LOCKBIT, "invariant");
4992 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4993 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4994 }
4995
4996 while (ev->OnList != 0) {
4997 ev->park();
4998 }
4999 }
5000 }
5001
5002 // Release() must extract a successor from the list and then wake that thread.
5003 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5004 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5005 // Release() would :
5006 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5007 // (B) Extract a successor from the private list "in-hand"
5008 // (C) attempt to CAS() the residual back into *Lock over null.
5009 // If there were any newly arrived threads and the CAS() would fail.
5010 // In that case Release() would detach the RATs, re-merge the list in-hand
5011 // with the RATs and repeat as needed. Alternately, Release() might
5012 // detach and extract a successor, but then pass the residual list to the wakee.
5013 // The wakee would be responsible for reattaching and remerging before it
5014 // competed for the lock.
5015 //
5016 // Both "pop" and DMR are immune from ABA corruption -- there can be
5017 // multiple concurrent pushers, but only one popper or detacher.
5018 // This implementation pops from the head of the list. This is unfair,
5019 // but tends to provide excellent throughput as hot threads remain hot.
5020 // (We wake recently run threads first).
5021 //
5022 // All paths through muxRelease() will execute a CAS.
5023 // Release consistency -- We depend on the CAS in muxRelease() to provide full
5024 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5025 // executed within the critical section are complete and globally visible before the
5026 // store (CAS) to the lock-word that releases the lock becomes globally visible.
5027 void Thread::muxRelease(volatile intptr_t * Lock) {
5028 for (;;) {
5029 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5030 assert(w & LOCKBIT, "invariant");
5031 if (w == LOCKBIT) return;
5032 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5033 assert(List != NULL, "invariant");
5034 assert(List->OnList == intptr_t(Lock), "invariant");
5035 ParkEvent * const nxt = List->ListNext;
5036 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5037
5038 // The following CAS() releases the lock and pops the head element.
5039 // The CAS() also ratifies the previously fetched lock-word value.
5040 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5041 continue;
5042 }
5043 List->OnList = 0;
5044 OrderAccess::fence();
5045 List->unpark();
5046 return;
5047 }
5048 }
5049
5050
5051 void Threads::verify() {
5052 ALL_JAVA_THREADS(p) {
5053 p->verify();
5054 }
5055 VMThread* thread = VMThread::vm_thread();
5056 if (thread != NULL) thread->verify();
5057 }