1 /*
2 * Copyright (c) 1997, 2018, 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 "jvmtifiles/jvmtiEnv.hpp"
44 #include "logging/log.hpp"
45 #include "logging/logConfiguration.hpp"
46 #include "logging/logStream.hpp"
47 #include "memory/allocation.inline.hpp"
48 #include "memory/metaspaceShared.hpp"
49 #include "memory/oopFactory.hpp"
50 #include "memory/resourceArea.hpp"
51 #include "memory/universe.hpp"
52 #include "oops/access.inline.hpp"
53 #include "oops/instanceKlass.hpp"
54 #include "oops/objArrayOop.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/symbol.hpp"
57 #include "oops/typeArrayOop.inline.hpp"
58 #include "oops/verifyOopClosure.hpp"
59 #include "prims/jvm_misc.hpp"
60 #include "prims/jvmtiExport.hpp"
61 #include "prims/jvmtiThreadState.hpp"
62 #include "prims/privilegedStack.hpp"
63 #include "runtime/arguments.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/biasedLocking.hpp"
66 #include "runtime/commandLineFlagConstraintList.hpp"
67 #include "runtime/commandLineFlagWriteableList.hpp"
68 #include "runtime/commandLineFlagRangeList.hpp"
69 #include "runtime/deoptimization.hpp"
70 #include "runtime/frame.inline.hpp"
71 #include "runtime/globals.hpp"
72 #include "runtime/handshake.hpp"
73 #include "runtime/init.hpp"
74 #include "runtime/interfaceSupport.inline.hpp"
75 #include "runtime/java.hpp"
76 #include "runtime/javaCalls.hpp"
77 #include "runtime/jniHandles.inline.hpp"
78 #include "runtime/jniPeriodicChecker.hpp"
79 #include "runtime/memprofiler.hpp"
80 #include "runtime/mutexLocker.hpp"
81 #include "runtime/objectMonitor.hpp"
82 #include "runtime/orderAccess.inline.hpp"
83 #include "runtime/osThread.hpp"
84 #include "runtime/prefetch.inline.hpp"
85 #include "runtime/safepoint.hpp"
86 #include "runtime/safepointMechanism.inline.hpp"
87 #include "runtime/sharedRuntime.hpp"
88 #include "runtime/statSampler.hpp"
89 #include "runtime/stubRoutines.hpp"
90 #include "runtime/sweeper.hpp"
91 #include "runtime/task.hpp"
92 #include "runtime/thread.inline.hpp"
93 #include "runtime/threadCritical.hpp"
94 #include "runtime/threadSMR.inline.hpp"
95 #include "runtime/timer.hpp"
96 #include "runtime/timerTrace.hpp"
97 #include "runtime/vframe.inline.hpp"
98 #include "runtime/vframeArray.hpp"
99 #include "runtime/vframe_hp.hpp"
100 #include "runtime/vmThread.hpp"
101 #include "runtime/vm_operations.hpp"
102 #include "runtime/vm_version.hpp"
103 #include "services/attachListener.hpp"
104 #include "services/management.hpp"
105 #include "services/memTracker.hpp"
106 #include "services/threadService.hpp"
107 #include "trace/traceMacros.hpp"
108 #include "trace/tracing.hpp"
109 #include "utilities/align.hpp"
110 #include "utilities/defaultStream.hpp"
111 #include "utilities/dtrace.hpp"
112 #include "utilities/events.hpp"
113 #include "utilities/macros.hpp"
114 #include "utilities/preserveException.hpp"
115 #include "utilities/vmError.hpp"
116 #if INCLUDE_ALL_GCS
117 #include "gc/cms/concurrentMarkSweepThread.hpp"
118 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
119 #include "gc/parallel/pcTasks.hpp"
120 #endif // INCLUDE_ALL_GCS
121 #if INCLUDE_JVMCI
122 #include "jvmci/jvmciCompiler.hpp"
123 #include "jvmci/jvmciRuntime.hpp"
124 #include "logging/logHandle.hpp"
125 #endif
126 #ifdef COMPILER1
127 #include "c1/c1_Compiler.hpp"
128 #endif
129 #ifdef COMPILER2
130 #include "opto/c2compiler.hpp"
131 #include "opto/idealGraphPrinter.hpp"
132 #endif
133 #if INCLUDE_RTM_OPT
134 #include "runtime/rtmLocking.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 // Class hierarchy
171 // - Thread
172 // - VMThread
173 // - WatcherThread
174 // - ConcurrentMarkSweepThread
175 // - JavaThread
176 // - CompilerThread
177
178 // ======= Thread ========
179 // Support for forcing alignment of thread objects for biased locking
180 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
181 if (UseBiasedLocking) {
182 const int alignment = markOopDesc::biased_lock_alignment;
183 size_t aligned_size = size + (alignment - sizeof(intptr_t));
184 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
185 : AllocateHeap(aligned_size, flags, CURRENT_PC,
186 AllocFailStrategy::RETURN_NULL);
187 void* aligned_addr = align_up(real_malloc_addr, alignment);
188 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
189 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
190 "JavaThread alignment code overflowed allocated storage");
191 if (aligned_addr != real_malloc_addr) {
192 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
193 p2i(real_malloc_addr),
194 p2i(aligned_addr));
195 }
196 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
197 return aligned_addr;
198 } else {
199 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
200 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
201 }
202 }
203
204 void Thread::operator delete(void* p) {
205 if (UseBiasedLocking) {
206 FreeHeap(((Thread*) p)->_real_malloc_address);
207 } else {
208 FreeHeap(p);
209 }
210 }
211
212 void JavaThread::smr_delete() {
213 if (_on_thread_list) {
214 ThreadsSMRSupport::smr_delete(this);
215 } else {
216 delete this;
217 }
218 }
219
220 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
221 // JavaThread
222
223
224 Thread::Thread() {
225 // stack and get_thread
226 set_stack_base(NULL);
227 set_stack_size(0);
228 set_self_raw_id(0);
229 set_lgrp_id(-1);
230 DEBUG_ONLY(clear_suspendible_thread();)
231
232 // allocated data structures
233 set_osthread(NULL);
234 set_resource_area(new (mtThread)ResourceArea());
235 DEBUG_ONLY(_current_resource_mark = NULL;)
236 set_handle_area(new (mtThread) HandleArea(NULL));
237 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
238 set_active_handles(NULL);
239 set_free_handle_block(NULL);
240 set_last_handle_mark(NULL);
241
242 // This initial value ==> never claimed.
243 _oops_do_parity = 0;
244 _threads_hazard_ptr = NULL;
245 _nested_threads_hazard_ptr = NULL;
246 _nested_threads_hazard_ptr_cnt = 0;
247
248 // the handle mark links itself to last_handle_mark
249 new HandleMark(this);
250
251 // plain initialization
252 debug_only(_owned_locks = NULL;)
253 debug_only(_allow_allocation_count = 0;)
254 NOT_PRODUCT(_allow_safepoint_count = 0;)
255 NOT_PRODUCT(_skip_gcalot = false;)
256 _jvmti_env_iteration_count = 0;
257 set_allocated_bytes(0);
258 _vm_operation_started_count = 0;
259 _vm_operation_completed_count = 0;
260 _current_pending_monitor = NULL;
261 _current_pending_monitor_is_from_java = true;
262 _current_waiting_monitor = NULL;
263 _num_nested_signal = 0;
264 omFreeList = NULL;
265 omFreeCount = 0;
266 omFreeProvision = 32;
267 omInUseList = NULL;
268 omInUseCount = 0;
269
270 #ifdef ASSERT
271 _visited_for_critical_count = false;
272 #endif
273
274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
275 Monitor::_safepoint_check_sometimes);
276 _suspend_flags = 0;
277
278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
279 _hashStateX = os::random();
280 _hashStateY = 842502087;
281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
282 _hashStateW = 273326509;
283
284 _OnTrap = 0;
285 _schedctl = NULL;
286 _Stalled = 0;
287 _TypeTag = 0x2BAD;
288
289 // Many of the following fields are effectively final - immutable
290 // Note that nascent threads can't use the Native Monitor-Mutex
291 // construct until the _MutexEvent is initialized ...
292 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
293 // we might instead use a stack of ParkEvents that we could provision on-demand.
294 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
295 // and ::Release()
296 _ParkEvent = ParkEvent::Allocate(this);
297 _SleepEvent = ParkEvent::Allocate(this);
298 _MutexEvent = ParkEvent::Allocate(this);
299 _MuxEvent = ParkEvent::Allocate(this);
300
301 #ifdef CHECK_UNHANDLED_OOPS
302 if (CheckUnhandledOops) {
303 _unhandled_oops = new UnhandledOops(this);
304 }
305 #endif // CHECK_UNHANDLED_OOPS
306 #ifdef ASSERT
307 if (UseBiasedLocking) {
308 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
309 assert(this == _real_malloc_address ||
310 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
311 "bug in forced alignment of thread objects");
312 }
313 #endif // ASSERT
314
315 // Notify the barrier set that a thread is being created. Note that the
316 // main thread is created before a barrier set is available. The call to
317 // BarrierSet::on_thread_create() for the main thread is therefore deferred
318 // until it calls BarrierSet::set_barrier_set().
319 BarrierSet* const barrier_set = BarrierSet::barrier_set();
320 if (barrier_set != NULL) {
321 barrier_set->on_thread_create(this);
322 }
323 }
324
325 void Thread::initialize_thread_current() {
326 #ifndef USE_LIBRARY_BASED_TLS_ONLY
327 assert(_thr_current == NULL, "Thread::current already initialized");
328 _thr_current = this;
329 #endif
330 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
331 ThreadLocalStorage::set_thread(this);
332 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
333 }
334
335 void Thread::clear_thread_current() {
336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
337 #ifndef USE_LIBRARY_BASED_TLS_ONLY
338 _thr_current = NULL;
339 #endif
340 ThreadLocalStorage::set_thread(NULL);
341 }
342
343 void Thread::record_stack_base_and_size() {
344 set_stack_base(os::current_stack_base());
345 set_stack_size(os::current_stack_size());
346 // CR 7190089: on Solaris, primordial thread's stack is adjusted
347 // in initialize_thread(). Without the adjustment, stack size is
348 // incorrect if stack is set to unlimited (ulimit -s unlimited).
349 // So far, only Solaris has real implementation of initialize_thread().
350 //
351 // set up any platform-specific state.
352 os::initialize_thread(this);
353
354 // Set stack limits after thread is initialized.
355 if (is_Java_thread()) {
356 ((JavaThread*) this)->set_stack_overflow_limit();
357 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
358 }
359 #if INCLUDE_NMT
360 // record thread's native stack, stack grows downward
361 MemTracker::record_thread_stack(stack_end(), stack_size());
362 #endif // INCLUDE_NMT
363 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
364 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
365 os::current_thread_id(), p2i(stack_base() - stack_size()),
366 p2i(stack_base()), stack_size()/1024);
367 }
368
369
370 Thread::~Thread() {
371 EVENT_THREAD_DESTRUCT(this);
372
373 // Notify the barrier set that a thread is being destroyed. Note that a barrier
374 // set might not be available if we encountered errors during bootstrapping.
375 BarrierSet* const barrier_set = BarrierSet::barrier_set();
376 if (barrier_set != NULL) {
377 barrier_set->on_thread_destroy(this);
378 }
379
380 // stack_base can be NULL if the thread is never started or exited before
381 // record_stack_base_and_size called. Although, we would like to ensure
382 // that all started threads do call record_stack_base_and_size(), there is
383 // not proper way to enforce that.
384 #if INCLUDE_NMT
385 if (_stack_base != NULL) {
386 MemTracker::release_thread_stack(stack_end(), stack_size());
387 #ifdef ASSERT
388 set_stack_base(NULL);
389 #endif
390 }
391 #endif // INCLUDE_NMT
392
393 // deallocate data structures
394 delete resource_area();
395 // since the handle marks are using the handle area, we have to deallocated the root
396 // handle mark before deallocating the thread's handle area,
397 assert(last_handle_mark() != NULL, "check we have an element");
398 delete last_handle_mark();
399 assert(last_handle_mark() == NULL, "check we have reached the end");
400
401 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
402 // We NULL out the fields for good hygiene.
403 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
404 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
405 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
406 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
407
408 delete handle_area();
409 delete metadata_handles();
410
411 // SR_handler uses this as a termination indicator -
412 // needs to happen before os::free_thread()
413 delete _SR_lock;
414 _SR_lock = NULL;
415
416 // osthread() can be NULL, if creation of thread failed.
417 if (osthread() != NULL) os::free_thread(osthread());
418
419 // clear Thread::current if thread is deleting itself.
420 // Needed to ensure JNI correctly detects non-attached threads.
421 if (this == Thread::current()) {
422 clear_thread_current();
423 }
424
425 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
426 }
427
428 // NOTE: dummy function for assertion purpose.
429 void Thread::run() {
430 ShouldNotReachHere();
431 }
432
433 #ifdef ASSERT
434 // A JavaThread is considered "dangling" if it is not the current
435 // thread, has been added the Threads list, the system is not at a
436 // safepoint and the Thread is not "protected".
437 //
438 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
439 assert(!thread->is_Java_thread() || Thread::current() == thread ||
440 !((JavaThread *) thread)->on_thread_list() ||
441 SafepointSynchronize::is_at_safepoint() ||
442 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
443 "possibility of dangling Thread pointer");
444 }
445 #endif
446
447 ThreadPriority Thread::get_priority(const Thread* const thread) {
448 ThreadPriority priority;
449 // Can return an error!
450 (void)os::get_priority(thread, priority);
451 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
452 return priority;
453 }
454
455 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
456 debug_only(check_for_dangling_thread_pointer(thread);)
457 // Can return an error!
458 (void)os::set_priority(thread, priority);
459 }
460
461
462 void Thread::start(Thread* thread) {
463 // Start is different from resume in that its safety is guaranteed by context or
464 // being called from a Java method synchronized on the Thread object.
465 if (!DisableStartThread) {
466 if (thread->is_Java_thread()) {
467 // Initialize the thread state to RUNNABLE before starting this thread.
468 // Can not set it after the thread started because we do not know the
469 // exact thread state at that time. It could be in MONITOR_WAIT or
470 // in SLEEPING or some other state.
471 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
472 java_lang_Thread::RUNNABLE);
473 }
474 os::start_thread(thread);
475 }
476 }
477
478 // Enqueue a VM_Operation to do the job for us - sometime later
479 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
480 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
481 VMThread::execute(vm_stop);
482 }
483
484
485 // Check if an external suspend request has completed (or has been
486 // cancelled). Returns true if the thread is externally suspended and
487 // false otherwise.
488 //
489 // The bits parameter returns information about the code path through
490 // the routine. Useful for debugging:
491 //
492 // set in is_ext_suspend_completed():
493 // 0x00000001 - routine was entered
494 // 0x00000010 - routine return false at end
495 // 0x00000100 - thread exited (return false)
496 // 0x00000200 - suspend request cancelled (return false)
497 // 0x00000400 - thread suspended (return true)
498 // 0x00001000 - thread is in a suspend equivalent state (return true)
499 // 0x00002000 - thread is native and walkable (return true)
500 // 0x00004000 - thread is native_trans and walkable (needed retry)
501 //
502 // set in wait_for_ext_suspend_completion():
503 // 0x00010000 - routine was entered
504 // 0x00020000 - suspend request cancelled before loop (return false)
505 // 0x00040000 - thread suspended before loop (return true)
506 // 0x00080000 - suspend request cancelled in loop (return false)
507 // 0x00100000 - thread suspended in loop (return true)
508 // 0x00200000 - suspend not completed during retry loop (return false)
509
510 // Helper class for tracing suspend wait debug bits.
511 //
512 // 0x00000100 indicates that the target thread exited before it could
513 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
514 // 0x00080000 each indicate a cancelled suspend request so they don't
515 // count as wait failures either.
516 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
517
518 class TraceSuspendDebugBits : public StackObj {
519 private:
520 JavaThread * jt;
521 bool is_wait;
522 bool called_by_wait; // meaningful when !is_wait
523 uint32_t * bits;
524
525 public:
526 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
527 uint32_t *_bits) {
528 jt = _jt;
529 is_wait = _is_wait;
530 called_by_wait = _called_by_wait;
531 bits = _bits;
532 }
533
534 ~TraceSuspendDebugBits() {
535 if (!is_wait) {
536 #if 1
537 // By default, don't trace bits for is_ext_suspend_completed() calls.
538 // That trace is very chatty.
539 return;
540 #else
541 if (!called_by_wait) {
542 // If tracing for is_ext_suspend_completed() is enabled, then only
543 // trace calls to it from wait_for_ext_suspend_completion()
544 return;
545 }
546 #endif
547 }
548
549 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
550 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
551 MutexLocker ml(Threads_lock); // needed for get_thread_name()
552 ResourceMark rm;
553
554 tty->print_cr(
555 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
556 jt->get_thread_name(), *bits);
557
558 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
559 }
560 }
561 }
562 };
563 #undef DEBUG_FALSE_BITS
564
565
566 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
567 uint32_t *bits) {
568 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
569
570 bool did_trans_retry = false; // only do thread_in_native_trans retry once
571 bool do_trans_retry; // flag to force the retry
572
573 *bits |= 0x00000001;
574
575 do {
576 do_trans_retry = false;
577
578 if (is_exiting()) {
579 // Thread is in the process of exiting. This is always checked
580 // first to reduce the risk of dereferencing a freed JavaThread.
581 *bits |= 0x00000100;
582 return false;
583 }
584
585 if (!is_external_suspend()) {
586 // Suspend request is cancelled. This is always checked before
587 // is_ext_suspended() to reduce the risk of a rogue resume
588 // confusing the thread that made the suspend request.
589 *bits |= 0x00000200;
590 return false;
591 }
592
593 if (is_ext_suspended()) {
594 // thread is suspended
595 *bits |= 0x00000400;
596 return true;
597 }
598
599 // Now that we no longer do hard suspends of threads running
600 // native code, the target thread can be changing thread state
601 // while we are in this routine:
602 //
603 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
604 //
605 // We save a copy of the thread state as observed at this moment
606 // and make our decision about suspend completeness based on the
607 // copy. This closes the race where the thread state is seen as
608 // _thread_in_native_trans in the if-thread_blocked check, but is
609 // seen as _thread_blocked in if-thread_in_native_trans check.
610 JavaThreadState save_state = thread_state();
611
612 if (save_state == _thread_blocked && is_suspend_equivalent()) {
613 // If the thread's state is _thread_blocked and this blocking
614 // condition is known to be equivalent to a suspend, then we can
615 // consider the thread to be externally suspended. This means that
616 // the code that sets _thread_blocked has been modified to do
617 // self-suspension if the blocking condition releases. We also
618 // used to check for CONDVAR_WAIT here, but that is now covered by
619 // the _thread_blocked with self-suspension check.
620 //
621 // Return true since we wouldn't be here unless there was still an
622 // external suspend request.
623 *bits |= 0x00001000;
624 return true;
625 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
626 // Threads running native code will self-suspend on native==>VM/Java
627 // transitions. If its stack is walkable (should always be the case
628 // unless this function is called before the actual java_suspend()
629 // call), then the wait is done.
630 *bits |= 0x00002000;
631 return true;
632 } else if (!called_by_wait && !did_trans_retry &&
633 save_state == _thread_in_native_trans &&
634 frame_anchor()->walkable()) {
635 // The thread is transitioning from thread_in_native to another
636 // thread state. check_safepoint_and_suspend_for_native_trans()
637 // will force the thread to self-suspend. If it hasn't gotten
638 // there yet we may have caught the thread in-between the native
639 // code check above and the self-suspend. Lucky us. If we were
640 // called by wait_for_ext_suspend_completion(), then it
641 // will be doing the retries so we don't have to.
642 //
643 // Since we use the saved thread state in the if-statement above,
644 // there is a chance that the thread has already transitioned to
645 // _thread_blocked by the time we get here. In that case, we will
646 // make a single unnecessary pass through the logic below. This
647 // doesn't hurt anything since we still do the trans retry.
648
649 *bits |= 0x00004000;
650
651 // Once the thread leaves thread_in_native_trans for another
652 // thread state, we break out of this retry loop. We shouldn't
653 // need this flag to prevent us from getting back here, but
654 // sometimes paranoia is good.
655 did_trans_retry = true;
656
657 // We wait for the thread to transition to a more usable state.
658 for (int i = 1; i <= SuspendRetryCount; i++) {
659 // We used to do an "os::yield_all(i)" call here with the intention
660 // that yielding would increase on each retry. However, the parameter
661 // is ignored on Linux which means the yield didn't scale up. Waiting
662 // on the SR_lock below provides a much more predictable scale up for
663 // the delay. It also provides a simple/direct point to check for any
664 // safepoint requests from the VMThread
665
666 // temporarily drops SR_lock while doing wait with safepoint check
667 // (if we're a JavaThread - the WatcherThread can also call this)
668 // and increase delay with each retry
669 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
670
671 // check the actual thread state instead of what we saved above
672 if (thread_state() != _thread_in_native_trans) {
673 // the thread has transitioned to another thread state so
674 // try all the checks (except this one) one more time.
675 do_trans_retry = true;
676 break;
677 }
678 } // end retry loop
679
680
681 }
682 } while (do_trans_retry);
683
684 *bits |= 0x00000010;
685 return false;
686 }
687
688 // Wait for an external suspend request to complete (or be cancelled).
689 // Returns true if the thread is externally suspended and false otherwise.
690 //
691 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
692 uint32_t *bits) {
693 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
694 false /* !called_by_wait */, bits);
695
696 // local flag copies to minimize SR_lock hold time
697 bool is_suspended;
698 bool pending;
699 uint32_t reset_bits;
700
701 // set a marker so is_ext_suspend_completed() knows we are the caller
702 *bits |= 0x00010000;
703
704 // We use reset_bits to reinitialize the bits value at the top of
705 // each retry loop. This allows the caller to make use of any
706 // unused bits for their own marking purposes.
707 reset_bits = *bits;
708
709 {
710 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
711 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
712 delay, bits);
713 pending = is_external_suspend();
714 }
715 // must release SR_lock to allow suspension to complete
716
717 if (!pending) {
718 // A cancelled suspend request is the only false return from
719 // is_ext_suspend_completed() that keeps us from entering the
720 // retry loop.
721 *bits |= 0x00020000;
722 return false;
723 }
724
725 if (is_suspended) {
726 *bits |= 0x00040000;
727 return true;
728 }
729
730 for (int i = 1; i <= retries; i++) {
731 *bits = reset_bits; // reinit to only track last retry
732
733 // We used to do an "os::yield_all(i)" call here with the intention
734 // that yielding would increase on each retry. However, the parameter
735 // is ignored on Linux which means the yield didn't scale up. Waiting
736 // on the SR_lock below provides a much more predictable scale up for
737 // the delay. It also provides a simple/direct point to check for any
738 // safepoint requests from the VMThread
739
740 {
741 MutexLocker ml(SR_lock());
742 // wait with safepoint check (if we're a JavaThread - the WatcherThread
743 // can also call this) and increase delay with each retry
744 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
745
746 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
747 delay, bits);
748
749 // It is possible for the external suspend request to be cancelled
750 // (by a resume) before the actual suspend operation is completed.
751 // Refresh our local copy to see if we still need to wait.
752 pending = is_external_suspend();
753 }
754
755 if (!pending) {
756 // A cancelled suspend request is the only false return from
757 // is_ext_suspend_completed() that keeps us from staying in the
758 // retry loop.
759 *bits |= 0x00080000;
760 return false;
761 }
762
763 if (is_suspended) {
764 *bits |= 0x00100000;
765 return true;
766 }
767 } // end retry loop
768
769 // thread did not suspend after all our retries
770 *bits |= 0x00200000;
771 return false;
772 }
773
774 // Called from API entry points which perform stack walking. If the
775 // associated JavaThread is the current thread, then wait_for_suspend
776 // is not used. Otherwise, it determines if we should wait for the
777 // "other" thread to complete external suspension. (NOTE: in future
778 // releases the suspension mechanism should be reimplemented so this
779 // is not necessary.)
780 //
781 bool
782 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
783 if (this != JavaThread::current()) {
784 // "other" threads require special handling.
785 if (wait_for_suspend) {
786 // We are allowed to wait for the external suspend to complete
787 // so give the other thread a chance to get suspended.
788 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
789 SuspendRetryDelay, bits)) {
790 // Didn't make it so let the caller know.
791 return false;
792 }
793 }
794 // We aren't allowed to wait for the external suspend to complete
795 // so if the other thread isn't externally suspended we need to
796 // let the caller know.
797 else if (!is_ext_suspend_completed_with_lock(bits)) {
798 return false;
799 }
800 }
801
802 return true;
803 }
804
805 #ifndef PRODUCT
806 void JavaThread::record_jump(address target, address instr, const char* file,
807 int line) {
808
809 // This should not need to be atomic as the only way for simultaneous
810 // updates is via interrupts. Even then this should be rare or non-existent
811 // and we don't care that much anyway.
812
813 int index = _jmp_ring_index;
814 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
815 _jmp_ring[index]._target = (intptr_t) target;
816 _jmp_ring[index]._instruction = (intptr_t) instr;
817 _jmp_ring[index]._file = file;
818 _jmp_ring[index]._line = line;
819 }
820 #endif // PRODUCT
821
822 void Thread::interrupt(Thread* thread) {
823 debug_only(check_for_dangling_thread_pointer(thread);)
824 os::interrupt(thread);
825 }
826
827 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
828 debug_only(check_for_dangling_thread_pointer(thread);)
829 // Note: If clear_interrupted==false, this simply fetches and
830 // returns the value of the field osthread()->interrupted().
831 return os::is_interrupted(thread, clear_interrupted);
832 }
833
834
835 // GC Support
836 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
837 int thread_parity = _oops_do_parity;
838 if (thread_parity != strong_roots_parity) {
839 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
840 if (res == thread_parity) {
841 return true;
842 } else {
843 guarantee(res == strong_roots_parity, "Or else what?");
844 return false;
845 }
846 }
847 return false;
848 }
849
850 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
851 active_handles()->oops_do(f);
852 // Do oop for ThreadShadow
853 f->do_oop((oop*)&_pending_exception);
854 handle_area()->oops_do(f);
855
856 if (MonitorInUseLists) {
857 // When using thread local monitor lists, we scan them here,
858 // and the remaining global monitors in ObjectSynchronizer::oops_do().
859 ObjectSynchronizer::thread_local_used_oops_do(this, f);
860 }
861 }
862
863 void Thread::metadata_handles_do(void f(Metadata*)) {
864 // Only walk the Handles in Thread.
865 if (metadata_handles() != NULL) {
866 for (int i = 0; i< metadata_handles()->length(); i++) {
867 f(metadata_handles()->at(i));
868 }
869 }
870 }
871
872 void Thread::print_on(outputStream* st) const {
873 // get_priority assumes osthread initialized
874 if (osthread() != NULL) {
875 int os_prio;
876 if (os::get_native_priority(this, &os_prio) == OS_OK) {
877 st->print("os_prio=%d ", os_prio);
878 }
879 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
880 osthread()->print_on(st);
881 }
882 if (_threads_hazard_ptr != NULL) {
883 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
884 }
885 if (_nested_threads_hazard_ptr != NULL) {
886 print_nested_threads_hazard_ptrs_on(st);
887 }
888 st->print(" ");
889 debug_only(if (WizardMode) print_owned_locks_on(st);)
890 }
891
892 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
893 assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
894
895 if (EnableThreadSMRStatistics) {
896 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
897 }
898 st->print(", _nested_threads_hazard_ptrs=");
899 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
900 node = node->next()) {
901 if (node != _nested_threads_hazard_ptr) {
902 // First node does not need a comma-space separator.
903 st->print(", ");
904 }
905 st->print(INTPTR_FORMAT, p2i(node->t_list()));
906 }
907 }
908
909 // Thread::print_on_error() is called by fatal error handler. Don't use
910 // any lock or allocate memory.
911 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
912 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
913
914 if (is_VM_thread()) { st->print("VMThread"); }
915 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
916 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
917 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
918 else { st->print("Thread"); }
919
920 if (is_Named_thread()) {
921 st->print(" \"%s\"", name());
922 }
923
924 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
925 p2i(stack_end()), p2i(stack_base()));
926
927 if (osthread()) {
928 st->print(" [id=%d]", osthread()->thread_id());
929 }
930
931 if (_threads_hazard_ptr != NULL) {
932 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
933 }
934 if (_nested_threads_hazard_ptr != NULL) {
935 print_nested_threads_hazard_ptrs_on(st);
936 }
937 }
938
939 void Thread::print_value_on(outputStream* st) const {
940 if (is_Named_thread()) {
941 st->print(" \"%s\" ", name());
942 }
943 st->print(INTPTR_FORMAT, p2i(this)); // print address
944 }
945
946 #ifdef ASSERT
947 void Thread::print_owned_locks_on(outputStream* st) const {
948 Monitor *cur = _owned_locks;
949 if (cur == NULL) {
950 st->print(" (no locks) ");
951 } else {
952 st->print_cr(" Locks owned:");
953 while (cur) {
954 cur->print_on(st);
955 cur = cur->next();
956 }
957 }
958 }
959
960 static int ref_use_count = 0;
961
962 bool Thread::owns_locks_but_compiled_lock() const {
963 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
964 if (cur != Compile_lock) return true;
965 }
966 return false;
967 }
968
969
970 #endif
971
972 #ifndef PRODUCT
973
974 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
975 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
976 // no threads which allow_vm_block's are held
977 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
978 // Check if current thread is allowed to block at a safepoint
979 if (!(_allow_safepoint_count == 0)) {
980 fatal("Possible safepoint reached by thread that does not allow it");
981 }
982 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
983 fatal("LEAF method calling lock?");
984 }
985
986 #ifdef ASSERT
987 if (potential_vm_operation && is_Java_thread()
988 && !Universe::is_bootstrapping()) {
989 // Make sure we do not hold any locks that the VM thread also uses.
990 // This could potentially lead to deadlocks
991 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
992 // Threads_lock is special, since the safepoint synchronization will not start before this is
993 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
994 // since it is used to transfer control between JavaThreads and the VMThread
995 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
996 if ((cur->allow_vm_block() &&
997 cur != Threads_lock &&
998 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
999 cur != VMOperationRequest_lock &&
1000 cur != VMOperationQueue_lock) ||
1001 cur->rank() == Mutex::special) {
1002 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1003 }
1004 }
1005 }
1006
1007 if (GCALotAtAllSafepoints) {
1008 // We could enter a safepoint here and thus have a gc
1009 InterfaceSupport::check_gc_alot();
1010 }
1011 #endif
1012 }
1013 #endif
1014
1015 bool Thread::is_in_stack(address adr) const {
1016 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1017 address end = os::current_stack_pointer();
1018 // Allow non Java threads to call this without stack_base
1019 if (_stack_base == NULL) return true;
1020 if (stack_base() >= adr && adr >= end) return true;
1021
1022 return false;
1023 }
1024
1025 bool Thread::is_in_usable_stack(address adr) const {
1026 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1027 size_t usable_stack_size = _stack_size - stack_guard_size;
1028
1029 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1030 }
1031
1032
1033 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1034 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1035 // used for compilation in the future. If that change is made, the need for these methods
1036 // should be revisited, and they should be removed if possible.
1037
1038 bool Thread::is_lock_owned(address adr) const {
1039 return on_local_stack(adr);
1040 }
1041
1042 bool Thread::set_as_starting_thread() {
1043 // NOTE: this must be called inside the main thread.
1044 return os::create_main_thread((JavaThread*)this);
1045 }
1046
1047 static void initialize_class(Symbol* class_name, TRAPS) {
1048 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1049 InstanceKlass::cast(klass)->initialize(CHECK);
1050 }
1051
1052
1053 // Creates the initial ThreadGroup
1054 static Handle create_initial_thread_group(TRAPS) {
1055 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
1056 InstanceKlass* ik = InstanceKlass::cast(k);
1057
1058 Handle system_instance = ik->allocate_instance_handle(CHECK_NH);
1059 {
1060 JavaValue result(T_VOID);
1061 JavaCalls::call_special(&result,
1062 system_instance,
1063 ik,
1064 vmSymbols::object_initializer_name(),
1065 vmSymbols::void_method_signature(),
1066 CHECK_NH);
1067 }
1068 Universe::set_system_thread_group(system_instance());
1069
1070 Handle main_instance = ik->allocate_instance_handle(CHECK_NH);
1071 {
1072 JavaValue result(T_VOID);
1073 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1074 JavaCalls::call_special(&result,
1075 main_instance,
1076 ik,
1077 vmSymbols::object_initializer_name(),
1078 vmSymbols::threadgroup_string_void_signature(),
1079 system_instance,
1080 string,
1081 CHECK_NH);
1082 }
1083 return main_instance;
1084 }
1085
1086 // Creates the initial Thread
1087 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1088 TRAPS) {
1089 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
1090 InstanceKlass* ik = InstanceKlass::cast(k);
1091 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1092
1093 java_lang_Thread::set_thread(thread_oop(), thread);
1094 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1095 thread->set_threadObj(thread_oop());
1096
1097 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1098
1099 JavaValue result(T_VOID);
1100 JavaCalls::call_special(&result, thread_oop,
1101 ik,
1102 vmSymbols::object_initializer_name(),
1103 vmSymbols::threadgroup_string_void_signature(),
1104 thread_group,
1105 string,
1106 CHECK_NULL);
1107 return thread_oop();
1108 }
1109
1110 char java_runtime_name[128] = "";
1111 char java_runtime_version[128] = "";
1112
1113 // extract the JRE name from java.lang.VersionProps.java_runtime_name
1114 static const char* get_java_runtime_name(TRAPS) {
1115 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1116 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1117 fieldDescriptor fd;
1118 bool found = k != NULL &&
1119 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1120 vmSymbols::string_signature(), &fd);
1121 if (found) {
1122 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1123 if (name_oop == NULL) {
1124 return NULL;
1125 }
1126 const char* name = java_lang_String::as_utf8_string(name_oop,
1127 java_runtime_name,
1128 sizeof(java_runtime_name));
1129 return name;
1130 } else {
1131 return NULL;
1132 }
1133 }
1134
1135 // extract the JRE version from java.lang.VersionProps.java_runtime_version
1136 static const char* get_java_runtime_version(TRAPS) {
1137 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1138 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1139 fieldDescriptor fd;
1140 bool found = k != NULL &&
1141 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1142 vmSymbols::string_signature(), &fd);
1143 if (found) {
1144 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1145 if (name_oop == NULL) {
1146 return NULL;
1147 }
1148 const char* name = java_lang_String::as_utf8_string(name_oop,
1149 java_runtime_version,
1150 sizeof(java_runtime_version));
1151 return name;
1152 } else {
1153 return NULL;
1154 }
1155 }
1156
1157 // General purpose hook into Java code, run once when the VM is initialized.
1158 // The Java library method itself may be changed independently from the VM.
1159 static void call_postVMInitHook(TRAPS) {
1160 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1161 if (klass != NULL) {
1162 JavaValue result(T_VOID);
1163 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1164 vmSymbols::void_method_signature(),
1165 CHECK);
1166 }
1167 }
1168
1169 static void reset_vm_info_property(TRAPS) {
1170 // the vm info string
1171 ResourceMark rm(THREAD);
1172 const char *vm_info = VM_Version::vm_info_string();
1173
1174 // java.lang.System class
1175 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1176
1177 // setProperty arguments
1178 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1179 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1180
1181 // return value
1182 JavaValue r(T_OBJECT);
1183
1184 // public static String setProperty(String key, String value);
1185 JavaCalls::call_static(&r,
1186 klass,
1187 vmSymbols::setProperty_name(),
1188 vmSymbols::string_string_string_signature(),
1189 key_str,
1190 value_str,
1191 CHECK);
1192 }
1193
1194
1195 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1196 bool daemon, TRAPS) {
1197 assert(thread_group.not_null(), "thread group should be specified");
1198 assert(threadObj() == NULL, "should only create Java thread object once");
1199
1200 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1201 InstanceKlass* ik = InstanceKlass::cast(k);
1202 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1203
1204 java_lang_Thread::set_thread(thread_oop(), this);
1205 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1206 set_threadObj(thread_oop());
1207
1208 JavaValue result(T_VOID);
1209 if (thread_name != NULL) {
1210 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1211 // Thread gets assigned specified name and null target
1212 JavaCalls::call_special(&result,
1213 thread_oop,
1214 ik,
1215 vmSymbols::object_initializer_name(),
1216 vmSymbols::threadgroup_string_void_signature(),
1217 thread_group, // Argument 1
1218 name, // Argument 2
1219 THREAD);
1220 } else {
1221 // Thread gets assigned name "Thread-nnn" and null target
1222 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1223 JavaCalls::call_special(&result,
1224 thread_oop,
1225 ik,
1226 vmSymbols::object_initializer_name(),
1227 vmSymbols::threadgroup_runnable_void_signature(),
1228 thread_group, // Argument 1
1229 Handle(), // Argument 2
1230 THREAD);
1231 }
1232
1233
1234 if (daemon) {
1235 java_lang_Thread::set_daemon(thread_oop());
1236 }
1237
1238 if (HAS_PENDING_EXCEPTION) {
1239 return;
1240 }
1241
1242 Klass* group = SystemDictionary::ThreadGroup_klass();
1243 Handle threadObj(THREAD, this->threadObj());
1244
1245 JavaCalls::call_special(&result,
1246 thread_group,
1247 group,
1248 vmSymbols::add_method_name(),
1249 vmSymbols::thread_void_signature(),
1250 threadObj, // Arg 1
1251 THREAD);
1252 }
1253
1254 // NamedThread -- non-JavaThread subclasses with multiple
1255 // uniquely named instances should derive from this.
1256 NamedThread::NamedThread() : Thread() {
1257 _name = NULL;
1258 _processed_thread = NULL;
1259 _gc_id = GCId::undefined();
1260 }
1261
1262 NamedThread::~NamedThread() {
1263 if (_name != NULL) {
1264 FREE_C_HEAP_ARRAY(char, _name);
1265 _name = NULL;
1266 }
1267 }
1268
1269 void NamedThread::set_name(const char* format, ...) {
1270 guarantee(_name == NULL, "Only get to set name once.");
1271 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1272 guarantee(_name != NULL, "alloc failure");
1273 va_list ap;
1274 va_start(ap, format);
1275 jio_vsnprintf(_name, max_name_len, format, ap);
1276 va_end(ap);
1277 }
1278
1279 void NamedThread::initialize_named_thread() {
1280 set_native_thread_name(name());
1281 }
1282
1283 void NamedThread::print_on(outputStream* st) const {
1284 st->print("\"%s\" ", name());
1285 Thread::print_on(st);
1286 st->cr();
1287 }
1288
1289
1290 // ======= WatcherThread ========
1291
1292 // The watcher thread exists to simulate timer interrupts. It should
1293 // be replaced by an abstraction over whatever native support for
1294 // timer interrupts exists on the platform.
1295
1296 WatcherThread* WatcherThread::_watcher_thread = NULL;
1297 bool WatcherThread::_startable = false;
1298 volatile bool WatcherThread::_should_terminate = false;
1299
1300 WatcherThread::WatcherThread() : Thread() {
1301 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1302 if (os::create_thread(this, os::watcher_thread)) {
1303 _watcher_thread = this;
1304
1305 // Set the watcher thread to the highest OS priority which should not be
1306 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1307 // is created. The only normal thread using this priority is the reference
1308 // handler thread, which runs for very short intervals only.
1309 // If the VMThread's priority is not lower than the WatcherThread profiling
1310 // will be inaccurate.
1311 os::set_priority(this, MaxPriority);
1312 if (!DisableStartThread) {
1313 os::start_thread(this);
1314 }
1315 }
1316 }
1317
1318 int WatcherThread::sleep() const {
1319 // The WatcherThread does not participate in the safepoint protocol
1320 // for the PeriodicTask_lock because it is not a JavaThread.
1321 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1322
1323 if (_should_terminate) {
1324 // check for termination before we do any housekeeping or wait
1325 return 0; // we did not sleep.
1326 }
1327
1328 // remaining will be zero if there are no tasks,
1329 // causing the WatcherThread to sleep until a task is
1330 // enrolled
1331 int remaining = PeriodicTask::time_to_wait();
1332 int time_slept = 0;
1333
1334 // we expect this to timeout - we only ever get unparked when
1335 // we should terminate or when a new task has been enrolled
1336 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1337
1338 jlong time_before_loop = os::javaTimeNanos();
1339
1340 while (true) {
1341 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1342 remaining);
1343 jlong now = os::javaTimeNanos();
1344
1345 if (remaining == 0) {
1346 // if we didn't have any tasks we could have waited for a long time
1347 // consider the time_slept zero and reset time_before_loop
1348 time_slept = 0;
1349 time_before_loop = now;
1350 } else {
1351 // need to recalculate since we might have new tasks in _tasks
1352 time_slept = (int) ((now - time_before_loop) / 1000000);
1353 }
1354
1355 // Change to task list or spurious wakeup of some kind
1356 if (timedout || _should_terminate) {
1357 break;
1358 }
1359
1360 remaining = PeriodicTask::time_to_wait();
1361 if (remaining == 0) {
1362 // Last task was just disenrolled so loop around and wait until
1363 // another task gets enrolled
1364 continue;
1365 }
1366
1367 remaining -= time_slept;
1368 if (remaining <= 0) {
1369 break;
1370 }
1371 }
1372
1373 return time_slept;
1374 }
1375
1376 void WatcherThread::run() {
1377 assert(this == watcher_thread(), "just checking");
1378
1379 this->record_stack_base_and_size();
1380 this->set_native_thread_name(this->name());
1381 this->set_active_handles(JNIHandleBlock::allocate_block());
1382 while (true) {
1383 assert(watcher_thread() == Thread::current(), "thread consistency check");
1384 assert(watcher_thread() == this, "thread consistency check");
1385
1386 // Calculate how long it'll be until the next PeriodicTask work
1387 // should be done, and sleep that amount of time.
1388 int time_waited = sleep();
1389
1390 if (VMError::is_error_reported()) {
1391 // A fatal error has happened, the error handler(VMError::report_and_die)
1392 // should abort JVM after creating an error log file. However in some
1393 // rare cases, the error handler itself might deadlock. Here periodically
1394 // check for error reporting timeouts, and if it happens, just proceed to
1395 // abort the VM.
1396
1397 // This code is in WatcherThread because WatcherThread wakes up
1398 // periodically so the fatal error handler doesn't need to do anything;
1399 // also because the WatcherThread is less likely to crash than other
1400 // threads.
1401
1402 for (;;) {
1403 // Note: we use naked sleep in this loop because we want to avoid using
1404 // any kind of VM infrastructure which may be broken at this point.
1405 if (VMError::check_timeout()) {
1406 // We hit error reporting timeout. Error reporting was interrupted and
1407 // will be wrapping things up now (closing files etc). Give it some more
1408 // time, then quit the VM.
1409 os::naked_short_sleep(200);
1410 // Print a message to stderr.
1411 fdStream err(defaultStream::output_fd());
1412 err.print_raw_cr("# [ timer expired, abort... ]");
1413 // skip atexit/vm_exit/vm_abort hooks
1414 os::die();
1415 }
1416
1417 // Wait a second, then recheck for timeout.
1418 os::naked_short_sleep(999);
1419 }
1420 }
1421
1422 if (_should_terminate) {
1423 // check for termination before posting the next tick
1424 break;
1425 }
1426
1427 PeriodicTask::real_time_tick(time_waited);
1428 }
1429
1430 // Signal that it is terminated
1431 {
1432 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1433 _watcher_thread = NULL;
1434 Terminator_lock->notify();
1435 }
1436 }
1437
1438 void WatcherThread::start() {
1439 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1440
1441 if (watcher_thread() == NULL && _startable) {
1442 _should_terminate = false;
1443 // Create the single instance of WatcherThread
1444 new WatcherThread();
1445 }
1446 }
1447
1448 void WatcherThread::make_startable() {
1449 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1450 _startable = true;
1451 }
1452
1453 void WatcherThread::stop() {
1454 {
1455 // Follow normal safepoint aware lock enter protocol since the
1456 // WatcherThread is stopped by another JavaThread.
1457 MutexLocker ml(PeriodicTask_lock);
1458 _should_terminate = true;
1459
1460 WatcherThread* watcher = watcher_thread();
1461 if (watcher != NULL) {
1462 // unpark the WatcherThread so it can see that it should terminate
1463 watcher->unpark();
1464 }
1465 }
1466
1467 MutexLocker mu(Terminator_lock);
1468
1469 while (watcher_thread() != NULL) {
1470 // This wait should make safepoint checks, wait without a timeout,
1471 // and wait as a suspend-equivalent condition.
1472 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1473 Mutex::_as_suspend_equivalent_flag);
1474 }
1475 }
1476
1477 void WatcherThread::unpark() {
1478 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1479 PeriodicTask_lock->notify();
1480 }
1481
1482 void WatcherThread::print_on(outputStream* st) const {
1483 st->print("\"%s\" ", name());
1484 Thread::print_on(st);
1485 st->cr();
1486 }
1487
1488 // ======= JavaThread ========
1489
1490 #if INCLUDE_JVMCI
1491
1492 jlong* JavaThread::_jvmci_old_thread_counters;
1493
1494 bool jvmci_counters_include(JavaThread* thread) {
1495 oop threadObj = thread->threadObj();
1496 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1497 }
1498
1499 void JavaThread::collect_counters(typeArrayOop array) {
1500 if (JVMCICounterSize > 0) {
1501 MutexLocker tl(Threads_lock);
1502 JavaThreadIteratorWithHandle jtiwh;
1503 for (int i = 0; i < array->length(); i++) {
1504 array->long_at_put(i, _jvmci_old_thread_counters[i]);
1505 }
1506 for (; JavaThread *tp = jtiwh.next(); ) {
1507 if (jvmci_counters_include(tp)) {
1508 for (int i = 0; i < array->length(); i++) {
1509 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
1510 }
1511 }
1512 }
1513 }
1514 }
1515
1516 #endif // INCLUDE_JVMCI
1517
1518 // A JavaThread is a normal Java thread
1519
1520 void JavaThread::initialize() {
1521 // Initialize fields
1522
1523 set_saved_exception_pc(NULL);
1524 set_threadObj(NULL);
1525 _anchor.clear();
1526 set_entry_point(NULL);
1527 set_jni_functions(jni_functions());
1528 set_callee_target(NULL);
1529 set_vm_result(NULL);
1530 set_vm_result_2(NULL);
1531 set_vframe_array_head(NULL);
1532 set_vframe_array_last(NULL);
1533 set_deferred_locals(NULL);
1534 set_deopt_mark(NULL);
1535 set_deopt_compiled_method(NULL);
1536 clear_must_deopt_id();
1537 set_monitor_chunks(NULL);
1538 set_next(NULL);
1539 _on_thread_list = false;
1540 set_thread_state(_thread_new);
1541 _terminated = _not_terminated;
1542 _privileged_stack_top = NULL;
1543 _array_for_gc = NULL;
1544 _suspend_equivalent = false;
1545 _in_deopt_handler = 0;
1546 _doing_unsafe_access = false;
1547 _stack_guard_state = stack_guard_unused;
1548 #if INCLUDE_JVMCI
1549 _pending_monitorenter = false;
1550 _pending_deoptimization = -1;
1551 _pending_failed_speculation = NULL;
1552 _pending_transfer_to_interpreter = false;
1553 _adjusting_comp_level = false;
1554 _jvmci._alternate_call_target = NULL;
1555 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1556 if (JVMCICounterSize > 0) {
1557 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
1558 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize);
1559 } else {
1560 _jvmci_counters = NULL;
1561 }
1562 #endif // INCLUDE_JVMCI
1563 _reserved_stack_activation = NULL; // stack base not known yet
1564 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1565 _exception_pc = 0;
1566 _exception_handler_pc = 0;
1567 _is_method_handle_return = 0;
1568 _jvmti_thread_state= NULL;
1569 _should_post_on_exceptions_flag = JNI_FALSE;
1570 _jvmti_get_loaded_classes_closure = NULL;
1571 _interp_only_mode = 0;
1572 _special_runtime_exit_condition = _no_async_condition;
1573 _pending_async_exception = NULL;
1574 _thread_stat = NULL;
1575 _thread_stat = new ThreadStatistics();
1576 _blocked_on_compilation = false;
1577 _jni_active_critical = 0;
1578 _pending_jni_exception_check_fn = NULL;
1579 _do_not_unlock_if_synchronized = false;
1580 _cached_monitor_info = NULL;
1581 _parker = Parker::Allocate(this);
1582
1583 #ifndef PRODUCT
1584 _jmp_ring_index = 0;
1585 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1586 record_jump(NULL, NULL, NULL, 0);
1587 }
1588 #endif // PRODUCT
1589
1590 // Setup safepoint state info for this thread
1591 ThreadSafepointState::create(this);
1592
1593 debug_only(_java_call_counter = 0);
1594
1595 // JVMTI PopFrame support
1596 _popframe_condition = popframe_inactive;
1597 _popframe_preserved_args = NULL;
1598 _popframe_preserved_args_size = 0;
1599 _frames_to_pop_failed_realloc = 0;
1600
1601 if (SafepointMechanism::uses_thread_local_poll()) {
1602 SafepointMechanism::initialize_header(this);
1603 }
1604
1605 pd_initialize();
1606 }
1607
1608 JavaThread::JavaThread(bool is_attaching_via_jni) :
1609 Thread() {
1610 initialize();
1611 if (is_attaching_via_jni) {
1612 _jni_attach_state = _attaching_via_jni;
1613 } else {
1614 _jni_attach_state = _not_attaching_via_jni;
1615 }
1616 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1617 }
1618
1619 bool JavaThread::reguard_stack(address cur_sp) {
1620 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1621 && _stack_guard_state != stack_guard_reserved_disabled) {
1622 return true; // Stack already guarded or guard pages not needed.
1623 }
1624
1625 if (register_stack_overflow()) {
1626 // For those architectures which have separate register and
1627 // memory stacks, we must check the register stack to see if
1628 // it has overflowed.
1629 return false;
1630 }
1631
1632 // Java code never executes within the yellow zone: the latter is only
1633 // there to provoke an exception during stack banging. If java code
1634 // is executing there, either StackShadowPages should be larger, or
1635 // some exception code in c1, c2 or the interpreter isn't unwinding
1636 // when it should.
1637 guarantee(cur_sp > stack_reserved_zone_base(),
1638 "not enough space to reguard - increase StackShadowPages");
1639 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1640 enable_stack_yellow_reserved_zone();
1641 if (reserved_stack_activation() != stack_base()) {
1642 set_reserved_stack_activation(stack_base());
1643 }
1644 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1645 set_reserved_stack_activation(stack_base());
1646 enable_stack_reserved_zone();
1647 }
1648 return true;
1649 }
1650
1651 bool JavaThread::reguard_stack(void) {
1652 return reguard_stack(os::current_stack_pointer());
1653 }
1654
1655
1656 void JavaThread::block_if_vm_exited() {
1657 if (_terminated == _vm_exited) {
1658 // _vm_exited is set at safepoint, and Threads_lock is never released
1659 // we will block here forever
1660 Threads_lock->lock_without_safepoint_check();
1661 ShouldNotReachHere();
1662 }
1663 }
1664
1665
1666 // Remove this ifdef when C1 is ported to the compiler interface.
1667 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1668 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1669
1670 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1671 Thread() {
1672 initialize();
1673 _jni_attach_state = _not_attaching_via_jni;
1674 set_entry_point(entry_point);
1675 // Create the native thread itself.
1676 // %note runtime_23
1677 os::ThreadType thr_type = os::java_thread;
1678 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1679 os::java_thread;
1680 os::create_thread(this, thr_type, stack_sz);
1681 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1682 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1683 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1684 // the exception consists of creating the exception object & initializing it, initialization
1685 // will leave the VM via a JavaCall and then all locks must be unlocked).
1686 //
1687 // The thread is still suspended when we reach here. Thread must be explicit started
1688 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1689 // by calling Threads:add. The reason why this is not done here, is because the thread
1690 // object must be fully initialized (take a look at JVM_Start)
1691 }
1692
1693 JavaThread::~JavaThread() {
1694
1695 // JSR166 -- return the parker to the free list
1696 Parker::Release(_parker);
1697 _parker = NULL;
1698
1699 // Free any remaining previous UnrollBlock
1700 vframeArray* old_array = vframe_array_last();
1701
1702 if (old_array != NULL) {
1703 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1704 old_array->set_unroll_block(NULL);
1705 delete old_info;
1706 delete old_array;
1707 }
1708
1709 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1710 if (deferred != NULL) {
1711 // This can only happen if thread is destroyed before deoptimization occurs.
1712 assert(deferred->length() != 0, "empty array!");
1713 do {
1714 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1715 deferred->remove_at(0);
1716 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1717 delete dlv;
1718 } while (deferred->length() != 0);
1719 delete deferred;
1720 }
1721
1722 // All Java related clean up happens in exit
1723 ThreadSafepointState::destroy(this);
1724 if (_thread_stat != NULL) delete _thread_stat;
1725
1726 #if INCLUDE_JVMCI
1727 if (JVMCICounterSize > 0) {
1728 if (jvmci_counters_include(this)) {
1729 for (int i = 0; i < JVMCICounterSize; i++) {
1730 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1731 }
1732 }
1733 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1734 }
1735 #endif // INCLUDE_JVMCI
1736 }
1737
1738
1739 // The first routine called by a new Java thread
1740 void JavaThread::run() {
1741 // initialize thread-local alloc buffer related fields
1742 this->initialize_tlab();
1743
1744 // used to test validity of stack trace backs
1745 this->record_base_of_stack_pointer();
1746
1747 // Record real stack base and size.
1748 this->record_stack_base_and_size();
1749
1750 this->create_stack_guard_pages();
1751
1752 this->cache_global_variables();
1753
1754 // Thread is now sufficient initialized to be handled by the safepoint code as being
1755 // in the VM. Change thread state from _thread_new to _thread_in_vm
1756 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1757
1758 assert(JavaThread::current() == this, "sanity check");
1759 assert(!Thread::current()->owns_locks(), "sanity check");
1760
1761 DTRACE_THREAD_PROBE(start, this);
1762
1763 // This operation might block. We call that after all safepoint checks for a new thread has
1764 // been completed.
1765 this->set_active_handles(JNIHandleBlock::allocate_block());
1766
1767 if (JvmtiExport::should_post_thread_life()) {
1768 JvmtiExport::post_thread_start(this);
1769 }
1770
1771 EventThreadStart event;
1772 if (event.should_commit()) {
1773 event.set_thread(THREAD_TRACE_ID(this));
1774 event.commit();
1775 }
1776
1777 // We call another function to do the rest so we are sure that the stack addresses used
1778 // from there will be lower than the stack base just computed
1779 thread_main_inner();
1780
1781 // Note, thread is no longer valid at this point!
1782 }
1783
1784
1785 void JavaThread::thread_main_inner() {
1786 assert(JavaThread::current() == this, "sanity check");
1787 assert(this->threadObj() != NULL, "just checking");
1788
1789 // Execute thread entry point unless this thread has a pending exception
1790 // or has been stopped before starting.
1791 // Note: Due to JVM_StopThread we can have pending exceptions already!
1792 if (!this->has_pending_exception() &&
1793 !java_lang_Thread::is_stillborn(this->threadObj())) {
1794 {
1795 ResourceMark rm(this);
1796 this->set_native_thread_name(this->get_thread_name());
1797 }
1798 HandleMark hm(this);
1799 this->entry_point()(this, this);
1800 }
1801
1802 DTRACE_THREAD_PROBE(stop, this);
1803
1804 this->exit(false);
1805 this->smr_delete();
1806 }
1807
1808
1809 static void ensure_join(JavaThread* thread) {
1810 // We do not need to grab the Threads_lock, since we are operating on ourself.
1811 Handle threadObj(thread, thread->threadObj());
1812 assert(threadObj.not_null(), "java thread object must exist");
1813 ObjectLocker lock(threadObj, thread);
1814 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1815 thread->clear_pending_exception();
1816 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1817 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1818 // Clear the native thread instance - this makes isAlive return false and allows the join()
1819 // to complete once we've done the notify_all below
1820 java_lang_Thread::set_thread(threadObj(), NULL);
1821 lock.notify_all(thread);
1822 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1823 thread->clear_pending_exception();
1824 }
1825
1826
1827 // For any new cleanup additions, please check to see if they need to be applied to
1828 // cleanup_failed_attach_current_thread as well.
1829 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1830 assert(this == JavaThread::current(), "thread consistency check");
1831
1832 elapsedTimer _timer_exit_phase1;
1833 elapsedTimer _timer_exit_phase2;
1834 elapsedTimer _timer_exit_phase3;
1835 elapsedTimer _timer_exit_phase4;
1836
1837 if (log_is_enabled(Debug, os, thread, timer)) {
1838 _timer_exit_phase1.start();
1839 }
1840
1841 HandleMark hm(this);
1842 Handle uncaught_exception(this, this->pending_exception());
1843 this->clear_pending_exception();
1844 Handle threadObj(this, this->threadObj());
1845 assert(threadObj.not_null(), "Java thread object should be created");
1846
1847 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1848 {
1849 EXCEPTION_MARK;
1850
1851 CLEAR_PENDING_EXCEPTION;
1852 }
1853 if (!destroy_vm) {
1854 if (uncaught_exception.not_null()) {
1855 EXCEPTION_MARK;
1856 // Call method Thread.dispatchUncaughtException().
1857 Klass* thread_klass = SystemDictionary::Thread_klass();
1858 JavaValue result(T_VOID);
1859 JavaCalls::call_virtual(&result,
1860 threadObj, thread_klass,
1861 vmSymbols::dispatchUncaughtException_name(),
1862 vmSymbols::throwable_void_signature(),
1863 uncaught_exception,
1864 THREAD);
1865 if (HAS_PENDING_EXCEPTION) {
1866 ResourceMark rm(this);
1867 jio_fprintf(defaultStream::error_stream(),
1868 "\nException: %s thrown from the UncaughtExceptionHandler"
1869 " in thread \"%s\"\n",
1870 pending_exception()->klass()->external_name(),
1871 get_thread_name());
1872 CLEAR_PENDING_EXCEPTION;
1873 }
1874 }
1875
1876 // Called before the java thread exit since we want to read info
1877 // from java_lang_Thread object
1878 EventThreadEnd event;
1879 if (event.should_commit()) {
1880 event.set_thread(THREAD_TRACE_ID(this));
1881 event.commit();
1882 }
1883
1884 // Call after last event on thread
1885 EVENT_THREAD_EXIT(this);
1886
1887 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1888 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1889 // is deprecated anyhow.
1890 if (!is_Compiler_thread()) {
1891 int count = 3;
1892 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1893 EXCEPTION_MARK;
1894 JavaValue result(T_VOID);
1895 Klass* thread_klass = SystemDictionary::Thread_klass();
1896 JavaCalls::call_virtual(&result,
1897 threadObj, thread_klass,
1898 vmSymbols::exit_method_name(),
1899 vmSymbols::void_method_signature(),
1900 THREAD);
1901 CLEAR_PENDING_EXCEPTION;
1902 }
1903 }
1904 // notify JVMTI
1905 if (JvmtiExport::should_post_thread_life()) {
1906 JvmtiExport::post_thread_end(this);
1907 }
1908
1909 // We have notified the agents that we are exiting, before we go on,
1910 // we must check for a pending external suspend request and honor it
1911 // in order to not surprise the thread that made the suspend request.
1912 while (true) {
1913 {
1914 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1915 if (!is_external_suspend()) {
1916 set_terminated(_thread_exiting);
1917 ThreadService::current_thread_exiting(this);
1918 break;
1919 }
1920 // Implied else:
1921 // Things get a little tricky here. We have a pending external
1922 // suspend request, but we are holding the SR_lock so we
1923 // can't just self-suspend. So we temporarily drop the lock
1924 // and then self-suspend.
1925 }
1926
1927 ThreadBlockInVM tbivm(this);
1928 java_suspend_self();
1929
1930 // We're done with this suspend request, but we have to loop around
1931 // and check again. Eventually we will get SR_lock without a pending
1932 // external suspend request and will be able to mark ourselves as
1933 // exiting.
1934 }
1935 // no more external suspends are allowed at this point
1936 } else {
1937 // before_exit() has already posted JVMTI THREAD_END events
1938 }
1939
1940 if (log_is_enabled(Debug, os, thread, timer)) {
1941 _timer_exit_phase1.stop();
1942 _timer_exit_phase2.start();
1943 }
1944 // Notify waiters on thread object. This has to be done after exit() is called
1945 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1946 // group should have the destroyed bit set before waiters are notified).
1947 ensure_join(this);
1948 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1949
1950 if (log_is_enabled(Debug, os, thread, timer)) {
1951 _timer_exit_phase2.stop();
1952 _timer_exit_phase3.start();
1953 }
1954 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1955 // held by this thread must be released. The spec does not distinguish
1956 // between JNI-acquired and regular Java monitors. We can only see
1957 // regular Java monitors here if monitor enter-exit matching is broken.
1958 //
1959 // Optionally release any monitors for regular JavaThread exits. This
1960 // is provided as a work around for any bugs in monitor enter-exit
1961 // matching. This can be expensive so it is not enabled by default.
1962 //
1963 // ensure_join() ignores IllegalThreadStateExceptions, and so does
1964 // ObjectSynchronizer::release_monitors_owned_by_thread().
1965 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) {
1966 // Sanity check even though JNI DetachCurrentThread() would have
1967 // returned JNI_ERR if there was a Java frame. JavaThread exit
1968 // should be done executing Java code by the time we get here.
1969 assert(!this->has_last_Java_frame(),
1970 "should not have a Java frame when detaching or exiting");
1971 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1972 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1973 }
1974
1975 // These things needs to be done while we are still a Java Thread. Make sure that thread
1976 // is in a consistent state, in case GC happens
1977 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1978
1979 if (active_handles() != NULL) {
1980 JNIHandleBlock* block = active_handles();
1981 set_active_handles(NULL);
1982 JNIHandleBlock::release_block(block);
1983 }
1984
1985 if (free_handle_block() != NULL) {
1986 JNIHandleBlock* block = free_handle_block();
1987 set_free_handle_block(NULL);
1988 JNIHandleBlock::release_block(block);
1989 }
1990
1991 // These have to be removed while this is still a valid thread.
1992 remove_stack_guard_pages();
1993
1994 if (UseTLAB) {
1995 tlab().make_parsable(true); // retire TLAB
1996 }
1997
1998 if (JvmtiEnv::environments_might_exist()) {
1999 JvmtiExport::cleanup_thread(this);
2000 }
2001
2002 // We must flush any deferred card marks and other various GC barrier
2003 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2004 // before removing a thread from the list of active threads.
2005 BarrierSet::barrier_set()->on_thread_detach(this);
2006
2007 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2008 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2009 os::current_thread_id());
2010
2011 if (log_is_enabled(Debug, os, thread, timer)) {
2012 _timer_exit_phase3.stop();
2013 _timer_exit_phase4.start();
2014 }
2015 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2016 Threads::remove(this);
2017
2018 if (log_is_enabled(Debug, os, thread, timer)) {
2019 _timer_exit_phase4.stop();
2020 ResourceMark rm(this);
2021 log_debug(os, thread, timer)("name='%s'"
2022 ", exit-phase1=" JLONG_FORMAT
2023 ", exit-phase2=" JLONG_FORMAT
2024 ", exit-phase3=" JLONG_FORMAT
2025 ", exit-phase4=" JLONG_FORMAT,
2026 get_thread_name(),
2027 _timer_exit_phase1.milliseconds(),
2028 _timer_exit_phase2.milliseconds(),
2029 _timer_exit_phase3.milliseconds(),
2030 _timer_exit_phase4.milliseconds());
2031 }
2032 }
2033
2034 void JavaThread::cleanup_failed_attach_current_thread() {
2035 if (active_handles() != NULL) {
2036 JNIHandleBlock* block = active_handles();
2037 set_active_handles(NULL);
2038 JNIHandleBlock::release_block(block);
2039 }
2040
2041 if (free_handle_block() != NULL) {
2042 JNIHandleBlock* block = free_handle_block();
2043 set_free_handle_block(NULL);
2044 JNIHandleBlock::release_block(block);
2045 }
2046
2047 // These have to be removed while this is still a valid thread.
2048 remove_stack_guard_pages();
2049
2050 if (UseTLAB) {
2051 tlab().make_parsable(true); // retire TLAB, if any
2052 }
2053
2054 BarrierSet::barrier_set()->on_thread_detach(this);
2055
2056 Threads::remove(this);
2057 this->smr_delete();
2058 }
2059
2060 JavaThread* JavaThread::active() {
2061 Thread* thread = Thread::current();
2062 if (thread->is_Java_thread()) {
2063 return (JavaThread*) thread;
2064 } else {
2065 assert(thread->is_VM_thread(), "this must be a vm thread");
2066 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2067 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2068 assert(ret->is_Java_thread(), "must be a Java thread");
2069 return ret;
2070 }
2071 }
2072
2073 bool JavaThread::is_lock_owned(address adr) const {
2074 if (Thread::is_lock_owned(adr)) return true;
2075
2076 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2077 if (chunk->contains(adr)) return true;
2078 }
2079
2080 return false;
2081 }
2082
2083
2084 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2085 chunk->set_next(monitor_chunks());
2086 set_monitor_chunks(chunk);
2087 }
2088
2089 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2090 guarantee(monitor_chunks() != NULL, "must be non empty");
2091 if (monitor_chunks() == chunk) {
2092 set_monitor_chunks(chunk->next());
2093 } else {
2094 MonitorChunk* prev = monitor_chunks();
2095 while (prev->next() != chunk) prev = prev->next();
2096 prev->set_next(chunk->next());
2097 }
2098 }
2099
2100 // JVM support.
2101
2102 // Note: this function shouldn't block if it's called in
2103 // _thread_in_native_trans state (such as from
2104 // check_special_condition_for_native_trans()).
2105 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2106
2107 if (has_last_Java_frame() && has_async_condition()) {
2108 // If we are at a polling page safepoint (not a poll return)
2109 // then we must defer async exception because live registers
2110 // will be clobbered by the exception path. Poll return is
2111 // ok because the call we a returning from already collides
2112 // with exception handling registers and so there is no issue.
2113 // (The exception handling path kills call result registers but
2114 // this is ok since the exception kills the result anyway).
2115
2116 if (is_at_poll_safepoint()) {
2117 // if the code we are returning to has deoptimized we must defer
2118 // the exception otherwise live registers get clobbered on the
2119 // exception path before deoptimization is able to retrieve them.
2120 //
2121 RegisterMap map(this, false);
2122 frame caller_fr = last_frame().sender(&map);
2123 assert(caller_fr.is_compiled_frame(), "what?");
2124 if (caller_fr.is_deoptimized_frame()) {
2125 log_info(exceptions)("deferred async exception at compiled safepoint");
2126 return;
2127 }
2128 }
2129 }
2130
2131 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2132 if (condition == _no_async_condition) {
2133 // Conditions have changed since has_special_runtime_exit_condition()
2134 // was called:
2135 // - if we were here only because of an external suspend request,
2136 // then that was taken care of above (or cancelled) so we are done
2137 // - if we were here because of another async request, then it has
2138 // been cleared between the has_special_runtime_exit_condition()
2139 // and now so again we are done
2140 return;
2141 }
2142
2143 // Check for pending async. exception
2144 if (_pending_async_exception != NULL) {
2145 // Only overwrite an already pending exception, if it is not a threadDeath.
2146 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2147
2148 // We cannot call Exceptions::_throw(...) here because we cannot block
2149 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2150
2151 LogTarget(Info, exceptions) lt;
2152 if (lt.is_enabled()) {
2153 ResourceMark rm;
2154 LogStream ls(lt);
2155 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2156 if (has_last_Java_frame()) {
2157 frame f = last_frame();
2158 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2159 }
2160 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2161 }
2162 _pending_async_exception = NULL;
2163 clear_has_async_exception();
2164 }
2165 }
2166
2167 if (check_unsafe_error &&
2168 condition == _async_unsafe_access_error && !has_pending_exception()) {
2169 condition = _no_async_condition; // done
2170 switch (thread_state()) {
2171 case _thread_in_vm: {
2172 JavaThread* THREAD = this;
2173 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2174 }
2175 case _thread_in_native: {
2176 ThreadInVMfromNative tiv(this);
2177 JavaThread* THREAD = this;
2178 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2179 }
2180 case _thread_in_Java: {
2181 ThreadInVMfromJava tiv(this);
2182 JavaThread* THREAD = this;
2183 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2184 }
2185 default:
2186 ShouldNotReachHere();
2187 }
2188 }
2189
2190 assert(condition == _no_async_condition || has_pending_exception() ||
2191 (!check_unsafe_error && condition == _async_unsafe_access_error),
2192 "must have handled the async condition, if no exception");
2193 }
2194
2195 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2196 //
2197 // Check for pending external suspend. Internal suspend requests do
2198 // not use handle_special_runtime_exit_condition().
2199 // If JNIEnv proxies are allowed, don't self-suspend if the target
2200 // thread is not the current thread. In older versions of jdbx, jdbx
2201 // threads could call into the VM with another thread's JNIEnv so we
2202 // can be here operating on behalf of a suspended thread (4432884).
2203 bool do_self_suspend = is_external_suspend_with_lock();
2204 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2205 //
2206 // Because thread is external suspended the safepoint code will count
2207 // thread as at a safepoint. This can be odd because we can be here
2208 // as _thread_in_Java which would normally transition to _thread_blocked
2209 // at a safepoint. We would like to mark the thread as _thread_blocked
2210 // before calling java_suspend_self like all other callers of it but
2211 // we must then observe proper safepoint protocol. (We can't leave
2212 // _thread_blocked with a safepoint in progress). However we can be
2213 // here as _thread_in_native_trans so we can't use a normal transition
2214 // constructor/destructor pair because they assert on that type of
2215 // transition. We could do something like:
2216 //
2217 // JavaThreadState state = thread_state();
2218 // set_thread_state(_thread_in_vm);
2219 // {
2220 // ThreadBlockInVM tbivm(this);
2221 // java_suspend_self()
2222 // }
2223 // set_thread_state(_thread_in_vm_trans);
2224 // if (safepoint) block;
2225 // set_thread_state(state);
2226 //
2227 // but that is pretty messy. Instead we just go with the way the
2228 // code has worked before and note that this is the only path to
2229 // java_suspend_self that doesn't put the thread in _thread_blocked
2230 // mode.
2231
2232 frame_anchor()->make_walkable(this);
2233 java_suspend_self();
2234
2235 // We might be here for reasons in addition to the self-suspend request
2236 // so check for other async requests.
2237 }
2238
2239 if (check_asyncs) {
2240 check_and_handle_async_exceptions();
2241 }
2242 #if INCLUDE_TRACE
2243 if (is_trace_suspend()) {
2244 TRACE_SUSPEND_THREAD(this);
2245 }
2246 #endif
2247 }
2248
2249 void JavaThread::send_thread_stop(oop java_throwable) {
2250 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2251 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2252 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2253
2254 // Do not throw asynchronous exceptions against the compiler thread
2255 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2256 if (!can_call_java()) return;
2257
2258 {
2259 // Actually throw the Throwable against the target Thread - however
2260 // only if there is no thread death exception installed already.
2261 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2262 // If the topmost frame is a runtime stub, then we are calling into
2263 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2264 // must deoptimize the caller before continuing, as the compiled exception handler table
2265 // may not be valid
2266 if (has_last_Java_frame()) {
2267 frame f = last_frame();
2268 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2269 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2270 RegisterMap reg_map(this, UseBiasedLocking);
2271 frame compiled_frame = f.sender(®_map);
2272 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2273 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2274 }
2275 }
2276 }
2277
2278 // Set async. pending exception in thread.
2279 set_pending_async_exception(java_throwable);
2280
2281 if (log_is_enabled(Info, exceptions)) {
2282 ResourceMark rm;
2283 log_info(exceptions)("Pending Async. exception installed of type: %s",
2284 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2285 }
2286 // for AbortVMOnException flag
2287 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2288 }
2289 }
2290
2291
2292 // Interrupt thread so it will wake up from a potential wait()
2293 Thread::interrupt(this);
2294 }
2295
2296 // External suspension mechanism.
2297 //
2298 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2299 // to any VM_locks and it is at a transition
2300 // Self-suspension will happen on the transition out of the vm.
2301 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2302 //
2303 // Guarantees on return:
2304 // + Target thread will not execute any new bytecode (that's why we need to
2305 // force a safepoint)
2306 // + Target thread will not enter any new monitors
2307 //
2308 void JavaThread::java_suspend() {
2309 ThreadsListHandle tlh;
2310 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2311 return;
2312 }
2313
2314 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2315 if (!is_external_suspend()) {
2316 // a racing resume has cancelled us; bail out now
2317 return;
2318 }
2319
2320 // suspend is done
2321 uint32_t debug_bits = 0;
2322 // Warning: is_ext_suspend_completed() may temporarily drop the
2323 // SR_lock to allow the thread to reach a stable thread state if
2324 // it is currently in a transient thread state.
2325 if (is_ext_suspend_completed(false /* !called_by_wait */,
2326 SuspendRetryDelay, &debug_bits)) {
2327 return;
2328 }
2329 }
2330
2331 VM_ThreadSuspend vm_suspend;
2332 VMThread::execute(&vm_suspend);
2333 }
2334
2335 // Part II of external suspension.
2336 // A JavaThread self suspends when it detects a pending external suspend
2337 // request. This is usually on transitions. It is also done in places
2338 // where continuing to the next transition would surprise the caller,
2339 // e.g., monitor entry.
2340 //
2341 // Returns the number of times that the thread self-suspended.
2342 //
2343 // Note: DO NOT call java_suspend_self() when you just want to block current
2344 // thread. java_suspend_self() is the second stage of cooperative
2345 // suspension for external suspend requests and should only be used
2346 // to complete an external suspend request.
2347 //
2348 int JavaThread::java_suspend_self() {
2349 int ret = 0;
2350
2351 // we are in the process of exiting so don't suspend
2352 if (is_exiting()) {
2353 clear_external_suspend();
2354 return ret;
2355 }
2356
2357 assert(_anchor.walkable() ||
2358 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2359 "must have walkable stack");
2360
2361 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2362
2363 assert(!this->is_ext_suspended(),
2364 "a thread trying to self-suspend should not already be suspended");
2365
2366 if (this->is_suspend_equivalent()) {
2367 // If we are self-suspending as a result of the lifting of a
2368 // suspend equivalent condition, then the suspend_equivalent
2369 // flag is not cleared until we set the ext_suspended flag so
2370 // that wait_for_ext_suspend_completion() returns consistent
2371 // results.
2372 this->clear_suspend_equivalent();
2373 }
2374
2375 // A racing resume may have cancelled us before we grabbed SR_lock
2376 // above. Or another external suspend request could be waiting for us
2377 // by the time we return from SR_lock()->wait(). The thread
2378 // that requested the suspension may already be trying to walk our
2379 // stack and if we return now, we can change the stack out from under
2380 // it. This would be a "bad thing (TM)" and cause the stack walker
2381 // to crash. We stay self-suspended until there are no more pending
2382 // external suspend requests.
2383 while (is_external_suspend()) {
2384 ret++;
2385 this->set_ext_suspended();
2386
2387 // _ext_suspended flag is cleared by java_resume()
2388 while (is_ext_suspended()) {
2389 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2390 }
2391 }
2392
2393 return ret;
2394 }
2395
2396 #ifdef ASSERT
2397 // Verify the JavaThread has not yet been published in the Threads::list, and
2398 // hence doesn't need protection from concurrent access at this stage.
2399 void JavaThread::verify_not_published() {
2400 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2401 // since an unpublished JavaThread doesn't participate in the
2402 // Thread-SMR protocol for keeping a ThreadsList alive.
2403 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2404 }
2405 #endif
2406
2407 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2408 // progress or when _suspend_flags is non-zero.
2409 // Current thread needs to self-suspend if there is a suspend request and/or
2410 // block if a safepoint is in progress.
2411 // Async exception ISN'T checked.
2412 // Note only the ThreadInVMfromNative transition can call this function
2413 // directly and when thread state is _thread_in_native_trans
2414 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2415 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2416
2417 JavaThread *curJT = JavaThread::current();
2418 bool do_self_suspend = thread->is_external_suspend();
2419
2420 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2421
2422 // If JNIEnv proxies are allowed, don't self-suspend if the target
2423 // thread is not the current thread. In older versions of jdbx, jdbx
2424 // threads could call into the VM with another thread's JNIEnv so we
2425 // can be here operating on behalf of a suspended thread (4432884).
2426 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2427 JavaThreadState state = thread->thread_state();
2428
2429 // We mark this thread_blocked state as a suspend-equivalent so
2430 // that a caller to is_ext_suspend_completed() won't be confused.
2431 // The suspend-equivalent state is cleared by java_suspend_self().
2432 thread->set_suspend_equivalent();
2433
2434 // If the safepoint code sees the _thread_in_native_trans state, it will
2435 // wait until the thread changes to other thread state. There is no
2436 // guarantee on how soon we can obtain the SR_lock and complete the
2437 // self-suspend request. It would be a bad idea to let safepoint wait for
2438 // too long. Temporarily change the state to _thread_blocked to
2439 // let the VM thread know that this thread is ready for GC. The problem
2440 // of changing thread state is that safepoint could happen just after
2441 // java_suspend_self() returns after being resumed, and VM thread will
2442 // see the _thread_blocked state. We must check for safepoint
2443 // after restoring the state and make sure we won't leave while a safepoint
2444 // is in progress.
2445 thread->set_thread_state(_thread_blocked);
2446 thread->java_suspend_self();
2447 thread->set_thread_state(state);
2448
2449 InterfaceSupport::serialize_thread_state_with_handler(thread);
2450 }
2451
2452 SafepointMechanism::block_if_requested(curJT);
2453
2454 if (thread->is_deopt_suspend()) {
2455 thread->clear_deopt_suspend();
2456 RegisterMap map(thread, false);
2457 frame f = thread->last_frame();
2458 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2459 f = f.sender(&map);
2460 }
2461 if (f.id() == thread->must_deopt_id()) {
2462 thread->clear_must_deopt_id();
2463 f.deoptimize(thread);
2464 } else {
2465 fatal("missed deoptimization!");
2466 }
2467 }
2468 #if INCLUDE_TRACE
2469 if (thread->is_trace_suspend()) {
2470 TRACE_SUSPEND_THREAD(thread);
2471 }
2472 #endif
2473 }
2474
2475 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2476 // progress or when _suspend_flags is non-zero.
2477 // Current thread needs to self-suspend if there is a suspend request and/or
2478 // block if a safepoint is in progress.
2479 // Also check for pending async exception (not including unsafe access error).
2480 // Note only the native==>VM/Java barriers can call this function and when
2481 // thread state is _thread_in_native_trans.
2482 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2483 check_safepoint_and_suspend_for_native_trans(thread);
2484
2485 if (thread->has_async_exception()) {
2486 // We are in _thread_in_native_trans state, don't handle unsafe
2487 // access error since that may block.
2488 thread->check_and_handle_async_exceptions(false);
2489 }
2490 }
2491
2492 // This is a variant of the normal
2493 // check_special_condition_for_native_trans with slightly different
2494 // semantics for use by critical native wrappers. It does all the
2495 // normal checks but also performs the transition back into
2496 // thread_in_Java state. This is required so that critical natives
2497 // can potentially block and perform a GC if they are the last thread
2498 // exiting the GCLocker.
2499 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2500 check_special_condition_for_native_trans(thread);
2501
2502 // Finish the transition
2503 thread->set_thread_state(_thread_in_Java);
2504
2505 if (thread->do_critical_native_unlock()) {
2506 ThreadInVMfromJavaNoAsyncException tiv(thread);
2507 GCLocker::unlock_critical(thread);
2508 thread->clear_critical_native_unlock();
2509 }
2510 }
2511
2512 // We need to guarantee the Threads_lock here, since resumes are not
2513 // allowed during safepoint synchronization
2514 // Can only resume from an external suspension
2515 void JavaThread::java_resume() {
2516 assert_locked_or_safepoint(Threads_lock);
2517
2518 // Sanity check: thread is gone, has started exiting or the thread
2519 // was not externally suspended.
2520 ThreadsListHandle tlh;
2521 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2522 return;
2523 }
2524
2525 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2526
2527 clear_external_suspend();
2528
2529 if (is_ext_suspended()) {
2530 clear_ext_suspended();
2531 SR_lock()->notify_all();
2532 }
2533 }
2534
2535 size_t JavaThread::_stack_red_zone_size = 0;
2536 size_t JavaThread::_stack_yellow_zone_size = 0;
2537 size_t JavaThread::_stack_reserved_zone_size = 0;
2538 size_t JavaThread::_stack_shadow_zone_size = 0;
2539
2540 void JavaThread::create_stack_guard_pages() {
2541 if (!os::uses_stack_guard_pages() ||
2542 _stack_guard_state != stack_guard_unused ||
2543 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2544 log_info(os, thread)("Stack guard page creation for thread "
2545 UINTX_FORMAT " disabled", os::current_thread_id());
2546 return;
2547 }
2548 address low_addr = stack_end();
2549 size_t len = stack_guard_zone_size();
2550
2551 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2552 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2553
2554 int must_commit = os::must_commit_stack_guard_pages();
2555 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2556
2557 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2558 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2559 return;
2560 }
2561
2562 if (os::guard_memory((char *) low_addr, len)) {
2563 _stack_guard_state = stack_guard_enabled;
2564 } else {
2565 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2566 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2567 if (os::uncommit_memory((char *) low_addr, len)) {
2568 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2569 }
2570 return;
2571 }
2572
2573 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2574 PTR_FORMAT "-" PTR_FORMAT ".",
2575 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2576 }
2577
2578 void JavaThread::remove_stack_guard_pages() {
2579 assert(Thread::current() == this, "from different thread");
2580 if (_stack_guard_state == stack_guard_unused) return;
2581 address low_addr = stack_end();
2582 size_t len = stack_guard_zone_size();
2583
2584 if (os::must_commit_stack_guard_pages()) {
2585 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2586 _stack_guard_state = stack_guard_unused;
2587 } else {
2588 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2589 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2590 return;
2591 }
2592 } else {
2593 if (_stack_guard_state == stack_guard_unused) return;
2594 if (os::unguard_memory((char *) low_addr, len)) {
2595 _stack_guard_state = stack_guard_unused;
2596 } else {
2597 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2598 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2599 return;
2600 }
2601 }
2602
2603 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2604 PTR_FORMAT "-" PTR_FORMAT ".",
2605 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2606 }
2607
2608 void JavaThread::enable_stack_reserved_zone() {
2609 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2610 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2611
2612 // The base notation is from the stack's point of view, growing downward.
2613 // We need to adjust it to work correctly with guard_memory()
2614 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2615
2616 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2617 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2618
2619 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2620 _stack_guard_state = stack_guard_enabled;
2621 } else {
2622 warning("Attempt to guard stack reserved zone failed.");
2623 }
2624 enable_register_stack_guard();
2625 }
2626
2627 void JavaThread::disable_stack_reserved_zone() {
2628 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2629 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled");
2630
2631 // Simply return if called for a thread that does not use guard pages.
2632 if (_stack_guard_state == stack_guard_unused) return;
2633
2634 // The base notation is from the stack's point of view, growing downward.
2635 // We need to adjust it to work correctly with guard_memory()
2636 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2637
2638 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2639 _stack_guard_state = stack_guard_reserved_disabled;
2640 } else {
2641 warning("Attempt to unguard stack reserved zone failed.");
2642 }
2643 disable_register_stack_guard();
2644 }
2645
2646 void JavaThread::enable_stack_yellow_reserved_zone() {
2647 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2648 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2649
2650 // The base notation is from the stacks point of view, growing downward.
2651 // We need to adjust it to work correctly with guard_memory()
2652 address base = stack_red_zone_base();
2653
2654 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2655 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2656
2657 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2658 _stack_guard_state = stack_guard_enabled;
2659 } else {
2660 warning("Attempt to guard stack yellow zone failed.");
2661 }
2662 enable_register_stack_guard();
2663 }
2664
2665 void JavaThread::disable_stack_yellow_reserved_zone() {
2666 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2667 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2668
2669 // Simply return if called for a thread that does not use guard pages.
2670 if (_stack_guard_state == stack_guard_unused) return;
2671
2672 // The base notation is from the stacks point of view, growing downward.
2673 // We need to adjust it to work correctly with guard_memory()
2674 address base = stack_red_zone_base();
2675
2676 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2677 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2678 } else {
2679 warning("Attempt to unguard stack yellow zone failed.");
2680 }
2681 disable_register_stack_guard();
2682 }
2683
2684 void JavaThread::enable_stack_red_zone() {
2685 // The base notation is from the stacks point of view, growing downward.
2686 // We need to adjust it to work correctly with guard_memory()
2687 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2688 address base = stack_red_zone_base() - stack_red_zone_size();
2689
2690 guarantee(base < stack_base(), "Error calculating stack red zone");
2691 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2692
2693 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2694 warning("Attempt to guard stack red zone failed.");
2695 }
2696 }
2697
2698 void JavaThread::disable_stack_red_zone() {
2699 // The base notation is from the stacks point of view, growing downward.
2700 // We need to adjust it to work correctly with guard_memory()
2701 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2702 address base = stack_red_zone_base() - stack_red_zone_size();
2703 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2704 warning("Attempt to unguard stack red zone failed.");
2705 }
2706 }
2707
2708 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2709 // ignore is there is no stack
2710 if (!has_last_Java_frame()) return;
2711 // traverse the stack frames. Starts from top frame.
2712 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2713 frame* fr = fst.current();
2714 f(fr, fst.register_map());
2715 }
2716 }
2717
2718
2719 #ifndef PRODUCT
2720 // Deoptimization
2721 // Function for testing deoptimization
2722 void JavaThread::deoptimize() {
2723 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2724 StackFrameStream fst(this, UseBiasedLocking);
2725 bool deopt = false; // Dump stack only if a deopt actually happens.
2726 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2727 // Iterate over all frames in the thread and deoptimize
2728 for (; !fst.is_done(); fst.next()) {
2729 if (fst.current()->can_be_deoptimized()) {
2730
2731 if (only_at) {
2732 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2733 // consists of comma or carriage return separated numbers so
2734 // search for the current bci in that string.
2735 address pc = fst.current()->pc();
2736 nmethod* nm = (nmethod*) fst.current()->cb();
2737 ScopeDesc* sd = nm->scope_desc_at(pc);
2738 char buffer[8];
2739 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2740 size_t len = strlen(buffer);
2741 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2742 while (found != NULL) {
2743 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2744 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2745 // Check that the bci found is bracketed by terminators.
2746 break;
2747 }
2748 found = strstr(found + 1, buffer);
2749 }
2750 if (!found) {
2751 continue;
2752 }
2753 }
2754
2755 if (DebugDeoptimization && !deopt) {
2756 deopt = true; // One-time only print before deopt
2757 tty->print_cr("[BEFORE Deoptimization]");
2758 trace_frames();
2759 trace_stack();
2760 }
2761 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2762 }
2763 }
2764
2765 if (DebugDeoptimization && deopt) {
2766 tty->print_cr("[AFTER Deoptimization]");
2767 trace_frames();
2768 }
2769 }
2770
2771
2772 // Make zombies
2773 void JavaThread::make_zombies() {
2774 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2775 if (fst.current()->can_be_deoptimized()) {
2776 // it is a Java nmethod
2777 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2778 nm->make_not_entrant();
2779 }
2780 }
2781 }
2782 #endif // PRODUCT
2783
2784
2785 void JavaThread::deoptimized_wrt_marked_nmethods() {
2786 if (!has_last_Java_frame()) return;
2787 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2788 StackFrameStream fst(this, UseBiasedLocking);
2789 for (; !fst.is_done(); fst.next()) {
2790 if (fst.current()->should_be_deoptimized()) {
2791 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2792 }
2793 }
2794 }
2795
2796
2797 // If the caller is a NamedThread, then remember, in the current scope,
2798 // the given JavaThread in its _processed_thread field.
2799 class RememberProcessedThread: public StackObj {
2800 NamedThread* _cur_thr;
2801 public:
2802 RememberProcessedThread(JavaThread* jthr) {
2803 Thread* thread = Thread::current();
2804 if (thread->is_Named_thread()) {
2805 _cur_thr = (NamedThread *)thread;
2806 _cur_thr->set_processed_thread(jthr);
2807 } else {
2808 _cur_thr = NULL;
2809 }
2810 }
2811
2812 ~RememberProcessedThread() {
2813 if (_cur_thr) {
2814 _cur_thr->set_processed_thread(NULL);
2815 }
2816 }
2817 };
2818
2819 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2820 // Verify that the deferred card marks have been flushed.
2821 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2822
2823 // Traverse the GCHandles
2824 Thread::oops_do(f, cf);
2825
2826 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);)
2827
2828 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2829 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2830
2831 if (has_last_Java_frame()) {
2832 // Record JavaThread to GC thread
2833 RememberProcessedThread rpt(this);
2834
2835 // Traverse the privileged stack
2836 if (_privileged_stack_top != NULL) {
2837 _privileged_stack_top->oops_do(f);
2838 }
2839
2840 // traverse the registered growable array
2841 if (_array_for_gc != NULL) {
2842 for (int index = 0; index < _array_for_gc->length(); index++) {
2843 f->do_oop(_array_for_gc->adr_at(index));
2844 }
2845 }
2846
2847 // Traverse the monitor chunks
2848 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2849 chunk->oops_do(f);
2850 }
2851
2852 // Traverse the execution stack
2853 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2854 fst.current()->oops_do(f, cf, fst.register_map());
2855 }
2856 }
2857
2858 // callee_target is never live across a gc point so NULL it here should
2859 // it still contain a methdOop.
2860
2861 set_callee_target(NULL);
2862
2863 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2864 // If we have deferred set_locals there might be oops waiting to be
2865 // written
2866 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2867 if (list != NULL) {
2868 for (int i = 0; i < list->length(); i++) {
2869 list->at(i)->oops_do(f);
2870 }
2871 }
2872
2873 // Traverse instance variables at the end since the GC may be moving things
2874 // around using this function
2875 f->do_oop((oop*) &_threadObj);
2876 f->do_oop((oop*) &_vm_result);
2877 f->do_oop((oop*) &_exception_oop);
2878 f->do_oop((oop*) &_pending_async_exception);
2879
2880 if (jvmti_thread_state() != NULL) {
2881 jvmti_thread_state()->oops_do(f);
2882 }
2883 }
2884
2885 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2886 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2887 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2888
2889 if (has_last_Java_frame()) {
2890 // Traverse the execution stack
2891 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2892 fst.current()->nmethods_do(cf);
2893 }
2894 }
2895 }
2896
2897 void JavaThread::metadata_do(void f(Metadata*)) {
2898 if (has_last_Java_frame()) {
2899 // Traverse the execution stack to call f() on the methods in the stack
2900 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2901 fst.current()->metadata_do(f);
2902 }
2903 } else if (is_Compiler_thread()) {
2904 // need to walk ciMetadata in current compile tasks to keep alive.
2905 CompilerThread* ct = (CompilerThread*)this;
2906 if (ct->env() != NULL) {
2907 ct->env()->metadata_do(f);
2908 }
2909 CompileTask* task = ct->task();
2910 if (task != NULL) {
2911 task->metadata_do(f);
2912 }
2913 }
2914 }
2915
2916 // Printing
2917 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2918 switch (_thread_state) {
2919 case _thread_uninitialized: return "_thread_uninitialized";
2920 case _thread_new: return "_thread_new";
2921 case _thread_new_trans: return "_thread_new_trans";
2922 case _thread_in_native: return "_thread_in_native";
2923 case _thread_in_native_trans: return "_thread_in_native_trans";
2924 case _thread_in_vm: return "_thread_in_vm";
2925 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2926 case _thread_in_Java: return "_thread_in_Java";
2927 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2928 case _thread_blocked: return "_thread_blocked";
2929 case _thread_blocked_trans: return "_thread_blocked_trans";
2930 default: return "unknown thread state";
2931 }
2932 }
2933
2934 #ifndef PRODUCT
2935 void JavaThread::print_thread_state_on(outputStream *st) const {
2936 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2937 };
2938 void JavaThread::print_thread_state() const {
2939 print_thread_state_on(tty);
2940 }
2941 #endif // PRODUCT
2942
2943 // Called by Threads::print() for VM_PrintThreads operation
2944 void JavaThread::print_on(outputStream *st) const {
2945 st->print_raw("\"");
2946 st->print_raw(get_thread_name());
2947 st->print_raw("\" ");
2948 oop thread_oop = threadObj();
2949 if (thread_oop != NULL) {
2950 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
2951 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2952 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2953 }
2954 Thread::print_on(st);
2955 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2956 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2957 if (thread_oop != NULL) {
2958 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2959 }
2960 #ifndef PRODUCT
2961 print_thread_state_on(st);
2962 _safepoint_state->print_on(st);
2963 #endif // PRODUCT
2964 if (is_Compiler_thread()) {
2965 CompileTask *task = ((CompilerThread*)this)->task();
2966 if (task != NULL) {
2967 st->print(" Compiling: ");
2968 task->print(st, NULL, true, false);
2969 } else {
2970 st->print(" No compile task");
2971 }
2972 st->cr();
2973 }
2974 }
2975
2976 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
2977 st->print("%s", get_thread_name_string(buf, buflen));
2978 }
2979
2980 // Called by fatal error handler. The difference between this and
2981 // JavaThread::print() is that we can't grab lock or allocate memory.
2982 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2983 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2984 oop thread_obj = threadObj();
2985 if (thread_obj != NULL) {
2986 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2987 }
2988 st->print(" [");
2989 st->print("%s", _get_thread_state_name(_thread_state));
2990 if (osthread()) {
2991 st->print(", id=%d", osthread()->thread_id());
2992 }
2993 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2994 p2i(stack_end()), p2i(stack_base()));
2995 st->print("]");
2996
2997 if (_threads_hazard_ptr != NULL) {
2998 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
2999 }
3000 if (_nested_threads_hazard_ptr != NULL) {
3001 print_nested_threads_hazard_ptrs_on(st);
3002 }
3003 return;
3004 }
3005
3006 // Verification
3007
3008 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3009
3010 void JavaThread::verify() {
3011 // Verify oops in the thread.
3012 oops_do(&VerifyOopClosure::verify_oop, NULL);
3013
3014 // Verify the stack frames.
3015 frames_do(frame_verify);
3016 }
3017
3018 // CR 6300358 (sub-CR 2137150)
3019 // Most callers of this method assume that it can't return NULL but a
3020 // thread may not have a name whilst it is in the process of attaching to
3021 // the VM - see CR 6412693, and there are places where a JavaThread can be
3022 // seen prior to having it's threadObj set (eg JNI attaching threads and
3023 // if vm exit occurs during initialization). These cases can all be accounted
3024 // for such that this method never returns NULL.
3025 const char* JavaThread::get_thread_name() const {
3026 #ifdef ASSERT
3027 // early safepoints can hit while current thread does not yet have TLS
3028 if (!SafepointSynchronize::is_at_safepoint()) {
3029 Thread *cur = Thread::current();
3030 if (!(cur->is_Java_thread() && cur == this)) {
3031 // Current JavaThreads are allowed to get their own name without
3032 // the Threads_lock.
3033 assert_locked_or_safepoint(Threads_lock);
3034 }
3035 }
3036 #endif // ASSERT
3037 return get_thread_name_string();
3038 }
3039
3040 // Returns a non-NULL representation of this thread's name, or a suitable
3041 // descriptive string if there is no set name
3042 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3043 const char* name_str;
3044 oop thread_obj = threadObj();
3045 if (thread_obj != NULL) {
3046 oop name = java_lang_Thread::name(thread_obj);
3047 if (name != NULL) {
3048 if (buf == NULL) {
3049 name_str = java_lang_String::as_utf8_string(name);
3050 } else {
3051 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3052 }
3053 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3054 name_str = "<no-name - thread is attaching>";
3055 } else {
3056 name_str = Thread::name();
3057 }
3058 } else {
3059 name_str = Thread::name();
3060 }
3061 assert(name_str != NULL, "unexpected NULL thread name");
3062 return name_str;
3063 }
3064
3065
3066 const char* JavaThread::get_threadgroup_name() const {
3067 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3068 oop thread_obj = threadObj();
3069 if (thread_obj != NULL) {
3070 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3071 if (thread_group != NULL) {
3072 // ThreadGroup.name can be null
3073 return java_lang_ThreadGroup::name(thread_group);
3074 }
3075 }
3076 return NULL;
3077 }
3078
3079 const char* JavaThread::get_parent_name() const {
3080 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3081 oop thread_obj = threadObj();
3082 if (thread_obj != NULL) {
3083 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3084 if (thread_group != NULL) {
3085 oop parent = java_lang_ThreadGroup::parent(thread_group);
3086 if (parent != NULL) {
3087 // ThreadGroup.name can be null
3088 return java_lang_ThreadGroup::name(parent);
3089 }
3090 }
3091 }
3092 return NULL;
3093 }
3094
3095 ThreadPriority JavaThread::java_priority() const {
3096 oop thr_oop = threadObj();
3097 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3098 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3099 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3100 return priority;
3101 }
3102
3103 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3104
3105 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3106 // Link Java Thread object <-> C++ Thread
3107
3108 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3109 // and put it into a new Handle. The Handle "thread_oop" can then
3110 // be used to pass the C++ thread object to other methods.
3111
3112 // Set the Java level thread object (jthread) field of the
3113 // new thread (a JavaThread *) to C++ thread object using the
3114 // "thread_oop" handle.
3115
3116 // Set the thread field (a JavaThread *) of the
3117 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3118
3119 Handle thread_oop(Thread::current(),
3120 JNIHandles::resolve_non_null(jni_thread));
3121 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3122 "must be initialized");
3123 set_threadObj(thread_oop());
3124 java_lang_Thread::set_thread(thread_oop(), this);
3125
3126 if (prio == NoPriority) {
3127 prio = java_lang_Thread::priority(thread_oop());
3128 assert(prio != NoPriority, "A valid priority should be present");
3129 }
3130
3131 // Push the Java priority down to the native thread; needs Threads_lock
3132 Thread::set_priority(this, prio);
3133
3134 // Add the new thread to the Threads list and set it in motion.
3135 // We must have threads lock in order to call Threads::add.
3136 // It is crucial that we do not block before the thread is
3137 // added to the Threads list for if a GC happens, then the java_thread oop
3138 // will not be visited by GC.
3139 Threads::add(this);
3140 }
3141
3142 oop JavaThread::current_park_blocker() {
3143 // Support for JSR-166 locks
3144 oop thread_oop = threadObj();
3145 if (thread_oop != NULL &&
3146 JDK_Version::current().supports_thread_park_blocker()) {
3147 return java_lang_Thread::park_blocker(thread_oop);
3148 }
3149 return NULL;
3150 }
3151
3152
3153 void JavaThread::print_stack_on(outputStream* st) {
3154 if (!has_last_Java_frame()) return;
3155 ResourceMark rm;
3156 HandleMark hm;
3157
3158 RegisterMap reg_map(this);
3159 vframe* start_vf = last_java_vframe(®_map);
3160 int count = 0;
3161 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3162 if (f->is_java_frame()) {
3163 javaVFrame* jvf = javaVFrame::cast(f);
3164 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3165
3166 // Print out lock information
3167 if (JavaMonitorsInStackTrace) {
3168 jvf->print_lock_info_on(st, count);
3169 }
3170 } else {
3171 // Ignore non-Java frames
3172 }
3173
3174 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3175 count++;
3176 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3177 }
3178 }
3179
3180
3181 // JVMTI PopFrame support
3182 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3183 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3184 if (in_bytes(size_in_bytes) != 0) {
3185 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3186 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3187 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3188 }
3189 }
3190
3191 void* JavaThread::popframe_preserved_args() {
3192 return _popframe_preserved_args;
3193 }
3194
3195 ByteSize JavaThread::popframe_preserved_args_size() {
3196 return in_ByteSize(_popframe_preserved_args_size);
3197 }
3198
3199 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3200 int sz = in_bytes(popframe_preserved_args_size());
3201 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3202 return in_WordSize(sz / wordSize);
3203 }
3204
3205 void JavaThread::popframe_free_preserved_args() {
3206 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3207 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3208 _popframe_preserved_args = NULL;
3209 _popframe_preserved_args_size = 0;
3210 }
3211
3212 #ifndef PRODUCT
3213
3214 void JavaThread::trace_frames() {
3215 tty->print_cr("[Describe stack]");
3216 int frame_no = 1;
3217 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3218 tty->print(" %d. ", frame_no++);
3219 fst.current()->print_value_on(tty, this);
3220 tty->cr();
3221 }
3222 }
3223
3224 class PrintAndVerifyOopClosure: public OopClosure {
3225 protected:
3226 template <class T> inline void do_oop_work(T* p) {
3227 oop obj = RawAccess<>::oop_load(p);
3228 if (obj == NULL) return;
3229 tty->print(INTPTR_FORMAT ": ", p2i(p));
3230 if (oopDesc::is_oop_or_null(obj)) {
3231 if (obj->is_objArray()) {
3232 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3233 } else {
3234 obj->print();
3235 }
3236 } else {
3237 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3238 }
3239 tty->cr();
3240 }
3241 public:
3242 virtual void do_oop(oop* p) { do_oop_work(p); }
3243 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3244 };
3245
3246
3247 static void oops_print(frame* f, const RegisterMap *map) {
3248 PrintAndVerifyOopClosure print;
3249 f->print_value();
3250 f->oops_do(&print, NULL, (RegisterMap*)map);
3251 }
3252
3253 // Print our all the locations that contain oops and whether they are
3254 // valid or not. This useful when trying to find the oldest frame
3255 // where an oop has gone bad since the frame walk is from youngest to
3256 // oldest.
3257 void JavaThread::trace_oops() {
3258 tty->print_cr("[Trace oops]");
3259 frames_do(oops_print);
3260 }
3261
3262
3263 #ifdef ASSERT
3264 // Print or validate the layout of stack frames
3265 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3266 ResourceMark rm;
3267 PRESERVE_EXCEPTION_MARK;
3268 FrameValues values;
3269 int frame_no = 0;
3270 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3271 fst.current()->describe(values, ++frame_no);
3272 if (depth == frame_no) break;
3273 }
3274 if (validate_only) {
3275 values.validate();
3276 } else {
3277 tty->print_cr("[Describe stack layout]");
3278 values.print(this);
3279 }
3280 }
3281 #endif
3282
3283 void JavaThread::trace_stack_from(vframe* start_vf) {
3284 ResourceMark rm;
3285 int vframe_no = 1;
3286 for (vframe* f = start_vf; f; f = f->sender()) {
3287 if (f->is_java_frame()) {
3288 javaVFrame::cast(f)->print_activation(vframe_no++);
3289 } else {
3290 f->print();
3291 }
3292 if (vframe_no > StackPrintLimit) {
3293 tty->print_cr("...<more frames>...");
3294 return;
3295 }
3296 }
3297 }
3298
3299
3300 void JavaThread::trace_stack() {
3301 if (!has_last_Java_frame()) return;
3302 ResourceMark rm;
3303 HandleMark hm;
3304 RegisterMap reg_map(this);
3305 trace_stack_from(last_java_vframe(®_map));
3306 }
3307
3308
3309 #endif // PRODUCT
3310
3311
3312 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3313 assert(reg_map != NULL, "a map must be given");
3314 frame f = last_frame();
3315 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3316 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3317 }
3318 return NULL;
3319 }
3320
3321
3322 Klass* JavaThread::security_get_caller_class(int depth) {
3323 vframeStream vfst(this);
3324 vfst.security_get_caller_frame(depth);
3325 if (!vfst.at_end()) {
3326 return vfst.method()->method_holder();
3327 }
3328 return NULL;
3329 }
3330
3331 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3332 assert(thread->is_Compiler_thread(), "must be compiler thread");
3333 CompileBroker::compiler_thread_loop();
3334 }
3335
3336 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3337 NMethodSweeper::sweeper_loop();
3338 }
3339
3340 // Create a CompilerThread
3341 CompilerThread::CompilerThread(CompileQueue* queue,
3342 CompilerCounters* counters)
3343 : JavaThread(&compiler_thread_entry) {
3344 _env = NULL;
3345 _log = NULL;
3346 _task = NULL;
3347 _queue = queue;
3348 _counters = counters;
3349 _buffer_blob = NULL;
3350 _compiler = NULL;
3351
3352 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3353 resource_area()->bias_to(mtCompiler);
3354
3355 #ifndef PRODUCT
3356 _ideal_graph_printer = NULL;
3357 #endif
3358 }
3359
3360 bool CompilerThread::can_call_java() const {
3361 return _compiler != NULL && _compiler->is_jvmci();
3362 }
3363
3364 // Create sweeper thread
3365 CodeCacheSweeperThread::CodeCacheSweeperThread()
3366 : JavaThread(&sweeper_thread_entry) {
3367 _scanned_compiled_method = NULL;
3368 }
3369
3370 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3371 JavaThread::oops_do(f, cf);
3372 if (_scanned_compiled_method != NULL && cf != NULL) {
3373 // Safepoints can occur when the sweeper is scanning an nmethod so
3374 // process it here to make sure it isn't unloaded in the middle of
3375 // a scan.
3376 cf->do_code_blob(_scanned_compiled_method);
3377 }
3378 }
3379
3380 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3381 JavaThread::nmethods_do(cf);
3382 if (_scanned_compiled_method != NULL && cf != NULL) {
3383 // Safepoints can occur when the sweeper is scanning an nmethod so
3384 // process it here to make sure it isn't unloaded in the middle of
3385 // a scan.
3386 cf->do_code_blob(_scanned_compiled_method);
3387 }
3388 }
3389
3390
3391 // ======= Threads ========
3392
3393 // The Threads class links together all active threads, and provides
3394 // operations over all threads. It is protected by the Threads_lock,
3395 // which is also used in other global contexts like safepointing.
3396 // ThreadsListHandles are used to safely perform operations on one
3397 // or more threads without the risk of the thread exiting during the
3398 // operation.
3399 //
3400 // Note: The Threads_lock is currently more widely used than we
3401 // would like. We are actively migrating Threads_lock uses to other
3402 // mechanisms in order to reduce Threads_lock contention.
3403
3404 JavaThread* Threads::_thread_list = NULL;
3405 int Threads::_number_of_threads = 0;
3406 int Threads::_number_of_non_daemon_threads = 0;
3407 int Threads::_return_code = 0;
3408 int Threads::_thread_claim_parity = 0;
3409 size_t JavaThread::_stack_size_at_create = 0;
3410
3411 #ifdef ASSERT
3412 bool Threads::_vm_complete = false;
3413 #endif
3414
3415 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3416 Prefetch::read((void*)addr, prefetch_interval);
3417 return *addr;
3418 }
3419
3420 // Possibly the ugliest for loop the world has seen. C++ does not allow
3421 // multiple types in the declaration section of the for loop. In this case
3422 // we are only dealing with pointers and hence can cast them. It looks ugly
3423 // but macros are ugly and therefore it's fine to make things absurdly ugly.
3424 #define DO_JAVA_THREADS(LIST, X) \
3425 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3426 *MACRO_list = (JavaThread*)(LIST), \
3427 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3428 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3429 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3430 MACRO_current_p != MACRO_end; \
3431 MACRO_current_p++, \
3432 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3433
3434 // All JavaThreads
3435 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3436
3437 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3438 void Threads::threads_do(ThreadClosure* tc) {
3439 assert_locked_or_safepoint(Threads_lock);
3440 // ALL_JAVA_THREADS iterates through all JavaThreads
3441 ALL_JAVA_THREADS(p) {
3442 tc->do_thread(p);
3443 }
3444 // Someday we could have a table or list of all non-JavaThreads.
3445 // For now, just manually iterate through them.
3446 tc->do_thread(VMThread::vm_thread());
3447 Universe::heap()->gc_threads_do(tc);
3448 WatcherThread *wt = WatcherThread::watcher_thread();
3449 // Strictly speaking, the following NULL check isn't sufficient to make sure
3450 // the data for WatcherThread is still valid upon being examined. However,
3451 // considering that WatchThread terminates when the VM is on the way to
3452 // exit at safepoint, the chance of the above is extremely small. The right
3453 // way to prevent termination of WatcherThread would be to acquire
3454 // Terminator_lock, but we can't do that without violating the lock rank
3455 // checking in some cases.
3456 if (wt != NULL) {
3457 tc->do_thread(wt);
3458 }
3459
3460 // If CompilerThreads ever become non-JavaThreads, add them here
3461 }
3462
3463 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3464 int cp = Threads::thread_claim_parity();
3465 ALL_JAVA_THREADS(p) {
3466 if (p->claim_oops_do(is_par, cp)) {
3467 tc->do_thread(p);
3468 }
3469 }
3470 VMThread* vmt = VMThread::vm_thread();
3471 if (vmt->claim_oops_do(is_par, cp)) {
3472 tc->do_thread(vmt);
3473 }
3474 }
3475
3476 // The system initialization in the library has three phases.
3477 //
3478 // Phase 1: java.lang.System class initialization
3479 // java.lang.System is a primordial class loaded and initialized
3480 // by the VM early during startup. java.lang.System.<clinit>
3481 // only does registerNatives and keeps the rest of the class
3482 // initialization work later until thread initialization completes.
3483 //
3484 // System.initPhase1 initializes the system properties, the static
3485 // fields in, out, and err. Set up java signal handlers, OS-specific
3486 // system settings, and thread group of the main thread.
3487 static void call_initPhase1(TRAPS) {
3488 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3489 JavaValue result(T_VOID);
3490 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3491 vmSymbols::void_method_signature(), CHECK);
3492 }
3493
3494 // Phase 2. Module system initialization
3495 // This will initialize the module system. Only java.base classes
3496 // can be loaded until phase 2 completes.
3497 //
3498 // Call System.initPhase2 after the compiler initialization and jsr292
3499 // classes get initialized because module initialization runs a lot of java
3500 // code, that for performance reasons, should be compiled. Also, this will
3501 // enable the startup code to use lambda and other language features in this
3502 // phase and onward.
3503 //
3504 // After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3505 static void call_initPhase2(TRAPS) {
3506 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3507
3508 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3509
3510 JavaValue result(T_INT);
3511 JavaCallArguments args;
3512 args.push_int(DisplayVMOutputToStderr);
3513 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3514 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3515 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3516 if (result.get_jint() != JNI_OK) {
3517 vm_exit_during_initialization(); // no message or exception
3518 }
3519
3520 universe_post_module_init();
3521 }
3522
3523 // Phase 3. final setup - set security manager, system class loader and TCCL
3524 //
3525 // This will instantiate and set the security manager, set the system class
3526 // loader as well as the thread context class loader. The security manager
3527 // and system class loader may be a custom class loaded from -Xbootclasspath/a,
3528 // other modules or the application's classpath.
3529 static void call_initPhase3(TRAPS) {
3530 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3531 JavaValue result(T_VOID);
3532 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3533 vmSymbols::void_method_signature(), CHECK);
3534 }
3535
3536 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3537 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3538
3539 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3540 create_vm_init_libraries();
3541 }
3542
3543 initialize_class(vmSymbols::java_lang_String(), CHECK);
3544
3545 // Inject CompactStrings value after the static initializers for String ran.
3546 java_lang_String::set_compact_strings(CompactStrings);
3547
3548 // Initialize java_lang.System (needed before creating the thread)
3549 initialize_class(vmSymbols::java_lang_System(), CHECK);
3550 // The VM creates & returns objects of this class. Make sure it's initialized.
3551 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3552 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3553 Handle thread_group = create_initial_thread_group(CHECK);
3554 Universe::set_main_thread_group(thread_group());
3555 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3556 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3557 main_thread->set_threadObj(thread_object);
3558 // Set thread status to running since main thread has
3559 // been started and running.
3560 java_lang_Thread::set_thread_status(thread_object,
3561 java_lang_Thread::RUNNABLE);
3562
3563 // The VM creates objects of this class.
3564 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3565
3566 // The VM preresolves methods to these classes. Make sure that they get initialized
3567 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3568 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3569
3570 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3571 call_initPhase1(CHECK);
3572
3573 // get the Java runtime name after java.lang.System is initialized
3574 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3575 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3576
3577 // an instance of OutOfMemory exception has been allocated earlier
3578 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3579 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3580 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3581 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3582 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3583 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3584 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3585 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3586 }
3587
3588 void Threads::initialize_jsr292_core_classes(TRAPS) {
3589 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3590
3591 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3592 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3593 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3594 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3595 }
3596
3597 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3598 extern void JDK_Version_init();
3599
3600 // Preinitialize version info.
3601 VM_Version::early_initialize();
3602
3603 // Check version
3604 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3605
3606 // Initialize library-based TLS
3607 ThreadLocalStorage::init();
3608
3609 // Initialize the output stream module
3610 ostream_init();
3611
3612 // Process java launcher properties.
3613 Arguments::process_sun_java_launcher_properties(args);
3614
3615 // Initialize the os module
3616 os::init();
3617
3618 // Record VM creation timing statistics
3619 TraceVmCreationTime create_vm_timer;
3620 create_vm_timer.start();
3621
3622 // Initialize system properties.
3623 Arguments::init_system_properties();
3624
3625 // So that JDK version can be used as a discriminator when parsing arguments
3626 JDK_Version_init();
3627
3628 // Update/Initialize System properties after JDK version number is known
3629 Arguments::init_version_specific_system_properties();
3630
3631 // Make sure to initialize log configuration *before* parsing arguments
3632 LogConfiguration::initialize(create_vm_timer.begin_time());
3633
3634 // Parse arguments
3635 // Note: this internally calls os::init_container_support()
3636 jint parse_result = Arguments::parse(args);
3637 if (parse_result != JNI_OK) return parse_result;
3638
3639 os::init_before_ergo();
3640
3641 jint ergo_result = Arguments::apply_ergo();
3642 if (ergo_result != JNI_OK) return ergo_result;
3643
3644 // Final check of all ranges after ergonomics which may change values.
3645 if (!CommandLineFlagRangeList::check_ranges()) {
3646 return JNI_EINVAL;
3647 }
3648
3649 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3650 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo);
3651 if (!constraint_result) {
3652 return JNI_EINVAL;
3653 }
3654
3655 CommandLineFlagWriteableList::mark_startup();
3656
3657 if (PauseAtStartup) {
3658 os::pause();
3659 }
3660
3661 HOTSPOT_VM_INIT_BEGIN();
3662
3663 // Timing (must come after argument parsing)
3664 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3665
3666 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3667 // Initialize assert poison page mechanism.
3668 if (ShowRegistersOnAssert) {
3669 initialize_assert_poison();
3670 }
3671 #endif // CAN_SHOW_REGISTERS_ON_ASSERT
3672
3673 // Initialize the os module after parsing the args
3674 jint os_init_2_result = os::init_2();
3675 if (os_init_2_result != JNI_OK) return os_init_2_result;
3676
3677 SafepointMechanism::initialize();
3678
3679 jint adjust_after_os_result = Arguments::adjust_after_os();
3680 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3681
3682 // Initialize output stream logging
3683 ostream_init_log();
3684
3685 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3686 // Must be before create_vm_init_agents()
3687 if (Arguments::init_libraries_at_startup()) {
3688 convert_vm_init_libraries_to_agents();
3689 }
3690
3691 // Launch -agentlib/-agentpath and converted -Xrun agents
3692 if (Arguments::init_agents_at_startup()) {
3693 create_vm_init_agents();
3694 }
3695
3696 // Initialize Threads state
3697 _thread_list = NULL;
3698 _number_of_threads = 0;
3699 _number_of_non_daemon_threads = 0;
3700
3701 // Initialize global data structures and create system classes in heap
3702 vm_init_globals();
3703
3704 #if INCLUDE_JVMCI
3705 if (JVMCICounterSize > 0) {
3706 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal);
3707 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3708 } else {
3709 JavaThread::_jvmci_old_thread_counters = NULL;
3710 }
3711 #endif // INCLUDE_JVMCI
3712
3713 // Attach the main thread to this os thread
3714 JavaThread* main_thread = new JavaThread();
3715 main_thread->set_thread_state(_thread_in_vm);
3716 main_thread->initialize_thread_current();
3717 // must do this before set_active_handles
3718 main_thread->record_stack_base_and_size();
3719 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3720
3721 if (!main_thread->set_as_starting_thread()) {
3722 vm_shutdown_during_initialization(
3723 "Failed necessary internal allocation. Out of swap space");
3724 main_thread->smr_delete();
3725 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3726 return JNI_ENOMEM;
3727 }
3728
3729 // Enable guard page *after* os::create_main_thread(), otherwise it would
3730 // crash Linux VM, see notes in os_linux.cpp.
3731 main_thread->create_stack_guard_pages();
3732
3733 // Initialize Java-Level synchronization subsystem
3734 ObjectMonitor::Initialize();
3735
3736 // Initialize global modules
3737 jint status = init_globals();
3738 if (status != JNI_OK) {
3739 main_thread->smr_delete();
3740 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3741 return status;
3742 }
3743
3744 if (TRACE_INITIALIZE() != JNI_OK) {
3745 vm_exit_during_initialization("Failed to initialize tracing backend");
3746 }
3747
3748 // Should be done after the heap is fully created
3749 main_thread->cache_global_variables();
3750
3751 HandleMark hm;
3752
3753 { MutexLocker mu(Threads_lock);
3754 Threads::add(main_thread);
3755 }
3756
3757 // Any JVMTI raw monitors entered in onload will transition into
3758 // real raw monitor. VM is setup enough here for raw monitor enter.
3759 JvmtiExport::transition_pending_onload_raw_monitors();
3760
3761 // Create the VMThread
3762 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3763
3764 VMThread::create();
3765 Thread* vmthread = VMThread::vm_thread();
3766
3767 if (!os::create_thread(vmthread, os::vm_thread)) {
3768 vm_exit_during_initialization("Cannot create VM thread. "
3769 "Out of system resources.");
3770 }
3771
3772 // Wait for the VM thread to become ready, and VMThread::run to initialize
3773 // Monitors can have spurious returns, must always check another state flag
3774 {
3775 MutexLocker ml(Notify_lock);
3776 os::start_thread(vmthread);
3777 while (vmthread->active_handles() == NULL) {
3778 Notify_lock->wait();
3779 }
3780 }
3781 }
3782
3783 assert(Universe::is_fully_initialized(), "not initialized");
3784 if (VerifyDuringStartup) {
3785 // Make sure we're starting with a clean slate.
3786 VM_Verify verify_op;
3787 VMThread::execute(&verify_op);
3788 }
3789
3790 Thread* THREAD = Thread::current();
3791
3792 // Always call even when there are not JVMTI environments yet, since environments
3793 // may be attached late and JVMTI must track phases of VM execution
3794 JvmtiExport::enter_early_start_phase();
3795
3796 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3797 JvmtiExport::post_early_vm_start();
3798
3799 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3800
3801 // We need this for ClassDataSharing - the initial vm.info property is set
3802 // with the default value of CDS "sharing" which may be reset through
3803 // command line options.
3804 reset_vm_info_property(CHECK_JNI_ERR);
3805
3806 quicken_jni_functions();
3807
3808 // No more stub generation allowed after that point.
3809 StubCodeDesc::freeze();
3810
3811 // Set flag that basic initialization has completed. Used by exceptions and various
3812 // debug stuff, that does not work until all basic classes have been initialized.
3813 set_init_completed();
3814
3815 LogConfiguration::post_initialize();
3816 Metaspace::post_initialize();
3817
3818 HOTSPOT_VM_INIT_END();
3819
3820 // record VM initialization completion time
3821 #if INCLUDE_MANAGEMENT
3822 Management::record_vm_init_completed();
3823 #endif // INCLUDE_MANAGEMENT
3824
3825 // Signal Dispatcher needs to be started before VMInit event is posted
3826 os::signal_init(CHECK_JNI_ERR);
3827
3828 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3829 if (!DisableAttachMechanism) {
3830 AttachListener::vm_start();
3831 if (StartAttachListener || AttachListener::init_at_startup()) {
3832 AttachListener::init();
3833 }
3834 }
3835
3836 // Launch -Xrun agents
3837 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3838 // back-end can launch with -Xdebug -Xrunjdwp.
3839 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3840 create_vm_init_libraries();
3841 }
3842
3843 if (CleanChunkPoolAsync) {
3844 Chunk::start_chunk_pool_cleaner_task();
3845 }
3846
3847 // initialize compiler(s)
3848 #if defined(COMPILER1) || COMPILER2_OR_JVMCI
3849 #if INCLUDE_JVMCI
3850 bool force_JVMCI_intialization = false;
3851 if (EnableJVMCI) {
3852 // Initialize JVMCI eagerly when it is explicitly requested.
3853 // Or when JVMCIPrintProperties is enabled.
3854 // The JVMCI Java initialization code will read this flag and
3855 // do the printing if it's set.
3856 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties;
3857
3858 if (!force_JVMCI_intialization) {
3859 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
3860 // compilations via JVMCI will not actually block until JVMCI is initialized.
3861 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
3862 }
3863 }
3864 #endif
3865 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
3866 // Postpone completion of compiler initialization to after JVMCI
3867 // is initialized to avoid timeouts of blocking compilations.
3868 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
3869 CompileBroker::compilation_init_phase2();
3870 }
3871 #endif
3872
3873 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3874 // It is done after compilers are initialized, because otherwise compilations of
3875 // signature polymorphic MH intrinsics can be missed
3876 // (see SystemDictionary::find_method_handle_intrinsic).
3877 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3878
3879 // This will initialize the module system. Only java.base classes can be
3880 // loaded until phase 2 completes
3881 call_initPhase2(CHECK_JNI_ERR);
3882
3883 // Always call even when there are not JVMTI environments yet, since environments
3884 // may be attached late and JVMTI must track phases of VM execution
3885 JvmtiExport::enter_start_phase();
3886
3887 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3888 JvmtiExport::post_vm_start();
3889
3890 // Final system initialization including security manager and system class loader
3891 call_initPhase3(CHECK_JNI_ERR);
3892
3893 // cache the system and platform class loaders
3894 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
3895
3896 #if INCLUDE_JVMCI
3897 if (force_JVMCI_intialization) {
3898 JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
3899 CompileBroker::compilation_init_phase2();
3900 }
3901 #endif
3902
3903 // Always call even when there are not JVMTI environments yet, since environments
3904 // may be attached late and JVMTI must track phases of VM execution
3905 JvmtiExport::enter_live_phase();
3906
3907 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3908 JvmtiExport::post_vm_initialized();
3909
3910 if (TRACE_START() != JNI_OK) {
3911 vm_exit_during_initialization("Failed to start tracing backend.");
3912 }
3913
3914 #if INCLUDE_MANAGEMENT
3915 Management::initialize(THREAD);
3916
3917 if (HAS_PENDING_EXCEPTION) {
3918 // management agent fails to start possibly due to
3919 // configuration problem and is responsible for printing
3920 // stack trace if appropriate. Simply exit VM.
3921 vm_exit(1);
3922 }
3923 #endif // INCLUDE_MANAGEMENT
3924
3925 if (MemProfiling) MemProfiler::engage();
3926 StatSampler::engage();
3927 if (CheckJNICalls) JniPeriodicChecker::engage();
3928
3929 BiasedLocking::init();
3930
3931 #if INCLUDE_RTM_OPT
3932 RTMLockingCounters::init();
3933 #endif
3934
3935 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3936 call_postVMInitHook(THREAD);
3937 // The Java side of PostVMInitHook.run must deal with all
3938 // exceptions and provide means of diagnosis.
3939 if (HAS_PENDING_EXCEPTION) {
3940 CLEAR_PENDING_EXCEPTION;
3941 }
3942 }
3943
3944 {
3945 MutexLocker ml(PeriodicTask_lock);
3946 // Make sure the WatcherThread can be started by WatcherThread::start()
3947 // or by dynamic enrollment.
3948 WatcherThread::make_startable();
3949 // Start up the WatcherThread if there are any periodic tasks
3950 // NOTE: All PeriodicTasks should be registered by now. If they
3951 // aren't, late joiners might appear to start slowly (we might
3952 // take a while to process their first tick).
3953 if (PeriodicTask::num_tasks() > 0) {
3954 WatcherThread::start();
3955 }
3956 }
3957
3958 create_vm_timer.end();
3959 #ifdef ASSERT
3960 _vm_complete = true;
3961 #endif
3962
3963 if (DumpSharedSpaces) {
3964 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3965 ShouldNotReachHere();
3966 }
3967
3968 return JNI_OK;
3969 }
3970
3971 // type for the Agent_OnLoad and JVM_OnLoad entry points
3972 extern "C" {
3973 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3974 }
3975 // Find a command line agent library and return its entry point for
3976 // -agentlib: -agentpath: -Xrun
3977 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3978 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3979 const char *on_load_symbols[],
3980 size_t num_symbol_entries) {
3981 OnLoadEntry_t on_load_entry = NULL;
3982 void *library = NULL;
3983
3984 if (!agent->valid()) {
3985 char buffer[JVM_MAXPATHLEN];
3986 char ebuf[1024] = "";
3987 const char *name = agent->name();
3988 const char *msg = "Could not find agent library ";
3989
3990 // First check to see if agent is statically linked into executable
3991 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3992 library = agent->os_lib();
3993 } else if (agent->is_absolute_path()) {
3994 library = os::dll_load(name, ebuf, sizeof ebuf);
3995 if (library == NULL) {
3996 const char *sub_msg = " in absolute path, with error: ";
3997 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3998 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3999 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4000 // If we can't find the agent, exit.
4001 vm_exit_during_initialization(buf, NULL);
4002 FREE_C_HEAP_ARRAY(char, buf);
4003 }
4004 } else {
4005 // Try to load the agent from the standard dll directory
4006 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4007 name)) {
4008 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4009 }
4010 if (library == NULL) { // Try the library path directory.
4011 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4012 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4013 }
4014 if (library == NULL) {
4015 const char *sub_msg = " on the library path, with error: ";
4016 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4017
4018 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4019 strlen(ebuf) + strlen(sub_msg2) + 1;
4020 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4021 if (!agent->is_instrument_lib()) {
4022 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4023 } else {
4024 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4025 }
4026 // If we can't find the agent, exit.
4027 vm_exit_during_initialization(buf, NULL);
4028 FREE_C_HEAP_ARRAY(char, buf);
4029 }
4030 }
4031 }
4032 agent->set_os_lib(library);
4033 agent->set_valid();
4034 }
4035
4036 // Find the OnLoad function.
4037 on_load_entry =
4038 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4039 false,
4040 on_load_symbols,
4041 num_symbol_entries));
4042 return on_load_entry;
4043 }
4044
4045 // Find the JVM_OnLoad entry point
4046 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4047 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4048 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4049 }
4050
4051 // Find the Agent_OnLoad entry point
4052 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4053 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4054 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4055 }
4056
4057 // For backwards compatibility with -Xrun
4058 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4059 // treated like -agentpath:
4060 // Must be called before agent libraries are created
4061 void Threads::convert_vm_init_libraries_to_agents() {
4062 AgentLibrary* agent;
4063 AgentLibrary* next;
4064
4065 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4066 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4067 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4068
4069 // If there is an JVM_OnLoad function it will get called later,
4070 // otherwise see if there is an Agent_OnLoad
4071 if (on_load_entry == NULL) {
4072 on_load_entry = lookup_agent_on_load(agent);
4073 if (on_load_entry != NULL) {
4074 // switch it to the agent list -- so that Agent_OnLoad will be called,
4075 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4076 Arguments::convert_library_to_agent(agent);
4077 } else {
4078 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4079 }
4080 }
4081 }
4082 }
4083
4084 // Create agents for -agentlib: -agentpath: and converted -Xrun
4085 // Invokes Agent_OnLoad
4086 // Called very early -- before JavaThreads exist
4087 void Threads::create_vm_init_agents() {
4088 extern struct JavaVM_ main_vm;
4089 AgentLibrary* agent;
4090
4091 JvmtiExport::enter_onload_phase();
4092
4093 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4094 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4095
4096 if (on_load_entry != NULL) {
4097 // Invoke the Agent_OnLoad function
4098 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4099 if (err != JNI_OK) {
4100 vm_exit_during_initialization("agent library failed to init", agent->name());
4101 }
4102 } else {
4103 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4104 }
4105 }
4106 JvmtiExport::enter_primordial_phase();
4107 }
4108
4109 extern "C" {
4110 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4111 }
4112
4113 void Threads::shutdown_vm_agents() {
4114 // Send any Agent_OnUnload notifications
4115 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4116 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4117 extern struct JavaVM_ main_vm;
4118 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4119
4120 // Find the Agent_OnUnload function.
4121 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4122 os::find_agent_function(agent,
4123 false,
4124 on_unload_symbols,
4125 num_symbol_entries));
4126
4127 // Invoke the Agent_OnUnload function
4128 if (unload_entry != NULL) {
4129 JavaThread* thread = JavaThread::current();
4130 ThreadToNativeFromVM ttn(thread);
4131 HandleMark hm(thread);
4132 (*unload_entry)(&main_vm);
4133 }
4134 }
4135 }
4136
4137 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4138 // Invokes JVM_OnLoad
4139 void Threads::create_vm_init_libraries() {
4140 extern struct JavaVM_ main_vm;
4141 AgentLibrary* agent;
4142
4143 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4144 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4145
4146 if (on_load_entry != NULL) {
4147 // Invoke the JVM_OnLoad function
4148 JavaThread* thread = JavaThread::current();
4149 ThreadToNativeFromVM ttn(thread);
4150 HandleMark hm(thread);
4151 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4152 if (err != JNI_OK) {
4153 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4154 }
4155 } else {
4156 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4157 }
4158 }
4159 }
4160
4161
4162 // Last thread running calls java.lang.Shutdown.shutdown()
4163 void JavaThread::invoke_shutdown_hooks() {
4164 HandleMark hm(this);
4165
4166 // We could get here with a pending exception, if so clear it now.
4167 if (this->has_pending_exception()) {
4168 this->clear_pending_exception();
4169 }
4170
4171 EXCEPTION_MARK;
4172 Klass* shutdown_klass =
4173 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4174 THREAD);
4175 if (shutdown_klass != NULL) {
4176 // SystemDictionary::resolve_or_null will return null if there was
4177 // an exception. If we cannot load the Shutdown class, just don't
4178 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4179 // won't be run. Note that if a shutdown hook was registered,
4180 // the Shutdown class would have already been loaded
4181 // (Runtime.addShutdownHook will load it).
4182 JavaValue result(T_VOID);
4183 JavaCalls::call_static(&result,
4184 shutdown_klass,
4185 vmSymbols::shutdown_method_name(),
4186 vmSymbols::void_method_signature(),
4187 THREAD);
4188 }
4189 CLEAR_PENDING_EXCEPTION;
4190 }
4191
4192 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4193 // the program falls off the end of main(). Another VM exit path is through
4194 // vm_exit() when the program calls System.exit() to return a value or when
4195 // there is a serious error in VM. The two shutdown paths are not exactly
4196 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
4197 // and VM_Exit op at VM level.
4198 //
4199 // Shutdown sequence:
4200 // + Shutdown native memory tracking if it is on
4201 // + Wait until we are the last non-daemon thread to execute
4202 // <-- every thing is still working at this moment -->
4203 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4204 // shutdown hooks
4205 // + Call before_exit(), prepare for VM exit
4206 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4207 // currently the only user of this mechanism is File.deleteOnExit())
4208 // > stop StatSampler, watcher thread, CMS threads,
4209 // post thread end and vm death events to JVMTI,
4210 // stop signal thread
4211 // + Call JavaThread::exit(), it will:
4212 // > release JNI handle blocks, remove stack guard pages
4213 // > remove this thread from Threads list
4214 // <-- no more Java code from this thread after this point -->
4215 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4216 // the compiler threads at safepoint
4217 // <-- do not use anything that could get blocked by Safepoint -->
4218 // + Disable tracing at JNI/JVM barriers
4219 // + Set _vm_exited flag for threads that are still running native code
4220 // + Delete this thread
4221 // + Call exit_globals()
4222 // > deletes tty
4223 // > deletes PerfMemory resources
4224 // + Return to caller
4225
4226 bool Threads::destroy_vm() {
4227 JavaThread* thread = JavaThread::current();
4228
4229 #ifdef ASSERT
4230 _vm_complete = false;
4231 #endif
4232 // Wait until we are the last non-daemon thread to execute
4233 { MutexLocker nu(Threads_lock);
4234 while (Threads::number_of_non_daemon_threads() > 1)
4235 // This wait should make safepoint checks, wait without a timeout,
4236 // and wait as a suspend-equivalent condition.
4237 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
4238 Mutex::_as_suspend_equivalent_flag);
4239 }
4240
4241 EventShutdown e;
4242 if (e.should_commit()) {
4243 e.set_reason("No remaining non-daemon Java threads");
4244 e.commit();
4245 }
4246
4247 // Hang forever on exit if we are reporting an error.
4248 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4249 os::infinite_sleep();
4250 }
4251 os::wait_for_keypress_at_exit();
4252
4253 // run Java level shutdown hooks
4254 thread->invoke_shutdown_hooks();
4255
4256 before_exit(thread);
4257
4258 thread->exit(true);
4259
4260 // Stop VM thread.
4261 {
4262 // 4945125 The vm thread comes to a safepoint during exit.
4263 // GC vm_operations can get caught at the safepoint, and the
4264 // heap is unparseable if they are caught. Grab the Heap_lock
4265 // to prevent this. The GC vm_operations will not be able to
4266 // queue until after the vm thread is dead. After this point,
4267 // we'll never emerge out of the safepoint before the VM exits.
4268
4269 MutexLocker ml(Heap_lock);
4270
4271 VMThread::wait_for_vm_thread_exit();
4272 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4273 VMThread::destroy();
4274 }
4275
4276 // Now, all Java threads are gone except daemon threads. Daemon threads
4277 // running Java code or in VM are stopped by the Safepoint. However,
4278 // daemon threads executing native code are still running. But they
4279 // will be stopped at native=>Java/VM barriers. Note that we can't
4280 // simply kill or suspend them, as it is inherently deadlock-prone.
4281
4282 VM_Exit::set_vm_exited();
4283
4284 // Clean up ideal graph printers after the VMThread has started
4285 // the final safepoint which will block all the Compiler threads.
4286 // Note that this Thread has already logically exited so the
4287 // clean_up() function's use of a JavaThreadIteratorWithHandle
4288 // would be a problem except set_vm_exited() has remembered the
4289 // shutdown thread which is granted a policy exception.
4290 #if defined(COMPILER2) && !defined(PRODUCT)
4291 IdealGraphPrinter::clean_up();
4292 #endif
4293
4294 notify_vm_shutdown();
4295
4296 // We are after VM_Exit::set_vm_exited() so we can't call
4297 // thread->smr_delete() or we will block on the Threads_lock.
4298 // Deleting the shutdown thread here is safe because another
4299 // JavaThread cannot have an active ThreadsListHandle for
4300 // this JavaThread.
4301 delete thread;
4302
4303 #if INCLUDE_JVMCI
4304 if (JVMCICounterSize > 0) {
4305 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4306 }
4307 #endif
4308
4309 // exit_globals() will delete tty
4310 exit_globals();
4311
4312 LogConfiguration::finalize();
4313
4314 return true;
4315 }
4316
4317
4318 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4319 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4320 return is_supported_jni_version(version);
4321 }
4322
4323
4324 jboolean Threads::is_supported_jni_version(jint version) {
4325 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4326 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4327 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4328 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4329 if (version == JNI_VERSION_9) return JNI_TRUE;
4330 if (version == JNI_VERSION_10) return JNI_TRUE;
4331 return JNI_FALSE;
4332 }
4333
4334
4335 void Threads::add(JavaThread* p, bool force_daemon) {
4336 // The threads lock must be owned at this point
4337 assert_locked_or_safepoint(Threads_lock);
4338
4339 BarrierSet::barrier_set()->on_thread_attach(p);
4340
4341 p->set_next(_thread_list);
4342 _thread_list = p;
4343
4344 // Once a JavaThread is added to the Threads list, smr_delete() has
4345 // to be used to delete it. Otherwise we can just delete it directly.
4346 p->set_on_thread_list();
4347
4348 _number_of_threads++;
4349 oop threadObj = p->threadObj();
4350 bool daemon = true;
4351 // Bootstrapping problem: threadObj can be null for initial
4352 // JavaThread (or for threads attached via JNI)
4353 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
4354 _number_of_non_daemon_threads++;
4355 daemon = false;
4356 }
4357
4358 ThreadService::add_thread(p, daemon);
4359
4360 // Maintain fast thread list
4361 ThreadsSMRSupport::add_thread(p);
4362
4363 // Possible GC point.
4364 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4365 }
4366
4367 void Threads::remove(JavaThread* p) {
4368
4369 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread.
4370 ObjectSynchronizer::omFlush(p);
4371
4372 // Extra scope needed for Thread_lock, so we can check
4373 // that we do not remove thread without safepoint code notice
4374 { MutexLocker ml(Threads_lock);
4375
4376 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4377
4378 // Maintain fast thread list
4379 ThreadsSMRSupport::remove_thread(p);
4380
4381 JavaThread* current = _thread_list;
4382 JavaThread* prev = NULL;
4383
4384 while (current != p) {
4385 prev = current;
4386 current = current->next();
4387 }
4388
4389 if (prev) {
4390 prev->set_next(current->next());
4391 } else {
4392 _thread_list = p->next();
4393 }
4394
4395 _number_of_threads--;
4396 oop threadObj = p->threadObj();
4397 bool daemon = true;
4398 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4399 _number_of_non_daemon_threads--;
4400 daemon = false;
4401
4402 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4403 // on destroy_vm will wake up.
4404 if (number_of_non_daemon_threads() == 1) {
4405 Threads_lock->notify_all();
4406 }
4407 }
4408 ThreadService::remove_thread(p, daemon);
4409
4410 // Make sure that safepoint code disregard this thread. This is needed since
4411 // the thread might mess around with locks after this point. This can cause it
4412 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4413 // of this thread since it is removed from the queue.
4414 p->set_terminated_value();
4415 } // unlock Threads_lock
4416
4417 // Since Events::log uses a lock, we grab it outside the Threads_lock
4418 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4419 }
4420
4421 // Operations on the Threads list for GC. These are not explicitly locked,
4422 // but the garbage collector must provide a safe context for them to run.
4423 // In particular, these things should never be called when the Threads_lock
4424 // is held by some other thread. (Note: the Safepoint abstraction also
4425 // uses the Threads_lock to guarantee this property. It also makes sure that
4426 // all threads gets blocked when exiting or starting).
4427
4428 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4429 ALL_JAVA_THREADS(p) {
4430 p->oops_do(f, cf);
4431 }
4432 VMThread::vm_thread()->oops_do(f, cf);
4433 }
4434
4435 void Threads::change_thread_claim_parity() {
4436 // Set the new claim parity.
4437 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4438 "Not in range.");
4439 _thread_claim_parity++;
4440 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4441 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4442 "Not in range.");
4443 }
4444
4445 #ifdef ASSERT
4446 void Threads::assert_all_threads_claimed() {
4447 ALL_JAVA_THREADS(p) {
4448 const int thread_parity = p->oops_do_parity();
4449 assert((thread_parity == _thread_claim_parity),
4450 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity);
4451 }
4452 VMThread* vmt = VMThread::vm_thread();
4453 const int thread_parity = vmt->oops_do_parity();
4454 assert((thread_parity == _thread_claim_parity),
4455 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity);
4456 }
4457 #endif // ASSERT
4458
4459 class ParallelOopsDoThreadClosure : public ThreadClosure {
4460 private:
4461 OopClosure* _f;
4462 CodeBlobClosure* _cf;
4463 public:
4464 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4465 void do_thread(Thread* t) {
4466 t->oops_do(_f, _cf);
4467 }
4468 };
4469
4470 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4471 ParallelOopsDoThreadClosure tc(f, cf);
4472 possibly_parallel_threads_do(is_par, &tc);
4473 }
4474
4475 #if INCLUDE_ALL_GCS
4476 // Used by ParallelScavenge
4477 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4478 ALL_JAVA_THREADS(p) {
4479 q->enqueue(new ThreadRootsTask(p));
4480 }
4481 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4482 }
4483
4484 // Used by Parallel Old
4485 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4486 ALL_JAVA_THREADS(p) {
4487 q->enqueue(new ThreadRootsMarkingTask(p));
4488 }
4489 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4490 }
4491 #endif // INCLUDE_ALL_GCS
4492
4493 void Threads::nmethods_do(CodeBlobClosure* cf) {
4494 ALL_JAVA_THREADS(p) {
4495 // This is used by the code cache sweeper to mark nmethods that are active
4496 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4497 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4498 if(!p->is_Code_cache_sweeper_thread()) {
4499 p->nmethods_do(cf);
4500 }
4501 }
4502 }
4503
4504 void Threads::metadata_do(void f(Metadata*)) {
4505 ALL_JAVA_THREADS(p) {
4506 p->metadata_do(f);
4507 }
4508 }
4509
4510 class ThreadHandlesClosure : public ThreadClosure {
4511 void (*_f)(Metadata*);
4512 public:
4513 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4514 virtual void do_thread(Thread* thread) {
4515 thread->metadata_handles_do(_f);
4516 }
4517 };
4518
4519 void Threads::metadata_handles_do(void f(Metadata*)) {
4520 // Only walk the Handles in Thread.
4521 ThreadHandlesClosure handles_closure(f);
4522 threads_do(&handles_closure);
4523 }
4524
4525 void Threads::deoptimized_wrt_marked_nmethods() {
4526 ALL_JAVA_THREADS(p) {
4527 p->deoptimized_wrt_marked_nmethods();
4528 }
4529 }
4530
4531
4532 // Get count Java threads that are waiting to enter the specified monitor.
4533 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4534 int count,
4535 address monitor) {
4536 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4537
4538 int i = 0;
4539 DO_JAVA_THREADS(t_list, p) {
4540 if (!p->can_call_java()) continue;
4541
4542 address pending = (address)p->current_pending_monitor();
4543 if (pending == monitor) { // found a match
4544 if (i < count) result->append(p); // save the first count matches
4545 i++;
4546 }
4547 }
4548
4549 return result;
4550 }
4551
4552
4553 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4554 address owner) {
4555 // NULL owner means not locked so we can skip the search
4556 if (owner == NULL) return NULL;
4557
4558 DO_JAVA_THREADS(t_list, p) {
4559 // first, see if owner is the address of a Java thread
4560 if (owner == (address)p) return p;
4561 }
4562
4563 // Cannot assert on lack of success here since this function may be
4564 // used by code that is trying to report useful problem information
4565 // like deadlock detection.
4566 if (UseHeavyMonitors) return NULL;
4567
4568 // If we didn't find a matching Java thread and we didn't force use of
4569 // heavyweight monitors, then the owner is the stack address of the
4570 // Lock Word in the owning Java thread's stack.
4571 //
4572 JavaThread* the_owner = NULL;
4573 DO_JAVA_THREADS(t_list, q) {
4574 if (q->is_lock_owned(owner)) {
4575 the_owner = q;
4576 break;
4577 }
4578 }
4579
4580 // cannot assert on lack of success here; see above comment
4581 return the_owner;
4582 }
4583
4584 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4585 void Threads::print_on(outputStream* st, bool print_stacks,
4586 bool internal_format, bool print_concurrent_locks) {
4587 char buf[32];
4588 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4589
4590 st->print_cr("Full thread dump %s (%s %s):",
4591 Abstract_VM_Version::vm_name(),
4592 Abstract_VM_Version::vm_release(),
4593 Abstract_VM_Version::vm_info_string());
4594 st->cr();
4595
4596 #if INCLUDE_SERVICES
4597 // Dump concurrent locks
4598 ConcurrentLocksDump concurrent_locks;
4599 if (print_concurrent_locks) {
4600 concurrent_locks.dump_at_safepoint();
4601 }
4602 #endif // INCLUDE_SERVICES
4603
4604 ThreadsSMRSupport::print_info_on(st);
4605 st->cr();
4606
4607 ALL_JAVA_THREADS(p) {
4608 ResourceMark rm;
4609 p->print_on(st);
4610 if (print_stacks) {
4611 if (internal_format) {
4612 p->trace_stack();
4613 } else {
4614 p->print_stack_on(st);
4615 }
4616 }
4617 st->cr();
4618 #if INCLUDE_SERVICES
4619 if (print_concurrent_locks) {
4620 concurrent_locks.print_locks_on(p, st);
4621 }
4622 #endif // INCLUDE_SERVICES
4623 }
4624
4625 VMThread::vm_thread()->print_on(st);
4626 st->cr();
4627 Universe::heap()->print_gc_threads_on(st);
4628 WatcherThread* wt = WatcherThread::watcher_thread();
4629 if (wt != NULL) {
4630 wt->print_on(st);
4631 st->cr();
4632 }
4633
4634 st->flush();
4635 }
4636
4637 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4638 int buflen, bool* found_current) {
4639 if (this_thread != NULL) {
4640 bool is_current = (current == this_thread);
4641 *found_current = *found_current || is_current;
4642 st->print("%s", is_current ? "=>" : " ");
4643
4644 st->print(PTR_FORMAT, p2i(this_thread));
4645 st->print(" ");
4646 this_thread->print_on_error(st, buf, buflen);
4647 st->cr();
4648 }
4649 }
4650
4651 class PrintOnErrorClosure : public ThreadClosure {
4652 outputStream* _st;
4653 Thread* _current;
4654 char* _buf;
4655 int _buflen;
4656 bool* _found_current;
4657 public:
4658 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4659 int buflen, bool* found_current) :
4660 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4661
4662 virtual void do_thread(Thread* thread) {
4663 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4664 }
4665 };
4666
4667 // Threads::print_on_error() is called by fatal error handler. It's possible
4668 // that VM is not at safepoint and/or current thread is inside signal handler.
4669 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4670 // memory (even in resource area), it might deadlock the error handler.
4671 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4672 int buflen) {
4673 ThreadsSMRSupport::print_info_on(st);
4674 st->cr();
4675
4676 bool found_current = false;
4677 st->print_cr("Java Threads: ( => current thread )");
4678 ALL_JAVA_THREADS(thread) {
4679 print_on_error(thread, st, current, buf, buflen, &found_current);
4680 }
4681 st->cr();
4682
4683 st->print_cr("Other Threads:");
4684 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4685 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4686
4687 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4688 Universe::heap()->gc_threads_do(&print_closure);
4689
4690 if (!found_current) {
4691 st->cr();
4692 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4693 current->print_on_error(st, buf, buflen);
4694 st->cr();
4695 }
4696 st->cr();
4697
4698 st->print_cr("Threads with active compile tasks:");
4699 print_threads_compiling(st, buf, buflen);
4700 }
4701
4702 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
4703 ALL_JAVA_THREADS(thread) {
4704 if (thread->is_Compiler_thread()) {
4705 CompilerThread* ct = (CompilerThread*) thread;
4706
4707 // Keep task in local variable for NULL check.
4708 // ct->_task might be set to NULL by concurring compiler thread
4709 // because it completed the compilation. The task is never freed,
4710 // though, just returned to a free list.
4711 CompileTask* task = ct->task();
4712 if (task != NULL) {
4713 thread->print_name_on_error(st, buf, buflen);
4714 task->print(st, NULL, true, true);
4715 }
4716 }
4717 }
4718 }
4719
4720
4721 // Internal SpinLock and Mutex
4722 // Based on ParkEvent
4723
4724 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4725 //
4726 // We employ SpinLocks _only for low-contention, fixed-length
4727 // short-duration critical sections where we're concerned
4728 // about native mutex_t or HotSpot Mutex:: latency.
4729 // The mux construct provides a spin-then-block mutual exclusion
4730 // mechanism.
4731 //
4732 // Testing has shown that contention on the ListLock guarding gFreeList
4733 // is common. If we implement ListLock as a simple SpinLock it's common
4734 // for the JVM to devolve to yielding with little progress. This is true
4735 // despite the fact that the critical sections protected by ListLock are
4736 // extremely short.
4737 //
4738 // TODO-FIXME: ListLock should be of type SpinLock.
4739 // We should make this a 1st-class type, integrated into the lock
4740 // hierarchy as leaf-locks. Critically, the SpinLock structure
4741 // should have sufficient padding to avoid false-sharing and excessive
4742 // cache-coherency traffic.
4743
4744
4745 typedef volatile int SpinLockT;
4746
4747 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4748 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4749 return; // normal fast-path return
4750 }
4751
4752 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4753 TEVENT(SpinAcquire - ctx);
4754 int ctr = 0;
4755 int Yields = 0;
4756 for (;;) {
4757 while (*adr != 0) {
4758 ++ctr;
4759 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4760 if (Yields > 5) {
4761 os::naked_short_sleep(1);
4762 } else {
4763 os::naked_yield();
4764 ++Yields;
4765 }
4766 } else {
4767 SpinPause();
4768 }
4769 }
4770 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4771 }
4772 }
4773
4774 void Thread::SpinRelease(volatile int * adr) {
4775 assert(*adr != 0, "invariant");
4776 OrderAccess::fence(); // guarantee at least release consistency.
4777 // Roach-motel semantics.
4778 // It's safe if subsequent LDs and STs float "up" into the critical section,
4779 // but prior LDs and STs within the critical section can't be allowed
4780 // to reorder or float past the ST that releases the lock.
4781 // Loads and stores in the critical section - which appear in program
4782 // order before the store that releases the lock - must also appear
4783 // before the store that releases the lock in memory visibility order.
4784 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4785 // the ST of 0 into the lock-word which releases the lock, so fence
4786 // more than covers this on all platforms.
4787 *adr = 0;
4788 }
4789
4790 // muxAcquire and muxRelease:
4791 //
4792 // * muxAcquire and muxRelease support a single-word lock-word construct.
4793 // The LSB of the word is set IFF the lock is held.
4794 // The remainder of the word points to the head of a singly-linked list
4795 // of threads blocked on the lock.
4796 //
4797 // * The current implementation of muxAcquire-muxRelease uses its own
4798 // dedicated Thread._MuxEvent instance. If we're interested in
4799 // minimizing the peak number of extant ParkEvent instances then
4800 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4801 // as certain invariants were satisfied. Specifically, care would need
4802 // to be taken with regards to consuming unpark() "permits".
4803 // A safe rule of thumb is that a thread would never call muxAcquire()
4804 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4805 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4806 // consume an unpark() permit intended for monitorenter, for instance.
4807 // One way around this would be to widen the restricted-range semaphore
4808 // implemented in park(). Another alternative would be to provide
4809 // multiple instances of the PlatformEvent() for each thread. One
4810 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4811 //
4812 // * Usage:
4813 // -- Only as leaf locks
4814 // -- for short-term locking only as muxAcquire does not perform
4815 // thread state transitions.
4816 //
4817 // Alternatives:
4818 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4819 // but with parking or spin-then-park instead of pure spinning.
4820 // * Use Taura-Oyama-Yonenzawa locks.
4821 // * It's possible to construct a 1-0 lock if we encode the lockword as
4822 // (List,LockByte). Acquire will CAS the full lockword while Release
4823 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4824 // acquiring threads use timers (ParkTimed) to detect and recover from
4825 // the stranding window. Thread/Node structures must be aligned on 256-byte
4826 // boundaries by using placement-new.
4827 // * Augment MCS with advisory back-link fields maintained with CAS().
4828 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4829 // The validity of the backlinks must be ratified before we trust the value.
4830 // If the backlinks are invalid the exiting thread must back-track through the
4831 // the forward links, which are always trustworthy.
4832 // * Add a successor indication. The LockWord is currently encoded as
4833 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4834 // to provide the usual futile-wakeup optimization.
4835 // See RTStt for details.
4836 // * Consider schedctl.sc_nopreempt to cover the critical section.
4837 //
4838
4839
4840 const intptr_t LOCKBIT = 1;
4841
4842 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4843 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4844 if (w == 0) return;
4845 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4846 return;
4847 }
4848
4849 TEVENT(muxAcquire - Contention);
4850 ParkEvent * const Self = Thread::current()->_MuxEvent;
4851 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4852 for (;;) {
4853 int its = (os::is_MP() ? 100 : 0) + 1;
4854
4855 // Optional spin phase: spin-then-park strategy
4856 while (--its >= 0) {
4857 w = *Lock;
4858 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4859 return;
4860 }
4861 }
4862
4863 Self->reset();
4864 Self->OnList = intptr_t(Lock);
4865 // The following fence() isn't _strictly necessary as the subsequent
4866 // CAS() both serializes execution and ratifies the fetched *Lock value.
4867 OrderAccess::fence();
4868 for (;;) {
4869 w = *Lock;
4870 if ((w & LOCKBIT) == 0) {
4871 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4872 Self->OnList = 0; // hygiene - allows stronger asserts
4873 return;
4874 }
4875 continue; // Interference -- *Lock changed -- Just retry
4876 }
4877 assert(w & LOCKBIT, "invariant");
4878 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4879 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4880 }
4881
4882 while (Self->OnList != 0) {
4883 Self->park();
4884 }
4885 }
4886 }
4887
4888 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4889 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4890 if (w == 0) return;
4891 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4892 return;
4893 }
4894
4895 TEVENT(muxAcquire - Contention);
4896 ParkEvent * ReleaseAfter = NULL;
4897 if (ev == NULL) {
4898 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4899 }
4900 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4901 for (;;) {
4902 guarantee(ev->OnList == 0, "invariant");
4903 int its = (os::is_MP() ? 100 : 0) + 1;
4904
4905 // Optional spin phase: spin-then-park strategy
4906 while (--its >= 0) {
4907 w = *Lock;
4908 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4909 if (ReleaseAfter != NULL) {
4910 ParkEvent::Release(ReleaseAfter);
4911 }
4912 return;
4913 }
4914 }
4915
4916 ev->reset();
4917 ev->OnList = intptr_t(Lock);
4918 // The following fence() isn't _strictly necessary as the subsequent
4919 // CAS() both serializes execution and ratifies the fetched *Lock value.
4920 OrderAccess::fence();
4921 for (;;) {
4922 w = *Lock;
4923 if ((w & LOCKBIT) == 0) {
4924 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4925 ev->OnList = 0;
4926 // We call ::Release while holding the outer lock, thus
4927 // artificially lengthening the critical section.
4928 // Consider deferring the ::Release() until the subsequent unlock(),
4929 // after we've dropped the outer lock.
4930 if (ReleaseAfter != NULL) {
4931 ParkEvent::Release(ReleaseAfter);
4932 }
4933 return;
4934 }
4935 continue; // Interference -- *Lock changed -- Just retry
4936 }
4937 assert(w & LOCKBIT, "invariant");
4938 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4939 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4940 }
4941
4942 while (ev->OnList != 0) {
4943 ev->park();
4944 }
4945 }
4946 }
4947
4948 // Release() must extract a successor from the list and then wake that thread.
4949 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4950 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4951 // Release() would :
4952 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4953 // (B) Extract a successor from the private list "in-hand"
4954 // (C) attempt to CAS() the residual back into *Lock over null.
4955 // If there were any newly arrived threads and the CAS() would fail.
4956 // In that case Release() would detach the RATs, re-merge the list in-hand
4957 // with the RATs and repeat as needed. Alternately, Release() might
4958 // detach and extract a successor, but then pass the residual list to the wakee.
4959 // The wakee would be responsible for reattaching and remerging before it
4960 // competed for the lock.
4961 //
4962 // Both "pop" and DMR are immune from ABA corruption -- there can be
4963 // multiple concurrent pushers, but only one popper or detacher.
4964 // This implementation pops from the head of the list. This is unfair,
4965 // but tends to provide excellent throughput as hot threads remain hot.
4966 // (We wake recently run threads first).
4967 //
4968 // All paths through muxRelease() will execute a CAS.
4969 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4970 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4971 // executed within the critical section are complete and globally visible before the
4972 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4973 void Thread::muxRelease(volatile intptr_t * Lock) {
4974 for (;;) {
4975 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
4976 assert(w & LOCKBIT, "invariant");
4977 if (w == LOCKBIT) return;
4978 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4979 assert(List != NULL, "invariant");
4980 assert(List->OnList == intptr_t(Lock), "invariant");
4981 ParkEvent * const nxt = List->ListNext;
4982 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4983
4984 // The following CAS() releases the lock and pops the head element.
4985 // The CAS() also ratifies the previously fetched lock-word value.
4986 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
4987 continue;
4988 }
4989 List->OnList = 0;
4990 OrderAccess::fence();
4991 List->unpark();
4992 return;
4993 }
4994 }
4995
4996
4997 void Threads::verify() {
4998 ALL_JAVA_THREADS(p) {
4999 p->verify();
5000 }
5001 VMThread* thread = VMThread::vm_thread();
5002 if (thread != NULL) thread->verify();
5003 }