1 /* 2 * Copyright (c) 1997, 2014, 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 "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/scopeDesc.hpp" 32 #include "compiler/compileBroker.hpp" 33 #include "interpreter/interpreter.hpp" 34 #include "interpreter/linkResolver.hpp" 35 #include "interpreter/oopMapCache.hpp" 36 #include "jvmtifiles/jvmtiEnv.hpp" 37 #include "memory/gcLocker.inline.hpp" 38 #include "memory/metaspaceShared.hpp" 39 #include "memory/oopFactory.hpp" 40 #include "memory/universe.inline.hpp" 41 #include "oops/instanceKlass.hpp" 42 #include "oops/objArrayOop.hpp" 43 #include "oops/oop.inline.hpp" 44 #include "oops/symbol.hpp" 45 #include "prims/jvm_misc.hpp" 46 #include "prims/jvmtiExport.hpp" 47 #include "prims/jvmtiThreadState.hpp" 48 #include "prims/privilegedStack.hpp" 49 #include "runtime/arguments.hpp" 50 #include "runtime/atomic.inline.hpp" 51 #include "runtime/biasedLocking.hpp" 52 #include "runtime/deoptimization.hpp" 53 #include "runtime/fprofiler.hpp" 54 #include "runtime/frame.inline.hpp" 55 #include "runtime/init.hpp" 56 #include "runtime/interfaceSupport.hpp" 57 #include "runtime/java.hpp" 58 #include "runtime/javaCalls.hpp" 59 #include "runtime/jniPeriodicChecker.hpp" 60 #include "runtime/memprofiler.hpp" 61 #include "runtime/mutexLocker.hpp" 62 #include "runtime/objectMonitor.hpp" 63 #include "runtime/orderAccess.inline.hpp" 64 #include "runtime/osThread.hpp" 65 #include "runtime/safepoint.hpp" 66 #include "runtime/sharedRuntime.hpp" 67 #include "runtime/statSampler.hpp" 68 #include "runtime/stubRoutines.hpp" 69 #include "runtime/task.hpp" 70 #include "runtime/thread.inline.hpp" 71 #include "runtime/threadCritical.hpp" 72 #include "runtime/threadLocalStorage.hpp" 73 #include "runtime/vframe.hpp" 74 #include "runtime/vframeArray.hpp" 75 #include "runtime/vframe_hp.hpp" 76 #include "runtime/vmThread.hpp" 77 #include "runtime/vm_operations.hpp" 78 #include "runtime/vm_version.hpp" 79 #include "services/attachListener.hpp" 80 #include "services/management.hpp" 81 #include "services/memTracker.hpp" 82 #include "services/threadService.hpp" 83 #include "trace/tracing.hpp" 84 #include "trace/traceMacros.hpp" 85 #include "utilities/defaultStream.hpp" 86 #include "utilities/dtrace.hpp" 87 #include "utilities/events.hpp" 88 #include "utilities/preserveException.hpp" 89 #include "utilities/macros.hpp" 90 #if INCLUDE_ALL_GCS 91 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 92 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 93 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 94 #endif // INCLUDE_ALL_GCS 95 #ifdef COMPILER1 96 #include "c1/c1_Compiler.hpp" 97 #endif 98 #ifdef COMPILER2 99 #include "opto/c2compiler.hpp" 100 #include "opto/idealGraphPrinter.hpp" 101 #endif 102 #if INCLUDE_RTM_OPT 103 #include "runtime/rtmLocking.hpp" 104 #endif 105 106 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 107 108 #ifdef DTRACE_ENABLED 109 110 // Only bother with this argument setup if dtrace is available 111 112 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 113 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 114 115 #define DTRACE_THREAD_PROBE(probe, javathread) \ 116 { \ 117 ResourceMark rm(this); \ 118 int len = 0; \ 119 const char* name = (javathread)->get_thread_name(); \ 120 len = strlen(name); \ 121 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 122 (char *) name, len, \ 123 java_lang_Thread::thread_id((javathread)->threadObj()), \ 124 (uintptr_t) (javathread)->osthread()->thread_id(), \ 125 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 126 } 127 128 #else // ndef DTRACE_ENABLED 129 130 #define DTRACE_THREAD_PROBE(probe, javathread) 131 132 #endif // ndef DTRACE_ENABLED 133 134 135 // Class hierarchy 136 // - Thread 137 // - VMThread 138 // - WatcherThread 139 // - ConcurrentMarkSweepThread 140 // - JavaThread 141 // - CompilerThread 142 143 // ======= Thread ======== 144 // Support for forcing alignment of thread objects for biased locking 145 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 146 if (UseBiasedLocking) { 147 const int alignment = markOopDesc::biased_lock_alignment; 148 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 149 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 150 : AllocateHeap(aligned_size, flags, CURRENT_PC, 151 AllocFailStrategy::RETURN_NULL); 152 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 153 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 154 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 155 "JavaThread alignment code overflowed allocated storage"); 156 if (TraceBiasedLocking) { 157 if (aligned_addr != real_malloc_addr) { 158 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 159 real_malloc_addr, aligned_addr); 160 } 161 } 162 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 163 return aligned_addr; 164 } else { 165 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 166 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 167 } 168 } 169 170 void Thread::operator delete(void* p) { 171 if (UseBiasedLocking) { 172 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 173 FreeHeap(real_malloc_addr, mtThread); 174 } else { 175 FreeHeap(p, mtThread); 176 } 177 } 178 179 180 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 181 // JavaThread 182 183 184 Thread::Thread() { 185 // stack and get_thread 186 set_stack_base(NULL); 187 set_stack_size(0); 188 set_self_raw_id(0); 189 set_lgrp_id(-1); 190 191 // allocated data structures 192 set_osthread(NULL); 193 set_resource_area(new (mtThread)ResourceArea()); 194 DEBUG_ONLY(_current_resource_mark = NULL;) 195 set_handle_area(new (mtThread) HandleArea(NULL)); 196 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 197 set_active_handles(NULL); 198 set_free_handle_block(NULL); 199 set_last_handle_mark(NULL); 200 201 // This initial value ==> never claimed. 202 _oops_do_parity = 0; 203 204 _metadata_on_stack_buffer = NULL; 205 206 // the handle mark links itself to last_handle_mark 207 new HandleMark(this); 208 209 // plain initialization 210 debug_only(_owned_locks = NULL;) 211 debug_only(_allow_allocation_count = 0;) 212 NOT_PRODUCT(_allow_safepoint_count = 0;) 213 NOT_PRODUCT(_skip_gcalot = false;) 214 _jvmti_env_iteration_count = 0; 215 set_allocated_bytes(0); 216 _vm_operation_started_count = 0; 217 _vm_operation_completed_count = 0; 218 _current_pending_monitor = NULL; 219 _current_pending_monitor_is_from_java = true; 220 _current_waiting_monitor = NULL; 221 _num_nested_signal = 0; 222 omFreeList = NULL; 223 omFreeCount = 0; 224 omFreeProvision = 32; 225 omInUseList = NULL; 226 omInUseCount = 0; 227 228 #ifdef ASSERT 229 _visited_for_critical_count = false; 230 #endif 231 232 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 233 _suspend_flags = 0; 234 235 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 236 _hashStateX = os::random(); 237 _hashStateY = 842502087; 238 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 239 _hashStateW = 273326509; 240 241 _OnTrap = 0; 242 _schedctl = NULL; 243 _Stalled = 0; 244 _TypeTag = 0x2BAD; 245 246 // Many of the following fields are effectively final - immutable 247 // Note that nascent threads can't use the Native Monitor-Mutex 248 // construct until the _MutexEvent is initialized ... 249 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 250 // we might instead use a stack of ParkEvents that we could provision on-demand. 251 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 252 // and ::Release() 253 _ParkEvent = ParkEvent::Allocate(this); 254 _SleepEvent = ParkEvent::Allocate(this); 255 _MutexEvent = ParkEvent::Allocate(this); 256 _MuxEvent = ParkEvent::Allocate(this); 257 258 #ifdef CHECK_UNHANDLED_OOPS 259 if (CheckUnhandledOops) { 260 _unhandled_oops = new UnhandledOops(this); 261 } 262 #endif // CHECK_UNHANDLED_OOPS 263 #ifdef ASSERT 264 if (UseBiasedLocking) { 265 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 266 assert(this == _real_malloc_address || 267 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 268 "bug in forced alignment of thread objects"); 269 } 270 #endif // ASSERT 271 } 272 273 void Thread::initialize_thread_local_storage() { 274 // Note: Make sure this method only calls 275 // non-blocking operations. Otherwise, it might not work 276 // with the thread-startup/safepoint interaction. 277 278 // During Java thread startup, safepoint code should allow this 279 // method to complete because it may need to allocate memory to 280 // store information for the new thread. 281 282 // initialize structure dependent on thread local storage 283 ThreadLocalStorage::set_thread(this); 284 } 285 286 void Thread::record_stack_base_and_size() { 287 set_stack_base(os::current_stack_base()); 288 set_stack_size(os::current_stack_size()); 289 if (is_Java_thread()) { 290 ((JavaThread*) this)->set_stack_overflow_limit(); 291 } 292 // CR 7190089: on Solaris, primordial thread's stack is adjusted 293 // in initialize_thread(). Without the adjustment, stack size is 294 // incorrect if stack is set to unlimited (ulimit -s unlimited). 295 // So far, only Solaris has real implementation of initialize_thread(). 296 // 297 // set up any platform-specific state. 298 os::initialize_thread(this); 299 300 #if INCLUDE_NMT 301 // record thread's native stack, stack grows downward 302 address stack_low_addr = stack_base() - stack_size(); 303 MemTracker::record_thread_stack(stack_low_addr, stack_size()); 304 #endif // INCLUDE_NMT 305 } 306 307 308 Thread::~Thread() { 309 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 310 ObjectSynchronizer::omFlush(this); 311 312 EVENT_THREAD_DESTRUCT(this); 313 314 // stack_base can be NULL if the thread is never started or exited before 315 // record_stack_base_and_size called. Although, we would like to ensure 316 // that all started threads do call record_stack_base_and_size(), there is 317 // not proper way to enforce that. 318 #if INCLUDE_NMT 319 if (_stack_base != NULL) { 320 address low_stack_addr = stack_base() - stack_size(); 321 MemTracker::release_thread_stack(low_stack_addr, stack_size()); 322 #ifdef ASSERT 323 set_stack_base(NULL); 324 #endif 325 } 326 #endif // INCLUDE_NMT 327 328 // deallocate data structures 329 delete resource_area(); 330 // since the handle marks are using the handle area, we have to deallocated the root 331 // handle mark before deallocating the thread's handle area, 332 assert(last_handle_mark() != NULL, "check we have an element"); 333 delete last_handle_mark(); 334 assert(last_handle_mark() == NULL, "check we have reached the end"); 335 336 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 337 // We NULL out the fields for good hygiene. 338 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 339 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 340 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 341 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 342 343 delete handle_area(); 344 delete metadata_handles(); 345 346 // osthread() can be NULL, if creation of thread failed. 347 if (osthread() != NULL) os::free_thread(osthread()); 348 349 delete _SR_lock; 350 351 // clear thread local storage if the Thread is deleting itself 352 if (this == Thread::current()) { 353 ThreadLocalStorage::set_thread(NULL); 354 } else { 355 // In the case where we're not the current thread, invalidate all the 356 // caches in case some code tries to get the current thread or the 357 // thread that was destroyed, and gets stale information. 358 ThreadLocalStorage::invalidate_all(); 359 } 360 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 361 } 362 363 // NOTE: dummy function for assertion purpose. 364 void Thread::run() { 365 ShouldNotReachHere(); 366 } 367 368 #ifdef ASSERT 369 // Private method to check for dangling thread pointer 370 void check_for_dangling_thread_pointer(Thread *thread) { 371 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 372 "possibility of dangling Thread pointer"); 373 } 374 #endif 375 376 377 #ifndef PRODUCT 378 // Tracing method for basic thread operations 379 void Thread::trace(const char* msg, const Thread* const thread) { 380 if (!TraceThreadEvents) return; 381 ResourceMark rm; 382 ThreadCritical tc; 383 const char *name = "non-Java thread"; 384 int prio = -1; 385 if (thread->is_Java_thread() 386 && !thread->is_Compiler_thread()) { 387 // The Threads_lock must be held to get information about 388 // this thread but may not be in some situations when 389 // tracing thread events. 390 bool release_Threads_lock = false; 391 if (!Threads_lock->owned_by_self()) { 392 Threads_lock->lock(); 393 release_Threads_lock = true; 394 } 395 JavaThread* jt = (JavaThread *)thread; 396 name = (char *)jt->get_thread_name(); 397 oop thread_oop = jt->threadObj(); 398 if (thread_oop != NULL) { 399 prio = java_lang_Thread::priority(thread_oop); 400 } 401 if (release_Threads_lock) { 402 Threads_lock->unlock(); 403 } 404 } 405 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 406 } 407 #endif 408 409 410 ThreadPriority Thread::get_priority(const Thread* const thread) { 411 trace("get priority", thread); 412 ThreadPriority priority; 413 // Can return an error! 414 (void)os::get_priority(thread, priority); 415 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 416 return priority; 417 } 418 419 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 420 trace("set priority", thread); 421 debug_only(check_for_dangling_thread_pointer(thread);) 422 // Can return an error! 423 (void)os::set_priority(thread, priority); 424 } 425 426 427 void Thread::start(Thread* thread) { 428 trace("start", thread); 429 // Start is different from resume in that its safety is guaranteed by context or 430 // being called from a Java method synchronized on the Thread object. 431 if (!DisableStartThread) { 432 if (thread->is_Java_thread()) { 433 // Initialize the thread state to RUNNABLE before starting this thread. 434 // Can not set it after the thread started because we do not know the 435 // exact thread state at that time. It could be in MONITOR_WAIT or 436 // in SLEEPING or some other state. 437 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 438 java_lang_Thread::RUNNABLE); 439 } 440 os::start_thread(thread); 441 } 442 } 443 444 // Enqueue a VM_Operation to do the job for us - sometime later 445 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 446 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 447 VMThread::execute(vm_stop); 448 } 449 450 451 // Check if an external suspend request has completed (or has been 452 // cancelled). Returns true if the thread is externally suspended and 453 // false otherwise. 454 // 455 // The bits parameter returns information about the code path through 456 // the routine. Useful for debugging: 457 // 458 // set in is_ext_suspend_completed(): 459 // 0x00000001 - routine was entered 460 // 0x00000010 - routine return false at end 461 // 0x00000100 - thread exited (return false) 462 // 0x00000200 - suspend request cancelled (return false) 463 // 0x00000400 - thread suspended (return true) 464 // 0x00001000 - thread is in a suspend equivalent state (return true) 465 // 0x00002000 - thread is native and walkable (return true) 466 // 0x00004000 - thread is native_trans and walkable (needed retry) 467 // 468 // set in wait_for_ext_suspend_completion(): 469 // 0x00010000 - routine was entered 470 // 0x00020000 - suspend request cancelled before loop (return false) 471 // 0x00040000 - thread suspended before loop (return true) 472 // 0x00080000 - suspend request cancelled in loop (return false) 473 // 0x00100000 - thread suspended in loop (return true) 474 // 0x00200000 - suspend not completed during retry loop (return false) 475 476 // Helper class for tracing suspend wait debug bits. 477 // 478 // 0x00000100 indicates that the target thread exited before it could 479 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 480 // 0x00080000 each indicate a cancelled suspend request so they don't 481 // count as wait failures either. 482 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 483 484 class TraceSuspendDebugBits : public StackObj { 485 private: 486 JavaThread * jt; 487 bool is_wait; 488 bool called_by_wait; // meaningful when !is_wait 489 uint32_t * bits; 490 491 public: 492 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 493 uint32_t *_bits) { 494 jt = _jt; 495 is_wait = _is_wait; 496 called_by_wait = _called_by_wait; 497 bits = _bits; 498 } 499 500 ~TraceSuspendDebugBits() { 501 if (!is_wait) { 502 #if 1 503 // By default, don't trace bits for is_ext_suspend_completed() calls. 504 // That trace is very chatty. 505 return; 506 #else 507 if (!called_by_wait) { 508 // If tracing for is_ext_suspend_completed() is enabled, then only 509 // trace calls to it from wait_for_ext_suspend_completion() 510 return; 511 } 512 #endif 513 } 514 515 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 516 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 517 MutexLocker ml(Threads_lock); // needed for get_thread_name() 518 ResourceMark rm; 519 520 tty->print_cr( 521 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 522 jt->get_thread_name(), *bits); 523 524 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 525 } 526 } 527 } 528 }; 529 #undef DEBUG_FALSE_BITS 530 531 532 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 533 uint32_t *bits) { 534 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 535 536 bool did_trans_retry = false; // only do thread_in_native_trans retry once 537 bool do_trans_retry; // flag to force the retry 538 539 *bits |= 0x00000001; 540 541 do { 542 do_trans_retry = false; 543 544 if (is_exiting()) { 545 // Thread is in the process of exiting. This is always checked 546 // first to reduce the risk of dereferencing a freed JavaThread. 547 *bits |= 0x00000100; 548 return false; 549 } 550 551 if (!is_external_suspend()) { 552 // Suspend request is cancelled. This is always checked before 553 // is_ext_suspended() to reduce the risk of a rogue resume 554 // confusing the thread that made the suspend request. 555 *bits |= 0x00000200; 556 return false; 557 } 558 559 if (is_ext_suspended()) { 560 // thread is suspended 561 *bits |= 0x00000400; 562 return true; 563 } 564 565 // Now that we no longer do hard suspends of threads running 566 // native code, the target thread can be changing thread state 567 // while we are in this routine: 568 // 569 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 570 // 571 // We save a copy of the thread state as observed at this moment 572 // and make our decision about suspend completeness based on the 573 // copy. This closes the race where the thread state is seen as 574 // _thread_in_native_trans in the if-thread_blocked check, but is 575 // seen as _thread_blocked in if-thread_in_native_trans check. 576 JavaThreadState save_state = thread_state(); 577 578 if (save_state == _thread_blocked && is_suspend_equivalent()) { 579 // If the thread's state is _thread_blocked and this blocking 580 // condition is known to be equivalent to a suspend, then we can 581 // consider the thread to be externally suspended. This means that 582 // the code that sets _thread_blocked has been modified to do 583 // self-suspension if the blocking condition releases. We also 584 // used to check for CONDVAR_WAIT here, but that is now covered by 585 // the _thread_blocked with self-suspension check. 586 // 587 // Return true since we wouldn't be here unless there was still an 588 // external suspend request. 589 *bits |= 0x00001000; 590 return true; 591 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 592 // Threads running native code will self-suspend on native==>VM/Java 593 // transitions. If its stack is walkable (should always be the case 594 // unless this function is called before the actual java_suspend() 595 // call), then the wait is done. 596 *bits |= 0x00002000; 597 return true; 598 } else if (!called_by_wait && !did_trans_retry && 599 save_state == _thread_in_native_trans && 600 frame_anchor()->walkable()) { 601 // The thread is transitioning from thread_in_native to another 602 // thread state. check_safepoint_and_suspend_for_native_trans() 603 // will force the thread to self-suspend. If it hasn't gotten 604 // there yet we may have caught the thread in-between the native 605 // code check above and the self-suspend. Lucky us. If we were 606 // called by wait_for_ext_suspend_completion(), then it 607 // will be doing the retries so we don't have to. 608 // 609 // Since we use the saved thread state in the if-statement above, 610 // there is a chance that the thread has already transitioned to 611 // _thread_blocked by the time we get here. In that case, we will 612 // make a single unnecessary pass through the logic below. This 613 // doesn't hurt anything since we still do the trans retry. 614 615 *bits |= 0x00004000; 616 617 // Once the thread leaves thread_in_native_trans for another 618 // thread state, we break out of this retry loop. We shouldn't 619 // need this flag to prevent us from getting back here, but 620 // sometimes paranoia is good. 621 did_trans_retry = true; 622 623 // We wait for the thread to transition to a more usable state. 624 for (int i = 1; i <= SuspendRetryCount; i++) { 625 // We used to do an "os::yield_all(i)" call here with the intention 626 // that yielding would increase on each retry. However, the parameter 627 // is ignored on Linux which means the yield didn't scale up. Waiting 628 // on the SR_lock below provides a much more predictable scale up for 629 // the delay. It also provides a simple/direct point to check for any 630 // safepoint requests from the VMThread 631 632 // temporarily drops SR_lock while doing wait with safepoint check 633 // (if we're a JavaThread - the WatcherThread can also call this) 634 // and increase delay with each retry 635 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 636 637 // check the actual thread state instead of what we saved above 638 if (thread_state() != _thread_in_native_trans) { 639 // the thread has transitioned to another thread state so 640 // try all the checks (except this one) one more time. 641 do_trans_retry = true; 642 break; 643 } 644 } // end retry loop 645 646 647 } 648 } while (do_trans_retry); 649 650 *bits |= 0x00000010; 651 return false; 652 } 653 654 // Wait for an external suspend request to complete (or be cancelled). 655 // Returns true if the thread is externally suspended and false otherwise. 656 // 657 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 658 uint32_t *bits) { 659 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 660 false /* !called_by_wait */, bits); 661 662 // local flag copies to minimize SR_lock hold time 663 bool is_suspended; 664 bool pending; 665 uint32_t reset_bits; 666 667 // set a marker so is_ext_suspend_completed() knows we are the caller 668 *bits |= 0x00010000; 669 670 // We use reset_bits to reinitialize the bits value at the top of 671 // each retry loop. This allows the caller to make use of any 672 // unused bits for their own marking purposes. 673 reset_bits = *bits; 674 675 { 676 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 677 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 678 delay, bits); 679 pending = is_external_suspend(); 680 } 681 // must release SR_lock to allow suspension to complete 682 683 if (!pending) { 684 // A cancelled suspend request is the only false return from 685 // is_ext_suspend_completed() that keeps us from entering the 686 // retry loop. 687 *bits |= 0x00020000; 688 return false; 689 } 690 691 if (is_suspended) { 692 *bits |= 0x00040000; 693 return true; 694 } 695 696 for (int i = 1; i <= retries; i++) { 697 *bits = reset_bits; // reinit to only track last retry 698 699 // We used to do an "os::yield_all(i)" call here with the intention 700 // that yielding would increase on each retry. However, the parameter 701 // is ignored on Linux which means the yield didn't scale up. Waiting 702 // on the SR_lock below provides a much more predictable scale up for 703 // the delay. It also provides a simple/direct point to check for any 704 // safepoint requests from the VMThread 705 706 { 707 MutexLocker ml(SR_lock()); 708 // wait with safepoint check (if we're a JavaThread - the WatcherThread 709 // can also call this) and increase delay with each retry 710 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 711 712 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 713 delay, bits); 714 715 // It is possible for the external suspend request to be cancelled 716 // (by a resume) before the actual suspend operation is completed. 717 // Refresh our local copy to see if we still need to wait. 718 pending = is_external_suspend(); 719 } 720 721 if (!pending) { 722 // A cancelled suspend request is the only false return from 723 // is_ext_suspend_completed() that keeps us from staying in the 724 // retry loop. 725 *bits |= 0x00080000; 726 return false; 727 } 728 729 if (is_suspended) { 730 *bits |= 0x00100000; 731 return true; 732 } 733 } // end retry loop 734 735 // thread did not suspend after all our retries 736 *bits |= 0x00200000; 737 return false; 738 } 739 740 #ifndef PRODUCT 741 void JavaThread::record_jump(address target, address instr, const char* file, 742 int line) { 743 744 // This should not need to be atomic as the only way for simultaneous 745 // updates is via interrupts. Even then this should be rare or non-existent 746 // and we don't care that much anyway. 747 748 int index = _jmp_ring_index; 749 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 750 _jmp_ring[index]._target = (intptr_t) target; 751 _jmp_ring[index]._instruction = (intptr_t) instr; 752 _jmp_ring[index]._file = file; 753 _jmp_ring[index]._line = line; 754 } 755 #endif // PRODUCT 756 757 // Called by flat profiler 758 // Callers have already called wait_for_ext_suspend_completion 759 // The assertion for that is currently too complex to put here: 760 bool JavaThread::profile_last_Java_frame(frame* _fr) { 761 bool gotframe = false; 762 // self suspension saves needed state. 763 if (has_last_Java_frame() && _anchor.walkable()) { 764 *_fr = pd_last_frame(); 765 gotframe = true; 766 } 767 return gotframe; 768 } 769 770 void Thread::interrupt(Thread* thread) { 771 trace("interrupt", thread); 772 debug_only(check_for_dangling_thread_pointer(thread);) 773 os::interrupt(thread); 774 } 775 776 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 777 trace("is_interrupted", thread); 778 debug_only(check_for_dangling_thread_pointer(thread);) 779 // Note: If clear_interrupted==false, this simply fetches and 780 // returns the value of the field osthread()->interrupted(). 781 return os::is_interrupted(thread, clear_interrupted); 782 } 783 784 785 // GC Support 786 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 787 jint thread_parity = _oops_do_parity; 788 if (thread_parity != strong_roots_parity) { 789 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 790 if (res == thread_parity) { 791 return true; 792 } else { 793 guarantee(res == strong_roots_parity, "Or else what?"); 794 assert(SharedHeap::heap()->workers()->active_workers() > 0, 795 "Should only fail when parallel."); 796 return false; 797 } 798 } 799 assert(SharedHeap::heap()->workers()->active_workers() > 0, 800 "Should only fail when parallel."); 801 return false; 802 } 803 804 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 805 active_handles()->oops_do(f); 806 // Do oop for ThreadShadow 807 f->do_oop((oop*)&_pending_exception); 808 handle_area()->oops_do(f); 809 } 810 811 void Thread::nmethods_do(CodeBlobClosure* cf) { 812 // no nmethods in a generic thread... 813 } 814 815 void Thread::metadata_do(void f(Metadata*)) { 816 if (metadata_handles() != NULL) { 817 for (int i = 0; i< metadata_handles()->length(); i++) { 818 f(metadata_handles()->at(i)); 819 } 820 } 821 } 822 823 void Thread::print_on(outputStream* st) const { 824 // get_priority assumes osthread initialized 825 if (osthread() != NULL) { 826 int os_prio; 827 if (os::get_native_priority(this, &os_prio) == OS_OK) { 828 st->print("os_prio=%d ", os_prio); 829 } 830 st->print("tid=" INTPTR_FORMAT " ", this); 831 ext().print_on(st); 832 osthread()->print_on(st); 833 } 834 debug_only(if (WizardMode) print_owned_locks_on(st);) 835 } 836 837 // Thread::print_on_error() is called by fatal error handler. Don't use 838 // any lock or allocate memory. 839 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 840 if (is_VM_thread()) st->print("VMThread"); 841 else if (is_Compiler_thread()) st->print("CompilerThread"); 842 else if (is_Java_thread()) st->print("JavaThread"); 843 else if (is_GC_task_thread()) st->print("GCTaskThread"); 844 else if (is_Watcher_thread()) st->print("WatcherThread"); 845 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 846 else st->print("Thread"); 847 848 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 849 _stack_base - _stack_size, _stack_base); 850 851 if (osthread()) { 852 st->print(" [id=%d]", osthread()->thread_id()); 853 } 854 } 855 856 #ifdef ASSERT 857 void Thread::print_owned_locks_on(outputStream* st) const { 858 Monitor *cur = _owned_locks; 859 if (cur == NULL) { 860 st->print(" (no locks) "); 861 } else { 862 st->print_cr(" Locks owned:"); 863 while (cur) { 864 cur->print_on(st); 865 cur = cur->next(); 866 } 867 } 868 } 869 870 static int ref_use_count = 0; 871 872 bool Thread::owns_locks_but_compiled_lock() const { 873 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 874 if (cur != Compile_lock) return true; 875 } 876 return false; 877 } 878 879 880 #endif 881 882 #ifndef PRODUCT 883 884 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 885 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 886 // no threads which allow_vm_block's are held 887 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 888 // Check if current thread is allowed to block at a safepoint 889 if (!(_allow_safepoint_count == 0)) { 890 fatal("Possible safepoint reached by thread that does not allow it"); 891 } 892 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 893 fatal("LEAF method calling lock?"); 894 } 895 896 #ifdef ASSERT 897 if (potential_vm_operation && is_Java_thread() 898 && !Universe::is_bootstrapping()) { 899 // Make sure we do not hold any locks that the VM thread also uses. 900 // This could potentially lead to deadlocks 901 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 902 // Threads_lock is special, since the safepoint synchronization will not start before this is 903 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 904 // since it is used to transfer control between JavaThreads and the VMThread 905 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 906 if ((cur->allow_vm_block() && 907 cur != Threads_lock && 908 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 909 cur != VMOperationRequest_lock && 910 cur != VMOperationQueue_lock) || 911 cur->rank() == Mutex::special) { 912 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); 913 } 914 } 915 } 916 917 if (GCALotAtAllSafepoints) { 918 // We could enter a safepoint here and thus have a gc 919 InterfaceSupport::check_gc_alot(); 920 } 921 #endif 922 } 923 #endif 924 925 bool Thread::is_in_stack(address adr) const { 926 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 927 address end = os::current_stack_pointer(); 928 // Allow non Java threads to call this without stack_base 929 if (_stack_base == NULL) return true; 930 if (stack_base() >= adr && adr >= end) return true; 931 932 return false; 933 } 934 935 936 bool Thread::is_in_usable_stack(address adr) const { 937 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; 938 size_t usable_stack_size = _stack_size - stack_guard_size; 939 940 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 941 } 942 943 944 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 945 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 946 // used for compilation in the future. If that change is made, the need for these methods 947 // should be revisited, and they should be removed if possible. 948 949 bool Thread::is_lock_owned(address adr) const { 950 return on_local_stack(adr); 951 } 952 953 bool Thread::set_as_starting_thread() { 954 // NOTE: this must be called inside the main thread. 955 return os::create_main_thread((JavaThread*)this); 956 } 957 958 static void initialize_class(Symbol* class_name, TRAPS) { 959 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 960 InstanceKlass::cast(klass)->initialize(CHECK); 961 } 962 963 964 // Creates the initial ThreadGroup 965 static Handle create_initial_thread_group(TRAPS) { 966 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 967 instanceKlassHandle klass (THREAD, k); 968 969 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 970 { 971 JavaValue result(T_VOID); 972 JavaCalls::call_special(&result, 973 system_instance, 974 klass, 975 vmSymbols::object_initializer_name(), 976 vmSymbols::void_method_signature(), 977 CHECK_NH); 978 } 979 Universe::set_system_thread_group(system_instance()); 980 981 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 982 { 983 JavaValue result(T_VOID); 984 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 985 JavaCalls::call_special(&result, 986 main_instance, 987 klass, 988 vmSymbols::object_initializer_name(), 989 vmSymbols::threadgroup_string_void_signature(), 990 system_instance, 991 string, 992 CHECK_NH); 993 } 994 return main_instance; 995 } 996 997 // Creates the initial Thread 998 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 999 TRAPS) { 1000 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1001 instanceKlassHandle klass (THREAD, k); 1002 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 1003 1004 java_lang_Thread::set_thread(thread_oop(), thread); 1005 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1006 thread->set_threadObj(thread_oop()); 1007 1008 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1009 1010 JavaValue result(T_VOID); 1011 JavaCalls::call_special(&result, thread_oop, 1012 klass, 1013 vmSymbols::object_initializer_name(), 1014 vmSymbols::threadgroup_string_void_signature(), 1015 thread_group, 1016 string, 1017 CHECK_NULL); 1018 return thread_oop(); 1019 } 1020 1021 static void call_initializeSystemClass(TRAPS) { 1022 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1023 instanceKlassHandle klass (THREAD, k); 1024 1025 JavaValue result(T_VOID); 1026 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 1027 vmSymbols::void_method_signature(), CHECK); 1028 } 1029 1030 char java_runtime_name[128] = ""; 1031 char java_runtime_version[128] = ""; 1032 1033 // extract the JRE name from sun.misc.Version.java_runtime_name 1034 static const char* get_java_runtime_name(TRAPS) { 1035 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1036 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1037 fieldDescriptor fd; 1038 bool found = k != NULL && 1039 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1040 vmSymbols::string_signature(), &fd); 1041 if (found) { 1042 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1043 if (name_oop == NULL) { 1044 return NULL; 1045 } 1046 const char* name = java_lang_String::as_utf8_string(name_oop, 1047 java_runtime_name, 1048 sizeof(java_runtime_name)); 1049 return name; 1050 } else { 1051 return NULL; 1052 } 1053 } 1054 1055 // extract the JRE version from sun.misc.Version.java_runtime_version 1056 static const char* get_java_runtime_version(TRAPS) { 1057 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1058 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1059 fieldDescriptor fd; 1060 bool found = k != NULL && 1061 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1062 vmSymbols::string_signature(), &fd); 1063 if (found) { 1064 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1065 if (name_oop == NULL) { 1066 return NULL; 1067 } 1068 const char* name = java_lang_String::as_utf8_string(name_oop, 1069 java_runtime_version, 1070 sizeof(java_runtime_version)); 1071 return name; 1072 } else { 1073 return NULL; 1074 } 1075 } 1076 1077 // General purpose hook into Java code, run once when the VM is initialized. 1078 // The Java library method itself may be changed independently from the VM. 1079 static void call_postVMInitHook(TRAPS) { 1080 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1081 instanceKlassHandle klass (THREAD, k); 1082 if (klass.not_null()) { 1083 JavaValue result(T_VOID); 1084 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1085 vmSymbols::void_method_signature(), 1086 CHECK); 1087 } 1088 } 1089 1090 static void reset_vm_info_property(TRAPS) { 1091 // the vm info string 1092 ResourceMark rm(THREAD); 1093 const char *vm_info = VM_Version::vm_info_string(); 1094 1095 // java.lang.System class 1096 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1097 instanceKlassHandle klass (THREAD, k); 1098 1099 // setProperty arguments 1100 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1101 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1102 1103 // return value 1104 JavaValue r(T_OBJECT); 1105 1106 // public static String setProperty(String key, String value); 1107 JavaCalls::call_static(&r, 1108 klass, 1109 vmSymbols::setProperty_name(), 1110 vmSymbols::string_string_string_signature(), 1111 key_str, 1112 value_str, 1113 CHECK); 1114 } 1115 1116 1117 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, 1118 bool daemon, TRAPS) { 1119 assert(thread_group.not_null(), "thread group should be specified"); 1120 assert(threadObj() == NULL, "should only create Java thread object once"); 1121 1122 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1123 instanceKlassHandle klass (THREAD, k); 1124 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1125 1126 java_lang_Thread::set_thread(thread_oop(), this); 1127 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1128 set_threadObj(thread_oop()); 1129 1130 JavaValue result(T_VOID); 1131 if (thread_name != NULL) { 1132 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1133 // Thread gets assigned specified name and null target 1134 JavaCalls::call_special(&result, 1135 thread_oop, 1136 klass, 1137 vmSymbols::object_initializer_name(), 1138 vmSymbols::threadgroup_string_void_signature(), 1139 thread_group, // Argument 1 1140 name, // Argument 2 1141 THREAD); 1142 } else { 1143 // Thread gets assigned name "Thread-nnn" and null target 1144 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1145 JavaCalls::call_special(&result, 1146 thread_oop, 1147 klass, 1148 vmSymbols::object_initializer_name(), 1149 vmSymbols::threadgroup_runnable_void_signature(), 1150 thread_group, // Argument 1 1151 Handle(), // Argument 2 1152 THREAD); 1153 } 1154 1155 1156 if (daemon) { 1157 java_lang_Thread::set_daemon(thread_oop()); 1158 } 1159 1160 if (HAS_PENDING_EXCEPTION) { 1161 return; 1162 } 1163 1164 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1165 Handle threadObj(this, this->threadObj()); 1166 1167 JavaCalls::call_special(&result, 1168 thread_group, 1169 group, 1170 vmSymbols::add_method_name(), 1171 vmSymbols::thread_void_signature(), 1172 threadObj, // Arg 1 1173 THREAD); 1174 1175 1176 } 1177 1178 // NamedThread -- non-JavaThread subclasses with multiple 1179 // uniquely named instances should derive from this. 1180 NamedThread::NamedThread() : Thread() { 1181 _name = NULL; 1182 _processed_thread = NULL; 1183 } 1184 1185 NamedThread::~NamedThread() { 1186 if (_name != NULL) { 1187 FREE_C_HEAP_ARRAY(char, _name, mtThread); 1188 _name = NULL; 1189 } 1190 } 1191 1192 void NamedThread::set_name(const char* format, ...) { 1193 guarantee(_name == NULL, "Only get to set name once."); 1194 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1195 guarantee(_name != NULL, "alloc failure"); 1196 va_list ap; 1197 va_start(ap, format); 1198 jio_vsnprintf(_name, max_name_len, format, ap); 1199 va_end(ap); 1200 } 1201 1202 void NamedThread::print_on(outputStream* st) const { 1203 st->print("\"%s\" ", name()); 1204 Thread::print_on(st); 1205 st->cr(); 1206 } 1207 1208 1209 // ======= WatcherThread ======== 1210 1211 // The watcher thread exists to simulate timer interrupts. It should 1212 // be replaced by an abstraction over whatever native support for 1213 // timer interrupts exists on the platform. 1214 1215 WatcherThread* WatcherThread::_watcher_thread = NULL; 1216 bool WatcherThread::_startable = false; 1217 volatile bool WatcherThread::_should_terminate = false; 1218 1219 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1220 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1221 if (os::create_thread(this, os::watcher_thread)) { 1222 _watcher_thread = this; 1223 1224 // Set the watcher thread to the highest OS priority which should not be 1225 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1226 // is created. The only normal thread using this priority is the reference 1227 // handler thread, which runs for very short intervals only. 1228 // If the VMThread's priority is not lower than the WatcherThread profiling 1229 // will be inaccurate. 1230 os::set_priority(this, MaxPriority); 1231 if (!DisableStartThread) { 1232 os::start_thread(this); 1233 } 1234 } 1235 } 1236 1237 int WatcherThread::sleep() const { 1238 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1239 1240 // remaining will be zero if there are no tasks, 1241 // causing the WatcherThread to sleep until a task is 1242 // enrolled 1243 int remaining = PeriodicTask::time_to_wait(); 1244 int time_slept = 0; 1245 1246 // we expect this to timeout - we only ever get unparked when 1247 // we should terminate or when a new task has been enrolled 1248 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1249 1250 jlong time_before_loop = os::javaTimeNanos(); 1251 1252 for (;;) { 1253 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); 1254 jlong now = os::javaTimeNanos(); 1255 1256 if (remaining == 0) { 1257 // if we didn't have any tasks we could have waited for a long time 1258 // consider the time_slept zero and reset time_before_loop 1259 time_slept = 0; 1260 time_before_loop = now; 1261 } else { 1262 // need to recalculate since we might have new tasks in _tasks 1263 time_slept = (int) ((now - time_before_loop) / 1000000); 1264 } 1265 1266 // Change to task list or spurious wakeup of some kind 1267 if (timedout || _should_terminate) { 1268 break; 1269 } 1270 1271 remaining = PeriodicTask::time_to_wait(); 1272 if (remaining == 0) { 1273 // Last task was just disenrolled so loop around and wait until 1274 // another task gets enrolled 1275 continue; 1276 } 1277 1278 remaining -= time_slept; 1279 if (remaining <= 0) { 1280 break; 1281 } 1282 } 1283 1284 return time_slept; 1285 } 1286 1287 void WatcherThread::run() { 1288 assert(this == watcher_thread(), "just checking"); 1289 1290 this->record_stack_base_and_size(); 1291 this->initialize_thread_local_storage(); 1292 this->set_native_thread_name(this->name()); 1293 this->set_active_handles(JNIHandleBlock::allocate_block()); 1294 while (!_should_terminate) { 1295 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1296 assert(watcher_thread() == this, "thread consistency check"); 1297 1298 // Calculate how long it'll be until the next PeriodicTask work 1299 // should be done, and sleep that amount of time. 1300 int time_waited = sleep(); 1301 1302 if (is_error_reported()) { 1303 // A fatal error has happened, the error handler(VMError::report_and_die) 1304 // should abort JVM after creating an error log file. However in some 1305 // rare cases, the error handler itself might deadlock. Here we try to 1306 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1307 // 1308 // This code is in WatcherThread because WatcherThread wakes up 1309 // periodically so the fatal error handler doesn't need to do anything; 1310 // also because the WatcherThread is less likely to crash than other 1311 // threads. 1312 1313 for (;;) { 1314 if (!ShowMessageBoxOnError 1315 && (OnError == NULL || OnError[0] == '\0') 1316 && Arguments::abort_hook() == NULL) { 1317 os::sleep(this, 2 * 60 * 1000, false); 1318 fdStream err(defaultStream::output_fd()); 1319 err.print_raw_cr("# [ timer expired, abort... ]"); 1320 // skip atexit/vm_exit/vm_abort hooks 1321 os::die(); 1322 } 1323 1324 // Wake up 5 seconds later, the fatal handler may reset OnError or 1325 // ShowMessageBoxOnError when it is ready to abort. 1326 os::sleep(this, 5 * 1000, false); 1327 } 1328 } 1329 1330 PeriodicTask::real_time_tick(time_waited); 1331 } 1332 1333 // Signal that it is terminated 1334 { 1335 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1336 _watcher_thread = NULL; 1337 Terminator_lock->notify(); 1338 } 1339 1340 // Thread destructor usually does this.. 1341 ThreadLocalStorage::set_thread(NULL); 1342 } 1343 1344 void WatcherThread::start() { 1345 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1346 1347 if (watcher_thread() == NULL && _startable) { 1348 _should_terminate = false; 1349 // Create the single instance of WatcherThread 1350 new WatcherThread(); 1351 } 1352 } 1353 1354 void WatcherThread::make_startable() { 1355 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1356 _startable = true; 1357 } 1358 1359 void WatcherThread::stop() { 1360 // Get the PeriodicTask_lock if we can. If we cannot, then the 1361 // WatcherThread is using it and we don't want to block on that lock 1362 // here because that might cause a safepoint deadlock depending on 1363 // what the current WatcherThread tasks are doing. 1364 bool have_lock = PeriodicTask_lock->try_lock(); 1365 1366 _should_terminate = true; 1367 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1368 1369 if (have_lock) { 1370 WatcherThread* watcher = watcher_thread(); 1371 if (watcher != NULL) { 1372 // If we managed to get the lock, then we should unpark the 1373 // WatcherThread so that it can see we want it to stop. 1374 watcher->unpark(); 1375 } 1376 1377 PeriodicTask_lock->unlock(); 1378 } 1379 1380 // it is ok to take late safepoints here, if needed 1381 MutexLocker mu(Terminator_lock); 1382 1383 while (watcher_thread() != NULL) { 1384 // This wait should make safepoint checks, wait without a timeout, 1385 // and wait as a suspend-equivalent condition. 1386 // 1387 // Note: If the FlatProfiler is running, then this thread is waiting 1388 // for the WatcherThread to terminate and the WatcherThread, via the 1389 // FlatProfiler task, is waiting for the external suspend request on 1390 // this thread to complete. wait_for_ext_suspend_completion() will 1391 // eventually timeout, but that takes time. Making this wait a 1392 // suspend-equivalent condition solves that timeout problem. 1393 // 1394 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1395 Mutex::_as_suspend_equivalent_flag); 1396 } 1397 } 1398 1399 void WatcherThread::unpark() { 1400 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() 1401 ? NULL 1402 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1403 PeriodicTask_lock->notify(); 1404 } 1405 1406 void WatcherThread::print_on(outputStream* st) const { 1407 st->print("\"%s\" ", name()); 1408 Thread::print_on(st); 1409 st->cr(); 1410 } 1411 1412 // ======= JavaThread ======== 1413 1414 // A JavaThread is a normal Java thread 1415 1416 void JavaThread::initialize() { 1417 // Initialize fields 1418 1419 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) 1420 set_claimed_par_id(UINT_MAX); 1421 1422 set_saved_exception_pc(NULL); 1423 set_threadObj(NULL); 1424 _anchor.clear(); 1425 set_entry_point(NULL); 1426 set_jni_functions(jni_functions()); 1427 set_callee_target(NULL); 1428 set_vm_result(NULL); 1429 set_vm_result_2(NULL); 1430 set_vframe_array_head(NULL); 1431 set_vframe_array_last(NULL); 1432 set_deferred_locals(NULL); 1433 set_deopt_mark(NULL); 1434 set_deopt_nmethod(NULL); 1435 clear_must_deopt_id(); 1436 set_monitor_chunks(NULL); 1437 set_next(NULL); 1438 set_thread_state(_thread_new); 1439 _terminated = _not_terminated; 1440 _privileged_stack_top = NULL; 1441 _array_for_gc = NULL; 1442 _suspend_equivalent = false; 1443 _in_deopt_handler = 0; 1444 _doing_unsafe_access = false; 1445 _stack_guard_state = stack_guard_unused; 1446 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1447 _exception_pc = 0; 1448 _exception_handler_pc = 0; 1449 _is_method_handle_return = 0; 1450 _jvmti_thread_state= NULL; 1451 _should_post_on_exceptions_flag = JNI_FALSE; 1452 _jvmti_get_loaded_classes_closure = NULL; 1453 _interp_only_mode = 0; 1454 _special_runtime_exit_condition = _no_async_condition; 1455 _pending_async_exception = NULL; 1456 _thread_stat = NULL; 1457 _thread_stat = new ThreadStatistics(); 1458 _blocked_on_compilation = false; 1459 _jni_active_critical = 0; 1460 _pending_jni_exception_check_fn = NULL; 1461 _do_not_unlock_if_synchronized = false; 1462 _cached_monitor_info = NULL; 1463 _parker = Parker::Allocate(this); 1464 1465 #ifndef PRODUCT 1466 _jmp_ring_index = 0; 1467 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1468 record_jump(NULL, NULL, NULL, 0); 1469 } 1470 #endif // PRODUCT 1471 1472 set_thread_profiler(NULL); 1473 if (FlatProfiler::is_active()) { 1474 // This is where we would decide to either give each thread it's own profiler 1475 // or use one global one from FlatProfiler, 1476 // or up to some count of the number of profiled threads, etc. 1477 ThreadProfiler* pp = new ThreadProfiler(); 1478 pp->engage(); 1479 set_thread_profiler(pp); 1480 } 1481 1482 // Setup safepoint state info for this thread 1483 ThreadSafepointState::create(this); 1484 1485 debug_only(_java_call_counter = 0); 1486 1487 // JVMTI PopFrame support 1488 _popframe_condition = popframe_inactive; 1489 _popframe_preserved_args = NULL; 1490 _popframe_preserved_args_size = 0; 1491 1492 pd_initialize(); 1493 } 1494 1495 #if INCLUDE_ALL_GCS 1496 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1497 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1498 #endif // INCLUDE_ALL_GCS 1499 1500 JavaThread::JavaThread(bool is_attaching_via_jni) : 1501 Thread() 1502 #if INCLUDE_ALL_GCS 1503 , _satb_mark_queue(&_satb_mark_queue_set), 1504 _dirty_card_queue(&_dirty_card_queue_set) 1505 #endif // INCLUDE_ALL_GCS 1506 { 1507 initialize(); 1508 if (is_attaching_via_jni) { 1509 _jni_attach_state = _attaching_via_jni; 1510 } else { 1511 _jni_attach_state = _not_attaching_via_jni; 1512 } 1513 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1514 } 1515 1516 bool JavaThread::reguard_stack(address cur_sp) { 1517 if (_stack_guard_state != stack_guard_yellow_disabled) { 1518 return true; // Stack already guarded or guard pages not needed. 1519 } 1520 1521 if (register_stack_overflow()) { 1522 // For those architectures which have separate register and 1523 // memory stacks, we must check the register stack to see if 1524 // it has overflowed. 1525 return false; 1526 } 1527 1528 // Java code never executes within the yellow zone: the latter is only 1529 // there to provoke an exception during stack banging. If java code 1530 // is executing there, either StackShadowPages should be larger, or 1531 // some exception code in c1, c2 or the interpreter isn't unwinding 1532 // when it should. 1533 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1534 1535 enable_stack_yellow_zone(); 1536 return true; 1537 } 1538 1539 bool JavaThread::reguard_stack(void) { 1540 return reguard_stack(os::current_stack_pointer()); 1541 } 1542 1543 1544 void JavaThread::block_if_vm_exited() { 1545 if (_terminated == _vm_exited) { 1546 // _vm_exited is set at safepoint, and Threads_lock is never released 1547 // we will block here forever 1548 Threads_lock->lock_without_safepoint_check(); 1549 ShouldNotReachHere(); 1550 } 1551 } 1552 1553 1554 // Remove this ifdef when C1 is ported to the compiler interface. 1555 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1556 1557 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1558 Thread() 1559 #if INCLUDE_ALL_GCS 1560 , _satb_mark_queue(&_satb_mark_queue_set), 1561 _dirty_card_queue(&_dirty_card_queue_set) 1562 #endif // INCLUDE_ALL_GCS 1563 { 1564 if (TraceThreadEvents) { 1565 tty->print_cr("creating thread %p", this); 1566 } 1567 initialize(); 1568 _jni_attach_state = _not_attaching_via_jni; 1569 set_entry_point(entry_point); 1570 // Create the native thread itself. 1571 // %note runtime_23 1572 os::ThreadType thr_type = os::java_thread; 1573 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1574 os::java_thread; 1575 os::create_thread(this, thr_type, stack_sz); 1576 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1577 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1578 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1579 // the exception consists of creating the exception object & initializing it, initialization 1580 // will leave the VM via a JavaCall and then all locks must be unlocked). 1581 // 1582 // The thread is still suspended when we reach here. Thread must be explicit started 1583 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1584 // by calling Threads:add. The reason why this is not done here, is because the thread 1585 // object must be fully initialized (take a look at JVM_Start) 1586 } 1587 1588 JavaThread::~JavaThread() { 1589 if (TraceThreadEvents) { 1590 tty->print_cr("terminate thread %p", this); 1591 } 1592 1593 // JSR166 -- return the parker to the free list 1594 Parker::Release(_parker); 1595 _parker = NULL; 1596 1597 // Free any remaining previous UnrollBlock 1598 vframeArray* old_array = vframe_array_last(); 1599 1600 if (old_array != NULL) { 1601 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1602 old_array->set_unroll_block(NULL); 1603 delete old_info; 1604 delete old_array; 1605 } 1606 1607 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1608 if (deferred != NULL) { 1609 // This can only happen if thread is destroyed before deoptimization occurs. 1610 assert(deferred->length() != 0, "empty array!"); 1611 do { 1612 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1613 deferred->remove_at(0); 1614 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1615 delete dlv; 1616 } while (deferred->length() != 0); 1617 delete deferred; 1618 } 1619 1620 // All Java related clean up happens in exit 1621 ThreadSafepointState::destroy(this); 1622 if (_thread_profiler != NULL) delete _thread_profiler; 1623 if (_thread_stat != NULL) delete _thread_stat; 1624 } 1625 1626 1627 // The first routine called by a new Java thread 1628 void JavaThread::run() { 1629 // initialize thread-local alloc buffer related fields 1630 this->initialize_tlab(); 1631 1632 // used to test validity of stack trace backs 1633 this->record_base_of_stack_pointer(); 1634 1635 // Record real stack base and size. 1636 this->record_stack_base_and_size(); 1637 1638 // Initialize thread local storage; set before calling MutexLocker 1639 this->initialize_thread_local_storage(); 1640 1641 this->create_stack_guard_pages(); 1642 1643 this->cache_global_variables(); 1644 1645 // Thread is now sufficient initialized to be handled by the safepoint code as being 1646 // in the VM. Change thread state from _thread_new to _thread_in_vm 1647 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1648 1649 assert(JavaThread::current() == this, "sanity check"); 1650 assert(!Thread::current()->owns_locks(), "sanity check"); 1651 1652 DTRACE_THREAD_PROBE(start, this); 1653 1654 // This operation might block. We call that after all safepoint checks for a new thread has 1655 // been completed. 1656 this->set_active_handles(JNIHandleBlock::allocate_block()); 1657 1658 if (JvmtiExport::should_post_thread_life()) { 1659 JvmtiExport::post_thread_start(this); 1660 } 1661 1662 EventThreadStart event; 1663 if (event.should_commit()) { 1664 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1665 event.commit(); 1666 } 1667 1668 // We call another function to do the rest so we are sure that the stack addresses used 1669 // from there will be lower than the stack base just computed 1670 thread_main_inner(); 1671 1672 // Note, thread is no longer valid at this point! 1673 } 1674 1675 1676 void JavaThread::thread_main_inner() { 1677 assert(JavaThread::current() == this, "sanity check"); 1678 assert(this->threadObj() != NULL, "just checking"); 1679 1680 // Execute thread entry point unless this thread has a pending exception 1681 // or has been stopped before starting. 1682 // Note: Due to JVM_StopThread we can have pending exceptions already! 1683 if (!this->has_pending_exception() && 1684 !java_lang_Thread::is_stillborn(this->threadObj())) { 1685 { 1686 ResourceMark rm(this); 1687 this->set_native_thread_name(this->get_thread_name()); 1688 } 1689 HandleMark hm(this); 1690 this->entry_point()(this, this); 1691 } 1692 1693 DTRACE_THREAD_PROBE(stop, this); 1694 1695 this->exit(false); 1696 delete this; 1697 } 1698 1699 1700 static void ensure_join(JavaThread* thread) { 1701 // We do not need to grap the Threads_lock, since we are operating on ourself. 1702 Handle threadObj(thread, thread->threadObj()); 1703 assert(threadObj.not_null(), "java thread object must exist"); 1704 ObjectLocker lock(threadObj, thread); 1705 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1706 thread->clear_pending_exception(); 1707 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1708 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1709 // Clear the native thread instance - this makes isAlive return false and allows the join() 1710 // to complete once we've done the notify_all below 1711 java_lang_Thread::set_thread(threadObj(), NULL); 1712 lock.notify_all(thread); 1713 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1714 thread->clear_pending_exception(); 1715 } 1716 1717 1718 // For any new cleanup additions, please check to see if they need to be applied to 1719 // cleanup_failed_attach_current_thread as well. 1720 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1721 assert(this == JavaThread::current(), "thread consistency check"); 1722 1723 HandleMark hm(this); 1724 Handle uncaught_exception(this, this->pending_exception()); 1725 this->clear_pending_exception(); 1726 Handle threadObj(this, this->threadObj()); 1727 assert(threadObj.not_null(), "Java thread object should be created"); 1728 1729 if (get_thread_profiler() != NULL) { 1730 get_thread_profiler()->disengage(); 1731 ResourceMark rm; 1732 get_thread_profiler()->print(get_thread_name()); 1733 } 1734 1735 1736 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1737 { 1738 EXCEPTION_MARK; 1739 1740 CLEAR_PENDING_EXCEPTION; 1741 } 1742 if (!destroy_vm) { 1743 if (uncaught_exception.not_null()) { 1744 EXCEPTION_MARK; 1745 // Call method Thread.dispatchUncaughtException(). 1746 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1747 JavaValue result(T_VOID); 1748 JavaCalls::call_virtual(&result, 1749 threadObj, thread_klass, 1750 vmSymbols::dispatchUncaughtException_name(), 1751 vmSymbols::throwable_void_signature(), 1752 uncaught_exception, 1753 THREAD); 1754 if (HAS_PENDING_EXCEPTION) { 1755 ResourceMark rm(this); 1756 jio_fprintf(defaultStream::error_stream(), 1757 "\nException: %s thrown from the UncaughtExceptionHandler" 1758 " in thread \"%s\"\n", 1759 pending_exception()->klass()->external_name(), 1760 get_thread_name()); 1761 CLEAR_PENDING_EXCEPTION; 1762 } 1763 } 1764 1765 // Called before the java thread exit since we want to read info 1766 // from java_lang_Thread object 1767 EventThreadEnd event; 1768 if (event.should_commit()) { 1769 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1770 event.commit(); 1771 } 1772 1773 // Call after last event on thread 1774 EVENT_THREAD_EXIT(this); 1775 1776 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1777 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1778 // is deprecated anyhow. 1779 if (!is_Compiler_thread()) { 1780 int count = 3; 1781 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1782 EXCEPTION_MARK; 1783 JavaValue result(T_VOID); 1784 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1785 JavaCalls::call_virtual(&result, 1786 threadObj, thread_klass, 1787 vmSymbols::exit_method_name(), 1788 vmSymbols::void_method_signature(), 1789 THREAD); 1790 CLEAR_PENDING_EXCEPTION; 1791 } 1792 } 1793 // notify JVMTI 1794 if (JvmtiExport::should_post_thread_life()) { 1795 JvmtiExport::post_thread_end(this); 1796 } 1797 1798 // We have notified the agents that we are exiting, before we go on, 1799 // we must check for a pending external suspend request and honor it 1800 // in order to not surprise the thread that made the suspend request. 1801 while (true) { 1802 { 1803 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1804 if (!is_external_suspend()) { 1805 set_terminated(_thread_exiting); 1806 ThreadService::current_thread_exiting(this); 1807 break; 1808 } 1809 // Implied else: 1810 // Things get a little tricky here. We have a pending external 1811 // suspend request, but we are holding the SR_lock so we 1812 // can't just self-suspend. So we temporarily drop the lock 1813 // and then self-suspend. 1814 } 1815 1816 ThreadBlockInVM tbivm(this); 1817 java_suspend_self(); 1818 1819 // We're done with this suspend request, but we have to loop around 1820 // and check again. Eventually we will get SR_lock without a pending 1821 // external suspend request and will be able to mark ourselves as 1822 // exiting. 1823 } 1824 // no more external suspends are allowed at this point 1825 } else { 1826 // before_exit() has already posted JVMTI THREAD_END events 1827 } 1828 1829 // Notify waiters on thread object. This has to be done after exit() is called 1830 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1831 // group should have the destroyed bit set before waiters are notified). 1832 ensure_join(this); 1833 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1834 1835 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1836 // held by this thread must be released. A detach operation must only 1837 // get here if there are no Java frames on the stack. Therefore, any 1838 // owned monitors at this point MUST be JNI-acquired monitors which are 1839 // pre-inflated and in the monitor cache. 1840 // 1841 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1842 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1843 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1844 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1845 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1846 } 1847 1848 // These things needs to be done while we are still a Java Thread. Make sure that thread 1849 // is in a consistent state, in case GC happens 1850 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1851 1852 if (active_handles() != NULL) { 1853 JNIHandleBlock* block = active_handles(); 1854 set_active_handles(NULL); 1855 JNIHandleBlock::release_block(block); 1856 } 1857 1858 if (free_handle_block() != NULL) { 1859 JNIHandleBlock* block = free_handle_block(); 1860 set_free_handle_block(NULL); 1861 JNIHandleBlock::release_block(block); 1862 } 1863 1864 // These have to be removed while this is still a valid thread. 1865 remove_stack_guard_pages(); 1866 1867 if (UseTLAB) { 1868 tlab().make_parsable(true); // retire TLAB 1869 } 1870 1871 if (JvmtiEnv::environments_might_exist()) { 1872 JvmtiExport::cleanup_thread(this); 1873 } 1874 1875 // We must flush any deferred card marks before removing a thread from 1876 // the list of active threads. 1877 Universe::heap()->flush_deferred_store_barrier(this); 1878 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1879 1880 #if INCLUDE_ALL_GCS 1881 // We must flush the G1-related buffers before removing a thread 1882 // from the list of active threads. We must do this after any deferred 1883 // card marks have been flushed (above) so that any entries that are 1884 // added to the thread's dirty card queue as a result are not lost. 1885 if (UseG1GC) { 1886 flush_barrier_queues(); 1887 } 1888 #endif // INCLUDE_ALL_GCS 1889 1890 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1891 Threads::remove(this); 1892 } 1893 1894 #if INCLUDE_ALL_GCS 1895 // Flush G1-related queues. 1896 void JavaThread::flush_barrier_queues() { 1897 satb_mark_queue().flush(); 1898 dirty_card_queue().flush(); 1899 } 1900 1901 void JavaThread::initialize_queues() { 1902 assert(!SafepointSynchronize::is_at_safepoint(), 1903 "we should not be at a safepoint"); 1904 1905 ObjPtrQueue& satb_queue = satb_mark_queue(); 1906 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1907 // The SATB queue should have been constructed with its active 1908 // field set to false. 1909 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1910 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1911 // If we are creating the thread during a marking cycle, we should 1912 // set the active field of the SATB queue to true. 1913 if (satb_queue_set.is_active()) { 1914 satb_queue.set_active(true); 1915 } 1916 1917 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1918 // The dirty card queue should have been constructed with its 1919 // active field set to true. 1920 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1921 } 1922 #endif // INCLUDE_ALL_GCS 1923 1924 void JavaThread::cleanup_failed_attach_current_thread() { 1925 if (get_thread_profiler() != NULL) { 1926 get_thread_profiler()->disengage(); 1927 ResourceMark rm; 1928 get_thread_profiler()->print(get_thread_name()); 1929 } 1930 1931 if (active_handles() != NULL) { 1932 JNIHandleBlock* block = active_handles(); 1933 set_active_handles(NULL); 1934 JNIHandleBlock::release_block(block); 1935 } 1936 1937 if (free_handle_block() != NULL) { 1938 JNIHandleBlock* block = free_handle_block(); 1939 set_free_handle_block(NULL); 1940 JNIHandleBlock::release_block(block); 1941 } 1942 1943 // These have to be removed while this is still a valid thread. 1944 remove_stack_guard_pages(); 1945 1946 if (UseTLAB) { 1947 tlab().make_parsable(true); // retire TLAB, if any 1948 } 1949 1950 #if INCLUDE_ALL_GCS 1951 if (UseG1GC) { 1952 flush_barrier_queues(); 1953 } 1954 #endif // INCLUDE_ALL_GCS 1955 1956 Threads::remove(this); 1957 delete this; 1958 } 1959 1960 1961 1962 1963 JavaThread* JavaThread::active() { 1964 Thread* thread = ThreadLocalStorage::thread(); 1965 assert(thread != NULL, "just checking"); 1966 if (thread->is_Java_thread()) { 1967 return (JavaThread*) thread; 1968 } else { 1969 assert(thread->is_VM_thread(), "this must be a vm thread"); 1970 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1971 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1972 assert(ret->is_Java_thread(), "must be a Java thread"); 1973 return ret; 1974 } 1975 } 1976 1977 bool JavaThread::is_lock_owned(address adr) const { 1978 if (Thread::is_lock_owned(adr)) return true; 1979 1980 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1981 if (chunk->contains(adr)) return true; 1982 } 1983 1984 return false; 1985 } 1986 1987 1988 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1989 chunk->set_next(monitor_chunks()); 1990 set_monitor_chunks(chunk); 1991 } 1992 1993 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1994 guarantee(monitor_chunks() != NULL, "must be non empty"); 1995 if (monitor_chunks() == chunk) { 1996 set_monitor_chunks(chunk->next()); 1997 } else { 1998 MonitorChunk* prev = monitor_chunks(); 1999 while (prev->next() != chunk) prev = prev->next(); 2000 prev->set_next(chunk->next()); 2001 } 2002 } 2003 2004 // JVM support. 2005 2006 // Note: this function shouldn't block if it's called in 2007 // _thread_in_native_trans state (such as from 2008 // check_special_condition_for_native_trans()). 2009 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2010 2011 if (has_last_Java_frame() && has_async_condition()) { 2012 // If we are at a polling page safepoint (not a poll return) 2013 // then we must defer async exception because live registers 2014 // will be clobbered by the exception path. Poll return is 2015 // ok because the call we a returning from already collides 2016 // with exception handling registers and so there is no issue. 2017 // (The exception handling path kills call result registers but 2018 // this is ok since the exception kills the result anyway). 2019 2020 if (is_at_poll_safepoint()) { 2021 // if the code we are returning to has deoptimized we must defer 2022 // the exception otherwise live registers get clobbered on the 2023 // exception path before deoptimization is able to retrieve them. 2024 // 2025 RegisterMap map(this, false); 2026 frame caller_fr = last_frame().sender(&map); 2027 assert(caller_fr.is_compiled_frame(), "what?"); 2028 if (caller_fr.is_deoptimized_frame()) { 2029 if (TraceExceptions) { 2030 ResourceMark rm; 2031 tty->print_cr("deferred async exception at compiled safepoint"); 2032 } 2033 return; 2034 } 2035 } 2036 } 2037 2038 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2039 if (condition == _no_async_condition) { 2040 // Conditions have changed since has_special_runtime_exit_condition() 2041 // was called: 2042 // - if we were here only because of an external suspend request, 2043 // then that was taken care of above (or cancelled) so we are done 2044 // - if we were here because of another async request, then it has 2045 // been cleared between the has_special_runtime_exit_condition() 2046 // and now so again we are done 2047 return; 2048 } 2049 2050 // Check for pending async. exception 2051 if (_pending_async_exception != NULL) { 2052 // Only overwrite an already pending exception, if it is not a threadDeath. 2053 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2054 2055 // We cannot call Exceptions::_throw(...) here because we cannot block 2056 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2057 2058 if (TraceExceptions) { 2059 ResourceMark rm; 2060 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 2061 if (has_last_Java_frame()) { 2062 frame f = last_frame(); 2063 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 2064 } 2065 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2066 } 2067 _pending_async_exception = NULL; 2068 clear_has_async_exception(); 2069 } 2070 } 2071 2072 if (check_unsafe_error && 2073 condition == _async_unsafe_access_error && !has_pending_exception()) { 2074 condition = _no_async_condition; // done 2075 switch (thread_state()) { 2076 case _thread_in_vm: { 2077 JavaThread* THREAD = this; 2078 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2079 } 2080 case _thread_in_native: { 2081 ThreadInVMfromNative tiv(this); 2082 JavaThread* THREAD = this; 2083 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2084 } 2085 case _thread_in_Java: { 2086 ThreadInVMfromJava tiv(this); 2087 JavaThread* THREAD = this; 2088 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2089 } 2090 default: 2091 ShouldNotReachHere(); 2092 } 2093 } 2094 2095 assert(condition == _no_async_condition || has_pending_exception() || 2096 (!check_unsafe_error && condition == _async_unsafe_access_error), 2097 "must have handled the async condition, if no exception"); 2098 } 2099 2100 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2101 // 2102 // Check for pending external suspend. Internal suspend requests do 2103 // not use handle_special_runtime_exit_condition(). 2104 // If JNIEnv proxies are allowed, don't self-suspend if the target 2105 // thread is not the current thread. In older versions of jdbx, jdbx 2106 // threads could call into the VM with another thread's JNIEnv so we 2107 // can be here operating on behalf of a suspended thread (4432884). 2108 bool do_self_suspend = is_external_suspend_with_lock(); 2109 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2110 // 2111 // Because thread is external suspended the safepoint code will count 2112 // thread as at a safepoint. This can be odd because we can be here 2113 // as _thread_in_Java which would normally transition to _thread_blocked 2114 // at a safepoint. We would like to mark the thread as _thread_blocked 2115 // before calling java_suspend_self like all other callers of it but 2116 // we must then observe proper safepoint protocol. (We can't leave 2117 // _thread_blocked with a safepoint in progress). However we can be 2118 // here as _thread_in_native_trans so we can't use a normal transition 2119 // constructor/destructor pair because they assert on that type of 2120 // transition. We could do something like: 2121 // 2122 // JavaThreadState state = thread_state(); 2123 // set_thread_state(_thread_in_vm); 2124 // { 2125 // ThreadBlockInVM tbivm(this); 2126 // java_suspend_self() 2127 // } 2128 // set_thread_state(_thread_in_vm_trans); 2129 // if (safepoint) block; 2130 // set_thread_state(state); 2131 // 2132 // but that is pretty messy. Instead we just go with the way the 2133 // code has worked before and note that this is the only path to 2134 // java_suspend_self that doesn't put the thread in _thread_blocked 2135 // mode. 2136 2137 frame_anchor()->make_walkable(this); 2138 java_suspend_self(); 2139 2140 // We might be here for reasons in addition to the self-suspend request 2141 // so check for other async requests. 2142 } 2143 2144 if (check_asyncs) { 2145 check_and_handle_async_exceptions(); 2146 } 2147 } 2148 2149 void JavaThread::send_thread_stop(oop java_throwable) { 2150 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2151 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2152 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2153 2154 // Do not throw asynchronous exceptions against the compiler thread 2155 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2156 if (is_Compiler_thread()) return; 2157 2158 { 2159 // Actually throw the Throwable against the target Thread - however 2160 // only if there is no thread death exception installed already. 2161 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2162 // If the topmost frame is a runtime stub, then we are calling into 2163 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2164 // must deoptimize the caller before continuing, as the compiled exception handler table 2165 // may not be valid 2166 if (has_last_Java_frame()) { 2167 frame f = last_frame(); 2168 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2169 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2170 RegisterMap reg_map(this, UseBiasedLocking); 2171 frame compiled_frame = f.sender(®_map); 2172 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2173 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2174 } 2175 } 2176 } 2177 2178 // Set async. pending exception in thread. 2179 set_pending_async_exception(java_throwable); 2180 2181 if (TraceExceptions) { 2182 ResourceMark rm; 2183 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2184 } 2185 // for AbortVMOnException flag 2186 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); 2187 } 2188 } 2189 2190 2191 // Interrupt thread so it will wake up from a potential wait() 2192 Thread::interrupt(this); 2193 } 2194 2195 // External suspension mechanism. 2196 // 2197 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2198 // to any VM_locks and it is at a transition 2199 // Self-suspension will happen on the transition out of the vm. 2200 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2201 // 2202 // Guarantees on return: 2203 // + Target thread will not execute any new bytecode (that's why we need to 2204 // force a safepoint) 2205 // + Target thread will not enter any new monitors 2206 // 2207 void JavaThread::java_suspend() { 2208 { MutexLocker mu(Threads_lock); 2209 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2210 return; 2211 } 2212 } 2213 2214 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2215 if (!is_external_suspend()) { 2216 // a racing resume has cancelled us; bail out now 2217 return; 2218 } 2219 2220 // suspend is done 2221 uint32_t debug_bits = 0; 2222 // Warning: is_ext_suspend_completed() may temporarily drop the 2223 // SR_lock to allow the thread to reach a stable thread state if 2224 // it is currently in a transient thread state. 2225 if (is_ext_suspend_completed(false /* !called_by_wait */, 2226 SuspendRetryDelay, &debug_bits)) { 2227 return; 2228 } 2229 } 2230 2231 VM_ForceSafepoint vm_suspend; 2232 VMThread::execute(&vm_suspend); 2233 } 2234 2235 // Part II of external suspension. 2236 // A JavaThread self suspends when it detects a pending external suspend 2237 // request. This is usually on transitions. It is also done in places 2238 // where continuing to the next transition would surprise the caller, 2239 // e.g., monitor entry. 2240 // 2241 // Returns the number of times that the thread self-suspended. 2242 // 2243 // Note: DO NOT call java_suspend_self() when you just want to block current 2244 // thread. java_suspend_self() is the second stage of cooperative 2245 // suspension for external suspend requests and should only be used 2246 // to complete an external suspend request. 2247 // 2248 int JavaThread::java_suspend_self() { 2249 int ret = 0; 2250 2251 // we are in the process of exiting so don't suspend 2252 if (is_exiting()) { 2253 clear_external_suspend(); 2254 return ret; 2255 } 2256 2257 assert(_anchor.walkable() || 2258 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2259 "must have walkable stack"); 2260 2261 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2262 2263 assert(!this->is_ext_suspended(), 2264 "a thread trying to self-suspend should not already be suspended"); 2265 2266 if (this->is_suspend_equivalent()) { 2267 // If we are self-suspending as a result of the lifting of a 2268 // suspend equivalent condition, then the suspend_equivalent 2269 // flag is not cleared until we set the ext_suspended flag so 2270 // that wait_for_ext_suspend_completion() returns consistent 2271 // results. 2272 this->clear_suspend_equivalent(); 2273 } 2274 2275 // A racing resume may have cancelled us before we grabbed SR_lock 2276 // above. Or another external suspend request could be waiting for us 2277 // by the time we return from SR_lock()->wait(). The thread 2278 // that requested the suspension may already be trying to walk our 2279 // stack and if we return now, we can change the stack out from under 2280 // it. This would be a "bad thing (TM)" and cause the stack walker 2281 // to crash. We stay self-suspended until there are no more pending 2282 // external suspend requests. 2283 while (is_external_suspend()) { 2284 ret++; 2285 this->set_ext_suspended(); 2286 2287 // _ext_suspended flag is cleared by java_resume() 2288 while (is_ext_suspended()) { 2289 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2290 } 2291 } 2292 2293 return ret; 2294 } 2295 2296 #ifdef ASSERT 2297 // verify the JavaThread has not yet been published in the Threads::list, and 2298 // hence doesn't need protection from concurrent access at this stage 2299 void JavaThread::verify_not_published() { 2300 if (!Threads_lock->owned_by_self()) { 2301 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2302 assert(!Threads::includes(this), 2303 "java thread shouldn't have been published yet!"); 2304 } else { 2305 assert(!Threads::includes(this), 2306 "java thread shouldn't have been published yet!"); 2307 } 2308 } 2309 #endif 2310 2311 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2312 // progress or when _suspend_flags is non-zero. 2313 // Current thread needs to self-suspend if there is a suspend request and/or 2314 // block if a safepoint is in progress. 2315 // Async exception ISN'T checked. 2316 // Note only the ThreadInVMfromNative transition can call this function 2317 // directly and when thread state is _thread_in_native_trans 2318 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2319 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2320 2321 JavaThread *curJT = JavaThread::current(); 2322 bool do_self_suspend = thread->is_external_suspend(); 2323 2324 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2325 2326 // If JNIEnv proxies are allowed, don't self-suspend if the target 2327 // thread is not the current thread. In older versions of jdbx, jdbx 2328 // threads could call into the VM with another thread's JNIEnv so we 2329 // can be here operating on behalf of a suspended thread (4432884). 2330 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2331 JavaThreadState state = thread->thread_state(); 2332 2333 // We mark this thread_blocked state as a suspend-equivalent so 2334 // that a caller to is_ext_suspend_completed() won't be confused. 2335 // The suspend-equivalent state is cleared by java_suspend_self(). 2336 thread->set_suspend_equivalent(); 2337 2338 // If the safepoint code sees the _thread_in_native_trans state, it will 2339 // wait until the thread changes to other thread state. There is no 2340 // guarantee on how soon we can obtain the SR_lock and complete the 2341 // self-suspend request. It would be a bad idea to let safepoint wait for 2342 // too long. Temporarily change the state to _thread_blocked to 2343 // let the VM thread know that this thread is ready for GC. The problem 2344 // of changing thread state is that safepoint could happen just after 2345 // java_suspend_self() returns after being resumed, and VM thread will 2346 // see the _thread_blocked state. We must check for safepoint 2347 // after restoring the state and make sure we won't leave while a safepoint 2348 // is in progress. 2349 thread->set_thread_state(_thread_blocked); 2350 thread->java_suspend_self(); 2351 thread->set_thread_state(state); 2352 // Make sure new state is seen by VM thread 2353 if (os::is_MP()) { 2354 if (UseMembar) { 2355 // Force a fence between the write above and read below 2356 OrderAccess::fence(); 2357 } else { 2358 // Must use this rather than serialization page in particular on Windows 2359 InterfaceSupport::serialize_memory(thread); 2360 } 2361 } 2362 } 2363 2364 if (SafepointSynchronize::do_call_back()) { 2365 // If we are safepointing, then block the caller which may not be 2366 // the same as the target thread (see above). 2367 SafepointSynchronize::block(curJT); 2368 } 2369 2370 if (thread->is_deopt_suspend()) { 2371 thread->clear_deopt_suspend(); 2372 RegisterMap map(thread, false); 2373 frame f = thread->last_frame(); 2374 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2375 f = f.sender(&map); 2376 } 2377 if (f.id() == thread->must_deopt_id()) { 2378 thread->clear_must_deopt_id(); 2379 f.deoptimize(thread); 2380 } else { 2381 fatal("missed deoptimization!"); 2382 } 2383 } 2384 } 2385 2386 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2387 // progress or when _suspend_flags is non-zero. 2388 // Current thread needs to self-suspend if there is a suspend request and/or 2389 // block if a safepoint is in progress. 2390 // Also check for pending async exception (not including unsafe access error). 2391 // Note only the native==>VM/Java barriers can call this function and when 2392 // thread state is _thread_in_native_trans. 2393 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2394 check_safepoint_and_suspend_for_native_trans(thread); 2395 2396 if (thread->has_async_exception()) { 2397 // We are in _thread_in_native_trans state, don't handle unsafe 2398 // access error since that may block. 2399 thread->check_and_handle_async_exceptions(false); 2400 } 2401 } 2402 2403 // This is a variant of the normal 2404 // check_special_condition_for_native_trans with slightly different 2405 // semantics for use by critical native wrappers. It does all the 2406 // normal checks but also performs the transition back into 2407 // thread_in_Java state. This is required so that critical natives 2408 // can potentially block and perform a GC if they are the last thread 2409 // exiting the GC_locker. 2410 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2411 check_special_condition_for_native_trans(thread); 2412 2413 // Finish the transition 2414 thread->set_thread_state(_thread_in_Java); 2415 2416 if (thread->do_critical_native_unlock()) { 2417 ThreadInVMfromJavaNoAsyncException tiv(thread); 2418 GC_locker::unlock_critical(thread); 2419 thread->clear_critical_native_unlock(); 2420 } 2421 } 2422 2423 // We need to guarantee the Threads_lock here, since resumes are not 2424 // allowed during safepoint synchronization 2425 // Can only resume from an external suspension 2426 void JavaThread::java_resume() { 2427 assert_locked_or_safepoint(Threads_lock); 2428 2429 // Sanity check: thread is gone, has started exiting or the thread 2430 // was not externally suspended. 2431 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2432 return; 2433 } 2434 2435 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2436 2437 clear_external_suspend(); 2438 2439 if (is_ext_suspended()) { 2440 clear_ext_suspended(); 2441 SR_lock()->notify_all(); 2442 } 2443 } 2444 2445 void JavaThread::create_stack_guard_pages() { 2446 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2447 address low_addr = stack_base() - stack_size(); 2448 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2449 2450 int allocate = os::allocate_stack_guard_pages(); 2451 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2452 2453 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2454 warning("Attempt to allocate stack guard pages failed."); 2455 return; 2456 } 2457 2458 if (os::guard_memory((char *) low_addr, len)) { 2459 _stack_guard_state = stack_guard_enabled; 2460 } else { 2461 warning("Attempt to protect stack guard pages failed."); 2462 if (os::uncommit_memory((char *) low_addr, len)) { 2463 warning("Attempt to deallocate stack guard pages failed."); 2464 } 2465 } 2466 } 2467 2468 void JavaThread::remove_stack_guard_pages() { 2469 assert(Thread::current() == this, "from different thread"); 2470 if (_stack_guard_state == stack_guard_unused) return; 2471 address low_addr = stack_base() - stack_size(); 2472 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2473 2474 if (os::allocate_stack_guard_pages()) { 2475 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2476 _stack_guard_state = stack_guard_unused; 2477 } else { 2478 warning("Attempt to deallocate stack guard pages failed."); 2479 } 2480 } else { 2481 if (_stack_guard_state == stack_guard_unused) return; 2482 if (os::unguard_memory((char *) low_addr, len)) { 2483 _stack_guard_state = stack_guard_unused; 2484 } else { 2485 warning("Attempt to unprotect stack guard pages failed."); 2486 } 2487 } 2488 } 2489 2490 void JavaThread::enable_stack_yellow_zone() { 2491 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2492 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2493 2494 // The base notation is from the stacks point of view, growing downward. 2495 // We need to adjust it to work correctly with guard_memory() 2496 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2497 2498 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2499 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2500 2501 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2502 _stack_guard_state = stack_guard_enabled; 2503 } else { 2504 warning("Attempt to guard stack yellow zone failed."); 2505 } 2506 enable_register_stack_guard(); 2507 } 2508 2509 void JavaThread::disable_stack_yellow_zone() { 2510 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2511 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2512 2513 // Simply return if called for a thread that does not use guard pages. 2514 if (_stack_guard_state == stack_guard_unused) return; 2515 2516 // The base notation is from the stacks point of view, growing downward. 2517 // We need to adjust it to work correctly with guard_memory() 2518 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2519 2520 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2521 _stack_guard_state = stack_guard_yellow_disabled; 2522 } else { 2523 warning("Attempt to unguard stack yellow zone failed."); 2524 } 2525 disable_register_stack_guard(); 2526 } 2527 2528 void JavaThread::enable_stack_red_zone() { 2529 // The base notation is from the stacks point of view, growing downward. 2530 // We need to adjust it to work correctly with guard_memory() 2531 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2532 address base = stack_red_zone_base() - stack_red_zone_size(); 2533 2534 guarantee(base < stack_base(), "Error calculating stack red zone"); 2535 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2536 2537 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2538 warning("Attempt to guard stack red zone failed."); 2539 } 2540 } 2541 2542 void JavaThread::disable_stack_red_zone() { 2543 // The base notation is from the stacks point of view, growing downward. 2544 // We need to adjust it to work correctly with guard_memory() 2545 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2546 address base = stack_red_zone_base() - stack_red_zone_size(); 2547 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2548 warning("Attempt to unguard stack red zone failed."); 2549 } 2550 } 2551 2552 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2553 // ignore is there is no stack 2554 if (!has_last_Java_frame()) return; 2555 // traverse the stack frames. Starts from top frame. 2556 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2557 frame* fr = fst.current(); 2558 f(fr, fst.register_map()); 2559 } 2560 } 2561 2562 2563 #ifndef PRODUCT 2564 // Deoptimization 2565 // Function for testing deoptimization 2566 void JavaThread::deoptimize() { 2567 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2568 StackFrameStream fst(this, UseBiasedLocking); 2569 bool deopt = false; // Dump stack only if a deopt actually happens. 2570 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2571 // Iterate over all frames in the thread and deoptimize 2572 for (; !fst.is_done(); fst.next()) { 2573 if (fst.current()->can_be_deoptimized()) { 2574 2575 if (only_at) { 2576 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2577 // consists of comma or carriage return separated numbers so 2578 // search for the current bci in that string. 2579 address pc = fst.current()->pc(); 2580 nmethod* nm = (nmethod*) fst.current()->cb(); 2581 ScopeDesc* sd = nm->scope_desc_at(pc); 2582 char buffer[8]; 2583 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2584 size_t len = strlen(buffer); 2585 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2586 while (found != NULL) { 2587 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2588 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2589 // Check that the bci found is bracketed by terminators. 2590 break; 2591 } 2592 found = strstr(found + 1, buffer); 2593 } 2594 if (!found) { 2595 continue; 2596 } 2597 } 2598 2599 if (DebugDeoptimization && !deopt) { 2600 deopt = true; // One-time only print before deopt 2601 tty->print_cr("[BEFORE Deoptimization]"); 2602 trace_frames(); 2603 trace_stack(); 2604 } 2605 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2606 } 2607 } 2608 2609 if (DebugDeoptimization && deopt) { 2610 tty->print_cr("[AFTER Deoptimization]"); 2611 trace_frames(); 2612 } 2613 } 2614 2615 2616 // Make zombies 2617 void JavaThread::make_zombies() { 2618 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2619 if (fst.current()->can_be_deoptimized()) { 2620 // it is a Java nmethod 2621 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2622 nm->make_not_entrant(); 2623 } 2624 } 2625 } 2626 #endif // PRODUCT 2627 2628 2629 void JavaThread::deoptimized_wrt_marked_nmethods() { 2630 if (!has_last_Java_frame()) return; 2631 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2632 StackFrameStream fst(this, UseBiasedLocking); 2633 for (; !fst.is_done(); fst.next()) { 2634 if (fst.current()->should_be_deoptimized()) { 2635 if (LogCompilation && xtty != NULL) { 2636 nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); 2637 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", 2638 this->name(), nm != NULL ? nm->compile_id() : -1); 2639 } 2640 2641 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2642 } 2643 } 2644 } 2645 2646 2647 // If the caller is a NamedThread, then remember, in the current scope, 2648 // the given JavaThread in its _processed_thread field. 2649 class RememberProcessedThread: public StackObj { 2650 NamedThread* _cur_thr; 2651 public: 2652 RememberProcessedThread(JavaThread* jthr) { 2653 Thread* thread = Thread::current(); 2654 if (thread->is_Named_thread()) { 2655 _cur_thr = (NamedThread *)thread; 2656 _cur_thr->set_processed_thread(jthr); 2657 } else { 2658 _cur_thr = NULL; 2659 } 2660 } 2661 2662 ~RememberProcessedThread() { 2663 if (_cur_thr) { 2664 _cur_thr->set_processed_thread(NULL); 2665 } 2666 } 2667 }; 2668 2669 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2670 // Verify that the deferred card marks have been flushed. 2671 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2672 2673 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2674 // since there may be more than one thread using each ThreadProfiler. 2675 2676 // Traverse the GCHandles 2677 Thread::oops_do(f, cld_f, cf); 2678 2679 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2680 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2681 2682 if (has_last_Java_frame()) { 2683 // Record JavaThread to GC thread 2684 RememberProcessedThread rpt(this); 2685 2686 // Traverse the privileged stack 2687 if (_privileged_stack_top != NULL) { 2688 _privileged_stack_top->oops_do(f); 2689 } 2690 2691 // traverse the registered growable array 2692 if (_array_for_gc != NULL) { 2693 for (int index = 0; index < _array_for_gc->length(); index++) { 2694 f->do_oop(_array_for_gc->adr_at(index)); 2695 } 2696 } 2697 2698 // Traverse the monitor chunks 2699 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2700 chunk->oops_do(f); 2701 } 2702 2703 // Traverse the execution stack 2704 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2705 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2706 } 2707 } 2708 2709 // callee_target is never live across a gc point so NULL it here should 2710 // it still contain a methdOop. 2711 2712 set_callee_target(NULL); 2713 2714 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2715 // If we have deferred set_locals there might be oops waiting to be 2716 // written 2717 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2718 if (list != NULL) { 2719 for (int i = 0; i < list->length(); i++) { 2720 list->at(i)->oops_do(f); 2721 } 2722 } 2723 2724 // Traverse instance variables at the end since the GC may be moving things 2725 // around using this function 2726 f->do_oop((oop*) &_threadObj); 2727 f->do_oop((oop*) &_vm_result); 2728 f->do_oop((oop*) &_exception_oop); 2729 f->do_oop((oop*) &_pending_async_exception); 2730 2731 if (jvmti_thread_state() != NULL) { 2732 jvmti_thread_state()->oops_do(f); 2733 } 2734 } 2735 2736 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2737 Thread::nmethods_do(cf); // (super method is a no-op) 2738 2739 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2740 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2741 2742 if (has_last_Java_frame()) { 2743 // Traverse the execution stack 2744 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2745 fst.current()->nmethods_do(cf); 2746 } 2747 } 2748 } 2749 2750 void JavaThread::metadata_do(void f(Metadata*)) { 2751 Thread::metadata_do(f); 2752 if (has_last_Java_frame()) { 2753 // Traverse the execution stack to call f() on the methods in the stack 2754 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2755 fst.current()->metadata_do(f); 2756 } 2757 } else if (is_Compiler_thread()) { 2758 // need to walk ciMetadata in current compile tasks to keep alive. 2759 CompilerThread* ct = (CompilerThread*)this; 2760 if (ct->env() != NULL) { 2761 ct->env()->metadata_do(f); 2762 } 2763 } 2764 } 2765 2766 // Printing 2767 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2768 switch (_thread_state) { 2769 case _thread_uninitialized: return "_thread_uninitialized"; 2770 case _thread_new: return "_thread_new"; 2771 case _thread_new_trans: return "_thread_new_trans"; 2772 case _thread_in_native: return "_thread_in_native"; 2773 case _thread_in_native_trans: return "_thread_in_native_trans"; 2774 case _thread_in_vm: return "_thread_in_vm"; 2775 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2776 case _thread_in_Java: return "_thread_in_Java"; 2777 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2778 case _thread_blocked: return "_thread_blocked"; 2779 case _thread_blocked_trans: return "_thread_blocked_trans"; 2780 default: return "unknown thread state"; 2781 } 2782 } 2783 2784 #ifndef PRODUCT 2785 void JavaThread::print_thread_state_on(outputStream *st) const { 2786 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2787 }; 2788 void JavaThread::print_thread_state() const { 2789 print_thread_state_on(tty); 2790 } 2791 #endif // PRODUCT 2792 2793 // Called by Threads::print() for VM_PrintThreads operation 2794 void JavaThread::print_on(outputStream *st) const { 2795 st->print("\"%s\" ", get_thread_name()); 2796 oop thread_oop = threadObj(); 2797 if (thread_oop != NULL) { 2798 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2799 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2800 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2801 } 2802 Thread::print_on(st); 2803 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2804 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2805 if (thread_oop != NULL) { 2806 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2807 } 2808 #ifndef PRODUCT 2809 print_thread_state_on(st); 2810 _safepoint_state->print_on(st); 2811 #endif // PRODUCT 2812 } 2813 2814 // Called by fatal error handler. The difference between this and 2815 // JavaThread::print() is that we can't grab lock or allocate memory. 2816 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2817 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2818 oop thread_obj = threadObj(); 2819 if (thread_obj != NULL) { 2820 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2821 } 2822 st->print(" ["); 2823 st->print("%s", _get_thread_state_name(_thread_state)); 2824 if (osthread()) { 2825 st->print(", id=%d", osthread()->thread_id()); 2826 } 2827 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2828 _stack_base - _stack_size, _stack_base); 2829 st->print("]"); 2830 return; 2831 } 2832 2833 // Verification 2834 2835 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2836 2837 void JavaThread::verify() { 2838 // Verify oops in the thread. 2839 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2840 2841 // Verify the stack frames. 2842 frames_do(frame_verify); 2843 } 2844 2845 // CR 6300358 (sub-CR 2137150) 2846 // Most callers of this method assume that it can't return NULL but a 2847 // thread may not have a name whilst it is in the process of attaching to 2848 // the VM - see CR 6412693, and there are places where a JavaThread can be 2849 // seen prior to having it's threadObj set (eg JNI attaching threads and 2850 // if vm exit occurs during initialization). These cases can all be accounted 2851 // for such that this method never returns NULL. 2852 const char* JavaThread::get_thread_name() const { 2853 #ifdef ASSERT 2854 // early safepoints can hit while current thread does not yet have TLS 2855 if (!SafepointSynchronize::is_at_safepoint()) { 2856 Thread *cur = Thread::current(); 2857 if (!(cur->is_Java_thread() && cur == this)) { 2858 // Current JavaThreads are allowed to get their own name without 2859 // the Threads_lock. 2860 assert_locked_or_safepoint(Threads_lock); 2861 } 2862 } 2863 #endif // ASSERT 2864 return get_thread_name_string(); 2865 } 2866 2867 // Returns a non-NULL representation of this thread's name, or a suitable 2868 // descriptive string if there is no set name 2869 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2870 const char* name_str; 2871 oop thread_obj = threadObj(); 2872 if (thread_obj != NULL) { 2873 typeArrayOop name = java_lang_Thread::name(thread_obj); 2874 if (name != NULL) { 2875 if (buf == NULL) { 2876 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2877 name->length()); 2878 } else { 2879 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2880 name->length(), buf, buflen); 2881 } 2882 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2883 name_str = "<no-name - thread is attaching>"; 2884 } else { 2885 name_str = Thread::name(); 2886 } 2887 } else { 2888 name_str = Thread::name(); 2889 } 2890 assert(name_str != NULL, "unexpected NULL thread name"); 2891 return name_str; 2892 } 2893 2894 2895 const char* JavaThread::get_threadgroup_name() const { 2896 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2897 oop thread_obj = threadObj(); 2898 if (thread_obj != NULL) { 2899 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2900 if (thread_group != NULL) { 2901 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2902 // ThreadGroup.name can be null 2903 if (name != NULL) { 2904 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2905 return str; 2906 } 2907 } 2908 } 2909 return NULL; 2910 } 2911 2912 const char* JavaThread::get_parent_name() const { 2913 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2914 oop thread_obj = threadObj(); 2915 if (thread_obj != NULL) { 2916 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2917 if (thread_group != NULL) { 2918 oop parent = java_lang_ThreadGroup::parent(thread_group); 2919 if (parent != NULL) { 2920 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2921 // ThreadGroup.name can be null 2922 if (name != NULL) { 2923 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2924 return str; 2925 } 2926 } 2927 } 2928 } 2929 return NULL; 2930 } 2931 2932 ThreadPriority JavaThread::java_priority() const { 2933 oop thr_oop = threadObj(); 2934 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2935 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2936 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2937 return priority; 2938 } 2939 2940 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2941 2942 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2943 // Link Java Thread object <-> C++ Thread 2944 2945 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2946 // and put it into a new Handle. The Handle "thread_oop" can then 2947 // be used to pass the C++ thread object to other methods. 2948 2949 // Set the Java level thread object (jthread) field of the 2950 // new thread (a JavaThread *) to C++ thread object using the 2951 // "thread_oop" handle. 2952 2953 // Set the thread field (a JavaThread *) of the 2954 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2955 2956 Handle thread_oop(Thread::current(), 2957 JNIHandles::resolve_non_null(jni_thread)); 2958 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 2959 "must be initialized"); 2960 set_threadObj(thread_oop()); 2961 java_lang_Thread::set_thread(thread_oop(), this); 2962 2963 if (prio == NoPriority) { 2964 prio = java_lang_Thread::priority(thread_oop()); 2965 assert(prio != NoPriority, "A valid priority should be present"); 2966 } 2967 2968 // Push the Java priority down to the native thread; needs Threads_lock 2969 Thread::set_priority(this, prio); 2970 2971 prepare_ext(); 2972 2973 // Add the new thread to the Threads list and set it in motion. 2974 // We must have threads lock in order to call Threads::add. 2975 // It is crucial that we do not block before the thread is 2976 // added to the Threads list for if a GC happens, then the java_thread oop 2977 // will not be visited by GC. 2978 Threads::add(this); 2979 } 2980 2981 oop JavaThread::current_park_blocker() { 2982 // Support for JSR-166 locks 2983 oop thread_oop = threadObj(); 2984 if (thread_oop != NULL && 2985 JDK_Version::current().supports_thread_park_blocker()) { 2986 return java_lang_Thread::park_blocker(thread_oop); 2987 } 2988 return NULL; 2989 } 2990 2991 2992 void JavaThread::print_stack_on(outputStream* st) { 2993 if (!has_last_Java_frame()) return; 2994 ResourceMark rm; 2995 HandleMark hm; 2996 2997 RegisterMap reg_map(this); 2998 vframe* start_vf = last_java_vframe(®_map); 2999 int count = 0; 3000 for (vframe* f = start_vf; f; f = f->sender()) { 3001 if (f->is_java_frame()) { 3002 javaVFrame* jvf = javaVFrame::cast(f); 3003 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3004 3005 // Print out lock information 3006 if (JavaMonitorsInStackTrace) { 3007 jvf->print_lock_info_on(st, count); 3008 } 3009 } else { 3010 // Ignore non-Java frames 3011 } 3012 3013 // Bail-out case for too deep stacks 3014 count++; 3015 if (MaxJavaStackTraceDepth == count) return; 3016 } 3017 } 3018 3019 3020 // JVMTI PopFrame support 3021 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3022 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3023 if (in_bytes(size_in_bytes) != 0) { 3024 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3025 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3026 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3027 } 3028 } 3029 3030 void* JavaThread::popframe_preserved_args() { 3031 return _popframe_preserved_args; 3032 } 3033 3034 ByteSize JavaThread::popframe_preserved_args_size() { 3035 return in_ByteSize(_popframe_preserved_args_size); 3036 } 3037 3038 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3039 int sz = in_bytes(popframe_preserved_args_size()); 3040 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3041 return in_WordSize(sz / wordSize); 3042 } 3043 3044 void JavaThread::popframe_free_preserved_args() { 3045 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3046 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread); 3047 _popframe_preserved_args = NULL; 3048 _popframe_preserved_args_size = 0; 3049 } 3050 3051 #ifndef PRODUCT 3052 3053 void JavaThread::trace_frames() { 3054 tty->print_cr("[Describe stack]"); 3055 int frame_no = 1; 3056 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3057 tty->print(" %d. ", frame_no++); 3058 fst.current()->print_value_on(tty, this); 3059 tty->cr(); 3060 } 3061 } 3062 3063 class PrintAndVerifyOopClosure: public OopClosure { 3064 protected: 3065 template <class T> inline void do_oop_work(T* p) { 3066 oop obj = oopDesc::load_decode_heap_oop(p); 3067 if (obj == NULL) return; 3068 tty->print(INTPTR_FORMAT ": ", p); 3069 if (obj->is_oop_or_null()) { 3070 if (obj->is_objArray()) { 3071 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 3072 } else { 3073 obj->print(); 3074 } 3075 } else { 3076 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 3077 } 3078 tty->cr(); 3079 } 3080 public: 3081 virtual void do_oop(oop* p) { do_oop_work(p); } 3082 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3083 }; 3084 3085 3086 static void oops_print(frame* f, const RegisterMap *map) { 3087 PrintAndVerifyOopClosure print; 3088 f->print_value(); 3089 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3090 } 3091 3092 // Print our all the locations that contain oops and whether they are 3093 // valid or not. This useful when trying to find the oldest frame 3094 // where an oop has gone bad since the frame walk is from youngest to 3095 // oldest. 3096 void JavaThread::trace_oops() { 3097 tty->print_cr("[Trace oops]"); 3098 frames_do(oops_print); 3099 } 3100 3101 3102 #ifdef ASSERT 3103 // Print or validate the layout of stack frames 3104 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3105 ResourceMark rm; 3106 PRESERVE_EXCEPTION_MARK; 3107 FrameValues values; 3108 int frame_no = 0; 3109 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3110 fst.current()->describe(values, ++frame_no); 3111 if (depth == frame_no) break; 3112 } 3113 if (validate_only) { 3114 values.validate(); 3115 } else { 3116 tty->print_cr("[Describe stack layout]"); 3117 values.print(this); 3118 } 3119 } 3120 #endif 3121 3122 void JavaThread::trace_stack_from(vframe* start_vf) { 3123 ResourceMark rm; 3124 int vframe_no = 1; 3125 for (vframe* f = start_vf; f; f = f->sender()) { 3126 if (f->is_java_frame()) { 3127 javaVFrame::cast(f)->print_activation(vframe_no++); 3128 } else { 3129 f->print(); 3130 } 3131 if (vframe_no > StackPrintLimit) { 3132 tty->print_cr("...<more frames>..."); 3133 return; 3134 } 3135 } 3136 } 3137 3138 3139 void JavaThread::trace_stack() { 3140 if (!has_last_Java_frame()) return; 3141 ResourceMark rm; 3142 HandleMark hm; 3143 RegisterMap reg_map(this); 3144 trace_stack_from(last_java_vframe(®_map)); 3145 } 3146 3147 3148 #endif // PRODUCT 3149 3150 3151 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3152 assert(reg_map != NULL, "a map must be given"); 3153 frame f = last_frame(); 3154 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3155 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3156 } 3157 return NULL; 3158 } 3159 3160 3161 Klass* JavaThread::security_get_caller_class(int depth) { 3162 vframeStream vfst(this); 3163 vfst.security_get_caller_frame(depth); 3164 if (!vfst.at_end()) { 3165 return vfst.method()->method_holder(); 3166 } 3167 return NULL; 3168 } 3169 3170 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3171 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3172 CompileBroker::compiler_thread_loop(); 3173 } 3174 3175 // Create a CompilerThread 3176 CompilerThread::CompilerThread(CompileQueue* queue, 3177 CompilerCounters* counters) 3178 : JavaThread(&compiler_thread_entry) { 3179 _env = NULL; 3180 _log = NULL; 3181 _task = NULL; 3182 _queue = queue; 3183 _counters = counters; 3184 _buffer_blob = NULL; 3185 _scanned_nmethod = NULL; 3186 _compiler = NULL; 3187 3188 #ifndef PRODUCT 3189 _ideal_graph_printer = NULL; 3190 #endif 3191 } 3192 3193 void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3194 JavaThread::oops_do(f, cld_f, cf); 3195 if (_scanned_nmethod != NULL && cf != NULL) { 3196 // Safepoints can occur when the sweeper is scanning an nmethod so 3197 // process it here to make sure it isn't unloaded in the middle of 3198 // a scan. 3199 cf->do_code_blob(_scanned_nmethod); 3200 } 3201 } 3202 3203 3204 // ======= Threads ======== 3205 3206 // The Threads class links together all active threads, and provides 3207 // operations over all threads. It is protected by its own Mutex 3208 // lock, which is also used in other contexts to protect thread 3209 // operations from having the thread being operated on from exiting 3210 // and going away unexpectedly (e.g., safepoint synchronization) 3211 3212 JavaThread* Threads::_thread_list = NULL; 3213 int Threads::_number_of_threads = 0; 3214 int Threads::_number_of_non_daemon_threads = 0; 3215 int Threads::_return_code = 0; 3216 size_t JavaThread::_stack_size_at_create = 0; 3217 #ifdef ASSERT 3218 bool Threads::_vm_complete = false; 3219 #endif 3220 3221 // All JavaThreads 3222 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3223 3224 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3225 void Threads::threads_do(ThreadClosure* tc) { 3226 assert_locked_or_safepoint(Threads_lock); 3227 // ALL_JAVA_THREADS iterates through all JavaThreads 3228 ALL_JAVA_THREADS(p) { 3229 tc->do_thread(p); 3230 } 3231 // Someday we could have a table or list of all non-JavaThreads. 3232 // For now, just manually iterate through them. 3233 tc->do_thread(VMThread::vm_thread()); 3234 Universe::heap()->gc_threads_do(tc); 3235 WatcherThread *wt = WatcherThread::watcher_thread(); 3236 // Strictly speaking, the following NULL check isn't sufficient to make sure 3237 // the data for WatcherThread is still valid upon being examined. However, 3238 // considering that WatchThread terminates when the VM is on the way to 3239 // exit at safepoint, the chance of the above is extremely small. The right 3240 // way to prevent termination of WatcherThread would be to acquire 3241 // Terminator_lock, but we can't do that without violating the lock rank 3242 // checking in some cases. 3243 if (wt != NULL) { 3244 tc->do_thread(wt); 3245 } 3246 3247 // If CompilerThreads ever become non-JavaThreads, add them here 3248 } 3249 3250 3251 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3252 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3253 3254 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3255 create_vm_init_libraries(); 3256 } 3257 3258 initialize_class(vmSymbols::java_lang_String(), CHECK); 3259 3260 // Initialize java_lang.System (needed before creating the thread) 3261 initialize_class(vmSymbols::java_lang_System(), CHECK); 3262 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3263 Handle thread_group = create_initial_thread_group(CHECK); 3264 Universe::set_main_thread_group(thread_group()); 3265 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3266 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3267 main_thread->set_threadObj(thread_object); 3268 // Set thread status to running since main thread has 3269 // been started and running. 3270 java_lang_Thread::set_thread_status(thread_object, 3271 java_lang_Thread::RUNNABLE); 3272 3273 // The VM creates & returns objects of this class. Make sure it's initialized. 3274 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3275 3276 // The VM preresolves methods to these classes. Make sure that they get initialized 3277 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3278 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3279 call_initializeSystemClass(CHECK); 3280 3281 // get the Java runtime name after java.lang.System is initialized 3282 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3283 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3284 3285 // an instance of OutOfMemory exception has been allocated earlier 3286 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3287 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3288 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3289 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3290 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3291 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3292 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3293 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3294 } 3295 3296 void Threads::initialize_jsr292_core_classes(TRAPS) { 3297 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3298 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3299 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3300 } 3301 3302 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3303 extern void JDK_Version_init(); 3304 3305 // Check version 3306 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3307 3308 // Initialize the output stream module 3309 ostream_init(); 3310 3311 // Process java launcher properties. 3312 Arguments::process_sun_java_launcher_properties(args); 3313 3314 // Initialize the os module before using TLS 3315 os::init(); 3316 3317 // Initialize system properties. 3318 Arguments::init_system_properties(); 3319 3320 // So that JDK version can be used as a discriminator when parsing arguments 3321 JDK_Version_init(); 3322 3323 // Update/Initialize System properties after JDK version number is known 3324 Arguments::init_version_specific_system_properties(); 3325 3326 // Parse arguments 3327 jint parse_result = Arguments::parse(args); 3328 if (parse_result != JNI_OK) return parse_result; 3329 3330 os::init_before_ergo(); 3331 3332 jint ergo_result = Arguments::apply_ergo(); 3333 if (ergo_result != JNI_OK) return ergo_result; 3334 3335 if (PauseAtStartup) { 3336 os::pause(); 3337 } 3338 3339 HOTSPOT_VM_INIT_BEGIN(); 3340 3341 // Record VM creation timing statistics 3342 TraceVmCreationTime create_vm_timer; 3343 create_vm_timer.start(); 3344 3345 // Timing (must come after argument parsing) 3346 TraceTime timer("Create VM", TraceStartupTime); 3347 3348 // Initialize the os module after parsing the args 3349 jint os_init_2_result = os::init_2(); 3350 if (os_init_2_result != JNI_OK) return os_init_2_result; 3351 3352 jint adjust_after_os_result = Arguments::adjust_after_os(); 3353 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3354 3355 // initialize TLS 3356 ThreadLocalStorage::init(); 3357 3358 // Initialize output stream logging 3359 ostream_init_log(); 3360 3361 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3362 // Must be before create_vm_init_agents() 3363 if (Arguments::init_libraries_at_startup()) { 3364 convert_vm_init_libraries_to_agents(); 3365 } 3366 3367 // Launch -agentlib/-agentpath and converted -Xrun agents 3368 if (Arguments::init_agents_at_startup()) { 3369 create_vm_init_agents(); 3370 } 3371 3372 // Initialize Threads state 3373 _thread_list = NULL; 3374 _number_of_threads = 0; 3375 _number_of_non_daemon_threads = 0; 3376 3377 // Initialize global data structures and create system classes in heap 3378 vm_init_globals(); 3379 3380 // Attach the main thread to this os thread 3381 JavaThread* main_thread = new JavaThread(); 3382 main_thread->set_thread_state(_thread_in_vm); 3383 // must do this before set_active_handles and initialize_thread_local_storage 3384 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3385 // change the stack size recorded here to one based on the java thread 3386 // stacksize. This adjusted size is what is used to figure the placement 3387 // of the guard pages. 3388 main_thread->record_stack_base_and_size(); 3389 main_thread->initialize_thread_local_storage(); 3390 3391 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3392 3393 if (!main_thread->set_as_starting_thread()) { 3394 vm_shutdown_during_initialization( 3395 "Failed necessary internal allocation. Out of swap space"); 3396 delete main_thread; 3397 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3398 return JNI_ENOMEM; 3399 } 3400 3401 // Enable guard page *after* os::create_main_thread(), otherwise it would 3402 // crash Linux VM, see notes in os_linux.cpp. 3403 main_thread->create_stack_guard_pages(); 3404 3405 // Initialize Java-Level synchronization subsystem 3406 ObjectMonitor::Initialize(); 3407 3408 // Initialize global modules 3409 jint status = init_globals(); 3410 if (status != JNI_OK) { 3411 delete main_thread; 3412 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3413 return status; 3414 } 3415 3416 // Should be done after the heap is fully created 3417 main_thread->cache_global_variables(); 3418 3419 HandleMark hm; 3420 3421 { MutexLocker mu(Threads_lock); 3422 Threads::add(main_thread); 3423 } 3424 3425 // Any JVMTI raw monitors entered in onload will transition into 3426 // real raw monitor. VM is setup enough here for raw monitor enter. 3427 JvmtiExport::transition_pending_onload_raw_monitors(); 3428 3429 // Create the VMThread 3430 { TraceTime timer("Start VMThread", TraceStartupTime); 3431 VMThread::create(); 3432 Thread* vmthread = VMThread::vm_thread(); 3433 3434 if (!os::create_thread(vmthread, os::vm_thread)) { 3435 vm_exit_during_initialization("Cannot create VM thread. " 3436 "Out of system resources."); 3437 } 3438 3439 // Wait for the VM thread to become ready, and VMThread::run to initialize 3440 // Monitors can have spurious returns, must always check another state flag 3441 { 3442 MutexLocker ml(Notify_lock); 3443 os::start_thread(vmthread); 3444 while (vmthread->active_handles() == NULL) { 3445 Notify_lock->wait(); 3446 } 3447 } 3448 } 3449 3450 assert(Universe::is_fully_initialized(), "not initialized"); 3451 if (VerifyDuringStartup) { 3452 // Make sure we're starting with a clean slate. 3453 VM_Verify verify_op; 3454 VMThread::execute(&verify_op); 3455 } 3456 3457 Thread* THREAD = Thread::current(); 3458 3459 // At this point, the Universe is initialized, but we have not executed 3460 // any byte code. Now is a good time (the only time) to dump out the 3461 // internal state of the JVM for sharing. 3462 if (DumpSharedSpaces) { 3463 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3464 ShouldNotReachHere(); 3465 } 3466 3467 // Always call even when there are not JVMTI environments yet, since environments 3468 // may be attached late and JVMTI must track phases of VM execution 3469 JvmtiExport::enter_start_phase(); 3470 3471 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3472 JvmtiExport::post_vm_start(); 3473 3474 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3475 3476 // We need this for ClassDataSharing - the initial vm.info property is set 3477 // with the default value of CDS "sharing" which may be reset through 3478 // command line options. 3479 reset_vm_info_property(CHECK_JNI_ERR); 3480 3481 quicken_jni_functions(); 3482 3483 // Must be run after init_ft which initializes ft_enabled 3484 if (TRACE_INITIALIZE() != JNI_OK) { 3485 vm_exit_during_initialization("Failed to initialize tracing backend"); 3486 } 3487 3488 // Set flag that basic initialization has completed. Used by exceptions and various 3489 // debug stuff, that does not work until all basic classes have been initialized. 3490 set_init_completed(); 3491 3492 Metaspace::post_initialize(); 3493 3494 HOTSPOT_VM_INIT_END(); 3495 3496 // record VM initialization completion time 3497 #if INCLUDE_MANAGEMENT 3498 Management::record_vm_init_completed(); 3499 #endif // INCLUDE_MANAGEMENT 3500 3501 // Compute system loader. Note that this has to occur after set_init_completed, since 3502 // valid exceptions may be thrown in the process. 3503 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3504 // set_init_completed has just been called, causing exceptions not to be shortcut 3505 // anymore. We call vm_exit_during_initialization directly instead. 3506 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR); 3507 3508 #if INCLUDE_ALL_GCS 3509 // Support for ConcurrentMarkSweep. This should be cleaned up 3510 // and better encapsulated. The ugly nested if test would go away 3511 // once things are properly refactored. XXX YSR 3512 if (UseConcMarkSweepGC || UseG1GC) { 3513 if (UseConcMarkSweepGC) { 3514 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3515 } else { 3516 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3517 } 3518 } 3519 #endif // INCLUDE_ALL_GCS 3520 3521 // Always call even when there are not JVMTI environments yet, since environments 3522 // may be attached late and JVMTI must track phases of VM execution 3523 JvmtiExport::enter_live_phase(); 3524 3525 // Signal Dispatcher needs to be started before VMInit event is posted 3526 os::signal_init(); 3527 3528 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3529 if (!DisableAttachMechanism) { 3530 AttachListener::vm_start(); 3531 if (StartAttachListener || AttachListener::init_at_startup()) { 3532 AttachListener::init(); 3533 } 3534 } 3535 3536 // Launch -Xrun agents 3537 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3538 // back-end can launch with -Xdebug -Xrunjdwp. 3539 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3540 create_vm_init_libraries(); 3541 } 3542 3543 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3544 JvmtiExport::post_vm_initialized(); 3545 3546 if (TRACE_START() != JNI_OK) { 3547 vm_exit_during_initialization("Failed to start tracing backend."); 3548 } 3549 3550 if (CleanChunkPoolAsync) { 3551 Chunk::start_chunk_pool_cleaner_task(); 3552 } 3553 3554 // initialize compiler(s) 3555 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) 3556 CompileBroker::compilation_init(); 3557 #endif 3558 3559 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3560 // It is done after compilers are initialized, because otherwise compilations of 3561 // signature polymorphic MH intrinsics can be missed 3562 // (see SystemDictionary::find_method_handle_intrinsic). 3563 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3564 3565 #if INCLUDE_MANAGEMENT 3566 Management::initialize(THREAD); 3567 3568 if (HAS_PENDING_EXCEPTION) { 3569 // management agent fails to start possibly due to 3570 // configuration problem and is responsible for printing 3571 // stack trace if appropriate. Simply exit VM. 3572 vm_exit(1); 3573 } 3574 #endif // INCLUDE_MANAGEMENT 3575 3576 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3577 if (MemProfiling) MemProfiler::engage(); 3578 StatSampler::engage(); 3579 if (CheckJNICalls) JniPeriodicChecker::engage(); 3580 3581 BiasedLocking::init(); 3582 3583 #if INCLUDE_RTM_OPT 3584 RTMLockingCounters::init(); 3585 #endif 3586 3587 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3588 call_postVMInitHook(THREAD); 3589 // The Java side of PostVMInitHook.run must deal with all 3590 // exceptions and provide means of diagnosis. 3591 if (HAS_PENDING_EXCEPTION) { 3592 CLEAR_PENDING_EXCEPTION; 3593 } 3594 } 3595 3596 { 3597 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 3598 // Make sure the watcher thread can be started by WatcherThread::start() 3599 // or by dynamic enrollment. 3600 WatcherThread::make_startable(); 3601 // Start up the WatcherThread if there are any periodic tasks 3602 // NOTE: All PeriodicTasks should be registered by now. If they 3603 // aren't, late joiners might appear to start slowly (we might 3604 // take a while to process their first tick). 3605 if (PeriodicTask::num_tasks() > 0) { 3606 WatcherThread::start(); 3607 } 3608 } 3609 3610 // Give os specific code one last chance to start 3611 os::init_3(); 3612 3613 create_vm_timer.end(); 3614 #ifdef ASSERT 3615 _vm_complete = true; 3616 #endif 3617 return JNI_OK; 3618 } 3619 3620 // type for the Agent_OnLoad and JVM_OnLoad entry points 3621 extern "C" { 3622 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3623 } 3624 // Find a command line agent library and return its entry point for 3625 // -agentlib: -agentpath: -Xrun 3626 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3627 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3628 const char *on_load_symbols[], 3629 size_t num_symbol_entries) { 3630 OnLoadEntry_t on_load_entry = NULL; 3631 void *library = NULL; 3632 3633 if (!agent->valid()) { 3634 char buffer[JVM_MAXPATHLEN]; 3635 char ebuf[1024]; 3636 const char *name = agent->name(); 3637 const char *msg = "Could not find agent library "; 3638 3639 // First check to see if agent is statically linked into executable 3640 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3641 library = agent->os_lib(); 3642 } else if (agent->is_absolute_path()) { 3643 library = os::dll_load(name, ebuf, sizeof ebuf); 3644 if (library == NULL) { 3645 const char *sub_msg = " in absolute path, with error: "; 3646 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3647 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3648 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3649 // If we can't find the agent, exit. 3650 vm_exit_during_initialization(buf, NULL); 3651 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3652 } 3653 } else { 3654 // Try to load the agent from the standard dll directory 3655 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3656 name)) { 3657 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3658 } 3659 if (library == NULL) { // Try the local directory 3660 char ns[1] = {0}; 3661 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3662 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3663 } 3664 if (library == NULL) { 3665 const char *sub_msg = " on the library path, with error: "; 3666 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3667 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3668 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3669 // If we can't find the agent, exit. 3670 vm_exit_during_initialization(buf, NULL); 3671 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3672 } 3673 } 3674 } 3675 agent->set_os_lib(library); 3676 agent->set_valid(); 3677 } 3678 3679 // Find the OnLoad function. 3680 on_load_entry = 3681 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3682 false, 3683 on_load_symbols, 3684 num_symbol_entries)); 3685 return on_load_entry; 3686 } 3687 3688 // Find the JVM_OnLoad entry point 3689 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3690 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3691 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3692 } 3693 3694 // Find the Agent_OnLoad entry point 3695 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3696 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3697 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3698 } 3699 3700 // For backwards compatibility with -Xrun 3701 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3702 // treated like -agentpath: 3703 // Must be called before agent libraries are created 3704 void Threads::convert_vm_init_libraries_to_agents() { 3705 AgentLibrary* agent; 3706 AgentLibrary* next; 3707 3708 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3709 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3710 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3711 3712 // If there is an JVM_OnLoad function it will get called later, 3713 // otherwise see if there is an Agent_OnLoad 3714 if (on_load_entry == NULL) { 3715 on_load_entry = lookup_agent_on_load(agent); 3716 if (on_load_entry != NULL) { 3717 // switch it to the agent list -- so that Agent_OnLoad will be called, 3718 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3719 Arguments::convert_library_to_agent(agent); 3720 } else { 3721 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3722 } 3723 } 3724 } 3725 } 3726 3727 // Create agents for -agentlib: -agentpath: and converted -Xrun 3728 // Invokes Agent_OnLoad 3729 // Called very early -- before JavaThreads exist 3730 void Threads::create_vm_init_agents() { 3731 extern struct JavaVM_ main_vm; 3732 AgentLibrary* agent; 3733 3734 JvmtiExport::enter_onload_phase(); 3735 3736 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3737 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3738 3739 if (on_load_entry != NULL) { 3740 // Invoke the Agent_OnLoad function 3741 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3742 if (err != JNI_OK) { 3743 vm_exit_during_initialization("agent library failed to init", agent->name()); 3744 } 3745 } else { 3746 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3747 } 3748 } 3749 JvmtiExport::enter_primordial_phase(); 3750 } 3751 3752 extern "C" { 3753 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3754 } 3755 3756 void Threads::shutdown_vm_agents() { 3757 // Send any Agent_OnUnload notifications 3758 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3759 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3760 extern struct JavaVM_ main_vm; 3761 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3762 3763 // Find the Agent_OnUnload function. 3764 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3765 os::find_agent_function(agent, 3766 false, 3767 on_unload_symbols, 3768 num_symbol_entries)); 3769 3770 // Invoke the Agent_OnUnload function 3771 if (unload_entry != NULL) { 3772 JavaThread* thread = JavaThread::current(); 3773 ThreadToNativeFromVM ttn(thread); 3774 HandleMark hm(thread); 3775 (*unload_entry)(&main_vm); 3776 } 3777 } 3778 } 3779 3780 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3781 // Invokes JVM_OnLoad 3782 void Threads::create_vm_init_libraries() { 3783 extern struct JavaVM_ main_vm; 3784 AgentLibrary* agent; 3785 3786 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3787 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3788 3789 if (on_load_entry != NULL) { 3790 // Invoke the JVM_OnLoad function 3791 JavaThread* thread = JavaThread::current(); 3792 ThreadToNativeFromVM ttn(thread); 3793 HandleMark hm(thread); 3794 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3795 if (err != JNI_OK) { 3796 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3797 } 3798 } else { 3799 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3800 } 3801 } 3802 } 3803 3804 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 3805 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 3806 3807 JavaThread* java_thread = NULL; 3808 // Sequential search for now. Need to do better optimization later. 3809 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 3810 oop tobj = thread->threadObj(); 3811 if (!thread->is_exiting() && 3812 tobj != NULL && 3813 java_tid == java_lang_Thread::thread_id(tobj)) { 3814 java_thread = thread; 3815 break; 3816 } 3817 } 3818 return java_thread; 3819 } 3820 3821 3822 // Last thread running calls java.lang.Shutdown.shutdown() 3823 void JavaThread::invoke_shutdown_hooks() { 3824 HandleMark hm(this); 3825 3826 // We could get here with a pending exception, if so clear it now. 3827 if (this->has_pending_exception()) { 3828 this->clear_pending_exception(); 3829 } 3830 3831 EXCEPTION_MARK; 3832 Klass* k = 3833 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3834 THREAD); 3835 if (k != NULL) { 3836 // SystemDictionary::resolve_or_null will return null if there was 3837 // an exception. If we cannot load the Shutdown class, just don't 3838 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3839 // and finalizers (if runFinalizersOnExit is set) won't be run. 3840 // Note that if a shutdown hook was registered or runFinalizersOnExit 3841 // was called, the Shutdown class would have already been loaded 3842 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3843 instanceKlassHandle shutdown_klass (THREAD, k); 3844 JavaValue result(T_VOID); 3845 JavaCalls::call_static(&result, 3846 shutdown_klass, 3847 vmSymbols::shutdown_method_name(), 3848 vmSymbols::void_method_signature(), 3849 THREAD); 3850 } 3851 CLEAR_PENDING_EXCEPTION; 3852 } 3853 3854 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3855 // the program falls off the end of main(). Another VM exit path is through 3856 // vm_exit() when the program calls System.exit() to return a value or when 3857 // there is a serious error in VM. The two shutdown paths are not exactly 3858 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 3859 // and VM_Exit op at VM level. 3860 // 3861 // Shutdown sequence: 3862 // + Shutdown native memory tracking if it is on 3863 // + Wait until we are the last non-daemon thread to execute 3864 // <-- every thing is still working at this moment --> 3865 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3866 // shutdown hooks, run finalizers if finalization-on-exit 3867 // + Call before_exit(), prepare for VM exit 3868 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3869 // currently the only user of this mechanism is File.deleteOnExit()) 3870 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 3871 // post thread end and vm death events to JVMTI, 3872 // stop signal thread 3873 // + Call JavaThread::exit(), it will: 3874 // > release JNI handle blocks, remove stack guard pages 3875 // > remove this thread from Threads list 3876 // <-- no more Java code from this thread after this point --> 3877 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3878 // the compiler threads at safepoint 3879 // <-- do not use anything that could get blocked by Safepoint --> 3880 // + Disable tracing at JNI/JVM barriers 3881 // + Set _vm_exited flag for threads that are still running native code 3882 // + Delete this thread 3883 // + Call exit_globals() 3884 // > deletes tty 3885 // > deletes PerfMemory resources 3886 // + Return to caller 3887 3888 bool Threads::destroy_vm() { 3889 JavaThread* thread = JavaThread::current(); 3890 3891 #ifdef ASSERT 3892 _vm_complete = false; 3893 #endif 3894 // Wait until we are the last non-daemon thread to execute 3895 { MutexLocker nu(Threads_lock); 3896 while (Threads::number_of_non_daemon_threads() > 1) 3897 // This wait should make safepoint checks, wait without a timeout, 3898 // and wait as a suspend-equivalent condition. 3899 // 3900 // Note: If the FlatProfiler is running and this thread is waiting 3901 // for another non-daemon thread to finish, then the FlatProfiler 3902 // is waiting for the external suspend request on this thread to 3903 // complete. wait_for_ext_suspend_completion() will eventually 3904 // timeout, but that takes time. Making this wait a suspend- 3905 // equivalent condition solves that timeout problem. 3906 // 3907 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3908 Mutex::_as_suspend_equivalent_flag); 3909 } 3910 3911 // Hang forever on exit if we are reporting an error. 3912 if (ShowMessageBoxOnError && is_error_reported()) { 3913 os::infinite_sleep(); 3914 } 3915 os::wait_for_keypress_at_exit(); 3916 3917 // run Java level shutdown hooks 3918 thread->invoke_shutdown_hooks(); 3919 3920 before_exit(thread); 3921 3922 thread->exit(true); 3923 3924 // Stop VM thread. 3925 { 3926 // 4945125 The vm thread comes to a safepoint during exit. 3927 // GC vm_operations can get caught at the safepoint, and the 3928 // heap is unparseable if they are caught. Grab the Heap_lock 3929 // to prevent this. The GC vm_operations will not be able to 3930 // queue until after the vm thread is dead. After this point, 3931 // we'll never emerge out of the safepoint before the VM exits. 3932 3933 MutexLocker ml(Heap_lock); 3934 3935 VMThread::wait_for_vm_thread_exit(); 3936 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3937 VMThread::destroy(); 3938 } 3939 3940 // clean up ideal graph printers 3941 #if defined(COMPILER2) && !defined(PRODUCT) 3942 IdealGraphPrinter::clean_up(); 3943 #endif 3944 3945 // Now, all Java threads are gone except daemon threads. Daemon threads 3946 // running Java code or in VM are stopped by the Safepoint. However, 3947 // daemon threads executing native code are still running. But they 3948 // will be stopped at native=>Java/VM barriers. Note that we can't 3949 // simply kill or suspend them, as it is inherently deadlock-prone. 3950 3951 #ifndef PRODUCT 3952 // disable function tracing at JNI/JVM barriers 3953 TraceJNICalls = false; 3954 TraceJVMCalls = false; 3955 TraceRuntimeCalls = false; 3956 #endif 3957 3958 VM_Exit::set_vm_exited(); 3959 3960 notify_vm_shutdown(); 3961 3962 delete thread; 3963 3964 // exit_globals() will delete tty 3965 exit_globals(); 3966 3967 return true; 3968 } 3969 3970 3971 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3972 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3973 return is_supported_jni_version(version); 3974 } 3975 3976 3977 jboolean Threads::is_supported_jni_version(jint version) { 3978 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3979 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3980 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3981 if (version == JNI_VERSION_1_8) return JNI_TRUE; 3982 return JNI_FALSE; 3983 } 3984 3985 3986 void Threads::add(JavaThread* p, bool force_daemon) { 3987 // The threads lock must be owned at this point 3988 assert_locked_or_safepoint(Threads_lock); 3989 3990 // See the comment for this method in thread.hpp for its purpose and 3991 // why it is called here. 3992 p->initialize_queues(); 3993 p->set_next(_thread_list); 3994 _thread_list = p; 3995 _number_of_threads++; 3996 oop threadObj = p->threadObj(); 3997 bool daemon = true; 3998 // Bootstrapping problem: threadObj can be null for initial 3999 // JavaThread (or for threads attached via JNI) 4000 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4001 _number_of_non_daemon_threads++; 4002 daemon = false; 4003 } 4004 4005 ThreadService::add_thread(p, daemon); 4006 4007 // Possible GC point. 4008 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 4009 } 4010 4011 void Threads::remove(JavaThread* p) { 4012 // Extra scope needed for Thread_lock, so we can check 4013 // that we do not remove thread without safepoint code notice 4014 { MutexLocker ml(Threads_lock); 4015 4016 assert(includes(p), "p must be present"); 4017 4018 JavaThread* current = _thread_list; 4019 JavaThread* prev = NULL; 4020 4021 while (current != p) { 4022 prev = current; 4023 current = current->next(); 4024 } 4025 4026 if (prev) { 4027 prev->set_next(current->next()); 4028 } else { 4029 _thread_list = p->next(); 4030 } 4031 _number_of_threads--; 4032 oop threadObj = p->threadObj(); 4033 bool daemon = true; 4034 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4035 _number_of_non_daemon_threads--; 4036 daemon = false; 4037 4038 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4039 // on destroy_vm will wake up. 4040 if (number_of_non_daemon_threads() == 1) { 4041 Threads_lock->notify_all(); 4042 } 4043 } 4044 ThreadService::remove_thread(p, daemon); 4045 4046 // Make sure that safepoint code disregard this thread. This is needed since 4047 // the thread might mess around with locks after this point. This can cause it 4048 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4049 // of this thread since it is removed from the queue. 4050 p->set_terminated_value(); 4051 } // unlock Threads_lock 4052 4053 // Since Events::log uses a lock, we grab it outside the Threads_lock 4054 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 4055 } 4056 4057 // Threads_lock must be held when this is called (or must be called during a safepoint) 4058 bool Threads::includes(JavaThread* p) { 4059 assert(Threads_lock->is_locked(), "sanity check"); 4060 ALL_JAVA_THREADS(q) { 4061 if (q == p) { 4062 return true; 4063 } 4064 } 4065 return false; 4066 } 4067 4068 // Operations on the Threads list for GC. These are not explicitly locked, 4069 // but the garbage collector must provide a safe context for them to run. 4070 // In particular, these things should never be called when the Threads_lock 4071 // is held by some other thread. (Note: the Safepoint abstraction also 4072 // uses the Threads_lock to guarantee this property. It also makes sure that 4073 // all threads gets blocked when exiting or starting). 4074 4075 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4076 ALL_JAVA_THREADS(p) { 4077 p->oops_do(f, cld_f, cf); 4078 } 4079 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4080 } 4081 4082 void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4083 // Introduce a mechanism allowing parallel threads to claim threads as 4084 // root groups. Overhead should be small enough to use all the time, 4085 // even in sequential code. 4086 SharedHeap* sh = SharedHeap::heap(); 4087 // Cannot yet substitute active_workers for n_par_threads 4088 // because of G1CollectedHeap::verify() use of 4089 // SharedHeap::process_roots(). n_par_threads == 0 will 4090 // turn off parallelism in process_roots while active_workers 4091 // is being used for parallelism elsewhere. 4092 bool is_par = sh->n_par_threads() > 0; 4093 assert(!is_par || 4094 (SharedHeap::heap()->n_par_threads() == 4095 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 4096 int cp = SharedHeap::heap()->strong_roots_parity(); 4097 ALL_JAVA_THREADS(p) { 4098 if (p->claim_oops_do(is_par, cp)) { 4099 p->oops_do(f, cld_f, cf); 4100 } 4101 } 4102 VMThread* vmt = VMThread::vm_thread(); 4103 if (vmt->claim_oops_do(is_par, cp)) { 4104 vmt->oops_do(f, cld_f, cf); 4105 } 4106 } 4107 4108 #if INCLUDE_ALL_GCS 4109 // Used by ParallelScavenge 4110 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4111 ALL_JAVA_THREADS(p) { 4112 q->enqueue(new ThreadRootsTask(p)); 4113 } 4114 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4115 } 4116 4117 // Used by Parallel Old 4118 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4119 ALL_JAVA_THREADS(p) { 4120 q->enqueue(new ThreadRootsMarkingTask(p)); 4121 } 4122 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4123 } 4124 #endif // INCLUDE_ALL_GCS 4125 4126 void Threads::nmethods_do(CodeBlobClosure* cf) { 4127 ALL_JAVA_THREADS(p) { 4128 p->nmethods_do(cf); 4129 } 4130 VMThread::vm_thread()->nmethods_do(cf); 4131 } 4132 4133 void Threads::metadata_do(void f(Metadata*)) { 4134 ALL_JAVA_THREADS(p) { 4135 p->metadata_do(f); 4136 } 4137 } 4138 4139 void Threads::deoptimized_wrt_marked_nmethods() { 4140 ALL_JAVA_THREADS(p) { 4141 p->deoptimized_wrt_marked_nmethods(); 4142 } 4143 } 4144 4145 4146 // Get count Java threads that are waiting to enter the specified monitor. 4147 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4148 address monitor, 4149 bool doLock) { 4150 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4151 "must grab Threads_lock or be at safepoint"); 4152 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4153 4154 int i = 0; 4155 { 4156 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4157 ALL_JAVA_THREADS(p) { 4158 if (p->is_Compiler_thread()) continue; 4159 4160 address pending = (address)p->current_pending_monitor(); 4161 if (pending == monitor) { // found a match 4162 if (i < count) result->append(p); // save the first count matches 4163 i++; 4164 } 4165 } 4166 } 4167 return result; 4168 } 4169 4170 4171 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4172 bool doLock) { 4173 assert(doLock || 4174 Threads_lock->owned_by_self() || 4175 SafepointSynchronize::is_at_safepoint(), 4176 "must grab Threads_lock or be at safepoint"); 4177 4178 // NULL owner means not locked so we can skip the search 4179 if (owner == NULL) return NULL; 4180 4181 { 4182 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4183 ALL_JAVA_THREADS(p) { 4184 // first, see if owner is the address of a Java thread 4185 if (owner == (address)p) return p; 4186 } 4187 } 4188 // Cannot assert on lack of success here since this function may be 4189 // used by code that is trying to report useful problem information 4190 // like deadlock detection. 4191 if (UseHeavyMonitors) return NULL; 4192 4193 // If we didn't find a matching Java thread and we didn't force use of 4194 // heavyweight monitors, then the owner is the stack address of the 4195 // Lock Word in the owning Java thread's stack. 4196 // 4197 JavaThread* the_owner = NULL; 4198 { 4199 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4200 ALL_JAVA_THREADS(q) { 4201 if (q->is_lock_owned(owner)) { 4202 the_owner = q; 4203 break; 4204 } 4205 } 4206 } 4207 // cannot assert on lack of success here; see above comment 4208 return the_owner; 4209 } 4210 4211 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4212 void Threads::print_on(outputStream* st, bool print_stacks, 4213 bool internal_format, bool print_concurrent_locks) { 4214 char buf[32]; 4215 st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); 4216 4217 st->print_cr("Full thread dump %s (%s %s):", 4218 Abstract_VM_Version::vm_name(), 4219 Abstract_VM_Version::vm_release(), 4220 Abstract_VM_Version::vm_info_string()); 4221 st->cr(); 4222 4223 #if INCLUDE_ALL_GCS 4224 // Dump concurrent locks 4225 ConcurrentLocksDump concurrent_locks; 4226 if (print_concurrent_locks) { 4227 concurrent_locks.dump_at_safepoint(); 4228 } 4229 #endif // INCLUDE_ALL_GCS 4230 4231 ALL_JAVA_THREADS(p) { 4232 ResourceMark rm; 4233 p->print_on(st); 4234 if (print_stacks) { 4235 if (internal_format) { 4236 p->trace_stack(); 4237 } else { 4238 p->print_stack_on(st); 4239 } 4240 } 4241 st->cr(); 4242 #if INCLUDE_ALL_GCS 4243 if (print_concurrent_locks) { 4244 concurrent_locks.print_locks_on(p, st); 4245 } 4246 #endif // INCLUDE_ALL_GCS 4247 } 4248 4249 VMThread::vm_thread()->print_on(st); 4250 st->cr(); 4251 Universe::heap()->print_gc_threads_on(st); 4252 WatcherThread* wt = WatcherThread::watcher_thread(); 4253 if (wt != NULL) { 4254 wt->print_on(st); 4255 st->cr(); 4256 } 4257 CompileBroker::print_compiler_threads_on(st); 4258 st->flush(); 4259 } 4260 4261 // Threads::print_on_error() is called by fatal error handler. It's possible 4262 // that VM is not at safepoint and/or current thread is inside signal handler. 4263 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4264 // memory (even in resource area), it might deadlock the error handler. 4265 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4266 int buflen) { 4267 bool found_current = false; 4268 st->print_cr("Java Threads: ( => current thread )"); 4269 ALL_JAVA_THREADS(thread) { 4270 bool is_current = (current == thread); 4271 found_current = found_current || is_current; 4272 4273 st->print("%s", is_current ? "=>" : " "); 4274 4275 st->print(PTR_FORMAT, thread); 4276 st->print(" "); 4277 thread->print_on_error(st, buf, buflen); 4278 st->cr(); 4279 } 4280 st->cr(); 4281 4282 st->print_cr("Other Threads:"); 4283 if (VMThread::vm_thread()) { 4284 bool is_current = (current == VMThread::vm_thread()); 4285 found_current = found_current || is_current; 4286 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4287 4288 st->print(PTR_FORMAT, VMThread::vm_thread()); 4289 st->print(" "); 4290 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4291 st->cr(); 4292 } 4293 WatcherThread* wt = WatcherThread::watcher_thread(); 4294 if (wt != NULL) { 4295 bool is_current = (current == wt); 4296 found_current = found_current || is_current; 4297 st->print("%s", is_current ? "=>" : " "); 4298 4299 st->print(PTR_FORMAT, wt); 4300 st->print(" "); 4301 wt->print_on_error(st, buf, buflen); 4302 st->cr(); 4303 } 4304 if (!found_current) { 4305 st->cr(); 4306 st->print("=>" PTR_FORMAT " (exited) ", current); 4307 current->print_on_error(st, buf, buflen); 4308 st->cr(); 4309 } 4310 } 4311 4312 // Internal SpinLock and Mutex 4313 // Based on ParkEvent 4314 4315 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4316 // 4317 // We employ SpinLocks _only for low-contention, fixed-length 4318 // short-duration critical sections where we're concerned 4319 // about native mutex_t or HotSpot Mutex:: latency. 4320 // The mux construct provides a spin-then-block mutual exclusion 4321 // mechanism. 4322 // 4323 // Testing has shown that contention on the ListLock guarding gFreeList 4324 // is common. If we implement ListLock as a simple SpinLock it's common 4325 // for the JVM to devolve to yielding with little progress. This is true 4326 // despite the fact that the critical sections protected by ListLock are 4327 // extremely short. 4328 // 4329 // TODO-FIXME: ListLock should be of type SpinLock. 4330 // We should make this a 1st-class type, integrated into the lock 4331 // hierarchy as leaf-locks. Critically, the SpinLock structure 4332 // should have sufficient padding to avoid false-sharing and excessive 4333 // cache-coherency traffic. 4334 4335 4336 typedef volatile int SpinLockT; 4337 4338 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4339 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4340 return; // normal fast-path return 4341 } 4342 4343 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4344 TEVENT(SpinAcquire - ctx); 4345 int ctr = 0; 4346 int Yields = 0; 4347 for (;;) { 4348 while (*adr != 0) { 4349 ++ctr; 4350 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4351 if (Yields > 5) { 4352 os::naked_short_sleep(1); 4353 } else { 4354 os::naked_yield(); 4355 ++Yields; 4356 } 4357 } else { 4358 SpinPause(); 4359 } 4360 } 4361 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4362 } 4363 } 4364 4365 void Thread::SpinRelease(volatile int * adr) { 4366 assert(*adr != 0, "invariant"); 4367 OrderAccess::fence(); // guarantee at least release consistency. 4368 // Roach-motel semantics. 4369 // It's safe if subsequent LDs and STs float "up" into the critical section, 4370 // but prior LDs and STs within the critical section can't be allowed 4371 // to reorder or float past the ST that releases the lock. 4372 // Loads and stores in the critical section - which appear in program 4373 // order before the store that releases the lock - must also appear 4374 // before the store that releases the lock in memory visibility order. 4375 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4376 // the ST of 0 into the lock-word which releases the lock, so fence 4377 // more than covers this on all platforms. 4378 *adr = 0; 4379 } 4380 4381 // muxAcquire and muxRelease: 4382 // 4383 // * muxAcquire and muxRelease support a single-word lock-word construct. 4384 // The LSB of the word is set IFF the lock is held. 4385 // The remainder of the word points to the head of a singly-linked list 4386 // of threads blocked on the lock. 4387 // 4388 // * The current implementation of muxAcquire-muxRelease uses its own 4389 // dedicated Thread._MuxEvent instance. If we're interested in 4390 // minimizing the peak number of extant ParkEvent instances then 4391 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4392 // as certain invariants were satisfied. Specifically, care would need 4393 // to be taken with regards to consuming unpark() "permits". 4394 // A safe rule of thumb is that a thread would never call muxAcquire() 4395 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4396 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4397 // consume an unpark() permit intended for monitorenter, for instance. 4398 // One way around this would be to widen the restricted-range semaphore 4399 // implemented in park(). Another alternative would be to provide 4400 // multiple instances of the PlatformEvent() for each thread. One 4401 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4402 // 4403 // * Usage: 4404 // -- Only as leaf locks 4405 // -- for short-term locking only as muxAcquire does not perform 4406 // thread state transitions. 4407 // 4408 // Alternatives: 4409 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4410 // but with parking or spin-then-park instead of pure spinning. 4411 // * Use Taura-Oyama-Yonenzawa locks. 4412 // * It's possible to construct a 1-0 lock if we encode the lockword as 4413 // (List,LockByte). Acquire will CAS the full lockword while Release 4414 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4415 // acquiring threads use timers (ParkTimed) to detect and recover from 4416 // the stranding window. Thread/Node structures must be aligned on 256-byte 4417 // boundaries by using placement-new. 4418 // * Augment MCS with advisory back-link fields maintained with CAS(). 4419 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4420 // The validity of the backlinks must be ratified before we trust the value. 4421 // If the backlinks are invalid the exiting thread must back-track through the 4422 // the forward links, which are always trustworthy. 4423 // * Add a successor indication. The LockWord is currently encoded as 4424 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4425 // to provide the usual futile-wakeup optimization. 4426 // See RTStt for details. 4427 // * Consider schedctl.sc_nopreempt to cover the critical section. 4428 // 4429 4430 4431 typedef volatile intptr_t MutexT; // Mux Lock-word 4432 enum MuxBits { LOCKBIT = 1 }; 4433 4434 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4435 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4436 if (w == 0) return; 4437 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4438 return; 4439 } 4440 4441 TEVENT(muxAcquire - Contention); 4442 ParkEvent * const Self = Thread::current()->_MuxEvent; 4443 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4444 for (;;) { 4445 int its = (os::is_MP() ? 100 : 0) + 1; 4446 4447 // Optional spin phase: spin-then-park strategy 4448 while (--its >= 0) { 4449 w = *Lock; 4450 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4451 return; 4452 } 4453 } 4454 4455 Self->reset(); 4456 Self->OnList = intptr_t(Lock); 4457 // The following fence() isn't _strictly necessary as the subsequent 4458 // CAS() both serializes execution and ratifies the fetched *Lock value. 4459 OrderAccess::fence(); 4460 for (;;) { 4461 w = *Lock; 4462 if ((w & LOCKBIT) == 0) { 4463 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4464 Self->OnList = 0; // hygiene - allows stronger asserts 4465 return; 4466 } 4467 continue; // Interference -- *Lock changed -- Just retry 4468 } 4469 assert(w & LOCKBIT, "invariant"); 4470 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4471 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4472 } 4473 4474 while (Self->OnList != 0) { 4475 Self->park(); 4476 } 4477 } 4478 } 4479 4480 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4481 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4482 if (w == 0) return; 4483 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4484 return; 4485 } 4486 4487 TEVENT(muxAcquire - Contention); 4488 ParkEvent * ReleaseAfter = NULL; 4489 if (ev == NULL) { 4490 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4491 } 4492 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4493 for (;;) { 4494 guarantee(ev->OnList == 0, "invariant"); 4495 int its = (os::is_MP() ? 100 : 0) + 1; 4496 4497 // Optional spin phase: spin-then-park strategy 4498 while (--its >= 0) { 4499 w = *Lock; 4500 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4501 if (ReleaseAfter != NULL) { 4502 ParkEvent::Release(ReleaseAfter); 4503 } 4504 return; 4505 } 4506 } 4507 4508 ev->reset(); 4509 ev->OnList = intptr_t(Lock); 4510 // The following fence() isn't _strictly necessary as the subsequent 4511 // CAS() both serializes execution and ratifies the fetched *Lock value. 4512 OrderAccess::fence(); 4513 for (;;) { 4514 w = *Lock; 4515 if ((w & LOCKBIT) == 0) { 4516 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4517 ev->OnList = 0; 4518 // We call ::Release while holding the outer lock, thus 4519 // artificially lengthening the critical section. 4520 // Consider deferring the ::Release() until the subsequent unlock(), 4521 // after we've dropped the outer lock. 4522 if (ReleaseAfter != NULL) { 4523 ParkEvent::Release(ReleaseAfter); 4524 } 4525 return; 4526 } 4527 continue; // Interference -- *Lock changed -- Just retry 4528 } 4529 assert(w & LOCKBIT, "invariant"); 4530 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4531 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4532 } 4533 4534 while (ev->OnList != 0) { 4535 ev->park(); 4536 } 4537 } 4538 } 4539 4540 // Release() must extract a successor from the list and then wake that thread. 4541 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4542 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4543 // Release() would : 4544 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4545 // (B) Extract a successor from the private list "in-hand" 4546 // (C) attempt to CAS() the residual back into *Lock over null. 4547 // If there were any newly arrived threads and the CAS() would fail. 4548 // In that case Release() would detach the RATs, re-merge the list in-hand 4549 // with the RATs and repeat as needed. Alternately, Release() might 4550 // detach and extract a successor, but then pass the residual list to the wakee. 4551 // The wakee would be responsible for reattaching and remerging before it 4552 // competed for the lock. 4553 // 4554 // Both "pop" and DMR are immune from ABA corruption -- there can be 4555 // multiple concurrent pushers, but only one popper or detacher. 4556 // This implementation pops from the head of the list. This is unfair, 4557 // but tends to provide excellent throughput as hot threads remain hot. 4558 // (We wake recently run threads first). 4559 // 4560 // All paths through muxRelease() will execute a CAS. 4561 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4562 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4563 // executed within the critical section are complete and globally visible before the 4564 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4565 void Thread::muxRelease(volatile intptr_t * Lock) { 4566 for (;;) { 4567 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4568 assert(w & LOCKBIT, "invariant"); 4569 if (w == LOCKBIT) return; 4570 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4571 assert(List != NULL, "invariant"); 4572 assert(List->OnList == intptr_t(Lock), "invariant"); 4573 ParkEvent * const nxt = List->ListNext; 4574 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4575 4576 // The following CAS() releases the lock and pops the head element. 4577 // The CAS() also ratifies the previously fetched lock-word value. 4578 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4579 continue; 4580 } 4581 List->OnList = 0; 4582 OrderAccess::fence(); 4583 List->unpark(); 4584 return; 4585 } 4586 } 4587 4588 4589 void Threads::verify() { 4590 ALL_JAVA_THREADS(p) { 4591 p->verify(); 4592 } 4593 VMThread* thread = VMThread::vm_thread(); 4594 if (thread != NULL) thread->verify(); 4595 }