1 /* 2 * Copyright (c) 1997, 2017, 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/moduleEntry.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/scopeDesc.hpp" 33 #include "compiler/compileBroker.hpp" 34 #include "compiler/compileTask.hpp" 35 #include "gc/shared/gcId.hpp" 36 #include "gc/shared/gcLocker.inline.hpp" 37 #include "gc/shared/workgroup.hpp" 38 #include "interpreter/interpreter.hpp" 39 #include "interpreter/linkResolver.hpp" 40 #include "interpreter/oopMapCache.hpp" 41 #include "jvmtifiles/jvmtiEnv.hpp" 42 #include "logging/log.hpp" 43 #include "logging/logConfiguration.hpp" 44 #include "memory/metaspaceShared.hpp" 45 #include "memory/oopFactory.hpp" 46 #include "memory/resourceArea.hpp" 47 #include "memory/universe.inline.hpp" 48 #include "oops/instanceKlass.hpp" 49 #include "oops/objArrayOop.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "oops/symbol.hpp" 52 #include "oops/verifyOopClosure.hpp" 53 #include "prims/jvm_misc.hpp" 54 #include "prims/jvmtiExport.hpp" 55 #include "prims/jvmtiThreadState.hpp" 56 #include "prims/privilegedStack.hpp" 57 #include "runtime/arguments.hpp" 58 #include "runtime/atomic.hpp" 59 #include "runtime/biasedLocking.hpp" 60 #include "runtime/commandLineFlagConstraintList.hpp" 61 #include "runtime/commandLineFlagWriteableList.hpp" 62 #include "runtime/commandLineFlagRangeList.hpp" 63 #include "runtime/deoptimization.hpp" 64 #include "runtime/fprofiler.hpp" 65 #include "runtime/frame.inline.hpp" 66 #include "runtime/globals.hpp" 67 #include "runtime/init.hpp" 68 #include "runtime/interfaceSupport.hpp" 69 #include "runtime/java.hpp" 70 #include "runtime/javaCalls.hpp" 71 #include "runtime/jniPeriodicChecker.hpp" 72 #include "runtime/timerTrace.hpp" 73 #include "runtime/memprofiler.hpp" 74 #include "runtime/mutexLocker.hpp" 75 #include "runtime/objectMonitor.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/osThread.hpp" 78 #include "runtime/safepoint.hpp" 79 #include "runtime/sharedRuntime.hpp" 80 #include "runtime/statSampler.hpp" 81 #include "runtime/stubRoutines.hpp" 82 #include "runtime/sweeper.hpp" 83 #include "runtime/task.hpp" 84 #include "runtime/thread.inline.hpp" 85 #include "runtime/threadCritical.hpp" 86 #include "runtime/vframe.hpp" 87 #include "runtime/vframeArray.hpp" 88 #include "runtime/vframe_hp.hpp" 89 #include "runtime/vmThread.hpp" 90 #include "runtime/vm_operations.hpp" 91 #include "runtime/vm_version.hpp" 92 #include "services/attachListener.hpp" 93 #include "services/management.hpp" 94 #include "services/memTracker.hpp" 95 #include "services/threadService.hpp" 96 #include "trace/traceMacros.hpp" 97 #include "trace/tracing.hpp" 98 #include "utilities/defaultStream.hpp" 99 #include "utilities/dtrace.hpp" 100 #include "utilities/events.hpp" 101 #include "utilities/macros.hpp" 102 #include "utilities/preserveException.hpp" 103 #if INCLUDE_ALL_GCS 104 #include "gc/cms/concurrentMarkSweepThread.hpp" 105 #include "gc/g1/concurrentMarkThread.inline.hpp" 106 #include "gc/parallel/pcTasks.hpp" 107 #endif // INCLUDE_ALL_GCS 108 #if INCLUDE_JVMCI 109 #include "jvmci/jvmciCompiler.hpp" 110 #include "jvmci/jvmciRuntime.hpp" 111 #endif 112 #ifdef COMPILER1 113 #include "c1/c1_Compiler.hpp" 114 #endif 115 #ifdef COMPILER2 116 #include "opto/c2compiler.hpp" 117 #include "opto/idealGraphPrinter.hpp" 118 #endif 119 #if INCLUDE_RTM_OPT 120 #include "runtime/rtmLocking.hpp" 121 #endif 122 123 // Initialization after module runtime initialization 124 void universe_post_module_init(); // must happen after call_initPhase2 125 126 #ifdef DTRACE_ENABLED 127 128 // Only bother with this argument setup if dtrace is available 129 130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 132 133 #define DTRACE_THREAD_PROBE(probe, javathread) \ 134 { \ 135 ResourceMark rm(this); \ 136 int len = 0; \ 137 const char* name = (javathread)->get_thread_name(); \ 138 len = strlen(name); \ 139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 140 (char *) name, len, \ 141 java_lang_Thread::thread_id((javathread)->threadObj()), \ 142 (uintptr_t) (javathread)->osthread()->thread_id(), \ 143 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 144 } 145 146 #else // ndef DTRACE_ENABLED 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) 149 150 #endif // ndef DTRACE_ENABLED 151 152 #ifndef USE_LIBRARY_BASED_TLS_ONLY 153 // Current thread is maintained as a thread-local variable 154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 155 #endif 156 // Class hierarchy 157 // - Thread 158 // - VMThread 159 // - WatcherThread 160 // - ConcurrentMarkSweepThread 161 // - JavaThread 162 // - CompilerThread 163 164 // ======= Thread ======== 165 // Support for forcing alignment of thread objects for biased locking 166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 167 if (UseBiasedLocking) { 168 const int alignment = markOopDesc::biased_lock_alignment; 169 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 171 : AllocateHeap(aligned_size, flags, CURRENT_PC, 172 AllocFailStrategy::RETURN_NULL); 173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 176 "JavaThread alignment code overflowed allocated storage"); 177 if (aligned_addr != real_malloc_addr) { 178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 179 p2i(real_malloc_addr), 180 p2i(aligned_addr)); 181 } 182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 183 return aligned_addr; 184 } else { 185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 187 } 188 } 189 190 void Thread::operator delete(void* p) { 191 if (UseBiasedLocking) { 192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 193 FreeHeap(real_malloc_addr); 194 } else { 195 FreeHeap(p); 196 } 197 } 198 199 200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 201 // JavaThread 202 203 204 Thread::Thread() { 205 // stack and get_thread 206 set_stack_base(NULL); 207 set_stack_size(0); 208 set_self_raw_id(0); 209 set_lgrp_id(-1); 210 DEBUG_ONLY(clear_suspendible_thread();) 211 212 // allocated data structures 213 set_osthread(NULL); 214 set_resource_area(new (mtThread)ResourceArea()); 215 DEBUG_ONLY(_current_resource_mark = NULL;) 216 set_handle_area(new (mtThread) HandleArea(NULL)); 217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 218 set_active_handles(NULL); 219 set_free_handle_block(NULL); 220 set_last_handle_mark(NULL); 221 222 // This initial value ==> never claimed. 223 _oops_do_parity = 0; 224 225 // the handle mark links itself to last_handle_mark 226 new HandleMark(this); 227 228 // plain initialization 229 debug_only(_owned_locks = NULL;) 230 debug_only(_allow_allocation_count = 0;) 231 NOT_PRODUCT(_allow_safepoint_count = 0;) 232 NOT_PRODUCT(_skip_gcalot = false;) 233 _jvmti_env_iteration_count = 0; 234 set_allocated_bytes(0); 235 _vm_operation_started_count = 0; 236 _vm_operation_completed_count = 0; 237 _current_pending_monitor = NULL; 238 _current_pending_monitor_is_from_java = true; 239 _current_waiting_monitor = NULL; 240 _num_nested_signal = 0; 241 omFreeList = NULL; 242 omFreeCount = 0; 243 omFreeProvision = 32; 244 omInUseList = NULL; 245 omInUseCount = 0; 246 247 #ifdef ASSERT 248 _visited_for_critical_count = false; 249 #endif 250 251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 252 Monitor::_safepoint_check_sometimes); 253 _suspend_flags = 0; 254 255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 256 _hashStateX = os::random(); 257 _hashStateY = 842502087; 258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 259 _hashStateW = 273326509; 260 261 _OnTrap = 0; 262 _schedctl = NULL; 263 _Stalled = 0; 264 _TypeTag = 0x2BAD; 265 266 // Many of the following fields are effectively final - immutable 267 // Note that nascent threads can't use the Native Monitor-Mutex 268 // construct until the _MutexEvent is initialized ... 269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 270 // we might instead use a stack of ParkEvents that we could provision on-demand. 271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 272 // and ::Release() 273 _ParkEvent = ParkEvent::Allocate(this); 274 _SleepEvent = ParkEvent::Allocate(this); 275 _MutexEvent = ParkEvent::Allocate(this); 276 _MuxEvent = ParkEvent::Allocate(this); 277 278 #ifdef CHECK_UNHANDLED_OOPS 279 if (CheckUnhandledOops) { 280 _unhandled_oops = new UnhandledOops(this); 281 } 282 #endif // CHECK_UNHANDLED_OOPS 283 #ifdef ASSERT 284 if (UseBiasedLocking) { 285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 286 assert(this == _real_malloc_address || 287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 288 "bug in forced alignment of thread objects"); 289 } 290 #endif // ASSERT 291 } 292 293 void Thread::initialize_thread_current() { 294 #ifndef USE_LIBRARY_BASED_TLS_ONLY 295 assert(_thr_current == NULL, "Thread::current already initialized"); 296 _thr_current = this; 297 #endif 298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 299 ThreadLocalStorage::set_thread(this); 300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 301 } 302 303 void Thread::clear_thread_current() { 304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 305 #ifndef USE_LIBRARY_BASED_TLS_ONLY 306 _thr_current = NULL; 307 #endif 308 ThreadLocalStorage::set_thread(NULL); 309 } 310 311 void Thread::record_stack_base_and_size() { 312 set_stack_base(os::current_stack_base()); 313 set_stack_size(os::current_stack_size()); 314 // CR 7190089: on Solaris, primordial thread's stack is adjusted 315 // in initialize_thread(). Without the adjustment, stack size is 316 // incorrect if stack is set to unlimited (ulimit -s unlimited). 317 // So far, only Solaris has real implementation of initialize_thread(). 318 // 319 // set up any platform-specific state. 320 os::initialize_thread(this); 321 322 // Set stack limits after thread is initialized. 323 if (is_Java_thread()) { 324 ((JavaThread*) this)->set_stack_overflow_limit(); 325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 326 } 327 #if INCLUDE_NMT 328 // record thread's native stack, stack grows downward 329 MemTracker::record_thread_stack(stack_end(), stack_size()); 330 #endif // INCLUDE_NMT 331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 333 os::current_thread_id(), p2i(stack_base() - stack_size()), 334 p2i(stack_base()), stack_size()/1024); 335 } 336 337 338 Thread::~Thread() { 339 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 340 ObjectSynchronizer::omFlush(this); 341 342 EVENT_THREAD_DESTRUCT(this); 343 344 // stack_base can be NULL if the thread is never started or exited before 345 // record_stack_base_and_size called. Although, we would like to ensure 346 // that all started threads do call record_stack_base_and_size(), there is 347 // not proper way to enforce that. 348 #if INCLUDE_NMT 349 if (_stack_base != NULL) { 350 MemTracker::release_thread_stack(stack_end(), stack_size()); 351 #ifdef ASSERT 352 set_stack_base(NULL); 353 #endif 354 } 355 #endif // INCLUDE_NMT 356 357 // deallocate data structures 358 delete resource_area(); 359 // since the handle marks are using the handle area, we have to deallocated the root 360 // handle mark before deallocating the thread's handle area, 361 assert(last_handle_mark() != NULL, "check we have an element"); 362 delete last_handle_mark(); 363 assert(last_handle_mark() == NULL, "check we have reached the end"); 364 365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 366 // We NULL out the fields for good hygiene. 367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 371 372 delete handle_area(); 373 delete metadata_handles(); 374 375 // SR_handler uses this as a termination indicator - 376 // needs to happen before os::free_thread() 377 delete _SR_lock; 378 _SR_lock = NULL; 379 380 // osthread() can be NULL, if creation of thread failed. 381 if (osthread() != NULL) os::free_thread(osthread()); 382 383 // clear Thread::current if thread is deleting itself. 384 // Needed to ensure JNI correctly detects non-attached threads. 385 if (this == Thread::current()) { 386 clear_thread_current(); 387 } 388 389 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 390 } 391 392 // NOTE: dummy function for assertion purpose. 393 void Thread::run() { 394 ShouldNotReachHere(); 395 } 396 397 #ifdef ASSERT 398 // Private method to check for dangling thread pointer 399 void check_for_dangling_thread_pointer(Thread *thread) { 400 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 401 "possibility of dangling Thread pointer"); 402 } 403 #endif 404 405 ThreadPriority Thread::get_priority(const Thread* const thread) { 406 ThreadPriority priority; 407 // Can return an error! 408 (void)os::get_priority(thread, priority); 409 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 410 return priority; 411 } 412 413 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 414 debug_only(check_for_dangling_thread_pointer(thread);) 415 // Can return an error! 416 (void)os::set_priority(thread, priority); 417 } 418 419 420 void Thread::start(Thread* thread) { 421 // Start is different from resume in that its safety is guaranteed by context or 422 // being called from a Java method synchronized on the Thread object. 423 if (!DisableStartThread) { 424 if (thread->is_Java_thread()) { 425 // Initialize the thread state to RUNNABLE before starting this thread. 426 // Can not set it after the thread started because we do not know the 427 // exact thread state at that time. It could be in MONITOR_WAIT or 428 // in SLEEPING or some other state. 429 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 430 java_lang_Thread::RUNNABLE); 431 } 432 os::start_thread(thread); 433 } 434 } 435 436 // Enqueue a VM_Operation to do the job for us - sometime later 437 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 438 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 439 VMThread::execute(vm_stop); 440 } 441 442 443 // Check if an external suspend request has completed (or has been 444 // cancelled). Returns true if the thread is externally suspended and 445 // false otherwise. 446 // 447 // The bits parameter returns information about the code path through 448 // the routine. Useful for debugging: 449 // 450 // set in is_ext_suspend_completed(): 451 // 0x00000001 - routine was entered 452 // 0x00000010 - routine return false at end 453 // 0x00000100 - thread exited (return false) 454 // 0x00000200 - suspend request cancelled (return false) 455 // 0x00000400 - thread suspended (return true) 456 // 0x00001000 - thread is in a suspend equivalent state (return true) 457 // 0x00002000 - thread is native and walkable (return true) 458 // 0x00004000 - thread is native_trans and walkable (needed retry) 459 // 460 // set in wait_for_ext_suspend_completion(): 461 // 0x00010000 - routine was entered 462 // 0x00020000 - suspend request cancelled before loop (return false) 463 // 0x00040000 - thread suspended before loop (return true) 464 // 0x00080000 - suspend request cancelled in loop (return false) 465 // 0x00100000 - thread suspended in loop (return true) 466 // 0x00200000 - suspend not completed during retry loop (return false) 467 468 // Helper class for tracing suspend wait debug bits. 469 // 470 // 0x00000100 indicates that the target thread exited before it could 471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 472 // 0x00080000 each indicate a cancelled suspend request so they don't 473 // count as wait failures either. 474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 475 476 class TraceSuspendDebugBits : public StackObj { 477 private: 478 JavaThread * jt; 479 bool is_wait; 480 bool called_by_wait; // meaningful when !is_wait 481 uint32_t * bits; 482 483 public: 484 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 485 uint32_t *_bits) { 486 jt = _jt; 487 is_wait = _is_wait; 488 called_by_wait = _called_by_wait; 489 bits = _bits; 490 } 491 492 ~TraceSuspendDebugBits() { 493 if (!is_wait) { 494 #if 1 495 // By default, don't trace bits for is_ext_suspend_completed() calls. 496 // That trace is very chatty. 497 return; 498 #else 499 if (!called_by_wait) { 500 // If tracing for is_ext_suspend_completed() is enabled, then only 501 // trace calls to it from wait_for_ext_suspend_completion() 502 return; 503 } 504 #endif 505 } 506 507 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 508 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 509 MutexLocker ml(Threads_lock); // needed for get_thread_name() 510 ResourceMark rm; 511 512 tty->print_cr( 513 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 514 jt->get_thread_name(), *bits); 515 516 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 517 } 518 } 519 } 520 }; 521 #undef DEBUG_FALSE_BITS 522 523 524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 525 uint32_t *bits) { 526 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 527 528 bool did_trans_retry = false; // only do thread_in_native_trans retry once 529 bool do_trans_retry; // flag to force the retry 530 531 *bits |= 0x00000001; 532 533 do { 534 do_trans_retry = false; 535 536 if (is_exiting()) { 537 // Thread is in the process of exiting. This is always checked 538 // first to reduce the risk of dereferencing a freed JavaThread. 539 *bits |= 0x00000100; 540 return false; 541 } 542 543 if (!is_external_suspend()) { 544 // Suspend request is cancelled. This is always checked before 545 // is_ext_suspended() to reduce the risk of a rogue resume 546 // confusing the thread that made the suspend request. 547 *bits |= 0x00000200; 548 return false; 549 } 550 551 if (is_ext_suspended()) { 552 // thread is suspended 553 *bits |= 0x00000400; 554 return true; 555 } 556 557 // Now that we no longer do hard suspends of threads running 558 // native code, the target thread can be changing thread state 559 // while we are in this routine: 560 // 561 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 562 // 563 // We save a copy of the thread state as observed at this moment 564 // and make our decision about suspend completeness based on the 565 // copy. This closes the race where the thread state is seen as 566 // _thread_in_native_trans in the if-thread_blocked check, but is 567 // seen as _thread_blocked in if-thread_in_native_trans check. 568 JavaThreadState save_state = thread_state(); 569 570 if (save_state == _thread_blocked && is_suspend_equivalent()) { 571 // If the thread's state is _thread_blocked and this blocking 572 // condition is known to be equivalent to a suspend, then we can 573 // consider the thread to be externally suspended. This means that 574 // the code that sets _thread_blocked has been modified to do 575 // self-suspension if the blocking condition releases. We also 576 // used to check for CONDVAR_WAIT here, but that is now covered by 577 // the _thread_blocked with self-suspension check. 578 // 579 // Return true since we wouldn't be here unless there was still an 580 // external suspend request. 581 *bits |= 0x00001000; 582 return true; 583 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 584 // Threads running native code will self-suspend on native==>VM/Java 585 // transitions. If its stack is walkable (should always be the case 586 // unless this function is called before the actual java_suspend() 587 // call), then the wait is done. 588 *bits |= 0x00002000; 589 return true; 590 } else if (!called_by_wait && !did_trans_retry && 591 save_state == _thread_in_native_trans && 592 frame_anchor()->walkable()) { 593 // The thread is transitioning from thread_in_native to another 594 // thread state. check_safepoint_and_suspend_for_native_trans() 595 // will force the thread to self-suspend. If it hasn't gotten 596 // there yet we may have caught the thread in-between the native 597 // code check above and the self-suspend. Lucky us. If we were 598 // called by wait_for_ext_suspend_completion(), then it 599 // will be doing the retries so we don't have to. 600 // 601 // Since we use the saved thread state in the if-statement above, 602 // there is a chance that the thread has already transitioned to 603 // _thread_blocked by the time we get here. In that case, we will 604 // make a single unnecessary pass through the logic below. This 605 // doesn't hurt anything since we still do the trans retry. 606 607 *bits |= 0x00004000; 608 609 // Once the thread leaves thread_in_native_trans for another 610 // thread state, we break out of this retry loop. We shouldn't 611 // need this flag to prevent us from getting back here, but 612 // sometimes paranoia is good. 613 did_trans_retry = true; 614 615 // We wait for the thread to transition to a more usable state. 616 for (int i = 1; i <= SuspendRetryCount; i++) { 617 // We used to do an "os::yield_all(i)" call here with the intention 618 // that yielding would increase on each retry. However, the parameter 619 // is ignored on Linux which means the yield didn't scale up. Waiting 620 // on the SR_lock below provides a much more predictable scale up for 621 // the delay. It also provides a simple/direct point to check for any 622 // safepoint requests from the VMThread 623 624 // temporarily drops SR_lock while doing wait with safepoint check 625 // (if we're a JavaThread - the WatcherThread can also call this) 626 // and increase delay with each retry 627 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 628 629 // check the actual thread state instead of what we saved above 630 if (thread_state() != _thread_in_native_trans) { 631 // the thread has transitioned to another thread state so 632 // try all the checks (except this one) one more time. 633 do_trans_retry = true; 634 break; 635 } 636 } // end retry loop 637 638 639 } 640 } while (do_trans_retry); 641 642 *bits |= 0x00000010; 643 return false; 644 } 645 646 // Wait for an external suspend request to complete (or be cancelled). 647 // Returns true if the thread is externally suspended and false otherwise. 648 // 649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 650 uint32_t *bits) { 651 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 652 false /* !called_by_wait */, bits); 653 654 // local flag copies to minimize SR_lock hold time 655 bool is_suspended; 656 bool pending; 657 uint32_t reset_bits; 658 659 // set a marker so is_ext_suspend_completed() knows we are the caller 660 *bits |= 0x00010000; 661 662 // We use reset_bits to reinitialize the bits value at the top of 663 // each retry loop. This allows the caller to make use of any 664 // unused bits for their own marking purposes. 665 reset_bits = *bits; 666 667 { 668 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 669 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 670 delay, bits); 671 pending = is_external_suspend(); 672 } 673 // must release SR_lock to allow suspension to complete 674 675 if (!pending) { 676 // A cancelled suspend request is the only false return from 677 // is_ext_suspend_completed() that keeps us from entering the 678 // retry loop. 679 *bits |= 0x00020000; 680 return false; 681 } 682 683 if (is_suspended) { 684 *bits |= 0x00040000; 685 return true; 686 } 687 688 for (int i = 1; i <= retries; i++) { 689 *bits = reset_bits; // reinit to only track last retry 690 691 // We used to do an "os::yield_all(i)" call here with the intention 692 // that yielding would increase on each retry. However, the parameter 693 // is ignored on Linux which means the yield didn't scale up. Waiting 694 // on the SR_lock below provides a much more predictable scale up for 695 // the delay. It also provides a simple/direct point to check for any 696 // safepoint requests from the VMThread 697 698 { 699 MutexLocker ml(SR_lock()); 700 // wait with safepoint check (if we're a JavaThread - the WatcherThread 701 // can also call this) and increase delay with each retry 702 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 703 704 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 705 delay, bits); 706 707 // It is possible for the external suspend request to be cancelled 708 // (by a resume) before the actual suspend operation is completed. 709 // Refresh our local copy to see if we still need to wait. 710 pending = is_external_suspend(); 711 } 712 713 if (!pending) { 714 // A cancelled suspend request is the only false return from 715 // is_ext_suspend_completed() that keeps us from staying in the 716 // retry loop. 717 *bits |= 0x00080000; 718 return false; 719 } 720 721 if (is_suspended) { 722 *bits |= 0x00100000; 723 return true; 724 } 725 } // end retry loop 726 727 // thread did not suspend after all our retries 728 *bits |= 0x00200000; 729 return false; 730 } 731 732 #ifndef PRODUCT 733 void JavaThread::record_jump(address target, address instr, const char* file, 734 int line) { 735 736 // This should not need to be atomic as the only way for simultaneous 737 // updates is via interrupts. Even then this should be rare or non-existent 738 // and we don't care that much anyway. 739 740 int index = _jmp_ring_index; 741 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 742 _jmp_ring[index]._target = (intptr_t) target; 743 _jmp_ring[index]._instruction = (intptr_t) instr; 744 _jmp_ring[index]._file = file; 745 _jmp_ring[index]._line = line; 746 } 747 #endif // PRODUCT 748 749 // Called by flat profiler 750 // Callers have already called wait_for_ext_suspend_completion 751 // The assertion for that is currently too complex to put here: 752 bool JavaThread::profile_last_Java_frame(frame* _fr) { 753 bool gotframe = false; 754 // self suspension saves needed state. 755 if (has_last_Java_frame() && _anchor.walkable()) { 756 *_fr = pd_last_frame(); 757 gotframe = true; 758 } 759 return gotframe; 760 } 761 762 void Thread::interrupt(Thread* thread) { 763 debug_only(check_for_dangling_thread_pointer(thread);) 764 os::interrupt(thread); 765 } 766 767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 768 debug_only(check_for_dangling_thread_pointer(thread);) 769 // Note: If clear_interrupted==false, this simply fetches and 770 // returns the value of the field osthread()->interrupted(). 771 return os::is_interrupted(thread, clear_interrupted); 772 } 773 774 775 // GC Support 776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 777 jint thread_parity = _oops_do_parity; 778 if (thread_parity != strong_roots_parity) { 779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 780 if (res == thread_parity) { 781 return true; 782 } else { 783 guarantee(res == strong_roots_parity, "Or else what?"); 784 return false; 785 } 786 } 787 return false; 788 } 789 790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 791 active_handles()->oops_do(f); 792 // Do oop for ThreadShadow 793 f->do_oop((oop*)&_pending_exception); 794 handle_area()->oops_do(f); 795 796 if (MonitorInUseLists) { 797 // When using thread local monitor lists, we scan them here, 798 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 799 ObjectSynchronizer::thread_local_used_oops_do(this, f); 800 } 801 } 802 803 void Thread::metadata_handles_do(void f(Metadata*)) { 804 // Only walk the Handles in Thread. 805 if (metadata_handles() != NULL) { 806 for (int i = 0; i< metadata_handles()->length(); i++) { 807 f(metadata_handles()->at(i)); 808 } 809 } 810 } 811 812 void Thread::print_on(outputStream* st) const { 813 // get_priority assumes osthread initialized 814 if (osthread() != NULL) { 815 int os_prio; 816 if (os::get_native_priority(this, &os_prio) == OS_OK) { 817 st->print("os_prio=%d ", os_prio); 818 } 819 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 820 ext().print_on(st); 821 osthread()->print_on(st); 822 } 823 debug_only(if (WizardMode) print_owned_locks_on(st);) 824 } 825 826 // Thread::print_on_error() is called by fatal error handler. Don't use 827 // any lock or allocate memory. 828 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 829 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 830 831 if (is_VM_thread()) { st->print("VMThread"); } 832 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 833 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 834 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 835 else { st->print("Thread"); } 836 837 if (is_Named_thread()) { 838 st->print(" \"%s\"", name()); 839 } 840 841 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 842 p2i(stack_end()), p2i(stack_base())); 843 844 if (osthread()) { 845 st->print(" [id=%d]", osthread()->thread_id()); 846 } 847 } 848 849 #ifdef ASSERT 850 void Thread::print_owned_locks_on(outputStream* st) const { 851 Monitor *cur = _owned_locks; 852 if (cur == NULL) { 853 st->print(" (no locks) "); 854 } else { 855 st->print_cr(" Locks owned:"); 856 while (cur) { 857 cur->print_on(st); 858 cur = cur->next(); 859 } 860 } 861 } 862 863 static int ref_use_count = 0; 864 865 bool Thread::owns_locks_but_compiled_lock() const { 866 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 867 if (cur != Compile_lock) return true; 868 } 869 return false; 870 } 871 872 873 #endif 874 875 #ifndef PRODUCT 876 877 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 878 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 879 // no threads which allow_vm_block's are held 880 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 881 // Check if current thread is allowed to block at a safepoint 882 if (!(_allow_safepoint_count == 0)) { 883 fatal("Possible safepoint reached by thread that does not allow it"); 884 } 885 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 886 fatal("LEAF method calling lock?"); 887 } 888 889 #ifdef ASSERT 890 if (potential_vm_operation && is_Java_thread() 891 && !Universe::is_bootstrapping()) { 892 // Make sure we do not hold any locks that the VM thread also uses. 893 // This could potentially lead to deadlocks 894 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 895 // Threads_lock is special, since the safepoint synchronization will not start before this is 896 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 897 // since it is used to transfer control between JavaThreads and the VMThread 898 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 899 if ((cur->allow_vm_block() && 900 cur != Threads_lock && 901 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 902 cur != VMOperationRequest_lock && 903 cur != VMOperationQueue_lock) || 904 cur->rank() == Mutex::special) { 905 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 906 } 907 } 908 } 909 910 if (GCALotAtAllSafepoints) { 911 // We could enter a safepoint here and thus have a gc 912 InterfaceSupport::check_gc_alot(); 913 } 914 #endif 915 } 916 #endif 917 918 bool Thread::is_in_stack(address adr) const { 919 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 920 address end = os::current_stack_pointer(); 921 // Allow non Java threads to call this without stack_base 922 if (_stack_base == NULL) return true; 923 if (stack_base() >= adr && adr >= end) return true; 924 925 return false; 926 } 927 928 bool Thread::is_in_usable_stack(address adr) const { 929 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 930 size_t usable_stack_size = _stack_size - stack_guard_size; 931 932 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 933 } 934 935 936 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 937 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 938 // used for compilation in the future. If that change is made, the need for these methods 939 // should be revisited, and they should be removed if possible. 940 941 bool Thread::is_lock_owned(address adr) const { 942 return on_local_stack(adr); 943 } 944 945 bool Thread::set_as_starting_thread() { 946 // NOTE: this must be called inside the main thread. 947 return os::create_main_thread((JavaThread*)this); 948 } 949 950 static void initialize_class(Symbol* class_name, TRAPS) { 951 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 952 InstanceKlass::cast(klass)->initialize(CHECK); 953 } 954 955 956 // Creates the initial ThreadGroup 957 static Handle create_initial_thread_group(TRAPS) { 958 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 959 InstanceKlass* ik = InstanceKlass::cast(k); 960 961 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 962 { 963 JavaValue result(T_VOID); 964 JavaCalls::call_special(&result, 965 system_instance, 966 ik, 967 vmSymbols::object_initializer_name(), 968 vmSymbols::void_method_signature(), 969 CHECK_NH); 970 } 971 Universe::set_system_thread_group(system_instance()); 972 973 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 974 { 975 JavaValue result(T_VOID); 976 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 977 JavaCalls::call_special(&result, 978 main_instance, 979 ik, 980 vmSymbols::object_initializer_name(), 981 vmSymbols::threadgroup_string_void_signature(), 982 system_instance, 983 string, 984 CHECK_NH); 985 } 986 return main_instance; 987 } 988 989 // Creates the initial Thread 990 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 991 TRAPS) { 992 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 993 InstanceKlass* ik = InstanceKlass::cast(k); 994 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 995 996 java_lang_Thread::set_thread(thread_oop(), thread); 997 java_lang_Thread::set_priority(thread_oop(), NormPriority); 998 thread->set_threadObj(thread_oop()); 999 1000 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1001 1002 JavaValue result(T_VOID); 1003 JavaCalls::call_special(&result, thread_oop, 1004 ik, 1005 vmSymbols::object_initializer_name(), 1006 vmSymbols::threadgroup_string_void_signature(), 1007 thread_group, 1008 string, 1009 CHECK_NULL); 1010 return thread_oop(); 1011 } 1012 1013 char java_runtime_name[128] = ""; 1014 char java_runtime_version[128] = ""; 1015 1016 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1017 static const char* get_java_runtime_name(TRAPS) { 1018 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1019 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1020 fieldDescriptor fd; 1021 bool found = k != NULL && 1022 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1023 vmSymbols::string_signature(), &fd); 1024 if (found) { 1025 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1026 if (name_oop == NULL) { 1027 return NULL; 1028 } 1029 const char* name = java_lang_String::as_utf8_string(name_oop, 1030 java_runtime_name, 1031 sizeof(java_runtime_name)); 1032 return name; 1033 } else { 1034 return NULL; 1035 } 1036 } 1037 1038 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1039 static const char* get_java_runtime_version(TRAPS) { 1040 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1041 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1042 fieldDescriptor fd; 1043 bool found = k != NULL && 1044 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1045 vmSymbols::string_signature(), &fd); 1046 if (found) { 1047 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1048 if (name_oop == NULL) { 1049 return NULL; 1050 } 1051 const char* name = java_lang_String::as_utf8_string(name_oop, 1052 java_runtime_version, 1053 sizeof(java_runtime_version)); 1054 return name; 1055 } else { 1056 return NULL; 1057 } 1058 } 1059 1060 // General purpose hook into Java code, run once when the VM is initialized. 1061 // The Java library method itself may be changed independently from the VM. 1062 static void call_postVMInitHook(TRAPS) { 1063 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1064 if (klass != NULL) { 1065 JavaValue result(T_VOID); 1066 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1067 vmSymbols::void_method_signature(), 1068 CHECK); 1069 } 1070 } 1071 1072 static void reset_vm_info_property(TRAPS) { 1073 // the vm info string 1074 ResourceMark rm(THREAD); 1075 const char *vm_info = VM_Version::vm_info_string(); 1076 1077 // java.lang.System class 1078 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1079 1080 // setProperty arguments 1081 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1082 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1083 1084 // return value 1085 JavaValue r(T_OBJECT); 1086 1087 // public static String setProperty(String key, String value); 1088 JavaCalls::call_static(&r, 1089 klass, 1090 vmSymbols::setProperty_name(), 1091 vmSymbols::string_string_string_signature(), 1092 key_str, 1093 value_str, 1094 CHECK); 1095 } 1096 1097 1098 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1099 bool daemon, TRAPS) { 1100 assert(thread_group.not_null(), "thread group should be specified"); 1101 assert(threadObj() == NULL, "should only create Java thread object once"); 1102 1103 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1104 InstanceKlass* ik = InstanceKlass::cast(k); 1105 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1106 1107 java_lang_Thread::set_thread(thread_oop(), this); 1108 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1109 set_threadObj(thread_oop()); 1110 1111 JavaValue result(T_VOID); 1112 if (thread_name != NULL) { 1113 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1114 // Thread gets assigned specified name and null target 1115 JavaCalls::call_special(&result, 1116 thread_oop, 1117 ik, 1118 vmSymbols::object_initializer_name(), 1119 vmSymbols::threadgroup_string_void_signature(), 1120 thread_group, // Argument 1 1121 name, // Argument 2 1122 THREAD); 1123 } else { 1124 // Thread gets assigned name "Thread-nnn" and null target 1125 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1126 JavaCalls::call_special(&result, 1127 thread_oop, 1128 ik, 1129 vmSymbols::object_initializer_name(), 1130 vmSymbols::threadgroup_runnable_void_signature(), 1131 thread_group, // Argument 1 1132 Handle(), // Argument 2 1133 THREAD); 1134 } 1135 1136 1137 if (daemon) { 1138 java_lang_Thread::set_daemon(thread_oop()); 1139 } 1140 1141 if (HAS_PENDING_EXCEPTION) { 1142 return; 1143 } 1144 1145 Klass* group = SystemDictionary::ThreadGroup_klass(); 1146 Handle threadObj(THREAD, this->threadObj()); 1147 1148 JavaCalls::call_special(&result, 1149 thread_group, 1150 group, 1151 vmSymbols::add_method_name(), 1152 vmSymbols::thread_void_signature(), 1153 threadObj, // Arg 1 1154 THREAD); 1155 } 1156 1157 // NamedThread -- non-JavaThread subclasses with multiple 1158 // uniquely named instances should derive from this. 1159 NamedThread::NamedThread() : Thread() { 1160 _name = NULL; 1161 _processed_thread = NULL; 1162 _gc_id = GCId::undefined(); 1163 } 1164 1165 NamedThread::~NamedThread() { 1166 if (_name != NULL) { 1167 FREE_C_HEAP_ARRAY(char, _name); 1168 _name = NULL; 1169 } 1170 } 1171 1172 void NamedThread::set_name(const char* format, ...) { 1173 guarantee(_name == NULL, "Only get to set name once."); 1174 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1175 guarantee(_name != NULL, "alloc failure"); 1176 va_list ap; 1177 va_start(ap, format); 1178 jio_vsnprintf(_name, max_name_len, format, ap); 1179 va_end(ap); 1180 } 1181 1182 void NamedThread::initialize_named_thread() { 1183 set_native_thread_name(name()); 1184 } 1185 1186 void NamedThread::print_on(outputStream* st) const { 1187 st->print("\"%s\" ", name()); 1188 Thread::print_on(st); 1189 st->cr(); 1190 } 1191 1192 1193 // ======= WatcherThread ======== 1194 1195 // The watcher thread exists to simulate timer interrupts. It should 1196 // be replaced by an abstraction over whatever native support for 1197 // timer interrupts exists on the platform. 1198 1199 WatcherThread* WatcherThread::_watcher_thread = NULL; 1200 bool WatcherThread::_startable = false; 1201 volatile bool WatcherThread::_should_terminate = false; 1202 1203 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1204 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1205 if (os::create_thread(this, os::watcher_thread)) { 1206 _watcher_thread = this; 1207 1208 // Set the watcher thread to the highest OS priority which should not be 1209 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1210 // is created. The only normal thread using this priority is the reference 1211 // handler thread, which runs for very short intervals only. 1212 // If the VMThread's priority is not lower than the WatcherThread profiling 1213 // will be inaccurate. 1214 os::set_priority(this, MaxPriority); 1215 if (!DisableStartThread) { 1216 os::start_thread(this); 1217 } 1218 } 1219 } 1220 1221 int WatcherThread::sleep() const { 1222 // The WatcherThread does not participate in the safepoint protocol 1223 // for the PeriodicTask_lock because it is not a JavaThread. 1224 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1225 1226 if (_should_terminate) { 1227 // check for termination before we do any housekeeping or wait 1228 return 0; // we did not sleep. 1229 } 1230 1231 // remaining will be zero if there are no tasks, 1232 // causing the WatcherThread to sleep until a task is 1233 // enrolled 1234 int remaining = PeriodicTask::time_to_wait(); 1235 int time_slept = 0; 1236 1237 // we expect this to timeout - we only ever get unparked when 1238 // we should terminate or when a new task has been enrolled 1239 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1240 1241 jlong time_before_loop = os::javaTimeNanos(); 1242 1243 while (true) { 1244 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1245 remaining); 1246 jlong now = os::javaTimeNanos(); 1247 1248 if (remaining == 0) { 1249 // if we didn't have any tasks we could have waited for a long time 1250 // consider the time_slept zero and reset time_before_loop 1251 time_slept = 0; 1252 time_before_loop = now; 1253 } else { 1254 // need to recalculate since we might have new tasks in _tasks 1255 time_slept = (int) ((now - time_before_loop) / 1000000); 1256 } 1257 1258 // Change to task list or spurious wakeup of some kind 1259 if (timedout || _should_terminate) { 1260 break; 1261 } 1262 1263 remaining = PeriodicTask::time_to_wait(); 1264 if (remaining == 0) { 1265 // Last task was just disenrolled so loop around and wait until 1266 // another task gets enrolled 1267 continue; 1268 } 1269 1270 remaining -= time_slept; 1271 if (remaining <= 0) { 1272 break; 1273 } 1274 } 1275 1276 return time_slept; 1277 } 1278 1279 void WatcherThread::run() { 1280 assert(this == watcher_thread(), "just checking"); 1281 1282 this->record_stack_base_and_size(); 1283 this->set_native_thread_name(this->name()); 1284 this->set_active_handles(JNIHandleBlock::allocate_block()); 1285 while (true) { 1286 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1287 assert(watcher_thread() == this, "thread consistency check"); 1288 1289 // Calculate how long it'll be until the next PeriodicTask work 1290 // should be done, and sleep that amount of time. 1291 int time_waited = sleep(); 1292 1293 if (is_error_reported()) { 1294 // A fatal error has happened, the error handler(VMError::report_and_die) 1295 // should abort JVM after creating an error log file. However in some 1296 // rare cases, the error handler itself might deadlock. Here periodically 1297 // check for error reporting timeouts, and if it happens, just proceed to 1298 // abort the VM. 1299 1300 // This code is in WatcherThread because WatcherThread wakes up 1301 // periodically so the fatal error handler doesn't need to do anything; 1302 // also because the WatcherThread is less likely to crash than other 1303 // threads. 1304 1305 for (;;) { 1306 // Note: we use naked sleep in this loop because we want to avoid using 1307 // any kind of VM infrastructure which may be broken at this point. 1308 if (VMError::check_timeout()) { 1309 // We hit error reporting timeout. Error reporting was interrupted and 1310 // will be wrapping things up now (closing files etc). Give it some more 1311 // time, then quit the VM. 1312 os::naked_short_sleep(200); 1313 // Print a message to stderr. 1314 fdStream err(defaultStream::output_fd()); 1315 err.print_raw_cr("# [ timer expired, abort... ]"); 1316 // skip atexit/vm_exit/vm_abort hooks 1317 os::die(); 1318 } 1319 1320 // Wait a second, then recheck for timeout. 1321 os::naked_short_sleep(999); 1322 } 1323 } 1324 1325 if (_should_terminate) { 1326 // check for termination before posting the next tick 1327 break; 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 1341 void WatcherThread::start() { 1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1343 1344 if (watcher_thread() == NULL && _startable) { 1345 _should_terminate = false; 1346 // Create the single instance of WatcherThread 1347 new WatcherThread(); 1348 } 1349 } 1350 1351 void WatcherThread::make_startable() { 1352 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1353 _startable = true; 1354 } 1355 1356 void WatcherThread::stop() { 1357 { 1358 // Follow normal safepoint aware lock enter protocol since the 1359 // WatcherThread is stopped by another JavaThread. 1360 MutexLocker ml(PeriodicTask_lock); 1361 _should_terminate = true; 1362 1363 WatcherThread* watcher = watcher_thread(); 1364 if (watcher != NULL) { 1365 // unpark the WatcherThread so it can see that it should terminate 1366 watcher->unpark(); 1367 } 1368 } 1369 1370 MutexLocker mu(Terminator_lock); 1371 1372 while (watcher_thread() != NULL) { 1373 // This wait should make safepoint checks, wait without a timeout, 1374 // and wait as a suspend-equivalent condition. 1375 // 1376 // Note: If the FlatProfiler is running, then this thread is waiting 1377 // for the WatcherThread to terminate and the WatcherThread, via the 1378 // FlatProfiler task, is waiting for the external suspend request on 1379 // this thread to complete. wait_for_ext_suspend_completion() will 1380 // eventually timeout, but that takes time. Making this wait a 1381 // suspend-equivalent condition solves that timeout problem. 1382 // 1383 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1384 Mutex::_as_suspend_equivalent_flag); 1385 } 1386 } 1387 1388 void WatcherThread::unpark() { 1389 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1390 PeriodicTask_lock->notify(); 1391 } 1392 1393 void WatcherThread::print_on(outputStream* st) const { 1394 st->print("\"%s\" ", name()); 1395 Thread::print_on(st); 1396 st->cr(); 1397 } 1398 1399 // ======= JavaThread ======== 1400 1401 #if INCLUDE_JVMCI 1402 1403 jlong* JavaThread::_jvmci_old_thread_counters; 1404 1405 bool jvmci_counters_include(JavaThread* thread) { 1406 oop threadObj = thread->threadObj(); 1407 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1408 } 1409 1410 void JavaThread::collect_counters(typeArrayOop array) { 1411 if (JVMCICounterSize > 0) { 1412 MutexLocker tl(Threads_lock); 1413 for (int i = 0; i < array->length(); i++) { 1414 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1415 } 1416 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1417 if (jvmci_counters_include(tp)) { 1418 for (int i = 0; i < array->length(); i++) { 1419 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1420 } 1421 } 1422 } 1423 } 1424 } 1425 1426 #endif // INCLUDE_JVMCI 1427 1428 // A JavaThread is a normal Java thread 1429 1430 void JavaThread::initialize() { 1431 // Initialize fields 1432 1433 set_saved_exception_pc(NULL); 1434 set_threadObj(NULL); 1435 _anchor.clear(); 1436 set_entry_point(NULL); 1437 set_jni_functions(jni_functions()); 1438 set_callee_target(NULL); 1439 set_vm_result(NULL); 1440 set_vm_result_2(NULL); 1441 set_vframe_array_head(NULL); 1442 set_vframe_array_last(NULL); 1443 set_deferred_locals(NULL); 1444 set_deopt_mark(NULL); 1445 set_deopt_compiled_method(NULL); 1446 clear_must_deopt_id(); 1447 set_monitor_chunks(NULL); 1448 set_next(NULL); 1449 set_thread_state(_thread_new); 1450 _terminated = _not_terminated; 1451 _privileged_stack_top = NULL; 1452 _array_for_gc = NULL; 1453 _suspend_equivalent = false; 1454 _in_deopt_handler = 0; 1455 _doing_unsafe_access = false; 1456 _stack_guard_state = stack_guard_unused; 1457 #if INCLUDE_JVMCI 1458 _pending_monitorenter = false; 1459 _pending_deoptimization = -1; 1460 _pending_failed_speculation = NULL; 1461 _pending_transfer_to_interpreter = false; 1462 _adjusting_comp_level = false; 1463 _jvmci._alternate_call_target = NULL; 1464 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1465 if (JVMCICounterSize > 0) { 1466 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1467 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1468 } else { 1469 _jvmci_counters = NULL; 1470 } 1471 #endif // INCLUDE_JVMCI 1472 _reserved_stack_activation = NULL; // stack base not known yet 1473 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1474 _exception_pc = 0; 1475 _exception_handler_pc = 0; 1476 _is_method_handle_return = 0; 1477 _jvmti_thread_state= NULL; 1478 _should_post_on_exceptions_flag = JNI_FALSE; 1479 _jvmti_get_loaded_classes_closure = NULL; 1480 _interp_only_mode = 0; 1481 _special_runtime_exit_condition = _no_async_condition; 1482 _pending_async_exception = NULL; 1483 _thread_stat = NULL; 1484 _thread_stat = new ThreadStatistics(); 1485 _blocked_on_compilation = false; 1486 _jni_active_critical = 0; 1487 _pending_jni_exception_check_fn = NULL; 1488 _do_not_unlock_if_synchronized = false; 1489 _cached_monitor_info = NULL; 1490 _parker = Parker::Allocate(this); 1491 1492 #ifndef PRODUCT 1493 _jmp_ring_index = 0; 1494 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1495 record_jump(NULL, NULL, NULL, 0); 1496 } 1497 #endif // PRODUCT 1498 1499 set_thread_profiler(NULL); 1500 if (FlatProfiler::is_active()) { 1501 // This is where we would decide to either give each thread it's own profiler 1502 // or use one global one from FlatProfiler, 1503 // or up to some count of the number of profiled threads, etc. 1504 ThreadProfiler* pp = new ThreadProfiler(); 1505 pp->engage(); 1506 set_thread_profiler(pp); 1507 } 1508 1509 // Setup safepoint state info for this thread 1510 ThreadSafepointState::create(this); 1511 1512 debug_only(_java_call_counter = 0); 1513 1514 // JVMTI PopFrame support 1515 _popframe_condition = popframe_inactive; 1516 _popframe_preserved_args = NULL; 1517 _popframe_preserved_args_size = 0; 1518 _frames_to_pop_failed_realloc = 0; 1519 1520 pd_initialize(); 1521 } 1522 1523 #if INCLUDE_ALL_GCS 1524 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1525 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1526 #endif // INCLUDE_ALL_GCS 1527 1528 JavaThread::JavaThread(bool is_attaching_via_jni) : 1529 Thread() 1530 #if INCLUDE_ALL_GCS 1531 , _satb_mark_queue(&_satb_mark_queue_set), 1532 _dirty_card_queue(&_dirty_card_queue_set) 1533 #endif // INCLUDE_ALL_GCS 1534 { 1535 initialize(); 1536 if (is_attaching_via_jni) { 1537 _jni_attach_state = _attaching_via_jni; 1538 } else { 1539 _jni_attach_state = _not_attaching_via_jni; 1540 } 1541 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1542 } 1543 1544 bool JavaThread::reguard_stack(address cur_sp) { 1545 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1546 && _stack_guard_state != stack_guard_reserved_disabled) { 1547 return true; // Stack already guarded or guard pages not needed. 1548 } 1549 1550 if (register_stack_overflow()) { 1551 // For those architectures which have separate register and 1552 // memory stacks, we must check the register stack to see if 1553 // it has overflowed. 1554 return false; 1555 } 1556 1557 // Java code never executes within the yellow zone: the latter is only 1558 // there to provoke an exception during stack banging. If java code 1559 // is executing there, either StackShadowPages should be larger, or 1560 // some exception code in c1, c2 or the interpreter isn't unwinding 1561 // when it should. 1562 guarantee(cur_sp > stack_reserved_zone_base(), 1563 "not enough space to reguard - increase StackShadowPages"); 1564 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1565 enable_stack_yellow_reserved_zone(); 1566 if (reserved_stack_activation() != stack_base()) { 1567 set_reserved_stack_activation(stack_base()); 1568 } 1569 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1570 set_reserved_stack_activation(stack_base()); 1571 enable_stack_reserved_zone(); 1572 } 1573 return true; 1574 } 1575 1576 bool JavaThread::reguard_stack(void) { 1577 return reguard_stack(os::current_stack_pointer()); 1578 } 1579 1580 1581 void JavaThread::block_if_vm_exited() { 1582 if (_terminated == _vm_exited) { 1583 // _vm_exited is set at safepoint, and Threads_lock is never released 1584 // we will block here forever 1585 Threads_lock->lock_without_safepoint_check(); 1586 ShouldNotReachHere(); 1587 } 1588 } 1589 1590 1591 // Remove this ifdef when C1 is ported to the compiler interface. 1592 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1593 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1594 1595 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1596 Thread() 1597 #if INCLUDE_ALL_GCS 1598 , _satb_mark_queue(&_satb_mark_queue_set), 1599 _dirty_card_queue(&_dirty_card_queue_set) 1600 #endif // INCLUDE_ALL_GCS 1601 { 1602 initialize(); 1603 _jni_attach_state = _not_attaching_via_jni; 1604 set_entry_point(entry_point); 1605 // Create the native thread itself. 1606 // %note runtime_23 1607 os::ThreadType thr_type = os::java_thread; 1608 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1609 os::java_thread; 1610 os::create_thread(this, thr_type, stack_sz); 1611 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1612 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1613 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1614 // the exception consists of creating the exception object & initializing it, initialization 1615 // will leave the VM via a JavaCall and then all locks must be unlocked). 1616 // 1617 // The thread is still suspended when we reach here. Thread must be explicit started 1618 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1619 // by calling Threads:add. The reason why this is not done here, is because the thread 1620 // object must be fully initialized (take a look at JVM_Start) 1621 } 1622 1623 JavaThread::~JavaThread() { 1624 1625 // JSR166 -- return the parker to the free list 1626 Parker::Release(_parker); 1627 _parker = NULL; 1628 1629 // Free any remaining previous UnrollBlock 1630 vframeArray* old_array = vframe_array_last(); 1631 1632 if (old_array != NULL) { 1633 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1634 old_array->set_unroll_block(NULL); 1635 delete old_info; 1636 delete old_array; 1637 } 1638 1639 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1640 if (deferred != NULL) { 1641 // This can only happen if thread is destroyed before deoptimization occurs. 1642 assert(deferred->length() != 0, "empty array!"); 1643 do { 1644 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1645 deferred->remove_at(0); 1646 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1647 delete dlv; 1648 } while (deferred->length() != 0); 1649 delete deferred; 1650 } 1651 1652 // All Java related clean up happens in exit 1653 ThreadSafepointState::destroy(this); 1654 if (_thread_profiler != NULL) delete _thread_profiler; 1655 if (_thread_stat != NULL) delete _thread_stat; 1656 1657 #if INCLUDE_JVMCI 1658 if (JVMCICounterSize > 0) { 1659 if (jvmci_counters_include(this)) { 1660 for (int i = 0; i < JVMCICounterSize; i++) { 1661 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1662 } 1663 } 1664 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1665 } 1666 #endif // INCLUDE_JVMCI 1667 } 1668 1669 1670 // The first routine called by a new Java thread 1671 void JavaThread::run() { 1672 // initialize thread-local alloc buffer related fields 1673 this->initialize_tlab(); 1674 1675 // used to test validity of stack trace backs 1676 this->record_base_of_stack_pointer(); 1677 1678 // Record real stack base and size. 1679 this->record_stack_base_and_size(); 1680 1681 this->create_stack_guard_pages(); 1682 1683 this->cache_global_variables(); 1684 1685 // Thread is now sufficient initialized to be handled by the safepoint code as being 1686 // in the VM. Change thread state from _thread_new to _thread_in_vm 1687 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1688 1689 assert(JavaThread::current() == this, "sanity check"); 1690 assert(!Thread::current()->owns_locks(), "sanity check"); 1691 1692 DTRACE_THREAD_PROBE(start, this); 1693 1694 // This operation might block. We call that after all safepoint checks for a new thread has 1695 // been completed. 1696 this->set_active_handles(JNIHandleBlock::allocate_block()); 1697 1698 if (JvmtiExport::should_post_thread_life()) { 1699 JvmtiExport::post_thread_start(this); 1700 } 1701 1702 EventThreadStart event; 1703 if (event.should_commit()) { 1704 event.set_thread(THREAD_TRACE_ID(this)); 1705 event.commit(); 1706 } 1707 1708 // We call another function to do the rest so we are sure that the stack addresses used 1709 // from there will be lower than the stack base just computed 1710 thread_main_inner(); 1711 1712 // Note, thread is no longer valid at this point! 1713 } 1714 1715 1716 void JavaThread::thread_main_inner() { 1717 assert(JavaThread::current() == this, "sanity check"); 1718 assert(this->threadObj() != NULL, "just checking"); 1719 1720 // Execute thread entry point unless this thread has a pending exception 1721 // or has been stopped before starting. 1722 // Note: Due to JVM_StopThread we can have pending exceptions already! 1723 if (!this->has_pending_exception() && 1724 !java_lang_Thread::is_stillborn(this->threadObj())) { 1725 { 1726 ResourceMark rm(this); 1727 this->set_native_thread_name(this->get_thread_name()); 1728 } 1729 HandleMark hm(this); 1730 this->entry_point()(this, this); 1731 } 1732 1733 DTRACE_THREAD_PROBE(stop, this); 1734 1735 this->exit(false); 1736 delete this; 1737 } 1738 1739 1740 static void ensure_join(JavaThread* thread) { 1741 // We do not need to grap the Threads_lock, since we are operating on ourself. 1742 Handle threadObj(thread, thread->threadObj()); 1743 assert(threadObj.not_null(), "java thread object must exist"); 1744 ObjectLocker lock(threadObj, thread); 1745 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1746 thread->clear_pending_exception(); 1747 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1748 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1749 // Clear the native thread instance - this makes isAlive return false and allows the join() 1750 // to complete once we've done the notify_all below 1751 java_lang_Thread::set_thread(threadObj(), NULL); 1752 lock.notify_all(thread); 1753 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1754 thread->clear_pending_exception(); 1755 } 1756 1757 1758 // For any new cleanup additions, please check to see if they need to be applied to 1759 // cleanup_failed_attach_current_thread as well. 1760 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1761 assert(this == JavaThread::current(), "thread consistency check"); 1762 1763 HandleMark hm(this); 1764 Handle uncaught_exception(this, this->pending_exception()); 1765 this->clear_pending_exception(); 1766 Handle threadObj(this, this->threadObj()); 1767 assert(threadObj.not_null(), "Java thread object should be created"); 1768 1769 if (get_thread_profiler() != NULL) { 1770 get_thread_profiler()->disengage(); 1771 ResourceMark rm; 1772 get_thread_profiler()->print(get_thread_name()); 1773 } 1774 1775 1776 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1777 { 1778 EXCEPTION_MARK; 1779 1780 CLEAR_PENDING_EXCEPTION; 1781 } 1782 if (!destroy_vm) { 1783 if (uncaught_exception.not_null()) { 1784 EXCEPTION_MARK; 1785 // Call method Thread.dispatchUncaughtException(). 1786 Klass* thread_klass = SystemDictionary::Thread_klass(); 1787 JavaValue result(T_VOID); 1788 JavaCalls::call_virtual(&result, 1789 threadObj, thread_klass, 1790 vmSymbols::dispatchUncaughtException_name(), 1791 vmSymbols::throwable_void_signature(), 1792 uncaught_exception, 1793 THREAD); 1794 if (HAS_PENDING_EXCEPTION) { 1795 ResourceMark rm(this); 1796 jio_fprintf(defaultStream::error_stream(), 1797 "\nException: %s thrown from the UncaughtExceptionHandler" 1798 " in thread \"%s\"\n", 1799 pending_exception()->klass()->external_name(), 1800 get_thread_name()); 1801 CLEAR_PENDING_EXCEPTION; 1802 } 1803 } 1804 1805 // Called before the java thread exit since we want to read info 1806 // from java_lang_Thread object 1807 EventThreadEnd event; 1808 if (event.should_commit()) { 1809 event.set_thread(THREAD_TRACE_ID(this)); 1810 event.commit(); 1811 } 1812 1813 // Call after last event on thread 1814 EVENT_THREAD_EXIT(this); 1815 1816 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1817 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1818 // is deprecated anyhow. 1819 if (!is_Compiler_thread()) { 1820 int count = 3; 1821 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1822 EXCEPTION_MARK; 1823 JavaValue result(T_VOID); 1824 Klass* thread_klass = SystemDictionary::Thread_klass(); 1825 JavaCalls::call_virtual(&result, 1826 threadObj, thread_klass, 1827 vmSymbols::exit_method_name(), 1828 vmSymbols::void_method_signature(), 1829 THREAD); 1830 CLEAR_PENDING_EXCEPTION; 1831 } 1832 } 1833 // notify JVMTI 1834 if (JvmtiExport::should_post_thread_life()) { 1835 JvmtiExport::post_thread_end(this); 1836 } 1837 1838 // We have notified the agents that we are exiting, before we go on, 1839 // we must check for a pending external suspend request and honor it 1840 // in order to not surprise the thread that made the suspend request. 1841 while (true) { 1842 { 1843 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1844 if (!is_external_suspend()) { 1845 set_terminated(_thread_exiting); 1846 ThreadService::current_thread_exiting(this); 1847 break; 1848 } 1849 // Implied else: 1850 // Things get a little tricky here. We have a pending external 1851 // suspend request, but we are holding the SR_lock so we 1852 // can't just self-suspend. So we temporarily drop the lock 1853 // and then self-suspend. 1854 } 1855 1856 ThreadBlockInVM tbivm(this); 1857 java_suspend_self(); 1858 1859 // We're done with this suspend request, but we have to loop around 1860 // and check again. Eventually we will get SR_lock without a pending 1861 // external suspend request and will be able to mark ourselves as 1862 // exiting. 1863 } 1864 // no more external suspends are allowed at this point 1865 } else { 1866 // before_exit() has already posted JVMTI THREAD_END events 1867 } 1868 1869 // Notify waiters on thread object. This has to be done after exit() is called 1870 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1871 // group should have the destroyed bit set before waiters are notified). 1872 ensure_join(this); 1873 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1874 1875 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1876 // held by this thread must be released. The spec does not distinguish 1877 // between JNI-acquired and regular Java monitors. We can only see 1878 // regular Java monitors here if monitor enter-exit matching is broken. 1879 // 1880 // Optionally release any monitors for regular JavaThread exits. This 1881 // is provided as a work around for any bugs in monitor enter-exit 1882 // matching. This can be expensive so it is not enabled by default. 1883 // 1884 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1885 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1886 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1887 // Sanity check even though JNI DetachCurrentThread() would have 1888 // returned JNI_ERR if there was a Java frame. JavaThread exit 1889 // should be done executing Java code by the time we get here. 1890 assert(!this->has_last_Java_frame(), 1891 "should not have a Java frame when detaching or exiting"); 1892 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1893 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1894 } 1895 1896 // These things needs to be done while we are still a Java Thread. Make sure that thread 1897 // is in a consistent state, in case GC happens 1898 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1899 1900 if (active_handles() != NULL) { 1901 JNIHandleBlock* block = active_handles(); 1902 set_active_handles(NULL); 1903 JNIHandleBlock::release_block(block); 1904 } 1905 1906 if (free_handle_block() != NULL) { 1907 JNIHandleBlock* block = free_handle_block(); 1908 set_free_handle_block(NULL); 1909 JNIHandleBlock::release_block(block); 1910 } 1911 1912 // These have to be removed while this is still a valid thread. 1913 remove_stack_guard_pages(); 1914 1915 if (UseTLAB) { 1916 tlab().make_parsable(true); // retire TLAB 1917 } 1918 1919 if (JvmtiEnv::environments_might_exist()) { 1920 JvmtiExport::cleanup_thread(this); 1921 } 1922 1923 // We must flush any deferred card marks before removing a thread from 1924 // the list of active threads. 1925 Universe::heap()->flush_deferred_store_barrier(this); 1926 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1927 1928 #if INCLUDE_ALL_GCS 1929 // We must flush the G1-related buffers before removing a thread 1930 // from the list of active threads. We must do this after any deferred 1931 // card marks have been flushed (above) so that any entries that are 1932 // added to the thread's dirty card queue as a result are not lost. 1933 if (UseG1GC) { 1934 flush_barrier_queues(); 1935 } 1936 #endif // INCLUDE_ALL_GCS 1937 1938 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1939 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1940 os::current_thread_id()); 1941 1942 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1943 Threads::remove(this); 1944 } 1945 1946 #if INCLUDE_ALL_GCS 1947 // Flush G1-related queues. 1948 void JavaThread::flush_barrier_queues() { 1949 satb_mark_queue().flush(); 1950 dirty_card_queue().flush(); 1951 } 1952 1953 void JavaThread::initialize_queues() { 1954 assert(!SafepointSynchronize::is_at_safepoint(), 1955 "we should not be at a safepoint"); 1956 1957 SATBMarkQueue& satb_queue = satb_mark_queue(); 1958 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1959 // The SATB queue should have been constructed with its active 1960 // field set to false. 1961 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1962 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1963 // If we are creating the thread during a marking cycle, we should 1964 // set the active field of the SATB queue to true. 1965 if (satb_queue_set.is_active()) { 1966 satb_queue.set_active(true); 1967 } 1968 1969 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1970 // The dirty card queue should have been constructed with its 1971 // active field set to true. 1972 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1973 } 1974 #endif // INCLUDE_ALL_GCS 1975 1976 void JavaThread::cleanup_failed_attach_current_thread() { 1977 if (get_thread_profiler() != NULL) { 1978 get_thread_profiler()->disengage(); 1979 ResourceMark rm; 1980 get_thread_profiler()->print(get_thread_name()); 1981 } 1982 1983 if (active_handles() != NULL) { 1984 JNIHandleBlock* block = active_handles(); 1985 set_active_handles(NULL); 1986 JNIHandleBlock::release_block(block); 1987 } 1988 1989 if (free_handle_block() != NULL) { 1990 JNIHandleBlock* block = free_handle_block(); 1991 set_free_handle_block(NULL); 1992 JNIHandleBlock::release_block(block); 1993 } 1994 1995 // These have to be removed while this is still a valid thread. 1996 remove_stack_guard_pages(); 1997 1998 if (UseTLAB) { 1999 tlab().make_parsable(true); // retire TLAB, if any 2000 } 2001 2002 #if INCLUDE_ALL_GCS 2003 if (UseG1GC) { 2004 flush_barrier_queues(); 2005 } 2006 #endif // INCLUDE_ALL_GCS 2007 2008 Threads::remove(this); 2009 delete this; 2010 } 2011 2012 2013 2014 2015 JavaThread* JavaThread::active() { 2016 Thread* thread = Thread::current(); 2017 if (thread->is_Java_thread()) { 2018 return (JavaThread*) thread; 2019 } else { 2020 assert(thread->is_VM_thread(), "this must be a vm thread"); 2021 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2022 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2023 assert(ret->is_Java_thread(), "must be a Java thread"); 2024 return ret; 2025 } 2026 } 2027 2028 bool JavaThread::is_lock_owned(address adr) const { 2029 if (Thread::is_lock_owned(adr)) return true; 2030 2031 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2032 if (chunk->contains(adr)) return true; 2033 } 2034 2035 return false; 2036 } 2037 2038 2039 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2040 chunk->set_next(monitor_chunks()); 2041 set_monitor_chunks(chunk); 2042 } 2043 2044 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2045 guarantee(monitor_chunks() != NULL, "must be non empty"); 2046 if (monitor_chunks() == chunk) { 2047 set_monitor_chunks(chunk->next()); 2048 } else { 2049 MonitorChunk* prev = monitor_chunks(); 2050 while (prev->next() != chunk) prev = prev->next(); 2051 prev->set_next(chunk->next()); 2052 } 2053 } 2054 2055 // JVM support. 2056 2057 // Note: this function shouldn't block if it's called in 2058 // _thread_in_native_trans state (such as from 2059 // check_special_condition_for_native_trans()). 2060 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2061 2062 if (has_last_Java_frame() && has_async_condition()) { 2063 // If we are at a polling page safepoint (not a poll return) 2064 // then we must defer async exception because live registers 2065 // will be clobbered by the exception path. Poll return is 2066 // ok because the call we a returning from already collides 2067 // with exception handling registers and so there is no issue. 2068 // (The exception handling path kills call result registers but 2069 // this is ok since the exception kills the result anyway). 2070 2071 if (is_at_poll_safepoint()) { 2072 // if the code we are returning to has deoptimized we must defer 2073 // the exception otherwise live registers get clobbered on the 2074 // exception path before deoptimization is able to retrieve them. 2075 // 2076 RegisterMap map(this, false); 2077 frame caller_fr = last_frame().sender(&map); 2078 assert(caller_fr.is_compiled_frame(), "what?"); 2079 if (caller_fr.is_deoptimized_frame()) { 2080 log_info(exceptions)("deferred async exception at compiled safepoint"); 2081 return; 2082 } 2083 } 2084 } 2085 2086 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2087 if (condition == _no_async_condition) { 2088 // Conditions have changed since has_special_runtime_exit_condition() 2089 // was called: 2090 // - if we were here only because of an external suspend request, 2091 // then that was taken care of above (or cancelled) so we are done 2092 // - if we were here because of another async request, then it has 2093 // been cleared between the has_special_runtime_exit_condition() 2094 // and now so again we are done 2095 return; 2096 } 2097 2098 // Check for pending async. exception 2099 if (_pending_async_exception != NULL) { 2100 // Only overwrite an already pending exception, if it is not a threadDeath. 2101 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2102 2103 // We cannot call Exceptions::_throw(...) here because we cannot block 2104 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2105 2106 if (log_is_enabled(Info, exceptions)) { 2107 ResourceMark rm; 2108 outputStream* logstream = Log(exceptions)::info_stream(); 2109 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2110 if (has_last_Java_frame()) { 2111 frame f = last_frame(); 2112 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2113 } 2114 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2115 } 2116 _pending_async_exception = NULL; 2117 clear_has_async_exception(); 2118 } 2119 } 2120 2121 if (check_unsafe_error && 2122 condition == _async_unsafe_access_error && !has_pending_exception()) { 2123 condition = _no_async_condition; // done 2124 switch (thread_state()) { 2125 case _thread_in_vm: { 2126 JavaThread* THREAD = this; 2127 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2128 } 2129 case _thread_in_native: { 2130 ThreadInVMfromNative tiv(this); 2131 JavaThread* THREAD = this; 2132 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2133 } 2134 case _thread_in_Java: { 2135 ThreadInVMfromJava tiv(this); 2136 JavaThread* THREAD = this; 2137 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2138 } 2139 default: 2140 ShouldNotReachHere(); 2141 } 2142 } 2143 2144 assert(condition == _no_async_condition || has_pending_exception() || 2145 (!check_unsafe_error && condition == _async_unsafe_access_error), 2146 "must have handled the async condition, if no exception"); 2147 } 2148 2149 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2150 // 2151 // Check for pending external suspend. Internal suspend requests do 2152 // not use handle_special_runtime_exit_condition(). 2153 // If JNIEnv proxies are allowed, don't self-suspend if the target 2154 // thread is not the current thread. In older versions of jdbx, jdbx 2155 // threads could call into the VM with another thread's JNIEnv so we 2156 // can be here operating on behalf of a suspended thread (4432884). 2157 bool do_self_suspend = is_external_suspend_with_lock(); 2158 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2159 // 2160 // Because thread is external suspended the safepoint code will count 2161 // thread as at a safepoint. This can be odd because we can be here 2162 // as _thread_in_Java which would normally transition to _thread_blocked 2163 // at a safepoint. We would like to mark the thread as _thread_blocked 2164 // before calling java_suspend_self like all other callers of it but 2165 // we must then observe proper safepoint protocol. (We can't leave 2166 // _thread_blocked with a safepoint in progress). However we can be 2167 // here as _thread_in_native_trans so we can't use a normal transition 2168 // constructor/destructor pair because they assert on that type of 2169 // transition. We could do something like: 2170 // 2171 // JavaThreadState state = thread_state(); 2172 // set_thread_state(_thread_in_vm); 2173 // { 2174 // ThreadBlockInVM tbivm(this); 2175 // java_suspend_self() 2176 // } 2177 // set_thread_state(_thread_in_vm_trans); 2178 // if (safepoint) block; 2179 // set_thread_state(state); 2180 // 2181 // but that is pretty messy. Instead we just go with the way the 2182 // code has worked before and note that this is the only path to 2183 // java_suspend_self that doesn't put the thread in _thread_blocked 2184 // mode. 2185 2186 frame_anchor()->make_walkable(this); 2187 java_suspend_self(); 2188 2189 // We might be here for reasons in addition to the self-suspend request 2190 // so check for other async requests. 2191 } 2192 2193 if (check_asyncs) { 2194 check_and_handle_async_exceptions(); 2195 } 2196 } 2197 2198 void JavaThread::send_thread_stop(oop java_throwable) { 2199 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2200 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2201 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2202 2203 // Do not throw asynchronous exceptions against the compiler thread 2204 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2205 if (!can_call_java()) return; 2206 2207 { 2208 // Actually throw the Throwable against the target Thread - however 2209 // only if there is no thread death exception installed already. 2210 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2211 // If the topmost frame is a runtime stub, then we are calling into 2212 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2213 // must deoptimize the caller before continuing, as the compiled exception handler table 2214 // may not be valid 2215 if (has_last_Java_frame()) { 2216 frame f = last_frame(); 2217 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2218 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2219 RegisterMap reg_map(this, UseBiasedLocking); 2220 frame compiled_frame = f.sender(®_map); 2221 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2222 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2223 } 2224 } 2225 } 2226 2227 // Set async. pending exception in thread. 2228 set_pending_async_exception(java_throwable); 2229 2230 if (log_is_enabled(Info, exceptions)) { 2231 ResourceMark rm; 2232 log_info(exceptions)("Pending Async. exception installed of type: %s", 2233 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2234 } 2235 // for AbortVMOnException flag 2236 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2237 } 2238 } 2239 2240 2241 // Interrupt thread so it will wake up from a potential wait() 2242 Thread::interrupt(this); 2243 } 2244 2245 // External suspension mechanism. 2246 // 2247 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2248 // to any VM_locks and it is at a transition 2249 // Self-suspension will happen on the transition out of the vm. 2250 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2251 // 2252 // Guarantees on return: 2253 // + Target thread will not execute any new bytecode (that's why we need to 2254 // force a safepoint) 2255 // + Target thread will not enter any new monitors 2256 // 2257 void JavaThread::java_suspend() { 2258 { MutexLocker mu(Threads_lock); 2259 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2260 return; 2261 } 2262 } 2263 2264 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2265 if (!is_external_suspend()) { 2266 // a racing resume has cancelled us; bail out now 2267 return; 2268 } 2269 2270 // suspend is done 2271 uint32_t debug_bits = 0; 2272 // Warning: is_ext_suspend_completed() may temporarily drop the 2273 // SR_lock to allow the thread to reach a stable thread state if 2274 // it is currently in a transient thread state. 2275 if (is_ext_suspend_completed(false /* !called_by_wait */, 2276 SuspendRetryDelay, &debug_bits)) { 2277 return; 2278 } 2279 } 2280 2281 VM_ForceSafepoint vm_suspend; 2282 VMThread::execute(&vm_suspend); 2283 } 2284 2285 // Part II of external suspension. 2286 // A JavaThread self suspends when it detects a pending external suspend 2287 // request. This is usually on transitions. It is also done in places 2288 // where continuing to the next transition would surprise the caller, 2289 // e.g., monitor entry. 2290 // 2291 // Returns the number of times that the thread self-suspended. 2292 // 2293 // Note: DO NOT call java_suspend_self() when you just want to block current 2294 // thread. java_suspend_self() is the second stage of cooperative 2295 // suspension for external suspend requests and should only be used 2296 // to complete an external suspend request. 2297 // 2298 int JavaThread::java_suspend_self() { 2299 int ret = 0; 2300 2301 // we are in the process of exiting so don't suspend 2302 if (is_exiting()) { 2303 clear_external_suspend(); 2304 return ret; 2305 } 2306 2307 assert(_anchor.walkable() || 2308 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2309 "must have walkable stack"); 2310 2311 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2312 2313 assert(!this->is_ext_suspended(), 2314 "a thread trying to self-suspend should not already be suspended"); 2315 2316 if (this->is_suspend_equivalent()) { 2317 // If we are self-suspending as a result of the lifting of a 2318 // suspend equivalent condition, then the suspend_equivalent 2319 // flag is not cleared until we set the ext_suspended flag so 2320 // that wait_for_ext_suspend_completion() returns consistent 2321 // results. 2322 this->clear_suspend_equivalent(); 2323 } 2324 2325 // A racing resume may have cancelled us before we grabbed SR_lock 2326 // above. Or another external suspend request could be waiting for us 2327 // by the time we return from SR_lock()->wait(). The thread 2328 // that requested the suspension may already be trying to walk our 2329 // stack and if we return now, we can change the stack out from under 2330 // it. This would be a "bad thing (TM)" and cause the stack walker 2331 // to crash. We stay self-suspended until there are no more pending 2332 // external suspend requests. 2333 while (is_external_suspend()) { 2334 ret++; 2335 this->set_ext_suspended(); 2336 2337 // _ext_suspended flag is cleared by java_resume() 2338 while (is_ext_suspended()) { 2339 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2340 } 2341 } 2342 2343 return ret; 2344 } 2345 2346 #ifdef ASSERT 2347 // verify the JavaThread has not yet been published in the Threads::list, and 2348 // hence doesn't need protection from concurrent access at this stage 2349 void JavaThread::verify_not_published() { 2350 if (!Threads_lock->owned_by_self()) { 2351 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2352 assert(!Threads::includes(this), 2353 "java thread shouldn't have been published yet!"); 2354 } else { 2355 assert(!Threads::includes(this), 2356 "java thread shouldn't have been published yet!"); 2357 } 2358 } 2359 #endif 2360 2361 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2362 // progress or when _suspend_flags is non-zero. 2363 // Current thread needs to self-suspend if there is a suspend request and/or 2364 // block if a safepoint is in progress. 2365 // Async exception ISN'T checked. 2366 // Note only the ThreadInVMfromNative transition can call this function 2367 // directly and when thread state is _thread_in_native_trans 2368 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2369 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2370 2371 JavaThread *curJT = JavaThread::current(); 2372 bool do_self_suspend = thread->is_external_suspend(); 2373 2374 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2375 2376 // If JNIEnv proxies are allowed, don't self-suspend if the target 2377 // thread is not the current thread. In older versions of jdbx, jdbx 2378 // threads could call into the VM with another thread's JNIEnv so we 2379 // can be here operating on behalf of a suspended thread (4432884). 2380 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2381 JavaThreadState state = thread->thread_state(); 2382 2383 // We mark this thread_blocked state as a suspend-equivalent so 2384 // that a caller to is_ext_suspend_completed() won't be confused. 2385 // The suspend-equivalent state is cleared by java_suspend_self(). 2386 thread->set_suspend_equivalent(); 2387 2388 // If the safepoint code sees the _thread_in_native_trans state, it will 2389 // wait until the thread changes to other thread state. There is no 2390 // guarantee on how soon we can obtain the SR_lock and complete the 2391 // self-suspend request. It would be a bad idea to let safepoint wait for 2392 // too long. Temporarily change the state to _thread_blocked to 2393 // let the VM thread know that this thread is ready for GC. The problem 2394 // of changing thread state is that safepoint could happen just after 2395 // java_suspend_self() returns after being resumed, and VM thread will 2396 // see the _thread_blocked state. We must check for safepoint 2397 // after restoring the state and make sure we won't leave while a safepoint 2398 // is in progress. 2399 thread->set_thread_state(_thread_blocked); 2400 thread->java_suspend_self(); 2401 thread->set_thread_state(state); 2402 // Make sure new state is seen by VM thread 2403 if (os::is_MP()) { 2404 if (UseMembar) { 2405 // Force a fence between the write above and read below 2406 OrderAccess::fence(); 2407 } else { 2408 // Must use this rather than serialization page in particular on Windows 2409 InterfaceSupport::serialize_memory(thread); 2410 } 2411 } 2412 } 2413 2414 if (SafepointSynchronize::do_call_back()) { 2415 // If we are safepointing, then block the caller which may not be 2416 // the same as the target thread (see above). 2417 SafepointSynchronize::block(curJT); 2418 } 2419 2420 if (thread->is_deopt_suspend()) { 2421 thread->clear_deopt_suspend(); 2422 RegisterMap map(thread, false); 2423 frame f = thread->last_frame(); 2424 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2425 f = f.sender(&map); 2426 } 2427 if (f.id() == thread->must_deopt_id()) { 2428 thread->clear_must_deopt_id(); 2429 f.deoptimize(thread); 2430 } else { 2431 fatal("missed deoptimization!"); 2432 } 2433 } 2434 } 2435 2436 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2437 // progress or when _suspend_flags is non-zero. 2438 // Current thread needs to self-suspend if there is a suspend request and/or 2439 // block if a safepoint is in progress. 2440 // Also check for pending async exception (not including unsafe access error). 2441 // Note only the native==>VM/Java barriers can call this function and when 2442 // thread state is _thread_in_native_trans. 2443 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2444 check_safepoint_and_suspend_for_native_trans(thread); 2445 2446 if (thread->has_async_exception()) { 2447 // We are in _thread_in_native_trans state, don't handle unsafe 2448 // access error since that may block. 2449 thread->check_and_handle_async_exceptions(false); 2450 } 2451 } 2452 2453 // This is a variant of the normal 2454 // check_special_condition_for_native_trans with slightly different 2455 // semantics for use by critical native wrappers. It does all the 2456 // normal checks but also performs the transition back into 2457 // thread_in_Java state. This is required so that critical natives 2458 // can potentially block and perform a GC if they are the last thread 2459 // exiting the GCLocker. 2460 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2461 check_special_condition_for_native_trans(thread); 2462 2463 // Finish the transition 2464 thread->set_thread_state(_thread_in_Java); 2465 2466 if (thread->do_critical_native_unlock()) { 2467 ThreadInVMfromJavaNoAsyncException tiv(thread); 2468 GCLocker::unlock_critical(thread); 2469 thread->clear_critical_native_unlock(); 2470 } 2471 } 2472 2473 // We need to guarantee the Threads_lock here, since resumes are not 2474 // allowed during safepoint synchronization 2475 // Can only resume from an external suspension 2476 void JavaThread::java_resume() { 2477 assert_locked_or_safepoint(Threads_lock); 2478 2479 // Sanity check: thread is gone, has started exiting or the thread 2480 // was not externally suspended. 2481 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2482 return; 2483 } 2484 2485 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2486 2487 clear_external_suspend(); 2488 2489 if (is_ext_suspended()) { 2490 clear_ext_suspended(); 2491 SR_lock()->notify_all(); 2492 } 2493 } 2494 2495 size_t JavaThread::_stack_red_zone_size = 0; 2496 size_t JavaThread::_stack_yellow_zone_size = 0; 2497 size_t JavaThread::_stack_reserved_zone_size = 0; 2498 size_t JavaThread::_stack_shadow_zone_size = 0; 2499 2500 void JavaThread::create_stack_guard_pages() { 2501 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2502 address low_addr = stack_end(); 2503 size_t len = stack_guard_zone_size(); 2504 2505 int must_commit = os::must_commit_stack_guard_pages(); 2506 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2507 2508 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2509 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2510 return; 2511 } 2512 2513 if (os::guard_memory((char *) low_addr, len)) { 2514 _stack_guard_state = stack_guard_enabled; 2515 } else { 2516 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2517 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2518 if (os::uncommit_memory((char *) low_addr, len)) { 2519 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2520 } 2521 return; 2522 } 2523 2524 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2525 PTR_FORMAT "-" PTR_FORMAT ".", 2526 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2527 } 2528 2529 void JavaThread::remove_stack_guard_pages() { 2530 assert(Thread::current() == this, "from different thread"); 2531 if (_stack_guard_state == stack_guard_unused) return; 2532 address low_addr = stack_end(); 2533 size_t len = stack_guard_zone_size(); 2534 2535 if (os::must_commit_stack_guard_pages()) { 2536 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2537 _stack_guard_state = stack_guard_unused; 2538 } else { 2539 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2540 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2541 return; 2542 } 2543 } else { 2544 if (_stack_guard_state == stack_guard_unused) return; 2545 if (os::unguard_memory((char *) low_addr, len)) { 2546 _stack_guard_state = stack_guard_unused; 2547 } else { 2548 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2549 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2550 return; 2551 } 2552 } 2553 2554 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2555 PTR_FORMAT "-" PTR_FORMAT ".", 2556 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2557 } 2558 2559 void JavaThread::enable_stack_reserved_zone() { 2560 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2561 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2562 2563 // The base notation is from the stack's point of view, growing downward. 2564 // We need to adjust it to work correctly with guard_memory() 2565 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2566 2567 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2568 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2569 2570 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2571 _stack_guard_state = stack_guard_enabled; 2572 } else { 2573 warning("Attempt to guard stack reserved zone failed."); 2574 } 2575 enable_register_stack_guard(); 2576 } 2577 2578 void JavaThread::disable_stack_reserved_zone() { 2579 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2580 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2581 2582 // Simply return if called for a thread that does not use guard pages. 2583 if (_stack_guard_state == stack_guard_unused) return; 2584 2585 // The base notation is from the stack's point of view, growing downward. 2586 // We need to adjust it to work correctly with guard_memory() 2587 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2588 2589 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2590 _stack_guard_state = stack_guard_reserved_disabled; 2591 } else { 2592 warning("Attempt to unguard stack reserved zone failed."); 2593 } 2594 disable_register_stack_guard(); 2595 } 2596 2597 void JavaThread::enable_stack_yellow_reserved_zone() { 2598 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2599 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2600 2601 // The base notation is from the stacks point of view, growing downward. 2602 // We need to adjust it to work correctly with guard_memory() 2603 address base = stack_red_zone_base(); 2604 2605 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2606 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2607 2608 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2609 _stack_guard_state = stack_guard_enabled; 2610 } else { 2611 warning("Attempt to guard stack yellow zone failed."); 2612 } 2613 enable_register_stack_guard(); 2614 } 2615 2616 void JavaThread::disable_stack_yellow_reserved_zone() { 2617 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2618 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2619 2620 // Simply return if called for a thread that does not use guard pages. 2621 if (_stack_guard_state == stack_guard_unused) return; 2622 2623 // The base notation is from the stacks point of view, growing downward. 2624 // We need to adjust it to work correctly with guard_memory() 2625 address base = stack_red_zone_base(); 2626 2627 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2628 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2629 } else { 2630 warning("Attempt to unguard stack yellow zone failed."); 2631 } 2632 disable_register_stack_guard(); 2633 } 2634 2635 void JavaThread::enable_stack_red_zone() { 2636 // The base notation is from the stacks point of view, growing downward. 2637 // We need to adjust it to work correctly with guard_memory() 2638 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2639 address base = stack_red_zone_base() - stack_red_zone_size(); 2640 2641 guarantee(base < stack_base(), "Error calculating stack red zone"); 2642 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2643 2644 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2645 warning("Attempt to guard stack red zone failed."); 2646 } 2647 } 2648 2649 void JavaThread::disable_stack_red_zone() { 2650 // The base notation is from the stacks point of view, growing downward. 2651 // We need to adjust it to work correctly with guard_memory() 2652 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2653 address base = stack_red_zone_base() - stack_red_zone_size(); 2654 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2655 warning("Attempt to unguard stack red zone failed."); 2656 } 2657 } 2658 2659 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2660 // ignore is there is no stack 2661 if (!has_last_Java_frame()) return; 2662 // traverse the stack frames. Starts from top frame. 2663 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2664 frame* fr = fst.current(); 2665 f(fr, fst.register_map()); 2666 } 2667 } 2668 2669 2670 #ifndef PRODUCT 2671 // Deoptimization 2672 // Function for testing deoptimization 2673 void JavaThread::deoptimize() { 2674 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2675 StackFrameStream fst(this, UseBiasedLocking); 2676 bool deopt = false; // Dump stack only if a deopt actually happens. 2677 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2678 // Iterate over all frames in the thread and deoptimize 2679 for (; !fst.is_done(); fst.next()) { 2680 if (fst.current()->can_be_deoptimized()) { 2681 2682 if (only_at) { 2683 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2684 // consists of comma or carriage return separated numbers so 2685 // search for the current bci in that string. 2686 address pc = fst.current()->pc(); 2687 nmethod* nm = (nmethod*) fst.current()->cb(); 2688 ScopeDesc* sd = nm->scope_desc_at(pc); 2689 char buffer[8]; 2690 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2691 size_t len = strlen(buffer); 2692 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2693 while (found != NULL) { 2694 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2695 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2696 // Check that the bci found is bracketed by terminators. 2697 break; 2698 } 2699 found = strstr(found + 1, buffer); 2700 } 2701 if (!found) { 2702 continue; 2703 } 2704 } 2705 2706 if (DebugDeoptimization && !deopt) { 2707 deopt = true; // One-time only print before deopt 2708 tty->print_cr("[BEFORE Deoptimization]"); 2709 trace_frames(); 2710 trace_stack(); 2711 } 2712 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2713 } 2714 } 2715 2716 if (DebugDeoptimization && deopt) { 2717 tty->print_cr("[AFTER Deoptimization]"); 2718 trace_frames(); 2719 } 2720 } 2721 2722 2723 // Make zombies 2724 void JavaThread::make_zombies() { 2725 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2726 if (fst.current()->can_be_deoptimized()) { 2727 // it is a Java nmethod 2728 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2729 nm->make_not_entrant(); 2730 } 2731 } 2732 } 2733 #endif // PRODUCT 2734 2735 2736 void JavaThread::deoptimized_wrt_marked_nmethods() { 2737 if (!has_last_Java_frame()) return; 2738 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2739 StackFrameStream fst(this, UseBiasedLocking); 2740 for (; !fst.is_done(); fst.next()) { 2741 if (fst.current()->should_be_deoptimized()) { 2742 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2743 } 2744 } 2745 } 2746 2747 2748 // If the caller is a NamedThread, then remember, in the current scope, 2749 // the given JavaThread in its _processed_thread field. 2750 class RememberProcessedThread: public StackObj { 2751 NamedThread* _cur_thr; 2752 public: 2753 RememberProcessedThread(JavaThread* jthr) { 2754 Thread* thread = Thread::current(); 2755 if (thread->is_Named_thread()) { 2756 _cur_thr = (NamedThread *)thread; 2757 _cur_thr->set_processed_thread(jthr); 2758 } else { 2759 _cur_thr = NULL; 2760 } 2761 } 2762 2763 ~RememberProcessedThread() { 2764 if (_cur_thr) { 2765 _cur_thr->set_processed_thread(NULL); 2766 } 2767 } 2768 }; 2769 2770 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2771 // Verify that the deferred card marks have been flushed. 2772 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2773 2774 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2775 // since there may be more than one thread using each ThreadProfiler. 2776 2777 // Traverse the GCHandles 2778 Thread::oops_do(f, cf); 2779 2780 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2781 2782 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2783 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2784 2785 if (has_last_Java_frame()) { 2786 // Record JavaThread to GC thread 2787 RememberProcessedThread rpt(this); 2788 2789 // Traverse the privileged stack 2790 if (_privileged_stack_top != NULL) { 2791 _privileged_stack_top->oops_do(f); 2792 } 2793 2794 // traverse the registered growable array 2795 if (_array_for_gc != NULL) { 2796 for (int index = 0; index < _array_for_gc->length(); index++) { 2797 f->do_oop(_array_for_gc->adr_at(index)); 2798 } 2799 } 2800 2801 // Traverse the monitor chunks 2802 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2803 chunk->oops_do(f); 2804 } 2805 2806 // Traverse the execution stack 2807 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2808 fst.current()->oops_do(f, cf, fst.register_map()); 2809 } 2810 } 2811 2812 // callee_target is never live across a gc point so NULL it here should 2813 // it still contain a methdOop. 2814 2815 set_callee_target(NULL); 2816 2817 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2818 // If we have deferred set_locals there might be oops waiting to be 2819 // written 2820 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2821 if (list != NULL) { 2822 for (int i = 0; i < list->length(); i++) { 2823 list->at(i)->oops_do(f); 2824 } 2825 } 2826 2827 // Traverse instance variables at the end since the GC may be moving things 2828 // around using this function 2829 f->do_oop((oop*) &_threadObj); 2830 f->do_oop((oop*) &_vm_result); 2831 f->do_oop((oop*) &_exception_oop); 2832 f->do_oop((oop*) &_pending_async_exception); 2833 2834 if (jvmti_thread_state() != NULL) { 2835 jvmti_thread_state()->oops_do(f); 2836 } 2837 } 2838 2839 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2840 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2841 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2842 2843 if (has_last_Java_frame()) { 2844 // Traverse the execution stack 2845 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2846 fst.current()->nmethods_do(cf); 2847 } 2848 } 2849 } 2850 2851 void JavaThread::metadata_do(void f(Metadata*)) { 2852 if (has_last_Java_frame()) { 2853 // Traverse the execution stack to call f() on the methods in the stack 2854 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2855 fst.current()->metadata_do(f); 2856 } 2857 } else if (is_Compiler_thread()) { 2858 // need to walk ciMetadata in current compile tasks to keep alive. 2859 CompilerThread* ct = (CompilerThread*)this; 2860 if (ct->env() != NULL) { 2861 ct->env()->metadata_do(f); 2862 } 2863 if (ct->task() != NULL) { 2864 ct->task()->metadata_do(f); 2865 } 2866 } 2867 } 2868 2869 // Printing 2870 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2871 switch (_thread_state) { 2872 case _thread_uninitialized: return "_thread_uninitialized"; 2873 case _thread_new: return "_thread_new"; 2874 case _thread_new_trans: return "_thread_new_trans"; 2875 case _thread_in_native: return "_thread_in_native"; 2876 case _thread_in_native_trans: return "_thread_in_native_trans"; 2877 case _thread_in_vm: return "_thread_in_vm"; 2878 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2879 case _thread_in_Java: return "_thread_in_Java"; 2880 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2881 case _thread_blocked: return "_thread_blocked"; 2882 case _thread_blocked_trans: return "_thread_blocked_trans"; 2883 default: return "unknown thread state"; 2884 } 2885 } 2886 2887 #ifndef PRODUCT 2888 void JavaThread::print_thread_state_on(outputStream *st) const { 2889 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2890 }; 2891 void JavaThread::print_thread_state() const { 2892 print_thread_state_on(tty); 2893 } 2894 #endif // PRODUCT 2895 2896 // Called by Threads::print() for VM_PrintThreads operation 2897 void JavaThread::print_on(outputStream *st) const { 2898 st->print_raw("\""); 2899 st->print_raw(get_thread_name()); 2900 st->print_raw("\" "); 2901 oop thread_oop = threadObj(); 2902 if (thread_oop != NULL) { 2903 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2904 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2905 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2906 } 2907 Thread::print_on(st); 2908 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2909 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2910 if (thread_oop != NULL) { 2911 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2912 } 2913 #ifndef PRODUCT 2914 print_thread_state_on(st); 2915 _safepoint_state->print_on(st); 2916 #endif // PRODUCT 2917 if (is_Compiler_thread()) { 2918 CompilerThread* ct = (CompilerThread*)this; 2919 if (ct->task() != NULL) { 2920 st->print(" Compiling: "); 2921 ct->task()->print(st, NULL, true, false); 2922 } else { 2923 st->print(" No compile task"); 2924 } 2925 st->cr(); 2926 } 2927 } 2928 2929 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2930 st->print("%s", get_thread_name_string(buf, buflen)); 2931 } 2932 2933 // Called by fatal error handler. The difference between this and 2934 // JavaThread::print() is that we can't grab lock or allocate memory. 2935 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2936 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2937 oop thread_obj = threadObj(); 2938 if (thread_obj != NULL) { 2939 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2940 } 2941 st->print(" ["); 2942 st->print("%s", _get_thread_state_name(_thread_state)); 2943 if (osthread()) { 2944 st->print(", id=%d", osthread()->thread_id()); 2945 } 2946 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2947 p2i(stack_end()), p2i(stack_base())); 2948 st->print("]"); 2949 return; 2950 } 2951 2952 // Verification 2953 2954 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2955 2956 void JavaThread::verify() { 2957 // Verify oops in the thread. 2958 oops_do(&VerifyOopClosure::verify_oop, NULL); 2959 2960 // Verify the stack frames. 2961 frames_do(frame_verify); 2962 } 2963 2964 // CR 6300358 (sub-CR 2137150) 2965 // Most callers of this method assume that it can't return NULL but a 2966 // thread may not have a name whilst it is in the process of attaching to 2967 // the VM - see CR 6412693, and there are places where a JavaThread can be 2968 // seen prior to having it's threadObj set (eg JNI attaching threads and 2969 // if vm exit occurs during initialization). These cases can all be accounted 2970 // for such that this method never returns NULL. 2971 const char* JavaThread::get_thread_name() const { 2972 #ifdef ASSERT 2973 // early safepoints can hit while current thread does not yet have TLS 2974 if (!SafepointSynchronize::is_at_safepoint()) { 2975 Thread *cur = Thread::current(); 2976 if (!(cur->is_Java_thread() && cur == this)) { 2977 // Current JavaThreads are allowed to get their own name without 2978 // the Threads_lock. 2979 assert_locked_or_safepoint(Threads_lock); 2980 } 2981 } 2982 #endif // ASSERT 2983 return get_thread_name_string(); 2984 } 2985 2986 // Returns a non-NULL representation of this thread's name, or a suitable 2987 // descriptive string if there is no set name 2988 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2989 const char* name_str; 2990 oop thread_obj = threadObj(); 2991 if (thread_obj != NULL) { 2992 oop name = java_lang_Thread::name(thread_obj); 2993 if (name != NULL) { 2994 if (buf == NULL) { 2995 name_str = java_lang_String::as_utf8_string(name); 2996 } else { 2997 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2998 } 2999 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3000 name_str = "<no-name - thread is attaching>"; 3001 } else { 3002 name_str = Thread::name(); 3003 } 3004 } else { 3005 name_str = Thread::name(); 3006 } 3007 assert(name_str != NULL, "unexpected NULL thread name"); 3008 return name_str; 3009 } 3010 3011 3012 const char* JavaThread::get_threadgroup_name() const { 3013 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3014 oop thread_obj = threadObj(); 3015 if (thread_obj != NULL) { 3016 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3017 if (thread_group != NULL) { 3018 // ThreadGroup.name can be null 3019 return java_lang_ThreadGroup::name(thread_group); 3020 } 3021 } 3022 return NULL; 3023 } 3024 3025 const char* JavaThread::get_parent_name() const { 3026 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3027 oop thread_obj = threadObj(); 3028 if (thread_obj != NULL) { 3029 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3030 if (thread_group != NULL) { 3031 oop parent = java_lang_ThreadGroup::parent(thread_group); 3032 if (parent != NULL) { 3033 // ThreadGroup.name can be null 3034 return java_lang_ThreadGroup::name(parent); 3035 } 3036 } 3037 } 3038 return NULL; 3039 } 3040 3041 ThreadPriority JavaThread::java_priority() const { 3042 oop thr_oop = threadObj(); 3043 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3044 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3045 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3046 return priority; 3047 } 3048 3049 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3050 3051 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3052 // Link Java Thread object <-> C++ Thread 3053 3054 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3055 // and put it into a new Handle. The Handle "thread_oop" can then 3056 // be used to pass the C++ thread object to other methods. 3057 3058 // Set the Java level thread object (jthread) field of the 3059 // new thread (a JavaThread *) to C++ thread object using the 3060 // "thread_oop" handle. 3061 3062 // Set the thread field (a JavaThread *) of the 3063 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3064 3065 Handle thread_oop(Thread::current(), 3066 JNIHandles::resolve_non_null(jni_thread)); 3067 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3068 "must be initialized"); 3069 set_threadObj(thread_oop()); 3070 java_lang_Thread::set_thread(thread_oop(), this); 3071 3072 if (prio == NoPriority) { 3073 prio = java_lang_Thread::priority(thread_oop()); 3074 assert(prio != NoPriority, "A valid priority should be present"); 3075 } 3076 3077 // Push the Java priority down to the native thread; needs Threads_lock 3078 Thread::set_priority(this, prio); 3079 3080 prepare_ext(); 3081 3082 // Add the new thread to the Threads list and set it in motion. 3083 // We must have threads lock in order to call Threads::add. 3084 // It is crucial that we do not block before the thread is 3085 // added to the Threads list for if a GC happens, then the java_thread oop 3086 // will not be visited by GC. 3087 Threads::add(this); 3088 } 3089 3090 oop JavaThread::current_park_blocker() { 3091 // Support for JSR-166 locks 3092 oop thread_oop = threadObj(); 3093 if (thread_oop != NULL && 3094 JDK_Version::current().supports_thread_park_blocker()) { 3095 return java_lang_Thread::park_blocker(thread_oop); 3096 } 3097 return NULL; 3098 } 3099 3100 3101 void JavaThread::print_stack_on(outputStream* st) { 3102 if (!has_last_Java_frame()) return; 3103 ResourceMark rm; 3104 HandleMark hm; 3105 3106 RegisterMap reg_map(this); 3107 vframe* start_vf = last_java_vframe(®_map); 3108 int count = 0; 3109 for (vframe* f = start_vf; f; f = f->sender()) { 3110 if (f->is_java_frame()) { 3111 javaVFrame* jvf = javaVFrame::cast(f); 3112 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3113 3114 // Print out lock information 3115 if (JavaMonitorsInStackTrace) { 3116 jvf->print_lock_info_on(st, count); 3117 } 3118 } else { 3119 // Ignore non-Java frames 3120 } 3121 3122 // Bail-out case for too deep stacks 3123 count++; 3124 if (MaxJavaStackTraceDepth == count) return; 3125 } 3126 } 3127 3128 3129 // JVMTI PopFrame support 3130 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3131 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3132 if (in_bytes(size_in_bytes) != 0) { 3133 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3134 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3135 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3136 } 3137 } 3138 3139 void* JavaThread::popframe_preserved_args() { 3140 return _popframe_preserved_args; 3141 } 3142 3143 ByteSize JavaThread::popframe_preserved_args_size() { 3144 return in_ByteSize(_popframe_preserved_args_size); 3145 } 3146 3147 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3148 int sz = in_bytes(popframe_preserved_args_size()); 3149 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3150 return in_WordSize(sz / wordSize); 3151 } 3152 3153 void JavaThread::popframe_free_preserved_args() { 3154 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3155 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3156 _popframe_preserved_args = NULL; 3157 _popframe_preserved_args_size = 0; 3158 } 3159 3160 #ifndef PRODUCT 3161 3162 void JavaThread::trace_frames() { 3163 tty->print_cr("[Describe stack]"); 3164 int frame_no = 1; 3165 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3166 tty->print(" %d. ", frame_no++); 3167 fst.current()->print_value_on(tty, this); 3168 tty->cr(); 3169 } 3170 } 3171 3172 class PrintAndVerifyOopClosure: public OopClosure { 3173 protected: 3174 template <class T> inline void do_oop_work(T* p) { 3175 oop obj = oopDesc::load_decode_heap_oop(p); 3176 if (obj == NULL) return; 3177 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3178 if (obj->is_oop_or_null()) { 3179 if (obj->is_objArray()) { 3180 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3181 } else { 3182 obj->print(); 3183 } 3184 } else { 3185 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3186 } 3187 tty->cr(); 3188 } 3189 public: 3190 virtual void do_oop(oop* p) { do_oop_work(p); } 3191 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3192 }; 3193 3194 3195 static void oops_print(frame* f, const RegisterMap *map) { 3196 PrintAndVerifyOopClosure print; 3197 f->print_value(); 3198 f->oops_do(&print, NULL, (RegisterMap*)map); 3199 } 3200 3201 // Print our all the locations that contain oops and whether they are 3202 // valid or not. This useful when trying to find the oldest frame 3203 // where an oop has gone bad since the frame walk is from youngest to 3204 // oldest. 3205 void JavaThread::trace_oops() { 3206 tty->print_cr("[Trace oops]"); 3207 frames_do(oops_print); 3208 } 3209 3210 3211 #ifdef ASSERT 3212 // Print or validate the layout of stack frames 3213 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3214 ResourceMark rm; 3215 PRESERVE_EXCEPTION_MARK; 3216 FrameValues values; 3217 int frame_no = 0; 3218 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3219 fst.current()->describe(values, ++frame_no); 3220 if (depth == frame_no) break; 3221 } 3222 if (validate_only) { 3223 values.validate(); 3224 } else { 3225 tty->print_cr("[Describe stack layout]"); 3226 values.print(this); 3227 } 3228 } 3229 #endif 3230 3231 void JavaThread::trace_stack_from(vframe* start_vf) { 3232 ResourceMark rm; 3233 int vframe_no = 1; 3234 for (vframe* f = start_vf; f; f = f->sender()) { 3235 if (f->is_java_frame()) { 3236 javaVFrame::cast(f)->print_activation(vframe_no++); 3237 } else { 3238 f->print(); 3239 } 3240 if (vframe_no > StackPrintLimit) { 3241 tty->print_cr("...<more frames>..."); 3242 return; 3243 } 3244 } 3245 } 3246 3247 3248 void JavaThread::trace_stack() { 3249 if (!has_last_Java_frame()) return; 3250 ResourceMark rm; 3251 HandleMark hm; 3252 RegisterMap reg_map(this); 3253 trace_stack_from(last_java_vframe(®_map)); 3254 } 3255 3256 3257 #endif // PRODUCT 3258 3259 3260 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3261 assert(reg_map != NULL, "a map must be given"); 3262 frame f = last_frame(); 3263 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3264 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3265 } 3266 return NULL; 3267 } 3268 3269 3270 Klass* JavaThread::security_get_caller_class(int depth) { 3271 vframeStream vfst(this); 3272 vfst.security_get_caller_frame(depth); 3273 if (!vfst.at_end()) { 3274 return vfst.method()->method_holder(); 3275 } 3276 return NULL; 3277 } 3278 3279 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3280 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3281 CompileBroker::compiler_thread_loop(); 3282 } 3283 3284 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3285 NMethodSweeper::sweeper_loop(); 3286 } 3287 3288 // Create a CompilerThread 3289 CompilerThread::CompilerThread(CompileQueue* queue, 3290 CompilerCounters* counters) 3291 : JavaThread(&compiler_thread_entry) { 3292 _env = NULL; 3293 _log = NULL; 3294 _task = NULL; 3295 _queue = queue; 3296 _counters = counters; 3297 _buffer_blob = NULL; 3298 _compiler = NULL; 3299 3300 #ifndef PRODUCT 3301 _ideal_graph_printer = NULL; 3302 #endif 3303 } 3304 3305 bool CompilerThread::can_call_java() const { 3306 return _compiler != NULL && _compiler->is_jvmci(); 3307 } 3308 3309 // Create sweeper thread 3310 CodeCacheSweeperThread::CodeCacheSweeperThread() 3311 : JavaThread(&sweeper_thread_entry) { 3312 _scanned_compiled_method = NULL; 3313 } 3314 3315 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3316 JavaThread::oops_do(f, cf); 3317 if (_scanned_compiled_method != NULL && cf != NULL) { 3318 // Safepoints can occur when the sweeper is scanning an nmethod so 3319 // process it here to make sure it isn't unloaded in the middle of 3320 // a scan. 3321 cf->do_code_blob(_scanned_compiled_method); 3322 } 3323 } 3324 3325 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3326 JavaThread::nmethods_do(cf); 3327 if (_scanned_compiled_method != NULL && cf != NULL) { 3328 // Safepoints can occur when the sweeper is scanning an nmethod so 3329 // process it here to make sure it isn't unloaded in the middle of 3330 // a scan. 3331 cf->do_code_blob(_scanned_compiled_method); 3332 } 3333 } 3334 3335 3336 // ======= Threads ======== 3337 3338 // The Threads class links together all active threads, and provides 3339 // operations over all threads. It is protected by its own Mutex 3340 // lock, which is also used in other contexts to protect thread 3341 // operations from having the thread being operated on from exiting 3342 // and going away unexpectedly (e.g., safepoint synchronization) 3343 3344 JavaThread* Threads::_thread_list = NULL; 3345 int Threads::_number_of_threads = 0; 3346 int Threads::_number_of_non_daemon_threads = 0; 3347 int Threads::_return_code = 0; 3348 int Threads::_thread_claim_parity = 0; 3349 size_t JavaThread::_stack_size_at_create = 0; 3350 #ifdef ASSERT 3351 bool Threads::_vm_complete = false; 3352 #endif 3353 3354 // All JavaThreads 3355 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3356 3357 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3358 void Threads::threads_do(ThreadClosure* tc) { 3359 assert_locked_or_safepoint(Threads_lock); 3360 // ALL_JAVA_THREADS iterates through all JavaThreads 3361 ALL_JAVA_THREADS(p) { 3362 tc->do_thread(p); 3363 } 3364 // Someday we could have a table or list of all non-JavaThreads. 3365 // For now, just manually iterate through them. 3366 tc->do_thread(VMThread::vm_thread()); 3367 Universe::heap()->gc_threads_do(tc); 3368 WatcherThread *wt = WatcherThread::watcher_thread(); 3369 // Strictly speaking, the following NULL check isn't sufficient to make sure 3370 // the data for WatcherThread is still valid upon being examined. However, 3371 // considering that WatchThread terminates when the VM is on the way to 3372 // exit at safepoint, the chance of the above is extremely small. The right 3373 // way to prevent termination of WatcherThread would be to acquire 3374 // Terminator_lock, but we can't do that without violating the lock rank 3375 // checking in some cases. 3376 if (wt != NULL) { 3377 tc->do_thread(wt); 3378 } 3379 3380 // If CompilerThreads ever become non-JavaThreads, add them here 3381 } 3382 3383 // The system initialization in the library has three phases. 3384 // 3385 // Phase 1: java.lang.System class initialization 3386 // java.lang.System is a primordial class loaded and initialized 3387 // by the VM early during startup. java.lang.System.<clinit> 3388 // only does registerNatives and keeps the rest of the class 3389 // initialization work later until thread initialization completes. 3390 // 3391 // System.initPhase1 initializes the system properties, the static 3392 // fields in, out, and err. Set up java signal handlers, OS-specific 3393 // system settings, and thread group of the main thread. 3394 static void call_initPhase1(TRAPS) { 3395 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3396 JavaValue result(T_VOID); 3397 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3398 vmSymbols::void_method_signature(), CHECK); 3399 } 3400 3401 // Phase 2. Module system initialization 3402 // This will initialize the module system. Only java.base classes 3403 // can be loaded until phase 2 completes. 3404 // 3405 // Call System.initPhase2 after the compiler initialization and jsr292 3406 // classes get initialized because module initialization runs a lot of java 3407 // code, that for performance reasons, should be compiled. Also, this will 3408 // enable the startup code to use lambda and other language features in this 3409 // phase and onward. 3410 // 3411 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3412 static void call_initPhase2(TRAPS) { 3413 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime)); 3414 3415 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3416 3417 JavaValue result(T_INT); 3418 JavaCallArguments args; 3419 args.push_int(DisplayVMOutputToStderr); 3420 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3421 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3422 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3423 if (result.get_jint() != JNI_OK) { 3424 vm_exit_during_initialization(); // no message or exception 3425 } 3426 3427 universe_post_module_init(); 3428 } 3429 3430 // Phase 3. final setup - set security manager, system class loader and TCCL 3431 // 3432 // This will instantiate and set the security manager, set the system class 3433 // loader as well as the thread context class loader. The security manager 3434 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3435 // other modules or the application's classpath. 3436 static void call_initPhase3(TRAPS) { 3437 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3438 JavaValue result(T_VOID); 3439 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3440 vmSymbols::void_method_signature(), CHECK); 3441 } 3442 3443 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3444 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3445 3446 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3447 create_vm_init_libraries(); 3448 } 3449 3450 initialize_class(vmSymbols::java_lang_String(), CHECK); 3451 3452 // Inject CompactStrings value after the static initializers for String ran. 3453 java_lang_String::set_compact_strings(CompactStrings); 3454 3455 // Initialize java_lang.System (needed before creating the thread) 3456 initialize_class(vmSymbols::java_lang_System(), CHECK); 3457 // The VM creates & returns objects of this class. Make sure it's initialized. 3458 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3459 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3460 Handle thread_group = create_initial_thread_group(CHECK); 3461 Universe::set_main_thread_group(thread_group()); 3462 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3463 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3464 main_thread->set_threadObj(thread_object); 3465 // Set thread status to running since main thread has 3466 // been started and running. 3467 java_lang_Thread::set_thread_status(thread_object, 3468 java_lang_Thread::RUNNABLE); 3469 3470 // The VM creates objects of this class. 3471 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3472 3473 // The VM preresolves methods to these classes. Make sure that they get initialized 3474 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3475 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3476 3477 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3478 call_initPhase1(CHECK); 3479 3480 // get the Java runtime name after java.lang.System is initialized 3481 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3482 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3483 3484 // an instance of OutOfMemory exception has been allocated earlier 3485 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3486 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3487 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3488 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3489 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3490 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3491 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3492 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3493 } 3494 3495 void Threads::initialize_jsr292_core_classes(TRAPS) { 3496 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3497 3498 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3499 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3500 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3501 } 3502 3503 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3504 extern void JDK_Version_init(); 3505 3506 // Preinitialize version info. 3507 VM_Version::early_initialize(); 3508 3509 // Check version 3510 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3511 3512 // Initialize library-based TLS 3513 ThreadLocalStorage::init(); 3514 3515 // Initialize the output stream module 3516 ostream_init(); 3517 3518 // Process java launcher properties. 3519 Arguments::process_sun_java_launcher_properties(args); 3520 3521 // Initialize the os module 3522 os::init(); 3523 3524 // Record VM creation timing statistics 3525 TraceVmCreationTime create_vm_timer; 3526 create_vm_timer.start(); 3527 3528 // Initialize system properties. 3529 Arguments::init_system_properties(); 3530 3531 // So that JDK version can be used as a discriminator when parsing arguments 3532 JDK_Version_init(); 3533 3534 // Update/Initialize System properties after JDK version number is known 3535 Arguments::init_version_specific_system_properties(); 3536 3537 // Make sure to initialize log configuration *before* parsing arguments 3538 LogConfiguration::initialize(create_vm_timer.begin_time()); 3539 3540 // Parse arguments 3541 jint parse_result = Arguments::parse(args); 3542 if (parse_result != JNI_OK) return parse_result; 3543 3544 os::init_before_ergo(); 3545 3546 jint ergo_result = Arguments::apply_ergo(); 3547 if (ergo_result != JNI_OK) return ergo_result; 3548 3549 // Final check of all ranges after ergonomics which may change values. 3550 if (!CommandLineFlagRangeList::check_ranges()) { 3551 return JNI_EINVAL; 3552 } 3553 3554 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3555 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3556 if (!constraint_result) { 3557 return JNI_EINVAL; 3558 } 3559 3560 CommandLineFlagWriteableList::mark_startup(); 3561 3562 if (PauseAtStartup) { 3563 os::pause(); 3564 } 3565 3566 HOTSPOT_VM_INIT_BEGIN(); 3567 3568 // Timing (must come after argument parsing) 3569 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3570 3571 // Initialize the os module after parsing the args 3572 jint os_init_2_result = os::init_2(); 3573 if (os_init_2_result != JNI_OK) return os_init_2_result; 3574 3575 jint adjust_after_os_result = Arguments::adjust_after_os(); 3576 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3577 3578 // Initialize output stream logging 3579 ostream_init_log(); 3580 3581 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3582 // Must be before create_vm_init_agents() 3583 if (Arguments::init_libraries_at_startup()) { 3584 convert_vm_init_libraries_to_agents(); 3585 } 3586 3587 // Launch -agentlib/-agentpath and converted -Xrun agents 3588 if (Arguments::init_agents_at_startup()) { 3589 create_vm_init_agents(); 3590 } 3591 3592 // Initialize Threads state 3593 _thread_list = NULL; 3594 _number_of_threads = 0; 3595 _number_of_non_daemon_threads = 0; 3596 3597 // Initialize global data structures and create system classes in heap 3598 vm_init_globals(); 3599 3600 #if INCLUDE_JVMCI 3601 if (JVMCICounterSize > 0) { 3602 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3603 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3604 } else { 3605 JavaThread::_jvmci_old_thread_counters = NULL; 3606 } 3607 #endif // INCLUDE_JVMCI 3608 3609 // Attach the main thread to this os thread 3610 JavaThread* main_thread = new JavaThread(); 3611 main_thread->set_thread_state(_thread_in_vm); 3612 main_thread->initialize_thread_current(); 3613 // must do this before set_active_handles 3614 main_thread->record_stack_base_and_size(); 3615 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3616 3617 if (!main_thread->set_as_starting_thread()) { 3618 vm_shutdown_during_initialization( 3619 "Failed necessary internal allocation. Out of swap space"); 3620 delete main_thread; 3621 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3622 return JNI_ENOMEM; 3623 } 3624 3625 // Enable guard page *after* os::create_main_thread(), otherwise it would 3626 // crash Linux VM, see notes in os_linux.cpp. 3627 main_thread->create_stack_guard_pages(); 3628 3629 // Initialize Java-Level synchronization subsystem 3630 ObjectMonitor::Initialize(); 3631 3632 // Initialize global modules 3633 jint status = init_globals(); 3634 if (status != JNI_OK) { 3635 delete main_thread; 3636 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3637 return status; 3638 } 3639 3640 if (TRACE_INITIALIZE() != JNI_OK) { 3641 vm_exit_during_initialization("Failed to initialize tracing backend"); 3642 } 3643 3644 // Should be done after the heap is fully created 3645 main_thread->cache_global_variables(); 3646 3647 HandleMark hm; 3648 3649 { MutexLocker mu(Threads_lock); 3650 Threads::add(main_thread); 3651 } 3652 3653 // Any JVMTI raw monitors entered in onload will transition into 3654 // real raw monitor. VM is setup enough here for raw monitor enter. 3655 JvmtiExport::transition_pending_onload_raw_monitors(); 3656 3657 // Create the VMThread 3658 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3659 3660 VMThread::create(); 3661 Thread* vmthread = VMThread::vm_thread(); 3662 3663 if (!os::create_thread(vmthread, os::vm_thread)) { 3664 vm_exit_during_initialization("Cannot create VM thread. " 3665 "Out of system resources."); 3666 } 3667 3668 // Wait for the VM thread to become ready, and VMThread::run to initialize 3669 // Monitors can have spurious returns, must always check another state flag 3670 { 3671 MutexLocker ml(Notify_lock); 3672 os::start_thread(vmthread); 3673 while (vmthread->active_handles() == NULL) { 3674 Notify_lock->wait(); 3675 } 3676 } 3677 } 3678 3679 assert(Universe::is_fully_initialized(), "not initialized"); 3680 if (VerifyDuringStartup) { 3681 // Make sure we're starting with a clean slate. 3682 VM_Verify verify_op; 3683 VMThread::execute(&verify_op); 3684 } 3685 3686 Thread* THREAD = Thread::current(); 3687 3688 // At this point, the Universe is initialized, but we have not executed 3689 // any byte code. Now is a good time (the only time) to dump out the 3690 // internal state of the JVM for sharing. 3691 if (DumpSharedSpaces) { 3692 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3693 ShouldNotReachHere(); 3694 } 3695 3696 // Always call even when there are not JVMTI environments yet, since environments 3697 // may be attached late and JVMTI must track phases of VM execution 3698 JvmtiExport::enter_early_start_phase(); 3699 3700 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3701 JvmtiExport::post_early_vm_start(); 3702 3703 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3704 3705 // We need this for ClassDataSharing - the initial vm.info property is set 3706 // with the default value of CDS "sharing" which may be reset through 3707 // command line options. 3708 reset_vm_info_property(CHECK_JNI_ERR); 3709 3710 quicken_jni_functions(); 3711 3712 // No more stub generation allowed after that point. 3713 StubCodeDesc::freeze(); 3714 3715 // Set flag that basic initialization has completed. Used by exceptions and various 3716 // debug stuff, that does not work until all basic classes have been initialized. 3717 set_init_completed(); 3718 3719 LogConfiguration::post_initialize(); 3720 Metaspace::post_initialize(); 3721 3722 HOTSPOT_VM_INIT_END(); 3723 3724 // record VM initialization completion time 3725 #if INCLUDE_MANAGEMENT 3726 Management::record_vm_init_completed(); 3727 #endif // INCLUDE_MANAGEMENT 3728 3729 // Signal Dispatcher needs to be started before VMInit event is posted 3730 os::signal_init(CHECK_JNI_ERR); 3731 3732 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3733 if (!DisableAttachMechanism) { 3734 AttachListener::vm_start(); 3735 if (StartAttachListener || AttachListener::init_at_startup()) { 3736 AttachListener::init(); 3737 } 3738 } 3739 3740 // Launch -Xrun agents 3741 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3742 // back-end can launch with -Xdebug -Xrunjdwp. 3743 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3744 create_vm_init_libraries(); 3745 } 3746 3747 if (CleanChunkPoolAsync) { 3748 Chunk::start_chunk_pool_cleaner_task(); 3749 } 3750 3751 // initialize compiler(s) 3752 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3753 CompileBroker::compilation_init(CHECK_JNI_ERR); 3754 #endif 3755 3756 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3757 // It is done after compilers are initialized, because otherwise compilations of 3758 // signature polymorphic MH intrinsics can be missed 3759 // (see SystemDictionary::find_method_handle_intrinsic). 3760 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3761 3762 // This will initialize the module system. Only java.base classes can be 3763 // loaded until phase 2 completes 3764 call_initPhase2(CHECK_JNI_ERR); 3765 3766 // Always call even when there are not JVMTI environments yet, since environments 3767 // may be attached late and JVMTI must track phases of VM execution 3768 JvmtiExport::enter_start_phase(); 3769 3770 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3771 JvmtiExport::post_vm_start(); 3772 3773 // Final system initialization including security manager and system class loader 3774 call_initPhase3(CHECK_JNI_ERR); 3775 3776 // cache the system class loader 3777 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3778 3779 #if INCLUDE_JVMCI 3780 if (EnableJVMCI) { 3781 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3782 // The JVMCI Java initialization code will read this flag and 3783 // do the printing if it's set. 3784 bool init = JVMCIPrintProperties; 3785 3786 if (!init) { 3787 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3788 // compilations via JVMCI will not actually block until JVMCI is initialized. 3789 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3790 } 3791 3792 if (init) { 3793 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3794 } 3795 } 3796 #endif 3797 3798 // Always call even when there are not JVMTI environments yet, since environments 3799 // may be attached late and JVMTI must track phases of VM execution 3800 JvmtiExport::enter_live_phase(); 3801 3802 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3803 JvmtiExport::post_vm_initialized(); 3804 3805 if (TRACE_START() != JNI_OK) { 3806 vm_exit_during_initialization("Failed to start tracing backend."); 3807 } 3808 3809 #if INCLUDE_MANAGEMENT 3810 Management::initialize(THREAD); 3811 3812 if (HAS_PENDING_EXCEPTION) { 3813 // management agent fails to start possibly due to 3814 // configuration problem and is responsible for printing 3815 // stack trace if appropriate. Simply exit VM. 3816 vm_exit(1); 3817 } 3818 #endif // INCLUDE_MANAGEMENT 3819 3820 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3821 if (MemProfiling) MemProfiler::engage(); 3822 StatSampler::engage(); 3823 if (CheckJNICalls) JniPeriodicChecker::engage(); 3824 3825 BiasedLocking::init(); 3826 3827 #if INCLUDE_RTM_OPT 3828 RTMLockingCounters::init(); 3829 #endif 3830 3831 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3832 call_postVMInitHook(THREAD); 3833 // The Java side of PostVMInitHook.run must deal with all 3834 // exceptions and provide means of diagnosis. 3835 if (HAS_PENDING_EXCEPTION) { 3836 CLEAR_PENDING_EXCEPTION; 3837 } 3838 } 3839 3840 { 3841 MutexLocker ml(PeriodicTask_lock); 3842 // Make sure the WatcherThread can be started by WatcherThread::start() 3843 // or by dynamic enrollment. 3844 WatcherThread::make_startable(); 3845 // Start up the WatcherThread if there are any periodic tasks 3846 // NOTE: All PeriodicTasks should be registered by now. If they 3847 // aren't, late joiners might appear to start slowly (we might 3848 // take a while to process their first tick). 3849 if (PeriodicTask::num_tasks() > 0) { 3850 WatcherThread::start(); 3851 } 3852 } 3853 3854 create_vm_timer.end(); 3855 #ifdef ASSERT 3856 _vm_complete = true; 3857 #endif 3858 return JNI_OK; 3859 } 3860 3861 // type for the Agent_OnLoad and JVM_OnLoad entry points 3862 extern "C" { 3863 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3864 } 3865 // Find a command line agent library and return its entry point for 3866 // -agentlib: -agentpath: -Xrun 3867 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3868 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3869 const char *on_load_symbols[], 3870 size_t num_symbol_entries) { 3871 OnLoadEntry_t on_load_entry = NULL; 3872 void *library = NULL; 3873 3874 if (!agent->valid()) { 3875 char buffer[JVM_MAXPATHLEN]; 3876 char ebuf[1024] = ""; 3877 const char *name = agent->name(); 3878 const char *msg = "Could not find agent library "; 3879 3880 // First check to see if agent is statically linked into executable 3881 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3882 library = agent->os_lib(); 3883 } else if (agent->is_absolute_path()) { 3884 library = os::dll_load(name, ebuf, sizeof ebuf); 3885 if (library == NULL) { 3886 const char *sub_msg = " in absolute path, with error: "; 3887 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3888 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3889 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3890 // If we can't find the agent, exit. 3891 vm_exit_during_initialization(buf, NULL); 3892 FREE_C_HEAP_ARRAY(char, buf); 3893 } 3894 } else { 3895 // Try to load the agent from the standard dll directory 3896 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3897 name)) { 3898 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3899 } 3900 if (library == NULL) { // Try the local directory 3901 char ns[1] = {0}; 3902 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3903 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3904 } 3905 if (library == NULL) { 3906 const char *sub_msg = " on the library path, with error: "; 3907 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3908 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3909 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3910 // If we can't find the agent, exit. 3911 vm_exit_during_initialization(buf, NULL); 3912 FREE_C_HEAP_ARRAY(char, buf); 3913 } 3914 } 3915 } 3916 agent->set_os_lib(library); 3917 agent->set_valid(); 3918 } 3919 3920 // Find the OnLoad function. 3921 on_load_entry = 3922 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3923 false, 3924 on_load_symbols, 3925 num_symbol_entries)); 3926 return on_load_entry; 3927 } 3928 3929 // Find the JVM_OnLoad entry point 3930 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3931 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3932 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3933 } 3934 3935 // Find the Agent_OnLoad entry point 3936 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3937 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3938 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3939 } 3940 3941 // For backwards compatibility with -Xrun 3942 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3943 // treated like -agentpath: 3944 // Must be called before agent libraries are created 3945 void Threads::convert_vm_init_libraries_to_agents() { 3946 AgentLibrary* agent; 3947 AgentLibrary* next; 3948 3949 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3950 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3951 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3952 3953 // If there is an JVM_OnLoad function it will get called later, 3954 // otherwise see if there is an Agent_OnLoad 3955 if (on_load_entry == NULL) { 3956 on_load_entry = lookup_agent_on_load(agent); 3957 if (on_load_entry != NULL) { 3958 // switch it to the agent list -- so that Agent_OnLoad will be called, 3959 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3960 Arguments::convert_library_to_agent(agent); 3961 } else { 3962 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3963 } 3964 } 3965 } 3966 } 3967 3968 // Create agents for -agentlib: -agentpath: and converted -Xrun 3969 // Invokes Agent_OnLoad 3970 // Called very early -- before JavaThreads exist 3971 void Threads::create_vm_init_agents() { 3972 extern struct JavaVM_ main_vm; 3973 AgentLibrary* agent; 3974 3975 JvmtiExport::enter_onload_phase(); 3976 3977 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3978 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3979 3980 if (on_load_entry != NULL) { 3981 // Invoke the Agent_OnLoad function 3982 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3983 if (err != JNI_OK) { 3984 vm_exit_during_initialization("agent library failed to init", agent->name()); 3985 } 3986 } else { 3987 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3988 } 3989 } 3990 JvmtiExport::enter_primordial_phase(); 3991 } 3992 3993 extern "C" { 3994 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3995 } 3996 3997 void Threads::shutdown_vm_agents() { 3998 // Send any Agent_OnUnload notifications 3999 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4000 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4001 extern struct JavaVM_ main_vm; 4002 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4003 4004 // Find the Agent_OnUnload function. 4005 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4006 os::find_agent_function(agent, 4007 false, 4008 on_unload_symbols, 4009 num_symbol_entries)); 4010 4011 // Invoke the Agent_OnUnload function 4012 if (unload_entry != NULL) { 4013 JavaThread* thread = JavaThread::current(); 4014 ThreadToNativeFromVM ttn(thread); 4015 HandleMark hm(thread); 4016 (*unload_entry)(&main_vm); 4017 } 4018 } 4019 } 4020 4021 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4022 // Invokes JVM_OnLoad 4023 void Threads::create_vm_init_libraries() { 4024 extern struct JavaVM_ main_vm; 4025 AgentLibrary* agent; 4026 4027 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4028 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4029 4030 if (on_load_entry != NULL) { 4031 // Invoke the JVM_OnLoad function 4032 JavaThread* thread = JavaThread::current(); 4033 ThreadToNativeFromVM ttn(thread); 4034 HandleMark hm(thread); 4035 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4036 if (err != JNI_OK) { 4037 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4038 } 4039 } else { 4040 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4041 } 4042 } 4043 } 4044 4045 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4046 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4047 4048 JavaThread* java_thread = NULL; 4049 // Sequential search for now. Need to do better optimization later. 4050 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4051 oop tobj = thread->threadObj(); 4052 if (!thread->is_exiting() && 4053 tobj != NULL && 4054 java_tid == java_lang_Thread::thread_id(tobj)) { 4055 java_thread = thread; 4056 break; 4057 } 4058 } 4059 return java_thread; 4060 } 4061 4062 4063 // Last thread running calls java.lang.Shutdown.shutdown() 4064 void JavaThread::invoke_shutdown_hooks() { 4065 HandleMark hm(this); 4066 4067 // We could get here with a pending exception, if so clear it now. 4068 if (this->has_pending_exception()) { 4069 this->clear_pending_exception(); 4070 } 4071 4072 EXCEPTION_MARK; 4073 Klass* shutdown_klass = 4074 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4075 THREAD); 4076 if (shutdown_klass != NULL) { 4077 // SystemDictionary::resolve_or_null will return null if there was 4078 // an exception. If we cannot load the Shutdown class, just don't 4079 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4080 // and finalizers (if runFinalizersOnExit is set) won't be run. 4081 // Note that if a shutdown hook was registered or runFinalizersOnExit 4082 // was called, the Shutdown class would have already been loaded 4083 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4084 JavaValue result(T_VOID); 4085 JavaCalls::call_static(&result, 4086 shutdown_klass, 4087 vmSymbols::shutdown_method_name(), 4088 vmSymbols::void_method_signature(), 4089 THREAD); 4090 } 4091 CLEAR_PENDING_EXCEPTION; 4092 } 4093 4094 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4095 // the program falls off the end of main(). Another VM exit path is through 4096 // vm_exit() when the program calls System.exit() to return a value or when 4097 // there is a serious error in VM. The two shutdown paths are not exactly 4098 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4099 // and VM_Exit op at VM level. 4100 // 4101 // Shutdown sequence: 4102 // + Shutdown native memory tracking if it is on 4103 // + Wait until we are the last non-daemon thread to execute 4104 // <-- every thing is still working at this moment --> 4105 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4106 // shutdown hooks, run finalizers if finalization-on-exit 4107 // + Call before_exit(), prepare for VM exit 4108 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4109 // currently the only user of this mechanism is File.deleteOnExit()) 4110 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4111 // post thread end and vm death events to JVMTI, 4112 // stop signal thread 4113 // + Call JavaThread::exit(), it will: 4114 // > release JNI handle blocks, remove stack guard pages 4115 // > remove this thread from Threads list 4116 // <-- no more Java code from this thread after this point --> 4117 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4118 // the compiler threads at safepoint 4119 // <-- do not use anything that could get blocked by Safepoint --> 4120 // + Disable tracing at JNI/JVM barriers 4121 // + Set _vm_exited flag for threads that are still running native code 4122 // + Delete this thread 4123 // + Call exit_globals() 4124 // > deletes tty 4125 // > deletes PerfMemory resources 4126 // + Return to caller 4127 4128 bool Threads::destroy_vm() { 4129 JavaThread* thread = JavaThread::current(); 4130 4131 #ifdef ASSERT 4132 _vm_complete = false; 4133 #endif 4134 // Wait until we are the last non-daemon thread to execute 4135 { MutexLocker nu(Threads_lock); 4136 while (Threads::number_of_non_daemon_threads() > 1) 4137 // This wait should make safepoint checks, wait without a timeout, 4138 // and wait as a suspend-equivalent condition. 4139 // 4140 // Note: If the FlatProfiler is running and this thread is waiting 4141 // for another non-daemon thread to finish, then the FlatProfiler 4142 // is waiting for the external suspend request on this thread to 4143 // complete. wait_for_ext_suspend_completion() will eventually 4144 // timeout, but that takes time. Making this wait a suspend- 4145 // equivalent condition solves that timeout problem. 4146 // 4147 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4148 Mutex::_as_suspend_equivalent_flag); 4149 } 4150 4151 // Hang forever on exit if we are reporting an error. 4152 if (ShowMessageBoxOnError && is_error_reported()) { 4153 os::infinite_sleep(); 4154 } 4155 os::wait_for_keypress_at_exit(); 4156 4157 // run Java level shutdown hooks 4158 thread->invoke_shutdown_hooks(); 4159 4160 before_exit(thread); 4161 4162 thread->exit(true); 4163 4164 // Stop VM thread. 4165 { 4166 // 4945125 The vm thread comes to a safepoint during exit. 4167 // GC vm_operations can get caught at the safepoint, and the 4168 // heap is unparseable if they are caught. Grab the Heap_lock 4169 // to prevent this. The GC vm_operations will not be able to 4170 // queue until after the vm thread is dead. After this point, 4171 // we'll never emerge out of the safepoint before the VM exits. 4172 4173 MutexLocker ml(Heap_lock); 4174 4175 VMThread::wait_for_vm_thread_exit(); 4176 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4177 VMThread::destroy(); 4178 } 4179 4180 // clean up ideal graph printers 4181 #if defined(COMPILER2) && !defined(PRODUCT) 4182 IdealGraphPrinter::clean_up(); 4183 #endif 4184 4185 // Now, all Java threads are gone except daemon threads. Daemon threads 4186 // running Java code or in VM are stopped by the Safepoint. However, 4187 // daemon threads executing native code are still running. But they 4188 // will be stopped at native=>Java/VM barriers. Note that we can't 4189 // simply kill or suspend them, as it is inherently deadlock-prone. 4190 4191 VM_Exit::set_vm_exited(); 4192 4193 notify_vm_shutdown(); 4194 4195 delete thread; 4196 4197 #if INCLUDE_JVMCI 4198 if (JVMCICounterSize > 0) { 4199 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4200 } 4201 #endif 4202 4203 // exit_globals() will delete tty 4204 exit_globals(); 4205 4206 LogConfiguration::finalize(); 4207 4208 return true; 4209 } 4210 4211 4212 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4213 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4214 return is_supported_jni_version(version); 4215 } 4216 4217 4218 jboolean Threads::is_supported_jni_version(jint version) { 4219 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4220 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4221 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4222 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4223 if (version == JNI_VERSION_9) return JNI_TRUE; 4224 return JNI_FALSE; 4225 } 4226 4227 4228 void Threads::add(JavaThread* p, bool force_daemon) { 4229 // The threads lock must be owned at this point 4230 assert_locked_or_safepoint(Threads_lock); 4231 4232 // See the comment for this method in thread.hpp for its purpose and 4233 // why it is called here. 4234 p->initialize_queues(); 4235 p->set_next(_thread_list); 4236 _thread_list = p; 4237 _number_of_threads++; 4238 oop threadObj = p->threadObj(); 4239 bool daemon = true; 4240 // Bootstrapping problem: threadObj can be null for initial 4241 // JavaThread (or for threads attached via JNI) 4242 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4243 _number_of_non_daemon_threads++; 4244 daemon = false; 4245 } 4246 4247 ThreadService::add_thread(p, daemon); 4248 4249 // Possible GC point. 4250 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4251 } 4252 4253 void Threads::remove(JavaThread* p) { 4254 // Extra scope needed for Thread_lock, so we can check 4255 // that we do not remove thread without safepoint code notice 4256 { MutexLocker ml(Threads_lock); 4257 4258 assert(includes(p), "p must be present"); 4259 4260 JavaThread* current = _thread_list; 4261 JavaThread* prev = NULL; 4262 4263 while (current != p) { 4264 prev = current; 4265 current = current->next(); 4266 } 4267 4268 if (prev) { 4269 prev->set_next(current->next()); 4270 } else { 4271 _thread_list = p->next(); 4272 } 4273 _number_of_threads--; 4274 oop threadObj = p->threadObj(); 4275 bool daemon = true; 4276 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4277 _number_of_non_daemon_threads--; 4278 daemon = false; 4279 4280 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4281 // on destroy_vm will wake up. 4282 if (number_of_non_daemon_threads() == 1) { 4283 Threads_lock->notify_all(); 4284 } 4285 } 4286 ThreadService::remove_thread(p, daemon); 4287 4288 // Make sure that safepoint code disregard this thread. This is needed since 4289 // the thread might mess around with locks after this point. This can cause it 4290 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4291 // of this thread since it is removed from the queue. 4292 p->set_terminated_value(); 4293 } // unlock Threads_lock 4294 4295 // Since Events::log uses a lock, we grab it outside the Threads_lock 4296 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4297 } 4298 4299 // Threads_lock must be held when this is called (or must be called during a safepoint) 4300 bool Threads::includes(JavaThread* p) { 4301 assert(Threads_lock->is_locked(), "sanity check"); 4302 ALL_JAVA_THREADS(q) { 4303 if (q == p) { 4304 return true; 4305 } 4306 } 4307 return false; 4308 } 4309 4310 // Operations on the Threads list for GC. These are not explicitly locked, 4311 // but the garbage collector must provide a safe context for them to run. 4312 // In particular, these things should never be called when the Threads_lock 4313 // is held by some other thread. (Note: the Safepoint abstraction also 4314 // uses the Threads_lock to guarantee this property. It also makes sure that 4315 // all threads gets blocked when exiting or starting). 4316 4317 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4318 ALL_JAVA_THREADS(p) { 4319 p->oops_do(f, cf); 4320 } 4321 VMThread::vm_thread()->oops_do(f, cf); 4322 } 4323 4324 void Threads::change_thread_claim_parity() { 4325 // Set the new claim parity. 4326 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4327 "Not in range."); 4328 _thread_claim_parity++; 4329 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4330 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4331 "Not in range."); 4332 } 4333 4334 #ifdef ASSERT 4335 void Threads::assert_all_threads_claimed() { 4336 ALL_JAVA_THREADS(p) { 4337 const int thread_parity = p->oops_do_parity(); 4338 assert((thread_parity == _thread_claim_parity), 4339 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4340 } 4341 } 4342 #endif // ASSERT 4343 4344 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4345 int cp = Threads::thread_claim_parity(); 4346 ALL_JAVA_THREADS(p) { 4347 if (p->claim_oops_do(is_par, cp)) { 4348 p->oops_do(f, cf); 4349 } 4350 } 4351 VMThread* vmt = VMThread::vm_thread(); 4352 if (vmt->claim_oops_do(is_par, cp)) { 4353 vmt->oops_do(f, cf); 4354 } 4355 } 4356 4357 #if INCLUDE_ALL_GCS 4358 // Used by ParallelScavenge 4359 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4360 ALL_JAVA_THREADS(p) { 4361 q->enqueue(new ThreadRootsTask(p)); 4362 } 4363 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4364 } 4365 4366 // Used by Parallel Old 4367 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4368 ALL_JAVA_THREADS(p) { 4369 q->enqueue(new ThreadRootsMarkingTask(p)); 4370 } 4371 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4372 } 4373 #endif // INCLUDE_ALL_GCS 4374 4375 void Threads::nmethods_do(CodeBlobClosure* cf) { 4376 ALL_JAVA_THREADS(p) { 4377 // This is used by the code cache sweeper to mark nmethods that are active 4378 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4379 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4380 if(!p->is_Code_cache_sweeper_thread()) { 4381 p->nmethods_do(cf); 4382 } 4383 } 4384 } 4385 4386 void Threads::metadata_do(void f(Metadata*)) { 4387 ALL_JAVA_THREADS(p) { 4388 p->metadata_do(f); 4389 } 4390 } 4391 4392 class ThreadHandlesClosure : public ThreadClosure { 4393 void (*_f)(Metadata*); 4394 public: 4395 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4396 virtual void do_thread(Thread* thread) { 4397 thread->metadata_handles_do(_f); 4398 } 4399 }; 4400 4401 void Threads::metadata_handles_do(void f(Metadata*)) { 4402 // Only walk the Handles in Thread. 4403 ThreadHandlesClosure handles_closure(f); 4404 threads_do(&handles_closure); 4405 } 4406 4407 void Threads::deoptimized_wrt_marked_nmethods() { 4408 ALL_JAVA_THREADS(p) { 4409 p->deoptimized_wrt_marked_nmethods(); 4410 } 4411 } 4412 4413 4414 // Get count Java threads that are waiting to enter the specified monitor. 4415 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4416 address monitor, 4417 bool doLock) { 4418 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4419 "must grab Threads_lock or be at safepoint"); 4420 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4421 4422 int i = 0; 4423 { 4424 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4425 ALL_JAVA_THREADS(p) { 4426 if (!p->can_call_java()) continue; 4427 4428 address pending = (address)p->current_pending_monitor(); 4429 if (pending == monitor) { // found a match 4430 if (i < count) result->append(p); // save the first count matches 4431 i++; 4432 } 4433 } 4434 } 4435 return result; 4436 } 4437 4438 4439 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4440 bool doLock) { 4441 assert(doLock || 4442 Threads_lock->owned_by_self() || 4443 SafepointSynchronize::is_at_safepoint(), 4444 "must grab Threads_lock or be at safepoint"); 4445 4446 // NULL owner means not locked so we can skip the search 4447 if (owner == NULL) return NULL; 4448 4449 { 4450 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4451 ALL_JAVA_THREADS(p) { 4452 // first, see if owner is the address of a Java thread 4453 if (owner == (address)p) return p; 4454 } 4455 } 4456 // Cannot assert on lack of success here since this function may be 4457 // used by code that is trying to report useful problem information 4458 // like deadlock detection. 4459 if (UseHeavyMonitors) return NULL; 4460 4461 // If we didn't find a matching Java thread and we didn't force use of 4462 // heavyweight monitors, then the owner is the stack address of the 4463 // Lock Word in the owning Java thread's stack. 4464 // 4465 JavaThread* the_owner = NULL; 4466 { 4467 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4468 ALL_JAVA_THREADS(q) { 4469 if (q->is_lock_owned(owner)) { 4470 the_owner = q; 4471 break; 4472 } 4473 } 4474 } 4475 // cannot assert on lack of success here; see above comment 4476 return the_owner; 4477 } 4478 4479 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4480 void Threads::print_on(outputStream* st, bool print_stacks, 4481 bool internal_format, bool print_concurrent_locks) { 4482 char buf[32]; 4483 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4484 4485 st->print_cr("Full thread dump %s (%s %s):", 4486 Abstract_VM_Version::vm_name(), 4487 Abstract_VM_Version::vm_release(), 4488 Abstract_VM_Version::vm_info_string()); 4489 st->cr(); 4490 4491 #if INCLUDE_SERVICES 4492 // Dump concurrent locks 4493 ConcurrentLocksDump concurrent_locks; 4494 if (print_concurrent_locks) { 4495 concurrent_locks.dump_at_safepoint(); 4496 } 4497 #endif // INCLUDE_SERVICES 4498 4499 ALL_JAVA_THREADS(p) { 4500 ResourceMark rm; 4501 p->print_on(st); 4502 if (print_stacks) { 4503 if (internal_format) { 4504 p->trace_stack(); 4505 } else { 4506 p->print_stack_on(st); 4507 } 4508 } 4509 st->cr(); 4510 #if INCLUDE_SERVICES 4511 if (print_concurrent_locks) { 4512 concurrent_locks.print_locks_on(p, st); 4513 } 4514 #endif // INCLUDE_SERVICES 4515 } 4516 4517 VMThread::vm_thread()->print_on(st); 4518 st->cr(); 4519 Universe::heap()->print_gc_threads_on(st); 4520 WatcherThread* wt = WatcherThread::watcher_thread(); 4521 if (wt != NULL) { 4522 wt->print_on(st); 4523 st->cr(); 4524 } 4525 st->flush(); 4526 } 4527 4528 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4529 int buflen, bool* found_current) { 4530 if (this_thread != NULL) { 4531 bool is_current = (current == this_thread); 4532 *found_current = *found_current || is_current; 4533 st->print("%s", is_current ? "=>" : " "); 4534 4535 st->print(PTR_FORMAT, p2i(this_thread)); 4536 st->print(" "); 4537 this_thread->print_on_error(st, buf, buflen); 4538 st->cr(); 4539 } 4540 } 4541 4542 class PrintOnErrorClosure : public ThreadClosure { 4543 outputStream* _st; 4544 Thread* _current; 4545 char* _buf; 4546 int _buflen; 4547 bool* _found_current; 4548 public: 4549 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4550 int buflen, bool* found_current) : 4551 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4552 4553 virtual void do_thread(Thread* thread) { 4554 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4555 } 4556 }; 4557 4558 // Threads::print_on_error() is called by fatal error handler. It's possible 4559 // that VM is not at safepoint and/or current thread is inside signal handler. 4560 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4561 // memory (even in resource area), it might deadlock the error handler. 4562 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4563 int buflen) { 4564 bool found_current = false; 4565 st->print_cr("Java Threads: ( => current thread )"); 4566 ALL_JAVA_THREADS(thread) { 4567 print_on_error(thread, st, current, buf, buflen, &found_current); 4568 } 4569 st->cr(); 4570 4571 st->print_cr("Other Threads:"); 4572 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4573 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4574 4575 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4576 Universe::heap()->gc_threads_do(&print_closure); 4577 4578 if (!found_current) { 4579 st->cr(); 4580 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4581 current->print_on_error(st, buf, buflen); 4582 st->cr(); 4583 } 4584 st->cr(); 4585 st->print_cr("Threads with active compile tasks:"); 4586 print_threads_compiling(st, buf, buflen); 4587 } 4588 4589 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4590 ALL_JAVA_THREADS(thread) { 4591 if (thread->is_Compiler_thread()) { 4592 CompilerThread* ct = (CompilerThread*) thread; 4593 if (ct->task() != NULL) { 4594 thread->print_name_on_error(st, buf, buflen); 4595 ct->task()->print(st, NULL, true, true); 4596 } 4597 } 4598 } 4599 } 4600 4601 4602 // Internal SpinLock and Mutex 4603 // Based on ParkEvent 4604 4605 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4606 // 4607 // We employ SpinLocks _only for low-contention, fixed-length 4608 // short-duration critical sections where we're concerned 4609 // about native mutex_t or HotSpot Mutex:: latency. 4610 // The mux construct provides a spin-then-block mutual exclusion 4611 // mechanism. 4612 // 4613 // Testing has shown that contention on the ListLock guarding gFreeList 4614 // is common. If we implement ListLock as a simple SpinLock it's common 4615 // for the JVM to devolve to yielding with little progress. This is true 4616 // despite the fact that the critical sections protected by ListLock are 4617 // extremely short. 4618 // 4619 // TODO-FIXME: ListLock should be of type SpinLock. 4620 // We should make this a 1st-class type, integrated into the lock 4621 // hierarchy as leaf-locks. Critically, the SpinLock structure 4622 // should have sufficient padding to avoid false-sharing and excessive 4623 // cache-coherency traffic. 4624 4625 4626 typedef volatile int SpinLockT; 4627 4628 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4629 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4630 return; // normal fast-path return 4631 } 4632 4633 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4634 TEVENT(SpinAcquire - ctx); 4635 int ctr = 0; 4636 int Yields = 0; 4637 for (;;) { 4638 while (*adr != 0) { 4639 ++ctr; 4640 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4641 if (Yields > 5) { 4642 os::naked_short_sleep(1); 4643 } else { 4644 os::naked_yield(); 4645 ++Yields; 4646 } 4647 } else { 4648 SpinPause(); 4649 } 4650 } 4651 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4652 } 4653 } 4654 4655 void Thread::SpinRelease(volatile int * adr) { 4656 assert(*adr != 0, "invariant"); 4657 OrderAccess::fence(); // guarantee at least release consistency. 4658 // Roach-motel semantics. 4659 // It's safe if subsequent LDs and STs float "up" into the critical section, 4660 // but prior LDs and STs within the critical section can't be allowed 4661 // to reorder or float past the ST that releases the lock. 4662 // Loads and stores in the critical section - which appear in program 4663 // order before the store that releases the lock - must also appear 4664 // before the store that releases the lock in memory visibility order. 4665 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4666 // the ST of 0 into the lock-word which releases the lock, so fence 4667 // more than covers this on all platforms. 4668 *adr = 0; 4669 } 4670 4671 // muxAcquire and muxRelease: 4672 // 4673 // * muxAcquire and muxRelease support a single-word lock-word construct. 4674 // The LSB of the word is set IFF the lock is held. 4675 // The remainder of the word points to the head of a singly-linked list 4676 // of threads blocked on the lock. 4677 // 4678 // * The current implementation of muxAcquire-muxRelease uses its own 4679 // dedicated Thread._MuxEvent instance. If we're interested in 4680 // minimizing the peak number of extant ParkEvent instances then 4681 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4682 // as certain invariants were satisfied. Specifically, care would need 4683 // to be taken with regards to consuming unpark() "permits". 4684 // A safe rule of thumb is that a thread would never call muxAcquire() 4685 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4686 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4687 // consume an unpark() permit intended for monitorenter, for instance. 4688 // One way around this would be to widen the restricted-range semaphore 4689 // implemented in park(). Another alternative would be to provide 4690 // multiple instances of the PlatformEvent() for each thread. One 4691 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4692 // 4693 // * Usage: 4694 // -- Only as leaf locks 4695 // -- for short-term locking only as muxAcquire does not perform 4696 // thread state transitions. 4697 // 4698 // Alternatives: 4699 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4700 // but with parking or spin-then-park instead of pure spinning. 4701 // * Use Taura-Oyama-Yonenzawa locks. 4702 // * It's possible to construct a 1-0 lock if we encode the lockword as 4703 // (List,LockByte). Acquire will CAS the full lockword while Release 4704 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4705 // acquiring threads use timers (ParkTimed) to detect and recover from 4706 // the stranding window. Thread/Node structures must be aligned on 256-byte 4707 // boundaries by using placement-new. 4708 // * Augment MCS with advisory back-link fields maintained with CAS(). 4709 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4710 // The validity of the backlinks must be ratified before we trust the value. 4711 // If the backlinks are invalid the exiting thread must back-track through the 4712 // the forward links, which are always trustworthy. 4713 // * Add a successor indication. The LockWord is currently encoded as 4714 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4715 // to provide the usual futile-wakeup optimization. 4716 // See RTStt for details. 4717 // * Consider schedctl.sc_nopreempt to cover the critical section. 4718 // 4719 4720 4721 typedef volatile intptr_t MutexT; // Mux Lock-word 4722 enum MuxBits { LOCKBIT = 1 }; 4723 4724 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4725 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4726 if (w == 0) return; 4727 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4728 return; 4729 } 4730 4731 TEVENT(muxAcquire - Contention); 4732 ParkEvent * const Self = Thread::current()->_MuxEvent; 4733 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4734 for (;;) { 4735 int its = (os::is_MP() ? 100 : 0) + 1; 4736 4737 // Optional spin phase: spin-then-park strategy 4738 while (--its >= 0) { 4739 w = *Lock; 4740 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4741 return; 4742 } 4743 } 4744 4745 Self->reset(); 4746 Self->OnList = intptr_t(Lock); 4747 // The following fence() isn't _strictly necessary as the subsequent 4748 // CAS() both serializes execution and ratifies the fetched *Lock value. 4749 OrderAccess::fence(); 4750 for (;;) { 4751 w = *Lock; 4752 if ((w & LOCKBIT) == 0) { 4753 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4754 Self->OnList = 0; // hygiene - allows stronger asserts 4755 return; 4756 } 4757 continue; // Interference -- *Lock changed -- Just retry 4758 } 4759 assert(w & LOCKBIT, "invariant"); 4760 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4761 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4762 } 4763 4764 while (Self->OnList != 0) { 4765 Self->park(); 4766 } 4767 } 4768 } 4769 4770 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4771 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4772 if (w == 0) return; 4773 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4774 return; 4775 } 4776 4777 TEVENT(muxAcquire - Contention); 4778 ParkEvent * ReleaseAfter = NULL; 4779 if (ev == NULL) { 4780 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4781 } 4782 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4783 for (;;) { 4784 guarantee(ev->OnList == 0, "invariant"); 4785 int its = (os::is_MP() ? 100 : 0) + 1; 4786 4787 // Optional spin phase: spin-then-park strategy 4788 while (--its >= 0) { 4789 w = *Lock; 4790 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4791 if (ReleaseAfter != NULL) { 4792 ParkEvent::Release(ReleaseAfter); 4793 } 4794 return; 4795 } 4796 } 4797 4798 ev->reset(); 4799 ev->OnList = intptr_t(Lock); 4800 // The following fence() isn't _strictly necessary as the subsequent 4801 // CAS() both serializes execution and ratifies the fetched *Lock value. 4802 OrderAccess::fence(); 4803 for (;;) { 4804 w = *Lock; 4805 if ((w & LOCKBIT) == 0) { 4806 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4807 ev->OnList = 0; 4808 // We call ::Release while holding the outer lock, thus 4809 // artificially lengthening the critical section. 4810 // Consider deferring the ::Release() until the subsequent unlock(), 4811 // after we've dropped the outer lock. 4812 if (ReleaseAfter != NULL) { 4813 ParkEvent::Release(ReleaseAfter); 4814 } 4815 return; 4816 } 4817 continue; // Interference -- *Lock changed -- Just retry 4818 } 4819 assert(w & LOCKBIT, "invariant"); 4820 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4821 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4822 } 4823 4824 while (ev->OnList != 0) { 4825 ev->park(); 4826 } 4827 } 4828 } 4829 4830 // Release() must extract a successor from the list and then wake that thread. 4831 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4832 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4833 // Release() would : 4834 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4835 // (B) Extract a successor from the private list "in-hand" 4836 // (C) attempt to CAS() the residual back into *Lock over null. 4837 // If there were any newly arrived threads and the CAS() would fail. 4838 // In that case Release() would detach the RATs, re-merge the list in-hand 4839 // with the RATs and repeat as needed. Alternately, Release() might 4840 // detach and extract a successor, but then pass the residual list to the wakee. 4841 // The wakee would be responsible for reattaching and remerging before it 4842 // competed for the lock. 4843 // 4844 // Both "pop" and DMR are immune from ABA corruption -- there can be 4845 // multiple concurrent pushers, but only one popper or detacher. 4846 // This implementation pops from the head of the list. This is unfair, 4847 // but tends to provide excellent throughput as hot threads remain hot. 4848 // (We wake recently run threads first). 4849 // 4850 // All paths through muxRelease() will execute a CAS. 4851 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4852 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4853 // executed within the critical section are complete and globally visible before the 4854 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4855 void Thread::muxRelease(volatile intptr_t * Lock) { 4856 for (;;) { 4857 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4858 assert(w & LOCKBIT, "invariant"); 4859 if (w == LOCKBIT) return; 4860 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4861 assert(List != NULL, "invariant"); 4862 assert(List->OnList == intptr_t(Lock), "invariant"); 4863 ParkEvent * const nxt = List->ListNext; 4864 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4865 4866 // The following CAS() releases the lock and pops the head element. 4867 // The CAS() also ratifies the previously fetched lock-word value. 4868 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4869 continue; 4870 } 4871 List->OnList = 0; 4872 OrderAccess::fence(); 4873 List->unpark(); 4874 return; 4875 } 4876 } 4877 4878 4879 void Threads::verify() { 4880 ALL_JAVA_THREADS(p) { 4881 p->verify(); 4882 } 4883 VMThread* thread = VMThread::vm_thread(); 4884 if (thread != NULL) thread->verify(); 4885 }