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/shenandoah/shenandoahConcurrentThread.hpp" 105 #include "gc/cms/concurrentMarkSweepThread.hpp" 106 #include "gc/g1/concurrentMarkThread.inline.hpp" 107 #include "gc/parallel/pcTasks.hpp" 108 #endif // INCLUDE_ALL_GCS 109 #if INCLUDE_JVMCI 110 #include "jvmci/jvmciCompiler.hpp" 111 #include "jvmci/jvmciRuntime.hpp" 112 #endif 113 #ifdef COMPILER1 114 #include "c1/c1_Compiler.hpp" 115 #endif 116 #ifdef COMPILER2 117 #include "opto/c2compiler.hpp" 118 #include "opto/idealGraphPrinter.hpp" 119 #endif 120 #if INCLUDE_RTM_OPT 121 #include "runtime/rtmLocking.hpp" 122 #endif 123 124 // Initialization after module runtime initialization 125 void universe_post_module_init(); // must happen after call_initPhase2 126 127 #ifdef DTRACE_ENABLED 128 129 // Only bother with this argument setup if dtrace is available 130 131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 133 134 #define DTRACE_THREAD_PROBE(probe, javathread) \ 135 { \ 136 ResourceMark rm(this); \ 137 int len = 0; \ 138 const char* name = (javathread)->get_thread_name(); \ 139 len = strlen(name); \ 140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 141 (char *) name, len, \ 142 java_lang_Thread::thread_id((javathread)->threadObj()), \ 143 (uintptr_t) (javathread)->osthread()->thread_id(), \ 144 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 145 } 146 147 #else // ndef DTRACE_ENABLED 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) 150 151 #endif // ndef DTRACE_ENABLED 152 153 #ifndef USE_LIBRARY_BASED_TLS_ONLY 154 // Current thread is maintained as a thread-local variable 155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 156 #endif 157 // Class hierarchy 158 // - Thread 159 // - VMThread 160 // - WatcherThread 161 // - ConcurrentMarkSweepThread 162 // - JavaThread 163 // - CompilerThread 164 165 // ======= Thread ======== 166 // Support for forcing alignment of thread objects for biased locking 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 168 if (UseBiasedLocking) { 169 const int alignment = markOopDesc::biased_lock_alignment; 170 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 172 : AllocateHeap(aligned_size, flags, CURRENT_PC, 173 AllocFailStrategy::RETURN_NULL); 174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 177 "JavaThread alignment code overflowed allocated storage"); 178 if (aligned_addr != real_malloc_addr) { 179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 180 p2i(real_malloc_addr), 181 p2i(aligned_addr)); 182 } 183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 184 return aligned_addr; 185 } else { 186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 188 } 189 } 190 191 void Thread::operator delete(void* p) { 192 if (UseBiasedLocking) { 193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 194 FreeHeap(real_malloc_addr); 195 } else { 196 FreeHeap(p); 197 } 198 } 199 200 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 202 // JavaThread 203 204 205 Thread::Thread() { 206 // stack and get_thread 207 set_stack_base(NULL); 208 set_stack_size(0); 209 set_self_raw_id(0); 210 set_lgrp_id(-1); 211 DEBUG_ONLY(clear_suspendible_thread();) 212 213 // allocated data structures 214 set_osthread(NULL); 215 set_resource_area(new (mtThread)ResourceArea()); 216 DEBUG_ONLY(_current_resource_mark = NULL;) 217 set_handle_area(new (mtThread) HandleArea(NULL)); 218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 219 set_active_handles(NULL); 220 set_free_handle_block(NULL); 221 set_last_handle_mark(NULL); 222 223 // This initial value ==> never claimed. 224 _oops_do_parity = 0; 225 226 // the handle mark links itself to last_handle_mark 227 new HandleMark(this); 228 229 // plain initialization 230 debug_only(_owned_locks = NULL;) 231 debug_only(_allow_allocation_count = 0;) 232 NOT_PRODUCT(_allow_safepoint_count = 0;) 233 NOT_PRODUCT(_skip_gcalot = false;) 234 _jvmti_env_iteration_count = 0; 235 set_allocated_bytes(0); 236 _vm_operation_started_count = 0; 237 _vm_operation_completed_count = 0; 238 _current_pending_monitor = NULL; 239 _current_pending_monitor_is_from_java = true; 240 _current_waiting_monitor = NULL; 241 _num_nested_signal = 0; 242 omFreeList = NULL; 243 omFreeCount = 0; 244 omFreeProvision = 32; 245 omInUseList = NULL; 246 omInUseCount = 0; 247 248 #ifdef ASSERT 249 _visited_for_critical_count = false; 250 #endif 251 252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 253 Monitor::_safepoint_check_sometimes); 254 _suspend_flags = 0; 255 256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 257 _hashStateX = os::random(); 258 _hashStateY = 842502087; 259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 260 _hashStateW = 273326509; 261 262 _OnTrap = 0; 263 _schedctl = NULL; 264 _Stalled = 0; 265 _TypeTag = 0x2BAD; 266 267 // Many of the following fields are effectively final - immutable 268 // Note that nascent threads can't use the Native Monitor-Mutex 269 // construct until the _MutexEvent is initialized ... 270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 271 // we might instead use a stack of ParkEvents that we could provision on-demand. 272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 273 // and ::Release() 274 _ParkEvent = ParkEvent::Allocate(this); 275 _SleepEvent = ParkEvent::Allocate(this); 276 _MutexEvent = ParkEvent::Allocate(this); 277 _MuxEvent = ParkEvent::Allocate(this); 278 279 #ifdef CHECK_UNHANDLED_OOPS 280 if (CheckUnhandledOops) { 281 _unhandled_oops = new UnhandledOops(this); 282 } 283 #endif // CHECK_UNHANDLED_OOPS 284 #ifdef ASSERT 285 if (UseBiasedLocking) { 286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 287 assert(this == _real_malloc_address || 288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 289 "bug in forced alignment of thread objects"); 290 } 291 #endif // ASSERT 292 } 293 294 void Thread::initialize_thread_current() { 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY 296 assert(_thr_current == NULL, "Thread::current already initialized"); 297 _thr_current = this; 298 #endif 299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 300 ThreadLocalStorage::set_thread(this); 301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 302 } 303 304 void Thread::clear_thread_current() { 305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY 307 _thr_current = NULL; 308 #endif 309 ThreadLocalStorage::set_thread(NULL); 310 } 311 312 void Thread::record_stack_base_and_size() { 313 set_stack_base(os::current_stack_base()); 314 set_stack_size(os::current_stack_size()); 315 // CR 7190089: on Solaris, primordial thread's stack is adjusted 316 // in initialize_thread(). Without the adjustment, stack size is 317 // incorrect if stack is set to unlimited (ulimit -s unlimited). 318 // So far, only Solaris has real implementation of initialize_thread(). 319 // 320 // set up any platform-specific state. 321 os::initialize_thread(this); 322 323 // Set stack limits after thread is initialized. 324 if (is_Java_thread()) { 325 ((JavaThread*) this)->set_stack_overflow_limit(); 326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 327 } 328 #if INCLUDE_NMT 329 // record thread's native stack, stack grows downward 330 MemTracker::record_thread_stack(stack_end(), stack_size()); 331 #endif // INCLUDE_NMT 332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 334 os::current_thread_id(), p2i(stack_base() - stack_size()), 335 p2i(stack_base()), stack_size()/1024); 336 } 337 338 339 Thread::~Thread() { 340 EVENT_THREAD_DESTRUCT(this); 341 342 // stack_base can be NULL if the thread is never started or exited before 343 // record_stack_base_and_size called. Although, we would like to ensure 344 // that all started threads do call record_stack_base_and_size(), there is 345 // not proper way to enforce that. 346 #if INCLUDE_NMT 347 if (_stack_base != NULL) { 348 MemTracker::release_thread_stack(stack_end(), stack_size()); 349 #ifdef ASSERT 350 set_stack_base(NULL); 351 #endif 352 } 353 #endif // INCLUDE_NMT 354 355 // deallocate data structures 356 delete resource_area(); 357 // since the handle marks are using the handle area, we have to deallocated the root 358 // handle mark before deallocating the thread's handle area, 359 assert(last_handle_mark() != NULL, "check we have an element"); 360 delete last_handle_mark(); 361 assert(last_handle_mark() == NULL, "check we have reached the end"); 362 363 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 364 // We NULL out the fields for good hygiene. 365 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 366 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 367 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 368 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 369 370 delete handle_area(); 371 delete metadata_handles(); 372 373 // SR_handler uses this as a termination indicator - 374 // needs to happen before os::free_thread() 375 delete _SR_lock; 376 _SR_lock = NULL; 377 378 // osthread() can be NULL, if creation of thread failed. 379 if (osthread() != NULL) os::free_thread(osthread()); 380 381 // clear Thread::current if thread is deleting itself. 382 // Needed to ensure JNI correctly detects non-attached threads. 383 if (this == Thread::current()) { 384 clear_thread_current(); 385 } 386 387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 388 } 389 390 // NOTE: dummy function for assertion purpose. 391 void Thread::run() { 392 ShouldNotReachHere(); 393 } 394 395 #ifdef ASSERT 396 // Private method to check for dangling thread pointer 397 void check_for_dangling_thread_pointer(Thread *thread) { 398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 399 "possibility of dangling Thread pointer"); 400 } 401 #endif 402 403 ThreadPriority Thread::get_priority(const Thread* const thread) { 404 ThreadPriority priority; 405 // Can return an error! 406 (void)os::get_priority(thread, priority); 407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 408 return priority; 409 } 410 411 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 412 debug_only(check_for_dangling_thread_pointer(thread);) 413 // Can return an error! 414 (void)os::set_priority(thread, priority); 415 } 416 417 418 void Thread::start(Thread* thread) { 419 // Start is different from resume in that its safety is guaranteed by context or 420 // being called from a Java method synchronized on the Thread object. 421 if (!DisableStartThread) { 422 if (thread->is_Java_thread()) { 423 // Initialize the thread state to RUNNABLE before starting this thread. 424 // Can not set it after the thread started because we do not know the 425 // exact thread state at that time. It could be in MONITOR_WAIT or 426 // in SLEEPING or some other state. 427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 428 java_lang_Thread::RUNNABLE); 429 } 430 os::start_thread(thread); 431 } 432 } 433 434 // Enqueue a VM_Operation to do the job for us - sometime later 435 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 437 VMThread::execute(vm_stop); 438 } 439 440 441 // Check if an external suspend request has completed (or has been 442 // cancelled). Returns true if the thread is externally suspended and 443 // false otherwise. 444 // 445 // The bits parameter returns information about the code path through 446 // the routine. Useful for debugging: 447 // 448 // set in is_ext_suspend_completed(): 449 // 0x00000001 - routine was entered 450 // 0x00000010 - routine return false at end 451 // 0x00000100 - thread exited (return false) 452 // 0x00000200 - suspend request cancelled (return false) 453 // 0x00000400 - thread suspended (return true) 454 // 0x00001000 - thread is in a suspend equivalent state (return true) 455 // 0x00002000 - thread is native and walkable (return true) 456 // 0x00004000 - thread is native_trans and walkable (needed retry) 457 // 458 // set in wait_for_ext_suspend_completion(): 459 // 0x00010000 - routine was entered 460 // 0x00020000 - suspend request cancelled before loop (return false) 461 // 0x00040000 - thread suspended before loop (return true) 462 // 0x00080000 - suspend request cancelled in loop (return false) 463 // 0x00100000 - thread suspended in loop (return true) 464 // 0x00200000 - suspend not completed during retry loop (return false) 465 466 // Helper class for tracing suspend wait debug bits. 467 // 468 // 0x00000100 indicates that the target thread exited before it could 469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 470 // 0x00080000 each indicate a cancelled suspend request so they don't 471 // count as wait failures either. 472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 473 474 class TraceSuspendDebugBits : public StackObj { 475 private: 476 JavaThread * jt; 477 bool is_wait; 478 bool called_by_wait; // meaningful when !is_wait 479 uint32_t * bits; 480 481 public: 482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 483 uint32_t *_bits) { 484 jt = _jt; 485 is_wait = _is_wait; 486 called_by_wait = _called_by_wait; 487 bits = _bits; 488 } 489 490 ~TraceSuspendDebugBits() { 491 if (!is_wait) { 492 #if 1 493 // By default, don't trace bits for is_ext_suspend_completed() calls. 494 // That trace is very chatty. 495 return; 496 #else 497 if (!called_by_wait) { 498 // If tracing for is_ext_suspend_completed() is enabled, then only 499 // trace calls to it from wait_for_ext_suspend_completion() 500 return; 501 } 502 #endif 503 } 504 505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 507 MutexLocker ml(Threads_lock); // needed for get_thread_name() 508 ResourceMark rm; 509 510 tty->print_cr( 511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 512 jt->get_thread_name(), *bits); 513 514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 515 } 516 } 517 } 518 }; 519 #undef DEBUG_FALSE_BITS 520 521 522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 523 uint32_t *bits) { 524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 525 526 bool did_trans_retry = false; // only do thread_in_native_trans retry once 527 bool do_trans_retry; // flag to force the retry 528 529 *bits |= 0x00000001; 530 531 do { 532 do_trans_retry = false; 533 534 if (is_exiting()) { 535 // Thread is in the process of exiting. This is always checked 536 // first to reduce the risk of dereferencing a freed JavaThread. 537 *bits |= 0x00000100; 538 return false; 539 } 540 541 if (!is_external_suspend()) { 542 // Suspend request is cancelled. This is always checked before 543 // is_ext_suspended() to reduce the risk of a rogue resume 544 // confusing the thread that made the suspend request. 545 *bits |= 0x00000200; 546 return false; 547 } 548 549 if (is_ext_suspended()) { 550 // thread is suspended 551 *bits |= 0x00000400; 552 return true; 553 } 554 555 // Now that we no longer do hard suspends of threads running 556 // native code, the target thread can be changing thread state 557 // while we are in this routine: 558 // 559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 560 // 561 // We save a copy of the thread state as observed at this moment 562 // and make our decision about suspend completeness based on the 563 // copy. This closes the race where the thread state is seen as 564 // _thread_in_native_trans in the if-thread_blocked check, but is 565 // seen as _thread_blocked in if-thread_in_native_trans check. 566 JavaThreadState save_state = thread_state(); 567 568 if (save_state == _thread_blocked && is_suspend_equivalent()) { 569 // If the thread's state is _thread_blocked and this blocking 570 // condition is known to be equivalent to a suspend, then we can 571 // consider the thread to be externally suspended. This means that 572 // the code that sets _thread_blocked has been modified to do 573 // self-suspension if the blocking condition releases. We also 574 // used to check for CONDVAR_WAIT here, but that is now covered by 575 // the _thread_blocked with self-suspension check. 576 // 577 // Return true since we wouldn't be here unless there was still an 578 // external suspend request. 579 *bits |= 0x00001000; 580 return true; 581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 582 // Threads running native code will self-suspend on native==>VM/Java 583 // transitions. If its stack is walkable (should always be the case 584 // unless this function is called before the actual java_suspend() 585 // call), then the wait is done. 586 *bits |= 0x00002000; 587 return true; 588 } else if (!called_by_wait && !did_trans_retry && 589 save_state == _thread_in_native_trans && 590 frame_anchor()->walkable()) { 591 // The thread is transitioning from thread_in_native to another 592 // thread state. check_safepoint_and_suspend_for_native_trans() 593 // will force the thread to self-suspend. If it hasn't gotten 594 // there yet we may have caught the thread in-between the native 595 // code check above and the self-suspend. Lucky us. If we were 596 // called by wait_for_ext_suspend_completion(), then it 597 // will be doing the retries so we don't have to. 598 // 599 // Since we use the saved thread state in the if-statement above, 600 // there is a chance that the thread has already transitioned to 601 // _thread_blocked by the time we get here. In that case, we will 602 // make a single unnecessary pass through the logic below. This 603 // doesn't hurt anything since we still do the trans retry. 604 605 *bits |= 0x00004000; 606 607 // Once the thread leaves thread_in_native_trans for another 608 // thread state, we break out of this retry loop. We shouldn't 609 // need this flag to prevent us from getting back here, but 610 // sometimes paranoia is good. 611 did_trans_retry = true; 612 613 // We wait for the thread to transition to a more usable state. 614 for (int i = 1; i <= SuspendRetryCount; i++) { 615 // We used to do an "os::yield_all(i)" call here with the intention 616 // that yielding would increase on each retry. However, the parameter 617 // is ignored on Linux which means the yield didn't scale up. Waiting 618 // on the SR_lock below provides a much more predictable scale up for 619 // the delay. It also provides a simple/direct point to check for any 620 // safepoint requests from the VMThread 621 622 // temporarily drops SR_lock while doing wait with safepoint check 623 // (if we're a JavaThread - the WatcherThread can also call this) 624 // and increase delay with each retry 625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 626 627 // check the actual thread state instead of what we saved above 628 if (thread_state() != _thread_in_native_trans) { 629 // the thread has transitioned to another thread state so 630 // try all the checks (except this one) one more time. 631 do_trans_retry = true; 632 break; 633 } 634 } // end retry loop 635 636 637 } 638 } while (do_trans_retry); 639 640 *bits |= 0x00000010; 641 return false; 642 } 643 644 // Wait for an external suspend request to complete (or be cancelled). 645 // Returns true if the thread is externally suspended and false otherwise. 646 // 647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 648 uint32_t *bits) { 649 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 650 false /* !called_by_wait */, bits); 651 652 // local flag copies to minimize SR_lock hold time 653 bool is_suspended; 654 bool pending; 655 uint32_t reset_bits; 656 657 // set a marker so is_ext_suspend_completed() knows we are the caller 658 *bits |= 0x00010000; 659 660 // We use reset_bits to reinitialize the bits value at the top of 661 // each retry loop. This allows the caller to make use of any 662 // unused bits for their own marking purposes. 663 reset_bits = *bits; 664 665 { 666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 668 delay, bits); 669 pending = is_external_suspend(); 670 } 671 // must release SR_lock to allow suspension to complete 672 673 if (!pending) { 674 // A cancelled suspend request is the only false return from 675 // is_ext_suspend_completed() that keeps us from entering the 676 // retry loop. 677 *bits |= 0x00020000; 678 return false; 679 } 680 681 if (is_suspended) { 682 *bits |= 0x00040000; 683 return true; 684 } 685 686 for (int i = 1; i <= retries; i++) { 687 *bits = reset_bits; // reinit to only track last retry 688 689 // We used to do an "os::yield_all(i)" call here with the intention 690 // that yielding would increase on each retry. However, the parameter 691 // is ignored on Linux which means the yield didn't scale up. Waiting 692 // on the SR_lock below provides a much more predictable scale up for 693 // the delay. It also provides a simple/direct point to check for any 694 // safepoint requests from the VMThread 695 696 { 697 MutexLocker ml(SR_lock()); 698 // wait with safepoint check (if we're a JavaThread - the WatcherThread 699 // can also call this) and increase delay with each retry 700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 701 702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 703 delay, bits); 704 705 // It is possible for the external suspend request to be cancelled 706 // (by a resume) before the actual suspend operation is completed. 707 // Refresh our local copy to see if we still need to wait. 708 pending = is_external_suspend(); 709 } 710 711 if (!pending) { 712 // A cancelled suspend request is the only false return from 713 // is_ext_suspend_completed() that keeps us from staying in the 714 // retry loop. 715 *bits |= 0x00080000; 716 return false; 717 } 718 719 if (is_suspended) { 720 *bits |= 0x00100000; 721 return true; 722 } 723 } // end retry loop 724 725 // thread did not suspend after all our retries 726 *bits |= 0x00200000; 727 return false; 728 } 729 730 #ifndef PRODUCT 731 void JavaThread::record_jump(address target, address instr, const char* file, 732 int line) { 733 734 // This should not need to be atomic as the only way for simultaneous 735 // updates is via interrupts. Even then this should be rare or non-existent 736 // and we don't care that much anyway. 737 738 int index = _jmp_ring_index; 739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 740 _jmp_ring[index]._target = (intptr_t) target; 741 _jmp_ring[index]._instruction = (intptr_t) instr; 742 _jmp_ring[index]._file = file; 743 _jmp_ring[index]._line = line; 744 } 745 #endif // PRODUCT 746 747 // Called by flat profiler 748 // Callers have already called wait_for_ext_suspend_completion 749 // The assertion for that is currently too complex to put here: 750 bool JavaThread::profile_last_Java_frame(frame* _fr) { 751 bool gotframe = false; 752 // self suspension saves needed state. 753 if (has_last_Java_frame() && _anchor.walkable()) { 754 *_fr = pd_last_frame(); 755 gotframe = true; 756 } 757 return gotframe; 758 } 759 760 void Thread::interrupt(Thread* thread) { 761 debug_only(check_for_dangling_thread_pointer(thread);) 762 os::interrupt(thread); 763 } 764 765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 766 debug_only(check_for_dangling_thread_pointer(thread);) 767 // Note: If clear_interrupted==false, this simply fetches and 768 // returns the value of the field osthread()->interrupted(). 769 return os::is_interrupted(thread, clear_interrupted); 770 } 771 772 773 // GC Support 774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 775 jint thread_parity = _oops_do_parity; 776 if (thread_parity != strong_roots_parity) { 777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 778 if (res == thread_parity) { 779 return true; 780 } else { 781 guarantee(res == strong_roots_parity, "Or else what?"); 782 return false; 783 } 784 } 785 return false; 786 } 787 788 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 789 active_handles()->oops_do(f); 790 // Do oop for ThreadShadow 791 f->do_oop((oop*)&_pending_exception); 792 handle_area()->oops_do(f); 793 if (MonitorInUseLists) { 794 VM_Operation* op = VMThread::vm_operation(); 795 if (op != NULL && op->deflates_idle_monitors()) { 796 ObjectSynchronizer::deflate_idle_monitors_and_oops_do(this, f); 797 } else { 798 ObjectSynchronizer::thread_local_used_oops_do(this, f); 799 } 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 instanceKlassHandle klass (THREAD, k); 960 961 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 962 { 963 JavaValue result(T_VOID); 964 JavaCalls::call_special(&result, 965 system_instance, 966 klass, 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 = klass->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 klass, 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 instanceKlassHandle klass (THREAD, k); 994 instanceHandle thread_oop = klass->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 klass, 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* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1064 instanceKlassHandle klass (THREAD, k); 1065 if (klass.not_null()) { 1066 JavaValue result(T_VOID); 1067 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1068 vmSymbols::void_method_signature(), 1069 CHECK); 1070 } 1071 } 1072 1073 static void reset_vm_info_property(TRAPS) { 1074 // the vm info string 1075 ResourceMark rm(THREAD); 1076 const char *vm_info = VM_Version::vm_info_string(); 1077 1078 // java.lang.System class 1079 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1080 instanceKlassHandle klass (THREAD, k); 1081 1082 // setProperty arguments 1083 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1084 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1085 1086 // return value 1087 JavaValue r(T_OBJECT); 1088 1089 // public static String setProperty(String key, String value); 1090 JavaCalls::call_static(&r, 1091 klass, 1092 vmSymbols::setProperty_name(), 1093 vmSymbols::string_string_string_signature(), 1094 key_str, 1095 value_str, 1096 CHECK); 1097 } 1098 1099 1100 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1101 bool daemon, TRAPS) { 1102 assert(thread_group.not_null(), "thread group should be specified"); 1103 assert(threadObj() == NULL, "should only create Java thread object once"); 1104 1105 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1106 instanceKlassHandle klass (THREAD, k); 1107 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1108 1109 java_lang_Thread::set_thread(thread_oop(), this); 1110 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1111 set_threadObj(thread_oop()); 1112 1113 JavaValue result(T_VOID); 1114 if (thread_name != NULL) { 1115 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1116 // Thread gets assigned specified name and null target 1117 JavaCalls::call_special(&result, 1118 thread_oop, 1119 klass, 1120 vmSymbols::object_initializer_name(), 1121 vmSymbols::threadgroup_string_void_signature(), 1122 thread_group, // Argument 1 1123 name, // Argument 2 1124 THREAD); 1125 } else { 1126 // Thread gets assigned name "Thread-nnn" and null target 1127 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1128 JavaCalls::call_special(&result, 1129 thread_oop, 1130 klass, 1131 vmSymbols::object_initializer_name(), 1132 vmSymbols::threadgroup_runnable_void_signature(), 1133 thread_group, // Argument 1 1134 Handle(), // Argument 2 1135 THREAD); 1136 } 1137 1138 1139 if (daemon) { 1140 java_lang_Thread::set_daemon(thread_oop()); 1141 } 1142 1143 if (HAS_PENDING_EXCEPTION) { 1144 return; 1145 } 1146 1147 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass()); 1148 Handle threadObj(THREAD, this->threadObj()); 1149 1150 JavaCalls::call_special(&result, 1151 thread_group, 1152 group, 1153 vmSymbols::add_method_name(), 1154 vmSymbols::thread_void_signature(), 1155 threadObj, // Arg 1 1156 THREAD); 1157 } 1158 1159 // NamedThread -- non-JavaThread subclasses with multiple 1160 // uniquely named instances should derive from this. 1161 NamedThread::NamedThread() : Thread() { 1162 _name = NULL; 1163 _processed_thread = NULL; 1164 _gc_id = GCId::undefined(); 1165 } 1166 1167 NamedThread::~NamedThread() { 1168 if (_name != NULL) { 1169 FREE_C_HEAP_ARRAY(char, _name); 1170 _name = NULL; 1171 } 1172 } 1173 1174 void NamedThread::set_name(const char* format, ...) { 1175 guarantee(_name == NULL, "Only get to set name once."); 1176 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1177 guarantee(_name != NULL, "alloc failure"); 1178 va_list ap; 1179 va_start(ap, format); 1180 jio_vsnprintf(_name, max_name_len, format, ap); 1181 va_end(ap); 1182 } 1183 1184 void NamedThread::initialize_named_thread() { 1185 set_native_thread_name(name()); 1186 } 1187 1188 void NamedThread::print_on(outputStream* st) const { 1189 st->print("\"%s\" ", name()); 1190 Thread::print_on(st); 1191 st->cr(); 1192 } 1193 1194 1195 // ======= WatcherThread ======== 1196 1197 // The watcher thread exists to simulate timer interrupts. It should 1198 // be replaced by an abstraction over whatever native support for 1199 // timer interrupts exists on the platform. 1200 1201 WatcherThread* WatcherThread::_watcher_thread = NULL; 1202 bool WatcherThread::_startable = false; 1203 volatile bool WatcherThread::_should_terminate = false; 1204 1205 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1206 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1207 if (os::create_thread(this, os::watcher_thread)) { 1208 _watcher_thread = this; 1209 1210 // WatcherThread needs GCLAB for cases when it writes to Java heap, 1211 // and needs the space to evacuate. Have to initialize here, because 1212 // WatcherThread is initialized before the Universe. 1213 if (UseShenandoahGC && UseTLAB) { 1214 gclab().initialize(true); 1215 } 1216 1217 // Set the watcher thread to the highest OS priority which should not be 1218 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1219 // is created. The only normal thread using this priority is the reference 1220 // handler thread, which runs for very short intervals only. 1221 // If the VMThread's priority is not lower than the WatcherThread profiling 1222 // will be inaccurate. 1223 os::set_priority(this, MaxPriority); 1224 if (!DisableStartThread) { 1225 os::start_thread(this); 1226 } 1227 } 1228 } 1229 1230 int WatcherThread::sleep() const { 1231 // The WatcherThread does not participate in the safepoint protocol 1232 // for the PeriodicTask_lock because it is not a JavaThread. 1233 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1234 1235 if (_should_terminate) { 1236 // check for termination before we do any housekeeping or wait 1237 return 0; // we did not sleep. 1238 } 1239 1240 // remaining will be zero if there are no tasks, 1241 // causing the WatcherThread to sleep until a task is 1242 // enrolled 1243 int remaining = PeriodicTask::time_to_wait(); 1244 int time_slept = 0; 1245 1246 // we expect this to timeout - we only ever get unparked when 1247 // we should terminate or when a new task has been enrolled 1248 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1249 1250 jlong time_before_loop = os::javaTimeNanos(); 1251 1252 while (true) { 1253 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1254 remaining); 1255 jlong now = os::javaTimeNanos(); 1256 1257 if (remaining == 0) { 1258 // if we didn't have any tasks we could have waited for a long time 1259 // consider the time_slept zero and reset time_before_loop 1260 time_slept = 0; 1261 time_before_loop = now; 1262 } else { 1263 // need to recalculate since we might have new tasks in _tasks 1264 time_slept = (int) ((now - time_before_loop) / 1000000); 1265 } 1266 1267 // Change to task list or spurious wakeup of some kind 1268 if (timedout || _should_terminate) { 1269 break; 1270 } 1271 1272 remaining = PeriodicTask::time_to_wait(); 1273 if (remaining == 0) { 1274 // Last task was just disenrolled so loop around and wait until 1275 // another task gets enrolled 1276 continue; 1277 } 1278 1279 remaining -= time_slept; 1280 if (remaining <= 0) { 1281 break; 1282 } 1283 } 1284 1285 return time_slept; 1286 } 1287 1288 void WatcherThread::run() { 1289 assert(this == watcher_thread(), "just checking"); 1290 1291 this->record_stack_base_and_size(); 1292 this->set_native_thread_name(this->name()); 1293 this->set_active_handles(JNIHandleBlock::allocate_block()); 1294 while (true) { 1295 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1296 assert(watcher_thread() == this, "thread consistency check"); 1297 1298 // Calculate how long it'll be until the next PeriodicTask work 1299 // should be done, and sleep that amount of time. 1300 int time_waited = sleep(); 1301 1302 if (is_error_reported()) { 1303 // A fatal error has happened, the error handler(VMError::report_and_die) 1304 // should abort JVM after creating an error log file. However in some 1305 // rare cases, the error handler itself might deadlock. Here we try to 1306 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1307 // 1308 // This code is in WatcherThread because WatcherThread wakes up 1309 // periodically so the fatal error handler doesn't need to do anything; 1310 // also because the WatcherThread is less likely to crash than other 1311 // threads. 1312 1313 for (;;) { 1314 if (!ShowMessageBoxOnError 1315 && (OnError == NULL || OnError[0] == '\0') 1316 && Arguments::abort_hook() == NULL) { 1317 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds 1318 fdStream err(defaultStream::output_fd()); 1319 err.print_raw_cr("# [ timer expired, abort... ]"); 1320 // skip atexit/vm_exit/vm_abort hooks 1321 os::die(); 1322 } 1323 1324 // Wake up 5 seconds later, the fatal handler may reset OnError or 1325 // ShowMessageBoxOnError when it is ready to abort. 1326 os::sleep(this, 5 * 1000, false); 1327 } 1328 } 1329 1330 if (_should_terminate) { 1331 // check for termination before posting the next tick 1332 break; 1333 } 1334 1335 PeriodicTask::real_time_tick(time_waited); 1336 } 1337 1338 // Signal that it is terminated 1339 { 1340 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1341 _watcher_thread = NULL; 1342 Terminator_lock->notify(); 1343 } 1344 } 1345 1346 void WatcherThread::start() { 1347 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1348 1349 if (watcher_thread() == NULL && _startable) { 1350 _should_terminate = false; 1351 // Create the single instance of WatcherThread 1352 new WatcherThread(); 1353 } 1354 } 1355 1356 void WatcherThread::make_startable() { 1357 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1358 _startable = true; 1359 } 1360 1361 void WatcherThread::stop() { 1362 { 1363 // Follow normal safepoint aware lock enter protocol since the 1364 // WatcherThread is stopped by another JavaThread. 1365 MutexLocker ml(PeriodicTask_lock); 1366 _should_terminate = true; 1367 1368 WatcherThread* watcher = watcher_thread(); 1369 if (watcher != NULL) { 1370 // unpark the WatcherThread so it can see that it should terminate 1371 watcher->unpark(); 1372 } 1373 } 1374 1375 MutexLocker mu(Terminator_lock); 1376 1377 while (watcher_thread() != NULL) { 1378 // This wait should make safepoint checks, wait without a timeout, 1379 // and wait as a suspend-equivalent condition. 1380 // 1381 // Note: If the FlatProfiler is running, then this thread is waiting 1382 // for the WatcherThread to terminate and the WatcherThread, via the 1383 // FlatProfiler task, is waiting for the external suspend request on 1384 // this thread to complete. wait_for_ext_suspend_completion() will 1385 // eventually timeout, but that takes time. Making this wait a 1386 // suspend-equivalent condition solves that timeout problem. 1387 // 1388 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1389 Mutex::_as_suspend_equivalent_flag); 1390 } 1391 } 1392 1393 void WatcherThread::unpark() { 1394 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1395 PeriodicTask_lock->notify(); 1396 } 1397 1398 void WatcherThread::print_on(outputStream* st) const { 1399 st->print("\"%s\" ", name()); 1400 Thread::print_on(st); 1401 st->cr(); 1402 } 1403 1404 // ======= JavaThread ======== 1405 1406 #if INCLUDE_JVMCI 1407 1408 jlong* JavaThread::_jvmci_old_thread_counters; 1409 1410 bool jvmci_counters_include(JavaThread* thread) { 1411 oop threadObj = thread->threadObj(); 1412 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1413 } 1414 1415 void JavaThread::collect_counters(typeArrayOop array) { 1416 if (JVMCICounterSize > 0) { 1417 MutexLocker tl(Threads_lock); 1418 for (int i = 0; i < array->length(); i++) { 1419 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1420 } 1421 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1422 if (jvmci_counters_include(tp)) { 1423 for (int i = 0; i < array->length(); i++) { 1424 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1425 } 1426 } 1427 } 1428 } 1429 } 1430 1431 #endif // INCLUDE_JVMCI 1432 1433 // A JavaThread is a normal Java thread 1434 1435 void JavaThread::initialize() { 1436 // Initialize fields 1437 1438 set_saved_exception_pc(NULL); 1439 set_threadObj(NULL); 1440 _anchor.clear(); 1441 set_entry_point(NULL); 1442 set_jni_functions(jni_functions()); 1443 set_callee_target(NULL); 1444 set_vm_result(NULL); 1445 set_vm_result_2(NULL); 1446 set_vframe_array_head(NULL); 1447 set_vframe_array_last(NULL); 1448 set_deferred_locals(NULL); 1449 set_deopt_mark(NULL); 1450 set_deopt_compiled_method(NULL); 1451 clear_must_deopt_id(); 1452 set_monitor_chunks(NULL); 1453 set_next(NULL); 1454 set_thread_state(_thread_new); 1455 _terminated = _not_terminated; 1456 _privileged_stack_top = NULL; 1457 _array_for_gc = NULL; 1458 _suspend_equivalent = false; 1459 _in_deopt_handler = 0; 1460 _doing_unsafe_access = false; 1461 _stack_guard_state = stack_guard_unused; 1462 #if INCLUDE_JVMCI 1463 _pending_monitorenter = false; 1464 _pending_deoptimization = -1; 1465 _pending_failed_speculation = NULL; 1466 _pending_transfer_to_interpreter = false; 1467 _adjusting_comp_level = false; 1468 _jvmci._alternate_call_target = NULL; 1469 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1470 if (JVMCICounterSize > 0) { 1471 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1472 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1473 } else { 1474 _jvmci_counters = NULL; 1475 } 1476 #endif // INCLUDE_JVMCI 1477 _reserved_stack_activation = NULL; // stack base not known yet 1478 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1479 _exception_pc = 0; 1480 _exception_handler_pc = 0; 1481 _is_method_handle_return = 0; 1482 _jvmti_thread_state= NULL; 1483 _should_post_on_exceptions_flag = JNI_FALSE; 1484 _jvmti_get_loaded_classes_closure = NULL; 1485 _interp_only_mode = 0; 1486 _special_runtime_exit_condition = _no_async_condition; 1487 _pending_async_exception = NULL; 1488 _thread_stat = NULL; 1489 _thread_stat = new ThreadStatistics(); 1490 _blocked_on_compilation = false; 1491 _jni_active_critical = 0; 1492 _pending_jni_exception_check_fn = NULL; 1493 _do_not_unlock_if_synchronized = false; 1494 _cached_monitor_info = NULL; 1495 _parker = Parker::Allocate(this); 1496 1497 #ifndef PRODUCT 1498 _jmp_ring_index = 0; 1499 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1500 record_jump(NULL, NULL, NULL, 0); 1501 } 1502 #endif // PRODUCT 1503 1504 set_thread_profiler(NULL); 1505 if (FlatProfiler::is_active()) { 1506 // This is where we would decide to either give each thread it's own profiler 1507 // or use one global one from FlatProfiler, 1508 // or up to some count of the number of profiled threads, etc. 1509 ThreadProfiler* pp = new ThreadProfiler(); 1510 pp->engage(); 1511 set_thread_profiler(pp); 1512 } 1513 1514 // Setup safepoint state info for this thread 1515 ThreadSafepointState::create(this); 1516 1517 debug_only(_java_call_counter = 0); 1518 1519 // JVMTI PopFrame support 1520 _popframe_condition = popframe_inactive; 1521 _popframe_preserved_args = NULL; 1522 _popframe_preserved_args_size = 0; 1523 _frames_to_pop_failed_realloc = 0; 1524 1525 pd_initialize(); 1526 } 1527 1528 #if INCLUDE_ALL_GCS 1529 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1530 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1531 bool JavaThread::_evacuation_in_progress_global = false; 1532 #endif // INCLUDE_ALL_GCS 1533 1534 JavaThread::JavaThread(bool is_attaching_via_jni) : 1535 Thread() 1536 #if INCLUDE_ALL_GCS 1537 , _satb_mark_queue(&_satb_mark_queue_set), 1538 _dirty_card_queue(&_dirty_card_queue_set), 1539 _evacuation_in_progress(_evacuation_in_progress_global) 1540 #endif // INCLUDE_ALL_GCS 1541 { 1542 initialize(); 1543 if (is_attaching_via_jni) { 1544 _jni_attach_state = _attaching_via_jni; 1545 } else { 1546 _jni_attach_state = _not_attaching_via_jni; 1547 } 1548 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1549 } 1550 1551 bool JavaThread::reguard_stack(address cur_sp) { 1552 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1553 && _stack_guard_state != stack_guard_reserved_disabled) { 1554 return true; // Stack already guarded or guard pages not needed. 1555 } 1556 1557 if (register_stack_overflow()) { 1558 // For those architectures which have separate register and 1559 // memory stacks, we must check the register stack to see if 1560 // it has overflowed. 1561 return false; 1562 } 1563 1564 // Java code never executes within the yellow zone: the latter is only 1565 // there to provoke an exception during stack banging. If java code 1566 // is executing there, either StackShadowPages should be larger, or 1567 // some exception code in c1, c2 or the interpreter isn't unwinding 1568 // when it should. 1569 guarantee(cur_sp > stack_reserved_zone_base(), 1570 "not enough space to reguard - increase StackShadowPages"); 1571 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1572 enable_stack_yellow_reserved_zone(); 1573 if (reserved_stack_activation() != stack_base()) { 1574 set_reserved_stack_activation(stack_base()); 1575 } 1576 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1577 set_reserved_stack_activation(stack_base()); 1578 enable_stack_reserved_zone(); 1579 } 1580 return true; 1581 } 1582 1583 bool JavaThread::reguard_stack(void) { 1584 return reguard_stack(os::current_stack_pointer()); 1585 } 1586 1587 1588 void JavaThread::block_if_vm_exited() { 1589 if (_terminated == _vm_exited) { 1590 // _vm_exited is set at safepoint, and Threads_lock is never released 1591 // we will block here forever 1592 Threads_lock->lock_without_safepoint_check(); 1593 ShouldNotReachHere(); 1594 } 1595 } 1596 1597 1598 // Remove this ifdef when C1 is ported to the compiler interface. 1599 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1600 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1601 1602 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1603 Thread() 1604 #if INCLUDE_ALL_GCS 1605 , _satb_mark_queue(&_satb_mark_queue_set), 1606 _dirty_card_queue(&_dirty_card_queue_set), 1607 _evacuation_in_progress(_evacuation_in_progress_global) 1608 #endif // INCLUDE_ALL_GCS 1609 { 1610 initialize(); 1611 _jni_attach_state = _not_attaching_via_jni; 1612 set_entry_point(entry_point); 1613 // Create the native thread itself. 1614 // %note runtime_23 1615 os::ThreadType thr_type = os::java_thread; 1616 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1617 os::java_thread; 1618 os::create_thread(this, thr_type, stack_sz); 1619 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1620 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1621 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1622 // the exception consists of creating the exception object & initializing it, initialization 1623 // will leave the VM via a JavaCall and then all locks must be unlocked). 1624 // 1625 // The thread is still suspended when we reach here. Thread must be explicit started 1626 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1627 // by calling Threads:add. The reason why this is not done here, is because the thread 1628 // object must be fully initialized (take a look at JVM_Start) 1629 } 1630 1631 JavaThread::~JavaThread() { 1632 1633 // JSR166 -- return the parker to the free list 1634 Parker::Release(_parker); 1635 _parker = NULL; 1636 1637 // Free any remaining previous UnrollBlock 1638 vframeArray* old_array = vframe_array_last(); 1639 1640 if (old_array != NULL) { 1641 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1642 old_array->set_unroll_block(NULL); 1643 delete old_info; 1644 delete old_array; 1645 } 1646 1647 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1648 if (deferred != NULL) { 1649 // This can only happen if thread is destroyed before deoptimization occurs. 1650 assert(deferred->length() != 0, "empty array!"); 1651 do { 1652 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1653 deferred->remove_at(0); 1654 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1655 delete dlv; 1656 } while (deferred->length() != 0); 1657 delete deferred; 1658 } 1659 1660 // All Java related clean up happens in exit 1661 ThreadSafepointState::destroy(this); 1662 if (_thread_profiler != NULL) delete _thread_profiler; 1663 if (_thread_stat != NULL) delete _thread_stat; 1664 1665 #if INCLUDE_JVMCI 1666 if (JVMCICounterSize > 0) { 1667 if (jvmci_counters_include(this)) { 1668 for (int i = 0; i < JVMCICounterSize; i++) { 1669 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1670 } 1671 } 1672 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1673 } 1674 #endif // INCLUDE_JVMCI 1675 } 1676 1677 1678 // The first routine called by a new Java thread 1679 void JavaThread::run() { 1680 // initialize thread-local alloc buffer related fields 1681 this->initialize_tlab(); 1682 1683 // used to test validity of stack trace backs 1684 this->record_base_of_stack_pointer(); 1685 1686 // Record real stack base and size. 1687 this->record_stack_base_and_size(); 1688 1689 this->create_stack_guard_pages(); 1690 1691 this->cache_global_variables(); 1692 1693 // Thread is now sufficient initialized to be handled by the safepoint code as being 1694 // in the VM. Change thread state from _thread_new to _thread_in_vm 1695 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1696 1697 assert(JavaThread::current() == this, "sanity check"); 1698 assert(!Thread::current()->owns_locks(), "sanity check"); 1699 1700 DTRACE_THREAD_PROBE(start, this); 1701 1702 // This operation might block. We call that after all safepoint checks for a new thread has 1703 // been completed. 1704 this->set_active_handles(JNIHandleBlock::allocate_block()); 1705 1706 if (JvmtiExport::should_post_thread_life()) { 1707 JvmtiExport::post_thread_start(this); 1708 } 1709 1710 EventThreadStart event; 1711 if (event.should_commit()) { 1712 event.set_thread(THREAD_TRACE_ID(this)); 1713 event.commit(); 1714 } 1715 1716 // We call another function to do the rest so we are sure that the stack addresses used 1717 // from there will be lower than the stack base just computed 1718 thread_main_inner(); 1719 1720 // Note, thread is no longer valid at this point! 1721 } 1722 1723 1724 void JavaThread::thread_main_inner() { 1725 assert(JavaThread::current() == this, "sanity check"); 1726 assert(this->threadObj() != NULL, "just checking"); 1727 1728 // Execute thread entry point unless this thread has a pending exception 1729 // or has been stopped before starting. 1730 // Note: Due to JVM_StopThread we can have pending exceptions already! 1731 if (!this->has_pending_exception() && 1732 !java_lang_Thread::is_stillborn(this->threadObj())) { 1733 { 1734 ResourceMark rm(this); 1735 this->set_native_thread_name(this->get_thread_name()); 1736 } 1737 HandleMark hm(this); 1738 this->entry_point()(this, this); 1739 } 1740 1741 DTRACE_THREAD_PROBE(stop, this); 1742 1743 this->exit(false); 1744 delete this; 1745 } 1746 1747 1748 static void ensure_join(JavaThread* thread) { 1749 // We do not need to grap the Threads_lock, since we are operating on ourself. 1750 Handle threadObj(thread, thread->threadObj()); 1751 assert(threadObj.not_null(), "java thread object must exist"); 1752 ObjectLocker lock(threadObj, thread); 1753 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1754 thread->clear_pending_exception(); 1755 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1756 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1757 // Clear the native thread instance - this makes isAlive return false and allows the join() 1758 // to complete once we've done the notify_all below 1759 java_lang_Thread::set_thread(threadObj(), NULL); 1760 lock.notify_all(thread); 1761 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1762 thread->clear_pending_exception(); 1763 } 1764 1765 1766 // For any new cleanup additions, please check to see if they need to be applied to 1767 // cleanup_failed_attach_current_thread as well. 1768 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1769 assert(this == JavaThread::current(), "thread consistency check"); 1770 1771 HandleMark hm(this); 1772 Handle uncaught_exception(this, this->pending_exception()); 1773 this->clear_pending_exception(); 1774 Handle threadObj(this, this->threadObj()); 1775 assert(threadObj.not_null(), "Java thread object should be created"); 1776 1777 if (get_thread_profiler() != NULL) { 1778 get_thread_profiler()->disengage(); 1779 ResourceMark rm; 1780 get_thread_profiler()->print(get_thread_name()); 1781 } 1782 1783 1784 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1785 { 1786 EXCEPTION_MARK; 1787 1788 CLEAR_PENDING_EXCEPTION; 1789 } 1790 if (!destroy_vm) { 1791 if (uncaught_exception.not_null()) { 1792 EXCEPTION_MARK; 1793 // Call method Thread.dispatchUncaughtException(). 1794 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1795 JavaValue result(T_VOID); 1796 JavaCalls::call_virtual(&result, 1797 threadObj, thread_klass, 1798 vmSymbols::dispatchUncaughtException_name(), 1799 vmSymbols::throwable_void_signature(), 1800 uncaught_exception, 1801 THREAD); 1802 if (HAS_PENDING_EXCEPTION) { 1803 ResourceMark rm(this); 1804 jio_fprintf(defaultStream::error_stream(), 1805 "\nException: %s thrown from the UncaughtExceptionHandler" 1806 " in thread \"%s\"\n", 1807 pending_exception()->klass()->external_name(), 1808 get_thread_name()); 1809 CLEAR_PENDING_EXCEPTION; 1810 } 1811 } 1812 1813 // Called before the java thread exit since we want to read info 1814 // from java_lang_Thread object 1815 EventThreadEnd event; 1816 if (event.should_commit()) { 1817 event.set_thread(THREAD_TRACE_ID(this)); 1818 event.commit(); 1819 } 1820 1821 // Call after last event on thread 1822 EVENT_THREAD_EXIT(this); 1823 1824 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1825 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1826 // is deprecated anyhow. 1827 if (!is_Compiler_thread()) { 1828 int count = 3; 1829 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1830 EXCEPTION_MARK; 1831 JavaValue result(T_VOID); 1832 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1833 JavaCalls::call_virtual(&result, 1834 threadObj, thread_klass, 1835 vmSymbols::exit_method_name(), 1836 vmSymbols::void_method_signature(), 1837 THREAD); 1838 CLEAR_PENDING_EXCEPTION; 1839 } 1840 } 1841 // notify JVMTI 1842 if (JvmtiExport::should_post_thread_life()) { 1843 JvmtiExport::post_thread_end(this); 1844 } 1845 1846 // We have notified the agents that we are exiting, before we go on, 1847 // we must check for a pending external suspend request and honor it 1848 // in order to not surprise the thread that made the suspend request. 1849 while (true) { 1850 { 1851 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1852 if (!is_external_suspend()) { 1853 set_terminated(_thread_exiting); 1854 ThreadService::current_thread_exiting(this); 1855 break; 1856 } 1857 // Implied else: 1858 // Things get a little tricky here. We have a pending external 1859 // suspend request, but we are holding the SR_lock so we 1860 // can't just self-suspend. So we temporarily drop the lock 1861 // and then self-suspend. 1862 } 1863 1864 ThreadBlockInVM tbivm(this); 1865 java_suspend_self(); 1866 1867 // We're done with this suspend request, but we have to loop around 1868 // and check again. Eventually we will get SR_lock without a pending 1869 // external suspend request and will be able to mark ourselves as 1870 // exiting. 1871 } 1872 // no more external suspends are allowed at this point 1873 } else { 1874 // before_exit() has already posted JVMTI THREAD_END events 1875 } 1876 1877 // Notify waiters on thread object. This has to be done after exit() is called 1878 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1879 // group should have the destroyed bit set before waiters are notified). 1880 ensure_join(this); 1881 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1882 1883 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1884 // held by this thread must be released. The spec does not distinguish 1885 // between JNI-acquired and regular Java monitors. We can only see 1886 // regular Java monitors here if monitor enter-exit matching is broken. 1887 // 1888 // Optionally release any monitors for regular JavaThread exits. This 1889 // is provided as a work around for any bugs in monitor enter-exit 1890 // matching. This can be expensive so it is not enabled by default. 1891 // 1892 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1893 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1894 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1895 // Sanity check even though JNI DetachCurrentThread() would have 1896 // returned JNI_ERR if there was a Java frame. JavaThread exit 1897 // should be done executing Java code by the time we get here. 1898 assert(!this->has_last_Java_frame(), 1899 "should not have a Java frame when detaching or exiting"); 1900 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1901 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1902 } 1903 1904 // These things needs to be done while we are still a Java Thread. Make sure that thread 1905 // is in a consistent state, in case GC happens 1906 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1907 1908 if (active_handles() != NULL) { 1909 JNIHandleBlock* block = active_handles(); 1910 set_active_handles(NULL); 1911 JNIHandleBlock::release_block(block); 1912 } 1913 1914 if (free_handle_block() != NULL) { 1915 JNIHandleBlock* block = free_handle_block(); 1916 set_free_handle_block(NULL); 1917 JNIHandleBlock::release_block(block); 1918 } 1919 1920 // These have to be removed while this is still a valid thread. 1921 remove_stack_guard_pages(); 1922 1923 if (UseTLAB) { 1924 tlab().make_parsable(true); // retire TLAB 1925 } 1926 1927 if (JvmtiEnv::environments_might_exist()) { 1928 JvmtiExport::cleanup_thread(this); 1929 } 1930 1931 // We must flush any deferred card marks before removing a thread from 1932 // the list of active threads. 1933 Universe::heap()->flush_deferred_store_barrier(this); 1934 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1935 1936 #if INCLUDE_ALL_GCS 1937 // We must flush the G1-related buffers before removing a thread 1938 // from the list of active threads. We must do this after any deferred 1939 // card marks have been flushed (above) so that any entries that are 1940 // added to the thread's dirty card queue as a result are not lost. 1941 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) { 1942 flush_barrier_queues(); 1943 } 1944 if (UseShenandoahGC && UseTLAB) { 1945 gclab().make_parsable(true); 1946 } 1947 #endif // INCLUDE_ALL_GCS 1948 1949 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1950 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1951 os::current_thread_id()); 1952 1953 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1954 Threads::remove(this); 1955 } 1956 1957 #if INCLUDE_ALL_GCS 1958 // Flush G1-related queues. 1959 void JavaThread::flush_barrier_queues() { 1960 satb_mark_queue().flush(); 1961 dirty_card_queue().flush(); 1962 } 1963 1964 void JavaThread::initialize_queues() { 1965 assert(!SafepointSynchronize::is_at_safepoint(), 1966 "we should not be at a safepoint"); 1967 1968 SATBMarkQueue& satb_queue = satb_mark_queue(); 1969 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1970 // The SATB queue should have been constructed with its active 1971 // field set to false. 1972 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1973 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1974 // If we are creating the thread during a marking cycle, we should 1975 // set the active field of the SATB queue to true. 1976 if (satb_queue_set.is_active()) { 1977 satb_queue.set_active(true); 1978 } 1979 1980 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1981 // The dirty card queue should have been constructed with its 1982 // active field set to true. 1983 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1984 1985 _evacuation_in_progress = _evacuation_in_progress_global; 1986 } 1987 1988 bool JavaThread::evacuation_in_progress() const { 1989 return _evacuation_in_progress; 1990 } 1991 1992 void JavaThread::set_evacuation_in_progress(bool in_prog) { 1993 _evacuation_in_progress = in_prog; 1994 } 1995 1996 void JavaThread::set_evacuation_in_progress_all_threads(bool in_prog) { 1997 assert_locked_or_safepoint(Threads_lock); 1998 _evacuation_in_progress_global = in_prog; 1999 for (JavaThread* t = Threads::first(); t != NULL; t = t->next()) { 2000 t->set_evacuation_in_progress(in_prog); 2001 } 2002 } 2003 #endif // INCLUDE_ALL_GCS 2004 2005 void JavaThread::cleanup_failed_attach_current_thread() { 2006 if (get_thread_profiler() != NULL) { 2007 get_thread_profiler()->disengage(); 2008 ResourceMark rm; 2009 get_thread_profiler()->print(get_thread_name()); 2010 } 2011 2012 if (active_handles() != NULL) { 2013 JNIHandleBlock* block = active_handles(); 2014 set_active_handles(NULL); 2015 JNIHandleBlock::release_block(block); 2016 } 2017 2018 if (free_handle_block() != NULL) { 2019 JNIHandleBlock* block = free_handle_block(); 2020 set_free_handle_block(NULL); 2021 JNIHandleBlock::release_block(block); 2022 } 2023 2024 // These have to be removed while this is still a valid thread. 2025 remove_stack_guard_pages(); 2026 2027 if (UseTLAB) { 2028 tlab().make_parsable(true); // retire TLAB, if any 2029 } 2030 2031 #if INCLUDE_ALL_GCS 2032 if (UseG1GC || (UseShenandoahGC && ShenandoahWriteBarrier)) { 2033 flush_barrier_queues(); 2034 } 2035 if (UseShenandoahGC && UseTLAB) { 2036 gclab().make_parsable(true); 2037 } 2038 #endif // INCLUDE_ALL_GCS 2039 2040 Threads::remove(this); 2041 delete this; 2042 } 2043 2044 2045 2046 2047 JavaThread* JavaThread::active() { 2048 Thread* thread = Thread::current(); 2049 if (thread->is_Java_thread()) { 2050 return (JavaThread*) thread; 2051 } else { 2052 assert(thread->is_VM_thread(), "this must be a vm thread"); 2053 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2054 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2055 assert(ret->is_Java_thread(), "must be a Java thread"); 2056 return ret; 2057 } 2058 } 2059 2060 bool JavaThread::is_lock_owned(address adr) const { 2061 if (Thread::is_lock_owned(adr)) return true; 2062 2063 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2064 if (chunk->contains(adr)) return true; 2065 } 2066 2067 return false; 2068 } 2069 2070 2071 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2072 chunk->set_next(monitor_chunks()); 2073 set_monitor_chunks(chunk); 2074 } 2075 2076 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2077 guarantee(monitor_chunks() != NULL, "must be non empty"); 2078 if (monitor_chunks() == chunk) { 2079 set_monitor_chunks(chunk->next()); 2080 } else { 2081 MonitorChunk* prev = monitor_chunks(); 2082 while (prev->next() != chunk) prev = prev->next(); 2083 prev->set_next(chunk->next()); 2084 } 2085 } 2086 2087 // JVM support. 2088 2089 // Note: this function shouldn't block if it's called in 2090 // _thread_in_native_trans state (such as from 2091 // check_special_condition_for_native_trans()). 2092 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2093 2094 if (has_last_Java_frame() && has_async_condition()) { 2095 // If we are at a polling page safepoint (not a poll return) 2096 // then we must defer async exception because live registers 2097 // will be clobbered by the exception path. Poll return is 2098 // ok because the call we a returning from already collides 2099 // with exception handling registers and so there is no issue. 2100 // (The exception handling path kills call result registers but 2101 // this is ok since the exception kills the result anyway). 2102 2103 if (is_at_poll_safepoint()) { 2104 // if the code we are returning to has deoptimized we must defer 2105 // the exception otherwise live registers get clobbered on the 2106 // exception path before deoptimization is able to retrieve them. 2107 // 2108 RegisterMap map(this, false); 2109 frame caller_fr = last_frame().sender(&map); 2110 assert(caller_fr.is_compiled_frame(), "what?"); 2111 if (caller_fr.is_deoptimized_frame()) { 2112 log_info(exceptions)("deferred async exception at compiled safepoint"); 2113 return; 2114 } 2115 } 2116 } 2117 2118 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2119 if (condition == _no_async_condition) { 2120 // Conditions have changed since has_special_runtime_exit_condition() 2121 // was called: 2122 // - if we were here only because of an external suspend request, 2123 // then that was taken care of above (or cancelled) so we are done 2124 // - if we were here because of another async request, then it has 2125 // been cleared between the has_special_runtime_exit_condition() 2126 // and now so again we are done 2127 return; 2128 } 2129 2130 // Check for pending async. exception 2131 if (_pending_async_exception != NULL) { 2132 // Only overwrite an already pending exception, if it is not a threadDeath. 2133 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2134 2135 // We cannot call Exceptions::_throw(...) here because we cannot block 2136 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2137 2138 if (log_is_enabled(Info, exceptions)) { 2139 ResourceMark rm; 2140 outputStream* logstream = Log(exceptions)::info_stream(); 2141 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2142 if (has_last_Java_frame()) { 2143 frame f = last_frame(); 2144 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2145 } 2146 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2147 } 2148 _pending_async_exception = NULL; 2149 clear_has_async_exception(); 2150 } 2151 } 2152 2153 if (check_unsafe_error && 2154 condition == _async_unsafe_access_error && !has_pending_exception()) { 2155 condition = _no_async_condition; // done 2156 switch (thread_state()) { 2157 case _thread_in_vm: { 2158 JavaThread* THREAD = this; 2159 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2160 } 2161 case _thread_in_native: { 2162 ThreadInVMfromNative tiv(this); 2163 JavaThread* THREAD = this; 2164 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2165 } 2166 case _thread_in_Java: { 2167 ThreadInVMfromJava tiv(this); 2168 JavaThread* THREAD = this; 2169 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2170 } 2171 default: 2172 ShouldNotReachHere(); 2173 } 2174 } 2175 2176 assert(condition == _no_async_condition || has_pending_exception() || 2177 (!check_unsafe_error && condition == _async_unsafe_access_error), 2178 "must have handled the async condition, if no exception"); 2179 } 2180 2181 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2182 // 2183 // Check for pending external suspend. Internal suspend requests do 2184 // not use handle_special_runtime_exit_condition(). 2185 // If JNIEnv proxies are allowed, don't self-suspend if the target 2186 // thread is not the current thread. In older versions of jdbx, jdbx 2187 // threads could call into the VM with another thread's JNIEnv so we 2188 // can be here operating on behalf of a suspended thread (4432884). 2189 bool do_self_suspend = is_external_suspend_with_lock(); 2190 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2191 // 2192 // Because thread is external suspended the safepoint code will count 2193 // thread as at a safepoint. This can be odd because we can be here 2194 // as _thread_in_Java which would normally transition to _thread_blocked 2195 // at a safepoint. We would like to mark the thread as _thread_blocked 2196 // before calling java_suspend_self like all other callers of it but 2197 // we must then observe proper safepoint protocol. (We can't leave 2198 // _thread_blocked with a safepoint in progress). However we can be 2199 // here as _thread_in_native_trans so we can't use a normal transition 2200 // constructor/destructor pair because they assert on that type of 2201 // transition. We could do something like: 2202 // 2203 // JavaThreadState state = thread_state(); 2204 // set_thread_state(_thread_in_vm); 2205 // { 2206 // ThreadBlockInVM tbivm(this); 2207 // java_suspend_self() 2208 // } 2209 // set_thread_state(_thread_in_vm_trans); 2210 // if (safepoint) block; 2211 // set_thread_state(state); 2212 // 2213 // but that is pretty messy. Instead we just go with the way the 2214 // code has worked before and note that this is the only path to 2215 // java_suspend_self that doesn't put the thread in _thread_blocked 2216 // mode. 2217 2218 frame_anchor()->make_walkable(this); 2219 java_suspend_self(); 2220 2221 // We might be here for reasons in addition to the self-suspend request 2222 // so check for other async requests. 2223 } 2224 2225 if (check_asyncs) { 2226 check_and_handle_async_exceptions(); 2227 } 2228 } 2229 2230 void JavaThread::send_thread_stop(oop java_throwable) { 2231 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2232 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2233 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2234 2235 // Do not throw asynchronous exceptions against the compiler thread 2236 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2237 if (!can_call_java()) return; 2238 2239 { 2240 // Actually throw the Throwable against the target Thread - however 2241 // only if there is no thread death exception installed already. 2242 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2243 // If the topmost frame is a runtime stub, then we are calling into 2244 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2245 // must deoptimize the caller before continuing, as the compiled exception handler table 2246 // may not be valid 2247 if (has_last_Java_frame()) { 2248 frame f = last_frame(); 2249 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2250 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2251 RegisterMap reg_map(this, UseBiasedLocking); 2252 frame compiled_frame = f.sender(®_map); 2253 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2254 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2255 } 2256 } 2257 } 2258 2259 // Set async. pending exception in thread. 2260 set_pending_async_exception(java_throwable); 2261 2262 if (log_is_enabled(Info, exceptions)) { 2263 ResourceMark rm; 2264 log_info(exceptions)("Pending Async. exception installed of type: %s", 2265 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2266 } 2267 // for AbortVMOnException flag 2268 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2269 } 2270 } 2271 2272 2273 // Interrupt thread so it will wake up from a potential wait() 2274 Thread::interrupt(this); 2275 } 2276 2277 // External suspension mechanism. 2278 // 2279 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2280 // to any VM_locks and it is at a transition 2281 // Self-suspension will happen on the transition out of the vm. 2282 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2283 // 2284 // Guarantees on return: 2285 // + Target thread will not execute any new bytecode (that's why we need to 2286 // force a safepoint) 2287 // + Target thread will not enter any new monitors 2288 // 2289 void JavaThread::java_suspend() { 2290 { MutexLocker mu(Threads_lock); 2291 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2292 return; 2293 } 2294 } 2295 2296 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2297 if (!is_external_suspend()) { 2298 // a racing resume has cancelled us; bail out now 2299 return; 2300 } 2301 2302 // suspend is done 2303 uint32_t debug_bits = 0; 2304 // Warning: is_ext_suspend_completed() may temporarily drop the 2305 // SR_lock to allow the thread to reach a stable thread state if 2306 // it is currently in a transient thread state. 2307 if (is_ext_suspend_completed(false /* !called_by_wait */, 2308 SuspendRetryDelay, &debug_bits)) { 2309 return; 2310 } 2311 } 2312 2313 VM_ForceSafepoint vm_suspend; 2314 VMThread::execute(&vm_suspend); 2315 } 2316 2317 // Part II of external suspension. 2318 // A JavaThread self suspends when it detects a pending external suspend 2319 // request. This is usually on transitions. It is also done in places 2320 // where continuing to the next transition would surprise the caller, 2321 // e.g., monitor entry. 2322 // 2323 // Returns the number of times that the thread self-suspended. 2324 // 2325 // Note: DO NOT call java_suspend_self() when you just want to block current 2326 // thread. java_suspend_self() is the second stage of cooperative 2327 // suspension for external suspend requests and should only be used 2328 // to complete an external suspend request. 2329 // 2330 int JavaThread::java_suspend_self() { 2331 int ret = 0; 2332 2333 // we are in the process of exiting so don't suspend 2334 if (is_exiting()) { 2335 clear_external_suspend(); 2336 return ret; 2337 } 2338 2339 assert(_anchor.walkable() || 2340 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2341 "must have walkable stack"); 2342 2343 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2344 2345 assert(!this->is_ext_suspended(), 2346 "a thread trying to self-suspend should not already be suspended"); 2347 2348 if (this->is_suspend_equivalent()) { 2349 // If we are self-suspending as a result of the lifting of a 2350 // suspend equivalent condition, then the suspend_equivalent 2351 // flag is not cleared until we set the ext_suspended flag so 2352 // that wait_for_ext_suspend_completion() returns consistent 2353 // results. 2354 this->clear_suspend_equivalent(); 2355 } 2356 2357 // A racing resume may have cancelled us before we grabbed SR_lock 2358 // above. Or another external suspend request could be waiting for us 2359 // by the time we return from SR_lock()->wait(). The thread 2360 // that requested the suspension may already be trying to walk our 2361 // stack and if we return now, we can change the stack out from under 2362 // it. This would be a "bad thing (TM)" and cause the stack walker 2363 // to crash. We stay self-suspended until there are no more pending 2364 // external suspend requests. 2365 while (is_external_suspend()) { 2366 ret++; 2367 this->set_ext_suspended(); 2368 2369 // _ext_suspended flag is cleared by java_resume() 2370 while (is_ext_suspended()) { 2371 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2372 } 2373 } 2374 2375 return ret; 2376 } 2377 2378 #ifdef ASSERT 2379 // verify the JavaThread has not yet been published in the Threads::list, and 2380 // hence doesn't need protection from concurrent access at this stage 2381 void JavaThread::verify_not_published() { 2382 if (!Threads_lock->owned_by_self()) { 2383 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2384 assert(!Threads::includes(this), 2385 "java thread shouldn't have been published yet!"); 2386 } else { 2387 assert(!Threads::includes(this), 2388 "java thread shouldn't have been published yet!"); 2389 } 2390 } 2391 #endif 2392 2393 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2394 // progress or when _suspend_flags is non-zero. 2395 // Current thread needs to self-suspend if there is a suspend request and/or 2396 // block if a safepoint is in progress. 2397 // Async exception ISN'T checked. 2398 // Note only the ThreadInVMfromNative transition can call this function 2399 // directly and when thread state is _thread_in_native_trans 2400 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2401 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2402 2403 JavaThread *curJT = JavaThread::current(); 2404 bool do_self_suspend = thread->is_external_suspend(); 2405 2406 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2407 2408 // If JNIEnv proxies are allowed, don't self-suspend if the target 2409 // thread is not the current thread. In older versions of jdbx, jdbx 2410 // threads could call into the VM with another thread's JNIEnv so we 2411 // can be here operating on behalf of a suspended thread (4432884). 2412 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2413 JavaThreadState state = thread->thread_state(); 2414 2415 // We mark this thread_blocked state as a suspend-equivalent so 2416 // that a caller to is_ext_suspend_completed() won't be confused. 2417 // The suspend-equivalent state is cleared by java_suspend_self(). 2418 thread->set_suspend_equivalent(); 2419 2420 // If the safepoint code sees the _thread_in_native_trans state, it will 2421 // wait until the thread changes to other thread state. There is no 2422 // guarantee on how soon we can obtain the SR_lock and complete the 2423 // self-suspend request. It would be a bad idea to let safepoint wait for 2424 // too long. Temporarily change the state to _thread_blocked to 2425 // let the VM thread know that this thread is ready for GC. The problem 2426 // of changing thread state is that safepoint could happen just after 2427 // java_suspend_self() returns after being resumed, and VM thread will 2428 // see the _thread_blocked state. We must check for safepoint 2429 // after restoring the state and make sure we won't leave while a safepoint 2430 // is in progress. 2431 thread->set_thread_state(_thread_blocked); 2432 thread->java_suspend_self(); 2433 thread->set_thread_state(state); 2434 // Make sure new state is seen by VM thread 2435 if (os::is_MP()) { 2436 if (UseMembar) { 2437 // Force a fence between the write above and read below 2438 OrderAccess::fence(); 2439 } else { 2440 // Must use this rather than serialization page in particular on Windows 2441 InterfaceSupport::serialize_memory(thread); 2442 } 2443 } 2444 } 2445 2446 if (SafepointSynchronize::do_call_back()) { 2447 // If we are safepointing, then block the caller which may not be 2448 // the same as the target thread (see above). 2449 SafepointSynchronize::block(curJT); 2450 } 2451 2452 if (thread->is_deopt_suspend()) { 2453 thread->clear_deopt_suspend(); 2454 RegisterMap map(thread, false); 2455 frame f = thread->last_frame(); 2456 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2457 f = f.sender(&map); 2458 } 2459 if (f.id() == thread->must_deopt_id()) { 2460 thread->clear_must_deopt_id(); 2461 f.deoptimize(thread); 2462 } else { 2463 fatal("missed deoptimization!"); 2464 } 2465 } 2466 } 2467 2468 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2469 // progress or when _suspend_flags is non-zero. 2470 // Current thread needs to self-suspend if there is a suspend request and/or 2471 // block if a safepoint is in progress. 2472 // Also check for pending async exception (not including unsafe access error). 2473 // Note only the native==>VM/Java barriers can call this function and when 2474 // thread state is _thread_in_native_trans. 2475 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2476 check_safepoint_and_suspend_for_native_trans(thread); 2477 2478 if (thread->has_async_exception()) { 2479 // We are in _thread_in_native_trans state, don't handle unsafe 2480 // access error since that may block. 2481 thread->check_and_handle_async_exceptions(false); 2482 } 2483 } 2484 2485 // This is a variant of the normal 2486 // check_special_condition_for_native_trans with slightly different 2487 // semantics for use by critical native wrappers. It does all the 2488 // normal checks but also performs the transition back into 2489 // thread_in_Java state. This is required so that critical natives 2490 // can potentially block and perform a GC if they are the last thread 2491 // exiting the GCLocker. 2492 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2493 check_special_condition_for_native_trans(thread); 2494 2495 // Finish the transition 2496 thread->set_thread_state(_thread_in_Java); 2497 2498 if (thread->do_critical_native_unlock()) { 2499 ThreadInVMfromJavaNoAsyncException tiv(thread); 2500 GCLocker::unlock_critical(thread); 2501 thread->clear_critical_native_unlock(); 2502 } 2503 } 2504 2505 // We need to guarantee the Threads_lock here, since resumes are not 2506 // allowed during safepoint synchronization 2507 // Can only resume from an external suspension 2508 void JavaThread::java_resume() { 2509 assert_locked_or_safepoint(Threads_lock); 2510 2511 // Sanity check: thread is gone, has started exiting or the thread 2512 // was not externally suspended. 2513 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2514 return; 2515 } 2516 2517 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2518 2519 clear_external_suspend(); 2520 2521 if (is_ext_suspended()) { 2522 clear_ext_suspended(); 2523 SR_lock()->notify_all(); 2524 } 2525 } 2526 2527 size_t JavaThread::_stack_red_zone_size = 0; 2528 size_t JavaThread::_stack_yellow_zone_size = 0; 2529 size_t JavaThread::_stack_reserved_zone_size = 0; 2530 size_t JavaThread::_stack_shadow_zone_size = 0; 2531 2532 void JavaThread::create_stack_guard_pages() { 2533 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2534 address low_addr = stack_end(); 2535 size_t len = stack_guard_zone_size(); 2536 2537 int must_commit = os::must_commit_stack_guard_pages(); 2538 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2539 2540 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2541 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2542 return; 2543 } 2544 2545 if (os::guard_memory((char *) low_addr, len)) { 2546 _stack_guard_state = stack_guard_enabled; 2547 } else { 2548 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2549 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2550 if (os::uncommit_memory((char *) low_addr, len)) { 2551 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2552 } 2553 return; 2554 } 2555 2556 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2557 PTR_FORMAT "-" PTR_FORMAT ".", 2558 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2559 } 2560 2561 void JavaThread::remove_stack_guard_pages() { 2562 assert(Thread::current() == this, "from different thread"); 2563 if (_stack_guard_state == stack_guard_unused) return; 2564 address low_addr = stack_end(); 2565 size_t len = stack_guard_zone_size(); 2566 2567 if (os::must_commit_stack_guard_pages()) { 2568 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2569 _stack_guard_state = stack_guard_unused; 2570 } else { 2571 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2572 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2573 return; 2574 } 2575 } else { 2576 if (_stack_guard_state == stack_guard_unused) return; 2577 if (os::unguard_memory((char *) low_addr, len)) { 2578 _stack_guard_state = stack_guard_unused; 2579 } else { 2580 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2581 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2582 return; 2583 } 2584 } 2585 2586 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2587 PTR_FORMAT "-" PTR_FORMAT ".", 2588 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2589 } 2590 2591 void JavaThread::enable_stack_reserved_zone() { 2592 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2593 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2594 2595 // The base notation is from the stack's point of view, growing downward. 2596 // We need to adjust it to work correctly with guard_memory() 2597 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2598 2599 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2600 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2601 2602 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2603 _stack_guard_state = stack_guard_enabled; 2604 } else { 2605 warning("Attempt to guard stack reserved zone failed."); 2606 } 2607 enable_register_stack_guard(); 2608 } 2609 2610 void JavaThread::disable_stack_reserved_zone() { 2611 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2612 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2613 2614 // Simply return if called for a thread that does not use guard pages. 2615 if (_stack_guard_state == stack_guard_unused) return; 2616 2617 // The base notation is from the stack's point of view, growing downward. 2618 // We need to adjust it to work correctly with guard_memory() 2619 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2620 2621 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2622 _stack_guard_state = stack_guard_reserved_disabled; 2623 } else { 2624 warning("Attempt to unguard stack reserved zone failed."); 2625 } 2626 disable_register_stack_guard(); 2627 } 2628 2629 void JavaThread::enable_stack_yellow_reserved_zone() { 2630 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2631 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2632 2633 // The base notation is from the stacks point of view, growing downward. 2634 // We need to adjust it to work correctly with guard_memory() 2635 address base = stack_red_zone_base(); 2636 2637 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2638 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2639 2640 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2641 _stack_guard_state = stack_guard_enabled; 2642 } else { 2643 warning("Attempt to guard stack yellow zone failed."); 2644 } 2645 enable_register_stack_guard(); 2646 } 2647 2648 void JavaThread::disable_stack_yellow_reserved_zone() { 2649 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2650 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2651 2652 // Simply return if called for a thread that does not use guard pages. 2653 if (_stack_guard_state == stack_guard_unused) return; 2654 2655 // The base notation is from the stacks point of view, growing downward. 2656 // We need to adjust it to work correctly with guard_memory() 2657 address base = stack_red_zone_base(); 2658 2659 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2660 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2661 } else { 2662 warning("Attempt to unguard stack yellow zone failed."); 2663 } 2664 disable_register_stack_guard(); 2665 } 2666 2667 void JavaThread::enable_stack_red_zone() { 2668 // The base notation is from the stacks point of view, growing downward. 2669 // We need to adjust it to work correctly with guard_memory() 2670 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2671 address base = stack_red_zone_base() - stack_red_zone_size(); 2672 2673 guarantee(base < stack_base(), "Error calculating stack red zone"); 2674 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2675 2676 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2677 warning("Attempt to guard stack red zone failed."); 2678 } 2679 } 2680 2681 void JavaThread::disable_stack_red_zone() { 2682 // The base notation is from the stacks point of view, growing downward. 2683 // We need to adjust it to work correctly with guard_memory() 2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2685 address base = stack_red_zone_base() - stack_red_zone_size(); 2686 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2687 warning("Attempt to unguard stack red zone failed."); 2688 } 2689 } 2690 2691 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2692 // ignore is there is no stack 2693 if (!has_last_Java_frame()) return; 2694 // traverse the stack frames. Starts from top frame. 2695 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2696 frame* fr = fst.current(); 2697 f(fr, fst.register_map()); 2698 } 2699 } 2700 2701 2702 #ifndef PRODUCT 2703 // Deoptimization 2704 // Function for testing deoptimization 2705 void JavaThread::deoptimize() { 2706 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2707 StackFrameStream fst(this, UseBiasedLocking); 2708 bool deopt = false; // Dump stack only if a deopt actually happens. 2709 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2710 // Iterate over all frames in the thread and deoptimize 2711 for (; !fst.is_done(); fst.next()) { 2712 if (fst.current()->can_be_deoptimized()) { 2713 2714 if (only_at) { 2715 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2716 // consists of comma or carriage return separated numbers so 2717 // search for the current bci in that string. 2718 address pc = fst.current()->pc(); 2719 nmethod* nm = (nmethod*) fst.current()->cb(); 2720 ScopeDesc* sd = nm->scope_desc_at(pc); 2721 char buffer[8]; 2722 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2723 size_t len = strlen(buffer); 2724 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2725 while (found != NULL) { 2726 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2727 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2728 // Check that the bci found is bracketed by terminators. 2729 break; 2730 } 2731 found = strstr(found + 1, buffer); 2732 } 2733 if (!found) { 2734 continue; 2735 } 2736 } 2737 2738 if (DebugDeoptimization && !deopt) { 2739 deopt = true; // One-time only print before deopt 2740 tty->print_cr("[BEFORE Deoptimization]"); 2741 trace_frames(); 2742 trace_stack(); 2743 } 2744 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2745 } 2746 } 2747 2748 if (DebugDeoptimization && deopt) { 2749 tty->print_cr("[AFTER Deoptimization]"); 2750 trace_frames(); 2751 } 2752 } 2753 2754 2755 // Make zombies 2756 void JavaThread::make_zombies() { 2757 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2758 if (fst.current()->can_be_deoptimized()) { 2759 // it is a Java nmethod 2760 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2761 nm->make_not_entrant(); 2762 } 2763 } 2764 } 2765 #endif // PRODUCT 2766 2767 2768 void JavaThread::deoptimized_wrt_marked_nmethods() { 2769 if (!has_last_Java_frame()) return; 2770 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2771 StackFrameStream fst(this, UseBiasedLocking); 2772 for (; !fst.is_done(); fst.next()) { 2773 if (fst.current()->should_be_deoptimized()) { 2774 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2775 } 2776 } 2777 } 2778 2779 2780 // If the caller is a NamedThread, then remember, in the current scope, 2781 // the given JavaThread in its _processed_thread field. 2782 class RememberProcessedThread: public StackObj { 2783 NamedThread* _cur_thr; 2784 public: 2785 RememberProcessedThread(JavaThread* jthr) { 2786 Thread* thread = Thread::current(); 2787 if (thread->is_Named_thread()) { 2788 _cur_thr = (NamedThread *)thread; 2789 _cur_thr->set_processed_thread(jthr); 2790 } else { 2791 _cur_thr = NULL; 2792 } 2793 } 2794 2795 ~RememberProcessedThread() { 2796 if (_cur_thr) { 2797 _cur_thr->set_processed_thread(NULL); 2798 } 2799 } 2800 }; 2801 2802 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2803 // Verify that the deferred card marks have been flushed. 2804 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2805 2806 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2807 // since there may be more than one thread using each ThreadProfiler. 2808 2809 // Traverse the GCHandles 2810 Thread::oops_do(f, cf); 2811 2812 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2813 2814 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2815 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2816 2817 if (has_last_Java_frame()) { 2818 // Record JavaThread to GC thread 2819 RememberProcessedThread rpt(this); 2820 2821 // Traverse the privileged stack 2822 if (_privileged_stack_top != NULL) { 2823 _privileged_stack_top->oops_do(f); 2824 } 2825 2826 // traverse the registered growable array 2827 if (_array_for_gc != NULL) { 2828 for (int index = 0; index < _array_for_gc->length(); index++) { 2829 f->do_oop(_array_for_gc->adr_at(index)); 2830 } 2831 } 2832 2833 // Traverse the monitor chunks 2834 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2835 chunk->oops_do(f); 2836 } 2837 2838 // Traverse the execution stack 2839 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2840 fst.current()->oops_do(f, cf, fst.register_map()); 2841 } 2842 } 2843 2844 // callee_target is never live across a gc point so NULL it here should 2845 // it still contain a methdOop. 2846 2847 set_callee_target(NULL); 2848 2849 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2850 // If we have deferred set_locals there might be oops waiting to be 2851 // written 2852 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2853 if (list != NULL) { 2854 for (int i = 0; i < list->length(); i++) { 2855 list->at(i)->oops_do(f); 2856 } 2857 } 2858 2859 // Traverse instance variables at the end since the GC may be moving things 2860 // around using this function 2861 f->do_oop((oop*) &_threadObj); 2862 f->do_oop((oop*) &_vm_result); 2863 f->do_oop((oop*) &_exception_oop); 2864 f->do_oop((oop*) &_pending_async_exception); 2865 2866 if (jvmti_thread_state() != NULL) { 2867 jvmti_thread_state()->oops_do(f); 2868 } 2869 } 2870 2871 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2872 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2873 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2874 2875 if (has_last_Java_frame()) { 2876 // Traverse the execution stack 2877 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2878 fst.current()->nmethods_do(cf); 2879 } 2880 } 2881 } 2882 2883 void JavaThread::metadata_do(void f(Metadata*)) { 2884 if (has_last_Java_frame()) { 2885 // Traverse the execution stack to call f() on the methods in the stack 2886 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2887 fst.current()->metadata_do(f); 2888 } 2889 } else if (is_Compiler_thread()) { 2890 // need to walk ciMetadata in current compile tasks to keep alive. 2891 CompilerThread* ct = (CompilerThread*)this; 2892 if (ct->env() != NULL) { 2893 ct->env()->metadata_do(f); 2894 } 2895 if (ct->task() != NULL) { 2896 ct->task()->metadata_do(f); 2897 } 2898 } 2899 } 2900 2901 // Printing 2902 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2903 switch (_thread_state) { 2904 case _thread_uninitialized: return "_thread_uninitialized"; 2905 case _thread_new: return "_thread_new"; 2906 case _thread_new_trans: return "_thread_new_trans"; 2907 case _thread_in_native: return "_thread_in_native"; 2908 case _thread_in_native_trans: return "_thread_in_native_trans"; 2909 case _thread_in_vm: return "_thread_in_vm"; 2910 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2911 case _thread_in_Java: return "_thread_in_Java"; 2912 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2913 case _thread_blocked: return "_thread_blocked"; 2914 case _thread_blocked_trans: return "_thread_blocked_trans"; 2915 default: return "unknown thread state"; 2916 } 2917 } 2918 2919 #ifndef PRODUCT 2920 void JavaThread::print_thread_state_on(outputStream *st) const { 2921 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2922 }; 2923 void JavaThread::print_thread_state() const { 2924 print_thread_state_on(tty); 2925 } 2926 #endif // PRODUCT 2927 2928 // Called by Threads::print() for VM_PrintThreads operation 2929 void JavaThread::print_on(outputStream *st) const { 2930 st->print_raw("\""); 2931 st->print_raw(get_thread_name()); 2932 st->print_raw("\" "); 2933 oop thread_oop = threadObj(); 2934 if (thread_oop != NULL) { 2935 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2936 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2937 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2938 } 2939 Thread::print_on(st); 2940 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2941 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2942 if (thread_oop != NULL) { 2943 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2944 } 2945 #ifndef PRODUCT 2946 print_thread_state_on(st); 2947 _safepoint_state->print_on(st); 2948 #endif // PRODUCT 2949 if (is_Compiler_thread()) { 2950 CompilerThread* ct = (CompilerThread*)this; 2951 if (ct->task() != NULL) { 2952 st->print(" Compiling: "); 2953 ct->task()->print(st, NULL, true, false); 2954 } else { 2955 st->print(" No compile task"); 2956 } 2957 st->cr(); 2958 } 2959 } 2960 2961 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2962 st->print("%s", get_thread_name_string(buf, buflen)); 2963 } 2964 2965 // Called by fatal error handler. The difference between this and 2966 // JavaThread::print() is that we can't grab lock or allocate memory. 2967 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2968 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2969 oop thread_obj = threadObj(); 2970 if (thread_obj != NULL) { 2971 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2972 } 2973 st->print(" ["); 2974 st->print("%s", _get_thread_state_name(_thread_state)); 2975 if (osthread()) { 2976 st->print(", id=%d", osthread()->thread_id()); 2977 } 2978 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2979 p2i(stack_end()), p2i(stack_base())); 2980 st->print("]"); 2981 return; 2982 } 2983 2984 // Verification 2985 2986 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2987 2988 void JavaThread::verify() { 2989 // Verify oops in the thread. 2990 oops_do(&VerifyOopClosure::verify_oop, NULL); 2991 2992 // Verify the stack frames. 2993 frames_do(frame_verify); 2994 } 2995 2996 // CR 6300358 (sub-CR 2137150) 2997 // Most callers of this method assume that it can't return NULL but a 2998 // thread may not have a name whilst it is in the process of attaching to 2999 // the VM - see CR 6412693, and there are places where a JavaThread can be 3000 // seen prior to having it's threadObj set (eg JNI attaching threads and 3001 // if vm exit occurs during initialization). These cases can all be accounted 3002 // for such that this method never returns NULL. 3003 const char* JavaThread::get_thread_name() const { 3004 #ifdef ASSERT 3005 // early safepoints can hit while current thread does not yet have TLS 3006 if (!SafepointSynchronize::is_at_safepoint()) { 3007 Thread *cur = Thread::current(); 3008 if (!(cur->is_Java_thread() && cur == this)) { 3009 // Current JavaThreads are allowed to get their own name without 3010 // the Threads_lock. 3011 assert_locked_or_safepoint(Threads_lock); 3012 } 3013 } 3014 #endif // ASSERT 3015 return get_thread_name_string(); 3016 } 3017 3018 // Returns a non-NULL representation of this thread's name, or a suitable 3019 // descriptive string if there is no set name 3020 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3021 const char* name_str; 3022 oop thread_obj = threadObj(); 3023 if (thread_obj != NULL) { 3024 oop name = java_lang_Thread::name(thread_obj); 3025 if (name != NULL) { 3026 if (buf == NULL) { 3027 name_str = java_lang_String::as_utf8_string(name); 3028 } else { 3029 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3030 } 3031 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3032 name_str = "<no-name - thread is attaching>"; 3033 } else { 3034 name_str = Thread::name(); 3035 } 3036 } else { 3037 name_str = Thread::name(); 3038 } 3039 assert(name_str != NULL, "unexpected NULL thread name"); 3040 return name_str; 3041 } 3042 3043 3044 const char* JavaThread::get_threadgroup_name() const { 3045 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3046 oop thread_obj = threadObj(); 3047 if (thread_obj != NULL) { 3048 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3049 if (thread_group != NULL) { 3050 // ThreadGroup.name can be null 3051 return java_lang_ThreadGroup::name(thread_group); 3052 } 3053 } 3054 return NULL; 3055 } 3056 3057 const char* JavaThread::get_parent_name() const { 3058 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3059 oop thread_obj = threadObj(); 3060 if (thread_obj != NULL) { 3061 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3062 if (thread_group != NULL) { 3063 oop parent = java_lang_ThreadGroup::parent(thread_group); 3064 if (parent != NULL) { 3065 // ThreadGroup.name can be null 3066 return java_lang_ThreadGroup::name(parent); 3067 } 3068 } 3069 } 3070 return NULL; 3071 } 3072 3073 ThreadPriority JavaThread::java_priority() const { 3074 oop thr_oop = threadObj(); 3075 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3076 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3077 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3078 return priority; 3079 } 3080 3081 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3082 3083 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3084 // Link Java Thread object <-> C++ Thread 3085 3086 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3087 // and put it into a new Handle. The Handle "thread_oop" can then 3088 // be used to pass the C++ thread object to other methods. 3089 3090 // Set the Java level thread object (jthread) field of the 3091 // new thread (a JavaThread *) to C++ thread object using the 3092 // "thread_oop" handle. 3093 3094 // Set the thread field (a JavaThread *) of the 3095 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3096 3097 Handle thread_oop(Thread::current(), 3098 JNIHandles::resolve_non_null(jni_thread)); 3099 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3100 "must be initialized"); 3101 set_threadObj(thread_oop()); 3102 java_lang_Thread::set_thread(thread_oop(), this); 3103 3104 if (prio == NoPriority) { 3105 prio = java_lang_Thread::priority(thread_oop()); 3106 assert(prio != NoPriority, "A valid priority should be present"); 3107 } 3108 3109 // Push the Java priority down to the native thread; needs Threads_lock 3110 Thread::set_priority(this, prio); 3111 3112 prepare_ext(); 3113 3114 // Add the new thread to the Threads list and set it in motion. 3115 // We must have threads lock in order to call Threads::add. 3116 // It is crucial that we do not block before the thread is 3117 // added to the Threads list for if a GC happens, then the java_thread oop 3118 // will not be visited by GC. 3119 Threads::add(this); 3120 } 3121 3122 oop JavaThread::current_park_blocker() { 3123 // Support for JSR-166 locks 3124 oop thread_oop = threadObj(); 3125 if (thread_oop != NULL && 3126 JDK_Version::current().supports_thread_park_blocker()) { 3127 return java_lang_Thread::park_blocker(thread_oop); 3128 } 3129 return NULL; 3130 } 3131 3132 3133 void JavaThread::print_stack_on(outputStream* st) { 3134 if (!has_last_Java_frame()) return; 3135 ResourceMark rm; 3136 HandleMark hm; 3137 3138 RegisterMap reg_map(this); 3139 vframe* start_vf = last_java_vframe(®_map); 3140 int count = 0; 3141 for (vframe* f = start_vf; f; f = f->sender()) { 3142 if (f->is_java_frame()) { 3143 javaVFrame* jvf = javaVFrame::cast(f); 3144 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3145 3146 // Print out lock information 3147 if (JavaMonitorsInStackTrace) { 3148 jvf->print_lock_info_on(st, count); 3149 } 3150 } else { 3151 // Ignore non-Java frames 3152 } 3153 3154 // Bail-out case for too deep stacks 3155 count++; 3156 if (MaxJavaStackTraceDepth == count) return; 3157 } 3158 } 3159 3160 3161 // JVMTI PopFrame support 3162 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3163 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3164 if (in_bytes(size_in_bytes) != 0) { 3165 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3166 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3167 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3168 } 3169 } 3170 3171 void* JavaThread::popframe_preserved_args() { 3172 return _popframe_preserved_args; 3173 } 3174 3175 ByteSize JavaThread::popframe_preserved_args_size() { 3176 return in_ByteSize(_popframe_preserved_args_size); 3177 } 3178 3179 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3180 int sz = in_bytes(popframe_preserved_args_size()); 3181 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3182 return in_WordSize(sz / wordSize); 3183 } 3184 3185 void JavaThread::popframe_free_preserved_args() { 3186 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3187 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3188 _popframe_preserved_args = NULL; 3189 _popframe_preserved_args_size = 0; 3190 } 3191 3192 #ifndef PRODUCT 3193 3194 void JavaThread::trace_frames() { 3195 tty->print_cr("[Describe stack]"); 3196 int frame_no = 1; 3197 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3198 tty->print(" %d. ", frame_no++); 3199 fst.current()->print_value_on(tty, this); 3200 tty->cr(); 3201 } 3202 } 3203 3204 class PrintAndVerifyOopClosure: public OopClosure { 3205 protected: 3206 template <class T> inline void do_oop_work(T* p) { 3207 oop obj = oopDesc::load_decode_heap_oop(p); 3208 if (obj == NULL) return; 3209 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3210 if (obj->is_oop_or_null()) { 3211 if (obj->is_objArray()) { 3212 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3213 } else { 3214 obj->print(); 3215 } 3216 } else { 3217 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3218 } 3219 tty->cr(); 3220 } 3221 public: 3222 virtual void do_oop(oop* p) { do_oop_work(p); } 3223 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3224 }; 3225 3226 3227 static void oops_print(frame* f, const RegisterMap *map) { 3228 PrintAndVerifyOopClosure print; 3229 f->print_value(); 3230 f->oops_do(&print, NULL, (RegisterMap*)map); 3231 } 3232 3233 // Print our all the locations that contain oops and whether they are 3234 // valid or not. This useful when trying to find the oldest frame 3235 // where an oop has gone bad since the frame walk is from youngest to 3236 // oldest. 3237 void JavaThread::trace_oops() { 3238 tty->print_cr("[Trace oops]"); 3239 frames_do(oops_print); 3240 } 3241 3242 3243 #ifdef ASSERT 3244 // Print or validate the layout of stack frames 3245 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3246 ResourceMark rm; 3247 PRESERVE_EXCEPTION_MARK; 3248 FrameValues values; 3249 int frame_no = 0; 3250 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3251 fst.current()->describe(values, ++frame_no); 3252 if (depth == frame_no) break; 3253 } 3254 if (validate_only) { 3255 values.validate(); 3256 } else { 3257 tty->print_cr("[Describe stack layout]"); 3258 values.print(this); 3259 } 3260 } 3261 #endif 3262 3263 void JavaThread::trace_stack_from(vframe* start_vf) { 3264 ResourceMark rm; 3265 int vframe_no = 1; 3266 for (vframe* f = start_vf; f; f = f->sender()) { 3267 if (f->is_java_frame()) { 3268 javaVFrame::cast(f)->print_activation(vframe_no++); 3269 } else { 3270 f->print(); 3271 } 3272 if (vframe_no > StackPrintLimit) { 3273 tty->print_cr("...<more frames>..."); 3274 return; 3275 } 3276 } 3277 } 3278 3279 3280 void JavaThread::trace_stack() { 3281 if (!has_last_Java_frame()) return; 3282 ResourceMark rm; 3283 HandleMark hm; 3284 RegisterMap reg_map(this); 3285 trace_stack_from(last_java_vframe(®_map)); 3286 } 3287 3288 3289 #endif // PRODUCT 3290 3291 3292 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3293 assert(reg_map != NULL, "a map must be given"); 3294 frame f = last_frame(); 3295 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3296 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3297 } 3298 return NULL; 3299 } 3300 3301 3302 Klass* JavaThread::security_get_caller_class(int depth) { 3303 vframeStream vfst(this); 3304 vfst.security_get_caller_frame(depth); 3305 if (!vfst.at_end()) { 3306 return vfst.method()->method_holder(); 3307 } 3308 return NULL; 3309 } 3310 3311 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3312 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3313 CompileBroker::compiler_thread_loop(); 3314 } 3315 3316 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3317 NMethodSweeper::sweeper_loop(); 3318 } 3319 3320 // Create a CompilerThread 3321 CompilerThread::CompilerThread(CompileQueue* queue, 3322 CompilerCounters* counters) 3323 : JavaThread(&compiler_thread_entry) { 3324 _env = NULL; 3325 _log = NULL; 3326 _task = NULL; 3327 _queue = queue; 3328 _counters = counters; 3329 _buffer_blob = NULL; 3330 _compiler = NULL; 3331 3332 #ifndef PRODUCT 3333 _ideal_graph_printer = NULL; 3334 #endif 3335 } 3336 3337 bool CompilerThread::can_call_java() const { 3338 return _compiler != NULL && _compiler->is_jvmci(); 3339 } 3340 3341 // Create sweeper thread 3342 CodeCacheSweeperThread::CodeCacheSweeperThread() 3343 : JavaThread(&sweeper_thread_entry) { 3344 _scanned_compiled_method = NULL; 3345 } 3346 3347 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3348 JavaThread::oops_do(f, cf); 3349 if (_scanned_compiled_method != NULL && cf != NULL) { 3350 // Safepoints can occur when the sweeper is scanning an nmethod so 3351 // process it here to make sure it isn't unloaded in the middle of 3352 // a scan. 3353 cf->do_code_blob(_scanned_compiled_method); 3354 } 3355 } 3356 3357 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3358 JavaThread::nmethods_do(cf); 3359 if (_scanned_compiled_method != NULL && cf != NULL) { 3360 // Safepoints can occur when the sweeper is scanning an nmethod so 3361 // process it here to make sure it isn't unloaded in the middle of 3362 // a scan. 3363 cf->do_code_blob(_scanned_compiled_method); 3364 } 3365 } 3366 3367 3368 // ======= Threads ======== 3369 3370 // The Threads class links together all active threads, and provides 3371 // operations over all threads. It is protected by its own Mutex 3372 // lock, which is also used in other contexts to protect thread 3373 // operations from having the thread being operated on from exiting 3374 // and going away unexpectedly (e.g., safepoint synchronization) 3375 3376 JavaThread* Threads::_thread_list = NULL; 3377 int Threads::_number_of_threads = 0; 3378 int Threads::_number_of_non_daemon_threads = 0; 3379 int Threads::_return_code = 0; 3380 int Threads::_thread_claim_parity = 0; 3381 size_t JavaThread::_stack_size_at_create = 0; 3382 #ifdef ASSERT 3383 bool Threads::_vm_complete = false; 3384 #endif 3385 3386 // All JavaThreads 3387 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3388 3389 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3390 void Threads::threads_do(ThreadClosure* tc) { 3391 assert_locked_or_safepoint(Threads_lock); 3392 // ALL_JAVA_THREADS iterates through all JavaThreads 3393 ALL_JAVA_THREADS(p) { 3394 tc->do_thread(p); 3395 } 3396 // Someday we could have a table or list of all non-JavaThreads. 3397 // For now, just manually iterate through them. 3398 tc->do_thread(VMThread::vm_thread()); 3399 Universe::heap()->gc_threads_do(tc); 3400 WatcherThread *wt = WatcherThread::watcher_thread(); 3401 // Strictly speaking, the following NULL check isn't sufficient to make sure 3402 // the data for WatcherThread is still valid upon being examined. However, 3403 // considering that WatchThread terminates when the VM is on the way to 3404 // exit at safepoint, the chance of the above is extremely small. The right 3405 // way to prevent termination of WatcherThread would be to acquire 3406 // Terminator_lock, but we can't do that without violating the lock rank 3407 // checking in some cases. 3408 if (wt != NULL) { 3409 tc->do_thread(wt); 3410 } 3411 3412 // If CompilerThreads ever become non-JavaThreads, add them here 3413 } 3414 3415 void Threads::parallel_java_threads_do(ThreadClosure* tc) { 3416 int cp = Threads::thread_claim_parity(); 3417 ALL_JAVA_THREADS(p) { 3418 if (p->claim_oops_do(true, cp)) { 3419 tc->do_thread(p); 3420 } 3421 } 3422 } 3423 3424 // The system initialization in the library has three phases. 3425 // 3426 // Phase 1: java.lang.System class initialization 3427 // java.lang.System is a primordial class loaded and initialized 3428 // by the VM early during startup. java.lang.System.<clinit> 3429 // only does registerNatives and keeps the rest of the class 3430 // initialization work later until thread initialization completes. 3431 // 3432 // System.initPhase1 initializes the system properties, the static 3433 // fields in, out, and err. Set up java signal handlers, OS-specific 3434 // system settings, and thread group of the main thread. 3435 static void call_initPhase1(TRAPS) { 3436 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3437 instanceKlassHandle klass (THREAD, k); 3438 3439 JavaValue result(T_VOID); 3440 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3441 vmSymbols::void_method_signature(), CHECK); 3442 } 3443 3444 // Phase 2. Module system initialization 3445 // This will initialize the module system. Only java.base classes 3446 // can be loaded until phase 2 completes. 3447 // 3448 // Call System.initPhase2 after the compiler initialization and jsr292 3449 // classes get initialized because module initialization runs a lot of java 3450 // code, that for performance reasons, should be compiled. Also, this will 3451 // enable the startup code to use lambda and other language features in this 3452 // phase and onward. 3453 // 3454 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3455 static void call_initPhase2(TRAPS) { 3456 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime)); 3457 3458 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3459 instanceKlassHandle klass (THREAD, k); 3460 3461 JavaValue result(T_INT); 3462 JavaCallArguments args; 3463 args.push_int(DisplayVMOutputToStderr); 3464 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3465 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3466 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3467 if (result.get_jint() != JNI_OK) { 3468 vm_exit_during_initialization(); // no message or exception 3469 } 3470 3471 universe_post_module_init(); 3472 } 3473 3474 // Phase 3. final setup - set security manager, system class loader and TCCL 3475 // 3476 // This will instantiate and set the security manager, set the system class 3477 // loader as well as the thread context class loader. The security manager 3478 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3479 // other modules or the application's classpath. 3480 static void call_initPhase3(TRAPS) { 3481 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3482 instanceKlassHandle klass (THREAD, k); 3483 3484 JavaValue result(T_VOID); 3485 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3486 vmSymbols::void_method_signature(), CHECK); 3487 } 3488 3489 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3490 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3491 3492 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3493 create_vm_init_libraries(); 3494 } 3495 3496 initialize_class(vmSymbols::java_lang_String(), CHECK); 3497 3498 // Inject CompactStrings value after the static initializers for String ran. 3499 java_lang_String::set_compact_strings(CompactStrings); 3500 3501 // Initialize java_lang.System (needed before creating the thread) 3502 initialize_class(vmSymbols::java_lang_System(), CHECK); 3503 // The VM creates & returns objects of this class. Make sure it's initialized. 3504 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3505 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3506 Handle thread_group = create_initial_thread_group(CHECK); 3507 Universe::set_main_thread_group(thread_group()); 3508 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3509 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3510 main_thread->set_threadObj(thread_object); 3511 // Set thread status to running since main thread has 3512 // been started and running. 3513 java_lang_Thread::set_thread_status(thread_object, 3514 java_lang_Thread::RUNNABLE); 3515 3516 // The VM creates objects of this class. 3517 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3518 3519 // The VM preresolves methods to these classes. Make sure that they get initialized 3520 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3521 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3522 3523 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3524 call_initPhase1(CHECK); 3525 3526 // get the Java runtime name after java.lang.System is initialized 3527 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3528 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3529 3530 // an instance of OutOfMemory exception has been allocated earlier 3531 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3532 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3533 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3534 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3535 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3536 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3537 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3538 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3539 } 3540 3541 void Threads::initialize_jsr292_core_classes(TRAPS) { 3542 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3543 3544 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3545 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3546 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3547 } 3548 3549 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3550 extern void JDK_Version_init(); 3551 3552 // Preinitialize version info. 3553 VM_Version::early_initialize(); 3554 3555 // Check version 3556 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3557 3558 // Initialize library-based TLS 3559 ThreadLocalStorage::init(); 3560 3561 // Initialize the output stream module 3562 ostream_init(); 3563 3564 // Process java launcher properties. 3565 Arguments::process_sun_java_launcher_properties(args); 3566 3567 // Initialize the os module 3568 os::init(); 3569 3570 // Record VM creation timing statistics 3571 TraceVmCreationTime create_vm_timer; 3572 create_vm_timer.start(); 3573 3574 // Initialize system properties. 3575 Arguments::init_system_properties(); 3576 3577 // So that JDK version can be used as a discriminator when parsing arguments 3578 JDK_Version_init(); 3579 3580 // Update/Initialize System properties after JDK version number is known 3581 Arguments::init_version_specific_system_properties(); 3582 3583 // Make sure to initialize log configuration *before* parsing arguments 3584 LogConfiguration::initialize(create_vm_timer.begin_time()); 3585 3586 // Parse arguments 3587 jint parse_result = Arguments::parse(args); 3588 if (parse_result != JNI_OK) return parse_result; 3589 3590 os::init_before_ergo(); 3591 3592 jint ergo_result = Arguments::apply_ergo(); 3593 if (ergo_result != JNI_OK) return ergo_result; 3594 3595 // Final check of all ranges after ergonomics which may change values. 3596 if (!CommandLineFlagRangeList::check_ranges()) { 3597 return JNI_EINVAL; 3598 } 3599 3600 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3601 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3602 if (!constraint_result) { 3603 return JNI_EINVAL; 3604 } 3605 3606 CommandLineFlagWriteableList::mark_startup(); 3607 3608 if (PauseAtStartup) { 3609 os::pause(); 3610 } 3611 3612 HOTSPOT_VM_INIT_BEGIN(); 3613 3614 // Timing (must come after argument parsing) 3615 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3616 3617 // Initialize the os module after parsing the args 3618 jint os_init_2_result = os::init_2(); 3619 if (os_init_2_result != JNI_OK) return os_init_2_result; 3620 3621 jint adjust_after_os_result = Arguments::adjust_after_os(); 3622 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3623 3624 // Initialize output stream logging 3625 ostream_init_log(); 3626 3627 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3628 // Must be before create_vm_init_agents() 3629 if (Arguments::init_libraries_at_startup()) { 3630 convert_vm_init_libraries_to_agents(); 3631 } 3632 3633 // Launch -agentlib/-agentpath and converted -Xrun agents 3634 if (Arguments::init_agents_at_startup()) { 3635 create_vm_init_agents(); 3636 } 3637 3638 // Initialize Threads state 3639 _thread_list = NULL; 3640 _number_of_threads = 0; 3641 _number_of_non_daemon_threads = 0; 3642 3643 // Initialize global data structures and create system classes in heap 3644 vm_init_globals(); 3645 3646 #if INCLUDE_JVMCI 3647 if (JVMCICounterSize > 0) { 3648 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3649 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3650 } else { 3651 JavaThread::_jvmci_old_thread_counters = NULL; 3652 } 3653 #endif // INCLUDE_JVMCI 3654 3655 // Attach the main thread to this os thread 3656 JavaThread* main_thread = new JavaThread(); 3657 main_thread->set_thread_state(_thread_in_vm); 3658 main_thread->initialize_thread_current(); 3659 // must do this before set_active_handles 3660 main_thread->record_stack_base_and_size(); 3661 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3662 3663 if (!main_thread->set_as_starting_thread()) { 3664 vm_shutdown_during_initialization( 3665 "Failed necessary internal allocation. Out of swap space"); 3666 delete main_thread; 3667 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3668 return JNI_ENOMEM; 3669 } 3670 3671 // Enable guard page *after* os::create_main_thread(), otherwise it would 3672 // crash Linux VM, see notes in os_linux.cpp. 3673 main_thread->create_stack_guard_pages(); 3674 3675 // Initialize Java-Level synchronization subsystem 3676 ObjectMonitor::Initialize(); 3677 3678 // Initialize global modules 3679 jint status = init_globals(); 3680 if (status != JNI_OK) { 3681 delete main_thread; 3682 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3683 return status; 3684 } 3685 3686 if (TRACE_INITIALIZE() != JNI_OK) { 3687 vm_exit_during_initialization("Failed to initialize tracing backend"); 3688 } 3689 3690 // Should be done after the heap is fully created 3691 main_thread->cache_global_variables(); 3692 3693 HandleMark hm; 3694 3695 { MutexLocker mu(Threads_lock); 3696 Threads::add(main_thread); 3697 } 3698 3699 // Any JVMTI raw monitors entered in onload will transition into 3700 // real raw monitor. VM is setup enough here for raw monitor enter. 3701 JvmtiExport::transition_pending_onload_raw_monitors(); 3702 3703 // Create the VMThread 3704 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3705 3706 VMThread::create(); 3707 Thread* vmthread = VMThread::vm_thread(); 3708 3709 if (!os::create_thread(vmthread, os::vm_thread)) { 3710 vm_exit_during_initialization("Cannot create VM thread. " 3711 "Out of system resources."); 3712 } 3713 3714 // Wait for the VM thread to become ready, and VMThread::run to initialize 3715 // Monitors can have spurious returns, must always check another state flag 3716 { 3717 MutexLocker ml(Notify_lock); 3718 os::start_thread(vmthread); 3719 while (vmthread->active_handles() == NULL) { 3720 Notify_lock->wait(); 3721 } 3722 } 3723 } 3724 3725 assert(Universe::is_fully_initialized(), "not initialized"); 3726 if (VerifyDuringStartup) { 3727 // Make sure we're starting with a clean slate. 3728 VM_Verify verify_op; 3729 VMThread::execute(&verify_op); 3730 } 3731 3732 Thread* THREAD = Thread::current(); 3733 3734 // At this point, the Universe is initialized, but we have not executed 3735 // any byte code. Now is a good time (the only time) to dump out the 3736 // internal state of the JVM for sharing. 3737 if (DumpSharedSpaces) { 3738 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3739 ShouldNotReachHere(); 3740 } 3741 3742 // Always call even when there are not JVMTI environments yet, since environments 3743 // may be attached late and JVMTI must track phases of VM execution 3744 JvmtiExport::enter_early_start_phase(); 3745 3746 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3747 JvmtiExport::post_early_vm_start(); 3748 3749 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3750 3751 // We need this for ClassDataSharing - the initial vm.info property is set 3752 // with the default value of CDS "sharing" which may be reset through 3753 // command line options. 3754 reset_vm_info_property(CHECK_JNI_ERR); 3755 3756 quicken_jni_functions(); 3757 3758 // No more stub generation allowed after that point. 3759 StubCodeDesc::freeze(); 3760 3761 // Set flag that basic initialization has completed. Used by exceptions and various 3762 // debug stuff, that does not work until all basic classes have been initialized. 3763 set_init_completed(); 3764 3765 LogConfiguration::post_initialize(); 3766 Metaspace::post_initialize(); 3767 3768 HOTSPOT_VM_INIT_END(); 3769 3770 // record VM initialization completion time 3771 #if INCLUDE_MANAGEMENT 3772 Management::record_vm_init_completed(); 3773 #endif // INCLUDE_MANAGEMENT 3774 3775 // Signal Dispatcher needs to be started before VMInit event is posted 3776 os::signal_init(); 3777 3778 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3779 if (!DisableAttachMechanism) { 3780 AttachListener::vm_start(); 3781 if (StartAttachListener || AttachListener::init_at_startup()) { 3782 AttachListener::init(); 3783 } 3784 } 3785 3786 // Launch -Xrun agents 3787 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3788 // back-end can launch with -Xdebug -Xrunjdwp. 3789 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3790 create_vm_init_libraries(); 3791 } 3792 3793 if (CleanChunkPoolAsync) { 3794 Chunk::start_chunk_pool_cleaner_task(); 3795 } 3796 3797 // initialize compiler(s) 3798 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3799 CompileBroker::compilation_init(CHECK_JNI_ERR); 3800 #endif 3801 3802 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3803 // It is done after compilers are initialized, because otherwise compilations of 3804 // signature polymorphic MH intrinsics can be missed 3805 // (see SystemDictionary::find_method_handle_intrinsic). 3806 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3807 3808 // This will initialize the module system. Only java.base classes can be 3809 // loaded until phase 2 completes 3810 call_initPhase2(CHECK_JNI_ERR); 3811 3812 // Always call even when there are not JVMTI environments yet, since environments 3813 // may be attached late and JVMTI must track phases of VM execution 3814 JvmtiExport::enter_start_phase(); 3815 3816 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3817 JvmtiExport::post_vm_start(); 3818 3819 // Final system initialization including security manager and system class loader 3820 call_initPhase3(CHECK_JNI_ERR); 3821 3822 // cache the system class loader 3823 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3824 3825 #if INCLUDE_JVMCI 3826 if (EnableJVMCI) { 3827 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3828 // The JVMCI Java initialization code will read this flag and 3829 // do the printing if it's set. 3830 bool init = JVMCIPrintProperties; 3831 3832 if (!init) { 3833 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3834 // compilations via JVMCI will not actually block until JVMCI is initialized. 3835 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3836 } 3837 3838 if (init) { 3839 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3840 } 3841 } 3842 #endif 3843 3844 // Always call even when there are not JVMTI environments yet, since environments 3845 // may be attached late and JVMTI must track phases of VM execution 3846 JvmtiExport::enter_live_phase(); 3847 3848 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3849 JvmtiExport::post_vm_initialized(); 3850 3851 if (TRACE_START() != JNI_OK) { 3852 vm_exit_during_initialization("Failed to start tracing backend."); 3853 } 3854 3855 #if INCLUDE_MANAGEMENT 3856 Management::initialize(THREAD); 3857 3858 if (HAS_PENDING_EXCEPTION) { 3859 // management agent fails to start possibly due to 3860 // configuration problem and is responsible for printing 3861 // stack trace if appropriate. Simply exit VM. 3862 vm_exit(1); 3863 } 3864 #endif // INCLUDE_MANAGEMENT 3865 3866 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3867 if (MemProfiling) MemProfiler::engage(); 3868 StatSampler::engage(); 3869 if (CheckJNICalls) JniPeriodicChecker::engage(); 3870 3871 BiasedLocking::init(); 3872 3873 #if INCLUDE_RTM_OPT 3874 RTMLockingCounters::init(); 3875 #endif 3876 3877 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3878 call_postVMInitHook(THREAD); 3879 // The Java side of PostVMInitHook.run must deal with all 3880 // exceptions and provide means of diagnosis. 3881 if (HAS_PENDING_EXCEPTION) { 3882 CLEAR_PENDING_EXCEPTION; 3883 } 3884 } 3885 3886 { 3887 MutexLocker ml(PeriodicTask_lock); 3888 // Make sure the WatcherThread can be started by WatcherThread::start() 3889 // or by dynamic enrollment. 3890 WatcherThread::make_startable(); 3891 // Start up the WatcherThread if there are any periodic tasks 3892 // NOTE: All PeriodicTasks should be registered by now. If they 3893 // aren't, late joiners might appear to start slowly (we might 3894 // take a while to process their first tick). 3895 if (PeriodicTask::num_tasks() > 0) { 3896 WatcherThread::start(); 3897 } 3898 } 3899 3900 create_vm_timer.end(); 3901 #ifdef ASSERT 3902 _vm_complete = true; 3903 #endif 3904 return JNI_OK; 3905 } 3906 3907 // type for the Agent_OnLoad and JVM_OnLoad entry points 3908 extern "C" { 3909 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3910 } 3911 // Find a command line agent library and return its entry point for 3912 // -agentlib: -agentpath: -Xrun 3913 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3914 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3915 const char *on_load_symbols[], 3916 size_t num_symbol_entries) { 3917 OnLoadEntry_t on_load_entry = NULL; 3918 void *library = NULL; 3919 3920 if (!agent->valid()) { 3921 char buffer[JVM_MAXPATHLEN]; 3922 char ebuf[1024] = ""; 3923 const char *name = agent->name(); 3924 const char *msg = "Could not find agent library "; 3925 3926 // First check to see if agent is statically linked into executable 3927 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3928 library = agent->os_lib(); 3929 } else if (agent->is_absolute_path()) { 3930 library = os::dll_load(name, ebuf, sizeof ebuf); 3931 if (library == NULL) { 3932 const char *sub_msg = " in absolute path, with error: "; 3933 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3934 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3935 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3936 // If we can't find the agent, exit. 3937 vm_exit_during_initialization(buf, NULL); 3938 FREE_C_HEAP_ARRAY(char, buf); 3939 } 3940 } else { 3941 // Try to load the agent from the standard dll directory 3942 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3943 name)) { 3944 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3945 } 3946 if (library == NULL) { // Try the local directory 3947 char ns[1] = {0}; 3948 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3949 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3950 } 3951 if (library == NULL) { 3952 const char *sub_msg = " on the library path, with error: "; 3953 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3954 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3955 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3956 // If we can't find the agent, exit. 3957 vm_exit_during_initialization(buf, NULL); 3958 FREE_C_HEAP_ARRAY(char, buf); 3959 } 3960 } 3961 } 3962 agent->set_os_lib(library); 3963 agent->set_valid(); 3964 } 3965 3966 // Find the OnLoad function. 3967 on_load_entry = 3968 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3969 false, 3970 on_load_symbols, 3971 num_symbol_entries)); 3972 return on_load_entry; 3973 } 3974 3975 // Find the JVM_OnLoad entry point 3976 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3977 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3978 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3979 } 3980 3981 // Find the Agent_OnLoad entry point 3982 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3983 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3984 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3985 } 3986 3987 // For backwards compatibility with -Xrun 3988 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3989 // treated like -agentpath: 3990 // Must be called before agent libraries are created 3991 void Threads::convert_vm_init_libraries_to_agents() { 3992 AgentLibrary* agent; 3993 AgentLibrary* next; 3994 3995 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3996 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3997 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3998 3999 // If there is an JVM_OnLoad function it will get called later, 4000 // otherwise see if there is an Agent_OnLoad 4001 if (on_load_entry == NULL) { 4002 on_load_entry = lookup_agent_on_load(agent); 4003 if (on_load_entry != NULL) { 4004 // switch it to the agent list -- so that Agent_OnLoad will be called, 4005 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4006 Arguments::convert_library_to_agent(agent); 4007 } else { 4008 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4009 } 4010 } 4011 } 4012 } 4013 4014 // Create agents for -agentlib: -agentpath: and converted -Xrun 4015 // Invokes Agent_OnLoad 4016 // Called very early -- before JavaThreads exist 4017 void Threads::create_vm_init_agents() { 4018 extern struct JavaVM_ main_vm; 4019 AgentLibrary* agent; 4020 4021 JvmtiExport::enter_onload_phase(); 4022 4023 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4024 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4025 4026 if (on_load_entry != NULL) { 4027 // Invoke the Agent_OnLoad function 4028 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4029 if (err != JNI_OK) { 4030 vm_exit_during_initialization("agent library failed to init", agent->name()); 4031 } 4032 } else { 4033 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4034 } 4035 } 4036 JvmtiExport::enter_primordial_phase(); 4037 } 4038 4039 extern "C" { 4040 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4041 } 4042 4043 void Threads::shutdown_vm_agents() { 4044 // Send any Agent_OnUnload notifications 4045 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4046 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4047 extern struct JavaVM_ main_vm; 4048 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4049 4050 // Find the Agent_OnUnload function. 4051 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4052 os::find_agent_function(agent, 4053 false, 4054 on_unload_symbols, 4055 num_symbol_entries)); 4056 4057 // Invoke the Agent_OnUnload function 4058 if (unload_entry != NULL) { 4059 JavaThread* thread = JavaThread::current(); 4060 ThreadToNativeFromVM ttn(thread); 4061 HandleMark hm(thread); 4062 (*unload_entry)(&main_vm); 4063 } 4064 } 4065 } 4066 4067 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4068 // Invokes JVM_OnLoad 4069 void Threads::create_vm_init_libraries() { 4070 extern struct JavaVM_ main_vm; 4071 AgentLibrary* agent; 4072 4073 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4074 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4075 4076 if (on_load_entry != NULL) { 4077 // Invoke the JVM_OnLoad function 4078 JavaThread* thread = JavaThread::current(); 4079 ThreadToNativeFromVM ttn(thread); 4080 HandleMark hm(thread); 4081 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4082 if (err != JNI_OK) { 4083 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4084 } 4085 } else { 4086 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4087 } 4088 } 4089 } 4090 4091 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4092 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4093 4094 JavaThread* java_thread = NULL; 4095 // Sequential search for now. Need to do better optimization later. 4096 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4097 oop tobj = thread->threadObj(); 4098 if (!thread->is_exiting() && 4099 tobj != NULL && 4100 java_tid == java_lang_Thread::thread_id(tobj)) { 4101 java_thread = thread; 4102 break; 4103 } 4104 } 4105 return java_thread; 4106 } 4107 4108 4109 // Last thread running calls java.lang.Shutdown.shutdown() 4110 void JavaThread::invoke_shutdown_hooks() { 4111 HandleMark hm(this); 4112 4113 // We could get here with a pending exception, if so clear it now. 4114 if (this->has_pending_exception()) { 4115 this->clear_pending_exception(); 4116 } 4117 4118 EXCEPTION_MARK; 4119 Klass* k = 4120 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4121 THREAD); 4122 if (k != NULL) { 4123 // SystemDictionary::resolve_or_null will return null if there was 4124 // an exception. If we cannot load the Shutdown class, just don't 4125 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4126 // and finalizers (if runFinalizersOnExit is set) won't be run. 4127 // Note that if a shutdown hook was registered or runFinalizersOnExit 4128 // was called, the Shutdown class would have already been loaded 4129 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4130 instanceKlassHandle shutdown_klass (THREAD, k); 4131 JavaValue result(T_VOID); 4132 JavaCalls::call_static(&result, 4133 shutdown_klass, 4134 vmSymbols::shutdown_method_name(), 4135 vmSymbols::void_method_signature(), 4136 THREAD); 4137 } 4138 CLEAR_PENDING_EXCEPTION; 4139 } 4140 4141 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4142 // the program falls off the end of main(). Another VM exit path is through 4143 // vm_exit() when the program calls System.exit() to return a value or when 4144 // there is a serious error in VM. The two shutdown paths are not exactly 4145 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4146 // and VM_Exit op at VM level. 4147 // 4148 // Shutdown sequence: 4149 // + Shutdown native memory tracking if it is on 4150 // + Wait until we are the last non-daemon thread to execute 4151 // <-- every thing is still working at this moment --> 4152 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4153 // shutdown hooks, run finalizers if finalization-on-exit 4154 // + Call before_exit(), prepare for VM exit 4155 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4156 // currently the only user of this mechanism is File.deleteOnExit()) 4157 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4158 // post thread end and vm death events to JVMTI, 4159 // stop signal thread 4160 // + Call JavaThread::exit(), it will: 4161 // > release JNI handle blocks, remove stack guard pages 4162 // > remove this thread from Threads list 4163 // <-- no more Java code from this thread after this point --> 4164 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4165 // the compiler threads at safepoint 4166 // <-- do not use anything that could get blocked by Safepoint --> 4167 // + Disable tracing at JNI/JVM barriers 4168 // + Set _vm_exited flag for threads that are still running native code 4169 // + Delete this thread 4170 // + Call exit_globals() 4171 // > deletes tty 4172 // > deletes PerfMemory resources 4173 // + Return to caller 4174 4175 bool Threads::destroy_vm() { 4176 JavaThread* thread = JavaThread::current(); 4177 4178 #ifdef ASSERT 4179 _vm_complete = false; 4180 #endif 4181 // Wait until we are the last non-daemon thread to execute 4182 { MutexLocker nu(Threads_lock); 4183 while (Threads::number_of_non_daemon_threads() > 1) 4184 // This wait should make safepoint checks, wait without a timeout, 4185 // and wait as a suspend-equivalent condition. 4186 // 4187 // Note: If the FlatProfiler is running and this thread is waiting 4188 // for another non-daemon thread to finish, then the FlatProfiler 4189 // is waiting for the external suspend request on this thread to 4190 // complete. wait_for_ext_suspend_completion() will eventually 4191 // timeout, but that takes time. Making this wait a suspend- 4192 // equivalent condition solves that timeout problem. 4193 // 4194 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4195 Mutex::_as_suspend_equivalent_flag); 4196 } 4197 4198 // Hang forever on exit if we are reporting an error. 4199 if (ShowMessageBoxOnError && is_error_reported()) { 4200 os::infinite_sleep(); 4201 } 4202 os::wait_for_keypress_at_exit(); 4203 4204 // run Java level shutdown hooks 4205 thread->invoke_shutdown_hooks(); 4206 4207 before_exit(thread); 4208 4209 thread->exit(true); 4210 4211 // Stop VM thread. 4212 { 4213 // 4945125 The vm thread comes to a safepoint during exit. 4214 // GC vm_operations can get caught at the safepoint, and the 4215 // heap is unparseable if they are caught. Grab the Heap_lock 4216 // to prevent this. The GC vm_operations will not be able to 4217 // queue until after the vm thread is dead. After this point, 4218 // we'll never emerge out of the safepoint before the VM exits. 4219 4220 MutexLocker ml(Heap_lock); 4221 4222 VMThread::wait_for_vm_thread_exit(); 4223 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4224 VMThread::destroy(); 4225 } 4226 4227 // clean up ideal graph printers 4228 #if defined(COMPILER2) && !defined(PRODUCT) 4229 IdealGraphPrinter::clean_up(); 4230 #endif 4231 4232 // Now, all Java threads are gone except daemon threads. Daemon threads 4233 // running Java code or in VM are stopped by the Safepoint. However, 4234 // daemon threads executing native code are still running. But they 4235 // will be stopped at native=>Java/VM barriers. Note that we can't 4236 // simply kill or suspend them, as it is inherently deadlock-prone. 4237 4238 VM_Exit::set_vm_exited(); 4239 4240 notify_vm_shutdown(); 4241 4242 delete thread; 4243 4244 #if INCLUDE_JVMCI 4245 if (JVMCICounterSize > 0) { 4246 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4247 } 4248 #endif 4249 4250 // exit_globals() will delete tty 4251 exit_globals(); 4252 4253 LogConfiguration::finalize(); 4254 4255 return true; 4256 } 4257 4258 4259 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4260 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4261 return is_supported_jni_version(version); 4262 } 4263 4264 4265 jboolean Threads::is_supported_jni_version(jint version) { 4266 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4267 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4268 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4269 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4270 if (version == JNI_VERSION_9) return JNI_TRUE; 4271 return JNI_FALSE; 4272 } 4273 4274 4275 void Threads::add(JavaThread* p, bool force_daemon) { 4276 // The threads lock must be owned at this point 4277 assert_locked_or_safepoint(Threads_lock); 4278 4279 // See the comment for this method in thread.hpp for its purpose and 4280 // why it is called here. 4281 p->initialize_queues(); 4282 p->set_next(_thread_list); 4283 _thread_list = p; 4284 _number_of_threads++; 4285 oop threadObj = p->threadObj(); 4286 bool daemon = true; 4287 // Bootstrapping problem: threadObj can be null for initial 4288 // JavaThread (or for threads attached via JNI) 4289 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4290 _number_of_non_daemon_threads++; 4291 daemon = false; 4292 } 4293 4294 ThreadService::add_thread(p, daemon); 4295 4296 // Possible GC point. 4297 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4298 } 4299 4300 void Threads::remove(JavaThread* p) { 4301 4302 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4303 ObjectSynchronizer::omFlush(p); 4304 4305 // Extra scope needed for Thread_lock, so we can check 4306 // that we do not remove thread without safepoint code notice 4307 { MutexLocker ml(Threads_lock); 4308 4309 assert(includes(p), "p must be present"); 4310 4311 JavaThread* current = _thread_list; 4312 JavaThread* prev = NULL; 4313 4314 while (current != p) { 4315 prev = current; 4316 current = current->next(); 4317 } 4318 4319 if (prev) { 4320 prev->set_next(current->next()); 4321 } else { 4322 _thread_list = p->next(); 4323 } 4324 _number_of_threads--; 4325 oop threadObj = p->threadObj(); 4326 bool daemon = true; 4327 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4328 _number_of_non_daemon_threads--; 4329 daemon = false; 4330 4331 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4332 // on destroy_vm will wake up. 4333 if (number_of_non_daemon_threads() == 1) { 4334 Threads_lock->notify_all(); 4335 } 4336 } 4337 ThreadService::remove_thread(p, daemon); 4338 4339 // Make sure that safepoint code disregard this thread. This is needed since 4340 // the thread might mess around with locks after this point. This can cause it 4341 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4342 // of this thread since it is removed from the queue. 4343 p->set_terminated_value(); 4344 } // unlock Threads_lock 4345 4346 // Since Events::log uses a lock, we grab it outside the Threads_lock 4347 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4348 } 4349 4350 // Threads_lock must be held when this is called (or must be called during a safepoint) 4351 bool Threads::includes(JavaThread* p) { 4352 assert(Threads_lock->is_locked(), "sanity check"); 4353 ALL_JAVA_THREADS(q) { 4354 if (q == p) { 4355 return true; 4356 } 4357 } 4358 return false; 4359 } 4360 4361 // Operations on the Threads list for GC. These are not explicitly locked, 4362 // but the garbage collector must provide a safe context for them to run. 4363 // In particular, these things should never be called when the Threads_lock 4364 // is held by some other thread. (Note: the Safepoint abstraction also 4365 // uses the Threads_lock to guarantee this property. It also makes sure that 4366 // all threads gets blocked when exiting or starting). 4367 4368 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4369 ALL_JAVA_THREADS(p) { 4370 p->oops_do(f, cf); 4371 } 4372 VMThread::vm_thread()->oops_do(f, cf); 4373 } 4374 4375 void Threads::change_thread_claim_parity() { 4376 // Set the new claim parity. 4377 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4378 "Not in range."); 4379 _thread_claim_parity++; 4380 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4381 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4382 "Not in range."); 4383 } 4384 4385 #ifdef ASSERT 4386 void Threads::assert_all_threads_claimed() { 4387 ALL_JAVA_THREADS(p) { 4388 const int thread_parity = p->oops_do_parity(); 4389 assert((thread_parity == _thread_claim_parity), 4390 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4391 } 4392 } 4393 #endif // ASSERT 4394 4395 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf, CodeBlobClosure* nmethods_cl) { 4396 CodeBlobClosure* blobs; 4397 VM_Operation* op = VMThread::vm_operation(); 4398 if (op != NULL && op->marks_nmethods()) { 4399 } 4400 int cp = Threads::thread_claim_parity(); 4401 ALL_JAVA_THREADS(p) { 4402 if (p->claim_oops_do(is_par, cp)) { 4403 p->oops_do(f, cf); 4404 if (nmethods_cl != NULL && ! p->is_Code_cache_sweeper_thread()) { 4405 p->nmethods_do(nmethods_cl); 4406 } 4407 } 4408 } 4409 VMThread* vmt = VMThread::vm_thread(); 4410 if (vmt->claim_oops_do(is_par, cp)) { 4411 vmt->oops_do(f, cf); 4412 } 4413 } 4414 4415 #if INCLUDE_ALL_GCS 4416 // Used by ParallelScavenge 4417 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4418 ALL_JAVA_THREADS(p) { 4419 q->enqueue(new ThreadRootsTask(p)); 4420 } 4421 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4422 } 4423 4424 // Used by Parallel Old 4425 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4426 ALL_JAVA_THREADS(p) { 4427 q->enqueue(new ThreadRootsMarkingTask(p)); 4428 } 4429 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4430 } 4431 #endif // INCLUDE_ALL_GCS 4432 4433 void Threads::nmethods_do(CodeBlobClosure* cf) { 4434 ALL_JAVA_THREADS(p) { 4435 // This is used by the code cache sweeper to mark nmethods that are active 4436 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4437 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4438 if(!p->is_Code_cache_sweeper_thread()) { 4439 p->nmethods_do(cf); 4440 } 4441 } 4442 } 4443 4444 void Threads::metadata_do(void f(Metadata*)) { 4445 ALL_JAVA_THREADS(p) { 4446 p->metadata_do(f); 4447 } 4448 } 4449 4450 class ThreadHandlesClosure : public ThreadClosure { 4451 void (*_f)(Metadata*); 4452 public: 4453 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4454 virtual void do_thread(Thread* thread) { 4455 thread->metadata_handles_do(_f); 4456 } 4457 }; 4458 4459 void Threads::metadata_handles_do(void f(Metadata*)) { 4460 // Only walk the Handles in Thread. 4461 ThreadHandlesClosure handles_closure(f); 4462 threads_do(&handles_closure); 4463 } 4464 4465 void Threads::deoptimized_wrt_marked_nmethods() { 4466 ALL_JAVA_THREADS(p) { 4467 p->deoptimized_wrt_marked_nmethods(); 4468 } 4469 } 4470 4471 4472 // Get count Java threads that are waiting to enter the specified monitor. 4473 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4474 address monitor, 4475 bool doLock) { 4476 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4477 "must grab Threads_lock or be at safepoint"); 4478 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4479 4480 int i = 0; 4481 { 4482 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4483 ALL_JAVA_THREADS(p) { 4484 if (!p->can_call_java()) continue; 4485 4486 address pending = (address)p->current_pending_monitor(); 4487 if (pending == monitor) { // found a match 4488 if (i < count) result->append(p); // save the first count matches 4489 i++; 4490 } 4491 } 4492 } 4493 return result; 4494 } 4495 4496 4497 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4498 bool doLock) { 4499 assert(doLock || 4500 Threads_lock->owned_by_self() || 4501 SafepointSynchronize::is_at_safepoint(), 4502 "must grab Threads_lock or be at safepoint"); 4503 4504 // NULL owner means not locked so we can skip the search 4505 if (owner == NULL) return NULL; 4506 4507 { 4508 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4509 ALL_JAVA_THREADS(p) { 4510 // first, see if owner is the address of a Java thread 4511 if (owner == (address)p) return p; 4512 } 4513 } 4514 // Cannot assert on lack of success here since this function may be 4515 // used by code that is trying to report useful problem information 4516 // like deadlock detection. 4517 if (UseHeavyMonitors) return NULL; 4518 4519 // If we didn't find a matching Java thread and we didn't force use of 4520 // heavyweight monitors, then the owner is the stack address of the 4521 // Lock Word in the owning Java thread's stack. 4522 // 4523 JavaThread* the_owner = NULL; 4524 { 4525 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4526 ALL_JAVA_THREADS(q) { 4527 if (q->is_lock_owned(owner)) { 4528 the_owner = q; 4529 break; 4530 } 4531 } 4532 } 4533 // cannot assert on lack of success here; see above comment 4534 return the_owner; 4535 } 4536 4537 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4538 void Threads::print_on(outputStream* st, bool print_stacks, 4539 bool internal_format, bool print_concurrent_locks) { 4540 char buf[32]; 4541 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4542 4543 st->print_cr("Full thread dump %s (%s %s):", 4544 Abstract_VM_Version::vm_name(), 4545 Abstract_VM_Version::vm_release(), 4546 Abstract_VM_Version::vm_info_string()); 4547 st->cr(); 4548 4549 #if INCLUDE_SERVICES 4550 // Dump concurrent locks 4551 ConcurrentLocksDump concurrent_locks; 4552 if (print_concurrent_locks) { 4553 concurrent_locks.dump_at_safepoint(); 4554 } 4555 #endif // INCLUDE_SERVICES 4556 4557 ALL_JAVA_THREADS(p) { 4558 ResourceMark rm; 4559 p->print_on(st); 4560 if (print_stacks) { 4561 if (internal_format) { 4562 p->trace_stack(); 4563 } else { 4564 p->print_stack_on(st); 4565 } 4566 } 4567 st->cr(); 4568 #if INCLUDE_SERVICES 4569 if (print_concurrent_locks) { 4570 concurrent_locks.print_locks_on(p, st); 4571 } 4572 #endif // INCLUDE_SERVICES 4573 } 4574 4575 VMThread::vm_thread()->print_on(st); 4576 st->cr(); 4577 Universe::heap()->print_gc_threads_on(st); 4578 WatcherThread* wt = WatcherThread::watcher_thread(); 4579 if (wt != NULL) { 4580 wt->print_on(st); 4581 st->cr(); 4582 } 4583 st->flush(); 4584 } 4585 4586 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4587 int buflen, bool* found_current) { 4588 if (this_thread != NULL) { 4589 bool is_current = (current == this_thread); 4590 *found_current = *found_current || is_current; 4591 st->print("%s", is_current ? "=>" : " "); 4592 4593 st->print(PTR_FORMAT, p2i(this_thread)); 4594 st->print(" "); 4595 this_thread->print_on_error(st, buf, buflen); 4596 st->cr(); 4597 } 4598 } 4599 4600 class PrintOnErrorClosure : public ThreadClosure { 4601 outputStream* _st; 4602 Thread* _current; 4603 char* _buf; 4604 int _buflen; 4605 bool* _found_current; 4606 public: 4607 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4608 int buflen, bool* found_current) : 4609 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4610 4611 virtual void do_thread(Thread* thread) { 4612 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4613 } 4614 }; 4615 4616 // Threads::print_on_error() is called by fatal error handler. It's possible 4617 // that VM is not at safepoint and/or current thread is inside signal handler. 4618 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4619 // memory (even in resource area), it might deadlock the error handler. 4620 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4621 int buflen) { 4622 bool found_current = false; 4623 st->print_cr("Java Threads: ( => current thread )"); 4624 ALL_JAVA_THREADS(thread) { 4625 print_on_error(thread, st, current, buf, buflen, &found_current); 4626 } 4627 st->cr(); 4628 4629 st->print_cr("Other Threads:"); 4630 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4631 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4632 4633 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4634 Universe::heap()->gc_threads_do(&print_closure); 4635 4636 if (!found_current) { 4637 st->cr(); 4638 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4639 current->print_on_error(st, buf, buflen); 4640 st->cr(); 4641 } 4642 st->cr(); 4643 st->print_cr("Threads with active compile tasks:"); 4644 print_threads_compiling(st, buf, buflen); 4645 } 4646 4647 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4648 ALL_JAVA_THREADS(thread) { 4649 if (thread->is_Compiler_thread()) { 4650 CompilerThread* ct = (CompilerThread*) thread; 4651 if (ct->task() != NULL) { 4652 thread->print_name_on_error(st, buf, buflen); 4653 ct->task()->print(st, NULL, true, true); 4654 } 4655 } 4656 } 4657 } 4658 4659 4660 // Internal SpinLock and Mutex 4661 // Based on ParkEvent 4662 4663 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4664 // 4665 // We employ SpinLocks _only for low-contention, fixed-length 4666 // short-duration critical sections where we're concerned 4667 // about native mutex_t or HotSpot Mutex:: latency. 4668 // The mux construct provides a spin-then-block mutual exclusion 4669 // mechanism. 4670 // 4671 // Testing has shown that contention on the ListLock guarding gFreeList 4672 // is common. If we implement ListLock as a simple SpinLock it's common 4673 // for the JVM to devolve to yielding with little progress. This is true 4674 // despite the fact that the critical sections protected by ListLock are 4675 // extremely short. 4676 // 4677 // TODO-FIXME: ListLock should be of type SpinLock. 4678 // We should make this a 1st-class type, integrated into the lock 4679 // hierarchy as leaf-locks. Critically, the SpinLock structure 4680 // should have sufficient padding to avoid false-sharing and excessive 4681 // cache-coherency traffic. 4682 4683 4684 typedef volatile int SpinLockT; 4685 4686 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4687 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4688 return; // normal fast-path return 4689 } 4690 4691 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4692 TEVENT(SpinAcquire - ctx); 4693 int ctr = 0; 4694 int Yields = 0; 4695 for (;;) { 4696 while (*adr != 0) { 4697 ++ctr; 4698 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4699 if (Yields > 5) { 4700 os::naked_short_sleep(1); 4701 } else { 4702 os::naked_yield(); 4703 ++Yields; 4704 } 4705 } else { 4706 SpinPause(); 4707 } 4708 } 4709 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4710 } 4711 } 4712 4713 void Thread::SpinRelease(volatile int * adr) { 4714 assert(*adr != 0, "invariant"); 4715 OrderAccess::fence(); // guarantee at least release consistency. 4716 // Roach-motel semantics. 4717 // It's safe if subsequent LDs and STs float "up" into the critical section, 4718 // but prior LDs and STs within the critical section can't be allowed 4719 // to reorder or float past the ST that releases the lock. 4720 // Loads and stores in the critical section - which appear in program 4721 // order before the store that releases the lock - must also appear 4722 // before the store that releases the lock in memory visibility order. 4723 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4724 // the ST of 0 into the lock-word which releases the lock, so fence 4725 // more than covers this on all platforms. 4726 *adr = 0; 4727 } 4728 4729 // muxAcquire and muxRelease: 4730 // 4731 // * muxAcquire and muxRelease support a single-word lock-word construct. 4732 // The LSB of the word is set IFF the lock is held. 4733 // The remainder of the word points to the head of a singly-linked list 4734 // of threads blocked on the lock. 4735 // 4736 // * The current implementation of muxAcquire-muxRelease uses its own 4737 // dedicated Thread._MuxEvent instance. If we're interested in 4738 // minimizing the peak number of extant ParkEvent instances then 4739 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4740 // as certain invariants were satisfied. Specifically, care would need 4741 // to be taken with regards to consuming unpark() "permits". 4742 // A safe rule of thumb is that a thread would never call muxAcquire() 4743 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4744 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4745 // consume an unpark() permit intended for monitorenter, for instance. 4746 // One way around this would be to widen the restricted-range semaphore 4747 // implemented in park(). Another alternative would be to provide 4748 // multiple instances of the PlatformEvent() for each thread. One 4749 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4750 // 4751 // * Usage: 4752 // -- Only as leaf locks 4753 // -- for short-term locking only as muxAcquire does not perform 4754 // thread state transitions. 4755 // 4756 // Alternatives: 4757 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4758 // but with parking or spin-then-park instead of pure spinning. 4759 // * Use Taura-Oyama-Yonenzawa locks. 4760 // * It's possible to construct a 1-0 lock if we encode the lockword as 4761 // (List,LockByte). Acquire will CAS the full lockword while Release 4762 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4763 // acquiring threads use timers (ParkTimed) to detect and recover from 4764 // the stranding window. Thread/Node structures must be aligned on 256-byte 4765 // boundaries by using placement-new. 4766 // * Augment MCS with advisory back-link fields maintained with CAS(). 4767 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4768 // The validity of the backlinks must be ratified before we trust the value. 4769 // If the backlinks are invalid the exiting thread must back-track through the 4770 // the forward links, which are always trustworthy. 4771 // * Add a successor indication. The LockWord is currently encoded as 4772 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4773 // to provide the usual futile-wakeup optimization. 4774 // See RTStt for details. 4775 // * Consider schedctl.sc_nopreempt to cover the critical section. 4776 // 4777 4778 4779 typedef volatile intptr_t MutexT; // Mux Lock-word 4780 enum MuxBits { LOCKBIT = 1 }; 4781 4782 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4783 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4784 if (w == 0) return; 4785 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4786 return; 4787 } 4788 4789 TEVENT(muxAcquire - Contention); 4790 ParkEvent * const Self = Thread::current()->_MuxEvent; 4791 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4792 for (;;) { 4793 int its = (os::is_MP() ? 100 : 0) + 1; 4794 4795 // Optional spin phase: spin-then-park strategy 4796 while (--its >= 0) { 4797 w = *Lock; 4798 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4799 return; 4800 } 4801 } 4802 4803 Self->reset(); 4804 Self->OnList = intptr_t(Lock); 4805 // The following fence() isn't _strictly necessary as the subsequent 4806 // CAS() both serializes execution and ratifies the fetched *Lock value. 4807 OrderAccess::fence(); 4808 for (;;) { 4809 w = *Lock; 4810 if ((w & LOCKBIT) == 0) { 4811 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4812 Self->OnList = 0; // hygiene - allows stronger asserts 4813 return; 4814 } 4815 continue; // Interference -- *Lock changed -- Just retry 4816 } 4817 assert(w & LOCKBIT, "invariant"); 4818 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4819 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4820 } 4821 4822 while (Self->OnList != 0) { 4823 Self->park(); 4824 } 4825 } 4826 } 4827 4828 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4829 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4830 if (w == 0) return; 4831 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4832 return; 4833 } 4834 4835 TEVENT(muxAcquire - Contention); 4836 ParkEvent * ReleaseAfter = NULL; 4837 if (ev == NULL) { 4838 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4839 } 4840 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4841 for (;;) { 4842 guarantee(ev->OnList == 0, "invariant"); 4843 int its = (os::is_MP() ? 100 : 0) + 1; 4844 4845 // Optional spin phase: spin-then-park strategy 4846 while (--its >= 0) { 4847 w = *Lock; 4848 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4849 if (ReleaseAfter != NULL) { 4850 ParkEvent::Release(ReleaseAfter); 4851 } 4852 return; 4853 } 4854 } 4855 4856 ev->reset(); 4857 ev->OnList = intptr_t(Lock); 4858 // The following fence() isn't _strictly necessary as the subsequent 4859 // CAS() both serializes execution and ratifies the fetched *Lock value. 4860 OrderAccess::fence(); 4861 for (;;) { 4862 w = *Lock; 4863 if ((w & LOCKBIT) == 0) { 4864 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4865 ev->OnList = 0; 4866 // We call ::Release while holding the outer lock, thus 4867 // artificially lengthening the critical section. 4868 // Consider deferring the ::Release() until the subsequent unlock(), 4869 // after we've dropped the outer lock. 4870 if (ReleaseAfter != NULL) { 4871 ParkEvent::Release(ReleaseAfter); 4872 } 4873 return; 4874 } 4875 continue; // Interference -- *Lock changed -- Just retry 4876 } 4877 assert(w & LOCKBIT, "invariant"); 4878 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4879 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4880 } 4881 4882 while (ev->OnList != 0) { 4883 ev->park(); 4884 } 4885 } 4886 } 4887 4888 // Release() must extract a successor from the list and then wake that thread. 4889 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4890 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4891 // Release() would : 4892 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4893 // (B) Extract a successor from the private list "in-hand" 4894 // (C) attempt to CAS() the residual back into *Lock over null. 4895 // If there were any newly arrived threads and the CAS() would fail. 4896 // In that case Release() would detach the RATs, re-merge the list in-hand 4897 // with the RATs and repeat as needed. Alternately, Release() might 4898 // detach and extract a successor, but then pass the residual list to the wakee. 4899 // The wakee would be responsible for reattaching and remerging before it 4900 // competed for the lock. 4901 // 4902 // Both "pop" and DMR are immune from ABA corruption -- there can be 4903 // multiple concurrent pushers, but only one popper or detacher. 4904 // This implementation pops from the head of the list. This is unfair, 4905 // but tends to provide excellent throughput as hot threads remain hot. 4906 // (We wake recently run threads first). 4907 // 4908 // All paths through muxRelease() will execute a CAS. 4909 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4910 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4911 // executed within the critical section are complete and globally visible before the 4912 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4913 void Thread::muxRelease(volatile intptr_t * Lock) { 4914 for (;;) { 4915 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4916 assert(w & LOCKBIT, "invariant"); 4917 if (w == LOCKBIT) return; 4918 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4919 assert(List != NULL, "invariant"); 4920 assert(List->OnList == intptr_t(Lock), "invariant"); 4921 ParkEvent * const nxt = List->ListNext; 4922 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4923 4924 // The following CAS() releases the lock and pops the head element. 4925 // The CAS() also ratifies the previously fetched lock-word value. 4926 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4927 continue; 4928 } 4929 List->OnList = 0; 4930 OrderAccess::fence(); 4931 List->unpark(); 4932 return; 4933 } 4934 } 4935 4936 4937 void Threads::verify() { 4938 ALL_JAVA_THREADS(p) { 4939 p->verify(); 4940 } 4941 VMThread* thread = VMThread::vm_thread(); 4942 if (thread != NULL) thread->verify(); 4943 }