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 "logging/logStream.hpp" 45 #include "memory/metaspaceShared.hpp" 46 #include "memory/oopFactory.hpp" 47 #include "memory/resourceArea.hpp" 48 #include "memory/universe.inline.hpp" 49 #include "oops/instanceKlass.hpp" 50 #include "oops/objArrayOop.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "oops/symbol.hpp" 53 #include "oops/verifyOopClosure.hpp" 54 #include "prims/jvm.h" 55 #include "prims/jvm_misc.hpp" 56 #include "prims/jvmtiExport.hpp" 57 #include "prims/jvmtiThreadState.hpp" 58 #include "prims/privilegedStack.hpp" 59 #include "runtime/arguments.hpp" 60 #include "runtime/atomic.hpp" 61 #include "runtime/biasedLocking.hpp" 62 #include "runtime/commandLineFlagConstraintList.hpp" 63 #include "runtime/commandLineFlagWriteableList.hpp" 64 #include "runtime/commandLineFlagRangeList.hpp" 65 #include "runtime/deoptimization.hpp" 66 #include "runtime/frame.inline.hpp" 67 #include "runtime/globals.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/interfaceSupport.hpp" 70 #include "runtime/java.hpp" 71 #include "runtime/javaCalls.hpp" 72 #include "runtime/jniPeriodicChecker.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/prefetch.inline.hpp" 79 #include "runtime/safepoint.hpp" 80 #include "runtime/sharedRuntime.hpp" 81 #include "runtime/statSampler.hpp" 82 #include "runtime/stubRoutines.hpp" 83 #include "runtime/sweeper.hpp" 84 #include "runtime/task.hpp" 85 #include "runtime/thread.inline.hpp" 86 #include "runtime/threadCritical.hpp" 87 #include "runtime/threadSMR.inline.hpp" 88 #include "runtime/timer.hpp" 89 #include "runtime/timerTrace.hpp" 90 #include "runtime/vframe.hpp" 91 #include "runtime/vframeArray.hpp" 92 #include "runtime/vframe_hp.hpp" 93 #include "runtime/vmThread.hpp" 94 #include "runtime/vm_operations.hpp" 95 #include "runtime/vm_version.hpp" 96 #include "services/attachListener.hpp" 97 #include "services/management.hpp" 98 #include "services/memTracker.hpp" 99 #include "services/threadService.hpp" 100 #include "trace/traceMacros.hpp" 101 #include "trace/tracing.hpp" 102 #include "utilities/align.hpp" 103 #include "utilities/defaultStream.hpp" 104 #include "utilities/dtrace.hpp" 105 #include "utilities/events.hpp" 106 #include "utilities/macros.hpp" 107 #include "utilities/preserveException.hpp" 108 #include "utilities/resourceHash.hpp" 109 #include "utilities/vmError.hpp" 110 #if INCLUDE_ALL_GCS 111 #include "gc/cms/concurrentMarkSweepThread.hpp" 112 #include "gc/g1/concurrentMarkThread.inline.hpp" 113 #include "gc/parallel/pcTasks.hpp" 114 #endif // INCLUDE_ALL_GCS 115 #if INCLUDE_JVMCI 116 #include "jvmci/jvmciCompiler.hpp" 117 #include "jvmci/jvmciRuntime.hpp" 118 #include "logging/logHandle.hpp" 119 #endif 120 #ifdef COMPILER1 121 #include "c1/c1_Compiler.hpp" 122 #endif 123 #ifdef COMPILER2 124 #include "opto/c2compiler.hpp" 125 #include "opto/idealGraphPrinter.hpp" 126 #endif 127 #if INCLUDE_RTM_OPT 128 #include "runtime/rtmLocking.hpp" 129 #endif 130 131 // Initialization after module runtime initialization 132 void universe_post_module_init(); // must happen after call_initPhase2 133 134 #ifdef DTRACE_ENABLED 135 136 // Only bother with this argument setup if dtrace is available 137 138 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 139 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 140 141 #define DTRACE_THREAD_PROBE(probe, javathread) \ 142 { \ 143 ResourceMark rm(this); \ 144 int len = 0; \ 145 const char* name = (javathread)->get_thread_name(); \ 146 len = strlen(name); \ 147 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 148 (char *) name, len, \ 149 java_lang_Thread::thread_id((javathread)->threadObj()), \ 150 (uintptr_t) (javathread)->osthread()->thread_id(), \ 151 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 152 } 153 154 #else // ndef DTRACE_ENABLED 155 156 #define DTRACE_THREAD_PROBE(probe, javathread) 157 158 #endif // ndef DTRACE_ENABLED 159 160 #ifndef USE_LIBRARY_BASED_TLS_ONLY 161 // Current thread is maintained as a thread-local variable 162 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 163 #endif 164 // Class hierarchy 165 // - Thread 166 // - VMThread 167 // - WatcherThread 168 // - ConcurrentMarkSweepThread 169 // - JavaThread 170 // - CompilerThread 171 172 // ======= Thread ======== 173 // Support for forcing alignment of thread objects for biased locking 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 175 if (UseBiasedLocking) { 176 const int alignment = markOopDesc::biased_lock_alignment; 177 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 179 : AllocateHeap(aligned_size, flags, CURRENT_PC, 180 AllocFailStrategy::RETURN_NULL); 181 void* aligned_addr = align_up(real_malloc_addr, alignment); 182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 184 "JavaThread alignment code overflowed allocated storage"); 185 if (aligned_addr != real_malloc_addr) { 186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 187 p2i(real_malloc_addr), 188 p2i(aligned_addr)); 189 } 190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 191 return aligned_addr; 192 } else { 193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 195 } 196 } 197 198 void Thread::operator delete(void* p) { 199 if (UseBiasedLocking) { 200 FreeHeap(((Thread*) p)->_real_malloc_address); 201 } else { 202 FreeHeap(p); 203 } 204 } 205 206 void JavaThread::smr_delete() { 207 if (_on_thread_list) { 208 Threads::smr_delete(this); 209 } else { 210 delete this; 211 } 212 } 213 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 215 // JavaThread 216 217 218 Thread::Thread() { 219 // stack and get_thread 220 set_stack_base(NULL); 221 set_stack_size(0); 222 set_self_raw_id(0); 223 set_lgrp_id(-1); 224 DEBUG_ONLY(clear_suspendible_thread();) 225 226 // allocated data structures 227 set_osthread(NULL); 228 set_resource_area(new (mtThread)ResourceArea()); 229 DEBUG_ONLY(_current_resource_mark = NULL;) 230 set_handle_area(new (mtThread) HandleArea(NULL)); 231 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 232 set_active_handles(NULL); 233 set_free_handle_block(NULL); 234 set_last_handle_mark(NULL); 235 236 // This initial value ==> never claimed. 237 _oops_do_parity = 0; 238 _threads_hazard_ptr = NULL; 239 _nested_threads_hazard_ptr = NULL; 240 _nested_threads_hazard_ptr_cnt = 0; 241 242 // the handle mark links itself to last_handle_mark 243 new HandleMark(this); 244 245 // plain initialization 246 debug_only(_owned_locks = NULL;) 247 debug_only(_allow_allocation_count = 0;) 248 NOT_PRODUCT(_allow_safepoint_count = 0;) 249 NOT_PRODUCT(_skip_gcalot = false;) 250 _jvmti_env_iteration_count = 0; 251 set_allocated_bytes(0); 252 _vm_operation_started_count = 0; 253 _vm_operation_completed_count = 0; 254 _current_pending_monitor = NULL; 255 _current_pending_monitor_is_from_java = true; 256 _current_waiting_monitor = NULL; 257 _num_nested_signal = 0; 258 omFreeList = NULL; 259 omFreeCount = 0; 260 omFreeProvision = 32; 261 omInUseList = NULL; 262 omInUseCount = 0; 263 264 #ifdef ASSERT 265 _visited_for_critical_count = false; 266 #endif 267 268 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 269 Monitor::_safepoint_check_sometimes); 270 _suspend_flags = 0; 271 272 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 273 _hashStateX = os::random(); 274 _hashStateY = 842502087; 275 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 276 _hashStateW = 273326509; 277 278 _OnTrap = 0; 279 _schedctl = NULL; 280 _Stalled = 0; 281 _TypeTag = 0x2BAD; 282 283 // Many of the following fields are effectively final - immutable 284 // Note that nascent threads can't use the Native Monitor-Mutex 285 // construct until the _MutexEvent is initialized ... 286 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 287 // we might instead use a stack of ParkEvents that we could provision on-demand. 288 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 289 // and ::Release() 290 _ParkEvent = ParkEvent::Allocate(this); 291 _SleepEvent = ParkEvent::Allocate(this); 292 _MutexEvent = ParkEvent::Allocate(this); 293 _MuxEvent = ParkEvent::Allocate(this); 294 295 #ifdef CHECK_UNHANDLED_OOPS 296 if (CheckUnhandledOops) { 297 _unhandled_oops = new UnhandledOops(this); 298 } 299 #endif // CHECK_UNHANDLED_OOPS 300 #ifdef ASSERT 301 if (UseBiasedLocking) { 302 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 303 assert(this == _real_malloc_address || 304 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 305 "bug in forced alignment of thread objects"); 306 } 307 #endif // ASSERT 308 } 309 310 void Thread::initialize_thread_current() { 311 #ifndef USE_LIBRARY_BASED_TLS_ONLY 312 assert(_thr_current == NULL, "Thread::current already initialized"); 313 _thr_current = this; 314 #endif 315 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 316 ThreadLocalStorage::set_thread(this); 317 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 318 } 319 320 void Thread::clear_thread_current() { 321 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 322 #ifndef USE_LIBRARY_BASED_TLS_ONLY 323 _thr_current = NULL; 324 #endif 325 ThreadLocalStorage::set_thread(NULL); 326 } 327 328 void Thread::record_stack_base_and_size() { 329 set_stack_base(os::current_stack_base()); 330 set_stack_size(os::current_stack_size()); 331 // CR 7190089: on Solaris, primordial thread's stack is adjusted 332 // in initialize_thread(). Without the adjustment, stack size is 333 // incorrect if stack is set to unlimited (ulimit -s unlimited). 334 // So far, only Solaris has real implementation of initialize_thread(). 335 // 336 // set up any platform-specific state. 337 os::initialize_thread(this); 338 339 // Set stack limits after thread is initialized. 340 if (is_Java_thread()) { 341 ((JavaThread*) this)->set_stack_overflow_limit(); 342 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 343 } 344 #if INCLUDE_NMT 345 // record thread's native stack, stack grows downward 346 MemTracker::record_thread_stack(stack_end(), stack_size()); 347 #endif // INCLUDE_NMT 348 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 349 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 350 os::current_thread_id(), p2i(stack_base() - stack_size()), 351 p2i(stack_base()), stack_size()/1024); 352 } 353 354 355 Thread::~Thread() { 356 EVENT_THREAD_DESTRUCT(this); 357 358 // stack_base can be NULL if the thread is never started or exited before 359 // record_stack_base_and_size called. Although, we would like to ensure 360 // that all started threads do call record_stack_base_and_size(), there is 361 // not proper way to enforce that. 362 #if INCLUDE_NMT 363 if (_stack_base != NULL) { 364 MemTracker::release_thread_stack(stack_end(), stack_size()); 365 #ifdef ASSERT 366 set_stack_base(NULL); 367 #endif 368 } 369 #endif // INCLUDE_NMT 370 371 // deallocate data structures 372 delete resource_area(); 373 // since the handle marks are using the handle area, we have to deallocated the root 374 // handle mark before deallocating the thread's handle area, 375 assert(last_handle_mark() != NULL, "check we have an element"); 376 delete last_handle_mark(); 377 assert(last_handle_mark() == NULL, "check we have reached the end"); 378 379 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 380 // We NULL out the fields for good hygiene. 381 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 382 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 383 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 384 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 385 386 delete handle_area(); 387 delete metadata_handles(); 388 389 // SR_handler uses this as a termination indicator - 390 // needs to happen before os::free_thread() 391 delete _SR_lock; 392 _SR_lock = NULL; 393 394 // osthread() can be NULL, if creation of thread failed. 395 if (osthread() != NULL) os::free_thread(osthread()); 396 397 // clear Thread::current if thread is deleting itself. 398 // Needed to ensure JNI correctly detects non-attached threads. 399 if (this == Thread::current()) { 400 clear_thread_current(); 401 } 402 403 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 404 } 405 406 // NOTE: dummy function for assertion purpose. 407 void Thread::run() { 408 ShouldNotReachHere(); 409 } 410 411 #ifdef ASSERT 412 // A JavaThread is considered "dangling" if it is not the current 413 // thread, has been added the Threads list, the system is not at a 414 // safepoint and the Thread is not "protected". 415 // 416 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 417 assert(!thread->is_Java_thread() || Thread::current() == thread || 418 !((JavaThread *) thread)->on_thread_list() || 419 SafepointSynchronize::is_at_safepoint() || 420 Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 421 "possibility of dangling Thread pointer"); 422 } 423 #endif 424 425 ThreadPriority Thread::get_priority(const Thread* const thread) { 426 ThreadPriority priority; 427 // Can return an error! 428 (void)os::get_priority(thread, priority); 429 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 430 return priority; 431 } 432 433 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 434 debug_only(check_for_dangling_thread_pointer(thread);) 435 // Can return an error! 436 (void)os::set_priority(thread, priority); 437 } 438 439 440 void Thread::start(Thread* thread) { 441 // Start is different from resume in that its safety is guaranteed by context or 442 // being called from a Java method synchronized on the Thread object. 443 if (!DisableStartThread) { 444 if (thread->is_Java_thread()) { 445 // Initialize the thread state to RUNNABLE before starting this thread. 446 // Can not set it after the thread started because we do not know the 447 // exact thread state at that time. It could be in MONITOR_WAIT or 448 // in SLEEPING or some other state. 449 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 450 java_lang_Thread::RUNNABLE); 451 } 452 os::start_thread(thread); 453 } 454 } 455 456 // Enqueue a VM_Operation to do the job for us - sometime later 457 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 458 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 459 VMThread::execute(vm_stop); 460 } 461 462 463 // Check if an external suspend request has completed (or has been 464 // cancelled). Returns true if the thread is externally suspended and 465 // false otherwise. 466 // 467 // The bits parameter returns information about the code path through 468 // the routine. Useful for debugging: 469 // 470 // set in is_ext_suspend_completed(): 471 // 0x00000001 - routine was entered 472 // 0x00000010 - routine return false at end 473 // 0x00000100 - thread exited (return false) 474 // 0x00000200 - suspend request cancelled (return false) 475 // 0x00000400 - thread suspended (return true) 476 // 0x00001000 - thread is in a suspend equivalent state (return true) 477 // 0x00002000 - thread is native and walkable (return true) 478 // 0x00004000 - thread is native_trans and walkable (needed retry) 479 // 480 // set in wait_for_ext_suspend_completion(): 481 // 0x00010000 - routine was entered 482 // 0x00020000 - suspend request cancelled before loop (return false) 483 // 0x00040000 - thread suspended before loop (return true) 484 // 0x00080000 - suspend request cancelled in loop (return false) 485 // 0x00100000 - thread suspended in loop (return true) 486 // 0x00200000 - suspend not completed during retry loop (return false) 487 488 // Helper class for tracing suspend wait debug bits. 489 // 490 // 0x00000100 indicates that the target thread exited before it could 491 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 492 // 0x00080000 each indicate a cancelled suspend request so they don't 493 // count as wait failures either. 494 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 495 496 class TraceSuspendDebugBits : public StackObj { 497 private: 498 JavaThread * jt; 499 bool is_wait; 500 bool called_by_wait; // meaningful when !is_wait 501 uint32_t * bits; 502 503 public: 504 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 505 uint32_t *_bits) { 506 jt = _jt; 507 is_wait = _is_wait; 508 called_by_wait = _called_by_wait; 509 bits = _bits; 510 } 511 512 ~TraceSuspendDebugBits() { 513 if (!is_wait) { 514 #if 1 515 // By default, don't trace bits for is_ext_suspend_completed() calls. 516 // That trace is very chatty. 517 return; 518 #else 519 if (!called_by_wait) { 520 // If tracing for is_ext_suspend_completed() is enabled, then only 521 // trace calls to it from wait_for_ext_suspend_completion() 522 return; 523 } 524 #endif 525 } 526 527 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 528 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 529 MutexLocker ml(Threads_lock); // needed for get_thread_name() 530 ResourceMark rm; 531 532 tty->print_cr( 533 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 534 jt->get_thread_name(), *bits); 535 536 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 537 } 538 } 539 } 540 }; 541 #undef DEBUG_FALSE_BITS 542 543 544 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 545 uint32_t *bits) { 546 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 547 548 bool did_trans_retry = false; // only do thread_in_native_trans retry once 549 bool do_trans_retry; // flag to force the retry 550 551 *bits |= 0x00000001; 552 553 do { 554 do_trans_retry = false; 555 556 if (is_exiting()) { 557 // Thread is in the process of exiting. This is always checked 558 // first to reduce the risk of dereferencing a freed JavaThread. 559 *bits |= 0x00000100; 560 return false; 561 } 562 563 if (!is_external_suspend()) { 564 // Suspend request is cancelled. This is always checked before 565 // is_ext_suspended() to reduce the risk of a rogue resume 566 // confusing the thread that made the suspend request. 567 *bits |= 0x00000200; 568 return false; 569 } 570 571 if (is_ext_suspended()) { 572 // thread is suspended 573 *bits |= 0x00000400; 574 return true; 575 } 576 577 // Now that we no longer do hard suspends of threads running 578 // native code, the target thread can be changing thread state 579 // while we are in this routine: 580 // 581 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 582 // 583 // We save a copy of the thread state as observed at this moment 584 // and make our decision about suspend completeness based on the 585 // copy. This closes the race where the thread state is seen as 586 // _thread_in_native_trans in the if-thread_blocked check, but is 587 // seen as _thread_blocked in if-thread_in_native_trans check. 588 JavaThreadState save_state = thread_state(); 589 590 if (save_state == _thread_blocked && is_suspend_equivalent()) { 591 // If the thread's state is _thread_blocked and this blocking 592 // condition is known to be equivalent to a suspend, then we can 593 // consider the thread to be externally suspended. This means that 594 // the code that sets _thread_blocked has been modified to do 595 // self-suspension if the blocking condition releases. We also 596 // used to check for CONDVAR_WAIT here, but that is now covered by 597 // the _thread_blocked with self-suspension check. 598 // 599 // Return true since we wouldn't be here unless there was still an 600 // external suspend request. 601 *bits |= 0x00001000; 602 return true; 603 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 604 // Threads running native code will self-suspend on native==>VM/Java 605 // transitions. If its stack is walkable (should always be the case 606 // unless this function is called before the actual java_suspend() 607 // call), then the wait is done. 608 *bits |= 0x00002000; 609 return true; 610 } else if (!called_by_wait && !did_trans_retry && 611 save_state == _thread_in_native_trans && 612 frame_anchor()->walkable()) { 613 // The thread is transitioning from thread_in_native to another 614 // thread state. check_safepoint_and_suspend_for_native_trans() 615 // will force the thread to self-suspend. If it hasn't gotten 616 // there yet we may have caught the thread in-between the native 617 // code check above and the self-suspend. Lucky us. If we were 618 // called by wait_for_ext_suspend_completion(), then it 619 // will be doing the retries so we don't have to. 620 // 621 // Since we use the saved thread state in the if-statement above, 622 // there is a chance that the thread has already transitioned to 623 // _thread_blocked by the time we get here. In that case, we will 624 // make a single unnecessary pass through the logic below. This 625 // doesn't hurt anything since we still do the trans retry. 626 627 *bits |= 0x00004000; 628 629 // Once the thread leaves thread_in_native_trans for another 630 // thread state, we break out of this retry loop. We shouldn't 631 // need this flag to prevent us from getting back here, but 632 // sometimes paranoia is good. 633 did_trans_retry = true; 634 635 // We wait for the thread to transition to a more usable state. 636 for (int i = 1; i <= SuspendRetryCount; i++) { 637 // We used to do an "os::yield_all(i)" call here with the intention 638 // that yielding would increase on each retry. However, the parameter 639 // is ignored on Linux which means the yield didn't scale up. Waiting 640 // on the SR_lock below provides a much more predictable scale up for 641 // the delay. It also provides a simple/direct point to check for any 642 // safepoint requests from the VMThread 643 644 // temporarily drops SR_lock while doing wait with safepoint check 645 // (if we're a JavaThread - the WatcherThread can also call this) 646 // and increase delay with each retry 647 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 648 649 // check the actual thread state instead of what we saved above 650 if (thread_state() != _thread_in_native_trans) { 651 // the thread has transitioned to another thread state so 652 // try all the checks (except this one) one more time. 653 do_trans_retry = true; 654 break; 655 } 656 } // end retry loop 657 658 659 } 660 } while (do_trans_retry); 661 662 *bits |= 0x00000010; 663 return false; 664 } 665 666 // Wait for an external suspend request to complete (or be cancelled). 667 // Returns true if the thread is externally suspended and false otherwise. 668 // 669 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 670 uint32_t *bits) { 671 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 672 false /* !called_by_wait */, bits); 673 674 // local flag copies to minimize SR_lock hold time 675 bool is_suspended; 676 bool pending; 677 uint32_t reset_bits; 678 679 // set a marker so is_ext_suspend_completed() knows we are the caller 680 *bits |= 0x00010000; 681 682 // We use reset_bits to reinitialize the bits value at the top of 683 // each retry loop. This allows the caller to make use of any 684 // unused bits for their own marking purposes. 685 reset_bits = *bits; 686 687 { 688 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 689 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 690 delay, bits); 691 pending = is_external_suspend(); 692 } 693 // must release SR_lock to allow suspension to complete 694 695 if (!pending) { 696 // A cancelled suspend request is the only false return from 697 // is_ext_suspend_completed() that keeps us from entering the 698 // retry loop. 699 *bits |= 0x00020000; 700 return false; 701 } 702 703 if (is_suspended) { 704 *bits |= 0x00040000; 705 return true; 706 } 707 708 for (int i = 1; i <= retries; i++) { 709 *bits = reset_bits; // reinit to only track last retry 710 711 // We used to do an "os::yield_all(i)" call here with the intention 712 // that yielding would increase on each retry. However, the parameter 713 // is ignored on Linux which means the yield didn't scale up. Waiting 714 // on the SR_lock below provides a much more predictable scale up for 715 // the delay. It also provides a simple/direct point to check for any 716 // safepoint requests from the VMThread 717 718 { 719 MutexLocker ml(SR_lock()); 720 // wait with safepoint check (if we're a JavaThread - the WatcherThread 721 // can also call this) and increase delay with each retry 722 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 723 724 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 725 delay, bits); 726 727 // It is possible for the external suspend request to be cancelled 728 // (by a resume) before the actual suspend operation is completed. 729 // Refresh our local copy to see if we still need to wait. 730 pending = is_external_suspend(); 731 } 732 733 if (!pending) { 734 // A cancelled suspend request is the only false return from 735 // is_ext_suspend_completed() that keeps us from staying in the 736 // retry loop. 737 *bits |= 0x00080000; 738 return false; 739 } 740 741 if (is_suspended) { 742 *bits |= 0x00100000; 743 return true; 744 } 745 } // end retry loop 746 747 // thread did not suspend after all our retries 748 *bits |= 0x00200000; 749 return false; 750 } 751 752 // Called from API entry points which perform stack walking. If the 753 // associated JavaThread is the current thread, then wait_for_suspend 754 // is not used. Otherwise, it determines if we should wait for the 755 // "other" thread to complete external suspension. (NOTE: in future 756 // releases the suspension mechanism should be reimplemented so this 757 // is not necessary.) 758 // 759 bool 760 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 761 if (this != JavaThread::current()) { 762 // "other" threads require special handling. 763 if (wait_for_suspend) { 764 // We are allowed to wait for the external suspend to complete 765 // so give the other thread a chance to get suspended. 766 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 767 SuspendRetryDelay, bits)) { 768 // Didn't make it so let the caller know. 769 return false; 770 } 771 } 772 // We aren't allowed to wait for the external suspend to complete 773 // so if the other thread isn't externally suspended we need to 774 // let the caller know. 775 else if (!is_ext_suspend_completed_with_lock(bits)) { 776 return false; 777 } 778 } 779 780 return true; 781 } 782 783 #ifndef PRODUCT 784 void JavaThread::record_jump(address target, address instr, const char* file, 785 int line) { 786 787 // This should not need to be atomic as the only way for simultaneous 788 // updates is via interrupts. Even then this should be rare or non-existent 789 // and we don't care that much anyway. 790 791 int index = _jmp_ring_index; 792 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 793 _jmp_ring[index]._target = (intptr_t) target; 794 _jmp_ring[index]._instruction = (intptr_t) instr; 795 _jmp_ring[index]._file = file; 796 _jmp_ring[index]._line = line; 797 } 798 #endif // PRODUCT 799 800 void Thread::interrupt(Thread* thread) { 801 debug_only(check_for_dangling_thread_pointer(thread);) 802 os::interrupt(thread); 803 } 804 805 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 806 debug_only(check_for_dangling_thread_pointer(thread);) 807 // Note: If clear_interrupted==false, this simply fetches and 808 // returns the value of the field osthread()->interrupted(). 809 return os::is_interrupted(thread, clear_interrupted); 810 } 811 812 813 // GC Support 814 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 815 jint thread_parity = _oops_do_parity; 816 if (thread_parity != strong_roots_parity) { 817 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 818 if (res == thread_parity) { 819 return true; 820 } else { 821 guarantee(res == strong_roots_parity, "Or else what?"); 822 return false; 823 } 824 } 825 return false; 826 } 827 828 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 829 active_handles()->oops_do(f); 830 // Do oop for ThreadShadow 831 f->do_oop((oop*)&_pending_exception); 832 handle_area()->oops_do(f); 833 834 if (MonitorInUseLists) { 835 // When using thread local monitor lists, we scan them here, 836 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 837 ObjectSynchronizer::thread_local_used_oops_do(this, f); 838 } 839 } 840 841 void Thread::metadata_handles_do(void f(Metadata*)) { 842 // Only walk the Handles in Thread. 843 if (metadata_handles() != NULL) { 844 for (int i = 0; i< metadata_handles()->length(); i++) { 845 f(metadata_handles()->at(i)); 846 } 847 } 848 } 849 850 void Thread::print_on(outputStream* st) const { 851 // get_priority assumes osthread initialized 852 if (osthread() != NULL) { 853 int os_prio; 854 if (os::get_native_priority(this, &os_prio) == OS_OK) { 855 st->print("os_prio=%d ", os_prio); 856 } 857 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 858 ext().print_on(st); 859 osthread()->print_on(st); 860 } 861 if (_threads_hazard_ptr != NULL) { 862 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 863 } 864 if (_nested_threads_hazard_ptr != NULL) { 865 print_nested_threads_hazard_ptrs_on(st); 866 } 867 st->print(" "); 868 debug_only(if (WizardMode) print_owned_locks_on(st);) 869 } 870 871 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 872 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 873 874 if (EnableThreadSMRStatistics) { 875 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 876 } 877 st->print(", _nested_threads_hazard_ptrs="); 878 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 879 node = node->next()) { 880 if (node != _nested_threads_hazard_ptr) { 881 // First node does not need a comma-space separator. 882 st->print(", "); 883 } 884 st->print(INTPTR_FORMAT, p2i(node->t_list())); 885 } 886 } 887 888 // Thread::print_on_error() is called by fatal error handler. Don't use 889 // any lock or allocate memory. 890 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 891 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 892 893 if (is_VM_thread()) { st->print("VMThread"); } 894 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 895 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 896 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 897 else { st->print("Thread"); } 898 899 if (is_Named_thread()) { 900 st->print(" \"%s\"", name()); 901 } 902 903 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 904 p2i(stack_end()), p2i(stack_base())); 905 906 if (osthread()) { 907 st->print(" [id=%d]", osthread()->thread_id()); 908 } 909 910 if (_threads_hazard_ptr != NULL) { 911 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 912 } 913 if (_nested_threads_hazard_ptr != NULL) { 914 print_nested_threads_hazard_ptrs_on(st); 915 } 916 } 917 918 void Thread::print_value_on(outputStream* st) const { 919 if (is_Named_thread()) { 920 st->print(" \"%s\" ", name()); 921 } 922 st->print(INTPTR_FORMAT, p2i(this)); // print address 923 } 924 925 #ifdef ASSERT 926 void Thread::print_owned_locks_on(outputStream* st) const { 927 Monitor *cur = _owned_locks; 928 if (cur == NULL) { 929 st->print(" (no locks) "); 930 } else { 931 st->print_cr(" Locks owned:"); 932 while (cur) { 933 cur->print_on(st); 934 cur = cur->next(); 935 } 936 } 937 } 938 939 static int ref_use_count = 0; 940 941 bool Thread::owns_locks_but_compiled_lock() const { 942 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 943 if (cur != Compile_lock) return true; 944 } 945 return false; 946 } 947 948 949 #endif 950 951 #ifndef PRODUCT 952 953 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 954 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 955 // no threads which allow_vm_block's are held 956 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 957 // Check if current thread is allowed to block at a safepoint 958 if (!(_allow_safepoint_count == 0)) { 959 fatal("Possible safepoint reached by thread that does not allow it"); 960 } 961 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 962 fatal("LEAF method calling lock?"); 963 } 964 965 #ifdef ASSERT 966 if (potential_vm_operation && is_Java_thread() 967 && !Universe::is_bootstrapping()) { 968 // Make sure we do not hold any locks that the VM thread also uses. 969 // This could potentially lead to deadlocks 970 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 971 // Threads_lock is special, since the safepoint synchronization will not start before this is 972 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 973 // since it is used to transfer control between JavaThreads and the VMThread 974 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 975 if ((cur->allow_vm_block() && 976 cur != Threads_lock && 977 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 978 cur != VMOperationRequest_lock && 979 cur != VMOperationQueue_lock) || 980 cur->rank() == Mutex::special) { 981 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 982 } 983 } 984 } 985 986 if (GCALotAtAllSafepoints) { 987 // We could enter a safepoint here and thus have a gc 988 InterfaceSupport::check_gc_alot(); 989 } 990 #endif 991 } 992 #endif 993 994 bool Thread::is_in_stack(address adr) const { 995 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 996 address end = os::current_stack_pointer(); 997 // Allow non Java threads to call this without stack_base 998 if (_stack_base == NULL) return true; 999 if (stack_base() >= adr && adr >= end) return true; 1000 1001 return false; 1002 } 1003 1004 bool Thread::is_in_usable_stack(address adr) const { 1005 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1006 size_t usable_stack_size = _stack_size - stack_guard_size; 1007 1008 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1009 } 1010 1011 1012 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1013 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1014 // used for compilation in the future. If that change is made, the need for these methods 1015 // should be revisited, and they should be removed if possible. 1016 1017 bool Thread::is_lock_owned(address adr) const { 1018 return on_local_stack(adr); 1019 } 1020 1021 bool Thread::set_as_starting_thread() { 1022 // NOTE: this must be called inside the main thread. 1023 return os::create_main_thread((JavaThread*)this); 1024 } 1025 1026 static void initialize_class(Symbol* class_name, TRAPS) { 1027 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1028 InstanceKlass::cast(klass)->initialize(CHECK); 1029 } 1030 1031 1032 // Creates the initial ThreadGroup 1033 static Handle create_initial_thread_group(TRAPS) { 1034 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1035 InstanceKlass* ik = InstanceKlass::cast(k); 1036 1037 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1038 { 1039 JavaValue result(T_VOID); 1040 JavaCalls::call_special(&result, 1041 system_instance, 1042 ik, 1043 vmSymbols::object_initializer_name(), 1044 vmSymbols::void_method_signature(), 1045 CHECK_NH); 1046 } 1047 Universe::set_system_thread_group(system_instance()); 1048 1049 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1050 { 1051 JavaValue result(T_VOID); 1052 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1053 JavaCalls::call_special(&result, 1054 main_instance, 1055 ik, 1056 vmSymbols::object_initializer_name(), 1057 vmSymbols::threadgroup_string_void_signature(), 1058 system_instance, 1059 string, 1060 CHECK_NH); 1061 } 1062 return main_instance; 1063 } 1064 1065 // Creates the initial Thread 1066 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1067 TRAPS) { 1068 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1069 InstanceKlass* ik = InstanceKlass::cast(k); 1070 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1071 1072 java_lang_Thread::set_thread(thread_oop(), thread); 1073 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1074 thread->set_threadObj(thread_oop()); 1075 1076 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1077 1078 JavaValue result(T_VOID); 1079 JavaCalls::call_special(&result, thread_oop, 1080 ik, 1081 vmSymbols::object_initializer_name(), 1082 vmSymbols::threadgroup_string_void_signature(), 1083 thread_group, 1084 string, 1085 CHECK_NULL); 1086 return thread_oop(); 1087 } 1088 1089 char java_runtime_name[128] = ""; 1090 char java_runtime_version[128] = ""; 1091 1092 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1093 static const char* get_java_runtime_name(TRAPS) { 1094 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1095 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1096 fieldDescriptor fd; 1097 bool found = k != NULL && 1098 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1099 vmSymbols::string_signature(), &fd); 1100 if (found) { 1101 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1102 if (name_oop == NULL) { 1103 return NULL; 1104 } 1105 const char* name = java_lang_String::as_utf8_string(name_oop, 1106 java_runtime_name, 1107 sizeof(java_runtime_name)); 1108 return name; 1109 } else { 1110 return NULL; 1111 } 1112 } 1113 1114 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1115 static const char* get_java_runtime_version(TRAPS) { 1116 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1117 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1118 fieldDescriptor fd; 1119 bool found = k != NULL && 1120 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1121 vmSymbols::string_signature(), &fd); 1122 if (found) { 1123 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1124 if (name_oop == NULL) { 1125 return NULL; 1126 } 1127 const char* name = java_lang_String::as_utf8_string(name_oop, 1128 java_runtime_version, 1129 sizeof(java_runtime_version)); 1130 return name; 1131 } else { 1132 return NULL; 1133 } 1134 } 1135 1136 // General purpose hook into Java code, run once when the VM is initialized. 1137 // The Java library method itself may be changed independently from the VM. 1138 static void call_postVMInitHook(TRAPS) { 1139 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1140 if (klass != NULL) { 1141 JavaValue result(T_VOID); 1142 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1143 vmSymbols::void_method_signature(), 1144 CHECK); 1145 } 1146 } 1147 1148 static void reset_vm_info_property(TRAPS) { 1149 // the vm info string 1150 ResourceMark rm(THREAD); 1151 const char *vm_info = VM_Version::vm_info_string(); 1152 1153 // java.lang.System class 1154 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1155 1156 // setProperty arguments 1157 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1158 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1159 1160 // return value 1161 JavaValue r(T_OBJECT); 1162 1163 // public static String setProperty(String key, String value); 1164 JavaCalls::call_static(&r, 1165 klass, 1166 vmSymbols::setProperty_name(), 1167 vmSymbols::string_string_string_signature(), 1168 key_str, 1169 value_str, 1170 CHECK); 1171 } 1172 1173 1174 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1175 bool daemon, TRAPS) { 1176 assert(thread_group.not_null(), "thread group should be specified"); 1177 assert(threadObj() == NULL, "should only create Java thread object once"); 1178 1179 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1180 InstanceKlass* ik = InstanceKlass::cast(k); 1181 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1182 1183 java_lang_Thread::set_thread(thread_oop(), this); 1184 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1185 set_threadObj(thread_oop()); 1186 1187 JavaValue result(T_VOID); 1188 if (thread_name != NULL) { 1189 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1190 // Thread gets assigned specified name and null target 1191 JavaCalls::call_special(&result, 1192 thread_oop, 1193 ik, 1194 vmSymbols::object_initializer_name(), 1195 vmSymbols::threadgroup_string_void_signature(), 1196 thread_group, // Argument 1 1197 name, // Argument 2 1198 THREAD); 1199 } else { 1200 // Thread gets assigned name "Thread-nnn" and null target 1201 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1202 JavaCalls::call_special(&result, 1203 thread_oop, 1204 ik, 1205 vmSymbols::object_initializer_name(), 1206 vmSymbols::threadgroup_runnable_void_signature(), 1207 thread_group, // Argument 1 1208 Handle(), // Argument 2 1209 THREAD); 1210 } 1211 1212 1213 if (daemon) { 1214 java_lang_Thread::set_daemon(thread_oop()); 1215 } 1216 1217 if (HAS_PENDING_EXCEPTION) { 1218 return; 1219 } 1220 1221 Klass* group = SystemDictionary::ThreadGroup_klass(); 1222 Handle threadObj(THREAD, this->threadObj()); 1223 1224 JavaCalls::call_special(&result, 1225 thread_group, 1226 group, 1227 vmSymbols::add_method_name(), 1228 vmSymbols::thread_void_signature(), 1229 threadObj, // Arg 1 1230 THREAD); 1231 } 1232 1233 // NamedThread -- non-JavaThread subclasses with multiple 1234 // uniquely named instances should derive from this. 1235 NamedThread::NamedThread() : Thread() { 1236 _name = NULL; 1237 _processed_thread = NULL; 1238 _gc_id = GCId::undefined(); 1239 } 1240 1241 NamedThread::~NamedThread() { 1242 if (_name != NULL) { 1243 FREE_C_HEAP_ARRAY(char, _name); 1244 _name = NULL; 1245 } 1246 } 1247 1248 void NamedThread::set_name(const char* format, ...) { 1249 guarantee(_name == NULL, "Only get to set name once."); 1250 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1251 guarantee(_name != NULL, "alloc failure"); 1252 va_list ap; 1253 va_start(ap, format); 1254 jio_vsnprintf(_name, max_name_len, format, ap); 1255 va_end(ap); 1256 } 1257 1258 void NamedThread::initialize_named_thread() { 1259 set_native_thread_name(name()); 1260 } 1261 1262 void NamedThread::print_on(outputStream* st) const { 1263 st->print("\"%s\" ", name()); 1264 Thread::print_on(st); 1265 st->cr(); 1266 } 1267 1268 1269 // ======= WatcherThread ======== 1270 1271 // The watcher thread exists to simulate timer interrupts. It should 1272 // be replaced by an abstraction over whatever native support for 1273 // timer interrupts exists on the platform. 1274 1275 WatcherThread* WatcherThread::_watcher_thread = NULL; 1276 bool WatcherThread::_startable = false; 1277 volatile bool WatcherThread::_should_terminate = false; 1278 1279 WatcherThread::WatcherThread() : Thread() { 1280 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1281 if (os::create_thread(this, os::watcher_thread)) { 1282 _watcher_thread = this; 1283 1284 // Set the watcher thread to the highest OS priority which should not be 1285 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1286 // is created. The only normal thread using this priority is the reference 1287 // handler thread, which runs for very short intervals only. 1288 // If the VMThread's priority is not lower than the WatcherThread profiling 1289 // will be inaccurate. 1290 os::set_priority(this, MaxPriority); 1291 if (!DisableStartThread) { 1292 os::start_thread(this); 1293 } 1294 } 1295 } 1296 1297 int WatcherThread::sleep() const { 1298 // The WatcherThread does not participate in the safepoint protocol 1299 // for the PeriodicTask_lock because it is not a JavaThread. 1300 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1301 1302 if (_should_terminate) { 1303 // check for termination before we do any housekeeping or wait 1304 return 0; // we did not sleep. 1305 } 1306 1307 // remaining will be zero if there are no tasks, 1308 // causing the WatcherThread to sleep until a task is 1309 // enrolled 1310 int remaining = PeriodicTask::time_to_wait(); 1311 int time_slept = 0; 1312 1313 // we expect this to timeout - we only ever get unparked when 1314 // we should terminate or when a new task has been enrolled 1315 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1316 1317 jlong time_before_loop = os::javaTimeNanos(); 1318 1319 while (true) { 1320 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1321 remaining); 1322 jlong now = os::javaTimeNanos(); 1323 1324 if (remaining == 0) { 1325 // if we didn't have any tasks we could have waited for a long time 1326 // consider the time_slept zero and reset time_before_loop 1327 time_slept = 0; 1328 time_before_loop = now; 1329 } else { 1330 // need to recalculate since we might have new tasks in _tasks 1331 time_slept = (int) ((now - time_before_loop) / 1000000); 1332 } 1333 1334 // Change to task list or spurious wakeup of some kind 1335 if (timedout || _should_terminate) { 1336 break; 1337 } 1338 1339 remaining = PeriodicTask::time_to_wait(); 1340 if (remaining == 0) { 1341 // Last task was just disenrolled so loop around and wait until 1342 // another task gets enrolled 1343 continue; 1344 } 1345 1346 remaining -= time_slept; 1347 if (remaining <= 0) { 1348 break; 1349 } 1350 } 1351 1352 return time_slept; 1353 } 1354 1355 void WatcherThread::run() { 1356 assert(this == watcher_thread(), "just checking"); 1357 1358 this->record_stack_base_and_size(); 1359 this->set_native_thread_name(this->name()); 1360 this->set_active_handles(JNIHandleBlock::allocate_block()); 1361 while (true) { 1362 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1363 assert(watcher_thread() == this, "thread consistency check"); 1364 1365 // Calculate how long it'll be until the next PeriodicTask work 1366 // should be done, and sleep that amount of time. 1367 int time_waited = sleep(); 1368 1369 if (VMError::is_error_reported()) { 1370 // A fatal error has happened, the error handler(VMError::report_and_die) 1371 // should abort JVM after creating an error log file. However in some 1372 // rare cases, the error handler itself might deadlock. Here periodically 1373 // check for error reporting timeouts, and if it happens, just proceed to 1374 // abort the VM. 1375 1376 // This code is in WatcherThread because WatcherThread wakes up 1377 // periodically so the fatal error handler doesn't need to do anything; 1378 // also because the WatcherThread is less likely to crash than other 1379 // threads. 1380 1381 for (;;) { 1382 // Note: we use naked sleep in this loop because we want to avoid using 1383 // any kind of VM infrastructure which may be broken at this point. 1384 if (VMError::check_timeout()) { 1385 // We hit error reporting timeout. Error reporting was interrupted and 1386 // will be wrapping things up now (closing files etc). Give it some more 1387 // time, then quit the VM. 1388 os::naked_short_sleep(200); 1389 // Print a message to stderr. 1390 fdStream err(defaultStream::output_fd()); 1391 err.print_raw_cr("# [ timer expired, abort... ]"); 1392 // skip atexit/vm_exit/vm_abort hooks 1393 os::die(); 1394 } 1395 1396 // Wait a second, then recheck for timeout. 1397 os::naked_short_sleep(999); 1398 } 1399 } 1400 1401 if (_should_terminate) { 1402 // check for termination before posting the next tick 1403 break; 1404 } 1405 1406 PeriodicTask::real_time_tick(time_waited); 1407 } 1408 1409 // Signal that it is terminated 1410 { 1411 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1412 _watcher_thread = NULL; 1413 Terminator_lock->notify(); 1414 } 1415 } 1416 1417 void WatcherThread::start() { 1418 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1419 1420 if (watcher_thread() == NULL && _startable) { 1421 _should_terminate = false; 1422 // Create the single instance of WatcherThread 1423 new WatcherThread(); 1424 } 1425 } 1426 1427 void WatcherThread::make_startable() { 1428 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1429 _startable = true; 1430 } 1431 1432 void WatcherThread::stop() { 1433 { 1434 // Follow normal safepoint aware lock enter protocol since the 1435 // WatcherThread is stopped by another JavaThread. 1436 MutexLocker ml(PeriodicTask_lock); 1437 _should_terminate = true; 1438 1439 WatcherThread* watcher = watcher_thread(); 1440 if (watcher != NULL) { 1441 // unpark the WatcherThread so it can see that it should terminate 1442 watcher->unpark(); 1443 } 1444 } 1445 1446 MutexLocker mu(Terminator_lock); 1447 1448 while (watcher_thread() != NULL) { 1449 // This wait should make safepoint checks, wait without a timeout, 1450 // and wait as a suspend-equivalent condition. 1451 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1452 Mutex::_as_suspend_equivalent_flag); 1453 } 1454 } 1455 1456 void WatcherThread::unpark() { 1457 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1458 PeriodicTask_lock->notify(); 1459 } 1460 1461 void WatcherThread::print_on(outputStream* st) const { 1462 st->print("\"%s\" ", name()); 1463 Thread::print_on(st); 1464 st->cr(); 1465 } 1466 1467 // ======= JavaThread ======== 1468 1469 #if INCLUDE_JVMCI 1470 1471 jlong* JavaThread::_jvmci_old_thread_counters; 1472 1473 bool jvmci_counters_include(JavaThread* thread) { 1474 oop threadObj = thread->threadObj(); 1475 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1476 } 1477 1478 void JavaThread::collect_counters(typeArrayOop array) { 1479 if (JVMCICounterSize > 0) { 1480 // dcubed - Looks like the Threads_lock is for stable access 1481 // to _jvmci_old_thread_counters and _jvmci_counters. 1482 MutexLocker tl(Threads_lock); 1483 ThreadsListHandle tlh; 1484 for (int i = 0; i < array->length(); i++) { 1485 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1486 } 1487 JavaThreadIterator jti(tlh.list()); 1488 for (JavaThread* tp = jti.first(); tp != NULL; tp = jti.next()) { 1489 if (jvmci_counters_include(tp)) { 1490 for (int i = 0; i < array->length(); i++) { 1491 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1492 } 1493 } 1494 } 1495 } 1496 } 1497 1498 #endif // INCLUDE_JVMCI 1499 1500 // A JavaThread is a normal Java thread 1501 1502 void JavaThread::initialize() { 1503 // Initialize fields 1504 1505 set_saved_exception_pc(NULL); 1506 set_threadObj(NULL); 1507 _anchor.clear(); 1508 set_entry_point(NULL); 1509 set_jni_functions(jni_functions()); 1510 set_callee_target(NULL); 1511 set_vm_result(NULL); 1512 set_vm_result_2(NULL); 1513 set_vframe_array_head(NULL); 1514 set_vframe_array_last(NULL); 1515 set_deferred_locals(NULL); 1516 set_deopt_mark(NULL); 1517 set_deopt_compiled_method(NULL); 1518 clear_must_deopt_id(); 1519 set_monitor_chunks(NULL); 1520 set_next(NULL); 1521 _on_thread_list = false; 1522 set_thread_state(_thread_new); 1523 _terminated = _not_terminated; 1524 _privileged_stack_top = NULL; 1525 _array_for_gc = NULL; 1526 _suspend_equivalent = false; 1527 _in_deopt_handler = 0; 1528 _doing_unsafe_access = false; 1529 _stack_guard_state = stack_guard_unused; 1530 #if INCLUDE_JVMCI 1531 _pending_monitorenter = false; 1532 _pending_deoptimization = -1; 1533 _pending_failed_speculation = NULL; 1534 _pending_transfer_to_interpreter = false; 1535 _adjusting_comp_level = false; 1536 _jvmci._alternate_call_target = NULL; 1537 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1538 if (JVMCICounterSize > 0) { 1539 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1540 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1541 } else { 1542 _jvmci_counters = NULL; 1543 } 1544 #endif // INCLUDE_JVMCI 1545 _reserved_stack_activation = NULL; // stack base not known yet 1546 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1547 _exception_pc = 0; 1548 _exception_handler_pc = 0; 1549 _is_method_handle_return = 0; 1550 _jvmti_thread_state= NULL; 1551 _should_post_on_exceptions_flag = JNI_FALSE; 1552 _jvmti_get_loaded_classes_closure = NULL; 1553 _interp_only_mode = 0; 1554 _special_runtime_exit_condition = _no_async_condition; 1555 _pending_async_exception = NULL; 1556 _thread_stat = NULL; 1557 _thread_stat = new ThreadStatistics(); 1558 _blocked_on_compilation = false; 1559 _jni_active_critical = 0; 1560 _pending_jni_exception_check_fn = NULL; 1561 _do_not_unlock_if_synchronized = false; 1562 _cached_monitor_info = NULL; 1563 _parker = Parker::Allocate(this); 1564 1565 #ifndef PRODUCT 1566 _jmp_ring_index = 0; 1567 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1568 record_jump(NULL, NULL, NULL, 0); 1569 } 1570 #endif // PRODUCT 1571 1572 // Setup safepoint state info for this thread 1573 ThreadSafepointState::create(this); 1574 1575 debug_only(_java_call_counter = 0); 1576 1577 // JVMTI PopFrame support 1578 _popframe_condition = popframe_inactive; 1579 _popframe_preserved_args = NULL; 1580 _popframe_preserved_args_size = 0; 1581 _frames_to_pop_failed_realloc = 0; 1582 1583 pd_initialize(); 1584 } 1585 1586 #if INCLUDE_ALL_GCS 1587 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1588 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1589 #endif // INCLUDE_ALL_GCS 1590 1591 JavaThread::JavaThread(bool is_attaching_via_jni) : 1592 Thread() 1593 #if INCLUDE_ALL_GCS 1594 , _satb_mark_queue(&_satb_mark_queue_set), 1595 _dirty_card_queue(&_dirty_card_queue_set) 1596 #endif // INCLUDE_ALL_GCS 1597 { 1598 initialize(); 1599 if (is_attaching_via_jni) { 1600 _jni_attach_state = _attaching_via_jni; 1601 } else { 1602 _jni_attach_state = _not_attaching_via_jni; 1603 } 1604 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1605 } 1606 1607 bool JavaThread::reguard_stack(address cur_sp) { 1608 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1609 && _stack_guard_state != stack_guard_reserved_disabled) { 1610 return true; // Stack already guarded or guard pages not needed. 1611 } 1612 1613 if (register_stack_overflow()) { 1614 // For those architectures which have separate register and 1615 // memory stacks, we must check the register stack to see if 1616 // it has overflowed. 1617 return false; 1618 } 1619 1620 // Java code never executes within the yellow zone: the latter is only 1621 // there to provoke an exception during stack banging. If java code 1622 // is executing there, either StackShadowPages should be larger, or 1623 // some exception code in c1, c2 or the interpreter isn't unwinding 1624 // when it should. 1625 guarantee(cur_sp > stack_reserved_zone_base(), 1626 "not enough space to reguard - increase StackShadowPages"); 1627 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1628 enable_stack_yellow_reserved_zone(); 1629 if (reserved_stack_activation() != stack_base()) { 1630 set_reserved_stack_activation(stack_base()); 1631 } 1632 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1633 set_reserved_stack_activation(stack_base()); 1634 enable_stack_reserved_zone(); 1635 } 1636 return true; 1637 } 1638 1639 bool JavaThread::reguard_stack(void) { 1640 return reguard_stack(os::current_stack_pointer()); 1641 } 1642 1643 1644 void JavaThread::block_if_vm_exited() { 1645 if (_terminated == _vm_exited) { 1646 // _vm_exited is set at safepoint, and Threads_lock is never released 1647 // we will block here forever 1648 Threads_lock->lock_without_safepoint_check(); 1649 ShouldNotReachHere(); 1650 } 1651 } 1652 1653 1654 // Remove this ifdef when C1 is ported to the compiler interface. 1655 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1656 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1657 1658 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1659 Thread() 1660 #if INCLUDE_ALL_GCS 1661 , _satb_mark_queue(&_satb_mark_queue_set), 1662 _dirty_card_queue(&_dirty_card_queue_set) 1663 #endif // INCLUDE_ALL_GCS 1664 { 1665 initialize(); 1666 _jni_attach_state = _not_attaching_via_jni; 1667 set_entry_point(entry_point); 1668 // Create the native thread itself. 1669 // %note runtime_23 1670 os::ThreadType thr_type = os::java_thread; 1671 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1672 os::java_thread; 1673 os::create_thread(this, thr_type, stack_sz); 1674 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1675 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1676 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1677 // the exception consists of creating the exception object & initializing it, initialization 1678 // will leave the VM via a JavaCall and then all locks must be unlocked). 1679 // 1680 // The thread is still suspended when we reach here. Thread must be explicit started 1681 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1682 // by calling Threads:add. The reason why this is not done here, is because the thread 1683 // object must be fully initialized (take a look at JVM_Start) 1684 } 1685 1686 JavaThread::~JavaThread() { 1687 1688 // JSR166 -- return the parker to the free list 1689 Parker::Release(_parker); 1690 _parker = NULL; 1691 1692 // Free any remaining previous UnrollBlock 1693 vframeArray* old_array = vframe_array_last(); 1694 1695 if (old_array != NULL) { 1696 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1697 old_array->set_unroll_block(NULL); 1698 delete old_info; 1699 delete old_array; 1700 } 1701 1702 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1703 if (deferred != NULL) { 1704 // This can only happen if thread is destroyed before deoptimization occurs. 1705 assert(deferred->length() != 0, "empty array!"); 1706 do { 1707 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1708 deferred->remove_at(0); 1709 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1710 delete dlv; 1711 } while (deferred->length() != 0); 1712 delete deferred; 1713 } 1714 1715 // All Java related clean up happens in exit 1716 ThreadSafepointState::destroy(this); 1717 if (_thread_stat != NULL) delete _thread_stat; 1718 1719 #if INCLUDE_JVMCI 1720 if (JVMCICounterSize > 0) { 1721 if (jvmci_counters_include(this)) { 1722 for (int i = 0; i < JVMCICounterSize; i++) { 1723 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1724 } 1725 } 1726 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1727 } 1728 #endif // INCLUDE_JVMCI 1729 } 1730 1731 1732 // The first routine called by a new Java thread 1733 void JavaThread::run() { 1734 // initialize thread-local alloc buffer related fields 1735 this->initialize_tlab(); 1736 1737 // used to test validity of stack trace backs 1738 this->record_base_of_stack_pointer(); 1739 1740 // Record real stack base and size. 1741 this->record_stack_base_and_size(); 1742 1743 this->create_stack_guard_pages(); 1744 1745 this->cache_global_variables(); 1746 1747 // Thread is now sufficient initialized to be handled by the safepoint code as being 1748 // in the VM. Change thread state from _thread_new to _thread_in_vm 1749 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1750 1751 assert(JavaThread::current() == this, "sanity check"); 1752 assert(!Thread::current()->owns_locks(), "sanity check"); 1753 1754 DTRACE_THREAD_PROBE(start, this); 1755 1756 // This operation might block. We call that after all safepoint checks for a new thread has 1757 // been completed. 1758 this->set_active_handles(JNIHandleBlock::allocate_block()); 1759 1760 if (JvmtiExport::should_post_thread_life()) { 1761 JvmtiExport::post_thread_start(this); 1762 } 1763 1764 EventThreadStart event; 1765 if (event.should_commit()) { 1766 event.set_thread(THREAD_TRACE_ID(this)); 1767 event.commit(); 1768 } 1769 1770 // We call another function to do the rest so we are sure that the stack addresses used 1771 // from there will be lower than the stack base just computed 1772 thread_main_inner(); 1773 1774 // Note, thread is no longer valid at this point! 1775 } 1776 1777 1778 void JavaThread::thread_main_inner() { 1779 assert(JavaThread::current() == this, "sanity check"); 1780 assert(this->threadObj() != NULL, "just checking"); 1781 1782 // Execute thread entry point unless this thread has a pending exception 1783 // or has been stopped before starting. 1784 // Note: Due to JVM_StopThread we can have pending exceptions already! 1785 if (!this->has_pending_exception() && 1786 !java_lang_Thread::is_stillborn(this->threadObj())) { 1787 { 1788 ResourceMark rm(this); 1789 this->set_native_thread_name(this->get_thread_name()); 1790 } 1791 HandleMark hm(this); 1792 this->entry_point()(this, this); 1793 } 1794 1795 DTRACE_THREAD_PROBE(stop, this); 1796 1797 this->exit(false); 1798 this->smr_delete(); 1799 } 1800 1801 1802 static void ensure_join(JavaThread* thread) { 1803 // We do not need to grab the Threads_lock, since we are operating on ourself. 1804 Handle threadObj(thread, thread->threadObj()); 1805 assert(threadObj.not_null(), "java thread object must exist"); 1806 ObjectLocker lock(threadObj, thread); 1807 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1808 thread->clear_pending_exception(); 1809 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1810 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1811 // Clear the native thread instance - this makes isAlive return false and allows the join() 1812 // to complete once we've done the notify_all below 1813 java_lang_Thread::set_thread(threadObj(), NULL); 1814 lock.notify_all(thread); 1815 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1816 thread->clear_pending_exception(); 1817 } 1818 1819 1820 // For any new cleanup additions, please check to see if they need to be applied to 1821 // cleanup_failed_attach_current_thread as well. 1822 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1823 assert(this == JavaThread::current(), "thread consistency check"); 1824 1825 elapsedTimer _timer_exit_phase1; 1826 elapsedTimer _timer_exit_phase2; 1827 elapsedTimer _timer_exit_phase3; 1828 elapsedTimer _timer_exit_phase4; 1829 1830 if (log_is_enabled(Debug, os, thread, timer)) { 1831 _timer_exit_phase1.start(); 1832 } 1833 1834 HandleMark hm(this); 1835 Handle uncaught_exception(this, this->pending_exception()); 1836 this->clear_pending_exception(); 1837 Handle threadObj(this, this->threadObj()); 1838 assert(threadObj.not_null(), "Java thread object should be created"); 1839 1840 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1841 { 1842 EXCEPTION_MARK; 1843 1844 CLEAR_PENDING_EXCEPTION; 1845 } 1846 if (!destroy_vm) { 1847 if (uncaught_exception.not_null()) { 1848 EXCEPTION_MARK; 1849 // Call method Thread.dispatchUncaughtException(). 1850 Klass* thread_klass = SystemDictionary::Thread_klass(); 1851 JavaValue result(T_VOID); 1852 JavaCalls::call_virtual(&result, 1853 threadObj, thread_klass, 1854 vmSymbols::dispatchUncaughtException_name(), 1855 vmSymbols::throwable_void_signature(), 1856 uncaught_exception, 1857 THREAD); 1858 if (HAS_PENDING_EXCEPTION) { 1859 ResourceMark rm(this); 1860 jio_fprintf(defaultStream::error_stream(), 1861 "\nException: %s thrown from the UncaughtExceptionHandler" 1862 " in thread \"%s\"\n", 1863 pending_exception()->klass()->external_name(), 1864 get_thread_name()); 1865 CLEAR_PENDING_EXCEPTION; 1866 } 1867 } 1868 1869 // Called before the java thread exit since we want to read info 1870 // from java_lang_Thread object 1871 EventThreadEnd event; 1872 if (event.should_commit()) { 1873 event.set_thread(THREAD_TRACE_ID(this)); 1874 event.commit(); 1875 } 1876 1877 // Call after last event on thread 1878 EVENT_THREAD_EXIT(this); 1879 1880 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1881 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1882 // is deprecated anyhow. 1883 if (!is_Compiler_thread()) { 1884 int count = 3; 1885 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1886 EXCEPTION_MARK; 1887 JavaValue result(T_VOID); 1888 Klass* thread_klass = SystemDictionary::Thread_klass(); 1889 JavaCalls::call_virtual(&result, 1890 threadObj, thread_klass, 1891 vmSymbols::exit_method_name(), 1892 vmSymbols::void_method_signature(), 1893 THREAD); 1894 CLEAR_PENDING_EXCEPTION; 1895 } 1896 } 1897 // notify JVMTI 1898 if (JvmtiExport::should_post_thread_life()) { 1899 JvmtiExport::post_thread_end(this); 1900 } 1901 1902 // We have notified the agents that we are exiting, before we go on, 1903 // we must check for a pending external suspend request and honor it 1904 // in order to not surprise the thread that made the suspend request. 1905 while (true) { 1906 { 1907 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1908 if (!is_external_suspend()) { 1909 set_terminated(_thread_exiting); 1910 ThreadService::current_thread_exiting(this); 1911 break; 1912 } 1913 // Implied else: 1914 // Things get a little tricky here. We have a pending external 1915 // suspend request, but we are holding the SR_lock so we 1916 // can't just self-suspend. So we temporarily drop the lock 1917 // and then self-suspend. 1918 } 1919 1920 ThreadBlockInVM tbivm(this); 1921 java_suspend_self(); 1922 1923 // We're done with this suspend request, but we have to loop around 1924 // and check again. Eventually we will get SR_lock without a pending 1925 // external suspend request and will be able to mark ourselves as 1926 // exiting. 1927 } 1928 // no more external suspends are allowed at this point 1929 } else { 1930 // before_exit() has already posted JVMTI THREAD_END events 1931 } 1932 1933 if (log_is_enabled(Debug, os, thread, timer)) { 1934 _timer_exit_phase1.stop(); 1935 _timer_exit_phase2.start(); 1936 } 1937 // Notify waiters on thread object. This has to be done after exit() is called 1938 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1939 // group should have the destroyed bit set before waiters are notified). 1940 ensure_join(this); 1941 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1942 1943 if (log_is_enabled(Debug, os, thread, timer)) { 1944 _timer_exit_phase2.stop(); 1945 _timer_exit_phase3.start(); 1946 } 1947 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1948 // held by this thread must be released. The spec does not distinguish 1949 // between JNI-acquired and regular Java monitors. We can only see 1950 // regular Java monitors here if monitor enter-exit matching is broken. 1951 // 1952 // Optionally release any monitors for regular JavaThread exits. This 1953 // is provided as a work around for any bugs in monitor enter-exit 1954 // matching. This can be expensive so it is not enabled by default. 1955 // 1956 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1957 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1958 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1959 // Sanity check even though JNI DetachCurrentThread() would have 1960 // returned JNI_ERR if there was a Java frame. JavaThread exit 1961 // should be done executing Java code by the time we get here. 1962 assert(!this->has_last_Java_frame(), 1963 "should not have a Java frame when detaching or exiting"); 1964 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1965 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1966 } 1967 1968 // These things needs to be done while we are still a Java Thread. Make sure that thread 1969 // is in a consistent state, in case GC happens 1970 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1971 1972 if (active_handles() != NULL) { 1973 JNIHandleBlock* block = active_handles(); 1974 set_active_handles(NULL); 1975 JNIHandleBlock::release_block(block); 1976 } 1977 1978 if (free_handle_block() != NULL) { 1979 JNIHandleBlock* block = free_handle_block(); 1980 set_free_handle_block(NULL); 1981 JNIHandleBlock::release_block(block); 1982 } 1983 1984 // These have to be removed while this is still a valid thread. 1985 remove_stack_guard_pages(); 1986 1987 if (UseTLAB) { 1988 tlab().make_parsable(true); // retire TLAB 1989 } 1990 1991 if (JvmtiEnv::environments_might_exist()) { 1992 JvmtiExport::cleanup_thread(this); 1993 } 1994 1995 // We must flush any deferred card marks before removing a thread from 1996 // the list of active threads. 1997 Universe::heap()->flush_deferred_store_barrier(this); 1998 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1999 2000 #if INCLUDE_ALL_GCS 2001 // We must flush the G1-related buffers before removing a thread 2002 // from the list of active threads. We must do this after any deferred 2003 // card marks have been flushed (above) so that any entries that are 2004 // added to the thread's dirty card queue as a result are not lost. 2005 if (UseG1GC) { 2006 flush_barrier_queues(); 2007 } 2008 #endif // INCLUDE_ALL_GCS 2009 2010 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2011 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2012 os::current_thread_id()); 2013 2014 if (log_is_enabled(Debug, os, thread, timer)) { 2015 _timer_exit_phase3.stop(); 2016 _timer_exit_phase4.start(); 2017 } 2018 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2019 Threads::remove(this); 2020 2021 if (log_is_enabled(Debug, os, thread, timer)) { 2022 _timer_exit_phase4.stop(); 2023 ResourceMark rm(this); 2024 log_debug(os, thread, timer)("name='%s'" 2025 ", exit-phase1=" JLONG_FORMAT 2026 ", exit-phase2=" JLONG_FORMAT 2027 ", exit-phase3=" JLONG_FORMAT 2028 ", exit-phase4=" JLONG_FORMAT, 2029 get_thread_name(), 2030 _timer_exit_phase1.milliseconds(), 2031 _timer_exit_phase2.milliseconds(), 2032 _timer_exit_phase3.milliseconds(), 2033 _timer_exit_phase4.milliseconds()); 2034 } 2035 } 2036 2037 #if INCLUDE_ALL_GCS 2038 // Flush G1-related queues. 2039 void JavaThread::flush_barrier_queues() { 2040 satb_mark_queue().flush(); 2041 dirty_card_queue().flush(); 2042 } 2043 2044 void JavaThread::initialize_queues() { 2045 assert(!SafepointSynchronize::is_at_safepoint(), 2046 "we should not be at a safepoint"); 2047 2048 SATBMarkQueue& satb_queue = satb_mark_queue(); 2049 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 2050 // The SATB queue should have been constructed with its active 2051 // field set to false. 2052 assert(!satb_queue.is_active(), "SATB queue should not be active"); 2053 assert(satb_queue.is_empty(), "SATB queue should be empty"); 2054 // If we are creating the thread during a marking cycle, we should 2055 // set the active field of the SATB queue to true. 2056 if (satb_queue_set.is_active()) { 2057 satb_queue.set_active(true); 2058 } 2059 2060 DirtyCardQueue& dirty_queue = dirty_card_queue(); 2061 // The dirty card queue should have been constructed with its 2062 // active field set to true. 2063 assert(dirty_queue.is_active(), "dirty card queue should be active"); 2064 } 2065 #endif // INCLUDE_ALL_GCS 2066 2067 void JavaThread::cleanup_failed_attach_current_thread() { 2068 if (active_handles() != NULL) { 2069 JNIHandleBlock* block = active_handles(); 2070 set_active_handles(NULL); 2071 JNIHandleBlock::release_block(block); 2072 } 2073 2074 if (free_handle_block() != NULL) { 2075 JNIHandleBlock* block = free_handle_block(); 2076 set_free_handle_block(NULL); 2077 JNIHandleBlock::release_block(block); 2078 } 2079 2080 // These have to be removed while this is still a valid thread. 2081 remove_stack_guard_pages(); 2082 2083 if (UseTLAB) { 2084 tlab().make_parsable(true); // retire TLAB, if any 2085 } 2086 2087 #if INCLUDE_ALL_GCS 2088 if (UseG1GC) { 2089 flush_barrier_queues(); 2090 } 2091 #endif // INCLUDE_ALL_GCS 2092 2093 Threads::remove(this); 2094 this->smr_delete(); 2095 } 2096 2097 2098 2099 2100 JavaThread* JavaThread::active() { 2101 Thread* thread = Thread::current(); 2102 if (thread->is_Java_thread()) { 2103 return (JavaThread*) thread; 2104 } else { 2105 assert(thread->is_VM_thread(), "this must be a vm thread"); 2106 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2107 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2108 assert(ret->is_Java_thread(), "must be a Java thread"); 2109 return ret; 2110 } 2111 } 2112 2113 bool JavaThread::is_lock_owned(address adr) const { 2114 if (Thread::is_lock_owned(adr)) return true; 2115 2116 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2117 if (chunk->contains(adr)) return true; 2118 } 2119 2120 return false; 2121 } 2122 2123 2124 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2125 chunk->set_next(monitor_chunks()); 2126 set_monitor_chunks(chunk); 2127 } 2128 2129 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2130 guarantee(monitor_chunks() != NULL, "must be non empty"); 2131 if (monitor_chunks() == chunk) { 2132 set_monitor_chunks(chunk->next()); 2133 } else { 2134 MonitorChunk* prev = monitor_chunks(); 2135 while (prev->next() != chunk) prev = prev->next(); 2136 prev->set_next(chunk->next()); 2137 } 2138 } 2139 2140 // JVM support. 2141 2142 // Note: this function shouldn't block if it's called in 2143 // _thread_in_native_trans state (such as from 2144 // check_special_condition_for_native_trans()). 2145 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2146 2147 if (has_last_Java_frame() && has_async_condition()) { 2148 // If we are at a polling page safepoint (not a poll return) 2149 // then we must defer async exception because live registers 2150 // will be clobbered by the exception path. Poll return is 2151 // ok because the call we a returning from already collides 2152 // with exception handling registers and so there is no issue. 2153 // (The exception handling path kills call result registers but 2154 // this is ok since the exception kills the result anyway). 2155 2156 if (is_at_poll_safepoint()) { 2157 // if the code we are returning to has deoptimized we must defer 2158 // the exception otherwise live registers get clobbered on the 2159 // exception path before deoptimization is able to retrieve them. 2160 // 2161 RegisterMap map(this, false); 2162 frame caller_fr = last_frame().sender(&map); 2163 assert(caller_fr.is_compiled_frame(), "what?"); 2164 if (caller_fr.is_deoptimized_frame()) { 2165 log_info(exceptions)("deferred async exception at compiled safepoint"); 2166 return; 2167 } 2168 } 2169 } 2170 2171 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2172 if (condition == _no_async_condition) { 2173 // Conditions have changed since has_special_runtime_exit_condition() 2174 // was called: 2175 // - if we were here only because of an external suspend request, 2176 // then that was taken care of above (or cancelled) so we are done 2177 // - if we were here because of another async request, then it has 2178 // been cleared between the has_special_runtime_exit_condition() 2179 // and now so again we are done 2180 return; 2181 } 2182 2183 // Check for pending async. exception 2184 if (_pending_async_exception != NULL) { 2185 // Only overwrite an already pending exception, if it is not a threadDeath. 2186 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2187 2188 // We cannot call Exceptions::_throw(...) here because we cannot block 2189 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2190 2191 LogTarget(Info, exceptions) lt; 2192 if (lt.is_enabled()) { 2193 ResourceMark rm; 2194 LogStream ls(lt); 2195 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2196 if (has_last_Java_frame()) { 2197 frame f = last_frame(); 2198 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2199 } 2200 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2201 } 2202 _pending_async_exception = NULL; 2203 clear_has_async_exception(); 2204 } 2205 } 2206 2207 if (check_unsafe_error && 2208 condition == _async_unsafe_access_error && !has_pending_exception()) { 2209 condition = _no_async_condition; // done 2210 switch (thread_state()) { 2211 case _thread_in_vm: { 2212 JavaThread* THREAD = this; 2213 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2214 } 2215 case _thread_in_native: { 2216 ThreadInVMfromNative tiv(this); 2217 JavaThread* THREAD = this; 2218 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2219 } 2220 case _thread_in_Java: { 2221 ThreadInVMfromJava tiv(this); 2222 JavaThread* THREAD = this; 2223 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2224 } 2225 default: 2226 ShouldNotReachHere(); 2227 } 2228 } 2229 2230 assert(condition == _no_async_condition || has_pending_exception() || 2231 (!check_unsafe_error && condition == _async_unsafe_access_error), 2232 "must have handled the async condition, if no exception"); 2233 } 2234 2235 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2236 // 2237 // Check for pending external suspend. Internal suspend requests do 2238 // not use handle_special_runtime_exit_condition(). 2239 // If JNIEnv proxies are allowed, don't self-suspend if the target 2240 // thread is not the current thread. In older versions of jdbx, jdbx 2241 // threads could call into the VM with another thread's JNIEnv so we 2242 // can be here operating on behalf of a suspended thread (4432884). 2243 bool do_self_suspend = is_external_suspend_with_lock(); 2244 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2245 // 2246 // Because thread is external suspended the safepoint code will count 2247 // thread as at a safepoint. This can be odd because we can be here 2248 // as _thread_in_Java which would normally transition to _thread_blocked 2249 // at a safepoint. We would like to mark the thread as _thread_blocked 2250 // before calling java_suspend_self like all other callers of it but 2251 // we must then observe proper safepoint protocol. (We can't leave 2252 // _thread_blocked with a safepoint in progress). However we can be 2253 // here as _thread_in_native_trans so we can't use a normal transition 2254 // constructor/destructor pair because they assert on that type of 2255 // transition. We could do something like: 2256 // 2257 // JavaThreadState state = thread_state(); 2258 // set_thread_state(_thread_in_vm); 2259 // { 2260 // ThreadBlockInVM tbivm(this); 2261 // java_suspend_self() 2262 // } 2263 // set_thread_state(_thread_in_vm_trans); 2264 // if (safepoint) block; 2265 // set_thread_state(state); 2266 // 2267 // but that is pretty messy. Instead we just go with the way the 2268 // code has worked before and note that this is the only path to 2269 // java_suspend_self that doesn't put the thread in _thread_blocked 2270 // mode. 2271 2272 frame_anchor()->make_walkable(this); 2273 java_suspend_self(); 2274 2275 // We might be here for reasons in addition to the self-suspend request 2276 // so check for other async requests. 2277 } 2278 2279 if (check_asyncs) { 2280 check_and_handle_async_exceptions(); 2281 } 2282 #if INCLUDE_TRACE 2283 if (is_trace_suspend()) { 2284 TRACE_SUSPEND_THREAD(this); 2285 } 2286 #endif 2287 } 2288 2289 void JavaThread::send_thread_stop(oop java_throwable) { 2290 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2291 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2292 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2293 2294 // Do not throw asynchronous exceptions against the compiler thread 2295 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2296 if (!can_call_java()) return; 2297 2298 { 2299 // Actually throw the Throwable against the target Thread - however 2300 // only if there is no thread death exception installed already. 2301 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2302 // If the topmost frame is a runtime stub, then we are calling into 2303 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2304 // must deoptimize the caller before continuing, as the compiled exception handler table 2305 // may not be valid 2306 if (has_last_Java_frame()) { 2307 frame f = last_frame(); 2308 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2309 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2310 RegisterMap reg_map(this, UseBiasedLocking); 2311 frame compiled_frame = f.sender(®_map); 2312 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2313 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2314 } 2315 } 2316 } 2317 2318 // Set async. pending exception in thread. 2319 set_pending_async_exception(java_throwable); 2320 2321 if (log_is_enabled(Info, exceptions)) { 2322 ResourceMark rm; 2323 log_info(exceptions)("Pending Async. exception installed of type: %s", 2324 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2325 } 2326 // for AbortVMOnException flag 2327 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2328 } 2329 } 2330 2331 2332 // Interrupt thread so it will wake up from a potential wait() 2333 Thread::interrupt(this); 2334 } 2335 2336 // External suspension mechanism. 2337 // 2338 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2339 // to any VM_locks and it is at a transition 2340 // Self-suspension will happen on the transition out of the vm. 2341 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2342 // 2343 // Guarantees on return: 2344 // + Target thread will not execute any new bytecode (that's why we need to 2345 // force a safepoint) 2346 // + Target thread will not enter any new monitors 2347 // 2348 void JavaThread::java_suspend() { 2349 ThreadsListHandle tlh; 2350 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2351 return; 2352 } 2353 2354 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2355 if (!is_external_suspend()) { 2356 // a racing resume has cancelled us; bail out now 2357 return; 2358 } 2359 2360 // suspend is done 2361 uint32_t debug_bits = 0; 2362 // Warning: is_ext_suspend_completed() may temporarily drop the 2363 // SR_lock to allow the thread to reach a stable thread state if 2364 // it is currently in a transient thread state. 2365 if (is_ext_suspend_completed(false /* !called_by_wait */, 2366 SuspendRetryDelay, &debug_bits)) { 2367 return; 2368 } 2369 } 2370 2371 VM_ThreadSuspend vm_suspend; 2372 VMThread::execute(&vm_suspend); 2373 } 2374 2375 // Part II of external suspension. 2376 // A JavaThread self suspends when it detects a pending external suspend 2377 // request. This is usually on transitions. It is also done in places 2378 // where continuing to the next transition would surprise the caller, 2379 // e.g., monitor entry. 2380 // 2381 // Returns the number of times that the thread self-suspended. 2382 // 2383 // Note: DO NOT call java_suspend_self() when you just want to block current 2384 // thread. java_suspend_self() is the second stage of cooperative 2385 // suspension for external suspend requests and should only be used 2386 // to complete an external suspend request. 2387 // 2388 int JavaThread::java_suspend_self() { 2389 int ret = 0; 2390 2391 // we are in the process of exiting so don't suspend 2392 if (is_exiting()) { 2393 clear_external_suspend(); 2394 return ret; 2395 } 2396 2397 assert(_anchor.walkable() || 2398 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2399 "must have walkable stack"); 2400 2401 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2402 2403 assert(!this->is_ext_suspended(), 2404 "a thread trying to self-suspend should not already be suspended"); 2405 2406 if (this->is_suspend_equivalent()) { 2407 // If we are self-suspending as a result of the lifting of a 2408 // suspend equivalent condition, then the suspend_equivalent 2409 // flag is not cleared until we set the ext_suspended flag so 2410 // that wait_for_ext_suspend_completion() returns consistent 2411 // results. 2412 this->clear_suspend_equivalent(); 2413 } 2414 2415 // A racing resume may have cancelled us before we grabbed SR_lock 2416 // above. Or another external suspend request could be waiting for us 2417 // by the time we return from SR_lock()->wait(). The thread 2418 // that requested the suspension may already be trying to walk our 2419 // stack and if we return now, we can change the stack out from under 2420 // it. This would be a "bad thing (TM)" and cause the stack walker 2421 // to crash. We stay self-suspended until there are no more pending 2422 // external suspend requests. 2423 while (is_external_suspend()) { 2424 ret++; 2425 this->set_ext_suspended(); 2426 2427 // _ext_suspended flag is cleared by java_resume() 2428 while (is_ext_suspended()) { 2429 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2430 } 2431 } 2432 2433 return ret; 2434 } 2435 2436 #ifdef ASSERT 2437 // verify the JavaThread has not yet been published in the Threads::list, and 2438 // hence doesn't need protection from concurrent access at this stage 2439 void JavaThread::verify_not_published() { 2440 ThreadsListHandle tlh; 2441 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!"); 2442 } 2443 #endif 2444 2445 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2446 // progress or when _suspend_flags is non-zero. 2447 // Current thread needs to self-suspend if there is a suspend request and/or 2448 // block if a safepoint is in progress. 2449 // Async exception ISN'T checked. 2450 // Note only the ThreadInVMfromNative transition can call this function 2451 // directly and when thread state is _thread_in_native_trans 2452 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2453 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2454 2455 JavaThread *curJT = JavaThread::current(); 2456 bool do_self_suspend = thread->is_external_suspend(); 2457 2458 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2459 2460 // If JNIEnv proxies are allowed, don't self-suspend if the target 2461 // thread is not the current thread. In older versions of jdbx, jdbx 2462 // threads could call into the VM with another thread's JNIEnv so we 2463 // can be here operating on behalf of a suspended thread (4432884). 2464 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2465 JavaThreadState state = thread->thread_state(); 2466 2467 // We mark this thread_blocked state as a suspend-equivalent so 2468 // that a caller to is_ext_suspend_completed() won't be confused. 2469 // The suspend-equivalent state is cleared by java_suspend_self(). 2470 thread->set_suspend_equivalent(); 2471 2472 // If the safepoint code sees the _thread_in_native_trans state, it will 2473 // wait until the thread changes to other thread state. There is no 2474 // guarantee on how soon we can obtain the SR_lock and complete the 2475 // self-suspend request. It would be a bad idea to let safepoint wait for 2476 // too long. Temporarily change the state to _thread_blocked to 2477 // let the VM thread know that this thread is ready for GC. The problem 2478 // of changing thread state is that safepoint could happen just after 2479 // java_suspend_self() returns after being resumed, and VM thread will 2480 // see the _thread_blocked state. We must check for safepoint 2481 // after restoring the state and make sure we won't leave while a safepoint 2482 // is in progress. 2483 thread->set_thread_state(_thread_blocked); 2484 thread->java_suspend_self(); 2485 thread->set_thread_state(state); 2486 2487 InterfaceSupport::serialize_thread_state_with_handler(thread); 2488 } 2489 2490 if (SafepointSynchronize::do_call_back()) { 2491 // If we are safepointing, then block the caller which may not be 2492 // the same as the target thread (see above). 2493 SafepointSynchronize::block(curJT); 2494 } 2495 2496 if (thread->is_deopt_suspend()) { 2497 thread->clear_deopt_suspend(); 2498 RegisterMap map(thread, false); 2499 frame f = thread->last_frame(); 2500 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2501 f = f.sender(&map); 2502 } 2503 if (f.id() == thread->must_deopt_id()) { 2504 thread->clear_must_deopt_id(); 2505 f.deoptimize(thread); 2506 } else { 2507 fatal("missed deoptimization!"); 2508 } 2509 } 2510 #if INCLUDE_TRACE 2511 if (thread->is_trace_suspend()) { 2512 TRACE_SUSPEND_THREAD(thread); 2513 } 2514 #endif 2515 } 2516 2517 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2518 // progress or when _suspend_flags is non-zero. 2519 // Current thread needs to self-suspend if there is a suspend request and/or 2520 // block if a safepoint is in progress. 2521 // Also check for pending async exception (not including unsafe access error). 2522 // Note only the native==>VM/Java barriers can call this function and when 2523 // thread state is _thread_in_native_trans. 2524 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2525 check_safepoint_and_suspend_for_native_trans(thread); 2526 2527 if (thread->has_async_exception()) { 2528 // We are in _thread_in_native_trans state, don't handle unsafe 2529 // access error since that may block. 2530 thread->check_and_handle_async_exceptions(false); 2531 } 2532 } 2533 2534 // This is a variant of the normal 2535 // check_special_condition_for_native_trans with slightly different 2536 // semantics for use by critical native wrappers. It does all the 2537 // normal checks but also performs the transition back into 2538 // thread_in_Java state. This is required so that critical natives 2539 // can potentially block and perform a GC if they are the last thread 2540 // exiting the GCLocker. 2541 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2542 check_special_condition_for_native_trans(thread); 2543 2544 // Finish the transition 2545 thread->set_thread_state(_thread_in_Java); 2546 2547 if (thread->do_critical_native_unlock()) { 2548 ThreadInVMfromJavaNoAsyncException tiv(thread); 2549 GCLocker::unlock_critical(thread); 2550 thread->clear_critical_native_unlock(); 2551 } 2552 } 2553 2554 // We need to guarantee the Threads_lock here, since resumes are not 2555 // allowed during safepoint synchronization 2556 // Can only resume from an external suspension 2557 void JavaThread::java_resume() { 2558 assert_locked_or_safepoint(Threads_lock); 2559 2560 // Sanity check: thread is gone, has started exiting or the thread 2561 // was not externally suspended. 2562 ThreadsListHandle tlh; 2563 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2564 return; 2565 } 2566 2567 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2568 2569 clear_external_suspend(); 2570 2571 if (is_ext_suspended()) { 2572 clear_ext_suspended(); 2573 SR_lock()->notify_all(); 2574 } 2575 } 2576 2577 size_t JavaThread::_stack_red_zone_size = 0; 2578 size_t JavaThread::_stack_yellow_zone_size = 0; 2579 size_t JavaThread::_stack_reserved_zone_size = 0; 2580 size_t JavaThread::_stack_shadow_zone_size = 0; 2581 2582 void JavaThread::create_stack_guard_pages() { 2583 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2584 address low_addr = stack_end(); 2585 size_t len = stack_guard_zone_size(); 2586 2587 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2588 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2589 2590 int must_commit = os::must_commit_stack_guard_pages(); 2591 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2592 2593 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2594 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2595 return; 2596 } 2597 2598 if (os::guard_memory((char *) low_addr, len)) { 2599 _stack_guard_state = stack_guard_enabled; 2600 } else { 2601 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2602 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2603 if (os::uncommit_memory((char *) low_addr, len)) { 2604 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2605 } 2606 return; 2607 } 2608 2609 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2610 PTR_FORMAT "-" PTR_FORMAT ".", 2611 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2612 } 2613 2614 void JavaThread::remove_stack_guard_pages() { 2615 assert(Thread::current() == this, "from different thread"); 2616 if (_stack_guard_state == stack_guard_unused) return; 2617 address low_addr = stack_end(); 2618 size_t len = stack_guard_zone_size(); 2619 2620 if (os::must_commit_stack_guard_pages()) { 2621 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2622 _stack_guard_state = stack_guard_unused; 2623 } else { 2624 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2625 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2626 return; 2627 } 2628 } else { 2629 if (_stack_guard_state == stack_guard_unused) return; 2630 if (os::unguard_memory((char *) low_addr, len)) { 2631 _stack_guard_state = stack_guard_unused; 2632 } else { 2633 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2634 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2635 return; 2636 } 2637 } 2638 2639 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2640 PTR_FORMAT "-" PTR_FORMAT ".", 2641 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2642 } 2643 2644 void JavaThread::enable_stack_reserved_zone() { 2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2646 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2647 2648 // The base notation is from the stack's point of view, growing downward. 2649 // We need to adjust it to work correctly with guard_memory() 2650 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2651 2652 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2653 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2654 2655 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2656 _stack_guard_state = stack_guard_enabled; 2657 } else { 2658 warning("Attempt to guard stack reserved zone failed."); 2659 } 2660 enable_register_stack_guard(); 2661 } 2662 2663 void JavaThread::disable_stack_reserved_zone() { 2664 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2665 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2666 2667 // Simply return if called for a thread that does not use guard pages. 2668 if (_stack_guard_state == stack_guard_unused) return; 2669 2670 // The base notation is from the stack's point of view, growing downward. 2671 // We need to adjust it to work correctly with guard_memory() 2672 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2673 2674 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2675 _stack_guard_state = stack_guard_reserved_disabled; 2676 } else { 2677 warning("Attempt to unguard stack reserved zone failed."); 2678 } 2679 disable_register_stack_guard(); 2680 } 2681 2682 void JavaThread::enable_stack_yellow_reserved_zone() { 2683 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2684 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2685 2686 // The base notation is from the stacks point of view, growing downward. 2687 // We need to adjust it to work correctly with guard_memory() 2688 address base = stack_red_zone_base(); 2689 2690 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2691 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2692 2693 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2694 _stack_guard_state = stack_guard_enabled; 2695 } else { 2696 warning("Attempt to guard stack yellow zone failed."); 2697 } 2698 enable_register_stack_guard(); 2699 } 2700 2701 void JavaThread::disable_stack_yellow_reserved_zone() { 2702 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2703 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2704 2705 // Simply return if called for a thread that does not use guard pages. 2706 if (_stack_guard_state == stack_guard_unused) return; 2707 2708 // The base notation is from the stacks point of view, growing downward. 2709 // We need to adjust it to work correctly with guard_memory() 2710 address base = stack_red_zone_base(); 2711 2712 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2713 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2714 } else { 2715 warning("Attempt to unguard stack yellow zone failed."); 2716 } 2717 disable_register_stack_guard(); 2718 } 2719 2720 void JavaThread::enable_stack_red_zone() { 2721 // The base notation is from the stacks point of view, growing downward. 2722 // We need to adjust it to work correctly with guard_memory() 2723 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2724 address base = stack_red_zone_base() - stack_red_zone_size(); 2725 2726 guarantee(base < stack_base(), "Error calculating stack red zone"); 2727 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2728 2729 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2730 warning("Attempt to guard stack red zone failed."); 2731 } 2732 } 2733 2734 void JavaThread::disable_stack_red_zone() { 2735 // The base notation is from the stacks point of view, growing downward. 2736 // We need to adjust it to work correctly with guard_memory() 2737 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2738 address base = stack_red_zone_base() - stack_red_zone_size(); 2739 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2740 warning("Attempt to unguard stack red zone failed."); 2741 } 2742 } 2743 2744 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2745 // ignore is there is no stack 2746 if (!has_last_Java_frame()) return; 2747 // traverse the stack frames. Starts from top frame. 2748 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2749 frame* fr = fst.current(); 2750 f(fr, fst.register_map()); 2751 } 2752 } 2753 2754 2755 #ifndef PRODUCT 2756 // Deoptimization 2757 // Function for testing deoptimization 2758 void JavaThread::deoptimize() { 2759 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2760 StackFrameStream fst(this, UseBiasedLocking); 2761 bool deopt = false; // Dump stack only if a deopt actually happens. 2762 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2763 // Iterate over all frames in the thread and deoptimize 2764 for (; !fst.is_done(); fst.next()) { 2765 if (fst.current()->can_be_deoptimized()) { 2766 2767 if (only_at) { 2768 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2769 // consists of comma or carriage return separated numbers so 2770 // search for the current bci in that string. 2771 address pc = fst.current()->pc(); 2772 nmethod* nm = (nmethod*) fst.current()->cb(); 2773 ScopeDesc* sd = nm->scope_desc_at(pc); 2774 char buffer[8]; 2775 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2776 size_t len = strlen(buffer); 2777 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2778 while (found != NULL) { 2779 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2780 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2781 // Check that the bci found is bracketed by terminators. 2782 break; 2783 } 2784 found = strstr(found + 1, buffer); 2785 } 2786 if (!found) { 2787 continue; 2788 } 2789 } 2790 2791 if (DebugDeoptimization && !deopt) { 2792 deopt = true; // One-time only print before deopt 2793 tty->print_cr("[BEFORE Deoptimization]"); 2794 trace_frames(); 2795 trace_stack(); 2796 } 2797 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2798 } 2799 } 2800 2801 if (DebugDeoptimization && deopt) { 2802 tty->print_cr("[AFTER Deoptimization]"); 2803 trace_frames(); 2804 } 2805 } 2806 2807 2808 // Make zombies 2809 void JavaThread::make_zombies() { 2810 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2811 if (fst.current()->can_be_deoptimized()) { 2812 // it is a Java nmethod 2813 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2814 nm->make_not_entrant(); 2815 } 2816 } 2817 } 2818 #endif // PRODUCT 2819 2820 2821 void JavaThread::deoptimized_wrt_marked_nmethods() { 2822 if (!has_last_Java_frame()) return; 2823 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2824 StackFrameStream fst(this, UseBiasedLocking); 2825 for (; !fst.is_done(); fst.next()) { 2826 if (fst.current()->should_be_deoptimized()) { 2827 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2828 } 2829 } 2830 } 2831 2832 2833 // If the caller is a NamedThread, then remember, in the current scope, 2834 // the given JavaThread in its _processed_thread field. 2835 class RememberProcessedThread: public StackObj { 2836 NamedThread* _cur_thr; 2837 public: 2838 RememberProcessedThread(JavaThread* jthr) { 2839 Thread* thread = Thread::current(); 2840 if (thread->is_Named_thread()) { 2841 _cur_thr = (NamedThread *)thread; 2842 _cur_thr->set_processed_thread(jthr); 2843 } else { 2844 _cur_thr = NULL; 2845 } 2846 } 2847 2848 ~RememberProcessedThread() { 2849 if (_cur_thr) { 2850 _cur_thr->set_processed_thread(NULL); 2851 } 2852 } 2853 }; 2854 2855 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2856 // Verify that the deferred card marks have been flushed. 2857 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2858 2859 // Traverse the GCHandles 2860 Thread::oops_do(f, cf); 2861 2862 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2863 2864 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2865 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2866 2867 if (has_last_Java_frame()) { 2868 // Record JavaThread to GC thread 2869 RememberProcessedThread rpt(this); 2870 2871 // Traverse the privileged stack 2872 if (_privileged_stack_top != NULL) { 2873 _privileged_stack_top->oops_do(f); 2874 } 2875 2876 // traverse the registered growable array 2877 if (_array_for_gc != NULL) { 2878 for (int index = 0; index < _array_for_gc->length(); index++) { 2879 f->do_oop(_array_for_gc->adr_at(index)); 2880 } 2881 } 2882 2883 // Traverse the monitor chunks 2884 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2885 chunk->oops_do(f); 2886 } 2887 2888 // Traverse the execution stack 2889 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2890 fst.current()->oops_do(f, cf, fst.register_map()); 2891 } 2892 } 2893 2894 // callee_target is never live across a gc point so NULL it here should 2895 // it still contain a methdOop. 2896 2897 set_callee_target(NULL); 2898 2899 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2900 // If we have deferred set_locals there might be oops waiting to be 2901 // written 2902 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2903 if (list != NULL) { 2904 for (int i = 0; i < list->length(); i++) { 2905 list->at(i)->oops_do(f); 2906 } 2907 } 2908 2909 // Traverse instance variables at the end since the GC may be moving things 2910 // around using this function 2911 f->do_oop((oop*) &_threadObj); 2912 f->do_oop((oop*) &_vm_result); 2913 f->do_oop((oop*) &_exception_oop); 2914 f->do_oop((oop*) &_pending_async_exception); 2915 2916 if (jvmti_thread_state() != NULL) { 2917 jvmti_thread_state()->oops_do(f); 2918 } 2919 } 2920 2921 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2922 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2923 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2924 2925 if (has_last_Java_frame()) { 2926 // Traverse the execution stack 2927 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2928 fst.current()->nmethods_do(cf); 2929 } 2930 } 2931 } 2932 2933 void JavaThread::metadata_do(void f(Metadata*)) { 2934 if (has_last_Java_frame()) { 2935 // Traverse the execution stack to call f() on the methods in the stack 2936 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2937 fst.current()->metadata_do(f); 2938 } 2939 } else if (is_Compiler_thread()) { 2940 // need to walk ciMetadata in current compile tasks to keep alive. 2941 CompilerThread* ct = (CompilerThread*)this; 2942 if (ct->env() != NULL) { 2943 ct->env()->metadata_do(f); 2944 } 2945 if (ct->task() != NULL) { 2946 ct->task()->metadata_do(f); 2947 } 2948 } 2949 } 2950 2951 // Printing 2952 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2953 switch (_thread_state) { 2954 case _thread_uninitialized: return "_thread_uninitialized"; 2955 case _thread_new: return "_thread_new"; 2956 case _thread_new_trans: return "_thread_new_trans"; 2957 case _thread_in_native: return "_thread_in_native"; 2958 case _thread_in_native_trans: return "_thread_in_native_trans"; 2959 case _thread_in_vm: return "_thread_in_vm"; 2960 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2961 case _thread_in_Java: return "_thread_in_Java"; 2962 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2963 case _thread_blocked: return "_thread_blocked"; 2964 case _thread_blocked_trans: return "_thread_blocked_trans"; 2965 default: return "unknown thread state"; 2966 } 2967 } 2968 2969 #ifndef PRODUCT 2970 void JavaThread::print_thread_state_on(outputStream *st) const { 2971 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2972 }; 2973 void JavaThread::print_thread_state() const { 2974 print_thread_state_on(tty); 2975 } 2976 #endif // PRODUCT 2977 2978 // Called by Threads::print() for VM_PrintThreads operation 2979 void JavaThread::print_on(outputStream *st) const { 2980 st->print_raw("\""); 2981 st->print_raw(get_thread_name()); 2982 st->print_raw("\" "); 2983 oop thread_oop = threadObj(); 2984 if (thread_oop != NULL) { 2985 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2986 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2987 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2988 } 2989 Thread::print_on(st); 2990 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2991 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2992 if (thread_oop != NULL) { 2993 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2994 } 2995 #ifndef PRODUCT 2996 print_thread_state_on(st); 2997 _safepoint_state->print_on(st); 2998 #endif // PRODUCT 2999 if (is_Compiler_thread()) { 3000 CompilerThread* ct = (CompilerThread*)this; 3001 if (ct->task() != NULL) { 3002 st->print(" Compiling: "); 3003 ct->task()->print(st, NULL, true, false); 3004 } else { 3005 st->print(" No compile task"); 3006 } 3007 st->cr(); 3008 } 3009 } 3010 3011 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3012 st->print("%s", get_thread_name_string(buf, buflen)); 3013 } 3014 3015 // Called by fatal error handler. The difference between this and 3016 // JavaThread::print() is that we can't grab lock or allocate memory. 3017 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3018 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3019 oop thread_obj = threadObj(); 3020 if (thread_obj != NULL) { 3021 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3022 } 3023 st->print(" ["); 3024 st->print("%s", _get_thread_state_name(_thread_state)); 3025 if (osthread()) { 3026 st->print(", id=%d", osthread()->thread_id()); 3027 } 3028 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3029 p2i(stack_end()), p2i(stack_base())); 3030 st->print("]"); 3031 3032 if (_threads_hazard_ptr != NULL) { 3033 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 3034 } 3035 if (_nested_threads_hazard_ptr != NULL) { 3036 print_nested_threads_hazard_ptrs_on(st); 3037 } 3038 return; 3039 } 3040 3041 // Verification 3042 3043 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3044 3045 void JavaThread::verify() { 3046 // Verify oops in the thread. 3047 oops_do(&VerifyOopClosure::verify_oop, NULL); 3048 3049 // Verify the stack frames. 3050 frames_do(frame_verify); 3051 } 3052 3053 // CR 6300358 (sub-CR 2137150) 3054 // Most callers of this method assume that it can't return NULL but a 3055 // thread may not have a name whilst it is in the process of attaching to 3056 // the VM - see CR 6412693, and there are places where a JavaThread can be 3057 // seen prior to having it's threadObj set (eg JNI attaching threads and 3058 // if vm exit occurs during initialization). These cases can all be accounted 3059 // for such that this method never returns NULL. 3060 const char* JavaThread::get_thread_name() const { 3061 #ifdef ASSERT 3062 // early safepoints can hit while current thread does not yet have TLS 3063 if (!SafepointSynchronize::is_at_safepoint()) { 3064 Thread *cur = Thread::current(); 3065 if (!(cur->is_Java_thread() && cur == this)) { 3066 // Current JavaThreads are allowed to get their own name without 3067 // the Threads_lock. 3068 assert_locked_or_safepoint(Threads_lock); 3069 } 3070 } 3071 #endif // ASSERT 3072 return get_thread_name_string(); 3073 } 3074 3075 // Returns a non-NULL representation of this thread's name, or a suitable 3076 // descriptive string if there is no set name 3077 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3078 const char* name_str; 3079 oop thread_obj = threadObj(); 3080 if (thread_obj != NULL) { 3081 oop name = java_lang_Thread::name(thread_obj); 3082 if (name != NULL) { 3083 if (buf == NULL) { 3084 name_str = java_lang_String::as_utf8_string(name); 3085 } else { 3086 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3087 } 3088 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3089 name_str = "<no-name - thread is attaching>"; 3090 } else { 3091 name_str = Thread::name(); 3092 } 3093 } else { 3094 name_str = Thread::name(); 3095 } 3096 assert(name_str != NULL, "unexpected NULL thread name"); 3097 return name_str; 3098 } 3099 3100 3101 const char* JavaThread::get_threadgroup_name() const { 3102 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3103 oop thread_obj = threadObj(); 3104 if (thread_obj != NULL) { 3105 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3106 if (thread_group != NULL) { 3107 // ThreadGroup.name can be null 3108 return java_lang_ThreadGroup::name(thread_group); 3109 } 3110 } 3111 return NULL; 3112 } 3113 3114 const char* JavaThread::get_parent_name() const { 3115 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3116 oop thread_obj = threadObj(); 3117 if (thread_obj != NULL) { 3118 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3119 if (thread_group != NULL) { 3120 oop parent = java_lang_ThreadGroup::parent(thread_group); 3121 if (parent != NULL) { 3122 // ThreadGroup.name can be null 3123 return java_lang_ThreadGroup::name(parent); 3124 } 3125 } 3126 } 3127 return NULL; 3128 } 3129 3130 ThreadPriority JavaThread::java_priority() const { 3131 oop thr_oop = threadObj(); 3132 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3133 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3134 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3135 return priority; 3136 } 3137 3138 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3139 3140 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3141 // Link Java Thread object <-> C++ Thread 3142 3143 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3144 // and put it into a new Handle. The Handle "thread_oop" can then 3145 // be used to pass the C++ thread object to other methods. 3146 3147 // Set the Java level thread object (jthread) field of the 3148 // new thread (a JavaThread *) to C++ thread object using the 3149 // "thread_oop" handle. 3150 3151 // Set the thread field (a JavaThread *) of the 3152 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3153 3154 Handle thread_oop(Thread::current(), 3155 JNIHandles::resolve_non_null(jni_thread)); 3156 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3157 "must be initialized"); 3158 set_threadObj(thread_oop()); 3159 java_lang_Thread::set_thread(thread_oop(), this); 3160 3161 if (prio == NoPriority) { 3162 prio = java_lang_Thread::priority(thread_oop()); 3163 assert(prio != NoPriority, "A valid priority should be present"); 3164 } 3165 3166 // Push the Java priority down to the native thread; needs Threads_lock 3167 Thread::set_priority(this, prio); 3168 3169 prepare_ext(); 3170 3171 // Add the new thread to the Threads list and set it in motion. 3172 // We must have threads lock in order to call Threads::add. 3173 // It is crucial that we do not block before the thread is 3174 // added to the Threads list for if a GC happens, then the java_thread oop 3175 // will not be visited by GC. 3176 Threads::add(this); 3177 } 3178 3179 oop JavaThread::current_park_blocker() { 3180 // Support for JSR-166 locks 3181 oop thread_oop = threadObj(); 3182 if (thread_oop != NULL && 3183 JDK_Version::current().supports_thread_park_blocker()) { 3184 return java_lang_Thread::park_blocker(thread_oop); 3185 } 3186 return NULL; 3187 } 3188 3189 3190 void JavaThread::print_stack_on(outputStream* st) { 3191 if (!has_last_Java_frame()) return; 3192 ResourceMark rm; 3193 HandleMark hm; 3194 3195 RegisterMap reg_map(this); 3196 vframe* start_vf = last_java_vframe(®_map); 3197 int count = 0; 3198 for (vframe* f = start_vf; f; f = f->sender()) { 3199 if (f->is_java_frame()) { 3200 javaVFrame* jvf = javaVFrame::cast(f); 3201 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3202 3203 // Print out lock information 3204 if (JavaMonitorsInStackTrace) { 3205 jvf->print_lock_info_on(st, count); 3206 } 3207 } else { 3208 // Ignore non-Java frames 3209 } 3210 3211 // Bail-out case for too deep stacks 3212 count++; 3213 if (MaxJavaStackTraceDepth == count) return; 3214 } 3215 } 3216 3217 3218 // JVMTI PopFrame support 3219 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3220 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3221 if (in_bytes(size_in_bytes) != 0) { 3222 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3223 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3224 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3225 } 3226 } 3227 3228 void* JavaThread::popframe_preserved_args() { 3229 return _popframe_preserved_args; 3230 } 3231 3232 ByteSize JavaThread::popframe_preserved_args_size() { 3233 return in_ByteSize(_popframe_preserved_args_size); 3234 } 3235 3236 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3237 int sz = in_bytes(popframe_preserved_args_size()); 3238 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3239 return in_WordSize(sz / wordSize); 3240 } 3241 3242 void JavaThread::popframe_free_preserved_args() { 3243 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3244 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3245 _popframe_preserved_args = NULL; 3246 _popframe_preserved_args_size = 0; 3247 } 3248 3249 #ifndef PRODUCT 3250 3251 void JavaThread::trace_frames() { 3252 tty->print_cr("[Describe stack]"); 3253 int frame_no = 1; 3254 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3255 tty->print(" %d. ", frame_no++); 3256 fst.current()->print_value_on(tty, this); 3257 tty->cr(); 3258 } 3259 } 3260 3261 class PrintAndVerifyOopClosure: public OopClosure { 3262 protected: 3263 template <class T> inline void do_oop_work(T* p) { 3264 oop obj = oopDesc::load_decode_heap_oop(p); 3265 if (obj == NULL) return; 3266 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3267 if (oopDesc::is_oop_or_null(obj)) { 3268 if (obj->is_objArray()) { 3269 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3270 } else { 3271 obj->print(); 3272 } 3273 } else { 3274 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3275 } 3276 tty->cr(); 3277 } 3278 public: 3279 virtual void do_oop(oop* p) { do_oop_work(p); } 3280 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3281 }; 3282 3283 3284 static void oops_print(frame* f, const RegisterMap *map) { 3285 PrintAndVerifyOopClosure print; 3286 f->print_value(); 3287 f->oops_do(&print, NULL, (RegisterMap*)map); 3288 } 3289 3290 // Print our all the locations that contain oops and whether they are 3291 // valid or not. This useful when trying to find the oldest frame 3292 // where an oop has gone bad since the frame walk is from youngest to 3293 // oldest. 3294 void JavaThread::trace_oops() { 3295 tty->print_cr("[Trace oops]"); 3296 frames_do(oops_print); 3297 } 3298 3299 3300 #ifdef ASSERT 3301 // Print or validate the layout of stack frames 3302 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3303 ResourceMark rm; 3304 PRESERVE_EXCEPTION_MARK; 3305 FrameValues values; 3306 int frame_no = 0; 3307 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3308 fst.current()->describe(values, ++frame_no); 3309 if (depth == frame_no) break; 3310 } 3311 if (validate_only) { 3312 values.validate(); 3313 } else { 3314 tty->print_cr("[Describe stack layout]"); 3315 values.print(this); 3316 } 3317 } 3318 #endif 3319 3320 void JavaThread::trace_stack_from(vframe* start_vf) { 3321 ResourceMark rm; 3322 int vframe_no = 1; 3323 for (vframe* f = start_vf; f; f = f->sender()) { 3324 if (f->is_java_frame()) { 3325 javaVFrame::cast(f)->print_activation(vframe_no++); 3326 } else { 3327 f->print(); 3328 } 3329 if (vframe_no > StackPrintLimit) { 3330 tty->print_cr("...<more frames>..."); 3331 return; 3332 } 3333 } 3334 } 3335 3336 3337 void JavaThread::trace_stack() { 3338 if (!has_last_Java_frame()) return; 3339 ResourceMark rm; 3340 HandleMark hm; 3341 RegisterMap reg_map(this); 3342 trace_stack_from(last_java_vframe(®_map)); 3343 } 3344 3345 3346 #endif // PRODUCT 3347 3348 3349 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3350 assert(reg_map != NULL, "a map must be given"); 3351 frame f = last_frame(); 3352 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3353 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3354 } 3355 return NULL; 3356 } 3357 3358 3359 Klass* JavaThread::security_get_caller_class(int depth) { 3360 vframeStream vfst(this); 3361 vfst.security_get_caller_frame(depth); 3362 if (!vfst.at_end()) { 3363 return vfst.method()->method_holder(); 3364 } 3365 return NULL; 3366 } 3367 3368 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3369 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3370 CompileBroker::compiler_thread_loop(); 3371 } 3372 3373 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3374 NMethodSweeper::sweeper_loop(); 3375 } 3376 3377 // Create a CompilerThread 3378 CompilerThread::CompilerThread(CompileQueue* queue, 3379 CompilerCounters* counters) 3380 : JavaThread(&compiler_thread_entry) { 3381 _env = NULL; 3382 _log = NULL; 3383 _task = NULL; 3384 _queue = queue; 3385 _counters = counters; 3386 _buffer_blob = NULL; 3387 _compiler = NULL; 3388 3389 #ifndef PRODUCT 3390 _ideal_graph_printer = NULL; 3391 #endif 3392 } 3393 3394 bool CompilerThread::can_call_java() const { 3395 return _compiler != NULL && _compiler->is_jvmci(); 3396 } 3397 3398 // Create sweeper thread 3399 CodeCacheSweeperThread::CodeCacheSweeperThread() 3400 : JavaThread(&sweeper_thread_entry) { 3401 _scanned_compiled_method = NULL; 3402 } 3403 3404 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3405 JavaThread::oops_do(f, cf); 3406 if (_scanned_compiled_method != NULL && cf != NULL) { 3407 // Safepoints can occur when the sweeper is scanning an nmethod so 3408 // process it here to make sure it isn't unloaded in the middle of 3409 // a scan. 3410 cf->do_code_blob(_scanned_compiled_method); 3411 } 3412 } 3413 3414 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3415 JavaThread::nmethods_do(cf); 3416 if (_scanned_compiled_method != NULL && cf != NULL) { 3417 // Safepoints can occur when the sweeper is scanning an nmethod so 3418 // process it here to make sure it isn't unloaded in the middle of 3419 // a scan. 3420 cf->do_code_blob(_scanned_compiled_method); 3421 } 3422 } 3423 3424 3425 // ======= Threads ======== 3426 3427 // The Threads class links together all active threads, and provides 3428 // operations over all threads. It is protected by its own Mutex 3429 // lock, which is also used in other contexts to protect thread 3430 // operations from having the thread being operated on from exiting 3431 // and going away unexpectedly (e.g., safepoint synchronization) 3432 3433 JavaThread* Threads::_thread_list = NULL; 3434 int Threads::_number_of_threads = 0; 3435 int Threads::_number_of_non_daemon_threads = 0; 3436 int Threads::_return_code = 0; 3437 int Threads::_thread_claim_parity = 0; 3438 size_t JavaThread::_stack_size_at_create = 0; 3439 Monitor* Threads::_smr_delete_lock = 3440 new Monitor(Monitor::special, "smr_delete_lock", 3441 false /* allow_vm_block */, 3442 Monitor::_safepoint_check_never); 3443 // The '_cnt', '_max' and '_times" fields are enabled via 3444 // -XX:+EnableThreadSMRStatistics: 3445 uint Threads::_smr_delete_lock_wait_cnt = 0; 3446 uint Threads::_smr_delete_lock_wait_max = 0; 3447 volatile jint Threads::_smr_delete_notify = 0; 3448 volatile jint Threads::_smr_deleted_thread_cnt = 0; 3449 volatile jint Threads::_smr_deleted_thread_time_max = 0; 3450 volatile jint Threads::_smr_deleted_thread_times = 0; 3451 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0); 3452 long Threads::_smr_java_thread_list_alloc_cnt = 1; 3453 long Threads::_smr_java_thread_list_free_cnt = 0; 3454 uint Threads::_smr_java_thread_list_max = 0; 3455 uint Threads::_smr_nested_thread_list_max = 0; 3456 volatile jint Threads::_smr_tlh_cnt = 0; 3457 volatile jint Threads::_smr_tlh_time_max = 0; 3458 volatile jint Threads::_smr_tlh_times = 0; 3459 ThreadsList* Threads::_smr_to_delete_list = NULL; 3460 uint Threads::_smr_to_delete_list_cnt = 0; 3461 uint Threads::_smr_to_delete_list_max = 0; 3462 3463 #ifdef ASSERT 3464 bool Threads::_vm_complete = false; 3465 #endif 3466 3467 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3468 Prefetch::read((void*)addr, prefetch_interval); 3469 return *addr; 3470 } 3471 3472 // Possibly the ugliest for loop the world has seen. C++ does not allow 3473 // multiple types in the declaration section of the for loop. In this case 3474 // we are only dealing with pointers and hence can cast them. It looks ugly 3475 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3476 #define DO_JAVA_THREADS(LIST, X) \ 3477 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3478 *MACRO_list = (JavaThread*)(LIST), \ 3479 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3480 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3481 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3482 MACRO_current_p != MACRO_end; \ 3483 MACRO_current_p++, \ 3484 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3485 3486 // All JavaThreads 3487 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X) 3488 3489 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3490 void Threads::threads_do(ThreadClosure* tc) { 3491 assert_locked_or_safepoint(Threads_lock); 3492 // ALL_JAVA_THREADS iterates through all JavaThreads 3493 ALL_JAVA_THREADS(p) { 3494 tc->do_thread(p); 3495 } 3496 // Someday we could have a table or list of all non-JavaThreads. 3497 // For now, just manually iterate through them. 3498 tc->do_thread(VMThread::vm_thread()); 3499 Universe::heap()->gc_threads_do(tc); 3500 WatcherThread *wt = WatcherThread::watcher_thread(); 3501 // Strictly speaking, the following NULL check isn't sufficient to make sure 3502 // the data for WatcherThread is still valid upon being examined. However, 3503 // considering that WatchThread terminates when the VM is on the way to 3504 // exit at safepoint, the chance of the above is extremely small. The right 3505 // way to prevent termination of WatcherThread would be to acquire 3506 // Terminator_lock, but we can't do that without violating the lock rank 3507 // checking in some cases. 3508 if (wt != NULL) { 3509 tc->do_thread(wt); 3510 } 3511 3512 // If CompilerThreads ever become non-JavaThreads, add them here 3513 } 3514 3515 void Threads::parallel_java_threads_do(ThreadClosure* tc) { 3516 int cp = Threads::thread_claim_parity(); 3517 ALL_JAVA_THREADS(p) { 3518 if (p->claim_oops_do(true, cp)) { 3519 tc->do_thread(p); 3520 } 3521 } 3522 // Thread claiming protocol requires us to claim the same interesting 3523 // threads on all paths. Notably, Threads::possibly_parallel_threads_do 3524 // claims all Java threads *and* the VMThread. To avoid breaking the 3525 // claiming protocol, we have to claim VMThread on this path too, even 3526 // if we do not apply the closure to the VMThread. 3527 VMThread* vmt = VMThread::vm_thread(); 3528 (void)vmt->claim_oops_do(true, cp); 3529 } 3530 3531 // The system initialization in the library has three phases. 3532 // 3533 // Phase 1: java.lang.System class initialization 3534 // java.lang.System is a primordial class loaded and initialized 3535 // by the VM early during startup. java.lang.System.<clinit> 3536 // only does registerNatives and keeps the rest of the class 3537 // initialization work later until thread initialization completes. 3538 // 3539 // System.initPhase1 initializes the system properties, the static 3540 // fields in, out, and err. Set up java signal handlers, OS-specific 3541 // system settings, and thread group of the main thread. 3542 static void call_initPhase1(TRAPS) { 3543 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3544 JavaValue result(T_VOID); 3545 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3546 vmSymbols::void_method_signature(), CHECK); 3547 } 3548 3549 // Phase 2. Module system initialization 3550 // This will initialize the module system. Only java.base classes 3551 // can be loaded until phase 2 completes. 3552 // 3553 // Call System.initPhase2 after the compiler initialization and jsr292 3554 // classes get initialized because module initialization runs a lot of java 3555 // code, that for performance reasons, should be compiled. Also, this will 3556 // enable the startup code to use lambda and other language features in this 3557 // phase and onward. 3558 // 3559 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3560 static void call_initPhase2(TRAPS) { 3561 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3562 3563 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3564 3565 JavaValue result(T_INT); 3566 JavaCallArguments args; 3567 args.push_int(DisplayVMOutputToStderr); 3568 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3569 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3570 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3571 if (result.get_jint() != JNI_OK) { 3572 vm_exit_during_initialization(); // no message or exception 3573 } 3574 3575 universe_post_module_init(); 3576 } 3577 3578 // Phase 3. final setup - set security manager, system class loader and TCCL 3579 // 3580 // This will instantiate and set the security manager, set the system class 3581 // loader as well as the thread context class loader. The security manager 3582 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3583 // other modules or the application's classpath. 3584 static void call_initPhase3(TRAPS) { 3585 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3586 JavaValue result(T_VOID); 3587 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3588 vmSymbols::void_method_signature(), CHECK); 3589 } 3590 3591 // Safe Memory Reclamation (SMR) support: 3592 // 3593 3594 // Acquire a stable ThreadsList. 3595 // 3596 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) { 3597 assert(self != NULL, "sanity check"); 3598 // acquire_stable_list_nested_path() will grab the Threads_lock 3599 // so let's make sure the ThreadsListHandle is in a safe place. 3600 // ThreadsListSetter cannot make this check on this code path. 3601 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) 3602 3603 if (self->get_threads_hazard_ptr() == NULL) { 3604 // The typical case is first. 3605 return acquire_stable_list_fast_path(self); 3606 } 3607 3608 // The nested case is rare. 3609 return acquire_stable_list_nested_path(self); 3610 } 3611 3612 // Fast path (and lock free) way to acquire a stable ThreadsList. 3613 // 3614 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) { 3615 assert(self != NULL, "sanity check"); 3616 assert(self->get_threads_hazard_ptr() == NULL, "sanity check"); 3617 assert(self->get_nested_threads_hazard_ptr() == NULL, 3618 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 3619 3620 ThreadsList* threads; 3621 3622 // Stable recording of a hazard ptr for SMR. This code does not use 3623 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr 3624 // fields is racy relative to code that uses those fields with locks. 3625 // OrderAccess and Atomic functions are used to deal with those races. 3626 // 3627 while (true) { 3628 threads = get_smr_java_thread_list(); 3629 3630 // Publish a tagged hazard ptr to denote that the hazard ptr is not 3631 // yet verified as being stable. Due to the fence after the hazard 3632 // ptr write, it will be sequentially consistent w.r.t. the 3633 // sequentially consistent writes of the ThreadsList, even on 3634 // non-multiple copy atomic machines where stores can be observed 3635 // in different order from different observer threads. 3636 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads); 3637 self->set_threads_hazard_ptr(unverified_threads); 3638 3639 // If _smr_java_thread_list has changed, we have lost a race with 3640 // Threads::add() or Threads::remove() and have to try again. 3641 if (get_smr_java_thread_list() != threads) { 3642 continue; 3643 } 3644 3645 // We try to remove the tag which will verify the hazard ptr as 3646 // being stable. This exchange can race with a scanning thread 3647 // which might invalidate the tagged hazard ptr to keep it from 3648 // being followed to access JavaThread ptrs. If we lose the race, 3649 // we simply retry. If we win the race, then the stable hazard 3650 // ptr is officially published. 3651 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) { 3652 break; 3653 } 3654 } 3655 3656 // A stable hazard ptr has been published letting other threads know 3657 // that the ThreadsList and the JavaThreads reachable from this list 3658 // are protected and hence they should not be deleted until everyone 3659 // agrees it is safe to do so. 3660 3661 return threads; 3662 } 3663 3664 // Acquire a nested stable ThreadsList; this is rare so it uses 3665 // Threads_lock. 3666 // 3667 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) { 3668 assert(self != NULL, "sanity check"); 3669 assert(self->get_threads_hazard_ptr() != NULL, 3670 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr"); 3671 3672 // The thread already has a hazard ptr (ThreadsList ref) so we need 3673 // to create a nested ThreadsListHandle with the current ThreadsList 3674 // since it might be different than our current hazard ptr. The need 3675 // for a nested ThreadsListHandle is rare so we do this while holding 3676 // the Threads_lock so we don't race with the scanning code; the code 3677 // is so much simpler this way. 3678 3679 NestedThreadsList* node; 3680 { 3681 // Only grab the Threads_lock if we don't already own it. 3682 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); 3683 node = new NestedThreadsList(get_smr_java_thread_list()); 3684 // We insert at the front of the list to match up with the delete 3685 // in release_stable_list(). 3686 node->set_next(self->get_nested_threads_hazard_ptr()); 3687 self->set_nested_threads_hazard_ptr(node); 3688 if (EnableThreadSMRStatistics) { 3689 self->inc_nested_threads_hazard_ptr_cnt(); 3690 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) { 3691 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt(); 3692 } 3693 } 3694 } 3695 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); 3696 3697 return node->t_list(); 3698 } 3699 3700 // Release a stable ThreadsList. 3701 // 3702 void Threads::release_stable_list(Thread *self) { 3703 assert(self != NULL, "sanity check"); 3704 // release_stable_list_nested_path() will grab the Threads_lock 3705 // so let's make sure the ThreadsListHandle is in a safe place. 3706 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) 3707 3708 if (self->get_nested_threads_hazard_ptr() == NULL) { 3709 // The typical case is first. 3710 release_stable_list_fast_path(self); 3711 return; 3712 } 3713 3714 // The nested case is rare. 3715 release_stable_list_nested_path(self); 3716 } 3717 3718 // Fast path way to release a stable ThreadsList. The release portion 3719 // is lock-free, but the wake up portion is not. 3720 // 3721 void Threads::release_stable_list_fast_path(Thread *self) { 3722 assert(self != NULL, "sanity check"); 3723 assert(self->get_threads_hazard_ptr() != NULL, "sanity check"); 3724 assert(self->get_nested_threads_hazard_ptr() == NULL, 3725 "cannot have a nested hazard ptr when releasing a regular hazard ptr"); 3726 3727 // After releasing the hazard ptr, other threads may go ahead and 3728 // free up some memory temporarily used by a ThreadsList snapshot. 3729 self->set_threads_hazard_ptr(NULL); 3730 3731 // We use double-check locking to reduce traffic on the system 3732 // wide smr_delete_lock. 3733 if (Threads::smr_delete_notify()) { 3734 // An exiting thread might be waiting in smr_delete(); we need to 3735 // check with smr_delete_lock to be sure. 3736 release_stable_list_wake_up((char *) "regular hazard ptr"); 3737 } 3738 } 3739 3740 // Release a nested stable ThreadsList; this is rare so it uses 3741 // Threads_lock. 3742 // 3743 void Threads::release_stable_list_nested_path(Thread *self) { 3744 assert(self != NULL, "sanity check"); 3745 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check"); 3746 assert(self->get_threads_hazard_ptr() != NULL, 3747 "must have a regular hazard ptr to have nested hazard ptrs"); 3748 3749 // We have a nested ThreadsListHandle so we have to release it first. 3750 // The need for a nested ThreadsListHandle is rare so we do this while 3751 // holding the Threads_lock so we don't race with the scanning code; 3752 // the code is so much simpler this way. 3753 3754 NestedThreadsList *node; 3755 { 3756 // Only grab the Threads_lock if we don't already own it. 3757 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); 3758 // We remove from the front of the list to match up with the insert 3759 // in acquire_stable_list(). 3760 node = self->get_nested_threads_hazard_ptr(); 3761 self->set_nested_threads_hazard_ptr(node->next()); 3762 if (EnableThreadSMRStatistics) { 3763 self->dec_nested_threads_hazard_ptr_cnt(); 3764 } 3765 } 3766 3767 // An exiting thread might be waiting in smr_delete(); we need to 3768 // check with smr_delete_lock to be sure. 3769 release_stable_list_wake_up((char *) "nested hazard ptr"); 3770 3771 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); 3772 3773 delete node; 3774 } 3775 3776 // Wake up portion of the release stable ThreadsList protocol; 3777 // uses the smr_delete_lock(). 3778 // 3779 void Threads::release_stable_list_wake_up(char *log_str) { 3780 assert(log_str != NULL, "sanity check"); 3781 3782 // Note: smr_delete_lock is held in smr_delete() for the entire 3783 // hazard ptr search so that we do not lose this notify() if 3784 // the exiting thread has to wait. That code path also holds 3785 // Threads_lock (which was grabbed before smr_delete_lock) so that 3786 // threads_do() can be called. This means the system can't start a 3787 // safepoint which means this thread can't take too long to get to 3788 // a safepoint because of being blocked on smr_delete_lock. 3789 // 3790 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag); 3791 if (Threads::smr_delete_notify()) { 3792 // Notify any exiting JavaThreads that are waiting in smr_delete() 3793 // that we've released a ThreadsList. 3794 ml.notify_all(); 3795 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str); 3796 } 3797 } 3798 3799 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3800 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3801 3802 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3803 create_vm_init_libraries(); 3804 } 3805 3806 initialize_class(vmSymbols::java_lang_String(), CHECK); 3807 3808 // Inject CompactStrings value after the static initializers for String ran. 3809 java_lang_String::set_compact_strings(CompactStrings); 3810 3811 // Initialize java_lang.System (needed before creating the thread) 3812 initialize_class(vmSymbols::java_lang_System(), CHECK); 3813 // The VM creates & returns objects of this class. Make sure it's initialized. 3814 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3815 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3816 Handle thread_group = create_initial_thread_group(CHECK); 3817 Universe::set_main_thread_group(thread_group()); 3818 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3819 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3820 main_thread->set_threadObj(thread_object); 3821 // Set thread status to running since main thread has 3822 // been started and running. 3823 java_lang_Thread::set_thread_status(thread_object, 3824 java_lang_Thread::RUNNABLE); 3825 3826 // The VM creates objects of this class. 3827 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3828 3829 // The VM preresolves methods to these classes. Make sure that they get initialized 3830 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3831 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3832 3833 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3834 call_initPhase1(CHECK); 3835 3836 // get the Java runtime name after java.lang.System is initialized 3837 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3838 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3839 3840 // an instance of OutOfMemory exception has been allocated earlier 3841 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3842 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3843 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3844 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3845 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3846 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3847 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3848 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3849 } 3850 3851 void Threads::initialize_jsr292_core_classes(TRAPS) { 3852 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3853 3854 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3855 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3856 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3857 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3858 } 3859 3860 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3861 extern void JDK_Version_init(); 3862 3863 // Preinitialize version info. 3864 VM_Version::early_initialize(); 3865 3866 // Check version 3867 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3868 3869 // Initialize library-based TLS 3870 ThreadLocalStorage::init(); 3871 3872 // Initialize the output stream module 3873 ostream_init(); 3874 3875 // Process java launcher properties. 3876 Arguments::process_sun_java_launcher_properties(args); 3877 3878 // Initialize the os module 3879 os::init(); 3880 3881 // Record VM creation timing statistics 3882 TraceVmCreationTime create_vm_timer; 3883 create_vm_timer.start(); 3884 3885 // Initialize system properties. 3886 Arguments::init_system_properties(); 3887 3888 // So that JDK version can be used as a discriminator when parsing arguments 3889 JDK_Version_init(); 3890 3891 // Update/Initialize System properties after JDK version number is known 3892 Arguments::init_version_specific_system_properties(); 3893 3894 // Make sure to initialize log configuration *before* parsing arguments 3895 LogConfiguration::initialize(create_vm_timer.begin_time()); 3896 3897 // Parse arguments 3898 jint parse_result = Arguments::parse(args); 3899 if (parse_result != JNI_OK) return parse_result; 3900 3901 os::init_before_ergo(); 3902 3903 jint ergo_result = Arguments::apply_ergo(); 3904 if (ergo_result != JNI_OK) return ergo_result; 3905 3906 // Final check of all ranges after ergonomics which may change values. 3907 if (!CommandLineFlagRangeList::check_ranges()) { 3908 return JNI_EINVAL; 3909 } 3910 3911 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3912 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3913 if (!constraint_result) { 3914 return JNI_EINVAL; 3915 } 3916 3917 CommandLineFlagWriteableList::mark_startup(); 3918 3919 if (PauseAtStartup) { 3920 os::pause(); 3921 } 3922 3923 HOTSPOT_VM_INIT_BEGIN(); 3924 3925 // Timing (must come after argument parsing) 3926 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3927 3928 // Initialize the os module after parsing the args 3929 jint os_init_2_result = os::init_2(); 3930 if (os_init_2_result != JNI_OK) return os_init_2_result; 3931 3932 jint adjust_after_os_result = Arguments::adjust_after_os(); 3933 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3934 3935 // Initialize output stream logging 3936 ostream_init_log(); 3937 3938 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3939 // Must be before create_vm_init_agents() 3940 if (Arguments::init_libraries_at_startup()) { 3941 convert_vm_init_libraries_to_agents(); 3942 } 3943 3944 // Launch -agentlib/-agentpath and converted -Xrun agents 3945 if (Arguments::init_agents_at_startup()) { 3946 create_vm_init_agents(); 3947 } 3948 3949 // Initialize Threads state 3950 _thread_list = NULL; 3951 _number_of_threads = 0; 3952 _number_of_non_daemon_threads = 0; 3953 3954 // Initialize global data structures and create system classes in heap 3955 vm_init_globals(); 3956 3957 #if INCLUDE_JVMCI 3958 if (JVMCICounterSize > 0) { 3959 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3960 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3961 } else { 3962 JavaThread::_jvmci_old_thread_counters = NULL; 3963 } 3964 #endif // INCLUDE_JVMCI 3965 3966 // Attach the main thread to this os thread 3967 JavaThread* main_thread = new JavaThread(); 3968 main_thread->set_thread_state(_thread_in_vm); 3969 main_thread->initialize_thread_current(); 3970 // must do this before set_active_handles 3971 main_thread->record_stack_base_and_size(); 3972 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3973 3974 if (!main_thread->set_as_starting_thread()) { 3975 vm_shutdown_during_initialization( 3976 "Failed necessary internal allocation. Out of swap space"); 3977 main_thread->smr_delete(); 3978 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3979 return JNI_ENOMEM; 3980 } 3981 3982 // Enable guard page *after* os::create_main_thread(), otherwise it would 3983 // crash Linux VM, see notes in os_linux.cpp. 3984 main_thread->create_stack_guard_pages(); 3985 3986 // Initialize Java-Level synchronization subsystem 3987 ObjectMonitor::Initialize(); 3988 3989 // Initialize global modules 3990 jint status = init_globals(); 3991 if (status != JNI_OK) { 3992 main_thread->smr_delete(); 3993 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3994 return status; 3995 } 3996 3997 if (TRACE_INITIALIZE() != JNI_OK) { 3998 vm_exit_during_initialization("Failed to initialize tracing backend"); 3999 } 4000 4001 // Should be done after the heap is fully created 4002 main_thread->cache_global_variables(); 4003 4004 HandleMark hm; 4005 4006 { MutexLocker mu(Threads_lock); 4007 Threads::add(main_thread); 4008 } 4009 4010 // Any JVMTI raw monitors entered in onload will transition into 4011 // real raw monitor. VM is setup enough here for raw monitor enter. 4012 JvmtiExport::transition_pending_onload_raw_monitors(); 4013 4014 // Create the VMThread 4015 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 4016 4017 VMThread::create(); 4018 Thread* vmthread = VMThread::vm_thread(); 4019 4020 if (!os::create_thread(vmthread, os::vm_thread)) { 4021 vm_exit_during_initialization("Cannot create VM thread. " 4022 "Out of system resources."); 4023 } 4024 4025 // Wait for the VM thread to become ready, and VMThread::run to initialize 4026 // Monitors can have spurious returns, must always check another state flag 4027 { 4028 MutexLocker ml(Notify_lock); 4029 os::start_thread(vmthread); 4030 while (vmthread->active_handles() == NULL) { 4031 Notify_lock->wait(); 4032 } 4033 } 4034 } 4035 4036 assert(Universe::is_fully_initialized(), "not initialized"); 4037 if (VerifyDuringStartup) { 4038 // Make sure we're starting with a clean slate. 4039 VM_Verify verify_op; 4040 VMThread::execute(&verify_op); 4041 } 4042 4043 Thread* THREAD = Thread::current(); 4044 4045 // Always call even when there are not JVMTI environments yet, since environments 4046 // may be attached late and JVMTI must track phases of VM execution 4047 JvmtiExport::enter_early_start_phase(); 4048 4049 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4050 JvmtiExport::post_early_vm_start(); 4051 4052 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 4053 4054 // We need this for ClassDataSharing - the initial vm.info property is set 4055 // with the default value of CDS "sharing" which may be reset through 4056 // command line options. 4057 reset_vm_info_property(CHECK_JNI_ERR); 4058 4059 quicken_jni_functions(); 4060 4061 // No more stub generation allowed after that point. 4062 StubCodeDesc::freeze(); 4063 4064 // Set flag that basic initialization has completed. Used by exceptions and various 4065 // debug stuff, that does not work until all basic classes have been initialized. 4066 set_init_completed(); 4067 4068 LogConfiguration::post_initialize(); 4069 Metaspace::post_initialize(); 4070 4071 HOTSPOT_VM_INIT_END(); 4072 4073 // record VM initialization completion time 4074 #if INCLUDE_MANAGEMENT 4075 Management::record_vm_init_completed(); 4076 #endif // INCLUDE_MANAGEMENT 4077 4078 // Signal Dispatcher needs to be started before VMInit event is posted 4079 os::signal_init(CHECK_JNI_ERR); 4080 4081 // Start Attach Listener if +StartAttachListener or it can't be started lazily 4082 if (!DisableAttachMechanism) { 4083 AttachListener::vm_start(); 4084 if (StartAttachListener || AttachListener::init_at_startup()) { 4085 AttachListener::init(); 4086 } 4087 } 4088 4089 // Launch -Xrun agents 4090 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 4091 // back-end can launch with -Xdebug -Xrunjdwp. 4092 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 4093 create_vm_init_libraries(); 4094 } 4095 4096 if (CleanChunkPoolAsync) { 4097 Chunk::start_chunk_pool_cleaner_task(); 4098 } 4099 4100 // initialize compiler(s) 4101 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 4102 CompileBroker::compilation_init(CHECK_JNI_ERR); 4103 #endif 4104 4105 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4106 // It is done after compilers are initialized, because otherwise compilations of 4107 // signature polymorphic MH intrinsics can be missed 4108 // (see SystemDictionary::find_method_handle_intrinsic). 4109 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4110 4111 // This will initialize the module system. Only java.base classes can be 4112 // loaded until phase 2 completes 4113 call_initPhase2(CHECK_JNI_ERR); 4114 4115 // Always call even when there are not JVMTI environments yet, since environments 4116 // may be attached late and JVMTI must track phases of VM execution 4117 JvmtiExport::enter_start_phase(); 4118 4119 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4120 JvmtiExport::post_vm_start(); 4121 4122 // Final system initialization including security manager and system class loader 4123 call_initPhase3(CHECK_JNI_ERR); 4124 4125 // cache the system class loader 4126 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 4127 4128 #if INCLUDE_JVMCI 4129 if (EnableJVMCI) { 4130 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 4131 // The JVMCI Java initialization code will read this flag and 4132 // do the printing if it's set. 4133 bool init = JVMCIPrintProperties; 4134 4135 if (!init) { 4136 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4137 // compilations via JVMCI will not actually block until JVMCI is initialized. 4138 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4139 } 4140 4141 if (init) { 4142 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 4143 } 4144 } 4145 #endif 4146 4147 // Always call even when there are not JVMTI environments yet, since environments 4148 // may be attached late and JVMTI must track phases of VM execution 4149 JvmtiExport::enter_live_phase(); 4150 4151 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4152 JvmtiExport::post_vm_initialized(); 4153 4154 if (TRACE_START() != JNI_OK) { 4155 vm_exit_during_initialization("Failed to start tracing backend."); 4156 } 4157 4158 #if INCLUDE_MANAGEMENT 4159 Management::initialize(THREAD); 4160 4161 if (HAS_PENDING_EXCEPTION) { 4162 // management agent fails to start possibly due to 4163 // configuration problem and is responsible for printing 4164 // stack trace if appropriate. Simply exit VM. 4165 vm_exit(1); 4166 } 4167 #endif // INCLUDE_MANAGEMENT 4168 4169 if (MemProfiling) MemProfiler::engage(); 4170 StatSampler::engage(); 4171 if (CheckJNICalls) JniPeriodicChecker::engage(); 4172 4173 BiasedLocking::init(); 4174 4175 #if INCLUDE_RTM_OPT 4176 RTMLockingCounters::init(); 4177 #endif 4178 4179 if (JDK_Version::current().post_vm_init_hook_enabled()) { 4180 call_postVMInitHook(THREAD); 4181 // The Java side of PostVMInitHook.run must deal with all 4182 // exceptions and provide means of diagnosis. 4183 if (HAS_PENDING_EXCEPTION) { 4184 CLEAR_PENDING_EXCEPTION; 4185 } 4186 } 4187 4188 { 4189 MutexLocker ml(PeriodicTask_lock); 4190 // Make sure the WatcherThread can be started by WatcherThread::start() 4191 // or by dynamic enrollment. 4192 WatcherThread::make_startable(); 4193 // Start up the WatcherThread if there are any periodic tasks 4194 // NOTE: All PeriodicTasks should be registered by now. If they 4195 // aren't, late joiners might appear to start slowly (we might 4196 // take a while to process their first tick). 4197 if (PeriodicTask::num_tasks() > 0) { 4198 WatcherThread::start(); 4199 } 4200 } 4201 4202 create_vm_timer.end(); 4203 #ifdef ASSERT 4204 _vm_complete = true; 4205 #endif 4206 4207 if (DumpSharedSpaces) { 4208 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4209 ShouldNotReachHere(); 4210 } 4211 4212 return JNI_OK; 4213 } 4214 4215 // type for the Agent_OnLoad and JVM_OnLoad entry points 4216 extern "C" { 4217 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4218 } 4219 // Find a command line agent library and return its entry point for 4220 // -agentlib: -agentpath: -Xrun 4221 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4222 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4223 const char *on_load_symbols[], 4224 size_t num_symbol_entries) { 4225 OnLoadEntry_t on_load_entry = NULL; 4226 void *library = NULL; 4227 4228 if (!agent->valid()) { 4229 char buffer[JVM_MAXPATHLEN]; 4230 char ebuf[1024] = ""; 4231 const char *name = agent->name(); 4232 const char *msg = "Could not find agent library "; 4233 4234 // First check to see if agent is statically linked into executable 4235 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4236 library = agent->os_lib(); 4237 } else if (agent->is_absolute_path()) { 4238 library = os::dll_load(name, ebuf, sizeof ebuf); 4239 if (library == NULL) { 4240 const char *sub_msg = " in absolute path, with error: "; 4241 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4242 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4243 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4244 // If we can't find the agent, exit. 4245 vm_exit_during_initialization(buf, NULL); 4246 FREE_C_HEAP_ARRAY(char, buf); 4247 } 4248 } else { 4249 // Try to load the agent from the standard dll directory 4250 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4251 name)) { 4252 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4253 } 4254 if (library == NULL) { // Try the library path directory. 4255 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4256 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4257 } 4258 if (library == NULL) { 4259 const char *sub_msg = " on the library path, with error: "; 4260 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4261 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4262 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4263 // If we can't find the agent, exit. 4264 vm_exit_during_initialization(buf, NULL); 4265 FREE_C_HEAP_ARRAY(char, buf); 4266 } 4267 } 4268 } 4269 agent->set_os_lib(library); 4270 agent->set_valid(); 4271 } 4272 4273 // Find the OnLoad function. 4274 on_load_entry = 4275 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4276 false, 4277 on_load_symbols, 4278 num_symbol_entries)); 4279 return on_load_entry; 4280 } 4281 4282 // Find the JVM_OnLoad entry point 4283 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4284 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4285 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4286 } 4287 4288 // Find the Agent_OnLoad entry point 4289 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4290 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4291 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4292 } 4293 4294 // For backwards compatibility with -Xrun 4295 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4296 // treated like -agentpath: 4297 // Must be called before agent libraries are created 4298 void Threads::convert_vm_init_libraries_to_agents() { 4299 AgentLibrary* agent; 4300 AgentLibrary* next; 4301 4302 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4303 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4304 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4305 4306 // If there is an JVM_OnLoad function it will get called later, 4307 // otherwise see if there is an Agent_OnLoad 4308 if (on_load_entry == NULL) { 4309 on_load_entry = lookup_agent_on_load(agent); 4310 if (on_load_entry != NULL) { 4311 // switch it to the agent list -- so that Agent_OnLoad will be called, 4312 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4313 Arguments::convert_library_to_agent(agent); 4314 } else { 4315 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4316 } 4317 } 4318 } 4319 } 4320 4321 // Create agents for -agentlib: -agentpath: and converted -Xrun 4322 // Invokes Agent_OnLoad 4323 // Called very early -- before JavaThreads exist 4324 void Threads::create_vm_init_agents() { 4325 extern struct JavaVM_ main_vm; 4326 AgentLibrary* agent; 4327 4328 JvmtiExport::enter_onload_phase(); 4329 4330 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4331 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4332 4333 if (on_load_entry != NULL) { 4334 // Invoke the Agent_OnLoad function 4335 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4336 if (err != JNI_OK) { 4337 vm_exit_during_initialization("agent library failed to init", agent->name()); 4338 } 4339 } else { 4340 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4341 } 4342 } 4343 JvmtiExport::enter_primordial_phase(); 4344 } 4345 4346 extern "C" { 4347 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4348 } 4349 4350 void Threads::shutdown_vm_agents() { 4351 // Send any Agent_OnUnload notifications 4352 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4353 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4354 extern struct JavaVM_ main_vm; 4355 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4356 4357 // Find the Agent_OnUnload function. 4358 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4359 os::find_agent_function(agent, 4360 false, 4361 on_unload_symbols, 4362 num_symbol_entries)); 4363 4364 // Invoke the Agent_OnUnload function 4365 if (unload_entry != NULL) { 4366 JavaThread* thread = JavaThread::current(); 4367 ThreadToNativeFromVM ttn(thread); 4368 HandleMark hm(thread); 4369 (*unload_entry)(&main_vm); 4370 } 4371 } 4372 } 4373 4374 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4375 // Invokes JVM_OnLoad 4376 void Threads::create_vm_init_libraries() { 4377 extern struct JavaVM_ main_vm; 4378 AgentLibrary* agent; 4379 4380 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4381 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4382 4383 if (on_load_entry != NULL) { 4384 // Invoke the JVM_OnLoad function 4385 JavaThread* thread = JavaThread::current(); 4386 ThreadToNativeFromVM ttn(thread); 4387 HandleMark hm(thread); 4388 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4389 if (err != JNI_OK) { 4390 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4391 } 4392 } else { 4393 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4394 } 4395 } 4396 } 4397 4398 4399 // Last thread running calls java.lang.Shutdown.shutdown() 4400 void JavaThread::invoke_shutdown_hooks() { 4401 HandleMark hm(this); 4402 4403 // We could get here with a pending exception, if so clear it now. 4404 if (this->has_pending_exception()) { 4405 this->clear_pending_exception(); 4406 } 4407 4408 EXCEPTION_MARK; 4409 Klass* shutdown_klass = 4410 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4411 THREAD); 4412 if (shutdown_klass != NULL) { 4413 // SystemDictionary::resolve_or_null will return null if there was 4414 // an exception. If we cannot load the Shutdown class, just don't 4415 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4416 // and finalizers (if runFinalizersOnExit is set) won't be run. 4417 // Note that if a shutdown hook was registered or runFinalizersOnExit 4418 // was called, the Shutdown class would have already been loaded 4419 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4420 JavaValue result(T_VOID); 4421 JavaCalls::call_static(&result, 4422 shutdown_klass, 4423 vmSymbols::shutdown_method_name(), 4424 vmSymbols::void_method_signature(), 4425 THREAD); 4426 } 4427 CLEAR_PENDING_EXCEPTION; 4428 } 4429 4430 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4431 // the program falls off the end of main(). Another VM exit path is through 4432 // vm_exit() when the program calls System.exit() to return a value or when 4433 // there is a serious error in VM. The two shutdown paths are not exactly 4434 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4435 // and VM_Exit op at VM level. 4436 // 4437 // Shutdown sequence: 4438 // + Shutdown native memory tracking if it is on 4439 // + Wait until we are the last non-daemon thread to execute 4440 // <-- every thing is still working at this moment --> 4441 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4442 // shutdown hooks, run finalizers if finalization-on-exit 4443 // + Call before_exit(), prepare for VM exit 4444 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4445 // currently the only user of this mechanism is File.deleteOnExit()) 4446 // > stop StatSampler, watcher thread, CMS threads, 4447 // post thread end and vm death events to JVMTI, 4448 // stop signal thread 4449 // + Call JavaThread::exit(), it will: 4450 // > release JNI handle blocks, remove stack guard pages 4451 // > remove this thread from Threads list 4452 // <-- no more Java code from this thread after this point --> 4453 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4454 // the compiler threads at safepoint 4455 // <-- do not use anything that could get blocked by Safepoint --> 4456 // + Disable tracing at JNI/JVM barriers 4457 // + Set _vm_exited flag for threads that are still running native code 4458 // + Delete this thread 4459 // + Call exit_globals() 4460 // > deletes tty 4461 // > deletes PerfMemory resources 4462 // + Return to caller 4463 4464 bool Threads::destroy_vm() { 4465 JavaThread* thread = JavaThread::current(); 4466 4467 #ifdef ASSERT 4468 _vm_complete = false; 4469 #endif 4470 // Wait until we are the last non-daemon thread to execute 4471 { MutexLocker nu(Threads_lock); 4472 while (Threads::number_of_non_daemon_threads() > 1) 4473 // This wait should make safepoint checks, wait without a timeout, 4474 // and wait as a suspend-equivalent condition. 4475 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4476 Mutex::_as_suspend_equivalent_flag); 4477 } 4478 4479 // Hang forever on exit if we are reporting an error. 4480 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4481 os::infinite_sleep(); 4482 } 4483 os::wait_for_keypress_at_exit(); 4484 4485 // run Java level shutdown hooks 4486 thread->invoke_shutdown_hooks(); 4487 4488 before_exit(thread); 4489 4490 thread->exit(true); 4491 4492 // Stop VM thread. 4493 { 4494 // 4945125 The vm thread comes to a safepoint during exit. 4495 // GC vm_operations can get caught at the safepoint, and the 4496 // heap is unparseable if they are caught. Grab the Heap_lock 4497 // to prevent this. The GC vm_operations will not be able to 4498 // queue until after the vm thread is dead. After this point, 4499 // we'll never emerge out of the safepoint before the VM exits. 4500 4501 MutexLocker ml(Heap_lock); 4502 4503 VMThread::wait_for_vm_thread_exit(); 4504 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4505 VMThread::destroy(); 4506 } 4507 4508 // clean up ideal graph printers 4509 #if defined(COMPILER2) && !defined(PRODUCT) 4510 IdealGraphPrinter::clean_up(); 4511 #endif 4512 4513 // Now, all Java threads are gone except daemon threads. Daemon threads 4514 // running Java code or in VM are stopped by the Safepoint. However, 4515 // daemon threads executing native code are still running. But they 4516 // will be stopped at native=>Java/VM barriers. Note that we can't 4517 // simply kill or suspend them, as it is inherently deadlock-prone. 4518 4519 VM_Exit::set_vm_exited(); 4520 4521 notify_vm_shutdown(); 4522 4523 // We are after VM_Exit::set_vm_exited() so we can't call 4524 // thread->smr_delete() or we will block on the Threads_lock. 4525 // Deleting the shutdown thread here is safe because another 4526 // JavaThread cannot have an active ThreadsListHandle for 4527 // this JavaThread. 4528 delete thread; 4529 4530 #if INCLUDE_JVMCI 4531 if (JVMCICounterSize > 0) { 4532 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4533 } 4534 #endif 4535 4536 // exit_globals() will delete tty 4537 exit_globals(); 4538 4539 LogConfiguration::finalize(); 4540 4541 return true; 4542 } 4543 4544 4545 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4546 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4547 return is_supported_jni_version(version); 4548 } 4549 4550 4551 jboolean Threads::is_supported_jni_version(jint version) { 4552 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4553 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4554 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4555 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4556 if (version == JNI_VERSION_9) return JNI_TRUE; 4557 return JNI_FALSE; 4558 } 4559 4560 // Hash table of pointers found by a scan. Used for collecting hazard 4561 // pointers (ThreadsList references). Also used for collecting JavaThreads 4562 // that are indirectly referenced by hazard ptrs. An instance of this 4563 // class only contains one type of pointer. 4564 // 4565 class ThreadScanHashtable : public CHeapObj<mtThread> { 4566 private: 4567 static bool ptr_equals(void * const& s1, void * const& s2) { 4568 return s1 == s2; 4569 } 4570 4571 static unsigned int ptr_hash(void * const& s1) { 4572 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u); 4573 } 4574 4575 int _table_size; 4576 // ResourceHashtable SIZE is specified at compile time so our 4577 // dynamic _table_size is unused for now; 1031 is the first prime 4578 // after 1024. 4579 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash, 4580 &ThreadScanHashtable::ptr_equals, 1031, 4581 ResourceObj::C_HEAP, mtThread> PtrTable; 4582 PtrTable * _ptrs; 4583 4584 public: 4585 // ResourceHashtable is passed to various functions and populated in 4586 // different places so we allocate it using C_HEAP to make it immune 4587 // from any ResourceMarks that happen to be in the code paths. 4588 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {} 4589 4590 ~ThreadScanHashtable() { delete _ptrs; } 4591 4592 bool has_entry(void *pointer) { 4593 int *val_ptr = _ptrs->get(pointer); 4594 return val_ptr != NULL && *val_ptr == 1; 4595 } 4596 4597 void add_entry(void *pointer) { 4598 _ptrs->put(pointer, 1); 4599 } 4600 }; 4601 4602 // Closure to gather JavaThreads indirectly referenced by hazard ptrs 4603 // (ThreadsList references) into a hash table. This closure handles part 2 4604 // of the dance - adding all the JavaThreads referenced by the hazard 4605 // pointer (ThreadsList reference) to the hash table. 4606 // 4607 class AddThreadHazardPointerThreadClosure : public ThreadClosure { 4608 private: 4609 ThreadScanHashtable *_table; 4610 4611 public: 4612 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {} 4613 4614 virtual void do_thread(Thread *thread) { 4615 if (!_table->has_entry((void*)thread)) { 4616 // The same JavaThread might be on more than one ThreadsList or 4617 // more than one thread might be using the same ThreadsList. In 4618 // either case, we only need a single entry for a JavaThread. 4619 _table->add_entry((void*)thread); 4620 } 4621 } 4622 }; 4623 4624 // Closure to gather JavaThreads indirectly referenced by hazard ptrs 4625 // (ThreadsList references) into a hash table. This closure handles part 1 4626 // of the dance - hazard ptr chain walking and dispatch to another 4627 // closure. 4628 // 4629 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure { 4630 private: 4631 ThreadScanHashtable *_table; 4632 public: 4633 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {} 4634 4635 virtual void do_thread(Thread *thread) { 4636 assert_locked_or_safepoint(Threads_lock); 4637 4638 if (thread == NULL) return; 4639 4640 // This code races with Threads::acquire_stable_list() which is 4641 // lock-free so we have to handle some special situations. 4642 // 4643 ThreadsList *current_list = NULL; 4644 while (true) { 4645 current_list = thread->get_threads_hazard_ptr(); 4646 // No hazard ptr so nothing more to do. 4647 if (current_list == NULL) { 4648 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4649 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4650 return; 4651 } 4652 4653 // If the hazard ptr is verified as stable (since it is not tagged), 4654 // then it is safe to use. 4655 if (!Thread::is_hazard_ptr_tagged(current_list)) break; 4656 4657 // The hazard ptr is tagged as not yet verified as being stable 4658 // so we are racing with acquire_stable_list(). This exchange 4659 // attempts to invalidate the hazard ptr. If we win the race, 4660 // then we can ignore this unstable hazard ptr and the other 4661 // thread will retry the attempt to publish a stable hazard ptr. 4662 // If we lose the race, then we retry our attempt to look at the 4663 // hazard ptr. 4664 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return; 4665 } 4666 4667 // The current JavaThread has a hazard ptr (ThreadsList reference) 4668 // which might be _smr_java_thread_list or it might be an older 4669 // ThreadsList that has been removed but not freed. In either case, 4670 // the hazard ptr is protecting all the JavaThreads on that 4671 // ThreadsList. 4672 AddThreadHazardPointerThreadClosure add_cl(_table); 4673 current_list->threads_do(&add_cl); 4674 4675 // Any NestedThreadsLists are also protecting JavaThreads so 4676 // gather those also; the ThreadsLists may be different. 4677 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4678 node != NULL; node = node->next()) { 4679 node->t_list()->threads_do(&add_cl); 4680 } 4681 } 4682 }; 4683 4684 // Closure to print JavaThreads that have a hazard ptr (ThreadsList 4685 // reference) that contains an indirect reference to a specific JavaThread. 4686 // 4687 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure { 4688 private: 4689 JavaThread *_thread; 4690 public: 4691 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {} 4692 4693 virtual void do_thread(Thread *thread) { 4694 assert_locked_or_safepoint(Threads_lock); 4695 4696 if (thread == NULL) return; 4697 ThreadsList *current_list = thread->get_threads_hazard_ptr(); 4698 if (current_list == NULL) { 4699 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4700 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4701 return; 4702 } 4703 // If the hazard ptr is unverified, then ignore it. 4704 if (Thread::is_hazard_ptr_tagged(current_list)) return; 4705 4706 // The current JavaThread has a hazard ptr (ThreadsList reference) 4707 // which might be _smr_java_thread_list or it might be an older 4708 // ThreadsList that has been removed but not freed. In either case, 4709 // the hazard ptr is protecting all the JavaThreads on that 4710 // ThreadsList, but we only care about matching a specific JavaThread. 4711 DO_JAVA_THREADS(current_list, p) { 4712 if (p == _thread) { 4713 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); 4714 break; 4715 } 4716 } 4717 4718 // Any NestedThreadsLists are also protecting JavaThreads so 4719 // check those also; the ThreadsLists may be different. 4720 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4721 node != NULL; node = node->next()) { 4722 DO_JAVA_THREADS(node->t_list(), p) { 4723 if (p == _thread) { 4724 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); 4725 return; 4726 } 4727 } 4728 } 4729 } 4730 }; 4731 4732 // Return true if the specified JavaThread is protected by a hazard 4733 // pointer (ThreadsList reference). Otherwise, returns false. 4734 // 4735 bool Threads::is_a_protected_JavaThread(JavaThread *thread) { 4736 assert_locked_or_safepoint(Threads_lock); 4737 4738 // Hash table size should be first power of two higher than twice 4739 // the length of the Threads list. 4740 int hash_table_size = MIN2(_number_of_threads, 32) << 1; 4741 hash_table_size--; 4742 hash_table_size |= hash_table_size >> 1; 4743 hash_table_size |= hash_table_size >> 2; 4744 hash_table_size |= hash_table_size >> 4; 4745 hash_table_size |= hash_table_size >> 8; 4746 hash_table_size |= hash_table_size >> 16; 4747 hash_table_size++; 4748 4749 // Gather a hash table of the JavaThreads indirectly referenced by 4750 // hazard ptrs. 4751 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); 4752 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table); 4753 Threads::threads_do(&scan_cl); 4754 4755 bool thread_is_protected = false; 4756 if (scan_table->has_entry((void*)thread)) { 4757 thread_is_protected = true; 4758 } 4759 delete scan_table; 4760 return thread_is_protected; 4761 } 4762 4763 // Safely delete a JavaThread when it is no longer in use by a 4764 // ThreadsListHandle. 4765 // 4766 void Threads::smr_delete(JavaThread *thread) { 4767 assert(!Threads_lock->owned_by_self(), "sanity"); 4768 4769 bool has_logged_once = false; 4770 elapsedTimer timer; 4771 if (EnableThreadSMRStatistics) { 4772 timer.start(); 4773 } 4774 4775 while (true) { 4776 { 4777 // No safepoint check because this JavaThread is not on the 4778 // Threads list. 4779 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 4780 // Cannot use a MonitorLockerEx helper here because we have 4781 // to drop the Threads_lock first if we wait. 4782 Threads::smr_delete_lock()->lock_without_safepoint_check(); 4783 // Set the smr_delete_notify flag after we grab smr_delete_lock 4784 // and before we scan hazard ptrs because we're doing 4785 // double-check locking in release_stable_list(). 4786 Threads::set_smr_delete_notify(); 4787 4788 if (!is_a_protected_JavaThread(thread)) { 4789 // This is the common case. 4790 Threads::clear_smr_delete_notify(); 4791 Threads::smr_delete_lock()->unlock(); 4792 break; 4793 } 4794 if (!has_logged_once) { 4795 has_logged_once = true; 4796 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread)); 4797 if (log_is_enabled(Debug, os, thread)) { 4798 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread); 4799 Threads::threads_do(&scan_cl); 4800 } 4801 } 4802 } // We have to drop the Threads_lock to wait or delete the thread 4803 4804 if (EnableThreadSMRStatistics) { 4805 _smr_delete_lock_wait_cnt++; 4806 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) { 4807 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt; 4808 } 4809 } 4810 // Wait for a release_stable_list() call before we check again. No 4811 // safepoint check, no timeout, and not as suspend equivalent flag 4812 // because this JavaThread is not on the Threads list. 4813 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0, 4814 !Mutex::_as_suspend_equivalent_flag); 4815 if (EnableThreadSMRStatistics) { 4816 _smr_delete_lock_wait_cnt--; 4817 } 4818 4819 Threads::clear_smr_delete_notify(); 4820 Threads::smr_delete_lock()->unlock(); 4821 // Retry the whole scenario. 4822 } 4823 4824 delete thread; 4825 if (EnableThreadSMRStatistics) { 4826 timer.stop(); 4827 jint millis = (jint)timer.milliseconds(); 4828 Threads::inc_smr_deleted_thread_cnt(); 4829 Threads::add_smr_deleted_thread_times(millis); 4830 Threads::update_smr_deleted_thread_time_max(millis); 4831 } 4832 4833 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread)); 4834 } 4835 4836 bool Threads::smr_delete_notify() { 4837 // Use load_acquire() in order to see any updates to _smr_delete_notify 4838 // earlier than when smr_delete_lock is grabbed. 4839 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0); 4840 } 4841 4842 // set_smr_delete_notify() and clear_smr_delete_notify() are called 4843 // under the protection of the smr_delete_lock, but we also use an 4844 // Atomic operation to ensure the memory update is seen earlier than 4845 // when the smr_delete_lock is dropped. 4846 // 4847 void Threads::set_smr_delete_notify() { 4848 Atomic::inc(&_smr_delete_notify); 4849 } 4850 4851 void Threads::clear_smr_delete_notify() { 4852 Atomic::dec(&_smr_delete_notify); 4853 } 4854 4855 // Closure to gather hazard ptrs (ThreadsList references) into a hash table. 4856 // 4857 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure { 4858 private: 4859 ThreadScanHashtable *_table; 4860 public: 4861 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {} 4862 4863 virtual void do_thread(Thread* thread) { 4864 assert_locked_or_safepoint(Threads_lock); 4865 4866 if (thread == NULL) return; 4867 ThreadsList *threads = thread->get_threads_hazard_ptr(); 4868 if (threads == NULL) { 4869 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4870 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4871 return; 4872 } 4873 // In this closure we always ignore the tag that might mark this 4874 // hazard ptr as not yet verified. If we happen to catch an 4875 // unverified hazard ptr that is subsequently discarded (not 4876 // published), then the only side effect is that we might keep a 4877 // to-be-deleted ThreadsList alive a little longer. 4878 threads = Thread::untag_hazard_ptr(threads); 4879 if (!_table->has_entry((void*)threads)) { 4880 _table->add_entry((void*)threads); 4881 } 4882 4883 // Any NestedThreadsLists are also protecting JavaThreads so 4884 // gather those also; the ThreadsLists may be different. 4885 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4886 node != NULL; node = node->next()) { 4887 threads = node->t_list(); 4888 if (!_table->has_entry((void*)threads)) { 4889 _table->add_entry((void*)threads); 4890 } 4891 } 4892 } 4893 }; 4894 4895 // Safely free a ThreadsList after a Threads::add() or Threads::remove(). 4896 // The specified ThreadsList may not get deleted during this call if it 4897 // is still in-use (referenced by a hazard ptr). Other ThreadsLists 4898 // in the chain may get deleted by this call if they are no longer in-use. 4899 void Threads::smr_free_list(ThreadsList* threads) { 4900 assert_locked_or_safepoint(Threads_lock); 4901 4902 threads->set_next_list(_smr_to_delete_list); 4903 _smr_to_delete_list = threads; 4904 if (EnableThreadSMRStatistics) { 4905 _smr_to_delete_list_cnt++; 4906 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) { 4907 _smr_to_delete_list_max = _smr_to_delete_list_cnt; 4908 } 4909 } 4910 4911 // Hash table size should be first power of two higher than twice the length of the ThreadsList 4912 int hash_table_size = MIN2(_number_of_threads, 32) << 1; 4913 hash_table_size--; 4914 hash_table_size |= hash_table_size >> 1; 4915 hash_table_size |= hash_table_size >> 2; 4916 hash_table_size |= hash_table_size >> 4; 4917 hash_table_size |= hash_table_size >> 8; 4918 hash_table_size |= hash_table_size >> 16; 4919 hash_table_size++; 4920 4921 // Gather a hash table of the current hazard ptrs: 4922 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); 4923 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table); 4924 Threads::threads_do(&scan_cl); 4925 4926 // Walk through the linked list of pending freeable ThreadsLists 4927 // and free the ones that are not referenced from hazard ptrs. 4928 ThreadsList* current = _smr_to_delete_list; 4929 ThreadsList* prev = NULL; 4930 ThreadsList* next = NULL; 4931 bool threads_is_freed = false; 4932 while (current != NULL) { 4933 next = current->next_list(); 4934 if (!scan_table->has_entry((void*)current)) { 4935 // This ThreadsList is not referenced by a hazard ptr. 4936 if (prev != NULL) { 4937 prev->set_next_list(next); 4938 } 4939 if (_smr_to_delete_list == current) { 4940 _smr_to_delete_list = next; 4941 } 4942 4943 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current)); 4944 if (current == threads) threads_is_freed = true; 4945 delete current; 4946 if (EnableThreadSMRStatistics) { 4947 _smr_java_thread_list_free_cnt++; 4948 _smr_to_delete_list_cnt--; 4949 } 4950 } else { 4951 prev = current; 4952 } 4953 current = next; 4954 } 4955 4956 if (!threads_is_freed) { 4957 // Only report "is not freed" on the original call to 4958 // smr_free_list() for this ThreadsList. 4959 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads)); 4960 } 4961 4962 delete scan_table; 4963 } 4964 4965 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a 4966 // new copy of the specified ThreadsList with the specified JavaThread 4967 // removed. 4968 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) { 4969 assert(list->_length > 0, "sanity"); 4970 4971 uint i = 0; 4972 DO_JAVA_THREADS(list, current) { 4973 if (current == java_thread) { 4974 break; 4975 } 4976 i++; 4977 } 4978 assert(i < list->_length, "did not find JavaThread on the list"); 4979 const uint index = i; 4980 const uint new_length = list->_length - 1; 4981 const uint head_length = index; 4982 const uint tail_length = (new_length >= index) ? (new_length - index) : 0; 4983 ThreadsList *const new_list = new ThreadsList(new_length); 4984 4985 if (head_length > 0) { 4986 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); 4987 } 4988 if (tail_length > 0) { 4989 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length); 4990 } 4991 4992 return new_list; 4993 } 4994 4995 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a 4996 // new copy of the specified ThreadsList with the specified JavaThread 4997 // appended to the end. 4998 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) { 4999 const uint index = list->_length; 5000 const uint new_length = index + 1; 5001 const uint head_length = index; 5002 ThreadsList *const new_list = new ThreadsList(new_length); 5003 5004 if (head_length > 0) { 5005 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); 5006 } 5007 *(JavaThread**)(new_list->_threads + index) = java_thread; 5008 5009 return new_list; 5010 } 5011 5012 int ThreadsList::find_index_of_JavaThread(JavaThread *target) { 5013 if (target == NULL) { 5014 return -1; 5015 } 5016 for (uint i = 0; i < length(); i++) { 5017 if (target == thread_at(i)) { 5018 return (int)i; 5019 } 5020 } 5021 return -1; 5022 } 5023 5024 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const { 5025 DO_JAVA_THREADS(this, thread) { 5026 oop tobj = thread->threadObj(); 5027 // Ignore the thread if it hasn't run yet, has exited 5028 // or is starting to exit. 5029 if (tobj != NULL && !thread->is_exiting() && 5030 java_tid == java_lang_Thread::thread_id(tobj)) { 5031 // found a match 5032 return thread; 5033 } 5034 } 5035 return NULL; 5036 } 5037 5038 bool ThreadsList::includes(const JavaThread * const p) const { 5039 if (p == NULL) { 5040 return false; 5041 } 5042 DO_JAVA_THREADS(this, q) { 5043 if (q == p) { 5044 return true; 5045 } 5046 } 5047 return false; 5048 } 5049 5050 void Threads::add(JavaThread* p, bool force_daemon) { 5051 // The threads lock must be owned at this point 5052 assert_locked_or_safepoint(Threads_lock); 5053 5054 // See the comment for this method in thread.hpp for its purpose and 5055 // why it is called here. 5056 p->initialize_queues(); 5057 p->set_next(_thread_list); 5058 _thread_list = p; 5059 5060 // Once a JavaThread is added to the Threads list, smr_delete() has 5061 // to be used to delete it. Otherwise we can just delete it directly. 5062 p->set_on_thread_list(); 5063 5064 _number_of_threads++; 5065 oop threadObj = p->threadObj(); 5066 bool daemon = true; 5067 // Bootstrapping problem: threadObj can be null for initial 5068 // JavaThread (or for threads attached via JNI) 5069 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 5070 _number_of_non_daemon_threads++; 5071 daemon = false; 5072 } 5073 5074 ThreadService::add_thread(p, daemon); 5075 5076 // Maintain fast thread list 5077 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p); 5078 if (EnableThreadSMRStatistics) { 5079 _smr_java_thread_list_alloc_cnt++; 5080 if (new_list->length() > _smr_java_thread_list_max) { 5081 _smr_java_thread_list_max = new_list->length(); 5082 } 5083 } 5084 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg. 5085 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); 5086 5087 ThreadsList *old_list = xchg_smr_java_thread_list(new_list); 5088 smr_free_list(old_list); 5089 5090 // Possible GC point. 5091 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 5092 } 5093 5094 void Threads::remove(JavaThread* p) { 5095 5096 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 5097 ObjectSynchronizer::omFlush(p); 5098 5099 // Extra scope needed for Thread_lock, so we can check 5100 // that we do not remove thread without safepoint code notice 5101 { MutexLocker ml(Threads_lock); 5102 5103 assert(get_smr_java_thread_list()->includes(p), "p must be present"); 5104 5105 // Maintain fast thread list 5106 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p); 5107 if (EnableThreadSMRStatistics) { 5108 _smr_java_thread_list_alloc_cnt++; 5109 // This list is smaller so no need to check for a "longest" update. 5110 } 5111 5112 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg. 5113 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); 5114 5115 ThreadsList *old_list = xchg_smr_java_thread_list(new_list); 5116 smr_free_list(old_list); 5117 5118 JavaThread* current = _thread_list; 5119 JavaThread* prev = NULL; 5120 5121 while (current != p) { 5122 prev = current; 5123 current = current->next(); 5124 } 5125 5126 if (prev) { 5127 prev->set_next(current->next()); 5128 } else { 5129 _thread_list = p->next(); 5130 } 5131 5132 _number_of_threads--; 5133 oop threadObj = p->threadObj(); 5134 bool daemon = true; 5135 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 5136 _number_of_non_daemon_threads--; 5137 daemon = false; 5138 5139 // Only one thread left, do a notify on the Threads_lock so a thread waiting 5140 // on destroy_vm will wake up. 5141 if (number_of_non_daemon_threads() == 1) { 5142 Threads_lock->notify_all(); 5143 } 5144 } 5145 ThreadService::remove_thread(p, daemon); 5146 5147 // Make sure that safepoint code disregard this thread. This is needed since 5148 // the thread might mess around with locks after this point. This can cause it 5149 // to do callbacks into the safepoint code. However, the safepoint code is not aware 5150 // of this thread since it is removed from the queue. 5151 p->set_terminated_value(); 5152 } // unlock Threads_lock 5153 5154 // Since Events::log uses a lock, we grab it outside the Threads_lock 5155 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 5156 } 5157 5158 // Operations on the Threads list for GC. These are not explicitly locked, 5159 // but the garbage collector must provide a safe context for them to run. 5160 // In particular, these things should never be called when the Threads_lock 5161 // is held by some other thread. (Note: the Safepoint abstraction also 5162 // uses the Threads_lock to guarantee this property. It also makes sure that 5163 // all threads gets blocked when exiting or starting). 5164 5165 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 5166 ALL_JAVA_THREADS(p) { 5167 p->oops_do(f, cf); 5168 } 5169 VMThread::vm_thread()->oops_do(f, cf); 5170 } 5171 5172 void Threads::change_thread_claim_parity() { 5173 // Set the new claim parity. 5174 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 5175 "Not in range."); 5176 _thread_claim_parity++; 5177 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 5178 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 5179 "Not in range."); 5180 } 5181 5182 #ifdef ASSERT 5183 void Threads::assert_all_threads_claimed() { 5184 ALL_JAVA_THREADS(p) { 5185 const int thread_parity = p->oops_do_parity(); 5186 assert((thread_parity == _thread_claim_parity), 5187 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 5188 } 5189 VMThread* vmt = VMThread::vm_thread(); 5190 const int thread_parity = vmt->oops_do_parity(); 5191 assert((thread_parity == _thread_claim_parity), 5192 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 5193 } 5194 #endif // ASSERT 5195 5196 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 5197 int cp = Threads::thread_claim_parity(); 5198 ALL_JAVA_THREADS(p) { 5199 if (p->claim_oops_do(is_par, cp)) { 5200 p->oops_do(f, cf); 5201 } 5202 } 5203 VMThread* vmt = VMThread::vm_thread(); 5204 if (vmt->claim_oops_do(is_par, cp)) { 5205 vmt->oops_do(f, cf); 5206 } 5207 } 5208 5209 #if INCLUDE_ALL_GCS 5210 // Used by ParallelScavenge 5211 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 5212 ALL_JAVA_THREADS(p) { 5213 q->enqueue(new ThreadRootsTask(p)); 5214 } 5215 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 5216 } 5217 5218 // Used by Parallel Old 5219 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 5220 ALL_JAVA_THREADS(p) { 5221 q->enqueue(new ThreadRootsMarkingTask(p)); 5222 } 5223 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 5224 } 5225 #endif // INCLUDE_ALL_GCS 5226 5227 void Threads::nmethods_do(CodeBlobClosure* cf) { 5228 ALL_JAVA_THREADS(p) { 5229 // This is used by the code cache sweeper to mark nmethods that are active 5230 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 5231 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 5232 if(!p->is_Code_cache_sweeper_thread()) { 5233 p->nmethods_do(cf); 5234 } 5235 } 5236 } 5237 5238 void Threads::metadata_do(void f(Metadata*)) { 5239 ALL_JAVA_THREADS(p) { 5240 p->metadata_do(f); 5241 } 5242 } 5243 5244 class ThreadHandlesClosure : public ThreadClosure { 5245 void (*_f)(Metadata*); 5246 public: 5247 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 5248 virtual void do_thread(Thread* thread) { 5249 thread->metadata_handles_do(_f); 5250 } 5251 }; 5252 5253 void Threads::metadata_handles_do(void f(Metadata*)) { 5254 // Only walk the Handles in Thread. 5255 ThreadHandlesClosure handles_closure(f); 5256 threads_do(&handles_closure); 5257 } 5258 5259 void Threads::deoptimized_wrt_marked_nmethods() { 5260 ALL_JAVA_THREADS(p) { 5261 p->deoptimized_wrt_marked_nmethods(); 5262 } 5263 } 5264 5265 5266 // Get count Java threads that are waiting to enter the specified monitor. 5267 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 5268 int count, 5269 address monitor) { 5270 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 5271 5272 int i = 0; 5273 DO_JAVA_THREADS(t_list, p) { 5274 if (!p->can_call_java()) continue; 5275 5276 address pending = (address)p->current_pending_monitor(); 5277 if (pending == monitor) { // found a match 5278 if (i < count) result->append(p); // save the first count matches 5279 i++; 5280 } 5281 } 5282 5283 return result; 5284 } 5285 5286 5287 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 5288 address owner) { 5289 // NULL owner means not locked so we can skip the search 5290 if (owner == NULL) return NULL; 5291 5292 DO_JAVA_THREADS(t_list, p) { 5293 // first, see if owner is the address of a Java thread 5294 if (owner == (address)p) return p; 5295 } 5296 5297 // Cannot assert on lack of success here since this function may be 5298 // used by code that is trying to report useful problem information 5299 // like deadlock detection. 5300 if (UseHeavyMonitors) return NULL; 5301 5302 // If we didn't find a matching Java thread and we didn't force use of 5303 // heavyweight monitors, then the owner is the stack address of the 5304 // Lock Word in the owning Java thread's stack. 5305 // 5306 JavaThread* the_owner = NULL; 5307 DO_JAVA_THREADS(t_list, q) { 5308 if (q->is_lock_owned(owner)) { 5309 the_owner = q; 5310 break; 5311 } 5312 } 5313 5314 // cannot assert on lack of success here; see above comment 5315 return the_owner; 5316 } 5317 5318 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 5319 void Threads::print_on(outputStream* st, bool print_stacks, 5320 bool internal_format, bool print_concurrent_locks) { 5321 char buf[32]; 5322 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 5323 5324 st->print_cr("Full thread dump %s (%s %s):", 5325 Abstract_VM_Version::vm_name(), 5326 Abstract_VM_Version::vm_release(), 5327 Abstract_VM_Version::vm_info_string()); 5328 st->cr(); 5329 5330 #if INCLUDE_SERVICES 5331 // Dump concurrent locks 5332 ConcurrentLocksDump concurrent_locks; 5333 if (print_concurrent_locks) { 5334 concurrent_locks.dump_at_safepoint(); 5335 } 5336 #endif // INCLUDE_SERVICES 5337 5338 print_smr_info_on(st); 5339 st->cr(); 5340 5341 ALL_JAVA_THREADS(p) { 5342 ResourceMark rm; 5343 p->print_on(st); 5344 if (print_stacks) { 5345 if (internal_format) { 5346 p->trace_stack(); 5347 } else { 5348 p->print_stack_on(st); 5349 } 5350 } 5351 st->cr(); 5352 #if INCLUDE_SERVICES 5353 if (print_concurrent_locks) { 5354 concurrent_locks.print_locks_on(p, st); 5355 } 5356 #endif // INCLUDE_SERVICES 5357 } 5358 5359 VMThread::vm_thread()->print_on(st); 5360 st->cr(); 5361 Universe::heap()->print_gc_threads_on(st); 5362 WatcherThread* wt = WatcherThread::watcher_thread(); 5363 if (wt != NULL) { 5364 wt->print_on(st); 5365 st->cr(); 5366 } 5367 5368 st->flush(); 5369 } 5370 5371 // Log Threads class SMR info. 5372 void Threads::log_smr_statistics() { 5373 LogTarget(Info, thread, smr) log; 5374 if (log.is_enabled()) { 5375 LogStream out(log); 5376 print_smr_info_on(&out); 5377 } 5378 } 5379 5380 // Print Threads class SMR info. 5381 void Threads::print_smr_info_on(outputStream* st) { 5382 // Only grab the Threads_lock if we don't already own it 5383 // and if we are not reporting an error. 5384 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock); 5385 5386 st->print_cr("Threads class SMR info:"); 5387 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, " 5388 "elements={", p2i(_smr_java_thread_list), 5389 _smr_java_thread_list->length()); 5390 print_smr_info_elements_on(st, _smr_java_thread_list); 5391 st->print_cr("}"); 5392 if (_smr_to_delete_list != NULL) { 5393 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, " 5394 "elements={", p2i(_smr_to_delete_list), 5395 _smr_to_delete_list->length()); 5396 print_smr_info_elements_on(st, _smr_to_delete_list); 5397 st->print_cr("}"); 5398 for (ThreadsList *t_list = _smr_to_delete_list->next_list(); 5399 t_list != NULL; t_list = t_list->next_list()) { 5400 st->print("next-> " INTPTR_FORMAT ", length=%u, " 5401 "elements={", p2i(t_list), t_list->length()); 5402 print_smr_info_elements_on(st, t_list); 5403 st->print_cr("}"); 5404 } 5405 } 5406 if (!EnableThreadSMRStatistics) { 5407 return; 5408 } 5409 st->print_cr("_smr_java_thread_list_alloc_cnt=%ld, " 5410 "_smr_java_thread_list_free_cnt=%ld, " 5411 "_smr_java_thread_list_max=%u, " 5412 "_smr_nested_thread_list_max=%u", 5413 _smr_java_thread_list_alloc_cnt, 5414 _smr_java_thread_list_free_cnt, 5415 _smr_java_thread_list_max, 5416 _smr_nested_thread_list_max); 5417 if (_smr_tlh_cnt > 0) { 5418 st->print_cr("_smr_tlh_cnt=" INT32_FORMAT 5419 ", _smr_tlh_times=" INT32_FORMAT 5420 ", avg_smr_tlh_time=%0.2f" 5421 ", _smr_tlh_time_max=" INT32_FORMAT, 5422 _smr_tlh_cnt, _smr_tlh_times, 5423 ((double) _smr_tlh_times / _smr_tlh_cnt), 5424 _smr_tlh_time_max); 5425 } 5426 if (_smr_deleted_thread_cnt > 0) { 5427 st->print_cr("_smr_deleted_thread_cnt=" INT32_FORMAT 5428 ", _smr_deleted_thread_times=" INT32_FORMAT 5429 ", avg_smr_deleted_thread_time=%0.2f" 5430 ", _smr_deleted_thread_time_max=" INT32_FORMAT, 5431 _smr_deleted_thread_cnt, _smr_deleted_thread_times, 5432 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt), 5433 _smr_deleted_thread_time_max); 5434 } 5435 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u", 5436 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max); 5437 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u", 5438 _smr_to_delete_list_cnt, _smr_to_delete_list_max); 5439 } 5440 5441 // Print ThreadsList elements (4 per line). 5442 void Threads::print_smr_info_elements_on(outputStream* st, 5443 ThreadsList* t_list) { 5444 uint cnt = 0; 5445 JavaThreadIterator jti(t_list); 5446 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) { 5447 st->print(INTPTR_FORMAT, p2i(jt)); 5448 if (cnt < t_list->length() - 1) { 5449 // Separate with comma or comma-space except for the last one. 5450 if (((cnt + 1) % 4) == 0) { 5451 // Four INTPTR_FORMAT fit on an 80 column line so end the 5452 // current line with just a comma. 5453 st->print_cr(","); 5454 } else { 5455 // Not the last one on the current line so use comma-space: 5456 st->print(", "); 5457 } 5458 } else { 5459 // Last one so just end the current line. 5460 st->cr(); 5461 } 5462 cnt++; 5463 } 5464 } 5465 5466 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 5467 int buflen, bool* found_current) { 5468 if (this_thread != NULL) { 5469 bool is_current = (current == this_thread); 5470 *found_current = *found_current || is_current; 5471 st->print("%s", is_current ? "=>" : " "); 5472 5473 st->print(PTR_FORMAT, p2i(this_thread)); 5474 st->print(" "); 5475 this_thread->print_on_error(st, buf, buflen); 5476 st->cr(); 5477 } 5478 } 5479 5480 class PrintOnErrorClosure : public ThreadClosure { 5481 outputStream* _st; 5482 Thread* _current; 5483 char* _buf; 5484 int _buflen; 5485 bool* _found_current; 5486 public: 5487 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 5488 int buflen, bool* found_current) : 5489 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 5490 5491 virtual void do_thread(Thread* thread) { 5492 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 5493 } 5494 }; 5495 5496 // Threads::print_on_error() is called by fatal error handler. It's possible 5497 // that VM is not at safepoint and/or current thread is inside signal handler. 5498 // Don't print stack trace, as the stack may not be walkable. Don't allocate 5499 // memory (even in resource area), it might deadlock the error handler. 5500 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 5501 int buflen) { 5502 print_smr_info_on(st); 5503 st->cr(); 5504 5505 bool found_current = false; 5506 st->print_cr("Java Threads: ( => current thread )"); 5507 ALL_JAVA_THREADS(thread) { 5508 print_on_error(thread, st, current, buf, buflen, &found_current); 5509 } 5510 st->cr(); 5511 5512 st->print_cr("Other Threads:"); 5513 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 5514 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 5515 5516 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 5517 Universe::heap()->gc_threads_do(&print_closure); 5518 5519 if (!found_current) { 5520 st->cr(); 5521 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 5522 current->print_on_error(st, buf, buflen); 5523 st->cr(); 5524 } 5525 st->cr(); 5526 5527 st->print_cr("Threads with active compile tasks:"); 5528 print_threads_compiling(st, buf, buflen); 5529 } 5530 5531 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 5532 ALL_JAVA_THREADS(thread) { 5533 if (thread->is_Compiler_thread()) { 5534 CompilerThread* ct = (CompilerThread*) thread; 5535 if (ct->task() != NULL) { 5536 thread->print_name_on_error(st, buf, buflen); 5537 ct->task()->print(st, NULL, true, true); 5538 } 5539 } 5540 } 5541 } 5542 5543 5544 // Internal SpinLock and Mutex 5545 // Based on ParkEvent 5546 5547 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 5548 // 5549 // We employ SpinLocks _only for low-contention, fixed-length 5550 // short-duration critical sections where we're concerned 5551 // about native mutex_t or HotSpot Mutex:: latency. 5552 // The mux construct provides a spin-then-block mutual exclusion 5553 // mechanism. 5554 // 5555 // Testing has shown that contention on the ListLock guarding gFreeList 5556 // is common. If we implement ListLock as a simple SpinLock it's common 5557 // for the JVM to devolve to yielding with little progress. This is true 5558 // despite the fact that the critical sections protected by ListLock are 5559 // extremely short. 5560 // 5561 // TODO-FIXME: ListLock should be of type SpinLock. 5562 // We should make this a 1st-class type, integrated into the lock 5563 // hierarchy as leaf-locks. Critically, the SpinLock structure 5564 // should have sufficient padding to avoid false-sharing and excessive 5565 // cache-coherency traffic. 5566 5567 5568 typedef volatile int SpinLockT; 5569 5570 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 5571 if (Atomic::cmpxchg (1, adr, 0) == 0) { 5572 return; // normal fast-path return 5573 } 5574 5575 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 5576 TEVENT(SpinAcquire - ctx); 5577 int ctr = 0; 5578 int Yields = 0; 5579 for (;;) { 5580 while (*adr != 0) { 5581 ++ctr; 5582 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 5583 if (Yields > 5) { 5584 os::naked_short_sleep(1); 5585 } else { 5586 os::naked_yield(); 5587 ++Yields; 5588 } 5589 } else { 5590 SpinPause(); 5591 } 5592 } 5593 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 5594 } 5595 } 5596 5597 void Thread::SpinRelease(volatile int * adr) { 5598 assert(*adr != 0, "invariant"); 5599 OrderAccess::fence(); // guarantee at least release consistency. 5600 // Roach-motel semantics. 5601 // It's safe if subsequent LDs and STs float "up" into the critical section, 5602 // but prior LDs and STs within the critical section can't be allowed 5603 // to reorder or float past the ST that releases the lock. 5604 // Loads and stores in the critical section - which appear in program 5605 // order before the store that releases the lock - must also appear 5606 // before the store that releases the lock in memory visibility order. 5607 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 5608 // the ST of 0 into the lock-word which releases the lock, so fence 5609 // more than covers this on all platforms. 5610 *adr = 0; 5611 } 5612 5613 // muxAcquire and muxRelease: 5614 // 5615 // * muxAcquire and muxRelease support a single-word lock-word construct. 5616 // The LSB of the word is set IFF the lock is held. 5617 // The remainder of the word points to the head of a singly-linked list 5618 // of threads blocked on the lock. 5619 // 5620 // * The current implementation of muxAcquire-muxRelease uses its own 5621 // dedicated Thread._MuxEvent instance. If we're interested in 5622 // minimizing the peak number of extant ParkEvent instances then 5623 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 5624 // as certain invariants were satisfied. Specifically, care would need 5625 // to be taken with regards to consuming unpark() "permits". 5626 // A safe rule of thumb is that a thread would never call muxAcquire() 5627 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 5628 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 5629 // consume an unpark() permit intended for monitorenter, for instance. 5630 // One way around this would be to widen the restricted-range semaphore 5631 // implemented in park(). Another alternative would be to provide 5632 // multiple instances of the PlatformEvent() for each thread. One 5633 // instance would be dedicated to muxAcquire-muxRelease, for instance. 5634 // 5635 // * Usage: 5636 // -- Only as leaf locks 5637 // -- for short-term locking only as muxAcquire does not perform 5638 // thread state transitions. 5639 // 5640 // Alternatives: 5641 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 5642 // but with parking or spin-then-park instead of pure spinning. 5643 // * Use Taura-Oyama-Yonenzawa locks. 5644 // * It's possible to construct a 1-0 lock if we encode the lockword as 5645 // (List,LockByte). Acquire will CAS the full lockword while Release 5646 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 5647 // acquiring threads use timers (ParkTimed) to detect and recover from 5648 // the stranding window. Thread/Node structures must be aligned on 256-byte 5649 // boundaries by using placement-new. 5650 // * Augment MCS with advisory back-link fields maintained with CAS(). 5651 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 5652 // The validity of the backlinks must be ratified before we trust the value. 5653 // If the backlinks are invalid the exiting thread must back-track through the 5654 // the forward links, which are always trustworthy. 5655 // * Add a successor indication. The LockWord is currently encoded as 5656 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 5657 // to provide the usual futile-wakeup optimization. 5658 // See RTStt for details. 5659 // * Consider schedctl.sc_nopreempt to cover the critical section. 5660 // 5661 5662 5663 typedef volatile intptr_t MutexT; // Mux Lock-word 5664 enum MuxBits { LOCKBIT = 1 }; 5665 5666 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 5667 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 5668 if (w == 0) return; 5669 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5670 return; 5671 } 5672 5673 TEVENT(muxAcquire - Contention); 5674 ParkEvent * const Self = Thread::current()->_MuxEvent; 5675 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 5676 for (;;) { 5677 int its = (os::is_MP() ? 100 : 0) + 1; 5678 5679 // Optional spin phase: spin-then-park strategy 5680 while (--its >= 0) { 5681 w = *Lock; 5682 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5683 return; 5684 } 5685 } 5686 5687 Self->reset(); 5688 Self->OnList = intptr_t(Lock); 5689 // The following fence() isn't _strictly necessary as the subsequent 5690 // CAS() both serializes execution and ratifies the fetched *Lock value. 5691 OrderAccess::fence(); 5692 for (;;) { 5693 w = *Lock; 5694 if ((w & LOCKBIT) == 0) { 5695 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5696 Self->OnList = 0; // hygiene - allows stronger asserts 5697 return; 5698 } 5699 continue; // Interference -- *Lock changed -- Just retry 5700 } 5701 assert(w & LOCKBIT, "invariant"); 5702 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5703 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 5704 } 5705 5706 while (Self->OnList != 0) { 5707 Self->park(); 5708 } 5709 } 5710 } 5711 5712 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 5713 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 5714 if (w == 0) return; 5715 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5716 return; 5717 } 5718 5719 TEVENT(muxAcquire - Contention); 5720 ParkEvent * ReleaseAfter = NULL; 5721 if (ev == NULL) { 5722 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 5723 } 5724 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 5725 for (;;) { 5726 guarantee(ev->OnList == 0, "invariant"); 5727 int its = (os::is_MP() ? 100 : 0) + 1; 5728 5729 // Optional spin phase: spin-then-park strategy 5730 while (--its >= 0) { 5731 w = *Lock; 5732 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5733 if (ReleaseAfter != NULL) { 5734 ParkEvent::Release(ReleaseAfter); 5735 } 5736 return; 5737 } 5738 } 5739 5740 ev->reset(); 5741 ev->OnList = intptr_t(Lock); 5742 // The following fence() isn't _strictly necessary as the subsequent 5743 // CAS() both serializes execution and ratifies the fetched *Lock value. 5744 OrderAccess::fence(); 5745 for (;;) { 5746 w = *Lock; 5747 if ((w & LOCKBIT) == 0) { 5748 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 5749 ev->OnList = 0; 5750 // We call ::Release while holding the outer lock, thus 5751 // artificially lengthening the critical section. 5752 // Consider deferring the ::Release() until the subsequent unlock(), 5753 // after we've dropped the outer lock. 5754 if (ReleaseAfter != NULL) { 5755 ParkEvent::Release(ReleaseAfter); 5756 } 5757 return; 5758 } 5759 continue; // Interference -- *Lock changed -- Just retry 5760 } 5761 assert(w & LOCKBIT, "invariant"); 5762 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5763 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 5764 } 5765 5766 while (ev->OnList != 0) { 5767 ev->park(); 5768 } 5769 } 5770 } 5771 5772 // Release() must extract a successor from the list and then wake that thread. 5773 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5774 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5775 // Release() would : 5776 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5777 // (B) Extract a successor from the private list "in-hand" 5778 // (C) attempt to CAS() the residual back into *Lock over null. 5779 // If there were any newly arrived threads and the CAS() would fail. 5780 // In that case Release() would detach the RATs, re-merge the list in-hand 5781 // with the RATs and repeat as needed. Alternately, Release() might 5782 // detach and extract a successor, but then pass the residual list to the wakee. 5783 // The wakee would be responsible for reattaching and remerging before it 5784 // competed for the lock. 5785 // 5786 // Both "pop" and DMR are immune from ABA corruption -- there can be 5787 // multiple concurrent pushers, but only one popper or detacher. 5788 // This implementation pops from the head of the list. This is unfair, 5789 // but tends to provide excellent throughput as hot threads remain hot. 5790 // (We wake recently run threads first). 5791 // 5792 // All paths through muxRelease() will execute a CAS. 5793 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5794 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5795 // executed within the critical section are complete and globally visible before the 5796 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5797 void Thread::muxRelease(volatile intptr_t * Lock) { 5798 for (;;) { 5799 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 5800 assert(w & LOCKBIT, "invariant"); 5801 if (w == LOCKBIT) return; 5802 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5803 assert(List != NULL, "invariant"); 5804 assert(List->OnList == intptr_t(Lock), "invariant"); 5805 ParkEvent * const nxt = List->ListNext; 5806 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5807 5808 // The following CAS() releases the lock and pops the head element. 5809 // The CAS() also ratifies the previously fetched lock-word value. 5810 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 5811 continue; 5812 } 5813 List->OnList = 0; 5814 OrderAccess::fence(); 5815 List->unpark(); 5816 return; 5817 } 5818 } 5819 5820 5821 void Threads::verify() { 5822 ALL_JAVA_THREADS(p) { 5823 p->verify(); 5824 } 5825 VMThread* thread = VMThread::vm_thread(); 5826 if (thread != NULL) thread->verify(); 5827 }