Mercurial > hg > graal-compiler
view src/share/vm/runtime/vmThread.cpp @ 1438:a7a0ef3c6858
Added timing printout on VM shutdown.
author | Thomas Wuerthinger <wuerthinger@ssw.jku.at> |
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date | Mon, 25 Oct 2010 18:35:34 +0200 |
parents | e392695de029 |
children | cff162798819 |
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/* * Copyright 1998-2010 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ # include "incls/_precompiled.incl" # include "incls/_vmThread.cpp.incl" HS_DTRACE_PROBE_DECL3(hotspot, vmops__request, char *, uintptr_t, int); HS_DTRACE_PROBE_DECL3(hotspot, vmops__begin, char *, uintptr_t, int); HS_DTRACE_PROBE_DECL3(hotspot, vmops__end, char *, uintptr_t, int); // Dummy VM operation to act as first element in our circular double-linked list class VM_Dummy: public VM_Operation { VMOp_Type type() const { return VMOp_Dummy; } void doit() {}; }; VMOperationQueue::VMOperationQueue() { // The queue is a circular doubled-linked list, which always contains // one element (i.e., one element means empty). for(int i = 0; i < nof_priorities; i++) { _queue_length[i] = 0; _queue_counter = 0; _queue[i] = new VM_Dummy(); _queue[i]->set_next(_queue[i]); _queue[i]->set_prev(_queue[i]); } _drain_list = NULL; } bool VMOperationQueue::queue_empty(int prio) { // It is empty if there is exactly one element bool empty = (_queue[prio] == _queue[prio]->next()); assert( (_queue_length[prio] == 0 && empty) || (_queue_length[prio] > 0 && !empty), "sanity check"); return _queue_length[prio] == 0; } // Inserts an element to the right of the q element void VMOperationQueue::insert(VM_Operation* q, VM_Operation* n) { assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); n->set_prev(q); n->set_next(q->next()); q->next()->set_prev(n); q->set_next(n); } void VMOperationQueue::queue_add_front(int prio, VM_Operation *op) { _queue_length[prio]++; insert(_queue[prio]->next(), op); } void VMOperationQueue::queue_add_back(int prio, VM_Operation *op) { _queue_length[prio]++; insert(_queue[prio]->prev(), op); } void VMOperationQueue::unlink(VM_Operation* q) { assert(q->next()->prev() == q && q->prev()->next() == q, "sanity check"); q->prev()->set_next(q->next()); q->next()->set_prev(q->prev()); } VM_Operation* VMOperationQueue::queue_remove_front(int prio) { if (queue_empty(prio)) return NULL; assert(_queue_length[prio] >= 0, "sanity check"); _queue_length[prio]--; VM_Operation* r = _queue[prio]->next(); assert(r != _queue[prio], "cannot remove base element"); unlink(r); return r; } VM_Operation* VMOperationQueue::queue_drain(int prio) { if (queue_empty(prio)) return NULL; DEBUG_ONLY(int length = _queue_length[prio];); assert(length >= 0, "sanity check"); _queue_length[prio] = 0; VM_Operation* r = _queue[prio]->next(); assert(r != _queue[prio], "cannot remove base element"); // remove links to base element from head and tail r->set_prev(NULL); _queue[prio]->prev()->set_next(NULL); // restore queue to empty state _queue[prio]->set_next(_queue[prio]); _queue[prio]->set_prev(_queue[prio]); assert(queue_empty(prio), "drain corrupted queue") #ifdef DEBUG int len = 0; VM_Operation* cur; for(cur = r; cur != NULL; cur=cur->next()) len++; assert(len == length, "drain lost some ops"); #endif return r; } void VMOperationQueue::queue_oops_do(int queue, OopClosure* f) { VM_Operation* cur = _queue[queue]; cur = cur->next(); while (cur != _queue[queue]) { cur->oops_do(f); cur = cur->next(); } } void VMOperationQueue::drain_list_oops_do(OopClosure* f) { VM_Operation* cur = _drain_list; while (cur != NULL) { cur->oops_do(f); cur = cur->next(); } } //----------------------------------------------------------------- // High-level interface bool VMOperationQueue::add(VM_Operation *op) { HS_DTRACE_PROBE3(hotspot, vmops__request, op->name(), strlen(op->name()), op->evaluation_mode()); // Encapsulates VM queue policy. Currently, that // only involves putting them on the right list if (op->evaluate_at_safepoint()) { queue_add_back(SafepointPriority, op); return true; } queue_add_back(MediumPriority, op); return true; } VM_Operation* VMOperationQueue::remove_next() { // Assuming VMOperation queue is two-level priority queue. If there are // more than two priorities, we need a different scheduling algorithm. assert(SafepointPriority == 0 && MediumPriority == 1 && nof_priorities == 2, "current algorithm does not work"); // simple counter based scheduling to prevent starvation of lower priority // queue. -- see 4390175 int high_prio, low_prio; if (_queue_counter++ < 10) { high_prio = SafepointPriority; low_prio = MediumPriority; } else { _queue_counter = 0; high_prio = MediumPriority; low_prio = SafepointPriority; } return queue_remove_front(queue_empty(high_prio) ? low_prio : high_prio); } void VMOperationQueue::oops_do(OopClosure* f) { for(int i = 0; i < nof_priorities; i++) { queue_oops_do(i, f); } drain_list_oops_do(f); } //------------------------------------------------------------------------------------------------------------------ // Implementation of VMThread stuff bool VMThread::_should_terminate = false; bool VMThread::_terminated = false; Monitor* VMThread::_terminate_lock = NULL; VMThread* VMThread::_vm_thread = NULL; VM_Operation* VMThread::_cur_vm_operation = NULL; VMOperationQueue* VMThread::_vm_queue = NULL; PerfCounter* VMThread::_perf_accumulated_vm_operation_time = NULL; void VMThread::create() { assert(vm_thread() == NULL, "we can only allocate one VMThread"); _vm_thread = new VMThread(); // Create VM operation queue _vm_queue = new VMOperationQueue(); guarantee(_vm_queue != NULL, "just checking"); _terminate_lock = new Monitor(Mutex::safepoint, "VMThread::_terminate_lock", true); if (UsePerfData) { // jvmstat performance counters Thread* THREAD = Thread::current(); _perf_accumulated_vm_operation_time = PerfDataManager::create_counter(SUN_THREADS, "vmOperationTime", PerfData::U_Ticks, CHECK); } } VMThread::VMThread() : NamedThread() { set_name("VM Thread"); } void VMThread::destroy() { if (_vm_thread != NULL) { delete _vm_thread; _vm_thread = NULL; // VM thread is gone } } void VMThread::run() { assert(this == vm_thread(), "check"); this->initialize_thread_local_storage(); this->record_stack_base_and_size(); // Notify_lock wait checks on active_handles() to rewait in // case of spurious wakeup, it should wait on the last // value set prior to the notify this->set_active_handles(JNIHandleBlock::allocate_block()); { MutexLocker ml(Notify_lock); Notify_lock->notify(); } // Notify_lock is destroyed by Threads::create_vm() int prio = (VMThreadPriority == -1) ? os::java_to_os_priority[NearMaxPriority] : VMThreadPriority; // Note that I cannot call os::set_priority because it expects Java // priorities and I am *explicitly* using OS priorities so that it's // possible to set the VM thread priority higher than any Java thread. os::set_native_priority( this, prio ); // Wait for VM_Operations until termination this->loop(); // Note the intention to exit before safepointing. // 6295565 This has the effect of waiting for any large tty // outputs to finish. if (xtty != NULL) { ttyLocker ttyl; xtty->begin_elem("destroy_vm"); xtty->stamp(); xtty->end_elem(); assert(should_terminate(), "termination flag must be set"); } // 4526887 let VM thread exit at Safepoint SafepointSynchronize::begin(); if (VerifyBeforeExit) { HandleMark hm(VMThread::vm_thread()); // Among other things, this ensures that Eden top is correct. Universe::heap()->prepare_for_verify(); os::check_heap(); Universe::verify(true, true); // Silent verification to not polute normal output } CompileBroker::set_should_block(); // wait for threads (compiler threads or daemon threads) in the // _thread_in_native state to block. VM_Exit::wait_for_threads_in_native_to_block(); // signal other threads that VM process is gone { // Note: we must have the _no_safepoint_check_flag. Mutex::lock() allows // VM thread to enter any lock at Safepoint as long as its _owner is NULL. // If that happens after _terminate_lock->wait() has unset _owner // but before it actually drops the lock and waits, the notification below // may get lost and we will have a hang. To avoid this, we need to use // Mutex::lock_without_safepoint_check(). MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); _terminated = true; _terminate_lock->notify(); } // Deletion must be done synchronously by the JNI DestroyJavaVM thread // so that the VMThread deletion completes before the main thread frees // up the CodeHeap. } // Notify the VMThread that the last non-daemon JavaThread has terminated, // and wait until operation is performed. void VMThread::wait_for_vm_thread_exit() { { MutexLocker mu(VMOperationQueue_lock); _should_terminate = true; VMOperationQueue_lock->notify(); } // Note: VM thread leaves at Safepoint. We are not stopped by Safepoint // because this thread has been removed from the threads list. But anything // that could get blocked by Safepoint should not be used after this point, // otherwise we will hang, since there is no one can end the safepoint. // Wait until VM thread is terminated // Note: it should be OK to use Terminator_lock here. But this is called // at a very delicate time (VM shutdown) and we are operating in non- VM // thread at Safepoint. It's safer to not share lock with other threads. { MutexLockerEx ml(_terminate_lock, Mutex::_no_safepoint_check_flag); while(!VMThread::is_terminated()) { _terminate_lock->wait(Mutex::_no_safepoint_check_flag); } } } void VMThread::print_on(outputStream* st) const { st->print("\"%s\" ", name()); Thread::print_on(st); st->cr(); } void VMThread::evaluate_operation(VM_Operation* op) { ResourceMark rm; { PerfTraceTime vm_op_timer(perf_accumulated_vm_operation_time()); HS_DTRACE_PROBE3(hotspot, vmops__begin, op->name(), strlen(op->name()), op->evaluation_mode()); op->evaluate(); HS_DTRACE_PROBE3(hotspot, vmops__end, op->name(), strlen(op->name()), op->evaluation_mode()); } // Last access of info in _cur_vm_operation! bool c_heap_allocated = op->is_cheap_allocated(); // Mark as completed if (!op->evaluate_concurrently()) { op->calling_thread()->increment_vm_operation_completed_count(); } // It is unsafe to access the _cur_vm_operation after the 'increment_vm_operation_completed_count' call, // since if it is stack allocated the calling thread might have deallocated if (c_heap_allocated) { delete _cur_vm_operation; } } void VMThread::loop() { assert(_cur_vm_operation == NULL, "no current one should be executing"); while(true) { VM_Operation* safepoint_ops = NULL; // // Wait for VM operation // // use no_safepoint_check to get lock without attempting to "sneak" { MutexLockerEx mu_queue(VMOperationQueue_lock, Mutex::_no_safepoint_check_flag); // Look for new operation assert(_cur_vm_operation == NULL, "no current one should be executing"); _cur_vm_operation = _vm_queue->remove_next(); // Stall time tracking code if (PrintVMQWaitTime && _cur_vm_operation != NULL && !_cur_vm_operation->evaluate_concurrently()) { long stall = os::javaTimeMillis() - _cur_vm_operation->timestamp(); if (stall > 0) tty->print_cr("%s stall: %Ld", _cur_vm_operation->name(), stall); } while (!should_terminate() && _cur_vm_operation == NULL) { // wait with a timeout to guarantee safepoints at regular intervals bool timedout = VMOperationQueue_lock->wait(Mutex::_no_safepoint_check_flag, GuaranteedSafepointInterval); // Support for self destruction if ((SelfDestructTimer != 0) && !is_error_reported() && (os::elapsedTime() > SelfDestructTimer * 60)) { tty->print_cr("VM self-destructed"); exit(-1); } if (timedout && (SafepointALot || SafepointSynchronize::is_cleanup_needed())) { MutexUnlockerEx mul(VMOperationQueue_lock, Mutex::_no_safepoint_check_flag); // Force a safepoint since we have not had one for at least // 'GuaranteedSafepointInterval' milliseconds. This will run all // the clean-up processing that needs to be done regularly at a // safepoint SafepointSynchronize::begin(); #ifdef ASSERT if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot(); #endif SafepointSynchronize::end(); } _cur_vm_operation = _vm_queue->remove_next(); // If we are at a safepoint we will evaluate all the operations that // follow that also require a safepoint if (_cur_vm_operation != NULL && _cur_vm_operation->evaluate_at_safepoint()) { safepoint_ops = _vm_queue->drain_at_safepoint_priority(); } } if (should_terminate()) break; } // Release mu_queue_lock // // Execute VM operation // { HandleMark hm(VMThread::vm_thread()); EventMark em("Executing VM operation: %s", vm_operation()->name()); assert(_cur_vm_operation != NULL, "we should have found an operation to execute"); // Give the VM thread an extra quantum. Jobs tend to be bursty and this // helps the VM thread to finish up the job. // FIXME: When this is enabled and there are many threads, this can degrade // performance significantly. if( VMThreadHintNoPreempt ) os::hint_no_preempt(); // If we are at a safepoint we will evaluate all the operations that // follow that also require a safepoint if (_cur_vm_operation->evaluate_at_safepoint()) { _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned SafepointSynchronize::begin(); evaluate_operation(_cur_vm_operation); // now process all queued safepoint ops, iteratively draining // the queue until there are none left do { _cur_vm_operation = safepoint_ops; if (_cur_vm_operation != NULL) { do { // evaluate_operation deletes the op object so we have // to grab the next op now VM_Operation* next = _cur_vm_operation->next(); _vm_queue->set_drain_list(next); evaluate_operation(_cur_vm_operation); _cur_vm_operation = next; if (PrintSafepointStatistics) { SafepointSynchronize::inc_vmop_coalesced_count(); } } while (_cur_vm_operation != NULL); } // There is a chance that a thread enqueued a safepoint op // since we released the op-queue lock and initiated the safepoint. // So we drain the queue again if there is anything there, as an // optimization to try and reduce the number of safepoints. // As the safepoint synchronizes us with JavaThreads we will see // any enqueue made by a JavaThread, but the peek will not // necessarily detect a concurrent enqueue by a GC thread, but // that simply means the op will wait for the next major cycle of the // VMThread - just as it would if the GC thread lost the race for // the lock. if (_vm_queue->peek_at_safepoint_priority()) { // must hold lock while draining queue MutexLockerEx mu_queue(VMOperationQueue_lock, Mutex::_no_safepoint_check_flag); safepoint_ops = _vm_queue->drain_at_safepoint_priority(); } else { safepoint_ops = NULL; } } while(safepoint_ops != NULL); _vm_queue->set_drain_list(NULL); // Complete safepoint synchronization SafepointSynchronize::end(); } else { // not a safepoint operation if (TraceLongCompiles) { elapsedTimer t; t.start(); evaluate_operation(_cur_vm_operation); t.stop(); double secs = t.seconds(); if (secs * 1e3 > LongCompileThreshold) { // XXX - _cur_vm_operation should not be accessed after // the completed count has been incremented; the waiting // thread may have already freed this memory. tty->print_cr("vm %s: %3.7f secs]", _cur_vm_operation->name(), secs); } } else { evaluate_operation(_cur_vm_operation); } _cur_vm_operation = NULL; } } // // Notify (potential) waiting Java thread(s) - lock without safepoint // check so that sneaking is not possible { MutexLockerEx mu(VMOperationRequest_lock, Mutex::_no_safepoint_check_flag); VMOperationRequest_lock->notify_all(); } // // We want to make sure that we get to a safepoint regularly. // if (SafepointALot || SafepointSynchronize::is_cleanup_needed()) { long interval = SafepointSynchronize::last_non_safepoint_interval(); bool max_time_exceeded = GuaranteedSafepointInterval != 0 && (interval > GuaranteedSafepointInterval); if (SafepointALot || max_time_exceeded) { HandleMark hm(VMThread::vm_thread()); SafepointSynchronize::begin(); SafepointSynchronize::end(); } } } } void VMThread::execute(VM_Operation* op) { Thread* t = Thread::current(); if (!t->is_VM_thread()) { SkipGCALot sgcalot(t); // avoid re-entrant attempts to gc-a-lot // JavaThread or WatcherThread t->check_for_valid_safepoint_state(true); // New request from Java thread, evaluate prologue if (!op->doit_prologue()) { return; // op was cancelled } // Setup VM_operations for execution op->set_calling_thread(t, Thread::get_priority(t)); // It does not make sense to execute the epilogue, if the VM operation object is getting // deallocated by the VM thread. bool concurrent = op->evaluate_concurrently(); bool execute_epilog = !op->is_cheap_allocated(); assert(!concurrent || op->is_cheap_allocated(), "concurrent => cheap_allocated"); // Get ticket number for non-concurrent VM operations int ticket = 0; if (!concurrent) { ticket = t->vm_operation_ticket(); } // Add VM operation to list of waiting threads. We are guaranteed not to block while holding the // VMOperationQueue_lock, so we can block without a safepoint check. This allows vm operation requests // to be queued up during a safepoint synchronization. { VMOperationQueue_lock->lock_without_safepoint_check(); bool ok = _vm_queue->add(op); op->set_timestamp(os::javaTimeMillis()); VMOperationQueue_lock->notify(); VMOperationQueue_lock->unlock(); // VM_Operation got skipped if (!ok) { assert(concurrent, "can only skip concurrent tasks"); if (op->is_cheap_allocated()) delete op; return; } } if (!concurrent) { // Wait for completion of request (non-concurrent) // Note: only a JavaThread triggers the safepoint check when locking MutexLocker mu(VMOperationRequest_lock); while(t->vm_operation_completed_count() < ticket) { VMOperationRequest_lock->wait(!t->is_Java_thread()); } } if (execute_epilog) { op->doit_epilogue(); } } else { // invoked by VM thread; usually nested VM operation assert(t->is_VM_thread(), "must be a VM thread"); VM_Operation* prev_vm_operation = vm_operation(); if (prev_vm_operation != NULL) { // Check the VM operation allows nested VM operation. This normally not the case, e.g., the compiler // does not allow nested scavenges or compiles. if (!prev_vm_operation->allow_nested_vm_operations()) { fatal2("Nested VM operation %s requested by operation %s", op->name(), vm_operation()->name()); } op->set_calling_thread(prev_vm_operation->calling_thread(), prev_vm_operation->priority()); } EventMark em("Executing %s VM operation: %s", prev_vm_operation ? "nested" : "", op->name()); // Release all internal handles after operation is evaluated HandleMark hm(t); _cur_vm_operation = op; if (op->evaluate_at_safepoint() && !SafepointSynchronize::is_at_safepoint()) { SafepointSynchronize::begin(); op->evaluate(); SafepointSynchronize::end(); } else { op->evaluate(); } // Free memory if needed if (op->is_cheap_allocated()) delete op; _cur_vm_operation = prev_vm_operation; } } void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { Thread::oops_do(f, cf); _vm_queue->oops_do(f); } //------------------------------------------------------------------------------------------------------------------ #ifndef PRODUCT void VMOperationQueue::verify_queue(int prio) { // Check that list is correctly linked int length = _queue_length[prio]; VM_Operation *cur = _queue[prio]; int i; // Check forward links for(i = 0; i < length; i++) { cur = cur->next(); assert(cur != _queue[prio], "list to short (forward)"); } assert(cur->next() == _queue[prio], "list to long (forward)"); // Check backwards links cur = _queue[prio]; for(i = 0; i < length; i++) { cur = cur->prev(); assert(cur != _queue[prio], "list to short (backwards)"); } assert(cur->prev() == _queue[prio], "list to long (backwards)"); } #endif void VMThread::verify() { oops_do(&VerifyOopClosure::verify_oop, NULL); }