truffle: src/share/vm/runtime/vmThread.cpp comparison

comparison src/share/vm/runtime/vmThread.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	821269eca479

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+:a61af66fc99e
+/*
+* Copyright 1998-2007 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"
+// 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) {
+// 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() : Thread() {
+// nothing to do
+}
+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());
+op->evaluate();
+}
+// 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()) {
+if (PrintGCApplicationConcurrentTime) {
+gclog_or_tty->print_cr("Application time: %3.7f seconds",
+RuntimeService::last_application_time_sec());
+}
+_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();
+if (PrintGCApplicationStoppedTime) {
+gclog_or_tty->print_cr("Total time for which application threads "
+"were stopped: %3.7f seconds",
+RuntimeService::last_safepoint_time_sec());
+}
+} 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()) {
+// 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) {
+Thread::oops_do(f);
+_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);
+}

Mercurial > hg > truffle

comparison src/share/vm/runtime/vmThread.cpp @ 0:a61af66fc99e jdk7-b24