1153 lines
39 KiB
Java
1153 lines
39 KiB
Java
/*
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* Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang;
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import java.lang.ref.Reference;
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import java.security.AccessController;
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import java.security.PrivilegedAction;
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import java.util.Locale;
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import java.util.Objects;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.Executor;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ForkJoinPool;
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import java.util.concurrent.ForkJoinPool.ForkJoinWorkerThreadFactory;
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import java.util.concurrent.ForkJoinTask;
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import java.util.concurrent.ForkJoinWorkerThread;
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import java.util.concurrent.Future;
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import java.util.concurrent.RejectedExecutionException;
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import java.util.concurrent.ScheduledExecutorService;
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import java.util.concurrent.ScheduledThreadPoolExecutor;
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import jdk.internal.event.ThreadSleepEvent;
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import jdk.internal.event.VirtualThreadEndEvent;
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import jdk.internal.event.VirtualThreadPinnedEvent;
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import jdk.internal.event.VirtualThreadStartEvent;
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import jdk.internal.event.VirtualThreadSubmitFailedEvent;
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import jdk.internal.misc.CarrierThread;
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import jdk.internal.misc.InnocuousThread;
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import jdk.internal.misc.Unsafe;
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import jdk.internal.vm.Continuation;
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import jdk.internal.vm.ContinuationScope;
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import jdk.internal.vm.StackableScope;
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import jdk.internal.vm.ThreadContainer;
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import jdk.internal.vm.ThreadContainers;
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import jdk.internal.vm.annotation.ChangesCurrentThread;
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import jdk.internal.vm.annotation.ForceInline;
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import jdk.internal.vm.annotation.Hidden;
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import jdk.internal.vm.annotation.JvmtiMountTransition;
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import sun.nio.ch.Interruptible;
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import sun.security.action.GetPropertyAction;
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import static java.util.concurrent.TimeUnit.*;
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/**
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* A thread that is scheduled by the Java virtual machine rather than the operating
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* system.
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*/
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final class VirtualThread extends BaseVirtualThread {
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private static final Unsafe U = Unsafe.getUnsafe();
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private static final ContinuationScope VTHREAD_SCOPE = new ContinuationScope("VirtualThreads");
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private static final ForkJoinPool DEFAULT_SCHEDULER = createDefaultScheduler();
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private static final ScheduledExecutorService UNPARKER = createDelayedTaskScheduler();
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private static final int TRACE_PINNING_MODE = tracePinningMode();
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private static final long STATE = U.objectFieldOffset(VirtualThread.class, "state");
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private static final long PARK_PERMIT = U.objectFieldOffset(VirtualThread.class, "parkPermit");
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private static final long CARRIER_THREAD = U.objectFieldOffset(VirtualThread.class, "carrierThread");
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private static final long TERMINATION = U.objectFieldOffset(VirtualThread.class, "termination");
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// scheduler and continuation
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private final Executor scheduler;
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private final Continuation cont;
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private final Runnable runContinuation;
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// virtual thread state, accessed by VM
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private volatile int state;
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/*
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* Virtual thread state and transitions:
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*
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* NEW -> STARTED // Thread.start
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* STARTED -> TERMINATED // failed to start
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* STARTED -> RUNNING // first run
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*
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* RUNNING -> PARKING // Thread attempts to park
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* PARKING -> PARKED // cont.yield successful, thread is parked
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* PARKING -> PINNED // cont.yield failed, thread is pinned
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*
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* PARKED -> RUNNABLE // unpark or interrupted
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* PINNED -> RUNNABLE // unpark or interrupted
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*
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* RUNNABLE -> RUNNING // continue execution
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*
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* RUNNING -> YIELDING // Thread.yield
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* YIELDING -> RUNNABLE // yield successful
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* YIELDING -> RUNNING // yield failed
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*
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* RUNNING -> TERMINATED // done
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*/
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private static final int NEW = 0;
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private static final int STARTED = 1;
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private static final int RUNNABLE = 2; // runnable-unmounted
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private static final int RUNNING = 3; // runnable-mounted
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private static final int PARKING = 4;
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private static final int PARKED = 5; // unmounted
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private static final int PINNED = 6; // mounted
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private static final int YIELDING = 7; // Thread.yield
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private static final int TERMINATED = 99; // final state
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// can be suspended from scheduling when unmounted
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private static final int SUSPENDED = 1 << 8;
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private static final int RUNNABLE_SUSPENDED = (RUNNABLE | SUSPENDED);
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private static final int PARKED_SUSPENDED = (PARKED | SUSPENDED);
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// parking permit
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private volatile boolean parkPermit;
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// carrier thread when mounted, accessed by VM
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private volatile Thread carrierThread;
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// termination object when joining, created lazily if needed
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private volatile CountDownLatch termination;
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/**
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* Returns the continuation scope used for virtual threads.
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*/
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static ContinuationScope continuationScope() {
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return VTHREAD_SCOPE;
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}
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/**
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* Creates a new {@code VirtualThread} to run the given task with the given
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* scheduler. If the given scheduler is {@code null} and the current thread
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* is a platform thread then the newly created virtual thread will use the
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* default scheduler. If given scheduler is {@code null} and the current
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* thread is a virtual thread then the current thread's scheduler is used.
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*
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* @param scheduler the scheduler or null
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* @param name thread name
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* @param characteristics characteristics
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* @param task the task to execute
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*/
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VirtualThread(Executor scheduler, String name, int characteristics, Runnable task) {
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super(name, characteristics, /*bound*/ false);
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Objects.requireNonNull(task);
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// choose scheduler if not specified
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if (scheduler == null) {
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Thread parent = Thread.currentThread();
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if (parent instanceof VirtualThread vparent) {
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scheduler = vparent.scheduler;
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} else {
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scheduler = DEFAULT_SCHEDULER;
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}
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}
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this.scheduler = scheduler;
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this.cont = new VThreadContinuation(this, task);
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this.runContinuation = this::runContinuation;
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}
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/**
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* The continuation that a virtual thread executes.
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*/
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private static class VThreadContinuation extends Continuation {
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VThreadContinuation(VirtualThread vthread, Runnable task) {
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super(VTHREAD_SCOPE, () -> vthread.run(task));
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}
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@Override
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protected void onPinned(Continuation.Pinned reason) {
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if (TRACE_PINNING_MODE > 0) {
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boolean printAll = (TRACE_PINNING_MODE == 1);
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PinnedThreadPrinter.printStackTrace(System.out, printAll);
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}
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}
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}
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/**
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* Runs or continues execution of the continuation on the current thread.
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*/
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private void runContinuation() {
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// the carrier must be a platform thread
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if (Thread.currentThread().isVirtual()) {
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throw new WrongThreadException();
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}
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// set state to RUNNING
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boolean firstRun;
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int initialState = state();
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if (initialState == STARTED && compareAndSetState(STARTED, RUNNING)) {
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// first run
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firstRun = true;
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} else if (initialState == RUNNABLE && compareAndSetState(RUNNABLE, RUNNING)) {
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// consume parking permit
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setParkPermit(false);
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firstRun = false;
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} else {
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// not runnable
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return;
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}
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// notify JVMTI before mount
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if (notifyJvmtiEvents) notifyJvmtiMountBegin(firstRun);
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try {
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cont.run();
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} finally {
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if (cont.isDone()) {
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afterTerminate(/*executed*/ true);
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} else {
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afterYield();
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}
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}
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}
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/**
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* Submits the runContinuation task to the scheduler. For the default scheduler,
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* and calling it on a worker thread, the task will be pushed to the local queue,
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* otherwise it will be pushed to a submission queue.
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*
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* @throws RejectedExecutionException
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*/
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private void submitRunContinuation() {
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try {
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scheduler.execute(runContinuation);
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} catch (RejectedExecutionException ree) {
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submitFailed(ree);
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throw ree;
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}
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}
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/**
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* Submits the runContinuation task to the scheduler with a lazy submit.
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* @throws RejectedExecutionException
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* @see ForkJoinPool#lazySubmit(ForkJoinTask)
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*/
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private void lazySubmitRunContinuation(ForkJoinPool pool) {
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try {
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pool.lazySubmit(ForkJoinTask.adapt(runContinuation));
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} catch (RejectedExecutionException ree) {
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submitFailed(ree);
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throw ree;
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}
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}
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/**
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* Submits the runContinuation task to the scheduler as an external submit.
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* @throws RejectedExecutionException
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* @see ForkJoinPool#externalSubmit(ForkJoinTask)
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*/
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private void externalSubmitRunContinuation(ForkJoinPool pool) {
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try {
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pool.externalSubmit(ForkJoinTask.adapt(runContinuation));
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} catch (RejectedExecutionException ree) {
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submitFailed(ree);
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throw ree;
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}
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}
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/**
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* If enabled, emits a JFR VirtualThreadSubmitFailedEvent.
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*/
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private void submitFailed(RejectedExecutionException ree) {
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var event = new VirtualThreadSubmitFailedEvent();
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if (event.isEnabled()) {
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event.javaThreadId = threadId();
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event.exceptionMessage = ree.getMessage();
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event.commit();
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}
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}
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/**
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* Runs a task in the context of this virtual thread. The virtual thread is
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* mounted on the current (carrier) thread before the task runs. It unmounts
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* from its carrier thread when the task completes.
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*/
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@ChangesCurrentThread
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private void run(Runnable task) {
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assert state == RUNNING;
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boolean notifyJvmti = notifyJvmtiEvents;
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// first mount
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mount();
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if (notifyJvmti) notifyJvmtiMountEnd(true);
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// emit JFR event if enabled
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if (VirtualThreadStartEvent.isTurnedOn()) {
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var event = new VirtualThreadStartEvent();
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event.javaThreadId = threadId();
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event.commit();
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}
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Object bindings = scopedValueBindings();
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try {
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runWith(bindings, task);
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} catch (Throwable exc) {
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dispatchUncaughtException(exc);
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} finally {
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try {
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// pop any remaining scopes from the stack, this may block
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StackableScope.popAll();
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// emit JFR event if enabled
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if (VirtualThreadEndEvent.isTurnedOn()) {
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var event = new VirtualThreadEndEvent();
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event.javaThreadId = threadId();
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event.commit();
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}
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} finally {
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// last unmount
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if (notifyJvmti) notifyJvmtiUnmountBegin(true);
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unmount();
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// final state
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setState(TERMINATED);
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}
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}
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}
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@Hidden
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@ForceInline
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private void runWith(Object bindings, Runnable op) {
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ensureMaterializedForStackWalk(bindings);
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op.run();
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Reference.reachabilityFence(bindings);
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}
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/**
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* Mounts this virtual thread onto the current platform thread. On
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* return, the current thread is the virtual thread.
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*/
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@ChangesCurrentThread
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private void mount() {
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// sets the carrier thread
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Thread carrier = Thread.currentCarrierThread();
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setCarrierThread(carrier);
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// sync up carrier thread interrupt status if needed
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if (interrupted) {
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carrier.setInterrupt();
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} else if (carrier.isInterrupted()) {
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synchronized (interruptLock) {
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// need to recheck interrupt status
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if (!interrupted) {
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carrier.clearInterrupt();
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}
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}
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}
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// set Thread.currentThread() to return this virtual thread
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carrier.setCurrentThread(this);
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}
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/**
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* Unmounts this virtual thread from the carrier. On return, the
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* current thread is the current platform thread.
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*/
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@ChangesCurrentThread
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private void unmount() {
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// set Thread.currentThread() to return the platform thread
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Thread carrier = this.carrierThread;
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carrier.setCurrentThread(carrier);
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// break connection to carrier thread, synchronized with interrupt
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synchronized (interruptLock) {
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setCarrierThread(null);
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}
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carrier.clearInterrupt();
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}
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/**
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* Sets the current thread to the current carrier thread.
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* @return true if JVMTI was notified
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*/
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@ChangesCurrentThread
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@JvmtiMountTransition
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private boolean switchToCarrierThread() {
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boolean notifyJvmti = notifyJvmtiEvents;
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if (notifyJvmti) {
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notifyJvmtiHideFrames(true);
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}
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Thread carrier = this.carrierThread;
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assert Thread.currentThread() == this
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&& carrier == Thread.currentCarrierThread();
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carrier.setCurrentThread(carrier);
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return notifyJvmti;
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}
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/**
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* Sets the current thread to the given virtual thread.
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* If {@code notifyJvmti} is true then JVMTI is notified.
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*/
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@ChangesCurrentThread
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@JvmtiMountTransition
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private void switchToVirtualThread(VirtualThread vthread, boolean notifyJvmti) {
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Thread carrier = vthread.carrierThread;
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assert carrier == Thread.currentCarrierThread();
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carrier.setCurrentThread(vthread);
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if (notifyJvmti) {
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notifyJvmtiHideFrames(false);
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}
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}
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/**
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* Unmounts this virtual thread, invokes Continuation.yield, and re-mounts the
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* thread when continued. When enabled, JVMTI must be notified from this method.
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* @return true if the yield was successful
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*/
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@ChangesCurrentThread
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private boolean yieldContinuation() {
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boolean notifyJvmti = notifyJvmtiEvents;
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// unmount
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if (notifyJvmti) notifyJvmtiUnmountBegin(false);
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unmount();
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try {
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return Continuation.yield(VTHREAD_SCOPE);
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} finally {
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// re-mount
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mount();
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if (notifyJvmti) notifyJvmtiMountEnd(false);
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}
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}
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/**
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* Invoked after the continuation yields. If parking then it sets the state
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* and also re-submits the task to continue if unparked while parking.
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* If yielding due to Thread.yield then it just submits the task to continue.
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*/
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private void afterYield() {
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int s = state();
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assert (s == PARKING || s == YIELDING) && (carrierThread == null);
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if (s == PARKING) {
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setState(PARKED);
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// notify JVMTI that unmount has completed, thread is parked
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if (notifyJvmtiEvents) notifyJvmtiUnmountEnd(false);
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// may have been unparked while parking
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if (parkPermit && compareAndSetState(PARKED, RUNNABLE)) {
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// lazy submit to continue on the current thread as carrier if possible
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if (currentThread() instanceof CarrierThread ct) {
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lazySubmitRunContinuation(ct.getPool());
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} else {
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submitRunContinuation();
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}
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}
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} else if (s == YIELDING) { // Thread.yield
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setState(RUNNABLE);
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// notify JVMTI that unmount has completed, thread is runnable
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if (notifyJvmtiEvents) notifyJvmtiUnmountEnd(false);
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// external submit if there are no tasks in the local task queue
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if (currentThread() instanceof CarrierThread ct && ct.getQueuedTaskCount() == 0) {
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externalSubmitRunContinuation(ct.getPool());
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} else {
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submitRunContinuation();
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}
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}
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}
|
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|
|
/**
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|
* Invoked after the thread terminates (or start failed). This method
|
|
* notifies anyone waiting for the thread to terminate.
|
|
*
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* @param executed true if the thread executed, false if it failed to start
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*/
|
|
private void afterTerminate(boolean executed) {
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assert (state() == TERMINATED) && (carrierThread == null);
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|
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if (executed) {
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if (notifyJvmtiEvents) notifyJvmtiUnmountEnd(true);
|
|
}
|
|
|
|
// notify anyone waiting for this virtual thread to terminate
|
|
CountDownLatch termination = this.termination;
|
|
if (termination != null) {
|
|
assert termination.getCount() == 1;
|
|
termination.countDown();
|
|
}
|
|
|
|
if (executed) {
|
|
// notify container if thread executed
|
|
threadContainer().onExit(this);
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|
|
|
// clear references to thread locals
|
|
clearReferences();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Schedules this {@code VirtualThread} to execute.
|
|
*
|
|
* @throws IllegalStateException if the container is shutdown or closed
|
|
* @throws IllegalThreadStateException if the thread has already been started
|
|
* @throws RejectedExecutionException if the scheduler cannot accept a task
|
|
*/
|
|
@Override
|
|
void start(ThreadContainer container) {
|
|
if (!compareAndSetState(NEW, STARTED)) {
|
|
throw new IllegalThreadStateException("Already started");
|
|
}
|
|
|
|
// bind thread to container
|
|
setThreadContainer(container);
|
|
|
|
// start thread
|
|
boolean started = false;
|
|
container.onStart(this); // may throw
|
|
try {
|
|
// scoped values may be inherited
|
|
inheritScopedValueBindings(container);
|
|
|
|
// submit task to run thread
|
|
submitRunContinuation();
|
|
started = true;
|
|
} finally {
|
|
if (!started) {
|
|
setState(TERMINATED);
|
|
container.onExit(this);
|
|
afterTerminate(/*executed*/ false);
|
|
}
|
|
}
|
|
}
|
|
|
|
@Override
|
|
public void start() {
|
|
start(ThreadContainers.root());
|
|
}
|
|
|
|
@Override
|
|
public void run() {
|
|
// do nothing
|
|
}
|
|
|
|
/**
|
|
* Parks until unparked or interrupted. If already unparked then the parking
|
|
* permit is consumed and this method completes immediately (meaning it doesn't
|
|
* yield). It also completes immediately if the interrupt status is set.
|
|
*/
|
|
@Override
|
|
void park() {
|
|
assert Thread.currentThread() == this;
|
|
|
|
// complete immediately if parking permit available or interrupted
|
|
if (getAndSetParkPermit(false) || interrupted)
|
|
return;
|
|
|
|
// park the thread
|
|
setState(PARKING);
|
|
try {
|
|
if (!yieldContinuation()) {
|
|
// park on the carrier thread when pinned
|
|
parkOnCarrierThread(false, 0);
|
|
}
|
|
} finally {
|
|
assert (Thread.currentThread() == this) && (state() == RUNNING);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Parks up to the given waiting time or until unparked or interrupted.
|
|
* If already unparked then the parking permit is consumed and this method
|
|
* completes immediately (meaning it doesn't yield). It also completes immediately
|
|
* if the interrupt status is set or the waiting time is {@code <= 0}.
|
|
*
|
|
* @param nanos the maximum number of nanoseconds to wait.
|
|
*/
|
|
@Override
|
|
void parkNanos(long nanos) {
|
|
assert Thread.currentThread() == this;
|
|
|
|
// complete immediately if parking permit available or interrupted
|
|
if (getAndSetParkPermit(false) || interrupted)
|
|
return;
|
|
|
|
// park the thread for the waiting time
|
|
if (nanos > 0) {
|
|
long startTime = System.nanoTime();
|
|
|
|
boolean yielded;
|
|
Future<?> unparker = scheduleUnpark(this::unpark, nanos);
|
|
setState(PARKING);
|
|
try {
|
|
yielded = yieldContinuation();
|
|
} finally {
|
|
assert (Thread.currentThread() == this)
|
|
&& (state() == RUNNING || state() == PARKING);
|
|
cancel(unparker);
|
|
}
|
|
|
|
// park on carrier thread for remaining time when pinned
|
|
if (!yielded) {
|
|
long deadline = startTime + nanos;
|
|
if (deadline < 0L)
|
|
deadline = Long.MAX_VALUE;
|
|
parkOnCarrierThread(true, deadline - System.nanoTime());
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Parks the current carrier thread up to the given waiting time or until
|
|
* unparked or interrupted. If the virtual thread is interrupted then the
|
|
* interrupt status will be propagated to the carrier thread.
|
|
* @param timed true for a timed park, false for untimed
|
|
* @param nanos the waiting time in nanoseconds
|
|
*/
|
|
private void parkOnCarrierThread(boolean timed, long nanos) {
|
|
assert state() == PARKING;
|
|
|
|
var pinnedEvent = new VirtualThreadPinnedEvent();
|
|
pinnedEvent.begin();
|
|
|
|
setState(PINNED);
|
|
try {
|
|
if (!parkPermit) {
|
|
if (!timed) {
|
|
U.park(false, 0);
|
|
} else if (nanos > 0) {
|
|
U.park(false, nanos);
|
|
}
|
|
}
|
|
} finally {
|
|
setState(RUNNING);
|
|
}
|
|
|
|
// consume parking permit
|
|
setParkPermit(false);
|
|
|
|
pinnedEvent.commit();
|
|
}
|
|
|
|
/**
|
|
* Schedule an unpark task to run after a given delay.
|
|
*/
|
|
@ChangesCurrentThread
|
|
private Future<?> scheduleUnpark(Runnable unparker, long nanos) {
|
|
// need to switch to current carrier thread to avoid nested parking
|
|
boolean notifyJvmti = switchToCarrierThread();
|
|
try {
|
|
return UNPARKER.schedule(unparker, nanos, NANOSECONDS);
|
|
} finally {
|
|
switchToVirtualThread(this, notifyJvmti);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Cancels a task if it has not completed.
|
|
*/
|
|
@ChangesCurrentThread
|
|
private void cancel(Future<?> future) {
|
|
if (!future.isDone()) {
|
|
// need to switch to current carrier thread to avoid nested parking
|
|
boolean notifyJvmti = switchToCarrierThread();
|
|
try {
|
|
future.cancel(false);
|
|
} finally {
|
|
switchToVirtualThread(this, notifyJvmti);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Re-enables this virtual thread for scheduling. If the virtual thread was
|
|
* {@link #park() parked} then it will be unblocked, otherwise its next call
|
|
* to {@code park} or {@linkplain #parkNanos(long) parkNanos} is guaranteed
|
|
* not to block.
|
|
* @throws RejectedExecutionException if the scheduler cannot accept a task
|
|
*/
|
|
@Override
|
|
@ChangesCurrentThread
|
|
void unpark() {
|
|
Thread currentThread = Thread.currentThread();
|
|
if (!getAndSetParkPermit(true) && currentThread != this) {
|
|
int s = state();
|
|
if (s == PARKED && compareAndSetState(PARKED, RUNNABLE)) {
|
|
if (currentThread instanceof VirtualThread vthread) {
|
|
boolean notifyJvmti = vthread.switchToCarrierThread();
|
|
try {
|
|
submitRunContinuation();
|
|
} finally {
|
|
switchToVirtualThread(vthread, notifyJvmti);
|
|
}
|
|
} else {
|
|
submitRunContinuation();
|
|
}
|
|
} else if (s == PINNED) {
|
|
// unpark carrier thread when pinned.
|
|
synchronized (carrierThreadAccessLock()) {
|
|
Thread carrier = carrierThread;
|
|
if (carrier != null && state() == PINNED) {
|
|
U.unpark(carrier);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Attempts to yield the current virtual thread (Thread.yield).
|
|
*/
|
|
void tryYield() {
|
|
assert Thread.currentThread() == this;
|
|
setState(YIELDING);
|
|
try {
|
|
yieldContinuation();
|
|
} finally {
|
|
assert Thread.currentThread() == this;
|
|
if (state() != RUNNING) {
|
|
assert state() == YIELDING;
|
|
setState(RUNNING);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Sleep the current virtual thread for the given sleep time.
|
|
*
|
|
* @param nanos the maximum number of nanoseconds to sleep
|
|
* @throws InterruptedException if interrupted while sleeping
|
|
*/
|
|
void sleepNanos(long nanos) throws InterruptedException {
|
|
assert Thread.currentThread() == this;
|
|
if (nanos >= 0) {
|
|
if (ThreadSleepEvent.isTurnedOn()) {
|
|
ThreadSleepEvent event = new ThreadSleepEvent();
|
|
try {
|
|
event.time = nanos;
|
|
event.begin();
|
|
doSleepNanos(nanos);
|
|
} finally {
|
|
event.commit();
|
|
}
|
|
} else {
|
|
doSleepNanos(nanos);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Sleep the current thread for the given sleep time (in nanoseconds). If
|
|
* nanos is 0 then the thread will attempt to yield.
|
|
*
|
|
* @implNote This implementation parks the thread for the given sleeping time
|
|
* and will therefore be observed in PARKED state during the sleep. Parking
|
|
* will consume the parking permit so this method makes available the parking
|
|
* permit after the sleep. This may be observed as a spurious, but benign,
|
|
* wakeup when the thread subsequently attempts to park.
|
|
*/
|
|
private void doSleepNanos(long nanos) throws InterruptedException {
|
|
assert nanos >= 0;
|
|
if (getAndClearInterrupt())
|
|
throw new InterruptedException();
|
|
if (nanos == 0) {
|
|
tryYield();
|
|
} else {
|
|
// park for the sleep time
|
|
try {
|
|
long remainingNanos = nanos;
|
|
long startNanos = System.nanoTime();
|
|
while (remainingNanos > 0) {
|
|
parkNanos(remainingNanos);
|
|
if (getAndClearInterrupt()) {
|
|
throw new InterruptedException();
|
|
}
|
|
remainingNanos = nanos - (System.nanoTime() - startNanos);
|
|
}
|
|
} finally {
|
|
// may have been unparked while sleeping
|
|
setParkPermit(true);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Waits up to {@code nanos} nanoseconds for this virtual thread to terminate.
|
|
* A timeout of {@code 0} means to wait forever.
|
|
*
|
|
* @throws InterruptedException if interrupted while waiting
|
|
* @return true if the thread has terminated
|
|
*/
|
|
boolean joinNanos(long nanos) throws InterruptedException {
|
|
if (state() == TERMINATED)
|
|
return true;
|
|
|
|
// ensure termination object exists, then re-check state
|
|
CountDownLatch termination = getTermination();
|
|
if (state() == TERMINATED)
|
|
return true;
|
|
|
|
// wait for virtual thread to terminate
|
|
if (nanos == 0) {
|
|
termination.await();
|
|
} else {
|
|
boolean terminated = termination.await(nanos, NANOSECONDS);
|
|
if (!terminated) {
|
|
// waiting time elapsed
|
|
return false;
|
|
}
|
|
}
|
|
assert state() == TERMINATED;
|
|
return true;
|
|
}
|
|
|
|
@Override
|
|
@SuppressWarnings("removal")
|
|
public void interrupt() {
|
|
if (Thread.currentThread() != this) {
|
|
checkAccess();
|
|
synchronized (interruptLock) {
|
|
interrupted = true;
|
|
Interruptible b = nioBlocker;
|
|
if (b != null) {
|
|
b.interrupt(this);
|
|
}
|
|
|
|
// interrupt carrier thread if mounted
|
|
Thread carrier = carrierThread;
|
|
if (carrier != null) carrier.setInterrupt();
|
|
}
|
|
} else {
|
|
interrupted = true;
|
|
carrierThread.setInterrupt();
|
|
}
|
|
unpark();
|
|
}
|
|
|
|
@Override
|
|
public boolean isInterrupted() {
|
|
return interrupted;
|
|
}
|
|
|
|
@Override
|
|
boolean getAndClearInterrupt() {
|
|
assert Thread.currentThread() == this;
|
|
synchronized (interruptLock) {
|
|
boolean oldValue = interrupted;
|
|
if (oldValue)
|
|
interrupted = false;
|
|
carrierThread.clearInterrupt();
|
|
return oldValue;
|
|
}
|
|
}
|
|
|
|
@Override
|
|
Thread.State threadState() {
|
|
switch (state()) {
|
|
case NEW:
|
|
return Thread.State.NEW;
|
|
case STARTED:
|
|
// return NEW if thread container not yet set
|
|
if (threadContainer() == null) {
|
|
return Thread.State.NEW;
|
|
} else {
|
|
return Thread.State.RUNNABLE;
|
|
}
|
|
case RUNNABLE:
|
|
case RUNNABLE_SUSPENDED:
|
|
// runnable, not mounted
|
|
return Thread.State.RUNNABLE;
|
|
case RUNNING:
|
|
// if mounted then return state of carrier thread
|
|
synchronized (carrierThreadAccessLock()) {
|
|
Thread carrierThread = this.carrierThread;
|
|
if (carrierThread != null) {
|
|
return carrierThread.threadState();
|
|
}
|
|
}
|
|
// runnable, mounted
|
|
return Thread.State.RUNNABLE;
|
|
case PARKING:
|
|
case YIELDING:
|
|
// runnable, mounted, not yet waiting
|
|
return Thread.State.RUNNABLE;
|
|
case PARKED:
|
|
case PARKED_SUSPENDED:
|
|
case PINNED:
|
|
return Thread.State.WAITING;
|
|
case TERMINATED:
|
|
return Thread.State.TERMINATED;
|
|
default:
|
|
throw new InternalError();
|
|
}
|
|
}
|
|
|
|
@Override
|
|
boolean alive() {
|
|
int s = state;
|
|
return (s != NEW && s != TERMINATED);
|
|
}
|
|
|
|
@Override
|
|
boolean isTerminated() {
|
|
return (state == TERMINATED);
|
|
}
|
|
|
|
@Override
|
|
StackTraceElement[] asyncGetStackTrace() {
|
|
StackTraceElement[] stackTrace;
|
|
do {
|
|
stackTrace = (carrierThread != null)
|
|
? super.asyncGetStackTrace() // mounted
|
|
: tryGetStackTrace(); // unmounted
|
|
if (stackTrace == null) {
|
|
Thread.yield();
|
|
}
|
|
} while (stackTrace == null);
|
|
return stackTrace;
|
|
}
|
|
|
|
/**
|
|
* Returns the stack trace for this virtual thread if it is unmounted.
|
|
* Returns null if the thread is in another state.
|
|
*/
|
|
private StackTraceElement[] tryGetStackTrace() {
|
|
int initialState = state();
|
|
return switch (initialState) {
|
|
case RUNNABLE, PARKED -> {
|
|
int suspendedState = initialState | SUSPENDED;
|
|
if (compareAndSetState(initialState, suspendedState)) {
|
|
try {
|
|
yield cont.getStackTrace();
|
|
} finally {
|
|
assert state == suspendedState;
|
|
setState(initialState);
|
|
|
|
// re-submit if runnable
|
|
// re-submit if unparked while suspended
|
|
if (initialState == RUNNABLE
|
|
|| (parkPermit && compareAndSetState(PARKED, RUNNABLE))) {
|
|
try {
|
|
submitRunContinuation();
|
|
} catch (RejectedExecutionException ignore) { }
|
|
}
|
|
}
|
|
}
|
|
yield null;
|
|
}
|
|
case NEW, STARTED, TERMINATED -> new StackTraceElement[0]; // empty stack
|
|
default -> null;
|
|
};
|
|
}
|
|
|
|
@Override
|
|
public String toString() {
|
|
StringBuilder sb = new StringBuilder("VirtualThread[#");
|
|
sb.append(threadId());
|
|
String name = getName();
|
|
if (!name.isEmpty()) {
|
|
sb.append(",");
|
|
sb.append(name);
|
|
}
|
|
sb.append("]/");
|
|
Thread carrier = carrierThread;
|
|
if (carrier != null) {
|
|
// include the carrier thread state and name when mounted
|
|
synchronized (carrierThreadAccessLock()) {
|
|
carrier = carrierThread;
|
|
if (carrier != null) {
|
|
String stateAsString = carrier.threadState().toString();
|
|
sb.append(stateAsString.toLowerCase(Locale.ROOT));
|
|
sb.append('@');
|
|
sb.append(carrier.getName());
|
|
}
|
|
}
|
|
}
|
|
// include virtual thread state when not mounted
|
|
if (carrier == null) {
|
|
String stateAsString = threadState().toString();
|
|
sb.append(stateAsString.toLowerCase(Locale.ROOT));
|
|
}
|
|
return sb.toString();
|
|
}
|
|
|
|
@Override
|
|
public int hashCode() {
|
|
return (int) threadId();
|
|
}
|
|
|
|
@Override
|
|
public boolean equals(Object obj) {
|
|
return obj == this;
|
|
}
|
|
|
|
/**
|
|
* Returns the termination object, creating it if needed.
|
|
*/
|
|
private CountDownLatch getTermination() {
|
|
CountDownLatch termination = this.termination;
|
|
if (termination == null) {
|
|
termination = new CountDownLatch(1);
|
|
if (!U.compareAndSetReference(this, TERMINATION, null, termination)) {
|
|
termination = this.termination;
|
|
}
|
|
}
|
|
return termination;
|
|
}
|
|
|
|
/**
|
|
* Returns the lock object to synchronize on when accessing carrierThread.
|
|
* The lock prevents carrierThread from being reset to null during unmount.
|
|
*/
|
|
private Object carrierThreadAccessLock() {
|
|
// return interruptLock as unmount has to coordinate with interrupt
|
|
return interruptLock;
|
|
}
|
|
|
|
// -- wrappers for get/set of state, parking permit, and carrier thread --
|
|
|
|
private int state() {
|
|
return state; // volatile read
|
|
}
|
|
|
|
private void setState(int newValue) {
|
|
state = newValue; // volatile write
|
|
}
|
|
|
|
private boolean compareAndSetState(int expectedValue, int newValue) {
|
|
return U.compareAndSetInt(this, STATE, expectedValue, newValue);
|
|
}
|
|
|
|
private void setParkPermit(boolean newValue) {
|
|
if (parkPermit != newValue) {
|
|
parkPermit = newValue;
|
|
}
|
|
}
|
|
|
|
private boolean getAndSetParkPermit(boolean newValue) {
|
|
if (parkPermit != newValue) {
|
|
return U.getAndSetBoolean(this, PARK_PERMIT, newValue);
|
|
} else {
|
|
return newValue;
|
|
}
|
|
}
|
|
|
|
private void setCarrierThread(Thread carrier) {
|
|
// U.putReferenceRelease(this, CARRIER_THREAD, carrier);
|
|
this.carrierThread = carrier;
|
|
}
|
|
|
|
// -- JVM TI support --
|
|
|
|
private static volatile boolean notifyJvmtiEvents; // set by VM
|
|
|
|
@JvmtiMountTransition
|
|
private native void notifyJvmtiMountBegin(boolean firstMount);
|
|
|
|
@JvmtiMountTransition
|
|
private native void notifyJvmtiMountEnd(boolean firstMount);
|
|
|
|
@JvmtiMountTransition
|
|
private native void notifyJvmtiUnmountBegin(boolean lastUnmount);
|
|
|
|
@JvmtiMountTransition
|
|
private native void notifyJvmtiUnmountEnd(boolean lastUnmount);
|
|
|
|
@JvmtiMountTransition
|
|
private native void notifyJvmtiHideFrames(boolean hide);
|
|
|
|
private static native void registerNatives();
|
|
static {
|
|
registerNatives();
|
|
}
|
|
|
|
/**
|
|
* Creates the default scheduler.
|
|
*/
|
|
@SuppressWarnings("removal")
|
|
private static ForkJoinPool createDefaultScheduler() {
|
|
ForkJoinWorkerThreadFactory factory = pool -> {
|
|
PrivilegedAction<ForkJoinWorkerThread> pa = () -> new CarrierThread(pool);
|
|
return AccessController.doPrivileged(pa);
|
|
};
|
|
PrivilegedAction<ForkJoinPool> pa = () -> {
|
|
int parallelism, maxPoolSize, minRunnable;
|
|
String parallelismValue = System.getProperty("jdk.virtualThreadScheduler.parallelism");
|
|
String maxPoolSizeValue = System.getProperty("jdk.virtualThreadScheduler.maxPoolSize");
|
|
String minRunnableValue = System.getProperty("jdk.virtualThreadScheduler.minRunnable");
|
|
if (parallelismValue != null) {
|
|
parallelism = Integer.parseInt(parallelismValue);
|
|
} else {
|
|
parallelism = Runtime.getRuntime().availableProcessors();
|
|
}
|
|
if (maxPoolSizeValue != null) {
|
|
maxPoolSize = Integer.parseInt(maxPoolSizeValue);
|
|
parallelism = Integer.min(parallelism, maxPoolSize);
|
|
} else {
|
|
maxPoolSize = Integer.max(parallelism, 256);
|
|
}
|
|
if (minRunnableValue != null) {
|
|
minRunnable = Integer.parseInt(minRunnableValue);
|
|
} else {
|
|
minRunnable = Integer.max(parallelism / 2, 1);
|
|
}
|
|
Thread.UncaughtExceptionHandler handler = (t, e) -> { };
|
|
boolean asyncMode = true; // FIFO
|
|
return new ForkJoinPool(parallelism, factory, handler, asyncMode,
|
|
0, maxPoolSize, minRunnable, pool -> true, 30, SECONDS);
|
|
};
|
|
return AccessController.doPrivileged(pa);
|
|
}
|
|
|
|
/**
|
|
* Creates the ScheduledThreadPoolExecutor used for timed unpark.
|
|
*/
|
|
private static ScheduledExecutorService createDelayedTaskScheduler() {
|
|
String propValue = GetPropertyAction.privilegedGetProperty("jdk.unparker.maxPoolSize");
|
|
int poolSize;
|
|
if (propValue != null) {
|
|
poolSize = Integer.parseInt(propValue);
|
|
} else {
|
|
poolSize = 1;
|
|
}
|
|
ScheduledThreadPoolExecutor stpe = (ScheduledThreadPoolExecutor)
|
|
Executors.newScheduledThreadPool(poolSize, task -> {
|
|
return InnocuousThread.newThread("VirtualThread-unparker", task);
|
|
});
|
|
stpe.setRemoveOnCancelPolicy(true);
|
|
return stpe;
|
|
}
|
|
|
|
/**
|
|
* Reads the value of the jdk.tracePinnedThreads property to determine if stack
|
|
* traces should be printed when a carrier thread is pinned when a virtual thread
|
|
* attempts to park.
|
|
*/
|
|
private static int tracePinningMode() {
|
|
String propValue = GetPropertyAction.privilegedGetProperty("jdk.tracePinnedThreads");
|
|
if (propValue != null) {
|
|
if (propValue.length() == 0 || "full".equalsIgnoreCase(propValue))
|
|
return 1;
|
|
if ("short".equalsIgnoreCase(propValue))
|
|
return 2;
|
|
}
|
|
return 0;
|
|
}
|
|
}
|