JDK-调度线程池

最新推荐文章于 2024-12-03 20:10:06 发布

Java老鸟-峰

最新推荐文章于 2024-12-03 20:10:06 发布

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分类专栏：源码文章标签： Java JDK

本文链接：https://blog.youkuaiyun.com/fl_zxf/article/details/140012314

版权

使用示例

https://github.com/zengxf/small-frame-demo/blob/master/jdk-demo/simple-demo/src/main/java/test/jdkapi/juc/thread_pool/TestSchedule.java

JDK 版本

openjdk version "17" 2021-09-14
OpenJDK Runtime Environment (build 17+35-2724)
OpenJDK 64-Bit Server VM (build 17+35-2724, mixed mode, sharing)

原理

类结构

java.util.concurrent.ScheduledThreadPoolExecutor

/*** 调度线程池 */
public class ScheduledThreadPoolExecutor
        extends ThreadPoolExecutor
        implements ScheduledExecutorService 
{
   
    /*** 构造器 */
    public ScheduledThreadPoolExecutor(int corePoolSize) {
   
        super(corePoolSize, Integer.MAX_VALUE,
              DEFAULT_KEEPALIVE_MILLIS, MILLISECONDS,
              new DelayedWorkQueue()); // 使用内部队列作任务队列 sign_c_001
    }

}

java.util.concurrent.ScheduledThreadPoolExecutor.DelayedWorkQueue

    /*** sign_c_001 延迟任务队列 */
    static class DelayedWorkQueue extends AbstractQueue<Runnable>
        implements BlockingQueue<Runnable> 
    {
   
        private static final int INITIAL_CAPACITY = 16; // 初始队列大小 16 个
        private RunnableScheduledFuture<?>[] queue =
            new RunnableScheduledFuture<?>[INITIAL_CAPACITY];
        private final ReentrantLock lock = new ReentrantLock();
        private final Condition available = lock.newCondition();
    }

java.util.concurrent.ScheduledThreadPoolExecutor.ScheduledFutureTask

    /*** sign_c_010 调度任务 */
    private class ScheduledFutureTask<V>
            extends FutureTask<V> implements RunnableScheduledFuture<V> // 继承 sign_c_011 实现 sign_i_011
    {
   
        private final long sequenceNumber;  // 序列号(添加时递增设置)
        private volatile long time;         // 触发时间(执行的时间点)，基于纳米
        /**
         * 重复任务的周期，以纳秒为单位。
         * 正值表示固定速率执行。
         * 负值表示固定延迟执行。
         * 值为 0 表示非重复（单次）任务。
         */
        private final long period;

        // 构造器
        ScheduledFutureTask(Runnable r, V result, long triggerTime,
                            long period, long sequenceNumber) {
   
            super(r, result); // 执行体交给父类(sign_c_011)保存
            this.time = triggerTime;
            this.period = period