java线程池源码解析

1.从提交Runnable开始

2. 具体流程（简化代码）

public void execute(Runnable command) {
	addWorker(command);
}

 private boolean addWorker(Runnable firstTask, boolean core) {
 	 w = new Worker(firstTask);
 	 //Worker中的Thread对象,真正执行工作的线程
     final Thread t = w.thread;
     //重要代码，会执行Worker中的run方法，进而执行runWorker()方法
     t.start();
 }

private final class Worker implements Runnable{
	final Thread thread; 
	//firstTask肯定是先被执行的，随后新建的这个线程就会从任务队列中不断getTask()，没有Task则阻塞
    Runnable firstTask;
    
    Worker(Runnable firstTask) {
   	setState(-1); // inhibit interrupts until runWorker
    this.firstTask = firstTask;
    //注意此处，newThread时将自己传入了
    //和上面联系起来
    this.thread = getThreadFactory().newThread(this);
    }
    
    public void run() {
       runWorker(this);
    }
}

final void runWorker(Worker w) {
        Thread wt = Thread.currentThread();
        Runnable task = w.firstTask;
        w.firstTask = null;
        w.unlock(); // allow interrupts
        boolean completedAbruptly = true;
        try {
            while (task != null || (task = getTask()) != null){
            	task.run();
            }

private Runnable getTask() {
        boolean timedOut = false; // Did the last poll() time out?

        for (;;) {
            try {
                Runnable r = timed ?
                    workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) :
                    workQueue.take();
                if (r != null)
                    return r;
                timedOut = true;
            } catch (InterruptedException retry) {
                timedOut = false;
            }
        }
    }

总结：

1.为啥工作线程在firstTask结束后没有die？ 因为内部有getTask(),是死循环，从阻塞队列中当取task时，取不到则阻塞
2.Woker对象，是一个封装线程的Runnable，addWoker内部，会执行Worker中的thread.start,进而执行runWoker，从而不断的获取task，执行task

本文地址：https://blog.csdn.net/weixin_38282516/article/details/107350764