Thread中断

• 为什么他们都抛出InterruptedException?
  Thread.sleep();
  BlockingQueue.put()/take();
• Thread.interrupt()唯一的作用就是取消一个耗时的操作;

// newThread 在sleep到500ms时,被主线程中断;
public static void main(String[] args) throws InterruptedException {
        Thread newThread = new Thread(()->{
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                System.out.println("I'm interrupted!");
                e.printStackTrace();
            }
        });
        newThread.start();

        Thread.sleep(500);
        newThread.interrupt();
    }

控制台结果:
java.lang.InterruptedException: sleep interrupted
    at java.lang.Thread.sleep(Native Method)
    at com.jd.paas.ofc.fpe.transfer.core.domain.support.model.ware.ProductExtInfo.lambda$main$0(ProductExtInfo.java:23)
    at java.lang.Thread.run(Thread.java:748)
I'm interrupted!

  1. 任何线程都可以被中断吗? --不是,取决于这个线程自己的决定;

// 例子: newThread 无限循环,不会被打断
public static void main(String[] args) throws InterruptedException {
        Thread newThread = new Thread(()->{
            try {
                int i = 0;
                while (true){
                    doNothing();
                    i++;
                }
            } catch (InterruptedException e) {
                System.out.println("I'm interrupted!");
                e.printStackTrace();
            }
        });
        newThread.start();

        Thread.sleep(500);
        newThread.interrupt();
    }

    private static void doNothing() throws InterruptedException{
    }

  2. 中断只能发生在这些方法里吗? -- 取决于线程自己的策略,JVM的阻塞方法都会正常响应;

• 允许线程A对线程B进行有限程度的控制;
  1.线程可以选择不响应InterruptedException,但是不推荐;
  2.除非你非常确定目标线程的中断特性,否则不要中断他;

    public static void main(String[] args) throws InterruptedException {
        Thread newThread = new Thread(()->{
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // 如果无法处理InterruptedException中断,那么最好重新设置中断标志位,使得其他人能知道该线程被中断了;
                Thread.currentThread().interrupt();
            }
        });
        newThread.start();
    }

常见的线程取消方法:
1. 线程池ExecutorService的Future中存在cancel(boolean mayInterruptIfRunning);
@param mayInterruptIfRunning {@code true} if the thread executing this task should be interrupted; otherwise, in-progress tasks are allowed to complete //如果入参mayInterruptIfRunning 是true,那么正在运行的线程中断,否则允许正在进行的线程完成后,才被取消;