Java 如何停止 ScheduledExecutorService？
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How to stop a ScheduledExecutorService?
提问by ferro
The program finishes after nine prints:
程序在打印九次后完成：
class BeeperControl {
private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
public void beep() {
final Runnable beeper = new Runnable() {
public void run() {
System.out.println("beep");
}
};
final ScheduledFuture<?> beeperHandle = scheduler.scheduleAtFixedRate(
beeper, 1, 1, SECONDS);
scheduler.schedule(new Runnable() {
public void run() {
beeperHandle.cancel(true);
}
}, 1 * 9, SECONDS);
}
public static void main(String[] args) {
BeeperControl bc = new BeeperControl();
bc.beep();
}
}
How to stop a process (i.e. java process in eclipse for example) because it does not stop after a time limit in 9 seconds?
如何停止一个进程（例如 eclipse 中的 java 进程），因为它在 9 秒的时间限制后没有停止？
采纳答案by RealSkeptic
The issue you have is that the scheduler keeps a live thread around after you have cancelled the beep task.
您遇到的问题是，在您取消哔声任务后，调度程序会保留一个实时线程。
If there is a live non-daemon thread, the JVM stays alive.
如果存在活动的非守护线程，则 JVM 会保持活动状态。
The reason that it keeps this thread around is that you have told it to do so in this line:
它保留此线程的原因是您已在此行中告诉它这样做：
private final ScheduledExecutorService scheduler
= Executors.newScheduledThreadPool(1);
Note the documentation of newScheduledThreadPool(int corePoolSize):
请注意以下文档newScheduledThreadPool(int corePoolSize)：
corePoolSize- the number of threads to keep in the pool, even if they are idle.
corePoolSize- 要保留在池中的线程数，即使它们处于空闲状态。
So, you have two possible ways to cause the JVM to terminate:
因此，您有两种可能的方法来导致 JVM 终止：
Pass
0tonewScheduledThreadPoolinstead of 1. The scheduler will not keep a live thread, and the JVM will terminate.Shut down the scheduler. You are supposed to do so anyway to release its resources. So change the
runin your anonymousRunnableto:public void run() { beeperHandle.cancel(true); scheduler.shutdown(); }
传递
0到newScheduledThreadPool而不是 1。调度程序不会保持活动线程，JVM 将终止。关闭调度程序。无论如何，您都应该这样做以释放其资源。因此
run，将匿名更改Runnable为：public void run() { beeperHandle.cancel(true); scheduler.shutdown(); }
(In fact, you don't need the cancelthere - the shutdownwill take effect as soon as the next "beep" is completed.)
（实际上，您不需要cancel那里 -shutdown一旦下一个“哔”声完成，它将立即生效。）
