发生TimeoutException时JVM不会退出

时间:2010-03-10 18:47:13

标签: java jvm executorservice timeoutexception

我有代码需要做这样的事情

有一个类列表,每个类都有一些方法(比如execute())。我需要在每个类上调用该方法,并且每次调用都有一个固定的timeOut。现在,其中一个类的execute方法编写得很糟糕,导致jvm不退出的超时。我正在运行这样的课程。

java ExecutorServiceTest execute TestClass1 TestClass2 TestClass3

为什么在完成代码执行后jvm没有退出?

我得到以下输出

In class 1
In Class 2
java.util.concurrent.TimeoutException
at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at ExecutorServiceTest.main(ExecutorServiceTest.java:78)
java.util.concurrent.TimeoutException
at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)

第二个类的执行超时,之后,第三个类的执行也超时。为什么第三类的执行超时?

执行完成后,jvm不会退出。是什么原因?另外为什么TestClass3执行timedout?

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

class Task implements Callable<String> {
    Object instance;
    Method m;
    Object[] input;
    Task(Object instance, Method m, Object[] input) {
        this.instance = instance;
        this.m = m;
        this.input = input;
    }
    public String call() {
        String s = "initial";
        try {
            m.invoke(instance, input);
        }
        catch (RuntimeException e) {
        }
        catch (Exception e) {
        }
        finally {

        }
        return s;
    }
}


public class ExecutorServiceTest {
    public static void main(String[] args) {
        String methodName = args[0];
        String className;
        List<Object> instanceList = new ArrayList<Object>();
        for (int i=1;i<args.length;i++) {
            className = args[i];
            Object o = null;
            try {
                o = Class.forName(className).newInstance();
            } catch (InstantiationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            instanceList.add(o);
        }
        ExecutorService executor = Executors.newSingleThreadExecutor();
        Iterator<Object> iter = instanceList.iterator();
        while (iter.hasNext()) {
            Object o = iter.next();
            Method m = null;
            try {
                m = o.getClass().getDeclaredMethod(methodName, new Class[] {});
            } catch (SecurityException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (NoSuchMethodException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            Task t = new Task(o,m,new Object[]{});
            Future<String> fut = executor.submit(t);
            try {
                fut.get(2,TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ExecutionException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (TimeoutException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        executor.shutdown();
    }
}


public class TestClass1 {
    public void execute() {
        System.out.println("In class 1");
    }
}


public class TestClass2 {
    public void execute() {
        System.out.println("In class 2");
        boolean b = true;
        while (b) {

        }
    }
}


public class TestClass3 {
    public void execute() {
        System.out.println("In class 3");
    }
}

2 个答案:

答案 0 :(得分:2)

您需要调用executor.shutdown()或创建一个守护程序线程(使用传递给ThreadFactory的相应Executors.newSingleThreadExecutor()

答案 1 :(得分:2)

ExecutorService.shutdown()实际上并不会停止任何正在运行的执行程序/线程,it just tells the service to stop accepting new tasks

  

void shutdown()
  启动有序关闭,其中先前提交的任务将被执行,但不会接受任何新任务。如果已经关闭,调用没有额外的效果。

你的TestClass2实例永远不会停止运行,因为它有一个永不停止的while(true)循环。

如果您想立即停止ExecutorService,可以使用awaitTermination(long timeout, TimeUnit unit)shutdownNow()