在main（）完成后，RMI线程阻止JVM退出 [英] RMI Threads prevent JVM from exiting after main() completes

问题描述

总而言之，在我的应用程序不再需要RMI之后，我无法让几个Java RMI的非守护程序线程关闭。这可以防止JVM在main（）完成时退出。

To make a long story short, I'm having trouble getting a couple of Java RMI's non-daemon threads to close out after my application no longer needs RMI. This prevents the JVM from exiting when main() completes.

我知道导出 UnicastRemoteObject s将导致RMI保持线程打开，直到您成功调用 UnicastRemoteObject.unexportObject（Object o，boolean force）。这是一个例子（运行没有修改，JVM将正常退出 - 删除对unexportObject的调用，JVM永远不会退出）：

I understand that exporting UnicastRemoteObjects will cause RMI to leave threads open until you successfully call UnicastRemoteObject.unexportObject(Object o,boolean force). Here's an example (run without modification and the JVM will exit normally - remove the call to unexportObject and the JVM will never exit):

import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;

public class TestUnicastRemoteObject{
private static UnicastRemoteObject obj;
private static Registry registry;

public static void main(String[] args) throws Exception{
    obj = new UnicastRemoteObject(){
        private static final long serialVersionUID = 1L;
    };
    System.err.println("created UnicastRemoteObject");
    System.err.println("creating registry ...");
    registry = LocateRegistry.createRegistry(9999);
    System.err.println("registry created.");
    System.err.println("binding obj to registry ...");
    registry.bind("Test", obj);
    System.err.println("bound");
    UnicastRemoteObject.unexportObject(obj, true);
    System.err.println("unexported obj");
}
}

此外，您是否并不重要创建注册表和/或将远程对象绑定到它 - 在这个示例中唯一重要的是，无论何时创建UnicastRemoteObject，都需要调用 unexportObject 为了防止任何线程在你完成之后剩下。

Also, it doesn't seem to matter whether you create the registry and/or bind the remote object to it - the only thing that seems to matter in this example is that any time you create a UnicastRemoteObject, you need to call unexportObject in order to prevent any threads from remaining after you're done.

在我的应用程序中，我确保在我创建的每个UnicastRemoteObject上都调用了unexportObject，然而，当我的应用程序使用RMI资源完成时，RMI的收割线程和连接接受线程仍然存在，阻止我的JVM退出。

In my application, I've made sure that I've called unexportObject on every UnicastRemoteObject I create, and yet RMI's "reaper" thread and "connection accept" thread still persist, preventing my JVM from exiting when my application is finished using RMI resources.

除了忘记取消导出UnicastRemoteObjects之外，是否有其他可能导致RMI留下线程的东西？

Is there something else that could cause RMI to leave threads behind, aside from forgetting to unexport UnicastRemoteObjects?

推荐答案

果然，我在代码中遇到了一个错误，导致我的（很多）UnicastRemoteObjects中的一个在ca时没有导出自身lling应用程序是利用它完成的。所以答案是：

Sure enough, I had a bug in the code that caused one of my (many) UnicastRemoteObjects to not unexport itself when the calling application was done utilizing it. So the answer is:

在正在运行的JVM中撤消所有UnicastRemoteObjects就足以关闭所有RMI非守护程序线程。

Unexporting all UnicastRemoteObjects within a running JVM is sufficient to close all RMI non-daemon threads.

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