jeromq:关闭上下文失败

Question

编辑:解决了自己,见下文(虽然我不确定我是否偶然发现了一个错误)

使用下面的简单hello-world请求 - 回复示例,在程序结束时关闭上下文失败:它只是挂起ctx.close()或者抛出以下异常:

Exception in thread "reaper-1" java.lang.NullPointerException
    at zmq.Ctx.destroy_socket(Ctx.java:327)
    at zmq.ZObject.destroy_socket(ZObject.java:144)
    at zmq.SocketBase.check_destroy(SocketBase.java:938)
    at zmq.SocketBase.start_reaping(SocketBase.java:753)
    at zmq.Reaper.process_reap(Reaper.java:133)
    at zmq.ZObject.process_command(ZObject.java:114)
    at zmq.Reaper.in_event(Reaper.java:90)
    at zmq.Poller.run(Poller.java:233)
    at java.lang.Thread.run(Thread.java:724)

无论哪种方式,程序都不会停止.

这是代码(请注意,套接字在创建它们的线程中都是关闭的):

import org.zeromq.ZMQ;
import org.zeromq.ZContext;

public class App {
    public static void main(String[] args) throws InterruptedException {
        final ZContext ctx = new ZContext();

        final Thread t1 = new Thread() {
            @Override
            public void run() {
                ZMQ.Socket socket = ctx.createSocket(ZMQ.REQ);
                socket.connect("inproc://test");
                System.err.format("[Thread %s] socket connected%n", Thread.currentThread().getId());
                socket.send("hello");
                System.err.format("[Thread %s] hello sent%n", Thread.currentThread().getId());
                String result = socket.recvStr();
                System.err.format("[Thread %s] received response '%s'%n", Thread.currentThread()
                        .getId(), result);
                socket.close();
                System.err.format("[Thread %s] socket closed%n", Thread.currentThread().getId());
                ctx.destroySocket(socket);
                System.err.format("[Thread %s] socket destroyed%n", Thread.currentThread().getId());
            }
        };
//      t1.start();

        final Thread t2 = new Thread() {
            @Override
            public void run() {
                ZMQ.Socket socket = ctx.createSocket(ZMQ.REP);
                socket.setLinger(10000);
                socket.bind("inproc://test");
                System.err.format("                    [Thread %s] socket bound%n", Thread.currentThread().getId());
                String request = socket.recvStr();
                assert request == "hello";
                System.err.format("                    [Thread %s] received request '%s'%n", Thread.currentThread()
                        .getId(), request);
                socket.send("world");
                socket.close();
                System.err.format("                    [Thread %s] socket closed%n", Thread.currentThread().getId());
                ctx.destroySocket(socket);
                System.err.format("                    [Thread %s] socket destroyed%n", Thread.currentThread().getId());
            }
        };
        t2.start();
        Thread.sleep(2000);
        t1.start();

        System.err.println("waiting on the threads to finish...");
        t1.join();
        t2.join();

        System.err.println("closing context...");
        ctx.close();
    }
}

编辑:解决了

事实证明这socket.close()不起作用,ctx.destroySocket(socket)仅此一点就足够了(它也关闭了套接字).因此删除socket.close()可以解决问题.这是一个错误吗？

Answer 1

有同样的问题；这不是一个错误，使用其中之一，而不是两者，但使用ZContext方法，它们更有效。

close()显式关闭套接字，因此ctx.destroySocket()之后调用会抛出该异常。如果您需要关闭套接字，请使用，根本ctx.destroySocket()不使用，并且始终使用在关闭并正常退出之前关闭上下文，它将自动关闭从该上下文创建的任何套接字。close()ctx.destroy()