Java ExecutorService 无法在执行服务器时关闭

Question

我不确定关闭我的服务器（和 ExecutorService）到底是什么问题。我启动 ServerMain 并按回车键，这会使用 socket.close() 启动 server.shutdown() 方法，但不会抛出 SocketException。我不知道这是否与 ExecutorService 无法关闭有关。这是代码：

public class ServerMain {

public static void main(String[] args) throws DirectoryServerException, IOException {
    TCPDirectoryServer server = new TCPDirectoryServer();
    ExecutorService serverExecutor = Executors.newSingleThreadExecutor();
    try {
        server.start(1337);
        serverExecutor.execute(server);
        System.out.println("Server started. Press enter to terminate.");

        System.in.read();

        server.shutdown();
        System.out.println("Server is shut down...");
    } finally {
        serverExecutor.shutdown();
        while (!serverExecutor.isTerminated()) {
            try {
                if (!serverExecutor.awaitTermination(5, TimeUnit.SECONDS)) {
                    System.err.println("Problem with shutting down the Executor");
                    serverExecutor.shutdownNow();
                }
            } catch (InterruptedException ignore) {
            }
        }
    }
}
}

这是服务器：

public class TCPDirectoryServer implements DirectoryServer {
private int port;
private ConcurrentHashMap<ParseDirectory, Histogram> cache;
private List<ClientHandler> clientHandlerList;
private ExecutorService clientExecutorService;
private Socket socket;

public TCPDirectoryServer() {
    super();
    this.cache = new ConcurrentHashMap<ParseDirectory, Histogram>();
    this.clientHandlerList = new LinkedList<ClientHandler>();
    this.clientExecutorService = Executors.newCachedThreadPool();
}

@Override
public void start(int port) throws DirectoryServerException {
    this.port = port;
}

@Override
public void disconnect(ClientHandler clientHandler) {
    clientHandlerList.remove(clientHandler);

}

@Override
public void shutdown() throws DirectoryServerException {
    try {
        socket.close();
    } catch (IOException e) {
        throw new DirectoryServerException(e);
    }
}

@Override
public void run() {
    try (ServerSocket serverSocket = new ServerSocket(port)) {
        while (true) {
            socket = serverSocket.accept();
            clientHandlerList.add(connect(socket));
        }
    } catch (SocketException e) {
        System.err.println("AAAA");
        System.out.println("Server is shutting down");

    } catch (IOException e) {
        System.out.println("Something failed " + e.getMessage());
    }
}

Answer 1

这部分：

    while (true) {
        socket = serverSocket.accept();
        clientHandlerList.add(connect(socket));
    }

...当您调用 shutdown 时不会抛出 SocketException，因为您正在关闭那里的客户端套接字（最后连接的那个）。 ServerSocket 仍处于打开状态并等待传入请求。

Answer 2

调用 serverExecutor.shutdown() 仍会导致服务器在关闭之前等待所有进程完成。这是一个优雅的关机。它可能正在等待 "while(true)" 循环退出，但它看起来永远不会退出。尝试调用 serverExecutor.shutdownNow();终止您的程序。

Answer 3

在您的 TCPDirectoryServer class 中将 serverSocket 设为成员变量，您的关闭方法应如下所示

public void shutdown() {
   ......
   this.serverSocket.close();
   ........
}

此外，当关闭客户端套接字时，如果套接字为空（没有人连接到您的服务器），请注意 NPE。这也将防止您的服务器关闭。

Java ExecutorService 无法在执行服务器时关闭

Java ExecutorService can't shutdown with executing Server

java

server

executorservice