test/jdk/java/net/Socket/DeadlockTest.java

/*
 * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 4176738
 * @library /test/lib
 * @summary Make sure a deadlock situation
 *     would not occur
 * @run main DeadlockTest
 * @run main/othervm -Djava.net.preferIPv4Stack=true DeadlockTest
 */

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;

import jdk.test.lib.net.IPSupport;

public class DeadlockTest {
    public static void main(String[] argv) throws Exception {
        IPSupport.throwSkippedExceptionIfNonOperational();

        ServerSocket ss = new ServerSocket(0, 0, InetAddress.getLoopbackAddress());
        Socket clientSocket = new Socket();

        try {
            // Start the server thread
            Thread s1 = new Thread(new ServerThread(ss));
            s1.start();

            // Start the client thread
            ClientThread ct = new ClientThread(clientSocket, ss.getLocalPort());
            Thread c1 = new Thread(ct);
            c1.start();

            // Wait for the client thread to finish.
            // If it doesn't finish then it's a sign of a deadlock
            c1.join();
        } finally {
            ss.close();
            clientSocket.close();
        }
    }
}

class ServerThread implements Runnable {

    private static boolean dbg = false;

    ObjectInputStream in;
    ObjectOutputStream out;

    ServerSocket server;

    Socket sock;

    public ServerThread(ServerSocket serverSocket) throws Exception {
        this.server = serverSocket;
    }

    public void ping(int cnt) {
       Message.write(out, new PingMessage(cnt));
    }

    private int cnt = 1;

    public void run() {

        try {
            if (Thread.currentThread().getName().startsWith("child") == false) {
                sock  = server.accept();

                new Thread(this, "child").start();

                out = new ObjectOutputStream(sock.getOutputStream());
                out.flush();

                if (dbg) System.out.println("*** ping0 ***");
                ping(0);
                if (dbg) System.out.println("*** ping1 ***");
                ping(1);
                if (dbg) System.out.println("*** ping2 ***");
                ping(2);
                if (dbg) System.out.println("*** ping3 ***");
                ping(3);
                if (dbg) System.out.println("*** ping4 ***");
                ping(4);
                if (dbg) System.out.println("*** end ***");
            }

        } catch (Throwable e) {
            System.out.println(e);
            // If anything goes wrong, just quit.
        }

        if (Thread.currentThread().getName().startsWith("child")) {
            try {

                in  = new ObjectInputStream(sock.getInputStream());

                while (true) {
                    if (dbg) System.out.println("read " + cnt);
                    Message msg = (Message) in.readObject();
                    if (dbg) System.out.println("read done " + cnt++);
                    switch (msg.code) {
                    case Message.PING: {
                        if (true) System.out.println("ping recv'ed");
                    } break;
                    }

                }

            } catch (Throwable e) {
                // If anything goes wrong, just quit.       }
            }
        }
    }
}

class ClientThread implements Runnable {

    ObjectInputStream  in;
    ObjectOutputStream out;

    Socket sock;

    public ClientThread(Socket sock, int serverPort) throws Exception {
        try {
            System.out.println("About to connect the client socket");
            this.sock = sock;
            this.sock.connect(new InetSocketAddress(InetAddress.getLoopbackAddress(), serverPort));
            System.out.println("connected");

            out = new ObjectOutputStream(sock.getOutputStream());
            out.flush();
        } catch (Throwable e) {
          System.out.println("client failed with: " + e);
          e.printStackTrace();
          throw new Exception("Unexpected exception");
        }
    }

    private int cnt = 1;

    public void run() {
        try {
          in  = new ObjectInputStream(sock.getInputStream());

          int count = 0;

          while (true) {
              System.out.println("read " + cnt);
              Message msg = (Message) in.readObject();
              System.out.println("read done " + cnt++);
              switch (msg.code) {
              case Message.PING: {
                  System.out.println("ping recv'ed");
                  count++;
              } break;
              }
              if (count == 5) {
                  sock.close();
                  break;
              }
          }
        }  catch (IOException ioe) {
        } catch (Throwable e) {
            // If anything went wrong, just quit
        }
    }

}

class Message implements java.io.Serializable {

    static final int UNKNOWN = 0;
    static final int PING = 1;

    protected int code;

    public Message() { this.code = UNKNOWN; }

    public Message(int code) { this.code = code; }

    private static int cnt = 1;

    public static void write(ObjectOutput out, Message msg) {
        try {
            System.out.println("write message " + cnt);
            out.writeObject(msg);
            System.out.println("flush message");
            out.flush();
            System.out.println("write message done " + cnt++);
        } catch (IOException ioe) {
            // Ignore the exception
            System.out.println(ioe);
        }
     }
}

class PingMessage extends Message implements java.io.Serializable {

      public PingMessage() {
          code = Message.PING;
      }

      public PingMessage(int cnt)
      {
          code = Message.PING;
          this.cnt = cnt;

          data = new int[50000];
      }

      int cnt;
      int[] data;
}