junixsocket server report “too many files open“

Environment:

• OS: [mac os] Version [11.4]
• java version “1.8.0_131”
• junixsocket version 2.4.0

初步怀疑可能是关闭文件描述符的时候存在问题

该问题已经在最新版本2.5.0中修复

1、在server端每次调用accept（）方法时，程序的文件描述符列表都会增加一个none的文件描述符。并且在调用close方法后，这个文件描述符没有被关闭。

2、查看调用accept()方法

在代码执行到标记1的时候创建了一个空的文件描述符81
在代码执行到标记2的时候创建了一个指向/tmp/junixsocket-test.socket的文件描述符82

大致可以断定在标记2执行的时候没有关闭标记1中创建的文件描述符
接下来详细看标记2中的代码执行逻辑

①、上图中红色圈出的就是在标记1中创建的空文件描述符
②、在java代码中并没有显式的看到哪里释放了空的文件描述符，不知道在NATIVE方法中是否存在释放的逻辑。需要进一步看Native部分的逻辑实现…

client端代码

public class UDSClient {
  final static String udsPath = "/tmp/junixsocket-test.sock";
  public static void main(String[] args) throws IOException {

    final File socketFile = new File(udsPath);

    long start = System.currentTimeMillis();
    test2(socketFile);

    long end = System.currentTimeMillis();

    System.out.println("total = " + (end - start));
  }

  private static void test2(File socketFile) throws SocketException {
    for (int i = 0; i < 100000; i++) {
      FactoryArg factoryArg = new FactoryArg(udsPath);
      Socket sock = null;
      try {
        sock = factoryArg.createSocket();
        try {
          sock.connect(new InetSocketAddress("localhost", 1000));
        } catch (SocketException e) {
          System.out.println("Cannot connect to server. Have you started it?");
          System.out.println();
          throw e;
        }
        System.out.println("Connected");

        SocketUtil.clientHandle(sock);
      } catch (Exception e) {
        e.printStackTrace();
        System.out.println("i = " + i);
        break;
      } finally {
        try {
          sock.close();
        } catch (IOException e) {
          e.printStackTrace();
        } finally {
          System.out.println("client socket has closed！");
        }

      }
    }
  }

  private static void test1(File socketFile) {
    for (int i = 0; i < 100000; i++) {
      try (AFUNIXSocket sock = AFUNIXSocket.newInstance()) {
        try {
          sock.connect(AFUNIXSocketAddress.of(socketFile));
        } catch (SocketException e) {
          System.out.println("Cannot connect to server. Have you started it?");
          System.out.println();
          throw e;
        }
        System.out.println("Connected");

        SocketUtil.clientHandle(sock);
      } catch (Exception e) {
        e.printStackTrace();
        System.out.println("i = " + i);
        break;
      }
    }
  }

  //100000 -> 695857
  // 100000 1k -> 154671
  
}

server端代码

public final class UDSServer {


  private UDSServer() {
    throw new UnsupportedOperationException("No instances");
  }

  public static void main(String[] args) throws IOException {
    final File socketFile = new File("/tmp/junixsocket-test.sock");
    System.out.println(socketFile);
    AFUNIXServerSocket server = null;
    try {
      server = AFUNIXServerSocket.newInstance();
//      server.setReuseAddress(true);
      server.bind(AFUNIXSocketAddress.of(socketFile));
      System.out.println("server: " + server);

      while (!Thread.interrupted()) {
        System.out.println("Waiting for connection...");
        AFUNIXSocket sock = null;
        try {
          sock = server.accept();
          System.out.println("Connected: " + sock);

          SocketUtil.serverhandle(sock);
        } catch (IOException e) {
          if (server.isClosed()) {
            throw e;
          } else {
            e.printStackTrace();
          }
        }finally {
          if (sock != null) {
            sock.close();
          }
        }
      }
    }finally {
      if (server != null) {
        server.close();
      }
    }
  }


}

SocketUtil代码

public class SocketUtil {
  private static final int MAX_NUMBER = 5;
  private static String oneKBString = null;

  public static void serverhandle(Socket sock) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
      os = sock.getOutputStream();
      is = sock.getInputStream();
      os.write("Hello, dear Client".getBytes("UTF-8"));
      os.flush();

      byte[] buf = new byte[128];
      int read = is.read(buf);
      System.out.println("Client's response: " + new String(buf, 0, read, "UTF-8"));
    } finally {
      if (is != null) {
        is.close();
      }
      if (os != null) {
        os.close();
      }
    }
  }


  public static void clientHandle(Socket sock) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
      is = sock.getInputStream();
      os = sock.getOutputStream();
      TimeUnit.MILLISECONDS.sleep(1);

      os.write(getOneKB().getBytes("UTF-8"));
      os.flush();

      byte[] buf = new byte[128];
      int read = is.read(buf);
      System.out.println("Server says: " + new String(buf, 0, read, "UTF-8"));


    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (is != null) {
        is.close();
      }
      if (os != null) {
        os.close();
      }
    }
  }

  public static String getOneKB() {
    if (oneKBString == null) {
      StringBuffer stringBuffer = new StringBuffer();
      for (int i = 0; i < 1024; i++) {
        stringBuffer.append("A");
      }
      stringBuffer.append("n");
      oneKBString = stringBuffer.toString();
    }
    return oneKBString;
  }

}