Reusing sockets in server-client

Question

I am trying to create a client-server system: my server is a raspberry pi which is running a python webserver on it, and my client is on a different pc and is written is Java. The idea is that the server collects data and when it gets a request from a client, it sends the data to the client. My client should request the data, wait for 10 seconds and request again etc.

Currently this system is working, but after a day or so, the client starts getting a lot (but not continuously) socket timeouts. I think that this may be the case because for each request I create a new socket for communication and I think that after a day the sockets run out or something like that. This is the code the client executes every 10 seconds:

    public static String getData() throws Exception {
    TreeSet<Integer> primes = MathUtils.primesSieve(10000);
    try {
        String data = "";
        Socket socket = new Socket(SERVER_ADDRESS, SERVER_PORT);
        socket.setReuseAddress(true);
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        int msg = ColUtils.drawRandomlyWithReplacement(primes, 1, ArrayList::new).get(0);
        out.write(msg+"");
        out.flush();
        String input;
        while ((input = in.readLine()) != null) {
            data += input;
            if (!data.endsWith("#" + prod(msg))) {
                throw new Exception("WRONG ECHO");
            }
        }
        socket.close();

        return data;
    } catch (Exception e) {
        e.printStackTrace();
    }

    return null;
}

I tried fixing it by having a socket which is a member of the encapsulating class, but after a singe request the inputstream stopped working. Is there any way where I can keep using a single socket for ALL communications with the server? Or is this the recommended way of doing this sort of communication?

Answer 1

Try first closing the socket and input, output streams. As in your code there is no quarantee that you are releasing the acquired objects.

PrintWriter out = null;
BufferedReader in = null;
Socket socket = null;
try {
  ...//your statements
} catch (Exception ex) {
  //catch or whatever
} finally {
  if (out != null) out.close();
  if (in != null) in.close();
  if (socket != null) socket.close();
}

Answer 2

try to make the Socket object static If possible that would created only once and read the data every 10 sec Otherwise u can instantiate it before calling the getData method and then read it. Doing so will make only 1 copy of Socket.

And I don't think u are running out of ports. The reason might be quit simple that your Program is not receiving the data before the time out. and it is a normal case in a bad network

Socket generally waits indefinitely until it receives data if the timeout is not set Programmatically