Re: Multiple Client Sockets, Single java program, connect to server socket, possible?

Gordon Beaton <>
08 Dec 2006 12:54:58 GMT
On 8 Dec 2006 02:55:02 -0800, wrote:

I have a strange problem. I started work on software expecting that it
was possible to create many client sockets in a single instance of a
java program that connect to a single server where ever that maybe.

Your code is unnecessarily complex for the task, and somewhat
difficult to follow. Here are some suggestions:

- you are doing too much work in your constructors. Use the
  constructor to *initialise* the object. Invoke methods to *do*
  something with the object.

- drop all use of setReuseAddress(), it serves no purpose at all here.

- the normal way to delay execution is with Thread.sleep(). Calling
  notify() followed by wait() does not do what you seem to think, but
  you shouldn't be polling here anyway.

- I cannot see need for any synchronization (notify(), wait(), or
  yield()) in this code, and your use of these methods seems to
  indicate that you do not really understand what they do, or how to
  fix your program.

- there is no need to use available() before reading, in fact it will
  only cause you grief. You can replace your read loop with something
  more like this:

    try {
      while (true) {
        str = dis.readUTF();
    catch (IOException e) {

  The above loop could be made even simpler if you used a
  BufferedReader instead of a DataInputStream, since reaching EOF
  isn't really an exceptional event.

- your server fails to close the client socket after reaching EOF.
  Don't rely on GC for this, you *will* run out of descriptors.

- when a client calls connect(), it will succeed even though the
  server is not waiting in accept(), and it will be able to send a
  limited amount of data. However unless the server invokes accept(),
  there is nobody receiving the data, and the client will eventually

- after accepting a connection, do not simply invoke the reqRec
  constructor (most of which should be in a method anyway). After
  calling accept() the server must create a thread to handle each new
  client, so that it can go back to accept() as quickly as possible.


[ don't email me support questions or followups ]
g o r d o n + n e w s @ b a l d e r 1 3 . s e

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