Question

i’ve a memory leak problem on java Socket Object communication.

this is my send thread.

    // create a new thread to send the packet
@Override
public synchronized void run() {

    if(!genericSocket.isConnected()){
        if(logger.isEnabled())
            logger.logMessage(PFLogging.LEVEL_WARN, "Socket is close");
        return;
    }

    int retry = 0;
    boolean packetSent = false;

    synchronized (objWriter) {
        while ((retry < RETRY) && (!packetSent) && (genericSocket.isConnected())) {
            try {
                objWriter.writeObject(bean);

                objWriter.flush();



                // Try until the cache is reset and the memory is free
                /*
                boolean resetDone = false;
                while(!resetDone) {
                    try {
                        objWriter.reset();
                        resetDone = true;
                    } catch (IOException r) {
                        Thread.sleep(1);
                    }
                }
                */

                // No error and packet sent
                continuousError = 0;
                packetSent = true;
            } catch (Exception e) {
                continuousError++;

                if(logger.isEnabled())
                    logger.logMessage(PFLogging.LEVEL_ERROR, "Continuous Error [" + continuousError + "] sending message [" + e.getMessage() + "," + e.getCause() + "]");

                // control the number of continuous errors
                if(continuousError >= CONTINUOUS_ERROR) {
                    if(logger.isEnabled())
                        logger.logMessage(PFLogging.LEVEL_WARN, "I close the socket");
                    genericSocket.disconnect();
                }

                // next time is the time!
                retry++;
            }
        }
    }
}

the cache, when i sent about i packet per ms grow and grow!

if i add the commented part the cache is clean but when i need to send an async long message (about 3000 char) i see that the other message are lost!

There’s another way to clean the cache without reset it??

Answer 1

ObjectOutputStream.reset() is not avoidable as it is the only means of clearing local hash tables, you can refer java source code for ObjectOutputStream for details of what happens in reset(), or else you will get OutOfMemoryError eventually

But you can very well implement a function like

private void writeObject(Object obj, ObjectOutputStream oos) throws IOException
    {
        synchronized(oos)
        {
            oos.writeObject(obj);
            oos.flush();
            oos.reset();
        }
    }

However you must ensure that all writes to ObjectOutputStream happens through this method.