Network Application getting Errors

Question

Admittedly, I'm a little green on java having only taken one class in college, but I am in dire need of some assistance.
A little background into my issue:
I work for a company that sells a business management software package, and equipment, for running businesses, primarily hardware stores and lumber yards.
We run Linux servers and as part of our Point of Sale (POS) Devices, we have ethernet Ingenico Signature pads. We communicate to the signature pads via java programs to create a socket, send/receive information, and close the socket. The issue I'm seeing is that in times of high volume use, we are getting errors saying that the system could not create a socket. A snippet of code is as follows:
SocketFactory sf = new SocketFactory(debug);
sconn = sf.getSocket(WAIT_ON_CONNECT_TIMEOUT);
sconn = new Socket();
if (sconn == null) {
logNow("***** Could not create socket after " +
WAIT_ON_CONNECT_TIMEOUT + " millis!!! Exiting..............."
System.exit(100);
Then in SocketFactory:
public void run() {
Socket socket = new Socket();
if (DEBUG) {
log("Socket object created: " + socket);
list.add(socket);
if (DEBUG) {
log(this.name + " Thread ended after creating socket.");
public Socket getSocket(int timeout) {
long current = System.currentTimeMillis();
long end = current + timeout;
while (current < end) {
if (list.size() > 0) {
Socket socket = (Socket) list.get(0);
return socket;
/* If nothing is found in the list, loop again until timeout after s
leeping for a while to let the
other thread create the Socket and put it in the ArrayList. */
try {
Thread.currentThread().sleep(20);
} catch (InterruptedException ex) {}
current = System.currentTimeMillis();
return null; /* Nothing in the ArrayList yet. Return null. */
As typing this, I have a thought. We have 1 server and 20 signature pads connecting to the server. Each signature pad uses port 9889. It appears to me that the error is occuring creating a socket on the server, not connecting it to the signature pad. Is it possible that two instances of the java application, that happen to occur at the exact same time, might be trying to grab the same random socket on the server?
How can I resolve this?
What I was thinking was modify the program to use a specific host server port, but this causes a java exception error because it won't use a socket port that is in time_wait status. So I thought to setReuseAddress(true) but cannot get this to work if I create a socket with specific host port. I'm creating the socket with the following:
Socket socket = new Socket(host, port, localip, localPort);
This of course will create the socket but not allow me to setReuseAddress. Any thoughts on how I might fix this issue? Am open to any suggestions and willing to read any information suggested.

Answer 1

Ok, I found my issue now. It's hanging trying to create a socket. Is there a way I can get it to try to create a socket for say... 5 seconds, then stop?
Here's what I have in my code now:
while (sconn == null) {
try {
plain = DateFormat.getDateTimeInstance(DateFormat.SHORT,
DateFormat.LONG);
now = plain.format(new Date());
System.err.print(now);
logNow("creating socket " + now);
sconn = new Socket(host, port);
} catch (Throwable ex) {
System.err.println("Fatal Error: exception occurred\n" +
ex.getMessage());
ex.printStackTrace();
if (sconn == null) {
logNow("***** Could not create socket " );
plain = DateFormat.getDateTimeInstance(DateFormat.SHORT,
DateFormat.LONG);
now = plain.format(new Date());
System.err.print(now);
logNow("socket created" + now);
Ok, a couple of notes about what I'm doing here. I have to prove that this is fixing the socket creation error, hence if (sconn == null) section. I did not know where the 3 - 10 minute hang was coming from, so I put the plain = DateFormat and logNow("blah " + now); throughout my code to get several time stamps to get an idea of where issue is occurring. I finally found it here. I do not believe it's looping because I'm not seeing the "could not create socket" error. I put the date in the loop partially to see if it was looping, if for example the socket wasn't created, it looped, and I wasn't getting a true test of sconn == null.
From my log:
Checking command: port
Checking command: no-debug
Checking command: txn-type
Checking command: amount
Checking command: auth-request
8/28/08 5:28:34 PM CDT8/28/08 5:28:34 PM CDT creating socket 8/28/08 5:28:34 PM CDT
8/28/08 5:31:43 PM CDT8/28/08 5:31:43 PM CDT socket created8/28/08 5:31:43 PM CDT
Executing command: port
Executing command: no-debug
Executing command: txn-type
8/28/08 5:31:43 PM CDT sndMsg() startTime 8/28/08 5:31:43 PM CDT
So this shows it's only running through once. I suppose this means I need a maximum time to create the socket, and then just try again... say, 5 times... I know how to make it try again, that's not an issue. I just need to know if I can designate a timeout on the actual socket creation.
NOTE: I also tried just sconn = Socket() then later sconn.connect(saddr,8000) which was in there before with socket factory, and using saddr which grabbed the hostname/IP and port of the signature pad.
Thanks for all your assistance, I've made a lot of progress and have learned a bit on the way. you've confirmed for me what I suspected was going on, and a solution for it even though I am not the best at explaining my thoughts and needs. I apologize for my lack of knowledge and pledge to get better as I'm thouroughly enjoying this.