java.net.SocketTimeoutException: Read timed out

Question

I have an application with client server architecture. The client use Java Web Start with Java Swing / AWT and the sert uses HTTP server / Servlet with Tomcat. The communication is made from the serialization of objects, create a ObjectOutput serializes a byte array and send to the server respectively called the ObjectInputStream and deserializes.

The application follows communicating correctly to a certain time of concurrency where starting to show error "SocketException read timeout". The erro happens when the server invoke the method ObjectInputStream.getObject() in my servlet doPost method.

The tomcat will come slow and the errors start to decrease server response time until the crash time where i must restart the server and after everything works.

Someone went through this problem ?

Client Code

URLConnection conn =  url.openConnection();
conn.setDoOutput(true);

OutputStream os = conn.getOutputStream();
ObjectOutputStream oss = new ObjectOutputStream(os);

oss.writeUTF("protocol header sample");

oss.writeObject(_parameters);
oss.flush();
oss.close();

Server Code

ObjectInputStream input = new ObjectInputStream(_request.getInputStream());
String method = input.readUTF();

parameters = input.readObject();

input.readObject() is where the error is

Answer 1

You haven't given us much information to go on, especially about the client side. But my suspicion is that the client side is:

• failing to setting the Content-length header (or setting it to the wrong value),
• failing to flush the output stream, and/or
• not closing the output side of the socket.

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Mysterious.

Based on your updated question, it looks like none of the above. Here are a couple of other possibilities:

• For some reason the client side is either locking up entirely during serialization or taking a VERY LONG TIME.
• There is a proxy between the client and server that is causing problems.
• You are experiencing load-related network problems, or network hardware problems.

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Another possible explanation is that you have a memory leak, and that the slowdown is caused by the GC taking more and more time as you run out of memory. This will show up in the GC logs if you have them enabled.

Answer 2

I think During high Concurrency, the Socket Timeout set in Tomcat is Expired and the connection is closed. The next read by Tomcat for that connection is greater than the server socket timeout specified in the server.
If you want to avoid this problem you have to increase the timeout on the server-side which is expired in your case. But not advisable.
BTW you did not give enough information. Did you increase the no of threads for connection in Tomcat? If you did, this surely would happen.