How can I make a socket close immediately, bypassing the timeout period?

Question

In Java, when you close a socket, it doesn't do anything anymore, but it actually closes the TCP connection after a timeout period.

I need to use thousands of sockets and I want them to be closed immediately after I close them, not after the timeout period, which wastes my time and my resources. What can I do?

Answer 1

I found out that by using socket.setReuseAddress(boolean), you can tell the JVM to reuse the port even if it's in the timeout period.

Answer 2

You are probably seeing sockets in TIME_WAIT state. This is the normal state for a socket to enter on the side of the connection that does the 'active close'. TIME_WAIT exists for a very good reason and so you should be careful of simply reusing addresses.

I wrote about TIME_WAIT, why it exists and what you can do about it when writing servers here on my blog: http://www.serverframework.com/asynchronousevents/2011/01/time-wait-and-its-design-implications-for-protocols-and-scalable-servers.html

In summary, if you can, change the protocol so that your clients enter TIME_WAIT.