Question

1. What is the difference between connection and read timeout for sockets?

2. What does connection timeout set to "infinity" mean? In what situation can it remain in an infinitive loop? and what can trigger that the infinity-loop dies?

3. What does read timeout set to "infinity" mean? In what situation can it remain in an infinitive loop? and what can trigger that the infinity-loop dies?

Answer 1

These are timeout values enforced by JVM for TCP connection establishment and waiting on reading data from socket.

If the value is set to infinity, you will not wait forever. It simply means JVM doesn't have timeout and OS will be responsible for all the timeouts. However, the timeouts on OS may be really long. On some slow network, I've seen timeouts as long as 6 minutes.

Even if you set the timeout value for socket, it may not work if the timeout happens in the native code. We can reproduce the problem on Linux by connecting to a host blocked by firewall or unplugging the cable on switch.

The only safe approach to handle TCP timeout is to run the connection code in a different thread and interrupt the thread when it takes too long.