java socket timeout behaviour

问题:

If I set soTimeout on java sockets what will be the behaviour in case of active peer vs passive peer. For instance if I have a readtimeout value 1 minute and having a file transfer and which takes 5 minutes will it get readtimeout exception or not ? For me its necessary to get timeout exception when connection hangs.

回答1:

The soTimeout setting explicitly affects operations that read from the socket's input stream. You can think of it as allowing the caller to define a timed block on read operations. From the Javadoc for setSoTimeout:

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid.

In the case of a passive peer, no timeout will be thrown solely due to the peer not calling read. However, if and when it does make a read call, the call must return data before the soTimeout expires, or else a SocketTimeoutException will be raised.