Question

Problem

In a desktop network application upon sending data to DatagramSocket sometimes the exceptiption occur:

java.net.SocketException: No buffer space available (maximum connections reached?): Datagram send failed

After this exception socket is completely unusable: it doesn’t recieve anything and send() hangs indefinitely. The reproducing test is a trivial app (create socket, bind, while (true) send();)

I can repeat this behavior in 100% of cases only on Windows when my machine goes to sleep mode and then come back in a middle of “intensive data flow”.

The questions are:

1. is this behavior normal for bsd sockets – to get unusable after an error? or it is a kind of WSA bug?
2. is there any way to “reset” faulty socket to working state or reopening socket is the only solution?
3. is it possible to distinguish such conditions from regular I/O errors (i.e. recoverable ones) after catching exception?
4. are there any general guidance/advices on when I shall reopen sockets in application (I mean: network address changed, PC sleep/wake-up and other events)

Thanks! 🙂

Answer 1

A socket is unusable after any exception at all with the exception of SocketTimeoutException.