What can cause a spontaneous EPIPE error without either end calling close() or crashing?
Perhaps you could try strace as described in: http://modperlbook.org/html/6-9-1-Detecting-Aborted-Connections.html
I assume that your problem is related to the one described here: http://blog.netherlabs.nl/articles/2009/01/18/the-ultimate-so_linger-page-or-why-is-my-tcp-not-reliable
Unfortunately I'm having a similar problem myself but couldn't manage to get it fixed with the given advices. However, perhaps that SO_LINGER thing works for you.
shutdown()may have been called on one of thesocket endpoints.If either side may fork and execute achild process, ensure that the
FD_CLOEXEC(close-on-exec) flag is set on thesocket file descriptor if you did notintend for it to be inherited by thechild. Otherwise the child processcould (accidentally or otherwise) bemanipulating your socket connection.
I would also check that there's no sneaky firewall in the middle. It's possible an intermediate forwarding node on the route sends an RST. The best way to track that down is of course the packet sniffer (or its GUI cousin.)