title: Proper handling of EWOULDBLOCK with polling on a non-blocking socket
body: <p>I've been working on a polling TCP daemon for some time now. Recently, I've read that non-blocking sockets can sometimes throw an EWOULDBLOCK error during a send() or recv(). My understanding is that if recv() throws an EWOULDBLOCK, this (usually) means that there's nothing to receive. But what I'm unclear on is under what circumstances send() would throw an EWOULDBLOCK, and what would be proper procedure for handling such an event?</p>
  
  <p>If send() throws an EWOULDBLOCK, should the daemon simply move on from that event, onto the next one? Using a polling interface like epoll, will a new event be fired when the descriptor becomes ready for writing?</p>