Question

I am writing a client that receives UDP datagrams from a single sender. All IO will be done in a single thread. Generally, there will either be no data, or a 30 MBit/s stream. My primary concern is in keeping latency as low as possible.

The plan is to block, waiting for data, in a loop with a short-ish timeout, so that the IO thread can be responsive to shutdown requests, etc.

I am inclined to use a blocking socket, set a timeout on it, and do a recvfrom() call. However, this seems to be much less common than a select()/poll() and recvfrom() combination on a nonblocking socket.

Given that I am only working with a single socket, it seems that the nonblocking approach is needlessly complicated. Am I missing something else? Is there a reason to prefer nonblocking sockets in this particular case?

Answer 1

If you have a dedicated thread for handling the socket then asynchronous I/O, select etc are useless. What you want is simply recvfrom(2) and handle the data as quickly as possible.

Any fancy mechanisms (epoll, libaio, etc.) won’t help you get more speed out of your application.