From: Niklas Frykholm <niklas@...>
Date: 2005-05-25T01:30:43+09:00
Subject: UDPSocket#recvfrom is slow

The #recvfrom call in this code:

    socket = UDPSocket.new
    socket.bind(0, 12345)
    loop {puts socket.recvfrom(1000)[0]}

Runs extremely slow on my ruby (ruby 1.8.2 (2004-07-29) [i386-cygwin]), 
on the order of 2 seconds per call. I see similar problems have been 
mentioned before:

    http://www.ruby-talk.org/cgi-bin/scat.rb/ruby/ruby-talk/136959
    http://www.ruby-talk.org/cgi-bin/scat.rb/ruby/ruby-talk/143448

but no solution or diagnostic was given in the replies.

If #recvfrom is changed to #recv, the code runs at the expected (fast) 
speed, so I believe that the slow operation is the conversion of the IP 
address returned by C's recvfrom() to a network name. Apparently, on a 
(badly configured???) Windows network, this can be a really slow operation.

Is there a way of disabling this name lookup in the call to #recvfrom? 
If not, maybe one could be added in a future version of ruby.

// Niklas