From: Tanaka Akira <akr@...17n.org>
Date: 2004-11-27T10:56:21+09:00
Subject: Re: [ANN] Multiplexer - linear non-blocking I/O

In article <024601c4d40a$674fc8e0$6442a8c0@musicbox>,
  "Bill Kelly" <billk@cts.com> writes:

> I've always used send/recv for my socket I/O.  I *think* I don't
> have a problem with blocking, even without NONBLOCK set.  (Excepting
> rare circumstances as are possible with accept(), etc.)
>
> Does that sound right?  Or should I be seeing blocking problems
> even using send/recv ?

You'll see blocking problem with send when you send huge data.

Linux man page of send(2) says:

|       When  the message does not fit into the send buffer of the socket, send
|       normally blocks, unless the socket has been placed in non-blocking  I/O
|       mode.   In  non-blocking mode it would return EAGAIN in this case.  The
|       select(2) call may be used to determine when it  is  possible  to  send
|       more data.

Try:

require 'socket'
require 'fcntl'

server = TCPServer.new 12345

t_a = Thread.start do
  a = server.accept
  data = "foo" * 10000000
  a.send data, 0
  a.close
end

b = server.accept
b.send "b", 0
b.close

t_a.join
-- 
Tanaka Akira