From: Tanaka Akira <akr@...17n.org>
Date: 2006-05-09T12:55:39+09:00
Subject: Re: Considering Ruby For a Networking Application

In article <021f01c67317$905a5900$6442a8c0@musicbox>,
  "Bill Kelly" <billk@cts.com> writes:

> Wow.  Thanks for the details!  I'm going to have to eat my
> words on a couple recent posts where I thought ruby behaved
> identically regardless of whether just one thread or multiple
> threads existed.

As far as I know, matz found the inconsistency in
[ruby-talk:66196].  It is not intended.

> Out of curiosity, is there a technical reason why it's 
> desirable for #sysread to raise EAGAIN in this one situation?

1. In general, matz respect programmer's knowledge on POSIX.
   For example, "read(2) system call cause EAGAIN on
   non-blocking mode" in this case.  I don't think many
   programmers understand the non-blocking issue well,
   though.

2. Some application, maybe event driven system, needs
   EAGAIN.  (If no application needs EAGAIN, why POSIX has
   EAGAIN?)

However checking O_NONBLOCK before read(2) have race
condition if the fd is shared with another process.  So I
recommend other solution if possible.
-- 
Tanaka Akira