linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Eli Barzilay <eli@barzilay.org>
To: linux-kernel@vger.kernel.org
Subject: Repost: Bug with select?
Date: Thu, 24 Jul 2003 01:28:10 -0400	[thread overview]
Message-ID: <16159.28266.868297.372200@mojave.cs.cornell.edu> (raw)
In-Reply-To: <16112.10166.989608.288954@mojave.cs.cornell.edu>


[This is a second post, since I didn't get any replies the first time.
It looks more like a bug now, which sounds strange for something that
common...]

When I run the following program, and block the terminal's output
(C-s), the `select' doesn't seem to have any effect, resulting in a
100% cpu usage (this is on a RH8, with 2.4.18).  I wouldn't be
surprised if I'm doing something stupid, but it does seem to work fine
on Solaris.

Is there anything wrong with this, or is this some bug?

======================================================================
#include <unistd.h>
#include <fcntl.h>
int main() {
  int flags, fd, len; fd_set writefds;
  fd = 1;
  flags = fcntl(fd, F_GETFL, 0);
  fcntl(fd, F_SETFL, flags | O_NONBLOCK);
  while (1) {
    FD_ZERO(&writefds);
    FD_SET(fd, &writefds);
    len = select(fd + 1, NULL, &writefds, NULL, NULL);
    if (!FD_ISSET(fd,&writefds)) exit(0);
    len = write(fd, "hi\n", 3);
  }
  fcntl(fd, F_SETFL, flags);
}
======================================================================

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

  reply	other threads:[~2003-07-24  5:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-06-18  8:49 Problem " Eli Barzilay
2003-07-24  5:28 ` Eli Barzilay [this message]
2003-07-25 13:41   ` Repost: Bug " Marco Roeland
2003-07-26  0:20     ` Ben Greear
2003-07-26  9:05       ` Marco Roeland
2003-07-26  0:35   ` Philippe Troin
2003-07-26 14:29     ` Eli Barzilay
2003-07-26 14:25   ` Eli Barzilay
2003-07-26 15:37     ` Marco Roeland
2003-07-27 19:29 Manfred Spraul

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=16159.28266.868297.372200@mojave.cs.cornell.edu \
    --to=eli@barzilay.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: Repost: Bug with select?' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).