SLUG Mailing List Archives
Re: [SLUG] Apps hanging when writing to /dev/log
- To: jeremy@xxxxxxxxxxx
- Subject: Re: [SLUG] Apps hanging when writing to /dev/log
- From: Jamie Wilkinson <jaq@xxxxxxxxxxxxxx>
- Date: Wed, 11 Feb 2009 19:07:46 +1100
- Cc: slug@xxxxxxxxxxx
Is the syslog daemon logging into /var/log/syslog that it's out of
connections? syslog can run out of file descriptors sometimes; if
it's syslog-ng it'll write "Number of allowed concurrent connections
2009/1/29 Jeremy Visser <jeremy.visser@xxxxxxxxx>:
> Since around the beginning of the month, I've been encountering a
> problem with our server (glenstorm, Ubuntu 8.04), where apps that
> attempt to write out logs to /dev/log will hang for 5 or so minutes.
> Most notably PAM gets affected, which makes ssh'ing in or using sudo a
> _very_ lengthy process. Also BIND was unresponsive, I guess anything
> that writes to the logs would have been.
> I only found out a workaround yesterday thanks to Mick Pollard (lunix),
> who suggested I use strace. Apps like sudo would connect() to /dev/log
> (which I presume is a UNIX socket), and use send() to write the actual
> log. The apps were hanging on send(), not connect().
> Eventually, I've found that this only occurs if syslogd is running.
> While an app is hanging, a `killall syslogd` will instantly un-freeze
> `fuser -u /dev/log` reveals that indeed, syslogd listens on /dev/log.
> Funny thing is, if I restart syslogd, and do things that write to the
> log, it works fine. I can see the log entries coming through in syslog,
> and it's all good. Just after a few hours, it conks out and starts
> I am not sure if the actual syslogd process is locked up, or what.
> Oh, and none of my filesystems are full. That was one of the first
> things I checked. :)
> Any idea why syslogd is behaving as such?
> SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/
> Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html