[syslog-ng] syslog-ng 2.0.4 hang

[Geller, Sandor (IT)]

Hi,

> On Tue, 2007-07-17 at 15:20 +0100, Geller, Sandor (IT) wrote:
> > > Hi,
> > > 
> > > I've encountered a strange problem. I'm using syslog-ng 2.0.4 with
> > > a fairly basic setup, and syslog-ng hangs when it is reading from
> > > /proc/kmsg, but only right after boot and only on one of 
> my machines,
> > > which is a RHEL AS3 machine.
> > > 
> > > It is reproducible, the host hangs on every boot as every process
> > > which tries to write to /dev/log gets blocked.
> > > 
> > > Has anyone seen such behaviour?
> > 
> > Replying to myself: adding log_fetch_limit(1) for the 
> /proc/kmsg source
> > solved the issue.
> 
> Hmm... this should not be happening, the file() source does not use
> fetch_limit(), it basically forces the use of a single read 
> system call.
> (by using the LR_NOMREAD flag)
> 
> This was implemented before 1.9.11, so it's been a long time, 
> since this
> is integrated.
> 
> Are you sure this was the cause? Can you check if syslog-ng actually
> issues multiple read() system calls without checking for readability?

The output of strace showed that a read was called without a prior poll.
I've sent the configuration and the strace outputs in a private mail.

Regards,

Sandor
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