[syslog-ng] Possible memleak in 3.3 HEAD

[Jakub Jankowski]

On Thu, 13 Oct 2011 15:32:27 +0200, Balazs Scheidler wrote:
> 
> > Anything else looks interesting?
> > 
> > During this run, VmRSS kept rising, from:
> > Sun Oct  9 21:44:51 CEST 2011; VmRSS:	    3804 kB
> > (...)
> > to:
> > Sun Oct  9 23:07:44 CEST 2011; VmRSS:	  445332 kB
> 
> Valgrind itself allocates memory to store the errors and warnings. Do
> you see this increase of memory usage without valgrind too?

I did, that graph I sent here earlier was exactly the VmRSS of syslog-ng
running, and as you've seen, it was rising. And it was running without
valgrind :) I wanted to test this some more, but today I've noticed something
odd.

Since upgrading to 3.3.1, there is a strange behaviour of my system: if I
reload syslog-ng, it spits out *tons* of similar messages:
Internal error, duplicate configuration elements refer to the same persistent config; name='dd_queue(d_mesg,d_mesg#0)'

As far as I can tell, this happens for every destination that was open:
$ grep '^Oct 14 00:00:03' /var/log/messages | grep -c 'dd_queue(d_mesg,d_mesg#0)' 
186 
$ grep '^Oct 14 00:00:03' /var/log/messages | grep -c 'dd_queue(d_cron,d_cron#0)'
164
$ grep '^Oct 14 00:00:03' /var/log/messages | grep -c '_errorlog#0'
62435

I'm pretty sure there are no duplicate configuration elements in my config,
especially for those "standard" ones like d_mesg or d_cron:

$ grep d_mesg /etc/syslog-ng/syslog-ng.conf
destination d_mesg { file("/var/log/messages" group("root") flush_lines(1)); };
log { source(s_sys); filter(f_default); destination(d_mesg); };
$ grep messages /etc/syslog-ng/syslog-ng.conf
destination d_mesg { file("/var/log/messages" group("root") flush_lines(1)); };
$

If there were, I'd get some errors at startup, right? Well, I don't.

But what's most peculiar, is that after such reload, VmRSS stays roughly the
same (at least it's not climbing like crazy).

> I've also read the complete log and I've found two minor leaks, both of
> which leak memory when processing SIGHUPs, I've fixed these:

I've built a package with these two patches applied, and run it on my test
system, to confirm this weird behaviour above. It still manifests.
After a clean start, until there are logs to process, I can reload syslog-ng
and there are no "Internal error" messages. As soon as I make my log relays
send some messages to this test system, and try to reload it: boom, internal
errors again.

This is very weird, I don't recall this behaviour before. I know this
description isn't the most precise one, but at this moment I had no time to
investigate more. I promise I'll dig some more during next few days.
But maybe even this much will help someone debug it.

Regards,

-- 
Jakub Jankowski|shasta at toxcorp.com|http://toxcorp.com/
GPG: FCBF F03D 9ADB B768 8B92 BB52 0341 9037 A875 942D