[syslog-ng] Interesting issue with syslog-ng 3.3

[Balazs Scheidler]

On Fri, 2011-09-02 at 13:21 +0200, Gergely Nagy wrote:
> Paul Krizak <paul.krizak at amd.com> writes:
> 
> > We had this problem at AMD.  The problem turned out to be that 
> > /dev/console was attached to a device (an iLO in our case) that went 
> > offline occasionally and would block on writes.  We fixed it by updating 
> > our syslog-ng.conf to write to the console using a pipe() directive 
> > instead of file().
> >
> > You may have something similar, especially if there are occasional 
> > messages that get routed to /dev/console (or any other pipe/device that 
> > may block).
> 
> I managed to reliably reproduce the problem, thanks to the above
> suggestion:
> 
> source s_src { system(); tcp(port(12345)); };
> destination d_xconsole { pipe("/dev/xconsole"); };
> log { source(s_src); destination(d_xconsole); };
> 
> Throwing a few thousand logs on this while there's nothing listening on
> the other end of /dev/xconsole will eventually hang syslog-ng 3.3, even
> if I use pipe() instead of file(). Emptying /dev/xconsole will, as
> expected, restore normal operation.
> 
> This used to work with previous releases, and judging by Paul's mail, it
> works with whatever version they have (which, I assume, is not 3.3).
> 
> Since I never ever use xconsole, I just removed that destination from my
> config, but the underlying bug should be fixed nevertheless (unless this
> is the expected behaviour, which I doubt).
> 

This patch fixes this issue:

commit bb0057e78b81c574f2ce677d13d23ac6df7ac057
Author: Balazs Scheidler <bazsi at balabit.hu>
Date:   Sat Sep 3 10:37:28 2011 +0200

    pipe/file destination: fixed flipped slow-flow-control state
    
    The condition to enable soft flow control was flipped between file and
    pipe destinations. Files should have had it enabled, pipe() disabled.
    
    This patch fixes that.
    
    Reported-By: Gergely Nagy <algernon at balabit.hu>
    Signed-off-by: Balazs Scheidler <bazsi at balabit.hu>


-- 
Bazsi