[horde] Apache running Horde segfaults

Daniel A. Ramaley daniel.ramaley at DRAKE.EDU
Tue Apr 4 10:05:30 PDT 2006

Thanks for the response. That you are seeing similar problems with 
slightly different software (MySQL instead of PostgreSQL, slightly 
older Horde, RHEL WS instead of AS) indicates to me that it is a 
general problem, and not something peculiar to the exact configuration 
i'm working with.

So far it looks like restarting Apache every hour or so (!) would fix 
the problem for me. However, that seems a bit excessive to me. During 
peak periods the problem doesn't occur until about an hour and a half. 
This morning the server hasn't been getting hit as hard and it took 3 
1/2 hours.

As i've worked with more 64-bit systems in the last few months i've 
gotten the impression that 64-bit is just not ready for prime time. So 
it doesn't surprise me that you suspect that to be the problem.

As to what you've tried, i had noticed in mailing list archives that 
mod_perl is blamed for many segmentation fault problems. I checked my 
installation and we don't have it installed (i was kind of hoping we 
did have it; we aren't using it and if removing it would have fixed the 
problem, well that would have been nice and simple). We aren't running 
turck_mmcache, but are running eAccelerator, which does the same thing. 
I can try turning off the PHP accelerator. We might need a faster 
machine to run Horde if i do that though. And a dual processor Opteron 
is already a fairly beefy system.

Could you please check what your MaxRequestsPerChild is set to? For 
comparison, the httpd.conf section that deals with child processes at 
my installation looks like this:
    StartServers       8
    MinSpareServers    5
    MaxSpareServers   20
    ServerLimit      256
    MaxClients       128
    MaxRequestsPerChild  1024
I might try setting MaxRequestsPerChild to something extremely low and 
see if that fixes the problem. If it does and i don't have to disable 
the PHP accelerator, that would be great. I tend to think of turning 
down MaxRequestsPerChild to be a kludge similar to restarting Apache on 
a regular basis, though.

On Tuesday 04 April 2006 11:15, Ryan Novosielski wrote:
>Hey Daniel,
>To start out, I've got roughly the same configuration. I run RHEL4.3
> WS on a V20z machine. The differences are that I run Horde 3.0.10 and
> MySQL, but my problem is the same and everything else is the same,
> and I'm currently solving it by restarting Apache every once in
> awhile during peak periods. This is a solution I abhor, but I have to
> if I want to keep the machine running.
>The problem appears to be at least somewhat related the the machine
>being 64-bit. I've heard suggestions by the author of Bacula that
> there might be a gcc bug on 64-bit platforms with regard to memory
> addressing. I've also seen some evidence to indicate that 64-bit
> Linux platforms are not stable for PHP. Unfortunately, that one
> doesn't fly for me because that is the equipment I've got. I've
> considered putting 32-bit Apache on the machine, but that's a gamble
> and I do not have spare equipment to try this on.
>It might be worth noting what I've tried so far, and the results.
> First off, I've removed mod_perl; reports say that these two share
> memory improperly. I don't use mod_perl, so there's no reason for me
> to have had it installed anyway. This improved things a certain
> amount, but did not kill off the problem. Removing turck_mmcache DID
> seem to quell the problem altogether, but my machine cannot handle
> the load without the piece of software. I've seen suggestions that
> PHP accelerators are particularly susceptible to this kind of thing
> on 64-bit platforms.
>Where do we go from here? No idea really. One idea that recently came
> to me is to lower "MaxRequestsPerChild" to ensure more subserver
> turnover. Not sure what mine is set to right now. If it's unlimited,
> changing this value might stop the problem.
>It is definitely worth knowing that this IS a problem though, it's on
> a major architecture (AMD64, or at least Sun AMD64 and RHEL4). I hope
> that something can be accomplished here.
>Daniel A. Ramaley wrote:
>> Hello. I have been testing a Horde Imp webmail server for some time.
>> Yesterday it finally went live, and the amount of traffic the server
>> had to deal with increased by a couple orders of magnitude. Since
>> then there has been a major problem. After running fine for awhile
>> (where "awhile" is on the order of an hour and a half), the server
>> will start returning empty pages. When this happens, Apache's
>> error_log gets filled with lines like this:
>> [Tue Apr 04 08:07:06 2006] [notice] child pid 9954 exit signal
>> Segmentation fault (11)
>> We are using a PostgreSQL database. It continually writes messages
>> to its log (whether there is a problem or not) that look like:
>> Apr  4 08:23:17 sun12 postgres[10281]: [1-1] LOG:  unexpected EOF on
>> client connection
>> At one time i was having a problem with PostgreSQL not accepting
>> enough client connections; right now it is set to "max_connections =
>> 256". I believe the relevant line in Apache's configuration is
>> "MaxClients 128" which is clearly less than PostgreSQL's limit so it
>> shouldn't be a problem anymore.
>> Has anyone seen a problem like this? How did you fix it?
>> The server is a Sun v40z, which is a dual Opteron box with 2 GB RAM.
>> It is running Red Hat Enterprise AS 4, with these versions of the
>> Horde software and other components:
>>   Horde 3.1.1
>>   Imp 4.1
>>   Ingo 1.1
>>   Kronolith 2.1
>>   Passwd 3.0
>>   Turba 2.1
>> The Apache version is 2.0.52, with PHP 4.3.9 and PostgreSQL 7.4.8.
>> All the server runs is the web server and database; the Imap server
>> it connects to is on a different machine. We are also using ldap
>> address books, but they again are on a different machine. The Horde
>> server has plenty of CPU (about 70% idle when it is getting hit
>> hardest) and RAM (over half of the RAM is just being used by Linux
>> for caching).

Dan Ramaley                            Dial Center 118, Drake University
Network Programmer/Analyst             2407 Carpenter Ave
+1 515 271-4540                        Des Moines IA 50311 USA

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