[pmwiki-users] Server open file count growing

[Doug Carter]

On Thu, Jun 08, 2006 at 01:34:22PM -0500, Patrick R. Michaud wrote:
>On Thu, Jun 08, 2006 at 11:06:50AM -0500, Doug Carter wrote:
>> Context:
>>  pmwiki 2.1.6 using Farms, "neutral" skin, no cookbook items
>>  PHP 4.4.1
>>  OpenBSD 3.9 with default chrooted Apache 1.3
>> 
>> On the surface pmwiki seems to be working perfectly (and is much
>> appreciated by the former Sharepoint user base :)
>
>Excellent!
>
>> I have a problem that manifests itself as a growing list of files
>> kept open by Apache (user www on my system) that seems to be
>> driven by pmwiki editing.
>> 
>> I can restart Apache and then count the number of open files that
>> it owns (fstat -u www|wc) and I see about 85 open files.  This
>> seems quite normal as each of the ten initial httpd daemons opens
>> various files when they initialize.
>> 
>> After operating for about a week (with very moderate usage) this
>> count grew to about 1,300 open files and I started getting errors
>> from other applications complaining about lack of file
>> descriptors.
>> 
>> I restarted Apache and over the last week I have watched the open
>> file count slowly grow.  After a bunch of editing of pages this
>> morning the count grew by about 100 files; it is now at 437 open
>> files.
>
>Hmmm.  I just double-checked all of the fopen() calls in PmWiki
>to make sure they're being properly closed, and as far as I can
>tell they are.  The only one that is a little questionable
>is the .flock file (and it's entirely possible that this is the
>culprit).  And of course, there are other PHP functions which
>might be allocating file descriptors and not releasing them --
>I haven't checked yet.
>
>I should note in passing that I've had trouble in the past with
>Apache and PHP not properly closing and unlocking files.
>
>Is there any way that you could find out *which files* the httpd
>daemons are holding open?  Perhaps something in the /proc filesystem
>could tell us?  On my linux boxes, the following bash command will 
>tell me the number of file descriptors currently held by each process:

It turns out that of the 492 open fd's by httpd's that 361 are to
/var/www/logs/ssl_scache.db.  

I failed to mention that all access to the WiKi is via SSL.  I'm
currently searching for SSL related issues...


>What's the setting for MaxRequestsPerChild in Apache?

MaxRequestsPerChild = 0

>If it's zero, then one workaround might be to set 
>MaxRequestsPerChild so that Apache child processes eventually 
>exit (thus freeing up any leaked file descriptors).  But
>I'd still prefer to see if we can find out what is holding
>open files.

Me too... At this point I'm guessing that I'm chasing an
Apache/SSL issue that happens to get exercised by heavy editing
in the WiKi, but....

---end quoted text---

-- 
Doug Carter
+1 (918) 742-4141