[horde] Sessions consuming CPU

[LALOT Dominique]

2011/11/4 Simon Wilson <simon at simonandkate.net>

> Over the last few weeks I have noticed periods of time where the virtual
> server running Horde climbs to 100% CPU utilisation. This can last for
> hours.
>
> Last time was 6 days ago, but then it did it again at 00:41am this
> morning, so I jumped into some troubleshooting.
>
> Stop httpd and the CPU drops to 0. Start it again, and within a minute or
> two it hits 100% again, and stays there.
>
> So I emptied the logs, stopped httpd, and set to monitoring it.
>
> iPhones / iPads turned off, Imp logged out.
> Started httpd.
> httpd access_log for Horde remains empty, with ZERO incoming requests.
> After about 15 seconds this time - httpd hits 100%. AT THE SAME TIME, this
> message hits the horde log:
>
> 2011-11-04T01:04:11+10:00 ERR: HORDE [imp] Server does not support TLS
> connections. [pid 22050 on line 340 of "/var/www/horde4/imp/lib/Imap.**
> php"]
>
> This message hits /var/log/horde up to 25 times per second, during which
> CPU usage remains at 100%.
>
> Still no incoming requests for httpd in httpd/access_log, or errors in
> httpd/error_log.
>
> The exact second that Horde logs that error, CPU hits 100%. Stop httpd,
> restart it, reproduce it. Did this several times over an hour, producing
> the exact same result - still ZERO http requests made of horde, 100% CPU at
> the same point the error gets logged.
>
> So I logged in to Horde, and looked in "Sessions". About 30 sessions
> sitting in there, dating back up to a week old, across iPhone, Ipad,
> Mozilla, IE.
>
> As soon as I deleted the session files from /var/lib/php/session (kicked
> me out of Horde as expected), CPU usage immediately dropped, and the IMAP
> TLS message stopped.
>
> It hasn't done it this morning since, and clearing the old sessions has
> stopped both the errors in the log and brought CPU usage down to about 3%.
>
> Is there any way I can stop this reoccurring (other than monitoring for
> 100% CPU load and triggering a session file delete!)
>
> Thanks
> Simon.
>
> --
> Simon Wilson
> M: 0400 12 11 16
>
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>

There was a bug in imp 5.0.13. For some search, IE9 is looping and leads to
100% CPU. The new version 5.0.14 should be better. You don't tell your
version..


-- 
Dominique LALOT
Ingénieur Systèmes et Réseaux
http://annuaire.univmed.fr/showuser.php?uid=lalot