[horde] Memcache issue

Michael M Slusarz slusarz at horde.org
Fri May 23 17:39:50 UTC 2014

Quoting Administrator BCS <adje at bezoekerscentrumsonsbeek.nl>:

> Quoting Arjen de Korte <arjen+horde at de-korte.org>:
>> Citeren Administrator BCS <adje at bezoekerscentrumsonsbeek.nl>:
>>> Got Horde is up and running but performance is not what it should  
>>> be. It seems I have a problem with memcache. Memcache is up and  
>>> running, I can connect to it with telnet localhost 11211, but the  
>>> stats tells me nothing is happening there.
>> First question, how many concurrent users do you have? If there is  
>> a performance issue, installing memcache is not magically going to  
>> fix that for you. In you case it might help only if you have a  
>> problem with storing/retrieving session information, but that will  
>> happen only if you have many concurrent users and are starved on  
>> I/O. And even then using native memcache sessions might be  
>> preferred over using a distributed hashtable for caching session  
>> information. Enabling the latter may even worsen the problem.
> I have only a few users, max 25 but in most cases only 3 or 4 are  
> active simultaneously. The server is a brand new 3.2Ghz Xeon  
> quadcore machine with 4Gb RAM. Apart from the  
> Horde/apache2/postfix/dovecot/clamav stuff it's only running samba  
> (only a few users as well). So it basically has nothing to do,  
> processor load is a few % at max during peak moments.
>>> When I enable Memcache server under  
>>> Configuration>Horde>Distributed Hash Table, my conf.php contains:
>>> $conf['sessionhandler']['type'] = 'Builtin';
>>> $conf['sessionhandler']['hashtable'] = true;
>>> ...
>>> $conf['hashtable']['params']['hostspec'] = array('localhost');
>>> $conf['hashtable']['params']['port'] = array('11211');
>>> $conf['hashtable']['params']['weight'] = array();
>>> $conf['hashtable']['params']['persistent'] = false;
>>> $conf['hashtable']['params']['compression'] = false;
>>> $conf['hashtable']['params']['large_items'] = true;
>>> $conf['hashtable']['driver'] = 'Memcache';
>> The above all looks good. Assuming that 'horde-memcache-stats'  
>> provide some sensible output, you can rule out that this is the  
>> problem.
> Output from horde-memcache-stats:
> horde-memcache-stats
> Server: localhost:11211 (Version: 1.4.13 - 4 thread(s))
>     Size:          0,00 MB (Max: 64,00 MB - 0% used)
>     Items:         0 (Total: 0)
>     Cache Ratio:   0 hits, 0 misses
>     Connections:   5
>     Traffic:       0,00 MB in, 0,00 MB out
> It will stay that way all day.

Then you aren't using memcache for anything.

>>> As soon as I enable memcache this way, I see some "Invalid  
>>> application" errors in Horde and I get randomly "User is not  
>>> authorized for horde" messages in the Horde log, followed by  
>>> logout. No other error messages. I set memcached logging to -vv  
>>> and see no activity at all.
>>> I suppose I do something wrong in the Horde config but after a lot  
>>> of reading and searching I got a bit lost now. Any pointers in the  
>>> right direction welcome!
>> What kind of performance issue do you have? And you do use an  
>> opcode cache, right?
> Performance is more or less acceptable, but not the response speed I  
> would expect based upon # of users, server load and server hardware.  
> It can take over 5 seconds to process a user login and switching  
> between let's say email and calendar also can take several seconds.  
> Btw all users are on a direct wired lan connection so that should  
> not be a bottleneck.

Your system is not setup correctly then.  Logins might take a second  
(or two on the most), but most other actions should be pretty darn  

Can verify that an installation of 1,000,000s of users (with 1,000s of  
concurrent users) averages response times for basic IMP actions < 100ms.


Michael Slusarz [slusarz at horde.org]

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