[imp] Slow mailbox list from time to time

[Michael M Slusarz]

Quoting Tornoci Laszlo <torlasz at xenia.sote.hu>:

> lst_hoe02 at kwsoft.de wrote:
>> Zitat von Tornoci Laszlo <torlasz at xenia.sote.hu>:
>>
>>> Hi,
>>>
>>> I have a Horde/IMP system that behaves strangely since I upgraded  
>>> from 3.1.5/4.1.5 to 3.3.4/4.3.4. I have about 400 users with 50-70  
>>> concurrent sessions usually. The IMAP mailstore (Cyrus) and the  
>>> MTA are on separate boxes. The system is dual Xeon (quad core)  
>>> 2GHz, 2GB RAM.
>>>
>>> We had excellent response times before the upgrade. The problem  
>>> is, we still have excellent response times (practically  
>>> instantaneous mailbox lists with > 3000 mails in one folder) most  
>>> of the time, BUT sometimes for long periods of time, I get  
>>> miserable response times (30-80 sec waiting) for the same large  
>>> mailbox to be listed. "top" show the http process to shoot up to  
>>> 100% cpu while waiting, but nothing else remarkable. Restarting  
>>> http or mysqld doesn't help. Logging in is not slow. The larger a  
>>> mailbox, the worse the problem is.
>>> After some time, response times get back to normal.
>>
>> It *may* be Horde Alarms. As far as i remember there was a problem  
>> with the way Horde Alarms uses the Database in some configurations  
>> but i can't remember for sure. This could explain why you see it  
>> only occasionally. Another point to check is if you are using a PHP  
>> accelerator which do maintenance at the slow times.
>
> Thanks for the tip, I've disabled the alarms, I'll see if it makes  
> any difference. I don't use any PHP accelerators (by the way: are  
> there any reliable ones that are free?)

You may also want to look at the discussion on the horde list.  In  
short: sorting by anything other than arrival time on large mailboxes,  
if using an IMAP server that doesn't cache message data, will kill  
your server.  So either upgrade your IMAP server or lock sort on  
arrival time (or set the pref to lock sorting to arrival time when a  
certain number of messages are reached).

michael

-- 
___________________________________
Michael Slusarz [slusarz at horde.org]