[imp] Slow mailbox list from time to time

[Tornoci Laszlo]

Webmaster Extraordinaire wrote:
> I think we have the same problem up to and including the top results.  Ours is caused by enabling message preview.  We discovered the problem after I went through message by message in a mailbox, found a 2 MB message (it was an error log), removed it and the mailbox opened significantly faster.
> 
> When we switch versions back to 3.1.1 the mailbox loads quickly and with no problems.  So something changed somewhere on the way with message preview.
> 
> Erik
> 
> --- On Thu, 6/4/09, Tornoci Laszlo <torlasz at xenia.sote.hu> wrote:
>> 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's not the IMAP box. Using IMAP clients, direct access to
>> the IMAP box shows absolutely no difference.
>>
>> Access is always fine if I use the "dynamic" mode. This
>> problem appears only if using the "traditional" mode.

Hi, let me summarize the suggestions I got, and my experience with them:
1. disable Horde Alarms: it didn't help me
2. disable/limit mailbox sorting on anything other than arrival time:
    also didn't help me
3. disable preview: since I disabled it, I don't have the slowdowns, so 
I believe this is the problem. I can confirm what Erik says, I had the 
preview enabled before (with Horde/Imp 3.1.5/4.1.5) and never had a 
problem like this. So indeed something must have been changed in the 
preview code that eats system resources. I'll wait a few days, just to 
make sure I won't experience any slowdowns, and I'll report this as a bug.

					Yours: Laszlo