[imp] Imp Performance Problem

[Registration]

> On 2014-10-29, at 17:45 , Registration <registration at portabile.net> wrote:
> 
> 
>> On 2015-03-29, at 14:10 , Arjen de Korte <arjen+horde at de-korte.org> wrote:
>> 
>> Citeren Registration <registration at portabile.net>:
>> 
>>> Dear Imp users and developers,
>>> 
>>> my problem is as follows:
>>> - Login to Horde takes 3 seconds.
>>> - Loading mails takes 7 seconds for a larger IMAP folder, and 1-2 seconds for one with only a few messages in it.
>>> - Top shows 97% CPU from php5-fpm, 3% from imap.
>> 
>> That means that performance problems are probably in php. Do you use an php opcode cache / accelerator? If so, which one?
> 
> XCache 2.0.0
> 
>> 
>>> - When messages are cached, everything gets super fast.
>>> - The loading times are probably proportional to the amount of message headers Imp loads for viewing.
>>> 
>>> My questions are:
>>> - Is this normal speed?
>> 
>> It depends. How large is a large IMAP folder? How many folders do you have?
> 
> I think that Imp caches something a few dozen messages around the currently displayed ones.
> So the IMAP folder size is not important, just that there are more than a few:
> For example, an inbox with 10 messages is loaded in a second, a view of a folder with 900 messages
> takes 6-8 seconds, and also 6-8 seconds for a folder with 20000 messages.
> 
>> 
>>> - If not, how would I systematically search for the problem?
>>> - I tried xhprof, but I can't get the part where Imp refreshes messages captured.
>>> 
>>> My config:
>>> - Debian Wheezy, Apache, php5-fpm, Dovecot, imapproxy
>> 
>> Without version numbers, there is no way for us to tell what you're actually using.
> 
> Kernel 3.2.0-4-amd64, Apache 2.2.22, PHP 5.4.39-0+deb7u1, Zend 2.4.0, XCache 2.0.0, Dovecot 2.1.7
> 
>> 
>>> - Auth using Imp using MySQL/PDO connection via sockets
>>> - Dovecot using Maildir, PAM disabled, mysql auth only
>>> - Horde caching enabled
>> 
>> Which cache backend?
>> 
>>> - everything on one host
>> 
>> If everything is on the same host, imapproxy is redundant an may even hurt performance if you have a modern IMAP server like Dovecot.
> 
> Ok, disconnected and purged it, no visible difference.
> 
>> 
>>> - standard rented server
>> 
>> I wonder what the specifications of a 'standard rented server' are. :-)
> 
> AMD Opteron 6272, 2 GB RAM, 100 GB SSD - not high end, but not stone-age either, I think
> 
>> 
>>> - everything up-to-date
>> 
>> What may be up-to-date on Debian Wheezy may still be seriously out-of-date.
> 
> I know, but no testing builds for me anymore...

I did a performance test using http://www.php-benchmark-script.com/bench.php, which resulted in ~7 seconds for my server, same time as the test on the benchmarks webpage.

The only thing I could find which could be related to this is the Horde-specific message:
FastCGI: server "/usr/lib/cgi-bin/php5-fcgi" stderr: PHP message: Cannot write Autoloader cache to backend.
I tried setting proper path permissions, but no success, the error doesn't go away.