[imp] Horde/IMP performance problems

[Jochen Roderburg]

Hello Andreas,

Thanks for many more hints about the possible problems.

Only one remark at the moment about one of the points:

>> And database traffic in general: During my unintended "public   
>> performance test" I had a situation where database connection were   
>> not all accepted by our MySQL server and I saw many warnings/errors  
>>  in the imp log with the names of the new groupware components  
>> which  we had not in use before. I got the impression that these  
>> program  parts create a lot of background activity even when they  
>> are not  really used.
>
> You have not really mentioned in your first post but from this i  
> guess  the biggest problem is the DB load?

> - You need to allow as many connections to the database as you have   
> webserver processes and maybe persistant connections could help.
>

This last one was the simple cause of the DB connection problems. I  
had increased the MaxClients on the Apache side to a higher values  
than the max_user_connections on the DB server.

OTOH there was no significant load on the DB server, only on the webserver.
I have yet to determine the real bottleneck, enough memory was  
available, CPU was more saturated. What several people noted, that  
there was a unusual high amount of system CPU used, but so far no one  
had a good idea where this could come from.

Best regards,
Jochen Roderburg