[imp] upgrade from IMP3 -> IMP4 : serious performance hit

[Chris J. Alexander]

No - the two new servers are strictly web servers, connecting to one of the
initial pair of boxes that has the MySQL DB.  We've seen some CPU spikes, but
nothing as bad as Monday/Tuesday when we first applied load to the situation.

We did discover a *strange* bug, that I haven't fully investigated, wherein if
someone:

a) has enabled filter_on_login
b) is directed by our load balancer to one of the 3 boxes that does *not* have
the DB on it (e.g. has to connect to mysql via TCP rather than a socket)

then the entire httpd serving that person either bus errors or segmentation
faults and they get a blank page.  If anyone has a clue on that one, I'm all
ears. We've temporarily turned filter_on_login off for everyone and 
removed the
option from the pages, until I have time to troubleshoot that one further.

I've also gone back to using PHP's gzip output handler rather than doing it
through Apache2's DEFLATE filter.  We're still seeing a *ton* of
Bus/Segmentation faults, though, so the filter_on_login thing is not the only
issue that we're facing.  I'm working as I can on getting apache to give us a
core file if at all possible.

Users are very unhappy, that they believe the new interface to be much slower
especially over dialup.  I'm still trying to sort through which of those are
legitimate complaints vs. the "it's new and I have to change...wahhhhh" folks.

I have done some rudimentary DB tuning, and continue to look at that to see if
any further can be done; the DB process is always at the top of the CPU list,
but seldom uses more than 25% now.  The backend IMAP servers are busy and
occasionally get very busy, but nothing that didn't used to happen with the
older IMP3.

Thanks again to all

CJA

Quoting Thomas Willert <thomas at willert.dk>:

> Quoting "Chris J. Alexander" <cjalexa at emory.edu>:
>
>> Just to keep the list updated - we configured two additional Sun 
>> v240 servers
>> this morning into our production mix, and are monitoring to see how 
>> this will
>> help performance.  So far so good - thanks to all who offered 
>> suggestions and
>> moral support (both equally important!)
>
> Do your two new servers also run the MySQL database, or only a webserver?
>
> Please keep us posted on your progress! Cheers!
>
> -- 
> Thomas Willert
> Petkumstrasse 19
> D - 22085 Hamburg
> GSM +49 179 7307416
>



-- 
Chris J. Alexander
404-727-8333/FAX:404-727-0817