[Zope] Re: Performance issues - excessive object loads

[Casey Duncan]

On Tue, 8 Jun 2004 10:04:05 -0400
"Gerry Kirk" <gerry at dioceseonline.com> wrote:

> > Generally increasing the cache size is the most effective way to
> > reduce loads. Try increasing the cache to say 15000 (assuming you
> > have enough RAM on the server) and see how that affects the load
> > rate. 2000 is a relatively low setting, but that really depends on
> > the size of the ZODB. How many objects are in your ZODB? Are you
> > using ZEO? (I assume not)
> >
> showing 176000 objects

A cache size of 2000 only allows 1% of the objects to be cached at once.
15000 is much better (about 8.5%), but you could still go higher if you
have the RAM.

Since the cache is per-thread, it can sometimes be better to run fewer
threads with bigger caches. You could try lowering the number of threads
to 2 and doubling the cache size. This may be better than 4 at 15000,
but it depends heavily on your application and the load it experiences
 
> I am using ZEO with one ZEO client, running on same server.
> 
> I'll try using 15,000 cache setting. This is what I now have in my
> zope.conf:
> 
>  <zodb_db main>
>    cache-size 15000
>    <zeoclient>
>      cache-size 20000000

Try upping the client disk cache size as well. This looks like the
default (20MB) which is quite small. I would probably multiply this by
10-30x. An indication for a too small ZEO client cache is many "Cache
flip" log messages from Zope.

-Casey