Ahh, this clarifies so far, thanks. But about how many zserver-threads would 
one need for approx. 50 concurrent connections?

>-----Original Message-----
>From: Pascal Peregrina [mailto:[EMAIL PROTECTED] 
>Sent: Tuesday, June 28, 2005 11:54 AM
>To: Germer, Carsten; zope list user
>Subject: RE: [Zope] Tweaking Zope DB- and connection parameters
>zserver-threads and pool-size should be almost the same.
>Each HTTP request from Apache to Zope uses a Connection object 
>bound to a
>Transaction object.
>As each Connection object has its own cache, then if the 
>connection pool
>size is much higher than the number of zsever threads, you could end up
>using new connections with empty cache when it's not 
>necessary... This will
>make the request response time slower (cause the connection 
>will need to get
>all objects from ZODB) and will end up using unecessary memory 
>(cause all
>connection caches will be caching objects).
>I would recommend pool-size 8 if you keep zserver-threads to 5.
>(I don't know why pool-size must be a little higher than 
>threads, but the
>default configuration is 4 threads and 7 connections, so...)
>Then try increasing the cache size, because if you have lots 
>of different
>websites, caching 500 objects will probably cause each 
>connection to often
>load objects from ZODB (cache miss). To monitor that you can 
>use Control
>Panel -> Database Management -> Main -> Cache Parameters
>For each connection, if the number of active objects hits your 
>500 limit,
>then it may be a good idea to increase it.
>But of course this will depend oh the available memory you have.
>Hope this helps.
>-----Message d'origine-----
>De : [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] la part de
>Germer, Carsten
>Envoyé : mardi 28 juin 2005 11:32
>À : zope list user
>Objet : [Zope] Tweaking Zope DB- and connection parameters
>Hello everyone,
>I'm trying to figure out what I can set all (I know) Zope Parameters to
>to get a good overall performance on our "old" live installation.
>We have a new System with upgraded Zope and the like in the making but
>untill then I'm trying to keep what is up smooth and stable.
>Machine: Dual Pentium with 4Gig Ram running on Suse Linux. Zope 2.7.2
>with Python 2.3.4 and ZMS for the Sites. There's a recent Apache 1.3.x
>in Front for caching and like 25 Sites running on the system, some very
>rarely visited some more loaded.
>While running the system with out-of-the-box-parameters at 
>times of high
>load the RAM went full, the machine started swapping and spiraling down
>so I started to set limits in Apache and Zope. I was mostly just
>Apache is set to "MaxClients 50"
>Zope.conf has set "zserver-threads 5" and 
><zodb_db main>
>    cache-size 500
>    pool-size 25
>With this settings the machine tops at load around 1.8 - 2 and no
>swapping takes place *puuh* but still users sometimes, too often for
>users taste, get to wait a minute and longer for their page. For me it
>tastes like a garbage collection or whatnot because after 5-20 minutes
>everything is fine again for an hour or two...
>- Apaches "MaxClients" is set for general limit
>- zserver-threads: How many ppl, approx., can connect with this set to
>5? Would be good to synchronize this with the apache settings somehow?
>- cache-size: This is per DB connection (pool-size) as I have 
>learned, I
>did set this down to limit memory usage
>- pool-size: number of concurrent DB-Connections as I learned. Does
>every concurrent connection have to have it's own db-connection or do N
>zserver-threads share one?
>What I'm looking for is general advice how these parameters 
>work and can
>be set for best cooperation. Or if there are other Params that I have
>missed yet ;)
>E.g. "every zserver-thread uses one db-connection and can server one
>user so for 50 concurrent users you have to set everything to 50 and
>tweak cache-size according to 'Cache Parameters' in the Zope config and
>your RAM-load behaves" Which is nonsense I bet but something like that
>would help me great time.
>Thanks in Advance for any Help! /Carsten
>Carsten Germer         Deutsches Elektronen Synchrotron 
>(Web-Office, IT)
>phone:  +49-40-8998-1661                                    
>Notkestr. 85
>web: http://wof.desy.de                                    
>22607 Hamburg
>e-mail: [EMAIL PROTECTED]                                 
>  Germany
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