[Zope] Urgent help needed: Zope falls over under moderate loa d

[sean.upton@uniontrib.com]

Squid load balances ZEO clients using a round-robin approach.  Squid does a
name lookup using DNS or /etc/hosts, and caches those values, so when you
run Squid as an accelerator, it will round-robin between all IPs it has in
its IP cache for a given domain name.  Virtual hosting is handled using a
VHM in Zope, and a redirector in Squid (fills same role as mod_rewrite in
Apache).  With a redirector, you do not need to specify virtual in the
httpd_accel_host option, as it is ignored for rewritten URLs...  pyredir is
a very easy to modify redirector written in Python...  With Squid in front
of Zope, you can use accelerated HTTP cache managers to explicity tell Squid
cache info, along with any RAM cache managers you need...

Sean

-----Original Message-----
From: bak [mailto:kedai@kedai.com.my]
Sent: Tuesday, November 20, 2001 5:27 PM
To: Chris McDonough
Cc: zope@zope.org
Subject: Re: [Zope] Urgent help needed: Zope falls over under moderate
load


On Wednesday 21 November 2001 05:38 am, you wrote:

> The big "bang for buck" solution provider is caching.  Assuming that
> you had no problems *before* the slashdotting, that will solve your
> problem because it will cause Zope to need to serve far fewer
> requests, closer to the number of requests you normally get.  And this
> is (I assume) the outcome that you actually want.  I highly recommend
> setting up a caching proxy in front of Zope if this sort of load will
> be recurring.  It's way faster and cheaper than trying to understand
> the problem deeply.  ;-)  Most commercial sites are developed using
> this principle, AFAICT.


butting in with questions :)
with 2.3.x, RAM Cache Manager has no refresh/expire/max_age feature.  you
get 
that with 2.4.x and above only.  so that might give users stale pages.  i 
know, i've encountered it.

i *really* think that there should be a RAM Cache Manager howto/best 
approach.  i'd like to write it, but i need inormation.  i'm currently 
caching my pages, but i'm not sure i'm doing it right.  properties such as 
REQUEST variables (there's two forms available. 1- at the method's page,
2-at 
the cachemanager page), statistics (seems that the url does have some effect

on the cache hit rates), etc.  confirmation from product author/zc would 
really help.  i guess that i should really look at the source ..., and i 
will.  today.

now, for putting squid in front of zope.  how do others do this, when you 
have more than one server (using zeo).  there's the virtual parameter in 
squid, but i don't get it.  any body done this?

my solution for now is putting in caching manager, and if *really* necessary

adding in another zeo client.

thanks

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