[users@httpd] mod_proxy_balancer not balancing correct in combination with MAX=1

[Toon Wijnands]

I'm having a setup on Gentoo, Apache 2.2.6 with a setup that relies on
mox_proxy_balancer: Apache is the proxy and proxies request to 3 workers
(in fact, Mongrel which is a basic HTTP server).

 

Rewriting rules are in places and on normal use no issues, so I guess
the setup is correct.

 

In my testing enviroment (i.e. I have full control over de requests sent
to the setup), I experience the following:

 

Setup A:

 

    <Proxy balancer://ips.dev.test_setup.com.mongrel_cluster>

        BalancerMember http://localhost:8010

        BalancerMember http://localhost:8011

        BalancerMember http://localhost:8012

    </Proxy>

 

I request an action that takes a long time to execute (10 minutes). This
is for testing purposes. Than I fire subsequents requests with normal
execution time (< 1 second). The results are:

 

-          worker 8010 gets the first long request and starts handling
this

-          worker 8011 and 8012 get the next two requests

-          request 4 is proxied to 8010 where it has to wait for the
long request to finish before it gets served.

 

This is expected behaviour.

 

Next, I've changed the configuration to



Setup B:

 

    <Proxy balancer://ips.dev.test_setup.com.mongrel_cluster>

        BalancerMember http://localhost:8010 <http://localhost:8010/>
max=1

        BalancerMember http://localhost:8011 <http://localhost:8011/>
max=1

        BalancerMember http://localhost:8012 <http://localhost:8012/>
max=1

    </Proxy>

 

I'm repeating the experiment. The results are the same as in setup A. In
my opinion this is unexpected behaviour: 8010 gets the first long
request and while serving this, it should not get any subsequent
request. The other workers should handle the subsequent requests. (I
fire the request by hand, with a large enough interval to get a free
worker available). More-over if I look in the balancer-manager, all
workers have state Ok. I would expect to see a state Busy (or something
like that for 8010).

 

Are my assumptions correct about the effect the max parameter should
have? Any experiencing the same problems?

Effectively, I'm looking for a solution that one 'bad performance'
thread does not hurt the overall response

 

Any help greatly appreciated.

 

Regards,

Toon