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From Sean Alderman <salderm...@udayton.edu>
Subject Re: [users@httpd] mod proxy balancer problem/question...
Date Tue, 02 Apr 2013 20:52:22 GMT
I have proven, through my own experimentation, that removing the status=+H
from the stateful balancer's member allow normal load balancing for the
stateless proxy balancer.  Leaving the status=+H in the stateful balancer's
config causes ALL requests in the stateless balancer to route to
tccontainer1.  Reversing the balance member order under this scenario
provides consistent behaviour, e.g. ALL requests goto tccontainer1, even
though it's the 2nd balance member.  This implies to me that setting
status=+H in the sticky balancer applies also to the stateless balancer,
because tccontainer2 never receives any requests while the status=+H
resides in the config.  If taken out of the config, the stateless balancer
evenly routes requests to both tccontainer1 and 2.

The behaviour is odd and unexpected, but consistent.

FWIW, I used Apache Bench for the experimentation from multiple clients on
the stateless side of things.  Unfortunately, due to the complexity of the
stateful sessions I don't have a means to perform a test using apache
bench, I can only do a manual test through an upstream application.

Thanks for your thoughts, your attention to my question is much
appreciated! :)

On Tue, Apr 2, 2013 at 4:40 PM, Igor Cicimov <icicimov@gmail.com> wrote:

>
> On 03/04/2013 7:28 AM, "Sean Alderman" <salderman1@udayton.edu> wrote:
> >
> > Perhaps I've not explained correctly, I apologize.  The concept I was
> going for was to have two independent balancers that point to the same
> tomcat instances.
> >
> > In the webservices virtual host I would have a configuration like so:
> >
> >   ProxyPass /service-sticky/
> balancer://webservices-sticky/service-sticky/
> >   ProxyPassReverse /service-sticky/
> balancer://webservice-sticky/service-sticky/
> >
> >   ProxyPass /service-stateless/ balancer://webservices/service-stateless/
> >   ProxyPassReverse /service-stateless/
> balancer://webservices/service-stateless/
> >
> > In my config, both of the quoted Proxy balancer directives exist and are
> referenced by a virtual host for different endpoints.  I absolutely
> understand what the status=+H does, and I was hoping to use it to confine
> all requests to services requiring stateful sessions to the tomcat instance
> on tccontainer2 unless it is offline.
> >
> > What I was trying to explain is that it would appear (by using mod
> status to inspect requests sent to each balance member) that applying
> status=+H to the balance member of one Proxy balancer, makes it apply to
> both, since the address:port of the balance members are identical between
> the two balancers.  I did not expect this behaviour and was looking for
> advice to accomplish the goal of load balancing the stateless requests
> across both containers and confining the stateful requests to one in a
> highly available way.
> >
> > Does that make more sense?
> >
> Not really, the proxy's have no dependencies of each other. Change the
> load factor in the second one from 1 to 2, thats the only reason i can
> think of that one not being used. Or try different lbmethod.
>
>  >
> > On Tue, Apr 2, 2013 at 4:06 PM, Igor Cicimov <icicimov@gmail.com> wrote:
> >>
> >>
> >> On 03/04/2013 2:02 AM, "Sean Alderman" <salderman1@udayton.edu> wrote:
> >> >
> >> > Greetings,
> >> >   I am running httpd 2.2.23.0-64 with mod_proxy to load balance
> Tomcat 6.0.36.B containers.  I have encountered a somewhat strange
> situation, and I was wondering if anyone could comment and or propose an
> alternative.
> >> >
> >> > I have a case where my tomcat containers have multiple webservice
> applications deployed.  Most of the deployments are stateless, but a few of
> them require session stickiness at the proxy layer.  I am looking for ways
> to better distribute the workload of the stateless webservice calls, with
> the hope of not having to create a new tomcat container separate stateful
> and stateless sessions.  The following configuration was tested, but had
> unexpected results...
> >> >
> >> > <Proxy balancer://webservices-sticky>
> >> >     BalancerMember ajp://tccontainer2.test.udayton.edu:12002route=webservices2-sticky
> >> >     BalancerMember ajp://tccontainer1.test.udayton.edu:12002route=webservices1-sticky
status=+H
> >> >     ProxySet lbmethod=byrequests
> >> >     ProxySet stickysession=JSESSIONID
> >> > </Proxy>
> >> >
> >> > <Proxy balancer://webservices>
> >> >     BalancerMember ajp://tccontainer1.test.udayton.edu:12002loadfactor=1
route=webservices1
> >> >     BalancerMember ajp://tccontainer2.test.udayton.edu:12002loadfactor=2
route=webservices2
> >> >     ProxySet lbmethod=byrequests
> >> > </Proxy>
> >> >
> >> > What I find is that balancer://webservices never sends any requests
> to ajp://tccontainer1.test.udayton.edu:12002.
> >>
> >> Thats because it never gets used, the requests are always being served
> by the first proxy. Why do you have 2 of them?
> >>
> >>  It would appear that the status=+H applies to the BalancerMember
> object instead of balancer://webservices-sticky.
> >>
> >> Correct, it means that that balancer member is hot standby as explained
> in the documentation.
> >
> >
>

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