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not getting "load-balancing" behavior

John Klassa

2005-02-11



We're using apache 1.3.33 with tomcat 5.0.16, connected via mod_jk, on
Solaris.

What I'm observing is that "load-balancing" isn't working. We have a
couple of machines dedicated to our XML interface, and have apache
configured to hand all such requests to "loadbalancer3". In our mod_jk
configuration file, we've got:

> JkMount /xml/* loadbalancer3

Loadbalancer3 is configured as follows, in the workers.properties file:

> worker.loadbalancer3.type=lb
> worker.loadbalancer3.balanced_workers=machine-a,machine-b
> worker.loadbalancer3.sticky_session=0
> worker.loadbalancer3.sticky_sessions=0

I used both "sticky_session" and "sticky_sessions" because I've seen it
both ways, in documentation. (Which is it really?)

Anyway, I've got "lbfactor" set to 1 for both machine-a and machine-b.

Now, in operation, machine-a is getting hammered, while machine-b gets
almost no traffic at all. Machine-a typically has CPU loads in the 4.0
range, while machine-b sits idle at 0.04.

My hunch is that the bulk of the traffic is coming from a single
source, and so apache/mod_jk/something is deciding to give it over to
the same tomcat instance each time, even though it shouldn't be.
Ideally, work would be handed to machine-a and machine-b in round-robin
fashion, regardless of past history.

Any clues as to what I'm doing wrong? This is causing no shortage of
consternation in our production environment.

Thanks,
John

--
John Klassa / klassa@(protected)
Test Information Systems / Central Engineering Services
Cisco Systems / RTP / NC/ USA

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