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Date: Thu, 4 Aug 2011 12:40:18 +0100
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From: Tom Evans <tevans.uk@googlemail.com>
To: users@httpd.apache.org
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Subject: Re: [users@httpd] Load Balancing question

On Thu, Aug 4, 2011 at 2:14 AM, Jeff Poling <jpoling@moody.edu> wrote:
> Thanks. =C2=A0For whatever reason, an apachectl stop and an apachectl sta=
rt corrected the issue- the balancer-manager now reflects the config in the=
 config file
>

mod_proxy_balancer is dangerous to use when doing graceful restarts.
The state of the balancers is saved, and then re-applied, however
various things can cause the settings to be applied to a different
balancer member.

This is a long standing bug, and hence (I presume) quite hard to fix.
These bug reports describe it

https://issues.apache.org/bugzilla/show_bug.cgi?id=3D44736
https://issues.apache.org/bugzilla/show_bug.cgi?id=3D45950

The only solutions are:

1) Don't use mod_proxy_balancer. Proxy to a local instance of ha-proxy
or varnish running on localhost, and use that to manage your backends
or
2) Don't use graceful restarts.

Both suck. You'll see the bug dates back over 3 years, and there is no
intention to fix it as far as I know. At $JOB, we're stopping using
mod_proxy_balancer now, we're slowly migrating each balancer to
ha-proxy.

Cheers

Tom

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