I've been looking at the mod_loadbalancer stuff with Apache very recently with Glassfish V2, and it's worth noting the supported Apache version is 2.0.x.
If you try 2.2.x as I did, you'll get an error loading the mod_loadbalancer module with an unknown symbol 'ap_run_http_method' - because the name of this symbol has changed in Apache 2.2 :( I'm assuming the current mod_loadbalancer has been compiled against Apache 2.0.x).
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