[mod_cluster-dev] Using mod_cluster for backgroud services

[Itamar Heim]

> From: Paul Ferraro [mailto:paul.ferraro at redhat.com]
...
> > I understand mod_cluster can distribute load across several jboss nodes.
> > This seems great for load balancing incoming requests, but I'm looking 
> > for
> > a solution to load balance internal system processes.
> >
> > Say I have a cluster of 4 nodes, monitoring 400 hosts and updating a
> > central database with the statistics.
> > So as a general rule, the system should
> > - Balance so each node would monitor ~100 hosts.
> > - Take each node load into consideration during load balance
> > - Prefer some affinity/stickiness
> > - Balance itself when a node goes down/up
> >
> > So all very similar to mod_cluster, only I'd like to balance internal
> > work, rather than incoming requests.
> >
> > is this something mod_cluster could help with?
>
> mod_cluster, in its present form, won't be much use here - though the
> concepts are similar.
> The above seems like it could be implemented fairly easily using JBoss
> clustering.  You would implement your workload manager as an HASingleton
> (i.e. so that only 1 node in your cluster will assume this
> responsibility at any given time).  The singleton master would
> periodically send rpcs to each slave node which would respond with their
> "load", however you want to represent this.  The
> DynamicLoadBalanceFactoryProvider from the mod_cluster code base could
> be reused here (i.e. calculating a single time decayed value from
> disparate load metrics).  The singleton master can respond to view
> changes, and inform slave nodes via rpc of new/changed workload.  It
> does not seem like this would be terribly complicated.
>
> If this is the route you want to take, you can direct any questions
> regarding JBoss clustering to the appropriate forum.
[IH] Thanks for the reply Paul.
Sounds like HASingleton would allow only a single node to run the load, but 
I would like each node to monitor ~100 hosts out of the 400 (and if that 
node fails, the other nodes should pick them up)?

[IH]
Thanks,
   Itamar