[infinispan-dev] Partial state transfer in Infinispan

[Mircea Markus]

On 17 Jun 2011, at 14:51, Bela Ban wrote:

> 
> 
> On 6/17/11 2:49 PM, Mircea Markus wrote:
> 
> 
>> Now this might sound a bit too radical but do we really need REPLICATED mode?
>> This is not fully brewed, but if e.g. we set numOwners = Integer.MAX_INTEGER the cluster is effectively in replicated mode, so can't we just drop the REPLICATION entirely? This would reduce the code size significantly...
> 
> 
> This is not the same as replicated mode. With numOwners > cluster size 
> N, we send N unicasts for updates. This is inefficient, a multicast is 
> much better here. Also, for gets, we pick a node, which might not be the 
> local node, whereas in replicated mode, we always pick the local node.
Agreed. But  DIST code can be easily changed to have the same behaviour.
> 
> Plus, we'd have to de-activate the entire rebalancing code, as it's not 
> needed in replicated mode.
If we go with the approach I suggested we can use rebalancing code to achieve replicated mode's state transfer:
- less code to maintain (i.e. all the replicated code will be removed)
- potentially faster state transfer as it will now happen from all the nodes in the cluster in parallel 
> 
> One thought though is to see if we should (internally) switch to 
> replicated mode if numOwners > cluster size. A bit dangerous though 
> because if this condition changes (e.g. more nodes are addded), we'd 
> have to switch back...
> 
> 
> -- 
> Bela Ban
> Lead JGroups / Clustering Team
> JBoss
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