[infinispan-dev] ISPN-30: DIST cache mode
Manik Surtani
manik at jboss.org
Thu Apr 16 05:26:03 EDT 2009
On 16 Apr 2009, at 08:02, Bela Ban wrote:
> Thinking more about the wait time, this might be problematic:
>
> * V1={A,B,C,D}
> * K maps to C and D, repl-count=2
> * V2={A,B,C}
> * V3={A,B}
> * If C and D crashed (say within 10 seconds), then we need to
> rebalance K immediately upon receiving V2 because repl-count < 2
>
> Why not handle views immediately and rebalance elements ? We can
> always think of optimizations later...
That is true - we need to think about shrinking clusters as well as
growing ones.
> Rebalancing should occur a lot when starting the cluster, but at
> this time, we don't have many elements in the cache anyway. During
> operation, views should be infrequent. And, if we pick a good
> consistent hashing algorithm, rehashing should only affect 1/N of
> all elements anyway.
Yes.
> And remember: at the JGroups level, we can bundle views (= process
> multiple LEAVE or JOIN requests together and generate only 1 view)
> with GMS.view_bundling, this might help reducing churn without any
> code changes, at least for the moment.
That's a good point.
Ok, I'll focus on immediate rehashing for now, and we'll look at wait
times as an optimisation.
Cheers
--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org
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