[infinispan-dev] Rehashing on view changes

[Vladimir Blagojevic]

On 10-11-26 10:50 AM, Bela Ban wrote:
> Quick question: when I have a view {A,B,C,D,E,F} at time T and then
> receive 2 subsequent views within 3 seconds:
>
> - {A,B,C}
> - {A,B,C,E,F}
>
> will there be 2 rehashes / rebalancings, or 1 ? Is there a delay that
> can be configured for rebalancing on view changes ?

2 rehashes.

> The reason I'm asking is that I'm working on RELAY for JGroups, which
> will allow for distribution of data across geographically separate
> clusters, e.g. NYC={A,B,C} and SFO={D,E,F}.
>
> NYC and SFO are linked by a relay, and the global view is therefore
> {A,B,C,D,E,F}.
>
> A is responsible for establishing a global view for NYC, and D does the
> same for SFO.
>
> What happens in NYC when D crashes, or leaves is:
> - All nodes from the remote cluster are removed from the global view:
> {A,B,C}
> - E then takes over as coordinator in SFO and establishes a bridge
> cluster with A, so A now installs {A,B,C,E,F}
>
>

That idea about delay in initiating rehash is excellent! However, we 
have to be careful to include delay only for high view instability. This 
is actually on my plate https://jira.jboss.org/browse/ISPN-493

Cheers,
Vladimir