On 19 Jul 2011, at 17:39, Bela Ban wrote:



On 7/19/11 5:36 PM, Mircea Markus wrote:


I think that even if you fix this in the unit tests it still might happen in a real-life situation, i.e. start two nodes and instead of forming a cluster they'd first form two clusters and then merge.
Thinking loud about this issue: can't jgroups realise that this node wants to join and not to merge? E.g. if node B starts and wants to join cluster {A}: if B hasn't received any application level
messages than can't jgroups just assume that it definitely wants to
join, and never wants to merge?

What if you start A, then the switch goes down, then start B ? B knows
it wants to join, but doesn't see A. A and B will only see each other
when the switch comes back up.

Of course, we always strive to have regular joins, not merges, but this
cannot always be achieved.
Thinking some more this situation will be nicely solved when version(vector clock) based merging will be in place, so doesn't make too much sense to strive for joins over merges ...