>
> I'm not deeply familiar with the AssignmentManager. I see when we process
> split rollbacks in onRegionSplit() we only call regionOffline() on
> daughters if they are known to exist. However when processing merge
> rollbacks in the else case of onRegionMerge() we unconditionally call
> regionOffline() on the parent-being-merged. Shouldn't that likewise be
> conditional on regionStates holding a state for the parent-being-merged?
> Pardon if I've missed something.
>
>
I'm really not familiar with the merge code, but this seems plausible to
me. I see that onRegionSplit() has an early out at the top of the method,
but that will fail to evaluate if rs_a and rs_b are open and rs_p is null.
So if it's called with a code of MERGE_REVERTED, I think we could wind up
creating an offline meta entry for rs_p with no regioninfo, similar to
HBASE-16093. And that entry could wind up hiding the (still online)
daughter regions.
