We need to make sure that leave rehash process properly handles massive and rapid node failure.

Massive failures:
JGroups detects multiple node failures and pushes up to Infinispan views that are more "volatile" than we currently assumed (only one member at the time can leave). For example, if we have view V1=

and massive failure causes

to fail, JGroups failure detection and GMS are going to install a view V2=

to surviving members. LeaveTask does not handle this scenario.

Rapid node failure:
We need to revisit how LeaveTasks are queued up and executed/canceled during rapid node failures. Do we always cancel currently running leave tasks? At what stage are we allowed to cancel it and at what stage of a leave tasks is it better to wait for a completion of a task.