healObject() should be non-blocking to ensure
that scanner is not blocked for a long time,
this adversely affects performance of the scanner
and also affects the way usage is updated
subsequently.
This PR allows for a non-blocking behavior for
healing, dropping operations that cannot be queued
anymore.
This commit gathers MRF metrics from
all nodes in a cluster and return it to the caller. This will show information about the
number of objects in the MRF queues
waiting to be healed.