HBASE-7703 Eventually all online snapshots fail due to Timeout at same regionserver. Online snapshot attempts would fail due to timeout because a rowlock could not be obtained. Prior to this a cancellation occurred which likely grabbed the lock without cleaning it properly. The fix here is to use nice cancel instead of interrupting cancel on failures.
hbase/branches/hbase-7290/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/snapshot/RegionServerSnapshotManager.java