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Andrew Purtell resolved HBASE-1110. ----------------------------------- Resolution: Duplicate Resolving as dup of work [~jxiang] is working on. Technically I had the idea first but it's execution that matters. :-) /cc [~stack] [~lhofhansl] > Distribute the master role to HRS after ZK integration > ------------------------------------------------------ > > Key: HBASE-1110 > URL: https://issues.apache.org/jira/browse/HBASE-1110 > Project: HBase > Issue Type: Improvement > Reporter: Andrew Purtell > > After ZK integration, the master role can be distributed out to the HRS as > group behaviors mediated by synchronization and rendezvous points in ZK. > - State sharing, for example load. > -- Load information can be shared with neighbors via ephemeral child > status znodes of a znode representing the cluster root. > -- Region servers can periodically walk the status nodes of their > neighbors. If they find themselves loaded relative to others, they can > release regions. If they find themselves less loaded relative to others, they > can be more aggressive about finding unassigned regions (see below). > - Ephemeral znodes for region ownership, e.g. > /hbase//<region>/<ephemeral-node> > -- Use a permanent child of <region> to serve as a 'dirty' flag, removed > during normal close. > - A distributed queue for region assignment. > -- When coming up, HRS can check the assignment queue for candidates. > -- HRS shutdown includes marking regions clean and moving them onto > assignment queue. > -- All/any HRS can do occasional random walks over region leases looking > for expired-dirty state (when timeout causes ZK to delete the ephemeral node > representing the lease), and can helpfully move them first to a queue (+ > barrier) for splitting then onto the assignment queue. -- This message was sent by Atlassian JIRA (v6.2#6252)