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Andrew Purtell commented on HBASE-6496: --------------------------------------- In an earlier iteration of CPs the coprocessor host provided an environment variable like facility, so for all CPs installed on a region could share state among themselves. This was a map provided by the CP host, so all CPs installed on a region could share state. We could bring that back as a map like you suggest but shared across all Observers in a RS, perhaps one map for every class that asks for it. (So, shared across the RS but private to each CP implementation.) It could also be useful to have a controlled facility for ZK watchers anyway: * Add to RegionServerServices a facility for getting ZK watchers on demand * Add to the RegionCoprocessorEnvironment an API for getting ZK watchers from the RS, handing them back to be reaped, and dealing with freeing up dangling resources from any CP termination / unload. * Extend above facility for shared watchers, one watcher per RS for a given CP, perhaps again keyed on class name. > Example ZK based scan policy > ---------------------------- > > Key: HBASE-6496 > URL: https://issues.apache.org/jira/browse/HBASE-6496 > Project: HBase > Issue Type: Sub-task > Reporter: Lars Hofhansl > Assignee: Lars Hofhansl > Fix For: 0.96.0, 0.94.2 > > Attachments: 6496.txt > > > Provide an example of a RegionServer that listens to a ZK node to learn about > what set of KVs can safely be deleted during a compaction. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira