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stack commented on HBASE-6060: ------------------------------ bq. We are only maintaining regions and the RITS. not the regionplans Yes. I should have said that. Thanks for the explanation of OPENING. I now understand. Do you think we could get your explanation into comments in the code in any way to help those that come after? bq. ... But we cannot guarentee at what point the RS had gone down, is it after forming the regionPlan or before forming the regionplan. IF it is before forming the regionplan we are already excluding the dead servers. Hmm... ok. That means that in the patch I uploaded, the new Set of servers being processed by shutdown handler is redundant with the deadServers Set that the ServerManager is keeping up. I can simplify my patch further (if you think the way getRegionPlan works in my patch is ok). > Regions's in OPENING state from failed regionservers takes a long time to > recover > --------------------------------------------------------------------------------- > > Key: HBASE-6060 > URL: https://issues.apache.org/jira/browse/HBASE-6060 > Project: HBase > Issue Type: Bug > Components: master, regionserver > Reporter: Enis Soztutar > Assignee: rajeshbabu > Fix For: 0.96.0, 0.94.1, 0.92.3 > > Attachments: 6060-94-v3.patch, 6060-94-v4.patch, 6060-94-v4_1.patch, > 6060-94-v4_1.patch, 6060-trunk.patch, 6060-trunk.patch, 6060-trunk_2.patch, > 6060-trunk_3.patch, 6060_suggestion_based_off_v3.patch, HBASE-6060-92.patch, > HBASE-6060-94.patch > > > we have seen a pattern in tests, that the regions are stuck in OPENING state > for a very long time when the region server who is opening the region fails. > My understanding of the process: > > - master calls rs to open the region. If rs is offline, a new plan is > generated (a new rs is chosen). RegionState is set to PENDING_OPEN (only in > master memory, zk still shows OFFLINE). See HRegionServer.openRegion(), > HMaster.assign() > - RegionServer, starts opening a region, changes the state in znode. But > that znode is not ephemeral. (see ZkAssign) > - Rs transitions zk node from OFFLINE to OPENING. See > OpenRegionHandler.process() > - rs then opens the region, and changes znode from OPENING to OPENED > - when rs is killed between OPENING and OPENED states, then zk shows OPENING > state, and the master just waits for rs to change the region state, but since > rs is down, that wont happen. > - There is a AssignmentManager.TimeoutMonitor, which does exactly guard > against these kind of conditions. It periodically checks (every 10 sec by > default) the regions in transition to see whether they timedout > (hbase.master.assignment.timeoutmonitor.timeout). Default timeout is 30 min, > which explains what you and I are seeing. > - ServerShutdownHandler in Master does not reassign regions in OPENING > state, although it handles other states. > Lowering that threshold from the configuration is one option, but still I > think we can do better. > Will investigate more. -- 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