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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2018/01/17 06:09:00 UTC
[jira] [Commented] (HBASE-19785) System Regions on the Master is
broken by parent HBASE-19694
[ https://issues.apache.org/jira/browse/HBASE-19785?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16328309#comment-16328309 ]
stack commented on HBASE-19785:
-------------------------------
I spent more time on this. The Master-as-RegionServer needs more work. The complication is special-handling assigning hbase:meta ahead of all other regions. Master would need to have checked-in as an 'ordinary' RegionServer way early in Master startup. This complicates assign. In past we had Master start up a background thread that took care of background check-in by RegionServers but it 'escaped' our control of startup sequence.
What sort-of-works is that the Master can act as any other RegionServer. It'll be late to check in so will probably miss the initial assignments but should pick up regions the next time the balancer runs.
TODO: backup Masters carrying regions.
For Master to be true RegionServer, needs more work/refactor/thought. Meantime, I can reenable a bunch of the disabled tests above: all of TestMultiParallel if I don't stipulate system tables on Master only and half of TestRegionServerReadRequestMetrics (too lazy to figure the counts in the remainder). The TestRegionsOnMasterOptions has the three possible combinations. The system-tables-on-master only is what does not work and is disabled.
> System Regions on the Master is broken by parent HBASE-19694
> ------------------------------------------------------------
>
> Key: HBASE-19785
> URL: https://issues.apache.org/jira/browse/HBASE-19785
> Project: HBase
> Issue Type: Sub-task
> Reporter: stack
> Assignee: stack
> Priority: Major
> Fix For: 2.0.0-beta-2
>
>
> The parent issue broke our being able to host system regions only on the Master.
> This broke a few tests that depend on this ability. Two of the below actually enable system regions on the Master for the test run. The remainder is the test that make sure this works.
> TestMultiParallel
> TestRegionsOnMasterOptions
> TestRegionServerReadRequestMetrics
> Parent changed the startup order. System regions and Master-as-a-RegionServer are having issues because we wait for regionservers to check in before completing Master startup which gets interesting when Master is supposed to act like a RegionServer. Previously, Master startup was off in a background thread.
> Needs more thought but not required for beta-1.
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