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https://issues.apache.org/jira/browse/HBASE-14012?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-14012:
--------------------------
Attachment: 14012.txt
Small patch that looks big because we did some changes in PB.
Change name of procedure executor thread from
ProcedureExecutorThread to ProcedureExecutor (Yeah, its a thread)
SplitLogManager: clean up logging.
ServerCrashProcedure: Don't run if master is initializing and then the fix
which is collapse steps: collapsed getting of list of regions to assign
together with assign so a server crash cannot split these steps. Required regen
of protobufs to remove step and to change name of one of the persisted Lists...
its name was changed from regionsToAssign to regionsAssigned.
Trying hadoopqa to see how it does.
It is hard to add a test in here given we are removing the hole during which a
crashed master could cause harm. Would be sweet if could set up the scenario
seen in cluster testing to ensure this fix for sure nails it.
> Double Assignment and Dataloss when ServerCrashProcedure runs during Master
> failover
> ------------------------------------------------------------------------------------
>
> Key: HBASE-14012
> URL: https://issues.apache.org/jira/browse/HBASE-14012
> Project: HBase
> Issue Type: Bug
> Components: master, Region Assignment
> Affects Versions: 2.0.0, 1.2.0
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Attachments: 14012.txt
>
>
> (Rewrite to be more explicit about what the problem is)
> ITBLL. Master comes up (It is being killed every 1-5 minutes or so). It is
> joining a running cluster (all servers up except Master with most regions
> assigned out on cluster). ProcedureStore has two ServerCrashProcedures
> unfinished (RUNNABLE state) for two separate servers. One SCP is in the
> middle of the assign step when master crashes (SERVER_CRASH_ASSIGN). This SCP
> step has this comment on it:
> {code}
> // Assign may not be idempotent. SSH used to requeue the SSH if we
> got an IOE assigning
> // which is what we are mimicing here but it looks prone to double
> assignment if assign
> // fails midway. TODO: Test.
> {code}
> This issue is 1.2+ only since it is ServerCrashProcedure (Added in
> HBASE-13616, post hbase-1.1.x).
> Looking at ServerShutdownHandler, how we used to do crash processing before
> we moved over to the Pv2 framework, SSH may have (accidentally) avoided this
> issue since it does its processing in a big blob starting over if killed
> mid-crash. In particular, post-crash, SSH scans hbase:meta to find servers
> that were on the downed server. SCP scanneds Meta in one step, saves off the
> regions it finds into the ProcedureStore, and then in the next step, does
> actual assign. In this case, we crashed post-meta scan and during assign.
> Assign is a bulk assign. It mostly succeeded but got this:
> {code}
> 809622 2015-06-09 20:05:28,576 INFO [ProcedureExecutorThread-9]
> master.GeneralBulkAssigner: Failed assigning 3 regions to server
> c2021.halxg.cloudera.com,16020,1433905510696, reassigning them
> {code}
> So, most regions actually made it to new locations except for a few
> stragglers. All of the successfully assigned regions then are reassigned on
> other side of master restart when we replay the SCP assign step.
> Let me put together the scan meta and assign steps in SCP; this should do
> until we redo all of assign to run on Pv2.
> A few other things I noticed:
> In SCP, we only check if failover in first step, not for every step, which
> means ServerCrashProcedure will run if on reload it is beyond the first step.
> {code}
> // Is master fully online? If not, yield. No processing of servers unless
> master is up
> if (!services.getAssignmentManager().isFailoverCleanupDone()) {
> throwProcedureYieldException("Waiting on master failover to complete");
> }
> {code}
> This means we are assigning while Master is still coming up, a no-no (though
> it does not seem to have caused problem here). Fix.
> Also, I see that over the 8 hours of this particular log, each time the
> master crashes and comes back up, we queue a ServerCrashProcedure for c2022
> because an empty dir never gets cleaned up:
> {code}
> 39 2015-06-09 22:15:33,074 WARN [ProcedureExecutorThread-0]
> master.SplitLogManager: returning success without actually splitting and
> deleting all the log files in path
> hdfs://c2020.halxg.cloudera.com:8020/hbase/WALs/c2022.halxg.cloudera.com,16020,1433902151857-splitting
> {code}
> Fix this too.
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