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https://issues.apache.org/jira/browse/HBASE-21565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16722726#comment-16722726
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Guanghao Zhang commented on HBASE-21565:
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{quote}bq.This patch relies on HBASE-21508, and I think it's useful to port
these 2 patches to branch-2.0.
{quote}
Can you explain more about this?
And FYI [~allan163] please take a look about this for branch-2.0. Thanks.
> Delete dead server from dead server list too early leads to concurrent Server
> Crash Procedures(SCP) for a same server
> ---------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-21565
> URL: https://issues.apache.org/jira/browse/HBASE-21565
> Project: HBase
> Issue Type: Bug
> Affects Versions: 3.0.0
> Reporter: Jingyun Tian
> Assignee: Jingyun Tian
> Priority: Critical
> Attachments: HBASE-21565.master.001.patch,
> HBASE-21565.master.002.patch, HBASE-21565.master.003.patch,
> HBASE-21565.master.004.patch, HBASE-21565.master.005.patch,
> HBASE-21565.master.006.patch, HBASE-21565.master.007.patch,
> HBASE-21565.master.008.patch
>
>
> There are 2 kinds of SCP for a same server will be scheduled during cluster
> restart, one is ZK session timeout, the other one is new server report in
> will cause the stale one do fail over. The only barrier for these 2 kinds of
> SCP is check if the server is in the dead server list.
> {code}
> if (this.deadservers.isDeadServer(serverName)) {
> LOG.warn("Expiration called on {} but crash processing already in
> progress", serverName);
> return false;
> }
> {code}
> But the problem is when master finish initialization, it will delete all
> stale servers from dead server list. Thus when the SCP for ZK session timeout
> come in, the barrier is already removed.
> Here is the logs that how this problem occur.
> {code}
> 2018-12-07,11:42:37,589 INFO
> org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure: Start pid=9,
> state=RUNNABLE:SERVER_CRASH_START, hasLock=true; ServerCrashProcedure
> server=c4-hadoop-tst-st27.bj,29100,1544153846859, splitWal=true, meta=false
> 2018-12-07,11:42:58,007 INFO
> org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure: Start pid=444,
> state=RUNNABLE:SERVER_CRASH_START, hasLock=true; ServerCrashProcedure
> server=c4-hadoop-tst-st27.bj,29100,1544153846859, splitWal=true, meta=false
> {code}
> Now we can see two SCP are scheduled for the same server.
> But the first procedure is finished after the second SCP starts.
> {code}
> 2018-12-07,11:43:08,038 INFO
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor: Finished pid=9,
> state=SUCCESS, hasLock=false; ServerCrashProcedure
> server=c4-hadoop-tst-st27.bj,29100,1544153846859, splitWal=true, meta=false
> in 30.5340sec
> {code}
> Thus it will leads the problem that regions will be assigned twice.
> {code}
> 2018-12-07,12:16:33,039 WARN
> org.apache.hadoop.hbase.master.assignment.AssignmentManager: rit=OPEN,
> location=c4-hadoop-tst-st28.bj,29100,1544154149607, table=test_failover,
> region=459b3130b40caf3b8f3e1421766f4089 reported OPEN on
> server=c4-hadoop-tst-st29.bj,29100,1544154149615 but state has otherwise
> {code}
> And here we can see the server is removed from dead server list before the
> second SCP starts.
> {code}
> 2018-12-07,11:42:44,938 DEBUG org.apache.hadoop.hbase.master.DeadServer:
> Removed c4-hadoop-tst-st27.bj,29100,1544153846859 ; numProcessing=3
> {code}
> Thus we should not delete dead server from dead server list immediately.
> Patch to fix this problem will be upload later.
>
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