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https://issues.apache.org/jira/browse/HBASE-24526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17163209#comment-17163209
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Michael Stack commented on HBASE-24526:
---------------------------------------
Update: I've put aside trying to find the issue we saw on the RegionServer side
which we originally thought a deadlock; I cannot reproduce it after multiple
runs. Hopefully next time it happens we have enough debug in place.
The notes above [~zhangduo] are great. Hoist them out into new Pv2 Scheduling
improvements issue? I'm afraid they'll be lost in the shuffle if left deep down
here. Could include working on stuff like "It is not easy to fix since the
MasterProcedureScheduler is really really complicated...", quoting you from
HBASE-19976.
> Deadlock executing assign meta procedure
> ----------------------------------------
>
> Key: HBASE-24526
> URL: https://issues.apache.org/jira/browse/HBASE-24526
> Project: HBase
> Issue Type: Bug
> Components: proc-v2, Region Assignment
> Affects Versions: 2.3.0
> Reporter: Nick Dimiduk
> Priority: Critical
>
> I have what appears to be a deadlock while assigning meta. During recovery,
> master creates the assign procedure for meta, and immediately marks meta as
> assigned in zookeeper. It then creates the subprocedure to open meta on the
> target region. However, the PEWorker pool is full of procedures that are
> stuck, I think because their calls to update meta are going nowhere. For what
> it's worth, the balancer is running concurrently, and has calculated a plan
> size of 41.
> From the master log,
> {noformat}
> 2020-06-06 00:34:07,314 INFO
> org.apache.hadoop.hbase.master.assignment.TransitRegionStateProcedure:
> Starting pid=17802, ppid=17801,
> state=RUNNABLE:REGION_STATE_TRANSITION_GET_ASSIGN_CANDIDATE, locked=true;
> TransitRegionStateProcedure table=hbase:meta, region=1588230740, ASSIGN;
> state=OPEN, location=null; forceNewPlan=true, retain=false
> 2020-06-06 00:34:07,465 INFO
> org.apache.hadoop.hbase.zookeeper.MetaTableLocator: Setting hbase:meta
> (replicaId=0) location in ZooKeeper as
> hbasedn139.example.com,16020,1591403576247
> 2020-06-06 00:34:07,466 INFO
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor: Initialized
> subprocedures=[{pid=17803, ppid=17802, state=RUNNABLE;
> org.apache.hadoop.hbase.master.assignment.OpenRegionProcedure}]
> {noformat}
> {{pid=17803}} is not mentioned again. hbasedn139 never receives an
> {{openRegion}} RPC.
> Meanwhile, additional procedures are scheduled and picked up by workers, each
> getting "stuck". I see log lines for all 16 PEWorker threads, saying that
> they are stuck.
> {noformat}
> 2020-06-06 00:34:07,961 INFO
> org.apache.hadoop.hbase.master.procedure.MasterProcedureScheduler: Took xlock
> for pid=17804, state=RUNNABLE:REGION_STATE_TRANSITION_CLOSE;
> TransitRegionStateProcedure table=IntegrationTestBigLinkedList,
> region=54f4f6c0e921e6d25e6043cba79c09aa, REOPEN/MOVE
> 2020-06-06 00:34:07,961 INFO
> org.apache.hadoop.hbase.master.assignment.RegionStateStore: pid=17804
> updating hbase:meta row=54f4f6c0e921e6d25e6043cba79c09aa,
> regionState=CLOSING, regionLocation=hbasedn046.example.com,16020,1591402383956
> ...
> 2020-06-06 00:34:22,295 WARN
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor: Worker stuck
> PEWorker-16(pid=17804), run time 14.3340 sec
> ...
> 2020-06-06 00:34:27,295 WARN
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor: Worker stuck
> PEWorker-16(pid=17804), run time 19.3340 sec
> ...
> {noformat}
> The cluster stays in this state, with PEWorker thread stuck for upwards of 15
> minutes. Eventually master starts logging
> {noformat}
> 2020-06-06 00:50:18,033 INFO
> org.apache.hadoop.hbase.client.RpcRetryingCallerImpl: Call exception,
> tries=30, retries=31, started=970072 ms ago, cancelled=false, msg=Call queue
> is full on hbasedn139.example.com,16020,1591403576247, too many items queued
> ?, details=row
> 'IntegrationTestBigLinkedList,,1591398987965.54f4f6c0e921e6d25e6043cba79c09aa.'
> on table 'hbase:meta' at region=hbase:meta,,1.
> 1588230740, hostname=hbasedn139.example.com,16020,1591403576247, seqNum=-1,
> see https://s.apache.org/timeout
> {noformat}
> The master never recovers on its own.
> I'm not sure how common this condition might be. This popped after about 20
> total hours of running ITBLL with ServerKillingMonkey.
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