Nick Dimiduk created HBASE-24526:
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             Summary: 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


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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