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  1. HBase
  2. HBASE-24526

Deadlock executing assign meta procedure



    • Bug
    • Status: Open
    • Critical
    • Resolution: Unresolved
    • 2.3.0
    • None
    • proc-v2, Region Assignment
    • None


      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,

      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}]

      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.

      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

      The cluster stays in this state, with PEWorker thread stuck for upwards of 15 minutes. Eventually master starts logging

      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

      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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              ndimiduk Nick Dimiduk
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