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  1. Pig
  2. PIG-3466

Race Conditions in InternalDistinctBag during proactive spill

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.11.1
    • Fix Version/s: 0.12.0
    • Component/s: None
    • Labels:
      None

      Description

      I have several jobs that use the following pattern:

      b = group a by x;
      c = foreach b {
                  dist_y = DISTINCT a.y;
                  generate
                  group,
                  COUNT(dist_y) as y_cnt;
      
      };
      

      These job fail intermittently during proactive spill when the data set is large:

      java.util.ConcurrentModificationException
              at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
              at java.util.HashMap$KeyIterator.next(HashMap.java:828)
              at java.util.AbstractCollection.toArray(AbstractCollection.java:171)
              at org.apache.pig.data.SortedSpillBag.proactive_spill(SortedSpillBag.java:77)
              at org.apache.pig.data.InternalDistinctBag.spill(InternalDistinctBag.java:464)
              at org.apache.pig.impl.util.SpillableMemoryManager.handleNotification(SpillableMemoryManager.java:274)
              at sun.management.NotificationEmitterSupport.sendNotification(NotificationEmitterSupport.java:138)
              at sun.management.MemoryImpl.createNotification(MemoryImpl.java:171)
              at sun.management.MemoryPoolImpl$PoolSensor.triggerAction(MemoryPoolImpl.java:272)
              at sun.management.Sensor.trigger(Sensor.java:120)
      

      PIG-3212 fixed the same issue for InternalSortedBag by synchronizing accesses to the content of bag. But InternalDistinctBag wasn't fixed, so the issue remains for nested DISTINCT.

        Attachments

        1. PIG-3466-1.patch
          11 kB
          Cheolsoo Park

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              • Assignee:
                cheolsoo Cheolsoo Park
                Reporter:
                cheolsoo Cheolsoo Park
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                • Created:
                  Updated:
                  Resolved: