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  1. HBase
  2. HBASE-23591

Negative memStoreSizing

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: 2.2.2
    • Component/s: read replicas
    • Labels:
      None

      Description

      After a flush on the replica region the memStoreSizing becomes negative:

      2019-12-17 08:31:59,983 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Replaying flush marker action: COMMIT_FLUSH table_name: "IntegrationTestRegionReplicaReplicati
      on" encoded_region_name: "544affde3e027454f67c8ea46c8f69ee" flush_sequence_number: 41392 store_flushes { family_name: "f1" store_home_dir: "f1" flush_output: "3c48a23eac784a348a18e10e337d80a2" } store_flushes { family_name: "f2" store_home_dir: "f2" flush_output: "9a5283ec95694667b4ead2398af5f01e" } store_flushes { family_name: "f3" store_home_dir: "f3" flush_output: "e6f25e6b0eca4d22af15d0626d0f8759" } region_name: "IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697.544affde3e027454f67c8ea46c8f69ee."
      2019-12-17 08:31:59,984 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Received a flush commit marker with seqId:41392 and a previous prepared snapshot was found
      2019-12-17 08:31:59,993 INFO org.apache.hadoop.hbase.regionserver.HStore: Region: 0beaae111b0f6e98bfde31ba35be5408 added hdfs://replica-1:8020/hbase/data/default/IntegrationTestRegionReplicaReplication/544affde3e027454f67c8ea46c8f69ee/f1/3c48a23eac784a348a18e10e337d80a2, entries=32445, sequenceid=41392, filesize=27.6 M
      2019-12-17 08:32:00,016 INFO org.apache.hadoop.hbase.regionserver.HStore: Region: 0beaae111b0f6e98bfde31ba35be5408 added hdfs://replica-1:8020/hbase/data/default/IntegrationTestRegionReplicaReplication/544affde3e027454f67c8ea46c8f69ee/f2/9a5283ec95694667b4ead2398af5f01e, entries=12264, sequenceid=41392, filesize=10.9 M
      2019-12-17 08:32:00,121 INFO org.apache.hadoop.hbase.regionserver.HStore: Region: 0beaae111b0f6e98bfde31ba35be5408 added hdfs://replica-1:8020/hbase/data/default/IntegrationTestRegionReplicaReplication/544affde3e027454f67c8ea46c8f69ee/f3/e6f25e6b0eca4d22af15d0626d0f8759, entries=32379, sequenceid=41392, filesize=27.5 M
      2019-12-17 08:32:00,122 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: CustomLog decrMemStoreSize. Current: dataSize=135810071, getHeapSize=148400960, getOffHeapSize=0, getCellsCount=167243 delta: dataSizeDelta=155923644, heapSizeDelta=170112320, offHeapSizeDelta=0, cellsCountDelta=188399
      2019-12-17 08:32:00,122 ERROR org.apache.hadoop.hbase.regionserver.HRegion: Asked to modify this region's (IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697_0001.0beaae111b0f6e98bfde31ba35be54
      08.) memStoreSizing to a negative value which is incorrect. Current memStoreSizing=135810071, delta=-155923644
      java.lang.Exception
              at org.apache.hadoop.hbase.regionserver.HRegion.checkNegativeMemStoreDataSize(HRegion.java:1323)
              at org.apache.hadoop.hbase.regionserver.HRegion.decrMemStoreSize(HRegion.java:1316)
              at org.apache.hadoop.hbase.regionserver.HRegion.decrMemStoreSize(HRegion.java:1303)
              at org.apache.hadoop.hbase.regionserver.HRegion.replayWALFlushCommitMarker(HRegion.java:5194)
              at org.apache.hadoop.hbase.regionserver.HRegion.replayWALFlushMarker(HRegion.java:5025)
              at org.apache.hadoop.hbase.regionserver.RSRpcServices.doReplayBatchOp(RSRpcServices.java:1143)
              at org.apache.hadoop.hbase.regionserver.RSRpcServices.replay(RSRpcServices.java:2232)
              at org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos$AdminService$2.callBlockingMethod(AdminProtos.java:29754)
              at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:413)
              at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:133)
              at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:338)
              at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:318)
      
      

      I added some custom logging to the snapshot logic to be able to see snapshot sizes: 

      2019-12-17 08:31:56,900 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Replaying flush marker action: START_FLUSH table_name: "IntegrationTestRegionReplicaReplication" encoded_region_name: "544affde3e027454f67c8ea46c8f69ee" flush_sequence_number: 41392 store_flushes { family_name: "f1" store_home_dir: "f1" } store_flushes { family_name: "f2" store_home_dir: "f2" } store_flushes { family_name: "f3" store_home_dir: "f3" } region_name: "IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697.544affde3e027454f67c8ea46c8f69ee."
      2019-12-17 08:31:56,900 INFO org.apache.hadoop.hbase.regionserver.HRegion: Flushing 0beaae111b0f6e98bfde31ba35be5408 3/3 column families, dataSize=126.49 MB heapSize=138.24 MB
      2019-12-17 08:31:56,900 WARN org.apache.hadoop.hbase.regionserver.DefaultMemStore: Snapshot called again without clearing previous. Doing nothing. Another ongoing flush or did we fail last attempt?
      2019-12-17 08:31:56,900 DEBUG org.apache.hadoop.hbase.regionserver.DefaultMemStore: CustomLog snapshot for region: {ENCODED => 0beaae111b0f6e98bfde31ba35be5408, NAME => 'IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697_0001.0beaae111b0f6e98bfde31ba35be5408.', STARTKEY => 'bbbbbbbb', ENDKEY => 'cccccccc', REPLICA_ID => 1} memstore: dataSize=41660529, getHeapSize=45422304, getOffHeapSize=0, getCellsCount=49951
      2019-12-17 08:31:56,901 DEBUG org.apache.hadoop.hbase.regionserver.DefaultMemStore: CustomLog snapshot for region: {ENCODED => 0beaae111b0f6e98bfde31ba35be5408, NAME => 'IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697_0001.0beaae111b0f6e98bfde31ba35be5408.', STARTKEY => 'bbbbbbbb', ENDKEY => 'cccccccc', REPLICA_ID => 1} memstore: dataSize=72246315, getHeapSize=78890240, getOffHeapSize=0, getCellsCount=88222
      2019-12-17 08:31:56,901 WARN org.apache.hadoop.hbase.regionserver.DefaultMemStore: Snapshot called again without clearing previous. Doing nothing. Another ongoing flush or did we fail last attempt?
      2019-12-17 08:31:56,901 DEBUG org.apache.hadoop.hbase.regionserver.DefaultMemStore: CustomLog snapshot for region: {ENCODED => 0beaae111b0f6e98bfde31ba35be5408, NAME => 'IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697_0001.0beaae111b0f6e98bfde31ba35be5408.', STARTKEY => 'bbbbbbbb', ENDKEY => 'cccccccc', REPLICA_ID => 1} memstore: dataSize=42016800, getHeapSize=45799776, getOffHeapSize=0, getCellsCount=50226
      2019-12-17 08:31:56,901 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 :  Prepared flush with seqId:41392
      
      

      This shows that snapshots combined size is actually bigger than the region's memStoreSizing. So when do we decrease memStoreSizing without actually flushing?

      A bit earlier in the log I found this:

      2019-12-17 08:31:43,581 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Replaying flush marker action: START_FLUSH table_name: "IntegrationTestRegionReplicaReplication" encoded_region_name: "544affde3e027454f67c8ea46c8f69ee" flush_sequence_number: 40445 store_flushes { family_name: "f2" store_home_dir: "f2" } region_name: "IntegrationTestRegionReplicaReplication,bbbbbb
      bb,1576599911697.544affde3e027454f67c8ea46c8f69ee."
      2019-12-17 08:31:43,582 WARN org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Received a flush prepare marker with a larger seqId: 40445 before clearing the previous one with seqId: 20747. Ignoring
      2019-12-17 08:31:43,582 TRACE org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Store files for region: 
      2019-12-17 08:31:43,582 INFO org.apache.hadoop.hbase.regionserver.HRegion: writing data to region IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697_0001.0beaae111b0f6e98bfde31ba35be5408. with WAL disabled. Data may be lost in the event of a crash.
      2019-12-17 08:31:43,586 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Replaying flush marker action: COMMIT_FLUSH table_name: "IntegrationTestRegionReplicaReplication" encoded_region_name: "544affde3e027454f67c8ea46c8f69ee" flush_sequence_number: 40445 store_flushes { family_name: "f2" store_home_dir: "f2" flush_output: "3f6a5302b36a4a65a6caa291a03f108d" } region_name: "IntegrationTestRegionReplicaReplication,bbbbbbbb,1576599911697.544affde3e027454f67c8ea46c8f69ee."
      2019-12-17 08:31:43,586 WARN org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Received a flush commit marker with larger seqId: 40445 than what we have prepared with seqId: 
      20747. Picking up new file and dropping prepared memstore snapshot
      2019-12-17 08:31:43,587 WARN org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Unexpected: flush commit marker received from store f2 but no associated flush context. Ignoring
      2019-12-17 08:31:43,587 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: CustomLog decrMemStoreSize. Current: dataSize=184492444, getHeapSize=201769960, getOffHeapSize=0, getCellsCount=229450 delta: dataSizeDelta=83677329, heapSizeDelta=91222080, offHeapSizeDelta=0, cellsCountDelta=100177
      2019-12-17 08:31:43,587 INFO org.apache.hadoop.hbase.regionserver.HRegion: 0beaae111b0f6e98bfde31ba35be5408 : Not dropping memstore contents since replayed flush seqId: 40445 is smaller than current seqId:40481
      
      

      Based on this the issues seems to originate from HRegion.replayFlushInStores. The StoreFlushContext is missing, we show a warning and continue the execution with the next StoreFlushDescriptor without actually flushing the snapshot in question. However replayWALFlushCommitMarker is unaware of the warn and continues assuming the flush was successful and decreasing the memStoreSizing (and doing cleanup).

       

      We should consider decreasing the memStoreSizing on a per store level instead of on the region level and do the negativity check before we do it, potentially preventing a flush if needed, to make sure we keep the memStoreSizing positive.

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            • Assignee:
              Unassigned
              Reporter:
              bszabolcs Szabolcs Bukros
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              • Created:
                Updated: