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https://issues.apache.org/jira/browse/HBASE-21200?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16630724#comment-16630724
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Toshihiro Suzuki commented on HBASE-21200:
------------------------------------------
It seems like a similar issue to HBASE-15871 occurs in case of the following
steps.
1) Create a reversed store scanner.
2) Put a lot of cells that have sequenceID grater than the readPt of the
reverse scanner into memstore.
3) Call the reverse scanner.next() and in this status, a lot of cells in
memstore have sequenceID greater than the readPt of the reverse scanner because
of 2). This condition causes that seekToPreviousRow() repeatedly search cells
that are already searched.
4) Flush a memstore, and wait until 3) process finished, to update store files
in the same HStore after flushing.
I'm attaching a patch to reproduce this issue.
> Memstore flush doesn't finish because of seekToPreviousRow() in memstore
> scanner.
> ---------------------------------------------------------------------------------
>
> Key: HBASE-21200
> URL: https://issues.apache.org/jira/browse/HBASE-21200
> Project: HBase
> Issue Type: Bug
> Components: Scanners
> Reporter: dongjin2193.jeon
> Priority: Major
> Attachments: RegionServerJstack.log
>
>
> The issue of delaying memstore flush still occurs after backport hbase-15871.
> Reverse scan takes a long time to seek previous row in the memstore full of
> deleted cells.
>
> jstack :
> "MemStoreFlusher.0" #114 prio=5 os_prio=0 tid=0x00007fa3d0729000 nid=0x486a
> waiting on condition [0x00007fa3b9b6b000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000000a465fe60> (a
> java.util.concurrent.locks.ReentrantLock$NonfairSync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
> at
> java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
> at
> java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
> at
> org.apache.hadoop.hbase.regionserver.*StoreScanner.updateReaders(StoreScanner.java:695)*
> at
> org.apache.hadoop.hbase.regionserver.HStore.notifyChangedReadersObservers(HStore.java:1127)
> at
> org.apache.hadoop.hbase.regionserver.HStore.updateStorefiles(HStore.java:1106)
> at
> org.apache.hadoop.hbase.regionserver.HStore.access$600(HStore.java:130)
> at
> org.apache.hadoop.hbase.regionserver.HStore$StoreFlusherImpl.commit(HStore.java:2455)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.internalFlushCacheAndCommit(HRegion.java:2519)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:2256)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:2218)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.flushcache(HRegion.java:2110)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.flush(HRegion.java:2036)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:501)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:471)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.access$800(MemStoreFlusher.java:75)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher$FlushHandler.run(MemStoreFlusher.java:259)
> at java.lang.Thread.run(Thread.java:748)
>
> "RpcServer.FifoWFPBQ.default.handler=27,queue=0,port=16020" #65 daemon prio=5
> os_prio=0 tid=0x00007fa3e6280000 nid=0x4801 runnable [0x00007fa3bd29a000]
> java.lang.Thread.State: RUNNABLE
> at
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner.getNext(DefaultMemStore.java:780)
> at
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner.seekInSubLists(DefaultMemStore.java:826)
> - locked <0x00000000b45aa5b8> (a
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner)
> at
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner.seek(DefaultMemStore.java:818)
> - locked <0x00000000b45aa5b8> (a
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner)
> at
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner.seekToPreviousRow(DefaultMemStore.java:1000)
> - locked <0x00000000b45aa5b8> (a
> org.apache.hadoop.hbase.regionserver.DefaultMemStore$MemStoreScanner)
> at
> org.apache.hadoop.hbase.regionserver.ReversedKeyValueHeap.next(ReversedKeyValueHeap.java:136)
> at
> org.apache.hadoop.hbase.regionserver.*StoreScanner.next(StoreScanner.java:629)*
> at
> org.apache.hadoop.hbase.regionserver.KeyValueHeap.next(KeyValueHeap.java:147)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.populateResult(HRegion.java:5876)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:6027)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:5814)
> at
> org.apache.hadoop.hbase.regionserver.RSRpcServices.scan(RSRpcServices.java:2552)
> - locked <0x000000009ee8ca10> (a
> org.apache.hadoop.hbase.regionserver.ReversedRegionScannerImpl)
> at
> org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:32385)
> at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2150)
> at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:112)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:187)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:167)
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