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https://issues.apache.org/jira/browse/HIVE-22492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16973569#comment-16973569
 ] 

Slim Bouguerra commented on HIVE-22492:
---------------------------------------

{code}
IO-Elevator-Thread-9  Blocked CPU usage on sample: 609ms
  
org.apache.hadoop.hive.llap.cache.LowLevelLrfuCachePolicy.notifyUnlock(LlapCacheableBuffer)
 LowLevelLrfuCachePolicy.java:125
  
org.apache.hadoop.hive.llap.cache.CacheContentsTracker.notifyUnlock(LlapCacheableBuffer)
 CacheContentsTracker.java:173
  
org.apache.hadoop.hive.llap.cache.LowLevelCacheImpl.unlockBuffer(LlapDataBuffer,
 boolean) LowLevelCacheImpl.java:391
  org.apache.hadoop.hive.llap.cache.LowLevelCacheImpl.decRefBuffers(List) 
LowLevelCacheImpl.java:379
  
org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.returnData(Reader$OrcEncodedColumnBatch)
 OrcEncodedDataReader.java:759
  
org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.returnData(Object) 
OrcEncodedDataReader.java:110
  
org.apache.hadoop.hive.llap.io.decode.EncodedDataConsumer.returnSourceData(EncodedColumnBatch)
 EncodedDataConsumer.java:100
  
org.apache.hadoop.hive.llap.io.decode.EncodedDataConsumer.consumeData(EncodedColumnBatch)
 EncodedDataConsumer.java:92
  org.apache.hadoop.hive.llap.io.decode.EncodedDataConsumer.consumeData(Object) 
EncodedDataConsumer.java:34
  
org.apache.hadoop.hive.ql.io.orc.encoded.EncodedReaderImpl.readEncodedColumns(int,
 StripeInformation, OrcProto$RowIndex[], List, List, boolean[], boolean[], 
Consumer) EncodedReaderImpl.java:532
  org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.performDataRead() 
OrcEncodedDataReader.java:407
  org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader$4.run() 
OrcEncodedDataReader.java:266
  org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader$4.run() 
OrcEncodedDataReader.java:263
  java.security.AccessController.doPrivileged(PrivilegedExceptionAction, 
AccessControlContext) AccessController.java (native)
  javax.security.auth.Subject.doAs(Subject, PrivilegedExceptionAction) 
Subject.java:422
  
org.apache.hadoop.security.UserGroupInformation.doAs(PrivilegedExceptionAction) 
UserGroupInformation.java:1688
  org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.callInternal() 
OrcEncodedDataReader.java:263
  org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.callInternal() 
OrcEncodedDataReader.java:110
  org.apache.tez.common.CallableWithNdc.call() CallableWithNdc.java:36
  
org.apache.hadoop.hive.llap.daemon.impl.StatsRecordingThreadPool$WrappedCallable.call()
 StatsRecordingThreadPool.java:110
  java.util.concurrent.FutureTask.run() FutureTask.java:266
  java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor$Worker) 
ThreadPoolExecutor.java:1142
  java.util.concurrent.ThreadPoolExecutor$Worker.run() 
ThreadPoolExecutor.java:617
  java.lang.Thread.run() Thread.java:745

{code}

> Amortize lock contention due to LRFU accounting
> -----------------------------------------------
>
>                 Key: HIVE-22492
>                 URL: https://issues.apache.org/jira/browse/HIVE-22492
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Slim Bouguerra
>            Assignee: Slim Bouguerra
>            Priority: Major
>
> LRFU eviction policy can be a major source of contention under high load.
> This can be see on the following profiles.
> To fix this the idea is to use a batching wrapper to amortize the locking 
> contention.
> The trick i a common way to amortize locking as explained here 
> http://www.ece.eng.wayne.edu/~sjiang/pubs/papers/ding-09-BP-Wrapper.pdf



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