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Date: Sun, 15 Sep 2013 05:44:54 +0000 (UTC)
From: "stack (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12637700.1363662283437.136428.1379223894822@arcas>
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References: <JIRA.12637700.1363662283437@arcas>
Subject: [jira] [Commented] (HBASE-8143) HBase on Hadoop 2 with local short
 circuit reads (ssr) causes OOM
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    [ https://issues.apache.org/jira/browse/HBASE-8143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13767699#comment-13767699 ] 

stack commented on HBASE-8143:
------------------------------

Just saying we will have to balance this sizing amongst the different needs.  4k or 8k might work for the local block reader but might not be appropriate for something like HBASE-9535 (or any other feature we'd want to do off-heap).
                
> HBase on Hadoop 2 with local short circuit reads (ssr) causes OOM 
> ------------------------------------------------------------------
>
>                 Key: HBASE-8143
>                 URL: https://issues.apache.org/jira/browse/HBASE-8143
>             Project: HBase
>          Issue Type: Bug
>          Components: hadoop2
>    Affects Versions: 0.98.0, 0.94.7, 0.95.0
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>             Fix For: 0.98.0, 0.96.0, 0.94.13
>
>         Attachments: OpenFileTest.java
>
>
> We've run into an issue with HBase 0.94 on Hadoop2, with SSR turned on that the memory usage of the HBase process grows to 7g, on an -Xmx3g, after some time, this causes OOM for the RSs. 
> Upon further investigation, I've found out that we end up with 200 regions, each having 3-4 store files open. Under hadoop2 SSR, BlockReaderLocal allocates DirectBuffers, which is unlike HDFS 1 where there is no direct buffer allocation. 
> It seems that there is no guards against the memory used by local buffers in hdfs 2, and having a large number of open files causes multiple GB of memory to be consumed from the RS process. 
> This issue is to further investigate what is going on. Whether we can limit the memory usage in HDFS, or HBase, and/or document the setup. 
> Possible mitigation scenarios are: 
>  - Turn off SSR for Hadoop 2
>  - Ensure that there is enough unallocated memory for the RS based on expected # of store files
>  - Ensure that there is lower number of regions per region server (hence number of open files)
> Stack trace:
> {code}
> org.apache.hadoop.hbase.DroppedSnapshotException: region: IntegrationTestLoadAndVerify,yC^P\xD7\x945\xD4,1363388517630.24655343d8d356ef708732f34cfe8946.
>         at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1560)
>         at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1439)
>         at org.apache.hadoop.hbase.regionserver.HRegion.flushcache(HRegion.java:1380)
>         at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:449)
>         at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushOneForGlobalPressure(MemStoreFlusher.java:215)
>         at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.access$500(MemStoreFlusher.java:63)
>         at org.apache.hadoop.hbase.regionserver.MemStoreFlusher$FlushHandler.run(MemStoreFlusher.java:237)
>         at java.lang.Thread.run(Thread.java:662)
> Caused by: java.lang.OutOfMemoryError: Direct buffer memory
>         at java.nio.Bits.reserveMemory(Bits.java:632)
>         at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:97)
>         at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:288)
>         at org.apache.hadoop.hdfs.util.DirectBufferPool.getBuffer(DirectBufferPool.java:70)
>         at org.apache.hadoop.hdfs.BlockReaderLocal.<init>(BlockReaderLocal.java:315)
>         at org.apache.hadoop.hdfs.BlockReaderLocal.newBlockReader(BlockReaderLocal.java:208)
>         at org.apache.hadoop.hdfs.DFSClient.getLocalBlockReader(DFSClient.java:790)
>         at org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:888)
>         at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:455)
>         at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:645)
>         at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:689)
>         at java.io.DataInputStream.readFully(DataInputStream.java:178)
>         at org.apache.hadoop.hbase.io.hfile.FixedFileTrailer.readFromStream(FixedFileTrailer.java:312)
>         at org.apache.hadoop.hbase.io.hfile.HFile.pickReaderVersion(HFile.java:543)
>         at org.apache.hadoop.hbase.io.hfile.HFile.createReaderWithEncoding(HFile.java:589)
>         at org.apache.hadoop.hbase.regionserver.StoreFile$Reader.<init>(StoreFile.java:1261)
>         at org.apache.hadoop.hbase.regionserver.StoreFile.open(StoreFile.java:512)
>         at org.apache.hadoop.hbase.regionserver.StoreFile.createReader(StoreFile.java:603)
>         at org.apache.hadoop.hbase.regionserver.Store.validateStoreFile(Store.java:1568)
>         at org.apache.hadoop.hbase.regionserver.Store.commitFile(Store.java:845)
>         at org.apache.hadoop.hbase.regionserver.Store.access$500(Store.java:109)
>         at org.apache.hadoop.hbase.regionserver.Store$StoreFlusherImpl.commit(Store.java:2209)
>         at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1541)
> {code}

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