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https://issues.apache.org/jira/browse/HBASE-8143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13767692#comment-13767692
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stack commented on HBASE-8143:
------------------------------
There is no way of getting a direct byte buffer w/o it being counted against
the commit charge for the process? Its a pity given we are just doing
read-only.
All of this off-heap allocation will impinge in our being able to use off heap
for other purposes.
> 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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