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https://issues.apache.org/jira/browse/HBASE-5001?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

stack updated HBASE-5001:
-------------------------

    Fix Version/s:     (was: 0.94.0)
                   0.92.0

Committed to 0.92 too.. .makes big difference in profiler view.
                
> Improve the performance of block cache keys
> -------------------------------------------
>
>                 Key: HBASE-5001
>                 URL: https://issues.apache.org/jira/browse/HBASE-5001
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.90.4
>            Reporter: Jean-Daniel Cryans
>            Assignee: Lars Hofhansl
>            Priority: Minor
>             Fix For: 0.92.0
>
>         Attachments: 5001-0.92.txt, 5001-v1.txt, 5001-v2.txt
>
>
> Doing a pure random read test on data that's 100% block cache, I see that we 
> are spending quite some time in getBlockCacheKey:
> {quote}
> "IPC Server handler 19 on 62023" daemon prio=10 tid=0x00007fe0501ff800 
> nid=0x6c87 runnable [0x00007fe0577f6000]
>    java.lang.Thread.State: RUNNABLE
>       at java.util.Arrays.copyOf(Arrays.java:2882)
>       at 
> java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:100)
>       at 
> java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:390)
>       at java.lang.StringBuilder.append(StringBuilder.java:119)
>       at 
> org.apache.hadoop.hbase.io.hfile.HFile.getBlockCacheKey(HFile.java:457)
>       at 
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2.readBlock(HFileReaderV2.java:249)
>       at 
> org.apache.hadoop.hbase.io.hfile.HFileBlockIndex$BlockIndexReader.seekToDataBlock(HFileBlockIndex.java:209)
>       at 
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$ScannerV2.seekTo(HFileReaderV2.java:521)
>       at 
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$ScannerV2.seekTo(HFileReaderV2.java:536)
>       at 
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seekAtOrAfter(StoreFileScanner.java:178)
>       at 
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seek(StoreFileScanner.java:111)
>       at 
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seekExactly(StoreFileScanner.java:219)
>       at 
> org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:80)
>       at 
> org.apache.hadoop.hbase.regionserver.Store.getScanner(Store.java:1689)
>       at 
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:2857)
> {quote}
> Since the HFile name size is known and the offset is a long, it should be 
> possible to allocate exactly what we need. Maybe use byte[] as the key and 
> drop the separator too.

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