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https://issues.apache.org/jira/browse/HBASE-3514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992214#comment-12992214
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Dave Latham commented on HBASE-3514:
------------------------------------

{quote}
// pre-allocates the byte stream to the block size + 25%
baos = new ByteArrayOutputStream(blocksize + (blocksize / 25));
{quote}

The comments says 25%, but it looks like 4%.  Not sure which it's supposed to 
be.

> Speedup HFile.Writer append
> ---------------------------
>
>                 Key: HBASE-3514
>                 URL: https://issues.apache.org/jira/browse/HBASE-3514
>             Project: HBase
>          Issue Type: Improvement
>          Components: io
>    Affects Versions: 0.90.0
>            Reporter: Matteo Bertozzi
>            Priority: Minor
>         Attachments: HBASE-3514-append.patch, 
> HBASE-3514-metaBlock-bsearch.patch
>
>
> Remove double writes when block cache is specified, by using, only, the 
> ByteArrayDataStream.
> baos is flushed with the compress stream on finishBlock.
> On my machines HFilePerformanceEvaluation SequentialWriteBenchmark passes 
> from 4000ms to 2500ms.
> Running SequentialWriteBenchmark for 1000000 rows took 4247ms.
> Running SequentialWriteBenchmark for 1000000 rows took 4512ms.
> Running SequentialWriteBenchmark for 1000000 rows took 4498ms.
> Running SequentialWriteBenchmark for 1000000 rows took 2697ms.
> Running SequentialWriteBenchmark for 1000000 rows took 2770ms.
> Running SequentialWriteBenchmark for 1000000 rows took 2721ms.

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