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https://issues.apache.org/jira/browse/HBASE-30391?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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huginn updated HBASE-30391:
---------------------------
Description:
ByteArrayOutputStream copies the entire backing array when it expands, even
though only the prefix containing written data is valid.
When a write exceeds the current capacity, checkSizeAndGrow() allocates a
larger array and copies buf.length bytes. The unused portion of the old buffer
is copied unnecessarily, increasing CPU work and temporary heap memory traffic.
The fix is to copy only pos bytes, which preserves the stream contents while
avoiding copies of unused capacity.
was:
org.apache.hadoop.hbase.io.ByteArrayOutputStream copies the entire backing
array when it expands, even though only the prefix containing written data is
valid.
When a write exceeds the current capacity, checkSizeAndGrow() allocates a
larger array and copies buf.length bytes. The unused portion of the old buffer
is copied unnecessarily, increasing CPU work and temporary heap memory traffic.
The fix is to copy only pos bytes, which preserves the stream contents while
avoiding copies of unused capacity.
> Reduce array copying when expanding ByteArrayOutputStream
> ---------------------------------------------------------
>
> Key: HBASE-30391
> URL: https://issues.apache.org/jira/browse/HBASE-30391
> Project: HBase
> Issue Type: Improvement
> Components: HFile
> Affects Versions: 2.4.11
> Reporter: huginn
> Priority: Minor
> Labels: pull-request-available
>
> ByteArrayOutputStream copies the entire backing array when it expands, even
> though only the prefix containing written data is valid.
> When a write exceeds the current capacity, checkSizeAndGrow() allocates a
> larger array and copies buf.length bytes. The unused portion of the old
> buffer is copied unnecessarily, increasing CPU work and temporary heap memory
> traffic.
> The fix is to copy only pos bytes, which preserves the stream contents while
> avoiding copies of unused capacity.
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