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https://issues.apache.org/jira/browse/ARROW-5057?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17662079#comment-17662079
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Rok Mihevc commented on ARROW-5057:
-----------------------------------
This issue has been migrated to [issue
#21550|https://github.com/apache/arrow/issues/21550] on GitHub. Please see the
[migration documentation|https://github.com/apache/arrow/issues/14542] for
further details.
> [Java] allocate new buffer code doesn't release extra allocated buffer
> properly
> --------------------------------------------------------------------------------
>
> Key: ARROW-5057
> URL: https://issues.apache.org/jira/browse/ARROW-5057
> Project: Apache Arrow
> Issue Type: Bug
> Components: Java
> Affects Versions: 0.12.1
> Reporter: Hitesh Khamesra
> Priority: Major
> Labels: pull-request-available
> Time Spent: 4.5h
> Remaining Estimate: 0h
>
> [Class
> BaseValueVector|https://github.com/apache/arrow/blob/master/java/vector/src/main/java/org/apache/arrow/vector/BaseValueVector.java]
> 's method allocFixedDataAndValidityBufs on line#162 allocates a buffer in
> power of 2 size. After that, it has a code to release extra buffer. For that,
> it calculates the extra buffer from allocated size "bufferSize" but in my
> opinion, it should take original "valueCount" to find the extra buffer size.
> Here, I see a problem in line#162, where its taking "bufferSize" to find the
> extra allocated bytes. It should be "valueCount*typeWidth + valueCount/8".
> Here is an example for that. Let's take 1000 ints. Then,
> valueCount = 1000 ints
> typeWidth = 4 bytes
> validitiyBufferSize = 125 bytes
> valueBufferSize = 4000 bytes
> combinedSize(valueBufferSize + validityBufferSize) = 4128 bytes (multiple of
> 8)
> combinedSizeWith2ThePowerSize = 8192 bytes, this will be "bufferSize" at
> line#152.
> With the above calculation, this code should release
> (combinedSizeWith2ThePowerSize - combinedSize) = 4064 bytes. But, this is not
> happening.
>
>
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