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https://issues.apache.org/jira/browse/ARROW-5221?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rok Mihevc updated ARROW-5221:
------------------------------
External issue URL: https://github.com/apache/arrow/issues/21695
> Improvement the performance of class SegmentsUtil
> -------------------------------------------------
>
> Key: ARROW-5221
> URL: https://issues.apache.org/jira/browse/ARROW-5221
> Project: Apache Arrow
> Issue Type: Improvement
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Minor
>
> Improve the performance of class SegmentsUtil from two points:
> # In method allocateReuseBytes, the generated byte array should be cached
> for reuse, if the size does not exceed MAX_BYTES_LENGTH. However, the array
> is not cached if bytes.length < length, and this will lead to performance
> overhead:
>
> if (bytes == null) {
> if (length <= MAX_BYTES_LENGTH) {
> bytes = new byte[MAX_BYTES_LENGTH];
> BYTES_LOCAL.set(bytes);
> } else {
> bytes = new byte[length];
> }
> } else if (bytes.length < length) {
> bytes = new byte[length];
> }
>
> 2. To evaluate the offset, an integer is bitand with a mask to clear to low
> bits, and then shift right. The bitand is useless:
>
> ((index & BIT_BYTE_POSITION_MASK) >>> 3)
>
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