Liya Fan created ARROW-5221:
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Summary: 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
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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