[jira] [Created] (FLINK-12335) Improvement the performance of class SegmentsUtil

[Shang Yuanchun (Jira)]

Liya Fan created FLINK-12335:
--------------------------------

             Summary: Improvement the performance of class SegmentsUtil
                 Key: FLINK-12335
                 URL: https://issues.apache.org/jira/browse/FLINK-12335
             Project: Flink
          Issue Type: Improvement
          Components: Table SQL / Runtime
            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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