Liya Fan created ARROW-5639:
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Summary: Remove floating point computation from
BaseVariableWidthVector#getOffsetBufferValueCapacity
Key: ARROW-5639
URL: https://issues.apache.org/jira/browse/ARROW-5639
Project: Apache Arrow
Issue Type: Improvement
Components: Java
Reporter: Liya Fan
Assignee: Liya Fan
Attachments: image-2019-06-18-20-30-17-826.png
Method BaseVariableWidthVector#getOffsetBufferValueCapacity uses floating point
computation to calculate the capacity, which is not necessary.
(int) ((offsetBuffer.capacity() * 1.0) / OFFSET_WIDTH);
It is interesting to note that JIT cannot optimize away the floating point
computations:
!image-2019-06-18-20-30-17-826.png!
So this has performance penalty:
Before:
VariableWidthVectorBenchmarks.getValueCapacity avgt 5 6.570 ± 0.004 ns/op
After:
VariableWidthVectorBenchmarks.getValueCapacity avgt 5 5.787 ± 0.575 ns/op
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