On Mon, 11 Mar 2024 20:41:25 GMT, Shaojin Wen <[email protected]> wrote:
>> The current BigDecimal(String) constructor calls String#toCharArray, which
>> has a memory allocation.
>>
>>
>> public BigDecimal(String val) {
>> this(val.toCharArray(), 0, val.length()); // allocate char[]
>> }
>>
>>
>> When the length is greater than 18, create a char[]
>>
>>
>> boolean isCompact = (len <= MAX_COMPACT_DIGITS); // 18
>> if (!isCompact) {
>> // ...
>> } else {
>> char[] coeff = new char[len]; // allocate char[]
>> // ...
>> }
>>
>>
>> This PR eliminates the two memory allocations mentioned above, resulting in
>> an approximate 60% increase in performance..
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 1. bug fix for CharBuffer catch IndexOutOfBoundsException
> 2. reorder if statement
> 3. Improve the performance of !isCompact branch
In (03
[#bb45da4d](https://github.com/openjdk/jdk/pull/18177/files/bb45da4da1c0fcd79db85dc9c1ce17b6b3dfd8a3)
) I have fixed the build error and further optimized the branch of !isCompact,
so that the performance in the BigDecimal(char[]) scenario is better than the
master version.
-Benchmark Mode Cnt Score Error
Units #master
-BigDecimals.testConstructorWithSmallCharArray avgt 15 16.488 ? 0.054
ns/op
-BigDecimals.testConstructorWithLargeCharArray avgt 15 90.583 ? 1.523
ns/op
-BigDecimals.testConstructorWithHugeCharArray avgt 15 90.683 ? 1.623
ns/op
-BigDecimals.testConstructorWithCharArray avgt 15 47.418 ? 0.473
ns/op
-BigDecimals.testConstructorWithSmallString avgt 15 19.725 ? 0.049
ns/op
-BigDecimals.testConstructorWithLargeString avgt 15 113.567 ? 1.470
ns/op
-BigDecimals.testConstructorWithHugeString avgt 15 119.712 ? 6.230
ns/op
-BigDecimals.testConstructorWithString avgt 15 67.046 ? 0.979
ns/op
+Benchmark Mode Cnt Score Error
Units (01 #61b5531b)
+BigDecimals.testConstructorWithSmallCharArray avgt 15 14.322 ? 0.063
ns/op +15.12%
+BigDecimals.testConstructorWithLargeCharArray avgt 15 74.090 ? 0.299
ns/op +22.26%
+BigDecimals.testConstructorWithHugeCharArray avgt 15 74.372 ? 0.461
ns/op +21.93%
+BigDecimals.testConstructorWithCharArray avgt 15 41.606 ? 0.284
ns/op +13.96%
+BigDecimals.testConstructorWithSmallString avgt 15 15.019 ? 0.100
ns/op +31.33%
+BigDecimals.testConstructorWithLargeString avgt 15 70.226 ? 0.240
ns/op +61.71%
+BigDecimals.testConstructorWithHugeString avgt 15 70.153 ? 0.455
ns/op +70.64%
+BigDecimals.testConstructorWithString avgt 15 40.064 ? 0.298
ns/op +67.36%
+Benchmark Mode Cnt Score Error
Units (03 #bb45da4d)
+BigDecimals.testConstructorWithSmallCharArray avgt 15 22.450 ? 0.334
ns/op -26.55%
+BigDecimals.testConstructorWithLargeCharArray avgt 15 88.087 ? 1.393
ns/op +2.83%
+BigDecimals.testConstructorWithHugeCharArray avgt 15 87.643 ? 1.081
ns/op +3.46%
+BigDecimals.testConstructorWithCharArray avgt 15 51.357 ? 2.389
ns/op -7.66%
+BigDecimals.testConstructorWithSmallString avgt 15 16.892 ? 0.377
ns/op +11.78%
+BigDecimals.testConstructorWithLargeString avgt 15 65.103 ? 0.219
ns/op +74.44%
+BigDecimals.testConstructorWithHugeString avgt 15 64.475 ? 0.464
ns/op +85.67%
+BigDecimals.testConstructorWithString avgt 15 36.582 ? 0.286
ns/op +83.27%
-------------
PR Comment: https://git.openjdk.org/jdk/pull/18177#issuecomment-1989429207
