RFR: 8327791: Optimization for new BigDecimal(String) [v16]
Claes Redestad
redestad at openjdk.org
Tue Mar 26 11:20:31 UTC 2024
On Wed, 20 Mar 2024 22:56:38 GMT, Shaojin Wen <duke at openjdk.org> 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:
>
> use while instead for
I agree that a public `BigDecimal(CharSequence, ...)` constructor (or set of constructors) should be considered out of scope here. I think the bar is higher on such a change, too, but I'm not ruling out that such an addition would make the cut.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/18177#issuecomment-2020156038
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