On Fri, 12 Apr 2024 10:19:27 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java line
>> 1430:
>>
>>> 1428: cb.new_(STRING_BUILDER);
>>> 1429: cb.dup();
>>> 1430: cb.invokespecial(STRING_BUILDER, "<init>",
>>> MethodTypeDesc.ofDescriptor("()V"));
>>
>> Would there be value in initializing to a larger capacity? Given the number
>> of append calls, seems the default cap of 16 is unlikely to be sufficient.
>
> Possibly. I tried a few simple variants that initialized the `StringBuilder`
> capacity at various guesses, such as sum of constant sizes + some factor
> based on args, but across a diverse set of micros that gives both some wins
> and some regressions. Getting the estimation just right is pretty tricky,
> especially when size of the arguments are arbitrary (like for any
> String/Object arg).
What are the scenarios which had regressions?
Given the conservative growth for StringBuilder, it surprises me a bit that any
scenario would regress.
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PR Review Comment: https://git.openjdk.org/jdk/pull/18690#discussion_r1564165946
