On Thu, 25 Apr 2024 09:41:11 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> When analyzing (startup) performance of the Classfile API I found this
> opportunity to further improve `MethodTypeDescImpl::descriptorString`.
>
> Performance improves across the board in existing microbenchmarks:
>
> Name
> (descString) Cnt Base Error Test Error Unit Change
> MethodTypeDescFactories.descriptorString
> (Ljava/lang/Object;Ljava/lang/String;)I 6 55,179 ± 2,027 32,920 ± 1,189
> ns/op 1,68x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ()V 6 17,689 ± 1,871 11,060 ± 0,331 ns/op 1,60x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ([IJLjava/lang/String;Z)Ljava/util/List; 6 86,627 ± 1,646 41,035 ± 0,636
> ns/op 2,11x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ()[Ljava/lang/String; 6 18,305 ± 1,974 13,110 ± 0,089 ns/op 1,40x (p =
> 0,000*)
> * = significant
>
>
> The improvement is even more pronounced when running with `-Xint`, which is
> relevant for reducing startup overheads of early ClassFile API use:
>
> Name
> (descString) Cnt Base Error Test Error Unit Change
> MethodTypeDescFactories.descriptorString
> (Ljava/lang/Object;Ljava/lang/String;)I 6 5122,061 ± 81,335 2626,481 ±
> 101,466 ns/op 1,95x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ()V 6 3481,316 ± 258,904 1489,267 ± 15,506 ns/op 2,34x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ([IJLjava/lang/String;Z)Ljava/util/List; 6 7741,081 ± 1628,244 3281,778 ±
> 41,892 ns/op 2,36x (p = 0,000*)
> MethodTypeDescFactories.descriptorString
> ()[Ljava/lang/String; 6 3677,803 ± 63,432 1495,291 ± 8,995 ns/op
> 2,46x (p = 0,000*)
> * = significant
> ```
>
> I also applied similar approach to `MethodTypeDesc::displayDescriptor`:
> while not performance sensitive I think these are so inter-related that it
> makes sense to implement them in a similar fashion.
src/java.base/share/classes/java/lang/constant/MethodTypeDesc.java line 210:
> 208: StringBuilder sb = new StringBuilder(24).append('(');
> 209: for (int i = 0; i < count; i++) {
> 210: sb.append(parameterType(i).displayName());
Aren't you forgetting the comma?
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PR Review Comment: https://git.openjdk.org/jdk/pull/18945#discussion_r1579294651
