RFR: 8254082: AbstractStringBuilder.insert(int dstOffset, CharSequence s, int start, int end) is missing fast-path for String [v4]

[Сергей Цыпанов]

On Sat, 28 Nov 2020 21:45:25 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Looks good to me. 
>> 
>> Theoretically the refactored `getBytes(byte[], int, byte)` should have no cost, but could cause some issues in some microbenchmarks that touches this. You mentioned this was used by StringConcatHelper, so could you run the org.openjdk.bench.java.lang.StringConcat micros to check that there are no regressions?
>
>> @cl4es Could you tell me where I can look for a command to run the benchmark?
> 
> See [doc/testing.md](https://github.com/openjdk/jdk/blob/master/doc/testing.md). The [configuration](https://github.com/openjdk/jdk/blob/master/doc/testing.md#configuration) section has a pointer on how to set up and configure the JDK build with JMH, then it should be a simple matter of running `make test TEST=micro:org.openjdk.bench.java.lang.StringConcat`.

Here are the results, looks like we have no regression:
Benchmark                               (intValue)  Mode  Cnt         original           patched  Units  Units
StringConcat.concat4String                    4711  avgt   15   27.267 ± 1.231    29.938 ± 1.099  ns/op  ns/op
StringConcat.concat6String                    4711  avgt   15   39.185 ± 1.604    42.759 ± 2.564  ns/op  ns/op
StringConcat.concatConst2String               4711  avgt   15   22.345 ± 1.685    21.913 ± 1.716  ns/op  ns/op
StringConcat.concatConst4String               4711  avgt   15   32.318 ± 4.073    32.847 ± 1.082  ns/op  ns/op
StringConcat.concatConst6Object               4711  avgt   15    9.227 ± 0.146     9.999 ± 0.939  ns/op  ns/op
StringConcat.concatConst6String               4711  avgt   15   46.134 ± 2.729    44.903 ± 1.960  ns/op  ns/op
StringConcat.concatConstBoolByte              4711  avgt   15   13.117 ± 0.725    12.575 ± 0.380  ns/op  ns/op
StringConcat.concatConstInt                   4711  avgt   15   12.230 ± 0.653    11.890 ± 0.556  ns/op  ns/op
StringConcat.concatConstIntConstInt           4711  avgt   15   18.152 ± 1.317    17.722 ± 0.566  ns/op  ns/op
StringConcat.concatConstString                4711  avgt   15   12.644 ± 0.656    13.424 ± 1.400  ns/op  ns/op
StringConcat.concatConstStringConstInt        4711  avgt   15   20.836 ± 0.703    19.975 ± 0.821  ns/op  ns/op
StringConcat.concatEmptyConstInt              4711  avgt   15   10.604 ± 0.443    10.229 ± 0.219  ns/op  ns/op
StringConcat.concatEmptyConstString           4711  avgt   15    4.844 ± 0.174     4.721 ± 0.147  ns/op  ns/op
StringConcat.concatEmptyLeft                  4711  avgt   15    5.386 ± 0.190     5.314 ± 0.104  ns/op  ns/op
StringConcat.concatEmptyRight                 4711  avgt   15    5.352 ± 0.471     5.484 ± 0.354  ns/op  ns/op
StringConcat.concatMethodConstString          4711  avgt   15   11.887 ± 0.560    14.025 ± 1.522  ns/op  ns/op
StringConcat.concatMix4String                 4711  avgt   15  172.425 ± 6.868   169.658 ± 8.440  ns/op  ns/op

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PR: https://git.openjdk.java.net/jdk/pull/402