On Wed, 22 May 2024 14:41:36 GMT, Scott Gibbons <[email protected]> wrote:
>> test/micro/org/openjdk/bench/java/lang/StringIndexOfHuge.java line 132:
>>
>>> 130: @Benchmark
>>> 131: public int searchHugeLargeSubstring() {
>>> 132: return dataStringHuge.indexOf("B".repeat(30) + "X" +
>>> "A".repeat(30), 74);
>>
>> .repeat() call and string concatenation shouldn't be part of the benchmark
>> (here and several other @Benchmark functions in this file) since it will
>> detract from the measurement.
>>
>> (String concatenation gets converted (by javac) into
>> StringBuilder().append().append()....append().toString())
>
> Since we're only concerned with the delta of performance, does this really
> matter? Can you suggest an alternative?
The needle really should be like the all the other strings, e.g.
`dataStringHuge` itself, generated by the setup.
As to weather it really matters; the answer is Amdahl's law. You can indeed
measure the delta, but you can't measure the speedup of just the indexOf; not
with repeat and concatenation obscuring the numbers.
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PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1613864094
