String.replace() implementation is very poor

fvasco · October 5, 2020, 8:15am

Fixed

github.com/JetBrains/kotlin

Use StringBuilder in String.replace (2x faster)

JetBrains:master ← fvasco:string-replace

opened 05:58AM - 10 Sep 20 UTC

fvasco

+31 -7

The current `String.replace` implementation use `splitToSequence`, it is pretty …slow. I made a test project to improve `String.replace`'s performance, available here: https://github.com/fvasco/kotlin-string-replace/blob/master/src/main/kotlin/org/sample/MyBenchmark.kt Results are: ~~~ Benchmark Mode Cnt Score Error Units MyBenchmark.replaceNew thrpt 5 1412205,791 ± 12644,734 ops/s MyBenchmark.replaceOriginal thrpt 5 697439,698 ± 5664,105 ops/s MyBenchmark.replaceRegex thrpt 5 1098579,545 ± 11091,188 ops/s ~~~ The regex version is a little faster, but it can be considered in order to reduce the bytecode. The `new` version is the case-insenditive translation of the Java native version. In both version the platform implementation has been preferred in order to delegate the maintenance. Original discussion here: https://discuss.kotlinlang.org/t/string-replace-implementation-is-very-poor/19026

rho · October 5, 2020, 8:48am

Well done, Francesco!
Next improvement could be the performance of the case-insensitive String.indexOf() which is also rather poor. But that’s for another topic :).

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String.replace() implementation is very poor

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