On Wed, 14 Apr 2021 19:54:26 GMT, Florent Guillaume <github.com+592810+e...@openjdk.org> wrote:
>> While JDK-8148937 improved StringJoiner class by replacing internal use of >> getChars that copies out characters from String elements into a char[] array >> with StringBuilder which is somehow more optimal, the improvement was >> marginal in speed (0% ... 10%) and mainly for smaller strings, while GC was >> reduced by about 50% in average per operation. >> Initial attempt to tackle that issue was more involved, but was later >> discarded because it was apparently using too much internal String details >> in code that lives outside String and outside java.lang package. >> But there is another way to package such "intimate" code - we can put it >> into String itself and just call it from StringJoiner. >> This PR is an attempt at doing just that. It introduces new package-private >> method in `java.lang.String` which is then used from both pubic static >> `String.join` methods as well as from `java.util.StringJoiner` (via >> SharedSecrets). The improvements can be seen by running the following JMH >> benchmark: >> >> https://gist.github.com/plevart/86ac7fc6d4541dbc08256cde544019ce >> >> The comparative results are here: >> >> https://jmh.morethan.io/?gist=7eb421cf7982456a2962269137f71c15 >> >> The jmh-result.json files are here: >> >> https://gist.github.com/plevart/7eb421cf7982456a2962269137f71c15 >> >> Improvement in speed ranges from 8% (for small strings) to 200% (for long >> strings), while creation of garbage has been further reduced to an almost >> garbage-free operation. >> >> So WDYT? > > src/java.base/share/classes/java/lang/String.java line 3230: > >> 3228: >> 3229: /** >> 3230: * Designated join routine. > > Did you mean "dedicated"? No, I meant designated. It is the routine that all other public API entry points call at the end to do the job. Would some other word more accurately describe that? I definitely didn't mean "dedicated". ------------- PR: https://git.openjdk.java.net/jdk/pull/3501
