On Tue, 24 Nov 2020 09:58:19 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> Original mail: >> https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-September/069197.html >> >> Hello, >> >> while working with `StringBuilder.insert()` I've spotted that its delegate >> `AbstractStringBuilder.insert()` is missing >> a fast-path for the most frequent case when its argument is `String`. >> >> Previously they did similart optimization for >> `StirngBuilder.append(CharSequence, int, int)`, >> see https://bugs.openjdk.java.net/browse/JDK-8224986 >> >> I'd like to contribute a trivial patch that brings improvement for the case >> when SB's content is Latin1 >> and inserted String is Latin1 as well. >> >> To measure improvement I've used simple benchmark: >> @BenchmarkMode(Mode.AverageTime) >> @OutputTimeUnit(TimeUnit.NANOSECONDS) >> @Fork(jvmArgsAppend = {"-Xms2g", "-Xmx2g"}) >> public class StringBuilderInsertBenchmark { >> >> @Benchmark >> public StringBuilder insert(Data data) { >> String string = data.string; >> return new StringBuilder().append("ABC").insert(1, string, 1, >> data.length + 1); >> } >> >> @State(Scope.Thread) >> public static class Data { >> String string; >> >> @Param({"true", "false"}) >> private boolean latin; >> >> @Param({"8", "64", "128", "1024"}) >> private int length; >> >> @Setup >> public void setup() { >> String alphabet = latin >> ? "abcdefghijklmnopqrstuvwxyz" // English >> : "абвгдеёжзиклмнопрстуфхцчшщьыъэюя"; // Russian >> >> string = new RandomStringGenerator().randomString(alphabet, length + >> 2); >> } >> } >> } >> >> public final class RandomStringGenerator { >> >> public String randomString(String alphabet, int length) { >> char[] chars = alphabet.toCharArray(); >> >> ThreadLocalRandom random = ThreadLocalRandom.current(); >> >> char[] array = new char[length]; >> for (int i = 0; i < length; i++) { >> array[i] = chars[random.nextInt(chars.length)]; >> } >> >> return new String(array); >> } >> } >> Which gives >> >> (latin) (length) original patched Units >> insert true 8 24.2 ± 0.1 22.2 ± 0.0 ns/op >> insert true 64 53.8 ± 0.2 36.1 ± 0.1 ns/op >> insert true 128 80.9 ± 0.2 44.6 ± 0.0 ns/op >> insert true 1024 365.4 ± 0.5 109.8 ± 3.9 ns/op >> >> insert false 8 33.5 ± 0.5 32.3 ± 0.2 ns/op >> insert false 64 73.2 ± 0.3 73.2 ± 0.2 ns/op >> insert false 128 103.9 ± 0.6 103.3 ± 0.1 ns/op >> insert false 1024 576.5 ± 4.8 569.5 ± 2.0 ns/op >> Patch is attached. As of tests tier1 and tier2 are ok. >> >> With best regards, >> Sergey Tsypanov > > Hi Sergey, I see Roger filed an RFE for this: > [JDK-8254082](https://bugs.openjdk.java.net/browse/JDK-8254082). To move the > PR along, you need to add "8254082: " as a prefix to the PR summary. Then all > checks should clear and this will move to the RFR stage. @cl4es thanks for pointing this out, done! ------------- PR: https://git.openjdk.java.net/jdk/pull/402
