esaulpaugh commented on PR #212: URL: https://github.com/apache/ant/pull/212#issuecomment-2925232549
I have not faced a performance issue but I discovered this trick while optimizing a String parser in one of my projects. It performs better in microbenchmarks compared to building an `ArrayList`. I suggested it to gson as well: https://github.com/google/gson/pull/2734 On corretto-11.0.27 aarch64: ``` Benchmark Mode Cnt Score Error Units Measure.arr avgt 14 17.527 ± 0.435 ns/op Measure.list avgt 14 44.013 ± 27.030 ns/op ``` On graalvm-jdk-24+36.1 (24.2.0) aarch64: ``` Benchmark Mode Cnt Score Error Units Measure.arr avgt 14 9.795 ± 0.173 ns/op Measure.list avgt 14 41.321 ± 3.544 ns/op ``` ```java @State(Scope.Benchmark) @Fork(2) @BenchmarkMode(Mode.AverageTime) @Warmup(iterations = 7, time = 500, timeUnit = TimeUnit.MILLISECONDS) @Measurement(iterations = 7, time = 500, timeUnit = TimeUnit.MILLISECONDS) @OutputTimeUnit(TimeUnit.NANOSECONDS) public class Measure { private static final String[] STRINGS = { null, "", "00", "\0", "...", null, "H", "ab", "+", "UUU", null, null, "5\t5" }; @Benchmark public void list(Blackhole blackhole) { ArrayList<String> list = new ArrayList<>(/* STRINGS.length */); for (String s : STRINGS) { if (s != null) { list.add(s); } } blackhole.consume(list.toArray(new String[0])); } @Benchmark public void arr(Blackhole blackhole) { String[] arr = new String[STRINGS.length]; int i = 0; for (String s : STRINGS) { if (s != null) { arr[i++] = s; } } blackhole.consume(Arrays.copyOf(arr, i)); } } ``` It's unlikely that this change alone would make a noticeable difference to users, but small changes can add up eventually, in my experience. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: dev-unsubscr...@ant.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@ant.apache.org For additional commands, e-mail: dev-h...@ant.apache.org
