Hi Christoph, looks good and trivial. I'll sponsor.
/Claes On 2020-04-05 10:57, Christoph Dreis wrote:
Hi, I just noticed a small optimization opportunity in URLStreamHandler.parseURL for inputs like the following: new URL(new URL("file:"), "file:./path/to/some/local.properties"); In those cases there is no authority involved, which makes it possible to rewrite URLStreamHandler:L269-270:String separator = (authority != null) ? "/" : "";path = separator + spec.substring(start, limit); into the following to avoid unnecessary string concatenations with an empty string: path = spec.substring(start, limit); path = (authority != null) ? "/" + path : path; I've written a small benchmark with two URLStreamHandler variants (one with the old parseURL and one with the new): @BenchmarkMode(Mode.AverageTime) @OutputTimeUnit(TimeUnit.NANOSECONDS) public class MyBenchmark { @State(Scope.Benchmark) public static class ThreadState { private URL context; private URLStreamHandler newHandler = new NewURLStreamHandler(); private URLStreamHandler oldHandler = new OldURLStreamHandler(); private String spec = "file:./path/to/some/application.properties"; public ThreadState() { try { context = new URL("file:"); } catch (MalformedURLException ignored) { } } } @Benchmark public URL testNew(ThreadState threadState) throws MalformedURLException { return new URL(threadState.context, threadState.spec, threadState.newHandler); } @Benchmark public URL testOld(ThreadState threadState) throws MalformedURLException { return new URL(threadState.context, threadState.spec, threadState.oldHandler); } } The benchmark above yields the following results on my local machine: Benchmark Mode Cnt Score Error Units MyBenchmark.testNew avgt 10 112,655 ± 3,494 ns/op MyBenchmark.testNew:·gc.alloc.rate avgt 10 1299,558 ± 41,238 MB/sec MyBenchmark.testNew:·gc.alloc.rate.norm avgt 10 192,015 ± 0,003 B/op MyBenchmark.testNew:·gc.count avgt 10 98,000 counts MyBenchmark.testNew:·gc.time avgt 10 105,000 ms MyBenchmark.testOld avgt 10 128,592 ± 1,183 ns/op MyBenchmark.testOld:·gc.alloc.rate avgt 10 1612,743 ± 15,792 MB/sec MyBenchmark.testOld:·gc.alloc.rate.norm avgt 10 272,019 ± 0,001 B/op MyBenchmark.testOld:·gc.count avgt 10 110,000 counts MyBenchmark.testOld:·gc.time avgt 10 121,000 ms In case you think this is worthwhile I would need someone to sponsor the attached patch for me. I would highly appreciate that. Cheers, Christoph ===== PATCH ===== diff --git a/src/java.base/share/classes/java/net/URLStreamHandler.java b/src/java.base/share/classes/java/net/URLStreamHandler.java --- a/src/java.base/share/classes/java/net/URLStreamHandler.java +++ b/src/java.base/share/classes/java/net/URLStreamHandler.java @@ -266,8 +266,8 @@ spec.substring(start, limit); } else { - String separator = (authority != null) ? "/" : ""; - path = separator + spec.substring(start, limit); + path = spec.substring(start, limit); + path = (authority != null) ? "/" + path : path; } } else if (queryOnly && path != null) { int ind = path.lastIndexOf('/');
