On Tue, 31 Aug 2021 20:04:23 GMT, Сергей Цыпанов <github.com+10835776+stsypa...@openjdk.org> wrote:
>> Just a very tiny clean-up. >> >> There are some places in JDK code base where we call >> `Enum.class.getEnumConstants()` to get all the values of the referenced >> `enum`. This is excessive, less-readable and slower than just calling >> `Enum.values()` as in `getEnumConstants()` we have volatile access: >> >> public T[] getEnumConstants() { >> T[] values = getEnumConstantsShared(); >> return (values != null) ? values.clone() : null; >> } >> >> private transient volatile T[] enumConstants; >> >> T[] getEnumConstantsShared() { >> T[] constants = enumConstants; >> if (constants == null) { /* ... */ } >> return constants; >> } >> >> Calling values() method is slightly faster: >> >> @BenchmarkMode(Mode.AverageTime) >> @OutputTimeUnit(TimeUnit.NANOSECONDS) >> @Fork(jvmArgsAppend = {"-Xms2g", "-Xmx2g"}) >> public class EnumBenchmark { >> >> @Benchmark >> public Enum[] values() { >> return Enum.values(); >> } >> >> @Benchmark >> public Enum[] getEnumConstants() { >> return Enum.class.getEnumConstants(); >> } >> >> private enum Enum { >> A, >> B >> } >> } >> >> >> Benchmark Mode Cnt >> Score Error Units >> EnumBenchmark.getEnumConstants avgt 15 >> 6,265 ± 0,051 ns/op >> EnumBenchmark.getEnumConstants:·gc.alloc.rate avgt 15 >> 2434,075 ± 19,568 MB/sec >> EnumBenchmark.getEnumConstants:·gc.alloc.rate.norm avgt 15 >> 24,002 ± 0,001 B/op >> EnumBenchmark.getEnumConstants:·gc.churn.G1_Eden_Space avgt 15 >> 2433,709 ± 70,216 MB/sec >> EnumBenchmark.getEnumConstants:·gc.churn.G1_Eden_Space.norm avgt 15 >> 23,998 ± 0,659 B/op >> EnumBenchmark.getEnumConstants:·gc.churn.G1_Survivor_Space avgt 15 >> 0,009 ± 0,003 MB/sec >> EnumBenchmark.getEnumConstants:·gc.churn.G1_Survivor_Space.norm avgt 15 >> ≈ 10⁻⁴ B/op >> EnumBenchmark.getEnumConstants:·gc.count avgt 15 >> 210,000 counts >> EnumBenchmark.getEnumConstants:·gc.time avgt 15 >> 119,000 ms >> >> EnumBenchmark.values avgt 15 >> 4,164 ± 0,134 ns/op >> EnumBenchmark.values:·gc.alloc.rate avgt 15 >> 3665,341 ± 120,721 MB/sec >> EnumBenchmark.values:·gc.alloc.rate.norm avgt 15 >> 24,002 ± 0,001 B/op >> EnumBenchmark.values:·gc.churn.G1_Eden_Space avgt 15 >> 3660,512 ± 137,250 MB/sec >> EnumBenchmark.values:·gc.churn.G1_Eden_Space.norm avgt 15 >> 23,972 ± 0,529 B/op >> EnumBenchmark.values:·gc.churn.G1_Survivor_Space avgt 15 >> 0,017 ± 0,003 MB/sec >> EnumBenchmark.values:·gc.churn.G1_Survivor_Space.norm avgt 15 >> ≈ 10⁻⁴ B/op >> EnumBenchmark.values:·gc.count avgt 15 >> 262,000 counts >> EnumBenchmark.values:·gc.time avgt 15 >> 155,000 ms > > Сергей Цыпанов has updated the pull request incrementally with one additional > commit since the last revision: > > 8273140: Fix copyright year Lgtm. ------------- Marked as reviewed by tschatzl (Reviewer). PR: https://git.openjdk.java.net/jdk/pull/5303