Re: RFR: 8273140: Replace usages of Enum.class.getEnumConstants() with Enum.values() where possible [v4]
On Tue, 31 Aug 2021 20:04:23 GMT, Сергей Цыпанов
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
>> }
>> }
>>
>>
>> BenchmarkMode Cnt
>> Score Error Units
>> EnumBenchmark.getEnumConstants avgt 15
>> 6,265 ± 0,051 ns/op
>> EnumBenchmark.getEnumConstants:·gc.alloc.rateavgt 15
>> 2434,075 ± 19,568 MB/sec
>> EnumBenchmark.getEnumConstants:·gc.alloc.rate.norm avgt 15
>> 24,002 ± 0,001B/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 ± 0,659B/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
>> 210,000counts
>> EnumBenchmark.getEnumConstants:·gc.time avgt 15
>> 119,000ms
>>
>> 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 ± 0,001B/op
>> EnumBenchmark.values:·gc.churn.G1_Eden_Space avgt 15
>> 3660,512 ± 137,250 MB/sec
>> EnumBenchmark.values:·gc.churn.G1_Eden_Space.normavgt 15
>> 23,972 ± 0,529B/op
>> EnumBenchmark.values:·gc.churn.G1_Survivor_Space avgt 15
>> 0,017 ± 0,003 MB/sec
>> EnumBenchmark.values:·gc.churn.G1_Survivor_Space.normavgt 15
>> ≈ 10⁻⁴ B/op
>> EnumBenchmark.values:·gc.count avgt 15
>> 262,000counts
>> EnumBenchmark.values:·gc.timeavgt 15
>> 155,000ms
>
> 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
Re: RFR: 8273140: Replace usages of Enum.class.getEnumConstants() with Enum.values() where possible [v4]
> 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
> }
> }
>
>
> BenchmarkMode Cnt
> Score Error Units
> EnumBenchmark.getEnumConstants avgt 15
> 6,265 ± 0,051 ns/op
> EnumBenchmark.getEnumConstants:·gc.alloc.rateavgt 15
> 2434,075 ± 19,568 MB/sec
> EnumBenchmark.getEnumConstants:·gc.alloc.rate.norm avgt 15
> 24,002 ± 0,001B/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 ± 0,659B/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
> 210,000counts
> EnumBenchmark.getEnumConstants:·gc.time avgt 15
> 119,000ms
>
> 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 ± 0,001B/op
> EnumBenchmark.values:·gc.churn.G1_Eden_Space avgt 15
> 3660,512 ± 137,250 MB/sec
> EnumBenchmark.values:·gc.churn.G1_Eden_Space.normavgt 15
> 23,972 ± 0,529B/op
> EnumBenchmark.values:·gc.churn.G1_Survivor_Space avgt 15
> 0,017 ± 0,003 MB/sec
> EnumBenchmark.values:·gc.churn.G1_Survivor_Space.normavgt 15
> ≈ 10⁻⁴ B/op
> EnumBenchmark.values:·gc.count avgt 15
> 262,000counts
> EnumBenchmark.values:·gc.timeavgt 15
> 155,000ms
Сергей Цыпанов has updated the pull request incrementally with one additional
commit since the last revision:
8273140: Fix copyright year
-
Changes:
- all: https://git.openjdk.java.net/jdk/pull/5303/files
- new: https://git.openjdk.java.net/jdk/pull/5303/files/171ecd4e..a5f58fe2
Webrevs:
- full: https://webrevs.openjdk.java.net/?repo=jdk=5303=03
- incr: https://webrevs.openjdk.java.net/?repo=jdk=5303=02-03
Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
Patch: https://git.openjdk.java.net/jdk/pull/5303.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/5303/head:pull/5303
PR: https://git.openjdk.java.net/jdk/pull/5303
