RFR: JDK-8310502 : Optimization for j.l.Long.fastUUID() [v8]

[温绍锦]

On Thu, 22 Jun 2023 07:16:25 GMT, 温绍锦 <duke at openjdk.org> wrote:

>> By optimizing the implementation of java.lang.Long#fastUUID, the performance of the java.util.UUID#toString method can be significantly improved.
>> 
>> The following are the test results of JMH: 
>> 
>> Benchmark                     Mode  Cnt      Score      Error   Units
>> UUIDUtilsBenchmark.new       thrpt    5  92676.550 ±  292.213  ops/ms
>> UUIDUtilsBenchmark.original  thrpt    5  37040.165 ± 1023.532  ops/ms
>
> 温绍锦 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix compile error

> I've tested the benchmarks and the patch and baseline (with extra stable annotation) with a slightly varied version suitable for gradle run:
> 
> ```java
> package com.alibaba.openjdk;
> 
> import org.openjdk.jmh.annotations.Benchmark;
> import org.openjdk.jmh.annotations.BenchmarkMode;
> import org.openjdk.jmh.annotations.Fork;
> import org.openjdk.jmh.annotations.Measurement;
> import org.openjdk.jmh.annotations.Mode;
> import org.openjdk.jmh.annotations.OutputTimeUnit;
> import org.openjdk.jmh.annotations.Warmup;
> import org.openjdk.jmh.infra.Blackhole;
> 
> import java.util.UUID;
> import java.util.concurrent.TimeUnit;
> 
> @BenchmarkMode(Mode.Throughput)
> @OutputTimeUnit(TimeUnit.MILLISECONDS)
> @Warmup(iterations = 3, time = 10)
> @Measurement(iterations = 6, time = 5)
> @Fork(1)
> public class UUIDUtilsBenchmark {
>     public static UUID uuid = UUID.randomUUID();
> 
>     @Benchmark
>     public void jdk(Blackhole bh) {
>         bh.consume(uuid.toString());
>     }
> 
>     @Benchmark
>     public void fast(Blackhole bh) {
>         bh.consume(UUIDUtils.fastUUID(uuid));
>     }
> }
> ```
> 
> The throughput varies a lot between iterations somehow; the patch and baseline with stable has no significant difference (i.e. within the error range, about 10%)

the performance of this improvement varies among different environments, with a significant improvement on the MacBookPro M1 Max chip (my laptop) and only about 10% improvement on Linux servers (Intel Xeon(Sapphire Rapids) Platinum and Aliyun Yitian 710 arm CPU and Orange Pi 5 Plus).

-------------

PR Comment: https://git.openjdk.org/jdk/pull/14578#issuecomment-1602144426