On Thu, 22 Jun 2023 10:13:18 GMT, 温绍锦 <d...@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:
>
> use ByteArray & simplify code
src/java.base/share/classes/java/lang/Long.java line 492:
> 490: ByteArray.setChar(buf, 30, i13);
> 491: ByteArray.setChar(buf, 32, i14);
> 492: ByteArray.setChar(buf, 34, i15);
Suggestion:
ByteArray.setLong(buf, 0, ((long) i0 << 48) | ((long) i1 << 32) |
((long) i2 << 16) | i3);
buf[8] = '-';
ByteArray.setInt(buf, 9, (i4 << 16) | i5);
buf[13] = '-';
ByteArray.setInt(buf, 14, (i6 << 16) | i7);
buf[18] = '-';
ByteArray.setInt(buf, 19, (i8 << 16) | i9);
buf[23] = '-';
ByteArray.setLong(buf, 24, ((long) i10 << 48) | ((long) i11 << 32)
| ((long) i12 << 16) | i13);
ByteArray.setInt(buf, 32, (i14 << 16) | i15);
JMH Result:
Benchmark Mode Cnt Score Error Units
- UUID.test thrpt 5 87196.091 ± 492.129 ops/ms
+ UUID.test thrpt 5 99197.287 ± 925.266 ops/ms
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14578#discussion_r1238363498
