On Thu, 22 Jun 2023 00:13:06 GMT, 温绍锦 <[email protected]> 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:
>
> move HEX256 to LongCache
Changes requested by liach (Author).
About @Glavo's VH suggestion: I think it is feasible, since the VH field is not
initialized until the method is used, so there should be no startup issue.
On a side note, JDK itself has a `UUIDBench` that benchmarks toString as well:
can run it with `make test TEST="micro:java.util.UUIDBench.toString"` once the
configuration has JMH set up, which I will be using (against master and this
patch)
src/java.base/share/classes/java/lang/Long.java line 484:
> 482:
> 483: buf[off] = (byte) (i >> 8);
> 484: buf[1 * charSize + off] = (byte) i;
Suggestion:
buf[off] = (byte) (i0 >> 8);
buf[1 * charSize + off] = (byte) i0;
Doesn't compile on my end
-------------
PR Review: https://git.openjdk.org/jdk/pull/14578#pullrequestreview-1492220846
PR Comment: https://git.openjdk.org/jdk/pull/14578#issuecomment-1601915404
PR Review Comment: https://git.openjdk.org/jdk/pull/14578#discussion_r1237906554
