RFR: 8261847: performace of java.lang.Record::toString should be improved
Glavo
duke at openjdk.java.net
Tue Nov 16 10:39:38 UTC 2021
On Tue, 16 Nov 2021 09:45:56 GMT, Сергей Цыпанов <duke at openjdk.java.net> wrote:
>> Please review this PR which aims to optimize the implementation of the `toString` method we provide for records. A benchmark comparing the implementation we are providing for records with lombok found out that lombok is much faster mainly because our implementation uses `String::format`. This fix is basically delegating on StringConcatFactory::makeConcatWithConstants which is faster.
>>
>> TIA
>>
>> This is the result of the benchmark comparing records to lombok with vanilla JDK:
>>
>> Benchmark Mode Cnt Score Error Units
>> MyBenchmark.base avgt 4 0.849 ± 0.111 ns/op
>> MyBenchmark.equals_record avgt 4 7.343 ± 2.740 ns/op
>> MyBenchmark.equals_value avgt 4 6.644 ± 1.920 ns/op
>> MyBenchmark.record_hash_code avgt 4 5.763 ± 3.882 ns/op
>> MyBenchmark.record_to_string avgt 4 262.626 ± 12.574 ns/op <------ Before
>> MyBenchmark.value_class_to_string avgt 4 30.325 ± 21.389 ns/op
>> MyBenchmark.value_hash_code avgt 4 5.048 ± 3.936 ns/op
>>
>>
>> after this patch:
>>
>> Benchmark Mode Cnt Score Error Units
>> MyBenchmark.base avgt 4 0.680 ± 0.185 ns/op
>> MyBenchmark.equals_record avgt 4 5.599 ± 1.348 ns/op
>> MyBenchmark.equals_value avgt 4 5.718 ± 4.633 ns/op
>> MyBenchmark.record_hash_code avgt 4 4.628 ± 4.368 ns/op
>> MyBenchmark.record_to_string avgt 4 26.791 ± 1.817 ns/op <------- After
>> MyBenchmark.value_class_to_string avgt 4 35.473 ± 2.626 ns/op
>> MyBenchmark.value_hash_code avgt 4 6.152 ± 5.101 ns/op
>
> src/java.base/share/classes/java/lang/runtime/ObjectMethods.java line 264:
>
>> 262: .map(g -> g.type().returnType())
>> 263: .toList()
>> 264: .toArray(new Class<?>[getters.length]);
>
> Why not `new Class[0]`? It's likely to be faster, isn't it?
(I'm not reviewer.)
I think `.toArray(Class<?>[]::new)` should be better here. `.toList` seems unnecessary.
-------------
PR: https://git.openjdk.java.net/jdk/pull/6403
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