RFR: 8311178: JMH tests don't scale well when sharing output buffers

[Hamlin Li]

On Sat, 1 Jul 2023 07:53:17 GMT, Swati Sharma <duke at openjdk.org> wrote:

> The below benchmark files have scaling issues due to cache contention and leads to poor scaling when run on multiple threads. The patch sets the scope from benchmark level to thread level to fix the issue:
> - org/openjdk/bench/java/io/DataOutputStreamTest.java
> - org/openjdk/bench/java/lang/ArrayCopyObject.java
> - org/openjdk/bench/java/lang/ArrayFiddle.java
> - org/openjdk/bench/java/time/format/DateTimeFormatterBench.java
> - org/openjdk/bench/jdk/incubator/vector/IndexInRangeBenchmark.java
> - org/openjdk/bench/jdk/incubator/vector/MemorySegmentVectorAccess.java
> - org/openjdk/bench/jdk/incubator/vector/StoreMaskedBenchmark.java
> - org/openjdk/bench/jdk/incubator/vector/StoreMaskedIOOBEBenchmark.java
> - org/openjdk/bench/vm/compiler/ArrayFill.java
> - org/openjdk/bench/vm/compiler/IndexVector.java
> 
> Also removing the static scope for variables in org/openjdk/bench/jdk/incubator/vector/VectorFPtoIntCastOperations.java for better scaling.
> 
> Please review and share your feedback.
> 
> Thanks,
> Swati

Marked as reviewed by mli (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/14746#pullrequestreview-1523547091