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

[Swati Sharma]

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

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

Commit messages:
 - 8311178: JMH tests don't scale well when sharing output buffers

Changes: https://git.openjdk.org/jdk/pull/14746/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14746&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311178
  Stats: 17 lines in 12 files changed: 0 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/14746.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14746/head:pull/14746

PR: https://git.openjdk.org/jdk/pull/14746