Please review this small benchmark fix.
Running `ThreadStartJoin` with two workers can fail: `java -jar benchmarks.jar
-t 2 ThreadStartJoin`
# Warmup Iteration 1: <failure>
java.lang.IllegalThreadStateException
at java.base/java.lang.Thread.start(Thread.java:1494)
at
org.openjdk.bench.java.lang.ThreadStartJoin.test(ThreadStartJoin.java:62)
at
org.openjdk.bench.java.lang.jmh_generated.ThreadStartJoin_test_jmhTest.test_avgt_jmhStub(ThreadStartJoin_test_jmhTest.java:238)
at
org.openjdk.bench.java.lang.jmh_generated.ThreadStartJoin_test_jmhTest.test_AverageTime(ThreadStartJoin_test_jmhTest.java:177)
at
java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
**Fix:** Change `Scope.Benchmark` to `Scope.Thread` so each worker has its own
thread array.
The test is meant to measure the cost of creating, starting, and waiting for a
batch of threads to finish, not having multiple workers operate on the same
thread array. So this looks like a low-risk change that keeps the benchmark's
original intent.
**Testing:**
- ThreadStartJoin: 1/2/4 workers passed, using the default CPU count and
`-XX:ActiveProcessorCount=1` and `2`.
---------
- [x] I confirm that I make this contribution in accordance with the [OpenJDK
Interim AI Policy](https://openjdk.org/legal/ai).
-------------
Commit messages:
- 8350907: [JMH] test ThreadStartJoin failed for 2 threads config
Changes: https://git.openjdk.org/jdk/pull/33239/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=33239&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8350907
Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
Patch: https://git.openjdk.org/jdk/pull/33239.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/33239/head:pull/33239
PR: https://git.openjdk.org/jdk/pull/33239
