RFR: 8339979: VirtualThreadSchedulerMXBeanTest.testReduceParallelism fails intermittently

Wed Oct 2 18:59:09 UTC 2024

This is a test only change. VirtualThreadSchedulerMXBeanTest.testReduceParallelism can fail if getMountedVirtualThreadCount over estimates the number of mounted virtual threads.

The change is changed from using getMountedVirtualThreadCount to use an awaitXXX method that will sample the mounted virtual thread count until it reads an expected value.

As part of the change, the awaitXXX supporting methods are changed to take a predicate and the trace message.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/21310/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21310&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339979
  Stats: 55 lines in 1 file changed: 18 ins; 10 del; 27 mod
  Patch: https://git.openjdk.org/jdk/pull/21310.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21310/head:pull/21310

PR: https://git.openjdk.org/jdk/pull/21310