RFR: 8345970: pthread_getcpuclockid related crashes in shenandoah tests [v3]

[William Kemper]

> I haven't seen this failure mode in our Alpine Linux test pipelines, but the suggestion to avoid getting cpu time for terminated threads sounds sensible.

William Kemper has updated the pull request incrementally with two additional commits since the last revision:

 - Stop regulator thread after control thread
 - Revert unnecessary change

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22693/files
  - new: https://git.openjdk.org/jdk/pull/22693/files/e99aaa5f..6b2f74e5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22693&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22693&range=01-02

  Stats: 11 lines in 2 files changed: 8 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22693.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22693/head:pull/22693

PR: https://git.openjdk.org/jdk/pull/22693