RFR: 8351976: assert(vthread_epoch == current_epoch) failed: invariant

[Markus Grönlund]

Greetings,

This fix adjusts for an epoch mismatch for excluded virtual threads that become included after being mounted. The JIRA issue has more details.

Testing: jdk_jfr, stress testing

Thanks
Markus

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Commit messages:
 - 8351976

Changes: https://git.openjdk.org/jdk/pull/24041/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24041&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351976
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24041.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24041/head:pull/24041

PR: https://git.openjdk.org/jdk/pull/24041