[jdk17] RFR: 8269635: Stress test SEGV while emitting OldObjectSample

[Markus Grönlund]

Greetings,

please help review this change set to protect the unloaded thread id set from growing, and hence de-allocated, in the middle of inspection.

Testing: jdk_jfr

Thanks
Markus

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Commit messages:
 - Stress test SEGV while emitting OldObjectSample

Changes: https://git.openjdk.java.net/jdk17/pull/218/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=218&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269635
  Stats: 7 lines in 1 file changed: 0 ins; 1 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/218.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/218/head:pull/218

PR: https://git.openjdk.java.net/jdk17/pull/218