[jdk17] RFR: 8271588: JFR Recorder Thread crashed with SIGSEGV in write_klass

[Markus Grönlund]

Greetings,

please help review this fix to better support concurrent class unloading.
Details in the JIRA issue.

Testing: jdk_jfr, stress

Thanks
Markus

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Commit messages:
 - JFR Recorder Thread crashed with SIGSEGV in write_klass

Changes: https://git.openjdk.java.net/jdk17/pull/301/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=301&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271588
  Stats: 19 lines in 5 files changed: 12 ins; 2 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/301.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/301/head:pull/301

PR: https://git.openjdk.java.net/jdk17/pull/301