RFR: 8252627: Make it safe for JFR thread to read threadObj

Mon Sep 7 14:20:05 UTC 2020

Migrating this review from the mailing list to a PR so I can integrate it. Already reviewed really.

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Commit messages:
 - 8252627_jfr_thread_oop

Changes: https://git.openjdk.java.net/jdk/pull/59/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=59&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252627
  Stats: 13 lines in 2 files changed: 3 ins; 4 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/59.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/59/head:pull/59

PR: https://git.openjdk.java.net/jdk/pull/59