RFR: 8314225: SIGSEGV in JavaThread::is_lock_owned [v7]

[Kevin Walls]

> Removal of JavaThread's MonitorChunks member.  This held lock information during deoptimization, but access to it is unnecessary for anything other than the deoptimization itself.
> 
> Access to it in is_lock_owned() was racy, and caused rare crashes.

Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:

  JavaThread comment update and synchronizer check before cast

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18940/files
  - new: https://git.openjdk.org/jdk/pull/18940/files/54086ccd..2989ad4c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18940&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18940&range=05-06

  Stats: 2 lines in 2 files changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18940.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18940/head:pull/18940

PR: https://git.openjdk.org/jdk/pull/18940