RFR: 8352088: Call of com.sun.jdi.ThreadReference.threadGroups() can lock up target VM [v4]

[Chris Plummer]

> Calling ThreadGroupReference.groups() from an event handler can cause a deadlock. Details in first comment. Tested with :jdk_lang on all supported platforms and tier1, tier2, tier3, and tier5 svc testing.

Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:

  remove unused locals.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24236/files
  - new: https://git.openjdk.org/jdk/pull/24236/files/ea44034c..42fd32e3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24236&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24236&range=02-03

  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24236.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24236/head:pull/24236

PR: https://git.openjdk.org/jdk/pull/24236