RFR: 8318757: VM_ThreadDump asserts in interleaved ObjectMonitor::deflate_monitor calls [v12]

[Stefan Karlsson]

> A safepointed monitor deflation pass can run interleaved with a paused async monitor deflation pass. The code is not written to handle that situation and asserts when it finds a DEFLATER_MARKER in the owner field. @pchilano also found other issues with having to monitor deflation passes interleaved. More info below ...

Stefan Karlsson has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 21 additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into 8318757_interleaved_monitor_deflation
 - More tweaks to the test
 - Tweak test
 - Do stuff in the synchronized block of the test
 - Update names in test
 - Remove the limit for deflation requests
 - Remove reinitialization in test
 - Update comments
 - Tweak the flag comment a bit
 - Add AsyncMonitorDeflationForThreadDumpLimit flag
 - ... and 11 more: https://git.openjdk.org/jdk/compare/3637348d...9e97ed90

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16519/files
  - new: https://git.openjdk.org/jdk/pull/16519/files/df04ca04..9e97ed90

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16519&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16519&range=10-11

  Stats: 635344 lines in 1331 files changed: 90458 ins; 480441 del; 64445 mod
  Patch: https://git.openjdk.org/jdk/pull/16519.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16519/head:pull/16519

PR: https://git.openjdk.org/jdk/pull/16519