RFR: 8319253: [BACKOUT] Change LockingMode default from LM_LEGACY to LM_LIGHTWEIGHT

[Thomas Stuefe]

On Wed, 8 Nov 2023 00:14:14 GMT, David Holmes <dholmes at openjdk.org> wrote:

> The change of default locking mode for JDK 22 is being restored to LM_LEGACY due to remaining stability and performance issues that have been uncovered with lightweight locking, for which solutions have not yet been found, but are being actively investigated. We will make the change in JDK 23 instead.
> 
> This reverts commit 455cfae1e137ff3055b3cc858e8954f60bdf3147.
> 
> Testing: tiers 1-3 (our internal tier 3 testing includes a set of tests using mode LM_LIGHTWEIGHT so that it will continue to experience some testing until we flip things back in December)
> 
> Thanks.

Seems reasonable if regrettable.

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Marked as reviewed by stuefe (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16551#pullrequestreview-1719504886