RFR: 8315061: Make LockingMode a product flag

[Daniel D. Daugherty]

On Wed, 30 Aug 2023 19:36:45 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> A trivial fix to make LockingMode a product flag.

Repeating my answer from the RFE:

https://bugs.openjdk.org/browse/JDK-8315061?focusedCommentId=14607768&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14607768

In order to change the default LockingMode value from LM_LEGACY to
LM_LIGHTWEIGHT, we have to first change LockingMode to a product
flag in JDK22 and then in the next release we can change the default
LockingMode value from LM_LEGACY to LM_LIGHTWEIGHT.

We can't change the default LockingMode value without making LockingMode
into a product flag because we have to give customers a supported means
of changing the LockingMode should there be any issues with the new default.

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PR Comment: https://git.openjdk.org/jdk/pull/15496#issuecomment-1699813461