RFR: 8352971: Increase maximum number of hold counts for ReentrantReadWriteLock

[Viktor Klang]

On Thu, 27 Mar 2025 11:30:11 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> I'm breaking this change out as a separate improvement, since it will not be generally possible to adjust these limits on the j.u.c primitives since they might already use a backing `long` to pack in information which needs to be updated atomically (would require 128-bit atomics to widen them, and it still infeasible to change return types of pre-existing APIs).
>
> We'll need to double check serialization compatibility as the "sync" field is in the serial form.

@AlanBateman I was able to serialize a RRWL created before this patch and deserialize it after this patch.

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PR Comment: https://git.openjdk.org/jdk/pull/24261#issuecomment-2761756050