RFR: 8359936: StableValues can release the underlying function after complete computation [v4]

[Per Minborg]

On Tue, 12 Aug 2025 09:09:17 GMT, Viktor Klang <vklang at openjdk.org> wrote:

>> No, because the stable value doesn’t get set in that case, so the supplier/function will be called again.
>
> @ExE-Boss That seems to presume that 1) it will be called again, and 2) it will eventually produce a non-exception

The underlying function will be retained until all values are computed (non exceptionally). It is as simple as that.

I was not able to come up with something better than that, but I am open to other suggestions.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25878#discussion_r2269603690