RFR: 8306647: Implementation of Structured Concurrency (Preview)

[Andrew Haley]

On Tue, 23 May 2023 18:23:21 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> Oh, and i guess that has some performance implications in some cases? more so on the set of instructions produced on ARM say rather than limiting C2 optimizations?

I think so. As far as I can remember, a release fence on x86 generates no code at all.

> Given that the Supplier is likely to be the target of a lambda expression which may also capture I was surprised there would be much of an increased impact. (HotSpot may not strength reduce multiple fences in this case.)

It may, or it may not. I don't really want the call without a checked exception to be more costly than a call with one. That seems a little weird, at least.

> Can we update to add say "/* non-final */ to the field and update the class doc to say the release fence inserted by HotSpot as a result of constructing a class with final fields has performance implications <<"insert loose quantification of those implications">> ?

Sure, thanks.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13932#discussion_r1202870649