RFR: 8291555: Replace stack-locking with fast-locking [v3]

[Roman Kennke]

On Tue, 11 Oct 2022 20:41:57 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Regarding benchmarks, is it possible to get some indication what fast-locking+lillput result will be? FinagleHttp seems to suffer a bit, will Lillput give some/all of that back, or more?

That particular benchmark, as some others, exhibit relatively high run-to-run variance. I have run it again many more times to average-out the variance, and I'm now getting the following results:
baseline: 3503.844 ms/ops, fast-locking: 3546.344 ms/ops, percent: -1.20%

That is still a slight regression, but with more confidence.

Regarding Lilliput, I cannot really say at the moment. Some workloads are actually regressing with Lilliput, presumably because they are sensitive on the performance of loading the Klass* out of objects, and that is currently more complex in Lilliput (because it needs to coordinate with monitor locking). FinagleHttp seems to be one of those workloads. I am working to get rid of this limitation, and then I can be more specific.

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PR: https://git.openjdk.org/jdk/pull/10590