RFR(XS) 8249719: MethodHandle performance suffers from bad ResolvedMethodTable hash function

[Volker Simonis]

Hi Andrei,

nice finding :)

I think your fix looks good and I'm happy to sponsor your change once
we get a second review.

I only have a question about your test. How long does it usually run
before and after your fix? Just trying to understand if it is stable
enough in cases where a test machine might be overloaded or if we
should rather make it a manual test.

Thank you and best regards,
Volker

On Fri, Jul 24, 2020 at 4:54 PM Andrei Pangin <andrei.pangin at gmail.com> wrote:
>
> Hi,
>
> Please review a small fix to a not-so-small performance issue that we've
> seen when migrating a production application from JDK 8 to JDK 14.
>
> On certain workloads, where Nashorn produces thousands MethodHandles,
> ResolvedMethodTable operations become extremely slow due to degenerate
> hashcode. This patch basically fixes hashcode by including the method
> holder's name in the computation. More details in the bug report.
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8249719
> Webrev: https://cr.openjdk.java.net/~apangin/8249719/webrev/
>
> Tested: tier1-2, hotspot*runtime
>
> I'll be glad if someone could sponsor the patch.
>
> Thank you,
> Andrei Pangin