RFR: Direct LambdaMetaFactory invocation from CallSite significantly improves lambda linkage performance

Sergey Kuksenko sergey.kuksenko at oracle.com
Mon Sep 16 16:22:46 UTC 2013

Hi John, Brian,
I did evaluation JDK-8024630(my patch) vs JDK-8024761(your patch).

I did it for lambda linkage vs anonymous classloading. Because of
non-capture lambdas behaviour significantly differ capturing lambdas I
have to measure linkage twice (non-capturing vs capturing). Other
dimension is Tiered vs NonTiered compilation. I checked it on loading
different amount of lambdas (classes) - 1K, 4K, 8K, 16K, 24K, 32K, 64K.

Non-capturing lambda:
- JDK-8024630 is slightly faster (2-3%) than JDK-8024761 on less amount
of lambdas (1K,4K,8K). But starting from 16K JDK-8024761 is faster (also
2-3%). The same for tiered/non-tiered.

Capturing lambda:
- Non-tiered compilation show the same behaviour and the same
percentages as non-capturing lambda. In case of TieredCompilation the
initial difference is started from 8% (JDK-8024630 is faster) and became
lower and both RFEs has the same performance from 24K lambdas.

So looking into my results I'll vote for JDK-8024761 instead of
JDK-8024630. Because of your solution is general and performance
difference is not significant.

On 09/11/2013 10:18 PM, John Rose wrote:
> Yes, this is a good tactic, but as written it is too much of a point hack for lambdas (important though they are).
> I have an alternate solution I would like you to measure.  It provides a fast path for other BSM lookups like Nashorn's, so (if it works well for lambda) it is preferable.
> I will attach a patch to the bug report.
> — John
> On Sep 11, 2013, at 9:23 AM, Sergey Kuksenko <sergey.kuksenko at oracle.com> wrote:
>> Please review the webrev at:
>> http://cr.openjdk.java.net/~skuksenko/jsr335/8024630/webrev.00/
>> LambdaMetafactory is is a quite frequent bootstrap method for
>> invokedynamic in JDK8.
>> We can do direct method (LambdaMetafactory) invocation as fastpath when
>> proved that bootstrap MethodHandle points to LambdaMetafactory.
>> The modification gives +10% - +35% to lambda linkage performance
>> (depends on amount of lambdas).
>> -- 
>> Best regards,
>> Sergey Kuksenko

Best regards,
Sergey Kuksenko

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