RFR: 8245455: Remove alternative StringConcatFactory strategies

[Remi Forax]

----- Mail original -----
> De: "Paul Sandoz" <paul.sandoz at oracle.com>
> À: "Claes Redestad" <claes.redestad at oracle.com>
> Cc: "core-libs-dev" <core-libs-dev at openjdk.java.net>
> Envoyé: Vendredi 22 Mai 2020 19:28:39
> Objet: Re: RFR: 8245455: Remove alternative StringConcatFactory strategies

> Hi,
> 
> I support the removal of all the other strategies to simplify SCF and make it
> more maintainable.
> 
> Having one or more strategies to fall back on (with an undocumented flag) was I
> think right thing to do when initially introducing the feature. Over time, the
> default strategy has become more and more robust where as the others have
> languished due to their lack of exposure and development focus, decreasing my
> confidence they would not introduce different issues if enabled.
> 
> It’s a judgement call but I think maturation of this feature has tipped in favor
> of the simplification provided by Claes’s patch.

I agree with Claes and Paul,
an indy + its metafactory is like a new opcode in the bytecode,
the VM doesn't maintain several implementations of a bytecode.

> 
> Paul.

Rémi

> 
> 
>> On May 22, 2020, at 2:52 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
>> 
>> Hi,
>> 
>> this patch removes the alternative, undocumented strategies from
>> StringConcatFactory.
>> 
>> The default strategy has been optimized and stabilized since inception in JDK 9,
>> while the alternative strategies have been falling behind
>> both in terms of performance and stability - while adding maintenance
>> cost.
>> 
>> The removal allows some simplifications to the code that will reduce
>> per callsite bootstrap overhead, and reduce what we need to load eagerly
>> during bootstrap. I've also applied the pattern from JDK-8218173 to
>> the remaining Stringifier method handles, which further improve
>> robustness of bootstrapping under an OOME condition.
>> 
>> Webrev: http://cr.openjdk.java.net/~redestad/8245455/open.00/
>> Bug:    https://bugs.openjdk.java.net/browse/JDK-8245455
>> 
>> Testing: tier1-3
>> 
>> Thanks!
>> 
> > /Claes