[jdk11u] Backport the fix of JDK-8180450 to JDK 11?

[Lindenmaier, Goetz]

Hi,

> I don't understand. What's the relevance of whether it's a regression?
Well, if we had backported a bugfix to, say, 11.0.23 that spoils performance,
this would be a performance regression we introduced during 
support. Such a regression we should probably fix because it makes
a younger update worse that an older one.  People updating would
suddenly get a problem.

This one has been there previous to 11 as I understand, so it 
is not a regression of 11 or one of it's updates.

Best regards, Goetz.


> -----Original Message-----
> From: Andrew Haley <aph-open at littlepinkcloud.com>
> Sent: Monday, October 21, 2024 1:01 PM
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; jdk-updates-
> dev at openjdk.org
> Subject: Re: [jdk11u] Backport the fix of JDK-8180450 to JDK 11?
> 
> On 10/17/24 09:14, Lindenmaier, Goetz wrote:
> 
> > This is a big improvement of performance for subtype checking.
> > But it is also a big change in central parts of the JVM.
> > Also, the performance issue solved here is not a regression in
> > 17 (or 11).
> 
> I don't understand. What's the relevance of whether it's a regression?
> 
> > So I think while we could consider this for the latest LTE, 21,
> > we should not bring this to 17 or older releases.  It's just too
> > risky for these.
> > Even for 21 it would be a considerable effort to backport it
> > along with the needed follow-up issues.
> 
> As far as I know there are no needed follow-up issues. It's pretty
> self contained. The patch is written in a way that makes backports
> possible.
> 
> >> I'm not sure. Looking at the rules for backporting, any bug fix "which
> >> contributes to the stability, security or performance of the affected line
> should
> >> be considered." So this definitely fits in the rule of what is allowed in 11u,
> but
> >> of course that doesn't mean that it will be backported, merely that it will
> be
> >> considered.
> > Anyways, in 11 it says "Please note that these common rules do not allow
> > enhancements to be back-ported, only fixes to bugs."
>  > https://wiki.openjdk.org/display/JDKUpdates/JDK11u> and I would rather
> categorize it as an enhancement than a bug, although
> > it's filed as bug in JBS.
> 
> Well, that's a discussion we can have, I suppose, but it's always been
> a bug, going back years. I guess there's a grey area.
> 
> --
> Andrew Haley  (he/him)
> Java Platform Lead Engineer
> Red Hat UK Ltd.
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