Thanks for bringing this to our attention! I would choose simplicity over backward compatibility given Flink 2.0 offers the opportunity for breaking changes. We will benefit from it from long-term's perspective. +1 for upgrading Kryo in Flink 2.0 in a non compatible way.
Best regards, Jing On Wed, Feb 26, 2025 at 5:37 AM Nick Nezis <nickne...@apache.org> wrote: > Thanks Martijn. > > That's really great context. In that case, then I'll change my previous > opinion. I agree that we should proceed with the simpler pull request and > get it into the Flink 2.0 release. > > On 2025/02/25 14:06:20 Martijn Visser wrote: > > Hi all, > > > > For the record, I don't think we have a guarantee around backwards > > compatibility for Flink 2.0 anyway, given that we upgraded Scala to the > > latest version (because of the bump to JDK 17) and that will potentially > > break savepoints when using Scala. So I think we should also put this in > > for Flink 2.0, and just have the right release notes/documentation for > this. > > > > Best regards, > > > > Martijn > > > > On Tue, Feb 25, 2025 at 3:31 AM Zhanghao Chen <zhanghao.c...@outlook.com > > > > wrote: > > > > > Hi Gyula, > > > > > > Thanks for bringing this up! Definitely +1 for upgrading Kryo in Flink > > > 2.0. As a side note, it might be useful to introduce customizable > generic > > > serializer support like Spark, where you can switch to your own > serializer > > > via the "spark.serializer" [1] option. Users starting new applications > can > > > introduce their own serialization stack in this case to resolve Java > > > compatibility issue is this case or for other performance issues. > > > > > > [1] https://spark.apache.org/docs/latest/configuration.html > > > > > > > > > Best, > > > Zhanghao Chen > > > ________________________________ > > > From: Gyula F?ra <gyula.f...@gmail.com> > > > Sent: Friday, February 21, 2025 14:04 > > > To: dev <dev@flink.apache.org> > > > Subject: [DISCUSSION] Upgrade to Kryo 5 for Flink 2.0 > > > > > > Hey all! > > > > > > I would like to rekindle this discussion as it seems that it has > stalled > > > several times in the past and we are nearing the point in time where > the > > > decision has to be made with regards to 2.0. (we are already a bit > late but > > > nevermind) > > > > > > There has been numerous requests and efforts to upgrade Kryo to better > > > support newer Java versions and Java native types. I think we can all > agree > > > that this change is inevitable one way or another. > > > > > > The latest JIRA for this seems to be: > > > https://issues.apache.org/jira/browse/FLINK-3154 > > > > > > There is even an open PR that accomplishes this (currently in a state > > > incompatible way) but based on the discussion it seems that with some > extra > > > complexity compatibility can even be preserved by having both the old > and > > > new Kryo versions active at the same time. > > > > > > The main question here is whether state compatibility is important for > 2.0 > > > with this regard or we want to bite the bullet and make this upgrade > once > > > and for all. > > > > > > Cheers, > > > Gyula > > > > > >
