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 > > >
