Hi Martijn, just to be sure, if all state-related classes use a POJO serializer, Kryo will never come into play, right? Given FLINK-16686 [1], I wonder how many users actually have jobs with Kryo and RocksDB, but even if there aren't many, that still leaves those who don't use RocksDB for checkpoints/savepoints.
If Kryo were to stay in the Flink APIs in v1.X, is it impossible to let users choose between v2/v5 jars by separating them like log4j2 jars? [1] https://issues.apache.org/jira/browse/FLINK-16686 Regards, Alexis. Am Do., 30. März 2023 um 14:26 Uhr schrieb Martijn Visser < martijnvis...@apache.org>: > Hi all, > > I also saw a thread on this topic from Clayton Wohl [1] on this topic, > which I'm including in this discussion thread to avoid that it gets lost. > > From my perspective, there's two main ways to get to Java 17: > > 1. The Flink community agrees that we upgrade Kryo to a later version, > which means breaking all checkpoint/savepoint compatibility and releasing a > Flink 2.0 with Java 17 support added and Java 8 and Flink Scala API support > dropped. This is probably the quickest way, but would still mean that we > expose Kryo in the Flink APIs, which is the main reason why we haven't been > able to upgrade Kryo at all. > 2. There's a contributor who makes a contribution that bumps Kryo, but > either a) automagically reads in all old checkpoints/savepoints in using > Kryo v2 and writes them to new snapshots using Kryo v5 (like is mentioned > in the Kryo migration guide [2][3] or b) provides an offline tool that > allows users that are interested in migrating their snapshots manually > before starting from a newer version. That potentially could prevent the > need to introduce a new Flink major version. In both scenarios, ideally the > contributor would also help with avoiding the exposure of Kryo so that we > will be in a better shape in the future. > > It would be good to get the opinion of the community for either of these > two options, or potentially for another one that I haven't mentioned. If it > appears that there's an overall agreement on the direction, I would propose > that a FLIP gets created which describes the entire process. > > Looking forward to the thoughts of others, including the Users (therefore > including the User ML). > > Best regards, > > Martijn > > [1] https://lists.apache.org/thread/qcw8wy9dv8szxx9bh49nz7jnth22p1v2 > [2] https://lists.apache.org/thread/gv49jfkhmbshxdvzzozh017ntkst3sgq > [3] https://github.com/EsotericSoftware/kryo/wiki/Migration-to-v5 > > On Sun, Mar 19, 2023 at 8:16 AM Tamir Sagi <tamir.s...@niceactimize.com> > wrote: > >> I agree, there are several options to mitigate the migration from v2 to >> v5. >> yet, Oracle roadmap is to end JDK 11 support in September this year. >> >> >> >> ________________________________ >> From: ConradJam <jam.gz...@gmail.com> >> Sent: Thursday, March 16, 2023 4:36 AM >> To: d...@flink.apache.org <d...@flink.apache.org> >> Subject: Re: [Discussion] - Release major Flink version to support JDK 17 >> (LTS) >> >> EXTERNAL EMAIL >> >> >> >> Thanks for your start this discuss >> >> >> I have been tracking this problem for a long time, until I saw a >> conversation in ISSUSE a few days ago and learned that the Kryo version >> problem will affect the JDK17 compilation of snapshots [1] FLINK-24998 , >> >> As @cherry said it ruined our whole effort towards JDK17 >> >> I am in favor of providing an external tool to migrate from Kryo old >> version checkpoint to the new Kryo new checkpoint at one time (Maybe this >> tool start in flink 2.0 ?), does this tool currently have any plans or >> ideas worth discuss >> >> >> I think it should not be difficult to be compatible with JDK11 and JDK17. >> We should indeed abandon JDK8 in 2.0.0. It is also mentioned in the doc >> that it is marked as Deprecated [2] >> >> >> Here I add that we need to pay attention to the version of Scala and the >> version of JDK17 >> >> >> [1] FLINK-24998 IGSEGV in Kryo / C2 CompilerThread on Java 17 >> https://issues.apache.org/jira/browse/FLINK-24998 >> >> [2] FLINK-30501 Update Flink build instruction to deprecate Java 8 instead >> of requiring Java 11 https://issues.apache.org/jira/browse/FLINK-30501 >> >> Tamir Sagi <tamir.s...@niceactimize.com> 于2023年3月16日周四 00:54写道： >> >> > Hey dev community, >> > >> > I'm writing this email to kick off a discussion following this epic: >> > FLINK-15736<https://issues.apache.org/jira/browse/FLINK-15736>. >> > >> > We are moving towards JDK 17 (LTS) , the only blocker now is Flink which >> > currently remains on JDK 11 (LTS). Flink does not support JDK 17 yet, >> with >> > no timeline, the reason, based on the aforementioned ticket is the >> > following tickets >> > >> > 1. FLINK-24998 - SIGSEGV in Kryo / C2 CompilerThread on Java 17< >> > https://issues.apache.org/jira/browse/FLINK-24998>. >> > 2. FLINK-3154 - Update Kryo version from 2.24.0 to latest Kryo LTS >> > version<https://issues.apache.org/jira/browse/FLINK-3154> >> > >> > My question is whether it is possible to release a major version (Flink >> > 2.0.0) using the latest Kryo version for those who don't need to restore >> > old savepoints/checkpoints in newer format. >> > >> > 1. Leverage JDK 17 features within JVM >> > 2. Moving from the old format to the newer one will be handled only >> > once - a mitigation can be achieved by a conversion tool or external >> > serializers, both can be provided later on. >> > >> > I'd like to emphasize that the next JDK LTS (21) will be released this >> > September. furthermore, Flink already supports JDK 12-15, which is very >> > close to JDK 17 (LTS) - that was released in September 2021. JDK 11 >> will >> > become a legacy soon, as more frameworks moving towards JDK 17 and are >> less >> > likely to support JDK 11 in the near future. (For example, Spring Boot 3 >> > requires JDK 17 already). >> > >> > Thank you for your consideration of my request. >> > >> > Tamir. >> > >> > >> > >> > >> > Confidentiality: This communication and any attachments are intended for >> > the above-named persons only and may be confidential and/or legally >> > privileged. Any opinions expressed in this communication are not >> > necessarily those of NICE Actimize. If this communication has come to >> you >> > in error you must take no action based on it, nor must you copy or show >> it >> > to anyone; please delete/destroy and inform the sender by e-mail >> > immediately. >> > Monitoring: NICE Actimize may monitor incoming and outgoing e-mails. >> > Viruses: Although we have taken steps toward ensuring that this e-mail >> and >> > attachments are free from any virus, we advise that in keeping with good >> > computing practice the recipient should ensure they are actually virus >> free. >> > >> >> >> -- >> Best >> >> ConradJam >> >> Confidentiality: This communication and any attachments are intended for >> the above-named persons only and may be confidential and/or legally >> privileged. Any opinions expressed in this communication are not >> necessarily those of NICE Actimize. If this communication has come to you >> in error you must take no action based on it, nor must you copy or show it >> to anyone; please delete/destroy and inform the sender by e-mail >> immediately. >> Monitoring: NICE Actimize may monitor incoming and outgoing e-mails. >> Viruses: Although we have taken steps toward ensuring that this e-mail >> and attachments are free from any virus, we advise that in keeping with >> good computing practice the recipient should ensure they are actually virus >> free. >> >
