@Xintong The original discussion [1] and vote [2] converged on the idea that it is better to make it clear to the users that they should stop using SourceFunction since it is going away. The longer we do not have this indication, the more user implementations will be based on it and the more pain will be induced when we finally drop it. Users now have an alternative API that they should use and which is fully functional, from that perspective nothing blocks marking it @Deprecated. As for the remaining work items - there are primarily three kinds:
1. Where Flink internally uses SourceFunction, without exposing this fact to the outside world: - FLINK-28050 [3] - FLINK-28229 [4] - FLINK-28048 [5] 2. Very specific edge cases that might not be covered by the Source API as is: - FLINK-28054 [6] - FLINK-28051 [7] 3. Usability improvements - something that was easily doable with SourceFunction, but requires deep knowledge of the new, significantly more complex, Source API to achieve: - FLINK-28056 [8] In my mind, none of those are blockers for proceeding with adding the @Deprecated annotation: (1) is a simple case of encapsulation, internals should not concern the API users (2) is really only relevant for "exotic" use cases. Does not mean we should not consider those, but since it is irrelevant for 99.9% of the users, I do not think we should get stuck here. (3) is purely a nice to have. Formally speaking, all of the tools are there, it is just that due to the complexity of the new Source API some "simple" things become non-trivial and ideally we want to do better here. [1] https://lists.apache.org/thread/d6cwqw9b3105wcpdkwq7rr4s7x4ywqr9 [2] https://lists.apache.org/thread/kv9rj3w2rmkb8jtss5bqffhw57or7v8v [3] https://issues.apache.org/jira/browse/FLINK-28050 [4] https://issues.apache.org/jira/browse/FLINK-28229 [5] https://issues.apache.org/jira/browse/FLINK-28048 [6] https://issues.apache.org/jira/browse/FLINK-28054 [7] https://issues.apache.org/jira/browse/FLINK-28051 [8] https://issues.apache.org/jira/browse/FLINK-28056 On Thu, 29 Jun 2023 at 13:13, Xintong Song <tonysong...@gmail.com> wrote: > Thanks for the inputs, Martijn, Jing and Alex. > > @Martijn, > Regarding the Scala supports, I personally don't think "a fully striked > through experience in the IDE" is something we want to avoid, especially > given that we are planning to remove the deprecated APIs soon, unlike when > FLINK-29740 was resolved we didn't really know when they would be removed. > Moreover, the even entry point for DataStream Scala > (`StreamExecutionEnvironment`) is not annotated. > > > @Jing and @Alex, > > IIUC, you mean SourceFunction can be annotated as `@Deprecated` in 1.18, > and there's already a PR doing so. However, after the deprecation, there > are still issues that need to be addressed before removing it in 2.0? This > sounds a bit weird. If the API cannot be dropped, which means without this > API some of functions cannot be supported, then how could it be deprecated? > How would we expect users to migrate away from it? > > > @Jing, > > Sounds like it's impractical to deprecate SinkFunction in 1.18. Any > expectation / plan on when / how it can be deprecated / removed? > > > Best, > > Xintong > > > > On Thu, Jun 29, 2023 at 6:12 PM Alexander Fedulov < > alexander.fedu...@gmail.com> wrote: > > > Hi Xintong, > > > > Thanks for bringing up this topic. I can provide some details regarding > > the SourceFunction deprecation efforts. Marking SourceFunction as > > deprecated was not possible until now since we have stringent compiler > > checks in flink-examples against using any deprecated APIs. We actually > > merged the migration of all examples to the new FLIP-27-based > > DataGeneratorSource [1] just two days ago [2]. Now the PR marking > > it @Deprecated is finally unblocked [3] (I would be grateful if you could > > merge it). > > > > With regards to the Flink 2.0 scope, I compiled a list of items required > to > > be able to drop the SourceFunction API [4] a while ago and as you can > see, > > there is still quite some work to be done. Some items [5] might even > > require additions to the new Source API. Overall, I am happy to take > > ownership of completing this work package. > > > > Best, > > Alex > > > > > > [1] https://cwiki.apache.org/confluence/x/9Av1D > > [2] https://github.com/apache/flink/pull/21774 > > [3] https://github.com/apache/flink/pull/20049 > > [4] https://issues.apache.org/jira/browse/FLINK-28045 > > [5] https://issues.apache.org/jira/browse/FLINK-28054 > > > > On Thu, 29 Jun 2023 at 10:45, Martijn Visser <martijnvis...@apache.org> > > wrote: > > > > > Hi Xintong, > > > > > > With regards to the deprecation of the Scala APIs, during the PR > > > review it was requested to not mark all APIs as deprecated but only > > > the entry point [1], to avoid a fully striked through experience in > > > the IDE. I think the same idea was applicable on the DataSet API. I > > > think it depends on how formal we want to treat this: if really > > > formal, then we should deprecate them in 1.18. I think in both cases, > > > it's quite well known that they are deprecated. I'm +0 for either way, > > > as long as we're all agreeing that they can be removed in 2.0. > > > > > > With regards to Queryable State and Source/SinkFunction, +1 to mark > > > these as deprecated. > > > > > > Best regards, > > > > > > Martijn > > > > > > [1] > > > > https://github.com/apache/flink/pull/21176#pullrequestreview-1159706808 > > > > > > On Thu, Jun 29, 2023 at 10:23 AM Xintong Song <tonysong...@gmail.com> > > > wrote: > > > > > > > > Hi devs, > > > > > > > > Looking at the release 2.0 proposals [1], I noticed that many APIs > that > > > are > > > > proposed to be removed in 2.0 are not (fully) deprecated yet. We > might > > > want > > > > to properly mark them as `@Deprecated` in 1.18 if we agree they > should > > be > > > > removed in 2.0. Moreover, according to FLIP-321 [2] (not voted yet > but > > > IMO > > > > is close to consensus IMO), a migration period is required after APIs > > are > > > > deprecated and before they can be removed. > > > > > > > > I might not be familiar with the status of all the APIs below. So I'd > > > like > > > > to bring them up and see if there's any concern regarding deprecating > > > them > > > > in 1.18. If there's concern for deprecating API, we can start a > > separate > > > > discussion thread for it. For those with no objections, I'd create > JIRA > > > > tickets and try to properly deprecate them in 1.18. > > > > > > > > 1. DataSet API > > > > It's described as "legacy", "soft deprecated" in user documentation > > [3]. > > > > However, it's not annotated with `@Deprecated` in codes. According to > > > > FLIP-131 [4], DataSet API should be deprecated when DataStream API > and > > > > Table API / SQL meet certain requirements. AFAICS, all the > requirements > > > > mentioned in the FLIP are already fulfilled. We should annotate it as > > > > `@Deprecated` now. > > > > > > > > 2. SourceFunction / SinkFunction > > > > They are described as deprecated in the roadmap[5], and I don't find > > > > anything regarding them in user documentation. But they are also not > > > > annotated with `@Deprecated` in codes. TBH, I'm not aware of any > formal > > > > decision to deprecate these. AFAICS, the replacement for > SourceFunction > > > > (Source) has already been promoted to `@Public`, while the > replacement > > > for > > > > SinkFunction (SinkV2) is still `@PublicEvolving`. I found a > > discussion[6] > > > > regarding promoting SinkV2 to `@Public`, but it's unclear to me what > > the > > > > conclusion is. > > > > > > > > 3. Queryable State > > > > It's described as approaching end-of-life in the roadmap [5], but is > > > > neither deprecated in codes nor in user documentation [7]. I also > > found a > > > > discussion [8] about rescuing it from deprecation, and it seems to me > > > there > > > > are more negative opinions than positive ones. > > > > > > > > 4. All Scala APIs > > > > I think we agreed to drop Scala API support in FLIP-265 [9], and have > > > tried > > > > to deprecate them in FLINK-29740 [10]. Also, both user documentation > > and > > > > roadmap[5] shows that scala API supports are deprecated. However, > > AFAICS, > > > > none of the APIs in `flink-streaming-scala` are annotated with > > > > `@Deprecated`, and only `ExecutionEnvironment` and `package` are > marked > > > > `@Deprecated` in `flink-scala`. > > > > > > > > Looking forward to your feedback. > > > > > > > > Best, > > > > > > > > Xintong > > > > > > > > > > > > [1] https://cwiki.apache.org/confluence/display/FLINK/2.0+Release > > > > > > > > [2] https://lists.apache.org/thread/vmhzv8fcw2b33pqxp43486owrxbkd5x9 > > > > > > > > [3] > > > > > > > > > > https://nightlies.apache.org/flink/flink-docs-master/docs/dev/dataset/overview/ > > > > > > > > [4] > > > > > > > > > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=158866741 > > > > > > > > [5] https://flink.apache.org/roadmap/ > > > > > > > > [6] https://lists.apache.org/thread/q62nj89rrz0t5xtggy5n65on95f2rmmx > > > > > > > > [7] > > > > > > > > > > https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/fault-tolerance/queryable_state/ > > > > > > > > [8] https://lists.apache.org/thread/9hmwcjb3q5c24pk3qshjvybfqk62v17m > > > > > > > > [9] > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-265+Deprecate+and+remove+Scala+API+support > > > > > > > > [10] https://issues.apache.org/jira/browse/FLINK-29740 > > > > > >
