Thanks Hongshun for starting this discussion. +1 from my side.
IIRC, @Jiangjie(Becket) also mentioned this in FLINK-31324 comment[1]. Best, Leonard [1] https://issues.apache.org/jira/browse/FLINK-31324?focusedCommentId=17696756&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17696756 > 2023年11月8日 下午5:42，Hongshun Wang <loserwang1...@gmail.com> 写道： > > Hi devs, > > I would like to start a discussion on FLIP-389: Annotate > SingleThreadFetcherManager and FutureCompletingBlockingQueue as > PublicEvolving.[ > <https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=278465498> > 1]. > > Though the SingleThreadFetcherManager is annotated as Internal, it actually > acts as some-degree public API, which is widely used in many connector > projects: flink-cdc-connector > <https://github.com/ververica/flink-cdc-connectors/blob/release-2.3.0/flink-connector-mysql-cdc/src/main/java/com/ververica/cdc/connectors/mysql/source/reader/MySqlSourceReader.java#L93> > , flink-connector-mongodb > <https://github.com/apache/flink-connector-mongodb/blob/main/flink-connector-mongodb/src/main/java/org/apache/flink/connector/mongodb/source/reader/MongoSourceReader.java#L58> > and > soon. > > Moreover, even the constructor of SingleThreadMultiplexSourceReaderBase > (which is PublicEvolving) includes the params of SingleThreadFetcherManager > and FutureCompletingBlockingQueue. That means that the > SingleThreadFetcherManager and FutureCompletingBlockingQueue have already > been exposed to users for a long time and are widely used. > > Considering that all source implementations are using them de facto, why > not annotate SingleThreadFetcherManager and FutureCompletingBlockingQueue > as PublicEvolving so that developers will modify it more carefully to avoid > any potential issues. As shown in FLINK-31324[2], FLINK-28853[3] used > to change the default constructor of SingleThreadFetcherManager. However, > it influenced a lot. Finally, the former constructor was added back and > marked as Deprecated。 > > In conclusion, the goal of this FLIP is to annotate > SingleThreadFetcherManager(includes its parent class) and > FutureCompletingBlockingQueue as PublicEvolving. > > Looking forward to hearing from you. > > > [1] > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=278465498 > > [2] https://issues.apache.org/jira/browse/FLINK-31324 > > [3] https://issues.apache.org/jira/browse/FLINK-28853
