Thanks for the KIP, Séamus! I agree that the current situation you’re describing doesn’t seem ideal, and it’s probably worth a slight behavior change to fix it.
It’s too bad that we introduced that placeholder record, since it seems less error prone for users if we have the invariant that exactly one argument is non-null. I’m concerned (as reported in KAFKA-7412) that people could mistake the placeholder for a successful ack. Since we’re considering some breakage to fix this inconsistency, did you consider just going back to the original behavior? Although it’s technically an implementation detail (which doesn’t need to be in a KIP), I like the fact that you’re planning to refactor the code to enforce consistent handling of the callbacks. Thanks, John On Thu, Nov 11, 2021, at 07:25, Séamus Ó Ceanainn wrote: > Hi, > > As outlined in KIP-799: Align behaviour for producer callbacks with > documented behaviour > <https://cwiki.apache.org/confluence/display/KAFKA/KIP-799%3A+Align+behaviour+for+producer+callbacks+with+documented+behaviour>, > there is an inconsistency between the documented behaviour and > implementation of producer callbacks for the Kafka client. The KIP > proposes > breaking changes to the implementation of the Kafka producer client to > align the implementation with the documented behaviour, and includes a > link > to a PR containing a tested implementation of the changes being > recommended. > > There is a need to take action here as a breaking change was previously > introduced accidentally, and the documentation was later updated to try to > reflect those breaking changes. I believe the main discussion here is > around the most appropriate behaviour for callbacks, which will inform > whether the implementation, documentation or a combination of both should > be updated. Right now, the documented behaviour aligns closely with the > implementation of ProducerInterceptors, and as a result I would favor > keeping the documented behaviour and updating the implementation to match, > as that would provide greater consistency between Callbacks and > Interceptors implementations for producers. > > Regards, > Séamus.
