Dear whiskers. Currently, an invoker rejects an activation with an outdated action. This can happen in the following situations.
1. Stale activations are sent to invokers. This is a case where Kafka could not send some activations in time and the action codes are updated in the meantime. It can happen when a target invoker fails for some reason. When the invoker becomes healthy again, it can receive the outdated activations. 2. The underlying action of a sequence action is updated while the sequence action is running. In case a sequence action includes long-running actions, the underlying actions can be updated while the sequence action is still running. In both cases, invokers receive outdated actions and it rejects them due to revision mismatch. @upgle opened a pull request to address this issue. https://github.com/apache/openwhisk/pull/4954 The main change is to take the latest codes as a fallback when the revision mismatch occurs. Since this could be a kind of semantics change as an activation would successfully run which would have been rejected with the current code, please share your opinion. I approved the PR with a warning log denoting the revision mismatch happens. Since it already has been open for some time, I would merge it in 72 hours. Regards Dominic.
