Tracking delivery of events to Saga's (that seem not be delivered)

We are in a situation where a Saga is created and milliseconds later new events arrive for the Saga. This happens for a lot of Saga’s in a short amount of time. There was 1 Saga that, roughly, should have received 30 additional events but only seems to have received the last 10.

We are not sure if our application logic could be buggy or that Saga’s sometimes need some time to be created and handle new events. Our use case requires guaranteed delivery of events to a Saga. But maybe this is not possible?

We would also like a way to log when events for Saga’s are published, but never delivered. Is that possible? We are using version 4.6.7 of the Axon Framework.

There was caching on the Saga and we removed it. The one with the weak-reference implementation. We also block the incoming events for 1 second right after a Saga is created. We hope that this will help. We are not able to reproduce the problem, but we are really unsure why the events did not arrive at the Saga.

Later we found out there was another Saga with the same problem, so we could not do nothing.

We did this “fix” now because we are also doing some overdue upgrades to Springboot3, Java17 and Axon 4.7.