On the issue of delivery ... can Pulsar users here talk about exactly once message delivery from the consumer side?

I use Kafka and needed a cache based on incoming events which were partitioned.

But if the consumer crashes it's not easy to pick up from exactly where it left off without manually committing offsets which hurts performance. There's also some hand waving Kafka gossip that it's hard to commit offsets right. Further suppose a task consumes events from topic A partition 3, produces events to topic B. Again, if the task crashes it's not clear what needs replaying in order to not to lose messages (on write) or missing messages (on read).

Any insight here is greatly appreciated.