This manual is for an old version of Hazelcast Jet, use the latest stable version.

The processor deposits the items it wants to emit to an instance of Outbox, which has a separate bucket for each outbound edge. The buckets are unbounded, but each has a defined "high water mark" that says when the bucket should be considered full. When the processor realizes it has hit the high water mark, it should return from the current processing callback and let the execution engine drain the outbox.