What is the Funnel component in NiFi and when do you use it?

A Funnel is a NiFi canvas component that merges FlowFiles from multiple incoming connections into a single outgoing connection. It has no processing logic — it is purely a flow topology tool for consolidating multiple data paths into one without introducing a processor's overhead, scheduling, or threading.

Common use cases:

Convergence after parallel processing: If you fan out a FlowFile through RouteOnAttribute to three different processing paths and all paths should eventually flow to the same downstream processor, a Funnel cleanly merges the three paths into one without requiring the downstream processor to have multiple input connections from different sources.

Canvas layout organization: Multiple processors feeding the same downstream path can first converge at a Funnel, reducing the number of long crossing connections on the canvas and improving readability.

Failure consolidation: Multiple processors' failure relationships can all connect to a single Funnel, which routes to a centralized error-handling path. This avoids duplicating error-handling connections from every processor to the same destination.

A Funnel differs from a Processor in that it has no scheduling, no concurrent task setting, no relationships (besides its one output), and no configuration properties. FlowFiles pass through it transparently and immediately. It also differs from a connection in that it can accept connections from any number of sources.