Don't let a billion RAG docs drown your 25-result pipeline

Backpressure For Streaming Pipelines

Last time we showed how to terminate non-cooperative CPU work at the worker boundary. This article stays cooperative but adds the missing piece: backpressure, the runtime contract that lets a producer pause the moment the consumer can't keep up.

A RAG ingest pipeline has a billion candidate documents. You only need the 25 that match a downstream filter. A naive promise collection can materialize far more work than the consumer needs; a hand-rolled async iterator can still fill a prefetch buffer before the first result arrives. With WorkIt:

import { work } from "@workit/core";

async function* billionDocuments() {