Backpressure

The Pattern

When a producer outruns its consumer, something, somewhere, must give: a buffer fills, data drops, or the producer slows. Backpressure is choosing which and where on purpose: and propagating the consumer's "slow down" signal upstream: instead of letting the default choice (an unbounded buffer) make itself, as an outage, later.

You've brushed against this pattern three times: the bidirectional lesson's slow phone eating a gateway's memory, the queue lesson's depth as the honest metric, the [rate limiter's](