A Gentle Note on Backpressure

When a fast producer meets a slow consumer, something has to give. The question is what — and backpressure is how a well-behaved system answers it.

Three honest options

1. Buffer — absorb the spike, until memory says no.
2. Drop — shed load deliberately, and admit it in your metrics.
3. Slow down — push back on the producer so it eases off.

Each is a trade-off. The mistake is pretending you didn't make one.

async function* throttle<T>(src: AsyncIterable<T>, max: number) {
  let inFlight = 0
  for await (const item of src) {
    while (inFlight >= max) await tick()
    inFlight++
    yield item
  }
}

The systems I trust most are the ones that are honest about their limits.