Backpressure

You might say

When downstream processing cannot keep up, do not let the queue and memory grow forever. Slow or pause the upstream and resume after recovery.

Backpressure sends a downstream slowdown or pause signal upstream to limit new or unfinished workIf an image-processing service can finish only a small number of tasks per second while uploads keep arriving, queue length and memory grow without backpressure. The system can slow or pause publishing, or cap unacknowledged work, then resume when capacity recovers. Backpressure is not extra capacity and is not a fixed rate limit independent of downstream state.

Why send a downstream slowdown back to the upstream?

Event-processing queue10,000 msg/s

producerkeeps full speed

consumerhandles 2,000/s

queue memorykeeps growing

EvidenceInput rate stays above processing rate

Without feedback, pending work fills memory.

Backpressure makes work follow processing capacity

Problem and key mechanism: When uploads outpace image processing, queue length, unfinished work, and memory rise; when downstream slows or reaches its limit, the system sends that feedback upstream so the producer slows down, pauses, or temporarily stops accepting work.

Judge improvement by recovery evidence: After a simulated peak, queue and memory should stay bounded and publishing should resume when capacity returns. Backpressure does not add capacity or become a fixed rate rule.

Financial report exports also need backpressure: During a bulk report export, data reading may outpace file writing. As the writer nears its capacity limit, it tells the reader to pause and resume after space is available, preventing the export process from exhausting memory as its buffer grows.

You can say this to an AI Agent

Add backpressure to the image-processing path: when downstream processing slows or unfinished work reaches its limit, pause or slow the upstream; resume after recovery. Simulate uploads faster than processing and verify that queue and memory do not grow without bound, with trigger and recovery feedback recorded.

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Image processing is slower than uploads, and queue length and memory are rising. Which change uses backpressure?

A. Only make the queue larger so more work can accumulate in memoryB. Permanently give every user the same fixed rate regardless of downstream stateC. Pause or slow publishing based on downstream capacity, and cap unfinished work