backpressure

Backpressure Middleware

What it does

Rejects or slows request admission when queue or worker saturation indicates that the service cannot safely accept more work.

How to implement

package main

import (
	"github.com/oarkflow/fh"
	"github.com/oarkflow/fh/mw/backpressure"
)

func main() {
	app := fh.New()
	app.Use(backpressure.New(backpressure.Config{}))

	app.Get("/", func(c fh.Ctx) error {
		return c.Status(fh.StatusOK).SendString("ok")
	})
}

Impact

Prevents unbounded memory growth and protects downstream durable queues. It can return 503/429 instead of allowing the process to overload.

Ordering guidance

Place before endpoints that enqueue background work. Combine with load shedding and retry-after responses.

Production considerations

Set thresholds according to queue depth, lag, and worker capacity. Monitor rejection counts, queue lag, and DLQ growth.