bulkhead

Bulkhead Middleware

What it does

Limits concurrent execution globally or by key, isolating expensive routes, tenants, or dependencies so one hot path cannot consume the whole server.

How to implement

package main

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

func main() {
	app := fh.New()
	app.Use(bulkhead.New(bulkhead.Config{MaxConcurrent: 128}))

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

Impact

Improves fault isolation. Excess requests are rejected instead of increasing latency for every request.

Ordering guidance

Place around expensive route groups or before handlers that call constrained dependencies. Use route-level bulkheads for high-cost operations.

Production considerations

Tune limits per dependency capacity. Expose metrics for in-flight, accepted, and rejected requests. Combine with timeouts and circuit breakers.