Notify Adapters

Notify adapters handle pub/sub notifications for efficient job scheduling. When a job is created, workers are notified immediately instead of polling. This reduces latency from seconds to milliseconds.

Package: @queuert/redis

Recommended for production. Uses Redis pub/sub for broadcasting job notifications to workers. Includes a hint-based optimization using Lua scripts for atomic decrement, preventing thundering herd when many workers are idle — only as many workers as there are new jobs will query the database.

npm install @queuert/redis

Supported clients

Client	Example
node-redis	notify-redis-redis
ioredis	notify-redis-ioredis
node-redis cluster	notify-redis-cluster-node-redis
ioredis cluster	notify-redis-cluster-ioredis

Package: @queuert/nats Experimental

Uses NATS pub/sub for job notifications. When JetStream KV is available, supports revision-based CAS operations for hint-based optimization.

npm install @queuert/nats

Client	Example
nats	notify-nats-nats

Package: @queuert/postgres

Uses PostgreSQL’s built-in LISTEN/NOTIFY mechanism. No additional infrastructure beyond your existing PostgreSQL database. All listeners query the database on notification (no hint-based optimization).

npm install @queuert/postgres

Supported drivers

Driver	Example
pg	notify-postgres-pg
postgres.js	notify-postgres-postgres-js

Built-in — no extra package. Imported from queuert.

Delivers job-arrival signals via in-memory subscriptions. Useful whenever publisher and subscriber run in the same process. Single-process only — workers in other processes won’t receive notifications.

import { createInProcessNotifyAdapter } from "queuert";

const notifyAdapter = await createInProcessNotifyAdapter();

Notify Provider

A Notify Provider bridges your pub/sub client (Redis, NATS, PostgreSQL, etc.) with the notify adapter. You implement an interface for publishing messages and subscribing to channels:

publish — Sends a message to a named channel.
subscribe — Listens on a channel and invokes a callback when messages arrive. Returns a dispose function to unsubscribe.

The provider maintains a dedicated connection for subscriptions and acquires/releases connections for publish operations automatically. Each example linked above demonstrates a complete Notify Provider implementation for its corresponding client.

You’re not limited to the clients listed here — you can write a provider for any pub/sub client that supports the same semantics, or implement the NotifyAdapter interface from scratch for an entirely different message broker. See Custom Adapters for a walkthrough.

Verify your provider

Queuert ships a conformance runner that exercises the 18-case notify adapter suite against any provider you build. Embed it in a single test() block from your test framework to validate correctness:

import { runNotifyAdapterConformance } from "queuert/conformance";

test("my provider passes notify adapter conformance", async () => {
  await runNotifyAdapterConformance(async () => ({
    notifyAdapter,
    dispose: async () => { /* close connections */ },
  }));
}, 60_000);

Every example’s src/provider.spec.ts is a working template. See the Custom Adapters guide for a full walkthrough and the Conformance reference for the complete API.