How to Scale Redis Pub/Sub Across Multiple VPS Nodes for Faster Performance

I enjoy using Redis Pub/Sub because it is quick, simple, and fun to scale. Moving from one VPS to many VPS servers makes it feel like you are building your own massive message system. If you have ever questioned doing this without your system slowing down, here is an easy explanation.

Why Redis Pub/Sub Needs Scaling​

When you send a ton of messages with Redis Pub/Sub everything is unbelievably quick. At some point, you may think, "Can I push this further?" I did too.

Redis Pub/Sub is great, but:

• It does not retain messages
• It does not resend messages
• One server cannot process extremely heavy traffic

This is why you need many VPS nodes.

How many VPS Nodes Will Help​

Once I have separated out the work across many VPS servers, everything is smoother.

You will get:

• Faster
• Better stability
• Fewer lost messages

This is how you scale it:

1. Use Redis Clustering​

A Redis Cluster takes the job and breaks it down into many pieces. Each data server manages a small piece of data.

The benefits of this, are:

• More total speed
• Automatic data splitting
• Faster work on heavy load

But just using a cluster isn't enough for Pub/Sub, it's time to add the next step.

2. Add a message broker layer​

Using tools like Redis Streams, NATS, and Kafka will help control messages between nodes servers.

These tools act like "traffic police" and direct messages to the correct users.

You’re going to get:

• More control of messages
• Better delivery
• Less chance of message loss

These are much better than using a simple Pub/Sub with multiple servers.

3. Load Balancers for VPS Nodes​

I use HAProxy or Nginx to manage connections among VPS nodes.

This is to avoid one server getting hammered while others are waiting on idle.

Benefits:

• Load is evenly balanced
• Better uptime
• Have a path for backups in the event of a node failure

4. Monitor Everything!​

I know, monitoring sounds boring - but it starts saving you later!

I use tools like Prometheus and Grafana that give me the ability to monitor:

• Latency
• Lost messages
• CPU load

If you are not monitoring, do not forget, it will eventually break!