Scale Your Node.js Application: Best Strategies and built-in tools for Scalability

Whether it's an increasingly demanding workload or you simply want to improve your Node.js application's fault tolerance and availability, there comes a time when you just need to scale it up, right? To "squeeze" the best performance out of your entire infrastructure. Here's how to scale your Node.js application:

And scaling your web back-end application at different levels – an overall improvement across the board – is certainly not an afterthought with Node.js:

"Scalability is built into the very core of the runtime."

And the infrastructure of nodes, strategically placed and communicating with each other, is what makes this framework particularly scalable.

What are the most powerful built-in scalability tools to explore and "exploit"? And what are the best strategies depending on your specific scenario and the needs of a scalable architecture?

Node.js App: Horizontally Scaling

You are essentially duplicating your application instance and allowing it to "deal" with more incoming connections.

Note: You can scale your Node.js application horizontally either on different machines or on a single multi-core machine.

Warning: keep in mind, however, that this scaling solution may unnecessarily complicate your application infrastructure; it can mean having to provision and maintain a load balancer, make troubleshooting more difficult, and even change the way you deploy your application.

That being said: 

"make sure your project specifically needs this Node.js scaling solution before you start implementing!"

Node.js App: Vertically Scaling

If your scalability architecture needs nothing more than:

1. Injection of more force
2. Adding more memory

without any special “tweaking” of the code, vertical scaling can be the right answer to the “how to scale your Node.js application” dilemma.

Here's why:

• By default, Node will not use more than 1.76 GB of memory on 64-bit machines
• For example, in the case of a machine with 32 GB of RAM, a Node process will be limited to only a fraction of its memory

Multiple processes running on the same machine

Here is another possible answer to your question "How to scale a Node.js application":

Having multiple processes running on the same port.

Obviously, this scaling solution requires some sort of internal load balancing to distribute incoming connections across the entire ecosystem of cores/processes.

Attention!

Not sure if this needs to be added: keep the number of running processes lower than the number of cores!

Next, we'll focus on 2 built-in Node.js tools for scalability that you might want to take advantage of:

Cluster Module

The Node cluster module is a great starter for scaling your application on a single machine.

How exactly does it work?

"This makes setting up child processes to share server ports conveniently easy."

Practically, one "master" process will be in charge of spawning all child processes (and there is one "worker" for each core), the ones that actually run your Node.js application.

However, there are some limitations to this basic scaling solution:

1. In case one of your child processes "dies", no...it regenerates itself
2. You will have to handle the difference between master-worker processes... "old school" with an "if-else" block
3. There is no way to edit multiple processes at once, on the fly!

Cluster module PM2

Using the PM2 cluster module, the dilemma of "how to scale a Node.js application" turns into:

"Relax and let PM2 to cluster your server for you!"

All you have to do is "run" the superpower of this command:

pm2 start app.js -i 4 –name="api"

It will instantly create a 4 node cluster for you!

Here are some more details about what happens "under the hood" during this process:

• The PM2 daemon will take over the former role of "master process" and create N processes (formerly "worker processes"), relying on circuit balancing
• In addition, if you use the PM2 process manager, your process automatically scales across all existing cores (no need to run the cluster module anymore)
• The same PM2 process manager also ensures that processes are restarted immediately if they happen to crash

Just write your Node.js application as if it were for single-core use, and the PM2 module takes care of scaling it for multi-core.

Note: If you want to further scale your Node.js application now, you may want to consider deploying multiple machines…

How to scale your Node.js application: 3 scaling strategies to consider:

1. Decaying

"Microservice" is another word for this scaling strategy. In practice, you'll be "juggling" multiple microservices (although their size doesn't really matter).

Or multiple applications with different codebases (and in many cases each with its own user interface and dedicated database).

And you will be decomposing/scaling your Node.js application using services and functions. A strategy that can lead to unexpected problems in the long run, but which, if implemented correctly, will translate into clear benefits for the performance of your applications.

2. Splitting

Or "horizontal division" or "sharding" if you want. This strategy involves splitting your application into multiple instances, each of which is responsible for one specific piece of your application's data!

Warning: data partitioning requires a lookup before each operation; this way you identify the correct application instance to use.

Take this example here:

You may want to segment Node.js users by language or area of ​​interest. In this case, the search step is a must; you will need to check this information first.

3. Cloning

And this is the easiest strategy to solve your "How to scale a Node.js application" dilemma!

Just clone your Node.js back-end application multiple times and assign a specific part of the workload to each cloned instance!

It's efficient and cost-effective!

Additionally, Node's cluster module makes it ideal to easily implement cloning on a single server!

And this is "How to scale your Node.js application"! See? You have not one but several built-in Node.js tools at your fingertips and different strategies to choose from depending on your scaling needs.