Scaling Node.js Applications

Scalability in Node.js is not reconsideration. It is carried out at the centre of the runtime. Node is named Node to highlight the idea that a Node application should ought to include various little disseminated nodes that can communicate to each other. Cluster module of Node not only provides an out of the box solution to use the compleet CPU power of a machine, but it also helps with increasing the availability of Node processes and provides an option to restart the whole application with a zero downtime.

Strategy of scaling the Node.js Applications-

Horizontally Scaling your App- 

Horizontal scaling comes to duplicating.

Shorly, you duplicate application instance, and this enables it to “cope with” a large number of incoming connections.

do remember, however, that this scaling solution may include pointless complexity to app’s infrastructure; it may involve the need to provide and maintain a load balancer, might make troubleshooting more challenging and change the way of deployment of your application. Ensure that it is particularly this Node.js scaling solution that your projects needs before you go a step forward and implement it.

Vertical Scaling-

If your scalability architecture needs involve only than:

  1. injecting more power 
  2. adding more memory

with no particular changes applied to the code, then vertical scaling be an option for you to scale the application.

The Cluster module-

The cluster module is used to enable load balancing over an environment’s multiple CPU cores. It is based on the child process module fork method. This basically allows us to fork the main application process as many times as we have CPU cores. It will then take over and load balance all requests to the main process across all forked processes. Cluster module makes setting up child processes sharing server ports conveniently easy.


one “master” process will be in charge with spawning all the child processes (and there’s one “worker” for each core), those that actually run your Node.js app.

Limitations of the basic scaling solution- 

  1. in case one of your child processes “dies”, it doesn’t… regenerate itself
  2. you’ll need to handle the master-worker processes difference… the “old school way”, using an “if-else” block
  3. there’s no way of modifying multiple processes, at once, on-the-fly!

Following code would enable the master process to… respawn the “worker”:

cluster.on(‘exit’, (worker, code, signal) => {



How to Scale Your Node.js App-


We can scale an application by decomposing. It is based on functionalities and services. This means having multiple applications with different code bases and sometimes with their own dedicated databases and user interfaces. Microservice is another name of Decomposing. Whereas Micro indicates that, these services should be as small as possible. But in reality, the size of the service is not what’s important but instead of the enforcement of loose coupling and high cohesion between services. Implementation of this strategy is not easy. It could result in long-term unexpected problems. But is it done correctly, its advantages are great.


Cloning is the easiest strategy for solving your problem of ‘How to scale the Node.js app?’ Here, you just need to clone your  Node.js back-end application, multiple times and assign a particular part of the workload to each cloned instance! It is effective and cost-effective. Cluster module of Node makes cloning on a single server ideally easy to implement! You have such various strategies to choose from, depending on your scaling needs.


We can also split the application into multiple instances where each instance is responsible for only a part of the application’s data. This strategy is named as horizontal partitioning or shading in databases. Data partitioning requires a lookup step before each operation to determine which instance of the application to use. For eg.,You want to partition your users based on their country or language. We need to lookup of that information first. Effectively, scaling a big application should implement all these three strategies. Node.js makes it easy to do this. Ensure that, you need a good understanding of Node.js child processes.

Upgrade your knowledge with the new features of Node 8 at- Node 8: Six New Features You must Know

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