EADDRINUSE Exception in node js while cluster.fork()

[abhay12]

I am running Node.js in EC2 instance, and sometimes while restarting the EC2, I am getting an EADDRINUSE error. I am using cluster.fork() to fork the process on the number of CPUs.

The main problem in my use case is, I am not able to replicate this scenario locally. This is coming very frequently in EC2 when auto-deployment happens.

Can someone help me understand what is causing the issue here?

I am suspecting that cluster.fork() is creating the problem.

Code:

if(cluster.isMaster){
 var num = require('os').cpus().length;
 for(int i=0; i<num; i++){ 
    cluster.fork();
 }
}

PS: I know this error comes when the port is already occupied and we can manually kill the process using the command. but that solution will not work here. When we deploy, we get a new instance hence and we check the port availability so chances are very very less that port is already occupied by some other service.