PM2 cluster mode - Jobs are duplicated

Hi,

I run my application in cluster mode with pm2 pm2 start -i 4 myApp.js

I see that the jobs is executed 4 times, normal, but is it a way to prevent the duplication of the jobs ?

Thanks.

[Jahnux]

I’ve pass through this problem in using the instance number of the process environment, without any requirements.

In my case it does the job, look at this :

( the appis my nodeApplication (express) )

        this.app.isMainCluster = parseInt(process.env.NODE_APP_INSTANCE) === 0;

	if (this.app.isMainCluster || this.app.env === 'dev') {
		console.log('IS THE MAINN INSTANCE');
		_.each(this.cronJobs, cronJob => {
			cron.schedule(cronJob.timing, cronJob.job);
		});
	}

[anjarulrobin]

I have faced the similar problem. Then to solve the issue i have configured my pm2.json as (here script is your startup file name)

{
    "apps": [
        {
            "script": "bootstrap.js",
            "instances": "1",
            "exec_mode": "cluster",
            "combine_logs": true,
            "name": "primary",
            "out_file": "./logs/out.log",
            "error_file": "./logs/error.log",
            "env_production": {
                "name": "prod-primary",
                "PORT": 3661,
                "NODE_ENV": "production"
            },
            "env_development": {
                "name": "develop-primary",
                "PORT": 3660,
                "NODE_ENV": "development"
            }
        },
        {
            "script": "bootstrap.js",
            "instances": "-1",
            "exec_mode": "cluster",
            "combine_logs": true,
            "name": "replica",
            "out_file": "./logs/out.log",
            "error_file": "./logs/error.log",
            "env_production": {
                "name": "prod-replica",
                "PORT": 3661,
                "NODE_ENV": "production"
            },
            "env_development": {
                "name": "develop-replica",
                "PORT": 3660,
                "NODE_ENV": "development"
            }
        }
    ]
}

Here i have passed two apps in apps array, and used quite similar configuration except the name of the instance. exec_mode is cluster so that all the instances can share the same port. Now if we run the project using the command pm2 start pm2.json Then you will find process.env.name = “primary” or “replica” in your projects code. Then it’s your choice on which process you will run the cron jobs. You can also run in production mode. to do so you will have to run the command pm2 start pm2.json --env production Then you will get process.env.name = “prod-replica” or “prod-primary”.

Now in code, if you want to check the process name without knowing on which environment the code is running you can name the instances as “something-primary” and “something-replica” for both your development or, then in your code simply use regular expression to be confirmed on which process the cron job should execute.

And you can also scale up your replica instance without any problem.