How to start node.js app with pm2 in cluster mode?

Question

We are trying to start our app with pm2 0.12.8 on ubuntu 14.04 with octa core proccessor. The read me on the git hub has a very straight forward command for running node app in cluster mode.

# Cluster mode

$ pm2 start app.js -i 0        **# Will start maximum processes with LB depending on available CPUs**
$ pm2 start app.js -i max      **# Same as above, but deprecated yet.**

But the above command are not working for us. When we try to run these commands only one instance is listed by pm2.

Why? Any suggestion

Thanks

Answer 1

Since you are looking to use a process file to manage your pm2, the process file should look similar to this:

    // ecosystem.js
    {
    "apps" : [{
      "name"      : "API",
      "script"    : "server.js",// name of the startup file
      "instances" : 4,          // number of workers you want to run
      "exec_mode" : "cluster",  // to turn on cluster mode; defaults to 'fork' mode 
      "env": {
        "PORT"      : "9090" // the port on which the app should listen
      }
      // for more options refer : http://pm2.keymetrics.io/docs/usage/application-declaration/#process-file
    }]
    }

Run this app using the following command to start and stop respectively:

$ pm2 start ecosystem.js
$ pm2 stop ecosystem.js

Answer 2

have you tried starting a fixed number of processes? i.e.

pm2 start app.js -i 2 //should start two instances.

what does "pm2 monit" show you?

also try

pm2 stop all
pm2 delete all 

and then

pm2 start app.js -i 0

if you stop a process in pm2 it still reserves one cpu for it even if its not running. you should allways use pm2 delete