Running Node.js App with cluster module is meaningless in Heroku?

Question

Heroku can run

Web Dynos

and

Worker Dynos

so that Web Dynos take care of routes

and worker Worker Dynos take care of processing works.

Since there is a unit of Dyno,

It seems using Node.js cluster module is meaningless to me on Heroku.

Because Node.js cluster module is to use all cores of server CPU

and Dyno seems virtual unit of CPU core to me.

Am I right? Or is it still worth to run a node.js app with cluster module?

Answer 1

I've found that it actually worth to use cluster module

because each dyno has 4 CPU cores.

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Reference: http://www.quora.com/Heroku/How-powerful-is-one-Heroku-dyno

Answer 2

This is an old question, thought I should update to a more complete answer.

According to this table on their documentation

• 1X Dynos have 1 cluster
• 2X Dynos have 2 clusters
• PX Dynos have 12 clusters

So, assuming that you are using 1X dynos, it won't be necessary to implement clusters. If you are using the other ones, it is a good idea to do so.

The number of clusters can be found on the WEB_CONCURRENCY environment variable.

Answer 3

That's very good news to me, i assumed that a dyno is just one core. I actually wrote and open sourced a small but very nicely made cluster setup (backed by redis and job queue)

https://bitbucket.org/jeveloper/nodejscluster