implement mutex in node.js

Question

I would like to implement a mutex inside my node.js application, here is the mutex in wiki http://en.wikipedia.org/wiki/Mutual_exclusion.

Is there any ready module f

Answer 1

There are many ways to accomplish this. Two easy ways are via Redis or Zookeeper servers. Node.js has very good modules for both of them.

In Redis you can use WATCH + MULTI commands to implement locking. In Zookeeper you can create ephemeral nodes. In both way no two processes will execute the critical operation at the same time.

I have recently implemented Redis approach in a node-ratelimiter module which is a critical part of our production applications where we need to guarantee no two processes increment the same value in Redis. Refer to WATCH and MULTI for details. The code is in fact very easy to understand and read.

For Zookeeper example, refer to Locks Recipe. It is possible to implement much more complex logic for distributed locks with Zookeeper ephemeral nodes. Redis solution is just a special case and works very well if you don't need more than that.

Using these two approaches you can implement mutexes for any app and any logic.