Questions
8 of 17
1How does the Node.js Cluster module work internally?
2What is the difference between the master process and a worker process in Node.js clustering?
3How do you send messages between master and worker processes in a Node.js cluster?
4What are the two load balancing strategies in Node.js cluster, and how do you configure them?
5How does clustering differ from using Worker Threads in Node.js?
6How would you monitor the health of worker processes in a Node.js cluster in production?
7What is clustering in Node.js, and why is it needed?
8How do you check if the current process is a master or worker in Node.js?
9How do workers in a Node.js cluster share a port without conflict?
10Can workers share memory or state in a Node.js cluster?
11What are the limitations of Node.js clustering?
12Your Node.js server handles 10,000 concurrent users but is slow. How does clustering help?
13What happens when a worker process crashes in a Node.js cluster?
14How do you gracefully shut down a worker in Node.js clustering?
15What is the difference between cluster.fork() and child_process.fork()?
16How do you implement sticky sessions with Node.js clustering?
17What is PM2 and how does it relate to Node.js clustering?
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Basics
Event Loop
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Time functions
Clusters
Crypto
Modules
Worker Threads
File Operations
Threads
Performance Optimisation
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How do you check if the current process is a master or worker in Node.js?

You can use cluster.isPrimary (or the deprecated cluster.isMaster) to check if the current process is the master, and cluster.isWorker to check if it is a worker process.

The cluster module exposes boolean properties that let you branch your code logic based on whether the current process is the primary/master or a worker. This is the foundational pattern used in every cluster-based Node.js application.

Checking Process Type
Important Notes
  1. 1

    cluster.isPrimary is the modern property introduced in Node.js v16.0.0

  2. 2

    cluster.isMaster is deprecated but still functional in older codebases

  3. 3

    cluster.isWorker is the complement of cluster.isPrimary

  4. 4

    process.pid gives the OS-level process ID for both master and workers