Memory usage
- Node.js course
- Advanced
- Lesson 15/83
- 5 min
Learn memory usage with process.memoryUsage.
process.memoryUsage()
process.memoryUsage() returns the process's memory usage as an object. It has four main fields: rss (Resident Set Size — total allocated memory), heapTotal (V8 heap total), heapUsed (V8 heap used), external (C++ objects).
These are numbers in bytes. To detect memory leaks you can log them at regular intervals. If heapUsed keeps growing you may have a leak.
Detecting memory leaks
A memory leak is when unused objects are not garbage collected. Over time heapUsed grows and the process crashes.
Detection method: log process.memoryUsage().heapUsed every second with setInterval. If it trends upward you have a leak. In Node.js you can take a heap snapshot in Chrome DevTools with the --inspect flag. This lets you visually find leaking objects.
Practice Check if heapTotal is positive
Store process.memoryUsage() in a variable. Log usage.heapTotal > 0.
Starter code
// get memory usage
// log if heapTotal is positiveSample solution
const usage = process.memoryUsage();
console.log(usage.heapTotal > 0);Expected output
true
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match each piece to its role
| Term | Meaning |
|---|---|
rss |
Resident set |
heapTotal |
Total heap |
heapUsed |
Used heap |
external |
External memory |
2 Complete the method name
const usage = process.____()const usage = process.memoryUsage()Explanation: process.memoryUsage() gives memory usage.
3 What does process.memoryUsage() return?
- Bir dize
- Bir Promise
- Bellek nesnesi Correct answer
- A number
Explanation: process.memoryUsage() returns an object with memory fields.