Memory usage

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.

Exercise Check if heapTotal is positive

Store process.memoryUsage() in a variable. Log usage.heapTotal > 0.

Show example solution

const usage = process.memoryUsage();
console.log(usage.heapTotal > 0);

Test yourself

Match each piece to its role

rss

Resident set
heapTotal

Total heap
heapUsed

Used heap
external

External memory

Complete the method name

const usage = process.____()

Show answer

const usage = process.memoryUsage()

What does process.memoryUsage() return?
- Bir dize
- Bir Promise
- Bellek nesnesi
- A number
Show answer

Bellek nesnesi — process.memoryUsage() returns an object with memory fields.

Next lesson: CPU profiling

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