pprof support for Node.js

[![NPM Version][npm-image]][npm-url]
[![Build Status][build-image]][build-url]
[![Known Vulnerabilities][snyk-image]][snyk-url]

[pprof][pprof-url] support for Node.js.

Prerequisites

1. Your application will need to be using Node.js 18 or greater.

2. The pprof module has a native component that is used to collect profiles
with v8's CPU and Heap profilers. You may need to install additional
dependencies to build this module.
* pprof has prebuilt binaries available for Linux arm64/x64,
Alpine Linux x64, macOS arm64/x64, and Windows x64 for Node 18/20/22/24/25.
No additional dependencies are required.
* For other environments: on environments that pprof does not have
prebuilt binaries for, the module
node-gyp will be used to
build binaries. See node-gyp's
documentation
for information on dependencies required to build binaries with node-gyp.

3. The [pprof][pprof-url] CLI can be used to view profiles collected with
this module. Instructions for installing the pprof CLI can be found
[here][pprof-install-url].

Basic Set-up

Install [pprof][npm-url] with npm or add to your package.json.
``sh
# Install through npm while saving to the local 'package.json'
npm install --save @datadog/pprof
`

Using the Profiler

$3

#### In code:
1. Update code to collect and save a profile:
`javascript
const profile = await pprof.time.profile({
durationMillis: 10000, // time in milliseconds for which to
// collect profile.
});
const buf = await pprof.encode(profile);
fs.writeFile('wall.pb.gz', buf, (err) => {
if (err) throw err;
});
`

2. View the profile with command line [pprof][pprof-url]:
`sh
pprof -http=: wall.pb.gz
`

#### Requiring from the command line

1. Start program from the command line:
`sh
node --require @datadog/pprof app.js
`

2. A wall time profile for the job will be saved in
pprof-profile-${process.pid}.pb.gz. View the profile with command line
[pprof][pprof-url]:
`sh
pprof -http=: pprof-profile-${process.pid}.pb.gz
`

$3


1. Enable heap profiling at the start of the application:
`javascript
// The average number of bytes between samples.
const intervalBytes = 512 * 1024;

// The maximum stack depth for samples collected.
const stackDepth = 64;

heap.start(intervalBytes, stackDepth);
`
2. Collect heap profiles:

* Collecting and saving a profile in profile.proto format:
`javascript
const profile = await pprof.heap.profile();
const buf = await pprof.encode(profile);
fs.writeFile('heap.pb.gz', buf, (err) => {
if (err) throw err;
})
`

* View the profile with command line [pprof][pprof-url].
`sh
pprof -http=: heap.pb.gz
`

* Collecting a heap profile with V8 allocation profile format:
`javascript
const profile = await pprof.heap.v8Profile();
``

[build-image]: https://github.com/Datadog/pprof-nodejs/actions/workflows/build.yml/badge.svg?branch=main
[build-url]: https://github.com/Datadog/pprof-nodejs/actions/workflows/build.yml
[npm-image]: https://badge.fury.io/js/@datadog%2Fpprof.svg
[npm-url]: https://npmjs.org/package/@datadog/pprof
[pprof-url]: https://github.com/google/pprof
[pprof-install-url]: https://github.com/google/pprof#building-pprof
[snyk-image]: https://snyk.io/test/github/Datadog/pprof-nodejs/badge.svg
[snyk-url]: https://snyk.io/test/github/Datadog/pprof-nodejs