> ## Documentation Index
> Fetch the complete documentation index at: https://developer.upsun.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Continuous profiling for Node.js

> Configure and use the NodeJS continuous profiler.

export const ContinuousProfilingSellableBody = () => <Info title="Feature availability">
    By default, Upsun offers 15 minutes of continuous profiling per project and for free.
    To get 30 days of continuous profiling per project and for a fixed fee, <a href="/docs/administration/billing/add-on-subscription#continuous-profiling-add-on">upgrade to the Continuous Profiling add-on</a>.
  </Info>;

<ContinuousProfilingSellableBody />

## Continuous profiling on Upsun

Upsun Continuous Profiling is powered by [Blackfire](/docs/observability/application-metrics/blackfire).
It is available directly in the Console, under **Apps and Services → your app → Profiling**.

The Node.js continuous profiling is currently made across 3 dimensions:

* **CPU Time**:  Time spent running on the CPU
* **Wall-time**: Elapsed time per function call
* **Heap**: Memory allocation and reserved space over time

The default sampling frequency is 100 Hz. This means the Node.js continuous profiler is
collecting information 100 times per second.

## Prerequisites

Upsun Continuous Profiler requires [`Node.js >= 16.0.0`](/docs/languages/nodejs).

## Installation

Get the [Blackfire Continuous Profiler NodeJS library](https://github.com/blackfireio/node-continuous-profiling/):

```shell theme={null}
npm install @blackfireio/node-tracing
```

```js theme={null}
const Blackfire = require('@blackfireio/node-tracing');
```

## NodeJS continuous profiler API

The NodeJS continuous profiler API has two functions:

```js theme={null}
function start(config) {}
function stop() {}
```

### `function start(config) {}`

The `start` function starts the continuous profiler probe.
It collects profiling information in the background and periodically uploads it to the Blackfire Agent until the `stop` function is called.

```js theme={null}
const Blackfire = require('@blackfireio/node-tracing');
Blackfire.start({
   appName: 'my-app'
});
// your application...
// If needed, you can stop profiling before cpuDuration
// Blackfire.stop();
```

The `start` function accepts an object as a parameter with the following keys:

* `appName`: name of the application

* `durationMillis`: time in milliseconds for which to collect profile (default: 45\_000)

* `cpuProfileRate`: average sampling frequency in Hz. (default: 100)

* `labels`: Labels to add to the profile. (default: {})

* `uploadTimeoutMillis`: Timeout in milliseconds for the upload request (default: 10000)

### `function stop() {}`

Stops the continuous profiling probe.

## An example application

1. Get the Continuous Profiler NodeJS library

```shell theme={null}
npm install express @blackfireio/node-tracing
```

2. Create `index.js` with the following code

```js theme={null}
const Blackfire = require('@blackfireio/node-tracing');
const express = require('express')
const crypto = require("crypto");
const app = express()
const port = 3000

app.get('/', (req, res) => {
   const salt = crypto.randomBytes(128).toString("base64");
   const hash = crypto.pbkdf2Sync("this is my password", salt, 10000, 512, "sha512");

   res.send('Hello World!');
})


app.listen(port, () => {
   console.log(`Example app listening on port ${port}`)
   Blackfire.start({appName: 'blackfire-example'});
})
```

3. Run the Node.js server

```bash theme={null}
node index.js
```