# heapdump-next

> Make a dump of the V8 heap for later inspection.

Latest version **1.0.0** (published 2021-09-02) · ISC license · 0 weekly downloads

## Install

```sh
npm install heapdump-next
pnpm add heapdump-next
yarn add heapdump-next
bun add heapdump-next
```

## Health

**Score 25/100 (F)** — status: abandoned.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.0.0 |
| Published | 2021-09-02 |
| First published | 2021-09-02 |
| Weekly downloads | 0 |
| License | ISC |
| TypeScript types | bundled |
| Module format | CommonJS |
| Node | >=0.10.0 |
| Dependencies | 2 |
| Unpacked size | 97.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | yes |
| GitHub stars | 0 |
| Author | s00d |
| Maintainers | s00d |

## Links

- npm: https://www.npmjs.com/package/heapdump-next
- Repository: https://github.com/s00d/node-heapdump-next
- Homepage: https://github.com/bnoordhuis/node-heapdump
- Issues: https://github.com/s00d/node-heapdump-next/issues
- npm.io page: https://npm.io/package/heapdump-next

## Dependencies (2)

- [nan](https://npm.io/package/nan.md) ^2.15.0
- [prebuild-install](https://npm.io/package/prebuild-install.md) ^6.1.4

## Recent versions

- 1.0.0 (latest) — 2021-09-02

## README

[![npm version](https://badge.fury.io/js/heapdump-next.svg)](https://badge.fury.io/js/heapdump-next)
[![npm downloads](https://img.shields.io/npm/dw/heapdump-next)](https://badge.fury.io/js/heapdump-next)
[![NPM license](https://img.shields.io/npm/l/heapdump-next)](https://github.com/s00d/heapdump-next/blob/master/LICENSE)
[![npm type definitions](https://img.shields.io/npm/types/heapdump-next)](https://github.com/s00d/heapdump-next)
[![donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_SM.gif)](https://www.paypal.me/s00d)
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# HeapDump next
===
add typescript and other

Make a dump of the V8 heap for later inspection.

### Install
```bash
npm install heapdump-next --save
```

### Build
```bash
node-gyp configure build
```

You need to have `g++` ane `make` installed to build it.

```bash
apt-get install make
apt-get install g++

```

### Usage

Load the add-on in your application:
```js
const {Heapdump} = require('heapdump-next');
const heapdump = new Heapdump()
// or
import { Heapdump } from "heapdump-next";
const heapdump = new Heapdump()
```

The module exports a single `writeSnapshot([filename], [callback])` function
that writes out a snapshot.  `filename` defaults to `heapdump-<sec>.<usec>.heapsnapshot` when omitted.
You can specify `NODE_HEAPDUMP_FILENAME` env variables, which will be used as template for
filename (include folder) - `NODE_HEAPDUMP_FILENAME="/var/heapdumps/heapdump-{sec}.{usec}.snapshot"`,
in case if you want to save snapshots in different folder than application's working directory.
```js
heapdump.writeSnapshot('/var/local/' + Date.now() + '.heapsnapshot');
```

The function also takes an optional callback function which is called upon
completion of the heap dump.
```js
heapdump.writeSnapshot(function(err, filename) {
    console.log('dump written to', filename);
});
```

The snapshot is written synchronously to disk.  When the JS heap is large,
it may introduce a noticeable "hitch".

Previously, heapdump-next first forked the process before writing the snapshot,
making it effectively asynchronous.  However, it broke the comparison view in
Chrome DevTools and is fundamentally incompatible with node.js v0.12.  If you
really want the old behavior and know what you are doing, you can enable it
again by setting `NODE_HEAPDUMP_OPTIONS=fork` in the environment:
```bash
$ env NODE_HEAPDUMP_OPTIONS=fork node script.js
```

On UNIX platforms, you can force a snapshot by sending the node.js process
a SIGUSR2 signal:
```bash
$ kill -USR2 <pid>
```

The SIGUSR2 signal handler is enabled by default but you can disable it
by setting `NODE_HEAPDUMP_OPTIONS=nosignal` in the environment:
```bash
$ env NODE_HEAPDUMP_OPTIONS=nosignal node script.js
```

### Inspecting the snapshot

Open [Google Chrome](https://www.google.com/intl/en/chrome/browser/) and
press F12 to open the developer toolbar.

Go to the `Profiles` tab, right-click in the tab pane and select
`Load profile...`.

Select the dump file and click `Open`.  You can now inspect the heap snapshot
at your leisure.

Note that Chrome will refuse to load the file unless it has the `.heapsnapshot`
extension.

### Caveats

On UNIX systems, the rule of thumb for creating a heap snapshot is that it
requires memory twice the size of the heap at the time of the snapshot.
If you end up with empty or truncated snapshot files, check the output of
`dmesg`; you may have had a run-in with the system's OOM killer or a resource
limit enforcing policy, like `ulimit -u` (max user processes) or `ulimit -v`
(max virtual memory size).

---
_Source: https://npm.io/package/heapdump-next · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._