---
title: Bun v0.6.9
description: Memory usage reductions in Bun.serve(), bun install, module imports, and crypto hashing. Crash in CommonJS modules fixed, plus additional bugfixes.
date: "2023-06-13T15:05:43.883Z"
author: jarred
draft: false
---

{% callout %}
We're hiring C/C++ and Zig engineers to build the future of JavaScript! [Join our team →](/careers)
{% /callout %}

We've been releasing a lot of changes to Bun recently, here's a recap in case you missed it:

- [`v0.6.0`](/blog/bun-bundler) - Introducing `bun build`, Bun's new JavaScript bundler.
- [`v0.6.2`](/blog/bun-v0.6.2) - Performance boosts: 20% faster `JSON.parse`, up to 2x faster `Proxy` and `arguments`.
- [`v0.6.3`](/blog/bun-v0.6.3) - Implemented `node:vm`, lots of fixes to `node:http` and `node:tls`.
- [`v0.6.4`](/blog/bun-v0.6.4) - Implemented `require.cache`, `process.env.TZ`, and 80% faster `bun test`.
- [`v0.6.5`](/blog/bun-v0.6.5) - Native support for CommonJS modules (_previously, Bun did CJS to ESM transpilation_),
- [`v0.6.6`](/blog/bun-v0.6.6) - `bun test` improvements, including Github Actions support, `test.only()`, `test.if()`, `describe.skip()`, and 15+ more `expect()` matchers; also streaming file uploads using `fetch()`.
- [`v0.6.7`](/blog/bun-v0.6.7) - Node.js compatibility improvements to unblock Discord.js, Prisma, and Puppeteer
- [`v0.6.8`](/blog/bun-v0.6.8) - `Bun.password`, function mocking in `bun test`, and a `toMatchObject` expect matcher. Plus an experimental `inspector` mode in `Bun.serve()`.

This release reduces Bun's memory usage across the board and fixes bugs in the bundler/transpiler, CommonJS module loading, `bun run`, and `bun install`.

To install Bun:

{% codetabs %}

```sh#curl
$ curl -fsSL https://bun.sh/install | bash
```

```sh#npm
$ npm install -g bun
```

```sh#brew
$ brew tap oven-sh/bun
$ brew install bun
```

```sh#docker
$ docker pull oven/bun
$ docker run --rm --init --ulimit memlock=-1:-1 oven/bun
```

{% /codetabs %}

{% raw %}
<br>
{% /raw %}

To upgrade Bun:

```sh
$ bun upgrade
```

## `Bun.serve()` uses less memory to send strings

Bun now supports zero-copy string `Response` bodies in `Bun.serve()`.

{% raw %}

<blockquote class="twitter-tweet"><p lang="en" dir="ltr">In the next version of Bun<br><br>Sending strings with Bun&#39;s HTTP server uses less memory.<br><br>After responding to 1000 requests with a 12 MB string<br><br>Bun: 60 MB ram<br>Deno: 425 MB ram<br>Node: 1414 MB ram <a href="https://t.co/LJ6FdAcWkZ">pic.twitter.com/LJ6FdAcWkZ</a></p>&mdash; Jarred Sumner (@jarredsumner) <a href="https://twitter.com/jarredsumner/status/1667863498825830402?ref_src=twsrc%5Etfw">June 11, 2023</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>

{% /raw %}

We've also applied this optimization to `Response` outside of `Bun.serve()`

Previously, the following code would clone `text` twice:

```ts
const text = await Bun.file("file.txt").text();

// Copy #1
const response = new Response(text);

// Copy #2
await response.text();
```

Now, it doesn't copy, saving you memory.

## Cold `bun install` uses 50% less memory

We free more memory in `bun install` now, reducing memory usage by 50% for cold installs.

{% raw %}

<blockquote class="twitter-tweet"><p lang="en" dir="ltr">In the next version of Bun<br><br>bun install (cold) uses 2x less memory <a href="https://t.co/HePmK3uHUx">pic.twitter.com/HePmK3uHUx</a></p>&mdash; Jarred Sumner (@jarredsumner) <a href="https://twitter.com/jarredsumner/status/1667469826548436992?ref_src=twsrc%5Etfw">June 10, 2023</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>

{% /raw %}

## Importing modules in Bun's runtime uses less memory

We've fixed a couple memory leaks in Bun that happened when importing modules in Bun's runtime, and improved our bindings with JavaScriptCore for source code management.

![image](https://github.com/oven-sh/bun/assets/709451/b839fda4-fa3d-4abd-b7f5-0573995ac313)

## Non-ascii filenames

Previously, Bun would throw an error when importing a file with a non-ascii filename.

{% codetabs %}

```bash#shell
$ bun run 👋.js

error: FileNotFound reading "/Users/jarred/Desktop/ð.js"
```

```js#👋.js
console.log("hello!");
```

{% /codetabs %}

This error was caused by both a printing bug and a bug in Bun's JavaScriptCore bindings when reading import identifier names.

## Bugfixes to mocks in `bun test`

`mockResolvedValue` is fixed in `bun test` now. Previously, `mockResolvedValue` would appear to do nothing in `bun test`.

To use `mockResolvedValue`:

```ts
import { mock, test, expect } from "bun:test";

test("hey", async () => {
  const fn = mock.mockResolvedValue(1);

  expect(fn()).toBeInstanceOf(Promise);

  const value = await fn();

  expect(value).toBe(1); // 1
});
```

The `mock` object returned was missing a `.bind`, `.apply`, `.call`, `.name`, and `.length` functions. This has been fixed. We've also made it so that the `.name` of the mocked function is copied over from the original function automatically.

```ts
import { mock, test, expect } from "bun:test";

test("hey", async () => {
  const hey = mock(function yo() {
    return 42;
  });

  expect(hey.name).toBe("yo");
});
```

## Crash in CommonJS `require()` fixed

This release fixes a crash that can occur when many CommonJS files are imported and then the garbage collector is run after the files are no longer in use:

```js
import "lodash/omit.js";
import "lodash/findIndex.js";
import "discord.js";

Bun.gc(true);
```

This was a bug in the CommonJS module loader not correctly preventing the function from being garbage collected.

## A memory leak in `node:crypto` has been fixed

This release fixes a memory leak in `node:crypto`. The following code would leak about 192 bytes per call.

```js
const crypto = require("crypto");

function sha256(buf) {
  return crypto.createHash("sha256").update(buf).digest();
}

async function main() {
  for (var i = 1000000; i >= 0; i--) {
    const buf = Buffer.alloc(2046);
    const hash = sha256(buf);
    if (i % 1000 === 0) {
      await new Promise((r) => setTimeout(r, 20));
      global.gc ? global.gc() : Bun?.gc(true);
    }
  }
}

main();
```

After:

![](https://github.com/oven-sh/bun/assets/709451/d111274a-0a4a-4075-82f2-39699dbf8521)

Before:

![](https://github.com/oven-sh/bun/assets/709451/231f7e38-0717-4610-a8dd-aebac2aa70d7)

Node.js, for comparison:

![](https://github.com/oven-sh/bun/assets/709451/22e4466e-883e-4659-9f5c-f0310865515b)

## Changelog

{% table %}

---

- [`#3277`](https://github.com/oven-sh/bun/pull/3277)
- add --save argument to install by [@kvakil](https://github.com/kvakil)

---

- [`#3292`](https://github.com/oven-sh/bun/pull/3292)
- handle unwrapping require in any expression by [@dylan-conway](https://github.com/dylan-conway)

---

- [`#3286`](https://github.com/oven-sh/bun/pull/3286)
- Typo in readline by [@paperclover](https://github.com/paperclover)

---

- [`#3290`](https://github.com/oven-sh/bun/pull/3290)
- workaround quote escape issues for bun run

---

{% /table %}

[**View Full Changelog**](https://github.com/oven-sh/bun/compare/bun-v0.6.8...bun-v0.6.9)