Bun v0.6.9

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

• v0.6.0 - Introducing bun build, Bun's new JavaScript bundler.
• v0.6.2 - Performance boosts: 20% faster JSON.parse, up to 2x faster Proxy and arguments.
• v0.6.3 - Implemented node:vm, lots of fixes to node:http and node:tls.
• v0.6.4 - Implemented require.cache, process.env.TZ, and 80% faster bun test.
• v0.6.5 - Native support for CommonJS modules (previously, Bun did CJS to ESM transpilation),
• 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 - Node.js compatibility improvements to unblock Discord.js, Prisma, and Puppeteer
• 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:

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

npm install -g bun

brew tap oven-sh/bun

brew install bun

docker pull oven/bun

docker run --rm --init --ulimit memlock=-1:-1 oven/bun

To upgrade Bun:

bun upgrade

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

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

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

Previously, the following code would clone text twice:

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.

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.

Non-ascii filenames#

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

bun run 👋.js

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

console.log("hello!");

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:

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.

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:

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.

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:

Before:

Node.js, for comparison:

Changelog#

View Full Changelog