perf(v2): more efficient hot reload & consistent filegen

[endiliey]

Motivation

More efficient hot reload & consistent generated file

Note that I set clientLogLevel to info in devserver config.

Previously, if we start development server and go to home page. We can go to src/pages/index.js and just 'save' without changing anything

GIF Preview

Note that there are several files that got disposed by WDS. This is because our generated files (although we have caching in

docusaurus/packages/docusaurus-utils/src/index.ts

Lines 15 to 32 in 87f864e

	const fileHash = new Map();
	export async function generate(
	generatedFilesDir: string,
	file: string,
	content: any,
	): Promise<void> {
	const filepath = path.join(generatedFilesDir, file);
	const lastHash = fileHash.get(filepath);
	const currentHash = createHash('md5')
	.update(content)
	.digest('hex');
	if (lastHash !== currentHash) {
	await fs.ensureDir(path.dirname(filepath));
	await fs.writeFile(filepath, content);
	fileHash.set(filepath, currentHash);
	}
	}

), is re-written due to different object keys ordering.

Explanation

{
'a': 'foo',
'b': 'bar',
}

Is considered different from

{
'b': 'bar',
'a': 'foo',
}

The generated files can be different because of async nature and keys ordering. We should always provide consistent file generation.

Others:

• set babel compact to true which removes "superfluous whitespace characters and line terminators https://stackoverflow.com/questions/35192796/babel-note-the-code-generator-has-deoptimised-the-styling-of-app-js-as-it-exc/36880182

Have you read the Contributing Guidelines on pull requests?

yes

Test Plan

After this PR

GIF preview

I tried editing the src/pages/index.js for real and its the right behavior

Index.js is detected to have changed, so it is disposed. Registry need to be dispsoed because index.js has changed, and so on.

Extra: Notice the hot reload performance is much faster :)

[yangshun]

Wow what an optimization. Maybe you could tweet/blog about this.

[docusaurus-bot]

Deploy preview for docusaurus-2 ready!

Built with commit 32af3c1

https://deploy-preview-1950--docusaurus-2.netlify.com

[docusaurus-bot]

Deploy preview for docusaurus-preview ready!

Built with commit 32af3c1

https://deploy-preview-1950--docusaurus-preview.netlify.com

[endiliey]

Previously had to sort it in test because snapshot will always fail previously due to inconsistent routes (async nature). Now no longer need to do that in test

[endiliey]

Had to do this because otherwise docsBaseMetadata (the root file generated) will always change without utilizing cache

[endiliey]

Even snapshot is consistent now in ordering😃

[endiliey]

it got merged before i can even comment 😭 .

Actually found this when stress testing 1,000 docs. My hot reload went down from 10s to 1-2s due to this optimization lol

Editing pages only took 600ms as usual

Seems we can handle 1k+ docs for now
~45s for cold startup

~20s after cache

[yangshun]

Sorry, I was too excited to merge this. This is such a crazy optimization. We are one step closer towards the scalability required for versioning!

[endiliey]

On production, removing

showLastUpdateTime and showLastUpdateAuthor saved 80s of nodejs time 😭 for 1026 docs lol
Thankfully we use fake data for dev :)