extensions/markdown-language-features/server/src/workspace.ts/VsCodeClientWorkspace/getAllMarkdownDocuments
class VsCodeClientWorkspace:	async getAllMarkdownDocuments(): Promise<Iterable<md.ITextDocument>> {
		// Add opened files (such as untitled files)
		const openTextDocumentResults = this.documents.all()
			.filter(doc => this.isRelevantMarkdownDocument(doc));

		const allDocs = new ResourceMap<md.ITextDocument>();
		for (const doc of openTextDocumentResults) {
			allDocs.set(URI.parse(doc.uri), doc);
		}

		// And then add files on disk
		const maxConcurrent = 20;
		const limiter = new Limiter<md.ITextDocument | undefined>(maxConcurrent);
		const resources = await this.connection.sendRequest(protocol.findMarkdownFilesInWorkspace, {});
		await Promise.all(resources.map(strResource => {
			return limiter.queue(async () => {
				const resource = URI.parse(strResource);
				if (allDocs.has(resource)) {
					return;
				}

				const doc = await this.openMarkdownDocument(resource);
				if (doc) {
					allDocs.set(resource, doc);
				}
				return doc;
			});
		}));

		return allDocs.values();
	}