From fcf3f9da6595f8cda843e8adbfdf466c52dd7d08 Mon Sep 17 00:00:00 2001
From: Adnan Hashmi <56730784+adnanhashmi09@users.noreply.github.com>
Date: Wed, 26 Oct 2022 05:05:35 +0530
Subject: [PATCH] docs: Mention wide globs performance implications in
 monorepos docs and parser README (#5864)

* docs: Mention wide globs performance implications in monorepos docs and parser readme

* Update docs/linting/typed-linting/MONOREPOS.md

Co-authored-by: Josh Goldberg <git@joshuakgoldberg.com>
---
 docs/linting/typed-linting/MONOREPOS.md | 27 +++++++++++++++++++++++++
 packages/parser/README.md               |  2 ++
 2 files changed, 29 insertions(+)

diff --git a/docs/linting/typed-linting/MONOREPOS.md b/docs/linting/typed-linting/MONOREPOS.md
index 1bb057718c6..5163e997ec8 100644
--- a/docs/linting/typed-linting/MONOREPOS.md
+++ b/docs/linting/typed-linting/MONOREPOS.md
@@ -62,6 +62,33 @@ module.exports = {
 };
 ```
 
+### Wide globs in `parserOptions.project`
+
+Using wide globs `**` in your `parserOptions.project` may degrade linting performance.
+Instead of globs that use `**` to recursively check all folders, prefer paths that use a single `*` at a time.
+
+```js title=".eslintrc.js"
+module.exports = {
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/recommended',
+    'plugin:@typescript-eslint/recommended-requiring-type-checking',
+  ],
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    tsconfigRootDir: __dirname,
+    // Remove this line
+    project: ['./tsconfig.eslint.json', './**/tsconfig.json'],
+    // Add this line
+    project: ['./tsconfig.eslint.json', './packages/*/tsconfig.json'],
+  },
+  plugins: ['@typescript-eslint'],
+  root: true,
+};
+```
+
+See [Glob pattern in parser's option "project" slows down linting](https://github.com/typescript-eslint/typescript-eslint/issues/2611) for more details.
+
 ### Important note regarding large (> 10) multi-package monorepos
 
 We've had reports that for sufficiently large and/or interdependent projects, you may run into OOMs using this approach.
diff --git a/packages/parser/README.md b/packages/parser/README.md
index efba4854413..b32ed30beab 100644
--- a/packages/parser/README.md
+++ b/packages/parser/README.md
@@ -164,6 +164,8 @@ This option allows you to provide a path to your project's `tsconfig.json`. **Th
 
 - If you use project references, TypeScript will not automatically use project references to resolve files. This means that you will have to add each referenced tsconfig to the `project` field either separately, or via a glob.
 
+- Note that using wide globs `**` in your `parserOptions.project` may cause performance implications. Instead of globs that use `**` to recursively check all folders, prefer paths that use a single `*` at a time. For more info see [#2611](https://github.com/typescript-eslint/typescript-eslint/issues/2611).
+
 - TypeScript will ignore files with duplicate filenames in the same folder (for example, `src/file.ts` and `src/file.js`). TypeScript purposely ignore all but one of the files, only keeping the one file with the highest priority extension (the extension priority order (from highest to lowest) is `.ts`, `.tsx`, `.d.ts`, `.js`, `.jsx`). For more info see #955.
 
 - Note that if this setting is specified and `createDefaultProgram` is not, you must only lint files that are included in the projects as defined by the provided `tsconfig.json` files. If your existing configuration does not include all of the files you would like to lint, you can create a separate `tsconfig.eslint.json` as follows: