Bug: eslint-plugin-import is slow when giant files such as typescript.js are included

[kaiyoma]

I initially filed this bug against eslint (eslint/eslint#15728), but that was analyzed and closed and I was told to file against typescript-eslint instead. I did that (typescript-eslint/typescript-eslint#4735) and after some thorough analysis by the maintainers, they concluded that eslint-plugin-import is the culprit, so posting here.

Environment

Node version: v16.13.0
npm version: v8.1.4
Local ESLint version: v8.10.0 (Currently used)
Global ESLint version: Not found
Operating System: win32 10.0.19044

What parser are you using?

@typescript-eslint/parser

What did you do?

Will post separately (GitHub is complaining about the content length).

What did you expect to happen?

For eslint to run in a timely manner.

What actually happened?

eslint is taking almost 2 minutes to lint half a dozen files, none of which are big. In the debug log (posted below), I can see that it's taking over 45 seconds (each) for two particular files to be linted, and neither one is more than 200 lines.

Additional comments

Will post separately (GitHub is complaining about the content length).

[kaiyoma]

For the eslint config, code that will repro the problem, debug logs, and an in-depth analysis of why this plugin is to blame, see the previous issue (typescript-eslint/typescript-eslint#4735).

[burtek]

Same here, working on an eslint plugin, imported typescript and it takes ages to lint a single file:

$ TIMING=1 yarn eslint src/eslint-utils/isMethodCalledOnArray.ts --fix-dry-run

[REDACTED]/src/eslint-utils/isMethodCalledOnArray.ts
  10:23  warning  No magic number: 1  @typescript-eslint/no-magic-numbers
  13:23  warning  No magic number: 2  @typescript-eslint/no-magic-numbers
  16:23  warning  No magic number: 3  @typescript-eslint/no-magic-numbers

✖ 3 problems (0 errors, 3 warnings)

Rule                                   | Time (ms) | Relative
:--------------------------------------|----------:|--------:
import/no-deprecated                   | 27330.375 |    38.6%
import/namespace                       | 25952.951 |    36.6%
import/no-cycle                        | 17408.762 |    24.6%
@typescript-eslint/naming-convention   |    42.714 |     0.1%
n/no-extraneous-import                 |    13.045 |     0.0%
n/no-unpublished-import                |     9.993 |     0.0%
@typescript-eslint/indent              |     9.372 |     0.0%
@typescript-eslint/no-misused-promises |     7.999 |     0.0%
import/order                           |     5.278 |     0.0%
import/no-duplicates                   |     4.737 |     0.0%
Done in 74.57s.

[JounQin]

Can you try https://github.com/un-es/eslint-plugin-i to see whether it's much faster?

[JounQin]

duplicate of #2348

[burtek]

@JounQin give me a few minutes, will let you know

[burtek]

@JounQin it is faster, but not much (I only replaced the 3 longest taking rules as I'm using shared config so it'd be hard to replicate all of it and replace import with i)

Rule                                   | Time (ms) | Relative
:--------------------------------------|----------:|--------:
i/no-deprecated                        | 19176.082 |    43.6%
i/namespace                            | 16235.055 |    36.9%
i/no-cycle                             |  8471.943 |    19.2%
@typescript-eslint/naming-convention   |    37.586 |     0.1%
n/no-extraneous-import                 |     8.199 |     0.0%
@typescript-eslint/indent              |     7.042 |     0.0%
@typescript-eslint/no-misused-promises |     6.244 |     0.0%
n/no-unpublished-import                |     5.568 |     0.0%
import/order                           |     2.679 |     0.0%
import/no-duplicates                   |     1.913 |     0.0%
Done in 48.12s.

eslint config that replaces the `import` plugin:

{
    "extends": "<internally-shared-config>",
    "parserOptions": {
        "project": "./tsconfig.json"
    },
    "plugins": ["i"]
    "rules": {
        // https://github.com/import-js/eslint-plugin-import/issues/2416
        "import/no-deprecated": "off",
        "import/namespace": "off",
        "import/no-cycle": "off",
        "i/no-deprecated": "warn",
        "i/namespace": "error",
        "i/no-cycle": "error"
    }
}

[JounQin]

@burtek

npm install -D eslint-plugin-import@npm:eslint-plugin-i

It should not needed to change your eslint config at all.

[burtek]

@JounQin oh, didn't know that's possible 😮

[JounQin]

Thanks for sharing, I'd like see if I can help to debug the performance issue tomorrow.

Let's track this issue at #2348.

[JounQin]

@JounQin oh, didn't know that's possible 😮

That's documented at https://github.com/un-es/eslint-plugin-i#installation 😏

[burtek]

@JounQin Imagine reading docs in 2022 🙃😆

My bad