Xo: Too slow on large projects

[pixelass]

Description

I am using XO and Ava in a large project. Both packages are too slow to be used. I never actually tried to let them finish. I usually give up after 10+ minutes.
I first thought this might be related to globby: https://github.com/sindresorhus/globby/issues/43

As mentioned in that issue I created a test source that reproduces this issue.
The glob targets a folder that exists only once.

I opened a separate issue in Ava. https://github.com/avajs/ava/issues/1418

Test Source

• https://github.com/pixelass/ava-xo-test
• https://github.com/pixelass/ava-xo-test/blob/3f9f228f279804d8634a367f5458f69ffbc7d253/one/a/b/c/d/e/f/g/h/i/j/this-is-it

Error Message & Stack Trace

nothing happens

Config

https://github.com/pixelass/ava-xo-test/blob/3f9f228f279804d8634a367f5458f69ffbc7d253/package.json#L35-L41

{
  "xo": {
    "ignores": [
      "node_modules/*"
    ],
    "rules": {
      "import/no-unassigned-import": 0
    }
  }
}

Command-Line Arguments

https://github.com/pixelass/ava-xo-test/blob/3f9f228f279804d8634a367f5458f69ffbc7d253/package.json#L10

{
"scripts": {
    "xo": "xo --quiet './**/*.js'"
  },
}

xo --quiet './**/*.js

Relevant Links

Minimal reproduction:
https://github.com/pixelass/ava-xo-test/

Environment

OS X 10.12.5 (16F73)  
Node 6.11.0  

Requested log:

Platform: darwin 16.6.0
xo: 0.18.2
node: 6.11.0
npm: 3.10.10

[Qix-]

Just chiming in - XO already ignores node_modules/.

[pixelass]

@Qix- thx. I'm not sure why we have it listed. Probably c&p from other plugins. I was aware that it is ignored though.

I created the test-repo similar to our setup.

[pixelass]

I switched to eslint using the XO shared config. It takes about 7 seconds to lint all files and the config can be read by the variety of editors our developers use.

So the issue is not related to eslint itself. Hope this helps.

[SamVerschueren]

Is it also slow when running it through the command line? There's an issue with the XO linter in VS Code on large projects. So my question, is this really a XO issue or rather a plugin issue?

[pixelass]

I first experienced this issue from the command line.
I myself don't use linters in my editor but rather use npm scripts. (See original issue description)

All issues around editors came from developers in my team. I'm just making sure everybody is happy.

[sindresorhus]

I discovered the main culprit. We didn't define quiet as a boolean, which made the glob pattern an argument to --quiet and not an actuall pattern, which resulted in XO using its default pattern, which is **/*.

Try changing it to:

```diff
- "xo": "xo --quiet './/.js'",
+ "xo": "xo './/.js' --quiet",

[sindresorhus]

It still takes 18 seconds just to glob the 25891 .js files out of 116329 files on my machine. Although totally unrealistic example, I think it should be faster.

The gitignore logic for example is inefficient.

[pixelass]

I just added eslint with the xo shared config as a comparison.
I removed the quiet flag and the config of xo.

For me xo is still very slow in that test project (>40 sec) while eslint works as expected (~12 sec) which isn't fast either but acceptable.

The changes can be viewed on the master branch

[pixelass]

This example is taken from a java/hybris project with multiple brands. The frontend is not separated from the backend. I tried to make it as similar as possible. Only a few files should be globbed now since I forgot the folder name this-is-it. So the glob might have been unrealistic but the the example is not ;)

[sindresorhus]

For me xo is still very slow in that test project (>40 sec) while eslint works as expected (~12 sec) which isn't fast either but acceptable.

Try deleting ~/.xo-cache and run again. That might improve it a little bit. Since the cache was filled up with all the files, not just .js files.

[sindresorhus]

As I thought, inefficient gitignore handling. This line takes more than 6 seconds.

[sindresorhus]

XO will always be slower than ESLint + eslint-config-xo though, as we include many more external plugins here that are not included in eslint-config-xo, but we will try to fix the biggest performance bottlenecks.

[pixelass]

After deleting the cache:

Eslint: 14s
XO: 59s

[marionebl]

To sum this up there is a bundle of performance related issues we could tackle to improve user experience:

• Reading gitignores is synchronous

• Wasted effort on reading irrelevant gitignores

• Wasted effort on globbing gitignored directory trees

I do not have a coherent idea on how to tackle points 2 and 3 without reimplementing the gitignore logic of ignore in globby. Thoughts @schnittstabil @sindresorhus?

[sindresorhus]

I do not have a coherent idea on how to tackle points 2 and 3 without reimplementing the gitignore logic of ignore in globby.

Why would we have to reimplement the gitignore logic?

[marionebl]

Why would we have to reimplement the gitignore logic?

Taking @schnittstabil 's comment about glob into account there are two ways to approach this:

1. Land a PR on glob to support Function, on .ignore, use that with ignore in globby. No reimplementation necessary here.

2. Make the translation from.gitignore to negative glob patterns and/or .ignore patterns work correctly. That boils down to reimplementation of ignore to some extent.

I only thought about scenario 2 in my previous comment.

[niftylettuce]

Any update here? I still find xo to be incredibly slow while linting 1000-2000 LOC and eslint is fast.

[niftylettuce]

xo albeit nice has greatly hindered my development speed, I'd gladly pay a bug bounty 🐛 💰

[OmgImAlexis]

@niftylettuce looks like sindresorhus/globby#68 has fixed or at least helped with this.

[pvdlg]

@pixelass @SamVerschueren @OmgImAlexis @niftylettuce we released a new version of XO with improved performances regarding globbing. That would be great to have your feedback, as you experienced performance issues on your projects before.
Is the new version improve the situation? Do you still experience unreasonable slowness?

[niftylettuce]

Still incredibly poor performance, even on a file only 600 LOC

[pvdlg]

What “incredibly poor performance” means? Please provide numbers.
Can you also provide the file in question and your XO configuration? Otherwise there is absolutely nothing that we can do.

[Qix-]

Also, keep in mind Node has a bootup time of about 600ms at the least, which is astronomically high especially if you're running it over and over in a loop.

There's nothing the XO team can do about that either.

[OmgImAlexis]

@Qix- eslint with the same config runs in a LOT less time. It's not node that's the issue. It's very likely still something like globby as it the slow down seem to point to before. Let's hope https://github.com/sindresorhus/globby/pull/68 helps with this.

@pvdlg have a look at the other issues @niftylettuce and I have commented on regarding speed issues with xo; We've both had issues on multiple different projects in multiple configs. If we could reduce it to a single issue we'd all be happy. 😞

Ref: https://github.com/xojs/xo/issues/212

[pvdlg]

@OmgImAlexis a lot has been done to improve performances since you opened #212, including changes in globby.

@niftylettuce, @OmgImAlexis any comments need to include:

• Actual time measured to lint (as in an actual number)
• The files linted, or a link or to it, or even better a link to the repo (as in "the actual file so I can reproduce", not "600 LOC" or some vague info)
• If possible, a comparison with ESlint with the same rules

Every comments with vague things like "incredibly poor performance” or "multiple different projects in multiple configs" or references to 2 years old things are not helpful and doesn't allow us to analyze anything.

[niftylettuce]

I have provided a reproducible test case https://github.com/xojs/xo/issues/212#issuecomment-425549531. The issue is when you have a lot of conditionals, the process for xo will never end as a result.

[Qix-]

  1 warning
  295 errors
node_modules/.bin/xo  1.03s user 0.14s system 107% cpu 1.091 total

1 second. Make sure your lockfiles are blown away - they cause lots of issues such as outdated modules.

EDIT Just saw https://github.com/xojs/xo/issues/212#issuecomment-425565385 - glad that was the case :)

[niftylettuce]

Please close issue