perf: fix lazy loading of core rules

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[x] Other, please explain:

Performance improvement.

We have lazy-loading-rule-map which prevents loading all core rule modules when they are not necessary, and that part works well.

On the other hand, eslint-all.js loads all rule modules, because it needs meta of rules to filter out deprecated ones.

The problem is that flat-config-array always loads eslint-all.js:

eslint/lib/config/flat-config-array.js

Line 17 in 8d3c25f

const allConfig = require("../../conf/eslint-all");

so, as a consequence, basically any use of ESLint loads all rules, which we were obviously trying to avoid.

What changes did you make? (Give an overview)

Moved require("../../conf/eslint-all") from the top level of flat-config-array.js to the place where it's needed.

`npm run perf` before this change

> eslint@8.9.0 perf D:\projects\eslint
> node Makefile.js perf


Loading:
  Load performance Run #1:  622.997785ms
  Load performance Run #2:  685.887445ms
  Load performance Run #3:  617.0843ms
  Load performance Run #4:  689.034299ms
  Load performance Run #5:  615.789688ms

  Load Performance median:  622.997785ms


Single File:
  CPU Speed is 2095 with multiplier 13000000
  Performance Run #1:  11956.969383ms
  Performance Run #2:  11742.944261ms
  Performance Run #3:  11807.732589ms
  Performance Run #4:  12022.606126ms
  Performance Run #5:  11804.399046ms

  Performance budget exceeded: 11807.732589ms (limit: 6205.250596658711ms)


Multi Files (450 files):
  CPU Speed is 2095 with multiplier 39000000
  Performance Run #1:  31217.632838ms
  Performance Run #2:  31106.2355ms
  Performance Run #3:  31508.789833ms
  Performance Run #4:  30745.145445ms
  Performance Run #5:  30807.573268ms

  Performance budget exceeded: 31106.2355ms (limit: 18615.751789976133ms)

`npm run perf` after this change

> eslint@8.9.0 perf D:\projects\eslint
> node Makefile.js perf


Loading:
  Load performance Run #1:  313.853045ms
  Load performance Run #2:  306.604384ms
  Load performance Run #3:  344.540608ms
  Load performance Run #4:  304.535642ms
  Load performance Run #5:  306.038938ms

  Load Performance median:  306.604384ms


Single File:
  CPU Speed is 2095 with multiplier 13000000
  Performance Run #1:  11899.784524ms
  Performance Run #2:  11760.932493ms
  Performance Run #3:  11679.374794ms
  Performance Run #4:  11751.555466ms
  Performance Run #5:  12019.626415ms

  Performance budget exceeded: 11760.932493ms (limit: 6205.250596658711ms)


Multi Files (450 files):
  CPU Speed is 2095 with multiplier 39000000
  Performance Run #1:  31008.965526ms
  Performance Run #2:  30747.93309ms
  Performance Run #3:  30830.182326ms
  Performance Run #4:  31287.272178ms
  Performance Run #5:  31279.041194ms

  Performance budget exceeded: 31008.965526ms (limit: 18615.751789976133ms)

This improves Loading performance by 50%.

Single File and Multi File are not relevant for this change, as they run all rules anyways.

Is there anything you'd like reviewers to focus on?

I tried to write a test for this using proxyquire's @global, and eventually managed to make a test that fails without this change, but didn't manage to remove proxies after the test.

Update: I added a test that runs in a child process and seems to be working well. I've verified that the test would fail without the change in flat-config-array.js. I've also verified that the test would fail if eslint-all.js is loaded from cli-engine.js (as in #15602 (comment)).

[nzakas]

LGTM. Nice catch!