Memory leak in jest-circus

[dylang]

🐛 Bug Report

When using jest-circus, an obvious memory leak and gradual slowdown occurs.

$ node --expose-gc ./node_modules/.bin/jest --logHeapUsage --runInBand funky
 PASS  tests/funky-36.test.js (20 MB heap size)
 PASS  tests/funky-86.test.js (22 MB heap size)
 PASS  tests/funky-28.test.js (24 MB heap size)
...
 PASS  tests/funky-56.test.js (195 MB heap size)
 PASS  tests/funky-24.test.js (197 MB heap size)
 PASS  tests/funky-30.test.js (199 MB heap size)
 PASS  tests/funky-52.test.js (201 MB heap size)

To Reproduce

100 identical tests with jest-circus/runner.

describe('funky-10.test', () => {
    test('funky-10', async () => {
        expect(1).toEqual(1);
    });
});

jest.config:

testRunner: require.resolve('jest-circus/runner')

Expected behavior

Same 100 tests without jest-circus/runner.

$ node --expose-gc ./node_modules/.bin/jest --logHeapUsage --runInBand funky
 PASS  tests/funky-36.test.js (17 MB heap size)
 PASS  tests/funky-40.test.js (17 MB heap size)
 PASS  tests/funky-28.test.js (17 MB heap size)
...
 PASS  tests/funky-18.test.js (17 MB heap size)
 PASS  tests/funky-87.test.js (17 MB heap size)
 PASS  tests/funky-89.test.js (17 MB heap size)

Link to repl or repo (highly encouraged)

https://github.com/dylang/jest-circus-memory-leak-repo

Run npx envinfo --preset jest

 System:
    OS: macOS Sierra 10.12.6
    CPU: x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  Binaries:
    Node: 10.8.0 - ~/.nvm/versions/node/v10.8.0/bin/node
    Yarn: 1.10.1 - /usr/local/bin/yarn
    npm: 6.4.1 - ~/.nvm/versions/node/v10.8.0/bin/npm
  npmPackages:
    jest: ^23.6.0 => 23.6.0

[rickhanlonii]

👀

[SimenB]

#6965?

[dylang]

I've determined this is caused by graceful-fs.

isaacs/node-graceful-fs#102

I have a fix locally and will create a PR to graceful-fs in the morning.

[dylang]

Here's a PR for graceful-fs:
isaacs/node-graceful-fs#137

This PR fixes the issue in my repro repo at
https://github.com/dylang/jest-circus-memory-leak-repo

HOWEVER, in my work repo that I can't share here, the graceful-fs changes weren't enough for jest-circus not to leak memory so I'm disabling it for now. I've spent more time than I intended already but I can look deeper if there are specific things I should try.

[thymikee]

That's awesome. I just feel this is never gonna be merged, based on the state of the repository. Also @palmerj3 seems to have some issues there as well: https://mobile.twitter.com/palmerj3/status/1055782284983496704

Maybe there's a maintained for of the project?

[SimenB]

@dylang can you test with eager evaluating error stacks, ref #6965?

[dylang]

@thymikee - my fixes for the memory leak were merged and published!

@SimenB I upgraded graceful-fs in dylang/jest-circus-memory-leak and it no longer have the memory leak issue, so I think we can consider this issue resolved, as long as graceful-fs is ^4.1.15 everywhere it's used in this project.

[SimenB]

HOWEVER, in my work repo that I can't share here, the graceful-fs changes weren't enough for jest-circus not to leak memory so I'm disabling it for now. I've spent more time than I intended already but I can look deeper if there are specific things I should try.

I'd still like to track that part. Or is it fixed? If not, could you test the stack change I linked to?

[dylang]

Very non-scientific. We have 5800 tests and I don't have time right now to do a full run several times over, so this is just the first 15 tests - which are not necessarily the same 15 tests. Filenames have been removed because I don't know if I can share them.

Jest 23.6.0, default runner

node --expose-gc ./node_modules/.bin/jest --logHeapUsage --runInBand --config=./jest.config.js

 PASS  -filename removed- (35.116s, 165 MB heap size)
 PASS  -filename removed- (193 MB heap size)
 PASS  -filename removed- (222 MB heap size)
 PASS  -filename removed- (251 MB heap size)
 PASS  -filename removed- (251 MB heap size)
 PASS  -filename removed- (66.108s, 192 MB heap size)
 PASS  -filename removed- (221 MB heap size)
 PASS  -filename removed- (10.591s, 214 MB heap size)
 PASS  -filename removed- (246 MB heap size)
 PASS  -filename removed- (258 MB heap size)
 PASS  -filename removed- (272 MB heap size)
 PASS  -filename removed- (275 MB heap size)
 PASS  -filename removed- (276 MB heap size)
 PASS  -filename removed- (246 MB heap size)
 PASS  -filename removed- (251 MB heap size)

Jest 23.6.0, Jest Circus 23.6.0

node --expose-gc ./node_modules/.bin/jest --logHeapUsage --runInBand --config=./jest.config.js

 PASS  -filename removed- (32.311s, 234 MB heap size)
 PASS  -filename removed- (262 MB heap size)
 PASS  -filename removed- (290 MB heap size)
 PASS  -filename removed- (319 MB heap size)
 PASS  -filename removed- (349 MB heap size)
 PASS  -filename removed- (100.506s, 379 MB heap size)
 PASS  -filename removed- (6.497s, 407 MB heap size)
 PASS  -filename removed- (16.084s, 422 MB heap size)
 PASS  -filename removed- (454 MB heap size)
 PASS  -filename removed- (466 MB heap size)
 PASS  -filename removed- (481 MB heap size)
 PASS  -filename removed- (497 MB heap size)
 PASS  -filename removed- (511 MB heap size)
 PASS  -filename removed- (525 MB heap size)
 PASS  -filename removed- (531 MB heap size)

Jest v24.0.0-alpha.4, Jest Circus v24.0.0-alpha.4

Not sure best way to test #6965, so I picked the latest alpha release.

node --expose-gc ./node_modules/.bin/jest --logHeapUsage --runInBand --config=./jest.config.js

 PASS  -filename removed- (73 MB heap size)
 PASS  -filename removed- (79 MB heap size)
 PASS  -filename removed- (85 MB heap size)
 PASS  -filename removed- (95 MB heap size)
 PASS  -filename removed- (13.113s, 212 MB heap size)
 PASS  -filename removed- (215 MB heap size)
 PASS  -filename removed- (224 MB heap size)
 PASS  -filename removed- (47.523s, 284 MB heap size)
 PASS  -filename removed- (285 MB heap size)
 PASS  -filename removed- (298 MB heap size)
 PASS  -filename removed- (304 MB heap size)
 PASS  -filename removed- (8.881s, 350 MB heap size)
 PASS  -filename removed- (354 MB heap size)
 PASS  -filename removed- (369 MB heap size)
 PASS  -filename removed- (375 MB heap size)

If running it for the full set of test would be more useful let me know specifically what would be helpful and I'll find time.

[SimenB]

The subset is fine 🙂 #6965 just landed for jasmine, not circus, I was wondering if you could eager evaluate all stacks and see if it helped

[dylang]

hi @SimenB - I'm not sure what you mean by eager evaluate all stacks.

[SimenB]

See the description in #6965. But essentially, every place we do new Error in jest-circus, add a line below it that does error.stack = error.stack. This changes the getter into just a string, thus it can free the references it's keeping

[dylang]

For what it's worth, I've updated jest-circus-memory-leak-repo for 24.8.0 and I'm still detecting a memory leak when using JEST_CIRCUS=1.

https://github.com/dylang/jest-circus-memory-leak-repo

[dylang]

This seems to be fixed, thank you!

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