mingo + ts-jest creates memory leak to crash

[j]

Latest mingo with ts-jest creates memory leak / heap limit error.

Here's a simple repro: https://github.com/j/mingo-error

[kofrasa]

Thanks a lot for the repro project. This is quite a weird issue to debug.

I haven't delved deeper into the node memory management to fully understand what could be happening as I suspect it would be an unnecessary rabbit hole.

Nonetheless I found these possibly related issues searching the jest project .

• ESM Modules implementations leak memory jestjs/jest#9959
• JavaScript heap out of memory after upgrade to Jest 26 jestjs/jest#9980
• jest-worker appears to create error: "Allocation failed - JavaScript heap out of memory" jestjs/jest#9346
• Jest leaks memory from required modules with closures over imports jestjs/jest#6814
• [Memory Leak] on module loading jestjs/jest#6738
• Memory Leak on ridiculously simple repo jestjs/jest#7874

It is rather unlikely that querying a single object should cause GC issues. Over 500 unit tests run for mingo without any memory problems. The culprits if any would be the esm module introduce in 3.0.0 or jest itself. The shear number of memory leak issues open with the jest project leads me to believe it is responsible.

Are you using the same version of jest without error against older versions of mingo (e.g 2.x.x without ESM support)?

[kofrasa]

See comment jestjs/jest#7874 (comment) which suggests the same type of problem described in this issue.

Please open an issue or add your vote to a relevant one in the jest project.

[j]

@kofrasa

Yes, I have dozens of dependencies and a huge mono-repo under one jest test suite, and it was just the mingo v3 version that caused the crash. The error mentioned esm from what I remember. Reverting back to 2.x.x fixed the issue, so I'm running the old version of mingo ATM. I used the same versions of everything else and tracked it down to mingo.

[j]

You can clone my repository, set mingo to 2.x and tests will pass.

[kofrasa]

The fingers point to the dependency on esm. Something is amiss in how it interacts with jest.

In any case, that does not have to be a hard dependency. Users are free to pick their preferred bundling solution so the right thing to do here is remove it.

[kofrasa]

Fix in latest version. esm module removed.

➜  mingo-error git:(master) ✗ node_modules/jest/bin/jest.js
 PASS  src/query.test.ts
  ✓ works (3 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        2.831 s, estimated 3 s
Ran all test suites.
➜  mingo-error git:(master) ✗