[Flaky] Possible flaky tests from Paddle

[masahi]

https://ci.tlcpack.ai/blue/organizations/jenkins/tvm/detail/PR-9954/7/pipeline/ tests/python/frontend/paddlepaddle/test_forward.py::test_forward_math_api tests/scripts/setup-pytest-env.sh: line 35: 2565288 Segmentation fault (Saw it multiple times)

https://ci.tlcpack.ai/blue/organizations/jenkins/tvm/detail/PR-9954/9/pipeline/ FAILED tests/python/frontend/paddlepaddle/test_forward.py::test_forward_ones_like (Just got this the first time)

@jiangjiajun

[jiangjiajun]

This is really flaky...， Is this reproducible?

[masahi]

I don't know, have you tried running these tests many times on your end? It could be a CI env issue.

[heliqi]

After repeated attempts, I reproduce one of the problems. I'm solving it...

[heliqi]

Paddle test_forwar use 'tvm.testing.enabled_targets()' and DEFAULT_TEST_TARGETS contain the 'nvptx' target.

when target == 'nvptx', the 'acos' of relay op run error. There are many op's that are no longer supported by 'nvptx' targe?
I see that some of the 'nvptx' target tests have also been removed from the PR.

@masahi

[masahi]

Yeah, nvptx causes some issues (not supporting RTX 3000 series in recent LLVM etc). I think it's totally fine to customize what targets to test on per frontend, and per individual test.

But this is not the cause of segfault and other flaky-test in question, right?

[heliqi]

After I filtered the 'nvptx' target, I repeated the code (tests/python/frontend/paddlepaddle/test_forward.py::test_forward_math_api) several times without a Segfault.

The previous error was also not Segfault and I didn't reproduce the CI mistake... 😅

[electriclilies]

I noticed that some std::moves in uses of the WithFields COW constuctors were causing potential use-after-frees. I haven't been following this thread that closely, but I figured that this might be the cause of some of the flaky segfaults we've been seeing recently. In #10009 I remove these std::moves-- might be worth seeing if it improves anything.

[areusch]

this is continuing to happen on main: https://ci.tlcpack.ai/blue/organizations/jenkins/tvm/detail/main/3415/pipeline

(the error is hard to find, but if you click Show complete log, you see:

[2022-05-31T20:31:52.944Z] tests/python/frontend/paddlepaddle/test_forward.py::test_forward_math_api tests/scripts/setup-pytest-env.sh: line 49: 44482 Segmentation fault      (core dumped) TVM_FFI=${ffi_type} python3 -m pytest -o "junit_suite_name=${suite_name}" "--junit-xml=${TVM_PYTEST_RESULT_DIR}/${suite_name}.xml" "--junit-prefix=${ffi_type}" "$@"
[2022-05-31T20:31:52.944Z] + exit_code=139

@jiangjiajun any ideas here?

[jiangjiajun]

The test_forward_math_api includes lots of operators's unit test, it will loop for many times, maybe it's one of the reason, let's split this big unit test first, this will also give us a clear error message.

We will send a pull request to split test_forward_math_api try to fix this problem. @heliqi

[heliqi]

@areusch @jiangjiajun
#11537