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Author Michael.Felt
Recipients Michael.Felt, vstinner
Date 2021-03-31.14:56:08
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On 30/03/2021 09:40, STINNER Victor wrote:
> STINNER Victor <> added the comment:
> A core dump is a very bad sign of health.
> Can you please try to bisect which test is causing the segfault using bisect_cmd? Try the command:
> ./python -m test.bisect_cmd -o bisect --fail-env-changed test_importlib
> The command should takes 10-60 minutes, and you should see the number of tests decreasing. I hope that at the end, the command will identify a single method triggering the crash.
> At the end, the create "bisect" file contains the test methods causing the bug.
> Then you can re-run tests with:
> ./python -m test --fail-env-changed test_importlib --matchfile=bisect
I like this!:

Fortunately, it did not take 10  minutes:

Writing 1 tests into bisect

Tests (1):

Output written into bisect
Bisection completed in 34 iterations and 0:00:28

>> The core dump is caused by SIGTRAP. I need help to learn how to stop the core dump from being cleaned up so I can load it into dbx and hopefully understand/learn with sub-test is actually having issues.
> You can re-run the test without libregrtest by running it directly. Example:
> ./python -m test.test_importlib test_spec.Frozen_ModuleSpecMethodsTests.test_reload -v

While - to use your example - using the normal verbose test syntax I do 
see the test you reference:

* test_reload 
(test.test_importlib.test_spec.Frozen_ModuleSpecMethodsTests) ... ok

but, when I run your example (and many variations) I always get 
something such as:

So, still - closer - but not quite there with:


./python -m test.test_importlib 
test_spec.Frozen_ModuleSpecMethodsTests.test_reload -v
test_spec (unittest.loader._FailedTest) ... ERROR

ERROR: test_spec (unittest.loader._FailedTest)
AttributeError: module '__main__' has no attribute 'test_spec'

Ran 1 test in 0.000s

FAILED (errors=1)

> It should create a core dump in the current directory, or you run the command in your favorite debugger.
> My notes on debugging a Python crash:
> ----------
> nosy: +vstinner
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File name Uploaded
OpenPGP_0x722BFDB61F396FC2.asc Michael.Felt, 2021-03-31.14:56:08
Date User Action Args
2021-03-31 14:56:09Michael.Feltsetrecipients: + Michael.Felt, vstinner
2021-03-31 14:56:09Michael.Feltlinkissue43665 messages
2021-03-31 14:56:08Michael.Feltcreate