Opened 4 years ago
Last modified 4 years ago
#31509 closed New feature
Enable faulthandler automatically during tests — at Initial Version
| Reported by: | Adam Johnson | Owned by: | nobody |
|---|---|---|---|
| Component: | Testing framework | Version: | dev |
| Severity: | Normal | Keywords: | |
| Cc: | Triage Stage: | Ready for checkin | |
| Has patch: | yes | Needs documentation: | no |
| Needs tests: | no | Patch needs improvement: | no |
| Easy pickings: | yes | UI/UX: | no |
Description
Sometimes when testing one discovers a "hang". This can be hard to diagnose since default test output just includes dots, so one can't tell which test has hung. Also hangs can be random, so hard to diagnose.
In such cases, faulthandler is useful to enable, as killing the process will output a stack trace for each thread.
Tests can be run using faulthandler with python -X faulthandler manage.py test. However this needs both knowledge that it exists, and re-running the tests, when the hang might be non-deterministic.
Pytest automatically enables faulthandler and provides the option to disable it. I suggest we replicate the same in Django's DiscoverRunner - call faulthandler.enable() at the start of tests, unless disabled with a flag --no-faulthandler.
Searching for past issues, it seems we've had three tickets where faulthandler was recommended for diagnosis: https://code.djangoproject.com/search?q=faulthandler . Additionally there are probably other cases where no progress was made on a bug because of lack of faulthandler knowledge.