[Python-Dev] [ python-Bugs-1124637 ] test_subprocess is far too slow (fwd) (original) (raw)

Guido van Rossum gvanrossum at gmail.com
Thu Feb 17 16:30:58 CET 2005

I'd like to have your opinion on this bug. Personally, I'd prefer to keep testnoleaking as it is, but if you think otherwise...

One thing that actually can motivate that testsubprocess takes 20% of the overall time is that this test is a good generic Python stress test - this test might catch some other startup race condition, for example.

A suite of unit tests is a precious thing. We want to test as much as we can, and as thoroughly as possible; but at the same time we want the test to run reasonably fast. If the test takes too long, human nature being what it is, this will actually cause less thorough testing because developers don't feel like running the test suite after each small change, and then we get frequent problems where someone breaks the build because they couldn't wait to run the unit test.

(For example, where I work we have a Java test suite that takes 25 minutes to run. The build is broken on a daily basis by developers (including me) who make a small change and check it in believing it won't break anything.)

The Python test suite already has a way (the -u flag) to distinguish between "regular" broad-coverage testing and deep coverage for specific (or all) areas. Let's keep the really long-running tests out of the regular test suite.

There used to be a farm of machines that did nothing but run the test suite ("snake-farm"). This seems to have stopped (it was run by volunteers at a Swedish university). Maybe we should revive such an effort, and make sure it runs with -u all.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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