running test_ctypes 25 times in a row causes it to fail #45938

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1. gvanrossum commented on Dec 11, 2007

   

   gvanrossum

   on Dec 11, 2007

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   In debug mode, on my Ubuntu Linux box, this fails on the last iteration:

   $ ./python Lib/test/regrtest.py -R:20 test_ctypes
   test_ctypes
   beginning 25 repetitions
   1234567890123456789012345
   ........................test test_ctypes failed -- Traceback (most
   recent call last):
     File
   "/usr/local/google/home/guido/python/py3kd/Lib/ctypes/test/test_values.py",
   line 18, in test_an_integer
       self.failUnlessEqual(x*2, ctdll.get_an_integer())
   AssertionError: 2818572288 != -1476395008

   1 test failed:
   test_ctypes
   [104230 refs]
   $

   Also, when using -R:19, I get some random leaks reported of 33 or -33
   references leaked. Does this test use threads? It seems to have a race
   condition.
2. gvanrossum

   assigned

   theller

   on Dec 11, 2007
3. gvanrossum commented on Dec 12, 2007

   

   gvanrossum

   on Dec 12, 2007

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   Thanks! (I agree with Eric Smith that this is mysterious for the
   innocent bystander.)

   Also, what about the -33/+33 leaks? I suppose these are harmless, but
   it would be better if the test reliably didn't report leaks...
4. gvanrossum

   closed this as completedon Dec 12, 2007
5. theller commented on Dec 12, 2007

   

   theller

   on Dec 12, 2007

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   Guido van Rossum schrieb:

   Thanks! (I agree with Eric Smith that this is mysterious for the
   innocent bystander.)

   I have added a comment.

   Also, what about the -33/+33 leaks? I suppose these are harmless, but
   it would be better if the test reliably didn't report leaks...

   I am using my own definition of leaking: a test is leaking if references
   grow without bounds ;-).

   Ok, I found that the test in charge is Lib/ctypes/test/test_loading.py,
   LoaderTest.test_find. This test uses the ctypes.util.find_library function,
   which contains several calls to os.popen(...).read().

   The minimal code reporting the -33/+33 leaks that I found is simply this:

   os.popen('ls').read()

   Is there a problem in "os.popen(...)", or do I something wrong here?
6. gvanrossum commented on Dec 12, 2007

   

   gvanrossum

   on Dec 12, 2007

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   The minimal code reporting the -33/+33 leaks that I found is simply this:

   os.popen('ls').read()

   Is there a problem in "os.popen(...)", or do I something wrong here?

   Try this instead:

    p = os.popen('ls')
    try:
      x = p.read()
    finally:
      p.close()

   IOW close the pipe explicitly. That should make the code execute in a
   more reproducible fashion. I've fixed this in ctypes/util.py now:
   r59477.
7. theller commented on Dec 12, 2007

   

   theller

   on Dec 12, 2007

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   more reproducible fashion. I've fixed this in ctypes/util.py now:
   r59477.

   Cool! And the 'leak' is gone.
8. ezio-melotti

   transferred this issue fromon Apr 10, 2022