[New-bugs-announce] [issue32542] memory not freed, aka memory leak continues...

[Michael Felt]

New submission from Michael Felt <michael at felt.demon.nl>:

in issue25582 - the issue is not (yet) resolved. Perhaps this one can be closed and issue25582 reopened.

Both from python2-2.7.14 and "git master" I am getting:

michael at x071:[/data/prj/python/git/gcc-python3-3.7]./python -m unittest -v ctypes.test.test_pointers          <
test_abstract (ctypes.test.test_pointers.PointersTestCase) ... ok
test_basic (ctypes.test.test_pointers.PointersTestCase) ... ok
test_basics (ctypes.test.test_pointers.PointersTestCase) ... ok
test_bug_1467852 (ctypes.test.test_pointers.PointersTestCase) ... ok
test_c_void_p (ctypes.test.test_pointers.PointersTestCase) ... ok
test_callbacks_with_pointers (ctypes.test.test_pointers.PointersTestCase) ... ok
test_change_pointers (ctypes.test.test_pointers.PointersTestCase) ... ok
test_charpp (ctypes.test.test_pointers.PointersTestCase)
Test that a character pointer-to-pointer is correctly passed ... ok
test_from_address (ctypes.test.test_pointers.PointersTestCase) ... ok
test_other (ctypes.test.test_pointers.PointersTestCase) ... ok
test_pass_pointers (ctypes.test.test_pointers.PointersTestCase) ... ok
test_pointer_crash (ctypes.test.test_pointers.PointersTestCase) ... ok
test_pointer_type_name (ctypes.test.test_pointers.PointersTestCase) ... ok
test_pointer_type_str_name (ctypes.test.test_pointers.PointersTestCase) ... ERROR
test_pointers_bool (ctypes.test.test_pointers.PointersTestCase) ... ok

======================================================================
ERROR: test_pointer_type_str_name (ctypes.test.test_pointers.PointersTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/data/prj/python/git/gcc-python3-3.7/Lib/ctypes/test/test_pointers.py", line 208, in test_pointer_type_str_name
    large_string = 'T' * 2 ** 25
MemoryError

----------------------------------------------------------------------
Ran 15 tests in 0.319s

FAILED (errors=1)

+++++
Looking at the test source:

  +196      def test_pointer_type_name(self):
  +197          LargeNamedType = type('T' * 2 ** 25, (Structure,), {})
  +198          self.assertTrue(POINTER(LargeNamedType))
  +199
  +200          # to not leak references, we must clean _pointer_type_cache
  +201          from ctypes import _pointer_type_cache
  +202          del _pointer_type_cache[LargeNamedType]
  +203
  +204      def test_pointer_type_str_name(self):
  +205          large_string = 'T' * 2 ** 25
  +206          P = POINTER(large_string)
  +207          self.assertTrue(P)
  +208
  +209          # to not leak references, we must clean _pointer_type_cache
  +210          from ctypes import _pointer_type_cache
  +211          del _pointer_type_cache[id(P)]

****
After changing the exponent (** 25) to "** 23" on either line 197 OR 205 
- ALL test succeed -
After changing the exponent to " ** 24" on BOTH lines 197 and 205, all tests pass.

****
My concern is that the "patch" from issue 25582 the 
"del _pointer_type_cache[]" statement is not freeing memory.

+++++
What can I add to the test to debug!
+++++
p.s. - results are the same on AIX (5.3 and 6.1) Python2-2.7.14 and Pyhton3-3.7.X (git master). Compiler does not seem to matter (both xlc and gcc).
32-bit, default memory model (256 MByte max - aka (2 ** 28) for data and malloc. I could also try changing the memory model - but will do that only if the test, by definition, is not "free()ing" the memory used, when done.

HTH
Michael

----------
components: Tests
messages: 309869
nosy: Michael.Felt
priority: normal
severity: normal
status: open
title: memory not freed, aka memory leak continues...
type: behavior
versions: Python 2.7, Python 3.7

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue32542>
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