Hi Franck,
The __del__ method of all OCC wrapped object is overloaded. Object
deletion management is delegated to the GarbageCollector class: all
deleted objects are added to the
GarbageCollector.garbage._collected_objects list (that's why you
actually don't see any decref in your sample):
Python 2.6.1 (r261:67515, Jul 7 2009, 23:51:51)
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from OCC.Standard import *
>>> GarbageCollector.garbage._collected_objects
[]
>>> s = Standard_Transient()
>>> del s
>>> GarbageCollector.garbage._collected_objects
[<OCC.Standard.Standard_Transient; proxy of <Swig Object of type
'Standard_Transient *' at 0x1004b9c90> >]
>>>
I've been currently working on the GarbageCollector module. I
definitely have to write a document about the way OCC/python/SWIG
handle memory management.
Thomas
2010/2/18 Frank Conradie <fr...@qfin.net <mailto:fr...@qfin.net>>
Sorry Thomas, but _kill_pointed does not solve the issue. It looks
like the SWIG wrapper objects are not DECREF'd at all - see the
example below, which shows that calling "del" on a shape does not
decrease the ref count of the SWIG wrapper object at all:
import gc
import sys
import gc
from OCC.gp import *
from OCC.BRepPrimAPI import *
from OCC.TopExp import *
from OCC.TopoDS import *
w = 0.1
fp1 = (0.,0.,0.)
fp2 = (w,w,w)
mkbox = BRepPrimAPI_MakeBox(gp_Pnt(fp1[0],fp1[1],fp1[2]),
gp_Pnt(fp2[0],fp2[1],fp2[2]))
s = mkbox.Shell()
class MemTest(object):
pass
mem = MemTest()
# The next 3 lines show that _kill_pointed nullifies the
underlying shape
print 'before: IsNull=', s.IsNull()
s._kill_pointed()
print 'after: IsNull=', s.IsNull()
print gc.get_count()
print gc.collect()
print gc.get_count()
for o in gc.get_objects():
if isinstance(o, TopoDS_Shape) or isinstance(o, MemTest):
print type(o), sys.getrefcount(o)
# The next 2 lines should remove s and mem from gc.get_objects,
but it only removes mem!!!
del s
del mem
print gc.get_count()
print gc.collect()
print gc.get_count()
for o in gc.get_objects():
if isinstance(o, TopoDS_Shape) or isinstance(o, MemTest):
print type(o), sys.getrefcount(o)
I'm not sure where to go from here.
- Frank
On 17/02/2010 8:29 PM, Thomas Paviot wrote:
2010/2/18 Frank Conradie <fr...@qfin.net <mailto:fr...@qfin.net>>
Hi guys,
Hi Franck,
After running into serious memory use issues with our geometric
processing algorithm, I have done a simple experiment that
seems to show
that wrapper garbage collection does not work at all. Try the
code
below, and you should run out of memory in no time:
import gc
from OCC.gp import *
from OCC.BRepPrimAPI import *
from OCC.TopExp import *
def TestMemory():
w = 0.1
fp1 = (0.,0.,0.)
fp2 = (w,w,w)
mkbox = BRepPrimAPI_MakeBox(gp_Pnt(fp1[0],fp1[1],fp1[2]),
gp_Pnt(fp2[0],fp2[1],fp2[2]))
s1 = mkbox.Shell()
e = TopExp_Explorer()
for i in range(1000000):
print i
e.Init(s1, TopAbs_FACE)
while e.More():
sh = e.Current()
e.Next()
if not (i % 1000):
print 'Collecting garbage...'
gc.collect()
while 1:
pass
Not sure if this is a known issue or not,
It's known to be an issue, see:
* http://www.opencascade.org/org/forum/thread_17702/
* the changelog of the 0.4 release
but it certainly makes the
wrapper problematic for our current purposes. If you can
point me at the
right place in the wrapper generator I can maybe try and help.
The standard python gc module can not be used with pythonOCC:
it's perfectly suitable to manage python objects deletion, but
fails to properly handle the C++ pointed objects. A
GarbageCollector class is available from any pythonOCC module
you're using. For instance:
Python 2.6.1 (r261:67515, Jul 7 2009, 23:51:51)
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more
information.
>>> from OCC.Standard import *
>>> GarbageCollector
<module 'OCC.GarbageCollector' from
'/Library/Python/2.6/site-packages/OCC/GarbageCollector.pyc'>
>>> dir(GarbageCollector)
['GarbageCollector', '__builtins__', '__doc__', '__file__',
'__name__', '__package__', 'garbage', 'sys']
>>> GarbageCollector.garbage
<OCC.GarbageCollector.GarbageCollector object at 0x100593e10>
>>> dir(GarbageCollector.garbage)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__',
'__getattribute__', '__hash__', '__init__', '__module__',
'__new__', '__reduce__', '__reduce_ex__', '__repr__',
'__setattr__', '__sizeof__', '__str__', '__subclasshook__',
'__weakref__', '_collected_objects', 'collect_object',
'get_collected', 'purge']
The source code of this module is here:
http://svn.gna.org/viewcvs/pythonocc/trunk/src/wrapper/GarbageCollector.py?rev=706&view=markup
<http://svn.gna.org/viewcvs/pythonocc/trunk/src/wrapper/GarbageCollector.py?rev=706&view=markup>
In a few words, if you want to completely free memory:
GarbageCollector.garbage.purge()
If you want to free one specific object, use the _kill_pointed()
method of that object (Nulify, Clear, Destroy won't work).
I'll take time to write a more detailed message tomorrow about
that topic.
Thanks,
Frank Conradie
Qfinsoft
All the best,
Thomas
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