Re: Python leaks in cyclic garbage collection
Wild guess: maybe when python exits they are called but sys.stdout has already been closed and nothing gets written on it anymore. Certainly NOT. class Foo(): def __init__(self): self.b = Bar(self) def __del__(self): print Free Foo class Bar(): def __init__(self, f): self.f = f def __del__(self): print Free Bar f = Foo() print f.b.f.b.f.b.f.b.f.b.f.b.f.b.f.b.f print f.b.f.b.f.b.f.b.f.b.f.b.f.b.f.b.f.b *Console output:*** __main__.Foo instance at 0x00AF7328 __main__.Bar instance at 0x00AF7350 D:\v3 -- http://mail.python.org/mailman/listinfo/python-list
Re: Python leaks in cyclic garbage collection
Il giorno 19/feb/2011, alle ore 05.10, moerchendiser2k3 ha scritto: Hi, I have some problems with Python and the garbage collection. In the following piece of code I create a simple gargabe collection but I am still wondering why the finalizers are never called - at least on exit of Py they should be called somehow. What do I miss here? I know, there is no deterministic way how to resolve this though. class Foo(): def __init__(self): self.b=Bar(self) def __del__(self): print Free Foo class Bar(): def __init__(self, f): self.f=f def __del__(self): print Free Bar f=Foo() print f -- http://mail.python.org/mailman/listinfo/python-list Wild guess: maybe when python exits they are called but sys.stdout has already been closed and nothing gets written on it anymore. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python leaks in cyclic garbage collection
Thanks for your answers! They really helped me out!! :) -- http://mail.python.org/mailman/listinfo/python-list
Python leaks in cyclic garbage collection
Hi, I have some problems with Python and the garbage collection. In the following piece of code I create a simple gargabe collection but I am still wondering why the finalizers are never called - at least on exit of Py they should be called somehow. What do I miss here? I know, there is no deterministic way how to resolve this though. class Foo(): def __init__(self): self.b=Bar(self) def __del__(self): print Free Foo class Bar(): def __init__(self, f): self.f=f def __del__(self): print Free Bar f=Foo() print f -- http://mail.python.org/mailman/listinfo/python-list
Re: Python leaks in cyclic garbage collection
Thanks a lot for any help!!! Bye, moerchendiser2k3 -- http://mail.python.org/mailman/listinfo/python-list
Re: Python leaks in cyclic garbage collection
On Fri, Feb 18, 2011 at 8:10 PM, moerchendiser2k3 googler.1.webmas...@spamgourmet.com wrote: Hi, I have some problems with Python and the garbage collection. In the following piece of code I create a simple gargabe collection but I am still wondering why the finalizers are never called - at least on exit of Py they should be called somehow. What do I miss here? code snippet involving circularly-referenced objects with __del__ methods snipped Read The Fine Manual (all emphases added): http://docs.python.org/reference/datamodel.html#object.__del__ : ***It is not guaranteed that __del__() methods are called for objects that still exist when the interpreter exits.*** Note: [...] x.__del__() — [...] is only called when x‘s reference count reaches zero. Some common situations that may prevent the reference count of an object from going to zero include: circular references between objects [...] Circular references which are garbage are detected when the option cycle detector is enabled (it’s on by default), ***but can only be cleaned up if there are no Python-level __del__() methods involved***. Refer to the documentation for the `gc` module for more information about how __del__() methods are handled by the cycle detector, particularly the description of the `garbage` value. And following the pointer to gc.garbage's docs: http://docs.python.org/library/gc.html#gc.garbage : Objects that have __del__() methods and are part of a reference cycle ***cause the entire reference cycle to be uncollectable*** [...] Python doesn’t collect such cycles automatically because, in general, it isn’t possible for Python to guess a safe order in which to run the __del__() methods. [...] It’s generally better to avoid the issue by not creating cycles containing objects with __del__() methods Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Python leaks in cyclic garbage collection
On Fri, 18 Feb 2011 20:49:09 -0800, Chris Rebert wrote: And following the pointer to gc.garbage's docs: http://docs.python.org/library/gc.html#gc.garbage : Objects that have __del__() methods and are part of a reference cycle ***cause the entire reference cycle to be uncollectable*** [...] Python doesn’t collect such cycles automatically because, in general, it isn’t possible for Python to guess a safe order in which to run the __del__() methods. [...] It’s generally better to avoid the issue by not creating cycles containing objects with __del__() methods Another solution is to manually break the cycle, perhaps by providing a close method, and requiring the caller to use it. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
