Question

利用objgraph,我发现这样的物体:

“InstanceState

粉碎的垃圾收集器是否像这样处理周期,还是会泄漏?

略为广泛看待 lo:

“Wider

Answer 1

灰色标准计算机制不能自由循环,因此,你的例子中的结构就会漏掉。

rel=“noreferer”> ,但因违约而得以提供,如果其组成部分不能从外部获得,并且没有<_del__(>>>/code>, methods>>>>>>,则该结构应能够自由运行。

If they do, the garbage collector will not free them because it cannot determine a safe order to run these __del__() methods.

Answer 2

关于Frédéric的答复范围,, docs中“参比量”部分对补充周期探测作了解释。

自2006年以来我认为,解释情况是证实我理解的好办法,这里就是一些例子。有两个班级:

class WithDel(object):
    def __del__(self):
        print "deleting %s object at %s" % (self.__class__.__name__, id(self))


class NoDel(object):
    pass

由于重新计算,产生物体和从<代码>a中失去参考,触发__del>方法:

>>> a = WithDel()
>>> a = None  # leaving the WithDel object with no references 
deleting WithDel object at 4299615184

If we make a reference loop between two objects with no __del__ method, all is still leak-free, this time thanks to the cycle detection. First, enable the garbage-collection debug output:

>>> import gc
>>> gc.set_debug(gc.DEBUG_COLLECTABLE | gc.DEBUG_UNCOLLECTABLE | gc.DEBUG_OBJECTS)

然后在两个目标之间提供参考文件:

>>> a = NoDel(); b = NoDel()
>>> a.other = b; b.other = a  # cyclical reference
>>> a = None; b = None # Leave only the reference-cycle
>>> gc.collect()
gc: collectable <NoDel 0x10046ed50>
gc: collectable <NoDel 0x10046ed90>
gc: collectable <dict 0x100376c20>
gc: collectable <dict 0x100376b00>
4
>>> gc.garbage
[]

(dict is from the Object Internal __dict__/code> Depende)



罚款:until 周期中的哪怕一个物体包含一个_del_。 方法:

>>> a = NoDel(); b = WithDel()
>>> a.other = b; b.other = a
>>> a = None; b = None
>>> gc.collect()
gc: uncollectable <WithDel 0x10046edd0>
gc: uncollectable <dict 0x100376b00>
gc: uncollectable <NoDel 0x10046ed90>
gc: uncollectable <dict 0x100376c20>
4
>>> gc.garbage
[<__main__.WithDel object at 0x10046edd0>]


正如保罗提到的那样,该休息室可与http://docs.python.org/library/weakref.html“rel=“noreferer”>weakref:

>>> import weakref
>>> a = NoDel(); b = WithDel()
>>> a.other = weakref.ref(b)
>>> b.other = a # could also be a weakref

接着,<代码>b查询 尽管循环:



>>> b = None
deleting WithDel object at 4299656848
>>> a.other
<weakref at 0x10045b9f0; dead>

Oh, objgraph ,将有益地表示,<>_del> 类似的方法

Answer 3

甲型六氯环己烷旨在转移所有活物体,以发现和消除没有外部参照的参考周期。

您可以证实,这是通过运行<代码>gc.( )和随后印刷gc.garbage <>/code>和

Answer 4

If you use weakrefs for your parent pointers, then GC will happen normally.

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