什么是Python中的引用循环？ [英] What is a reference cycle in python?

问题描述

我已经查看过Python的官方文档，但我似乎无法找到参考周期。任何人都可以澄清它是什么，因为我想了解GC模块。

解决方案

引用循环就是指一个或多个引用对象的对象，这样如果你（几乎）最简单的参考周期是有两个对象 a
$ b

/ code>和 b 表示彼此：



  a.other = b 
 b.some_attr = a 
  

天真的垃圾收集器严格遵守对象是否被另一个对象引用。在这种情况下，如果 a 和 b 都没有被别的东西引用，它们仍然互相引用，一个天真的垃圾收集器可能无法回收内存。 （我不知道Python是否可以被引用循环所困住）。编辑：最简单的引用循环是引用自身的对象： / p>



  a = [] 
 a.append（a）
  




I have looked in the official documentation for python, but i cannot seem to find what a reference cycle is. Could anyone please clarify what it is for me, as i am trying to understand the GC module. Thank you in advance for your replies.

解决方案

A reference cycle simply means one or more objects referencing each other, such that if you drew it out on paper with arrows representing the dependencies you would see a cycle.

The (almost) simplest reference cycle is having two objects a and b that refer to each other:

a.other = b
b.some_attr = a

Naive garbage collectors work strictly off of whether or not an object is referenced by another object. In this case, if both a and b are not referred to by anything else, they still refer to each other and a naive garbage collector may not reclaim the memory. (I don't know if Python can be trapped by reference cycles or not, though.)

EDIT: The simplest reference cycle is an object that refers to itself:

a = []
a.append(a)

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