Python GC也会关闭文件吗? [英] Does Python GC close files too?

问题描述

请考虑以下Python(2.x)代码:

Consider the following piece of Python (2.x) code:

for line in open('foo').readlines():
    print line.rstrip()

我认为，由于打开的文件仍然未被引用，因此必须自动将其关闭.我已经阅读了有关Python中的垃圾收集器的信息，该垃圾收集器释放了未使用的对象分配的内存. GC是否也足以处理文件?

I assume that since the open file remains unreferenced it has to be closed automatically. I have read about garbage collector in Python which frees memory allocated by unused objects. Is GC general enough to handle the files too?

推荐答案

来自 docs (python 3.6):

Taken from the docs (python 3.6):

如果您不使用with关键字，则应调用f.close()关闭文件并立即释放文件使用的所有系统资源.如果您未明确关闭文件， Python的垃圾收集器最终将破坏该对象并为您关闭打开的文件，但该文件可能会保持打开状态一段时间.另一个风险是，不同的Python实现将在不同的时间进行清理.

If you’re not using the with keyword, then you should call f.close() to close the file and immediately free up any system resources used by it. If you don’t explicitly close a file, Python’s garbage collector will eventually destroy the object and close the open file for you, but the file may stay open for a while. Another risk is that different Python implementations will do this clean-up at different times.

是的，文件将自动关闭，但是为了控制该过程，您应该自己关闭或使用with语句:

So yes, the file will be closed automatically, but in order to be in control of the process you should do so yourself or use a with statement:

with open('foo') as foo_file
    for line in foo_file.readlines():
        print line.rstrip()

一旦with块结束，

foo_file将被清除

foo_file will be clsoed once the with block ends

在python 2.7 docs 中，措辞有所不同:

In the python 2.7 docs, the wording is different:

使用完文件后，请调用f.close()将其关闭并释放 打开文件占用的所有系统资源.打电话后 f.close()，尝试使用文件对象将自动失败.

When you’re done with a file, call f.close() to close it and free up any system resources taken up by the open file. After calling f.close(), attempts to use the file object will automatically fail.

所以我假设您不应该依赖垃圾收集器自动为您关闭文件，而只需手动/使用with

so I assume that you should not depend on the garbage collector automatically closing files for you and just do it manually/use with

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