为什么python中的函数/方法调用很昂贵? [英] Why is a function/method call in python expensive?

问题描述

在这篇博文中，Guido van Rossum 说函数调用可能很昂贵，但我不明白为什么，也不明白会贵多少.

一个简单的函数调用会给您的代码增加多少延迟，为什么?

解决方案

一个函数调用要求挂起当前执行帧，并创建一个新的帧并压入堆栈.与许多其他操作相比，这是相对昂贵的.

您可以使用 timeit 模块测量所需的确切时间:

<预><代码>>>>导入时间>>>def f(): 通过...>>>timeit.timeit(f)0.15175890922546387

对于一百万次调用一个空函数来说，这是 1/6 秒；您将所需的时间与您想放入函数的时间进行比较；如果性能有问题，则需要考虑 0.15 秒.

In this post, Guido van Rossum says that a function call may be expensive, but I do not understand why nor how much expensive can be.

How much delay adds to your code a simple function call and why?

解决方案

A function call requires that the current execution frame is suspended, and a new frame is created and pushed on the stack. This is relatively expensive, compared to many other operations.

You can measure the exact time required with the timeit module:

>>> import timeit
>>> def f(): pass
... 
>>> timeit.timeit(f)
0.15175890922546387

That's 1/6th of a second for a million calls to an empty function; you'd compare the time required with whatever you are thinking of putting in a function; the 0.15 second would need to taken into account, if performance is an issue.

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