Python优化(-O或PYTHONOPTIMIZE)有什么作用? [英] What does Python optimization (-O or PYTHONOPTIMIZE) do?

问题描述

文档只说Python解释器执行基本优化"，而没有涉及任何细节.显然，它取决于实现方式，但是有什么方法可以使人们知道可以优化哪种类型的东西，以及可以节省多少运行时间?

The docs only say that Python interpreter performs "basic optimizations", without going into any detail. Obviously, it's implementation dependent, but is there any way to get a feel for what type of things could be optimized, and how much run-time savings it could generate?

使用-O是否有不利之处?

Is there any downside to using -O?

我唯一知道的是-O禁用了assert，但是对于在生产中仍然可能出错的事情，大概不应该使用assert.

The only thing I know is that -O disables assert, but presumably one shouldn't use assert for things that could still go wrong in production.

推荐答案

在Python 2.7中，-O具有以下作用:

In Python 2.7, -O has the following effect:

• 字节码扩展名更改为.pyo
• sys.flags.optimize设置为1
• __debug__是错误的
• 断言不会被执行

• the byte code extension changes to .pyo
• sys.flags.optimize gets set to 1
• __debug__ is False
• asserts don't get executed

此外，-OO具有以下作用:

• sys.flags.optimize设置为2
• 文档字符串不可用

要验证不同版本的CPython的效果，请grep Py_OptimizeFlag的源代码.

To verify the effect for a different release of CPython, grep the source code for Py_OptimizeFlag.

链接到官方文档: https://docs.python .org/2.7/tutorial/modules.html#compiled-python-files

这篇关于Python优化(-O或PYTHONOPTIMIZE)有什么作用?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！