Documentation for os.environ should say that os.environ caching behavior is undefined if other threads are setting environment values

Documentation

It says here:

This mapping is captured the first time the os module is imported, typically during Python startup as part of processing site.py. Changes to the environment made after this time are not reflected in os.environ, except for changes made by modifying os.environ directly.

It should mention the caveat that such cashing would cause undefined behavior or/and crashes when other threads would be setting environment values. This would be true at least on Linux and FreeBSD.

The same should be mentioned in the documentation of the function that initializes the Python interpreter and caches environment.

These functions are not thread-safe.

Linked PRs

• gh-152979

查看 issue 中链接的 os.environ 文档，以及会缓存环境的解释器初始化函数的文档。将所要求的线程安全注意事项与链接的 PR gh-152979 进行比较。当两个相关的文档部分都准确描述其他线程修改环境值时的行为时，即表示完成。