Documentation of os.exec*() provides confusing information about "flushing file descriptors"

Documentation

The documentation of os.exec*() says:

The current process is replaced immediately. Open file objects and descriptors are not flushed, so if there may be data buffered on these open files, you should flush them using sys.stdout.flush() or os.fsync() before calling an exec* function.

However, os.fsync() flushs OS buffers to disk, and has nothing to with flushing userspace buffer to OS.

Linked PRs

• gh-133333

从 issue 中引用的 os.exec*() 文档开始，比较 sys.stdout.flush() 和 os.fsync() 的作用。确认措辞准确地区分了用户空间缓冲与 OS 缓冲，然后验证修订后的文档是否清楚地说明了在 exec*() 之前应刷新什么。