Hangup when printing empty string to unbuffered stdout

Crash report

What happened?

$ sudo python3 -u -c 'print(""); print("foo")'
Hangup

When printing an empty string to unbuffered stdout, under certain circumstances (e.g. when running on AIX under sudo, screen, tmux), the user session including the Python interpreter will terminate.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Output from running 'python -VV' on the command line:

Python 3.12.13 (main, Mar 6 2026, 03:56:12) [GCC 10.3.0]

Linked PRs

• gh-148774

首先使用无缓冲的 stdout 重现报告中的命令，重点关注 issue 中描述的 AIX、sudo、screen 和 tmux 情况。检查链接的 PR gh-148774，以及其中指出的相关 CPython stdout/write 路径。完成的标准是该命令不再终止用户会话，并且该行为由适当的回归测试覆盖。