[New-bugs-announce] [issue24283] Print not safe in signal handlers

[Devin Jeanpierre]

New submission from Devin Jeanpierre:

The code attached runs a while loop that prints, and has a signal handler that also prints. There is a thread that constantly fires off signals, but this is just to ensure the condition for the bug happens -- this is a bug with signal handling, not threads -- I can trigger a RuntimeError (... with a missing message?) by commenting out the threading lines and instead running a separate process "while true; do kill -s SIGUSR1 4687; done".

Traceback:

$ python3 threading_print_test.py 
hello
world
Traceback (most recent call last):
  File "/usr/local/google/home/devinj/Downloads/threading_print_test.py", line 36, in <module>
    main()
  File "/usr/local/google/home/devinj/Downloads/threading_print_test.py", line 30, in main
    print("world")
  File "/usr/local/google/home/devinj/Downloads/threading_print_test.py", line 13, in print_hello
    print("hello")
RuntimeError: reentrant call inside <_io.BufferedWriter name='<stdout>'>

----------
files: threading_print_test.py
messages: 244020
nosy: Devin Jeanpierre, haypo
priority: normal
severity: normal
status: open
title: Print not safe in signal handlers
Added file: http://bugs.python.org/file39491/threading_print_test.py

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue24283>
_______________________________________