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Title: Delayed signals in the REPL on OpenBSD (possibly libpthread related)
Type: behavior Stage:
Components: Interpreter Core Versions: Python 3.1, Python 2.7
Status: closed Resolution: out of date
Dependencies: Superseder:
Assigned To: Nosy List: djmdjm, henry.precheur, neologix, skrah, vstinner
Priority: normal Keywords:

Created on 2010-05-14 16:26 by skrah, last changed 2022-04-11 14:57 by admin. This issue is now closed.

Messages (6)
msg105720 - (view) Author: Stefan Krah (skrah) * (Python committer) Date: 2010-05-14 16:26
On OpenBSD, SIGINT handling in the REPL is delayed until further input:

Python 2.7b2+ (trunk:81162, May 14 2010, 14:47:52) 
[GCC 3.3.5 (propolice)] on openbsd4
Type "help", "copyright", "credits" or "license" for more information.
>>>  <= here Ctrl-C is pressed but nothing appears
Only after hitting <Return> a traceback appears:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>

This behavior was introduced (exposed by?) r68460.

When Python is compiled without threads, the behavior is normal.
msg106124 - (view) Author: Henry Precheur (henry.precheur) Date: 2010-05-20 01:59
The bug is also present with Python 3.1 on OpenBSD 4.7-current.
msg140972 - (view) Author: Charles-François Natali (neologix) * (Python committer) Date: 2011-07-23 11:08
> This behavior was introduced (exposed by?) r68460.

After a quick look, I don't see anything wrong with r68460, but it might very well have exposed this problem which was lurking before.

> When Python is compiled without threads, the behavior is normal.

We've already had some problems - especially on *BSD - when mixing signals and threads (and it might be even worse on OpenBSD, since pthreads are implemented in user-space). However, IIUC, in this case you only have a single thread, right?

Could you post the output of an strace (well, ktrace on OpenBSD)?
Is Python compiled with readline support?
msg141007 - (view) Author: Stefan Krah (skrah) * (Python committer) Date: 2011-07-23 19:25
I know, the OpenBSD libpthread has problems. I listed some possible
candidates in #8712.

For instance:;content-type=text%2Fplain

The comment says: "siginterrupt not reliable (does not mix well with threading"

To answer your questions:

1) Yes, there is only a single thread.

2) I only have an old OpenBSD 4.5, so it's not so useful to test
   there; I know Philip Guenther fixed some libpthread problems
   in the meantime.
msg141012 - (view) Author: Stefan Krah (skrah) * (Python committer) Date: 2011-07-23 19:58
I forgot: readline support is enabled, and there are known problems:
msg180124 - (view) Author: Stefan Krah (skrah) * (Python committer) Date: 2013-01-17 12:13
Fixed in OpenBSD 5.2.
Date User Action Args
2022-04-11 14:57:01adminsetgithub: 52960
2013-01-17 12:13:33skrahsetstatus: open -> closed
resolution: out of date
messages: + msg180124
2011-10-17 01:07:50vstinnersetnosy: + vstinner
2011-07-23 19:58:55skrahsetmessages: + msg141012
2011-07-23 19:25:57skrahsetmessages: + msg141007
2011-07-23 11:08:23neologixsetnosy: + neologix
messages: + msg140972
2010-05-20 02:09:01henry.precheursetversions: + Python 3.1
2010-05-20 01:59:16henry.precheursetmessages: + msg106124
2010-05-14 16:26:02skrahcreate