[Python-bugs-list] [ python-Bugs-231273 ] [windows] os.popen doens't kill subprocess when interrupted

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Bugs item #231273, was opened at 2001-02-06 17:43
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=231273&group_id=5470

Category: Windows
Group: Platform-specific
Status: Open
Resolution: None
Priority: 5
Submitted By: Christophe Gouiran (cgouiran)
Assigned to: Mark Hammond (mhammond)
Summary: [windows] os.popen doens't kill subprocess when interrupted

Initial Comment:
Hi, in the following script I liked to make an interface to the contig program(http://www.sysinternals.com)

As the popen invocation can be a long time process (since it walks recursively trough directories) I press CTRL-C sometimes and the contig continues to run.

I use Python 2.0 (BeOpen version) under WinNT 4.0(SP 4)

Maybe I made a mistake in the following script ?

-------------------------------------------------

#! /usr/bin/env python

import sys;
import os;
import re;

content = ""

mm = re.compile("Processing (.+)?:\nFragments: (\d+)?");

output = os.popen("contig -a -s *.*");

while(1):
  line = output.readline();
	
  if line == '':
    break
	
    content += line;


status = output.close()

if status:
  print("Error contig : "+`status`+"("+os.strerror(status)+")");
  sys.exit(12);

print mm.findall(content)

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>Comment By: Martin v. Löwis (loewis)
Date: 2002-07-11 10:22

Message:
Logged In: YES 
user_id=21627

Delivery of Ctrl-C (SIGINT) is platform-specific; I see no
need to provide a uniform behaviour across systems.

On Unix, the terminal device sends SIGINT to all processes
that have this terminal as their controlling terminal; the
idea is that logging off that terminal will also terminate
all incomplete processes (unless they have been detached
from the terminal). If Windows treats Ctrl-C in a different
way, traditionally, I think platform conventions should
overrule Python-uniformness.

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Comment By: Mark Hammond (mhammond)
Date: 2002-07-11 08:57

Message:
Logged In: YES 
user_id=14198

Martin: you wrote:
> I can't see the bug here, though - why *should* 
> terminating the parent process terminate the child 
> processes also?

I think there is a bug here - certainly a difference
compared to Linux.  Consider a script popen_child.py:

import time

for i in range(20):
    print i
    time.sleep(1)

and consider popen_parent.py

import os

f=os.popen("python popen_child.py")
print f.read()
f.close()

When popen_parent.py is executed on Linux and I press
Ctrl+C, I see *both* processes terminate with
KeyboardInterrupt.  On Windows, the parent process is killed
but the child continues until it dies of other causes.

I may be able to fix it but now I am not even sure it is a
bug :)

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Comment By: Martin v. Löwis (loewis)
Date: 2001-06-04 22:46

Message:
Logged In: YES 
user_id=21627

A patch for this problem is in progress at

https://sourceforge.net/tracker/index.php?func=detail&aid=403743&group_id=5470&atid=305470

I can't see the bug here, though - why *should* 
terminating the parent process terminate the child 
processes also?


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Comment By: Tim Peters (tim_one)
Date: 2001-02-10 00:50

Message:
Poor Mark.  I assign anything with "popen + Windows" to you, because you're the only one who ever makes progress on them <wink>.  Offhand, I can't see how Ctrl+C directed at Python *could* interrupt a spawned process.

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=231273&group_id=5470