[ python-Bugs-701836 ] Thread running (os.system or popen#)

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Bugs item #701836, was opened at 2003-03-11 18:46
Message generated for change (Comment added) made by facundobatista
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=701836&group_id=5470

Category: Python Interpreter Core
Group: Python 2.2.2
Status: Open
Resolution: None
Priority: 5
Submitted By: Johan Fredrik Öhman (johanfo)
Assigned to: Nobody/Anonymous (nobody)
Summary: Thread running (os.system or popen#)

Initial Comment:
Bottom line: Some programs may lock up when 
spawned from a thread.


>>> import thread, os
>>> thread.start_new_thread(os.system,
("/usr/sbin/ntpdate ifi.uio.no",))

This starts a program "ntpdate" from a Python thread.  
Usually this is no problem. Ntpdate, is a simple program 
to adjust the clock of the system. However, when 
ntpdate is started from a thread it locks up and newer 
exits!!   With my limited debugging knowledge, it sems 
as it hangs in a "poll()" kernel call, however, this could 
be misleading. (I used stacktrace -p <pid>)



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>Comment By: Facundo Batista (facundobatista)
Date: 2005-01-15 17:34

Message:
Logged In: YES 
user_id=752496

Works ok for me:

Python 2.3.4 (#1, Oct 26 2004, 16:42:40)
[GCC 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)] on linux2
Type "help", "copyright", "credits" or "license" for more
information.
>>> import thread, os
>>> thread.start_new_thread(os.system,("/usr/sbin/ntpdate
ifi.uio.no",))
-1210684496
>>>


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Comment By: Facundo Batista (facundobatista)
Date: 2005-01-15 17:34

Message:
Logged In: YES 
user_id=752496

Please, could you verify if this problem persists in Python 2.3.4
or 2.4?

If yes, in which version? Can you provide a test case?

If the problem is solved, from which version?

Note that if you fail to answer in one month, I'll close this bug
as "Won't fix".

Thank you! 

.    Facundo

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Comment By: Johan Fredrik Öhman (johanfo)
Date: 2003-03-12 13:12

Message:
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user_id=556425

I have verified this bug on both Redhat 8.0 and SuSE 8.1, 
linux yes.

Signal is one possible path, filedescriptors another.  I read 
somwhere that there was some issues with pthreads forking 
and filedescriptors.  However, this is not my area (too low 
level)....

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Comment By: Michael Hudson (mwh)
Date: 2003-03-12 09:40

Message:
Logged In: YES 
user_id=6656

IIRC, threads other than the main thread get a signal mask
that blocks everything.  That could be the problem, but I
don't know what to do about it...

What platform are you on?  Linux?

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