question about ctrl-d and atexit with threads

Darren Dale dsdale24 at gmail.com
Fri Mar 6 18:55:28 CET 2009


On Mar 5, 6:27 pm, "Gabriel Genellina" <gagsl-... at yahoo.com.ar> wrote:
> En Thu, 05 Mar 2009 15:26:18 -0200, Darren Dale <dsdal... at gmail.com>  
> escribió:
>
>
>
> > On Mar 5, 12:02 pm, s... at pobox.com wrote:
> >> What happens if you simply call
>
> >>     my_thread.setDaemon(True)
>
> >> (or in Python 2.6):
>
> >>     my_thread.daemon = True
>
> >> ?  That is the documented way to exit worker threads when you want the
> >> application to exit.  From the threading module docs:
>
> >>     "The entire Python program exits when no alive non-daemon threads  
> >> are
> >>     left."
>
> > Thank you Skip, that solves the problem. I'm still curious what the
> > difference is between python's handling of sys.exit and EOF, but its
> > academic at this point.
>
> Some applications open a new window for each document they're handling.  
> When you close the last window, the application exits ("close" does an  
> implicit "quit"). Note that this does *not* happen when you close the  
> first, original document you opened, but when there are no more documents  
> open. The first document is not special in this regard.
>
> Python threads work the same way; a thread may finish, but as long as  
> there are other threads alive, the process continues running. Only after  
> the last thread has finished, the application quits. The main thread *is*  
> special sometimes, but not in this aspect,
> Setting daemon=True is like telling Python "I don't care about this  
> thread; don't wait for it if that's the only thing you have to do".
>
> Calling sys.exit() is an explicit statement: "I want this program to  
> finish now" (or as soon as possible). It doesn't wait for the remaining  
> threads (unless you explicitely do so, like in your code).

Right, I understand all that. I don't understand how calling sys.exit
at the python command line is different from invoking ctrl-D. They
should both trigger the same mechanism if they are advertised as
equivalent mechanisms for exiting the interpreter, shouldnt they?



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