[Python-Dev] Behavior change in subprocess.py

[Delaney, Timothy (Tim)]

Hah - just found it. I even remember reading it...
 
I'll update the SF tracker (1526203) with your analysis.
 
Tim Delaney

	-----Original Message-----
	From: python-dev-bounces+tdelaney=avaya.com at python.org
[mailto:python-dev-bounces+tdelaney=avaya.com at python.org] On Behalf Of
Kevin Jacobs <jacobs at bioinformed.com>
	Sent: Thursday, 13 July 2006 12:33 AM
	To: python-dev at python.org
	Subject: [Python-Dev] Behavior change in subprocess.py
	
	
	During my testing of Python 2.5b2, I've found something that may
be worthy of discussion.  I suspect that recent GC and finalization
changes have altered the behavior of the Popen object in subprocess.py.
I am now getting many many many finalization warnings in my code like: 
	
	Exception exceptions.AttributeError: "'NoneType' object has no
attribute 'append'" in <bound method Popen.__del__ of <subprocess.Popen
object at 0x2aaaab910950>> ignored
	
	Is this a bug or a feature?  Personally, I'd like to see these
messages silenced, since it is being generated during interpreter
shutdown.  The following patch does the trick for me: 
	
	--- /usr/local/lib/python2.5/subprocess.py      2006-07-11
14:11:59.000000000 -0400
	+++ subprocess.py       2006-07-12 10:17:09.000000000 -0400
	@@ -613,7 +613,7 @@
	             return
	         # In case the child hasn't been waited on, check if
it's done. 
	         self.poll(_deadstate=sys.maxint)
	-        if self.returncode is None:
	+        if self.returncode is None and _active is not None:
	             # Child is still running, keep us alive until we
can wait on it. 
	             _active.append(self)
	
	
	Note that popen.py does something similar, though I am not
convinced that the test is right or if it is doing something more
subtle:
	
	    def __del__(self):
	        # In case the child hasn't been waited on, check if it's
done. 
	        self.poll(_deadstate=sys.maxint)
	        if self.sts < 0:
	            if _active:
	                # Child is still running, keep us alive until we
can wait on it.
	                _active.append(self) 
	
	Regards,
	-Kevin
	
	

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