[XML-SIG] Wierd bug in DOM cloneNode (or copy.deepcopy)

Tue, 27 Oct 1998 14:21:50 -0500

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I have been trying to figure out what is crashing the Python interpreter on
Windows NT when I ran across a strange bug.  My python program runs fine on
Win 98 but will crash on NT 4.0.  It may take a few hours of running, but
eventually it crashes.  I was hoping that if I could create a small test
file to reproduce the problem, I could get Guido to look into it.  So... I
took my DOM test file and put in an infinite loop to see if it would crash
on NT.  When I did, I noticed that __del__() is called more than __init__()
on xml.dom.core._nodeData when cloneNode() is used.  I don't know what kind
of wierd voodoo happens in the copy.deepcopy() function but it looks like
it messes up the reference counts somehow.

That leads to a question about Python, how stable is the memory management?
Should I be surprised that it runs forever on Win98 but not on WinNT?  Does
copy.deepcopy do things it should not?

Good news! While I was writing this, my test file did crash the interpreter
on NT.  I'll comment out the cloneNode line and try again.  Then I'm going
to load NT service pack 4 and try again.  The exception was in malloc().  I
think I might have been out of memory.  That's strange, if __del__ gets
called too many times, I would think the exception would be in free().
Anyone feel like figuring this one out?

(See attached file: test.py)

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