[Zope-dev] RE: Memory Leak Question

[Jim Fulton]

Dan Pozmanter wrote:
> Sure thing:
> 
> I was mucking around in _Acquisition.c with getattr, findattr, etc,
> and I noticed checked to see if my code was leaky.
> It was!  I then checked just vanilla code, and found the same
> leak (only much much smaller).
> 
> So here is what I did to make things more visible:
> In Wrapper_getattro, I simply added a while loop,
> and another call to Wrapper_findattr before the return statement "
> return Wrapper_findattr(self, oname, NULL, NULL, NULL, 1, 1, 0, 0);".
> Loop it 1000 times for some fireworks, 5 times for a more modest
> display.
> 
> Looping other calls (such as Wrapper_acquire before "    return
> Wrapper_acquire(self, oname, filter, extra, orig, explicit, 
> 			   containment);" in Wrapper_findattr)
> does not produce a similar leak.
> 
> So.  To reproduce:
> 
> Edit _Acquisition.c
> Function Wrapper_getattro
> add 
> "    int i = 0;"
> at the top.
> then, if self->obj ... and all that, add:
> "
> while (i < xyz) {
> Wrapper_findattr(self, oname, NULL, NULL, NULL, 1, 1, 0, 0);
> i++;
> }
> "

Wrapper_findattr (like, for example, PyObject_GetAttr) returns a
*new* reference to the result of the attribute access.  So this would,
of course, cause a leak.  If you have code that is calling Wrapper_findattr
and not taking care of the new reference, then it is not surprizing that
you have a leak.

Jim

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