[Python-Dev] Valgrind on 2.2.2

[Michael Gilfix]

On Mon, Oct 28 @ 20:15, Guido van Rossum wrote:
> >   * A pointer to the start of the block is found. This usually
> >   indicates programming sloppiness; since the block is still pointed
> >   at, the programmer could, at least in principle, free'd it before
> >   program exit.
> 
> Booh again.  Lots of globals get initialized with pointers to
> malloc'ed blocks that are never freed.  There are never called "leaks"
> in other leak detectors, just "alive at exit".  I think valgrind
> actually doesn't call these leaks either.

  I don't think valgrind reports this first case. Only the second and
third, from what I gathered in the docs.

> >   Possibly is the second case and definitely lost is the third case.
> > The definitely lost, in my experience, tends to mean you just forgot
> > to free a pointer. The possibly lost usually means that some memory
> > rot occurred, where it's not clear which pointer is causing the mem
> > leak.
> 
> How much Python extension coding (in C) have you done?  In Python, it
> almost never is a matter of forgetting to free() -- it's usually a
> matter of forgetting to DECREF, and sometimes a matter of doing an
> unnecessary INCREF.

  I've done a fair bit, but to explain valgrind things, I figured it was
best to talk the valgrind talk. Either way, it comes to the same thing.
Glad that helped.

                      -- Mike

-- 
Michael Gilfix
mgilfix@eecs.tufts.edu

For my gpg public key:
http://www.eecs.tufts.edu/~mgilfix/contact.html