Re: Valgrind and FontForge: now with less grit in your grind

You're now on my list of heroes.



On Sat, Aug 2, 2014 at 2:54 PM, Thomas Shinnick <[email protected]> wrote:

> So I wanted to rebuild Python and then use Python's supplied Valgrind
> suppression file to make the reports much less confusing, but ran into
> problems.  And then thought "but not everyone wants to rebuild Python.
> Maybe I could just rudely crudely remove all the Python 'noise' with new
> suppression files...?"
>
> So I did, and now Valgrind report of FontForge initialization shows 12
> entries instead of 200+ without these suppressions.  Even after doing a lot
> of moving around in a font and a few UI operations the report has only ~100
> entries.  It is now **much easier** to see FontForge's leaks and oddities.
>
> I've built up Valgrind suppressions files for both Python and Pango
> gotchas.  These eliminate much or nearly all of the 'noise' from problems
> running with embedded Python or Pango libraries.
>
> Note however that the Python is for version 3.  I'll be working on one for
> Python 2 shortly.
>
> For lack of another idea, I've dumped the two suppression files into gists:
>     Valgrind suppression file for FontForge built with Python 3
> <https://gist.github.com/tshinnic/2febc414cee2a7f96066>
>     Valgrind suppression file for FontForge built with Pango
> <https://gist.github.com/tshinnic/1aa5d249ceede82abf1a>
>
> I've been running Valgrind with these like so:
>     valgrind --suppressions=valgrind_ff_pango.supp
> --suppressions=valgrind_ff_p3.supp
>           --log-file=valgrind --leak-check=full --track-origins=yes
> fontforge
>
>
> For example of 'noise', one source of 'leaks' by Python is from its
> 'interning'
> strings.  Dozens of Valgrind report entries.  A completely unseen pool
> of memory, I'm not sure they clean this up on termination of stand-alone
> Python, but we certainly don't get it cleaned up when running the
> embedded Python.  Much better to ignore these completely.
>
> I've tested the suppression files on both Ubuntu and Fedora.  I'm
> hoping people will *test on other platforms*.  While I'm taking great
> advantage of the Valgrind wildcarding features to try to
> *make therules more portable*, there are differences that can pop up from
> platform to platform.  One possibility is changed library filenames. :(
>
> A very strange thing (to me anyway) is that Valgrind doesn't see any
> address or value errors running under Fedora, but *does* see those
> running under Ubuntu.  And Ubuntu hits far fewer of other kinds of
> entries.  Very strange...
>
> And of course it is possible I'm also seeing differences between
> Python versions, 3.3 on my Fedora and 3.4 on Ubuntu.
>
> Please test on your favorite platforms and exercising your least favorite
> scenarios.
> If you see Python or Pango entries pop up I'd like to hear the details.
>
>
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