[Vimprobable-users] [HOWTO] Debugging Vimprobable with Valgrind

[Hans-Peter D. <hpd...@gm...>]

Hi,

Valgrind is a nice tool to debug memory leaks. Here is what I had to do
to make it work well with vimprobable and in particular webkit:

To run vimprobable under valgrind, use the following command:

  G_SLICE=always-malloc G_DEBUG=gc-friendly \
  valgrind --leak-check=full --suppressions=valgrind_suppressions.supp \
           --demangle=no --smc-check=all --num-callers=50 \
           --log-file=valgrind.out ./vimprobable2

G_SLICE and G_DEBUG are there to make glib more valgrind friendly and
are explained at [1].

The various options I used are:

    --leak-check=full: Give details about every leak

    --suppressions: Suppress errors that are unrelated to
        vimprobable. I will attach this file.

    --demangle=no: Webkit is C++ and thus uses mangled C-symbols. Valgrind
        shouldn't try to print the demangled symbols, because we need the
        mangled ones for the suppressions file.

    --smc-check=all: Detect self-modifying code. This is needed for Webkits
        JIT-compiler.

    --num-callers=50: Webkit and glib have very deep stack-traces. Show
        as much as possible of them.

Regarding the suppressions file: Without it, valgrind shows many errors
and leaks in libraries that are not caused by vimprobable. I tried to
suppress all "definitely lost" warnings, that are not vimprobable's
fault. I didn't do anything about "possibly lost" messages, because I'm
unsure where most of them come from. You can skip them for now and
concentrate on "definitely lost".

I tested this (especially the suppressions file) only on one system, so
it could happen that your system shows entirely different errors. You
would have to write your own suppressions in this case.

Also, I certainly didn't exercise all code paths with my testing, so
there could be many more leaks lingering.


HP


[1]: http://developer.gnome.org/glib/2.28/glib-running.html

--
Hans-Peter Deifel