[Vm-dev] [Pharo-users] macOS VM builds with AddressSanitizer/LeakSanitizer

[Ben Coman]

Hi Manuel,

This level question would be better handled on pharo-dev and vm-dev mail
lists (forwarded a copy).
http://lists.pharo.org/mailman/listinfo/pharo-dev_lists.pharo.org
http://lists.squeakfoundation.org/mailman/listinfo/vm-dev

On Fri, 25 Jan 2019 at 16:09, Manuel Leuenberger <leuenberger at inf.unibe.ch>
wrote:

> Hi,
>
> Anybody has experience building the VM (pharo.cog.spur) on macOS with
> custom compiler and flags?
>
> I am observing a memory leak on macOS Sierra/Pharo 7/GToolkit. I cannot
> precisely locate the issue, e.g. I cannot reliably reproduce the problem.
> So I tried to use AddressSanitizer/LeakSanitizer with custom debug builds
> of the VM and libMoz2D (used by GToolkit). As building on Linux is easier
> than on macOS, I got myself some help from a colleague and we managed to
> build those two artifacts on Linux by sprinkling "-g3 -O0 -fsanitize=leak
> -fsanitize-memory-track-origins" into the CFLAGS wherever they appear or
> are picked up. This works fine on Debian 9 with "CC=clang-6.0
> CXX=clang++-6.0 ./mvm -d" and some on-the-fly patches for other breaking
> things.
>
> Unfortunately, I cannot reproduce the problem on Linux, so it seems to be
> platform specific. Even more so, I seem to be the only one observing the
> issue. Other GToolkit users do not report this issue. As these kind of
> issues are freaking me out, I cannot let go and need to learn what causes
> them. So, here I am, trying to build the VM on macOS Sierra and miserably
> failing to include the sanitizer tags with Clang and giving me those tasty
> leak reports on VM shutdown.
>
> The leak is not observable in the image memory, i.e. the image size
> reported by the VM is not growing, I am suspecting FFI, possibly in Moz2D,
> to leak.
> The FFI registry in the VM also does not report many or large surviving
> objects, so I would assume the problem to be either on the plugin or VM
> side.
>
> My two concrete questions are:
> 1. Is it even feasible to detect leaks with this approach? E.g., how does
> the VM behave on shutdown? Will the leaks show up in the report or will
> they not be covered, as the VM actually frees everything before shutting
> down?
> 2. How do I swap compiler and inject flags on macOS builds? On Linux it
> was fairly easily done by replacing some variables. But on macOS, Xcode
> seems to like to mess with me. I got myself Clang-6.0 on macOS from
> MacPorts, the same as version as I took on Linux. I can build the VM with
> this, but it there is no leak report on VM shutdown. Anybody has an idea
> how to debug the build?
>
> Bonus question: Can the VM provide an inspectable view of all the
> allocated memory to the image? That would be perfect. I think Luke Gorrie
> does some magic like this in his Studio for core dumps etc.
>
> Cheers,
> Manuel
>
>
>
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