Re: [gta-list] Imagemagick test fails randomly

[Martin Lambers]

Hi Volker!

On Sun, 03 Feb 2013 14:27:32 +0100, Volker Froehlich wrote:
> The imagemagick test of gtatool 1.5 seems to fail randomly in Fedora
> 16 and 17. It always seems to pass in Fedora 18 though. I didn't
> notice this behaviour with gtatool 1.4. libgta version is 1.0.2 in
> all cases.
> 
> Imagemagick versions are:
> 
> F16: 6.7.0.10 (fails randomly)
> F17: 6.7.5.6 (fails randomly)
> F18: 6.7.7.5 (seems working)

Thanks for reporting this! I cannot reproduce the problem on Ubuntu,
but I have two guesses: 
1) Some versions of ImageMagick might write a file creation stamp into
a generated image, so that 'cmp' in the test script fails.
2) The random crashes may be related to threading/locking issues inside
ImageMagick. I have seen similar problems on Windows, but not yet on
Linux. I have no idea how the test can 'PASS' in that case; the test
scripts use 'set -e' which should abort immediately.

I pushed a patch that changes the library initialization, which might
make it more predictable, and that changes the image format used in the
test script to ppm, which cannot store metadata. See
http://git.savannah.gnu.org/cgit/gta.git/commit/?id=8a4cba71a35fa19eb58c111d6a376e181f642ae0

This should at least fix 1), but I'm not sure about 2).

To be absolutely identical to gtatool-1.4.0 code, I could remove the
InitializeMagick() call altogether. But that is not recommended and
does not work on all platforms.

I also have a patch that replaces ImageMagick with GraphicsMagick, but
on Windows that leads to the exact same threading problems, so I'm not
sure it is worth trying that on Linux.

Greetings,
Martin