Legacy ImageMagick Discussions Archive

The last time I checked, the MacPorts version of ImageMagick didn't have a built-in option for disabling OpenMP. You have to modify the portfile. See http://www.ctcms.nist.gov/oof/oof2/install.html#osx for the instructions that we give our users.

-- Steve

No. I tried setting it to 1 and also to 0, just to be sure. It seems that any call to an OpenMP routine makes the program crash, even if it's just querying the number of OpenMP threads, or if there aren't any OpenMP threads.

magick wrote:We know of no run-time method to disable OpenMP. If you discover a method, let us know.

Yes, I would expect it to, because it works with Linux pthreads. But the whole point is ImageMagick is relying on OpenMP behavior that is not defined in the OpenMP or pthreads standards, does not work with OS X pthreads, and is not guaranteed to work with future versions of Linux pthreads. By not ...

It's short, I'll just post it here. All it does is try to open an image file on a subthread. // -*- C++ -*- // compile with // g++ -o magicktest magicktest.C `Magick++-config --cppflags --ldflags --libs` // #include <Magick++.h> #include <pthread.h> #include <iostream> void *subthread(void *threadid ...

Its libgomp that is seg faulting, not the ImageMagick API. Yes, I know that. I wasn't implying that ImageMagick was seg faulting. But ImageMagick is using OpenMP in a way that causes OpenMP to seg fault if ImageMagick is used within a posix thread. This severely limits the ways in which ImageMagick ...

No, using "#pragma omp single" on the ImageMagick calls doesn't help. It just moves the location of the seg fault from the OpenMP calls in ImageMagick to the OpenMP code generated in the calling routine by the pragma. I don't doubt that ImageMagick is much faster with OpenMP. But it's also much ...

My understanding, from discussions at OpenMP.org, is that the OpenMP standard doesn't say anything about how it interacts with threads, and so the behavior is undefined. See http://openmp.org/forum/viewtopic.php?f=3&t=642&p=2556&hilit=pthread#p2556, for example. This means that libMagick++ can't be ...

I forgot to mention that I'm using IM 6.6.1 and OS X 10.6.4.

Hi -- I develop and distribute a program that uses pthreads and Magick++. Since pthreads aren't compatible with OpenMP on many platforms (including OS X) users of our software have to build Magick++ with the --disable-openmp option. (If it's omitted, the program crashes on the first Magick++ call ...