This gtk-fortran example demonstrates you can write a GTK application that uses the modern Fortran parallel features like coarrays (Fortran 2008) or collective routines, teams, events (Fortran 2018). The main principle is that everything concerning the GUI must be managed by the first Fortran image using structures like if (this_image() == 1) then ...GUI STUFF... end if.
The application is drawing a Buddhabrot and finally save the picture in a file.
Each Fortran image is computing its own Buddhabrot, and they are regularly summed with the co_sum() intrinsic. The process is very similar to what is done in astrophotography.
The Fortran 2018 intrinsics event post() and event_query() are used to manage the closing of the GTK window: if the user closes it before the end, the image 1 post an event to each other image, which can then exit the scientific computation. These events are also used when the scientific computation is achieved: in that case image 1 is entering the GTK main loop to keep the window opened, and the other images are waiting that the image 1 post an event. To keep them idle, we use the g_usleep() GLib function.
Note that when you close the window before the end of the computation, it can take up to 10 seconds for all the images to stop.
For GFortran, you need to install OpenCoarrays and type that command (4 images here):
$ caf -O3 GUI_and_computation.f90 main.f90 && cafrun -n 4 ./a.outAnd for ifort:
$ ifort -O3 -coarray GUI_and_computation.f90 main.f90 && ./a.outNote that gtk-fortran must have been built with the same compiler.
You can also use the build.sh script to build and run the example. The default compiler is GFortran but you can use ifort with:
$ FC='ifort' ./build.sh- Curcic, Milan. Modern Fortran - Building efficient parallel applications, Manning Publications, 1st edition, novembre 2020, ISBN 978-1-61729-528-7.
- Metcalf, Michael, John Ker Reid, et Malcolm Cohen. Modern Fortran Explained: Incorporating Fortran 2018. Numerical Mathematics and Scientific Computation. Oxford (England): Oxford University Press, 2018, ISBN 978-0-19-185002-8.