Re: [Gimp-developer] Error when calling gimp_file_load() from concurrent thread

[Alessandro Francesconi <misterbirra hotmail it>]

On 14/07/2012 22:01, Michael Natterer wrote:
> On Sat, 2012-07-14 at 21:15 +0200, Alessandro Francesconi wrote:
> > Hello, I'm the author of BIMP, Batch Image Manipulation Plugin
> > (http://www.alessandrofrancesconi.it/projects/bimp/) and I'm extending
> > this tool with the possibility to stop the whole batch process by
> > clicking on a GTK button.
> >
> > For that I'm enabling a multi threading functionality. In few words,
> > when clicking on the "Apply" button, the function that does the batch
> > process is called from a newly created thread, with the use of
> > 'g_thread_new ("thread_name", bimp_start_batch, data)'.
> >
> > I'm facing a strange problem: everything that is called from the
> > concurrent thread (precisely by 'bimp_start_batch' function) works,
> > except when it's time to call 'gimp_file_load' for opening the image
> > files... because the program crashes with this kind of message in the
> > console:
> >
> > (bimp:6646): LibGimpBase-ERROR **: gimp_wire_read_msg: could not find
> > handler for message: 1952804208
> >
> > Is it something related to the fact that gimp_file_load() tries to send
> > a message but, having it been called from a secondary thread, the
> > message "never reaches its destination"?
> > Does the group of functions here
> > http://developer.gimp.org/api/2.0/libgimp/libgimp-gimpmessage.html and
> > here
> > http://developer.gimp.org/api/2.0/libgimp/libgimp-gimpplugin.html#gimp-plugin-set-pdb-error-handler
> > can help me?
> >
> > In other words, what's the correct way to call gimp_* functions from a
> > concurrent thread? Thank you so much for your help.
> You *must not* call GIMP API from anywhere but the main thread, and
> you *should* not call GTK+ API from anything but the main thread,
> or your stuff won't work on win32/osx.
>
> You might find GIMP API that works multi-threaded, but definitely not
> any that talk to the core via the PDB.
>
> --mitch
Damn, it's the worst thing I could expect (and by the way it seems 
really strange because GTK itself has a lot of multithreading APIs here 
http://developer.gnome.org/glib/2.28/glib-Threads.html)...
Any ideas on how to solvethis situation?

-Ale