Emitting signals from a thread will run the handler in the same thread. You
shouldn't call gtk functions from a thread other than the main one. If you
insist on doing so you have to make sure to acquire the GDK lock first by
wrapping your code in gtk.gdk.threads_enter() ... gtk.gdk.threads_leave()
calls. In this case you also have to call gtk.gdk.thread_init() as
otherwise the main loop will never release the GDK lock. The easier
solution is to push the signal emission to the main thread by replacing
self.emit('ASignal') with gobject.idle_add(self.emit, 'ASignal') which
guarantees the handler will also run in the main thread (which already has
the GDK lock).
Regards.
On Thu, Jul 25, 2013 at 4:56 PM, Todong Ma <gbstac...@gmail.com> wrote:
> Hi, everyone
>
> I met a problem that UI will be blocked forever if I emit a signal from a
> thread to create a message dialog.
> Following code will reproduce the issue, please let me give a short
> explanation: AThread thread defines a custom signal named "ASignal", and
> the signal handler is aSignal() function of MainWindow class. The aSignal()
> function is used to display a message dialog. Emitting "ASignal" signal
> will display the message dialog successfully but the UI is blocked forever.
>
> import gtk
> import gobject
> import threading
>
> class AThread(threading.Thread, gobject.GObject):
> __gsignals__ = {
> 'ASignal': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE, ())
> }
> def __init__(self):
> threading.Thread.__init__(self)
> gobject.GObject.__init__(self)
>
> def run(self):
> self.emit('ASignal')
>
> class MainWindow(gtk.Window):
> def aSignal(self, obj):
> dialog = gtk.MessageDialog(self, gtk.DIALOG_DESTROY_WITH_PARENT,
> gtk.MESSAGE_INFO, gtk.BUTTONS_CLOSE, 'asdfasf')
> dialog.run()
> dialog.destroy()
>
> gobject.threads_init()
>
> w = MainWindow()
>
> t = AThread()
> t.connect('ASignal', w.aSignal)
> t.start()
>
> gtk.main()
>
>
> Any suggestion is appreciated.
>
> Thanks,
>
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> Read the PyGTK FAQ: http://faq.pygtk.org/
>
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