On Thu, May 31, 2012 at 12:22 AM, Matteo Landi <mat...@matteolandi.net> wrote: > Hi list, > recently I started to work on an application [1] which makes use of the > Tkinter > module to handle interaction with the user. Simply put, the app is a text > widget displaying a file filtered by given criteria, with a handy feature that > the window is raised each time a new line is added to the widget. > > The application mainly consists of three threads: the first one, the file > processor, reads the file, filters the lines of interest, and pushes them into > a shared queue (henceforth `lines_queue`); the second one, the gui_updater, > pops elements from `lines_queue`, and schedule GUI updates using the > `after_idle` method of the Tkinter module; finally the last one, the worker > spawner, receives commands by the gui (by means of a shared queue, > `filters_queue`), and drives the application, terminating or spawning new > threads. > > For example, let's see what happens when you start the application, fill the > filter entry and press Enter button: > 1 the associated even handler is scheduled (we should be inside the Tkinter > mainloop thread), and the filter is pushed into `filters_queue`; > 2 the worker spawner receives the new filter, terminate a possibly running > working thread, and once done, create a new file processor; > 3 the file processor actually processes the file and fills the `lines_queue` > with the lines matching given filter; > 4 the gui updater schedules GUI updates as soon as items are pushed into > `lines_queue` > 5 Tkinter mainloop thread updates the gui when idle > > What happens when the main window is closed? Here is how I implemented the > graceful shutdown of the app: > 1 a quit event is scheduled and a _special_ message is pushed into both > `filter_queue` and `lines_queue` > 2 the gui updater threads receives the _special_ message, and terminates > 3 the worker spawner receives the message, terminates the working thread and > interrupts her execution. > 4 Tk.quit() is called after the quit event handler, and we finally quit the > mainloop > > Honestly speaking, I see no issues with the algorithm presented above; > however, > if I close the window in the middle of updates of the text widget, the > applications hangs indefinitely. On the other hand, everything works as > expected if I close the app when the file processor, for example, is waiting > for > new content to filter. > > I put some logging messages to analyze the deadlock (?!), and noticed that > both > the worker spawner and the file processor are terminated correctly. The only > thread still active for some strange reasons, is the gui updater. > > Do you see anything wrong with the description presented above? Please say > so, > because I can't figure it out! > > > Regards, > Matteo > > -- > http://www.matteolandi.net
I forgot the link to the application: https://bitbucket.org/iamFIREcracker/logfilter Matteo -- http://www.matteolandi.net/ _______________________________________________ Tkinter-discuss mailing list Tkinter-discuss@python.org http://mail.python.org/mailman/listinfo/tkinter-discuss
