Tasking with GtkAda
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Hello,
We followed the advice given at http://docs.adacore.com/gtkada-docs/gtkada_ug/_build/html/tasking.html but still found that our program would crash after a varying amount of time, at varying places (usually ending somewhere in libpango). All backtraces had in common that recompute_idle_func() was involved. Here is an example backtrace: (sns_main:2426): Pango-CRITICAL **: pango_layout_line_get_extents: assertion 'LINE_IS_VALID (line)' failed Program received signal SIGSEGV, Segmentation fault. 0x00007ffff57b5955 in pango_context_get_font_description () from /lib64/libpango-1.0.so.0 (gdb) bt #0 0x00007ffff57b5955 in pango_context_get_font_description () from /lib64/libpango-1.0.so.0 #1 0x00007ffff57ba4c8 in pango_layout_get_empty_extents_at_index () from /lib64/libpango-1.0.so.0 #2 0x00007ffff57bd175 in pango_layout_line_get_extents () from /lib64/libpango-1.0.so.0 #3 0x00007ffff69d3a66 in gtk_entry_adjust_scroll () from /lib64/libgtk-3.so.0 #4 0x00007ffff69d5190 in recompute_idle_func () from /lib64/libgtk-3.so.0 #5 0x00007ffff65e66b8 in gdk_threads_dispatch () from /lib64/libgdk-3.so.0 #6 0x00007ffff4d34d7a in g_main_context_dispatch () from /lib64/libglib-2.0.so.0 #7 0x00007ffff4d350b8 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0 #8 0x00007ffff4d3538a in g_main_loop_run () from /lib64/libglib-2.0.so.0 #9 0x00007ffff6a4d045 in gtk_main () from /lib64/libgtk-3.so.0 Our program makes GUI widget update calls from Ada tasks. We changed the program so that the Ada tasks put their widget update requests into a protected-object based queue, and in the main program we call Glib.Main.Timeout_Add with a function that reads from this queue and executes the requests. Since that change, our tasking program has been running without crash. Oliver _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada |
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On 17/03/2017 01:41, Oliver Kellogg wrote:
> We changed the program so that the Ada tasks put their widget update > requests into a protected-object based queue, You cannot use a queue because in a large number of cases return values and side effects are needed at the caller's point. The protected object must act rather as a rendezvous with the main task. P.S. It would be nice if GtkAda generated wrappers checked if the caller's task ID is one of the main task and otherwise used a wait-for-timer mechanism. At least they could drop an exception. However, I understand it might be too much work. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada |
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In reply to this post by Oliver Kellogg-3
I don't know if what I have to say is of any importance to you, But I do
have an workig program under Windows using GTKAda and tasking. I have done nothing with the aid of chapter 8 (Tasking with GtkAda). What I have been doing is simply putall GtkAda in one task, in my case the basic task and let all othertasks communicate withthis task. L. Dries -----Oorspronkelijk bericht----- From: Oliver Kellogg Sent: Friday, March 17, 2017 1:41 AM To: [hidden email] Subject: [gtkada] Tasking with GtkAda Hello, We followed the advice given at http://docs.adacore.com/gtkada-docs/gtkada_ug/_build/html/tasking.html but still found that our program would crash after a varying amount of time, at varying places (usually ending somewhere in libpango). All backtraces had in common that recompute_idle_func() was involved. Here is an example backtrace: (sns_main:2426): Pango-CRITICAL **: pango_layout_line_get_extents: assertion 'LINE_IS_VALID (line)' failed Program received signal SIGSEGV, Segmentation fault. 0x00007ffff57b5955 in pango_context_get_font_description () from /lib64/libpango-1.0.so.0 (gdb) bt #0 0x00007ffff57b5955 in pango_context_get_font_description () from /lib64/libpango-1.0.so.0 #1 0x00007ffff57ba4c8 in pango_layout_get_empty_extents_at_index () from /lib64/libpango-1.0.so.0 #2 0x00007ffff57bd175 in pango_layout_line_get_extents () from /lib64/libpango-1.0.so.0 #3 0x00007ffff69d3a66 in gtk_entry_adjust_scroll () from /lib64/libgtk-3.so.0 #4 0x00007ffff69d5190 in recompute_idle_func () from /lib64/libgtk-3.so.0 #5 0x00007ffff65e66b8 in gdk_threads_dispatch () from /lib64/libgdk-3.so.0 #6 0x00007ffff4d34d7a in g_main_context_dispatch () from /lib64/libglib-2.0.so.0 #7 0x00007ffff4d350b8 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0 #8 0x00007ffff4d3538a in g_main_loop_run () from /lib64/libglib-2.0.so.0 #9 0x00007ffff6a4d045 in gtk_main () from /lib64/libgtk-3.so.0 Our program makes GUI widget update calls from Ada tasks. We changed the program so that the Ada tasks put their widget update requests into a protected-object based queue, and in the main program we call Glib.Main.Timeout_Add with a function that reads from this queue and executes the requests. Since that change, our tasking program has been running without crash. Oliver _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada _______________________________________________ gtkada mailing list [hidden email] http://lists.adacore.com/mailman/listinfo/gtkada |
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