[DRE-maint] [Bug 514899] Re: Multithreaded Gtk applications using Ruby bindings freeze

[Jean-Baptiste Lallement]

** Description changed:

  Binary package hint: libgtk2-ruby
  
  In Ubuntu 9.10 with the version of libgtk2-ruby from the repositories
  (0.19.0), new threads cause the Gtk main loop to freeze. As an example,
  the following code will never produce any output:
- 
  
  ===== Impact =====
  I don't know which program available directly within Ubuntu is written in Ruby-GTK+, but those which do and which are using the Ruby Thread class are broken, and of course developing such a program is broken too.
  
  The fix is available in ruby-gnome2 since version 0.19.2 and was
  introduced through SVN revisions 3692[1] and 3694[2]. Both are within
  the attachment "ruby-gnome2-gtk-thread-patch.debdiff" in comment #1.
  
  [1] http://ruby-gnome2.svn.sourceforge.net/viewvc/ruby-gnome2?view=rev&revision=3692
  [2] http://ruby-gnome2.svn.sourceforge.net/viewvc/ruby-gnome2?view=rev&revision=3694
  
+ TEST CASE:
+  require 'gtk2'
  
- TEST CASE:
-  require 'gtk2'
+  Thread.new do
+    sleep 1 # Look busy
+    exit    # Finished, exit
+  end
  
-  Thread.new do
-    sleep 1 # Look busy
-    exit    # Finished, exit
-  end
- 
-  # Main loop
-  loop do
-    # Process all currently pending events
-    Gtk.main_iteration while Gtk.events_pending?
-    print '.'
-  end
+  # Main loop
+  loop do
+    # Process all currently pending events
+    Gtk.main_iteration while Gtk.events_pending?
+    print '.'
+  end
  
  However, when the latest version of the bindings is installed (0.19.3)
  the program works as expected, filling the screen with dots.
  
  TEST CASE 2:
  Here is another example for reproducing this bug:
  
  require "gtk2"
  include Gtk, GLib
  # Create widgets
  window = Window.new
  vbox = VBox.new(false, 2)
  button = Button.new("Run Thread")
  progress = ProgressBar.new
  # Pack widgets
  window.add(vbox)
  vbox.add(button)
  vbox.add(progress)
  # Set default window size
  window.default_width = 120
  window.default_height = 50
  window.show_all
  # Connect signals
  button.signal_connect("clicked") do
-         Thread.new do
-                 puts "Thread started!"
-                 progress.pulse
-         end
+         Thread.new do
+                 puts "Thread started!"
+                 progress.pulse
+         end
  end
  window.signal_connect("destroy") { main_quit }
  # Show all and run
  main # start the GTK+ main loop
  
  The test program shows a window with a button and a progress bar.
  Clicking the button will execute a Ruby Thread object, and the GUI
  visual elements/the GTK+ main loop will remain freezed.
  
- REGRESSION:
- The only package that depends on ruby-gnome2 in karmic is alien-arena-browser, which is far from being a critical application. The impact of a potential regression would be very limited.
  
- The example in the bug description is supposed to print dots, and
- instead it doesn't.
+ The example in the bug description is supposed to print dots, and instead it doesn't.
  
  This problem is also reported at:
  http://sourceforge.net/mailarchive/forum.php?thread_name=dc3bf8581001120746kb5da118udd0a74439cc4dcd9%40mail.gmail.com&forum_name=ruby-gnome2-devel-en

-- 
Multithreaded Gtk applications using Ruby bindings freeze
https://bugs.launchpad.net/bugs/514899
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Status in “ruby-gnome2” package in Ubuntu: Fix Released
Status in “ruby-gnome2” source package in Karmic: Fix Committed

Bug description:
Binary package hint: libgtk2-ruby

In Ubuntu 9.10 with the version of libgtk2-ruby from the repositories (0.19.0), new threads cause the Gtk main loop to freeze. As an example, the following code will never produce any output:

===== Impact =====
I don't know which program available directly within Ubuntu is written in Ruby-GTK+, but those which do and which are using the Ruby Thread class are broken, and of course developing such a program is broken too.

The fix is available in ruby-gnome2 since version 0.19.2 and was introduced through SVN revisions 3692[1] and 3694[2]. Both are within the attachment "ruby-gnome2-gtk-thread-patch.debdiff" in comment #1.

[1] http://ruby-gnome2.svn.sourceforge.net/viewvc/ruby-gnome2?view=rev&revision=3692
[2] http://ruby-gnome2.svn.sourceforge.net/viewvc/ruby-gnome2?view=rev&revision=3694

TEST CASE:
 require 'gtk2'

 Thread.new do
   sleep 1 # Look busy
   exit    # Finished, exit
 end

 # Main loop
 loop do
   # Process all currently pending events
   Gtk.main_iteration while Gtk.events_pending?
   print '.'
 end

However, when the latest version of the bindings is installed (0.19.3) the program works as expected, filling the screen with dots.

TEST CASE 2:
Here is another example for reproducing this bug:

require "gtk2"
include Gtk, GLib
# Create widgets
window = Window.new
vbox = VBox.new(false, 2)
button = Button.new("Run Thread")
progress = ProgressBar.new
# Pack widgets
window.add(vbox)
vbox.add(button)
vbox.add(progress)
# Set default window size
window.default_width = 120
window.default_height = 50
window.show_all
# Connect signals
button.signal_connect("clicked") do
        Thread.new do
                puts "Thread started!"
                progress.pulse
        end
end
window.signal_connect("destroy") { main_quit }
# Show all and run
main # start the GTK+ main loop

The test program shows a window with a button and a progress bar. Clicking the button will execute a Ruby Thread object, and the GUI visual elements/the GTK+ main loop will remain freezed.


The example in the bug description is supposed to print dots, and instead it doesn't.

This problem is also reported at:
http://sourceforge.net/mailarchive/forum.php?thread_name=dc3bf8581001120746kb5da118udd0a74439cc4dcd9%40mail.gmail.com&forum_name=ruby-gnome2-devel-en