Merge 295a6c3 into ac0ec81

docs/src/manual/async.md

@@ -1,11 +1,13 @@
 # Asynchronous UI
 
-Here is an example of an asynchronous update of the user interface. Since
-Julia has currently no possibility of multithreading we use a second process
-to offload the work. The example is just a proof of principle.
+It is possible to perform background computation without interfering with user interface
+responsiveness either using separate processes or using multithreading. Use of a separate
+process includes slightly more overhead but is also more robust.
+
+Here is an example using a separate process to offload the work.
 
 ```julia
-using Gtk
+using Gtk, Distributed
 
 btn = GtkButton("Start")
 sp = GtkSpinner()
@@ -19,23 +21,53 @@ grid[1:2,2] = ent
 id = addprocs(1)[1]
 
 signal_connect(btn, "clicked") do widget
- start(sp)
- @Gtk.sigatom begin
-   @async begin
-    s = @fetchfrom id begin
-      sleep(4)
-      return "I am back"
-    end
-    @Gtk.sigatom begin
-      stop(sp)
-      set_gtk_property!(ent,:text,s)
+    start(sp)
+    @async begin
+        counter = @fetchfrom id begin
+            stop_time = time() + 3
+            counter = 0
+            while time() < stop_time
+                counter += 1
+            end
+            counter
+        end
+        stop(sp)
+        set_gtk_property!(ent, :text, "I counted to $counter in a separate process!")
     end
-  end
- end
 end
 
-win = GtkWindow(grid, "Progress Bar", 200, 200)
+win = GtkWindow(grid, "Distributed", 200, 200)
 showall(win)
 ```
 
+And here is an example using threads. Notice that this example will freeze the UI during
+computation unless Julia is run with two or more threads (`julia -t2` on the command line).
+
+```julia
+using Gtk
 
+btn = GtkButton("Start")
+sp = GtkSpinner()
+ent = GtkEntry()
+
+grid = GtkGrid()
+grid[1,1] = btn
+grid[2,1] = sp
+grid[1:2,2] = ent
+
+signal_connect(btn, "clicked") do widget
+    start(sp)
+    Threads.@spawn begin
+        stop_time = time() + 3
+        counter = 0
+        while time() < stop_time
+            counter += 1
+        end
+        stop(sp)
+        set_gtk_property!(ent, :text, "I counted to $counter in a thread!")
+    end
+end
+
+win = GtkWindow(grid, "Threads", 200, 200)
+showall(win)
+```