Too much free time...

[John W. Eaton]

On 24-Mar-2007, Daniel J Sebald wrote:

| In trying to investigate why my system takes so long to draw, I placed a 
pause() 
| inside of __go_draw_axes__.m.  I've tried pause in a simple test M file and 
it 
| seemed to work fine, but inside __go_draw_axes__.m according to the attached 
| patch Octave goes into an infinite loop of redrawing the figure at a rapid 
rate. 
|   After about twenty seconds I get:
| 
| error: max_recursion_limit exceeded
| 
| Any explanation for this?  I wonder because this might be a clue to the 
source 
| of delay in my system.  That is, without the "pause()" perhaps (just 
guessing) 
| there is this loop that goes to the recursion limit, stops then draws the 
plot. 
|   With the pause(), the loop "comes back to the command line" and draws every 
| time, hence it takes longer to reach the recursion limit.
| 
| I can't see any files in octave subdirectory left over from the plotting 
| debugging that might cause this.

As you found, pause calls drawnow.  I think the following patch would
avoid the problem, but I'm not sure it is really necessary.

jwe

2007-03-26  John W. Eaton  <address@hidden>

        * plot/drawnow.m: Exit early if call is recursive.


Index: scripts/plot/drawnow.m
===================================================================
RCS file: /cvs/octave/scripts/plot/drawnow.m,v
retrieving revision 1.14
diff -u -u -w -r1.14 drawnow.m
--- scripts/plot/drawnow.m      24 Mar 2007 17:54:23 -0000      1.14
+++ scripts/plot/drawnow.m      26 Mar 2007 14:25:50 -0000
@@ -26,6 +26,15 @@
 
 function drawnow (term, file)
 
+  persistent drawnow_executing = 0;
+
+  unwind_protect
+
+    ## If this is a recursive call, do nothing.
+    if (++drawnow_executing > 1)
+      return;
+    endif
+
   if (nargin == 2)
     h = get (0, "currentfigure");
     if (h)
@@ -60,15 +69,19 @@
          endif
          set (h, "__modified__", false);
        endif
-       __request_drawnow__ (false);
       endif
     endfor
   else
     print_usage ();
   endif
 
+  unwind_protect_cleanup
+
+    drawnow_executing--;
   __request_drawnow__ (false);
 
+  end_unwind_protect
+
 endfunction
 
 function plot_stream = open_gnuplot_stream (h, term, file)