Performance: accessing handle properties

13 Responses

1. 
   oro77 November 20, 2013 at 18:50 Reply

   Thank you very much, I did not know about the handle() tip. It will increase the performance of my GUI.
   I have a question concerning the java Button. How do you put it in the figure ? There is no parent member in the handle. How to change the size of the button using the java button ?

   jb = javax.swing.JButton;

   jb = javax.swing.JButton;

• 
  Yair Altman November 21, 2013 at 02:12 Reply

  @oro77 – http://undocumentedmatlab.com/blog/javacomponent/

2. 
   Lucius Domitius Ahenobarbus November 21, 2013 at 01:05 Reply

   Thanks a lot! there is another thing, which makes this even more interesting for me: With the dot-notation, one can use the autocomplete-functionality 🙂 what makes coding a bit faster for me in many cases.

3. 
   Dan November 21, 2013 at 11:33 Reply

   Yair, I noticed something interesting. It appears that you pay the time penalty the first time you access any property within a given scope. Try this: create a handle object and pass it into a function (you can pass it in within a cell array, at a minimum). The first time you access any property within the function you pay the time penalty, but all subsequent calls are fast. BUT: you pay that penalty every time you call the function… Try profiling this:

   function SpeedTests fig = figure; for i = 1:4 hObj(i) = subplot(2,2,i); handleObj{i} = handle(hObj(i)); handleObjs2(i) = handle(hObj(i)); end for itest = 1:1000 subfun(handleObj,hObj,handleObjs2); end return end   function subfun(handleObj,hObj,handleObjs2) for i = 1:4 pos0 = handleObjs2(i).Position; pos1 = handleObj{i}.Position; pos2 = get(hObj(i),'Position'); pos3 = handleObj{i}.Position; XLIMS = handleObj{i}.XLim; end end

   function SpeedTests fig = figure; for i = 1:4 hObj(i) = subplot(2,2,i); handleObj{i} = handle(hObj(i)); handleObjs2(i) = handle(hObj(i)); end for itest = 1:1000 subfun(handleObj,hObj,handleObjs2); end return end function subfun(handleObj,hObj,handleObjs2) for i = 1:4 pos0 = handleObjs2(i).Position; pos1 = handleObj{i}.Position; pos2 = get(hObj(i),'Position'); pos3 = handleObj{i}.Position; XLIMS = handleObj{i}.XLim; end end

   Any thoughts?

4. 
   Malcolm Lidierth November 21, 2013 at 19:16 Reply

   While this may not be a real application test case note that using GShell (which uses a Groovy shell) from Waterloo in MATLAB gives:

   tic; GShell.setVariable('button', jhb); GShell.eval('for (def idx=0; idx < 10000; idx++) { button.setText("testing")'); toc;

   tic; GShell.setVariable('button', jhb); GShell.eval('for (def idx=0; idx < 10000; idx++) { button.setText("testing")'); toc;

   Elapsed time is 0.019272 seconds.

   A ~10x improvement on the best of the above on my machine (after GShell warm up).

   Further info at http://waterloo.sourceforge.net/groovy/GShell.html

   Horses-for-courses: expect JVM languages to outperform MATLAB on JVM operations ; and MATLAB to (substantially) outperform the JVM when working with natives.

• 
  Malcolm Lidierth November 22, 2013 at 05:40 Reply

  PPS. Adding the code to a script file and using run allows the compiled code to be used each time. Then we see

  >> GShell.load('/Users/ML/blogtest.groovy') % Load and compile once ans = 1   >> tic;GShell.run();toc Elapsed time is 0.060009 seconds. >> tic;GShell.run();toc Elapsed time is 0.019712 seconds. >> tic;GShell.run();toc Elapsed time is 0.003378 seconds. >> tic;GShell.run();toc Elapsed time is 0.003129 seconds. >> tic;GShell.run();toc Elapsed time is 0.003126 seconds. >> tic;GShell.run();toc Elapsed time is 0.003531 seconds. >> tic;GShell.run();toc Elapsed time is 0.003365 seconds. >> tic;GShell.run();toc Elapsed time is 0.003394 seconds.

  >> GShell.load('/Users/ML/blogtest.groovy') % Load and compile once ans = 1 >> tic;GShell.run();toc Elapsed time is 0.060009 seconds. >> tic;GShell.run();toc Elapsed time is 0.019712 seconds. >> tic;GShell.run();toc Elapsed time is 0.003378 seconds. >> tic;GShell.run();toc Elapsed time is 0.003129 seconds. >> tic;GShell.run();toc Elapsed time is 0.003126 seconds. >> tic;GShell.run();toc Elapsed time is 0.003531 seconds. >> tic;GShell.run();toc Elapsed time is 0.003365 seconds. >> tic;GShell.run();toc Elapsed time is 0.003394 seconds.

  The performance improvements are down to HotSpot I guess.

  As this is a JButton, the code should really be run on the EDT.
  Using GShell.runEDT – which uses invokeAndWait – performance returns to ~0.03s.
  Using GShell.runLater – which uses invokeLater – performance improves another 10x (the MATLAB thread is not blocked as control returns as soon as the code is posted to the EDT).

  invokeAndWait cannot be called if already on the EDT (e.g. if javaObjectEDT has been used on the button). GShell solves that with GShell.runQuery which uses GShell.runEDT if it can, and GShell.runLater otherwise.

  Note that GShell is independent of the rest of the Waterloo code – in fact it’s wrapped in an RStudio project folder and can be used from MATLAB, R, Python, SciLab, JRuby etc. It can be used to run any Java/Groovy code and control threading e.g. to create a background SwingWorker thread or work on the JavaFX platform thread.

  GShell contains little or no novel code – it’s just giving easy access to a Groovy shell instance from other scripting environments.

5. 
   Xiaohu November 22, 2013 at 16:18 Reply

   Nice tip (as always)!
   It is however surprising to me that using dot notation is actually faster. As you probably know, method invocation using function notation is typically faster in Matlab, see:
   http://blogs.mathworks.com/loren/2012/03/26/considering-performance-in-object-oriented-matlab-code/#11
   http://stackoverflow.com/questions/1693429/is-matlab-oop-slow-or-am-i-doing-something-wrong
   Any insight on this?

• 
  Yair Altman November 23, 2013 at 08:45 Reply

  @Xiaohu – I do not understand why this is, but it appears to be consistent. If anyone has an explanation, I’d be happy to learn.

• 
  Andrew November 26, 2013 at 14:47 Reply

  This is not really the case of two different ways of invoking a method. We’re setting or getting a property. Properties can either be directly specified/obtained using set/get methods (allowing for things like validation) or via “dot” notation. The latter is much simpler and probably why this is faster. Indeed, trying to get nonexistent properties using the various methods shows that they return different error messages. When setting nonexistent properties, the set method returns an error, but the “dot” notation methods obviously do not. This additional overhead of validation may be what is slowing down get/set over repeated calls.

• 
  Yair Altman November 26, 2013 at 15:03 Reply

  @Andrew – you may indeed be correct, but when we use a.B=c notation, the setB(a,c) function is still getting invoked if you declare it, which seems to indicate that the opposite is the case. But then it would not explain why a.B would be faster than calling setB() directly. I don’t have a good answer to explain the apparent contradiction.

6. 
   Bjorn November 26, 2013 at 06:10 Reply

   This seems to be a good approach when resetting the same handle over and over again. Not quite the case when updating many different graphical objects.

   %Setup many axes in one figure tmp = figure; Fig = zeros(1,10000); for idx=1:10000 Fig(idx) = axes('parent',tmp); end   % Using standard set() function tic, for idx=1:10000, set(Fig(idx),'tag','testing'); end, toc % Elapsed time is 0.163880 seconds   % Using the HG handle() wrapper within the loop tic, for idx=1:10000, hFig = handle(Fig(idx)); set(hFig,'tag','testing'); end, toc % Elapsed time is 0.375456 seconds   % Using the HG handle() wrapper outside of the loop tic hFig = handle(Fig); for idx=1:10000, set(hFig(idx),'tag','testing'); end, toc % Elapsed time is 0.241068 seconds   % Using dot notation with handle() wrapper within the loop tic for idx=1:10000, hFig = handle(Fig(idx)); hFig.tag = 'testing'; end toc % Elapsed time is 0.290306 seconds   % Using dot notation with handle() wrapper outside of the loop tic hFig = handle(Fig); for idx=1:10000, hFig(idx).tag = 'testing'; end toc % Elapsed time is 3.585026 seconds

   %Setup many axes in one figure tmp = figure; Fig = zeros(1,10000); for idx=1:10000 Fig(idx) = axes('parent',tmp); end % Using standard set() function tic, for idx=1:10000, set(Fig(idx),'tag','testing'); end, toc % Elapsed time is 0.163880 seconds % Using the HG handle() wrapper within the loop tic, for idx=1:10000, hFig = handle(Fig(idx)); set(hFig,'tag','testing'); end, toc % Elapsed time is 0.375456 seconds % Using the HG handle() wrapper outside of the loop tic hFig = handle(Fig); for idx=1:10000, set(hFig(idx),'tag','testing'); end, toc % Elapsed time is 0.241068 seconds % Using dot notation with handle() wrapper within the loop tic for idx=1:10000, hFig = handle(Fig(idx)); hFig.tag = 'testing'; end toc % Elapsed time is 0.290306 seconds % Using dot notation with handle() wrapper outside of the loop tic hFig = handle(Fig); for idx=1:10000, hFig(idx).tag = 'testing'; end toc % Elapsed time is 3.585026 seconds

• 
  Andrew November 26, 2013 at 14:21 Reply

  Interesting

• 
  Andrew November 26, 2013 at 14:29 Reply

  … the blog apparently ate my n-dash and the rest of my post. In any case, similarly, I wonder which method would be fastest for getting/setting multiple properties of the same handle when using cell arrays, i.e., as in this StackOverflow/Matlab answer of mine.

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