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How to programmatically determine if in headless mode..?

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I'm working on an issue with the Parallel Computing Toolbox (PCT)..
As each MATLAB.exe worker thread process is initialized, startup.m is executed. All worker threads are "headless" (no output window). Certain graphics-related function calls that are fine-- when launched within the full MATLAB app with its output capability-- can cause problems in the headless context.
I have a graphics-related function that's very convenient to have in the full MATLAB app's startup.m, but mustn't execute in the PCT worker thread context. Is there a function call I can insert into startup.m to determine if its MATLAB.exe process is running in headless mode? I would like to use as follows:
% Is there an output window associated with this MATLAB.exe process?
if ~isInHeadlessMode()
% YES : render graphics window
Any help appreciated, Thanks, Brad

Accepted Answer

Edric Ellis
Edric Ellis on 16 Jan 2012
One option is to check:
java.lang.System.getProperty( 'java.awt.headless' )
Edric Ellis
Edric Ellis on 18 Jan 2012
FWIW, "usejava('desktop')" is fine for most purposes, but it's not quite the same thing - for example, if you run MATLAB in "-nodesktop" mode (as I do most of the time), then it will give you the wrong answer - you can still produce graphics in "-nodesktop" mode. Oh, and I'm a MathWorker too ;)
Bradley Stiritz
Bradley Stiritz on 23 Jan 2012
Thanks for the deeper understanding, very appreciated. Sorry to have judged your suggestion too superficially. Accepting now..

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More Answers (1)

Bradley Stiritz
Bradley Stiritz on 17 Jan 2012
Per Nathan Lloyd in Mathworks PCT support, the native MATLAB usejava() function can be used to determine whether the executing MATLAB.exe instance is in 'desktop' or 'headless' mode..
"[The following] code checks to see if a desktop exists before executing the sensitive block of code. For any worker, the desktop will never exist, so the code will be jumped over and the workers will persist; while the client MATLAB will execute the 'startup.m' file without issues."
if usejava('desktop')
% YES : render graphics window


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