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Why does my MATLAB becomes unresponsive (hangs) when I issue MATLABPOOL OPEN in Parallel Computing Toolbox 4.3 (R2010a)?

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Murugavel Sivagnanam
Murugavel Sivagnanam on 12 Jan 2011
When I issue the MATLABPOOL OPEN command MATLAB just hangs. I can use CTRL-C to interrupt the command and return to the command prompt. Similarly, when I try to validate my local parallel configuration the validation hangs at MATLABPOOL OPEN. There is nothing special about my configuration, except that inside my startup.m file I ask the user to specify some configuration options.

Answers (1)

Murugavel Sivagnanam
Murugavel Sivagnanam on 12 Jan 2011
This behavior is expected and is due to how MATLABPOOL OPEN command works. When MATLABPOOL OPEN is issued, the command starts a specified number of headless MATLAB workers. Each of these workers executes the startup.m file, and awaits user input. Because the headless workers do not have desktops, user is not aware that they are requesting input and thus it appears that the MATLABPOOL OPEN hangs the system.
As a workaround either remove the user input commands from the startup.m file, or choose a default setting that is executed when the script is executed on a headless node, using the JAVACHK('DESKTOP') command as shown in the example below:
if(isempty(javachk('desktop')))
disp('Interactive mode');
else
disp('head less mode');
end

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