Question

I have thousands of lines of MATLAB code that realizes different computationally intensive operations on fMRI brain-imaging data. Many of the operations could be run in multiple parallel threads, but the problem is that all fprintf and disp output of different threads/workers is printed on the same window.

I have written a custom multithreading code that forks out new MATLAB instances using unix command in Linux environment. So, I first write out .m-files PreprocessSubj1.m, PreprocessSubj2.m, PreprocessSubj3.m and PreprocessSubj4.m, each of these contains the same computations but for different subjects. These 4 MATLAB functions are completely independent of each other.

CellArrayOfFunctions = { 'PreprocessSubj1', 'PreprocessSubj2', ...
'PreprocessSubj3', 'PreprocessSubj4' };

CellArrayOfFunctions_i = 1;

while (CellArrayOfFunctions_i <= size(CellArrayOfFunctions, 2))
    FunctionToBeRun = CellArrayOfFunctions{CellArrayOfFunctions_i};
    unix([ 'matlab -desktop -r ', FunctionToBeRun, ' &' ]);
    CellArrayOfFunctions_i = CellArrayOfFunctions_i + 1;
end

I think using unix for forking MATLAB threads is quite a kludge. I would like to implement this code using parfor, for better maintainability and smaller memory usage. But is there any way how I could redirect fprintf (and disp) output of different threads/workers to separate windows?

Thank you 🙂

Answer 1

You probably want to write to /dev/pts/#, where # will denote the window. You can do this with:

output1 = fopen('/dev/pts/0', 'w');
output2 = fopen('/dev/pts/1', 'w');
fwrite(output1, 'Data to window 1');
fwrite(output2, 'Data to window 2');

You will need to determine which numbers to put after /dev/pts/ somehow though. Each time you open a new terminal, a new file appears there corresponding to that terminal, so you can check what terminals are available with !ls /dev/pts.