MATLAB: Is it possible to conditionally switch between parallel and non parallel for loops

conditionalconditionally parallelparfor

I would like to be able to set a flag as the input to a function that changes the code from executing a for loop to a parfor loop and vice versa.

It would be handy sometimes so I can debug the contents of the loop (in a standard for) without actually changing the function around it.

Best Answer

You can do this by setting the optional "number of workers" argument to 0. For example

runInSerial = <...>;
if runInSerial
  parforArg = 0;
else
  parforArg = Inf;
end
parfor (idx = 1:N, parforArg)
  ...
end

Related Solutions

MATLAB: How to degug inside a parfor loop

You can debug code called from the body of a parfor loop if no parallel pool is open, but unfortunately you cannot debug the body of a parfor loop itself. You can force the parfor loop to run in the desktop MATLAB by appending the optional "number of workers" argument, like so:

parfor (idx = 1:10, 0)
  out(idx) = myFcn(idx);
end

With that code, you can set breakpoints inside myFcn.

MATLAB: Using Parfor in Ga

Nested parfor loops will be treated as a parfor calling a for-loop. For example:

parfor idx = 1:N
    myfcn(idx)
end
function myfcn(idx)
parfor jdx = 1:idx
end
end

The jdx parfor will be treated as a for-loop. The one exception is if the neste parfor is embedded within the outer.

parfor idx = 1:N
    parfor jdx = 1:N
    end
end

In this case, jdx will cause an error.

Best Answer

Related Solutions

MATLAB: How to degug inside a parfor loop

MATLAB: Using Parfor in Ga

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