parfor loop stalls where a for loop does fine, no error

Hi all,

I have a parfor loop that calls a function. Parameters are passed to the function. Two of the parameters are omega and delta, if either one of these is close to zero, the parfor loop stalls out and freezes. But, if it is for loop it works fine.

Doesn't make any sense to me. There is clearly more code to it....but is there any red flag that would make sense when parameters are close to zero, it works fine in a for, but stalls in a parfor?

Here is the code

parfor j = 1:numberOfICs

      str = sprintf('trial: %d/%d',j,numberOfICs); disp(str)
      IC = ICmatrix(j,:); % Choose initial position

          % Pass to RK4
          [all_Y_pos(:,:,j),all_aveLE(:,j),savedLETimeTemp] = ODE_approx_RK4(j,epsilon,eta,delta,omega,A,xi...
              ,IC(1),IC(2),t0,dt,tf,pert,threshold,exposh,orbitSaved,save_aveV...
              ,save_aveLE, orbitSaveStart);

if j == 1
    savedLETime(j,:) = savedLETimeTemp;
end

end

Will

Answer 1

[Edric Ellis]

The main difference when running PARFOR are that different iterations of the loop are executed by different processes. So, if your function has persistent state for example, that is not shared across all the workers. Other than that, there are no expected differences in the way functions are evaluated on the workers.