Error using fetchnext and parallel.pool.constant

I have this code, that I run on a remote cluster. I followed this tutorial on using parallel.pool.constant with parfeval. I run into a problem in fetchnext. The error is "Error using parallel.FevalFuture/fetchNext . The function evaluation completed with an error. Caused by no workers abailable for FevalQueue excution". I followed this as well. An error occured during parallel.pool.constant . I am not sure how to proceed.

poolobj=parpool('my_cluster',8);
[up, op]=ndgri(1e-3:1e-2:1,1e-3:1e-2:1);
up=reshape(up, [1,size(up,1)*size(up,2)]);
up=reshape(up, [1,size(up,1)*size(up,2)]);
z=rand(5,5e3);
addAttachedFiles('<path to my function/cores_random.m');%%to add the function files to workers on the pool
C1=parallel.pool.Constant(z);%%use parallel.pool.Constant to copy these variables into workers
U2=parallel.pool.Constant(up);
O2=parallel.pool.Constant(op);
for i=1:size(up,2)
    f1(i) = parfeval(poolobj,@cores_random, 3, i, 1,C1,U2,O2); %%line 11
    f2(i) = parfeval(poolobj,@cores_random, 3, i, 2,C1,U2,O2);
    f3(i) = parfeval(poolobj,@cores_random, 3, i, 3,C1,U2,O2);
    f4(i) = parfeval(poolobj,@cores_random, 3, i, 4,C1,U2,O2);
    f5(i) = parfeval(poolobj,@cores_random, 3, i, 5,C1,U2,O2);
end 
wait(f1);
wait(f2);
wait(f3);
wait(f4);
wait(f5);
for j=1:size(up,2):-1:1
    [idx1,u1,o1,ep1]=fetchNext(f1);
    [idx2,u2,o2,ep2]=fetchNext(f2);
    [idx3,u3,o3,ep3]=fetchNext(f3);
     [idx4,u4,o4,ep4]=fetchNext(f4);
     [idx5,u5,o5,ep5]=fetchNext(f5);
end
function [uu,oo,ep] = cores_random(i, zidx,C1,U2,O2)
    up = U2.Value(i)
    op = O2.Value(i);
    z = C1.Value(zidx,:);
    
    %%doing some calculations here
    %%z is of size 1*1e3 
    %%up is scalar op is scalar 
end

[Raymond Norris]

Hi Muna,

Just to clarify one thing: your parfeval calls specify you are returning 2 output arguments from cores_random. However, when you fetch the futures, you return 3 (plus the idx). Can you try calling with 3, as such:

f1(i) = parfeval(poolobj,@cores_random, 3, i, 1,C1,U2,O2);

And see if that first resolves anything?

Thanks,

Raymond

[Muna Tageldin]

yes sorry I made a typo. Actually its 3 in the real code. This is a simplified code.

[Muna Tageldin]

so basically, I should write 4 for outputs ? ( three from the function and one index)