error using parallel.pool.constant/get value

Question

Muna Tageldin 2020-10-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/604042-error-using-parallel-pool-constant-get-value

评论： Muna Tageldin 2020-10-8

so this is my code (not sure about function handle in parfeval). The error I get is on line 11. I dont understand the error

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,U2.value(i),O2.Value(i),C1.Value(1,:)); %%line 11
f2(i)=parfeval(poolobj,@cores_random,3,U2.value(i),O2.Value(i),C1.Value(2,:));
f3(i)=parfeval(poolobj,@cores_random,3,U2.value(i),O2.Value(i),C1.Value(3,:));
f4(i)=parfeval(poolobj,@cores_random,3,U2.value(i),O2.Value(i),C1.Value(4,:));
f5(i)=parfeval(poolobj,@cores_random,3,U2.value(i),O2.Value(i),C1.Value(5,:));
end 
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

I got an error

{Error using paralle.pool.Constant/get.Value The value of a parallel.pool.Constant is only available on the workers. 
Error in main_parallel_norm (line 11) 
f1(i)=parfeval(poolobj,@cores_random,3,U2.value(i),O2.Value(i),C1.Value(1,:));

the function cores_random is as the following:

[uu,oo,ep]=cores_random(up,op,z)
%%doing some calculations here
%%z is of size 1*1e3 
%%up is scalar op is scalar 
end

2 个评论
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Walter Roberson 2020-10-5

Is there a particular reason to ask for 8 cores but use cycles of 5 futures?

Muna Tageldin 2020-10-8

在 MATLAB Online 中打开

yes since the output depends on differnt rows of C1.value

On other words the original function is like this:

for i=1:size(up,2)
[u1(1,i),oo(1,i),ep(1,i)]=cores_random(up(i),op(i),z(1,:))
[u1(2,i),oo(2,i),ep(2,i)]=cores_random(up(i),op(i),z(2,:))
[u1(3,i),oo(3,i),ep(3,i)]=cores_random(up(i),op(i),z(3,:))
end

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Answer 1

Walter Roberson 2020-10-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/604042-error-using-parallel-pool-constant-get-value#answer_504241

在 MATLAB Online 中打开

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, 2, i, 1); %%line 11
    f2(i) = parfeval(poolobj,@cores_random, 2, i, 2);
    f3(i) = parfeval(poolobj,@cores_random, 2, i, 3);
    f4(i) = parfeval(poolobj,@cores_random, 2, i, 4);
    f5(i) = parfeval(poolobj,@cores_random, 2, i, 5);
end 
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)
    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