error using parallel.p​ool.consta​nt/get value

2020 10 2
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更新时间：2020 10 8
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0 个投票

  1. 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
Walter Roberson 2020-10-5
Is there a particular reason to ask for 8 cores but use cycles of 5 futures?
Muna Tageldin
Muna Tageldin 2020-10-8
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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 采纳的回答

Walter Roberson
Walter Roberson 2020-10-2

0 个投票

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

6 个评论
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Muna Tageldin
Muna Tageldin 2020-10-2
why would I pass the indices to the function instead of the data themselves? . I will try it. Thanks
Walter Roberson
Walter Roberson 2020-10-2
parpool constant sends the entire variable to the workers. The data is already on the workers, so you do not need to send the data again, just the index to use.
Muna Tageldin
Muna Tageldin 2020-10-4
ok thanks actually it worked but I have changed 2 to 3 since I am having 3 ouputs
f1(i) = parfeval(poolobj,@cores_random, 2, i, 1);
Muna Tageldin
Muna Tageldin 2020-10-4
Also, when I run the matlab code, I got an error:
"The parallel pool has shutwodn" and when I examined the log file I get the following:
f3= 1*2 FevalFuture array
ID State FinishedDateTime function Error
8 finished(unread) @cores_random Error
Not really sure where this error come from
Walter Roberson
Walter Roberson 2020-10-4
Are you getting any succesful outputs ?

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