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Must have valid initData to build channel

Asked by Halil Eyyuboglu on 3 Jul 2019
Latest activity Answered by Halil Eyyuboglu on 5 Jul 2019
I have a parallel Matlab of 56 workers, I get the following error as I increase the upper (end) value of the parfor loop.
"Must have valid initData to build channel"
Can you please help me to solve this problem
Thanks

  1 Comment

This is an internal consistency error and definitely not expected - do you have any reproduction steps that you can post?

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3 Answers

Answer by Halil Eyyuboglu on 4 Jul 2019

Thanks for the reply. I get the error message, "Must have valid initData to build channel" I run the code below
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patd = 'C:\PhaseFluctuations_Data\Paper_data\DataSLmV1L01km_Dmat200';
Psmat = load(patd,'-mat');Psmat = Psmat.Psmaty;Psmat = imag(Psmat);
iatla = 201;nreals = 2000;nreals = 50;%PsL01 = [];
parfor is = 1:nreals
PsL01(:,:,is) = Psmat(iatla*(is -1) + 1:is*iatla,1:iatla);
end
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Notes
1) Error does not occur, if "nreals" = 10, but error occurs when "nreals" is changed to 50 or higher.
2) Psmat is a matrix of 402000 x 200 elements and the loop attempts to rearrange this matrix into 200 x 200 x 2000
3) No error is generated if "for" is used instead of "parfor"

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Answer by Edric Ellis
on 5 Jul 2019
Edited by Edric Ellis
on 5 Jul 2019

I expect this is a misleading error as a consequence of running out of memory on the workers. You're duplicating Psmat and attempting to put a full copy of it on each of your 56 workers. (By restricting nreals, you're limiting the number of workers used).
I doubt this sort of manipulation is a good fit for parfor in any case. You might be better off doing:
permute(reshape(Psmat.', 200, 200, 2000), [2 1 3])
or something similar. Here's my vastly-simplified example:
>> data = [ 1, 2; 3, 4; 11, 12; 13, 14; 101, 102; 103, 104]
data =
1 2
3 4
11 12
13 14
101 102
103 104
>> permute(reshape(data.', 2, 2, 3), [2 1 3])
ans(:,:,1) =
1 2
3 4
ans(:,:,2) =
11 12
13 14
ans(:,:,3) =
101 102
103 104

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Answer by Halil Eyyuboglu on 5 Jul 2019

Thanks, this solves my problem.

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