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Why the data in the workers cannot be plotted in graph in PCT?

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DhanaLakshmiR
DhanaLakshmiR on 20 Mar 2018
Edited: William Smith on 26 Mar 2018
In parpool i have two workers. I cannot use the output data in the workers for plotting the graph. How it can be accessed?
delete(gcp('nocreate'))
parpool(2)
delete(gcp);
parpool('AttachedFiles',{'parallel1.m','parallel2.m'})
poolobj = gcp('nocreate');
spmd
first_run = true;
for i=1:5
if labindex == 1
if first_run
A_parameters = 1;
disp('hello');
first_run = false;
else
A_parameters = labReceive()
end
A_output = parallel1(A_parameters);
else
B_output = parallel2(1);
labSend(B_output, 1);
end
end
end
parallel1.m code
function[str1]= parallel1(y1)
filename = fullfile(tempdir, 'talkk.dat');
% Memory map the file.
m = memmapfile(filename, 'Writable', true, 'Format','double' );
m.Data(1) = 0;
for i=1
y11=y1;
% Set first byte to zero, indicating a message is not yet ready.
a=[250000.1594+i 26000+i 27000+i];
str=a ;
len = length(str);
if (m.Data(1)==0)
% Update the file via the memory map.
m.Data(2:len+1) = str;
m.Data(1)=len;
disp('sending message')
end
str1=str;
% Wait until the first byte is set back to zero,indicating that a response is available.
while (m.Data(1) ~= 0)
pause(.25);
end
end
parallel2.m code
function[output]= parallel2(y)
yy=y;
k=1
% Respond to SEND using memmapfile class.
disp('ANSWER server is awaiting message');
filename = fullfile(tempdir, 'talkk.dat');
% Memory map the file.
m = memmapfile(filename, 'Writable', true, 'Format', 'double');
m.Data(1) = 0;
for i=1:5
% Wait until the first byte is not zero.
while (m.Data(1) == 0)
pause(.25);
end
if (m.Data(1)~=0)
textdat = double(m.Data(2:1+double(m.Data(1))))';
output=textdat+1;
%Display the message.
disp('Received message from SEND:')
disp(textdat)
% Signal to SEND that the response is ready.
m.Data(1) = 0;
k=k+1;
end
Data=1;
end
I want this textdat in the worker to be plotted for the whole iteration or any other way to plotting is also appreciated.Kindly give answers.Thanks in advance!!

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Answers (2)

Jason Ross
Jason Ross on 20 Mar 2018
Edited: Jason Ross on 20 Mar 2018
You could look at using a DataQueue. There is an example of using one here.

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William Smith
William Smith on 26 Mar 2018
Edited: William Smith on 26 Mar 2018
I have multiple parfor workers plotting 'invisible' graphs then saving to PNG. Seems to work fine.
Pseudocode:
fig = figure('Position', [ 100 100 1000 500 ], 'Visible', 'off' );
ax1 = subplot(1,2,1);
ax2 = subplot(1,2,2);
plot(ax1, ...);
plot(ax2, ...);
print(fig, imageFilename, '-dpng');
close(fig);

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