How can I run 2 tasks in parallel?

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JAI PRAKASH 2018-7-1

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https://ww2.mathworks.cn/matlabcentral/answers/408323-how-can-i-run-2-tasks-in-parallel

评论： JAI PRAKASH 2018-7-2

采纳的回答： OCDER

I have 2 scripts.

Script1.m___________%infinite while loop which constantly modifying a 'fixed length array'

Script2.m___________% again infinite loop which is processing a live video.

Script1 is independent. But script2 requires the fixed length array generated by script1 before starting image processing on each frame.

I can't merge the scripts because time taken by image processing is significant and will modify script1's independency.

Any alternate non-conventional ideas are also welcome.

Thanks

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JAI PRAKASH 2018-7-2

编辑：JAI PRAKASH 2018-7-2

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Thanks for replying.

Can you please guide me, how to modify the scripts.

Scripts are similar to below examples:

Script1

i=1; n=100;
s = zeros(n,1);
while true
  s(n+1) = i;
  s = s(2:end);   %%This is what Script2 is interested in
  pause(0.01)
end

Script2:

while true
steer = s %%currently generated array from Script1
Rest code of image processing
this while loop generally takes 0.10 seconds
end

Walter Roberson 2018-7-2

You should consider using a circular buffer; they are faster than what you are doing now, which involves a lot of memory re-allocations.

https://www.mathworks.com/matlabcentral/fileexchange/52411-circularbuffer

Or a DSP Queue: https://www.mathworks.com/help/dsp/ref/queue.html

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采纳的回答

OCDER 2018-7-2

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https://ww2.mathworks.cn/matlabcentral/answers/408323-how-can-i-run-2-tasks-in-parallel#answer_327156

编辑：OCDER 2018-7-2

在 MATLAB Online 中打开

You could use two timer objects, one for updating your s vector, and another for extracting the s vector and processing the image with it. See example code and modify the functions script1 and script2.

BUT, this isn't truely in parallel... The real solution require some sort of talk between workers and parallel. See this

https://www.mathworks.com/help/distcomp/parallel.pool.pollabledataqueue.html

%createTimer1.m---------------------------------
function Timer1 = createTimer1()
UserData.s = zeros(1, 100);
UserData.i = 1;
UserData.n = 100;
Timer1 = timer;
Timer1.UserData = UserData;
Timer1.Period = 0.01;
Timer1.TasksToExecute = Inf;  %replaces your infinite while loop
Timer1.ExecutionMode = 'fixedSpacing';
Timer1.Timerfcn = @script1;
function script1(Timer1, events)
UserData = get(Timer1, 'UserData');
UserData.s = [UserData.s(2:end) UserData.i];
UserData.i = UserData.i + 1;
set(Timer1, 'UserData', UserData);
%-----------------------------------------------------end of createTimer1.m
%createTimer2.m---------------------------------
function Timer2 = createTimer2(Timer1)
Timer2 = timer;
Timer2.UserData = Timer1;
Timer2.Period = 0.01;
Timer2.TasksToExecute = Inf;
Timer2.ExecutionMode = 'fixedSpacing';
Timer2.Timerfcn = @script2;
function script2(Timer2, events)
UserData = get(get(Timer2, 'UserData'), 'UserData'); %get Timer1's current data
disp(UserData.s); %to show you what's happening
%-----------------------------------------------------end of createTimer2.m

To run these, use the script:

Timer1 = createTimer1();
Timer2 = createTimer2(Timer1);
start(Timer1);
start(Timer2);

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OCDER 2018-7-2

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function Timer1 = createTimer1()
UserData.s = zeros(1, 100);
UserData.i = 1;
UserData.n = 100;
UserData.tic = tic;  %<<<<<<<<<<<<<<<<<<<<<
Timer1 = timer;
Timer1.UserData = UserData;
Timer1.Period = 0.01;
Timer1.TasksToExecute = 100;
Timer1.ExecutionMode = 'fixedRate';
Timer1.Timerfcn = @script1;
function script1(Timer1, events)
UserData = get(Timer1, 'UserData');
UserData.s = [UserData.s(2:end) UserData.i];
UserData.i = UserData.i + 1;
set(Timer1, 'UserData', UserData);
disp(toc(UserData.tic));  %<<<<<<<<<<<<<<<<<<<<<<<