Speed up: Parfor loop vs Vectorization

I'm trying to speed up my code, which is bottlenecking here:
tic
FD = zeros(28, Rotations);
parfor i = 1:Rotations
CodePR = rotate (CodeP, i*(Rotations - 1)*angle, [0 0]);
for j = 1:28
FD(j, i) = (area(intersect(intersect(CodePR, MaskP), WholeVD(j))))/(AreaFD(j));
end
end
A = FD;
toc
I came up with that solution:
tic
FD = zeros(28, Rotations);
WholeVD = transpose(WholeVD);
AreaFD = transpose(AreaFD);
parfor i = 1:Rotations
CodePR = rotate (CodeP, i*(Rotations - 1)*angle, [0 0]);
FD(:,i) = area(intersect(intersect(CodePR, MaskP), WholeVD))./AreaFD;
end
B = FD;
toc
which is like 20 times (for my rig at least). The bad thing is that with actual dataset it consumes too much RAM (and eventually crashes matlab) so I can't evaluate that. Getting rid or PARFOR helps with memory problem but effectivly slower (by amount of CPU cores). Is there any walk arounds to reduce memory usage so I could utilize more threads?
The whole code is in attachment (fold everything, described part is not foldable). Thanks.

 采纳的回答

R2020a introduced Threads based parallel pool. This may reduce the memory issues.
You can create a threads based parpool before using parfor.
pool = parpool("threads");

3 个评论

Thanks, seems a legit way to improve memory usage. I have to update to 2020a to check this, tho.
Running your code (which I'm asusming isn't the entire number of iteration) ran under "threads", so I think that's a good approach to potentially solving your parfor memory issues. Both "local" and "threads" ran in the same amount of time.
Oh, that's nice of you, Raymond, thanks.

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