Parfor or parfeval, what is better?

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Andrea Stevanato
Andrea Stevanato 2018-7-14
回答： Edric Ellis 2018-7-16
if I have some code that could be writed in same way with parfeval o parfor, what i have to use? What is better? Which is more advantageous, faster... e.g:
parfor i = 1:n
result = function(data);
end
or
for i = 1:n
F(i) = parfeval(@function, 1, data);
end
for i = 1:n
[index, value] = fetchNext(F);
end
  2 个评论
Rik
Rik 2018-7-14
I couldn't find any comparisons with a quick search, although I did find that parfeval is (or used to be?) 'plagued by memory a leak'. I checked the release notes for mentions of parfeval, but nothing popped up.
In general I would assume that parfor is a better choice, but that might be a knee jerk reaction because of the feval part of its name.
Edric Ellis
Edric Ellis 2018-7-16
The memory leak described in that bug report is shown as being fixed in R2015a.

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采纳的回答

Edric Ellis
Edric Ellis 2018-7-16
At least some of the trade-offs are:
  • parfor is generally easier to use, and the code probably looks much more like your serial code
  • parfor loops can be used by people who don't have Parallel Computing Toolbox
  • parfor loops perform a degree of load-balancing to try and minimise overheads
  • parfeval gives you complete control over how the work is chunked up for the workers
  • parfeval is asynchronous, and lets the MATLAB client get on with other stuff while the workers are busy (e.g. updating plots or other visualisations)

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