Update cartesian product to provide better perf for parallel execution #4
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This PR changes the way iterators are advanced to achieve up to 3x speedup when using cartesian product with
par
execution policy infor_each
.The main idea is to keep one index that is being advanced (as a canonical induction variable) and the iterators are being computed using mod/div operation from the induction variable.
Note: this approach doesn't work well when executing with
seq
policy particularly when there are more than 2 iterators in cartesian product.