Are you doing floating point calculations? Some FP operations aren't associative and therefore may appear different on successive runs of a parallel operation depending on what's summed first:
julia> (0.1 + 0.2) + 0.3 0.6000000000000001 julia> 0.1 + (0.2 + 0.3) 0.6 On Thursday, November 26, 2015 at 11:48:25 AM UTC-8, Eduardo Lenz wrote: > > Hi. > > I came across a very weird behaviour when using a very simple @parallel > loop. The block is quite large and complex, but the idea is the following: > > > A = zeros(some_dimension) > A = convert(SharedArray,A) > @sync @parallel for i=1:some_dimension > > Lots of code, but with no function calls > > A[i] += block_result > > end > > some computation with sdata(A). > > If I use 4 processes, I get one result. With 8 processes, a diferent > result. Without parallel processing, another one. > > I am probably losing something, but I think this is not the intended > behaviour. > > I am using jula 4.11, fedora 23 - 64 bits. > > Thanks for your help. >
