Usually the whole point of a SharedArray is that workers only update the piece they "own." You can make it work different if you implement locking, but lock contention can be a bottleneck.
--Tim On Monday, July 20, 2015 04:29:04 PM John Brock wrote: > I'm seeing inconsistent results when multiple workers write values to a > SharedArray at the same time, presumably because += isn't atomic. Is this > intended behavior, and is there a workaround? Behavior is reproducible in > 0.3.8-pre+22 and 0.3.9. > > Sample code: > > function doStuff() > result_shared = SharedArray(Int64, (2,), init = S -> S[localindexes(S)] = > 0) > @sync for i=1:3 > @spawn begin > result_shared[:] += [i, i] > end > end > return sdata(result_shared) > end > > > julia -p 3 > > julia> dump(doStuff()) > Array(Int64,(2,)) [3,3] > > julia> dump(doStuff()) > Array(Int64,(2,)) [6,6]
