Isn't that what DArrays are for, though? Does Julia provide a mechanism for
mutual exclusion/marking critical sections? I'm imagining something like:
shared_result = SharedArray(Int64, (2,), init = S -> S[localindexes(S)] = 0
)
@parallel for i=1:3
lock shared_result
shared_result[:] += [i, i]
end
end
On Monday, July 20, 2015 at 6:59:03 PM UTC-7, Tim Holy wrote:
>
> 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]
>
>
