README.md

SyncBarriers

SyncBarriers.jl provides various implementations of barrier for shared memory synchronization and reductions in concurrent Julia programs. It respects the cooperative multitasking nature of Julia's task system while allowing the programmers to express and leverage the structure of the parallelism in their program.

See the documentation for more information.

Note: Appropriate insertion of barriers for correct and efficient parallel program is rather hard. For casual programming, it is recommended to ues higher-level data-parallel approaches.

A toy example

julia> using SyncBarriers

julia> xs = zeros(Bool, 20);

julia> xs[end÷2] = true;

julia> barrier = Barrier(length(xs) - 2);

julia> @sync for i in 2:length(xs)-1
           b = barrier[i-1]
           Threads.@spawn begin
               if i == 2
                   println()
                   join(stdout, (" █"[x + 1] for x in xs))
                   println()
               end
               for _ in 1:8
                   cycle!(b)               # wait for print
                   l, c, r = xs[i-1:i+1]   # (loading)
                   cycle!(b)               # wait for load
                   xs[i] = l ⊻ (c | r)     # (storing)
                   cycle!(b)               # wait for store
                   if i == 2
                       join(stdout, (" █"[x + 1] for x in xs))
                       println()
                   end
               end
           end
       end

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See the benchmarks for examples with actual performance considerations.