@only_one block is executed by a single iteration (not a single task)

[CarloLucibello]

From my understanding of the docstring

  @only_one begin ... end

  This can be used inside a @tasks for ... end block to mark a region of code to be executed by only one
  of the parallel tasks (all other tasks skip over this region).

I was expecting

@tasks for i in 1:8
    @set ntasks = 2

    println(i, ": before")
    @only_one begin
        println(i, ": after")
    end
end

to print after 4 times (since a single task has to run 4 iterations of the loop). Instead, I get the output

5: before
1: before
5: after
6: before
2: before
7: before
8: before
3: before
4: before

Is this expected? Should the docstring be changed or I just got it wrong? It seems to me that this macro should be called @only_once instead.

[carstenbauer]

This was indeed a bug. I committed a fix (to master). Feel free to try it out.