[julia-users] Threads.@threads and throw ErrorException interaction

[Diego Javier Zea]

Hi, 
I was starting to play with* Threads.@threads *and I noticed a strange 
behaviour when the macro is used together with *throw* and *ErrorException*:

  | | |_| | | | (_| |  |  Version 0.5.0 (2016-09-19 18:14 UTC)
 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release
|__/                   |  x86_64-pc-linux-gnu

julia> a = zeros(10);

julia> Threads.@threads for i = 1:10
           a[i] = Threads.threadid()
           if 4 <= i <= 8
               throw(ErrorException("My Error"))
           end
       end

julia> a
10-element Array{Float64,1}:
 1.0
 1.0
 1.0
 2.0
 0.0
 0.0
 3.0
 0.0
 4.0
 4.0

julia> a = zeros(10);

julia> Threads.@threads for i = 1:10
           if 4 <= i <= 8
               throw(ErrorException("My Error"))
           end
           a[i] = Threads.threadid()
       end

julia> a
10-element Array{Float64,1}:
 1.0
 1.0
 1.0
 0.0
 0.0
 0.0
 0.0
 0.0
 4.0
 4.0

The loop isn't terminated with the error and there is not error message 
printed. When the *throw* is at the end of the loop body, the result looks 
strange and unpredictable.
*Is this behaviour expected?  *
*Do I simply need to avoid using throw and threads together?*

*Best,*