I have the below MWE for a simple function `test_serial()`

. I tried to parallelize its `p1!()&p2!()`

functions. However, it seems I am not using the `fetch`

correctly. Could you please guide me here?

```
function p1!(x)
x .+= 1;
end
function p2!(x)
x .*= 2;
end
#
function test_serial()
x =[zeros(10),zeros(10)]
for i in 1:5
p1!(x[1])
p1!(x[2])
x[1] .+= 1;
p2!(x[1])
p2!(x[2])
end
return x
end
x = test_serial()
#=
julia> x
[124.0, 124.0, 124.0, 124.0, 124.0, 124.0, 124.0, 124.0, 124.0, 124.0]
[62.0, 62.0, 62.0, 62.0, 62.0, 62.0, 62.0, 62.0, 62.0, 62.0]
=#
function test_parallel()
x =[zeros(10),zeros(10)]
for i in 1:5
tasks = [Threads.@spawn begin
p1!(x[i])
end for i = 1:2];
fetch(tasks);
x[1] .+= 1;
tasks = [Threads.@spawn begin
p2!(x[i])
end for i = 1:2];
fetch(tasks);
end
return x
end
x = test_parallel()
#=
julia> x
2-element Vector{Vector{Float64}}:
[218.0, 218.0, 218.0, 218.0, 218.0, 218.0, 218.0, 218.0, 218.0, 218.0]
[74.0, 74.0, 74.0, 74.0, 74.0, 74.0, 74.0, 74.0, 74.0, 74.0]
=#
```