Channel in Julia - julia

Question

I read about channel in julia in parallel computing.
I realized that we can use channel to be able to write and read in a same time. When I wanted to try it I find out when we use take actually we take the top data on channel and then remove it from that! How another process can read that ? and how channel is doing parallel? and I don't know when it's good for using that and how efficient it is.
-------------------- EDITE---------------------- :
This is a simple program for showing how to use channel for parallelisation:
julia> addprocs(4)
4-element Array{Int64,1}:
2
3
4
5
julia> const jobs = RemoteChannel(()->Channel{Int}(32))
RemoteChannel{Channel{Int64}}(1, 1, 6)
julia> const results = RemoteChannel(()->Channel{Tuple}(32))
RemoteChannel{Channel{Tuple}}(1, 1, 7)
julia> #everywhere function do_work(jobs,results)
while true
job_id=take!(jobs)
exec_time=rand()
sleep(exec_time)
put!(results, (job_id, exec_time, myid()))
end
end
julia> function make_jobs(n)
for i in 1:n
put!(jobs,i)
end
end
make_jobs (generic function with 1 method)
julia> n=12
12
julia> #schedule make_jobs(n)
Task (done) #0x00007fa873905a50
julia> for p in workers()
#async remote_do(do_work, p, jobs, results)
end
julia> #elapsed while n>0
job_id, exec_time, where=take!(results)
println("$job_id finished in $(round(exec_time,2)) seconds on worker $where")
n=n-1
end
4 finished in 0.13 seconds on worker 5
1 finished in 0.21 seconds on worker 4
2 finished in 0.64 seconds on worker 3
3 finished in 0.82 seconds on worker 2
6 finished in 0.72 seconds on worker 5
7 finished in 0.35 seconds on worker 3
5 finished in 0.89 seconds on worker 4
11 finished in 0.33 seconds on worker 4
10 finished in 0.61 seconds on worker 3
8 finished in 0.82 seconds on worker 2
9 finished in 0.71 seconds on worker 5
12 finished in 0.24 seconds on worker 4
0.082128167
I can't understand! We can use a a for loop instead of the function do_work! and then we can save it the result as an SharedArray and then we could parallel it by dynamic scheduling or something.
Why we are using like this?
Actually my question is when we use like this? and why?