Comparison between parallel map in Elixir and map

tasks.exs

# p_map is a parallel map which runs each and every process concurrently 
> p_map = fn -> 1..5 |> Enum.map(fn(i) -> Task.async(fn -> :timer.sleep(200); i + 1 end) end) |> Enum.map(fn(tsk) -> Task.await(tsk) end) end

# slow_map runs each and every iteration one after the other
> slow_map = fn -> 1..5 |> Enum.map(fn(i) -> :timer.sleep(200); i + 1 end) end

> :timer.tc(fn -> p_map.() end, [])
{200830, [2, 3, 4, 5, 6]}

> :timer.tc(fn -> slow_map.() end, [])
{1004430, [2, 3, 4, 5, 6]}

# all results are displayed in microseconds so therefore the p_map has taken around 0.2 seconds and slow_map has taken 1 second
# each task slept 200 milliseconds which makes sense that pmap would take 0.2 seconds as each task ran in parallel
# this also explains why slow_map has taken 1 second. 200 milliseconds * 5 = 1 second to run each iteration sequentially