let len = 25000000
let map = Map.ofArray[|for i =1 to len do yield (i,i+1)|]
let maparr = [|map;map;map;map|]
let f1 i =
for i1 =1 to len do
let l1 = maparr.[i-1].Item(i1)
()
let index = [|1..4|]
let _ = index |> Array.Parallel.map f1
printf "done"
I found that only one core is working at full speed be the code above . But what i except is all the four thread is working together with a high level of cpu usage. So it seems multithread conflict with Map, am i right? If not, how can achieve my initial goal? Thank you in advance
So I think you were tripping a heuristic where the library assumed when there were only a small number of tasks, it would be fastest to just use a single thread.
This code maxes out all threads on my computer:
let len = 1000000
let map = Map.ofArray[|for i =1 to len do yield (i,i+1)|]
let maparr = [|map;map;map;map|]
let f1 (m:Map<_,_>) =
let mutable sum = 0
for i1 =1 to len do
let l1 = m.Item(i1)
for i = 1 to 10000 do
sum <- sum + 1
printfn "%i" sum
let index = [|1..40|]
printfn "starting"
index |> Array.map (fun t -> maparr.[(t-1)/10]) |> Array.Parallel.iter f1
printf "done"
Important changes: