CODEWITHSUNDEEP
f#
ca9163d9
ca9163d9

Reputation: 29159

Run function in parallel in async workflow?

The following code

let doWork n = async {
    [1..5]
    |> Seq.iter(fun i ->
        System.Threading.Thread.Sleep 1000 // Simulate working
        printfn "%s runs %i seconds" n i
        )
}

let f1 = async {
    do! doWork "f1"
    return 1
}

async {
    let a = f1
    do! doWork "main"
    let! i = a
} |> Async.RunSynchronously

And it prints the following result. It shows that the two doWork calls run sequentially. 

main runs 1 seconds
main runs 2 seconds
main runs 3 seconds
main runs 4 seconds
main runs 5 seconds
f1 runs 1 seconds
f1 runs 2 seconds
f1 runs 3 seconds
f1 runs 4 seconds
f1 runs 5 seconds

However, I want the doWork called by f1 and the main code be running in parallel?

Upvotes: 1

Views: 89

Answers (1)

ajuch
ajuch

Reputation: 415

Try it like this:

let computation () = async {
  printfn "Start work"
  do! Async.Sleep(100)
  printfn "Finished work"
}

let s = seq {
  for i in 1 .. 10 do
    let c = computation()
    yield c
}

s |> Async.Parallel |> Async.Ignore |> Async.Start

Async.Parallel converts the Async<unit> list to Async<unit []> which can be run in parallel then.

Upvotes: 1

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