Async code crashes in Swift Playground but not in Project

The funny thing is everything executes fine. I get all my last print line but then it is crashing when it exits. If I take out:

    await  calculated_async = get_calculations_async(my: inputs)

It will stop crashing. It could be I’m missing something fundamental with async-await?

I cut a copy of this code out of my project to mess around with it more in Playground. And that exact same code does not have any issues in Project (Command Line Tool) crashing or anything. I don’t know how to debug this scenario.

The code

import Foundation
import Cocoa

let inputs: [(Int, Int)] = [(1, 4), (2, 7), (3, 2), (4, 3), (5, 4), (6, 7), (7, 12), (8, 8), (9, 12), (10, 1), (11, 32), (12, 45), (13, 8), (14, 5), (15, 25), (16, 1), (17, 24), (18, 95), (19, 5), (20, 2)]

struct Calculations
{
    let hypotenuse: Double
    let voltage: Double
}

func calculate(x: Int, y: Int) -> Calculations
{
    let hypotenuse: Double = sqrt(Double(x*x + y*y))
    let voltage: Double = Double(x*y)
    let calculations: Calculations = Calculations(hypotenuse: hypotenuse, voltage: voltage)
    return calculations
}

func calculate_async(key: Int, x: Int, y: Int) async -> (Int, Calculations)
{
    let hypotenuse: Double = sqrt(Double(x*x + y*y))
    let voltage: Double = Double(x*y)
    let calculations: Calculations = Calculations(hypotenuse: hypotenuse, voltage: voltage)
    return (key, calculations)
}

func get_calculations(my inputs: [(Int, Int)]) -> [Calculations]
{
    var solutions: [Calculations] = [Calculations](repeating: Calculations(hypotenuse: -1, voltage: 1), count: inputs.count)
    for index in inputs.indices
    {
        solutions[index] = calculate(x: inputs[index].0, y: inputs[index].1)
    }
    return solutions
}

func get_calculations_async(my inputs: [(Int, Int)]) async -> [Calculations]
{
    let processed = await withTaskGroup(of: (Int, Calculations).self, returning: [Calculations].self) { taskGroup in
        for index in inputs.indices
        {
            taskGroup.addTask(priority: .background)
            {
                await calculate_async(key: index, x: inputs[index].0, y: inputs[index].1)
            }
        }
        var solutions: [Calculations] = [Calculations](repeating: Calculations(hypotenuse: -1, voltage: 1), count: inputs.count)
        for await result in taskGroup
        //while let result = await taskGroup.next()
        {
            solutions[result.0] = result.1
        }
        return solutions
    }
    return processed
}
let time = ContinuousClock().measure
{
    let calculated = get_calculations(my: inputs)
    print("CALCULATED:")
    for index in calculated.indices
    {
        print("(inputs[index]) -> hypotenuse: (calculated[index].hypotenuse) voltage: (calculated[index].voltage)", terminator: " :: ")
    }
}
let t = Double(time.components.attoseconds) * 1e-15
print("nt msecs: (t)ms")

//let time_async = ContinuousClock().measure
//{
    let t0 = CACurrentMediaTime()
    var calculated_async: [Calculations]
    await  calculated_async = get_calculations_async(my: inputs)
    print("nASYNC CALCULATED:")
    for index in calculated_async.indices
    {
        print("(inputs[index]) -> hypotenuse: (calculated_async[index].hypotenuse) voltage: (calculated_async[index].voltage)", terminator: " :: ")
    }
//}
let t_async  = (CACurrentMediaTime() - t0)*1000
print("nt async msecs: (t_async)ms")
print("nGot (100 * (t - t_async)/t)% performance increase")

The output

CALCULATED:
(1, 4) -> hypotenuse: 4.123105625617661 voltage: 4.0 :: (2, 7) -> hypotenuse: 7.280109889280518 voltage: 14.0 :: (3, 2) -> hypotenuse: 3.605551275463989 voltage: 6.0 :: (4, 3) -> hypotenuse: 5.0 voltage: 12.0 :: (5, 4) -> hypotenuse: 6.4031242374328485 voltage: 20.0 :: (6, 7) -> hypotenuse: 9.219544457292887 voltage: 42.0 :: (7, 12) -> hypotenuse: 13.892443989449804 voltage: 84.0 :: (8, 8) -> hypotenuse: 11.313708498984761 voltage: 64.0 :: (9, 12) -> hypotenuse: 15.0 voltage: 108.0 :: (10, 1) -> hypotenuse: 10.04987562112089 voltage: 10.0 :: (11, 32) -> hypotenuse: 33.83784863137726 voltage: 352.0 :: (12, 45) -> hypotenuse: 46.57252408878007 voltage: 540.0 :: (13, 8) -> hypotenuse: 15.264337522473747 voltage: 104.0 :: (14, 5) -> hypotenuse: 14.866068747318506 voltage: 70.0 :: (15, 25) -> hypotenuse: 29.154759474226502 voltage: 375.0 :: (16, 1) -> hypotenuse: 16.0312195418814 voltage: 16.0 :: (17, 24) -> hypotenuse: 29.410882339705484 voltage: 408.0 :: (18, 95) -> hypotenuse: 96.6902270139025 voltage: 1710.0 :: (19, 5) -> hypotenuse: 19.6468827043885 voltage: 95.0 :: (20, 2) -> hypotenuse: 20.09975124224178 voltage: 40.0 :: 
t msecs: 31.005333000000004ms

ASYNC CALCULATED:
(1, 4) -> hypotenuse: 4.123105625617661 voltage: 4.0 :: (2, 7) -> hypotenuse: 7.280109889280518 voltage: 14.0 :: (3, 2) -> hypotenuse: 3.605551275463989 voltage: 6.0 :: (4, 3) -> hypotenuse: 5.0 voltage: 12.0 :: (5, 4) -> hypotenuse: 6.4031242374328485 voltage: 20.0 :: (6, 7) -> hypotenuse: 9.219544457292887 voltage: 42.0 :: (7, 12) -> hypotenuse: 13.892443989449804 voltage: 84.0 :: (8, 8) -> hypotenuse: 11.313708498984761 voltage: 64.0 :: (9, 12) -> hypotenuse: 15.0 voltage: 108.0 :: (10, 1) -> hypotenuse: 10.04987562112089 voltage: 10.0 :: (11, 32) -> hypotenuse: 33.83784863137726 voltage: 352.0 :: (12, 45) -> hypotenuse: 46.57252408878007 voltage: 540.0 :: (13, 8) -> hypotenuse: 15.264337522473747 voltage: 104.0 :: (14, 5) -> hypotenuse: 14.866068747318506 voltage: 70.0 :: (15, 25) -> hypotenuse: 29.154759474226502 voltage: 375.0 :: (16, 1) -> hypotenuse: 16.0312195418814 voltage: 16.0 :: (17, 24) -> hypotenuse: 29.410882339705484 voltage: 408.0 :: (18, 95) -> hypotenuse: 96.6902270139025 voltage: 1710.0 :: (19, 5) -> hypotenuse: 19.6468827043885 voltage: 95.0 :: (20, 2) -> hypotenuse: 20.09975124224178 voltage: 40.0 :: 
t async msecs: 2.583541441708803ms

Got 91.66742882036196% performance increase
Playground execution failed:

error: execution stopped with unexpected state.
error: Execution was interrupted.
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

Filed under: Kiến thức lập trình - @ 04:01

Thẻ: swiftasync-awaitswift-playground

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Async code crashes in Swift Playground but not in Project