Proper async looping in console app

I know async I/O doesn't bring parallelism but I thought when the app is awaiting an async operation it could carry on doing other stuff.

Consider the below code I would expect the loop to carry on while awaiting Wait(i) but obviously I was wrong and each iteration is blocking. What's the correct way to achieve some concurrency here?

using System;
using System.Threading.Tasks;

namespace asynctest

class Program

static void Main(string args)

Do().GetAwaiter().GetResult();


public static async Task Do()

for(int i=0;i<10;i++)

await Wait(i);



public static async Task Wait(int i)

await Task.Delay(10000);





await

2 Answers
2

public static async Task Do()

var tasks = new Task[10];
for (int i = 0; i < 10; i++)

tasks[i] = Wait(i);


await Task.WhenAll(tasks);



You should use WhenAll() to combine the task results, thus your tasks will run in parallel:

WhenAll()

namespace asynctest

class Program

static void Main(string args)

Do().GetAwaiter().GetResult();


public static async Task Do()

for(int i=0;i<10;i++)


var task1 = Wait(5000);
var task2 = Wait(3000);
int result = await Task.WhenAll(task1, task2);
Console.WriteLine("waited for a total of " + result.Sum() + " ms");



public static async Task<int> Wait(int i)

await Task.Delay(i);
return i;





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