Task.WhenAll 方法

定義

命名空間:

System.Threading.Tasks

組件:

System.Runtime.dll

建立當所有提供的工作都完成時，將會完成的工作。

多載

WhenAll(IEnumerable<Task>)	建立工作，此工作會在可列舉集合中的所有 Task 物件都完成時完成。
WhenAll(Task[])	建立當陣列中的所有 Task 物件都完成時，將會完成的工作。
WhenAll<TResult>(IEnumerable<Task<TResult>>)	建立工作，此工作會在可列舉集合中的所有 Task<TResult> 物件都完成時完成。
WhenAll<TResult>(Task<TResult>[])	建立當陣列中的所有 Task<TResult> 物件都完成時，將會完成的工作。

WhenAll(IEnumerable<Task>)

來源:

Task.cs

建立工作，此工作會在可列舉集合中的所有 Task 物件都完成時完成。

public:
 static System::Threading::Tasks::Task ^ WhenAll(System::Collections::Generic::IEnumerable<System::Threading::Tasks::Task ^> ^ tasks);

public static System.Threading.Tasks.Task WhenAll (System.Collections.Generic.IEnumerable<System.Threading.Tasks.Task> tasks);

static member WhenAll : seq<System.Threading.Tasks.Task> -> System.Threading.Tasks.Task

Public Shared Function WhenAll (tasks As IEnumerable(Of Task)) As Task

參數

tasks

IEnumerable<Task>

要等候完成的工作。

傳回

Task

表示所有所提供工作完成的工作。

例外狀況

ArgumentNullException

tasks 自變數 null。

ArgumentException

tasks 集合包含 null 工作。

範例

下列範例會建立一組工作，以偵測陣列中的URL。 工作會儲存在傳遞至 WhenAll(IEnumerable<Task>) 方法的 List<Task> 集合中。 呼叫 Wait 方法可確保所有線程都已完成之後，此範例會檢查 Task.Status 屬性，以判斷是否有任何工作發生錯誤。

using System;
using System.Collections.Generic;
using System.Net.NetworkInformation;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      int failed = 0;
      var tasks = new List<Task>();
      String[] urls = { "www.adatum.com", "www.cohovineyard.com",
                        "www.cohowinery.com", "www.northwindtraders.com",
                        "www.contoso.com" };
      
      foreach (var value in urls) {
         var url = value;
         tasks.Add(Task.Run( () => { var png = new Ping();
                                     try {
                                        var reply = png.Send(url);
                                        if (! (reply.Status == IPStatus.Success)) {
                                           Interlocked.Increment(ref failed);
                                           throw new TimeoutException("Unable to reach " + url + ".");
                                        }
                                     }
                                     catch (PingException) {
                                        Interlocked.Increment(ref failed);
                                        throw;
                                     }
                                   }));
      }
      Task t = Task.WhenAll(tasks);
      try {
         t.Wait();
      }
      catch {}   

      if (t.Status == TaskStatus.RanToCompletion)
         Console.WriteLine("All ping attempts succeeded.");
      else if (t.Status == TaskStatus.Faulted)
         Console.WriteLine("{0} ping attempts failed", failed);      
   }
}
// The example displays output like the following:
//       5 ping attempts failed

open System
open System.Net.NetworkInformation
open System.Threading
open System.Threading.Tasks

let mutable failed = 0

let urls =
    [ "www.adatum.com"
      "www.cohovineyard.com"
      "www.cohowinery.com"
      "www.northwindtraders.com"
      "www.contoso.com" ]

let tasks =
    urls
    |> List.map (fun url ->
        Task.Run(fun () ->
            let png = new Ping()

            try
                let reply = png.Send url

                if reply.Status <> IPStatus.Success then
                    Interlocked.Increment &failed |> ignore
                    raise (TimeoutException $"Unable to reach {url}.")
            with :? PingException ->
                Interlocked.Increment &failed |> ignore
                reraise ()))

let t = Task.WhenAll tasks

try
    t.Wait()
with _ ->
    ()

if t.Status = TaskStatus.RanToCompletion then
    printfn "All ping attempts succeeded."
elif t.Status = TaskStatus.Faulted then
    printfn $"{failed} ping attempts failed"

// The example displays output like the following:
//       5 ping attempts failed

Imports System.Collections.Generic
Imports System.Net.NetworkInformation
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim failed As Integer = 0
      Dim tasks As New List(Of Task)()
      Dim urls() As String = { "www.adatum.com", "www.cohovineyard.com",
                              "www.cohowinery.com", "www.northwindtraders.com",
                              "www.contoso.com" }
      
      For Each value In urls
         Dim url As String = value
         tasks.Add(Task.Run( Sub()
                                Dim png As New Ping()
                                Try
                                   Dim reply = png.Send(url)
                                   If Not reply.Status = IPStatus.Success Then
                                      Interlocked.Increment(failed)
                                      Throw New TimeoutException("Unable to reach " + url + ".")
                                   End If
                                   Catch e As PingException
                                      Interlocked.Increment(failed)
                                      Throw
                                   End Try
                             End Sub))
      Next
      Dim t As Task = Task.WhenAll(tasks)
      Try
         t.Wait()
      Catch
      End Try   

      If t.Status = TaskStatus.RanToCompletion
         Console.WriteLine("All ping attempts succeeded.")
      ElseIf t.Status = TaskStatus.Faulted
         Console.WriteLine("{0} ping attempts failed", failed)      
      End If
   End Sub
End Module
' The example displays output like the following:
'     5 ping attempts failed

備註

傳回 Task 物件之 WhenAll 方法的多載通常會在您對一組工作的狀態或一組工作擲回的例外狀況感興趣時呼叫。

注意

對 WhenAll(IEnumerable<Task>) 方法的呼叫不會封鎖呼叫線程。

如果任何提供的工作都以錯誤狀態完成，傳回的工作也會以 Faulted 狀態完成，其中其例外狀況會包含每個所提供工作未包裝例外狀況集的匯總。

如果沒有提供的工作發生錯誤，但至少其中一項已取消，則傳回的工作將會以 Canceled 狀態結束。

如果沒有任何工作發生錯誤且未取消任何工作，則產生的工作將會以 RanToCompletion 狀態結束。

如果提供的陣列舉不包含任何工作，則傳回的工作會在傳回給呼叫端之前，立即轉換為 RanToCompletion 狀態。

WhenAll(Task[])

來源:

Task.cs

建立當陣列中的所有 Task 物件都完成時，將會完成的工作。

public:
 static System::Threading::Tasks::Task ^ WhenAll(... cli::array <System::Threading::Tasks::Task ^> ^ tasks);

public static System.Threading.Tasks.Task WhenAll (params System.Threading.Tasks.Task[] tasks);

static member WhenAll : System.Threading.Tasks.Task[] -> System.Threading.Tasks.Task

Public Shared Function WhenAll (ParamArray tasks As Task()) As Task

參數

tasks

Task[]

要等候完成的工作。

傳回

Task

表示所有所提供工作完成的工作。

例外狀況

ArgumentNullException

tasks 自變數 null。

ArgumentException

tasks 陣列包含 null 工作。

範例

下列範例會建立一組工作，以偵測陣列中的URL。 工作會儲存在轉換成陣列並傳遞至 WhenAll(IEnumerable<Task>) 方法的 List<Task> 集合中。 呼叫 Wait 方法可確保所有線程都已完成之後，此範例會檢查 Task.Status 屬性，以判斷是否有任何工作發生錯誤。

using System;
using System.Collections.Generic;
using System.Net.NetworkInformation;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static async Task Main()
   {
      int failed = 0;
      var tasks = new List<Task>();
      String[] urls = { "www.adatum.com", "www.cohovineyard.com",
                        "www.cohowinery.com", "www.northwindtraders.com",
                        "www.contoso.com" };
      
      foreach (var value in urls) {
         var url = value;
         tasks.Add(Task.Run( () => { var png = new Ping();
                                     try {
                                        var reply = png.Send(url);
                                        if (! (reply.Status == IPStatus.Success)) {
                                           Interlocked.Increment(ref failed);
                                           throw new TimeoutException("Unable to reach " + url + ".");
                                        }
                                     }
                                     catch (PingException) {
                                        Interlocked.Increment(ref failed);
                                        throw;
                                     }
                                   }));
      }
      Task t = Task.WhenAll(tasks.ToArray());
      try {
         await t;
      }
      catch {}   

      if (t.Status == TaskStatus.RanToCompletion)
         Console.WriteLine("All ping attempts succeeded.");
      else if (t.Status == TaskStatus.Faulted)
         Console.WriteLine("{0} ping attempts failed", failed);      
   }
}
// The example displays output like the following:
//       5 ping attempts failed

open System
open System.Net.NetworkInformation
open System.Threading
open System.Threading.Tasks

let mutable failed = 0

let urls =
    [| "www.adatum.com"
       "www.cohovineyard.com"
       "www.cohowinery.com"
       "www.northwindtraders.com"
       "www.contoso.com" |]

let tasks =
    urls
    |> Array.map (fun url ->
        Task.Run(fun () ->
            let png = new Ping()

            try
                let reply = png.Send url

                if reply.Status <> IPStatus.Success then
                    Interlocked.Increment &failed |> ignore
                    raise (TimeoutException $"Unable to reach {url}.")
            with :? PingException ->
                Interlocked.Increment &failed |> ignore
                reraise ()))

let main =
    task {
        let t = Task.WhenAll tasks

        try
            do! t
        with _ ->
            ()

        if t.Status = TaskStatus.RanToCompletion then
            printfn "All ping attempts succeeded."
        elif t.Status = TaskStatus.Faulted then
            printfn $"{failed} ping attempts failed"
    }

main.Wait()
// The example displays output like the following:
//       5 ping attempts failed

Imports System.Collections.Generic
Imports System.Net.NetworkInformation
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim failed As Integer = 0
      Dim tasks As New List(Of Task)()
      Dim urls() As String = { "www.adatum.com", "www.cohovineyard.com",
                              "www.cohowinery.com", "www.northwindtraders.com",
                              "www.contoso.com" }
      
      For Each value In urls
         Dim url As String = value
         tasks.Add(Task.Run( Sub()
                                Dim png As New Ping()
                                Try
                                   Dim reply = png.Send(url)
                                   If Not reply.Status = IPStatus.Success Then
                                      Interlocked.Increment(failed)
                                      Throw New TimeoutException("Unable to reach " + url + ".")
                                   End If
                                   Catch e As PingException
                                      Interlocked.Increment(failed)
                                      Throw
                                   End Try
                             End Sub))
      Next
      Dim t As Task = Task.WhenAll(tasks.ToArray())
      Try
         t.Wait()
      Catch
      End Try   

      If t.Status = TaskStatus.RanToCompletion
         Console.WriteLine("All ping attempts succeeded.")
      ElseIf t.Status = TaskStatus.Faulted
         Console.WriteLine("{0} ping attempts failed", failed)      
      End If
   End Sub
End Module
' The example displays output like the following:
'     5 ping attempts failed

備註

傳回 Task 物件之 WhenAll 方法的多載通常會在您對一組工作的狀態或一組工作擲回的例外狀況感興趣時呼叫。

注意

對 WhenAll(Task[]) 方法的呼叫不會封鎖呼叫線程。

如果任何提供的工作都以錯誤狀態完成，傳回的工作也會以 Faulted 狀態完成，其中其例外狀況會包含每個所提供工作未包裝例外狀況集的匯總。

如果沒有提供的工作發生錯誤，但至少其中一項已取消，則傳回的工作將會以 Canceled 狀態結束。

如果沒有任何工作發生錯誤且未取消任何工作，則產生的工作將會以 RanToCompletion 狀態結束。

如果提供的陣列舉不包含任何工作，則傳回的工作會在傳回給呼叫端之前，立即轉換為 RanToCompletion 狀態。

WhenAll<TResult>(IEnumerable<Task<TResult>>)

來源:

Task.cs

建立工作，此工作會在可列舉集合中的所有 Task<TResult> 物件都完成時完成。

public:
generic <typename TResult>
 static System::Threading::Tasks::Task<cli::array <TResult> ^> ^ WhenAll(System::Collections::Generic::IEnumerable<System::Threading::Tasks::Task<TResult> ^> ^ tasks);

public static System.Threading.Tasks.Task<TResult[]> WhenAll<TResult> (System.Collections.Generic.IEnumerable<System.Threading.Tasks.Task<TResult>> tasks);

static member WhenAll : seq<System.Threading.Tasks.Task<'Result>> -> System.Threading.Tasks.Task<'Result[]>

Public Shared Function WhenAll(Of TResult) (tasks As IEnumerable(Of Task(Of TResult))) As Task(Of TResult())

類型參數

TResult

已完成工作的型別。

參數

tasks

IEnumerable<Task<TResult>>

要等候完成的工作。

傳回

Task<TResult[]>

表示所有所提供工作完成的工作。

例外狀況

ArgumentNullException

tasks 自變數 null。

ArgumentException

tasks 集合包含 null 工作。

範例

下列範例會建立10個工作，每個工作都會具現化隨機數產生器，以在1到1,000之間建立1,000個隨機數，並計算其平均值。 Delay(Int32) 方法可用來延遲隨機數產生器的具現化，因此不會使用相同的種子值來建立它們。 接著，呼叫 WhenAll 方法會傳回包含每個工作所計算平均值的 Int64 陣列。 然後，這些會用來計算整體平均值。

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var tasks = new List<Task<long>>();
      for (int ctr = 1; ctr <= 10; ctr++) {
         int delayInterval = 18 * ctr;
         tasks.Add(Task.Run(async () => { long total = 0;
                                          await Task.Delay(delayInterval);
                                          var rnd = new Random();
                                          // Generate 1,000 random numbers.
                                          for (int n = 1; n <= 1000; n++)
                                             total += rnd.Next(0, 1000);
                                          return total; } ));
      }
      var continuation = Task.WhenAll(tasks);
      try {
         continuation.Wait();
      }
      catch (AggregateException)
      { }
   
      if (continuation.Status == TaskStatus.RanToCompletion) {
         long grandTotal = 0;
         foreach (var result in continuation.Result) {
            grandTotal += result;
            Console.WriteLine("Mean: {0:N2}, n = 1,000", result/1000.0);
         }
   
         Console.WriteLine("\nMean of Means: {0:N2}, n = 10,000",
                           grandTotal/10000);
      }
      // Display information on faulted tasks.
      else {
         foreach (var t in tasks) {
            Console.WriteLine("Task {0}: {1}", t.Id, t.Status);
         }
      }
   }
}
// The example displays output like the following:
//       Mean: 506.34, n = 1,000
//       Mean: 504.69, n = 1,000
//       Mean: 489.32, n = 1,000
//       Mean: 505.96, n = 1,000
//       Mean: 515.31, n = 1,000
//       Mean: 499.94, n = 1,000
//       Mean: 496.92, n = 1,000
//       Mean: 508.58, n = 1,000
//       Mean: 494.88, n = 1,000
//       Mean: 493.53, n = 1,000
//
//       Mean of Means: 501.55, n = 10,000

open System
open System.Threading.Tasks

let tasks =
    [| for i = 1 to 10 do
           let delayInterval = 18 * i

           task {
               let mutable total = 0L
               do! Task.Delay delayInterval
               let rnd = Random()

               for _ = 1 to 1000 do
                   total <- total + (rnd.Next(0, 1000) |> int64)

               return total
           } |]

let continuation = Task.WhenAll tasks

try
    continuation.Wait()

with :? AggregateException ->
    ()

if continuation.Status = TaskStatus.RanToCompletion then
    for result in continuation.Result do
        printfn $"Mean: {float result / 1000.:N2}, n = 1,000"

    let grandTotal = continuation.Result |> Array.sum

    printfn $"\nMean of Means: {float grandTotal / 10000.:N2}, n = 10,000"

// Display information on faulted tasks.
else
    for t in tasks do
        printfn $"Task {t.Id}: {t.Status}"

// The example displays output like the following:
//       Mean: 506.34, n = 1,000
//       Mean: 504.69, n = 1,000
//       Mean: 489.32, n = 1,000
//       Mean: 505.96, n = 1,000
//       Mean: 515.31, n = 1,000
//       Mean: 499.94, n = 1,000
//       Mean: 496.92, n = 1,000
//       Mean: 508.58, n = 1,000
//       Mean: 494.88, n = 1,000
//       Mean: 493.53, n = 1,000
//
//       Mean of Means: 501.55, n = 10,000

Imports System.Collections.Generic
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim tasks As New List(Of Task(Of Long))()
      For ctr As Integer = 1 To 10
         Dim delayInterval As Integer = 18 * ctr
         tasks.Add(Task.Run(Async Function()
                               Dim total As Long = 0
                               Await Task.Delay(delayInterval)
                               Dim rnd As New Random()
                               ' Generate 1,000 random numbers.
                               For n As Integer = 1 To 1000
                                  total += rnd.Next(0, 1000)
                               Next
                               Return total
                            End Function))
      Next
      Dim continuation = Task.WhenAll(tasks)
      Try
         continuation.Wait()
      Catch ae As AggregateException
      End Try
      
      If continuation.Status = TaskStatus.RanToCompletion Then
         Dim grandTotal As Long = 0
         For Each result in continuation.Result
            grandTotal += result
            Console.WriteLine("Mean: {0:N2}, n = 1,000", result/1000)
         Next
         Console.WriteLine()
         Console.WriteLine("Mean of Means: {0:N2}, n = 10,000",
                           grandTotal/10000)
      ' Display information on faulted tasks.
      Else 
         For Each t In tasks
            Console.WriteLine("Task {0}: {1}", t.Id, t.Status)
         Next
      End If
   End Sub
End Module
' The example displays output like the following:
'       Mean: 506.34, n = 1,000
'       Mean: 504.69, n = 1,000
'       Mean: 489.32, n = 1,000
'       Mean: 505.96, n = 1,000
'       Mean: 515.31, n = 1,000
'       Mean: 499.94, n = 1,000
'       Mean: 496.92, n = 1,000
'       Mean: 508.58, n = 1,000
'       Mean: 494.88, n = 1,000
'       Mean: 493.53, n = 1,000
'
'       Mean of Means: 501.55, n = 10,000

在此情況下，十個個別工作會儲存在 List<T> 物件中。 List<T> 實作 IEnumerable<T> 介面。

備註

對 WhenAll<TResult>(IEnumerable<Task<TResult>>) 方法的呼叫不會封鎖呼叫線程。 不過，對傳回 Result 屬性的呼叫會封鎖呼叫線程。

如果任何提供的工作都以錯誤狀態完成，傳回的工作也會以 Faulted 狀態完成，其中其例外狀況會包含每個所提供工作未包裝例外狀況集的匯總。

如果沒有提供的工作發生錯誤，但至少其中一項已取消，則傳回的工作將會以 Canceled 狀態結束。

如果沒有任何工作發生錯誤且未取消任何工作，則產生的工作將會以 RanToCompletion 狀態結束。 傳回工作的 Task<TResult>.Result 屬性會設定為陣列，其中包含所提供工作的所有結果，其順序與提供的順序相同（例如，如果輸入工作陣列包含 t1，t2， t3，輸出工作的 Task<TResult>.Result 屬性會傳回 TResult[]，其中 arr[0] == t1.Result, arr[1] == t2.Result, and arr[2] == t3.Result)。

如果 tasks 自變數不包含任何工作，則傳回的工作會在傳回給呼叫端之前，立即轉換為 RanToCompletion 狀態。 傳回的 TResult[] 將是0個專案的陣列。

WhenAll<TResult>(Task<TResult>[])

來源:

Task.cs

建立當陣列中的所有 Task<TResult> 物件都完成時，將會完成的工作。

public:
generic <typename TResult>
 static System::Threading::Tasks::Task<cli::array <TResult> ^> ^ WhenAll(... cli::array <System::Threading::Tasks::Task<TResult> ^> ^ tasks);

public static System.Threading.Tasks.Task<TResult[]> WhenAll<TResult> (params System.Threading.Tasks.Task<TResult>[] tasks);

static member WhenAll : System.Threading.Tasks.Task<'Result>[] -> System.Threading.Tasks.Task<'Result[]>

Public Shared Function WhenAll(Of TResult) (ParamArray tasks As Task(Of TResult)()) As Task(Of TResult())

類型參數

TResult

已完成工作的型別。

參數

tasks

Task<TResult>[]

要等候完成的工作。

傳回

Task<TResult[]>

表示所有所提供工作完成的工作。

例外狀況

ArgumentNullException

tasks 自變數 null。

ArgumentException

tasks 陣列包含 null 工作。

範例

下列範例會建立10個工作，每個工作都會具現化隨機數產生器，以在1到1,000之間建立1,000個隨機數，並計算其平均值。 在此情況下，十個個別工作會儲存在 Task<Int64> 陣列中。 Delay(Int32) 方法可用來延遲隨機數產生器的具現化，因此不會使用相同的種子值來建立它們。 接著，呼叫 WhenAll 方法會傳回包含每個工作所計算平均值的 Int64 陣列。 然後，這些會用來計算整體平均值。

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var tasks = new Task<long>[10];
      for (int ctr = 1; ctr <= 10; ctr++) {
         int delayInterval = 18 * ctr;
         tasks[ctr - 1] = Task.Run(async () => { long total = 0;
                                                 await Task.Delay(delayInterval);
                                                 var rnd = new Random();
                                                 // Generate 1,000 random numbers.
                                                 for (int n = 1; n <= 1000; n++)
                                                    total += rnd.Next(0, 1000);

                                                 return total; } );
      }
      var continuation = Task.WhenAll(tasks);
      try {
         continuation.Wait();
      }
      catch (AggregateException)
      {}
   
      if (continuation.Status == TaskStatus.RanToCompletion) {
         long grandTotal = 0;
         foreach (var result in continuation.Result) {
            grandTotal += result;
            Console.WriteLine("Mean: {0:N2}, n = 1,000", result/1000.0);
         }
   
         Console.WriteLine("\nMean of Means: {0:N2}, n = 10,000",
                           grandTotal/10000);
      }
      // Display information on faulted tasks.
      else { 
         foreach (var t in tasks)
            Console.WriteLine("Task {0}: {1}", t.Id, t.Status);
      }
   }
}
// The example displays output like the following:
//       Mean: 506.38, n = 1,000
//       Mean: 501.01, n = 1,000
//       Mean: 505.36, n = 1,000
//       Mean: 492.00, n = 1,000
//       Mean: 508.36, n = 1,000
//       Mean: 503.99, n = 1,000
//       Mean: 504.95, n = 1,000
//       Mean: 508.58, n = 1,000
//       Mean: 490.23, n = 1,000
//       Mean: 501.59, n = 1,000
//
//       Mean of Means: 502.00, n = 10,000

open System
open System.Threading.Tasks

let tasks =
    [| for i = 1 to 10 do
           let delayInterval = 18 * i

           task {
               let mutable total = 0L
               do! Task.Delay delayInterval
               let rnd = Random()

               for _ = 1 to 1000 do
                   total <- total + (rnd.Next(0, 1000) |> int64)

               return total
           } |]

let continuation = Task.WhenAll tasks

try
    continuation.Wait()

with :? AggregateException ->
    ()

if continuation.Status = TaskStatus.RanToCompletion then
    for result in continuation.Result do
        printfn $"Mean: {float result / 1000.:N2}, n = 1,000"

    let grandTotal = Array.sum continuation.Result

    printfn $"\nMean of Means: {float grandTotal / 10000.:N2}, n = 10,000"

// Display information on faulted tasks.
else
    for t in tasks do
        printfn $"Task {t.Id}: {t.Status}"

// The example displays output like the following:
//       Mean: 506.38, n = 1,000
//       Mean: 501.01, n = 1,000
//       Mean: 505.36, n = 1,000
//       Mean: 492.00, n = 1,000
//       Mean: 508.36, n = 1,000
//       Mean: 503.99, n = 1,000
//       Mean: 504.95, n = 1,000
//       Mean: 508.58, n = 1,000
//       Mean: 490.23, n = 1,000
//       Mean: 501.59, n = 1,000
//
//       Mean of Means: 502.00, n = 10,000

Imports System.Collections.Generic
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim tasks(9) As Task(Of Long)
      For ctr As Integer = 1 To 10
         Dim delayInterval As Integer = 18 * ctr
         tasks(ctr - 1) =Task.Run(Async Function()
                                     Dim total As Long = 0
                                     Await Task.Delay(delayInterval)
                                     Dim rnd As New Random()
                                     ' Generate 1,000 random numbers.
                                     For n As Integer = 1 To 1000
                                        total += rnd.Next(0, 1000)
                                     Next
                                     Return total
                                  End Function)
      Next
      Dim continuation = Task.WhenAll(tasks)
      Try
         continuation.Wait()
      Catch ae As AggregateException
      End Try
         
      If continuation.Status = TaskStatus.RanToCompletion Then
         Dim grandTotal As Long = 0
         For Each result in continuation.Result
            grandTotal += result
            Console.WriteLine("Mean: {0:N2}, n = 1,000", result/1000)
         Next
         Console.WriteLine()
         Console.WriteLine("Mean of Means: {0:N2}, n = 10,000",
                           grandTotal/10000)
      ' Display information on faulted tasks.
      Else 
         For Each t In tasks
            Console.WriteLine("Task {0}: {1}", t.Id, t.Status)
         Next
      End If
   End Sub
End Module
' The example displays output like the following:
'       Mean: 506.38, n = 1,000
'       Mean: 501.01, n = 1,000
'       Mean: 505.36, n = 1,000
'       Mean: 492.00, n = 1,000
'       Mean: 508.36, n = 1,000
'       Mean: 503.99, n = 1,000
'       Mean: 504.95, n = 1,000
'       Mean: 508.58, n = 1,000
'       Mean: 490.23, n = 1,000
'       Mean: 501.59, n = 1,000
'
'       Mean of Means: 502.00, n = 10,000

備註

對 WhenAll<TResult>(Task<TResult>[]) 方法的呼叫不會封鎖呼叫線程。 不過，對傳回 Result 屬性的呼叫會封鎖呼叫線程。

如果任何提供的工作都以錯誤狀態完成，傳回的工作也會以 Faulted 狀態完成，其中其例外狀況會包含每個所提供工作未包裝例外狀況集的匯總。

如果沒有提供的工作發生錯誤，但至少其中一項已取消，則傳回的工作將會以 Canceled 狀態結束。

如果沒有任何工作發生錯誤且未取消任何工作，則產生的工作將會以 RanToCompletion 狀態結束。 傳回工作的 Result 會設定為數位，其中包含所提供工作的所有結果，其順序與提供的順序相同（例如，如果輸入工作陣列包含 t1，t2， t3，輸出工作的 Result 會傳回 TResult[]，其中 arr[0] == t1.Result, arr[1] == t2.Result, and arr[2] == t3.Result)。

如果提供的陣列舉不包含任何工作，則傳回的工作會在傳回給呼叫端之前，立即轉換為 RanToCompletion 狀態。 傳回的 TResult[] 將是0個專案的陣列。