Task.WaitAny Method

Definition

Namespace:

System.Threading.Tasks

Assembly:

System.Runtime.dll

Waits for any of the provided Task objects to complete execution.

Overloads

WaitAny(Task[], TimeSpan)	Waits for any of the provided Task objects to complete execution within a specified time interval.
WaitAny(Task[], Int32, CancellationToken)	Waits for any of the provided Task objects to complete execution within a specified number of milliseconds or until a cancellation token is cancelled.
WaitAny(Task[], Int32)	Waits for any of the provided Task objects to complete execution within a specified number of milliseconds.
WaitAny(Task[], CancellationToken)	Waits for any of the provided Task objects to complete execution unless the wait is cancelled.
WaitAny(Task[])	Waits for any of the provided Task objects to complete execution.

WaitAny(Task[], TimeSpan)

Source:

Task.cs

Waits for any of the provided Task objects to complete execution within a specified time interval.

public:
 static int WaitAny(cli::array <System::Threading::Tasks::Task ^> ^ tasks, TimeSpan timeout);

public static int WaitAny (System.Threading.Tasks.Task[] tasks, TimeSpan timeout);

static member WaitAny : System.Threading.Tasks.Task[] * TimeSpan -> int

Public Shared Function WaitAny (tasks As Task(), timeout As TimeSpan) As Integer

Parameters

tasks

Task[]

An array of Task instances on which to wait.

timeout

TimeSpan

A TimeSpan that represents the number of milliseconds to wait, or a TimeSpan that represents -1 milliseconds to wait indefinitely.

Returns

Int32

The index of the completed task in the tasks array argument, or -1 if the timeout occurred.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The tasks argument is null.

ArgumentOutOfRangeException

The TotalMilliseconds property of the timeout argument is a negative number other than -1, which represents an infinite time-out.

-or-

The TotalMilliseconds property of the timeout argument is greater than Int32.MaxValue.

ArgumentException

The tasks argument contains a null element.

WaitAny(Task[], Int32, CancellationToken)

Source:

Task.cs

Waits for any of the provided Task objects to complete execution within a specified number of milliseconds or until a cancellation token is cancelled.

public:
 static int WaitAny(cli::array <System::Threading::Tasks::Task ^> ^ tasks, int millisecondsTimeout, System::Threading::CancellationToken cancellationToken);

public static int WaitAny (System.Threading.Tasks.Task[] tasks, int millisecondsTimeout, System.Threading.CancellationToken cancellationToken);

static member WaitAny : System.Threading.Tasks.Task[] * int * System.Threading.CancellationToken -> int

Public Shared Function WaitAny (tasks As Task(), millisecondsTimeout As Integer, cancellationToken As CancellationToken) As Integer

Parameters

tasks

Task[]

An array of Task instances on which to wait.

millisecondsTimeout

Int32

The number of milliseconds to wait, or Infinite (-1) to wait indefinitely.

cancellationToken

CancellationToken

A CancellationToken to observe while waiting for a task to complete.

Returns

Int32

The index of the completed task in the tasks array argument, or -1 if the timeout occurred.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The tasks argument is null.

ArgumentOutOfRangeException

millisecondsTimeout is a negative number other than -1, which represents an infinite time-out.

ArgumentException

The tasks argument contains a null element.

OperationCanceledException

The cancellationToken was canceled.

WaitAny(Task[], Int32)

Source:

Task.cs

Waits for any of the provided Task objects to complete execution within a specified number of milliseconds.

public:
 static int WaitAny(cli::array <System::Threading::Tasks::Task ^> ^ tasks, int millisecondsTimeout);

public static int WaitAny (System.Threading.Tasks.Task[] tasks, int millisecondsTimeout);

static member WaitAny : System.Threading.Tasks.Task[] * int -> int

Public Shared Function WaitAny (tasks As Task(), millisecondsTimeout As Integer) As Integer

Parameters

tasks

Task[]

An array of Task instances on which to wait.

millisecondsTimeout

Int32

The number of milliseconds to wait, or Infinite (-1) to wait indefinitely.

Returns

Int32

The index of the completed task in the tasks array argument, or -1 if the timeout occurred.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The tasks argument is null.

ArgumentOutOfRangeException

millisecondsTimeout is a negative number other than -1, which represents an infinite time-out.

ArgumentException

The tasks argument contains a null element.

WaitAny(Task[], CancellationToken)

Source:

Task.cs

Waits for any of the provided Task objects to complete execution unless the wait is cancelled.

public:
 static int WaitAny(cli::array <System::Threading::Tasks::Task ^> ^ tasks, System::Threading::CancellationToken cancellationToken);

public static int WaitAny (System.Threading.Tasks.Task[] tasks, System.Threading.CancellationToken cancellationToken);

static member WaitAny : System.Threading.Tasks.Task[] * System.Threading.CancellationToken -> int

Public Shared Function WaitAny (tasks As Task(), cancellationToken As CancellationToken) As Integer

Parameters

tasks

Task[]

An array of Task instances on which to wait.

cancellationToken

CancellationToken

A CancellationToken to observe while waiting for a task to complete.

Returns

Int32

The index of the completed task in the tasks array argument.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The tasks argument is null.

ArgumentException

The tasks argument contains a null element.

OperationCanceledException

The cancellationToken was canceled.

WaitAny(Task[])

Source:

Task.cs

Waits for any of the provided Task objects to complete execution.

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

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

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

Public Shared Function WaitAny (ParamArray tasks As Task()) As Integer

Parameters

tasks

Task[]

An array of Task instances on which to wait.

Returns

Int32

The index of the completed Task object in the tasks array.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The tasks argument is null.

ArgumentException

The tasks argument contains a null element.

Examples

The following example launches five tasks, each of which sleeps for a minimum of 50 milliseconds or a maximum of 1,050 milliseconds. The WaitAny method then waits for any of the tasks to complete. The example displays the task ID of the task that ended the wait, as well as the current status of all the tasks.

using System;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      Task[] tasks = new Task[5];
      for (int ctr = 0; ctr <= 4; ctr++) {
         int factor = ctr;
         tasks[ctr] = Task.Run(() => Thread.Sleep(factor * 250 + 50));
      }
      int index = Task.WaitAny(tasks);
      Console.WriteLine("Wait ended because task #{0} completed.",
                        tasks[index].Id);
      Console.WriteLine("\nCurrent Status of Tasks:");
      foreach (var t in tasks)
         Console.WriteLine("   Task {0}: {1}", t.Id, t.Status);
   }
}
// The example displays output like the following:
//       Wait ended because task #1 completed.
//
//       Current Status of Tasks:
//          Task 1: RanToCompletion
//          Task 2: Running
//          Task 3: Running
//          Task 4: Running
//          Task 5: Running

open System.Threading
open System.Threading.Tasks

let tasks =
    [| for factor = 0 to 4 do
           Task.Run(fun () -> Thread.Sleep(factor * 250 + 50)) |]

let index = Task.WaitAny tasks
printfn $"Wait ended because task #{tasks[index].Id} completed."
printfn "\nCurrent Status of Tasks:"

for t in tasks do
    printfn $"   Task {t.Id}: {t.Status}"


// The example displays output like the following:
//       Wait ended because task #1 completed.
//
//       Current Status of Tasks:
//          Task 1: RanToCompletion
//          Task 2: Running
//          Task 3: Running
//          Task 4: Running
//          Task 5: Running

Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim tasks(4) As Task
      For ctr As Integer = 0 To 4
         Dim factor As Integer = ctr
         tasks(ctr) = Task.Run(Sub() Thread.Sleep(factor * 250 + 50))
      Next
      Dim index As Integer = Task.WaitAny(tasks)

      Console.WriteLine("Wait ended because task #{0} completed.",
                        tasks(index).Id)
      Console.WriteLine()
      Console.WriteLine("Current Status of Tasks:")
      For Each t In tasks
         Console.WriteLine("   Task {0}: {1}", t.Id, t.Status)
      Next
   End Sub
End Module
' The example displays output like the following:
'       Wait ended because task #1 completed.
'
'       Current Status of Tasks:
'          Task 1: RanToCompletion
'          Task 2: Running
'          Task 3: Running
'          Task 4: Running
'          Task 5: Running