Parallel.For Parallel.For Parallel.For Parallel.For Method

定義

執行可平行執行反覆項目的 for 迴圈。Executes a for loop in which iterations may run in parallel.

多載

For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>)

執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop in which iterations may run in parallel and the state of the loop can be monitored and manipulated.

For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>)

執行可平行執行反覆項目的 for 迴圈。Executes a for loop in which iterations may run in parallel.

For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes in which iterations may run in parallel and the state of the loop can be monitored and manipulated.

For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目。Executes a for loop with 64-bit indexes in which iterations may run in parallel.

For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>) For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>) For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>)

執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

For(Int32, Int32, ParallelOptions, Action<Int32>) For(Int32, Int32, ParallelOptions, Action<Int32>) For(Int32, Int32, ParallelOptions, Action<Int32>)

執行 for 迴圈,其中可以平行執行反覆項目,還可以設定迴圈選項。Executes a for loop in which iterations may run in parallel and loop options can be configured.

For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>) For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>) For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

For(Int64, Int64, ParallelOptions, Action<Int64>) For(Int64, Int64, ParallelOptions, Action<Int64>) For(Int64, Int64, ParallelOptions, Action<Int64>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目,還可以設定迴圈選項。Executes a for loop with 64-bit indexes in which iterations may run in parallel and loop options can be configured.

For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用 64 位元索引和執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes and thread-local data in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with thread-local data in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with thread-local data in which iterations may run in parallel, and the state of the loop can be monitored and manipulated.

For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用 64 位元索引和執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes and thread-local data in which iterations may run in parallel, and the state of the loop can be monitored and manipulated.

For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>) For(Int32, Int32, Action<Int32,ParallelLoopState>)

執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop in which iterations may run in parallel and the state of the loop can be monitored and manipulated.

public:
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, Action<int, System::Threading::Tasks::ParallelLoopState ^> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (int fromInclusive, int toExclusive, Action<int,System.Threading.Tasks.ParallelLoopState> body);
static member For : int * int * Action<int, System.Threading.Tasks.ParallelLoopState> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For (fromInclusive As Integer, toExclusive As Integer, body As Action(Of Integer, ParallelLoopState)) As ParallelLoopResult

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

body
Action<Int32,ParallelLoopState>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

範例

下列範例會以平行方式執行迴圈的最多 100 個反覆項目。The following example executes up to 100 iterations of a loop in parallel. 從 1 到 1000 毫秒之間的隨機間隔就會暫停每個反覆項目。Each iteration pauses for a random interval from 1 to 1,000 milliseconds. 隨機產生的值會決定迴圈的反覆項目上ParallelLoopState.Break呼叫方法。A randomly generated value determines on which iteration of the loop the ParallelLoopState.Break method is called. 如輸出所範例所示,其索引大於任何反覆項目ParallelLoopState.LowestBreakIteration呼叫後面的屬性值開始ParallelLoopState.Break方法。As the output from the example shows, no iterations whose index is greater than the ParallelLoopState.LowestBreakIteration property value start after the call to the ParallelLoopState.Break method.

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

public class Example
{
   public static void Main()
   {
      var rnd = new Random();
      int breakIndex = rnd.Next(1, 11);
      Nullable<long> lowest = new Nullable<long>();

      Console.WriteLine("Will call Break at iteration {0}\n",
                        breakIndex);

      var result = Parallel.For(1, 101, (i, state) => {
                                            Console.WriteLine("Beginning iteration {0}", i);
                                            int delay;
                                            Monitor.Enter(rnd);
                                               delay = rnd.Next(1, 1001);
                                            Monitor.Exit(rnd);
                                            Thread.Sleep(delay);
                                            
                                            if (state.ShouldExitCurrentIteration) {
                                               if (state.LowestBreakIteration < i)
                                                  return;
                                            }

                                            if (i == breakIndex) {
                                               Console.WriteLine("Break in iteration {0}", i);
                                               state.Break();
                                               if (state.LowestBreakIteration.HasValue)
                                                  if (lowest < state.LowestBreakIteration)
                                                     lowest = state.LowestBreakIteration;
                                                  else
                                                     lowest = state.LowestBreakIteration;
                                            }

                                            Console.WriteLine("Completed iteration {0}", i);
                                       });
         if (lowest.HasValue)
            Console.WriteLine("\nLowest Break Iteration: {0}", lowest);
         else
            Console.WriteLine("\nNo lowest break iteration.");
   }
}
// The example displays output like the following:
//       Will call Break at iteration 8
//
//       Beginning iteration 1
//       Beginning iteration 13
//       Beginning iteration 97
//       Beginning iteration 25
//       Beginning iteration 49
//       Beginning iteration 37
//       Beginning iteration 85
//       Beginning iteration 73
//       Beginning iteration 61
//       Completed iteration 85
//       Beginning iteration 86
//       Completed iteration 61
//       Beginning iteration 62
//       Completed iteration 86
//       Beginning iteration 87
//       Completed iteration 37
//       Beginning iteration 38
//       Completed iteration 38
//       Beginning iteration 39
//       Completed iteration 25
//       Beginning iteration 26
//       Completed iteration 26
//       Beginning iteration 27
//       Completed iteration 73
//       Beginning iteration 74
//       Completed iteration 62
//       Beginning iteration 63
//       Completed iteration 39
//       Beginning iteration 40
//       Completed iteration 40
//       Beginning iteration 41
//       Completed iteration 13
//       Beginning iteration 14
//       Completed iteration 1
//       Beginning iteration 2
//       Completed iteration 97
//       Beginning iteration 98
//       Completed iteration 49
//       Beginning iteration 50
//       Completed iteration 87
//       Completed iteration 27
//       Beginning iteration 28
//       Completed iteration 50
//       Beginning iteration 51
//       Beginning iteration 88
//       Completed iteration 14
//       Beginning iteration 15
//       Completed iteration 15
//       Completed iteration 2
//       Beginning iteration 3
//       Beginning iteration 16
//       Completed iteration 63
//       Beginning iteration 64
//       Completed iteration 74
//       Beginning iteration 75
//       Completed iteration 41
//       Beginning iteration 42
//       Completed iteration 28
//       Beginning iteration 29
//       Completed iteration 29
//       Beginning iteration 30
//       Completed iteration 98
//       Beginning iteration 99
//       Completed iteration 64
//       Beginning iteration 65
//       Completed iteration 42
//       Beginning iteration 43
//       Completed iteration 88
//       Beginning iteration 89
//       Completed iteration 51
//       Beginning iteration 52
//       Completed iteration 16
//       Beginning iteration 17
//       Completed iteration 43
//       Beginning iteration 44
//       Completed iteration 44
//       Beginning iteration 45
//       Completed iteration 99
//       Beginning iteration 4
//       Completed iteration 3
//       Beginning iteration 8
//       Completed iteration 4
//       Beginning iteration 5
//       Completed iteration 52
//       Beginning iteration 53
//       Completed iteration 75
//       Beginning iteration 76
//       Completed iteration 76
//       Beginning iteration 77
//       Completed iteration 65
//       Beginning iteration 66
//       Completed iteration 5
//       Beginning iteration 6
//       Completed iteration 89
//       Beginning iteration 90
//       Completed iteration 30
//       Beginning iteration 31
//       Break in iteration 8
//       Completed iteration 8
//       Completed iteration 6
//       Beginning iteration 7
//       Completed iteration 7
//
//       Lowest Break Iteration: 8
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim rnd As New Random()
      Dim breakIndex As Integer = rnd.Next(1, 11)
      Dim lowest As New Nullable(Of Long)()

      Console.WriteLine("Will call Break at iteration {0}", breakIndex)
      Console.WriteLine()

      Dim result = Parallel.For(1, 101, Sub(i, state)
                                            Console.WriteLine("Beginning iteration {0}", i)
                                            Dim delay As Integer
                                            Monitor.Enter(rnd)
                                               delay = rnd.Next(1, 1001)
                                            Monitor.Exit(rnd)
                                            Thread.Sleep(delay)

                                            If state.ShouldExitCurrentIteration Then
                                               If state.LowestBreakIteration < i Then
                                                  Return
                                               End If
                                            End If

                                            If i = breakIndex Then
                                               Console.WriteLine("Break in iteration {0}", i)
                                               state.Break()
                                               If state.LowestBreakIteration.HasValue Then
                                                  If lowest < state.LowestBreakIteration Then
                                                     lowest = state.LowestBreakIteration
                                                  Else
                                                     lowest = state.LowestBreakIteration
                                                  End If
                                               End If
                                            End If

                                            Console.WriteLine("Completed iteration {0}", i)
                                       End Sub )
         Console.WriteLine()
         If lowest.HasValue Then
            Console.WriteLine("Lowest Break Iteration: {0}", lowest)
         Else
            Console.WriteLine("No lowest break iteration.")
         End If
   End Sub
End Module
' The example displays output like the following:
'       Will call Break at iteration 8
'
'       Beginning iteration 1
'       Beginning iteration 13
'       Beginning iteration 97
'       Beginning iteration 25
'       Beginning iteration 49
'       Beginning iteration 37
'       Beginning iteration 85
'       Beginning iteration 73
'       Beginning iteration 61
'       Completed iteration 85
'       Beginning iteration 86
'       Completed iteration 61
'       Beginning iteration 62
'       Completed iteration 86
'       Beginning iteration 87
'       Completed iteration 37
'       Beginning iteration 38
'       Completed iteration 38
'       Beginning iteration 39
'       Completed iteration 25
'       Beginning iteration 26
'       Completed iteration 26
'       Beginning iteration 27
'       Completed iteration 73
'       Beginning iteration 74
'       Completed iteration 62
'       Beginning iteration 63
'       Completed iteration 39
'       Beginning iteration 40
'       Completed iteration 40
'       Beginning iteration 41
'       Completed iteration 13
'       Beginning iteration 14
'       Completed iteration 1
'       Beginning iteration 2
'       Completed iteration 97
'       Beginning iteration 98
'       Completed iteration 49
'       Beginning iteration 50
'       Completed iteration 87
'       Completed iteration 27
'       Beginning iteration 28
'       Completed iteration 50
'       Beginning iteration 51
'       Beginning iteration 88
'       Completed iteration 14
'       Beginning iteration 15
'       Completed iteration 15
'       Completed iteration 2
'       Beginning iteration 3
'       Beginning iteration 16
'       Completed iteration 63
'       Beginning iteration 64
'       Completed iteration 74
'       Beginning iteration 75
'       Completed iteration 41
'       Beginning iteration 42
'       Completed iteration 28
'       Beginning iteration 29
'       Completed iteration 29
'       Beginning iteration 30
'       Completed iteration 98
'       Beginning iteration 99
'       Completed iteration 64
'       Beginning iteration 65
'       Completed iteration 42
'       Beginning iteration 43
'       Completed iteration 88
'       Beginning iteration 89
'       Completed iteration 51
'       Beginning iteration 52
'       Completed iteration 16
'       Beginning iteration 17
'       Completed iteration 43
'       Beginning iteration 44
'       Completed iteration 44
'       Beginning iteration 45
'       Completed iteration 99
'       Beginning iteration 4
'       Completed iteration 3
'       Beginning iteration 8
'       Completed iteration 4
'       Beginning iteration 5
'       Completed iteration 52
'       Beginning iteration 53
'       Completed iteration 75
'       Beginning iteration 76
'       Completed iteration 76
'       Beginning iteration 77
'       Completed iteration 65
'       Beginning iteration 66
'       Completed iteration 5
'       Beginning iteration 6
'       Completed iteration 89
'       Beginning iteration 90
'       Completed iteration 30
'       Beginning iteration 31
'       Break in iteration 8
'       Completed iteration 8
'       Completed iteration 6
'       Beginning iteration 7
'       Completed iteration 7
'
'       Lowest Break Iteration: 8

因為迴圈的反覆項目仍可能同時執行的時機ParallelLoopState.Break呼叫方法,每個反覆項目會呼叫ParallelLoopState.ShouldExitCurrentIteration屬性,以檢查是否已呼叫另一個反覆項目ParallelLoopState.Break方法。Because iterations of the loop are still likely to be executing when the ParallelLoopState.Break method is called, each iteration calls the ParallelLoopState.ShouldExitCurrentIteration property to check whether another iteration has called the ParallelLoopState.Break method. 屬性值是否true,在反覆項目值檢查ParallelLoopState.LowestBreakIteration屬性以及其是否大於目前的反覆項目的索引值,會立即傳回。If the property value is true, the iteration checks the value of the ParallelLoopState.LowestBreakIteration property and, if it is greater than the current iteration's index value, returns immediately.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這會提供兩個引數:It is provided with two arguments:

  • Int32表示反覆項目計數的值。An Int32 value that represents the iteration count.

  • AParallelLoopState可用來提早脫離迴圈的執行個體。A ParallelLoopState instance that can be used to break out of the loop prematurely. ParallelLoopState編譯器所建立物件; 無法在使用者程式碼中執行個體化。The ParallelLoopState object is created by the compiler; it cannot be instantiated in user code.

呼叫Break方法會通知for之後目前的反覆項目沒有要執行的作業。Calling the Break method informs the for operation that iterations after the current one don't have to execute. 但目前所有的反覆項目將仍然有一個要執行,如果它們還沒有這麼做。However, all iterations before the current one will still have to be executed if they haven't already.

因此,呼叫Break類似於使用符號內的作業傳統for等語言中的迴圈C#,但它不是完美的替代:比方說,則無法保證該反覆項目之後目前絕對不會執行。Therefore, calling Break is similar to using a break operation within a conventional for loop in a language like C#, but it is not a perfect substitute: For example, there is no guarantee that iterations after the current one will definitely not execute.

如果目前不需要之前,請執行所有的反覆項目,使用Stop方法,而不是使用BreakIf executing all iterations before the current one is not necessary, use the Stop method instead of using Break. 呼叫Stop會通知for迴圈,它可能會放棄所有剩餘反覆項目,不論它們位之前或之後的目前反覆項目,因為所有所需的工作將已經完成。Calling Stop informs the for loop that it may abandon all remaining iterations, regardless of whether they're before or after the current iteration, because all required work will have already been completed. 不過,隨著使用Break,不有哪些其他反覆項目將不會執行任何保證。However, as with Break, there are no guarantees regarding which other iterations will not execute.

如果迴圈已提前結束,ParallelLoopResult傳回的結構將會包含迴圈的完成的相關資訊。If a loop is ended prematurely, the ParallelLoopResult structure that is returned will contain relevant information about the loop's completion.

如果fromInclusive大於或等於toExclusive,方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, the method returns immediately without performing any iterations.

另請參閱

For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>) For(Int32, Int32, Action<Int32>)

執行可平行執行反覆項目的 for 迴圈。Executes a for loop in which iterations may run in parallel.

public:
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, Action<int> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (int fromInclusive, int toExclusive, Action<int> body);
static member For : int * int * Action<int> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For (fromInclusive As Integer, toExclusive As Integer, body As Action(Of Integer)) As ParallelLoopResult

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

body
Action<Int32>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

範例

下列範例會使用For值 100 的引動過程,會產生隨機位元組之委派的方法,並計算其總和。The following example uses the For method for 100 invocations of a delegate that generates random byte values and computes their sum.

using System;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      ParallelLoopResult result = Parallel.For(0, 100, ctr => { Random rnd = new Random(ctr * 100000);
                                                                Byte[] bytes = new Byte[100];
                                                                rnd.NextBytes(bytes);
                                                                int sum = 0;
                                                                foreach(var byt in bytes)
                                                                    sum += byt;
                                                                Console.WriteLine("Iteration {0,2}: {1:N0}", ctr, sum);
                                                              });
      Console.WriteLine("Result: {0}", result.IsCompleted ? "Completed Normally" : 
                                                             String.Format("Completed to {0}", result.LowestBreakIteration));
   }
}
// The following is a portion of the output displayed by the example:
//       Iteration  0: 12,509
//       Iteration 50: 12,823
//       Iteration 51: 11,275
//       Iteration 52: 12,531
//       Iteration  1: 13,007
//       Iteration 53: 13,799
//       Iteration  4: 12,945
//       Iteration  2: 13,246
//       Iteration 54: 13,008
//       Iteration 55: 12,727
//       Iteration 56: 13,223
//       Iteration 57: 13,717
//       Iteration  5: 12,679
//       Iteration  3: 12,455
//       Iteration 58: 12,669
//       Iteration 59: 11,882
//       Iteration  6: 13,167
//       ...
//       Iteration 92: 12,275
//       Iteration 93: 13,282
//       Iteration 94: 12,745
//       Iteration 95: 11,957
//       Iteration 96: 12,455
//       Result: Completed Normally
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim result As ParallelLoopResult = Parallel.For(0, 100, Sub(ctr)
                                                                 Dim rnd As New Random(ctr * 100000)
                                                                 Dim bytes(99) As Byte
                                                                 rnd.NextBytes(bytes)
                                                                 Dim sum As Integer
                                                                 For Each byt In bytes
                                                                    sum += byt
                                                                 Next
                                                                 Console.WriteLine("Iteration {0,2}: {1:N0}", ctr, sum)
                                                              End Sub)
      Console.WriteLine("Result: {0}", If(result.IsCompleted, "Completed Normally", 
                                                             String.Format("Completed to {0}", result.LowestBreakIteration)))
   End Sub
End Module
' The following is a portion of the output displayed by the example:
'       Iteration  0: 12,509
'       Iteration 50: 12,823
'       Iteration 51: 11,275
'       Iteration 52: 12,531
'       Iteration  1: 13,007
'       Iteration 53: 13,799
'       Iteration  4: 12,945
'       Iteration  2: 13,246
'       Iteration 54: 13,008
'       Iteration 55: 12,727
'       Iteration 56: 13,223
'       Iteration 57: 13,717
'       Iteration  5: 12,679
'       Iteration  3: 12,455
'       Iteration 58: 12,669
'       Iteration 59: 11,882
'       Iteration  6: 13,167
'       ...
'       Iteration 92: 12,275
'       Iteration 93: 13,282
'       Iteration 94: 12,745
'       Iteration 95: 11,957
'       Iteration 96: 12,455
'       Result: Completed Normally

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 它隨附的反覆項目計數 (Int32) 做為參數。It is provided with the iteration count (Int32) as a parameter.

如果fromInclusive大於或等於toExclusive,方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, the method returns immediately without performing any iterations.

另請參閱

For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>) For(Int64, Int64, Action<Int64,ParallelLoopState>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes in which iterations may run in parallel and the state of the loop can be monitored and manipulated.

public:
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, Action<long, System::Threading::Tasks::ParallelLoopState ^> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (long fromInclusive, long toExclusive, Action<long,System.Threading.Tasks.ParallelLoopState> body);
static member For : int64 * int64 * Action<int64, System.Threading.Tasks.ParallelLoopState> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For (fromInclusive As Long, toExclusive As Long, body As Action(Of Long, ParallelLoopState)) As ParallelLoopResult

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

body
Action<Int64,ParallelLoopState>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

ParallelLoopResult 結構,其中包含迴圈已完成部分的相關資訊。A ParallelLoopResult structure that contains information on what portion of the loop completed.

例外狀況

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int64),和ParallelLoopState可用來提早脫離迴圈的執行個體。It is provided with the following parameters: the iteration count (Int64), and a ParallelLoopState instance that may be used to break out of the loop prematurely.

呼叫Break方法會通知for之後目前的反覆項目不必執行,但所有的反覆項目之前目前執行的作業。Calling the Break method informs the for operation that iterations after the current one don't have to be executed, but all iterations before the current one do.

因此,呼叫中斷,類似於使用符號內的作業傳統for等語言中的迴圈C#,但它不是完美的替代:比方說,則無法保證該反覆項目之後目前絕對不會執行。Therefore, calling Break is similar to using a break operation within a conventional for loop in a language like C#, but it is not a perfect substitute: For example, there is no guarantee that iterations after the current one will definitely not execute.

如果目前不需要之前,請執行所有的反覆項目,使用Stop方法,而不是使用BreakIf executing all iterations before the current one is not necessary, use the Stop method instead of using Break. 呼叫Stop會通知for迴圈,它可能會放棄所有剩餘反覆項目,不論它們位之前或之後的目前反覆項目,因為所有所需的工作將已經完成。Calling Stop informs the for loop that it may abandon all remaining iterations, regardless of whether they're before or after the current iteration, because all required work will have already been completed. 不過,隨著使用Break,不有哪些其他反覆項目將不會執行任何保證。However, as with Break, there are no guarantees regarding which other iterations will not execute.

如果迴圈已提前結束,ParallelLoopResult傳回的結構將會包含迴圈的完成的相關資訊。If a loop is ended prematurely, the ParallelLoopResult structure that is returned will contain relevant information about the loop's completion.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

另請參閱

For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>) For(Int64, Int64, Action<Int64>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目。Executes a for loop with 64-bit indexes in which iterations may run in parallel.

public:
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, Action<long> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (long fromInclusive, long toExclusive, Action<long> body);
static member For : int64 * int64 * Action<int64> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For (fromInclusive As Long, toExclusive As Long, body As Action(Of Long)) As ParallelLoopResult

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

body
Action<Int64>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 它隨附的反覆項目計數 (Int64) 做為參數。It is provided with the iteration count (Int64) as a parameter.

如果fromInclusive大於或等於toExclusive,方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, the method returns immediately without performing any iterations.

另請參閱

For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>) For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>) For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>)

執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

public:
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Action<int, System::Threading::Tasks::ParallelLoopState ^> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (int fromInclusive, int toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Action<int,System.Threading.Tasks.ParallelLoopState> body);
static member For : int * int * System.Threading.Tasks.ParallelOptions * Action<int, System.Threading.Tasks.ParallelLoopState> -> System.Threading.Tasks.ParallelLoopResult

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

body
Action<Int32,ParallelLoopState>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

body 引數為 nullThe body argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int32),和ParallelLoopState可用來提早脫離迴圈的執行個體。It is provided with the following parameters: the iteration count (Int32), and a ParallelLoopState instance that may be used to break out of the loop prematurely.

如果fromInclusive大於或等於toExclusive,方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, the method returns immediately without performing any iterations.

另請參閱

For(Int32, Int32, ParallelOptions, Action<Int32>) For(Int32, Int32, ParallelOptions, Action<Int32>) For(Int32, Int32, ParallelOptions, Action<Int32>)

執行 for 迴圈,其中可以平行執行反覆項目,還可以設定迴圈選項。Executes a for loop in which iterations may run in parallel and loop options can be configured.

public:
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Action<int> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (int fromInclusive, int toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Action<int> body);
static member For : int * int * System.Threading.Tasks.ParallelOptions * Action<int> -> System.Threading.Tasks.ParallelLoopResult

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

body
Action<Int32>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

body 引數為 nullThe body argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

範例

下列範例示範如何取消平行迴圈:The following example shows how to cancel a parallel loop:



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

class ParallelForCancellation
{
    // Demonstrated features:
    //		CancellationTokenSource
    // 		Parallel.For()
    //		ParallelOptions
    //		ParallelLoopResult
    // Expected results:
    // 		An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
    //		The order of execution of the iterations is undefined.
    //		The iteration when i=2 cancels the loop.
    //		Some iterations may bail out or not start at all; because they are temporally executed in unpredictable order, 
    //          it is impossible to say which will start/complete and which won't.
    //		At the end, an OperationCancelledException is surfaced.
    // Documentation:
    //		http://msdn.microsoft.com/library/system.threading.cancellationtokensource(VS.100).aspx
    static void CancelDemo()
    {
        CancellationTokenSource cancellationSource = new CancellationTokenSource();
        ParallelOptions options = new ParallelOptions();
        options.CancellationToken = cancellationSource.Token;

        try
        {
            ParallelLoopResult loopResult = Parallel.For(
                    0,
                    10,
                    options,
                    (i, loopState) =>
                    {
                        Console.WriteLine("Start Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i);

                        // Simulate a cancellation of the loop when i=2
                        if (i == 2)
                        {
                            cancellationSource.Cancel();
                        }

                        // Simulates a long execution
                        for (int j = 0; j < 10; j++)
                        {
                            Thread.Sleep(1 * 200);

                            // check to see whether or not to continue
                            if (loopState.ShouldExitCurrentIteration) return;
                        }

                        Console.WriteLine("Finish Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i);
                    }
                );

            if (loopResult.IsCompleted)
            {
                Console.WriteLine("All iterations completed successfully. THIS WAS NOT EXPECTED.");
            }
        }
        // No exception is expected in this example, but if one is still thrown from a task,
        // it will be wrapped in AggregateException and propagated to the main thread.
        catch (AggregateException e)
        {
            Console.WriteLine("Parallel.For has thrown an AggregateException. THIS WAS NOT EXPECTED.\n{0}", e);
        }
        // Catching the cancellation exception
        catch (OperationCanceledException e)
        {
            Console.WriteLine("An iteration has triggered a cancellation. THIS WAS EXPECTED.\n{0}", e.ToString());
        }
        finally
        {
           cancellationSource.Dispose();
        }
    }
}
Imports System.Threading
Imports System.Threading.Tasks

Module LoopCancellation
    ' Demonstrated features:
    '   CancellationTokenSource
    '   Parallel.For()
    '   ParallelOptions
    '   ParallelLoopResult
    ' Expected results:
    '   An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
    '   The order of execution of the iterations is undefined.
    '   The iteration when i=2 cancels the loop.
    '   Some iterations may bail out or not start at all; because they are temporally executed in unpredictable order, 
    '      it is impossible to say which will start/complete and which won't.
    '   At the end, an OperationCancelledException is surfaced.
    ' Documentation:
    '   http://msdn.microsoft.com/library/system.threading.cancellationtokensource(VS.100).aspx
    Private Sub Main()
        Dim cancellationSource As New CancellationTokenSource()
        Dim options As New ParallelOptions()
        options.CancellationToken = cancellationSource.Token

        Try
            Dim loopResult As ParallelLoopResult = _
                Parallel.For(0, 10, options, Sub(i, loopState)
                                                 Console.WriteLine("Start Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i)

                                                 ' Simulate a cancellation of the loop when i=2
                                                 If i = 2 Then
                                                     cancellationSource.Cancel()
                                                 End If

                                                 ' Simulates a long execution
                                                 For j As Integer = 0 To 9
                                                     Thread.Sleep(1 * 200)

                                                     ' check to see whether or not to continue
                                                     If loopState.ShouldExitCurrentIteration Then
                                                         Exit Sub
                                                     End If
                                                 Next

                                                 Console.WriteLine("Finish Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i)
                                             End Sub)

            If loopResult.IsCompleted Then
                Console.WriteLine("All iterations completed successfully. THIS WAS NOT EXPECTED.")
            End If
        Catch e As AggregateException
            ' No exception is expected in this example, but if one is still thrown from a task,
            ' it will be wrapped in AggregateException and propagated to the main thread.
            Console.WriteLine("An action has thrown an AggregateException. THIS WAS NOT EXPECTED." & vbLf & "{0}", e)
        Catch e As OperationCanceledException
            ' Catching the cancellation exception
            Console.WriteLine("An iteration has triggered a cancellation. THIS WAS EXPECTED." & vbLf & "{0}", e)
        Finally
            cancellationSource.Dispose()
        End Try
    End Sub
End Module

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 它隨附的反覆項目計數 (Int32) 做為參數。It is provided with the iteration count (Int32) as a parameter.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

另請參閱

For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>) For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>) For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

public:
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Action<long, System::Threading::Tasks::ParallelLoopState ^> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (long fromInclusive, long toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Action<long,System.Threading.Tasks.ParallelLoopState> body);
static member For : int64 * int64 * System.Threading.Tasks.ParallelOptions * Action<int64, System.Threading.Tasks.ParallelLoopState> -> System.Threading.Tasks.ParallelLoopResult

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

body
Action<Int64,ParallelLoopState>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

body 引數為 nullThe body argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

範例

下列範例示範如何使用Parallel.For方法使用ParallelOptions物件:The following example shows how to use the Parallel.For method with a ParallelOptions object:

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


class ParallelOptionsDemo
{
    // Demonstrated features:
    // 		Parallel.For()
    //		ParallelOptions
    // Expected results:
    // 		An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
    //		The order of execution of the iterations is undefined.
    //		Verify that no more than two threads have been used for the iterations.
    // Documentation:
    //		http://msdn.microsoft.com/library/system.threading.tasks.parallel.for(VS.100).aspx
    static void Main()
    {
        ParallelOptions options = new ParallelOptions();
        options.MaxDegreeOfParallelism = 2; // -1 is for unlimited. 1 is for sequential.

        try
        {
            Parallel.For(
                    0,
                    9,
                    options,
                    (i) =>
                    {
                        Console.WriteLine("Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i);
                    }
                );

        }
        // No exception is expected in this example, but if one is still thrown from a task,
        // it will be wrapped in AggregateException and propagated to the main thread.
        catch (AggregateException e)
        {
            Console.WriteLine("Parallel.For has thrown the following (unexpected) exception:\n{0}", e);
        }
    }

}


Imports System.Threading
Imports System.Threading.Tasks


Module ParallelForDemo

    ' Demonstrated features:
    '   Parallel.For()
    '   ParallelOptions
    ' Expected results:
    '   An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
    '   The order of execution of the iterations is undefined.
    '   Verify that no more than two threads have been used for the iterations.
    ' Documentation:
    '   http://msdn.microsoft.com/library/system.threading.tasks.parallel.for(VS.100).aspx
    Sub Main()
        Dim options As New ParallelOptions()
        options.MaxDegreeOfParallelism = 2 ' -1 is for unlimited. 1 is for sequential.
        Try
            Parallel.For(0, 9, options, Sub(i)
                                            Console.WriteLine("Thread={0}, i={1}", Thread.CurrentThread.ManagedThreadId, i)

                                        End Sub)
        Catch e As AggregateException
            ' No exception is expected in this example, but if one is still thrown from a task,
            ' it will be wrapped in AggregateException and propagated to the main thread.
            Console.WriteLine("Parallel.For has thrown the following (unexpected) exception:" & vbLf & "{0}", e)
        End Try
    End Sub

End Module

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int64),和ParallelLoopState可用來提早脫離迴圈的執行個體。It is provided with the following parameters: the iteration count (Int64), and a ParallelLoopState instance that may be used to break out of the loop prematurely.

如果fromInclusive大於或等於toExclusive,方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, the method returns immediately without performing any iterations.

另請參閱

For(Int64, Int64, ParallelOptions, Action<Int64>) For(Int64, Int64, ParallelOptions, Action<Int64>) For(Int64, Int64, ParallelOptions, Action<Int64>)

使用 64 位元索引執行 for 迴圈,其中可以平行執行反覆項目,還可以設定迴圈選項。Executes a for loop with 64-bit indexes in which iterations may run in parallel and loop options can be configured.

public:
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Action<long> ^ body);
public static System.Threading.Tasks.ParallelLoopResult For (long fromInclusive, long toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Action<long> body);
static member For : int64 * int64 * System.Threading.Tasks.ParallelOptions * Action<int64> -> System.Threading.Tasks.ParallelLoopResult

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

body
Action<Int64>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

body 引數為 nullThe body argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

範例

下列範例示範如何使用ParallelOptions來指定自訂的工作排程器:The following example shows how to use ParallelOptions to specify a custom task scheduler:

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

class ParallelSchedulerDemo2
{
        // Demonstrated features:
        //		TaskScheduler
        //      BlockingCollection
        // 		Parallel.For()
        //		ParallelOptions
        // Expected results:
        // 		An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
        //		The TwoThreadTaskScheduler employs 2 threads on which iterations may be executed in a random order.
        //		Thus a scheduler thread may execute multiple iterations.
        // Documentation:
        //		http://msdn.microsoft.com/library/system.threading.tasks.taskscheduler(VS.100).aspx
        //		http://msdn.microsoft.com/library/dd997413(VS.100).aspx
        // More information:
        //		http://blogs.msdn.com/pfxteam/archive/2009/09/22/9898090.aspx
        static void Main()
        {
            ParallelOptions options = new ParallelOptions();

            // Construct and associate a custom task scheduler
            options.TaskScheduler = new TwoThreadTaskScheduler();

            try
            {
                Parallel.For(
                        0,
                        10,
                        options,
                        (i, localState) =>
                        {
                            Console.WriteLine("i={0}, Task={1}, Thread={2}", i, Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
                        }
                    );

            }
            // No exception is expected in this example, but if one is still thrown from a task,
            // it will be wrapped in AggregateException and propagated to the main thread.
            catch (AggregateException e)
            {
                Console.WriteLine("An iteration has thrown an exception. THIS WAS NOT EXPECTED.\n{0}", e);
            }
        }

        // This scheduler schedules all tasks on (at most) two threads
        sealed class TwoThreadTaskScheduler : TaskScheduler, IDisposable
        {
            // The runtime decides how many tasks to create for the given set of iterations, loop options, and scheduler's max concurrency level.
            // Tasks will be queued in this collection
            private BlockingCollection<Task> _tasks = new BlockingCollection<Task>();

            // Maintain an array of threads. (Feel free to bump up _n.)
            private readonly int _n = 2;
            private Thread[] _threads;

            public TwoThreadTaskScheduler()
            {
                _threads = new Thread[_n];

                // Create unstarted threads based on the same inline delegate
                for (int i = 0; i < _n; i++)
                {
                    _threads[i] = new Thread(() =>
                    {
                        // The following loop blocks until items become available in the blocking collection.
                        // Then one thread is unblocked to consume that item.
                        foreach (var task in _tasks.GetConsumingEnumerable())
                        {
                            TryExecuteTask(task);
                        }
                    });

                    // Start each thread
                    _threads[i].IsBackground = true;
                    _threads[i].Start();
                }
            }

            // This method is invoked by the runtime to schedule a task
            protected override void QueueTask(Task task)
            {
                _tasks.Add(task);
            }

            // The runtime will probe if a task can be executed in the current thread.
            // By returning false, we direct all tasks to be queued up.
            protected override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)
            {
                return false;
            }

            public override int MaximumConcurrencyLevel { get { return _n; } }

            protected override IEnumerable<Task> GetScheduledTasks()
            {
                return _tasks.ToArray();
            }

            // Dispose is not thread-safe with other members.
            // It may only be used when no more tasks will be queued
            // to the scheduler.  This implementation will block
            // until all previously queued tasks have completed.
            public void Dispose()
            {
                if (_threads != null)
                {
                    _tasks.CompleteAdding();

                    for (int i = 0; i < _n; i++)
                    {
                        _threads[i].Join();
                        _threads[i] = null;
                    }
                    _threads = null;
                    _tasks.Dispose();
                    _tasks = null;
                }
            }
        

    }
}
Imports System.Collections.Concurrent
Imports System.Threading
Imports System.Threading.Tasks
Module SchedulerDemo
    ' Demonstrated features:
    '   TaskScheduler
    '   BlockingCollection
    '   Parallel.For()
    '   ParallelOptions
    ' Expected results:
    '   An iteration for each argument value (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is executed.
    '   The TwoThreadTaskScheduler employs 2 threads on which iterations may be executed in a random order.
    '   A task is internally created for each thread of the task scheduler (plus an aditional internal task).
    '	Thus a scheduler thread may execute multiple iterations.
    ' Documentation:
    '   http://msdn.microsoft.com/library/system.threading.tasks.taskscheduler(VS.100).aspx
    '   http://msdn.microsoft.com/library/dd997413(VS.100).aspx
    ' More information:
    '   http://blogs.msdn.com/pfxteam/archive/2009/09/22/9898090.aspx
    Sub Main()
        Dim options As New ParallelOptions()

        ' Construct and associate a custom task scheduler
        options.TaskScheduler = New TwoThreadTaskScheduler()

        Try
            Parallel.For(0, 10, options, Sub(i, localState)
                                             Console.WriteLine("i={0}, Task={1}, Thread={2}", i, Task.CurrentId, Thread.CurrentThread.ManagedThreadId)

                                         End Sub)
        Catch e As AggregateException
            ' No exception is expected in this example, but if one is still thrown from a task,
            ' it will be wrapped in AggregateException and propagated to the main thread.
            Console.WriteLine("An iteration has thrown an exception. THIS WAS NOT EXPECTED." & vbLf & "{0}", e)
        End Try
    End Sub

    ' This scheduler schedules all tasks on (at most) two threads
    Private NotInheritable Class TwoThreadTaskScheduler
        Inherits TaskScheduler
        Implements IDisposable
        ' The runtime decides how many tasks to create for the given set of iterations, loop options, and scheduler's max concurrency level.
        ' Tasks will be queued in this collection
        Private _tasks As New BlockingCollection(Of Task)()

        ' Maintain an array of threads. (Feel free to bump up _n.)
        Private ReadOnly _n As Integer = 2
        Private _threads As Thread()

        Public Sub New()
            _threads = New Thread(_n - 1) {}

            ' Create unstarted threads based on the same inline delegate
            For i As Integer = 0 To _n - 1
                _threads(i) = New Thread(Sub()
                                             ' The following loop blocks until items become available in the blocking collection.
                                             ' Then one thread is unblocked to consume that item.
                                             For Each task In _tasks.GetConsumingEnumerable()
                                                 TryExecuteTask(task)
                                             Next
                                         End Sub)

                ' Start each thread
                _threads(i).IsBackground = True
                _threads(i).Start()
            Next
        End Sub

        ' This method is invoked by the runtime to schedule a task
        Protected Overloads Overrides Sub QueueTask(ByVal task As Task)
            _tasks.Add(task)
        End Sub

        ' The runtime will probe if a task can be executed in the current thread.
        ' By returning false, we direct all tasks to be queued up.
        Protected Overloads Overrides Function TryExecuteTaskInline(ByVal task As Task, ByVal taskWasPreviouslyQueued As Boolean) As Boolean
            Return False
        End Function

        Public Overloads Overrides ReadOnly Property MaximumConcurrencyLevel() As Integer
            Get
                Return _n
            End Get
        End Property

        Protected Overloads Overrides Function GetScheduledTasks() As IEnumerable(Of Task)
            Return _tasks.ToArray()
        End Function

        ' Dispose is not thread-safe with other members.
        ' It may only be used when no more tasks will be queued
        ' to the scheduler. This implementation will block
        ' until all previously queued tasks have completed.
        Public Sub Dispose() Implements IDisposable.Dispose
            If _threads IsNot Nothing Then
                _tasks.CompleteAdding()

                For i As Integer = 0 To _n - 1
                    _threads(i).Join()
                    _threads(i) = Nothing
                Next
                _threads = Nothing
                _tasks.Dispose()
                _tasks = Nothing
            End If
        End Sub
    End Class

End Module

備註

支援 64 位元索引。Supports 64-bit indexes. body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 它隨附的反覆項目計數 (Int64) 做為參數。It is provided with the iteration count (Int64) as a parameter.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

另請參閱

For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用 64 位元索引和執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes and thread-local data in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

public:
generic <typename TLocal>
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Func<TLocal> ^ localInit, Func<long, System::Threading::Tasks::ParallelLoopState ^, TLocal, TLocal> ^ body, Action<TLocal> ^ localFinally);
public static System.Threading.Tasks.ParallelLoopResult For<TLocal> (long fromInclusive, long toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Func<TLocal> localInit, Func<long,System.Threading.Tasks.ParallelLoopState,TLocal,TLocal> body, Action<TLocal> localFinally);
static member For : int64 * int64 * System.Threading.Tasks.ParallelOptions * Func<'Local> * Func<int64, System.Threading.Tasks.ParallelLoopState, 'Local, 'Local> * Action<'Local> -> System.Threading.Tasks.ParallelLoopResult

類型參數

TLocal

執行緒區域資料的類型。The type of the thread-local data.

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

localInit
Func<TLocal>

函式委派,會針對每個執行緒的本機資料執行起始狀態。The function delegate that returns the initial state of the local data for each thread.

body
Func<Int64,ParallelLoopState,TLocal,TLocal>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

localFinally
Action<TLocal>

委派,會針對每個執行緒的本機狀態執行最終動作。The delegate that performs a final action on the local state of each thread.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

body 引數為 nullThe body argument is null.

-或--or- localInit 引數為 nullThe localInit argument is null.

-或--or- localFinally 引數為 nullThe localFinally argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int64)、ParallelLoopState可用來提前結束,脫離迴圈的執行個體,且可能在相同執行緒執行的反覆項目之間共用某些本機狀態。It is provided with the following parameters: the iteration count (Int64), a ParallelLoopState instance that may be used to break out of the loop prematurely, and some local state that may be shared amongst iterations that execute on the same thread.

localInit叫用委派一次的每個執行緒都參與迴圈的執行,並傳回每個執行緒的初始本機狀態。The localInit delegate is invoked once for each thread that participates in the loop's execution and returns the initial local state for each of those threads. 這些初始狀態會傳遞至第一個body引動過程上每個執行緒。These initial states are passed to the first body invocations on each thread. 然後,每個後續的內文引動過程傳回可能已修改的狀態值傳遞至下一個主體引動過程。Then, every subsequent body invocation returns a possibly modified state value that is passed to the next body invocation. 最後,在每個執行緒上的最後一個主體引動過程會傳回狀態的值傳遞至localFinally委派。Finally, the last body invocation on each thread returns a state value that is passed to the localFinally delegate. localFinally叫用委派一次每個執行緒上每個執行緒的本機狀態執行最終動作。The localFinally delegate is invoked once per thread to perform a final action on each thread's local state. 這個委派可能會同時叫用上多個執行緒;因此,您必須同步處理任何共用變數的存取權。This delegate might be invoked concurrently on multiple threads; therefore, you must synchronize access to any shared variables.

Parallel.For方法可能會使用更多的工作,比執行緒存留時間內執行,為現有的工作完成,並由新的工作所取代。The Parallel.For method may use more tasks than threads over the lifetime of its execution, as existing tasks complete and are replaced by new tasks. 這可讓基礎TaskScheduler物件有機會新增、 變更或移除服務迴圈的執行緒。This gives the underlying TaskScheduler object the chance to add, change, or remove threads that service the loop.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

另請參閱

For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目、可以設定迴圈選項,還可以監控和操作迴圈的狀態。Executes a for loop with thread-local data in which iterations may run in parallel, loop options can be configured, and the state of the loop can be monitored and manipulated.

public:
generic <typename TLocal>
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, System::Threading::Tasks::ParallelOptions ^ parallelOptions, Func<TLocal> ^ localInit, Func<int, System::Threading::Tasks::ParallelLoopState ^, TLocal, TLocal> ^ body, Action<TLocal> ^ localFinally);
public static System.Threading.Tasks.ParallelLoopResult For<TLocal> (int fromInclusive, int toExclusive, System.Threading.Tasks.ParallelOptions parallelOptions, Func<TLocal> localInit, Func<int,System.Threading.Tasks.ParallelLoopState,TLocal,TLocal> body, Action<TLocal> localFinally);
static member For : int * int * System.Threading.Tasks.ParallelOptions * Func<'Local> * Func<int, System.Threading.Tasks.ParallelLoopState, 'Local, 'Local> * Action<'Local> -> System.Threading.Tasks.ParallelLoopResult

類型參數

TLocal

執行緒區域資料的類型。The type of the thread-local data.

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

parallelOptions
ParallelOptions ParallelOptions ParallelOptions ParallelOptions

物件,設定這個作業的行為。An object that configures the behavior of this operation.

localInit
Func<TLocal>

函式委派,會針對每個工作的本機資料執行起始狀態。The function delegate that returns the initial state of the local data for each task.

body
Func<Int32,ParallelLoopState,TLocal,TLocal>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

localFinally
Action<TLocal>

委派,會針對每個工作的本機狀態執行最終動作。The delegate that performs a final action on the local state of each task.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

body 引數為 nullThe body argument is null.

-或--or- localInit 引數為 nullThe localInit argument is null.

-或--or- localFinally 引數為 nullThe localFinally argument is null.

-或--or- parallelOptions 引數為 nullThe parallelOptions argument is null.

parallelOptions 引數中的 CancellationToken 已取消。The CancellationToken in the parallelOptions argument is canceled.

已處置與 parallelOptions 中的 CancellationTokenSource 相關聯的 CancellationTokenThe CancellationTokenSource associated with the CancellationToken in the parallelOptions has been disposed.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

範例

下列範例會使用執行緒區域變數,以計算許多長時間作業的結果的總和。The following example uses thread-local variables to compute the sum of the results of many lengthy operations. 此範例中會限制為 4 的平行處理原則程度。This example limits the degree of parallelism to four.

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

class ThreadLocalForWithOptions
{
   // The number of parallel iterations to perform.
   const int N = 1000000;

   static void Main()
   {
      // The result of all thread-local computations.
      int result = 0;

      // This example limits the degree of parallelism to four.
      // You might limit the degree of parallelism when your algorithm
      // does not scale beyond a certain number of cores or when you 
      // enforce a particular quality of service in your application.

      Parallel.For(0, N, new ParallelOptions { MaxDegreeOfParallelism = 4 },
         // Initialize the local states
         () => 0,
         // Accumulate the thread-local computations in the loop body
         (i, loop, localState) =>
         {
            return localState + Compute(i);
         },
         // Combine all local states
         localState => Interlocked.Add(ref result, localState)
      );

      // Print the actual and expected results.
      Console.WriteLine("Actual result: {0}. Expected 1000000.", result);
   }

   // Simulates a lengthy operation.
   private static int Compute(int n)
   {
      for (int i = 0; i < 10000; i++) ;
      return 1;
   }
}
Imports System.Threading
Imports System.Threading.Tasks

Module ThreadLocalForWithOptions

   ' The number of parallel iterations to perform.
   Const N As Integer = 1000000

   Sub Main()
      ' The result of all thread-local computations.
      Dim result As Integer = 0

      ' This example limits the degree of parallelism to four.
      ' You might limit the degree of parallelism when your algorithm
      ' does not scale beyond a certain number of cores or when you 
      ' enforce a particular quality of service in your application.

      Parallel.For(0, N, New ParallelOptions With {.MaxDegreeOfParallelism = 4},
         Function()
            ' Initialize the local states 
            Return 0
         End Function,
         Function(i, loopState, localState)
            ' Accumulate the thread-local computations in the loop body
            Return localState + Compute(i)
         End Function,
         Sub(localState)
            ' Combine all local states
            Interlocked.Add(result, localState)
         End Sub
      )

      ' Print the actual and expected results.
      Console.WriteLine("Actual result: {0}. Expected 1000000.", result)
   End Sub

   ' Simulates a lengthy operation.
   Function Compute(ByVal n As Integer) As Integer
      For i As Integer = 0 To 10000
      Next
      Return 1
   End Function
End Module

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int32)、ParallelLoopState可用來提前結束,脫離迴圈的執行個體,且可能在相同工作執行的反覆項目之間共用某些本機狀態。It is provided with the following parameters: the iteration count (Int32), a ParallelLoopState instance that may be used to break out of the loop prematurely, and some local state that may be shared amongst iterations that execute on the same task.

localInit叫用委派一次參與迴圈的執行,並傳回每個這些工作的初始本機狀態每項工作。The localInit delegate is invoked once for each task that participates in the loop's execution and returns the initial local state for each of those tasks. 這些初始狀態會傳遞至第一個body上每個工作引動過程。These initial states are passed to the first body invocations on each task. 然後,每個後續的內文引動過程傳回可能已修改的狀態值傳遞至下一個主體引動過程。Then, every subsequent body invocation returns a possibly modified state value that is passed to the next body invocation. 最後,每個工作上上次的主體引動過程會傳回傳遞至狀態值localFinally委派。Finally, the last body invocation on each task returns a state value that is passed to the localFinally delegate. localFinally叫用委派一次每個工作,每個工作的本機狀態執行最終動作。The localFinally delegate is invoked once per task to perform a final action on each task's local state. 這個委派可能會同時叫用上多個執行緒;因此,您必須同步處理任何共用變數的存取權。This delegate might be invoked concurrently on multiple threads; therefore, you must synchronize access to any shared variables.

Parallel.For方法可能會使用更多的工作,比執行緒存留時間內執行,為現有的工作完成,並由新的工作所取代。The Parallel.For method may use more tasks than threads over the lifetime of its execution, as existing tasks complete and are replaced by new tasks. 這可讓基礎TaskScheduler物件有機會新增、 變更或移除服務迴圈的執行緒。This gives the underlying TaskScheduler object the chance to add, change, or remove threads that service the loop.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

另請參閱

For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with thread-local data in which iterations may run in parallel, and the state of the loop can be monitored and manipulated.

public:
generic <typename TLocal>
 static System::Threading::Tasks::ParallelLoopResult For(int fromInclusive, int toExclusive, Func<TLocal> ^ localInit, Func<int, System::Threading::Tasks::ParallelLoopState ^, TLocal, TLocal> ^ body, Action<TLocal> ^ localFinally);
public static System.Threading.Tasks.ParallelLoopResult For<TLocal> (int fromInclusive, int toExclusive, Func<TLocal> localInit, Func<int,System.Threading.Tasks.ParallelLoopState,TLocal,TLocal> body, Action<TLocal> localFinally);
static member For : int * int * Func<'Local> * Func<int, System.Threading.Tasks.ParallelLoopState, 'Local, 'Local> * Action<'Local> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For(Of TLocal) (fromInclusive As Integer, toExclusive As Integer, localInit As Func(Of TLocal), body As Func(Of Integer, ParallelLoopState, TLocal, TLocal), localFinally As Action(Of TLocal)) As ParallelLoopResult

類型參數

TLocal

執行緒區域資料的類型。The type of the thread-local data.

參數

fromInclusive
Int32 Int32 Int32 Int32

起始索引 (含)。The start index, inclusive.

toExclusive
Int32 Int32 Int32 Int32

要排除的結束索引。The end index, exclusive.

localInit
Func<TLocal>

函式委派,會針對每個工作的本機資料執行起始狀態。The function delegate that returns the initial state of the local data for each task.

body
Func<Int32,ParallelLoopState,TLocal,TLocal>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

localFinally
Action<TLocal>

委派,會針對每個工作的本機狀態執行最終動作。The delegate that performs a final action on the local state of each task.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

body 引數為 nullThe body argument is null.

-或--or- localInit 引數為 nullThe localInit argument is null.

-或--or- localFinally 引數為 nullThe localFinally argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int32)、ParallelLoopState可用來提前結束,脫離迴圈的執行個體,且可能在相同執行緒執行的反覆項目之間共用某些本機狀態。It is provided with the following parameters: the iteration count (Int32), a ParallelLoopState instance that may be used to break out of the loop prematurely, and some local state that may be shared amongst iterations that execute on the same thread.

localInit叫用委派一次參與迴圈的執行,並傳回每個這些工作的初始本機狀態每項工作。The localInit delegate is invoked once for each task that participates in the loop's execution and returns the initial local state for each of those tasks. 這些初始狀態會傳遞至第一個body上每個工作引動過程。These initial states are passed to the first body invocations on each task. 然後,每個後續的內文引動過程傳回可能已修改的狀態值傳遞至下一個主體引動過程。Then, every subsequent body invocation returns a possibly modified state value that is passed to the next body invocation. 最後,每個工作上上次的主體引動過程會傳回傳遞至狀態值localFinally委派。Finally, the last body invocation on each task returns a state value that is passed to the localFinally delegate. localFinally叫用委派一次每個工作,每個工作的本機狀態執行最終動作。The localFinally delegate is invoked once per task to perform a final action on each task's local state. 這個委派可能會同時叫用多個工作;因此,您必須同步處理任何共用變數的存取權。This delegate might be invoked concurrently on multiple tasks; therefore, you must synchronize access to any shared variables.

Parallel.For方法可能會使用更多的工作,比執行緒存留時間內執行,為現有的工作完成,並由新的工作所取代。The Parallel.For method may use more tasks than threads over the lifetime of its execution, as existing tasks complete and are replaced by new tasks. 這可讓基礎TaskScheduler物件有機會新增、 變更或移除服務迴圈的執行緒。This gives the underlying TaskScheduler object the chance to add, change, or remove threads that service the loop.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

如需使用這個方法的範例,請參閱How to:撰寫含有執行緒區域變數的 Parallel.For 迴圈For an example that uses this method, see How to: Write a Parallel.For Loop with Thread-Local Variables.

另請參閱

For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>) For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)

使用 64 位元索引和執行緒區域資料執行 for 迴圈,其中可以平行執行反覆項目,還可以監控和操作迴圈的狀態。Executes a for loop with 64-bit indexes and thread-local data in which iterations may run in parallel, and the state of the loop can be monitored and manipulated.

public:
generic <typename TLocal>
 static System::Threading::Tasks::ParallelLoopResult For(long fromInclusive, long toExclusive, Func<TLocal> ^ localInit, Func<long, System::Threading::Tasks::ParallelLoopState ^, TLocal, TLocal> ^ body, Action<TLocal> ^ localFinally);
public static System.Threading.Tasks.ParallelLoopResult For<TLocal> (long fromInclusive, long toExclusive, Func<TLocal> localInit, Func<long,System.Threading.Tasks.ParallelLoopState,TLocal,TLocal> body, Action<TLocal> localFinally);
static member For : int64 * int64 * Func<'Local> * Func<int64, System.Threading.Tasks.ParallelLoopState, 'Local, 'Local> * Action<'Local> -> System.Threading.Tasks.ParallelLoopResult
Public Shared Function For(Of TLocal) (fromInclusive As Long, toExclusive As Long, localInit As Func(Of TLocal), body As Func(Of Long, ParallelLoopState, TLocal, TLocal), localFinally As Action(Of TLocal)) As ParallelLoopResult

類型參數

TLocal

執行緒區域資料的類型。The type of the thread-local data.

參數

fromInclusive
Int64 Int64 Int64 Int64

起始索引 (含)。The start index, inclusive.

toExclusive
Int64 Int64 Int64 Int64

要排除的結束索引。The end index, exclusive.

localInit
Func<TLocal>

函式委派,會針對每個工作的本機資料執行起始狀態。The function delegate that returns the initial state of the local data for each task.

body
Func<Int64,ParallelLoopState,TLocal,TLocal>

每個反覆項目都會叫用一次的委派。The delegate that is invoked once per iteration.

localFinally
Action<TLocal>

委派,會針對每個工作的本機狀態執行最終動作。The delegate that performs a final action on the local state of each task.

傳回

包含迴圈已完成部分之相關資訊的的結構。A structure that contains information about which portion of the loop completed.

例外狀況

body 引數為 nullThe body argument is null.

-或--or- localInit 引數為 nullThe localInit argument is null.

-或--or- localFinally 引數為 nullThe localFinally argument is null.

在所有執行緒擲回包含所有個別例外狀況的例外狀況。The exception that contains all the individual exceptions thrown on all threads.

備註

body叫用委派一次反覆項目範圍中每個值 (fromInclusivetoExclusive)。The body delegate is invoked once for each value in the iteration range (fromInclusive, toExclusive). 這提供下列參數: 反覆項目計數 (Int64)、ParallelLoopState可用來提前結束,脫離迴圈的執行個體,且可能在相同工作執行的反覆項目之間共用某些本機狀態。It is provided with the following parameters: the iteration count (Int64), a ParallelLoopState instance that may be used to break out of the loop prematurely, and some local state that may be shared amongst iterations that execute on the same task.

localInit叫用委派一次參與迴圈的執行,並傳回每個這些工作的初始本機狀態每項工作。The localInit delegate is invoked once for each task that participates in the loop's execution and returns the initial local state for each of those tasks. 這些初始狀態會傳遞至第一個body上每個工作引動過程。These initial states are passed to the first body invocations on each task. 然後,每個後續的內文引動過程傳回可能已修改的狀態值傳遞至下一個主體引動過程。Then, every subsequent body invocation returns a possibly modified state value that is passed to the next body invocation. 最後,每個工作上上次的主體引動過程會傳回傳遞至狀態值localFinally委派。Finally, the last body invocation on each task returns a state value that is passed to the localFinally delegate. localFinally叫用委派一次每個工作,每個工作的本機狀態執行最終動作。The localFinally delegate is invoked once per task to perform a final action on each task's local state. 這個委派可能會同時叫用多個工作;因此,您必須同步處理任何共用變數的存取權。This delegate might be invoked concurrently on multiple tasks; therefore, you must synchronize access to any shared variables.

Parallel.For方法可能會使用更多的工作,比執行緒存留時間內執行,為現有的工作完成,並由新的工作所取代。The Parallel.For method may use more tasks than threads over the lifetime of its execution, as existing tasks complete and are replaced by new tasks. 這可讓基礎TaskScheduler物件有機會新增、 變更或移除服務迴圈的執行緒。This gives the underlying TaskScheduler object the chance to add, change, or remove threads that service the loop.

如果fromInclusive大於或等於toExclusive,則方法會立即傳回而不執行任何反覆項目。If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.

如需使用這個方法的範例,請參閱How to:撰寫含有執行緒區域變數的 Parallel.For 迴圈For an example that uses this method, see How to: Write a Parallel.For Loop with Thread-Local Variables.

另請參閱

適用於