Parallel.For 方法

定義

命名空間:: System.Threading.Tasks

組件:: mscorlib.dll, System.Threading.Tasks.Parallel.dll

組件:: netstandard.dll, System.Threading.Tasks.Parallel.dll

組件:: System.Threading.Tasks.Parallel.dll

組件:: mscorlib.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

執行 for 一個迴圈，使迭代可以平行執行。

多載

名稱	Description
For(Int32, Int32, Action<Int32,ParallelLoopState>)	執行 `for` 一個迴圈，其中可平行執行迭代，並可監控與操作迴圈狀態。
For(Int32, Int32, Action<Int32>)	執行 `for` 一個迴圈，使迭代可以平行執行。
For(Int64, Int64, Action<Int64,ParallelLoopState>)	執行 `for` 一個 64 位元索引的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。
For(Int64, Int64, Action<Int64>)	執行 `for` 一個 64 位元索引的迴圈，並可平行執行迭代。
For(Int32, Int32, ParallelOptions, Action<Int32,ParallelLoopState>)	執行 `for` 一個迴圈，在其中可平行執行迭代，可設定迴圈選項，並監控與操作迴圈狀態。
For(Int32, Int32, ParallelOptions, Action<Int32>)	執行 `for` 一個迴圈，該迴圈可平行執行迭代，並可配置迴圈選項。
For(Int64, Int64, ParallelOptions, Action<Int64,ParallelLoopState>)	執行 `for` 一個 64 位元索引的迴圈，該迴圈可平行執行，迴圈選項可配置，迴圈狀態可被監控與操作。
For(Int64, Int64, ParallelOptions, Action<Int64>)	執行 `for` 一個 64 位元索引的迴圈，可平行迭代並配置迴圈選項。
For<TLocal>(Int32, Int32, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)	執行 `for` 一個包含執行緒本地資料的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。
For<TLocal>(Int64, Int64, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)	執行 `for` 一個包含 64 位元索引與執行緒本地資料的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。
For<TLocal>(Int32, Int32, ParallelOptions, Func<TLocal>, Func<Int32,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)	執行 `for` 一個包含線程本地資料的迴圈，該迴圈可平行執行，迴圈選項可設定，迴圈狀態可被監控與操作。
For<TLocal>(Int64, Int64, ParallelOptions, Func<TLocal>, Func<Int64,ParallelLoopState,TLocal,TLocal>, Action<TLocal>)	執行 `for` 一個包含 64 位元索引與執行緒本地資料的迴圈，該迴圈可平行執行，迴圈選項可配置，迴圈狀態可被監控與操作。

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個迴圈，其中可平行執行迭代，並可監控與操作迴圈狀態。

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

包含起始索引。

toExclusive: Int32

末端索引，獨家。

body: Action<Int32,ParallelLoopState>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

範例

以下範例可平行執行最多 100 次迴圈迭代。每次迭代會隨機暫停，間隔從 1 到 1,000 毫秒不等。隨機產生的值決定該方法在迴圈 ParallelLoopState.Break 的哪一次迭代中被呼叫。如範例輸出所示，索引大於屬性值的迭代 ParallelLoopState.LowestBreakIteration 不會在呼叫 ParallelLoopState.Break 該方法後開始。

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);

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

        var result = Parallel.For(1, 101, (i, state) => 
        {
            Console.WriteLine($"Beginning iteration {i}");
            int delay;
            lock (rnd)
                delay = rnd.Next(1, 1001);
            Thread.Sleep(delay);

            if (state.ShouldExitCurrentIteration)
            {
                if (state.LowestBreakIteration < i)
                    return;
            }

            if (i == breakIndex)
            {
                Console.WriteLine($"Break in iteration {i}");
                state.Break();
            }

            Console.WriteLine($"Completed iteration {i}");
        });

        if (result.LowestBreakIteration.HasValue)
            Console.WriteLine($"\nLowest Break Iteration: {result.LowestBreakIteration}");
        else
            Console.WriteLine($"\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

由於當方法被呼叫時 ParallelLoopState.Break ，迴圈的迭代很可能仍在執行中，每次迭代都會呼叫該 ParallelLoopState.ShouldExitCurrentIteration 屬性，以檢查是否有其他迭代已呼叫該 ParallelLoopState.Break 方法。若屬性值為 true，迭代會檢查屬性值 ParallelLoopState.LowestBreakIteration ，若大於當前迭代的索引值，則立即返回。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供了兩個論點：

一個 Int32 代表迭代次數的值。
一個 ParallelLoopState 可以用來提前脫離循環的實例。 ParallelLoopState物件由編譯器建立;無法在使用者程式碼中實例化。

呼叫該 Break 方法會告知 for 操作，接下來的迭代不必執行。不過，如果之前的所有迭代都必須執行，如果還沒執行的話。

因此，呼叫 Break 類似於在 C# 等語言中使用傳統 for 迴圈中的中斷操作，但並非完美替代方案：例如，無法保證在當前迭代之後的迭代一定不會執行。

若不需要在當前迭代之前執行所有迭代，則改用該 Stop 方法而非 Break。呼叫 Stop 時會通知 for 迴圈，它可以放棄所有剩餘的迭代，不論是在當前迭代之前還是之後，因為所有必要的工作都已經完成。然而，與 Break一樣，無法保證哪些其他迭代不會執行。

若迴圈過早結束，回傳的 ParallelLoopResult 結構將包含迴圈完成的相關資訊。

若 fromInclusive 大於或等於 toExclusive，該方法會立即返回，無需進行任何迭代。

另請參閱

適用於

For(Int32, Int32, Action<Int32>)

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個迴圈，使迭代可以平行執行。

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

包含起始索引。

toExclusive: Int32

末端索引，獨家。

body: Action<Int32>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

範例

以下範例使用 For 了 100 次代理式呼叫的方法，該代理產生隨機位元組值並計算其總和。

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代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它以迭代次數（Int32）作為參數提供。

若 fromInclusive 大於或等於 toExclusive，該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個 64 位元索引的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。

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

包含起始索引。

toExclusive: Int64

末端索引，獨家。

body: Action<Int64,ParallelLoopState>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個 ParallelLoopResult 包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int64），以及 ParallelLoopState 一個可用來提前脫離迴圈的實例。

呼叫該 Break 方法會告訴 for 操作，目前迭代之後的迭代不必執行，但所有之前的迭代都需要執行。

因此，呼叫 Break 類似於在 C# 等語言中使用傳統 for 迴圈中的中斷操作，但它並非完美替代品：例如，無法保證在當前迭代之後的迭代一定不會執行。

若迴圈過早結束，回傳的 ParallelLoopResult 結構將包含迴圈完成的相關資訊。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

For(Int64, Int64, Action<Int64>)

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個 64 位元索引的迴圈，並可平行執行迭代。

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

包含起始索引。

toExclusive: Int64

末端索引，獨家。

body: Action<Int64>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它以迭代次數（Int64）作為參數提供。

若 fromInclusive 大於或等於 toExclusive，該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個迴圈，在其中可平行執行迭代，可設定迴圈選項，並監控與操作迴圈狀態。

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

Public Shared Function For (fromInclusive As Integer, toExclusive As Integer, parallelOptions As ParallelOptions, body As Action(Of Integer, ParallelLoopState)) As ParallelLoopResult

參數

fromInclusive: Int32

包含起始索引。

toExclusive: Int32

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

body: Action<Int32,ParallelLoopState>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ArgumentNullException

論 body 點為 null。

-或-

論 parallelOptions 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int32），以及 ParallelLoopState 一個可用來提前脫離迴圈的實例。

若 fromInclusive 大於或等於 toExclusive，該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個迴圈，該迴圈可平行執行迭代，並可配置迴圈選項。

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

Public Shared Function For (fromInclusive As Integer, toExclusive As Integer, parallelOptions As ParallelOptions, body As Action(Of Integer)) As ParallelLoopResult

參數

fromInclusive: Int32

包含起始索引。

toExclusive: Int32

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

body: Action<Int32>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ArgumentNullException

論 body 點為 null。

-或-

論 parallelOptions 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

範例

以下範例展示了如何取消平行迴路：

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代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它以迭代次數（Int32）作為參數提供。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個 64 位元索引的迴圈，該迴圈可平行執行，迴圈選項可配置，迴圈狀態可被監控與操作。

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

Public Shared Function For (fromInclusive As Long, toExclusive As Long, parallelOptions As ParallelOptions, body As Action(Of Long, ParallelLoopState)) As ParallelLoopResult

參數

fromInclusive: Int64

包含起始索引。

toExclusive: Int64

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

body: Action<Int64,ParallelLoopState>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ArgumentNullException

論 body 點為 null。

-或-

論 parallelOptions 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

範例

以下範例展示了如何將此方法應用 Parallel.For 於物件 ParallelOptions ：

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

若 fromInclusive 大於或等於 toExclusive，該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個 64 位元索引的迴圈，可平行迭代並配置迴圈選項。

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

Public Shared Function For (fromInclusive As Long, toExclusive As Long, parallelOptions As ParallelOptions, body As Action(Of Long)) As ParallelLoopResult

參數

fromInclusive: Int64

包含起始索引。

toExclusive: Int64

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

body: Action<Int64>

這個代理在每次迭代中被調用一次。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ArgumentNullException

論 body 點為 null。

-或-

論 parallelOptions 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

範例

以下範例說明如何使用 ParallelOptions 自訂任務排程器：

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。 body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它以迭代次數（Int64）作為參數提供。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個包含執行緒本地資料的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。

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

執行緒本地資料的類型。

參數

fromInclusive: Int32

包含起始索引。

toExclusive: Int32

末端索引，獨家。

localInit: Func<TLocal>

函式委派每個任務的本地資料初始狀態。

body: Func<Int32,ParallelLoopState,TLocal,TLocal>

這個代理在每次迭代中被調用一次。

localFinally: Action<TLocal>

代表負責對每個任務的本地狀態執行最後操作。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

-或-

論 localInit 點為 null。

-或-

論 localFinally 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int32）、 ParallelLoopState 一個可用來提前脫離迴圈的實例，以及可在同一執行緒執行的迭代間共享的本地狀態。

localInit代理會對參與迴圈執行的每個任務呼叫一次，並回傳每個任務的初始本地狀態。這些初始狀態會傳遞給每個任務的首次 body 呼叫。接著，每次後續的身體呼叫都會回傳一個可能修改過的狀態值，並傳給下一個身體呼叫。最後，每個任務的最後一次主體調用會回傳一個狀態值，並傳給 localFinally 代理。 localFinally每個任務會被召喚一次，對每個任務的當地狀態執行最終行動。此代表可同時執行多項任務;因此，你必須同步存取任何共享變數。

該 Parallel.For 方法在其執行期間可能使用比執行緒更多的任務，因為現有任務會完成並被新任務取代。這讓底層 TaskScheduler 物件有機會新增、變更或移除服務迴圈的執行緒。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

若想看使用此方法的範例，請參見《如何寫平行。For 迴圈，Thread-Local 變數。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個包含 64 位元索引與執行緒本地資料的迴圈，該迴圈可平行執行，迴圈狀態可被監控與操作。

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

執行緒本地資料的類型。

參數

fromInclusive: Int64

包含起始索引。

toExclusive: Int64

末端索引，獨家。

localInit: Func<TLocal>

函式委派每個任務的本地資料初始狀態。

body: Func<Int64,ParallelLoopState,TLocal,TLocal>

這個代理在每次迭代中被調用一次。

localFinally: Action<TLocal>

代表負責對每個任務的本地狀態執行最後操作。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

-或-

論 localInit 點為 null。

-或-

論 localFinally 點為 null。

AggregateException

包含所有執行緒拋出的個別例外的例外。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int64）、 ParallelLoopState 一個可用來提前脫離迴圈的實例，以及可能在同一任務執行的迭代間共享的某個局部狀態。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

若想看使用此方法的範例，請參見《如何寫平行。For 迴圈，Thread-Local 變數。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個包含線程本地資料的迴圈，該迴圈可平行執行，迴圈選項可設定，迴圈狀態可被監控與操作。

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

Public Shared Function For(Of TLocal) (fromInclusive As Integer, toExclusive As Integer, parallelOptions As ParallelOptions, 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

執行緒本地資料的類型。

參數

fromInclusive: Int32

包含起始索引。

toExclusive: Int32

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

localInit: Func<TLocal>

函式委派每個任務的本地資料初始狀態。

body: Func<Int32,ParallelLoopState,TLocal,TLocal>

這個代理在每次迭代中被調用一次。

localFinally: Action<TLocal>

代表負責對每個任務的本地狀態執行最後操作。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

-或-

論 localInit 點為 null。

-或-

論 localFinally 點為 null。

-或-

論 parallelOptions 點為 null。

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

AggregateException

包含所有執行緒拋出的個別例外的例外。

範例

以下範例使用執行緒-局部變數來計算許多冗長運算結果的總和。此範例將平行程度限制為四。

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代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int32）、 ParallelLoopState 一個可用來提前脫離迴圈的實例，以及可能在同一任務執行的迭代間共享的某個局部狀態。

localInit代理會對參與迴圈執行的每個任務呼叫一次，並回傳每個任務的初始本地狀態。這些初始狀態會傳遞給每個任務的首次 body 呼叫。接著，每次後續的身體呼叫都會回傳一個可能修改過的狀態值，並傳給下一個身體呼叫。最後，每個任務的最後一次主體調用會回傳一個狀態值，並傳給 localFinally 代理。 localFinally每個任務會被召喚一次，對每個任務的當地狀態執行最終行動。此代理可同時在多個執行緒中被調用;因此，你必須同步存取任何共享變數。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

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

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

來源:: Parallel.cs

執行 for 一個包含 64 位元索引與執行緒本地資料的迴圈，該迴圈可平行執行，迴圈選項可配置，迴圈狀態可被監控與操作。

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

Public Shared Function For(Of TLocal) (fromInclusive As Long, toExclusive As Long, parallelOptions As ParallelOptions, 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

執行緒本地資料的類型。

參數

fromInclusive: Int64

包含起始索引。

toExclusive: Int64

末端索引，獨家。

parallelOptions: ParallelOptions

一個用來設定此操作行為的物件。

localInit: Func<TLocal>

函式會代理每個執行緒的本地資料初始狀態。

body: Func<Int64,ParallelLoopState,TLocal,TLocal>

這個代理在每次迭代中被調用一次。

localFinally: Action<TLocal>

代表者負責對每個執行緒的本地狀態執行最後操作。

傳回

ParallelLoopResult

一個包含迴圈完成部分資訊的結構。

例外狀況

ArgumentNullException

論 body 點為 null。

-或-

論 localInit 點為 null。

-或-

論 localFinally 點為 null。

-或-

論 parallelOptions 點為 null。

OperationCanceledException

CancellationToken parallelOptions爭論被取消了。

ObjectDisposedException

CancellationTokenSource與相關CancellationTokenparallelOptions事物已處置。

AggregateException

包含所有執行緒拋出的個別例外的例外。

備註

body代理在迭代範圍內fromInclusive的每個值（， toExclusive）中會被調用一次。它提供以下參數：迭代次數（Int64）、 ParallelLoopState 一個可用來提前脫離迴圈的實例，以及可在同一執行緒執行的迭代間共享的本地狀態。

localInit代理會對參與迴圈執行的每個執行緒呼叫一次，並回傳每個執行緒的初始本地狀態。這些初始狀態會傳遞給每個執行緒的最初 body 調用。接著，每次後續的身體呼叫都會回傳一個可能修改過的狀態值，並傳給下一個身體呼叫。最後，每個執行緒的最後一次主體調用會回傳一個狀態值，並傳給 localFinally 代理。 localFinally代理在每個執行緒中會被呼叫一次，以對每個執行緒的本地狀態執行最後一個動作。此代理可同時在多個執行緒中被調用;因此，你必須同步存取任何共享變數。

若 fromInclusive 大於或等於 toExclusive，則該方法會立即返回，無需進行任何迭代。

另請參閱

平行環線

適用於

意見反應

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共用方式為

Parallel.For 方法

定義

多載

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

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

For(Int32, Int32, Action<Int32>)

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

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

參數

傳回

例外狀況

備註

另請參閱

適用於

For(Int64, Int64, Action<Int64>)

參數

傳回

例外狀況

備註

另請參閱

適用於

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

參數

傳回

例外狀況

備註

另請參閱

適用於

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

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

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

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

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

參數

傳回

例外狀況

範例

備註

另請參閱

適用於

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

類型參數

參數

傳回

例外狀況

備註

另請參閱

適用於

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

類型參數

參數

傳回

例外狀況

備註

另請參閱