ParallelLoopState.Stop ParallelLoopState.Stop ParallelLoopState.Stop ParallelLoopState.Stop Method

定義

傳達 Parallel 迴圈應該依系統的方便盡早停止執行。Communicates that the Parallel loop should cease execution at the system's earliest convenience.

public:
 void Stop();
public void Stop ();
member this.Stop : unit -> unit
Public Sub Stop ()

例外狀況

之前呼叫過 Break() 方法。The Break() method was called previously. Break()Stop() 可能無法由相同迴圈的反覆項目搭配使用。Break() and Stop() may not be used in combination by iterations of the same loop.

範例

下列範例會平行執行最多10000個反覆運算的反復專案。The following example executes up to 10,000 iterations of a loop in parallel. 每個反復專案都會暫停1到1000毫秒的隨機間隔。Each iteration pauses for a random interval from 1 to 1,000 milliseconds. 隨機產生的值會決定要在哪一個迴圈Stop反覆運算上呼叫方法。A randomly generated value determines on which iteration of the loop the Stop method is called. 如範例的輸出所示, 在呼叫Stop方法之後, 不會執行任何反復專案。As the output from the example shows, no iterations execute after the call to the Stop method.

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

public class Example
{
   public static void Main()
   {
      var rnd = new Random();
      long stopIndex = rnd.Next(1, 11);

      Console.WriteLine("Will call Stop in iteration {0}\n", stopIndex);

      var result = Parallel.For(1, 10000, (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 (i == stopIndex) {
                                               Console.WriteLine("Stop in iteration {0}", i);
                                               state.Stop();
                                               return;
                                            }

                                            if (state.IsStopped) {
                                               return;
                                            }

                                            Console.WriteLine("Completed iteration {0}", i);
                                       });
   }
}
// The example displays output like the following:
//       Will call Stop in iteration 5
//
//       Beginning iteration 1
//       Beginning iteration 9993
//       Beginning iteration 8744
//       Beginning iteration 6246
//       Beginning iteration 7495
//       Beginning iteration 3748
//       Beginning iteration 4997
//       Beginning iteration 2499
//       Beginning iteration 1250
//       Completed iteration 6246
//       Beginning iteration 6247
//       Completed iteration 3748
//       Beginning iteration 3749
//       Completed iteration 8744
//       Beginning iteration 8745
//       Completed iteration 7495
//       Beginning iteration 7496
//       Completed iteration 1250
//       Beginning iteration 1251
//       Completed iteration 2499
//       Beginning iteration 2500
//       Completed iteration 1
//       Beginning iteration 2
//       Completed iteration 2500
//       Beginning iteration 2501
//       Completed iteration 3749
//       Beginning iteration 3750
//       Completed iteration 6247
//       Beginning iteration 6248
//       Completed iteration 7496
//       Beginning iteration 7497
//       Completed iteration 3750
//       Beginning iteration 3751
//       Completed iteration 2
//       Beginning iteration 3
//       Completed iteration 9993
//       Beginning iteration 9994
//       Completed iteration 8745
//       Beginning iteration 8746
//       Completed iteration 4997
//       Completed iteration 9994
//       Beginning iteration 9995
//       Beginning iteration 4998
//       Completed iteration 6248
//       Beginning iteration 6249
//       Completed iteration 7497
//       Beginning iteration 7498
//       Completed iteration 1251
//       Beginning iteration 1252
//       Completed iteration 2501
//       Beginning iteration 2502
//       Completed iteration 9995
//       Beginning iteration 9996
//       Completed iteration 4998
//       Beginning iteration 4999
//       Completed iteration 2502
//       Beginning iteration 2503
//       Completed iteration 1252
//       Beginning iteration 1253
//       Completed iteration 7498
//       Beginning iteration 7499
//       Completed iteration 3751
//       Beginning iteration 3752
//       Completed iteration 9996
//       Beginning iteration 9997
//       Completed iteration 1253
//       Beginning iteration 1254
//       Completed iteration 9997
//       Beginning iteration 9998
//       Completed iteration 1254
//       Beginning iteration 1255
//       Completed iteration 6249
//       Beginning iteration 6250
//       Completed iteration 3
//       Beginning iteration 4
//       Completed iteration 4
//       Beginning iteration 5
//       Completed iteration 4999
//       Beginning iteration 5000
//       Completed iteration 8746
//       Beginning iteration 8747
//       Stop in iteration 5
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim rnd As New Random()
      Dim stopIndex As Long = rnd.Next(1, 11)

      Console.WriteLine("Will call Stop in iteration {0}", stopIndex)
      Console.WriteLine()

      Dim result = Parallel.For(1, 10000, 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 i = stopIndex Then
                                               Console.WriteLine("Stop in iteration {0}", i)
                                               state.Stop()
                                               Return
                                            End If

                                            If state.IsStopped Then
                                               Return
                                            End If

                                            Console.WriteLine("Completed iteration {0}", i)
                                       End Sub)
    End Sub
End Module
' The example displays output like the following:
'       Will call Stop in iteration 5
'
'       Beginning iteration 1
'       Beginning iteration 9993
'       Beginning iteration 8744
'       Beginning iteration 6246
'       Beginning iteration 7495
'       Beginning iteration 3748
'       Beginning iteration 4997
'       Beginning iteration 2499
'       Beginning iteration 1250
'       Completed iteration 6246
'       Beginning iteration 6247
'       Completed iteration 3748
'       Beginning iteration 3749
'       Completed iteration 8744
'       Beginning iteration 8745
'       Completed iteration 7495
'       Beginning iteration 7496
'       Completed iteration 1250
'       Beginning iteration 1251
'       Completed iteration 2499
'       Beginning iteration 2500
'       Completed iteration 1
'       Beginning iteration 2
'       Completed iteration 2500
'       Beginning iteration 2501
'       Completed iteration 3749
'       Beginning iteration 3750
'       Completed iteration 6247
'       Beginning iteration 6248
'       Completed iteration 7496
'       Beginning iteration 7497
'       Completed iteration 3750
'       Beginning iteration 3751
'       Completed iteration 2
'       Beginning iteration 3
'       Completed iteration 9993
'       Beginning iteration 9994
'       Completed iteration 8745
'       Beginning iteration 8746
'       Completed iteration 4997
'       Completed iteration 9994
'       Beginning iteration 9995
'       Beginning iteration 4998
'       Completed iteration 6248
'       Beginning iteration 6249
'       Completed iteration 7497
'       Beginning iteration 7498
'       Completed iteration 1251
'       Beginning iteration 1252
'       Completed iteration 2501
'       Beginning iteration 2502
'       Completed iteration 9995
'       Beginning iteration 9996
'       Completed iteration 4998
'       Beginning iteration 4999
'       Completed iteration 2502
'       Beginning iteration 2503
'       Completed iteration 1252
'       Beginning iteration 1253
'       Completed iteration 7498
'       Beginning iteration 7499
'       Completed iteration 3751
'       Beginning iteration 3752
'       Completed iteration 9996
'       Beginning iteration 9997
'       Completed iteration 1253
'       Beginning iteration 1254
'       Completed iteration 9997
'       Beginning iteration 9998
'       Completed iteration 1254
'       Beginning iteration 1255
'       Completed iteration 6249
'       Beginning iteration 6250
'       Completed iteration 3
'       Beginning iteration 4
'       Completed iteration 4
'       Beginning iteration 5
'       Completed iteration 4999
'       Beginning iteration 5000
'       Completed iteration 8746
'       Beginning iteration 8747
'       Stop in iteration 5

因為呼叫Stop方法時, 迴圈的反復專案仍可能執行, 每個反復專案都會IsStopped呼叫方法來檢查Stop另一個反復專案是否已呼叫方法。Because iterations of the loop are still likely to be executing when the Stop method is called, each iteration calls the IsStopped method to check whether another iteration has called the Stop method. 如果傳回true, 則會立即傳回反復專案。If it returns true, the iteration returns immediately.

備註

Stop呼叫方法表示不需要執行任何尚未開始之迴圈的反覆運算。Calling the Stop method indicates that any iterations of the loop that have not yet started need not be run. 它會有效地取消迴圈的任何其他反覆運算。It effectively cancels any additional iterations of the loop. 不過, 它不會停止已開始執行的任何反復專案。However, it does not stop any iterations that have already begun execution.

呼叫方法會讓true屬性針對仍在執行之迴圈的任何反復專案傳回。 IsStopped StopCalling the Stop method causes the IsStopped property to return true for any iteration of the loop that is still executing. 這對於長時間執行的反復專案特別有用, 可以檢查IsStopped屬性並提早結束 (如果其值為true)。This is particularly useful for long-running iterations, which can check the IsStopped property and exit early if its value is true.

Stop通常會在以搜尋為基礎的演算法中採用, 一旦找到結果, 就不需要執行其他任何反復專案。Stop is typically employed in search-based algorithms, where once a result is found, no other iterations need be executed.

適用於

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