ParallelLoopState.LowestBreakIteration ParallelLoopState.LowestBreakIteration ParallelLoopState.LowestBreakIteration ParallelLoopState.LowestBreakIteration Property

Definition

Ruft die niedrigste Iteration der Schleife ab, von der Break() aufgerufen wurde.Gets the lowest iteration of the loop from which Break() was called.

public:
 property Nullable<long> LowestBreakIteration { Nullable<long> get(); };
public Nullable<long> LowestBreakIteration { get; }
member this.LowestBreakIteration : Nullable<int64>
Public ReadOnly Property LowestBreakIteration As Nullable(Of Long)

Eigenschaftswert

Die niedrigste Iteration, aus der Break() aufgerufen wurde.The lowest iteration from which Break() was called. Bei einer ForEach<TSource>(Partitioner<TSource>, Action<TSource>)-Schleife basiert der Wert auf einem intern generierten Index.In the case of a ForEach<TSource>(Partitioner<TSource>, Action<TSource>) loop, the value is based on an internally-generated index.

Beispiele

Im folgenden Beispiel werden bis zu 100 Iterationen einer Schleife parallel ausgeführt.The following example executes up to 100 iterations of a loop in parallel. Jede Iterations Pause wird für ein zufälliges Intervall von 1 bis 1.000 Millisekunden angehalten.Each iteration pauses for a random interval from 1 to 1,000 milliseconds. Ein zufällig generierter Wert bestimmt, in welcher Iterations Schleife die Break Methode aufgerufen wird.A randomly generated value determines on which iteration of the loop the Break method is called. Dadurch wird verhindert, dass Iterationen, deren Index LowestBreakIteration größer ist als der-Eigenschafts Wert, Break beginnend nach dem aufzurufenden-Methode, jedoch keine Auswirkungen auf Iterationen haben, die bereits mit der Ausführung begonnen haben.This prevents iterations whose index is greater than the LowestBreakIteration property value from starting after the call to the Break method, but it does not affect any iterations that have already begun executing. Um dies zu verhindern, ruft jede Iterations Methode die ShouldExitCurrentIteration -Methode auf, um zu überprüfen, ob Break die Methode von einer anderen Iterations Methode aufgerufen wurde.To prevent these from completing, each iteration calls the ShouldExitCurrentIteration method to check whether another iteration has called the Break method. Wenn dies der Fall ist, überprüft die Iterations Werte LowestBreakIteration den Wert der-Eigenschaft und, wenn er größer als der Indexwert der aktuellen Iterationen ist, sofort.If so, the iteration checks the value of the LowestBreakIteration property and, if it is greater than the current iteration's index value, returns immediately.

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

Beachten Sie Folgendes: da LowestBreakIteration der Wert außerhalb des Gültigkeits Bereichs außerhalb der parallelen Schleife liegt, müssen Sie ihn einer Variablen zuweisen, die außerhalb der Schleife sichtbar ist, wenn Sie den Wert beibehalten möchten.Note that, because the LowestBreakIteration value is out of scope outside of the parallel loop, you must assign it to a variable that is visible outside of the loop if you want to preserve its value.

Hinweise

Es ist möglich, dass mehrere Iterationen einer parallelen Schleife die Break -Methode aufruft.It is possible for multiple iterations of a parallel loop to call the Break method. Wenn dies der Fall ist, ist dieser Wert der kleinste Index einer Iterationen, Breakdie aufgerufen hat.If they do, this value is the smallest index of an iteration that called Break. Wenn keine Iterations Schleife aufgerufen Breakwird, gibt diese Eigenschaft zurück. nullIf no iteration of the loop called Break, this property returns null. Beachten Sie, dass der-Eigenschafts Wert durch Aufrufe Stop der-Methode nicht beeinträchtigt wird.Note that the property value is unaffected by calls to the Stop method.

In Iterationen mit langer Laufzeit, in denen alle Iterationen nach der Iteration, die Break die-Methode aufruft, nicht LowestBreakIteration ausgeführt werden müssen, wird die-Eigenschaft verwendet, um Iterationen zu beenden Break , die vor dem Aufruf der-Methode gestartet wurden.In long-running iterations in which all iterations after the iteration that calls the Break method need not run, the LowestBreakIteration property is used to terminate iterations that began execution before the call to the Break method. Führen Sie die folgenden Schritte aus, um Iterationen zu verhindern, deren Index größer als die niedrigste Unterbrechung bei der Ausführung der konkurrierenden Ausführung ist:To stop iterations whose index is greater than the lowest break iteration from competing execution, you should do the following:

  1. Überprüfen Sie ShouldExitCurrentIteration , ob truedie-Eigenschaft ist.Check whether the ShouldExitCurrentIteration property is true.

  2. Beenden Sie die Iterations, wenn Ihr Index größer als der LowestBreakIteration -Eigenschafts Wert ist.Exit from the iteration if its index is greater than the LowestBreakIteration property value.

Dies wird im Beispiel veranschaulicht.The example provides an illustration.

Gilt für:

Siehe auch