ParallelLoopState.Stop Metoda

Definicja

Komunikuje się, że Parallel Pętla powinna zaprzestać wykonywania na najwcześniejszym wygodie systemu.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 ()

Wyjątki

Break()Metoda została wcześniej wywołana.The Break() method was called previously. Break()i Stop() nie mogą być używane w połączeniu z iteracjami tej samej pętli.Break() and Stop() may not be used in combination by iterations of the same loop.

Przykłady

Poniższy przykład wykonuje równolegle do 10 000 iteracji pętli.The following example executes up to 10,000 iterations of a loop in parallel. Każda iteracja wstrzymuje się dla losowego interwału od 1 do 1 000 milisekund.Each iteration pauses for a random interval from 1 to 1,000 milliseconds. Generowana losowo wartość określa, na której iteracji pętli Stop wywoływana jest metoda.A randomly generated value determines on which iteration of the loop the Stop method is called. Dane wyjściowe z przykładu pokazują, że żadne iteracje nie są wykonywane po wywołaniu Stop metody.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

Ponieważ iteracje pętli nadal mogą być wykonywane Stop , gdy wywoływana jest metoda, każda iteracja wywołuje IsStopped metodę, aby sprawdzić, czy inna iteracja nazywa Stop metodę.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. Jeśli zwróci true , iteracja zwraca natychmiast.If it returns true, the iteration returns immediately.

Uwagi

Wywołanie Stop metody wskazuje, że nie trzeba uruchamiać wszystkich iteracji pętli, które nie zostały jeszcze uruchomione.Calling the Stop method indicates that any iterations of the loop that have not yet started need not be run. Efektywnie anuluje wszelkie dodatkowe iteracje pętli.It effectively cancels any additional iterations of the loop. Nie zatrzymuje jednak żadnych iteracji, które już rozpoczęły wykonywanie.However, it does not stop any iterations that have already begun execution.

Wywołanie Stop metody powoduje, że IsStopped Właściwość zwraca true dla każdej iteracji pętli, która jest nadal wykonywana.Calling the Stop method causes the IsStopped property to return true for any iteration of the loop that is still executing. Jest to szczególnie przydatne w przypadku długotrwałych iteracji, które mogą sprawdzić IsStopped Właściwość i zakończyć wczesne, jeśli wartość jest true .This is particularly useful for long-running iterations, which can check the IsStopped property and exit early if its value is true.

Stopjest zazwyczaj stosowany w algorytmach opartych na wyszukiwaniu, gdzie po znalezieniu wyniku nie trzeba wykonywać żadnych innych iteracji.Stop is typically employed in search-based algorithms, where once a result is found, no other iterations need be executed.

Dotyczy

Zobacz też