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

Definizione

Comunica che il ciclo Parallel deve interrompere l'esecuzione non appena il sistema lo richieda.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 ()

Eccezioni

Il metodo Break() è stato chiamato in precedenza.The Break() method was called previously. Break() e Stop() non possono essere utilizzati in combinazione da iterazioni dello stesso ciclo.Break() and Stop() may not be used in combination by iterations of the same loop.

Esempi

Nell'esempio seguente viene eseguita fino a 10.000 iterazioni di un ciclo in parallelo.The following example executes up to 10,000 iterations of a loop in parallel. Ogni iterazione viene sospeso per un intervallo casuale compreso tra 1 e 1.000 millisecondi.Each iteration pauses for a random interval from 1 to 1,000 milliseconds. Un valore generato casualmente determina a quali iterazione del ciclo di Stop viene chiamato il metodo.A randomly generated value determines on which iteration of the loop the Stop method is called. Come illustrato nell'output dell'esempio, non le iterazioni vengono eseguite dopo la chiamata al Stop (metodo).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

Poiché le iterazioni del ciclo sono ancora soggetti a essere in esecuzione quando il Stop viene chiamato il metodo, le chiamate di ogni iterazione il IsStopped metodo per verificare se un'altra iterazione è chiamato il Stop (metodo).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. Se il valore restituito true, viene restituito immediatamente all'iterazione.If it returns true, the iteration returns immediately.

Commenti

La chiamata di Stop (metodo) indica che le iterazioni del ciclo che non sono ancora state avviate non devono essere eseguite.Calling the Stop method indicates that any iterations of the loop that have not yet started need not be run. Cancella in modo efficace eventuali altre iterazioni del ciclo.It effectively cancels any additional iterations of the loop. Tuttavia, tutte le iterazioni che aver già iniziato l'esecuzione non viene arrestato.However, it does not stop any iterations that have already begun execution.

Chiama il Stop metodo provoca il IsStopped proprietà da restituire true per un'iterazione del ciclo che è ancora in esecuzione.Calling the Stop method causes the IsStopped property to return true for any iteration of the loop that is still executing. Ciò è particolarmente utile per le iterazioni con esecuzione prolungata, che possono controllare la IsStopped proprietà e uscita anticipo se il valore è true.This is particularly useful for long-running iterations, which can check the IsStopped property and exit early if its value is true.

Stop viene in genere utilizzato negli algoritmi basate sulla ricerca, in cui una volta un risultato trovate, nessun altro iterazioni necessitano da eseguire.Stop is typically employed in search-based algorithms, where once a result is found, no other iterations need be executed.

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