ParallelLoopState.Stop Metode
Definisi
Penting
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Berkomunikasi bahwa perulangan Parallel harus menghentikan eksekusi pada kenyamanan paling awal sistem.
public:
void Stop();public void Stop();member this.Stop : unit -> unitPublic Sub Stop ()Pengecualian
Metode Break() ini dipanggil sebelumnya. Break() dan Stop() mungkin tidak digunakan dalam kombinasi oleh perulangan dari perulangan yang sama.
Contoh
Contoh berikut menjalankan hingga 10.000 iterasi perulangan secara paralel. Setiap perulangan dijeda untuk interval acak dari 1 hingga 1.000 milidetik. Nilai yang dihasilkan secara acak menentukan di mana iterasi perulangan metode dipanggil Stop . Seperti yang ditunjukkan oleh output dari contoh, tidak ada iterasi yang dijalankan setelah panggilan ke Stop metode .
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
Karena iterasi perulangan masih cenderung dijalankan ketika Stop metode dipanggil, setiap perulangan memanggil IsStopped metode untuk memeriksa apakah iterasi lain telah memanggil metode .Stop Jika mengembalikan true, perulangan akan segera dikembalikan.
Keterangan
Memanggil Stop metode menunjukkan bahwa perulangan dari perulangan yang belum dimulai tidak perlu dijalankan. Ini secara efektif membatalkan perulangan tambahan dari perulangan. Namun, itu tidak menghentikan iterasi apa pun yang telah memulai eksekusi.
Memanggil Stop metode menyebabkan IsStopped properti kembali true untuk perulangan apa pun dari perulangan yang masih dijalankan. Ini sangat berguna untuk iterasi jangka panjang, yang dapat memeriksa IsStopped properti dan keluar lebih awal jika nilainya adalah true.
Stop biasanya digunakan dalam algoritma berbasis pencarian, di mana setelah hasil ditemukan, tidak ada iterasi lain yang perlu dijalankan.
