Cómo: Usar Parallel.Invoke para ejecutar operaciones paralelas
En este ejemplo se muestra cómo paralelizar las operaciones utilizando ParallelInvoke() en la biblioteca TPL (Task Parallel Library, biblioteca de procesamiento paralelo basado en tareas). En un origen de datos compartido se realizan tres operaciones. Dado que ninguna de ellas modifica el origen, se pueden ejecutar en paralelo de manera sencilla.
Nota |
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En esta documentación, se usan expresiones lambda para definir los delegados en la TPL.Si no está familiarizado con las expresiones lambda en C# o Visual Basic, vea Expresiones lambda en PLINQ y TPL. |
Ejemplo
' How to: Use Parallel.Invoke to Execute Parallel Operations
Option Explicit On
Option Strict On
Imports System.Threading.Tasks
Imports System.Net
Module ParallelTasks
Sub Main()
' Retrieve Darwin's "Origin of the Species" from Gutenberg.org.
Dim words As String() = CreateWordArray("http://www.gutenberg.org/files/2009/2009.txt")
'#Region "ParallelTasks"
' Perform three tasks in parallel on the source array
Parallel.Invoke(Sub()
Console.WriteLine("Begin first task...")
GetLongestWord(words)
' close first Action
End Sub,
Sub()
Console.WriteLine("Begin second task...")
GetMostCommonWords(words)
'close second Action
End Sub,
Sub()
Console.WriteLine("Begin third task...")
GetCountForWord(words, "species")
'close third Action
End Sub)
'close parallel.invoke
Console.WriteLine("Returned from Parallel.Invoke")
'#End Region
Console.WriteLine("Press any key to exit")
Console.ReadKey()
End Sub
#Region "HelperMethods"
Sub GetCountForWord(ByVal words As String(), ByVal term As String)
Dim findWord = From word In words _
Where word.ToUpper().Contains(term.ToUpper()) _
Select word
Console.WriteLine("Task 3 -- The word ""{0}"" occurs {1} times.", term, findWord.Count())
End Sub
Sub GetMostCommonWords(ByVal words As String())
Dim frequencyOrder = From word In words _
Where word.Length > 6 _
Group By word
Into wordGroup = Group, Count()
Order By wordGroup.Count() Descending _
Select wordGroup
Dim commonWords = From grp In frequencyOrder
Select grp
Take (10)
Dim s As String
s = "Task 2 -- The most common words are:" & vbCrLf
For Each v In commonWords
s = s & v(0) & vbCrLf
Next
Console.WriteLine(s)
End Sub
Function GetLongestWord(ByVal words As String()) As String
Dim longestWord = (From w In words _
Order By w.Length Descending _
Select w).First()
Console.WriteLine("Task 1 -- The longest word is {0}", longestWord)
Return longestWord
End Function
' An http request performed synchronously for simplicity.
Function CreateWordArray(ByVal uri As String) As String()
Console.WriteLine("Retrieving from {0}", uri)
' Download a web page the easy way.
Dim s As String = New WebClient().DownloadString(uri)
' Separate string into an array of words, removing some common punctuation.
Return s.Split(New Char() {" "c, ControlChars.Lf, ","c, "."c, ";"c, ":"c, _
"-"c, "_"c, "/"c}, StringSplitOptions.RemoveEmptyEntries)
End Function
#End Region
' Output (May vary on each execution):
' Retrieving from http://www.gutenberg.org/dirs/etext99/otoos610.txt
' Response stream received.
' Begin first task...
' Begin second task...
' Task 2 -- The most common words are:
' species
' selection
' varieties
' natural
' animals
' between
' different
' distinct
' several
' conditions
'
' Begin third task...
' Task 1 -- The longest word is characteristically
' Task 3 -- The word "species" occurs 1927 times.
' Returned from Parallel.Invoke
' Press any key to exit
'
End Module
namespace ParallelTasks
{
using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Net;
class ParallelInvoke
{
static void Main()
{
// Retrieve Darwin's "Origin of the Species" from Gutenberg.org.
string[] words = CreateWordArray(@"http://www.gutenberg.org/files/2009/2009.txt");
#region ParallelTasks
// Perform three tasks in parallel on the source array
Parallel.Invoke(() =>
{
Console.WriteLine("Begin first task...");
GetLongestWord(words);
}, // close first Action
() =>
{
Console.WriteLine("Begin second task...");
GetMostCommonWords(words);
}, //close second Action
() =>
{
Console.WriteLine("Begin third task...");
GetCountForWord(words, "species");
} //close third Action
); //close parallel.invoke
Console.WriteLine("Returned from Parallel.Invoke");
#endregion
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
#region HelperMethods
private static void GetCountForWord(string[] words, string term)
{
var findWord = from word in words
where word.ToUpper().Contains(term.ToUpper())
select word;
Console.WriteLine(@"Task 3 -- The word ""{0}"" occurs {1} times.",
term, findWord.Count());
}
private static void GetMostCommonWords(string[] words)
{
var frequencyOrder = from word in words
where word.Length > 6
group word by word into g
orderby g.Count() descending
select g.Key;
var commonWords = frequencyOrder.Take(10);
StringBuilder sb = new StringBuilder();
sb.AppendLine("Task 2 -- The most common words are:");
foreach (var v in commonWords)
{
sb.AppendLine(" " + v);
}
Console.WriteLine(sb.ToString());
}
private static string GetLongestWord(string[] words)
{
var longestWord = (from w in words
orderby w.Length descending
select w).First();
Console.WriteLine("Task 1 -- The longest word is {0}", longestWord);
return longestWord;
}
// An http request performed synchronously for simplicity.
static string[] CreateWordArray(string uri)
{
Console.WriteLine("Retrieving from {0}", uri);
// Download a web page the easy way.
string s = new WebClient().DownloadString(uri);
// Separate string into an array of words, removing some common punctuation.
return s.Split(
new char[] { ' ', '\u000A', ',', '.', ';', ':', '-', '_', '/' },
StringSplitOptions.RemoveEmptyEntries);
}
#endregion
}
/* Output (May vary on each execution):
Retrieving from http://www.gutenberg.org/dirs/etext99/otoos610.txt
Response stream received.
Begin first task...
Begin second task...
Task 2 -- The most common words are:
species
selection
varieties
natural
animals
between
different
distinct
several
conditions
Begin third task...
Task 1 -- The longest word is characteristically
Task 3 -- The word "species" occurs 1927 times.
Returned from Parallel.Invoke
Press any key to exit
*/
}
Observe que con Invoke(), simplemente expresa qué acciones desea que se ejecuten simultáneamente; el runtime controla todos los detalles de programación de subprocesos, incluido el escalado automático al número de núcleos del equipo host.
En este ejemplo se paralelizan las operaciones, no los datos. Como enfoque alternativo, puede paralelizar los consultas LINQ mediante PLINQ y ejecutar las consultas de forma secuencial. También puede paralelizar los datos con PLINQ. Otra opción consiste en paralelizar las consultas y las tareas. Aunque la sobrecarga resultante podría degradar el rendimiento en equipos host con relativamente pocos procesadores, se ajustaría mucho mejor en equipos con muchos procesadores.
Compilar el código
- Copie y pegue el ejemplo completo en un proyecto de Microsoft Visual Studio 2010 y presione F5.
Vea también
Tareas
Cómo: Esperar a que una o varias tareas se completen
Cómo: Encadenar varias tareas con continuaciones
Cómo: Cancelar una tarea y sus elementos secundarios