Como: usar Parallel.Invoke para executar operações paralelasHow to: Use Parallel.Invoke to Execute Parallel Operations

Este exemplo mostra como paralelizar operações usando Invoke na Biblioteca de paralelismo de tarefas.This example shows how to parallelize operations by using Invoke in the Task Parallel Library. Três operações são executadas em uma fonte de dados compartilhada.Three operations are performed on a shared data source. As operações podem ser executadas em paralelo de maneira simples, porque nenhuma delas modifica a origem.The operations can be executed in parallel in a straightforward manner, because none of them modifies the source.

Observação

Esta documentação usa expressões lambda para definir delegados na TLP.This documentation uses lambda expressions to define delegates in TPL. Se você não estiver familiarizado com expressões lambda em C# ou Visual Basic, consulte expressões lambda em PLINQ e TPL.If you aren't familiar with lambda expressions in C# or Visual Basic, see Lambda Expressions in PLINQ and TPL.

ExemploExample

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 Goncharov's "Oblomov" from Gutenberg.org.
            string[] words = CreateWordArray(@"http://www.gutenberg.org/files/54700/54700-0.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, "sleep");
                             } //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 ""{term}"" occurs {findWord.Count()} times.");
        }

        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 {longestWord}.");
            return longestWord;
        }

        // An http request performed synchronously for simplicity.
        static string[] CreateWordArray(string uri)
        {
            Console.WriteLine($"Retrieving from {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
    }
}
//        The example displays output like the following:
//              Retrieving from http://www.gutenberg.org/files/54700/54700-0.txt
//              Begin first task...
//              Begin second task...
//              Begin third task...
//              Task 2 -- The most common words are:
//              Oblomov
//              himself
//              Schtoltz
//              Gutenberg
//              Project
//              another
//              thought
//              Oblomov's
//              nothing
//              replied
//
//              Task 1 -- The longest word is incomprehensible.
//              Task 3 -- The word "sleep" occurs 57 times.
//              Returned from Parallel.Invoke
//              Press any key to exit
Imports System.Net
Imports System.Threading.Tasks

Module ParallelTasks
    Sub Main()
        ' Retrieve Goncharov's "Oblomov" from Gutenberg.org.
        Dim words As String() = CreateWordArray("http://www.gutenberg.org/files/54700/54700-0.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, "sleep")
                '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 ""{term}"" occurs {findWord.Count()} times.")
    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 {longestWord}.")
        Return longestWord
    End Function


    ' An http request performed synchronously for simplicity.
    Function CreateWordArray(ByVal uri As String) As String()
        Console.WriteLine($"Retrieving from {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
End Module
' The exmaple displays output like the following:
'       Retrieving from http://www.gutenberg.org/files/54700/54700-0.txt
'       Begin first task...
'       Begin second task...
'       Begin third task...
'       Task 2 -- The most common words are:
'       Oblomov
'       himself
'       Schtoltz
'       Gutenberg
'       Project
'       another
'       thought
'       Oblomov's
'       nothing
'       replied
'
'       Task 1 -- The longest word is incomprehensible.
'       Task 3 -- The word "sleep" occurs 57 times.
'       Returned from Parallel.Invoke
'       Press any key to exit

Com o Invoke , basta expressar quais ações você deseja executar simultaneamente, e o tempo de execução manipula todos os detalhes de agendamento de thread, incluindo o dimensionamento automático para o número de núcleos no computador host.With Invoke, you simply express which actions you want to run concurrently, and the runtime handles all thread scheduling details, including scaling automatically to the number of cores on the host computer.

Este exemplo paraleliza as operações, não os dados.This example parallelizes the operations, not the data. Como uma abordagem alternativa, você pode paralelizar as consultas do LINQ usando PLINQ e executar as consultas em sequência.As an alternate approach, you can parallelize the LINQ queries by using PLINQ and run the queries sequentially. Como alternativa, você poderia paralelizar os dados usando o PLINQ.Alternatively, you could parallelize the data by using PLINQ. Outra opção é paralelizar as consultas e as tarefas.Another option is to parallelize both the queries and the tasks. Embora a sobrecarga resultante possa prejudicar o desempenho em computadores host com relativamente poucos processadores, ela é dimensionada melhor em computadores com muitos processadores.Although the resulting overhead might degrade performance on host computers with relatively few processors, it scales better on computers with many processors.

Compile o códigoCompile the Code

Copie e cole o exemplo inteiro em um projeto do Microsoft Visual Studio e pressione F5.Copy and paste the entire example into a Microsoft Visual Studio project and press F5.

Confira tambémSee also