SpeedUp your Linq Queries with AsParallel

 

Diminuire il tempo di esecuzione di queries LINQ con l’abilitazione del parallelismo è semplice:

Public Class User
    Public ID_User As Integer
    Public ID_Role As Integer
    Public Name As String
    Public Surname As String
End Class
Public Class Role
    Public ID_Role As Integer
    Public Name As String
    Public Description As String
End Class

Sub Main()
    Dim sw As New Stopwatch
    Dim rs As New List(Of Role) From {New Role() With {.ID_Role = 1, .Name = "Default", .Description = ""}, _
                                      New Role() With {.ID_Role = 2, .Name = "J.Dev", .Description = ""}, _
                                      New Role() With {.ID_Role = 3, .Name = "S.Dev", .Description = ""}}

    Dim us As New List(Of User) From {New User() With {.ID_User = 1, .ID_Role = 1, .Name = "Fabio", .Surname = "Arosio"}, _
                                      New User() With {.ID_User = 1, .ID_Role = 2, .Name = "Claudio", .Surname = "Arosio"}, _
                                      New User() With {.ID_User = 1, .ID_Role = 1, .Name = "Lorenzo", .Surname = "Arosio"}}

    'Uso di una sola CPU
    sw.Start()
    Dim us_rs = (From p In us Where p.ID_Role = 1 _
                Select New With {.User_Name = p.Name, _
                                 .User_Surname = p.Surname, _
                                 .Role = (From q In rs Where q.ID_Role = p.ID_Role Select q.Name).FirstOrDefault _
                                }).ToList
    sw.Stop()
    Console.WriteLine("Single CPU Query - {0}", sw.Elapsed.TotalMilliseconds)


    'Multi CPU (AsParallel)
    sw = New Stopwatch
    sw.Start()
    Dim Parallel_us_rs = (From p In us Where p.ID_Role = 1 _
               Select New With {.User_Name = p.Name, _
                                .User_Surname = p.Surname, _
                                .Role = (From q In rs Where q.ID_Role = p.ID_Role Select q.Name).FirstOrDefault _
                               }).AsParallel.ToList
    sw.Stop()
    Console.WriteLine("Multi CPU Query - {0}", sw.Elapsed.TotalMilliseconds)


    '  PrintAnonymousT(us_rs)
    Console.ReadLine()
End Sub