Parallel LINQ: PLINQ Query in C# and VB.Net

Parallel LINQ: PLINQ Query in C# and VB.Net

In this article I will explain what is Parallel LINQ (PLINQ) and a simple example how to write a PLINQ Query in C# and VB.Net .Net 4.0 and .Net 4.5.

Parallelism can be achieved in two ways

1.     Parallel class

2.     PLINQ (Parallel LINQ)

Here I will be explaining how to achieve parallelism using Parallel LINQ (PLINQ) with an example that will have a list of websites in a string collection and we’ll try to ping the sites in parallel. In the example I’ll be making use of the following namespace to access the Ping class.

C#

using System.Net.NetworkInformation;

 

VB.Net

Imports System.Net.NetworkInformation

PLINQ (Parallel LINQ)

Next technique is very similar to above but belongs to a different namespace i.e. System.Linq

C#

List<string> sites = new List<string>

{

"www.yahoo.com",

"www.google.com",

"www.aspsnippets.com"

};

 

List<PingReply> pingReplies = (from site in sites.AsParallel().WithDegreeOfParallelism(sites.Count)

                           select DoPing(site)).ToList() as List<PingReply>;

 

foreach (var s in pingReplies.ToList())

{

    Response.Write(s.Address + ": " + s.RoundtripTime + ": " + s.Status + "<br />");

}

 

VB.Net

Dim sites As New List(Of String)

sites.Add("www.yahoo.com")

sites.Add("www.google.com")

sites.Add("www.aspsnippets.com")

 

Dim pingReplies As List(Of PingReply) = TryCast((

                  From site In sites.AsParallel().WithDegreeOfParallelism(sites.Count) _

                  Select DoPing(site)).ToList(), List(Of PingReply))

 

For Each s In pingReplies.ToList()

    Response.Write(Convert.ToString(s.Address) & ": " & Convert.ToString(s.RoundtripTime) & ": " & Convert.ToString(s.Status) & "<br />")

Next

Above you will notice that I am executing a LINQ query on the List of the sites. It looks like a normal LINQ query the only difference is that I have used the additional methods AsParallel (Tells the compiler to execute query in parallel) and WithDegreeOfParallelism (Allows you to specify the number of threads executed in parallel). Also I am calling a Method DoPing which basically pings the site and returns the Ping Reply, this method is described below

C#

private PingReply DoPing(string site)

{

    Ping p = new Ping();

    return p.Send(site);

}

 

VB.Net

Private Function DoPing(ByVal site As String) As PingReply

    Dim p As New Ping()

    Return p.Send(site)

End Function