I want to execute a network based task (with a possible long timeout) on multiple peers simultaneously.
So i have the following code:
Parallel.ForEach(hosts, i => SomeLongRunningNetworkTask(i));
I noticed that from the sixth task on the execution is delayed for ~ 1 second.
So i changed the code to:
hosts.AsParallel()
.WithDegreeOfParallelism(64)
.ForAll(i => result.Add(SomeLongRunningNetworkTask(i)));
but the result is the same.
Output (on a Quad-Core):
Start: 44,00 ms
Start: 44,00 ms
Start: 44,00 ms
Start: 44,00 ms
Start: 44,00 ms
Start: 1025,06 ms
Start: 2024,12 ms
Start: 3024,17 ms
Start: 4024,23 ms
Start: 5024,29 ms
...
Is there an easy way to use PLINQ without this weird behavior, or am i missing something ?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApplicationParallelTest
{
class Program
{
private DateTime Started { get; set; }
static void Main(string[] args)
{
// for testing: All Subnet IP's:
var ips = new List<IPAddress>();
for(int i=1 ; i< 255 ;i++)
ips.Add( IPAddress.Parse( "192.168.10." + i ));
var result = new Program().ExecuteAll(ips);
}
private List<Object> ExecuteAll(List<IPAddress> hosts)
{
Started = DateTime.Now;
var result = new List<Object>();
//Parallel.ForEach(hosts, i => SomeLongRunningNetworkTask(i));
hosts.AsParallel()
.WithDegreeOfParallelism(64)
.ForAll(i => result.Add(SomeLongRunningNetworkTask(i))
);
return result;
}
private Object SomeLongRunningNetworkTask(Object o)
{
Console.WriteLine("Start: " + DateTime.Now.Subtract(Started).TotalMilliseconds.ToString("F2") + " ms");
Thread.Sleep(60 * 1000);
Console.WriteLine("End: " + DateTime.Now.Subtract(Started).TotalMilliseconds.ToString("F2") + " ms");
return new Object();
}
}
}