Can we create 300,000 threads in a C# application and run it on a PC?

Question

I am trying to imitate a scenario where 300,000 consumers are accessing a server. So I am trying to create the pseudo clients, by repeatedly querying the server from the concurrent threads.

But the first hurdle to be cleared is, whether it is possible to run 300,000 threads on a PC? Here is a code which I am using to see intially how many max threads I can get, and later then replace the test function with the actual function:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace CheckThread
{
    class Program
    {
        static int count;

        public static void TestThread(int i)
        {
            while (true)
            {
                Console.Write("\rThread Executing : {0}", i);
                Thread.Sleep(500);
            }
        }

        static void Main(string[] args)
        {
            count = 0;
            int limit = 0;
            if (args.Length != 1)
            {
                Console.WriteLine("Usage CheckThread <number of threads>");
                return;
            }
            else
            {
                limit = Convert.ToInt32(args[0]);
            }
            Console.WriteLine();
            while (count < limit)
            {
                ThreadStart newThread = new ThreadStart(delegate { TestThread(count); });
                Thread mythread = new Thread(newThread);
                mythread.Start();
                Console.WriteLine("Thread # {0}", count++);
            }

            while (true)
            {
                Thread.Sleep(30*1000);
            }
        } // end of main
    } // end of CheckThread class
} // end of namespace

Now what I am trying might be unrealistic, but still, if there is a way out to do it and you know, then please help me.

Looks like a duplicate of http://stackoverflow.com/questions/145312/maximum-number-of-threads-in-a-net-app — holtavolt, Jun 07 '11 at 14:18
I am sorry that I didnt clarify the purpose too well. My setup is a server-client setup. I want to stress the client and not the server. In the setup, the processes give there request to the client process running and the client process will in turn forward the request to the server to be serviced. But I get the point we all are converging to, that creating these many threads on one machine is unrealistic and not recommended. Moreover, my motive to create a stress on the client by intending to have these threads executed atleast once every 1 min seems to be wanting too much! :( — Andy_MSFT, Jun 07 '11 at 17:30

score 6 · Accepted Answer · answered Jun 07 '11 at 14:26

Each thread will create its own stack and local storage, you are looking at roughly 512k of stack space per thread on a 32bit OS, I think the stack space doubles on a 64 bit OS. A quick back of the spreadsheet calc gives us 146.484375 gigs of stack space for your 300k clients.

So, no, don't create 300k threads, but rather use the threadpool to simulate 300k requests, although tbh I think you would be better off with several test clients spamming your server through a network interface.

There are a lot of web load-testing tools available. Good starting point : http://www.webperformance.com/library/reports/TestingAspDotNet/

score 4 · Answer 2 · answered Jun 07 '11 at 14:21

4

You can alter the maximum nunmber of threads by calling the ThreadPool.SetMaxThreads method. 300,000 threads will probably make your PC explode*

*This is probably an exaggeration

answered Jun 07 '11 at 14:21

Ben Robinson

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This has nothing to do with the question as he isn't using the ThreadPool. – Sven Jun 07 '11 at 14:30
1

Probably an exaggeration, but he would need something like 300 gigs of ram to keep that many threads in memory. – Alex Moore Jun 07 '11 at 14:30

score 3 · Answer 3 · answered Jun 07 '11 at 14:35

3

Language-agnostic answer:

The better way to probably go about this is using the Reactor pattern, with a maximum of 1 or 2 concurrent threads per core.

answered Jun 07 '11 at 14:35

Evert

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If you are going to use the Reactor pattern this might be helpful: http://www.robertsindall.co.uk/blog/the-reactor-pattern-using-c-sharp/ – Robs Jun 12 '11 at 17:44

score 1 · Answer 4 · answered Jun 07 '11 at 14:27

1

As .net commits the entire stack (1MB) for each clr thread; as Ben says, your PC may actually explode. Or possibly OoM.

answered Jun 07 '11 at 14:27

dashton

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score 0 · Answer 5 · answered Jun 07 '11 at 15:39

Well, what was the result of your test when you tried to create 300K threads? I'm not going to try it on mine!

You could not connect up 300K clients at once anyway because there are not enough sockets available on a single server, (hence farming).

I have done some server testing and, by tweaking the registry to make more sockets available, I have had 24K sockets connected to a server, all one one box. That was somewhat what I was expecting since the server<>client connection requires one socket object at each end and there are only 64K sockets available. I did not attempt to create 24K threads for my testing, I used a client thread class that opened/closed connections on multiple client socket objects in a list.

Rgds, Martin

Actually frankly telling you.. i couldnt even go anywhere near to that mark! I incremented the number of threads in intervals.. So the maximum i reached is around 5k threads. — Andy_MSFT, Jun 07 '11 at 16:47

Can we create 300,000 threads in a C# application and run it on a PC?

5 Answers5