ThreadPool.QueueUserWorkItem is not working in C# Console

I am trying to use ThreadPool in C# Console application as shown below.

static void Main(string[] args)
{
for (var i = 1; i<= 10; i++)
{
ThreadPool.QueueUserWorkItem(n =>
{
Console.WriteLine($"Start operation {n}");
Thread.Sleep(1000); // Simulate long running operation
Console.WriteLine($"Operation {n} completed");
}, i);
}
Console.ReadKey();
}

But it is showing the below error:

The type or namespace name "QueueUserWorkItem" does not exist in the namespace "ThreadPool".

What I am doing wrong or which reference I need to add. I have already used the namespace system.Threading.

I am working on .Net framework version 4.6.

I got my solution as the project name was also ThreadPool so it was not working. Now I have changed the name of project and now ThreadPool.QueueUserWorkItem is working.

Previously my project was something like this.

namespace ThreadPool
{
class Program
{
static void Main(string[] args)
{
for (var i = 1; i<= 10; i++)
{
ThreadPool.QueueUserWorkItem(n =>
{
Console.WriteLine($"Start operation {n}");
Thread.Sleep(1000); // Simulate long running operation
Console.WriteLine($"Operation {n} completed");
}, i);
}
Console.ReadKey();
}
}
}

Now I have changed it to as below and is working now.

namespace MyThreadPool
{
class Program
{
static void Main(string[] args)
{
for (var i = 1; i<= 10; i++)
{
ThreadPool.QueueUserWorkItem(n =>
{
Console.WriteLine($"Start operation {n}");
Thread.Sleep(1000); // Simulate long running operation
Console.WriteLine($"Operation {n} completed");
}, i);
}
Console.ReadKey();
}
}
}

1 Reply

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Suraj Kumar7y ago
I got my solution as the project name was also ThreadPool so it was not working. Now I have changed the name of project and now ThreadPool.QueueUserWorkItem is working.

Previously my project was something like this.
namespace ThreadPool
{
    class Program
    {
        static void Main(string[] args)
        {
            for (var i = 1;  i<= 10; i++)
            {
                ThreadPool.QueueUserWorkItem(n =>
                {
                    Console.WriteLine($"Start operation {n}");
                    Thread.Sleep(1000); // Simulate long running operation
                    Console.WriteLine($"Operation {n} completed");
                }, i);
            }
            Console.ReadKey();
        }
    }
}
Now I have changed it to as below and is working now.
namespace MyThreadPool
{
    class Program
    {
        static void Main(string[] args)
        {
            for (var i = 1;  i<= 10; i++)
            {
                ThreadPool.QueueUserWorkItem(n =>
                {
                    Console.WriteLine($"Start operation {n}");
                    Thread.Sleep(1000); // Simulate long running operation
                    Console.WriteLine($"Operation {n} completed");
                }, i);
            }
            Console.ReadKey();
        }
    }
}