Limiting the number of threads executing a method at a single time

We have a situation where we want to limit the number of paralell requests our application can make to its application server. We have potentially 100+ background threads running that will want to at some point make a call to the application server but only want 5 threads to be able to call SendMessage() (or whatever the method will be) at any one time. What is the best way of achieving this?

I have considered开发者_如何学JAVA using some sort of gatekeeper object that blocks threads coming into the method until the number of threads executing in it has dropped below the threshold. Would this be a reasonable solution or am I overlooking the fact that this might be dirty/dangerous?

We are developing in C#.NET 3.5.

Thanks,

Steve

Use a semaphore

http://msdn.microsoft.com/en-us/library/system.threading.semaphore.aspx

Limits the number of threads that can access a resource or pool of resources concurrently.

You want a semaphore... System.Threading.Semaphore

public static class MyClass
{
    private static Semaphore sem = new Semaphore(5, 5);

    public static void SendMessage()
    {
        sem.WaitOne();

        try
        {
        }
        finally
        {
            sem.Release(1);
        }
    }
}

Alternatively, if you only want a single thread to be able to call a method at a given time, .NET also exposes a concept equivalent with java's synchronized attribute:

[System.Runtime.CompilerServices.MethodImpl(MethodImpl.Synchronized)]

The Semaphore class was designed for exactly this scenario.

Design Pattern Approach: - Use command pattern with five Executor threads and wrap your requests in Command classes.