What are semaphores in C# and how do they work?

What are semaphores in C# and how do they work?

Semaphores in C# are synchronization primitives that control access to a resource by multiple threads. They maintain a count that represents the number of threads that can access a resource concurrently.

Can you give me an example of how to implement a semaphore in C#?

Sure! Here's a simple example:

using System;
using System.Threading;

class Program
{
    static Semaphore semaphore = new Semaphore(2, 2);

    static void AccessResource(int threadNumber)
    {
        Console.WriteLine($"Thread {threadNumber} is waiting to access the resource.");
        semaphore.WaitOne(); // Wait until it is safe to enter.
        Console.WriteLine($"Thread {threadNumber} has entered the resource.");
        Thread.Sleep(2000); // Simulate some work.
        Console.WriteLine($"Thread {threadNumber} is leaving the resource.");
        semaphore.Release(); // Release the semaphore.
    }

    static void Main()
    {
        for (int i = 1; i <= 5; i++)
        {
            int threadNumber = i;
            new Thread(() => AccessResource(threadNumber)).Start();
        }
    }
}

What is the difference between a semaphore and a mutex?

A semaphore allows multiple threads to access a resource concurrently, while a mutex allows only one thread to access a resource at a time. Semaphores are more flexible for managing multiple threads.