Mutexes.md

Mutexes

Simple Explanation

A Mutex (short for mutual exclusion) is a synchronization primitive that allows multiple threads to access a shared resource while preventing simultaneous access to it. It is similar to a lock but can be used across multiple processes. Mutexes are commonly used in multi-threaded and multi-process applications to avoid race conditions and ensure that only one thread or process can access a shared resource at any given time.

Deep Explanation

A Mutex is a synchronization object that allows multiple threads to access a shared resource while preventing simultaneous access to it. It is a kernel object, meaning that it is created and managed by the operating system. A Mutex can be owned by a single thread or process at any given time. When a thread or process requests ownership of a Mutex, the operating system checks whether it is available. If it is available, the requesting thread or process takes ownership of the Mutex and can access the shared resource. If it is not available, the requesting thread or process is blocked until it becomes available.

In C# and .NET, you can use the Mutex class to create and use Mutexes. The Mutex class provides methods for creating and releasing Mutexes, as well as methods for waiting for ownership and releasing ownership of Mutexes. You can create a Mutex using the Mutex constructor, and acquire ownership of a Mutex using the WaitOne method. Once you have ownership of a Mutex, you can access the shared resource, and release ownership of the Mutex using the ReleaseMutex method.

Examples

using System;
using System.Threading;

class Program
{
    static Mutex mutex = new Mutex();

    static void Main()
    {
        // Create 5 threads to access the shared resource
        for (int i = 0; i < 5; i++)
        {
            Thread t = new Thread(DoWork);
            t.Start();
        }

        Console.ReadKey();
    }

    static void DoWork()
    {
        mutex.WaitOne(); // Acquire ownership of the Mutex

        // Access the shared resource here
        Console.WriteLine("Thread {0} is accessing the shared resource.", Thread.CurrentThread.ManagedThreadId);
        Thread.Sleep(1000);

        mutex.ReleaseMutex(); // Release ownership of the Mutex
    }
}