C++ Mutex vs Shared Mutex

What is the difference between a mutex and a shared mutex in C++?

A mutex allows only one thread to access a resource at a time, while a shared mutex allows multiple threads to read but only one to write.

When should I use a shared mutex instead of a regular mutex?

Use a shared mutex when you have multiple threads that need to read data simultaneously, but only one thread needs to write.

Can you give an example of using a shared mutex in C++?

Sure! Here's a simple example:

#include <shared_mutex>
#include <thread>
#include <iostream>

std::shared_mutex mtx;
int shared_data = 0;

void read_data() {
    std::shared_lock<std::shared_mutex> lock(mtx);
    std::cout << "Reading data: " << shared_data << std::endl;
}

void write_data(int value) {
    std::unique_lock<std::shared_mutex> lock(mtx);
    shared_data = value;
    std::cout << "Writing data: " << shared_data << std::endl;
}

This code allows multiple threads to read shared_data while ensuring exclusive access for writing.

Are there any performance considerations when using shared mutexes?

Yes, shared mutexes can improve performance in read-heavy scenarios, but they may introduce overhead due to the complexity of managing multiple readers and a single writer.