How can I use thread-local storage in C++?

How can I use thread-local storage in C++?

In C++, you can use the thread_local keyword to declare variables that are unique to each thread. This means that each thread has its own instance of the variable.

Can you give me an example of how to implement it?

Sure! Here's a simple example:

#include <iostream>
#include <thread>

thread_local int threadVar = 0;

void incrementVar() {
    threadVar++;
    std::cout << "Thread ID: " << std::this_thread::get_id() << " - Value: " << threadVar << std::endl;
}

int main() {
    std::thread t1(incrementVar);
    std::thread t2(incrementVar);
    t1.join();
    t2.join();
    return 0;
}

What happens if I don't use thread_local?

If you don't use thread_local, all threads will share the same instance of the variable, leading to potential data races and inconsistent results.

Are there any performance implications of using thread-local storage?

Yes, using thread_local can introduce some overhead due to the management of separate instances for each thread, but it can improve thread safety.