What are some examples of data races in C++?

What are some examples of data races in C++?

Data races occur when two or more threads access shared data simultaneously, and at least one thread modifies it. For example, if two threads increment a shared counter without proper synchronization, it can lead to inconsistent results.

Can you give me a code example of a data race?

Sure! Here's a simple example:

#include <iostream>
#include <thread>

int counter = 0;

void increment() {
    for (int i = 0; i < 1000; ++i) {
        ++counter;
    }
}

int main() {
    std::thread t1(increment);
    std::thread t2(increment);
    t1.join();
    t2.join();
    std::cout << "Final counter value: " << counter << std::endl;
    return 0;
}

In this code, both threads increment the counter variable without synchronization, leading to a data race.

How can I prevent data races in my code?

You can prevent data races by using synchronization mechanisms like mutexes, locks, or atomic operations. For example, wrapping the increment operation in a mutex lock ensures that only one thread can modify the counter at a time.

What are mutexes and how do they work?

Mutexes, or mutual exclusions, are synchronization primitives that prevent multiple threads from accessing a shared resource simultaneously. When a thread locks a mutex, other threads trying to lock it will be blocked until the mutex is unlocked.