Quiz · Multithreading: An Overview · lesson 6 of 10

Quiz — two mutexes in opposite order

What can happen if two threads call lock_both(a, b) and lock_both(b, a) at once?

C++

#include <mutex>

std::mutex a;
std::mutex b;

void lock_both(std::mutex& first, std::mutex& second) {
    std::lock_guard<std::mutex> g1(first);
    std::lock_guard<std::mutex> g2(second);
}