How can mutual deadlocks be prevented in multithreaded applications?

Deadlocks occur when two or more threads wait for each other, holding resources, and none can proceed. To prevent their occurrence, the following approaches can be used:

• Avoid nested locks: minimize the number of mutexes acquired simultaneously.
• Order resource acquisition: always acquire mutexes in the same order across all threads.
• Use timeouts when acquiring locks: if a resource is unavailable, the thread releases already acquired locks and retries.
• Apply detection and recovery algorithms: periodically check for deadlocks and take action.
• Use higher-level synchronization primitives: for example, lock-free data structures or atomic operations.

Example of resource ordering:

std::mutex mtx1, mtx2;

void thread_func() {
    std::lock(mtx1, mtx2); // Acquire both mutexes simultaneously
    std::lock_guard<std::mutex> lock1(mtx1, std::adopt_lock);
    std::lock_guard<std::mutex> lock2(mtx2, std::adopt_lock);
    // Work with resources
}

Using std::lock helps avoid deadlocks when acquiring multiple mutexes.