How to avoid and deal with deadlocks in C++ multi-threaded programming?

Avoiding and handling deadlocks in C++ multi-threaded programming Deadlock avoidance strategies: Avoid circular waits Implement deadlock prevention or avoidance mechanisms Deadlock detection and recovery: Detect deadlock situations and take steps to resume the program, such as terminating threads or unlocking resources

How to avoid and deal with deadlocks in C++ multi-threaded programming

Preface

Deadlock is a problem often encountered in multi-threaded programming. It will cause the program to stall. If not handled in time, it may cause the program to crash. This article will introduce strategies and techniques for avoiding and dealing with deadlocks in C++ multi-threaded programming, and provide practical cases for demonstration.

Strategies to avoid deadlock

• Avoid circular waiting: Ensure that no thread waits indefinitely for another thread to release a resource.
• Deadlock prevention: Avoid deadlocks by enforcing sequential access to resources.
• Deadlock avoidance: Check for potential deadlock situations at runtime and take steps to avoid them.
• Deadlock detection and recovery: If a deadlock occurs, the program can be detected and recovered to minimize the impact.

Practical case

The following is a simple C++ program that demonstrates deadlock:

#include <thread>
#include <mutex>
#include <iostream>

std::mutex m1, m2;

void thread1() {
    m1.lock();
    std::cout << "Thread 1 acquired lock m1" << std::endl;
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    m2.lock();
    std::cout << "Thread 1 acquired lock m2" << std::endl;
    m1.unlock();
    m2.unlock();
}

void thread2() {
    m2.lock();
    std::cout << "Thread 2 acquired lock m2" << std::endl;
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    m1.lock();
    std::cout << "Thread 2 acquired lock m1" << std::endl;
    m2.unlock();
    m1.unlock();
}

int main() {
    std::thread t1(thread1);
    std::thread t2(thread2);
    t1.join();
    t2.join();
    return 0;
}

Running this program will cause a deadlock because The two threads wait for each other to release the lock.

Handling deadlock

• Deadlock detection: Regularly check the status of the program to detect whether there is a deadlock.
• Deadlock recovery: If a deadlock is detected, steps can be taken to recover the program, such as forcefully terminating a thread or unlocking resources.

Conclusion

Avoiding and handling deadlocks is critical to ensuring the robustness of C++ multi-threaded applications. By following the strategies and techniques described, you can minimize the likelihood of deadlocks and ensure they are handled correctly when they occur.

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