std::lock_guard vs. std::scoped_lock: Which Should You Choose?

std::lock_guard vs. std::scoped_lock: When to Use Each

C 17 introduced std::scoped_lock, a new lock class that appears similar to the existing std::lock_guard. While both classes provide thread synchronization capabilities, there are key differences to consider when selecting the appropriate option.

std::lock_guard

std::lock_guard is designed for situations where you need to lock a single mutex for a specific scope. It's simple to use and enforces the automatic unlocking of the mutex when the scope exits. However, it only handles a single mutex at a time.

std::scoped_lock

std::scoped_lock, on the other hand, is a more versatile class that can lock multiple mutexes concurrently. Its variadic template allows you to specify the mutexes you want to lock. Additionally, if you don't specify any mutexes, std::scoped_lock essentially becomes a no-op.

When to Use Which

Generally, here are some guidelines for choosing between std::lock_guard and std::scoped_lock:

• Use std::lock_guard when you need to lock a single mutex for an entire scope. This ensures type safety and avoids potential runtime errors.
• Use std::scoped_lock when you need to lock multiple mutexes concurrently or handle situations where you may not need to lock any mutexes.

Additional Considerations

While std::lock_guard has less flexibility, its simplicity and compile-time checks can help reduce the chances of runtime errors. If you require more advanced locking scenarios that involve multiple mutexes or conditional unlocking, std::scoped_lock provides greater flexibility and control.

Conclusion

Understanding the differences between std::lock_guard and std::scoped_lock is crucial for choosing the best option for your specific threading requirements. By considering the number of mutexes involved and the potential for runtime errors, you can optimize your code and ensure proper thread synchronization.

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