How to correctly implement the Singleton pattern in C++ with multithreading in mind?

Hello everyone! I'm a beginner C++ developer and trying to understand the Singleton pattern. I've read that it's a creational pattern that guarantees a class has only one instance and provides a global access point to it. I wrote a simple implementation for a logger: ```cpp class Logger { public: static Logger* getInstance() { if (instance == nullptr) { instance = new Logger(); } return instance; } void log(const std::string& msg) { std::cout << msg << std::endl; } private: Logger() {} static Logger* instance; }; Logger* Logger::instance = nullptr; ``` But several points bother me: 1. In a multithreaded environment, multiple instances could be created if two threads simultane