静态类数据成员的线程安全

Question

Can I assume thread-safety for static class data members in C++? In the following example, is SetCounter thread-safe?

class Foo {
public:
  static void SetCounter(int c) { counter = c; }  
private:
  static int counter = 0;
}

Answer 1

Thread-safety refers to making actions independent of other actions to avoid race conditions. If you have 2 threads, one calling SetCounter(1) and the other calling SetCounter(2) , you can't guarantee what counter will be set to. You'd need to use a mutex/lock on the value to prevent it from being modified by other threads. If you're using libraries like boost, you can refer to the Synchronization page . Otherwise, use your own mutex to toggle whether it's locked or unlocked.