When used for serialize the shared pointer, memory leak occurs. I am not sure that is due to the internal bug or the wrong use of serialization library. The following is test code: ============================================================================ ====== #include <iostream> #include <cstddef> #include <fstream> #include <string> #include <cstdio> #include #include #include #include #include class A{ private: friend class boost::serialization::access; int x; template<class Archive> void serialize(Archive& ar, const unsigned int /* file version */) { ar & x; } public: static int count; A(){++count; std::cout<<"A ctor"<> spa; } spa.reset(); std::cout << std::endl; return 0; } ============================================================================ ====== The output is: A ctor A dtor A ctor Valgrind report memory leak of 8 bytes, just the size of class A.