Re: Singleton_pattern and Thread Safety

HI All ,

i have a query using given singleton that its not thread Safe ?

Since function getInstance() is returning the static object singleton
class
AS far my knowlege, static object is intialized only first time when
control
reaches there. The second time control Thread reached there , compiler
skipps the initialization part.

http://en.wikipedia.org/wiki/Singleton_pattern

// This version solves the problems of the minimalist Singleton above,
// but strictly speaking only in a single-threaded environment,
// and use in a multithreaded environment when relying on the ABI
// may still pose problems at program termination time.

class Singleton
{
private:
   Singleton() {}
   ~Singleton() {}
   Singleton(const Singleton&); // intentionally undefined
   Singleton& operator=(const Singleton&); // intentionally undefined

public:
   static Singleton&getInstance();
};

// Source file (.cpp)
Singleton& Singleton::getInstance()
{
   // Static Variables are initialized only first time Thread of
   // Execution reaches here first time.
   static Singleton instance;
   return instance;
}

Thx

Pallav Singh