This is the first time I'm using boost in a multi-threaded env (linux x86_64,gcc 4).  This question may have been asked in other forms. However, from what I've been able to search (google) up, I could not get a crystal clear answer.  I'm essentially trying to use the solution provided in this page.  http://onlamp.com/pub/a/onlamp/2006/05/04/smart-pointers.html?page=5.  >From the boost documentation, it appears that this could be an  undefined operation as the global shared pointer is being read and written to by multiple threads. Is that correct ?  In case the link fails  or someone wants more details, please read on.  I've got a n reader threads and 1 writer thread.  initializion Thread :  shared_ptr< MyClass > global_ptr(createNewObject()) ; WriterThread : global_ptr.reset( createNewObject()) ReaderThreads: weak_ptr<MyClass> local_weak_ptr (globally_ptr) ; ... if(shared_ptr< MyClass > local_shared_ptr = local_weak_ptr.lock() ) {  // using local_shared_ptr. } else {     // recreate weak ptr from global ? } thanks. Rajeev