Hello struct A {} // executes before spawning any boost threads shared_ptr<A> sp(new A()); weak_ptr<A> wp(sp); // then in thread1 sp.reset(); // in thread thread2 shared_ptr<A> sp2(wp.lock()); Is the above code thread safe ? Is sp2 always either a default initilized shared_ptr<A> or a valid shared_ptr to the instance of A initially referenced by sp ? I couldn't find documentation on weak_ptr thread safety issues just on shared_ptr. I am unable to determine from the documentation what is the intended behaivour for the above code. I could look into the boost code and/or test it but I want to know not how it works but how it's intended to work (portably and all) :) Thank you. -- Mihai RUSU Email: dizzy@roedu.net GPG : http://dizzy.roedu.net/dizzy-gpg.txt WWW: http://dizzy.roedu.net "Linux is obsolete" -- AST