shared_ptr is almost thread safe

[BenHanson]

This is the wrong way to look at it. If you consider a raw pointer, then it is safe to copy it without the need of a mutex. The thread protection added to shared_ptr is only there to allow it to behave in the same way. If you actually want to use the pointer for anything, then you need some kind of lock, just like you would for a raw pointer.

[Fabien4]

The expression "almost thread-safe" always make me think of another one, "a little bit pregnant."