[boost] boost signals in multithreaded envirionments

Hallo boost developers, I have a question about the problems with boost signals in multithreaded environments. Is there a problem when I create some threads which notify one sink. Lets say i have several sensors, all of them running in a thread. This sensors call's a update method from the sink which is protected by a mutex. In this multithreaded case boost signals will work correct, do they? What exectly will be the problem with the class trackable in multithreaded environments. Can you explain me what will occure in that case? Thank you very much. Greetings Daniel