Hi all, I've finished thread_safe_signals. To get thread safety you have to include an additional header file thread_safe_signals/multi_threaded.hpp and set the last template parameter to boost::signals::multi_threaded. I've done a little benchmarking. With thread-safety off and connecting 10 slots, it appears to have about the same overhead as cvs boost.signals (which is much less than the latest release of boost.signals). When 1 slot is connected, it has more overhead, a little less than a factor of 2 when running a single empty slot. Turning thread-safety on increases overhead by about 50% for the 1 slot case and 100% for the 10 slot case. It is able to invoke slots concurrently though, which should be a win if the slot is non-trivial. -- Frank