Greetings Frank, boosters, Currently using a signal with a boost::signals2:dummy_mutex works well only in single-threaded programs. I'm wondering if it can be made a little more useful. I have an use case with a single global signal, where all slots and connections are setup on program start. Afterwards a bunch of threads are fired, and each of them can call the signal's operator(). There are no more connections added/removed, only signal invocations. According to the workflow described here: http://www.boost.org/doc/libs/1_41_0/doc/html/signals2/thread-safety.html#id... ...it seems that a dummy_mutex should be enough, since the slot list is never modified. It turns out it's not - I'm getting assertion failures in nolock_cleanup_connections() because the _shared_state.unique() requirement is sometimes violated. Because using a real mutex will significantly degrade both performance and concurrency, I'm wondering if this assertion is really necessary. In this case it should be safe to continue even if the uniqueness is violated, because the connection list is never modified. And I think my use case is quite common :) - Peter