Hi I'm using boost::detail::spinlock (boost-1.81) in code that compiles on both Visual Studio and gcc. I've hit a problem on the gcc build where the underlying spinlock member (v_) in spinlock_gcc_atomic.hpp isn't an atomic variable and isn't explicitly initialised (BOOST_DETAIL_SPINLOCK_INIT is defined, but there's no initializer and no constructor). v_ is declared as a non-atomic unsigned char and atomic operations use gcc intrinsics in that file. So v_ needs to be explicitly initialized to 0. When the lock method is called, it just spins as a result. This may be work-in-progress or am I misunderstanding? It seems such a glaring omission. The STL version of the spinlock uses std::atomic which does initialize v_ because it's wrapped up in the atomic template. Also there is a scoped_lock nested class within the boost spinlock. Why have an additional lock guard? Surely std::scoped_lock should be sufficient (or is it there just for testing - if so please comment it). I can overcome the problem (without modifying spinlock_gcc_atomic.hpp) by trying to acquire the lock when I create it and releasing it regardless. Is this a bug in that file? Thanks Cliff