In general, Boost.Fiber synchronization objects can neither be moved nor copied. A synchronization object acts as a mutually-agreed rendezvous point between different fibers. If such an object were copied somewhere else, the new copy would have no consumers. If such an object were moved somewhere else, leaving the original instance in an unspecified state, existing consumers would behave strangely.

The fiber synchronization objects provided by this library will, by default, safely synchronize fibers running on different threads. However, this level of synchronization can be removed (for performance) by building the library with BOOST_FIBERS_NO_ATOMICS defined. When the library is built with that macro, you must ensure that all the fibers referencing a particular synchronization object are running in the same thread.