Decreases the reference count of the asynchronous @queue by 1.
If the reference count went to 0, the @queue will be destroyed
and the memory allocated will be freed. So you are not allowed
to use the @queue afterwards, as it might have disappeared.
You do not need to hold the lock to call this function.
Decreases the reference count of the asynchronous @queue by 1.
If the reference count went to 0, the @queue will be destroyed and the memory allocated will be freed. So you are not allowed to use the @queue afterwards, as it might have disappeared. You do not need to hold the lock to call this function.