Lingering will sometimes not work when you're working with non-blocking sockets. Even if the socket is set to linger and you keep tying to close until the socket doesn't return an error and the resource is no longer identifiable as type 'Socket', the socket may STILL close without sending everything.
Therefore, in the event that you are using non-blocking sockets (which is preferable if you care at all about signaling), you should set the socket as blocking (socket_set_block()) before calling to close it. This will allow everything to flush before it returns.
Dustin Oprea