To help with shutdown of multi-threaded programs nanomsg provides the nn_term() function which informs all the open sockets that process termination is underway.
If a socket is blocked inside a blocking function, such as nn_recv(3), it will be unblocked and ETERM error will be returned to the user. Similarly, any subsequent attempt to invoke a socket function other than nn_close(3) after nn_term() was called will result in ETERM error.
If waiting for NN_SNDFD or NN_RCVFD using a polling function, such as poll() or select(), the call will unblock with both NN_SNDFD and NN_RCVFD signaled.
The nn_term() function itself is non-blocking.