void shutdown_clients(struct sender_status *ss);
void send_chunk(struct sender_client *sc, struct sender_status *ss,
size_t max_bytes_per_write, long unsigned current_chunk,
void shutdown_clients(struct sender_status *ss);
void send_chunk(struct sender_client *sc, struct sender_status *ss,
size_t max_bytes_per_write, long unsigned current_chunk,