setsockopt($conn->{sock}, SOL_SOCKET, SO_KEEPALIVE, 1) or confess "setsockopt keepalive: $!";
setsockopt($conn->{sock}, SOL_SOCKET, SO_LINGER, pack("ll", 0, 0)) or confess "setsockopt linger: $!";
setsockopt($conn->{sock}, IPPROTO_TCP, TCP_NODELAY, 1) or confess "setsockopt: $!";
setsockopt($conn->{sock}, SOL_SOCKET, SO_KEEPALIVE, 1) or confess "setsockopt keepalive: $!";
setsockopt($conn->{sock}, SOL_SOCKET, SO_LINGER, pack("ll", 0, 0)) or confess "setsockopt linger: $!";
setsockopt($conn->{sock}, IPPROTO_TCP, TCP_NODELAY, 1) or confess "setsockopt: $!";