Otherwise I get
Error: test_massively_parallel_IP_address_addition(TestAddr::TestWithNetlinkRouteSocket)
Errno::EMFILE: Too many open files - socket(2)
lib/linux/netlink/nlsocket.rb:61:in `initialize'
lib/linux/netlink/nlsocket.rb:61:in `new'
lib/linux/netlink/nlsocket.rb:61:in `initialize'
lib/linux/netlink/route.rb:21:in `initialize'
test/t_route.rb:54:in `new'
test/t_route.rb:54:in `block (4 levels) in <class:TestAddr>'