Each thread can use the same resolver.
@ -321,7 +321,7 @@ namespace nodetool
try
{
addr_list = tools::DNSResolver().get_ipv4(addr_str, avail, valid);
addr_list = tools::DNSResolver::instance().get_ipv4(addr_str, avail, valid);
LOG_PRINT_L4("dns_threads[" << result_index << "] DNS resolve done");
boost::this_thread::interruption_point();
}