kea6 multi-threading fail to send packet

logs from set of tests:

Mar 21 13:17:03 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:17:17 perf-kea-1 kea-dhcp6: message repeated 11 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:17:40 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:17:43 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:18:07 perf-kea-1 kea-dhcp6: message repeated 37 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:18:31 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:18:34 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:18:58 perf-kea-1 kea-dhcp6: message repeated 41 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:19:20 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:19:23 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:19:47 perf-kea-1 kea-dhcp6: message repeated 51 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:20:10 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:20:13 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:20:38 perf-kea-1 kea-dhcp6: message repeated 50 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:21:00 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:21:03 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:21:27 perf-kea-1 kea-dhcp6: message repeated 55 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:21:49 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:21:52 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:22:17 perf-kea-1 kea-dhcp6: message repeated 61 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:22:40 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:22:43 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:22:52 perf-kea-1 kea-dhcp6: message repeated 29 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:22:52 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:23:08 perf-kea-1 kea-dhcp6: message repeated 33 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:23:29 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:23:32 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:23:34 perf-kea-1 kea-dhcp6: message repeated 6 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:23:35 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:23:44 perf-kea-1 kea-dhcp6: message repeated 23 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:23:45 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:23:57 perf-kea-1 kea-dhcp6: message repeated 25 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:24:20 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:24:23 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:24:47 perf-kea-1 kea-dhcp6: message repeated 48 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:25:10 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:25:13 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:25:38 perf-kea-1 kea-dhcp6: message repeated 85 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:26:03 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:26:06 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:26:30 perf-kea-1 kea-dhcp6: message repeated 77 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:26:55 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:26:58 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:27:22 perf-kea-1 kea-dhcp6: message repeated 64 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:27:45 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:27:49 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:28:12 perf-kea-1 kea-dhcp6: message repeated 13 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:28:35 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:28:38 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:29:03 perf-kea-1 kea-dhcp6: message repeated 39 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:29:26 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:29:30 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:29:53 perf-kea-1 kea-dhcp6: message repeated 40 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:30:15 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:30:18 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:30:43 perf-kea-1 kea-dhcp6: message repeated 47 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:31:05 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:31:08 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:31:33 perf-kea-1 kea-dhcp6: message repeated 43 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:31:55 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:31:58 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:32:23 perf-kea-1 kea-dhcp6: message repeated 51 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:32:46 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:32:49 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:33:13 perf-kea-1 kea-dhcp6: message repeated 41 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:33:36 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:33:39 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:34:04 perf-kea-1 kea-dhcp6: message repeated 51 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:34:26 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:34:30 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:34:54 perf-kea-1 kea-dhcp6: message repeated 45 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:35:16 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:35:19 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:35:42 perf-kea-1 kea-dhcp6: message repeated 34 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:36:07 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:36:10 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:36:35 perf-kea-1 kea-dhcp6: message repeated 97 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:37:00 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:37:03 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:37:27 perf-kea-1 kea-dhcp6: message repeated 86 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:37:52 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:37:55 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:37:56 perf-kea-1 kea-dhcp6: message repeated 3 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:37:57 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:38:20 perf-kea-1 kea-dhcp6: message repeated 73 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
Mar 21 13:38:43 perf-kea-1 kea-dhcp6: FATAL [kea-dhcp6.dhcp6] DHCP6_MULTI_THREADING_WARNING multi-threading support is experimental. Don't use in production environment.
Mar 21 13:38:46 perf-kea-1 kea-dhcp6: ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument
Mar 21 13:38:57 perf-kea-1 kea-dhcp6: message repeated 13 times: [ ERROR [kea-dhcp6.packets] DHCP6_PACKET_SEND_FAIL failed to send DHCPv6 packet: pkt6 send failed: sendmsg() returned with an error: Invalid argument]
jenkins@perf-kea-1:~$ 

master branch, last git commit e24cc15c3a9af308d468e5c2fd585d66fc18b217 kea started with -N0 parameter config:

{
    "Dhcp6": {
        "control-socket": {
            "socket-name": "/tmp/control_socket",
            "socket-type": "unix"
        },
        "interfaces-config": {
            "interfaces": [
                "enp1s0f3"
            ]
        },
        "lease-database": {
            "name": "keatest",
            "password": "keatest",
            "type": "mysql",
            "user": "keatest"
        },
        "loggers": [
            {
                "name": "kea-dhcp6",
                "output_options": [
                    {
                        "output": "syslog"
                    }
                ],
                "severity": "ERROR"
            }
        ],
        "subnet6": [
            {
                "interface": "enp1s0f3",
                "pools": [
                    {
                        "pool": "2001:db8:a::1-2001:db8:a::ffff:ffff:ffff:ffff"
                    }
                ],
                "subnet": "2001:db8:a::/64"
            }
        ]
    }
}