ctylihuai left a comment (kamailio/kamailio#4238)
Its strange that you are seeing TCP operations in your backtrace, when you are saying that no TCP was configured for this node. Can you share the listen cfg?
Regarding the Kamailio 5.7.4 - its an old version which is not maintained anymore from the open source project. I would suggest to update to a maintained version, e.g. one of the latest 5.8.x or 6.0.x versions.
listen cfg config：
listen=tcp:PCSCF_IP:5460 #!define TCP_PROCESSES 48 tcp_async= yes # Alias name: tcp_buf_write tcp_conn_wq_max = 16384 tcp_rd_buf_size = 16384 tcp_wq_max = 16777216 #tcp_defer_accept = 5 #tcp_keepidle = 7200 #tcp_keepintvl = 75 #tcp_keecnt = 10 tcp_poll_method= epoll_lt tcp_send_timeout = 10 tcp_syncnt = 2 tcp_delayed_ack = no tcp_max_connections = 1000000 tcp_accept_haproxy=no tcp_reuse_port = yes tcp_keepalive = yes tcp_keepcnt = 3 tcp_keepidle = 120 tcp_keepintvl = 75 tcp_listen_backlog = 10240 tcp_clone_rcvbuf=1 #tcp_msg_read_timeout=120 #tcp_msg_data_timeout=120 tcp_accept_iplimit =0 tcp_connection_lifetime=3615 tcp_accept_aliases=no tcp_crlf_ping=yes tcp_accept_no_cl=yes #!ifdef TCP_PROCESSES tcp_children=TCP_PROCESSES loadmodule "tcpops" modparam("tcpops", "closed_event", 2) event_route[tcp:closed] { route(TCPEVENT); event_route[tcp:reset] { route(TCPEVENT); event_route[tcp:timeout] { route(TCPEVENT);