help request: The number of udp socket is not released about apisix HOT 2 OPEN

version: "3"
services:
  apisix:
    image: apache/apisix:${APISIX_IMAGE_TAG:-3.2.0-debian}
    restart: always
    volumes:
      - ./apisix_conf/config.yaml:/usr/local/apisix/conf/config.yaml:ro
    depends_on:
      - etcd
    network_mode: host

  etcd:
    image: bitnami/etcd:3.4.15
    restart: always
    volumes:
      - etcd_data:/bitnami/etcd
    environment:
      ETCD_ENABLE_V2: "true"
      ALLOW_NONE_AUTHENTICATION: "yes"
      ETCD_ADVERTISE_CLIENT_URLS: "http://etcd:2379"
      ETCD_LISTEN_CLIENT_URLS: "http://0.0.0.0:2379"
    network_mode: host

  prometheus:
    image: prom/prometheus:v2.25.0
    restart: always
    volumes:
      - ./prometheus_conf/prometheus.yml:/etc/prometheus/prometheus.yml
    network_mode: host
  grafana:
    image: grafana/grafana:7.3.7
    restart: always
    volumes:
      - "./grafana_conf/provisioning:/etc/grafana/provisioning"
      - "./grafana_conf/dashboards:/var/lib/grafana/dashboards"
      - "./grafana_conf/config/grafana.ini:/etc/grafana/grafana.ini"
    network_mode: host

volumes:
  etcd_data:
    driver: local

apisix:
  node_listen: 9080              # APISIX listening port
  enable_ipv6: false

  enable_control: true
  control:
    ip: "0.0.0.0"
    port: 9092

  stream_proxy:
    only: false
    udp:
      - 9997
      - 9996
deployment:
  admin:
    allow_admin:               # http://nginx.org/en/docs/http/ngx_http_access_module.html#allow
      - 0.0.0.0/0              # We need to restrict ip access rules for security. 0.0.0.0/0 is for test.

    admin_key:
      - name: "admin"
        key: edd1c9f034335f136f87ad84b625c8f1
        role: admin                 # admin: manage all configuration data

      - name: "viewer"
        key: 4054f7cf07e344346cd3f287985e76a2
        role: viewer

  etcd:
    host:                           # it's possible to define multiple etcd hosts addresses of the same etcd cluster.
      - "http://127.0.0.1:2379"          # multiple etcd address
    prefix: "/apisix"               # apisix configurations prefix
    timeout: 30                     # 30 seconds

plugin_attr:
  prometheus:
    export_addr:
      ip: "0.0.0.0"
      port: 9091

curl http://127.0.0.1:9180/apisix/admin/stream_routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "upstream": {
        "nodes": {
            "192.168.1.80:9999": 1
        },
        "type": "roundrobin"
    },
	"server_port":9997
}'

version: '3'
services:
  nginx:
   image: openresty/openresty:1.19.9.1-14-buster-fat
   restart: always
   network_mode: host
   environment:
       - TZ=Asia/Shanghai
   volumes:
    - ./conf:/usr/local/openresty/nginx/conf
    - ./nginx/logs:/usr/local/openresty/nginx/logs

#user  nobody;
#worker_processes 1;

# Enables the use of JIT for regular expressions to speed-up their processing.
pcre_jit on;



#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    # Enables or disables the use of underscores in client request header fields.
    # When the use of underscores is disabled, request header fields whose names contain underscores are marked as invalid and become subject to the ignore_invalid_headers directive.
    # underscores_in_headers off;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

        # Log in JSON Format
        # log_format nginxlog_json escape=json '{ "timestamp": "$time_iso8601", '
        # '"remote_addr": "$remote_addr", '
        #  '"body_bytes_sent": $body_bytes_sent, '
        #  '"request_time": $request_time, '
        #  '"response_status": $status, '
        #  '"request": "$request", '
        #  '"request_method": "$request_method", '
        #  '"host": "$host",'
        #  '"upstream_addr": "$upstream_addr",'
        #  '"http_x_forwarded_for": "$http_x_forwarded_for",'
        #  '"http_referrer": "$http_referer", '
        #  '"http_user_agent": "$http_user_agent", '
        #  '"http_version": "$server_protocol", '
        #  '"nginx_access": true }';
        # access_log /dev/stdout nginxlog_json;

    # See Move default writable paths to a dedicated directory (#119)
    # https://github.com/openresty/docker-openresty/issues/119
    client_body_temp_path /var/run/openresty/nginx-client-body;
    proxy_temp_path       /var/run/openresty/nginx-proxy;
    fastcgi_temp_path     /var/run/openresty/nginx-fastcgi;
    uwsgi_temp_path       /var/run/openresty/nginx-uwsgi;
    scgi_temp_path        /var/run/openresty/nginx-scgi;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;

    # Don't reveal OpenResty version to clients.
    # server_tokens off;
}




stream {
 server {
            listen 9998 udp;
            proxy_pass 192.168.1.80:9999;
            proxy_timeout 1s;
            proxy_responses 1;
        }

}

package main

import (
	"fmt"

	"net"
)

func main() {
	socket, err := net.ListenUDP("udp4", &net.UDPAddr{
		IP:   net.IPv4(0, 0, 0, 0),
		Port: 9999,
	})
	if err != nil {
		fmt.Println("监听失败!", err)
	}
	defer socket.Close()
	for {
		// 读取数据
		data := make([]byte, 4096)
		read, remoteAddr, err := socket.ReadFromUDP(data)
		if err != nil {
			fmt.Println("读取数据失败!", err)
			continue
		}
		fmt.Println(read, remoteAddr)
		fmt.Printf("%s\n\n", data)
		// 发送数据
		senddata := []byte("hello client!")
		_, err = socket.WriteToUDP(senddata, remoteAddr)
		if err != nil {
			fmt.Println("发送数据失败!", err)
			return
		}
	}
}