@sheshant
Friend provide more info, How the client is connecting? Post more logs? Show us the source code?

Client side code

var socket;
$(document).ready(function(){
var n='sheshant';
 socket = io("http://hostip:4000",{query:'name='+n});

      socket.on('chatmsg', function(msg){
      var user = JSON.parse(msg);
      if(user.type=="user") {
        $("#msg_console").append("<div id='out_name'>"+user.name+"</div>"+"<div id='out_msg'>"+user.message+"<br>"+"<div class='downtimer'>"+user.time+"<br>"+user.date);   
      } else {
            $("#msg_console").append("<div id='sys_msg'>"+user.message);
            callback(n,grp);
      }
})
})

Server side code

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var date = require('date-and-time');
var mysql = require('mysql');

var pool      =    mysql.createPool({
    connectionLimit : 100, //important
    host     : 'localhost',
    user     : 'root',
    password : '',
    database : 'db',
    debug    :  false
});

io.on('connection', function(socket){
    var store =socket.handshake.query.name;
     console.log(store+" is connected");
console.log(socket.id+" is connected");
})
socket.on('disconnect', function(){
     console.log(store+" is disconnected");
console.log(socket.id+" is disconnected");
})
http.listen(4000, function(){
  console.log('listening on *:4000');
});