javascript - node Cron with callback getting Cannot enqueue Handshake after invoking quit error -

i trying query db in particular interval. using node corn. creating connection every minute , close once query completed. works first minute, next minute throws error of cannot enqueue handshake after invoking quit, using callback. 1 correct doing wrong

app.js

var scontroller = require('./scontroller');  cron.schedule('* * * * *',function(){   console.log("i running every minute");   var params ="dddd";   scontroller.updatedb(params,function(err,res){   console.log("xxxx");  });  }); 

scontroller.js

var smodel = require('./smodel'); var scontroller = function(){}  scontroller.prototype.updatedb = function(params,callback){     smodel.updatedb(params,function(res,err){         if(res){             console.log("kkk");         }         callback(err,res);     }); } module.exports = new scontroller(); 

smodel.js

var connection = mysql.createconnection(mysqlconfig); function mysqlconnect() {     connection.connect(); } function mysqlclose() {     if(!connection._protocol._ended){         connection.end();     } } var smodel = function() {};  smodel.prototype.updatedb = function(params,callback){     updatedb(params, function(err, res) {         callback(err,res);     }); }; function updatedb(params,callback){     var query = 'select * tablename';     mysqlconnect();     connection.query(query,function(err,rows,fields){         if(!err){             console.log(rows.length);         }          callback(err,rows);     });     mysqlclose(); }  module.exports = new smodel(); 

short answer

you should use mysql connections pool. offical doc https://github.com/mysqljs/mysql#pooling-connections

long answer

server take enough time & resource create connection. pool save connection instance , reuse. see info https://en.wikipedia.org/wiki/connection_pool

wiki