Mysql: Error: Cannot enqueue Handshake after already enqueuing a Handshake.

Created on 7 Sep 2015 · 7Comments · Source: mysqljs/mysql

function reloadQuestion() {
    var obj = {};
    connection.connect();
    connection.query("SELECT * FROM quiz", function (err, rows, fields) {
        if (err) throw err;
        for (var i = 0; i < rows.length; i++) {
            var row = rows[i];
            obj = {"id":row.id, "question":row.question, "answers":row.answers.split(", ")};
            f100.push(obj);
            arr.push(i);
        };
        shuffleArray(arr);
        newQuestion();
    });
    connection.end();
}

reloadQuestion();

its work fine, then when after a condition when try to call reloadQuestion again its got error

Error: Cannot enqueue Handshake after already enqueuing a Handshake.
    at Protocol._validateEnqueue (/home/bot/node_modules/mysql/lib/protocol/Protocol.js:202:16)
    at Protocol._enqueue (/home/bot/node_modules/mysql/lib/protocol/Protocol.js:129:13)
    at Protocol.handshake (/home/bot/node_modules/mysql/lib/protocol/Protocol.js:52:41)
    at Connection.connect (/home/bot/node_modules/mysql/lib/Connection.js:123:18)
    at reloadQuestion (/home/bot/f100.js:56:13)
    at null._onTimeout (/home/bot/f100.js:80:8)
    at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)

already try to remove connection.end(); but the problem still

question

Source

anonprophet

Most helpful comment

I think use pooling is the best way
For example:

var pool        = mysql.createPool({
    connectionLimit : 10, // default = 10
    host            : 'localhost',
    user            : 'root',
    password        : 'kensxxx',
    database        : 'fbtool'
});

router.get('/test/query', function (req, res) {
    pool.getConnection(function (err, connection) {
        connection.query("SELECT * FROM tblcomment", function (err, rows) {
            connection.release();
            if (err) throw err;

            console.log(rows.length);
            res.send(JSON.stringify(rows));
        });
    });
});

mozaa-vn on 6 Mar 2018

👍24 ❤16

All 7 comments

im fixed this using connection pool remove .connect() & . end() and using .release

anonprophet on 7 Sep 2015

👍2

I have same problem although I am not using .connect() & . end() .
Anyone help me? Thanks

huykon on 5 Mar 2018

I think use pooling is the best way
For example:

var pool        = mysql.createPool({
    connectionLimit : 10, // default = 10
    host            : 'localhost',
    user            : 'root',
    password        : 'kensxxx',
    database        : 'fbtool'
});

router.get('/test/query', function (req, res) {
    pool.getConnection(function (err, connection) {
        connection.query("SELECT * FROM tblcomment", function (err, rows) {
            connection.release();
            if (err) throw err;

            console.log(rows.length);
            res.send(JSON.stringify(rows));
        });
    });
});

mozaa-vn on 6 Mar 2018

👍24 ❤16

Hi @MrKenitvnn , Still not working with me :( . Any way help me check it?

huykon on 6 Mar 2018

I had the same issue on my end and I resolve it by removing
connection.connect(); and connection.end();

innodjet on 6 Apr 2019

👍2

Hey guys Use mysql.createPool instead of mysql.createConnection to set up teh conenction and use connection.release to end connections.

This error happens when you have multiple queries running through the program and the connections aren't closed properly after the query is resolved.

Amrithnath on 15 Jul 2019

🎉3 👍3 🚀1

-> I resolve this so that every time after connecting to the DB (Query etc.) I close the connection using this function:
(The function terminates the connection and creates the connection again)

function endCon(){
db.end( function(err) {
if (err) {console.log("Error ending the connection:",err);}

     db = mysql.createConnection({
        host: 'localhost',
        user: 'your_user',
        password: 'your_psw',
        database: 'your_DB'
           });
});

}