Configuration mysql node js error Can not enqueue Query after fatal error

Question

I have an application nodejs running on top of a pm2.

My application has a strange behavior where I can not identify the problem, for some time running, 3 4 or 5 days the application when trying to do a simple login where it needs a connection with the database the following error occurs:

Can not enqueue Query after fatal error

I have done everything possible to try to identify the cause of this problem, and it has not been identified a drop in the database server.

Someone could try to help, maybe it's the way that getting the connection to the bank is wrong.

Database connection configuration db.js

const mysql = require('mysql');

const connection = mysql.createConnection({
    connectionLimit : 20,
    host     : '******',
    port     : 3306,
    user     : '******',
    password : '******',
    database : '******'
});

connection.connect(function(err) {
    if (err) {
        console.log('Conexão com banco ocorreu erro. ' + err + ' ' + err.code);
        return;
    }
    console.log('Conexão com banco ok!');
});

module.exports = connection;

route usuario

var express = require('express');
var router = express.Router();

var usuarioController  = require('../controllers/usuario-controller');

router.get('/find/:id', usuarioController.findUsuario);

module.exports = router;

usuarioController

var db = require('../models/db');

var usuarioController = {


    findUsuario: function(req, res) {

        var codigoPessoa = req.params.id;

        var sql = "SELECT p.codigoPessoa As codigo, "+
                  "  p.nome AS nome "+
                  "  FROM tpessoa p, "+
                  "      tusuario u "+
                  "  WHERE p.codigoPessoa = u.codigoPessoa "+
                  "  AND u.codigoPessoa = " + codigoPessoa;

        db.query(sql, function (err, rows) {
            if (err) {

                var message = err.message;

                return res.status(500).send(message);

            } else {

                res.status(200).json(rows);
            }
        });
    },
};

module.exports = usuarioController;

Error

Error: Connection lost: The server closed the connection.
    at Protocol.end (/home/softaction/apps_nodejs/node_modules/mysql/lib/protocol/Protocol.js:112:13)
    at Socket.<anonymous> (/home/softaction/apps_nodejs/node_modules/mysql/lib/Connection.js:97:28)
    at Socket.<anonymous> (/home/softaction/apps_nodejs/node_modules/mysql/lib/Connection.js:502:10)
    at emitNone (events.js:111:20)
    at Socket.emit (events.js:208:7)
    at endReadableNT (_stream_readable.js:1064:12)
    at args.(anonymous function) (/opt/nvm/versions/node/v8.11.3/lib/node_modules/pm2/node_modules/event-loop-inspector/index.js:138:29)
    at _combinedTickCallback (internal/process/next_tick.js:138:11)
    at process._tickCallback (internal/process/next_tick.js:180:9)
Error: Cannot enqueue Query after fatal error.
    at Protocol._validateEnqueue (/home/softaction/apps_nodejs/node_modules/mysql/lib/protocol/Protocol.js:200:16)
    at Protocol._enqueue (/home/softaction/apps_nodejs/node_modules/mysql/lib/protocol/Protocol.js:138:13)
    at Connection.query (/home/softaction/apps_nodejs/node_modules/mysql/lib/Connection.js:200:25)
    at Strategy._verify (/home/softaction/apps_nodejs/security/autenticacao.js:66:16)
    at Strategy.authenticate (/home/softaction/apps_nodejs/node_modules/passport-local/lib/strategy.js:88:12)
    at attempt (/home/softaction/apps_nodejs/node_modules/passport/lib/middleware/authenticate.js:361:16)
    at authenticate (/home/softaction/apps_nodejs/node_modules/passport/lib/middleware/authenticate.js:362:7)

My database connection configuration file is in a separate folder in the project.

Example:

-app
--models
---db.js
--controllers
---usuario-controller.js
--routes
---usuario-route.js

score 0 · Accepted Answer · answered Feb 26 '19 at 16:08

0

The common way to handle this with seems to use a pool of connections.

You can see examples based on the same problem you have in this post. One of the answers there shows a way to override the query method so that you don't need to rewrite each call with getConnection/release.

You can probably test this with a local DB:

start the DB
start the server
try a login (or a mocked route that queries something)
ensure it works
kill/restart the DB
try the route again
ensure you have the same error
implement the solution based on the link above
test again and check the problem is gone

answered Feb 26 '19 at 16:08

Stock Overflaw

3,203
1
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14

Thanks for the response @Stock Overflaw, I'll do the tests and post the results. – Ger Feb 26 '19 at 16:32
It worked perfectly, thank you very much for the help. I did according to the post that indicated, the guys are grade 10 – Ger Feb 26 '19 at 23:05

score 0 · Answer 2 · answered Mar 30 '21 at 00:58

0

I had this same problem, found this, tested it, and it worked. It's an NPM module called serverless-mysql.

answered Mar 30 '21 at 00:58

Taylor Evanson

384
4
16

score 0 · Answer 3 · edited Sep 03 '23 at 09:17

0

Use createPool for making connection.

edited Sep 03 '23 at 09:17

Yunnosch

26,130
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answered Sep 03 '23 at 08:29

Akshat kumar Singh

1

Configuration mysql node js error Can not enqueue Query after fatal error

3 Answers3