mysql will make more connections than allowed - mysql

Question

I'm using Sequelize ORM for my nodejs project and it seems there is a mistake in configuration or I'm doing something really awry with the queries... The problem is that our client will make more than 60 connections sometimes when the user is requesting a lot of information at once (graphql request with deep structure and data loaders on top for a lot of records fetched from MySQL). The pool settings should not let do that since it is configured for 10 max connections at once. The main question is how those connections appear? The app is being hosted at AWS using ELB, for MySQL we are using RDS and we can have up to 2 app instances at once, so no more than 20 connections at all. Sequelize config:
production: {
username: process.env.DB_USER,
password: process.env.DB_PASS,
database: process.env.DB_NAME,
host: process.env.DB_HOST,
dialect: 'mysql',
define: {
charset: 'utf8mb4',
collate: 'utf8mb4_general_ci',
},
pool: {
max: parseInt(process.env.DB_POOL_SIZE, 10), // 10 from ENV variables
min: 0,
acquire: 60000,
idle: 60000,
},
operatorsAliases: 0,
logging: false,
},
once there are >50 connections on our RDS client we can see that our ELB can't perform health check since it can't make new connections and return positive status from MySQL. so our app becomes unreachable.
After bombing the backend with this particular query I've fetched processlist for MySQL. Some sleeping queries will go to more than 1000 "time".
Also I'm going to attach my Sequelize connection config. It is a singleton object which will be run only once the app is loaded. But on the other hand, I'm importing models from this file everywhere in the project. But is it a mistake?
/* eslint-disable import/no-cycle */
import { Sequelize } from 'sequelize-typescript';
import databaseConfig from '#config/database';
import models from './models';
const env = process.env.NODE_ENV || 'development';
const database = (databaseConfig as any)[env];
const sequelize = new Sequelize(database.database, database.username, database.password, {
host: database.host,
dialect: database.dialect,
define: database.define,
pool: database.pool,
operatorsAliases: database.operatorsAliases,
logging: database.logging,
retry: {
match: [
/SequelizeConnectionError/,
/SequelizeConnectionRefusedError/,
/SequelizeHostNotFoundError/,
/SequelizeHostNotReachableError/,
/SequelizeInvalidConnectionError/,
/SequelizeConnectionTimedOutError/,
],
max: Infinity,
},
});
sequelize.addModels(Object.values(models));
setTimeout(() => console.log('Waiting for mysql connection...'), 200);
sequelize.sync().then(() => console.log('Mysql connection established'));
export const {
... 16 MODELS...
} = models;
export { sequelize, Sequelize };
also I'm using sequelize suggested config in .sequelizerc file to make a connection when running migrations etc..
const path = require('path');
module.exports = {
'config': path.resolve('dist', './config/database.js'),
'models-path': path.resolve('dist', './models'),
'seeders-path': path.resolve('dist', './seeders'),
'migrations-path': path.resolve('dist', './migrations')
}
What I'm missing here?