Pool query/execute prevents script from exiting

Using this: mysql.js

function connection() {
	try {
		const mysql = require('mysql2');

		const pool = mysql.createPool({
			host: 'localhost',
			user: '',
			password: '',
			database: '',
			timezone: 'utc',
			connectionLimit: 100,
			waitForConnections: true,
			queueLimit: 0
		});

		const promisePool = pool.promise();

		return promisePool;
	} catch (error) {
		return console.log(`Could not connect - ${error}`);
	}
}

const pool = connection();

module.exports = {
	connection: async () => pool.getConnection(),
	execute: (...params) => pool.execute(...params),
	query: (...params) => pool.query(...params),
	escape: (...params) => pool.escape(...params)
};

script.js

async function testPromises() {
	test = [1, 2, 3, 4, 5, 6, 7, 3, 73, 7, 37, 7, 7];
	await db.query('SELECT * FROM test LIMIT 10');

console.log('after query');
}

testPromises();

Script never exits and keeps all records in memory indefinitely, however everything after the query executes too so it doesn’t hang on this query. How can I prevent that? I also tried:

const db = require('./mysql');
async function testPromises() {
	connection = await db.connection();
	let test2 = await connection.query('SELECT * FROM test LIMIT 10');
	connection.release();
	console.log(test2);
}

testPromises();

[izzymg]

For an HTTP server a common practice is to create a module which initializes the connection pool and exports it when it’s required, making use of Node’s module caching (effectively a singleton pattern). You can hook into something like process.on("SIGINT", pool.end) to try to gracefully quit. Otherwise keep your pool open for the duration of the process’s lifetime and query it as you wish. Mysql2 will tend to hang Node if you don’t release connections as well, so make good use of finally and the query methods.

[sidorares]

in that case not much you can do to reduce memory pressure. Maybe use separate pool with a small number of max open connections, that way it’ll act as a semaphore reducing the maximum number of the simultaneous requests processing 300mb of data ( and maybe only release back connection when data processing is done, not after the data is received )