node-mysql doesn't reuse connections - node.js

Question

I'm using the connection pool in this way:
var pool = mysql.createPool({
host: config.db.host,
port: config.db.port,
user: config.db.user,
password: config.db.password,
database: config.db.database,
connectionLimit: config.db.connectionLimit
});
exports.api_point = function(req, res) {
pool.getConnection(function(err, connection) {
if (err) {
console.error('error acquiring connection', err);
var result = {};
result.error = err.code;
res.json(result);
return;
} else {
var query = connection.query('SELECT * FROM tableName', function(err, rows) {
connection.release();
var result = {};
if (err) {
console.error('error executing query: ' + err.stack);
result.error = err.message;
} else {
result.data = rows;
}
res.json(result);
return;
});
}
});
};
Problem:
Yet, after all the connections (defined by connectionLimit, e.g. 20) are created, the next call to pool.getConnection() hangs until Express returns: "GET /api_point - - ms - -" (after ~10s).
I've tried replacing connection.release(); with connection.destroy(); with no effect.
How can I solve this?
node-mysql version:
"mysql": "~2.5.1",
Btw. I track connections being created with:
var connCount = 0;
pool.on('connection', function(connection) {
console.log('connCount:', ++connCount);
});

Answer 1

Whatever I changed, nothing seemed to work until I switched to using "express-myconnection" as middleware (as described here: http://teknosains.com/i/simple-crud-nodejs-mysql).
In short: you get the connection from the request and no need to release it afterwards as the middleware cares about that.
So, my code is now (only important parts):
app.js:
var myconnection = require('express-myconnection');
var mysql = require('mysql');
app.use(
myconnection(mysql, {
host: config.db.host,
port: config.db.port,
user: config.db.user,
password: config.db.password,
database: config.db.database,
connectionLimit: config.db.connectionLimit
}, 'request')
);
api.js:
exports.api_point = function(req, res) {
req.getConnection(function(err, connection) {
if (err) {
console.error('error acquiring connection', err);
var result = {};
result.error = err.code;
res.json(result);
return;
} else {
var query = connection.query('SELECT * FROM tableName', function(err, rows) {
var result = {};
if (err) {
console.error('error executing query: ' + err.stack);
result.error = err.message;
} else {
result.data = rows;
}
res.json(result);
return;
});
}
});
};