rest api using express.js and PostgreSQL - node.js

Question

I have a script that has rest apis that gets data from a postgresql database and returns it back to the client. At the start, the script only uses the about 7mb of memory and the response time when making queries is very fast. However, as time passes by(about 1 day), the memory used by the script balloons to 170mb. And now, the queries takes more than 1 minute to respond. But when I restart the script, it is now again fast on its response. I am clueless as to why this happens. Can anybody shed light on this? Here is a portion of what my script looks like:
var port = process.env.PORT || 8000;
var router = express.Router();
router.get('/:id/from/:prevdate', function (req, res) {
var results = [];
var id = req.params.id;
var prevdate = req.params.prevdate;
pg.connect(connectionString, function (err, client, done) {
var query = client.query("some sql statement here", [id, prevdate]);
query.on('row', function (row) {
results.push(row);
});
query.on('end', function () {
client.end();
return res.json(results);
});
if (err) {
console.log(err);
}
});
});
router.get('/:id/getdata', function (req, res) {
var results = [];
var id = req.params.id;
pg.connect(connectionString, function (err, client, done) {
var query = client.query("some sql statement here", [id]);
query.on('row', function (row) {
results.push(row);
});
query.on('end', function () {
client.end();
return res.json(results);
});
if (err) {
console.log(err);
}
});
});
app.use('/restapitest', router);
app.listen(port);
console.log('Webservice started using port: ' + port);

Answer 1

You are mixing connection pooling (which uses done()) with creating single connections (which uses client.end()).
Try this:
query.on('end', function() {
done();
return res.json(results);
});
Also, since you are storing all results in memory anyway, there's no need to use events. So with proper error and connection handling, you could use this:
pg.connect(connectionString, function (err, client, done) {
var sendError = function(err) {
console.log(err);
return res.sendStatus(500);
};
if (err) return sendError(err);
client.query("some sql statement here", [id, prevdate], function(err, results) {
// Done with the client.
done();
// Handle any errors.
if (err) return sendError(err);
// Return result
return res.json(results);
});
});