Node Postgres Module not responding - node.js

Question

I have an amazon beanstalk node app that uses the postgres amazon RDS. To interface node with postgres I use node postgres. Code looks like this:
var pg = require('pg'),
done,client;
function DataObject(config,success,error) {
var PG_CONNECT = "postgres://"+config.username+":"+config.password+"#"+
config.server+":"+config.port+"/"+config.database;
self=this;
pg.connect(PG_CONNECT, function(_error, client, done) {
if(_error){ error();}
else
{
self.client = client;
self.done = done;
success();
}
});
}
DataObject.prototype.add_data = function(data,success,error) {
self=this;
this.client.query('INSERT INTO sample (data) VALUES ($1,$2)',
[data], function(_error, result) {
self.done();
success();
});
};
To use it I create my data object and then call add_data every time new data comes along. Within add_data I call 'this/self.done()' to release the connection back to the pool. Now when I repeatedly make those requests the client.query never gets back. Under what circumstance could this lead to a blocking/not responding database interface?

Answer 1

The way you are using pool is incorrect.
You are asking for a connection from pool in the function DataObject. This function acts as a constructor and is executed once per data object. Thus only one connection is asked for from the pool.
When we call add_data the first time, the query is executed and the connection is returned to the pool. Thus the consequent calls are not successful since the connection is already returned.
You can verify this by logging _error:
DataObject.prototype.add_data = function(data,success,error) {
self=this;
this.client.query('INSERT INTO sample (data) VALUES ($1,$2)',
[data], function(_error, result) {
if(_error) console.log(_error); //log the error to console
self.done();
success();
});
};
There are couple of ways you can do it differently:
Ask for a connection for every query made. Thus you'll need to move the code which ask for pool to function add_data.
Release client after performing all queries. This is a tricky way since calls are made asynchronously, you need to be careful that client is not shared i.e. no new request be made until client.query callback function is done.