Connection pool - Connection leaks!!!

Background:

Opening a database connection is a resource intensive and time consuming operation. Connection pooling is a boon to performance since it increases the performance by reusing the database connection instead of creating a new connection for every request.

So what is a connection pool and how does it work?

It is a pool of open database connections. When a new connection request comes in, the pool manager checks if the pool contains any unused connections and returns one if available. If  all the connections in the pool are busy and the maximum size has not been reached, a new connection is created and added to the pool. When the pool reaches its maximum size, the connection requests will be being queued up until a connection in the pool becomes available or the connection will be times out.

Parameters of a connection pool

There are 4 parameters that control the behavior if a connection pool

• Connect timeout

It controls the wait period when a new connection is requested.  If this timeout expires, an exception will be thrown.

• Min pool size

Initial number of connections that will be added to the pool. Say if you set it to 5, there will be 5 connections available readily to server the requests. So the user requests won’t have to wait for the database connection to establish.

• Max pool size

It is the maximum size that a connection pool can grow.  If you set it to 100, the connection pool will grow from the min size to the max size based on the user requests. After it reached the max size, the requests will start queued up.

• Pooling

It lets you to control if you want to sue the connection pooling or not. It is controlled by the key words true or false based on your requirement.

What is a connection leak?

When the application doesn't close the database connection correctly and consistently, it is called as connection leaks. Eventually you will be thrown with some kind of exception or connection failures.

Fix for connection  leaks

Ensure that the database connections are always closed in your code.