Java/Hibernate Error: Connection leak detected. The internal connection pool has reached its maximum size and no connection is currently available

Solution 1:

I think you should also flush & close the session object before closing the factory object.

Solution 2:

Use below in your entity class @GeneratedValue(strategy = GenerationType.IDENTITY)

Solution 3:

In Student class, on Line no.14, you have declared the Id generation strategy as:

@GeneratedValue(strategy=GenerationType.AUTO)

Change it to

@GeneratedValue(strategy = GenerationType.IDENTITY)

This will remove the error.

Look in Hibernate Docs to find out which one is supported by your database. Below are all 4 Id generation strategies:

• GenerationType.AUTO: Pick an appropriate strategy for the particular database.
• GenerationType.IDENTITY: Assign primary key using database identity column.
• GenerationType.SEQUENCE: Assign primary keys using database sequence.
• GenerationType.TABLE: Assign primary keys using an underlying database table to ensure uniqueness.