Does Spring Boot automatically close database connection?

By Atul Rai | Last Updated: May 21, 2023 Previous       Next

Yes, Spring Boot can automatically manage and close database connections for you. Spring Boot provides integration with various database technologies through its data access framework, Spring Data JPA or Spring Data JDBC.

When using Spring Data JPA, the underlying persistence provider (such as Hibernate) manages the database connections. By default, Spring Data JPA uses a connection pool to manage connections, and it will automatically acquire and release connections as needed. When a transaction is complete or a method annotated with @Transactional finishes its execution, the connection is released back to the connection pool.

Similarly, when using Spring Data JDBC, Spring Boot provides a connection pool and manages the connections for you. It ensures that connections are acquired and released correctly without manual intervention.

In both cases, Spring Boot takes care of managing the lifecycle of the database connections, ensuring that connections are properly closed and returned to the pool when no longer needed. This helps prevent resource leaks and improves performance by reusing existing connections from the pool.

How?

Spring Boot achieves automatic management and closing of database connections through the use of connection pooling libraries. Connection pooling is a technique that creates and maintains a pool of pre-initialized database connections, allowing applications to reuse connections instead of establishing a new connection for each database operation.

When you configure Spring Boot with a supported database, such as MySQL or PostgreSQL, it automatically sets up a connection pool for you. Spring Boot uses a connection pool library like HikariCP as the default connection pool implementation, although you can also choose other libraries such as Apache Commons DBCP or Tomcat JDBC.

The connection pool is typically configured through properties in the application’s configuration file (application.properties or application.yml). For example, in application.properties, you might have the following configuration for a MySQL database:

spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase
spring.datasource.username=dbuser
spring.datasource.password=dbpass
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.hikari.maximum-pool-size=10

In this configuration, spring.datasource.url, spring.datasource.username, spring.datasource.password, and spring.datasource.driver-class-name specify the database connection details, while spring.datasource.hikari.maximum-pool-size sets the maximum number of connections in the pool.

When your application accesses the database using Spring Data JPA or Spring Data JDBC, the connection pool manages the acquisition and release of connections. When a database operation is executed, Spring Boot retrieves a connection from the pool. After the operation is completed or the transaction is finished, Spring Boot releases the connection back to the pool.

By utilizing connection pooling, Spring Boot ensures that database connections are efficiently managed, reused, and closed when no longer needed, saving the overhead of creating a new connection for each database interaction.