How to manage database connection pool in spring jpa?
I am using spring-boot in my web application and use spring-jpa to read/write from/to my database. It works very well but I want to understand how to manage the database connections. Below is my properties configuration for database:
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8
spring.datasource.username=user
spring.datasource.password=pwd
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.max-active=500
I have set the maximum connections to 500. When a user makes a request on my spring application, a database connection will be opened for him. After finishing the request, will spring jpa close this connection? If not, when will it close the unused connections?
I have read through the spring jpa reference document from http://docs.spring.io/spring-data/jpa/docs/current/reference/html/. But it doesn't mention anything about the connections.
Answer
When using DB connection pooling, a call to sqlconnection.close() will not necessarily close the heavyweight connection to the database, instead most often will just release the connection as re-usable in the pool. That's why it is advisable to invoke the close() on connection as soon as possible when leveraging a client side connection pool.
In your configuration, the pool will contain a maximum number of 500 connections ( it would be also good to configure maxIdle, minIdle, and minEvictableIdleTimeMillis to tune the number of ready-to-use connections and how often to release them when not used).
Some more doc here