Hibernate 和 Spring 连接池默认值

Question

I am working on an application which is based on Hibernate 5.1.9.Final and Spring 4.3.6.RELEASE

What I am trying to discover is what the default values for connecting to the relational database are, such as connection_timeout, maxConnections, etc.

I am trying to understand this existing project, and I don't have any of this configuration on that, but still, I see several connections on the Database -> Postgres.

How to discover what the defaults are? Are there defaults values? And what is the default connection pool framework? C3p0?

Answer 1

The default connection pooling mechanisms in hibernate are not production, not even performance testing ready. Here is a quotation from hibernate documentation

Hibernate's own connection pooling algorithm is, however, quite rudimentary. It is intended to help you get started and is not intended for use in a production system, or even for performance testing. You should use a third party pool for best performance and stability. Just replace the hibernate.connection.pool_size property with connection pool specific settings. This will turn off Hibernate's internal pool. For example, you might like to use c3p0.

The property setting up the number of pooled connections is:

hibernate.connection.pool_size

Here is an example C3P0 configuration:

hibernate.connection.driver_class = org.postgresql.Driver
hibernate.connection.url = jdbc:postgresql://localhost/mydatabase
hibernate.connection.username = myuser
hibernate.connection.password = secret
hibernate.c3p0.min_size=5
hibernate.c3p0.max_size=20
hibernate.c3p0.timeout=1800
hibernate.c3p0.max_statements=50
hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect

recently Hikari is very popular choice for connection pooling. https://brettwooldridge.github.io/HikariCP/

Here is an example set of Hikari properties:

<property name="hikari.dataSource.cachePrepStmts">true</property>
  <property name="hikari.dataSource.prepStmtCacheSize">250</property>
  <property name="hikari.dataSource.prepStmtCacheSqlLimit">2048</property>
  <property name="hikari.dataSource.useServerPrepStmts">true</property>
  <property name="hikari.maximumPoolSize">30</property>
  <property name="hikari.idleTimeout">30000</property>

  <!-- Database connection properties -->
  <property name="hibernate.hikari.dataSourceClassName">com.mysql.jdbc.jdbc2.optional.MysqlDataSource</property>
  <property name="hikari.dataSource.url">jdbc:mysql://127.0.0.1/sample</property>
  <property name="hikari.dataSource.user">root</property>
  <property name="hikari.dataSource.password">tiger</property>

source: https://self-learning-java-tutorial.blogspot.com/2016/01/hibernate-hikaricp-example.html