Connection Pooling in Grails 2.2.x? - grails

Question

I could not find how connection pooling is activated in Grails.
In my DataSource.groovy I have the following:
url = "jdbc:mysql://localhost/myapp?useUnicode=yes&characterEncoding=UTF-8"
username = "root"
password = ""
dialect = org.hibernate.dialect.MySQL5InnoDBDialect
pooled = true
properties {
maxActive = -1
minEvictableIdleTimeMillis=1800000
timeBetweenEvictionRunsMillis=1800000
numTestsPerEvictionRun=3
testOnBorrow=true
testWhileIdle=true
testOnReturn=true
validationQuery = "select 1"
}
Is there something else I have to do to activate connection pooling than setting pooled = true?

Answer 1

No, the pooled attribute configures pooling. If it's set to false then you will create a new connection each time, and this can take hundreds of milliseconds, so it's not advised.
You would set pooled = false when using JNDI however, since the JNDI datasource does its own pooling, so there's no need to pool twice.

Answer 2

Below is a sample from Grails DataSource documentation page:
dataSource {
pooled = true
dbCreate = "update"
url = "jdbc:mysql://localhost:3306/my_database"
driverClassName = "com.mysql.jdbc.Driver"
dialect = org.hibernate.dialect.MySQL5InnoDBDialect
username = "username"
password = "password"
properties {
jmxEnabled = true
initialSize = 5
maxActive = 50
minIdle = 5
maxIdle = 25
maxWait = 10000
maxAge = 10 * 60000
timeBetweenEvictionRunsMillis = 5000
minEvictableIdleTimeMillis = 60000
validationQuery = "SELECT 1"
validationQueryTimeout = 3
validationInterval = 15000
testOnBorrow = true
testWhileIdle = true
testOnReturn = false
jdbcInterceptors = "ConnectionState;StatementCache(max=200)"
defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED
}}
In addition to setting pooled to true, you can also tweak settings on how many connections are initialized up front (initialSize) and the maximum number of connections you would want to maintain when the load gets higher (maxActive).