Configuring HikariCP in a Grails 3.3.X Application

This post will show how to use a HikariCP JDBC connection pool in a Grails 3 application. By default, GORM for Hibernate uses a Tomcat JDBC connection pool when you bootstrap your app using grails' create-app command. Switching to HikariCP is simple. Remove the Tomcat JDBC dependency in build.gradle```` runtime "org.apache.tomcat:tomcat-jdbc" ```And replace it with the HikariCP dependency as follows:``` runtime "com.zaxxer:HikariCP:3.2.0" ```Just like Tomcat JDBC, HikariCP config properties can be set in application.ymlunder thedatasource.properties` key. An example of specifying the poolName is shown below:``` dataSource: properties: poolName: ‘grails-hikari’