Migration to Tomcat 8: InstanceAlreadyExistsException datasource

Vadim R picture Vadim R · Feb 3, 2015 · Viewed 12.6k times · Source

I have a question about context config in Tomcat 8. I migrating project from Tomcat 7 to 8 and have unusual problem: if nothing change in config I caught an error:

    "2015-02-03 12:05:48,310 FIRST_ADMIN ERROR web.context.ContextLoader:331 
-> Context initialization failed org.springframework.jmx.export.UnableToRegisterMBeanException: 
    Unable to register MBean [org.apache.tomcat.dbcp.dbcp2.BasicDataSource@434990dd]
     with key 'dataSource'; nested exception is 
    javax.management.InstanceAlreadyExistsException:  
    Catalina:type=DataSource,host=localhost,context=/first-
    admin,class=javax.sql.DataSource,name="jdbc/datasource/first"

Part of context:

<Resource name="jdbc/datasource/first"
              auth="Container"
              type="javax.sql.DataSource"
              poolPreparedStatements="true"
              initialSize="25"
              maxActive="100"
              maxIdle="100"
              minIdle="25"
              username="us"
              password="pa"
              driverClassName="com.mysql.jdbc.Driver"
              validationQuery="select 1"
              testOnBorrow="true"
          url="jdbc:mysql://localhost:3306/firstproject?useUnicode=true&amp;characterEncoding=UTF-8&amp;profileSQL=false&amp;autoSlowLog=false&amp;slowQueryThresholdMillis=100&amp;autoReconnect=true"/>

So, it's works in tomcat 7 without any problem. In Tomcat 8 I can solve this problem in 2 ways:

  1. By adding to resource: singleton = "false";
  2. By adding to resource: factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"

If I clearly understand tomcat creates datasource for my app and for jmx, but in Tomcat 7 it was single object, in Tomcat 8 it must be different. So my question is why that situation has happened? I couldn't find any information of this change in documentation. And I'm interesting what is better: create single datasource (I think so) or create several by factory.

Answer

Radi Radichev picture Radi Radichev · Apr 22, 2016

We had the same problem. We declared our data source as a spring bean, and it looks like both spring and the bean itself try to register an Mbean which leads to this conflict. All we had to do is configure our Mbean Exporter like this:

@Bean
public AnnotationMBeanExporter annotationMBeanExporter() {
    AnnotationMBeanExporter annotationMBeanExporter = new AnnotationMBeanExporter();
    annotationMBeanExporter.addExcludedBean("dataSource");
    return annotationMBeanExporter;
}

Although I suppose setting the registration policy to:

annotationMBeanExporter.setRegistrationPolicy(RegistrationPolicy.IGNORE_EXISTING);

might also work.