Spring - Do all beans get processed?

Question

I have a beans.xml file for an LDAP application that I am writing. I am allowing the user the choice of several LdapContextSource(s). For each one I have a different bean, e.g.

<bean id="ldapTemplate" class="yyy.LdapTemplate">
      <constructor-arg ref="contextSource1" />
</bean>
<bean id="contextSource1" class="xxx.LdapContextSource">
      ...
</bean>
<bean id="contextSource2" class="xxx.LdapContextSource">
      ...
</bean>
<bean id="contextSource3" class="xxx.LdapContextSource">
      ...
</bean>

You can see that only one of these context source beans gets instantiated, because only one is referred to by the ldapTemplate bean. However, when I run my application, my Spring log messages in stdout provide information about each context source, even though only one is depended on.

Jan 25, 2011 11:56:36 AM org.springframework.ldap.core.support.AbstractContextSource afterPropertiesSet INFO: Property 'userDn' not set - anonymous context will be used for read-write operations Jan 25, 2011 11:56:37 AM org.springframework.ldap.core.support.AbstractContextSource afterPropertiesSet INFO: Property 'userDn' not set - anonymous context will be used for read-write operations Jan 25, 2011 11:56:37 AM org.springframework.ldap.core.support.AbstractContextSource afterPropertiesSet INFO: Property 'userDn' not set - anonymous context will be used for read-write operations

My questions are:

(1) What is Spring doing with the context sources that are not referred to / depended on? They should never be instantiated in my application, and it worries me that Spring is providing log information for each of these beans.

(2) Should I comment out the context source beans that are not used in the application? What are the consequences of leaving them uncommented? What is the standard practice?

Thanks,
ktm

Answer 1

Maybe you could check out Lazy Loading of Beans. Here is the relevant explanation from the Spring 2.5.x docs...

The default behavior for ApplicationContext implementations is to eagerly pre-instantiate all singleton beans at startup. Pre-instantiation means that an ApplicationContext will eagerly create and configure all of its singleton beans as part of its initialization process. Generally this is a good thing, because it means that any errors in the configuration or in the surrounding environment will be discovered immediately (as opposed to possibly hours or even days down the line).

However, there are times when this behavior is not what is wanted. If you do not want a singleton bean to be pre-instantiated when using an ApplicationContext, you can selectively control this by marking a bean definition as lazy-initialized. A lazily-initialized bean indicates to the IoC container whether or not a bean instance should be created at startup or when it is first requested.

For the sake of completness here is an example...

<bean id="contextSource1" class="xxx.LdapContextSource" lazy-init="true"/>