Initialize BeanFactoryPostProcessors as lazily as possible [SPR-596]

[spring-projects-issues]

Matthew Sgarlata opened SPR-596 and commented

I was going to post a question about this on the user list, but after further testing I'm convinced this is a bug and not me being stupid :) The PropertyPlaceHolderConfigurer is working fine for most of my beans, but is not working for the special "messageSource" bean which, as you know, has special meaning in the Spring framework.

Before I get started, a little background: I am using the ReloadableResourceBundleMessageSource which I have subclassed and added a boolean property called "development" to. If the value is set to true, each request to the resource bundle will go to the hard drive. If set to false, the bundle is cached in memory.

Now that we have some background, let me describe how to reproduce the error. First, I setup a simple test class called ScoreboardCommandlineLauncher that was configured like this (see attached file for source):

<bean
id="scoreboardCommandlineLauncher"
class="com.spider.scoreboard.ScoreboardCommandlineLauncher">
<property name="development">
<value>${development}</value>
</property>
</bean>

<bean
id="messageSource"
class="com.spider.scoreboard.framework.ScoreboardMessageSource"
dependency-check="none">
<property name="basenames">
<list>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardDefaults</value>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardImageResources</value>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardMessageResources</value>
</list>
</property>
<property name="development">
<value>true</value>

<!-- NOTE I AM NOT USING THE PropertyPlaceholderConfigurer SO THAT MY TEST WILL RUN SUCCESSFULLY
<value>${development}</value>
-->

</property>

</bean>

I use the launcher to launch the application, and then invoke itself with all of Spring's autowiring, etc. In the Java source, you will see I just do System.out.println(getDevelopment()); which prints out "true" as expected.

Now I remove the hardcoded "true" value to use the PropertyPlaceholderConfigurer just like the scoreboardCommandlineLauncher bean so my context looks like this:

<bean
id="scoreboardCommandlineLauncher"
class="com.spider.scoreboard.ScoreboardCommandlineLauncher">
<property name="development">
<value>${development}</value>
</property>
</bean>

<bean
id="messageSource"
class="com.spider.scoreboard.framework.ScoreboardMessageSource"
dependency-check="none">
<property name="basenames">
<list>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardDefaults</value>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardImageResources</value>
<value>file:c:/eclipse/workspace/scoreboard/web/WEB-INF/ScoreboardMessageResources</value>
</list>
</property>
<property name="development">

<!-- NOT HARDCODING ANYMORE
<value>true</value>
-->

    <value>${development}</value>
</property>

</bean>

Now I get an exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageSource' defined in URL [file:c:/eclipse/workspace/Scoreboard/web/WEB-INF/commandlineContext.xml]: Error setting property values; nested exception is org.springframework.beans.PropertyAccessExceptionsException: PropertyAccessExceptionsException (1 errors); nested propertyAccessExceptions are: [org.springframework.beans.TypeMismatchException: Failed to convert property value of type [java.lang.String] to required type [boolean] for property 'development'; nested exception is java.lang.IllegalArgumentException: ${development}]
PropertyAccessExceptionsException (1 errors)
org.springframework.beans.TypeMismatchException: Failed to convert property value of type [java.lang.String] to required type [boolean] for property 'development'; nested exception is java.lang.IllegalArgumentException: ${development}
java.lang.IllegalArgumentException: ${development}
at sun.beans.editors.BoolEditor.setAsText(BoolEditor.java:43)
at org.springframework.beans.BeanWrapperImpl.doTypeConversionIfNecessary(BeanWrapperImpl.java:874)
at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:711)
at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:617)
at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:758)
at org.springframework.beans.BeanWrapperImpl.setPropertyValues(BeanWrapperImpl.java:785)
at org.springframework.beans.BeanWrapperImpl.setPropertyValues(BeanWrapperImpl.java:774)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:784)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:601)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:258)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:193)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:240)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:163)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByName(AbstractAutowireCapableBeanFactory.java:621)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:589)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:258)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:193)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:240)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:163)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByName(AbstractAutowireCapableBeanFactory.java:621)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:589)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:258)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:193)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:240)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:163)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.addBeanToResultMap(DefaultListableBeanFactory.java:204)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:163)
at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:526)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:338)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:286)
at org.springframework.web.context.support.XmlWebApplicationContext.refresh(XmlWebApplicationContext.java:131)
at com.spider.scoreboard.configuration.ScoreboardApplicationContext.refresh(ScoreboardApplicationContext.java:71)
at com.spider.scoreboard.framework.Launcher.launch(Launcher.java:25)
at com.spider.scoreboard.ScoreboardCommandlineLauncher.main(ScoreboardCommandlineLauncher.java:31)

As you can see, the post processors are trying to be invoked... but as part of that invocation they're instantiating the special messageSource bean, but that depends on the post processors... oh boy.

FYI, below is my definition of the PropertyPlaceholderConfigurer. The home: prefix is for the location is a special Resource type I defined, but as I demonstrated earlier, the PropertyPlaceholderConfigurer is definitely able to get to that Resource, because I was able to successfully print out "true" in my example.

<bean
id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
dependency-check="none">
<property name="locations">
<list>
<value>home:conf/scoreboardconfig.properties</value>
</list>
</property>

<!-- equivalent to load-on-startup in web.xml. Need to make sure this
post processor runs before any other BeanFactoryPostProcessors -->
<property name="order">
<value>1</value>
</property>
</bean>
To make things more interesting, I'm using autowiring by name in some contexts and not in others, and I have about 3 or 4 contexts. If you need more info or more of my context definitions let me know.

---

Affects: 1.1.3

Attachments:

• ScoreboardCommandlineLauncher.java (1.21 kB)

[spring-projects-issues]

Matthew Sgarlata commented

ScoreboardCommandlineLauncher.java mentioned in the bug report

[spring-projects-issues]

Juergen Hoeller commented

Looks like you have some BeanFactoryPostProcessors defined in your context that are marked to be autowired by name. This causes the "messageSource" bean to be initialized before any of the BeanFactoryPostProcessors gets invoked, which includes the PropertyPlaceholderConfigurer.

No BeanFactoryPostProcessor should need a reference to a bean that in turn depends on another BeanFactoryPostProcessor having been executed. The reason is that all BeanFactoryPostProcessors get instantiated and wired before the first one of them gets applied to the context's internal BeanFactory.

Juergen

[spring-projects-issues]

Matthew Sgarlata commented

That's true; I do have a BeanFactoryPostProcessor that is autowired by name. However, it's not dependent on the messageSource bean. Why must the messageSource bean be instantiated before the BeanFactoryPostProcessors are run?

[spring-projects-issues]

Matthew Sgarlata commented

Disregard my previous comment... I checked and one of my BeanFactoryPostProcessors indirectly depends on the messageSource bean. However, I have that post processor set to run after the PropertyPlaceholderConfigurer. I think I understand the current implementation, but I think it should be refined to handle this case.

If I understand correctly, the current implementation runs like this:

1. Instantiate all BeanFactoryPostProcessors
2. Wire all BeanFactoryPostProcessors
3. Apply the BeanFactoryPostProcessors in order

I think this sequence is more robust:

1. Find all the BeanFactoryPostProcessors
2. Arrange the post processors with those that implement Ordered first (in ascending Order), followed by those that do not implement Ordered
3. For each BeanFactoryPostProcessor from Improve annotation processing thread-safety #2,
   a) Instantiate the BeanFactoryPostProcessor
   b) Wire the processor
   c) apply the processor

What do you think?

[spring-projects-issues]

Juergen Hoeller commented

I've refined the invocation of BeanFactoryPostProcessors to:

• first fetch all bean names of BeanFactoryPostProcessors
• then instantiate, wire and sort the ones that implement Ordered
• then invoke all those instances that implement Ordered
• then instantiate, wire and invoke all remaining BeanFactoryPostProcessors, one by one

All BeanFactoryPostProcessors that implement the Ordered interface are still created all at once, before any of them gets invoked, which needs to happen for properly sorting them according to their Ordered value. But all other BeanFactoryPostProcessors get created separately, so can benefit from the services of earlier BeanFactoryPostProcessors (for example, placeholder resolution).

Juergen