ConcurrentModificationException thrown while iterating over bean definition names in DefaultListableBeanFactory#getBeansWithAnnotation(Class<? extends Annotation> annotationType) [SPR-12688]

[spring-projects-issues]

Chip Killmar opened SPR-12688 and commented

During the creation of one of our beans, we call getBeansWithAnnotation(Class<? extends Annotation> annotationType) to get a map of lazy-loaded annotated beans. This method instantiates these annotated beans using getBean(String beanName).

In our configuration, we're dynamically registering Spring beans using a post processor bean. The post processor bean receives a callback whenever one of these annotated beans is created, and dynamically registers new bean definitions.

The problem is that dynamic registration modifies List<String> beanDefinitionNames while Spring is iterating over it, causing a java.util.ConcurrentModificationException to be thrown:

Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansWithAnnotation(DefaultListableBeanFactory.java:566)
	at com.homeaway.TestConfiguration.testBean(TestConfiguration.java:43)
	at com.homeaway.TestConfiguration$$EnhancerBySpringCGLIB$$c0d0df0c.CGLIB$testBean$0(<generated>)
	at com.homeaway.TestConfiguration$$EnhancerBySpringCGLIB$$c0d0df0c$$FastClassBySpringCGLIB$$7a010a97.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:309)
	at com.homeaway.TestConfiguration$$EnhancerBySpringCGLIB$$c0d0df0c.testBean(<generated>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
	... 36 more

Spring 3.2.2.RELEASE doesn't exhibit the same behavior because it creates a local set of bean names and iterates over that:

   // 3.2.2.RELEASE, DefaultListableBeanFactory.java
   public Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType) {
     Set<String> beanNames = new LinkedHashSet<String>(getBeanDefinitionCount());
     beanNames.addAll(Arrays.asList(getBeanDefinitionNames()));
     beanNames.addAll(Arrays.asList(getSingletonNames()));
     Map<String, Object> results = new LinkedHashMap<String, Object>();
     for (String beanName : beanNames) {
          if (findAnnotationOnBean(beanName, annotationType) != null) {
               results.put(beanName, getBean(beanName));
          }
     }
     return results;
}

   // 4.1.4.RELEASE, DefaultListableBeanFactory.java
@Override
public Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType) {
     Map<String, Object> results = new LinkedHashMap<String, Object>();
     for (String beanName : this.beanDefinitionNames) {
          BeanDefinition beanDefinition = getBeanDefinition(beanName);
          if (!beanDefinition.isAbstract() && findAnnotationOnBean(beanName, annotationType) != null) {
               results.put(beanName, getBean(beanName));
          }
     }
     for (String beanName : this.manualSingletonNames) {
          if (!results.containsKey(beanName) && findAnnotationOnBean(beanName, annotationType) != null) {
               results.put(beanName, getBean(beanName));
          }
     }
     return results;
}

As a workaround for Spring 4.1.4.RELEASE, I've implemented a separate version of getBeansWithAnnotation(Class<? extends Annotation> annotationType as a custom method outside of Spring using the logic in 3.2.2.RELEASE.

I've attached an isolated test configuration and unit test that demonstrates the problem.

---

Affects: 4.1.4

Attachments:

• spr-12688.tar.gz (2.52 kB)

Issue Links:

• DefaultListableBeanFactory should allow efficient access to current bean names [SPR-12404] #17012 DefaultListableBeanFactory should allow efficient access to current bean names
• ConcurrentModificationException when executing AutowireCapableBeanFactory.createBean [SPR-13493] #18071 ConcurrentModificationException when executing AutowireCapableBeanFactory.createBean

Referenced from: commits 918bc3b, 6c47b5f

[spring-projects-issues]

Chip Killmar commented

Attaching an example Spring configuration and unit test that demonstrates the problem.

[spring-projects-issues]

Juergen Hoeller commented

Good catch! It is more efficient to talk to the local data structures directly, which was the point of #17012, but of course we need to be defensive in terms of not delegating to external code inbetween.

I've fixed this specific issue through making getBeansWithAnnotation delegate to getBeanNamesForAnnotation first (doing all access to bean name structures) and then retrieving the bean instances in a second step.

This will be available in tomorrow's 4.1.5 snapshot. Please give it a try once available...

Juergen