[hibernate-issues] [Hibernate-JIRA] Created: (METAGEN-49) JPAMetaModelEntityProcessor.createMetaModelClasses calls remove within foreach loop (causing a ConcurrentModificationException)

[Robin Sander (JIRA)]

JPAMetaModelEntityProcessor.createMetaModelClasses calls remove within foreach loop (causing a ConcurrentModificationException)
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                 Key: METAGEN-49
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/METAGEN-49
             Project: Hibernate Metamodel Generator
          Issue Type: Bug
          Components: processor
    Affects Versions: 1.1.0.Final
         Environment: Hibernate 3.6.0, Java 6 (1.6.0_22), Mac OS X 10.6.5
            Reporter: Robin Sander
            Assignee: Hardy Ferentschik


Running the annotation processor causes a ConcurrentModificationException.
I'm using Maven and the maven-processor-plugin 1.3.7 but from looking into the sources I guess this bug occurs in any environment.
JPAMetaModelEntityProcessor.createMetaModelClasses iterates of a Collection<MetaEntity> using a foreach loop and calls remove
on the same collection which causes a ConcurrentModificationException.
Obviously an iterator should be used instead.

Here are the lines concerned:
{code:java} 
 Collection<MetaEntity> toProcessEntities = context.getMetaEmbeddables();
 while ( !toProcessEntities.isEmpty() ) {
  Set<MetaEntity> processedEntities = new HashSet<MetaEntity>();
  int toProcessCountBeforeLoop = toProcessEntities.size();
  for ( MetaEntity entity : toProcessEntities ) {
    // see METAGEN-36
    if ( generatedModelClasses.contains( entity.getQualifiedName() ) ) {
      toProcessEntities.remove( entity );  // XXX this causes a ConcurrentModificationException
      continue;
  }
 ...
{code}
Here is the stacktrace:
{code}
...
[INFO] diagnostic Note: Hibernate JPA 2 Static-Metamodel Generator 1.1.0.Final
An annotation processor threw an uncaught exception.
Consult the following stack trace for details.
java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
	at java.util.HashMap$ValueIterator.next(HashMap.java:822)
	at org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor.createMetaModelClasses(JPAMetaModelEntityProcessor.java:153)
	at org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor.process(JPAMetaModelEntityProcessor.java:133)
	at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:625)
	at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:554)
	at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:699)
	at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:981)
	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:727)
	at com.sun.tools.javac.main.Main.compile(Main.java:353)
	at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:115)
	at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.executeWithExceptionsHandled(AbstractAnnotationProcessorMojo.java:261)
	at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.execute(AbstractAnnotationProcessorMojo.java:129)
	at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
{code}

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