Aled Sage created BROOKLYN-119:
----------------------------------
Summary: ConcurrentModificationException when persisting entity
attributes
Key: BROOKLYN-119
URL: https://issues.apache.org/jira/browse/BROOKLYN-119
Project: Brooklyn
Issue Type: Bug
Affects Versions: 0.7.0-SNAPSHOT
Reporter: Aled Sage
Priority: Minor
When running apps with persistence enabled, the log sometimes contains the an
exception like the following:
{noformat}
2015-01-15 14:47:51,025 WARN b.e.r.PersistenceExceptionHandlerImpl
[brooklyn-execmanager-RBNffgWM-169]: Problem persisting (ignoring): generate
memento for ENTITY brooklyn.entity.webapp.jboss.JBoss7ServerImpl(fQvgDCKq)
java.util.ConcurrentModificationException: null
at
java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:711)
~[na:1.8.0_25]
at
java.util.LinkedHashMap$LinkedEntryIterator.next(LinkedHashMap.java:744)
~[na:1.8.0_25]
at
java.util.LinkedHashMap$LinkedEntryIterator.next(LinkedHashMap.java:742)
~[na:1.8.0_25]
at brooklyn.event.basic.AttributeMap.asMap(AttributeMap.java:79)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:0.7.0-SNAPSHOT]
at
brooklyn.entity.basic.AbstractEntity.getAllAttributes(AbstractEntity.java:1053)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:0.7.0-SNAPSHOT]
at
brooklyn.entity.rebind.dto.MementosGenerators.newEntityMementoBuilder(MementosGenerators.java:173)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:0.7.0-SNAPSHOT]
at
brooklyn.entity.rebind.BasicEntityRebindSupport.getMementoWithProperties(BasicEntityRebindSupport.java:70)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.entity.rebind.BasicEntityRebindSupport.getMemento(BasicEntityRebindSupport.java:62)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.entity.rebind.BasicEntityRebindSupport.getMemento(BasicEntityRebindSupport.java:1)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.entity.rebind.PeriodicDeltaChangeListener.persistNow(PeriodicDeltaChangeListener.java:392)
~[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.entity.rebind.PeriodicDeltaChangeListener$1$1.call(PeriodicDeltaChangeListener.java:215)
[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.entity.rebind.PeriodicDeltaChangeListener$1$1.call(PeriodicDeltaChangeListener.java:1)
[brooklyn-core-0.7.0-SNAPSHOT.jar:na]
at
brooklyn.util.task.BasicExecutionManager$ScheduledTaskCallable$1.call(BasicExecutionManager.java:410)
[brooklyn-core-0.7.0-SNAPSHOT.jar:0.7.0-SNAPSHOT]
at
brooklyn.util.task.BasicExecutionManager$SubmissionCallable.call(BasicExecutionManager.java:469)
[brooklyn-core-0.7.0-SNAPSHOT.jar:0.7.0-SNAPSHOT]
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[na:1.8.0_25]
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[na:1.8.0_25]
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[na:1.8.0_25]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_25]
{noformat}
This means that `AttributeMap.values` was modified by another thread during
this method call, and that the `values` map is not a `ConcurrentMap`.
The field is initialised by the map being passed into the constructor (which is
intended to allow a back-end storage such as Hazelcast to be used). The comment
on the field says "Assumed to be something like a ConcurrentMap passed in", but
clearly it is being passed a `java.util.LinkedHashMap`.
The application seems to continue to behave itself. As long as the entity is
persisted again before the Brooklyn server is restarted, then it will not have
any impact. However, we should definitely fix this!
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