[UIMA-1376] Fix NPE in Uima AS Aggregate while handling getMeta responses

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.3AS
• Component/s: Async Scaleout
• Assignee: Unassigned
• Reporter: Jaroslaw Cwiklik
• Created: 08/Jun/09 18:40
• Updated: 15/Sep/09 14:36
• Resolved: 25/Jun/09 17:56

Description

While merging type system from a delegate Uima AS the following exception is thrown:
6/8/09 8:59:20 AM - 32: org.apache.uima.aae.error.handler.GetMetaErrorHandler.handleError: WARNING:

{0}

java.lang.NullPointerException
at org.apache.uima.resource.CasDefinition.<init>(CasDefinition.java:66)
at org.apache.uima.resource.impl.CasManager_impl.getCasDefinition(CasManager_impl.java:94)
at org.apache.uima.resource.impl.CasManager_impl.createNewCas(CasManager_impl.java:196)
at org.apache.uima.util.CasPool.fillPool(CasPool.java:319)
at org.apache.uima.util.CasPool.<init>(CasPool.java:191)
at org.apache.uima.resource.impl.CasManager_impl.defineCasPool(CasManager_impl.java:174)
at org.apache.uima.resource.impl.CasManager_impl.defineCasPool(CasManager_impl.java:152)
at org.apache.uima.aae.EECasManager_impl.defineCasPool(EECasManager_impl.java:60)
at org.apache.uima.aae.AsynchAECasManager_impl.initialize(AsynchAECasManager_impl.java:98)
at org.apache.uima.aae.AsynchAECasManager_impl.initialize(AsynchAECasManager_impl.java:86)
at org.apache.uima.aae.controller.AggregateAnalysisEngineController_impl.mergeTypeSystem(AggregateAnalysisEngineController_impl.java:2182)
at org.apache.uima.aae.handler.input.MetadataResponseHandler_impl.handle(MetadataResponseHandler_impl.java:133)
at org.apache.uima.aae.handler.HandlerBase.delegate(HandlerBase.java:158)
at org.apache.uima.aae.handler.input.ProcessResponseHandler.handle(ProcessResponseHandler.java:673)
at org.apache.uima.adapter.jms.activemq.JmsInputChannel.onMessage(JmsInputChannel.java:665)
at org.apache.uima.adapter.jms.activemq.ConcurrentMessageListener$1.run(ConcurrentMessageListener.java:163)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)

it could be that this is caused when two threads simultaneously try to merge their typesystems. This exception happens rarely, suggesting a race condition of some sort or/and perhaps, that the core is not thread safe with respect to merging typesystems in multiple threads. The latter is just a speculation.