[UIMA-1580] Synchronize AsynchAECasManager initialize() method to fix NPE while merging type systems

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.3AS
• Component/s: Async Scaleout
• Assignee: Jaroslaw Cwiklik
• Reporter: Jaroslaw Cwiklik
• Created: 21/Sep/09 13:41
• Updated: 21/Sep/09 14:11
• Resolved: 21/Sep/09 14:11

Description

A NPE exception occurs intermittently while merging type systems. There seems to be a race condition where multiple threads attempt to initialize cas pools. The result is an exception that looks like this:

org.apache.uima.aae.error.AsynchAEException: java.lang.NullPointerException
at org.apache.uima.aae.controller.AggregateAnalysisEngineController_impl.mergeTypeSystem(AggregateAnalysisEngineController_impl.java:2430)
at org.apache.uima.aae.handler.input.MetadataResponseHandler_impl.handle(MetadataResponseHandler_impl.java:140)
at org.apache.uima.aae.handler.input.MetadataRequestHandler_impl.handle(MetadataRequestHandler_impl.java:78)
at org.apache.uima.aae.handler.HandlerBase.delegate(HandlerBase.java:149)
at org.apache.uima.aae.handler.input.ProcessResponseHandler.handle(ProcessResponseHandler.java:664)
at org.apache.uima.aae.handler.HandlerBase.delegate(HandlerBase.java:149)
at org.apache.uima.aae.handler.input.ProcessRequestHandler_impl.handle(ProcessRequestHandler_impl.java:951)
at org.apache.uima.aae.spi.transport.vm.UimaVmMessageListener.onMessage(UimaVmMessageListener.java:107)
at org.apache.uima.aae.spi.transport.vm.UimaVmMessageDispatcher$1.run(UimaVmMessageDispatcher.java:70)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: 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:161)