IllegalArgumentException in AbstractJDBCModel when requesting mostSimilarItems
for an item without preferences
--------------------------------------------------------------------------------------------------------------
Key: MAHOUT-367
URL: https://issues.apache.org/jira/browse/MAHOUT-367
Project: Mahout
Issue Type: Bug
Components: Collaborative Filtering
Reporter: Sebastian Schelter
I'm using GenericItemBasedRecommender together with MySQLJDBCDataModel for
generating recommendations for an online shop. Whenever the recommender tries
to calculate the most similar items for an item without preferences (e.g. a
brand new product), an IllegalArgumentException is thrown as AbstractJDBCModel
tries to create a GenericItemPreferenceArray from the empty preference list.
Sample stacktrace:
java.lang.IllegalArgumentException: size is less than 1
at
org.apache.mahout.cf.taste.impl.model.GenericItemPreferenceArray.<init>(GenericItemPreferenceArray.java:49)
at
org.apache.mahout.cf.taste.impl.model.GenericItemPreferenceArray.<init>(GenericItemPreferenceArray.java:56)
at
org.apache.mahout.cf.taste.impl.model.jdbc.AbstractJDBCDataModel.getPreferencesForItem(AbstractJDBCDataModel.java:441)
at
org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.doMostSimilarItems(GenericItemBasedRecommender.java:169)
at
org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.mostSimilarItems(GenericItemBasedRecommender.java:128)
at
org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender.mostSimilarItems(GenericItemBasedRecommender.java:121)
at
de.zalando.recommendation.recommender.cf.TasteRecommenderAdapter.mostSimilarItems(TasteRecommenderAdapter.java:38)
at
de.zalando.recommendation.recommender.taste.cache.CachingRecommender.mostSimilarItems(CachingRecommender.java:39)
at
de.zalando.recommendation.recoreco.rest.RecommendationsRestController.mostSimilarItems(RecommendationsRestController.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doInvokeMethod(HandlerMethodInvoker.java:710)
at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:167)
at
org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:414)
at
org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:402)
at
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
at
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
at
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)
at
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:552)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
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