[jira] Resolved: (MAHOUT-367) IllegalArgumentException in AbstractJDBCModel when requesting mostSimilarItems for an item without preferences

["Sean Owen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAHOUT-367?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sean Owen resolved MAHOUT-367.
------------------------------

       Resolution: Fixed
    Fix Version/s: 0.4
         Assignee: Sean Owen

Easy enough, I committed what I think is the right solution.

> 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
>            Assignee: Sean Owen
>             Fix For: 0.4
>
>
> 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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