Hi,

I'm running the RecommenderServlet on my machine and I sending requests for
different users id.
For example:
http://michal:57000/RecommenderServlet?userID=010232120.

It usually works, and I'm getting recommendations. However, for some userids
(which exists on the file), I'm getting this error:

HTTP ERROR 500

Problem accessing /RecommenderServlet. Reason:

    Server Error

Caused by:

java.lang.IllegalArgumentException
        at java.util.PriorityQueue.<init>(PriorityQueue.java:135)
        at 
org.apache.mahout.cf.taste.impl.recommender.TopItems.getTopItems(TopItems.java:48)
        at 
org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender.recommend(GenericUserBasedRecommender.java:90)
        at 
org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender.recommend(AbstractRecommender.java:52)
        at 
org.apache.mahout.cf.taste.impl.recommender.CachingRecommender$RecommendationRetriever.get(CachingRecommender.java:190)
        at 
org.apache.mahout.cf.taste.impl.recommender.CachingRecommender$RecommendationRetriever.get(CachingRecommender.java:177)
        at 
org.apache.mahout.cf.taste.impl.common.Cache.getAndCacheValue(Cache.java:101)
        at org.apache.mahout.cf.taste.impl.common.Cache.get(Cache.java:77)
        at 
org.apache.mahout.cf.taste.impl.recommender.CachingRecommender.recommend(CachingRecommender.java:114)
        at 
org.apache.mahout.cf.taste.impl.recommender.CachingRecommender.recommend(CachingRecommender.java:96)
        at 
org.apache.mahout.cf.taste.example.grouplens.GroupLensRecommender.recommend(GroupLensRecommender.java:85)
        at 
org.apache.mahout.cf.taste.web.RecommenderServlet.doGet(RecommenderServlet.java:99)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at 
org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:530)
        at 
org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:426)
        at 
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:118)
        at 
org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:495)
        at 
org.eclipse.jetty.server.session.SessionHandler.handle(SessionHandler.java:179)
        at 
org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:930)
        at 
org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:361)
        at 
org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:864)
        at 
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:116)
        at 
org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:243)
        at 
org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:126)
        at 
org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:112)
        at org.eclipse.jetty.server.Server.handle(Server.java:337)
        at 
org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:552)
        at 
org.eclipse.jetty.server.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:979)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:533)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:203)
        at 
org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:399)
        at 
org.eclipse.jetty.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:437)
        at 
org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:435)
        at java.lang.Thread.run(Thread.java:619)


any idea?

thanks,
Michal

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