Shangru Li created MAHOUT-2096: ---------------------------------- Summary: next() Called On Possible Empty iterator() Key: MAHOUT-2096 URL: https://issues.apache.org/jira/browse/MAHOUT-2096 Project: Mahout Issue Type: Bug Components: Algorithms Reporter: Shangru Li
Consider this function: {quote} protected void reduce ( VarIntWritable index, Iterable<VarLongWritable> ids, Context ctx) throws IOException, InterruptedException { ctx.write(index, ids.iterator().next()); } {quote} The line `_ctx.write(index, ids.iterator().next());_` does not check for empty iterator when calling the next() function, which could result in an exception. Function can be found on the GitHub repository [here|[https://github.com/apache/mahout/blob/754068bc3ac62bcf4b9b656cd4a6f413b29b18df/community/mahout-mr/mr/src/main/java/org/apache/mahout/cf/taste/hadoop/als/ParallelALSFactorizationJob.java#L395].] Line 395, in file _/src/main/java/org/apache/mahout/cf/taste/hadoop/als/ParallelALSFactorizationJob.java_ -- This message was sent by Atlassian Jira (v8.3.4#803005)