Hi Eirc, (I was new to this mailing list, so I don't have the original email to reply directly.)
I have exact the same problem today, and finally found the reason. In our case, we add some URI to DistributedCache like you. But unfortunately the problem was the URI. When we tried to add several jars by calling addFileToClassPath, these files are actually joined by colons, which is the default path separator in java classpath. And this is the reason of failure. For example, if you have hdfs://example.com:9000/a.jar and hdfs://example.com:9000/b.jar to add to classpath, your mapred.job.classpath.files will look like (note these colons!): dfs://example.com:9000/a.jar:hdfs://example.com:9000/b.jar Then when a worker tries to add them to the classpath (search getFileClassPaths in org.apache.hadoop.mapred.TaskRunner.java), it actually adds "dfs", "//example.com", "9000/a.jar", and so on, which is not desired. Our solution is to remove "hdfs://example.com:9000" part when calling addFileToClassPath. Hope it helps! Victor
