Hi Witgo, Thanks a lot for your reply.
In my second test, the user features and product features were loaded from the file system directly,which means I did not use ALS here, and this problem happened at the loading data stage. The way I am asking the question was a little bit miss leading, this problem might not be ALS specific. As far as I had discovered, it might related to the usage of master memory, since I could solve this problem by increase the master memory size, or reduce the number of partitions. But I am still waiting for a better explanation :) Thank you again. Sue -- View this message in context: http://apache-spark-developers-list.1001551.n3.nabble.com/MLlib-ALS-Errors-communicating-with-MapOutputTracker-tp6740p6758.html Sent from the Apache Spark Developers List mailing list archive at Nabble.com.