add a comment about the last products.persist

yinxusen · Mar 18, 2014 · c9676a6 · c9676a6
1 parent d3a88aa
commit c9676a6
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/recommendation/ALS.scala b/mllib/src/main/scala/org/apache/spark/mllib/recommendation/ALS.scala
@@ -220,6 +220,8 @@ class ALS private (
       }
     }
 
+    // The last `products` will be used twice. One to generate the last `users` and the other to
+    // generate `productsOut`. So we cache it for better performance.
     products.persist()
 
     // Flatten and cache the two final RDDs to un-block them