add a comment about the last products.persist

mengxr · mengxr · commit c9676a67994d · 2014-03-18T11:42:11.000-07:00
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

Original file line number	Diff line number	Diff line change
`@@ -220,6 +220,8 @@ class ALS private (`
`220`	`220`	`}`
`221`	`221`	`}`
`222`	`222`
	`223`	+ // The last `products` will be used twice. One to generate the last `users` and the other to
	`224`	+ // generate `productsOut`. So we cache it for better performance.
`223`	`225`	`products.persist()`
`224`	`226`
`225`	`227`	`// Flatten and cache the two final RDDs to un-block them`