Enable compression by default for spills

core/src/main/scala/org/apache/spark/storage/BlockManager.scala

@@ -81,7 +81,7 @@ private[spark] class BlockManager(
   // Whether to compress RDD partitions that are stored serialized
   val compressRdds = conf.getBoolean("spark.rdd.compress", false)
   // Whether to compress shuffle output temporarily spilled to disk
-  val compressShuffleSpill = conf.getBoolean("spark.shuffle.spill.compress", false)
+  val compressShuffleSpill = conf.getBoolean("spark.shuffle.spill.compress", true)
 
   val heartBeatFrequency = BlockManager.getHeartBeatFrequency(conf)
 

docs/configuration.md

@@ -156,7 +156,7 @@ Apart from these, the following properties are also available, and may be useful
 </tr>
 <tr>
   <td>spark.shuffle.spill.compress</td>
-  <td>false</td>
+  <td>true</td>
   <td>
     Whether to compress data spilled during shuffles.
   </td>