Add more docs and value check

apache · Nov 24, 2017 · 0f87dd6 · 0f87dd6
1 parent c9c26ce
commit 0f87dd6
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/core/src/main/scala/org/apache/spark/internal/config/package.scala b/core/src/main/scala/org/apache/spark/internal/config/package.scala
@@ -490,8 +490,10 @@ package object config {
     ConfigBuilder("spark.shuffle.mapOutput.parallelAggregationThreshold")
       .internal()
       .doc("Multi-thread is used when the number of mappers * shuffle partitions is greater than " +
-        "or equal to this threshold.")
+        "or equal to this threshold. Note that the actual parallelism is calculated by number of " +
+        "mappers * shuffle partitions / this threshold + 1, so this threshold should be positive.")
       .intConf
+      .checkValue(v => v > 0, "The threshold should be positive.")
       .createWithDefault(10000000)
 
 }