[SPARK-9737] [YARN] Add the suggested configuration when required executor...

[SPARK-9737] [YARN] Add the suggested configuration when required executor memory is above the max threshold of this cluster on YARN mode

Author: Yadong Qi <qiyadong2010@gmail.com>

Closes #8028 from watermen/SPARK-9737 and squashes the following commits:

48bdf3d [Yadong Qi] Add suggested configuration.

yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala

@@ -203,12 +203,14 @@ private[spark] class Client(
     val executorMem = args.executorMemory + executorMemoryOverhead
     if (executorMem > maxMem) {
       throw new IllegalArgumentException(s"Required executor memory (${args.executorMemory}" +
-        s"+$executorMemoryOverhead MB) is above the max threshold ($maxMem MB) of this cluster!")
+        s"+$executorMemoryOverhead MB) is above the max threshold ($maxMem MB) of this cluster! " +
+        "Please increase the value of 'yarn.scheduler.maximum-allocation-mb'.")
     }
     val amMem = args.amMemory + amMemoryOverhead
     if (amMem > maxMem) {
       throw new IllegalArgumentException(s"Required AM memory (${args.amMemory}" +
-        s"+$amMemoryOverhead MB) is above the max threshold ($maxMem MB) of this cluster!")
+        s"+$amMemoryOverhead MB) is above the max threshold ($maxMem MB) of this cluster! " +
+        "Please increase the value of 'yarn.scheduler.maximum-allocation-mb'.")
     }
     logInfo("Will allocate AM container, with %d MB memory including %d MB overhead".format(
       amMem,