[SPARK-9388] [YARN] Make executor info log messages easier to read.

Author: Marcelo Vanzin <[email protected]>

Closes #7706 from vanzin/SPARK-9388 and squashes the following commits:

028b990 [Marcelo Vanzin] Single log statement.
3c5fb6a [Marcelo Vanzin] YARN not Yarn.
5bcd7a0 [Marcelo Vanzin] [SPARK-9388] [yarn] Make executor info log messages easier to read.

Author: Marcelo Vanzin

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

@@ -767,7 +767,7 @@ private[spark] class Client(
     amContainer.setCommands(printableCommands)
 
     logDebug("===============================================================================")
-    logDebug("Yarn AM launch context:")
+    logDebug("YARN AM launch context:")
     logDebug(s"    user class: ${Option(args.userClass).getOrElse("N/A")}")
     logDebug("    env:")
     launchEnv.foreach { case (k, v) => logDebug(s"        $k -> $v") }

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

@@ -86,10 +86,17 @@ class ExecutorRunnable(
     val commands = prepareCommand(masterAddress, slaveId, hostname, executorMemory, executorCores,
       appId, localResources)
 
-    logInfo(s"Setting up executor with environment: $env")
-    logInfo("Setting up executor with commands: " + commands)
-    ctx.setCommands(commands)
+    logInfo(s"""
+      |===============================================================================
+      |YARN executor launch context:
+      |  env:
+      |${env.map { case (k, v) => s"    $k -> $v\n" }.mkString}
+      |  command:
+      |    ${commands.mkString(" ")}
+      |===============================================================================
+      """.stripMargin)
 
+    ctx.setCommands(commands)
     ctx.setApplicationACLs(YarnSparkHadoopUtil.getApplicationAclsForYarn(securityMgr))
 
     // If external shuffle service is enabled, register with the Yarn shuffle service already