[SPARK-13904] Add exit code parameter to exitExecutor()

## What changes were proposed in this pull request?

This PR adds exit code parameter to exitExecutor() so that caller can specify different exit code.

## How was this patch tested?

Existing test

rxin hbhanawat

Author: tedyu <yuzhihong@gmail.com>

Closes #12457 from tedyu/master.

core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala

@@ -64,7 +64,7 @@ private[spark] class CoarseGrainedExecutorBackend(
         // Always receive `true`. Just ignore it
       case Failure(e) =>
         logError(s"Cannot register with driver: $driverUrl", e)
-        exitExecutor()
+        exitExecutor(1)
     }(ThreadUtils.sameThread)
   }
 
@@ -81,12 +81,12 @@ private[spark] class CoarseGrainedExecutorBackend(
 
     case RegisterExecutorFailed(message) =>
       logError("Slave registration failed: " + message)
-      exitExecutor()
+      exitExecutor(1)
 
     case LaunchTask(data) =>
       if (executor == null) {
         logError("Received LaunchTask command but executor was null")
-        exitExecutor()
+        exitExecutor(1)
       } else {
         val taskDesc = ser.deserialize[TaskDescription](data.value)
         logInfo("Got assigned task " + taskDesc.taskId)
@@ -97,7 +97,7 @@ private[spark] class CoarseGrainedExecutorBackend(
     case KillTask(taskId, _, interruptThread) =>
       if (executor == null) {
         logError("Received KillTask command but executor was null")
-        exitExecutor()
+        exitExecutor(1)
       } else {
         executor.killTask(taskId, interruptThread)
       }
@@ -127,7 +127,7 @@ private[spark] class CoarseGrainedExecutorBackend(
       logInfo(s"Driver from $remoteAddress disconnected during shutdown")
     } else if (driver.exists(_.address == remoteAddress)) {
       logError(s"Driver $remoteAddress disassociated! Shutting down.")
-      exitExecutor()
+      exitExecutor(1)
     } else {
       logWarning(s"An unknown ($remoteAddress) driver disconnected.")
     }
@@ -146,7 +146,7 @@ private[spark] class CoarseGrainedExecutorBackend(
    * executor exits differently. For e.g. when an executor goes down,
    * back-end may not want to take the parent process down.
    */
-  protected def exitExecutor(): Unit = System.exit(1)
+  protected def exitExecutor(code: Int): Unit = System.exit(code)
 }
 
 private[spark] object CoarseGrainedExecutorBackend extends Logging {