Incorporate feedback from mateiz:

- we do not need getEnvOrEmpty
- Instead of saving SPARK_NONDAEMON_JAVA_OPTS, it would be better to modify the scripts to use a different variable name for the JAVA_OPTS they do eventually use

core/src/main/scala/spark/deploy/worker/ExecutorRunner.scala

@@ -75,10 +75,10 @@ private[spark] class ExecutorRunner(
 
   def buildCommandSeq(): Seq[String] = {
     val command = appDesc.command
-    val runner = if (getEnvOrEmpty("JAVA_HOME") == "") {
+    val runner = if (System.getenv("JAVA_HOME") == null) {
       "java"
     } else {
-      getEnvOrEmpty("JAVA_HOME") + "/bin/java"
+      System.getenv("JAVA_HOME") + "/bin/java"
     }
     // SPARK-698: do not call the run.cmd script, as process.destroy()
     // fails to kill a process tree on Windows
@@ -91,29 +91,19 @@ private[spark] class ExecutorRunner(
    * way the JAVA_OPTS are assembled there.
    */
   def buildJavaOpts(): Seq[String] = {
-    val _javaLibPath = if (getEnvOrEmpty("SPARK_LIBRARY_PATH") == "") {
+    val _javaLibPath = if (System.getenv("SPARK_LIBRARY_PATH") == null) {
       ""
     } else {
-      "-Djava.library.path=" + getEnvOrEmpty("SPARK_LIBRARY_PATH")
+      "-Djava.library.path=" + System.getenv("SPARK_LIBRARY_PATH")
     }
     
     Seq("-cp", 
-        getEnvOrEmpty("CLASSPATH"), 
-        // SPARK_JAVA_OPTS is overwritten with SPARK_DAEMON_JAVA_OPTS for running the worker
-        getEnvOrEmpty("SPARK_NONDAEMON_JAVA_OPTS"), 
+        System.getenv("CLASSPATH"), 
+        System.getenv("SPARK_JAVA_OPTS"), 
         _javaLibPath,
         "-Xms" + memory.toString + "M",
         "-Xmx" + memory.toString + "M")
-    .filter(_ != "")
-  }
-  
-  def getEnvOrEmpty(key: String): String = {
-    val result = System.getenv(key)
-    if (result == null) {
-      ""
-    } else {
-      result
-    }
+    .filter(_ != null)
   }
 
   /** Spawn a thread that will redirect a given stream to a file */

run

@@ -22,9 +22,10 @@ fi
 # values for that; it doesn't need a lot
 if [ "$1" = "spark.deploy.master.Master" -o "$1" = "spark.deploy.worker.Worker" ]; then
   SPARK_MEM=${SPARK_DAEMON_MEMORY:-512m}
-  # Backup current SPARK_JAVA_OPTS for use in ExecutorRunner.scala
-  SPARK_NONDAEMON_JAVA_OPTS=$SPARK_JAVA_OPTS
-  SPARK_JAVA_OPTS=$SPARK_DAEMON_JAVA_OPTS   # Empty by default
+  # Do not overwrite SPARK_JAVA_OPTS environment variable in this script
+  OUR_JAVA_OPTS=$SPARK_DAEMON_JAVA_OPTS   # Empty by default
+else
+  OUR_JAVA_OPTS=$SPARK_JAVA_OPTS
 fi
 
 if [ "$SPARK_LAUNCH_WITH_SCALA" == "1" ]; then
@@ -64,7 +65,7 @@ fi
 export SPARK_MEM
 
 # Set JAVA_OPTS to be able to load native libraries and to set heap size
-JAVA_OPTS="$SPARK_JAVA_OPTS"
+JAVA_OPTS="$OUR_JAVA_OPTS"
 JAVA_OPTS+=" -Djava.library.path=$SPARK_LIBRARY_PATH"
 JAVA_OPTS+=" -Xms$SPARK_MEM -Xmx$SPARK_MEM"
 # Load extra JAVA_OPTS from conf/java-opts, if it exists

run2.cmd

@@ -22,9 +22,9 @@ if "%1"=="spark.deploy.master.Master" set RUNNING_DAEMON=1
 if "%1"=="spark.deploy.worker.Worker" set RUNNING_DAEMON=1
 if "x%SPARK_DAEMON_MEMORY%" == "x" set SPARK_DAEMON_MEMORY=512m
 if "%RUNNING_DAEMON%"=="1" set SPARK_MEM=%SPARK_DAEMON_MEMORY%
-rem Backup current SPARK_JAVA_OPTS for use in ExecutorRunner.scala
-if "%RUNNING_DAEMON%"=="1" set SPARK_NONDAEMON_JAVA_OPTS=%SPARK_JAVA_OPTS%
-if "%RUNNING_DAEMON%"=="1" set SPARK_JAVA_OPTS=%SPARK_DAEMON_JAVA_OPTS%
+rem Do not overwrite SPARK_JAVA_OPTS environment variable in this script
+if "%RUNNING_DAEMON%"=="0" set OUR_JAVA_OPTS=%SPARK_JAVA_OPTS%
+if "%RUNNING_DAEMON%"=="1" set OUR_JAVA_OPTS=%SPARK_DAEMON_JAVA_OPTS%
 
 rem Check that SCALA_HOME has been specified
 if not "x%SCALA_HOME%"=="x" goto scala_exists
@@ -41,7 +41,7 @@ rem variable so that our process sees it and can report it to Mesos
 if "x%SPARK_MEM%"=="x" set SPARK_MEM=512m
 
 rem Set JAVA_OPTS to be able to load native libraries and to set heap size
-set JAVA_OPTS=%SPARK_JAVA_OPTS% -Djava.library.path=%SPARK_LIBRARY_PATH% -Xms%SPARK_MEM% -Xmx%SPARK_MEM%
+set JAVA_OPTS=%OUR_JAVA_OPTS% -Djava.library.path=%SPARK_LIBRARY_PATH% -Xms%SPARK_MEM% -Xmx%SPARK_MEM%
 rem Load extra JAVA_OPTS from conf/java-opts, if it exists
 if exist "%FWDIR%conf\java-opts.cmd" call "%FWDIR%conf\java-opts.cmd"
 rem Attention: when changing the way the JAVA_OPTS are assembled, the change must be reflected in ExecutorRunner.scala!