SPARK-5425: Modified Utils.getSystemProperties to return a map of all…

… system properties - explicit + defaults

core/src/main/scala/org/apache/spark/SparkConf.scala

@@ -17,9 +17,10 @@
 
 package org.apache.spark
 
-import scala.collection.JavaConverters._
 import scala.collection.mutable.HashMap
 
+import org.apache.spark.util.Utils
+
 /**
  * Configuration for a Spark application. Used to set various Spark parameters as key-value pairs.
  *
@@ -49,9 +50,8 @@ class SparkConf(loadDefaults: Boolean) extends Cloneable with Logging {
 
   if (loadDefaults) {
     // Load any spark.* system properties
-    val propNames = System.getProperties.stringPropertyNames().asScala
-    for (k <- propNames if k.startsWith("spark.")) {
-      settings(k) = System.getProperty(k)
+    for ((key, value) <- Utils.getSystemProperties if key.startsWith("spark.")) {
+      settings(key) = value
     }
   }
 

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -1227,9 +1227,14 @@ private[spark] object Utils extends Logging {
     hashAbs
   }
 
-  /** Returns a copy of the system properties that is thread-safe to iterator over. */
-  def getSystemProperties(): Map[String, String] = {
-    System.getProperties.clone().asInstanceOf[java.util.Properties].toMap[String, String]
+  /** Returns the system properties map that is thread-safe to iterator over. It gets the
+    * properties which have been set explicitly, as well as those for which only a default value
+    * has been defined. */
+  def getSystemProperties: Map[String, String] = {
+    val sysProps = for (key <- System.getProperties.stringPropertyNames()) yield
+      (key, System.getProperty(key))
+
+    sysProps.toMap
   }
 
   /**

examples/src/main/scala/org/apache/spark/examples/DriverSubmissionTest.scala

@@ -19,6 +19,8 @@ package org.apache.spark.examples
 
 import scala.collection.JavaConversions._
 
+import org.apache.spark.util.Utils
+
 /** Prints out environmental information, sleeps, and then exits. Made to
   * test driver submission in the standalone scheduler. */
 object DriverSubmissionTest {
@@ -30,7 +32,7 @@ object DriverSubmissionTest {
     val numSecondsToSleep = args(0).toInt
 
     val env = System.getenv()
-    val properties = System.getProperties()
+    val properties = Utils.getSystemProperties
 
     println("Environment variables containing SPARK_TEST:")
     env.filter{case (k, v) => k.contains("SPARK_TEST")}.foreach(println)