[SYSTEMDS-3849] Perftest: Fix MVSM performance regression (spark ctx)

This patch fixes a perftest performance regression of
runMSVM_10k_1k_dense_k5 which ran in 36s instead of few seconds in
earlier releases. The reason was unnecessary spark context creation
during parfor optimization. We now handle theses cluster info requests
more carefully, which now avoids this unnecessary spark context creation
and reduced the total runtime back to 5.9s.

Author: mboehm7

src/main/java/org/apache/sysds/runtime/controlprogram/context/SparkExecutionContext.java

@@ -340,8 +340,11 @@ public static SparkConf createSystemDSSparkConf() {
 		return conf;
 	}
 
+	@SuppressWarnings("resource")
 	public static boolean isLocalMaster() {
-		return getSparkContextStatic().isLocal();
+		return isSparkContextCreated() ? 
+			getSparkContextStatic().isLocal() : 
+			DMLScript.USE_LOCAL_SPARK_CONFIG;
 	}
 
 	/**

src/main/java/org/apache/sysds/utils/stats/InfrastructureAnalyzer.java

@@ -183,10 +183,13 @@ public static int getCkMaxCP() {
 	 * @return maximum remote parallelism constraint
 	 */
 	public static int getCkMaxMR() {
+		//NOTE: we refresh only if there is already a spark context created
+		// in order to avoid unnecessary spark context creation in local ops
+		boolean refresh = SparkExecutionContext.isSparkContextCreated();
 		if( OptimizerUtils.isSparkExecutionMode() )
 			return SparkExecutionContext.isLocalMaster() ?
 				InfrastructureAnalyzer.getLocalParallelism() :
-				SparkExecutionContext.getDefaultParallelism(true);
+				SparkExecutionContext.getDefaultParallelism(refresh);
 		else
 			return getRemoteParallelMapTasks();
 	}
@@ -198,7 +201,6 @@ public static int getCkMaxMR() {
 	 */
 	public static long getCmMax() {
 		//default value (if not specified)
-		//TODO spark remote map task budget?
 		return getLocalMaxMemory();
 	}