HADOOP-15549. Upgrade to commons-configuration 2.1 regresses task CPU consumption

Change-Id: I03d1994adc9fc0a3ca38d886c3766948d2020c74

Author: toddlipcon

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/impl/MetricsConfig.java

@@ -37,10 +37,8 @@
 import org.apache.commons.configuration2.Configuration;
 import org.apache.commons.configuration2.PropertiesConfiguration;
 import org.apache.commons.configuration2.SubsetConfiguration;
-import org.apache.commons.configuration2.builder.fluent.Configurations;
-import org.apache.commons.configuration2.builder.fluent.Parameters;
-import org.apache.commons.configuration2.convert.DefaultListDelimiterHandler;
 import org.apache.commons.configuration2.ex.ConfigurationException;
+import org.apache.commons.configuration2.io.FileHandler;
 import org.apache.hadoop.metrics2.MetricsFilter;
 import org.apache.hadoop.metrics2.MetricsPlugin;
 import org.apache.hadoop.metrics2.filter.GlobFilter;
@@ -112,14 +110,15 @@ static MetricsConfig create(String prefix, String... fileNames) {
   static MetricsConfig loadFirst(String prefix, String... fileNames) {
     for (String fname : fileNames) {
       try {
-        Configuration cf = new Configurations().propertiesBuilder(fname)
-            .configure(new Parameters().properties()
-                .setFileName(fname)
-                .setListDelimiterHandler(new DefaultListDelimiterHandler(',')))
-              .getConfiguration()
-              .interpolatedConfiguration();
-        LOG.info("loaded properties from "+ fname);
-        LOG.debug(toString(cf));
+        PropertiesConfiguration pcf = new PropertiesConfiguration();
+        FileHandler fh = new FileHandler(pcf);
+        fh.setFileName(fname);
+        fh.load();
+        Configuration cf = pcf.interpolatedConfiguration();
+        LOG.info("Loaded properties from {}", fname);
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Properties: {}", toString(cf));
+        }
         MetricsConfig mc = new MetricsConfig(cf, prefix);
         LOG.debug(mc.toString());
         return mc;