HDFS-12502. nntop should support a category based on FilesInGetListingOps.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -3673,6 +3673,11 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
       readUnlock(operationName);
     }
     logAuditEvent(true, operationName, src);
+    if (topConf.isEnabled && isAuditEnabled() && isExternalInvocation()
+        && dl != null && Server.getRemoteUser() != null) {
+      topMetrics.reportFilesInGetListing(Server.getRemoteUser().toString(),
+          dl.getPartialListing().length);
+    }
     return dl;
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/top/metrics/TopMetrics.java

@@ -70,6 +70,14 @@ public class TopMetrics implements MetricsSource {
   public static final Logger LOG = LoggerFactory.getLogger(TopMetrics.class);
   public static final String TOPMETRICS_METRICS_SOURCE_NAME =
       "NNTopUserOpCounts";
+  /**
+   * In addition to counts of different RPC calls, NNTop also reports top
+   * users listing large directories (measured by the number of files involved
+   * in listing operations from the user). This is important because the CPU
+   * and GC overhead of a listing operation grows linearly with the number of
+   * files involved. This category in NNTop is {@link #FILES_IN_GETLISTING}.
+   */
+  public static final String FILES_IN_GETLISTING = "filesInGetListing";
   private final boolean isMetricsSourceEnabled;
 
   private static void logConf(Configuration conf) {
@@ -123,22 +131,30 @@ public class TopMetrics implements MetricsSource {
   public void report(boolean succeeded, String userName, InetAddress addr,
       String cmd, String src, String dst, FileStatus status) {
     // currently nntop only makes use of the username and the command
-    report(userName, cmd);
+    report(userName, cmd, 1);
   }
 
-  public void report(String userName, String cmd) {
+  public void reportFilesInGetListing(String userName, int numFiles) {
+    report(userName, FILES_IN_GETLISTING, numFiles);
+  }
+
+  public void report(String userName, String cmd, int delta) {
     long currTime = Time.monotonicNow();
-    report(currTime, userName, cmd);
+    report(currTime, userName, cmd, delta);
   }
 
-  public void report(long currTime, String userName, String cmd) {
+  public void report(long currTime, String userName, String cmd, int delta) {
     LOG.debug("a metric is reported: cmd: {} user: {}", cmd, userName);
     userName = UserGroupInformation.trimLoginMethod(userName);
     for (RollingWindowManager rollingWindowManager : rollingWindowManagers
         .values()) {
-      rollingWindowManager.recordMetric(currTime, cmd, userName, 1);
+      rollingWindowManager.recordMetric(currTime, cmd, userName, delta);
-      rollingWindowManager.recordMetric(currTime,
+      // Increase the number of all RPC calls by the user, unless the report
-          TopConf.ALL_CMDS, userName, 1);
+      // is for the number of files in a listing operation.
+      if (!cmd.equals(FILES_IN_GETLISTING)) {
+        rollingWindowManager.recordMetric(currTime,
+            TopConf.ALL_CMDS, userName, delta);
+      }
     }
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestTopMetrics.java

@@ -26,6 +26,7 @@ import org.apache.hadoop.metrics2.lib.Interns;
 import org.junit.Test;
 
 import static org.apache.hadoop.hdfs.server.namenode.top.metrics.TopMetrics.TOPMETRICS_METRICS_SOURCE_NAME;
+import static org.apache.hadoop.hdfs.server.namenode.top.metrics.TopMetrics.FILES_IN_GETLISTING;
 import static org.apache.hadoop.test.MetricsAsserts.getMetrics;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -41,9 +42,10 @@ public class TestTopMetrics {
     TopMetrics topMetrics = new TopMetrics(conf,
         topConf.nntopReportingPeriodsMs);
     // Dummy command
-    topMetrics.report("test", "listStatus");
+    topMetrics.report("test", "listStatus", 1);
-    topMetrics.report("test", "listStatus");
+    topMetrics.report("test", "listStatus", 1);
-    topMetrics.report("test", "listStatus");
+    topMetrics.report("test", "listStatus", 1);
+    topMetrics.report("test", FILES_IN_GETLISTING, 1000);
 
     MetricsRecordBuilder rb = getMetrics(topMetrics);
     MetricsCollector mc = rb.parent();
@@ -59,5 +61,8 @@ public class TestTopMetrics {
 
     verify(rb, times(3)).addCounter(Interns.info("op=listStatus." +
         "user=test.count", "Total operations performed by user"), 3L);
+
+    verify(rb, times(3)).addCounter(Interns.info("op=" + FILES_IN_GETLISTING +
+        ".user=test.count", "Total operations performed by user"), 1000L);
   }
 }