HDFS-8410. Add computation time metrics to datanode for ECWorker. Contributed by SammiChen.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockReconstructor.java

@@ -103,7 +103,10 @@ class StripedBlockReconstructor extends StripedReconstructor
     int[] erasedIndices = stripedWriter.getRealTargetIndices();
     ByteBuffer[] outputs = stripedWriter.getRealTargetBuffers(toReconstructLen);
 
+    long start = System.nanoTime();
     getDecoder().decode(inputs, erasedIndices, outputs);
+    long end = System.nanoTime();
+    this.getDatanode().getMetrics().incrECDecodingTime(end - start);
 
     stripedWriter.updateRealTargetBuffers(toReconstructLen);
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/metrics/DataNodeMetrics.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.hdfs.server.datanode.metrics;
 
 import static org.apache.hadoop.metrics2.impl.MsInfo.SessionId;
+import static org.apache.hadoop.metrics2.lib.Interns.info;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -134,6 +135,8 @@ public class DataNodeMetrics {
   MutableCounterLong ecReconstructionTasks;
   @Metric("Count of erasure coding failed reconstruction tasks")
   MutableCounterLong ecFailedReconstructionTasks;
+  // Nanoseconds spent by decoding tasks.
+  MutableCounterLong ecDecodingTimeNanos;
 
   final MetricsRegistry registry = new MetricsRegistry("datanode");
   final String name;
@@ -153,6 +156,9 @@ public class DataNodeMetrics {
     sendDataPacketTransferNanosQuantiles = new MutableQuantiles[len];
     ramDiskBlocksEvictionWindowMsQuantiles = new MutableQuantiles[len];
     ramDiskBlocksLazyPersistWindowMsQuantiles = new MutableQuantiles[len];
+    ecDecodingTimeNanos = registry.newCounter(
+        info("ecDecodingTimeNanos", "Nanoseconds spent by decoding tasks"),
+        (long) 0);
 
     for (int i = 0; i < len; i++) {
       int interval = intervals[i];
@@ -442,7 +448,10 @@ public class DataNodeMetrics {
   }
 
   public void setDataNodeActiveXceiversCount(int value) {
-    this.dataNodeActiveXceiversCount.set(value);
+    dataNodeActiveXceiversCount.set(value);
   }
 
+  public void incrECDecodingTime(long decodingTimeNanos) {
+    ecDecodingTimeNanos.incr(decodingTimeNanos);
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeErasureCodingMetrics.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hdfs.server.datanode;
 
+import com.google.common.base.Supplier;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -42,14 +43,15 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 
+import org.apache.hadoop.test.GenericTestUtils;
 import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.io.IOException;
 import java.util.Arrays;
 
-
 /**
  * This file tests the erasure coding metrics in DataNode.
  */
@@ -94,24 +96,37 @@ public class TestDataNodeErasureCodingMetrics {
     DataNode workerDn = doTest("/testEcTasks");
     MetricsRecordBuilder rb = getMetrics(workerDn.getMetrics().name());
 
-    // EcReconstructionTasks metric value will be updated in the finally block
-    // of striped reconstruction thread. Here, giving a grace period to finish
-    // EC reconstruction metric updates in DN.
-    LOG.info("Waiting to finish EC reconstruction metric updates in DN");
-    int retries = 0;
-    while (retries < 20) {
+    // Ensure that reconstruction task is finished
+    GenericTestUtils.waitFor(new Supplier<Boolean>() {
+      @Override
+      public Boolean get() {
         long taskMetricValue = getLongCounter("EcReconstructionTasks", rb);
-      if (taskMetricValue > 0) {
-        break;
-      }
-      Thread.sleep(500);
-      retries++;
-      rb = getMetrics(workerDn.getMetrics().name());
+        return (taskMetricValue > 0);
       }
+    }, 500, 10000);
+
     assertCounter("EcReconstructionTasks", (long) 1, rb);
     assertCounter("EcFailedReconstructionTasks", (long) 0, rb);
   }
 
+  @Test(timeout = 120000)
+  public void testEcCodingTime() throws Exception {
+    DataNode workerDn = doTest("/testEcCodingTime");
+    MetricsRecordBuilder rb = getMetrics(workerDn.getMetrics().name());
+
+    // Ensure that reconstruction task is finished
+    GenericTestUtils.waitFor(new Supplier<Boolean>() {
+      @Override
+      public Boolean get() {
+        long taskMetricValue = getLongCounter("EcReconstructionTasks", rb);
+        return (taskMetricValue > 0);
+      }
+    }, 500, 10000);
+
+    long decodeTime = getLongCounter("ecDecodingTimeNanos", rb);
+    Assert.assertTrue(decodeTime > 0);
+  }
+
   private DataNode doTest(String fileName) throws Exception {
 
     Path file = new Path(fileName);