HDFS-16526. Add metrics for slow DataNode (#4162)

hadoop-common-project/hadoop-common/src/site/markdown/Metrics.md

@@ -481,7 +481,8 @@ Each metrics record contains tags such as SessionId and Hostname as additional i
 | `PacketsSlowWriteToMirror` | Total number of packets whose write to other Datanodes in the pipeline takes more than a certain time (300ms by default) |
 | `PacketsSlowWriteToDisk` | Total number of packets whose write to disk takes more than a certain time (300ms by default) |
 | `PacketsSlowWriteToOsCache` | Total number of packets whose write to os cache takes more than a certain time (300ms by default) |
-
+| `slowFlushOrSyncCount` | Total number of packets whose sync/flush takes more than a certain time (300ms by default) |
+| `slowAckToUpstreamCount` | Total number of packets whose upstream ack takes more than a certain time (300ms by default) |
 FsVolume
 --------
 

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

@@ -412,6 +412,7 @@ boolean packetSentInTime() {
   void flushOrSync(boolean isSync, long seqno) throws IOException {
     long flushTotalNanos = 0;
     long begin = Time.monotonicNow();
+    DataNodeFaultInjector.get().delay();
     if (checksumOut != null) {
       long flushStartNanos = System.nanoTime();
       checksumOut.flush();
@@ -445,6 +446,7 @@ void flushOrSync(boolean isSync, long seqno) throws IOException {
     }
     long duration = Time.monotonicNow() - begin;
     if (duration > datanodeSlowLogThresholdMs && LOG.isWarnEnabled()) {
+      datanode.metrics.incrSlowFlushOrSyncCount();
       LOG.warn("Slow flushOrSync took " + duration + "ms (threshold="
           + datanodeSlowLogThresholdMs + "ms), isSync:" + isSync + ", flushTotalNanos="
           + flushTotalNanos + "ns, volume=" + getVolumeBaseUri()
@@ -1656,6 +1658,7 @@ private void sendAckUpstreamUnprotected(PipelineAck ack, long seqno,
       }
       // send my ack back to upstream datanode
       long begin = Time.monotonicNow();
+      DataNodeFaultInjector.get().delay();
       /* for test only, no-op in production system */
       DataNodeFaultInjector.get().delaySendingAckToUpstream(inAddr);
       replyAck.write(upstreamOut);
@@ -1665,6 +1668,7 @@ private void sendAckUpstreamUnprotected(PipelineAck ack, long seqno,
           inAddr,
           duration);
       if (duration > datanodeSlowLogThresholdMs) {
+        datanode.metrics.incrSlowAckToUpstreamCount();
         LOG.warn("Slow PacketResponder send ack to upstream took " + duration
             + "ms (threshold=" + datanodeSlowLogThresholdMs + "ms), " + myString
             + ", replyAck=" + replyAck

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

@@ -191,6 +191,8 @@ public class DataNodeMetrics {
   @Metric MutableCounterLong packetsSlowWriteToMirror;
   @Metric MutableCounterLong packetsSlowWriteToDisk;
   @Metric MutableCounterLong packetsSlowWriteToOsCache;
+  @Metric private MutableCounterLong slowFlushOrSyncCount;
+  @Metric private MutableCounterLong slowAckToUpstreamCount;
 
   @Metric("Number of replaceBlock ops between" +
       " storage types on same host with local copy")
@@ -440,6 +442,14 @@ public void incrVolumeFailures(int size) {
     volumeFailures.incr(size);
   }
 
+  public void incrSlowFlushOrSyncCount() {
+    slowFlushOrSyncCount.incr();
+  }
+
+  public void incrSlowAckToUpstreamCount() {
+    slowAckToUpstreamCount.incr();
+  }
+
   public void incrDatanodeNetworkErrors() {
     datanodeNetworkErrors.incr();
   }

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

@@ -603,6 +603,60 @@ public void testNNRpcMetricsWithNonHA() throws IOException {
     MetricsRecordBuilder rb = getMetrics(dn.getMetrics().name());
     assertCounter("HeartbeatsNumOps", 1L, rb);
   }
+  @Test(timeout = 60000)
+  public void testSlowMetrics() throws Exception {
+    DataNodeFaultInjector dnFaultInjector = new DataNodeFaultInjector() {
+      @Override public void delay() {
+        try {
+          Thread.sleep(310);
+        } catch (InterruptedException e) {
+        }
+      }
+    };
+    DataNodeFaultInjector oldDnInjector = DataNodeFaultInjector.get();
+    DataNodeFaultInjector.set(dnFaultInjector);
+
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = null;
+    try {
+      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(3).build();
+      final FileSystem fs = cluster.getFileSystem();
+      List<DataNode> datanodes = cluster.getDataNodes();
+      assertEquals(datanodes.size(), 3);
+      final DataNode datanode = datanodes.get(0);
+      MetricsRecordBuilder rb = getMetrics(datanode.getMetrics().name());
+      final long longFileLen = 10;
+      final long startFlushOrSyncValue =
+          getLongCounter("SlowFlushOrSyncCount", rb);
+      final long startAckToUpstreamValue =
+          getLongCounter("SlowAckToUpstreamCount", rb);
+      final AtomicInteger x = new AtomicInteger(0);
+
+      GenericTestUtils.waitFor(new Supplier<Boolean>() {
+        @Override public Boolean get() {
+          x.getAndIncrement();
+          try {
+            DFSTestUtil
+                .createFile(fs, new Path("/time.txt." + x.get()), longFileLen,
+                    (short) 3, Time.monotonicNow());
+          } catch (IOException ioe) {
+            LOG.error("Caught IOException while ingesting DN metrics", ioe);
+            return false;
+          }
+          MetricsRecordBuilder rbNew = getMetrics(datanode.getMetrics().name());
+          final long endFlushOrSyncValue = getLongCounter("SlowFlushOrSyncCount", rbNew);
+          final long endAckToUpstreamValue = getLongCounter("SlowAckToUpstreamCount", rbNew);
+          return endFlushOrSyncValue > startFlushOrSyncValue
+              && endAckToUpstreamValue > startAckToUpstreamValue;
+        }
+      }, 30, 30000);
+    } finally {
+      DataNodeFaultInjector.set(oldDnInjector);
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
 
   @Test
   public void testNNRpcMetricsWithHA() throws IOException {