HDFS-7675. Remove unused member DFSClient.spanReceiverHost (cmccabe)

(cherry picked from commit d12dd47f4516fe125221ae073f1bc88b702b122f)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -271,6 +271,8 @@ Release 2.7.0 - UNRELEASED
     HDFS-7683. Combine usages and percent stats in NameNode UI.
     (Vinayakumar B via wheat9)
 
+    HDFS-7675. Remove unused member DFSClient#spanReceiverHost (cmccabe)
+
   OPTIMIZATIONS
 
     HDFS-7454. Reduce memory footprint for AclEntries in NameNode.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java

@@ -282,7 +282,6 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   private static ThreadPoolExecutor HEDGED_READ_THREAD_POOL;
   @VisibleForTesting
   KeyProvider provider;
-  private final SpanReceiverHost spanReceiverHost;
   private final Sampler<?> traceSampler;
 
   /**
@@ -627,7 +626,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DFSClient(URI nameNodeUri, ClientProtocol rpcNamenode,
       Configuration conf, FileSystem.Statistics stats)
     throws IOException {
-    spanReceiverHost = SpanReceiverHost.getInstance(conf);
+    SpanReceiverHost.getInstance(conf);
     traceSampler = TraceSamplerFactory.createSampler(conf);
     // Copy only the required DFSClient configuration
     this.dfsClientConf = new Conf(conf);