HDFS-9572. Prevent DataNode log spam if a client connects on the data transfer port but sends no data. Contributed by Chris Nauroth

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

@@ -2513,6 +2513,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9515. NPE when MiniDFSCluster#shutdown is invoked on uninitialized
     reference. (Wei-Chiu Chuang via Arpit Agarwal)
 
+    HDFS-9572. Prevent DataNode log spam if a client connects on the data
+    transfer port but sends no data. (cnauroth)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -233,18 +233,15 @@ class DataXceiver extends Receiver implements Runnable {
         } catch (InterruptedIOException ignored) {
           // Time out while we wait for client rpc
           break;
-        } catch (IOException err) {
-          // Since we optimistically expect the next op, it's quite normal to get EOF here.
-          if (opsProcessed > 0 &&
-              (err instanceof EOFException || err instanceof ClosedChannelException)) {
-            if (LOG.isDebugEnabled()) {
-              LOG.debug("Cached " + peer + " closing after " + opsProcessed + " ops");
-            }
-          } else {
-            incrDatanodeNetworkErrors();
-            throw err;
-          }
+        } catch (EOFException | ClosedChannelException e) {
+          // Since we optimistically expect the next op, it's quite normal to
+          // get EOF here.
+          LOG.debug("Cached {} closing after {} ops.  " +
+              "This message is usually benign.", peer, opsProcessed);
           break;
+        } catch (IOException err) {
+          incrDatanodeNetworkErrors();
+          throw err;
         }
 
         // restore normal timeout