HDFS-10792. RedundantEditLogInputStream should log caught exceptions. Contributed by Wei-Chiu Chuang.

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

@@ -170,6 +170,7 @@ class RedundantEditLogInputStream extends EditLogInputStream {
       }
       return nextOp();
     } catch (IOException e) {
+      LOG.warn("encountered an exception", e);
       return null;
     }
   }
@@ -228,7 +229,8 @@ class RedundantEditLogInputStream extends EditLogInputStream {
               "streams are shorter than the current one!  The best " +
               "remaining edit log ends at transaction " +
               newLast + ", but we thought we could read up to transaction " +
-              oldLast + ".  If you continue, metadata will be lost forever!");
+              oldLast + ".  If you continue, metadata will be lost forever!",
+              prevException);
         }
         LOG.error("Got error reading edit log input stream " +
           streams[curIdx].getName() + "; failing over to edit log " +