HDFS-16074. Remove an expensive debug string concatenation (#3107)

Reviewed-by: Ayush Saxena <ayushsaxena@apache.org>
Reviewed-by: Akira Ajisaka <aajisaka@apache.org>
Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Reviewed-by: Hui Fei <ferhui@apache.org>
Reviewed-by: Viraj Jasani <vjasani@apache.org>
Reviewed-by: litao <tomleescut@gmail.com>
(cherry picked from commit 1ad674e)

Author: jojochuang

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java

@@ -480,9 +480,10 @@ private synchronized void writeChunkPrepare(int buflen,
       currentPacket = createPacket(packetSize, chunksPerPacket, getStreamer()
           .getBytesCurBlock(), getStreamer().getAndIncCurrentSeqno(), false);
       DFSClient.LOG.debug("WriteChunk allocating new packet seqno={},"
-              + " src={}, packetSize={}, chunksPerPacket={}, bytesCurBlock={}",
+              + " src={}, packetSize={}, chunksPerPacket={}, bytesCurBlock={},"
+              + " output stream={}",
           currentPacket.getSeqno(), src, packetSize, chunksPerPacket,
-          getStreamer().getBytesCurBlock() + ", " + this);
+          getStreamer().getBytesCurBlock(), this);
     }
   }