[HDFS-16074] Remove an expensive debug string concatenation

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha1
• Fix Version/s: 3.4.0, 3.2.3, 3.3.2
• Component/s: hdfs-client
• Labels: pull-request-available
• Target Version/s: 3.4.0, 3.2.3, 3.3.2
• Hadoop Flags: Reviewed
• Assignee: Wei-Chiu Chuang
• Reporter: Wei-Chiu Chuang
• Created: 16/Jun/21 06:32
• Updated: 11/Feb/24 09:04
• Resolved: 17/Jun/21 03:40

Description

Running a YCSB load query, found that we do an expensive string concatenation on the write path in DFSOutputStream.writeChunkPrepare().

Nearly 25% of HDFS client write CPU time is spent here. It is not necessary because it's supposed to be a debug message. So let's remove it.

 if (currentPacket == null) {
      currentPacket = createPacket(packetSize, chunksPerPacket, getStreamer()
          .getBytesCurBlock(), getStreamer().getAndIncCurrentSeqno(), false);
      DFSClient.LOG.debug("WriteChunk allocating new packet seqno={},"
              + " src={}, packetSize={}, chunksPerPacket={}, bytesCurBlock={}",
          currentPacket.getSeqno(), src, packetSize, chunksPerPacket,
          getStreamer().getBytesCurBlock() + ", " + this); <---- here
    }

Issue Links

• links to: GitHub Pull Request #3107