Always store blank clientVersion in 2.x pulsar broker

[geniusjoe]

Expected behavior

Broker will return producer/consumer status with client version when call stats command, same as in 3.x version broker:

/data/service/pulsar/apache-pulsar-3.0.4 # curl http://localhost:8080/admin/v2/persistent/public/default/test1/stats             

{
  "msgRateIn": 1.0002999738406537,
  "msgThroughputIn": 57.01709850891726,
  "msgRateOut": 0,
  "msgThroughputOut": 0,
  "bytesInCounter": 7374,
  "msgInCounter": 129,
  "bytesOutCounter": 0,
  "msgOutCounter": 0,
  "averageMsgSize": 56.99999999999999,
  "msgChunkPublished": false,
  "storageSize": 7374,
  "backlogSize": 0,
  "publishRateLimitedTimes": 0,
  "earliestMsgPublishTimeInBacklogs": 0,
  "offloadedStorageSize": 0,
  "lastOffloadLedgerId": 0,
  "lastOffloadSuccessTimeStamp": 0,
  "lastOffloadFailureTimeStamp": 0,
  "ongoingTxnCount": 0,
  "abortedTxnCount": 0,
  "committedTxnCount": 0,
  "publishers": [
    {
      "accessMode": "Shared",
      "msgRateIn": 1.0002999738406537,
      "msgThroughputIn": 57.01709850891726,
      "averageMsgSize": 57,
      "chunkedMessageRate": 0,
      "producerId": 1,
      "supportsPartialProducer": false,
      "metadata": {},
      "address": "/9.x.x.x:58644",
      "producerName": "standalone-946-0",
      "connectedSince": "2025-06-05T16:02:33.768362397+08:00",
      "clientVersion": "Pulsar Go v0.15.1"               # <-------  print client version
    }
  ],
  "waitingPublishers": 0,
  "subscriptions": {},
  "replication": {},
  "deduplicationStatus": "Disabled",
  "nonContiguousDeletedMessagesRanges": 0,
  "nonContiguousDeletedMessagesRangesSerializedSize": 0,
  "delayedMessageIndexSizeInBytes": 0,
  "compaction": {
    "lastCompactionRemovedEventCount": 0,
    "lastCompactionSucceedTimestamp": 0,
    "lastCompactionFailedTimestamp": 0,
    "lastCompactionDurationTimeInMills": 0
  },
  "ownerBroker": "9.x.x.x:8080"
}

Actual behavior

Broker will return a blank clientVersion:
"clientVersion":""

Steps to reproduce

1. Deploy a apache-pulsar-2.11.4 pulsar cluster in standalone mode ./bin/pulsar standalone --config ./conf/standalone.conf -nss -nfw with default configuration
2. Create a pulsar producer with 0.15.1 version, code below:

func main() {
	client, err := pulsar.NewClient(pulsar.ClientOptions{
		URL: "http://localhost:8080",
	})
	if err != nil {
		log.Fatal(err)
	}
	defer client.Close()

	producer, err := client.CreateProducer(pulsar.ProducerOptions{
		Topic: "public/default/test1",
	})
	if err != nil {
		log.Fatal(err)
	}
	defer producer.Close()

	ctx := context.Background()
	for i := 0; i < 10000; i++ {
		if msgId, err := producer.Send(ctx, &pulsar.ProducerMessage{
			Payload: []byte(fmt.Sprintf("hello-%d", i)),
		}); err != nil {
			log.Fatal(err)
		} else {
			log.Println("Published message: ", msgId)
		}
		time.Sleep(1000*time.Millisecond)
	}
}

3. When producer running, execute command curl http://localhost:8080/admin/v2/persistent/public/default/test1/stats

Additinal info

Go sdk create clientVersion in the format of Pulsar Go <version> #856. But Pulsar broker 2.x does not allow clientVersions with spaces, which has been fixed since pulsar 3.x apache/pulsar#19616.
To make consistent with 2.x pulsar broker, maybe we need to change Go clientVersion format to Pulsar-Go-<version> like Java and C++ sdk. However, this could be a little break change but I think it's just fine.

pulsar-client-go/pulsar/internal/version.go

Line 43 in f673e4d

ClientVersionString = "Pulsar Go " + Version

	if buildInfo, ok := debug.ReadBuildInfo(); ok {
		for _, dep := range buildInfo.Deps {
			if dep.Path == pulsarClientGoModulePath {
				Version = semver.Canonical(dep.Version)
				ClientVersionString = "Pulsar Go " + Version  # <----- change to "Pulsar-Go-"
				return
			}
		}
	}

[RobertIndie]

Thanks for reporting this issue.

To make consistent with 2.x pulsar broker, maybe we need to change Go clientVersion format to Pulsar-Go- like Java and C++ sdk. However, this could be a little break change but I think it's just fine.

I'm +1 for this. We didn't document the exact format for the client version, and since it's mainly used for debugging, I don't think it should be considered a breaking change.