卡夫卡消费者-JMX属性

Question

I enabled JMX on the kafka brokers on port 8081. When I view the MBean properties in jConsole, I only see the following for kafka.consumer -

kafka.consumer:type=FetchRequestAndResponseMetrics,name=FetchRequestRateAndTimeMs,clientId=ReplicaFetcherThread-2-413

kafka.consumer:type=FetchRequestAndResponseMetrics,name=FetchResponseSize,clientId=ReplicaFetcherThread-0-413

But none of the other ones that are identified in here under Kafka Consumer Metrics are emitted by JMX.

Kafka Version # 0.8.2.1

I am specifically interested in - kafka.consumer:type=ConsumerFetcherManager,name=MaxLag,clientId=([-.\\w]+)

Any thoughts?

Answer 1

The JMX PORT you are listening is the broker port. But the Mbean of kafka.consumer: is the consumer jvm metrics. So if you have another JVM that is consume a topic, you can see kafka.consumer Mbeans.

Answer 2

ConsumerLag is an overloaded term in Kafka , it can stand for:

1. Consumer's metric : Calculated difference between a consumer's current log offset and a producer's current log offset. You can find it under JMX bean, if you're using Java/Scala based consumer (eg pykafka consumer doesn't export metrics ):

   • kafka v0.8.2.x :

      kafka.consumer:type= ConsumerFetcherManager, name=MaxLag, clientId=([-.\\w]+) 

   • kafka v0.9+ :

      kafka.consumer:type=consumer-fetch-manager-metrics,client-id=([-.w]+) 

   Consumer lag used to be stored in ZooKeeper (Kafka <= v0.8 ), newer versions of Kafka have special topic __consumer_offsets that stores each consumer's lag. There are tools (eg kafka-manager ) that can compute lag by consuming messages from this topic and calculating lag. In kafka-manager you have to enable this feature for each cluster:

   [ ] Poll consumer information (Not recommended for large # of consumers)

2. Broker's metric : Represent the offset differences between partition leaders and their followers. You can find this metric under JMX bean:

    kafka.server:type=FetcherLagMetrics,name=ConsumerLag,clientId=([-.\\w]+),topic=([-.\\w]+),partition=([0-9]+) 

Answer 3

This may help to find it for 0.8, but I am currently running a Kafka 0.10 broker and consumer. When using a console consumer, I pointed jconsole to this consumer and found on the MBeans TAB: kafka.consumer -> consumer-fetcher-manager-metric -> consumer-1 -> Attributes -> records-max-lag .