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Monitoring Kafka

Apache Kafka® brokers and clients report many internal metrics. JMX is the default reporter, though you can add any pluggable reporter.

You can deploy Confluent Control Center for out-of-the-box Kafka cluster monitoring so you don’t have to build your own monitoring system. Control Center makes it easy to manage the entire Confluent Platform. Control Center is a web-based application that allows you to manage your cluster, to monitor Kafka system health in predefined dashboards and to alert on triggers. Additionally, Control Center reports end-to-end stream monitoring to assure that every message is delivered from producer to consumer, measures how long messages take to be delivered, and determines the source of any issues in your cluster.

Refer to Optimizing Your Apache Kafka Deployment whitepaper for a practical guide to optimizing your Kafka deployment for various services goals including throughput, latency, durability and availability, and useful metrics to monitor for performance and cluster health.

Server Metrics

Broker Metrics

Confluent Control Center monitors the following important operational broker metrics aggregated across the cluster, and per broker or per topic where applicable. Control Center provides built-in dashboards for viewing these metrics, and we recommend that you set alerts at least on the first three.

kafka.server:type=ReplicaManager,name=UnderReplicatedPartitions

Number of under-replicated partitions (| ISR | < | all replicas |). Alert if value is greater than 0.

kafka.controller:type=KafkaController,name=OfflinePartitionsCount

Number of partitions that don’t have an active leader and are hence not writable or readable. Alert if value is greater than 0.

kafka.controller:type=KafkaController,name=ActiveControllerCount

Number of active controllers in the cluster. Alert if the aggregated sum across all brokers in the cluster is anything other than 1 because there should be exactly one controller per cluster.

kafka.server:type=BrokerTopicMetrics,name=BytesInPerSec

Aggregate incoming byte rate.

kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec

Aggregate outgoing byte rate.

kafka.network:type=RequestMetrics,name=RequestsPerSec,request={Produce|FetchConsumer|FetchFollower}

Request rate.

kafka.server:type=BrokerTopicMetrics,name=TotalProduceRequestsPerSec

Produce request rate.

kafka.server:type=BrokerTopicMetrics,name=TotalFetchRequestsPerSec

Fetch request rate.

kafka.server:type=BrokerTopicMetrics,name=FailedProduceRequestsPerSec

Produce request rate for requests that failed.

kafka.server:type=BrokerTopicMetrics,name=FailedFetchRequestsPerSec

Fetch request rate for requests that failed.

kafka.controller:type=ControllerStats,name=LeaderElectionRateAndTimeMs

Leader election rate and latency.

kafka.controller:type=ControllerStats,name=UncleanLeaderElectionsPerSec

Unclean leader election rate.

kafka.server:type=ReplicaManager,name=PartitionCount

Number of partitions on this broker. This should be mostly even across all brokers.

kafka.server:type=ReplicaManager,name=LeaderCount

Number of leaders on this broker. This should be mostly even across all brokers. If not, set auto.leader.rebalance.enable to true on all brokers in the cluster.

kafka.server:type=ReplicaFetcherManager,name=MaxLag,clientId=Replica

Maximum lag in messages between the follower and leader replicas. This is controlled by the replica.lag.max.messages config.

kafka.server:type=KafkaRequestHandlerPool,name=RequestHandlerAvgIdlePercent

Average fraction of time the request handler threads are idle. Values are between 0 (all resources are used) and 1 (all resources are available)

kafka.network:type=SocketServer,name=NetworkProcessorAvgIdlePercent

Average fraction of time the network processor threads are idle. Values are between 0 (all resources are used) and 1 (all resources are available)

kafka.network:type=RequestChannel,name=RequestQueueSize

Size of the request queue. A congested request queue will not be able to process incoming or outgoing requests

kafka.network:type=RequestMetrics,name=TotalTimeMs,request={Produce|FetchConsumer|FetchFollower}

Total time in ms to serve the specified request

kafka.network:type=RequestMetrics,name=RequestQueueTimeMs,request={Produce|FetchConsumer|FetchFollower}

Time the request waits in the request queue

kafka.network:type=RequestMetrics,name=LocalTimeMs,request={Produce|FetchConsumer|FetchFollower}

Time the request is processed at the leader

kafka.network:type=RequestMetrics,name=RemoteTimeMs,request={Produce|FetchConsumer|FetchFollower}

Time the request waits for the follower. This is non-zero for produce requests when acks=all

kafka.network:type=RequestMetrics,name=ResponseQueueTimeMs,request={Produce|FetchConsumer|FetchFollower}

Time the request waits in the response queue

kafka.network:type=RequestMetrics,name=ResponseSendTimeMs,request={Produce|FetchConsumer|FetchFollower}

Time to send the response

Here are other available metrics you may optionally observe on a Kafka broker.

kafka.server:type=BrokerTopicMetrics,name=MessagesInPerSec

Aggregate incoming message rate.

kafka.log:type=LogFlushStats,name=LogFlushRateAndTimeMs

Log flush rate and time.

kafka.server:type=ReplicaManager,name=IsrShrinksPerSec

If a broker goes down, ISR for some of the partitions will shrink. When that broker is up again, ISR will be expanded once the replicas are fully caught up. Other than that, the expected value for both ISR shrink rate and expansion rate is 0.

kafka.server:type=ReplicaManager,name=IsrExpandsPerSec

When a broker is brought up after a failure, it starts catching up by reading from the leader. Once it is caught up, it gets added back to the ISR.

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

Lag in number of messages per follower replica. This is useful to know if the replica is slow or has stopped replicating from the leader.

kafka.server:type=DelayedOperationPurgatory,delayedOperation=Produce,name=PurgatorySize

Number of requests waiting in the producer purgatory. This should be non-zero when acks=all is used on the producer.

kafka.server:type=DelayedOperationPurgatory,delayedOperation=Fetch,name=PurgatorySize

Number of requests waiting in the fetch purgatory. This is high if consumers use a large value for fetch.wait.max.ms .

ZooKeeper Metrics

Confluent Control Center monitors the following important operational broker metrics relating to ZooKeeper. We expose counts for ZooKeeper state transitions, which can help to spot problems, e.g., with broker sessions to ZooKeeper. The metrics currently show the rate of transitions per second for each one of the possible states. Here is the list of the counters we expose, one for each possible ZooKeeper client states.

kafka.server:type=SessionExpireListener,name=ZooKeeperDisconnectsPerSec

ZooKeeper client is currently disconnected from the ensemble. The client lost its previous connection to a server and it is currently trying to reconnect. The session is not necessarily expired.

kafka.server:type=SessionExpireListener,name=ZooKeeperExpiresPerSec

The ZooKeeper session has expired. When a session expires, we can have leader changes and even a new controller. It is important to keep an eye on the number of such events across a Kafka cluster and if the overall number is high, then we have a few recommendations:

1. Check the health of your network
2. Check for garbage collection issues and tune it accordingly
3. If necessary, increase the session time out by setting the value of zookeeper.session.timeout.ms.

Here are other available ZooKeeper metrics you may optionally observe on a Kafka broker.

kafka.server:type=SessionExpireListener,name=ZooKeeperSyncConnectsPerSec

ZooKeeper client is connected to the ensemble and ready to execute operations.

kafka.server:type=SessionExpireListener,name=ZooKeeperAuthFailuresPerSec

An attempt to connect to the ensemble failed because the client has not provided correct credentials.

kafka.server:type=SessionExpireListener,name=ZooKeeperReadOnlyConnectsPerSec

The server the client is connected to is currently LOOKING, which means that it is neither FOLLOWING nor LEADING. Consequently, the client can only read the ZooKeeper state, but not make any changes (create, delete, or set the data of znodes).

kafka.server:type=SessionExpireListener,name=ZooKeeperSaslAuthenticationsPerSec

Client has successfully authenticated.

Producer Metrics

Starting with 0.8.2, the new producer exposes the following metrics:

Global Request Metrics

MBean: kafka.producer:type=producer-metrics,client-id=([-.w]+)

request-latency-avg

The average request latency in ms.

request-latency-max

The maximum request latency in ms.

request-rate

The average number of requests sent per second.

response-rate

The average number of responses received per second.

incoming-byte-rate

The average number of incoming bytes received per second from all servers.

outgoing-byte-rate

The average number of outgoing bytes sent per second to all servers.

Global Connection Metrics

MBean: kafka.producer:type=producer-metrics,client-id=([-.w]+)

connection-count

The current number of active connections.

connection-creation-rate

New connections established per second in the window.

connection-close-rate

Connections closed per second in the window.

io-ratio

The fraction of time the I/O thread spent doing I/O.

io-time-ns-avg

The average length of time for I/O per select call in nanoseconds.

io-wait-ratio

The fraction of time the I/O thread spent waiting.

select-rate

Number of times the I/O layer checked for new I/O to perform per second.

io-wait-time-ns-avg

The average length of time the I/O thread spent waiting for a socket ready for reads or writes in nanoseconds.

Per-Broker Metrics

MBean: kafka.producer:type=producer-node-metrics,client-id=([-.w]+),node-id=([0-9]+)

Besides the Global Request Metrics, the following metrics are also available per broker:

request-size-max

The maximum size of any request sent in the window for a broker.

request-size-avg

The average size of all requests in the window for a broker.

request-rate

The average number of requests sent per second to the broker.

response-rate

The average number of responses received per second from the broker.

incoming-byte-rate

The average number of bytes received per second from the broker.

outgoing-byte-rate

The average number of bytes sent per second to the broker.

Per-Topic Metrics

MBean: kafka.producer:type=producer-topic-metrics,client-id=([-.w]+),topic=([-.w]+)

Besides the Global Request Metrics, the following metrics are also available per topic:

byte-rate

The average number of bytes sent per second for a topic.

record-send-rate

The average number of records sent per second for a topic.

compression-rate

The average compression rate of record batches for a topic.

record-retry-rate

The average per-second number of retried record sends for a topic.

record-error-rate

The average per-second number of record sends that resulted in errors for a topic.

New Consumer Metrics

Starting with Kafka 0.9.0.0, the new consumer exposes the following metrics:

Fetch Metrics

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

records-lag-max

The maximum lag in terms of number of records for any partition in this window. An increasing value over time is your best indication that the consumer group is not keeping up with the producers.

fetch-size-avg

The average number of bytes fetched per request.

fetch-size-max

The average number of bytes fetched per request.

bytes-consumed-rate

The average number of bytes consumed per second.

records-per-request-avg

The average number of records in each request.

records-consumed-rate

The average number of records consumed per second.

fetch-rate

The number of fetch requests per second.

fetch-latency-avg

The average time taken for a fetch request.

fetch-latency-max

The max time taken for a fetch request.

fetch-throttle-time-avg

The average throttle time in ms. When quotas are enabled, the broker may delay fetch requests in order to throttle a consumer which has exceeded its limit. This metric indicates how throttling time has been added to fetch requests on average.

fetch-throttle-time-max

The maximum throttle time in ms.

Topic-level Fetch Metrics

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

fetch-size-avg

The average number of bytes fetched per request for a specific topic.

fetch-size-max

The maximum number of bytes fetched per request for a specific topic.

bytes-consumed-rate

The average number of bytes consumed per second for a specific topic.

records-per-request-avg

The average number of records in each request for a specific topic.

records-consumed-rate

The average number of records consumed per second for a specific topic.

Consumer Group Metrics

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

assigned-partitions

The number of partitions currently assigned to this consumer.

commit-latency-avg

The average time taken for a commit request.

commit-latency-max

The max time taken for a commit request.

commit-rate

The number of commit calls per second.

join-rate

The number of group joins per second. Group joining is the first phase of the rebalance protocol. A large value indicates that the consumer group is unstable and will likely be coupled with increased lag.

join-time-avg

The average time taken for a group rejoin. This value can get as high as the configured session timeout for the consumer, but should usually be lower.

join-time-max

The max time taken for a group rejoin. This value should not get much higher than the configured session timeout for the consumer.

sync-rate

The number of group syncs per second. Group synchronization is the second and last phase of the rebalance protocol. Similar to join-rate, a large value indicates group instability.

sync-time-avg

The average time taken for a group sync.

sync-time-max

The max time taken for a group sync.

heartbeat-rate

The average number of heartbeats per second. After a rebalance, the consumer sends heartbeats to the coordinator to keep itself active in the group. You can control this using the heartbeat.interval.ms setting for the consumer. You may see a lower rate than configured if the processing loop is taking more time to handle message batches. Usually this is OK as long as you see no increase in the join rate.

heartbeat-response-time-max

The max time taken to receive a response to a heartbeat request.

last-heartbeat-seconds-ago

The number of seconds since the last controller heartbeat.

Global Request Metrics

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

request-latency-avg

The average request latency in ms.

request-latency-max

The maximum request latency in ms.

request-rate

The average number of requests sent per second.

response-rate

The average number of responses received per second.

incoming-byte-rate

The average number of incoming bytes received per second from all servers.

outgoing-byte-rate

The average number of outgoing bytes sent per second to all servers.

Global Connection Metrics

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

connection-count

The current number of active connections.

connection-creation-rate

New connections established per second in the window.

connection-close-rate

Connections closed per second in the window.

io-ratio

The fraction of time the I/O thread spent doing I/O.

io-time-ns-avg

The average length of time for I/O per select call in nanoseconds.

io-wait-ratio

The fraction of time the I/O thread spent waiting.

select-rate

Number of times the I/O layer checked for new I/O to perform per second.

io-wait-time-ns-avg

The average length of time the I/O thread spent waiting for a socket ready for reads or writes in nanoseconds.

Per-Broker Metrics

MBean: kafka.consumer:type=consumer-node-metrics,client-id=([-.w]+),node-id=([0-9]+)

Besides the Global Request Metrics, the following metrics are also available per broker:

request-size-max

The maximum size of any request sent in the window for a broker.

request-size-avg

The average size of all requests in the window for a broker.

request-rate

The average number of requests sent per second to the broker.

response-rate

The average number of responses received per second from the broker.

incoming-byte-rate

The average number of bytes received per second from the broker.

outgoing-byte-rate

The average number of bytes sent per second to the broker.

Old Consumer Metrics

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

Number of messages the consumer lags behind the producer by.

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

The minimum rate at which the consumer sends fetch requests to the broker. If a consumer is dead, this value drops to roughly 0.

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

The throughput in messages consumed per second.

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

The throughput in bytes consumed per second.

The following metrics are available only on the high-level consumer:

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

The rate at which this consumer commits offsets to Kafka. This is only relevant if offsets.storage=kafka.

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

The rate at which this consumer commits offsets to ZooKeeper. This is only relevant if offsets.storage=zookeeper. Monitor this value if your ZooKeeper cluster is under performing due to high write load.

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

The rate and latency of the rebalance operation on this consumer.

kafka.consumer:type=ZookeeperConsumerConnector,name=OwnedPartitionsCount,clientId=([-.\w]+),groupId=([-.\w]+)

The number of partitions owned by this consumer.