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  5. 3.6 Kafka Streams Configs

3.6 Kafka Streams Configs

Below is the configuration of the Kafka Streams client library.

An identifier for the stream processing application. Must be unique within the Kafka cluster. It is used as 1) the default client-id prefix, 2) the group-id for membership management, 3) the changelog topic prefix.

Type:string
Default:
Valid Values:
Importance:high

A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The client will make use of all servers irrespective of which servers are specified here for bootstrapping—this list only impacts the initial hosts used to discover the full set of servers. This list should be in the form host1:port1,host2:port2,…. Since these servers are just used for the initial connection to discover the full cluster membership (which may change dynamically), this list need not contain the full set of servers (you may want more than one, though, in case a server is down).

Type:list
Default:
Valid Values:
Importance:high

The replication factor for change log topics and repartition topics created by the stream processing application.

Type:int
Default:1
Valid Values:
Importance:high

Directory location for state store. This path must be unique for each streams instance sharing the same underlying filesystem.

Type:string
Default:/tmp/kafka-streams
Valid Values:
Importance:high

The maximum acceptable lag (number of offsets to catch up) for a client to be considered caught-up for an active task.Should correspond to a recovery time of well under a minute for a given workload. Must be at least 0.

Type:long
Default:10000
Valid Values:[0,…]
Importance:medium

Maximum number of memory bytes to be used for buffering across all threads

Type:long
Default:10485760
Valid Values:[0,…]
Importance:medium

An ID prefix string used for the client IDs of internal consumer, producer and restore-consumer, with pattern ‘-StreamThread–‘.

Type:string
Default:“”
Valid Values:
Importance:medium

Exception handling class that implements the org.apache.kafka.streams.errors.DeserializationExceptionHandlerinterface.

Type:class
Default:org.apache.kafka.streams.errors.LogAndFailExceptionHandler
Valid Values:
Importance:medium

Default serializer / deserializer class for key that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via ‘default.windowed.key.serde.inner’ or ‘default.windowed.value.serde.inner’ as well

Type:class
Default:org.apache.kafka.common.serialization.Serdes$ByteArraySerde
Valid Values:
Importance:medium

Exception handling class that implements the org.apache.kafka.streams.errors.ProductionExceptionHandler interface.

Type:class
Default:org.apache.kafka.streams.errors.DefaultProductionExceptionHandler
Valid Values:
Importance:medium

Default timestamp extractor class that implements the org.apache.kafka.streams.processor.TimestampExtractor interface.

Type:class
Default:org.apache.kafka.streams.processor.FailOnInvalidTimestamp
Valid Values:
Importance:medium

Default serializer / deserializer class for value that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via ‘default.windowed.key.serde.inner’ or ‘default.windowed.value.serde.inner’ as well

Type:class
Default:org.apache.kafka.common.serialization.Serdes$ByteArraySerde
Valid Values:
Importance:medium

Maximum amount of time a stream task will stay idle when not all of its partition buffers contain records, to avoid potential out-of-order record processing across multiple input streams.

Type:long
Default:0
Valid Values:
Importance:medium

The maximum number of warmup replicas (extra standbys beyond the configured num.standbys) that can be assigned at once for the purpose of keeping the task available on one instance while it is warming up on another instance it has been reassigned to. Used to throttle how much extra broker traffic and cluster state can be used for high availability. Must be at least 1.

Type:int
Default:2
Valid Values:[1,…]
Importance:medium

The number of standby replicas for each task.

Type:int
Default:0
Valid Values:
Importance:medium

The number of threads to execute stream processing.

Type:int
Default:1
Valid Values:
Importance:medium

The processing guarantee that should be used. Possible values are at_least_once(default), exactly_once (requires brokers version 0.11.0 or higher), and exactly_once_beta (requires brokers version 2.5 or higher). Note that exactly-once processing requires a cluster of at least three brokers by default what is the recommended setting for production; for development you can change this, by adjusting broker setting transaction.state.log.replication.factor and transaction.state.log.min.isr.

Type:string
Default:at_least_once
Valid Values:[at_least_once, exactly_once, exactly_once_beta]
Importance:medium

Protocol used to communicate with brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL.

Type:string
Default:PLAINTEXT
Valid Values:
Importance:medium

A configuration telling Kafka Streams if it should optimize the topology, disabled by default

Type:string
Default:none
Valid Values:[none, all]
Importance:medium

A host:port pair pointing to a user-defined endpoint that can be used for state store discovery and interactive queries on this KafkaStreams instance.

Type:string
Default:“”
Valid Values:
Importance:low

Maximum number of records to buffer per partition.

Type:int
Default:1000
Valid Values:
Importance:low

Version of the built-in metrics to use.

Type:string
Default:latest
Valid Values:[0.10.0-2.4, latest]
Importance:low

The frequency with which to save the position of the processor. (Note, if processing.guarantee is set to exactly_once, the default value is 100, otherwise the default value is 30000.

Type:long
Default:30000 (30 seconds)
Valid Values:[0,…]
Importance:low

Close idle connections after the number of milliseconds specified by this config.

Type:long
Default:540000 (9 minutes)
Valid Values:
Importance:low

The period of time in milliseconds after which we force a refresh of metadata even if we haven’t seen any partition leadership changes to proactively discover any new brokers or partitions.

Type:long
Default:300000 (5 minutes)
Valid Values:[0,…]
Importance:low

A list of classes to use as metrics reporters. Implementing the org.apache.kafka.common.metrics.MetricsReporter interface allows plugging in classes that will be notified of new metric creation. The JmxReporter is always included to register JMX statistics.

Type:list
Default:“”
Valid Values:
Importance:low

The number of samples maintained to compute metrics.

Type:int
Default:2
Valid Values:[1,…]
Importance:low

The highest recording level for metrics.

Type:string
Default:INFO
Valid Values:[INFO, DEBUG]
Importance:low

The window of time a metrics sample is computed over.

Type:long
Default:30000 (30 seconds)
Valid Values:[0,…]
Importance:low

Partition grouper class that implements the org.apache.kafka.streams.processor.PartitionGrouper interface. WARNING: This config is deprecated and will be removed in 3.0.0 release.

Type:class
Default:org.apache.kafka.streams.processor.DefaultPartitionGrouper
Valid Values:
Importance:low

The amount of time in milliseconds to block waiting for input.

Type:long
Default:100
Valid Values:
Importance:low

The maximum time to wait before triggering a rebalance to probe for warmup replicas that have finished warming up and are ready to become active. Probing rebalances will continue to be triggered until the assignment is balanced. Must be at least 1 minute.

Type:long
Default:600000 (10 minutes)
Valid Values:[60000,…]
Importance:low

The size of the TCP receive buffer (SO_RCVBUF) to use when reading data. If the value is -1, the OS default will be used.

Type:int
Default:32768 (32 kibibytes)
Valid Values:[-1,…]
Importance:low

The maximum amount of time in milliseconds to wait when reconnecting to a broker that has repeatedly failed to connect. If provided, the backoff per host will increase exponentially for each consecutive connection failure, up to this maximum. After calculating the backoff increase, 20% random jitter is added to avoid connection storms.

Type:long
Default:1000 (1 second)
Valid Values:[0,…]
Importance:low

The base amount of time to wait before attempting to reconnect to a given host. This avoids repeatedly connecting to a host in a tight loop. This backoff applies to all connection attempts by the client to a broker.

Type:long
Default:50
Valid Values:[0,…]
Importance:low

The configuration controls the maximum amount of time the client will wait for the response of a request. If the response is not received before the timeout elapses the client will resend the request if necessary or fail the request if retries are exhausted.

Type:int
Default:40000 (40 seconds)
Valid Values:[0,…]
Importance:low

Setting a value greater than zero will cause the client to resend any request that fails with a potentially transient error.

Type:int
Default:0
Valid Values:[0,…,2147483647]
Importance:low

The amount of time to wait before attempting to retry a failed request to a given topic partition. This avoids repeatedly sending requests in a tight loop under some failure scenarios.

Type:long
Default:100
Valid Values:[0,…]
Importance:low

A Rocks DB config setter class or class name that implements the org.apache.kafka.streams.state.RocksDBConfigSetter interface

Type:class
Default:null
Valid Values:
Importance:low

The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used.

Type:int
Default:131072 (128 kibibytes)
Valid Values:[-1,…]
Importance:low

The amount of time in milliseconds to wait before deleting state when a partition has migrated. Only state directories that have not been modified for at least state.cleanup.delay.ms will be removed

Type:long
Default:600000 (10 minutes)
Valid Values:
Importance:low

Allows upgrading in a backward compatible way. This is needed when upgrading from [0.10.0, 1.1] to 2.0+, or when upgrading from [2.0, 2.3] to 2.4+. When upgrading from 2.4 to a newer version it is not required to specify this config. Default is `null`. Accepted values are “0.10.0”, “0.10.1”, “0.10.2”, “0.11.0”, “1.0”, “1.1”, “2.0”, “2.1”, “2.2”, “2.3” (for upgrading from the corresponding old version).

Type:string
Default:null
Valid Values:[null, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 1.0, 1.1, 2.0, 2.1, 2.2, 2.3]
Importance:low

Added to a windows maintainMs to ensure data is not deleted from the log prematurely. Allows for clock drift. Default is 1 day

Type:long
Default:86400000 (1 day)
Valid Values:
Importance:low