Streams Configurations

This topic provides configuration parameters available for Confluent Platform. The parameters are organized by order of importance, ranked from high to low.

• application.id

  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

• bootstrap.servers

  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

• replication.factor

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

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

• state.dir

  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

• acceptable.recovery.lag

  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

• cache.max.bytes.buffering

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

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

• client.id

  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

• default.deserialization.exception.handler

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

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

• default.key.serde

  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

• default.production.exception.handler

  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

  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.value.serde

  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

• default.windowed.key.serde.inner

  Default serializer / deserializer for the inner class of a windowed key. Must implement the org.apache.kafka.common.serialization.Serde interface.

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

• default.windowed.value.serde.inner

  Default serializer / deserializer for the inner class of a windowed value. Must implement the org.apache.kafka.common.serialization.Serde interface.

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

• max.task.idle.ms

  Maximum amount of time in milliseconds 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

• max.warmup.replicas

  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

• num.standby.replicas

  The number of standby replicas for each task.

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

• num.stream.threads

  The number of threads to execute stream processing.

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

• processing.guarantee

  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

• security.protocol

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

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

• task.timeout.ms

  The maximum amount of time in milliseconds a task might stall due to internal errors and retries until an error is raised. For a timeout of 0ms, a task would raise an error for the first internal error. For any timeout larger than 0ms, a task will retry at least once before an error is raised.

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

• topology.optimization

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

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

• application.server

  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

• buffered.records.per.partition

  Maximum number of records to buffer per partition.

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

• built.in.metrics.version

  Version of the built-in metrics to use.

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

• commit.interval.ms

  The frequency in milliseconds 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

• connections.max.idle.ms

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

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

• metadata.max.age.ms

  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

• metric.reporters

  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

• metrics.num.samples

  The number of samples maintained to compute metrics.

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

• metrics.recording.level

  The highest recording level for metrics.

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

• metrics.sample.window.ms

  The window of time a metrics sample is computed over.

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

• partition.grouper

  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

• poll.ms

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

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

• probing.rebalance.interval.ms

  The maximum time in milliseconds 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

• receive.buffer.bytes

  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

• reconnect.backoff.max.ms

  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

• reconnect.backoff.ms

  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

• request.timeout.ms

  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

• retries

  Setting a value greater than zero will cause the client to resend any request that fails with a potentially transient error. It is recommended to set the value to either zero or `MAX_VALUE` and use corresponding timeout parameters to control how long a client should retry a request.

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

• retry.backoff.ms

  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

• rocksdb.config.setter

  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

• send.buffer.bytes

  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

• state.cleanup.delay.ms

  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

• upgrade.from

  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

• windowstore.changelog.additional.retention.ms

  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

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