API Reference¶
kafka¶
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kafka.codec.
snappy_encode
(payload, xerial_compatible=False, xerial_blocksize=32768)[source]¶ Encodes the given data with snappy if xerial_compatible is set then the stream is encoded in a fashion compatible with the xerial snappy library
The block size (xerial_blocksize) controls how frequent the blocking occurs 32k is the default in the xerial library.
- The format winds up being
- Header16 bytes
Block1 len Block1 data Blockn len Blockn datasnappy bytesBE int32 snappy bytes BE int32 It is important to not that the blocksize is the amount of uncompressed data presented to snappy at each block, whereas the blocklen is the number of bytes that will be present in the stream, that is the length will always be <= blocksize.
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class
kafka.common.
BrokerMetadata
(nodeId, host, port)¶ -
host
¶ Alias for field number 1
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nodeId
¶ Alias for field number 0
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port
¶ Alias for field number 2
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class
kafka.common.
FetchRequest
(topic, partition, offset, max_bytes)¶ -
max_bytes
¶ Alias for field number 3
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offset
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
FetchResponse
(topic, partition, error, highwaterMark, messages)¶ -
error
¶ Alias for field number 2
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highwaterMark
¶ Alias for field number 3
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messages
¶ Alias for field number 4
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
KafkaMessage
(topic, partition, offset, key, value)¶ -
key
¶ Alias for field number 3
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offset
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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value
¶ Alias for field number 4
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class
kafka.common.
Message
(magic, attributes, key, value)¶ -
attributes
¶ Alias for field number 1
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key
¶ Alias for field number 2
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magic
¶ Alias for field number 0
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value
¶ Alias for field number 3
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class
kafka.common.
MetadataResponse
(brokers, topics)¶ -
brokers
¶ Alias for field number 0
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topics
¶ Alias for field number 1
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class
kafka.common.
OffsetAndMessage
(offset, message)¶ -
message
¶ Alias for field number 1
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offset
¶ Alias for field number 0
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class
kafka.common.
OffsetCommitRequest
(topic, partition, offset, metadata)¶ -
metadata
¶ Alias for field number 3
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offset
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
OffsetCommitResponse
(topic, partition, error)¶ -
error
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
OffsetFetchRequest
(topic, partition)¶ -
partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
OffsetFetchResponse
(topic, partition, offset, metadata, error)¶ -
error
¶ Alias for field number 4
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metadata
¶ Alias for field number 3
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offset
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
OffsetRequest
(topic, partition, time, max_offsets)¶ -
max_offsets
¶ Alias for field number 3
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partition
¶ Alias for field number 1
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time
¶ Alias for field number 2
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topic
¶ Alias for field number 0
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class
kafka.common.
OffsetResponse
(topic, partition, error, offsets)¶ -
error
¶ Alias for field number 2
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offsets
¶ Alias for field number 3
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
PartitionMetadata
(topic, partition, leader, replicas, isr, error)¶ -
error
¶ Alias for field number 5
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isr
¶ Alias for field number 4
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leader
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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replicas
¶ Alias for field number 3
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topic
¶ Alias for field number 0
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class
kafka.common.
ProduceRequest
(topic, partition, messages)¶ -
messages
¶ Alias for field number 2
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
ProduceResponse
(topic, partition, error, offset)¶ -
error
¶ Alias for field number 2
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offset
¶ Alias for field number 3
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partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
TopicAndPartition
(topic, partition)¶ -
partition
¶ Alias for field number 1
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topic
¶ Alias for field number 0
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class
kafka.common.
TopicMetadata
(topic, error, partitions)¶ -
error
¶ Alias for field number 1
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partitions
¶ Alias for field number 2
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topic
¶ Alias for field number 0
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class
kafka.conn.
KafkaConnection
(host, port, timeout=120)[source]¶ A socket connection to a single Kafka broker
This class is _not_ thread safe. Each call to send must be followed by a call to recv in order to get the correct response. Eventually, we can do something in here to facilitate multiplexed requests/responses since the Kafka API includes a correlation id.
- Arguments:
host: the host name or IP address of a kafka broker port: the port number the kafka broker is listening on timeout: default 120. The socket timeout for sending and receiving data
in seconds. None means no timeout, so a request can block forever.
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copy
()[source]¶ Create an inactive copy of the connection object A reinit() has to be done on the copy before it can be used again return a new KafkaConnection object
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recv
(request_id)[source]¶ Get a response packet from Kafka
- Arguments:
- request_id: can be any int (only used for debug logging...)
- Returns:
- str: Encoded kafka packet response from server
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kafka.conn.
collect_hosts
(hosts, randomize=True)[source]¶ Collects a comma-separated set of hosts (host:port) and optionally randomize the returned list.
Context manager to commit/rollback consumer offsets.
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class
kafka.context.
OffsetCommitContext
(consumer)[source]¶ Provides commit/rollback semantics around a SimpleConsumer.
Usage assumes that auto_commit is disabled, that messages are consumed in batches, and that the consuming process will record its own successful processing of each message. Both the commit and rollback operations respect a “high-water mark” to ensure that last unsuccessfully processed message will be retried.
Example:
consumer = SimpleConsumer(client, group, topic, auto_commit=False) consumer.provide_partition_info() consumer.fetch_last_known_offsets() while some_condition: with OffsetCommitContext(consumer) as context: messages = consumer.get_messages(count, block=False) for partition, message in messages: if can_process(message): context.mark(partition, message.offset) else: break if not context: sleep(delay)
These semantics allow for deferred message processing (e.g. if can_process compares message time to clock time) and for repeated processing of the last unsuccessful message (until some external error is resolved).
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commit
()[source]¶ Commit this context’s offsets:
- If the high-water mark has moved, commit up to and position the consumer at the high-water mark.
- Otherwise, reset to the consumer to the initial offsets.
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handle_out_of_range
()[source]¶ Handle out of range condition by seeking to the beginning of valid ranges.
This assumes that an out of range doesn’t happen by seeking past the end of valid ranges – which is far less likely.
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class
kafka.protocol.
KafkaProtocol
[source]¶ Class to encapsulate all of the protocol encoding/decoding. This class does not have any state associated with it, it is purely for organization.
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classmethod
decode_fetch_response
(data)[source]¶ Decode bytes to a FetchResponse
- Arguments:
- data: bytes to decode
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classmethod
decode_metadata_response
(data)[source]¶ Decode bytes to a MetadataResponse
- Arguments:
- data: bytes to decode
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classmethod
decode_offset_commit_response
(data)[source]¶ Decode bytes to an OffsetCommitResponse
- Arguments:
- data: bytes to decode
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classmethod
decode_offset_fetch_response
(data)[source]¶ Decode bytes to an OffsetFetchResponse
- Arguments:
- data: bytes to decode
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classmethod
decode_offset_response
(data)[source]¶ Decode bytes to an OffsetResponse
- Arguments:
- data: bytes to decode
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classmethod
decode_produce_response
(data)[source]¶ Decode bytes to a ProduceResponse
- Arguments:
- data: bytes to decode
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classmethod
encode_fetch_request
(client_id, correlation_id, payloads=None, max_wait_time=100, min_bytes=4096)[source]¶ Encodes some FetchRequest structs
- Arguments:
client_id: string correlation_id: int payloads: list of FetchRequest max_wait_time: int, how long to block waiting on min_bytes of data min_bytes: int, the minimum number of bytes to accumulate before
returning the response
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classmethod
encode_metadata_request
(client_id, correlation_id, topics=None, payloads=None)[source]¶ Encode a MetadataRequest
- Arguments:
- client_id: string correlation_id: int topics: list of strings
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classmethod
encode_offset_commit_request
(client_id, correlation_id, group, payloads)[source]¶ Encode some OffsetCommitRequest structs
- Arguments:
- client_id: string correlation_id: int group: string, the consumer group you are committing offsets for payloads: list of OffsetCommitRequest
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classmethod
encode_offset_fetch_request
(client_id, correlation_id, group, payloads)[source]¶ Encode some OffsetFetchRequest structs
- Arguments:
- client_id: string correlation_id: int group: string, the consumer group you are fetching offsets for payloads: list of OffsetFetchRequest
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classmethod
encode_produce_request
(client_id, correlation_id, payloads=None, acks=1, timeout=1000)[source]¶ Encode some ProduceRequest structs
- Arguments:
client_id: string correlation_id: int payloads: list of ProduceRequest acks: How “acky” you want the request to be
0: immediate response 1: written to disk by the leader 2+: waits for this many number of replicas to sync -1: waits for all replicas to be in sync- timeout: Maximum time the server will wait for acks from replicas.
- This is _not_ a socket timeout
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classmethod
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kafka.protocol.
create_gzip_message
(payloads, key=None)[source]¶ Construct a Gzipped Message containing multiple Messages
The given payloads will be encoded, compressed, and sent as a single atomic message to Kafka.
- Arguments:
- payloads: list(bytes), a list of payload to send be sent to Kafka key: bytes, a key used for partition routing (optional)
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kafka.protocol.
create_message
(payload, key=None)[source]¶ Construct a Message
- Arguments:
- payload: bytes, the payload to send to Kafka key: bytes, a key used for partition routing (optional)
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kafka.protocol.
create_message_set
(messages, codec=0, key=None)[source]¶ Create a message set using the given codec.
If codec is CODEC_NONE, return a list of raw Kafka messages. Otherwise, return a list containing a single codec-encoded message.
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kafka.protocol.
create_snappy_message
(payloads, key=None)[source]¶ Construct a Snappy Message containing multiple Messages
The given payloads will be encoded, compressed, and sent as a single atomic message to Kafka.
- Arguments:
- payloads: list(bytes), a list of payload to send be sent to Kafka key: bytes, a key used for partition routing (optional)
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class
kafka.util.
ReentrantTimer
(t, fn, *args, **kwargs)[source]¶ A timer that can be restarted, unlike threading.Timer (although this uses threading.Timer)
Arguments:
t: timer interval in milliseconds fn: a callable to invoke args: tuple of args to be passed to function kwargs: keyword arguments to be passed to function
kafka.consumer¶
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class
kafka.consumer.base.
Consumer
(client, group, topic, partitions=None, auto_commit=True, auto_commit_every_n=100, auto_commit_every_t=5000)[source]¶ Base class to be used by other consumers. Not to be used directly
This base class provides logic for
- initialization and fetching metadata of partitions
- Auto-commit logic
- APIs for fetching pending message count
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class
kafka.consumer.kafka.
KafkaConsumer
(*topics, **configs)[source]¶ A simpler kafka consumer
# A very basic 'tail' consumer, with no stored offset management kafka = KafkaConsumer('topic1') for m in kafka: print m # Alternate interface: next() print kafka.next() # Alternate interface: batch iteration while True: for m in kafka.fetch_messages(): print m print "Done with batch - let's do another!"
# more advanced consumer -- multiple topics w/ auto commit offset management kafka = KafkaConsumer('topic1', 'topic2', group_id='my_consumer_group', auto_commit_enable=True, auto_commit_interval_ms=30 * 1000, auto_offset_reset='smallest') # Infinite iteration for m in kafka: process_message(m) kafka.task_done(m) # Alternate interface: next() m = kafka.next() process_message(m) kafka.task_done(m) # If auto_commit_enable is False, remember to commit() periodically kafka.commit() # Batch process interface while True: for m in kafka.fetch_messages(): process_message(m) kafka.task_done(m)
messages (m) are namedtuples with attributes:
- m.topic: topic name (str)
- m.partition: partition number (int)
- m.offset: message offset on topic-partition log (int)
- m.key: key (bytes - can be None)
- m.value: message (output of deserializer_class - default is raw bytes)
Configuration settings can be passed to constructor, otherwise defaults will be used:
client_id='kafka.consumer.kafka', group_id=None, fetch_message_max_bytes=1024*1024, fetch_min_bytes=1, fetch_wait_max_ms=100, refresh_leader_backoff_ms=200, metadata_broker_list=None, socket_timeout_ms=30*1000, auto_offset_reset='largest', deserializer_class=lambda msg: msg, auto_commit_enable=False, auto_commit_interval_ms=60 * 1000, consumer_timeout_ms=-1
Configuration parameters are described in more detail at http://kafka.apache.org/documentation.html#highlevelconsumerapi
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commit
()[source]¶ Store consumed message offsets (marked via task_done()) to kafka cluster for this consumer_group.
Note: this functionality requires server version >=0.8.1.1 See this wiki page.
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configure
(**configs)[source]¶ Configuration settings can be passed to constructor, otherwise defaults will be used:
client_id='kafka.consumer.kafka', group_id=None, fetch_message_max_bytes=1024*1024, fetch_min_bytes=1, fetch_wait_max_ms=100, refresh_leader_backoff_ms=200, metadata_broker_list=None, socket_timeout_ms=30*1000, auto_offset_reset='largest', deserializer_class=lambda msg: msg, auto_commit_enable=False, auto_commit_interval_ms=60 * 1000, auto_commit_interval_messages=None, consumer_timeout_ms=-1
Configuration parameters are described in more detail at http://kafka.apache.org/documentation.html#highlevelconsumerapi
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fetch_messages
()[source]¶ Sends FetchRequests for all topic/partitions set for consumption Returns a generator that yields KafkaMessage structs after deserializing with the configured deserializer_class
Refreshes metadata on errors, and resets fetch offset on OffsetOutOfRange, per the configured auto_offset_reset policy
Key configuration parameters:
- fetch_message_max_bytes
- fetch_max_wait_ms
- fetch_min_bytes
- deserializer_class
- auto_offset_reset
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get_partition_offsets
(topic, partition, request_time_ms, max_num_offsets)[source]¶ Request available fetch offsets for a single topic/partition
- Arguments:
topic (str) partition (int) request_time_ms (int): Used to ask for all messages before a
certain time (ms). There are two special values. Specify -1 to receive the latest offset (i.e. the offset of the next coming message) and -2 to receive the earliest available offset. Note that because offsets are pulled in descending order, asking for the earliest offset will always return you a single element.max_num_offsets (int)
- Returns:
- offsets (list)
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next
()[source]¶ Return a single message from the message iterator If consumer_timeout_ms is set, will raise ConsumerTimeout if no message is available Otherwise blocks indefinitely
Note that this is also the method called internally during iteration:
for m in consumer: pass
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offsets
(group=None)[source]¶ - Keyword Arguments:
- group: Either “fetch”, “commit”, “task_done”, or “highwater”.
- If no group specified, returns all groups.
- Returns:
- A copy of internal offsets struct
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set_topic_partitions
(*topics)[source]¶ Set the topic/partitions to consume Optionally specify offsets to start from
Accepts types:
str (utf-8): topic name (will consume all available partitions)
tuple: (topic, partition)
- dict:
- { topic: partition }
- { topic: [partition list] }
- { topic: (partition tuple,) }
Optionally, offsets can be specified directly:
- tuple: (topic, partition, offset)
- dict: { (topic, partition): offset, ... }
Example:
kafka = KafkaConsumer() # Consume topic1-all; topic2-partition2; topic3-partition0 kafka.set_topic_partitions("topic1", ("topic2", 2), {"topic3": 0}) # Consume topic1-0 starting at offset 123, and topic2-1 at offset 456 # using tuples -- kafka.set_topic_partitions(("topic1", 0, 123), ("topic2", 1, 456)) # using dict -- kafka.set_topic_partitions({ ("topic1", 0): 123, ("topic2", 1): 456 })
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class
kafka.consumer.kafka.
OffsetsStruct
(fetch, highwater, commit, task_done)¶ -
commit
¶ Alias for field number 2
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fetch
¶ Alias for field number 0
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highwater
¶ Alias for field number 1
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task_done
¶ Alias for field number 3
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class
kafka.consumer.multiprocess.
MultiProcessConsumer
(client, group, topic, auto_commit=True, auto_commit_every_n=100, auto_commit_every_t=5000, num_procs=1, partitions_per_proc=0)[source]¶ A consumer implementation that consumes partitions for a topic in parallel using multiple processes
- Arguments:
- client: a connected KafkaClient group: a name for this consumer, used for offset storage and must be unique topic: the topic to consume
- Keyword Arguments:
auto_commit: default True. Whether or not to auto commit the offsets auto_commit_every_n: default 100. How many messages to consume
before a commit- auto_commit_every_t: default 5000. How much time (in milliseconds) to
- wait before commit
- num_procs: Number of processes to start for consuming messages.
- The available partitions will be divided among these processes
- partitions_per_proc: Number of partitions to be allocated per process
- (overrides num_procs)
Auto commit details: If both auto_commit_every_n and auto_commit_every_t are set, they will reset one another when one is triggered. These triggers simply call the commit method on this class. A manual call to commit will also reset these triggers
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get_messages
(count=1, block=True, timeout=10)[source]¶ Fetch the specified number of messages
- Keyword Arguments:
count: Indicates the maximum number of messages to be fetched block: If True, the API will block till some messages are fetched. timeout: If block is True, the function will block for the specified
time (in seconds) until count messages is fetched. If None, it will block forever.
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class
kafka.consumer.simple.
FetchContext
(consumer, block, timeout)[source]¶ Class for managing the state of a consumer during fetch
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class
kafka.consumer.simple.
SimpleConsumer
(client, group, topic, auto_commit=True, partitions=None, auto_commit_every_n=100, auto_commit_every_t=5000, fetch_size_bytes=4096, buffer_size=4096, max_buffer_size=32768, iter_timeout=None)[source]¶ A simple consumer implementation that consumes all/specified partitions for a topic
- Arguments:
- client: a connected KafkaClient group: a name for this consumer, used for offset storage and must be unique topic: the topic to consume
- Keyword Arguments:
partitions: An optional list of partitions to consume the data from
auto_commit: default True. Whether or not to auto commit the offsets
- auto_commit_every_n: default 100. How many messages to consume
- before a commit
- auto_commit_every_t: default 5000. How much time (in milliseconds) to
- wait before commit
fetch_size_bytes: number of bytes to request in a FetchRequest
- buffer_size: default 4K. Initial number of bytes to tell kafka we
- have available. This will double as needed.
- max_buffer_size: default 16K. Max number of bytes to tell kafka we have
- available. None means no limit.
- iter_timeout: default None. How much time (in seconds) to wait for a
- message in the iterator before exiting. None means no timeout, so it will wait forever.
Auto commit details: If both auto_commit_every_n and auto_commit_every_t are set, they will reset one another when one is triggered. These triggers simply call the commit method on this class. A manual call to commit will also reset these triggers
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get_messages
(count=1, block=True, timeout=0.1)[source]¶ Fetch the specified number of messages
- Keyword Arguments:
count: Indicates the maximum number of messages to be fetched block: If True, the API will block till some messages are fetched. timeout: If block is True, the function will block for the specified
time (in seconds) until count messages is fetched. If None, it will block forever.
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seek
(offset, whence)[source]¶ Alter the current offset in the consumer, similar to fseek
- Arguments:
offset: how much to modify the offset whence: where to modify it from
- 0 is relative to the earliest available offset (head)
- 1 is relative to the current offset
- 2 is relative to the latest known offset (tail)
kafka.partitioner¶
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class
kafka.partitioner.base.
Partitioner
(partitions)[source]¶ Base class for a partitioner
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partition
(key, partitions)[source]¶ Takes a string key and num_partitions as argument and returns a partition to be used for the message
- Arguments:
- partitions: The list of partitions is passed in every call. This
- may look like an overhead, but it will be useful (in future) when we handle cases like rebalancing
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kafka.producer¶
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class
kafka.producer.base.
Producer
(client, async=False, req_acks=1, ack_timeout=1000, codec=None, batch_send=False, batch_send_every_n=20, batch_send_every_t=20)[source]¶ Base class to be used by producers
- Arguments:
client: The Kafka client instance to use async: If set to true, the messages are sent asynchronously via another
thread (process). We will not wait for a response to these WARNING!!! current implementation of async producer does not guarantee message delivery. Use at your own risk! Or help us improve with a PR!- req_acks: A value indicating the acknowledgements that the server must
- receive before responding to the request
- ack_timeout: Value (in milliseconds) indicating a timeout for waiting
- for an acknowledgement
batch_send: If True, messages are send in batches batch_send_every_n: If set, messages are send in batches of this size batch_send_every_t: If set, messages are send after this timeout
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send_messages
(topic, partition, *msg)[source]¶ Helper method to send produce requests @param: topic, name of topic for produce request – type str @param: partition, partition number for produce request – type int @param: *msg, one or more message payloads – type bytes @returns: ResponseRequest returned by server raises on error
Note that msg type must be encoded to bytes by user. Passing unicode message will not work, for example you should encode before calling send_messages via something like unicode_message.encode(‘utf-8’)
All messages produced via this method will set the message ‘key’ to Null
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class
kafka.producer.keyed.
KeyedProducer
(client, partitioner=None, async=False, req_acks=1, ack_timeout=1000, codec=None, batch_send=False, batch_send_every_n=20, batch_send_every_t=20)[source]¶ A producer which distributes messages to partitions based on the key
- Arguments:
- client: The kafka client instance
- Keyword Arguments:
- partitioner: A partitioner class that will be used to get the partition
- to send the message to. Must be derived from Partitioner
- async: If True, the messages are sent asynchronously via another
- thread (process). We will not wait for a response to these
- ack_timeout: Value (in milliseconds) indicating a timeout for waiting
- for an acknowledgement
batch_send: If True, messages are send in batches batch_send_every_n: If set, messages are send in batches of this size batch_send_every_t: If set, messages are send after this timeout
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class
kafka.producer.simple.
SimpleProducer
(client, async=False, req_acks=1, ack_timeout=1000, codec=None, batch_send=False, batch_send_every_n=20, batch_send_every_t=20, random_start=True)[source]¶ A simple, round-robin producer. Each message goes to exactly one partition
- Arguments:
- client: The Kafka client instance to use
- Keyword Arguments:
- async: If True, the messages are sent asynchronously via another
- thread (process). We will not wait for a response to these
- req_acks: A value indicating the acknowledgements that the server must
- receive before responding to the request
- ack_timeout: Value (in milliseconds) indicating a timeout for waiting
- for an acknowledgement
batch_send: If True, messages are send in batches batch_send_every_n: If set, messages are send in batches of this size batch_send_every_t: If set, messages are send after this timeout random_start: If true, randomize the initial partition which the
the first message block will be published to, otherwise if false, the first message block will always publish to partition 0 before cycling through each partition