0561c45449
This PR brings the Python API for Spark Streaming Kafka data source.
```
class KafkaUtils(__builtin__.object)
| Static methods defined here:
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| createStream(ssc, zkQuorum, groupId, topics, storageLevel=StorageLevel(True, True, False, False,
2), keyDecoder=<function utf8_decoder>, valueDecoder=<function utf8_decoder>)
| Create an input stream that pulls messages from a Kafka Broker.
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| :param ssc: StreamingContext object
| :param zkQuorum: Zookeeper quorum (hostname:port,hostname:port,..).
| :param groupId: The group id for this consumer.
| :param topics: Dict of (topic_name -> numPartitions) to consume.
| Each partition is consumed in its own thread.
| :param storageLevel: RDD storage level.
| :param keyDecoder: A function used to decode key
| :param valueDecoder: A function used to decode value
| :return: A DStream object
```
run the example:
```
bin/spark-submit --driver-class-path external/kafka-assembly/target/scala-*/spark-streaming-kafka-assembly-*.jar examples/src/main/python/streaming/kafka_wordcount.py localhost:2181 test
```
Author: Davies Liu <davies@databricks.com>
Author: Tathagata Das <tdas@databricks.com>
Closes #3715 from davies/kafka and squashes the following commits:
d93bfe0 [Davies Liu] Update make-distribution.sh
4280d04 [Davies Liu] address comments
e6d0427 [Davies Liu] Merge branch 'master' of github.com:apache/spark into kafka
f257071 [Davies Liu] add tests for null in RDD
23b039a [Davies Liu] address comments
9af51c4 [Davies Liu] Merge branch 'kafka' of github.com:davies/spark into kafka
a74da87 [Davies Liu] address comments
dc1eed0 [Davies Liu] Update kafka_wordcount.py
31e2317 [Davies Liu] Update kafka_wordcount.py
370ba61 [Davies Liu] Update kafka.py
97386b3 [Davies Liu] address comment
2c567a5 [Davies Liu] update logging and comment
33730d1 [Davies Liu] Merge branch 'master' of github.com:apache/spark into kafka
adeeb38 [Davies Liu] Merge pull request #3 from tdas/kafka-python-api
aea8953 [Tathagata Das] Kafka-assembly for Python API
eea16a7 [Davies Liu] refactor
f6ce899 [Davies Liu] add example and fix bugs
98c8d17 [Davies Liu] fix python style
5697a01 [Davies Liu] bypass decoder in scala
048dbe6 [Davies Liu] fix python style
75d485e [Davies Liu] add mqtt
07923c4 [Davies Liu] support kafka in Python
84 lines
3.7 KiB
Python
84 lines
3.7 KiB
Python
#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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from py4j.java_collections import MapConverter
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from py4j.java_gateway import java_import, Py4JError
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from pyspark.storagelevel import StorageLevel
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from pyspark.serializers import PairDeserializer, NoOpSerializer
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from pyspark.streaming import DStream
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__all__ = ['KafkaUtils', 'utf8_decoder']
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def utf8_decoder(s):
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""" Decode the unicode as UTF-8 """
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return s and s.decode('utf-8')
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class KafkaUtils(object):
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@staticmethod
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def createStream(ssc, zkQuorum, groupId, topics, kafkaParams={},
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storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
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keyDecoder=utf8_decoder, valueDecoder=utf8_decoder):
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"""
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Create an input stream that pulls messages from a Kafka Broker.
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:param ssc: StreamingContext object
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:param zkQuorum: Zookeeper quorum (hostname:port,hostname:port,..).
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:param groupId: The group id for this consumer.
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:param topics: Dict of (topic_name -> numPartitions) to consume.
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Each partition is consumed in its own thread.
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:param kafkaParams: Additional params for Kafka
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:param storageLevel: RDD storage level.
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:param keyDecoder: A function used to decode key (default is utf8_decoder)
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:param valueDecoder: A function used to decode value (default is utf8_decoder)
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:return: A DStream object
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"""
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java_import(ssc._jvm, "org.apache.spark.streaming.kafka.KafkaUtils")
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kafkaParams.update({
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"zookeeper.connect": zkQuorum,
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"group.id": groupId,
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"zookeeper.connection.timeout.ms": "10000",
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})
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if not isinstance(topics, dict):
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raise TypeError("topics should be dict")
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jtopics = MapConverter().convert(topics, ssc.sparkContext._gateway._gateway_client)
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jparam = MapConverter().convert(kafkaParams, ssc.sparkContext._gateway._gateway_client)
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jlevel = ssc._sc._getJavaStorageLevel(storageLevel)
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def getClassByName(name):
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return ssc._jvm.org.apache.spark.util.Utils.classForName(name)
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try:
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array = getClassByName("[B")
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decoder = getClassByName("kafka.serializer.DefaultDecoder")
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jstream = ssc._jvm.KafkaUtils.createStream(ssc._jssc, array, array, decoder, decoder,
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jparam, jtopics, jlevel)
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except Py4JError, e:
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# TODO: use --jar once it also work on driver
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if not e.message or 'call a package' in e.message:
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print "No kafka package, please put the assembly jar into classpath:"
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print " $ bin/spark-submit --driver-class-path external/kafka-assembly/target/" + \
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"scala-*/spark-streaming-kafka-assembly-*.jar"
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raise e
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ser = PairDeserializer(NoOpSerializer(), NoOpSerializer())
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stream = DStream(jstream, ssc, ser)
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return stream.map(lambda (k, v): (keyDecoder(k), valueDecoder(v)))
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