Source code for pyspark.streaming.kafka

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from py4j.java_collections import MapConverter
from py4j.java_gateway import java_import, Py4JError, Py4JJavaError

from pyspark.storagelevel import StorageLevel
from pyspark.serializers import PairDeserializer, NoOpSerializer
from pyspark.streaming import DStream

__all__ = ['KafkaUtils', 'utf8_decoder']

[docs]def utf8_decoder(s): """ Decode the unicode as UTF-8 """ return s and s.decode('utf-8')
[docs]class KafkaUtils(object): @staticmethod
[docs] def createStream(ssc, zkQuorum, groupId, topics, kafkaParams={}, storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2, keyDecoder=utf8_decoder, valueDecoder=utf8_decoder): """ Create an input stream that pulls messages from a Kafka Broker. :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 kafkaParams: Additional params for Kafka :param storageLevel: RDD storage level. :param keyDecoder: A function used to decode key (default is utf8_decoder) :param valueDecoder: A function used to decode value (default is utf8_decoder) :return: A DStream object """ kafkaParams.update({ "zookeeper.connect": zkQuorum, "": groupId, "": "10000", }) if not isinstance(topics, dict): raise TypeError("topics should be dict") jtopics = MapConverter().convert(topics, ssc.sparkContext._gateway._gateway_client) jparam = MapConverter().convert(kafkaParams, ssc.sparkContext._gateway._gateway_client) jlevel = ssc._sc._getJavaStorageLevel(storageLevel) try: # Use KafkaUtilsPythonHelper to access Scala's KafkaUtils (see SPARK-6027) helperClass =\ .loadClass("org.apache.spark.streaming.kafka.KafkaUtilsPythonHelper") helper = helperClass.newInstance() jstream = helper.createStream(ssc._jssc, jparam, jtopics, jlevel) except Py4JJavaError, e: # TODO: use --jar once it also work on driver if 'ClassNotFoundException' in str(e.java_exception): print """ ________________________________________________________________________________________________ Spark Streaming's Kafka libraries not found in class path. Try one of the following. 1. Include the Kafka library and its dependencies with in the spark-submit command as $ bin/spark-submit --packages org.apache.spark:spark-streaming-kafka:%s ... 2. Download the JAR of the artifact from Maven Central, Group Id = org.apache.spark, Artifact Id = spark-streaming-kafka-assembly, Version = %s. Then, include the jar in the spark-submit command as $ bin/spark-submit --jars <spark-streaming-kafka-assembly.jar> ... ________________________________________________________________________________________________ """ % (ssc.sparkContext.version, ssc.sparkContext.version) raise e ser = PairDeserializer(NoOpSerializer(), NoOpSerializer()) stream = DStream(jstream, ssc, ser) return (k, v): (keyDecoder(k), valueDecoder(v)))