python/streaming/stateful_network_wordcount.py

0001 #
0002 # Licensed to the Apache Software Foundation (ASF) under one or more
0003 # contributor license agreements.  See the NOTICE file distributed with
0004 # this work for additional information regarding copyright ownership.
0005 # The ASF licenses this file to You under the Apache License, Version 2.0
0006 # (the "License"); you may not use this file except in compliance with
0007 # the License.  You may obtain a copy of the License at
0008 #
0009 #    http://www.apache.org/licenses/LICENSE-2.0
0010 #
0011 # Unless required by applicable law or agreed to in writing, software
0012 # distributed under the License is distributed on an "AS IS" BASIS,
0013 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0014 # See the License for the specific language governing permissions and
0015 # limitations under the License.
0016 #
0017
0018 r"""
0019  Counts words in UTF8 encoded, '\n' delimited text received from the
0020  network every second.
0021
0022  Usage: stateful_network_wordcount.py <hostname> <port>
0023    <hostname> and <port> describe the TCP server that Spark Streaming
0024     would connect to receive data.
0025
0026  To run this on your local machine, you need to first run a Netcat server
0027     `$ nc -lk 9999`
0028  and then run the example
0029     `$ bin/spark-submit examples/src/main/python/streaming/stateful_network_wordcount.py \
0030         localhost 9999`
0031 """
0032 from __future__ import print_function
0033
0034 import sys
0035
0036 from pyspark import SparkContext
0037 from pyspark.streaming import StreamingContext
0038
0039 if __name__ == "__main__":
0040     if len(sys.argv) != 3:
0041         print("Usage: stateful_network_wordcount.py <hostname> <port>", file=sys.stderr)
0042         sys.exit(-1)
0043     sc = SparkContext(appName="PythonStreamingStatefulNetworkWordCount")
0044     ssc = StreamingContext(sc, 1)
0045     ssc.checkpoint("checkpoint")
0046
0047     # RDD with initial state (key, value) pairs
0048     initialStateRDD = sc.parallelize([(u'hello', 1), (u'world', 1)])
0049
0050     def updateFunc(new_values, last_sum):
0051         return sum(new_values) + (last_sum or 0)
0052
0053     lines = ssc.socketTextStream(sys.argv[1], int(sys.argv[2]))
0054     running_counts = lines.flatMap(lambda line: line.split(" "))\
0055                           .map(lambda word: (word, 1))\
0056                           .updateStateByKey(updateFunc, initialRDD=initialStateRDD)
0057
0058     running_counts.pprint()
0059
0060     ssc.start()
0061     ssc.awaitTermination()