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From "Alex Hanna (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AVRO-1271) Hadoop Streaming mangles Python-produced Avro
Date Wed, 06 Mar 2013 16:48:13 GMT
Alex Hanna created AVRO-1271:
--------------------------------

             Summary: Hadoop Streaming mangles Python-produced Avro
                 Key: AVRO-1271
                 URL: https://issues.apache.org/jira/browse/AVRO-1271
             Project: Avro
          Issue Type: Bug
          Components: java, python
    Affects Versions: 1.7.4
         Environment: Linux
            Reporter: Alex Hanna


I've got a rather simple script that takes Twitter data in JSON and turns it into an Avro
file.

from avro import schema, datafile, io
import json, sys
from types import *

def main():
    if len(sys.argv) < 2:
        print "Usage: cat input.json | python2.7 JSONtoAvro.py output"
        return

    s = schema.parse(open("tweet.avsc").read())
    f = open(sys.argv[1], 'wb')

    writer = datafile.DataFileWriter(f, io.DatumWriter(), s, codec = 'deflate')

    failed = 0

    for line in sys.stdin:
        line = line.strip()

    try:
        data = json.loads(line)
    except ValueError as detail:
        continue

    try:
        writer.append(data)
    except io.AvroTypeException as detail:
        print line
        failed += 1

writer.close()

print str(failed) + " failed in schema"

if __name__ == '__main__':
    main()

>From there, I use this to feed a basic Hadoop Streaming script (also in Python) which
just pulls out certain elements of the tweets. However, when I do this, it appears that the
input for the script is mangled JSON. Usually the JSON fails with some errant \u in the middle
of the tweet body or user-defined description.

The Streaming script is rather basic -- it reads from sys.stdin and attempts to parse the
JSON string using the json package.

Here is the bash script I use to invoke Hadoop Streaming:

jars=/usr/lib/hadoop/lib/avro-1.7.1.cloudera.2.jar,/usr/lib/hive/lib/avro-mapred-1.7.1.cloudera.2.jar

hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar \
    -files $jars,$HOME/sandbox/hadoop/streaming/map/tweetMapper.py,$HOME/sandbox/hadoop/streaming/data/keywords.txt,$HOME/sandbox/hadoop/streaming/data/follow-r3.txt
\
     -libjars $jars \
     -input /user/ahanna/avrotest/avrotest.json.avro \
     -output output \
     -mapper "tweetMapper.py -a" \
     -reducer org.apache.hadoop.mapred.lib.IdentityReducer \
     -inputformat org.apache.avro.mapred.AvroAsTextInputFormat \
     -numReduceTasks 1

I'm starting to think this is a bug with org.apache.avro.mapred.AvroAsTextInputFormat?

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