如何在使用Python的hadoop流作业中使用文件？

我想从hadoop流作业中的文件中读取列表。这是我简单的mapper.py：

#!/usr/bin/env python

import sys
import json

def read_file():
    id_list = []
    #read ids from a file
    f = open('../user_ids','r')
    for line in f:
        line = line.strip()
        id_list.append(line)
    return id_list

if __name__ == '__main__':
    id_list = set(read_file())
    # input comes from STDIN (standard input)
    for line in sys.stdin:
        # remove leading and trailing whitespace
        line = line.strip()
        line = json.loads(line)
        user_id = line['user']['id']
        if str(user_id) in id_list:
            print '%s\t%s' % (user_id, line)

这是我的reducer.py

#!/usr/bin/env python

from operator import itemgetter
import sys

current_id = None
current_list = []
id = None

# input comes from STDIN
for line in sys.stdin:
    # remove leading and trailing whitespace
    line = line.strip()

    # parse the input we got from mapper.py
    id, line = line.split('\t', 1)

    # this IF-switch only works because Hadoop sorts map output
    # by key (here: word) before it is passed to the reducer
    if current_id == id:
        current_list.append(line)
    else:
        if current_id:
            # write result to STDOUT
            print '%s\t%s' % (current_id, current_list)
        current_id = id
        current_list = [line]

# do not forget to output the last word if needed!
if current_id == id:
        print '%s\t%s' % (current_id, current_list)

现在运行它，我说：

hadoop jar contrib/streaming/hadoop-streaming-1.1.1.jar -file ./mapper.py \
    -mapper ./mapper.py -file ./reducer.py -reducer ./reducer.py \
    -input test/input.txt  -output test/output -file '../user_ids' 

作业开始运行：

13/11/07 05:04:52 INFO streaming.StreamJob:  map 0%  reduce 0%
13/11/07 05:05:21 INFO streaming.StreamJob:  map 100%  reduce 100%
13/11/07 05:05:21 INFO streaming.StreamJob: To kill this job, run:

我得到错误：

job not successful. Error: # of failed Map Tasks exceeded allowed limit. FailedCount: 1.         LastFailedTask: task_201309172143_1390_m_000001
13/11/07 05:05:21 INFO streaming.StreamJob: killJob...

我不从文件../user_ids中读取ID时，不会出现任何错误。我认为问题是找不到我的../user_id文件。我也使用了hdfs中的位置，但仍然无法正常工作。谢谢你的帮助。