hadoop 流作业在 python 中失败

Question

我正在尝试在 hadoop 中实现一个算法。 我尝试在 hadoop 中执行部分代码，但流作业失败

$ /home/hadoop/hadoop/bin/hadoop jar contrib/streaming/hadoop-*-streaming.jar -file /home/hadoop/hadoop/PR/mapper.py -mapper mapper.py -file /home/hadoop/hadoop/PR/reducer.py -reducer reducer.py -input pagerank/* -output PRoutput6

packageJobJar: [/home/hadoop/hadoop/PR/mapper.py, /home/hadoop/hadoop/PR/reducer.py, /home/hadoop/hadoop/tmp/dir/hadoop-hadoop/hadoop-unjar7101759175212283428/] [] /tmp/streamjob6286075675343269479.jar tmpDir=null

11/04/23 01:03:24 INFO mapred.FileInputFormat: Total input paths to process : 1

11/04/23 01:03:24 INFO streaming.StreamJob: getLocalDirs(): [/home/hadoop/hadoop/tmp/dir/hadoop-hadoop/mapred/local]

11/04/23 01:03:24 INFO streaming.StreamJob: Running job: job_201104222325_0021

11/04/23 01:03:24 INFO streaming.StreamJob: To kill this job, run:

11/04/23 01:03:24 INFO streaming.StreamJob: /home/hadoop/hadoop/bin/../bin/hadoop job  -Dmapred.job.tracker=localhost:54311 -kill job_201104222325_0021

11/04/23 01:03:24 INFO streaming.StreamJob: Tracking URL: http://localhost:50030/jobdetails.jsp?jobid=job_201104222325_0021

11/04/23 01:03:25 INFO streaming.StreamJob:  map 0%  reduce 0%

11/04/23 01:03:31 INFO streaming.StreamJob:  map 50%  reduce 0%

11/04/23 01:03:41 INFO streaming.StreamJob:  map 50%  reduce 17%

11/04/23 01:03:56 INFO streaming.StreamJob:  map 100%  reduce 100%

11/04/23 01:03:56 INFO streaming.StreamJob: To kill this job, run:

11/04/23 01:03:56 INFO streaming.StreamJob: /home/hadoop/hadoop/bin/../bin/hadoop job  -Dmapred.job.tracker=localhost:54311 -kill job_201104222325_0021

11/04/23 01:03:56 INFO streaming.StreamJob: Tracking URL: http://localhost:50030/jobdetails.jsp?jobid=job_201104222325_0021

11/04/23 01:03:56 ERROR streaming.StreamJob: Job not Successful!

11/04/23 01:03:56 INFO streaming.StreamJob: killJob...

Streaming Job Failed!

ma​​pper.py

#!/usr/bin/env python
import sys
import itertools

def ipsum(input_key,input_value_list):
   return sum(input_value_list)

n= 20 # works up to about 1000000 pages
i = {}
for j in xrange(n): i[j] = [1.0/n,0,[]]
j=0
u=0
for line in sys.stdin:
  if j<n:
    i[j][1]=int(line)
  j=j+1

  if j > n: 
    if line != "-1\n":
      i[u][2] = line.split(',')
    else: 
      i[u][2]=[]
    u=u+1
for j in xrange(n):
  if i[j][1] != 0:
    i[j][2] = map(int,i[j][2])    

intermediate=[]
for (input_key,input_value) in i.items():
  if input_value[1] == 0: intermediate.extend([(1,input_value[0])])
  else: intermediate.extend([])
grp = {}
for key, group in itertools.groupby(sorted(intermediate),lambda x: x[0]):
  grp[key] = list([y for x, y in group])
iplist = [ipsum(intermediate_key,grp[intermediate_key]) for intermediate_key in grp]
inter=[]
for (input_key,input_value) in i.items():
  if input_value[1] == 0: inter.extend([(input_key,0.0)]+[(outlink,input_value[0]/input_value[1]) for outlink in input_value[2]])
  else: inter.extend([])

for value in inter:
  value1 = value[0]
  value2 = value[1]
  print '%s %s' % (value1,value2)

reducer.py

#!/usr/bin/env python
import sys
import itertools
for line in sys.stdin:
  input_key, input_value=line.split(' ',1)
  input_key = input_key.strip()
  input_value = input_value.strip()
  input_key = int(input_key)
  input_value = float(input_value)
  print str(input_key)+' '+str(input_value)

我不知道错误是在我的代码中还是在 hadoop 配置中......因为我能够使用执行代码， $ cat /home/hadoop/hadoop/PR/pagerank/input.txt | $ cat /home/hadoop/hadoop/PR/pagerank/input.txt | python /home/hadoop/hadoop/PR/mapper.py |排序| python /home/hadoop/hadoop/PR/reducer.py

将不胜感激任何帮助， 谢谢。

Answer 1

我的猜测是你的数据可能是关键。从字符串或类似问题中转换浮点数可能会在本地测试数据中未出现的实际数据中遇到麻烦。也许您可以通过异常处理或断言来解决。

Answer 2

查看输出中的职位信息页面 URL。就你而言，
localhost:50030/jobdetails.jsp?jobid=job_201104222325_0021

单击“失败的映射器”列中的数字和“最后 8KB”（或其他）日志链接，您将看到（最有可能的）您遇到的 python 异常。