python - hadoop流作业在python中失败

Question

我试图在Hadoop中实现一个算法。
我试图在hadoop中执行部分代码，但是流作业失败

$ /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!

mapper.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...因为我能够使用以下代码执行代码，
$ 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，
谢谢。

Answer 1

我的猜测是您的数据可能是关键。从字符串或类似问题中强制转换浮点数可能会导致真实数据中出现泡沫，而这些泡沫不会出现在本地测试数据中。也许您可以使用异常处理或断言来解决。