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我正在尝试使用 Python 处理 Hadoop 流。我通过从这里获得帮助编写了简单的 map 和 reduce 脚本

map脚本如下：

#!/usr/bin/env python

import sys, urllib, re

title_re = re.compile("<title>(.*?)</title>", re.MULTILINE | re.DOTALL | re.IGNORECASE)

for line in sys.stdin:
    url = line.strip()
    match = title_re.search(urllib.urlopen(url).read())
    if match :
        print url, "\t", match.group(1).strip()

脚本reduce如下：

#!/usr/bin/env python

from operator import itemgetter
import sys

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

使用 hadoop 流 jar 运行这些脚本后，map任务完成，我可以看到它们 100% 完成，但reduce工作卡在 22%，并且在很长一段时间后它给出了ERROR streaming.StreamJob: Job not successful. Error: # of failed Map Tasks exceeded allowed limit. FailedCount: 1.错误。

我无法找出这背后的确切原因。

我的终端窗口如下所示：

shekhar@ubuntu:/host/Shekhar/Softwares/hadoop-1.0.0$ hadoop jar contrib/streaming/hadoop-streaming-1.0.0.jar -mapper /host/Shekhar/HadoopWorld/MultiFetch.py -reducer /host/Shekhar/HadoopWorld/reducer.py -input /host/Shekhar/HadoopWorld/urls/* -output /host/Shekhar/HadoopWorld/titles3
Warning: $HADOOP_HOME is deprecated.

packageJobJar: [/tmp/hadoop-shekhar/hadoop-unjar2709939812732871143/] [] /tmp/streamjob1176812134999992997.jar tmpDir=null
12/05/27 11:27:46 INFO util.NativeCodeLoader: Loaded the native-hadoop library
12/05/27 11:27:46 INFO mapred.FileInputFormat: Total input paths to process : 3
12/05/27 11:27:46 INFO streaming.StreamJob: getLocalDirs(): [/tmp/hadoop-shekhar/mapred/local]
12/05/27 11:27:46 INFO streaming.StreamJob: Running job: job_201205271050_0006
12/05/27 11:27:46 INFO streaming.StreamJob: To kill this job, run:
12/05/27 11:27:46 INFO streaming.StreamJob: /host/Shekhar/Softwares/hadoop-1.0.0/libexec/../bin/hadoop job  -Dmapred.job.tracker=localhost:9001 -kill job_201205271050_0006
12/05/27 11:27:46 INFO streaming.StreamJob: Tracking URL: http://localhost:50030/jobdetails.jsp?jobid=job_201205271050_0006
12/05/27 11:27:47 INFO streaming.StreamJob:  map 0%  reduce 0%
12/05/27 11:28:07 INFO streaming.StreamJob:  map 67%  reduce 0%
12/05/27 11:28:37 INFO streaming.StreamJob:  map 100%  reduce 0%
12/05/27 11:28:40 INFO streaming.StreamJob:  map 100%  reduce 11%
12/05/27 11:28:49 INFO streaming.StreamJob:  map 100%  reduce 22%
12/05/27 11:31:35 INFO streaming.StreamJob:  map 67%  reduce 22%
12/05/27 11:31:44 INFO streaming.StreamJob:  map 100%  reduce 22%
12/05/27 11:34:52 INFO streaming.StreamJob:  map 67%  reduce 22%
12/05/27 11:35:01 INFO streaming.StreamJob:  map 100%  reduce 22%
12/05/27 11:38:11 INFO streaming.StreamJob:  map 67%  reduce 22%
12/05/27 11:38:20 INFO streaming.StreamJob:  map 100%  reduce 22%
12/05/27 11:41:29 INFO streaming.StreamJob:  map 67%  reduce 22%
12/05/27 11:41:35 INFO streaming.StreamJob:  map 100%  reduce 100%
12/05/27 11:41:35 INFO streaming.StreamJob: To kill this job, run:
12/05/27 11:41:35 INFO streaming.StreamJob: /host/Shekhar/Softwares/hadoop-1.0.0/libexec/../bin/hadoop job  -Dmapred.job.tracker=localhost:9001 -kill job_201205271050_0006
12/05/27 11:41:35 INFO streaming.StreamJob: Tracking URL: http://localhost:50030/jobdetails.jsp?jobid=job_201205271050_0006
12/05/27 11:41:35 ERROR streaming.StreamJob: Job not successful. Error: # of failed Map Tasks exceeded allowed limit. FailedCount: 1. LastFailedTask: task_201205271050_0006_m_000001
12/05/27 11:41:35 INFO streaming.StreamJob: killJob...
Streaming Job Failed!

谁能帮帮我吗？？

编辑 作业跟踪器详细信息如下：

Hadoop job_201205271050_0006 on localhost

User: shekhar
Job Name: streamjob1176812134999992997.jar
Job File: file:/tmp/hadoop-shekhar/mapred/staging/shekhar/.staging/job_201205271050_0006/job.xml
Submit Host: ubuntu
Submit Host Address: 127.0.1.1
Job-ACLs: All users are allowed
Job Setup: Successful
Status: Failed
Failure Info:# of failed Map Tasks exceeded allowed limit. FailedCount: 1. LastFailedTask: task_201205271050_0006_m_000001
Started at: Sun May 27 11:27:46 IST 2012
Failed at: Sun May 27 11:41:35 IST 2012
Failed in: 13mins, 48sec
Job Cleanup: Successful
Black-listed TaskTrackers: 1
Kind    % Complete  Num Tasks   Pending Running Complete    Killed  Failed/Killed
Task Attempts
map 100.00%
3   0   0   2   1   4 / 0
reduce  100.00%
1   0   0   0   1   0 / 1
4

4 回答 4

3

此错误只是一般错误，太多 Map 任务未能完成：

失败的地图任务超过了允许的限制

您可以使用 EMR 控制台导航到各个 Map / Reduce 任务的日志。然后您应该能够看到问题所在。

就我而言 - 当我犯了一些小错误时出现了这个错误，比如错误地设置了 Map 脚本的路径。

查看任务日志的步骤：

http://antipatterns.blogspot.nl/2013/03/amazon-emr-map-reduce-error-of-failed.html

于 2013-03-31T00:33:14.967 回答
2

I just had the same error show up. In my case it turned out to be a parsing error. There was an "unexpected" new line at places which the stdin split the line at. I would suggest checking your data file. Once I removed the column which had these new lines it worked fine.

于 2012-06-25T22:08:51.607 回答
0

首先检查您的标准错误。您的信息不足以确定它是什么错误，stderr 通常位于：{your hadoop temp dir here}/mapred/local/userlogs/{your job id}/{your attemp id}/stderr

Sean 的回答是您第一次使用 hadoop 时最常见的情况，所以我猜您可能会收到 'env: python\r: No such file or directory' 错误。如果是这样，只需将您的 CR 替换为 LF 即可解决此问题。只需运行脚本将 \r 替换为 \n

于 2014-02-23T09:34:28.447 回答
0

在 Mapper 和 Reducer 的开头添加以下行： 

#!/usr/bin/python
于 2017-07-11T21:34:24.310 回答