三台机器 CentOS7（机器名分别为master-CentOS7、slave1-CentOS7、slave2-CentOS7），每台机器内存2G（迫于无奈，刚换了内存条）
之前写了一篇“CentOS 7 安装Hadoop 2.7.1”http://blog.csdn.net/noob_f/article/details/52356779
wordcount统计单词
master-CentOS7（已启动Hadoop集群）
[root@master ~]# cd /usr/local/hadoop/
[root@master hadoop]# bin/hdfs dfs -mkdir /test001
[root@master hadoop]# bin/hdfs dfs -ls /
Found 3 items
drwxr-xr-x - root supergroup 0 2016-09-01 19:41 /test001
drwx------ - root supergroup 0 2016-08-29 20:26 /tmp
drwxr-xr-x - root supergroup 0 2016-08-29 20:26 /user
[root@master hadoop]# ls
bin etc lib LICENSE.txt NOTICE.txt sbin tmp
dfs include libexec logs README.txt share
[root@master hadoop]# wc -l LICENSE.txt
289 LICENSE.txt
[root@master hadoop]# du -sh !$
du -sh LICENSE.txt
16K LICENSE.txt
[root@master hadoop]# bin/hdfs dfs -copyFromLocal ./LICENSE.txt /test001
[root@master hadoop]# bin/hdfs dfs -ls /test001
Found 1 items
-rw-r--r-- 2 root supergroup 15429 2016-09-01 19:46 /test001/LICENSE.txt
[root@master hadoop]# bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.1.jar wordcount /test001/LICENSE.txt /test001/
[root@master hadoop]# echo $?
255
发现命令执行出错：
org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://192.168.1.182:9000/test001 already exists命令改一下
[root@master hadoop]# bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.1.jar wordcount /test001/LICENSE.txt /test001/wordcount
16/09/02 17:09:35 INFO client.RMProxy: Connecting to ResourceManager at /192.168.1.182:8032
16/09/02 17:09:36 INFO input.FileInputFormat: Total input paths to process : 1
16/09/02 17:09:36 INFO mapreduce.JobSubmitter: number of splits:1
16/09/02 17:09:37 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1472804584592_0003
16/09/02 17:09:37 INFO impl.YarnClientImpl: Submitted application application_1472804584592_0003
16/09/02 17:09:37 INFO mapreduce.Job: The url to track the job: http://master:8088/proxy/application_1472804584592_0003/
16/09/02 17:09:37 INFO mapreduce.Job: Running job: job_1472804584592_0003
16/09/02 17:09:46 INFO mapreduce.Job: Job job_1472804584592_0003 running in uber mode : false
16/09/02 17:09:46 INFO mapreduce.Job: map 0% reduce 0%
16/09/02 17:09:55 INFO mapreduce.Job: map 100% reduce 0%
16/09/02 17:10:04 INFO mapreduce.Job: map 100% reduce 100%
16/09/02 17:10:05 INFO mapreduce.Job: Job job_1472804584592_0003 completed successfully
16/09/02 17:10:05 INFO mapreduce.Job: Counters: 49
File System Counters
FILE: Number of bytes read=10992
FILE: Number of bytes written=252973
FILE: Number of read operations=0
FILE: Number of large read operations=0
FILE: Number of write operations=0
HDFS: Number of bytes read=15539
HDFS: Number of bytes written=8006
HDFS: Number of read operations=6
HDFS: Number of large read operations=0
HDFS: Number of write operations=2
Job Counters
Launched map tasks=1
Launched reduce tasks=1
Data-local map tasks=1
Total time spent by all maps in occupied slots (ms)=6493
Total time spent by all reduces in occupied slots (ms)=6714
Total time spent by all map tasks (ms)=6493
Total time spent by all reduce tasks (ms)=6714
Total vcore-seconds taken by all map tasks=6493
Total vcore-seconds taken by all reduce tasks=6714
Total megabyte-seconds taken by all map tasks=6648832
Total megabyte-seconds taken by all reduce tasks=6875136
Map-Reduce Framework
Map input records=289
Map output records=2157
Map output bytes=22735
Map output materialized bytes=10992
Input split bytes=110
Combine input records=2157
Combine output records=755
Reduce input groups=755
Reduce shuffle bytes=10992
Reduce input records=755
Reduce output records=755
Spilled Records=1510
Shuffled Maps =1
Failed Shuffles=0
Merged Map outputs=1
GC time elapsed (ms)=146
CPU time spent (ms)=2360
Physical memory (bytes) snapshot=312647680
Virtual memory (bytes) snapshot=1717682176
Total committed heap usage (bytes)=163123200
Shuffle Errors
BAD_ID=0
CONNECTION=0
IO_ERROR=0
WRONG_LENGTH=0
WRONG_MAP=0
WRONG_REDUCE=0
File Input Format Counters
Bytes Read=15429
File Output Format Counters
Bytes Written=8006
[root@master hadoop]# echo $?
0
[root@master hadoop]# bin/hdfs dfs -ls /test001/
Found 2 items
-rw-r--r-- 2 root supergroup 15429 2016-09-01 19:46 /test001/LICENSE.txt
drwxr-xr-x - root supergroup 0 2016-09-02 17:10 /test001/wordcount
[root@master hadoop]# bin/hdfs dfs -ls /test001/wordcount
Found 2 items
-rw-r--r-- 2 root supergroup 0 2016-09-02 17:10 /test001/wordcount/_SUCCESS
-rw-r--r-- 2 root supergroup 8006 2016-09-02 17:10 /test001/wordcount/part-r-00000
[root@master hadoop]# bin/hdfs dfs -cat /test001/wordcount/part-r-00000
"AS 4
"Contribution" 1
"Contributor" 1
"Derivative 1
"Legal 1
"License" 1
"License"); 1
"Licensor" 1
"NOTICE" 1
"Not 1
"Object" 1
"Source" 1
"Work" 1
"You" 1
"Your") 1
"[]" 1
"control" 1
"printed 1
"submitted" 1
(50%) 1
(C) 1
(Don't 1
(INCLUDING 2
(INCLUDING, 2
(a) 1
(an 1
(and 1
(b) 1
(c) 2
(d) 1
(except 1
(http://www.one-lab.org) 1
(http://www.opensource.org/licenses/bsd-license.php) 1
(i) 1
(ii) 1
(iii) 1
(including 3
(or 3
(such 1
(the 1
* 34
*/ 3
- 7
/* 1
/** 2
034819 1
1 1
1. 1
2-Clause 1
2. 1
2.0 1
2.0, 1
2004 1
2005, 1
2008,2009,2010 1
2011-2014, 1
3. 1
4. 1
5. 1
6. 1
7. 1
8. 1
9 1
9. 1
: 3
A 3
ADVISED 2
AND 11
ANY 10
APACHE 1
APPENDIX: 1
ARE 2
ARISING 2
Accepting 1
Additional 1
All 2
Apache 5
Appendix 1
BASIS, 2
BE 2
BSD 1
BSD-style 1
BUSINESS 2
BUT 4
BY 2
CAUSED 2
CONDITIONS 4
CONSEQUENTIAL 2
CONTRACT, 2
CONTRIBUTORS 4
COPYRIGHT 4
CRC 1
Catholique 1
Collet. 1
Commission 1
Contribution 3
Contribution(s) 3
Contribution." 1
Contributions) 1
Contributions. 2
Contributor 8
Contributor, 1
Copyright 5
DAMAGE. 2
DAMAGES 2
DATA, 2
DIRECT, 2
DISCLAIMED. 2
DISTRIBUTION 1
Definitions. 1
Derivative 17
Disclaimer 1
END 1
EVEN 2
EVENT 2
EXEMPLARY, 2
EXPRESS 2
Entity 3
Entity" 1
European 1
FITNESS 3
FOR 6
Fast 1
File 1
For 6
GOODS 2
Grant 2
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IN 6
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LIABILITY, 4
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License 10
License, 6
License. 11
License; 1
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Licensor, 1
Limitation 1
Louvain 1
MERCHANTABILITY 2
MERCHANTABILITY, 1
Massachusetts 1
NEGLIGENCE 2
NO 2
NON-INFRINGEMENT, 1
NOT 4
NOTICE 5
Neither 1
Notwithstanding 1
OF 19
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OUT 2
OWNER 2
Object 4
OneLab 1
PARTICULAR 3
POSSIBILITY 2
PROCUREMENT 2
PROFITS; 2
PROVIDED 2
PURPOSE 2
PURPOSE. 1
Patent 1
REPRODUCTION, 1
Redistribution 2
Redistribution. 1
Redistributions 4
SERVICES; 2
SHALL 2
SOFTWARE 2
SOFTWARE, 2
SPECIAL, 2
STRICT 2
SUBCOMPONENTS: 1
SUBSTITUTE 2
SUCH 2
Sections 1
See 1
Source 8
Subject 2
Submission 1
TERMS 2
THE 10
THEORY 2
THIS 4
TITLE, 1
TO, 4
TORT 2
Technology. 1
The 3
This 1
To 1
Trademarks. 1
UCL 1
USE 2
USE, 3
University 1
Unless 3
Use 1
Version 2
WARRANTIES 4
WARRANTIES, 2
WAY 2
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WITHOUT 2
Warranty 1
Warranty. 1
We 1
While 1
Work 20
Work, 4
Work. 1
Works 12
Works" 1
Works, 2
Works; 3
Yann 1
You 24
Your 9
[name 1
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a 21
above 4
above, 1
acceptance 1
accepting 2
act 1
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addendum 1
additional 4
additions 1
advised 1
against 1
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agreement 1
algorithm 1
all 3
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and 51
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any 28
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conditions 14
conditions. 1
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consequential 1
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contents 1
contract 2
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copyright 15
copyright, 1
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damages 3
damages, 1
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date 1
de 1
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src/main/native/src/org/apache/hadoop/io/compress/lz4/{lz4.h,lz4.c,lz4hc.h,lz4hc.c}, 1
src/main/native/src/org/apache/hadoop/util: 1
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your 4
运行 PI 实例
master-CentOS7（已启动Hadoop集群）
[root@master ~]# cd /usr/local/hadoop/
[root@master hadoop]# bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.1.jar pi 100 100
Number of Maps = 100
Samples per Map = 100
Wrote input for Map #0
Wrote input for Map #1
Wrote input for Map #2
Wrote input for Map #3
Wrote input for Map #4
Wrote input for Map #5
Wrote input for Map #6
Wrote input for Map #7
Wrote input for Map #8
Wrote input for Map #9
Wrote input for Map #10
Wrote input for Map #11
Wrote input for Map #12
Wrote input for Map #13
Wrote input for Map #14
Wrote input for Map #15
Wrote input for Map #16
Wrote input for Map #17
Wrote input for Map #18
Wrote input for Map #19
Wrote input for Map #20
Wrote input for Map #21
Wrote input for Map #22
Wrote input for Map #23
Wrote input for Map #24
Wrote input for Map #25
Wrote input for Map #26
Wrote input for Map #27
Wrote input for Map #28
Wrote input for Map #29
Wrote input for Map #30
Wrote input for Map #31
Wrote input for Map #32
Wrote input for Map #33
Wrote input for Map #34
Wrote input for Map #35
Wrote input for Map #36
Wrote input for Map #37
Wrote input for Map #38
Wrote input for Map #39
Wrote input for Map #40
Wrote input for Map #41
Wrote input for Map #42
Wrote input for Map #43
Wrote input for Map #44
Wrote input for Map #45
Wrote input for Map #46
Wrote input for Map #47
Wrote input for Map #48
Wrote input for Map #49
Wrote input for Map #50
Wrote input for Map #51
Wrote input for Map #52
Wrote input for Map #53
Wrote input for Map #54
Wrote input for Map #55
Wrote input for Map #56
Wrote input for Map #57
Wrote input for Map #58
Wrote input for Map #59
Wrote input for Map #60
Wrote input for Map #61
Wrote input for Map #62
Wrote input for Map #63
Wrote input for Map #64
Wrote input for Map #65
Wrote input for Map #66
Wrote input for Map #67
Wrote input for Map #68
Wrote input for Map #69
Wrote input for Map #70
Wrote input for Map #71
Wrote input for Map #72
Wrote input for Map #73
Wrote input for Map #74
Wrote input for Map #75
Wrote input for Map #76
Wrote input for Map #77
Wrote input for Map #78
Wrote input for Map #79
Wrote input for Map #80
Wrote input for Map #81
Wrote input for Map #82
Wrote input for Map #83
Wrote input for Map #84
Wrote input for Map #85
Wrote input for Map #86
Wrote input for Map #87
Wrote input for Map #88
Wrote input for Map #89
Wrote input for Map #90
Wrote input for Map #91
Wrote input for Map #92
Wrote input for Map #93
Wrote input for Map #94
Wrote input for Map #95
Wrote input for Map #96
Wrote input for Map #97
Wrote input for Map #98
Wrote input for Map #99
Starting Job
16/09/02 16:40:43 INFO client.RMProxy: Connecting to ResourceManager at /192.168.1.182:8032
16/09/02 16:40:44 INFO input.FileInputFormat: Total input paths to process : 100
16/09/02 16:40:45 INFO mapreduce.JobSubmitter: number of splits:100
16/09/02 16:40:45 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1472804584592_0002
16/09/02 16:40:45 INFO impl.YarnClientImpl: Submitted application application_1472804584592_0002
16/09/02 16:40:46 INFO mapreduce.Job: The url to track the job: http://master:8088/proxy/application_1472804584592_0002/
16/09/02 16:40:46 INFO mapreduce.Job: Running job: job_1472804584592_0002
16/09/02 16:40:55 INFO mapreduce.Job: Job job_1472804584592_0002 running in uber mode : false
16/09/02 16:40:55 INFO mapreduce.Job: map 0% reduce 0%
16/09/02 16:41:16 INFO mapreduce.Job: map 2% reduce 0%
16/09/02 16:41:31 INFO mapreduce.Job: map 3% reduce 0%
16/09/02 16:41:32 INFO mapreduce.Job: map 4% reduce 0%
16/09/02 16:41:44 INFO mapreduce.Job: map 5% reduce 0%
16/09/02 16:41:46 INFO mapreduce.Job: map 6% reduce 0%
16/09/02 16:41:59 INFO mapreduce.Job: map 7% reduce 0%
16/09/02 16:42:00 INFO mapreduce.Job: map 8% reduce 0%
16/09/02 16:42:12 INFO mapreduce.Job: map 9% reduce 0%
16/09/02 16:42:13 INFO mapreduce.Job: map 10% reduce 0%
16/09/02 16:42:26 INFO mapreduce.Job: map 11% reduce 0%
16/09/02 16:42:27 INFO mapreduce.Job: map 12% reduce 0%
16/09/02 16:42:40 INFO mapreduce.Job: map 13% reduce 0%
16/09/02 16:42:41 INFO mapreduce.Job: map 14% reduce 0%
16/09/02 16:42:55 INFO mapreduce.Job: map 15% reduce 0%
16/09/02 16:42:56 INFO mapreduce.Job: map 16% reduce 0%
16/09/02 16:43:10 INFO mapreduce.Job: map 17% reduce 0%
16/09/02 16:43:11 INFO mapreduce.Job: map 18% reduce 0%
16/09/02 16:43:25 INFO mapreduce.Job: map 19% reduce 0%
16/09/02 16:43:26 INFO mapreduce.Job: map 20% reduce 0%
16/09/02 16:43:39 INFO mapreduce.Job: map 21% reduce 0%
16/09/02 16:43:40 INFO mapreduce.Job: map 22% reduce 0%
16/09/02 16:43:52 INFO mapreduce.Job: map 23% reduce 0%
16/09/02 16:43:53 INFO mapreduce.Job: map 24% reduce 0%
16/09/02 16:44:06 INFO mapreduce.Job: map 25% reduce 0%
16/09/02 16:44:07 INFO mapreduce.Job: map 26% reduce 0%
16/09/02 16:44:21 INFO mapreduce.Job: map 27% reduce 0%
16/09/02 16:44:23 INFO mapreduce.Job: map 28% reduce 0%
16/09/02 16:44:35 INFO mapreduce.Job: map 29% reduce 0%
16/09/02 16:44:36 INFO mapreduce.Job: map 30% reduce 0%
16/09/02 16:44:48 INFO mapreduce.Job: map 31% reduce 0%
16/09/02 16:44:49 INFO mapreduce.Job: map 32% reduce 0%
16/09/02 16:44:59 INFO mapreduce.Job: map 33% reduce 0%
16/09/02 16:45:00 INFO mapreduce.Job: map 34% reduce 0%
16/09/02 16:45:11 INFO mapreduce.Job: map 35% reduce 0%
16/09/02 16:45:12 INFO mapreduce.Job: map 36% reduce 0%
16/09/02 16:45:22 INFO mapreduce.Job: map 37% reduce 0%
16/09/02 16:45:24 INFO mapreduce.Job: map 38% reduce 0%
16/09/02 16:45:35 INFO mapreduce.Job: map 39% reduce 0%
16/09/02 16:45:36 INFO mapreduce.Job: map 40% reduce 0%
16/09/02 16:45:46 INFO mapreduce.Job: map 41% reduce 0%
16/09/02 16:45:48 INFO mapreduce.Job: map 42% reduce 0%
16/09/02 16:45:58 INFO mapreduce.Job: map 43% reduce 0%
16/09/02 16:46:00 INFO mapreduce.Job: map 44% reduce 0%
16/09/02 16:46:12 INFO mapreduce.Job: map 45% reduce 0%
16/09/02 16:46:13 INFO mapreduce.Job: map 46% reduce 0%
16/09/02 16:46:23 INFO mapreduce.Job: map 47% reduce 0%
16/09/02 16:46:24 INFO mapreduce.Job: map 48% reduce 0%
16/09/02 16:46:34 INFO mapreduce.Job: map 49% reduce 0%
16/09/02 16:46:35 INFO mapreduce.Job: map 50% reduce 0%
16/09/02 16:46:45 INFO mapreduce.Job: map 51% reduce 0%
16/09/02 16:46:46 INFO mapreduce.Job: map 52% reduce 0%
16/09/02 16:46:59 INFO mapreduce.Job: map 53% reduce 0%
16/09/02 16:47:03 INFO mapreduce.Job: map 53% reduce 18%
16/09/02 16:47:07 INFO mapreduce.Job: map 54% reduce 18%
16/09/02 16:47:14 INFO mapreduce.Job: map 55% reduce 18%
16/09/02 16:47:21 INFO mapreduce.Job: map 56% reduce 18%
16/09/02 16:47:25 INFO mapreduce.Job: map 56% reduce 19%
16/09/02 16:47:28 INFO mapreduce.Job: map 57% reduce 19%
16/09/02 16:47:35 INFO mapreduce.Job: map 58% reduce 19%
16/09/02 16:47:42 INFO mapreduce.Job: map 59% reduce 19%
16/09/02 16:47:43 INFO mapreduce.Job: map 59% reduce 20%
16/09/02 16:47:49 INFO mapreduce.Job: map 60% reduce 20%
16/09/02 16:47:57 INFO mapreduce.Job: map 61% reduce 20%
16/09/02 16:48:05 INFO mapreduce.Job: map 62% reduce 20%
16/09/02 16:48:08 INFO mapreduce.Job: map 62% reduce 21%
16/09/02 16:48:14 INFO mapreduce.Job: map 63% reduce 21%
16/09/02 16:48:22 INFO mapreduce.Job: map 64% reduce 21%
16/09/02 16:48:31 INFO mapreduce.Job: map 65% reduce 21%
16/09/02 16:48:32 INFO mapreduce.Job: map 65% reduce 22%
16/09/02 16:48:41 INFO mapreduce.Job: map 66% reduce 22%
16/09/02 16:48:49 INFO mapreduce.Job: map 67% reduce 22%
16/09/02 16:48:57 INFO mapreduce.Job: map 68% reduce 22%
16/09/02 16:49:00 INFO mapreduce.Job: map 68% reduce 23%
16/09/02 16:49:05 INFO mapreduce.Job: map 69% reduce 23%
16/09/02 16:49:12 INFO mapreduce.Job: map 70% reduce 23%
16/09/02 16:49:20 INFO mapreduce.Job: map 71% reduce 23%
16/09/02 16:49:22 INFO mapreduce.Job: map 71% reduce 24%
16/09/02 16:49:28 INFO mapreduce.Job: map 72% reduce 24%
16/09/02 16:49:36 INFO mapreduce.Job: map 73% reduce 24%
16/09/02 16:49:43 INFO mapreduce.Job: map 74% reduce 24%
16/09/02 16:49:46 INFO mapreduce.Job: map 74% reduce 25%
16/09/02 16:49:50 INFO mapreduce.Job: map 75% reduce 25%
16/09/02 16:49:58 INFO mapreduce.Job: map 76% reduce 25%
16/09/02 16:50:09 INFO mapreduce.Job: map 77% reduce 25%
16/09/02 16:50:11 INFO mapreduce.Job: map 77% reduce 26%
16/09/02 16:50:17 INFO mapreduce.Job: map 78% reduce 26%
16/09/02 16:50:25 INFO mapreduce.Job: map 79% reduce 26%
16/09/02 16:50:32 INFO mapreduce.Job: map 80% reduce 26%
16/09/02 16:50:35 INFO mapreduce.Job: map 80% reduce 27%
16/09/02 16:50:39 INFO mapreduce.Job: map 81% reduce 27%
16/09/02 16:50:47 INFO mapreduce.Job: map 82% reduce 27%
16/09/02 16:50:55 INFO mapreduce.Job: map 83% reduce 27%
16/09/02 16:50:56 INFO mapreduce.Job: map 83% reduce 28%
16/09/02 16:51:03 INFO mapreduce.Job: map 84% reduce 28%
16/09/02 16:51:10 INFO mapreduce.Job: map 85% reduce 28%
16/09/02 16:51:17 INFO mapreduce.Job: map 86% reduce 28%
16/09/02 16:51:20 INFO mapreduce.Job: map 86% reduce 29%
16/09/02 16:51:25 INFO mapreduce.Job: map 87% reduce 29%
16/09/02 16:51:34 INFO mapreduce.Job: map 88% reduce 29%
16/09/02 16:51:41 INFO mapreduce.Job: map 89% reduce 29%
16/09/02 16:51:44 INFO mapreduce.Job: map 89% reduce 30%
16/09/02 16:51:49 INFO mapreduce.Job: map 90% reduce 30%
16/09/02 16:51:56 INFO mapreduce.Job: map 91% reduce 30%
16/09/02 16:52:03 INFO mapreduce.Job: map 92% reduce 30%
16/09/02 16:52:06 INFO mapreduce.Job: map 92% reduce 31%
16/09/02 16:52:11 INFO mapreduce.Job: map 93% reduce 31%
16/09/02 16:52:18 INFO mapreduce.Job: map 94% reduce 31%
16/09/02 16:52:26 INFO mapreduce.Job: map 95% reduce 31%
16/09/02 16:52:27 INFO mapreduce.Job: map 95% reduce 32%
16/09/02 16:52:34 INFO mapreduce.Job: map 96% reduce 32%
16/09/02 16:52:41 INFO mapreduce.Job: map 97% reduce 32%
16/09/02 16:52:48 INFO mapreduce.Job: map 98% reduce 32%
16/09/02 16:52:52 INFO mapreduce.Job: map 98% reduce 33%
16/09/02 16:52:55 INFO mapreduce.Job: map 99% reduce 33%
16/09/02 16:53:02 INFO mapreduce.Job: map 100% reduce 33%
16/09/02 16:53:03 INFO mapreduce.Job: map 100% reduce 100%
16/09/02 16:53:04 INFO mapreduce.Job: Job job_1472804584592_0002 completed successfully
16/09/02 16:53:04 INFO mapreduce.Job: Counters: 49
File System Counters
FILE: Number of bytes read=2206
FILE: Number of bytes written=11703871
FILE: Number of read operations=0
FILE: Number of large read operations=0
FILE: Number of write operations=0
HDFS: Number of bytes read=26890
HDFS: Number of bytes written=215
HDFS: Number of read operations=403
HDFS: Number of large read operations=0
HDFS: Number of write operations=3
Job Counters
Launched map tasks=100
Launched reduce tasks=1
Data-local map tasks=100
Total time spent by all maps in occupied slots (ms)=921440
Total time spent by all reduces in occupied slots (ms)=376555
Total time spent by all map tasks (ms)=921440
Total time spent by all reduce tasks (ms)=376555
Total vcore-seconds taken by all map tasks=921440
Total vcore-seconds taken by all reduce tasks=376555
Total megabyte-seconds taken by all map tasks=943554560
Total megabyte-seconds taken by all reduce tasks=385592320
Map-Reduce Framework
Map input records=100
Map output records=200
Map output bytes=1800
Map output materialized bytes=2800
Input split bytes=15090
Combine input records=0
Combine output records=0
Reduce input groups=2
Reduce shuffle bytes=2800
Reduce input records=200
Reduce output records=0
Spilled Records=400
Shuffled Maps =100
Failed Shuffles=0
Merged Map outputs=100
GC time elapsed (ms)=12309
CPU time spent (ms)=75150
Physical memory (bytes) snapshot=20894449664
Virtual memory (bytes) snapshot=86424981504
Total committed heap usage (bytes)=13431619584
Shuffle Errors
BAD_ID=0
CONNECTION=0
IO_ERROR=0
WRONG_LENGTH=0
WRONG_MAP=0
WRONG_REDUCE=0
File Input Format Counters
Bytes Read=11800
File Output Format Counters
Bytes Written=97
Job Finished in 741.887 seconds
Estimated value of Pi is 3.14080000000000000000
如果提示 copyFromLocal: Cannot create directory /123/. Name node is in safe mode.
这是因为开启了安全模式（先关闭再启动Hadoop集群时，也会导致安全模式，此时不妨试试关闭安全模式）- 解决方法：
cd /usr/local/hadoop
bin/hdfs dfsadmin -safemode leave
- 解决方法：