我刚刚开始集成RHadoop。它是与Hadoop集成的R-studio服务器，但我在运行map reduce作业时出错。当我运行以下代码行时。
library(rmr2)
a <- to.dfs(seq(from=1, to=500, by=3), output="/user/hduser/num")
*b <- mapreduce(input=a, map=function(k,v){keyval(v,v*v)})*
StackTrace:
15/03/24 21:13:47 INFO Configuration.deprecation: mapred.reduce.tasks is deprecated. Instead, use mapreduce.job.reduces
packageJobJar: [] [/usr/lib/hadoop-mapreduce/hadoop-streaming-2.5.0-cdh5.2.0.jar] /tmp/streamjob4788227373090541042.jar tmpDir=null
15/03/24 21:13:48 INFO client.RMProxy: Connecting to ResourceManager at tungsten10/192.168.0.123:8032
15/03/24 21:13:48 INFO client.RMProxy: Connecting to ResourceManager at tungsten10/192.168.0.123:8032
15/03/24 21:13:49 INFO mapred.FileInputFormat: Total input paths to process : 1
15/03/24 21:13:50 INFO mapreduce.JobSubmitter: number of splits:2
15/03/24 21:13:50 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1427104115974_0009
15/03/24 21:13:50 INFO impl.YarnClientImpl: Submitted application application_1427104115974_0009
15/03/24 21:13:50 INFO mapreduce.Job: The url to track the job: http://XXX.XXX.XXX.XXX:8088/proxy/application_1427104115974_0009/
15/03/24 21:13:50 INFO mapreduce.Job: Running job: job_1427104115974_0009
15/03/24 21:14:02 INFO mapreduce.Job: Job job_1427104115974_0009 running in uber mode : false
15/03/24 21:14:03 INFO mapreduce.Job: map 0% reduce 0%
15/03/24 21:14:07 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000000_0, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:08 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000001_0, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:15 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000001_1, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:16 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000000_1, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:20 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000001_2, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:21 INFO mapreduce.Job: Task Id : attempt_1427104115974_0009_m_000000_2, Status : FAILED
Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:320)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:533)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
15/03/24 21:14:25 INFO mapreduce.Job: map 100% reduce 0%
15/03/24 21:14:26 INFO mapreduce.Job: Job job_1427104115974_0009 failed with state FAILED due to: Task failed task_1427104115974_0009_m_000001
Job failed as tasks failed. failedMaps:1 failedReduces:0
15/03/24 21:14:26 INFO mapreduce.Job: Counters: 13
Job Counters
Failed map tasks=7
Killed map tasks=1
Launched map tasks=8
Other local map tasks=6
Data-local map tasks=2
Total time spent by all maps in occupied slots (ms)=27095
Total time spent by all reduces in occupied slots (ms)=0
Total time spent by all map tasks (ms)=27095
Total vcore-seconds taken by all map tasks=27095
Total megabyte-seconds taken by all map tasks=27745280
Map-Reduce Framework
CPU time spent (ms)=0
Physical memory (bytes) snapshot=0
Virtual memory (bytes) snapshot=0
15/03/24 21:14:26 ERROR streaming.StreamJob: Job not Successful!
Streaming Command Failed!
**Error in mr(map = map, reduce = reduce, combine = combine, vectorized.reduce, :
hadoop streaming failed with error code 1
15/03/24 21:14:30 INFO fs.TrashPolicyDefault: Namenode trash configuration: Deletion interval = 1440 minutes, Emptier interval = 0 minutes.
Moved: 'hdfs://XXX.XXX.XXX.XXX:8020/tmp/file10076f272b9a' to trash at: hdfs://XXX.XXX.XXX.XXX:8020/user/hduser/.Trash/Current**
我找了很多方法来解决这个问题，但还没有找到解决办法。由于我是RHadoop的新手，我遇到了这个问题。可以，任何人请帮助我解决这个问题，我将非常感谢。
错误是由于代码中未设置HADOOP_STREAMING环境变量所致。您应该指定完整的路径和jar文件名。下面的R代码似乎对我来说很好。
R代码（我在Ubuntu上使用hadoop2.4.0）
Sys.setenv("HADOOP_CMD"="/usr/local/hadoop/bin/hadoop")
Sys.setenv("HADOOP_STREAMING"="/usr/local/hadoop/share/hadoop/tools/lib/hadoop-streaming-2.4.0.jar")
library(rJava)
library(rhdfs)
# Initialise
hdfs.init()
library(rmr2)
a <- to.dfs(seq(from=1, to=500, by=3), output="/user/hduser/num")
b <- mapreduce(input=a, map=function(k,v){keyval(v,v*v)})
希望这能有所帮助。