RHadoop:所需的REDUCE功能超过了群集中支持的最大容器功能

Question

在沙箱Hadoop(Cloudera5.1/Hortonworks2.1)的R(build 1060)中是否有类似的问题？这似乎是新R/Hadoop的问题,因为在CDH5.0上它可以工作.

码:

Sys.setenv(HADOOP_CMD="/usr/bin/hadoop")
Sys.setenv(HADOOP_STREAMING="/usr/lib/hadoop-mapreduce/hadoop-streaming.jar")
Sys.setenv(JAVA_HOME="/usr/java/jdk1.7.0_55-cloudera")
library(rhdfs)
library(rmr2)
hdfs.init()

## space and word delimiter
map <- function(k,lines) {
  words.list <- strsplit(lines, '\\s')
  words <- unlist(words.list)
  return( keyval(words, 1) )
}
reduce <- function(word, counts) {
  keyval(word, sum(counts))
}
wordcount <- function (input, output=NULL) {
  mapreduce(input=input, output=output, input.format="text", map=map, reduce=reduce)
}

## variables
hdfs.root <- '/user/cloudera'
hdfs.data <- file.path(hdfs.root, 'scenario_1')
hdfs.out <- file.path(hdfs.root, 'out')

## run mapreduce job
##out <- wordcount(hdfs.data, hdfs.out)
system.time(out <- wordcount(hdfs.data, hdfs.out))

错误:

> system.time(out <- wordcount(hdfs.data, hdfs.out))
packageJobJar: [] [/usr/lib/hadoop-mapreduce/hadoop-streaming-2.3.0-cdh5.1.0.jar] /tmp/streamjob8497498354509963133.jar tmpDir=null
14/09/17 01:49:38 INFO client.RMProxy: Connecting to ResourceManager at quickstart.cloudera/127.0.0.1:8032
14/09/17 01:49:38 INFO client.RMProxy: Connecting to ResourceManager at quickstart.cloudera/127.0.0.1:8032
14/09/17 01:49:39 INFO mapred.FileInputFormat: Total input paths to process : 1
14/09/17 01:49:39 INFO mapreduce.JobSubmitter: number of splits:2
14/09/17 01:49:39 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1410940439997_0001
14/09/17 01:49:40 INFO impl.YarnClientImpl: Submitted application application_1410940439997_0001
14/09/17 01:49:40 INFO mapreduce.Job: The url to track the job: http://quickstart.cloudera:8088/proxy/application_1410940439997_0001/
14/09/17 01:49:40 INFO mapreduce.Job: Running job: job_1410940439997_0001
14/09/17 01:49:54 INFO mapreduce.Job: Job job_1410940439997_0001 running in uber mode : false
14/09/17 01:49:54 INFO mapreduce.Job:  map 100% reduce 100%
14/09/17 01:49:55 INFO mapreduce.Job: Job job_1410940439997_0001 failed with state KILLED due to: MAP capability required is more than the supported max container capability in the cluster. Killing the Job. mapResourceReqt: 4096 maxContainerCapability:1024
Job received Kill while in RUNNING state.
REDUCE capability required is more than the supported max container capability in the cluster. Killing the Job. **reduceResourceReqt: 4096 maxContainerCapability:1024**

14/09/17 01:49:55 INFO mapreduce.Job: Counters: 2
    Job Counters 
        Total time spent by all maps in occupied slots (ms)=0
        Total time spent by all reduces in occupied slots (ms)=0
14/09/17 01:49:55 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
Timing stopped at: 3.681 0.695 20.43 

似乎问题出在reduceResourceReqt:4096 maxContainerCapability:1024.我试图改变:yarn-site.xml,但它没有帮助.:(

请帮忙...

Answer 1

我没有使用过RHadoop.但是我的群集上有一个非常类似的问题,这个问题似乎只与MapReduce有关.

此日志中的maxContainerCapability指的是配置的yarn.scheduler.maximum-allocation-mb属性yarn-site.xml.它是可以在任何容器中使用的最大内存量.

该mapResourceReqt和reduceResourceReqt在日志指的是mapreduce.map.memory.mb与mapreduce.reduce.memory.mb你的性能mapred-site.xml配置.它是将在mapreduce中为Mapper或Reducer创建的容器的内存大小.

如果您的Reducer容器的大小设置为大于yarn.scheduler.maximum-allocation-mb(这似乎是这种情况),您的作业将被终止,因为不允许为容器分配如此多的内存.

在http:// [your-resource-manager]:8088/conf检查您的配置,您通常应该找到这些值并看到这种情况.

也许你的新环境将这些值设置为4096 Mb(相当大,Hadoop 2.7.1中的默认值为1024).

解

您应该将mapreduce.[map|reduce].memory.mb值降低到1024,或者如果您有大量内存并且需要大容器,请将yarn.scheduler.maximum-allocation-mb值提高到4096.只有MapReduce才能创建容器.

我希望这有帮助.