python - 流命令失败!在CentOS7的单节点hadoop集群设置中执行MapReduce python代码时

Question

我已经在同一台计算机上成功执行了mapreduce java代码。现在，我正在尝试在同一台计算机上执行以python编写的Mapreduce代码。为此，我使用hadoop_3.2.1和hadoop-streaming-3.2.1.jar。

我已经通过命令测试了代码
[dsawale@localhost ~]$ cat Desktop/sample.txt | python PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py | sort | python PycharmProjects/MapReduceCode/com/code/wordcount/WordCountReducer.py
我发现它显示正确的输出。

但是当我尝试使用命令在hadoop集群上执行时
[dsawale@localhost ~]$ hadoop jar Desktop/JAR/hadoop-streaming-3.2.1.jar -mapper mapper.py -reducer reducer.py -file PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py -file PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py -input /sample.txt -output pysamp
我得到的输出为:

packageJobJar: [PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py, PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py, /tmp/hadoop-unjar6715579504628929924/] [] /tmp/streamjob3211585412475799030.jar tmpDir=null
Streaming Command Failed!

这是我的第一个python MapReduce程序。您能帮我摆脱这个错误吗？
谢谢!

配置文件:
mapred-site.xml

<configuration>
    <property>
        <name>mapreduce.framework.name</name>
        <value>yarn</value>
    </property>
    <property>
            <name>yarn.app.mapreduce.am.env</name>
            <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
    </property>
        <property>
            <name>mapreduce.map.env</name>
            <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
    </property>
        <property>
            <name>mapreduce.reduce.env</name>
            <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
    </property>
</configuration>

core-site.xml:

<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

hdfs-site.xml

<configuration>
    <property>
            <name>dfs.replication</name>
            <value>1</value>
    </property>
    <property>  
        <name>dfs.permission</name>
        <value>false</value>
    </property>
    <property>  
        <name>dfs.namenode.name.dir</name>
        <value>/home/dsawale/hadoop-3.2.1/hadoop2_data/hdfs/namenode</value>
    </property>
    <property>
        <name>dfs.datanode.data.dir</name>
        <value>/home/dsawale/hadoop-3.2.1/hadoop2_data/hdfs/datanode</value>
    </property>
</configuration>

yarn-site.xml:

    <configuration>
<!-- Site specific YARN configuration properties -->
    <property>
        <name>yarn.nodemanager.aux-services</name>
        <value>mapreduce_shuffle</value>
    </property>
    <property>
        <name>yarn.nodemanager.auxservices.mapreduce.shuffle.class</name>
        <value>org.apache.hadoop.mapred.ShuffleHandler</value>
    </property>
</configuration>

Answer 1

您传递给mapper和reducer参数的文件路径不正确。

尝试，

hadoop jar Desktop/JAR/hadoop-streaming-3.2.1.jar \
-mapper PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py \
-reducer PycharmProjects/MapReduceCode/com/code/wordcount/WordCountReducer.py  \
-file PycharmProjects/MapReduceCode/com/code/wordcount/WordCountMapper.py \
-file PycharmProjects/MapReduceCode/com/code/wordcount/WordCountReducer.py \
-input /sample.txt \
-output pysamp