hadoop配置（5） --启动YARN

新版的 Hadoop 使用了新的 MapReduce 框架（MapReduce V2，也称为 YARN，Yet Another Resource Negotiator）。

YARN 是从 MapReduce 中分离出来的，负责资源管理与任务调度。YARN 运行于 MapReduce 之上，提供了高可用性、高扩展性。

上述通过 ./sbin/start-dfs.sh 启动 Hadoop，仅仅是启动了 MapReduce 环境，我们可以启动 YARN ，让 YARN 来负责资源管理与任务调度。

配置 mapr-site.xml文件 

mv ./etc/hadoop/mapred-site.xml.template ./etc/hadoop/mapred-site.xml

<configuration>
        <property>
             <name>mapreduce.framework.name</name>
             <value>yarn</value>
        </property>
</configuration>

修改配置文件 yarn-site.xml：

<configuration>
        <property>
             <name>yarn.nodemanager.aux-services</name>
             <value>mapreduce_shuffle</value>
            </property>
</configuration>

启动yarn(需要先执行过 ./sbin/start-dfs.sh)

./sbin/start-yarn.sh

检查：

启动 YARN 之后，运行实例的方法还是一样的，仅仅是资源管理方式、任务调度不同。

观察日志信息可以发现，不启用 YARN 时，是 “mapred.LocalJobRunner” 在跑任务，启用 YARN 之后，是 “mapred.YARNRunner” 在跑任务。启动 YARN 有个好处是可以通过 Web 界面查看任务的运行情况：http://localhost:8088/cluster

hadoop@Athena:/usr/local/hadoop$ ./sbin/start-dfs.sh 

16/06/22 20:28:42 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

Starting namenodes on [localhost]

localhost: starting namenode, logging to /usr/local/hadoop/logs/hadoop-hadoop-namenode-Athena.out

localhost: starting datanode, logging to /usr/local/hadoop/logs/hadoop-hadoop-datanode-Athena.out

Starting secondary namenodes [0.0.0.0]

0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/logs/hadoop-hadoop-secondarynamenode-Athena.out

16/06/22 20:29:05 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

hadoop@Athena:/usr/local/hadoop$ ./sbin/start-yarn..sh 

-su: ./sbin/start-yarn..sh: No such file or directory

hadoop@Athena:/usr/local/hadoop$ ./sbin/start-yarn. 

start-yarn.cmd  start-yarn.sh   

hadoop@Athena:/usr/local/hadoop$ ./sbin/start-yarn.sh 

starting yarn daemons

starting resourcemanager, logging to /usr/local/hadoop/logs/yarn-hadoop-resourcemanager-Athena.out

localhost: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-hadoop-nodemanager-Athena.out

hadoop@Athena:/usr/local/hadoop$ jps

16896 DataNode

17395 NodeManager

17109 SecondaryNameNode

16774 NameNode

17271 ResourceManager

17432 Jps

hadoop@Athena:/usr/local/hadoop$ ./bin/hdfs dfs -rm -r output

16/06/22 20:29:46 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

16/06/22 20:29:47 INFO fs.TrashPolicyDefault: Namenode trash configuration: Deletion interval = 0 minutes, Emptier interval = 0 minutes.

Deleted output

hadoop@Athena:/usr/local/hadoop$ ./bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount input/core-site.xml output/RESULT

hadoop fs -lsr /查看所有文件和子目录，

hadoop fs -put example.txt.

注意上面的这个命令最后一个参数是句点(.)。这意味着我们把文件放入了默认的工作目录。该命令等价于:

hadoop fs -put example.txt /user/chuck

来自为知笔记(Wiz)