运行hadoop中的实例wordcount及问题

1.准备数据

wc.txt wc2.txt

2.在hdfs中创建/wordcount/input文件夹

hdfs dfs -mkdir -p /wordcount/input

3.上传到hdfs文件系统中

hdfs dfs -put wc.txt wc2.txt /wordcount/input

4.进入apps/hadoop-2.6.4/share/hadoop/mapreduce目录

cd apps/hadoop-2.6.4/share/hadoop/mapreduce

5.运行实例wordcount

hadoop jar hadoop-mapreduce-examples-2.6.4.jar wordcount /wordcount/input /wordcount/output

注意：

运行wordcount实例代码时，显示

INFO ipc.Client: Retrying connect to server: node01/192.168.30.134:8032. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)会重新连接服务器10次

原因：

没有启动yarn或者启动失败

解决：

启动yarn

start-yarn.sh