错误一：本地运行Java 代码时出出现：
2018-09-14 19:45:07,266 DEBUG org.apache.hadoop.util.Shell.checkHadoopHome() - Failed to detect a valid hadoop home directory
java.io.IOException: HADOOP_HOME or hadoop.home.dir are not set.
2018-09-14 19:45:07,275 ERROR org.apache.hadoop.util.Shell.getWinUtilsPath() - Failed to locate the winutils binary in the hadoop binary path
java.io.IOException: Could not locate executable null\bin\winutils.exe in the Hadoop binaries.
解决：把hadoop安装目录下的hadoop.dll考到system32目录下
错误二：运行mapreduce
Job job_1536830416611_0021 failed with state FAILED due to: Application application_1536830416611_0021 failed 2 times due to Error launching appattempt_1536830416611_0021_000002. Got exception: org.apache.hadoop.yarn.exceptions.YarnException: Unauthorized request to start container.
This token is expired. current time is 1536878358609 found 1536837804741
Note: System times on machines may be out of sync. Check system time and time zones.
没有同步时间
解决：
在namenode 和datanode所在的服务器上都输入：
cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
ntpdate pool.ntp.org 进行时间同步
如果在ntpdate pool.ntp.org 时 出现 the NTP socket is in use, exiting
用 ps -ef|grep ntp 查出进程后 杀死
错误三：
启动zookeeper 服务时
zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper-3.4.10/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.
删除 /etc/hosts 中的 127.0.0.0拿一行
错误四：
linux的shell脚本运行出现失败
shell 脚本在/usr/local/bin 下 不管在哪执行都可以不用写路径
-bash: /usr/local/bin/xcall.sh: /bin/bash^M: bad interpreter:
在行末模式下输入set ff回车，查看当前的模式，如果时doc就通过set fileformat=unix修改成unix
错误五：
Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)
18/09/19 19:41:53 INFO ipc.Client: Retrying connect to server: hadoop03/192.168.136.130:8485. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)(所有journalnode都得开启，才能format namenode)
错误六：
2018-09-19 20:22:04,275 FATAL org.apache.hadoop.ha.ZKFailoverController: Unable to start failover controller. Parent znode does not exist.
Run with -formatZK flag to initialize ZooKeeper.
（要保证所有设置的zookeper集群的zookeeper服务都开启 才能 格式化 ）
