运行hadoop2 自带的圆周率计算方法时，报错，找了半天，原来是在配置hadoop临时目录时，没有给权限，找到配置的hadoop临时目录文件夹，修改权限即可
Application application_1548242073562_0005 failed 2 times due to AM Container for appattempt_1548242073562_0005_000002 exited with exitCode: 1 Failing this attempt.Diagnostics: [2019-01-23 20:50:53.319]Exception from container-launch. Container id: container_1548242073562_0005_02_000001 Exit code: 1 [2019-01-23 20:50:53.321]Container exited with a non-zero exit code 1. Error file: prelaunch.err. Last 4096 bytes of prelaunch.err : Last 4096 bytes of stderr : log4j:WARN No appenders could be found for logger (org.apache.hadoop.mapreduce.v2.app.MRAppMaster). log4j:WARN Please initialize the log4j system properly.