【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 
Hadoop运行mapreduce实例时,抛出错误 All datanodes xxx.xxx.xxx.xxx:xxx are bad. Aborting…
java.io.IOException: All datanodes xxx.xxx.xxx.xxx:xxx are bad. Aborting…
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.processDatanodeError(DFSClient.java:2158)
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.access$1400(DFSClient.java:1735)
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:1889)
java.io.IOException: Could not get block locations. Aborting…
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.processDatanodeError(DFSClient.java:2143)
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.access$1400(DFSClient.java:1735)
at org.apache.hadoop.dfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:1889)
经查明，问题原因是linux机器打开了过多的文件导致。
用命令ulimit -n可以发现linux默认的文件打开数目为1024
修改/ect/security/limit.conf，增加hadoop soft 65535
再重新运行程序（最好所有的datanode都修改），问题解决
来源：oschina
链接：https://my.oschina.net/u/4101357/blog/3151121