error=11, Resource temporarily unavailable

问题1：Cannot run program "/bin/ls": error=11, Resource temporarily unavailable

 1 15/04/22 14:46:46 INFO mapred.JobClient: Task Id : attempt_201504221017_0006_r_000077_0, Status : FAILED
 2 java.lang.RuntimeException: Error while running command to get file permissions : java.io.IOException: Cannot run program "/bin/ls": error=11, Resource temporarily unavailable
 3         at java.lang.ProcessBuilder.start(ProcessBuilder.java:1047)
 4         at org.apache.hadoop.util.Shell.runCommand(Shell.java:200)
 5         at org.apache.hadoop.util.Shell.run(Shell.java:182)
 6         at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:375)
 7         at org.apache.hadoop.util.Shell.execCommand(Shell.java:461)
 8         at org.apache.hadoop.util.Shell.execCommand(Shell.java:444)
 9         at org.apache.hadoop.fs.FileUtil.execCommand(FileUtil.java:712)
10         at org.apache.hadoop.fs.RawLocalFileSystem$RawLocalFileStatus.loadPermissionInfo(RawLocalFileSystem.java:448)
11         at org.apache.hadoop.fs.RawLocalFileSystem$RawLocalFileStatus.getOwner(RawLocalFileSystem.java:431)
12 at org.apache.hadoop.mapred.TaskLog.obtainLogDirOwner(TaskLog.java:267)
13         at org.apache.hadoop.mapred.TaskLogsTruncater.truncateLogs(TaskLogsTruncater.java:124)
14         at org.apache.hadoop.mapred.Child$4.run(Child.java:260)
15         at java.security.AccessController.doPrivileged(Native Method)
16         at javax.security.auth.Subject.doAs(Subject.java:415)
17         at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1190)
18         at org.apache.hadoop.mapred.Child.main(Child.java:249)
19 Caused by: java.io.IOException: error=11, Resource temporarily unavailable
20         at java.lang.UNIXProcess.forkAndExec(Native Method)
21         at java.lang.UNIXProcess.<init>(UNIXProcess.java:186)
22         at java.lang.ProcessImpl.start(ProcessImpl.java:130)
23         at java.lang.ProcessBuilder.start(ProcessBuilder.java:1028)
24         ... 15 more

　　该问题很可能是因为当前提交Hadoop作业的用户能够打开的文件个数限制(主要是slave结点)，可以使用ulimit -n查看当前用户能够打开的文件个数。

　　参考：http://mail-archives.apache.org/mod_mbox/nutch-user/201312.mbox/%3C1386546180.6104.5.camel@senf.fritz.box%3E

问题2：java.lang.OutOfMemoryError: unable to create new native thread

1 15/04/22 11:08:16 WARN hdfs.DFSClient: DataStreamer Exception: java.lang.OutOfMemoryError: unable to create new native thread
2         at java.lang.Thread.start0(Native Method)
3         at java.lang.Thread.start(Thread.java:714)
4         at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:3030)

　　该问题并不一定是内存不够了，很可能是当前提交Hadoop作业的用户能够创建的进程个数限制(主要是slave结点)，可以使用ulimit -u查看当前用户能够创建的文件个数。

　　参考：http://www.nosql.se/2011/10/hadoop-tasktracker-java-lang-outofmemoryerror/

　　如何修改当前用户能够创建的进程个数：

　　在CentOS中，在vim /etc/security/limits.d/90-nproc.conf文件末尾添加如下语句：

1 *    soft    nproc     102400
2 *    hard    nproc     102400

　　修改完成后需要使用该用户重新登录。(如果使用Xshell这种远程软件，需要关闭该主机远程连接的标签卡，然后重新登录即可)