在Centos 6.4 X64， JDK 1.7 U21下用hadoop 1.2.1 运行 mahout 0.9，处理一个5GB的数据，系统提示There is insufficient memory for the Java Runtime Environment to continue.
14/07/15 08:46:05 INFO mapred.JobClient: Task Id : attempt_201407141818_0002_m_000018_0, Status : FAILED
java.lang.Throwable: Child Error
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:271)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:258)
attempt_201407141818_0002_m_000018_0: #
attempt_201407141818_0002_m_000018_0: # There is insufficient memory for the Java Runtime Environment to continue.
attempt_201407141818_0002_m_000018_0: # Cannot create GC thread. Out of system resources.
attempt_201407141818_0002_m_000018_0: # An error report file with more information is saved as:
attempt_201407141818_0002_m_000018_0: # /home/hadoop/hd_space/mapred/local/taskTracker/hadoop/jobcache/job_201407141818_0002/attempt_201407141818_0002_m_000018_0/work/hs_err_pid25377.log
14/07/15 08:46:07 INFO mapred.JobClient: map 15% reduce 0%
14/07/15 08:46:09 INFO mapred.JobClient: map 16% reduce 0%
14/07/15 08:46:09 INFO mapred.JobClient: Task Id : attempt_201407141818_0002_m_000018_1, Status : FAILED
java.lang.Throwable: Child Error
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:271)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:258)
attempt_201407141818_0002_m_000018_1: #
attempt_201407141818_0002_m_000018_1: # There is insufficient memory for the Java Runtime Environment to continue.
attempt_201407141818_0002_m_000018_1: # Cannot create GC thread. Out of system resources.
attempt_201407141818_0002_m_000018_1: # An error report file with more information is saved as:
查看系统限制
[root@NameNode ~]# ulimit -a
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 2066288
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
文件数太少了。查看系统的/etc/security/limit.conf，etc/sysctl.conf ，换JDK版本等等，均无果！
在Root下设置 ulimit -c unlimited后，仍然不行。
[hadoop@NameNode mahout-distribution-0.9]$ ulimit -a
max user processes (-u) 1024
virtual memory (kbytes, -v) unlimited
经过查证，再在/etc/security/下一看。centos6多出来一个limits.d目录，下面有个文件： 90-nproc.config
此文件内容：
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.
* soft nproc 1024
root soft nproc unlimited
这里限制了1024呀，果断注释。
问题解决。
【转】：http://blog.csdn.net/liema2000/article/details/37808209