“too many open files" ----增大打开的文件数

http://www.cnblogs.com/ibook360/archive/2012/05/11/2495405.html 
[root@localhost ~]# ab -n 40000 -c 1024 http://192.168.1.26/index.html This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Copyright 2006 The Apache Software Foundation, http://www.apache.org/ 
Benchmarking 192.168.1.26 (be patient)
socket: Too many open files (24)

解决：
ulimit -n 65535
1.只针对当前会话修改,另外一个相同用户会话还是会1024
2.重起失效

说明:不是解决问题根本源因

永久修改有效:

修改/etc/security/limits.conf

*  soft   nofile   32768
*  hard   nofile   65536
所有用户都有效

“*" 还可以基于用户修改:

oracle  soft        nproc   2047
oracle  hard        nproc   16384
oracle  soft        nofile  1024
oracle  hard        nofile  65536

示例：[root@localhost ~]# cat /etc/security/limits.conf
# /etc/security/limits.conf
#
#Each line describes a limit for a user in the form:
#
#<domain>        <type>  <item>  <value>
#
#Where:
#<domain> can be:
#        - an user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#        - the wildcard %, can be also used with %group syntax,
#                 for maxlogin limit
#
#<type> can have the two values:
#        - "soft" for enforcing the soft limits
#        - "hard" for enforcing hard limits
#
#<item> can be one of the following:
#        - core - limits the core file size (KB)
#        - data - max data size (KB)
#        - fsize - maximum filesize (KB)
#        - memlock - max locked-in-memory address space (KB)
#        - nofile - max number of open files
#        - rss - max resident set size (KB)
#        - stack - max stack size (KB)
#        - cpu - max CPU time (MIN)
#        - nproc - max number of processes
#        - as - address space limit
#        - maxlogins - max number of logins for this user
#        - maxsyslogins - max number of logins on the system
#        - priority - the priority to run user process with
#        - locks - max number of file locks the user can hold
#        - sigpending - max number of pending signals
#        - msgqueue - max memory used by POSIX message queues (bytes)
#        - nice - max nice priority allowed to raise to
#        - rtprio - max realtime priority
#
#<domain>      <type>  <item>         <value>
##*               soft    core            0
#*               hard    rss             10000
#@student        hard    nproc           20
#@faculty        soft    nproc           20
#@faculty        hard    nproc           50
#ftp             hard    nproc           0
#@student        -       maxlogins       4
oracle  soft        nproc   2047
oracle  hard        nproc   16384
oracle  soft        nofile  1024
oracle  hard        nofile  65536# End of file