apache性能调优

apache + 2 tomcat搭建的集群，在320并发的时候，apache自动宕机，错误信息如下：

[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:40:59 2011] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 2
[Tue Nov 15 10:41:00 2011] [alert] Child 26597 returned a Fatal error... Apache is exiting!
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue Nov 15 10:41:00 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex

根本原因是系统资源限制造成的，/etc/security/limits.conf配置如下：

*                soft    nofile          40960
*                hard    nofile          40960

打开文件数改大了，但是线程数没有改，RHEL6.1中nproc默认是1000个，也需要改大

core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 25924
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 40960
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 1000
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

 最后修改limits.conf为

*                soft    nofile          40960
*                hard    nofile          40960
*                soft    nproc           5000
*                hard    nproc           5000
*                soft    memlock         unlimited
*                hard    memlock         unlimited

apache出现各种错误是，可以参考下面的文章，IBM Http Server的说明文档很细致啊

http://blog.sina.com.cn/s/blog_7dfa89350100wh2f.html