centos 6.3 64bit
cpu 双核
7.5G内存
php 5.3
apache 2
<ifmodule>
StartServers 20
MinSpareServers 20
MaxSpareServers 60
ServerLimit 10000
MaxClients 5000
MaxRequestsPerChild 1000
</ifmodule>
谷歌分析显示平时同时在线500到1200、晚上人最多。

日志：
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] Child 25763 returned a Fatal error... Apache is exiting!
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500
[Wed Jun 25 20:40:35 2014] [alert] (11)Resource temporarily unavailable: setuid: unable to change to uid: 500

这可能是啥问题、、、apache配置呢合理么？求教、