看来我们的 apache httpd 某处可能存在（不断增长的）内存问题。
快速图片：http ://screencast.com/t/NGAzarD87O
请注意，它已经在原始（物理）服务器上运行了一段时间。现在在新的 VM（具有更多内存和 cpu）上，它运行但会慢慢消耗 mem/swap，直到系统挂起。
如果我重新启动 httpd，mem 会跳回来（如果我们抓住它）。
httpd.x86_64 2.2.3-76.el5_9 installed
PHP 5.1.6 (cli) (built: Jun 22 2012 06:20:25)
MySQL Server version: 5.0.95
我不认为它可以是运行/等的任何脚本，因为它们在物理机器上运行多年。我们尝试在新机器上匹配所有配置（http、php 等），但无法弄清楚为什么 httpd 不断增长。
$ ps -ylC httpd --sort:rss
S UID PID PPID C PRI NI RSS SZ WCHAN TTY TIME CMD
S 0 13814 1 0 78 0 29208 68382 - ? 00:00:00 httpd
S 48 20854 13814 0 76 0 34876 70930 semtim ? 00:00:00 httpd
S 48 20853 13814 0 75 0 36592 71387 semtim ? 00:00:00 httpd
S 48 13822 13814 0 75 0 36780 71430 semtim ? 00:00:00 httpd
S 48 20696 13814 0 75 0 37092 71520 semtim ? 00:00:00 httpd
S 48 13821 13814 0 75 0 37184 71529 semtim ? 00:00:01 httpd
S 48 13820 13814 0 75 0 37220 71527 - ? 00:00:01 httpd
S 48 13824 13814 0 75 0 37236 71513 semtim ? 00:00:01 httpd
S 48 13818 13814 0 75 0 37636 71547 semtim ? 00:00:01 httpd
S 48 13819 13814 0 75 0 37636 71617 semtim ? 00:00:01 httpd
S 48 13823 13814 0 75 0 37888 71689 semtim ? 00:00:01 httpd
S 48 13825 13814 0 75 0 37900 71676 semtim ? 00:00:01 httpd
更新：在写出这个问题时（可能需要 10-15 分钟）我重新运行了上面的内容，RSS 都在 ~51072 而不是上面的 ~37000
Private + Shared = RAM used Program
.... SNIPPED OUT ....
208.0 MiB + 25.5 MiB = 233.5 MiB httpd (12)
---------------------------------
477.1 MiB
PHP 内存设置：
max_execution_time = 30
max_input_time = 60
memory_limit = 152M
模块：
$ apachectl -M
httpd: Could not reliably determine the server's fully qualified domain name, using 192.168.1.2 for ServerName
Loaded Modules:
core_module (static)
mpm_prefork_module (static)
http_module (static)
so_module (static)
auth_basic_module (shared)
auth_digest_module (shared)
authn_file_module (shared)
authn_alias_module (shared)
authn_anon_module (shared)
authn_dbm_module (shared)
authn_default_module (shared)
authz_host_module (shared)
authz_user_module (shared)
authz_owner_module (shared)
authz_groupfile_module (shared)
authz_dbm_module (shared)
authz_default_module (shared)
ldap_module (shared)
authnz_ldap_module (shared)
include_module (shared)
log_config_module (shared)
logio_module (shared)
env_module (shared)
ext_filter_module (shared)
mime_magic_module (shared)
expires_module (shared)
deflate_module (shared)
headers_module (shared)
usertrack_module (shared)
setenvif_module (shared)
mime_module (shared)
dav_module (shared)
status_module (shared)
autoindex_module (shared)
info_module (shared)
dav_fs_module (shared)
vhost_alias_module (shared)
negotiation_module (shared)
dir_module (shared)
actions_module (shared)
speling_module (shared)
userdir_module (shared)
alias_module (shared)
rewrite_module (shared)
proxy_module (shared)
proxy_balancer_module (shared)
proxy_ftp_module (shared)
proxy_http_module (shared)
proxy_connect_module (shared)
cache_module (shared)
suexec_module (shared)
disk_cache_module (shared)
file_cache_module (shared)
mem_cache_module (shared)
cgi_module (shared)
version_module (shared)
perl_module (shared)
php5_module (shared)
proxy_ajp_module (shared)
python_module (shared)
ssl_module (shared)
Syntax OK
httpd.conf 设置：
IfModule prefork.c> ignore format on these tags
StartServers 8
MinSpareServers 5
MaxSpareServers 20
ServerLimit 256
MaxClients 256
MaxRequestsPerChild 4000
# worker MPM
StartServers 2
MaxClients 150
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25
MaxRequestsPerChild 0
使用https://code.google.com/p/check-httpd-limits/wiki/Documentation上的程序我得到：
检查 Apache Httpd MPM 配置限制（2.4 版）
让-塞巴斯蒂安·莫里塞特（Jean-Sebastien Morisset）- http://surniaulula.com/
Httpd 二进制
- 配置：/etc/httpd/conf/httpd.conf
- 可执行文件：/usr/sbin/httpd
- MPM：前叉
- 根目录：/etc/httpd
- 版本：2.2
Httpd 进程
- PID 10860 (httpd)：106.93 MB / 3.95 MB 共享
- PID 13814 (httpd) : 28.52 MB / 6.36 MB 共享 [从平均值中排除]
- PID 13818 (httpd)：180.28 MB / 4.29 MB 共享
- PID 13819 (httpd)：182.67 MB / 4.04 MB 共享
- PID 13820 (httpd)：182.45 MB / 4.08 MB 共享
- PID 13821 (httpd)：185.53 MB / 4.04 MB 共享
- PID 13822 (httpd)：176.12 MB / 4.36 MB 共享
- PID 13823 (httpd)：180.05 MB / 4.04 MB 共享
- PID 13824 (httpd)：182.21 MB / 4.05 MB 共享
- PID 13825 (httpd)：179.36 MB / 4.04 MB 共享
- PID 20696 (httpd)：180.10 MB / 4.04 MB 共享
- PID 20853 (httpd)：180.39 MB / 4.03 MB 共享
- PID 20854 (httpd)：180.79 MB / 4.04 MB 共享
- PID 21003 (httpd)：159.77 MB / 4.05 MB 共享
- HttpdRealAvg：166.09 MB [不包括共享]
- HttpdSharedAvg：4.05 MB
- HttpdRealTot：2225.76 MB [不包括共享]
- HttpdRunning：14
Httpd 配置
- 启动服务器：8
- 服务器限制：256
- MinSpareServers：5
- MaxSpareServers：20
- MaxRequestsPerChild：4000
- 最大客户数：256
服务器内存
- 缓存：671.46 MB
- 内存免费：547.88 MB
- 内存总量：3819.89 MB
- 无交换：5951.89 MB
- 总交换：5951.99 MB
计算摘要
- OtherProcsMem：370.74 MB（MemTotal - 缓存 - MemFree - HttpdRealTot - HttpdSharedAvg）
- FreeMemNoHttpd：3449.15 MB（MemFree + Cached + HttpdRealTot + HttpdSharedAvg）
- MaxLimitHttpdMem：42523.09 MB（HttpdRealAvg * MaxClients + HttpdSharedAvg）
- AllProcsTotalMem：42893.83 MB（OtherProcsMem + MaxLimitHttpdMem）
MemTotal 的最大值 (3819.89 MB)
StartServers 8 #（无变化）默认为 5
ServerLimit 21 # (256 -> 21) MaxClients
MinSpareServers 5 #（无变化）默认为 5
MaxSpareServers 20 #（无变化）默认为 10
MaxRequestsPerChild 4000 #（无变化）默认为 10000
MaxClients 21 # (256 -> 21) (MemFree + Cached + HttpdRealTot + HttpdSharedAvg) / HttpdRealAvg
结果
错误：AllProcsTotalMem (42893.83 MB) 超过 MemTotal (3819.89 MB) 和自由交换 (5951.89 MB) 33122.05 MB。