LAMP ->进程的CPU使用率过高

Question

我有一个带有CentOS 6.4、Apache2.2.15、MySQL 5.5.32和PHP5.3.26的LAMP系统，它使用一个带有4个CPU和6GBRAM的虚拟机上的Drupal (https)。

我的问题是apache进程的CPU使用率，如果我使用一个带有10个并发请求的网页爬行器，它的使用率将达到100%。怎样才能减少CPU的使用率？有什么想法吗？下面是我的top结果和配置文件，其中有一个mod_status server-status页面：

top - 20:37:23 up 14 days, 22:52,  2 users,  load average: 8.54, 6.45, 3.22
Tasks: 180 total,   8 running, 171 sleeping,   0 stopped,   1 zombie
Cpu(s): 93.5%us,  6.2%sy,  0.0%ni,  0.0%id,  0.1%wa,  0.0%hi,  0.2%si,  0.0%st
Mem:   8061508k total,  7634052k used,   427456k free,   146132k buffers
Swap:  8208376k total,    35116k used,  8173260k free,  5019896k cached
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                                                           
13155 apache    20   0  472m  95m  41m R 69.8  1.2   0:04.75 httpd                                                                                                                              
13144 apache    20   0  467m  88m  40m R 61.8  1.1   0:03.49 httpd                                                                                                                              
13141 apache    20   0  477m  97m  39m R 52.9  1.2   0:06.69 httpd                                                                                                                              
13162 apache    20   0  449m  71m  41m R 51.5  0.9   0:04.53 httpd                                                                                                                              
13145 apache    20   0  473m  93m  39m R 30.6  1.2   0:02.13 httpd                                                                                                                              
13136 apache    20   0  477m  98m  40m R 28.9  1.3   0:04.93 httpd                                                                                                                              
13158 apache    20   0  459m  79m  38m S 28.9  1.0   0:00.87 httpd                                                                                                                              
13160 apache    20   0  467m  84m  36m R 24.9  1.1   0:00.75 httpd                                                                                                                              
 3496 mysql     20   0 2454m 374m 5072 S 19.6  4.8  31:10.75 mysqld                                                                                                                             
13120 apache    20   0  460m  81m  40m S 15.3  1.0   0:05.63 httpd                                                                                                                              
13148 apache    20   0  462m  82m  39m R 12.0  1.1   0:01.79 httpd

我在我的httpd.conf中使用这个：

Timeout 60
KeepAlive On
MaxKeepAliveRequests 128
KeepAliveTimeout 10

<IfModule prefork.c>
  StartServers           16
  MinSpareServers        10
  MaxSpareServers        40
  ServerLimit       256
  MaxClients        256
  MaxRequestsPerChild  4000
</IfModule>

在我的MySQL my.cnf中(其他是默认的)：

max_allowed_packet = 64M
query_cache_size = 128M
query_cache_type = 1
query_cache_limit= 1M
slow-query-log-file=/var/log/mysqld/log-slow-queries.log // nothing logged -> no slow queries
table_cache = 1K
table_definition_cache = 4K
open_files_limit = 3K
thread_cache_size = 3

如果服务器没有任何事可做，mod_status将向我展示这一点：

Parent Server Generation: 0
Server uptime: 23 seconds
Total accesses: 10 - Total Traffic: 49 kB
CPU Usage: u.04 s0 cu0 cs0 - .174% CPU load
.435 requests/sec - 2181 B/second - 5017 B/request
1 requests currently being processed, 15 idle workers
W_______________................................................
................................................................
................................................................
................................................................
Scoreboard Key:
"_" Waiting for Connection, "S" Starting up, "R" Reading Request,
"W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
"C" Closing connection, "L" Logging, "G" Gracefully finishing,
"I" Idle cleanup of worker, "." Open slot with no current process

Srv PID Acc M   CPU SS  Req Conn    Child   Slot    Client  VHost    Request
0-0 14223   10/10/10    W   0.04    0   0   49.1    0.05    0.05     IP www.test.com    GET /server-status HTTP/1.1

并且使用一个网站爬虫(~10个并发请求)：

Server uptime: 5 minutes 46 seconds
Total accesses: 1883 - Total Traffic: 65.5 MB
CPU Usage: u365.13 s17.79 cu0 cs0 - 111% CPU load
5.44 requests/sec - 193.8 kB/second - 35.6 kB/request
15 requests currently being processed, 10 idle workers
WWWW_WWKW___W_W__WW__K_WW.......................................
................................................................
................................................................
................................................................

    Srv     PID     Acc         M   CPU     SS  Req     Conn    Child   Slot    Client  VHost   Request
0-0     14223   90/207/207  W   2.07    0   0       902.0   1.61    1.61    IP  www.test.com    GET /server-status HTTP/1.1
1-0     14224   11/70/70    W   18.87   47  0       279.7   0.84    0.84    IP  www.test.com    GET /site1
2-0     14225   0/19/19     W   9.66    1   0       0.0     0.95    0.95    IP  www.test.com    GET /site2
3-0     14226   1/84/84     W   13.94   36  0       0.0     2.14    2.14    IP  www.test.com    GET /site3.pdf
4-0     14227   0/153/153   _   27.46   4   81      0.0     3.56    3.56    IP  www.test.com    GET /site4pdf
5-0     14228   12/78/78    W   17.59   1   0       275.8   2.67    2.67    IP  www.test.com    GET /site5.pdf
6-0     14229   10/90/90    W   14.62   0   0       611.4   3.85    3.85    IP  www.test.com    GET /site6
7-0     14230   4/53/53     K   34.12   0   141     9       81.9    2.48    IP  www.test.com    GET /site7
8-0     14231   1/114/114   W   12.39   27  0       0.0     2.29    2.29    IP  www.test.com    GET /site8.pdf
9-0     14232   0/106/106   _   9.68    2   64      0.0     6.33    6.33    IP  www.test.com    GET /site9
10-0    14233   0/39/39     _   15.66   5   1376    0.0     2.68    2.68    IP  www.test.com    GET /site10
11-0    14234   0/36/36     _   11.31   5   128     0.0     2.78    2.78    IP  www.test.com    GET /site11
12-0    14235   1/63/63     W   10.58   7   0       70.9    3.59    3.59    IP  www.test.com    GET /site12.pdf
13-0    14236   0/100/100   _   22.76   1   20      0.0     2.76    2.76    IP  www.test.com    GET /site13
14-0    14237   0/63/63     W   4.34    37  0       0.0     0.58    0.58    IP  www.test.com    GET /site14
15-0    14238   0/12/12     _   1.75    0   29      0.0     1.85    1.85    IP  www.test.com    GET /site15
16-0    14283   0/43/43     _   14.94   1   119     0.0     2.25    2.25    IP  www.test.com    GET /site16
17-0    14286   8/80/80     W   6.79    0   0       222.7   5.98    5.98    IP  www.test.com    GET /site17.pdf
18-0    14288   3/111/111   W   21.87   0   0       60.5    2.35    2.35    IP  www.test.com    GET /site18.pdf
19-0    14289   0/75/75     _   18.81   5   31      0.0     3.06    3.06    IP  www.test.com    GET /site19
20-0    14290   0/50/50     _   16.15   1   259     0.0     2.16    2.16    IP  www.test.com    GET /site20.pdf
21-0    14292   6/88/88     K   23.71   0   0       32.8    2.79    2.79    IP  www.test.com    GET /site21
22-0    14293   0/92/92     _   30.82   1   45      0.0     3.78    3.78    IP  www.test.com    GET /site22
23-0    14294   11/37/37    W   12.85   27  0       774.2   1.48    1.48    IP  www.test.com    GET /site23.pdf
24-0    14302   16/20/20    W   10.18   37  0       557.3   0.68    0.68    IP  www.test.com    GET /site24.pdf

在爬行结束的时候，我已经到了Srv 46-0。

跳槽？在爬行结束后我做了这件事：

# swapon -s
Filename                Type        Size    Used    Priority
/dev/am-1                      partition         8208376    35172   -1
# free
         total       used       free     shared    buffers     cached
Mem:       8061508    7287776     773732          0     147220    4806004
-/+ buffers/cache:    2334552    5726956
Swap:      8208376      35172    8173204

Answer 1

看着这其中的一些，你似乎在交换。交换是非常糟糕的，并导致大量CPU的消耗，进行I/O交换进程的进出。您可以考虑添加更多的memory....or，以减少启动的apache服务器的数量。

Answer 2

使用新文物并查看应用程序的web事务。

新的遗迹现在也包含Drupal特定的工具(模块，钩子，视图)。

对不起，如果这听起来像一个广告，但如果你运行Drupal，这真的是一个没有头脑的丰富的信息提供。反正我和新文物没什么关系，只是一个快乐的顾客。

如果你想用硬的方式来分析你的代码(例如，oprofile)

HTH

附注：

你可以把你的thread_cache_size提高到一个更合理的数字(例如32)，但我怀疑这会产生很大的影响。