後始末

方針が決まったのであとはただ作業。

普通に考えて、プロセス間通信でもしない限りmemory上のキャッシュはプロセス単位で閉じたものになる。ここにもこう書いてある。

each process builds up its own in-memory cache.

httplibで304と200が混じったのは、cacheに中身が入ったapache instanceに処理してもらえたかどうかなのだろう。

mpm.conf of /etc/httpd/conf.d
TheardLimitを1000にするのは怖くてできない。fileがそこまでたくさん作れる保証が無い。kernelの.configをいじればいいのだろうけど。

<IfModule worker.c>
StartServers         1
MinSpareThreads     16
MaxSpareThreads     32
MaxRequestsPerChild  0
ThreadLimit        512
ThreadsPerChild    512
MaxClients         512
</IfModule>

結果。
測定中にロードグラフを眺めると、CPU負荷はほとんど上がらずにNetworkのsentだけが100%の状態になる。

20%くらい改善したかな？

-c 300なら大丈夫。

[nori@asama]~/Desktop/work/srvtest% ab -n 100000 -c 300 "http://image.backgammonbase.com/image?gnubgid=4HPwATDgc%2FABMA%3AMAAAAAAAAAAA&height=300&width=400&css=minimal&format=png"
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 image.backgammonbase.com (be patient)
Completed 10000 requests
Completed 20000 requests
Completed 30000 requests
Completed 40000 requests
Completed 50000 requests
Completed 60000 requests
Completed 70000 requests
Completed 80000 requests
Completed 90000 requests
Finished 100000 requests


Server Software:        Apache/2.2.3
Server Hostname:        image.backgammonbase.com
Server Port:            80

Document Path:          /image?gnubgid=4HPwATDgc%2FABMA%3AMAAAAAAAAAAA&height=300&width=400&css=minimal&format=png
Document Length:        17877 bytes

Concurrency Level:      300
Time taken for tests:   158.133125 seconds
Complete requests:      100000
Failed requests:        0
Write errors:           0
Total transferred:      1828222590 bytes
HTML transferred:       1789024272 bytes
Requests per second:    632.38 [#/sec] (mean)
Time per request:       474.399 [ms] (mean)
Time per request:       1.581 [ms] (mean, across all concurrent requests)
Transfer rate:          11290.32 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        3   94  84.1     93    3106
Processing:   113  378  18.2    379    1060
Waiting:        2   93  10.4     95     405
Total:        120  473  86.5    473    3956

Percentage of the requests served within a certain time (ms)
  50%    473
  66%    474
  75%    474
  80%    474
  90%    474
  95%    474
  98%    474
  99%    475
 100%   3956 (longest request)

350にすると破綻の兆しでてくる。とはいえ、変更前の312よりはマシ。

[nori@asama]~/Desktop/work/srvtest% ab -n 100000 -c 350 "http://image.backgammonbase.com/image?gnubgid=4HPwATDgc%2FABMA%3AMAAAAAAAAAAA&height=300&width=400&css=minimal&format=png"
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 image.backgammonbase.com (be patient)
Completed 10000 requests
Completed 20000 requests
Completed 30000 requests
Completed 40000 requests
Completed 50000 requests
Completed 60000 requests
Completed 70000 requests
Completed 80000 requests
Completed 90000 requests
Finished 100000 requests


Server Software:        Apache/2.2.3
Server Hostname:        image.backgammonbase.com
Server Port:            80

Document Path:          /image?gnubgid=4HPwATDgc%2FABMA%3AMAAAAAAAAAAA&height=300&width=400&css=minimal&format=png
Document Length:        17877 bytes

Concurrency Level:      350
Time taken for tests:   158.20219 seconds
Complete requests:      100000
Failed requests:        0
Write errors:           0
Total transferred:      1827205440 bytes
HTML transferred:       1788094492 bytes
Requests per second:    632.83 [#/sec] (mean)
Time per request:       553.071 [ms] (mean)
Time per request:       1.580 [ms] (mean, across all concurrent requests)
Transfer rate:          11292.10 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        4  119 245.5    102    9104
Processing:   121  426  78.2    410    1831
Waiting:        2  103  26.2    102     719
Total:        128  545 262.3    512   10024

Percentage of the requests served within a certain time (ms)
  50%    512
  66%    513
  75%    514
  80%    514
  90%    516
  95%    716
  98%    821
  99%   1025
 100%  10024 (longest request)