[Moin-user] CPU over 100% while "RecentChanges"

[Marcel Häfner]

Hi there

I'm running now a MoinMoin (actually a small Wikifarm) with Twisted on a
RedHat Linux System with 4 XEON CPUs and 4 GB Memory (well it's hosting
environment; so not only for me). 

Due the configuration the twisted instance running as localhost, with 10
threads (default) and the main front apache proxy the request. 

While I made some performance Test with AB (-n 100 -c 10) I notice that
the Memory usages stays around 15-30MB and the CPU goes with 2 or 5%
normally.  Interesting is if I run my test on a Page with
[[RecentChanges]] included... the CPU goes up to 110%. (see below for
some data). The "normal" Page Access without Stress Testing is really
fast. I did run those tests on different days and times and saw always
the same result / effect.

As far as I understand Python and the Twisted Framework... it's only
using threads so I can not benefit from multiple processors. But anyway
I'm a bit confused 'bout this high %cpu wile fetching the RecentChanges
Page. 

*****************************
MY QUESTIONS
*****************************


1. Why; or what makes the CPU goes so high?
*******************************************
a) Diskaccess?
b) I'm missing something... like AntiSpam or SurgeProtection that makes
 the CPU goes so high?


2. Are there any optimizing possibilities, like:
*******************************************
a) Running MemCached with MoinMoin? 

b) A Makro like RecentChangesChached (like the TitleSearch)?

c) Optimizing the Twisted Framework, how (maybe forking process; extend
the threads to 20 doesn't help a lot..)

d) Using Mod_Python or Standalone Modus (FastCGI ist not an option for
me)

e) don't care... just avoid RecentChange, drink a coffee and waiting for
1.6 


thanks for any comments.
Best regards,
Marcel



***************************************************
AB Test
***************************************************
ab -n 100 -c 10 http://lotek.heavy.ch/Index
Benchmarking lotek.heavy.ch (be patient).....done


Server Software:        TwistedWeb/2.5.0
Server Hostname:        lotek.heavy.ch
Server Port:            80

Document Path:          /Index
Document Length:        32752 bytes

Concurrency Level:      10
Time taken for tests:   14.215936 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      3321210 bytes
HTML transferred:       3301919 bytes
Requests per second:    7.03 [#/sec] (mean)
Time per request:       1421.594 [ms] (mean)
Time per request:       142.159 [ms] (mean, across all concurrent
requests)
Transfer rate:          228.12 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:      139  144   5.0    142     164
Processing:   590 1238 132.7   1235    1601
Waiting:      164  407  91.3    411    1081
Total:        732 1383 134.0   1378    1751

Percentage of the requests served within a certain time (ms)
  50%   1378
  66%   1403
  75%   1420
  80%   1441
  90%   1522
  95%   1664
  98%   1730
  99%   1751
 100%   1751 (longest request)


***************************************************
Normal Timing (without Stress Testing)
***************************************************
1. Timings of RecentChange
* compile_huge_and_ugly = 0.000s
* getACL = 0.035s
* getPageList = 0.017s
* load_multi_cfg = 0.000s
* run = 0.170s
* send_page = 0.147s
* send_page_content = 0.117s
* total = 0.172s

2. a single Page
* compile_huge_and_ugly = 0.000s
  * getACL = 0.003s
  * load_multi_cfg = 0.000s
  * run = 0.057s
  * send_page = 0.056s
  * send_page_content = 0.020s
  * total = 0.060s