[Bug 710319] Re: CPU usage is incorrect on server-status page

[tinodj]

Hi Scott,

Thank you for your time. I did what you suggest, and I've noticed two
strange things.

1. Compiling showed me the following warnings:

gcc -o mytest mytest.c -lpthread
mytest.c: In function ‘child’:
mytest.c:83: warning: format ‘%3d’ expects type ‘int’, but argument 4 has type ‘                                                                                clock_t’
mytest.c:83: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘c                                                                                lock_t’
mytest.c:83: warning: format ‘%d’ expects type ‘int’, but argument 6 has type ‘c                                                                                lock_t’
and so on ... 


2. I was not able to test it with 500threads - it is production server, so ... I did it with 16. 

Here is the result:

 ./mytest 16
### Prep:
loops_per_tick: 289017
threads       : 16

### Test:
looptype    : cont
samplesleep : no
 ## start ##
 ## done. ##
 loop total:
  user   :    8800 ms
  system :      80 ms
  elapse :    4000 ms
  error  : 0

result: GOOD

Segmentation fault
^^^

Result is good - but there is a segmentation fault.

Furthermore, testing with apache, I found that the source of the problem
are the threads that are dying - because if I leave
MaxSpareServers=MaxClients  and MaxRequestsPerChild=0 ( so no thread is
killed) then CPU usage seems normal.

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https://bugs.launchpad.net/bugs/710319

Title:
  CPU usage is incorrect on server-status page