Wrong number httpd.worker process

[Wp_SEO]

Hi all,
i use plesk 11.5 last version up to date and recently i try to use the nginx reverse proxy.

After some test i decide to come back to only Apache server but now i have a strange problem.

The httpd.conf is the same (before nginx,after ngnix) but the worker process work in a different way.

This is the configuration of worker:

<IfModule worker.c>
StartServers 10
ServerLimit 20
ThreadLimit 64
MinSpareThreads 15
MaxSpareThreads 35
ThreadsPerChild 64
#ThreadStackSize 2097152
MaxClients 512
MaxRequestsPerChild 0
</IfModule>

After i remove nginx and after httpdmng reconfigure all and reconfigure server every time i restart or graceful restart the httpd process i see 10 httpd.worker process (correctly like StartServers) and after a couple of second 7 were killed (defunct). After this the apache server work with 3 worker process 1 (root user) e 2 (apache user) also if is high loaded.

someone can help me debugging this situation?

I try some stupid tricks like switch to prefork and after switch again to worker but nothing change.

I made some change in my.cnf but i don't think there is a link between this 2 processes.

before nginx installation i saw the correct number of process configured in httpd.conf

What can i check? There is a way to debug and understand why 7 worker processes were killed immediately after start?
i try to switch apache to debug log level but i doesn't find anything interesting.

Thanks for any suggestion

 

[Wp_SEO]

may have remained active rules proxying to make nginx reverse proxy? although it is no longer installed?

Using LogLevel debug and doing a restart of apache i saw this rows:

[Thu Oct 03 15:27:35 2013] [info] Server built: Aug 13 2013 17:30:10
[Thu Oct 03 15:27:35 2013] [debug] worker.c(1757): AcceptMutex: sysvsem (default: sysvsem)
[Thu Oct 03 15:27:35 2013] [warn] long lost child came home! (pid 8976)
[Thu Oct 03 15:27:35 2013] [debug] proxy_util.c(1833): proxy: grabbed scoreboard slot 0 in child 9489 for worker proxy:reverse
[Thu Oct 03 15:27:35 2013] [debug] proxy_util.c(1852): proxy: worker proxy:reverse already initialized
[Thu Oct 03 15:27:35 2013] [debug] proxy_util.c(1929): proxy: initialized worker 0 in child 9489 for (*) min=0 max=64 smax=64

any idea?

 

[Wp_SEO]

i tried make change but the problem persist.

anybody know why workers work in this strange way?