I am trying to see how apache2 thread model scales with the new kernel
and scheduler activation.

I compiled apache with worker module.

Here is a configuration that worked without much problem

StartServers 4
ServerLimit 64
ThreadPerChild 8

So intialy 32 thread are created.  
With this configuration the server runs fine.

Now if i change the settings to something like this

StartServers 16
ServerLimtit 64
ThreadsPerChild 32

As soon as any request comes to the server it hangs with loop
If more then one request comes then that is how many processes loop

In the error log a couple of these messages:
[crit] listener thread didnt exit

My initial guess is that the problem can be the stack size. 
I plan to increase it and see if the problem sticks around.

Also what is the procedure for debuging threaded applications ?