Can somebody explain what is the Apache doing when the state is "sleep"?

My friend is suspecting that it is a zombie process, which means it consumes memory and CPU resource but it doing nothing.. that's why it is called "sleep" state. I doubt this theory.

My suspect is the child process is created when the apache first started and accepting request as it should. But when the user is already close the browser, the child process is still waiting other request in state of sleep and not immediately killed and that's why it is called "sleep" state.

Which one is correct? Actually I still doubt in my theory too, could somebody explain to me?

I am using mpm_prefork.

Thanks.

You are right, zombies are dead, so can't sleep !
It is wrong however to state zombies processes consumes memory and CPU, they make use of neither actually.
Yes, a sleeping process is a process that currently has nothing to execute. It is just waiting for some event to occur (user action, network traffic)

Hi jlliagre, thanks for the reply.

Now the problem is how to explain things like that to our client that has the same opinion with my friend. He insisted that the "sleep" process is harmful to his system and wanted a good explanation why the heck was the process sleeping while the load / hits to the web were hundreds.

Well the person has no *NIX background and this is the first time he is using Apache... and the word "sleep" which is displayed by prstat command really bugs him since the website becomes very slow at the peak time.

Our box is using 8 GB RAM and at the peak time, all the 90% of the memory is taken by apache. I already try to change the MaxClients directive in the httpd.comf file, and it has no effect to the performance whether the webservd user is 180 or 300. It is still slow..

Could it be because of the content? The index.php file itself is loading many dynamic flash files and image type objects. The server's bandwidth will be no problem as they are one of the biggest ISPs in my country.

I am gonna checking the Oracle's query in the server with my friend tomorrow. I just want to assure that the server (the "sleeping" httpd) is fine.

Thanks for the suggestion.

It's not as easy to diagnose such problem without observing the runtime environment. You should profile your application, run performance test with a proper methodology and discover the causes of the slowdown, which aren't obvious a priori. You should not only check memory usage, but the usual parameters you observe in such situation such as: CPUs usage, memory usage, I/O, network usage, threading issues, request queues and so on and discover which is the major bottleneck at peak time. Once resolved that, you may iterate to resolve other issues which may surface and you can't observe now.