Re: Understanding the APACHE 1.3 process model

Michael Conlen <m@xxxxxxxxxx> · Thu, 27 Sep 2007 22:51:21 -0400

you likely have 23 established connections using server processes and  

an additional number of server processes available to handle new  

connections. Apache keeps some number of processes available so that  

it doesn't have to fork the process at the time the request is made,  

but instead has the process ready to go. There are httpd.conf  

parameters to specify the minimum and maximum of these to keep  

available.

--
Michael Conlen

On Sep 27, 2007, at 10:39 PM, Robinson Craig wrote:

Hi Folks,

I'm trying to clarify my understanding of the APACHE 1.3 process model
on Solaris UNIX.

As I understand, "Apache 1.3 on UNIX is a pre-forking process per

request server". This means that Apache effectively needs 1 HTTP  

process

per 1 concurrently connected client. For example, if [StartServers  

5] is

set in httpd.conf, Apache starts with 6 HTTPD processes (5 childs + 1
parent). If there were 20 concurrently connected clients, then there
would be 21 HTTPD processes.

Firstly, is this correct understanding?

If so, my next question is thus:

What constitutes a "concurrently connected client"? At a moment in  

time,

if I run the following netstat command on a Solaris machine:

netstat -P tcp -n | grep ".80 " | grep -v TIME_WAIT | wc -l

I get '45', which is constituted as follows, with the following TCP
statuses:

23 x ESTABLISHED
1  x FIN_WAIT_1
20 x FIN_WAIT_2
1  x LAST_ACK
--
45

However, if I count the number of HTTPD processes at this same  

point in

time per '/usr/ucb/ps -auxww | grep httpd | wc -l', I get '35'.

Therefore, either my first premise above is wrong...or I am not
measuring the number of 'concurrently connected clients' accurately.

Any enlightenment will be appreciated.

Cheers, Craig

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