[users@httpd] Apache stops processing the request

[Chidanand Gangur <ch...@gmail.com>]

Hi,

I am using apache with mod_php and mod_ssl

apache-1.3.34
php-4.4.2


I have following server configuration

  Timeout               300
  MaxKeepAliveRequests  0
  KeepAliveTimeout      60
  KeepAlive             On
  MinSpareServers       3
  MaxSpareServers       5
  StartServers          4
  MaxClients            250
  MaxRequestsPerChild   0

Let me explain my system


------------------  UNIX stream socket    -------------------------
SSL                   -------------------------
backend       <------------------------------>Apache server
<----------------------->client (around 150-180)
module
------------------
-------------------------
--------------------------

Few client querys for some data (the data length can vary from 10-100K) from
the back end every 30 seconds this communication from php to backend process
happens on unix stream socket.

Rest of the clients keep on sending periodic keep alives to the backend
every 60 seconds. (communication for these request to back end happens on
UNIX datagram sockets.

All the comunication from client to Apache is on SSL.

My observation:

Too many apache process get spwaned (100-150) and things become very slow.

1.  where my apache process stops responding to the client requests.
2.  When this problem occurs I see lot of unix stream sockets in the
netstat.
3.  free memory on my system (180-200Mb).
4.  Number of apache process (150-180)
5.  when issused ps -ax i see al the process show status as S (sleeping)
6.  I see lot of UNIX stream socket entries in netstat
7.  I see the data is not sent from php to the back end module.
8.  All of a sudden burst of request come to the back end. (Burst requests
are served properly by the back end)

So my question is when I have MaxClients as 250 why are the request not
served.
What server configuration is going wrong?
Is there any internal limitation which is causing such condition?
Does apache+mod_php+mod_ssl have any limitation?

Please give a pointer to go ahead.

-- 
Chidanand Gangur
Pune.