PQ75521: Webserver plugins to restrict the number of connections

 Fixes are available

5.0.2: WebSphere Application Server Version 5.0 Fix Pack 2 (Version 5.0.2)
PQ86603: IBM HTTP Server V2.0.x mod_alias/mod_rewrite conflict with V5.0 plug-in



APAR status
Closed as program error.

Error description
Webserver plugins to restrict the number of
connections
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All WebSphere Application Server users of    *
*                 HTTP plugin for webservers.                  *
****************************************************************
* PROBLEM DESCRIPTION: Application Servers could get over      *
*                      loaded with many connections.           *
*                                                              *
*                      There is a need to throttle the         *
*                      number of connections to the            *
*                      Application Servers.                    *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
Plugin is now enhanced to limit the number of connections
going to the Application Server.
Problem conclusion
HTTP plugin is enhanced so that users can set a limit of
the number of pending connections to an App Server using
the new attribute "MaxConnections".

If the number of current pending connections reaches
"MaxConnections", then that server will not be selected.
If no other servers are selectable, the request will end
with HTTP return code 503.

This feature will work well if the webservers follow
**threading model (not a process model)** and only
**one** process is started by the web server.

The following changes are to be made to have the
feature fully enabled.

The plugin config file should be updated to include
the attribute "MaxConnections" for the server definition.
The following is a sample configuration.

<ServerGroup Name="PLUGINCLUSTER">
 <Server CloneID="ujsv71f3" Name="myhost1_server1"
          MaxConnections="50">
      <Transport Hostname="myhost1" Port="9080"
                 Protocol="http"/>
  </Server>
  <Server CloneID="ujsvembh" Name="myhost2_server1"
          MaxConnections="100">
      <Transport Hostname="myhost2" Port="9081"
                 Protocol="http"/>
  </Server>
</ServerGroup>

Changes to IHS 2.0 config file (httpd.conf) :

Replace the existing block for worker.c with the following.

<IfModule worker.c>
ServerLimit           1
ThreadLimit           4000
StartServers          1
MaxClients            1024
MinSpareThreads       1
MaxSpareThreads       1024
ThreadsPerChild       1024
MaxRequestsPerChild   0
</IfModule>

Eventhough, IHS 2.0 follows threading model, it allows
more than one process to be started. Above changes to
the httpd.conf will ensure that only one process is
started by IHS 2.0.
Temporary fix Comments
APAR information
APAR number PQ75521
Reported component name WAS BASE 5.0
Reported component ID 5630A3600
Reported release 00W
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2003-06-23
Closed date 2003-07-18
Last modified date 2003-07-18

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Modules/Macros
Plugin          

Publications Referenced

Fix information

Applicable component levels
R003 PSY    UP
R00A PSY    UP
R00H PSY    UP
R00I PSY    UP
R00P PSY    UP
R00S PSY    UP
R00W PSY    UP


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > General
Operating system(s):
Software version: 00W
Software edition:
Reference #: PQ75521
IBM Group: Software Group
Modified date: Jul 18, 2003