Configuring apache prefork + mod_jk + jboss

The goal of this resource is to represent a working configuration of the above mentioned servers. We here assume you have installed apache prefork, mod_jk и jboss.

We start with the configuration of the apache http server:
apache2.conf :

# Replace jsp-hostname with the hostname of your JSP server, as
# specified in workers.properties.
#
<IfModule mod_jk.c>
	JkWorkersFile /etc/apache2/includes/workers.properties
	JkShmFile  /var/log/apache2/jk-runtime-status
	JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
	JkRequestLogFormat "%w %V %T"
</IfModule>


<IfModule mpm_prefork_module>
    StartServers 10
    MinSpareServers 10
    MaxSpareServers 30
    MaxClients          200
    MaxRequestsPerChild 0
</IfModule>


#Your site config
<VirtualHost 78.78.78.78:80>
    ServerAdmin     info@yoursite.com
    ServerName      www.yoursite.com
    ServerAlias     yoursite.com 78.78.78.78 
    
    ErrorLog        /var/log/apache2/users/some_error.log
    <IfModule mod_jk.c>
        JkMount /*.* worker1
        JkMount /* worker1
    </IfModule>    
</VirtualHost>

JkWorkersFile must point to workers.properties


Here is the file workers.properties

worker.list=worker1
worker.worker1.type=ajp13
worker.worker1.host=127.0.0.1
worker.worker1.port=8009
worker.worker1.lbfactor=1
worker.worker1.connection_pool_timeout=600
#Socket timeout in seconds used for the communication channel between JK and remote host.
worker.worker1.socket_timeout=40
worker.worker1.socket_keepalive=1
#Do not use connection_pool_size with values higher then 1 on Apache 2.x prefork
worker.worker1.connection_pool_size=1
#Do not use connection_pool_size with values higher then 1 on Apache 2.x prefork 
worker.worker1.connection_pool_minsize=1
worker.worker1.ping_mode=A
#Timeout in milliseconds used when waiting for the CPong answer of a CPing connection probe. 
worker.worker1.ping_timeout=10000
#connection_ping_interval in seconds
worker.worker1.connection_ping_interval=70

server.xml in the JBoss or Tomcat:

    <Connector port="8009" address="${jboss.bind.address}" 
         protocol="AJP/1.3"
         emptySessionPath="true" 
         enableLookups="false" 
         redirectPort="8443" 
         URIEncoding="UTF-8" 
         maxThreads="400" 
         connectionTimeout="600000"
         acceptCount="400"
         
         />

The key here is:
- when determining the MaxClients you must honor this formula:
MaxClients = maxThreads * 0.8
or at least MaxClients to be not more than maxThreads, considering MaxClients cannot be more 256

- connection_pool_timeout=600 must be as <Connector...connectionTimeout="600000", having connection_pool_timeout is in seconds and connectionTimeout is in milliseconds.


One important remark here is how mod_jk forwards the request.
In the mod_jk configuration we used

JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories 

and this is not very correct and more specifically the option +ForwardURICompat. If we don't use mod_rewrite it is more correct to pass URI path without any change to JBOSS.

+ForwardURICompatUnparsed option is most secure, because it does not modify the URI. It is more safe option in case we have UTF symbol in the url. If we have URL PARAMETERS which are utf it may work with the +ForwardURICompat , but if you have utf symbols in the PATH, for example:

/some/%D0%B2%D0%B0%D0%B3%D0%BE%D0%BD?param1=value1

then the thing that works is this:

JkOptions +ForwardKeySize +ForwardURICompatUnparsed -ForwardDirectories