[Php-java-bridge-users] Tomcat cluster HOWTO (RE: php-java-bridge and tomcat cluster)

[<php...@li...>]

Hi,

[please excuse the delay]


> of tomcat are running within 15 to 30 min one of the
> tomcat instances stops responding and a browser

I could reproduce something like this when running
2700 instances of the sessionSharing.jsp. The reason
for the failure was an OutOfMemoryError in the session
replicator.

> We have not found exception in the log files

I have started both instances with catalina.sh run,
the error message appeared in the console window.

However, I have attached the proposed tomcat cluster
howto that someone has asked for:

----------------------------------------------

Ho do I set up a tomcat cluster?

Download tomcat 5 or higher, a Java JRE 5 or higher
and the PHP/Java Bridge 4.1.5 or higher.

The following example uses two nodes running on two
machines called "carlos" and "diego". The web server
is running on a third machine which has full access to
both nodes (at least it needs access to the ports from
the range [9267, [9367).

On all nodes: Extract the tomcat distribution into a
directory.

On "diego" add the following to conf/server.xml:

    <Cluster
className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
      channelSendOptions="8">
      <Manager
className="org.apache.catalina.ha.session.DeltaManager"
        expireSessionsOnShutdown="false"
        notifyListenersOnReplication="true"/>
      <Channel
className="org.apache.catalina.tribes.group.GroupChannel">
        <Receiver
className="org.apache.catalina.tribes.transport.nio.NioReceiver"
        address="diego"
        port="4000"
        autoBind="100"
        selectorTimeout="5000"
        maxThreads="6"/>
      </Channel>
    </Cluster>

On "carlos" add the following to conf/server.xml:

    <Cluster
className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
      channelSendOptions="8">
      <Manager
className="org.apache.catalina.ha.session.DeltaManager"
        expireSessionsOnShutdown="false"
        notifyListenersOnReplication="true"/>
      <Channel
className="org.apache.catalina.tribes.group.GroupChannel">
        <Receiver
className="org.apache.catalina.tribes.transport.nio.NioReceiver"
        address="carlos"
        port="4000"
        autoBind="100"
        selectorTimeout="5000"
        maxThreads="6"/>
      </Channel>
    </Cluster>

Copy the "JavaBridge.war" into the "webapps" directory
on "diego" and "carlos" and start both nodes. For
example with the command:

    JAVA_OPTS="-Dphp.java.bridge.promiscuous=true"
JAVA_HOME=/opt/jdk1.5 bin/catalina.sh run 

Start the web server on the third computer "timon".
For example with the command:

    apachectl restart 

Create a PHP script called "sessionSharing-diego.php"
and copy it into the web server document root (usually
"/var/www/html" or "~/public_html") on "timon":

    <?php
   
require_once("http://diego:8080/JavaBridge/java/Java.inc");
    $session = java_session();
    if(is_null($session->get("counter")))
      $session->put("counter", new
Java("java.lang.Integer", 1));

    $counter = java_values($session->get("counter"));
    print "HttpSession variable \"counter\":
$counter<br>\n";
    $next = new Java("java.lang.Integer", $counter+1);
    $session->put("counter", $next);
    ?>

Create a PHP script called "sessionSharing-carlos.php"
and copy it into the web server document root (usually
"/var/www/html" or "~/public_html") on "timon":

    <?php
   
require_once("http://carlos:8080/JavaBridge/java/Java.inc");
    $session = java_session();
    if(is_null($session->get("counter")))
      $session->put("counter", new
Java("java.lang.Integer", 1));

    $counter = java_values($session->get("counter"));
    print "HttpSession variable \"counter\":
$counter<br>\n";
    $next = new Java("java.lang.Integer", $counter+1);
    $session->put("counter", $next);
    ?>

Start a web brower and remove all cookies

Browse to http://timon/sessionSharing-carlos.php and
check the generated cookie. It should have the key
"JSESSIONID", host attribute "timon" and the path
attribute "/". The value should be "1". Click on the
browser refresh button to increase the value.

Use the same browser window and navigate to
http://timon/sessionSharing-diego.php and check if
there is still only one cookie with the same
attributes as before. The value should be "3"

Use the same browser window and navigate to
http://timon/sessionSharing-carlos.php and check if
there is still only one cookie with the same
attributes as before. The value should be "4".

Switch off "diego" and start it again.

Use the same browser window and navigate to
http://timon/sessionSharing-diego.php and check if
there is still only one cookie with the same
attributes as before. The value should be "5"

Switch off "carlos".

Use the same browser window and navigate to
http://timon/sessionSharing-carlos.php and check if
you get an exception.

Start "carlos".

Use the same browser window and navigate to
http://timon/sessionSharing-carlos.php and check if
there is still only one cookie with the same
attributes as before. The value should be "6"

Please see your HTTP server documentation how to set
it up as a load balancer. This differs from the
architecture described above in that the load balancer
forwards the requests to the nodes and the nodes run
PHP using the FastCGI mechanism.

---------------------------------------------------


Regards,
Jost Boekemeier





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