Liferay cluster session replication

Question

I'm trying to enable session replication in liferay on tomcat without much luck. I have written a small test to see if sessions are being replicated and it works well in a separate JSP file that I have placed under webapps/examples but when I input the same code in a liferay-porlet only the JSESSION are correct.

   HttpSession httpSession = request.getSession();
   String testTime = (String) httpSession.getAttribute("testTime");
   String before = testTime;

   testTime = Long.toString(System.currentTimeMillis());
   httpSession.setAttribute("testTime", testTime);

   String sessionid = httpSession.getId();
   System.out.println("JSESSIONID:    "+sessionid);
   System.out.println("TEST TIME WAS: "+before);
   System.out.println("TEST TIME IS:  "+testTime);

Anybody got an idea of why its not working in the liferay-portlet? I have added distributable to portlet/WEB-INF/web.xml

Edit 1: Versions

liferay 6.1.1
Tomcat 7.0.47

Edit 2: I tried another test.

   HttpSession httpSession = request.getSession();
   String testTime = (String) httpSession.getAttribute("testTime");
   String before = testTime;

   if(testTime == null) {
       testTime = Long.toString(System.currentTimeMillis());
       httpSession.setAttribute("testTime", testTime);
   }

   String sessionid = httpSession.getId();
   System.out.println("JSESSIONID:    "+sessionid);
   System.out.println("TEST TIME WAS: "+before);
   System.out.println("TEST TIME IS:  "+testTime);

this time i only set the variable if its null. And it works as expected in the JSP outside of liferay but within liferay it goes like this.

1. First server to get the request gets null end sets the variable
2. When the other server gets the request it also gets null and setts the variable
3. When the server that got the first request tries to get the variable it gets the value from the second server. so now it is replicated.

It does not matter which server gets the first request its always the same outcome anyway

Edit 4. Cluster info

Nodes: 2 Load-balancer:

    <Proxy balancer://mycluster>
            BalancerMember ajp://node1:8009 route=tomcat1 loadfactor=1
            BalancerMember ajp://node2:8009 route=tomcat2 loadfactor=1

            Order Deny,Allow
            Deny from none
            Allow from all

            ProxySet lbmethod=byrequests
    </Proxy>
    <Location /balancer-manager>
            SetHandler balancer-manager
            Order deny,allow
            Allow from all
    </Location>

    ProxyPass /balancer-manager !
    ProxyPass / balancer://mycluster/

portal-ext.properties

cluster.link.enabled=true
jdbc.default.driverClassName=com.mysql.jdbc.Driver
jdbc.default.url=jdbc:mysql://dbserver:3306/lportal?autoReconnect&autoReconnectForPools;&useUnicode=true&characterEncoding=UTF-8&useFastDateParsing=false
jdbc.default.username=u jdbc.default.password=p

spring.configs=\
        META-INF/base-spring.xml,\
        \
        META-INF/hibernate-spring.xml,\
        META-INF/infrastructure-spring.xml,\
        META-INF/management-spring.xml,\
        \
        META-INF/util-spring.xml,\
        \
        META-INF/jpa-spring.xml,\
        \
        META-INF/executor-spring.xml,\
        \
        META-INF/audit-spring.xml,\
        META-INF/cluster-spring.xml,\
        META-INF/editor-spring.xml,\
        META-INF/jcr-spring.xml,\
        META-INF/ldap-spring.xml,\
        META-INF/messaging-core-spring.xml,\
        META-INF/messaging-misc-spring.xml,\
        META-INF/mobile-device-spring.xml,\
        META-INF/notifications-spring.xml,\
        META-INF/poller-spring.xml,\
        META-INF/rules-spring.xml,\
        META-INF/scheduler-spring.xml,\
        META-INF/scripting-spring.xml,\
        META-INF/search-spring.xml,\
        META-INF/workflow-spring.xml,\
        \
        META-INF/counter-spring.xml,\
        META-INF/mail-spring.xml,\
        META-INF/portal-spring.xml,\
        META-INF/portlet-container-spring.xml,\
        META-INF/staging-spring.xml,\
        META-INF/virtual-layouts-spring.xml,\
        \
        META-INF/dynamic-data-source-spring.xml,\
        #META-INF/shard-data-source-spring.xml,\
        #META-INF/memcached-spring.xml,\
        #META-INF/monitoring-spring.xml,\
        \
        META-INF/ext-spring.xml

Answer 1

If you want proper session replication, you should declare the portal as well as all plugins as distributable. The reason is that each one is a separate webapp.

However, utilizing session replication generates a huge amount of overhead. If you build a cluster for performance reasons, you're eating quite a bit of the added performance right away.

The standard advice (I know, you're not asking for this, but I'd like to see it in here for others finding the question later) is to rely on sticky sessions. If you ever want to shut down one appserver, take it out of the load balancer, but keep it online to serve the already allocated sessions for a while (they'll run out eventually). Not using session replication will typically lower the required processing capacity dramatically. Yes, there are some applications that definitely need session replication, but I'd estimate them to be 10% of those that initially want to use this feature.