23.2.3. CacheManager service configuration

JBoss Cache provides the session state replication service for EJB 3.0 stateful session beans. The CacheManager service, described in Section 21.2.1, “The JBoss Enterprise Application Platform CacheManager Service” is both a factory and registry of JBoss Cache instances. By default, stateful session beans use the sfsb-cache configuration from the CacheManager, defined as follows:
<bean name="StandardSFSBCacheConfig" class="org.jboss.cache.config.Configuration">

  <!--  No transaction manager lookup -->
  
  <!-- Name of cluster. Needs to be the same for all members -->
  <property name="clusterName">${jboss.partition.name:DefaultPartition}-SFSBCache</property>
  <!--
    Use a UDP (multicast) based stack. Need JGroups flow control (FC)
    because we are using asynchronous replication.
  -->
  <property name="multiplexerStack">${jboss.default.jgroups.stack:udp}</property>
  <property name="fetchInMemoryState">true</property>
  
  <property name="nodeLockingScheme">PESSIMISTIC</property>
  <property name="isolationLevel">REPEATABLE_READ</property>
  <property name="useLockStriping">false</property>
  <property name="cacheMode">REPL_ASYNC</property>
  
  <!--
    Number of milliseconds to wait until all responses for a
    synchronous call have been received. Make this longer 
    than lockAcquisitionTimeout.
  -->
  <property name="syncReplTimeout">17500</property>
  <!-- Max number of milliseconds to wait for a lock acquisition -->
  <property name="lockAcquisitionTimeout">15000</property>
  <!-- The max amount of time (in milliseconds) we wait until the
  state (ie. the contents of the cache) are retrieved from
  existing members at startup. -->
  <property name="stateRetrievalTimeout">60000</property>
  
  <!--
    SFSBs use region-based marshalling to provide for partial state
    transfer during deployment/undeployment.
  -->
  <property name="useRegionBasedMarshalling">false</property>
  <!-- Must match the value of "useRegionBasedMarshalling" -->
  <property name="inactiveOnStartup">false</property>
  
  <!-- Disable asynchronous RPC marshalling/sending -->
  <property name="serializationExecutorPoolSize">0</property>        
  <!-- We have no asynchronous notification listeners -->
  <property name="listenerAsyncPoolSize">0</property>
  
  <property name="exposeManagementStatistics">true</property>
  
  <property name="buddyReplicationConfig">
    <bean class="org.jboss.cache.config.BuddyReplicationConfig">
    
      <!--  Just set to true to turn on buddy replication -->
      <property name="enabled">false</property>
      
      <!--
        A way to specify a preferred replication group.  We try
        and pick a buddy who shares the same pool name (falling 
        back to other buddies if not available).
      -->
      <property name="buddyPoolName">default</property>
      
      <property name="buddyCommunicationTimeout">17500</property>
      
      <!-- Do not change these -->
      <property name="autoDataGravitation">false</property>
      <property name="dataGravitationRemoveOnFind">true</property>
      <property name="dataGravitationSearchBackupTrees">true</property>
               
      <property name="buddyLocatorConfig">
        <bean class="org.jboss.cache.buddyreplication.NextMemberBuddyLocatorConfig">
          <!-- The number of backup nodes we maintain -->
          <property name="numBuddies">1</property>
          <!-- Means that each node will *try* to select a buddy on 
               a different physical host. If not able to do so 
               though, it will fall back to colocated nodes. -->
          <property name="ignoreColocatedBuddies">true</property>
        </bean>
      </property>
    </bean>
  </property>
  <property name="cacheLoaderConfig">
    <bean class="org.jboss.cache.config.CacheLoaderConfig">
      <!-- Do not change these -->
      <property name="passivation">true</property>
      <property name="shared">false</property>
      
      <property name="individualCacheLoaderConfigs">
        <list>
          <bean class="org.jboss.cache.loader.FileCacheLoaderConfig">
            <!-- Where passivated sessions are stored -->
            <property name="location">${jboss.server.data.dir}${/}sfsb</property>
            <!-- Do not change these -->
            <property name="async">false</property>
            <property name="fetchPersistentState">true</property>
            <property name="purgeOnStartup">true</property>
            <property name="ignoreModifications">false</property>
            <property name="checkCharacterPortability">false</property>
          </bean>
        </list>
      </property>
    </bean>
  </property>

  <!-- EJBs use JBoss Cache eviction -->
  <property name="evictionConfig">
    <bean class="org.jboss.cache.config.EvictionConfig">
      <property name="wakeupInterval">5000</property>
      <!--  Overall default -->
      <property name="defaultEvictionRegionConfig">
        <bean class="org.jboss.cache.config.EvictionRegionConfig">
          <property name="regionName">/</property>
          <property name="evictionAlgorithmConfig">
            <bean class="org.jboss.cache.eviction.NullEvictionAlgorithmConfig"/>
          </property>
        </bean>
      </property>
      <!-- EJB3 integration code will programatically create other regions as beans are deployed -->
    </bean>
  </property>
</bean>
Eviction

The default SFSB cache is configured to support eviction. The EJB3 SFSB container uses the JBoss Cache eviction mechanism to manage SFSB passivation. When beans are deployed, the EJB container will programatically add eviction regions to the cache, one region per bean type.

CacheLoader

A JBoss Cache CacheLoader is also configured; again to support SFSB passivation. When beans are evicted from the cache, the cache loader passivates them to a persistent store; in this case to the file system in the <JBOSS_HOME>/server/production/data/sfsb directory. JBoss Cache supports a variety of different CacheLoader implementations that know how to store data to different persistent store types; see the JBoss Cache documentation for details. However, if you change the CacheLoaderConfiguration, be sure that you do not use a shared store, e.g. a single schema in a shared database. Each node in the cluster must have its own persistent store, otherwise as nodes independently passivate and activate clustered beans, they will corrupt each other's data.

Buddy Replication

Using buddy replication, state is replicated to a configurable number of backup servers in the cluster (a.k.a. buddies), rather than to all servers in the cluster. To enable buddy replication, adjust the following properties in the buddyReplicationConfig property bean:

  • Set enabled to true.
  • Use the buddyPoolName to form logical subgroups of nodes within the cluster. If possible, buddies will be chosen from nodes in the same buddy pool.
  • Adjust the buddyLocatorConfig.numBuddies property to reflect the number of backup nodes to which each node should replicate its state.