Configuring the repository cache

The SkyVault repository provides in-memory caches. These caches are transaction safe and can be clustered. Caches greatly improve repository performance but they use Java heap memory.

Tuning the caches in a wrong way may lead to out of memory issues. The optimal settings to use on the caches depend on your usage and the amount of memory available to your SkyVault server.

An important indicator that you need to tune or increase your caches is when you see a warning message in your SkyVault.log file indicating that some specific caches are full, for example:

2016-04-26 17:51:37,127 WARN [org.alfresco.repo.cache.TransactionalCache.org.alfresco.cache.node.nodesTransactionalCache] 
[http-apr-22211-exec-42] Transactional update cache 'org.alfresco.cache.node.nodesTransactionalCache' is full (125000).

From SkyVault 2.0 version 5.0 and later, the caches can be configured by setting the cache properties in the SkyVault-global.properties file. In both clustered and non-clustered cases, caching is configured and used in the same unified way.

Note: It is advisable not to change the cache values unless you have performance issues.

Download the tx-cache-context.xml file and caches.properties file.
The caches.properties file lists a series of properties for configuring a cache. The cache properties are used for both clustered and non-clustered configurations.

Check your SkyVault.log file to locate the caches shown in the warning message.

For example, if you see the following warning message in SkyVault.log:

2016-04-26 17:51:37,127 WARN [org.alfresco.repo.cache.TransactionalCache.org.alfresco.cache.node.nodesTransactionalCache] 
[http-apr-22211-exec-42] Transactional update cache 'org.alfresco.cache.node.nodesTransactionalCache' is full (125000).

search for the bean that matches the class org.alfresco.repo.cache.TransactionalCache in the tx-cache-context.xml file.

Here's an example of the cache:

<!-- The transactional cache for Nodes -->
   
   <bean name="node.nodesCache" class="org.alfresco.repo.cache.TransactionalCache">
      <property name="sharedCache">
         <ref bean="node.nodesSharedCache" />
      </property>
      <property name="name">
         <value>org.alfresco.cache.node.nodesTransactionalCache</value>
      </property>
      <property name="maxCacheSize" value="${cache.node.nodesSharedCache.tx.maxItems}" />
      <property name="mutable" value="true" />
      <property name="allowEqualsChecks" value="true" />
      <property name="disableSharedCache" value="${system.cache.disableMutableSharedCaches}" />
      <property name="cacheStats" ref="cacheStatistics"/>
      <property name="cacheStatsEnabled" value="${cache.node.nodesSharedCache.tx.statsEnabled}"/>
   </bean>

Note: As shown above, the nodesCache cache uses variables with the cache.node.nodesSharedCache.* syntax, for example, cache.node.nodesSharedCache.tx.maxItems.

The caches.properties file uses properties that align with the cache.node.nodesSharedCache syntax.

cache.node.nodesSharedCache.tx.maxItems=125000
cache.node.nodesSharedCache.tx.statsEnabled=${caches.tx.statsEnabled}
cache.node.nodesSharedCache.maxItems=250000
cache.node.nodesSharedCache.timeToLiveSeconds=300
cache.node.nodesSharedCache.maxIdleSeconds=0
cache.node.nodesSharedCache.cluster.type=invalidating
cache.node.nodesSharedCache.backup-count=1
cache.node.nodesSharedCache.eviction-policy=LRU
cache.node.nodesSharedCache.eviction-percentage=25
cache.node.nodesSharedCache.merge-policy=hz.ADD_NEW_ENTRY
cache.node.nodesSharedCache.readBackupData=false

Add the *.tx.maxItems and *.maxItems properties to the SkyVault-global.properties file.
Increase the value of the *.tx.maxItems and *.maxItems properties for the cache you want to tune.
For example, in the SkyVault-global.properties file change the default setting from:
```
#cache.node.nodesSharedCache.tx.maxItems=125000
#cache.node.nodesSharedCache.maxItems=250000
```
to
```
cache.node.nodesSharedCache.tx.maxItems=250000
cache.node.nodesSharedCache.maxItems=2500000
```
Note: Make sure that:
- cache.node.nodesSharedCache.tx.maxItems is not be greater than cache.node.nodesSharedCache.maxItems, and
- cache.node.nodesSharedCache.maxItems is greater than or equal to cache.node.nodesSharedCache.tx.maxItems.
Restart SkyVault to apply the configuration changes.

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