The Server Administration app’s Resources tab contains several server wide actions that an administrator can execute. These include the following items:
Run the garbage collector: Tells the JVM to free memory by running the garbage collector.
Generate a thread dump: Generates a thread dump for later scrutiny to
determine the presence and location of any deadlocks. Useful during
performance testing, but you must add a logger category for
and set it to
INFO before executing.
Clear content cached by this VM: Clears content stored in the local cache. Only local JVM scope Ehcache content is cleared, not clustered Ehcache. 1
Clear content cached across the cluster: Clears the content of the entire clustered Ehcache. 1
Clear the database cache: Clears the database cache. Does not clear any Ehcache content except database results at the persistence layer. 1
Clear the direct servlet cache: Clears the direct servlet cache. In case emergency fixes must be applied, this action allows an administrator to clear out the cache manually to force JSPs to reload.
The direct servlet context optimizes JSP serving performance by caching and
accessing the generated servlets directly instead of accessing them over the
application server’s dispatcher chain. This function is only suitable for
cases where no filter is required for the JSPs; it should be enabled for
production mode to improve performance, but disabled for development mode to
allow JSP servlets to be reloaded on the fly. See the Direct Servlet Context
section of the
portal.properties file for details. 1
Verify database tables of all plugins: Checks all tables against their indexes for data retrieval accuracy.
Verify membership policies: Checks that existing Site membership policies were correctly applied and automatically makes updates. If the Liferay DXP database is changed manually or is hacked—resulting in a user assigned to a Site in violation of a site membership policy—this action triggers the verification methods of all implemented Site membership policies. Changes are automatically made to any memberships in violation.
Reset preview and thumbnail files for Documents and Media: Regenerates previews of each item in your Documents and Media libraries.
Clean up permissions: Removes permissions on the Guest, User, and Power User Roles to simplify the management of User Customizable Pages. The Add To Page permission is removed from the Guest and User Roles for all portlets, and is reduced in scope for Power Users from portal-wide to User Personal Site.
Clean up portlet preferences: This action cleans up database entries if portlet preferences become orphaned in the Liferay DXP database.
 Caching occurs at multiple levels. Some higher caching layers aren’t aware of lower caching layers. Always clear the cache at the lowest (most granular) layer possible, even if you’ve already cleared a higher level cache.