Confluence Docs 3.0 : Cache Statistics This page last changed on May 31, 2009 by ggaskell. Confluence provides statistics about its internal caches that allow you to track the size and hit ratio of each cache and tune it for better performance (if necessary). See Performance Tuning for more information. #### Configurable Caches System administrators can change the sizes of Confluence's internal caches through the Administration Console and these changes will take effect without the need to first shut down and then restart Confluence. The maximum number of units for any of the defined cache regions can be adjusted individually. Note that larger cache sizes will require more memory at runtime, so you should review the memory allocation of the Confluence Java process and the physical memory available on your server. #### Viewing Cache Statistics and Modifying Cache Sizes To view the cache statistics: Go to the Confluence 'Administration Console'. To do this: Open the 'Browse' menu and select 'Confluence Admin'. The 'Administration Console' view will open. Click 'Cache Statistics' in the left-hand panel. There you will find a list of all objects cached within Confluence. Click the 'Advanced' tab for more detail. Below is an example for one of the most frequently used caches, the 'Content Object' cache.
Name | Percent Used | Effectiveness | Objects / Size | Hit / Miss / Expiry | Adjust Size | Flush
--- | --- | --- | --- | --- | --- | ---
Content Object | 80% | 73% | 4023 / 5000 | 374550 / 140460 / 55044 | Adjust Size | Flush
About the generated numbers:
Percent Used: | =(Objects)/(Size)
Effectiveness: | =(Hits)/(Hits + Misses)
Objects / Size: | The number of entries in the cache / the number of total possible entries allowed (configurable).
Hit / Miss / Expiry: | The number of reads accessing cache where required content was found / the number of reads accessing cache where required content was not found / the number of objects evicted from the cache.
Adjust Size | Use this option to specify a different maximum cache size. Enter a new cache size and click the 'Adjust Size' button to set it.
Flush: | Flushes the cache.
For instance, to calculate Percent Used:
    Percent Used = Objects / Size

    Percent Used = 4023/5000 = 80%
To calculate Effectiveness:
    Effectiveness = (Hits)/(Hits + Misses)

    Effectiveness = 374550 / (374550 + 140460) = 73%
| The clustered versions of Confluence use distributed cache called Tangosol Coherence.
#### Additional Notes about Configurable Caches Changes to cache size configurations persist across confluence restarts as they are saved in the `<confluence-home>/config/confluence-coherence-cache-config.xml` file (or `<confluence-home>/config/confluence-coherence-cache-config-clustered.xml` for a clustered instance). In most cases, a Confluence administrator will never need to know about these files. However, if it is necessary to tune cache options other than the maximum cache size, this can be done by manually editing these files. See Cache Performance Tuning for details.
| Important note about clustered Confluence installations The cache configuration file is stored in a home directory of each cluster node. When a Confluence administrator changes a cache size, all running cluster nodes will automatically update their own configuration files in their respective home directories. However, if a cluster node is not running when an administrator adjusts a cache size, the `/config/confluence-coherence-cache-config-clustered.xml` file in its home directory will not be updated. Since cluster caches are configured by the first node to start, if a node with an outdated cache configuration is the first to start up, the whole cluster would end up using the configuration of that node. However, copying this file from one node to another would resolve this issue.
#### Performance Tuning If you need to tune your application when under high usage, you may like to review this document for suggestions. ##### RELATED TOPICS
Viewing System Information
Cache Performance Tuning for Specific Problems
Cache Performance Tuning
Cache Statistics
Confluence Cache Schemes
Viewing and Editing License Details

Document generated by Confluence on Nov 05, 2009 23:26