Adjusting Application Caches

Jive SBS caches data in order to reduce the number of trips the application makes to its database. The caches improve performance by letting people get things done in the application more quickly. You can adjust the sizes of these caches so that they're best tailored for your community's needs. Adjusting cache settings often is the best way to improve performance.

You'll probably do most of your cache adjustment during the first few months of your deployment, then less frequently as use of the application grows.

Admin Console: System > Settings > Caches

How the Application Uses Caches to Avoid Database Requests

Each of nearly 100 kinds of data is cached in a separately adjustable cache. Each of these caches contains data that the application might need to retrieve and display for users.
You set each cache's maximum size (in memory) based on how much data might need to be cached. If the maximum is reached during use, then the application can no longer store data in the cache and must make queries to the database to retrieve the data the user has requested (for example, by viewing a particular page).
A cache's performance is measured in terms of effectiveness. Effectiveness is a percentage that represents how often the application successfully attempts to retrieve useful data from the cache. When the cache's maximum size is too small, the application must query the database instead.
Default maximum sizes for the caches are usually not appropriate for a new community because circumstances vary so greatly from community to community.
You can adjust cache maximums by clicking the Edit Caches link at the top of the Caches page.

How to Fine Tune Caches

Start by choosing a cache preset that makes sense for your use. When you're editing caches, you can choose one of the presets included with Jive SBS: small, medium, and large (there's also a custom option). Each of these sets all caches to particular default levels. A good rule of thumb is to start with a larger preset, such as medium or large, then adjust downward if it turns out you don't need that much.
Watch for caches with poor effectiveness and adjust those caches by increasing their maximum size. The application signals especially poor effectiveness with a red box, as shown in the following illustration. The columns, left to right, are maximum size, current size, percent used, and effectiveness.
Use the Auto-Refresh interval on the cache performance summary page to have the page refresh regularly with current numbers.
For the first few weeks in production keep a close watch for low cache effectiveness (note the red boxes!). When effectiveness gets too low for a particular cache, increase its maximum size. Here's a suggested schedule:
- Watch effectiveness hourly immediately after launch.
- After caches become stable, watch daily.
- On an ongoing basis, watch weekly.
In general, try to keep effectiveness over 90 percent.
Look for caches you can set to very low levels, such as those for features you're not using. For example, if you're not using blogs, you might set blog-related caches to 0.5MB. (Don't set it to 0, though, which effectively sets it to "unlimited.") This frees up overall memory you can use for other cache maximums.
Ensure that the total of cache maximums doesn't exceed one-third of the maximum memory you've assigned to the JVM. The total is shown at the bottom of the cache summary list, while your total Java memory is shown at the very bottom of the page where the Java memory monitor is displayed. See below for more information on adjusting the JVM settings.