Use this task to interpret
cache monitor statistics to
improve the performance of the dynamic cache service.
Before you begin
Verify that dynamic
cache is enabled and that the cache monitor
application is installed on your application server.
About this task
Refer to the Displaying cache information topic for information about how to configure
the cache monitor application.
Use the cache monitor to watch cache hits versus misses. By
comparing these two values, you can determine how much dynamic cache is helping your application,
and if you can take any additional steps to further improve performance and decrease the cost of
processing for your application server.
Procedure
-
Start cache monitor and click on Cache Statistics.
You can view the following cache statistics:
Cache statistic |
Description |
Cache Size |
The maximum number of entries that the cache can hold. |
Used Entries |
The number
of cache entries used. |
Cache Hits |
The number of request responses that are served from the
cache. |
Cache Misses |
The
number of request responses that are cacheable but cannot
be served from the cache. |
LRU Evictions |
The number of cache entries removed to make room for new
cache entries. |
Explicit Removals |
The number of cache entries removed or invalidated from the
cache based on cache policies or were deleted from the cache through
the cache monitor. |
- You can also view the following cache configuration values:
Cache configuration value |
Description |
Default priority |
Specifies the default priority for all cache entries. Lower priority entries are moved from
the cache before higher priority entries when the cache is full. You can specify the priority for
individual cache entries in the cache policy. |
Servlet Caching Enabled |
If servlet caching is enabled, results from servlets and JavaServer Pages (JSP) files are
cached. Refer to the Configuring servlet caching topic for more information about how to configure
servlet caching. |
Disk Offload Enabled |
Specifies if entries that are being removed from the cache are saved to disk. Refer to the
Configuring dynamic cache disk offload topic for more information. |
- Wait for the application
server to add data to the cache.
You want the number of
used cache entries in the cache monitor
to be as high as it can go. When the number of used entries is at
its highest, the cache can serve responses to as many requests as
possible.
- When the cache has a high number
of used entries, reset
the statistics. Watch the number of cache hits versus cache misses.
If the number of hits is far greater than the number of misses,
your cache configuration is optimal. You do not need to take any further
actions. If you find a higher number of misses with a lower number
of hits, the application server is working hard to generate responses
instead of serving the request using a cached value. The application
server might be making database queries, or running logic to respond
to the requests.
- If you have a large number
of cache misses, increase the
number of cache hits by improving the probability that a request can
be served from the cache.
To improve the number of cache hits, you can increase the cache size or configure additional
cache policies. Refer to the Dynamic cache service settings topic for information about how to
increase the cache size and the Configuring cacheable objects with the cachespec.xml file topic for
information about configuring cache policies.
Results
By using the cache monitor application, you
optimized the
performance of the dynamic cache service.
What to do next
Refer to the Task overview: Using the dynamic cache service to improve performance topic for more
information about the dynamic cache.