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
See Displaying cache information
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. See Configuring servlet caching
for
more information. |
Disk Offload Enabled |
Specifies if entries that are being removed from the cache are saved
to disk. See Configuring dynamic cache disk offload
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.
See Dynamic cache service settings
to
increase the cache size and Configuring cacheable objects with the cachespec.xml file
for
information about configuring cache policies.
Results
By using the cache monitor application, you optimized the performance
of the dynamic cache service.