Identifying possible impacts of DynaCache
In general, DynaCache will improve system performance, but it might also have side effects:
| JVM heap and fragmentation |
DynaCache uses JVM heap to store cached objects. A large number of cached objects occupy a large portion of the JVM heap and contribute to heap fragmentation. During benchmark-creation tests, we need to monitor the JVM usage in relation to the number of DynaCache entries, adjusting the number of entries as necessary.
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| DynaCache overhead |
Cached object search and invalidation use resources. If the cache hit ratio is too low or the cache refresh rate is too high, the resulting overhead might be significant. It is important to keep the hit ratio high by adjusting the number of DynaCache entries as well as the number of cacheable objects.
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| Time required to stop the WebSphere Commerce server with the "Flush to disk" option enabled |
DynaCache contents can be flushed to a file on a disk when the WebSphere Commerce server is shut down. If the cache size is big, the shutdown may take a long time. On the other hand, if we disable the "Flush to disk" option, the cached objects will be lost and will need to be regenerated and cached after the WebSphere Commerce server is restarted. Several experiments may be necessary to establish the optimal strategy for your site.