Production environments

Operating WebSphere Commerce in a production environment introduces complexities. For example, accessing cache entries that have been offloaded from memory introduces overhead associated with reading from and writing to the disk. Invalidating these entries is time consuming. Therefore, it is important to tune the cache using the available properties. By setting these values to the appropriate values, you improve the cache invalidation process.

Tuning parameters

Each WebSphere Application Server process has several parameters influencing application performance. By changing tuning parameters we can configure and tune applications.

First review the tuning parameter hot list, which is a subset of the tuning parameter index. These parameters have an important impact on performance. Because these parameters are application dependent, the parameter settings for specific applications and environments can vary.

Each parameter in the tuning parameter index links to information that explains the parameter, provides reasons to adjust the parameter, how to view or set the parameter, as well as default and recommended values.

Delay offload entries limit

The htodDelayOffloadEntriesLimit property specifies the number of different cache IDs that we can save in memory for the dependency ID and template buffers. Consider increasing this value if you have a lot of memory in your server and we want to increase the performance of your disk cache.

The value of this parameter indicates how many items the index will hold. For example, a value of 1000 means that each dependency ID or template ID can have up to 1000 different cache IDs in memory.

The application of this setting to WebSphere Commerce is that there will be an index of this size on disk. We can access the indexed entries on the disk through the use of the index, without having to look for them. See Java virtual machine cache settings.

Note: Delay offload entries limit does not need to be set when the recommended High performance and high memory usage setting is specified.

Delay offload

Another parameter that we can set is htodDelayOffload (com.ibm.ws.cache.CacheConfig.htodDelayOffload). Having this property set to true indicates that the Application Server can use extra memory buffers for the dependency IDs and templates. This delays disk offload and minimizes the input and output operations to the disk.

Note: The default value for this parameter is true. There is no need to set it to true, only to ensure that it has not been set to false.

Cleanup frequency

Use this property to change the amount of time between disk cache cleanups.

If you have thousands of cache entries that might expire within one or two hours, the files that are in the disk cache can grow large and become unmanageable. Use the com.ibm.ws.cache.CacheConfig.htodCleanupFrequency custom property to change the time interval between disk cache cleanups. See Java virtual machine cache settings

Note: Cleanup frequency does not need to be set when the recommended High performance and high memory usage setting is specified.

Flush to disk

When the flushToDiskOnStop property is set to true, in-memory cached objects are saved to disk when the server is stopped.

Related tasks
Enable the dynamic cache service and servlet caching