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Java virtual machine cache settings

Use this page to set JVM custom properties to maintain cache entries that are saved to disk.

 

Example

You can set the custom properties globally to affect all cache instances, or you can set the custom property on a single cache instance. In most cases, set the properties on the individual cache instances. To set the custom properties on the default cache instance, use the global option. If you set the same property both globally and on a cache instance, the value that is set on the cache instance overrides the global value.

To configure the custom properties on a single object cache instance or servlet cache instance, perform the following steps:

  1. In the console, click one of the following paths:

    • To configure a servlet cache instance, click Resources > Cache instances > Servlet cache instances > servlet_cache_instance_name > Custom properties > New.

    • To configure an object cache instance, click Resources > Cache instances > Object cache instances > object_cache_instance_name > Custom properties > New.

  2. Type the name of the custom property. When configuring these custom properties on a single cache instance, you do not use the full property path. For example, type explictBufferLimitOnStop to configure the com.ibm.ws.cache.CacheConfig.explictBufferLimitOnStop custom property.

  3. Type a valid value for the property in the Value field.

  4. Save the property and restart WAS.

To configure the custom property globally across all configured cache instances, perform the following steps:

  1. In the console, click Servers > Application servers > server > Java and process management > Process definition > Java virtual machine > Custom properties > New.

  2. Type the name of the custom property (for example, com.ibm.ws.cache.CacheConfig.explictBufferLimitOnStop) in the Name field.

  3. Type a valid value for the property in the Value field.

  4. Save the property and restart WAS.

 

com.ibm.ws.cache.CacheConfig.htodCleanupFrequency

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

Setting this custom property manually is deprecated for V6.1. Therefore, you should use the console to set this property. To set this property in the console, click one of the following paths:

Then:

  1. Under Disk Cache setting, select the Enable disk offload field if it is not already selected.

  2. Under Performance Settings, select Balanced performance and balanced memory usage or Custom.

  3. In the Disk cache cleanup frequency field, specify an appropriate length of time, in minutes.

By default, the disk cache cleanup is scheduled to run at midnight to remove expired cache entries and cache entries that have not been accessed in the past 24 hours. However, 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 cleanup.

Units minutes

For example, a value of 60 means 60 minutes between each disk cache cleanup.

Default 0

The disk cache cleanup occurs at midnight every 24 hours.

 

com.ibm.ws.cache.CacheConfig.htodDelayOffloadEntriesLimit

Use this property to specify the number of different cache IDs that can be saved in memory for the dependency ID and template buffers. Consider increasing this value if you have a lot of memory in your server and you want to increase the performance of your disk cache.

Setting this custom property manually is deprecated for V6.1. Therefore, you should use the console to set this property. To set this property in the console, click one of the following paths:

Then:

  1. Under Disk Cache setting, select the Enable disk offload field, if it is not already selected.

  2. Under Disk Cache settings, select Limit disk cache size in entries, if it is not already selected.

  3. In the Disk cache size field, specify the number of cache IDs that can be saved in memory for the dependency ID and template buffers.

Units number of cache IDs

For example, a value of 1000 means that each dependency ID or template ID can have up to 1000 different cache IDs in memory.

Default 1000
Minimum 100

 

Tune the delay offload function

Use these properties to tune the delay offload function for the disk cache.

Setting these custom properties manually is deprecated for WAS V6.1. Use the console to set these properties. The individual property descriptions include information on how to use the console to set these properties.

The delay offload function uses extra memory buffers for dependency IDs and templates to delay the disk offload and minimize the input and output operations. However, if most of your cache IDs are longer than 100 bytes, the delay offload function might use too much memory. Use any combination of the following properties to tune the configuration:

 

com.ibm.ws.cache.CacheConfig.explictBufferLimitOnStop

Use this custom property when the flush-to-disk-on-stop feature is enabled. When the server is stopping, offloads are limited to the value specified for this property, pending removal of entries in the explicit invalidation buffer. If this property is set to 0, there is no limit to the number of offloads that can occur. Only positive integers are accepted as values for this property. If the number of entries in the explicit invalidation buffer is greater then the specified limit, all of the disk files for this specified cache instance are deleted after the server stops.

You cannot use the console to set this property.

 

Related tasks


Configure dynamic cache disk offload

 

Related Reference


Troubleshooting tips for the dynamic cache service

 

Reference topic