Debugging cache

If you encounter unexpected caching behavior or any problems related to the cache, you can use the system’s debugging functionality to:

• Check the exact content of the application’s cache
• Monitor caching operations for web requests

You can access the system’s debugging interface through the Debug application.

Viewing the stored cache items

On the Cache items tab, you can see which Data items and Dummy keys (cache dependencies) are currently stored in the system’s server-side cache.

You can delete individual cache keys by clicking Delete () next to the corresponding items. To remove all items from the cache, click Clear cache.

Clicking View () next to a cache key opens a new window showing detailed information about the cached object:

• Key - the key under which the object is stored in the cache.
• Expiration - date and time when the cache item will expire (i.e. will be removed from the cache).
• Priority - Kentico uses two priorities for cache items: High and NotRemovable (will not be deleted from the cache as the server frees system memory).
• Dependencies - list of dummy keys on which the cache item depends. The system removes the cache item if any of the dummy keys are touched (modified).
• Object type - the type of the cached item.
• Fields - the fields storing the actual data of the cached item (depend on the item’s object type).

If you need even more information about a cached object, click Debug () next to the item in the list of cache keys. Debugging cache keys allows you to browse the full system data of the given object, including all properties, variables and related objects.

Debugging cache access

The cache access debug allows you to view the cache operations that the system performs for individual web requests (adding items to the cache, loading data from the cache).

Enabling the cache access debug

To use cache access debugging, you need to adjust the settings in Settings -> System -> Debug:

Monitoring cache access

To view which cache operations the system performed for recent web requests:

1. Open the Debug application.
2. Select the Cache access tab.

You can see the URLs of web requests and the time when the system processed the requests. The table below each request contains the cache items that the system accessed during the request. The table provides the following information for each cache item:

• The type of Access (Get, Add)

• The name of the accessed Cache key

• The cache item’s dependencies

• The object type and size of the cached Data

• The Context in which the cache item was accessed (API method)

  • Click on the method to see the stack trace of the cache access
  • If you enable the Show complete context option at the top of the interface, the stack trace is displayed for all cache items.

Click Clear debug log to remove all records in the cache access debug. To remove the actual data from the system’s cache, click Clear cache.

Clicking View () next to a cache key opens a new window showing detailed information about the cached object:

• Key - the key under which the object is stored in the cache
• Expiration - date and time when the cache item will expire (i.e. will be removed from the cache)
• Priority - Kentico uses two priorities for cache items: High and NotRemovable (will not be deleted from the cache as the server frees system memory)
• Dependencies - list of dummy keys on which the cache item depends. The system removes the cache item if any of the dummy keys are touched (modified).
• Object type - the type of the cached item
• Fields - the fields storing the actual cached data (different for each object type)