Find code clearing Sitecore caches


Description

Sitecore Platform ships with multiple levels of caches in order to maximize the performance. The item fetch operation is backed by the following multiple caching layers by default:

The platform caching layer logic is located under the Sitecore.Caching namespace, while main cache-related logic is exposed by the Sitecore.Abstractions.BaseCacheManager contract or the static Sitecore.Caching.CacheManager class. The ClearAllCaches() API provided by the CacheManager leads to clearing all previously registered caches, likely causing a temporary performance drop. The corresponding log entry is written into Sitecore log files:

WARN All caches have been cleared. This can decrease performance considerably.

The Sitecore.Caching.ICacheInfo interface defines the Clear() API method that allows clearing caches on a more granular level as well.

Sitecore Platform provides diagnostic capabilities to locate the cause for cache clearing.

Solution

To configure the cache cleanup mechanism to write diagnostic messages:

  1. Add the following setting into the Sitecore configuration: 
    <setting name="Caching.DebugEnabled" value="true" />
  2. Configure Sitecore logger to write diagnostic messages: 
    <root>
  <priority value="DEBUG" />
</root>

You can find the debug log entry with the cache cleanup call stack:

6080 2018:07:04 16:08:22 DEBUG The 'web[blobIDs]' cache has been cleared.
Entries removed: 0
StackTrace:
   at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo)
   at System.Environment.get_StackTrace()
   at Sitecore.Caching.Generics.Cache`1.DoLogDebugMessage(String messagePrefix, String messageBody, Boolean ensureDebugEnabled) in
   at Sitecore.Caching.Generics.Cache`1.Clear()
   at Sitecore.sitecore.admin.CacheAdmin.ClearAllButtonClick(Object sender, EventArgs arguments)
   at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
   at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)

When the investigation is over, revert the configuration change.