With a fresh Sitecore 9.1 installation, we were seeing thousands of these errors in the logs:

WARN AccessResultCache cache is cleared by Sitecore.Caching.Generics.Cache`1+DefaultScavengeStrategy[[Sitecore.Caching.AccessResultCacheKey, Sitecore.Kernel, Version=12.0.0.0, Culture=neutral, PublicKeyToken=null]] strategy. Cache running size was 9 MB.

As mentioned in the warning, the default cache size was used: "Cache running size was 9 MB". That was clearly too small for our environments, so cache size tuning was needed.

The related setting is the following:

<setting name="Caching.AccessResultCacheSize" value="9MB" />

So we created a patch file to increase the size to 200MB:

<?xml version="1.0"?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:role="http://www.sitecore.net/xmlconfig/role/" xmlns:set="http://www.sitecore.net/xmlconfig/set/">
  <sitecore role:require="Standalone or ContentDelivery or ContentManagement">
      <settings>
        <setting name="Caching.AccessResultCacheSize" value="200MB" />
      </settings>
    </sitecore>
</configuration>

Deployed the patch to the app services and the errors have disappeared, and there was also a noticable performance increase.

Do you have any Sitecore tips or tricks to share? Please send them along!

Regards,
David