Cache warning messages in catalina.out in debian xwiki-tomcat8-* packages

Although closed, the following issue XWIKI-15756 still occurs in 11.1 and 10.11 debian packaging. 

I noted mass-spewage of errors in /var/log/tomcat8/catalina.out – many repeated lines like:

"Unable to add the resource at [/WEB-INF/lib/xwiki-platform-container-servlet-11.1.xed] to the cache for web application [/xwiki] because there was insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache"

 Note that /usr/lib/xwiki/META-INF/context.xml has

<!-- We need to set the resource cache size since the default (10K) is too small for loading all XWiki resources at once -->
 <Resources cacheMaxSize="20480" />

however it's not clear that gets loaded with current config (it doesn't):

Looking at logs it loads /etc/tomcat8/Catalina/localhost/xwiki.xml

08-Mar-2019 00:20:20.169 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDescriptor Deploying configuration descriptor [/etc/tomcat8/Catalina/localhost/xwiki.xml]

where in /etc/tomcat8/Catalina/localhost:

lrwxrwxrwx 1 root tomcat8 28 Feb 25 09:41 xwiki.xml -> /etc/xwiki/xwikitomcat8.xml

So I did following, also integrating suggestions from
https://stackoverflow.com/questions/26893297/tomcat-8-throwing-org-apache-catalina-webresources-cache-getresource-unable-to
and specifically from
http://jira.xwiki.org/browse/XWIKI-15756?focusedCommentId=100290&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-100290

• added my changes to /etc/tomcat8/context.xml (just like vmassol suggests above)
• and the errors still happen....
• tried again increasing cache size to 50K...
• and it still happens....

So I went back and did two things:

(1) set /etc/xwiki/xwiki.cfg per Admin.CheckXWikiConfig suggestion:
xwiki.store.cache.capacity=1000

Now CheckXWikiConfig admin-tools app reports:

Cache configuration
This lists the main cache settings. An XWiki instance is set by default to 100 for the main cache which is ok for a small instance. A large one with at least 1000 (large XE) to 3000 (very large XE or large XEM).

Store Page Cache Capacity : 1000
Store Page Cache in Use : 379

(2) added to /etc/xwiki/xwiki-tomcat8.xml

• --> note, put everything in one "Resources" clause, wondering if different resource clauses are overriding previously defined ones instead of additive?
• (NB: this may be reason for OP having XWiki not startup at all as I had similar issues with adding two "Resources" entries within one context in early attempts).
• --> e.g. there is a setting to "20,480" in the package-installed /usr/lib/xwiki/META-INF/context.xml and a separate one ("<Resources allowLinking="true".../>") in xwiki-tomcat8.xml ?
• --> per tomcat8 docs, set cacheObjectMaxSize to cacheMaxSize/20 ... and tripled orig size of cacheMaxSize from default 10240 (10Mb)
  to 30Mb (30720), raising cacheObjectMaxSize from default 512 (512 kilobytes) to 1536 (1.5 megabytes). 

<Context path="/xwiki" docBase="/usr/lib/xwiki" privileged="true" crossContext="true">
  <!-- NPM: fix /var/log/tomcat8/catalina.out errors (See http://jira.xwiki.org/browse/XWIKI-15756?focusedCommentId=100290&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-100290 )
       "Unable to add the resource at ... to the cache for web application /xwiki because there was insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache" 
       /usr/lib/xwiki/META-INF/context.xml's cacheMaxSize="20480" does not
       appear to be applied in the case of this xwiki apt/debian setup. -->
  <!-- Make symlinks work in Tomcat -->
  <Resources allowLinking="true" cachingAllowed="true" cacheMaxSize="30720" cacheObjectMaxSize="1536" />

  <!-- Disable JAR scanning since Xwiki does not need that -->
  <JarScanner scanClassPath="false"> <JarScanFilter defaultTldScan="false"/> </JarScanner>
</Context>