Message "The background cache eviction process was unable to free [10] percent of the cache for Context" filling Nolio log files.

Document ID : KB000016503
Last Modified Date : 16/01/2019
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Introduction:
There are frequent observation of the error in Nolio Automation Center(NAC) a.k.a Data Management Server(DMS) and Execution Servers.

ERROR:
INFO: The background cache eviction process was unable to free [10] percent of the cache for Context [/nolio-app] - consider increasing the maximum size of the cache. After eviction approximately [177,273] KB of data remained in the cache. 

The frequent emission of these log message is causing below issues:

  1. With frequent repetition of error message, logs are getting filled quickly
  2. It raises an alarm in log monitoring system and tools. It is not deterministic if this is a genuine or false alarm, as the error message is recorded at INFO level.
Question:
  1. What does this log message been raised?
  2. How can the error be subside?
Environment:
CA Release Automation(CARA) version:  6.4,6.5 or higher
Answer:
1: What does the log message is referring to?
 
The problem is caused by Tomcat being unable to reach its target cache size due to cache entries that are less than the TTL of those entries. As Tomcat didn't have enough cache entries that it could expire, because the entries in cache are afresh, it couldn't free enough cache and thus outputs warnings.
The problem didn't appear in Tomcat 7 because Tomcat 7 simply didn't output warnings in this situation. With upgrade of Tomcat to version 8 CARA  started to log this message as we are using the default cache size.
 
2: How can the error be normalize or can be subside?

The maximum of static resource cache (all resources in total) is by default 10240 kbyte (10 mbyte).  The cache size can be increased from default value by adding following line to the RA_HOME\conf\context.xml  file, at end of the file just before the </Context> 

<Resources cachingAllowed="true" cacheMaxSize="100000" /> 
# This will increase the cache size  to 100Mb. 

Note:

  1. You need to restart the Release automation Tomcat service.