Symptoms

K2 service stop responding from time to time during the business hours and has to be killed and started again. In addition to this you may observe "System.OutOfMemoryException" in K2 host server logs on Service Instance related operations.
 

Diagnoses

One of the possible causes of such behavior is large volume of K2 SmartObjects logs. In case this logging was enabled for prolonged period of time and especially with overwrite option disabled these logs files can reach huge size leading to "System.OutOfMemoryException" for K2 host server. For example after running for some times with this logging enabled with no overwrite option you may see sizes such as 2GB for "servicepackagein.log" and 9GB for "servicepackageout.log"
K2 SmartObjects logging should be enabled only for short period of time for troubleshooting purposes. It is not recommended to leave it enabled for prolonged period of time as it produce high volume of output and adds unnecessary extra load on K2 server. Whenever you using this logging it is recommended to have overwrite option enabled (so that logs are starting from scratch upon each K2 service restart).
 

Resolution

Remove large SmartObjects log files and make sure that you enable this logging only temporarily for troubleshooting purposes, do not leave it enabled without necessity. Use overwrite option for SmartObjects logs to prevent excessively large volume of logs.