BSM support tip: "Number of files for PageCacheDeadLetter objects" in RUM engine is increasing
Sometimes in the Real User Monitor (RUM) web console the RUM engine shows warnings. Following the worst status rule we can dig down only to find that the problem is within the DBCache section and more specifically the metric "Number of files for PageCacheDeadLetter objects"
This usually occurs if for any reason the RUM engine cannot insert the samples in its database. In this case we can check the common.cache.log .
2015-02-04 01:42:42,283 [Timer-36] (Cache.java:353 WARN - Some objects could not be saved to the data base. [SessionCache
… Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Deadlock found when trying to get lock; try restarting transaction
In this case we have two options to remove the warnings in the web console:
1. Re-insert the samples:
- Stop the RUM engine;
- Backup the folders <HPRUM>\cache\cache\PageCacheDeadLetter and <HPRUM>\persistency\cache\PageCache on your desktop. Do not keep the backup in the original location;\
- Copy the content from <HPRUM>\cache\cache\PageCacheDeadLetter, and paste it in the <HPRUM>\persistency\cache\PageCache folder;
- Start the RUM engine.
2. If the non-inserted samples are not required they can be safely removed by deleting the content of <HPRUM>\cache\cache\PageCacheDeadLetter and restarting the engine.