The Process Engine is responsible for executing all the various processes defined in the system. Its status can be determined by navigating to Administration -> Process Engine page. Red colour against the Status column indicates that the Process Engine is down. When the Process Engine is down, a BG restart can get it running again.
But an issue has been noticed where the Process Engine goes down again after a BG restart.
Latest Version Tested: 15.7.1
The following sample logging can be noticed in the app-ca.log and bg-ca.log.
Error message: [CA Clarity] [Oracle JDBC Driver] [Oracle] ORA-01555: too old snapshot: rollback segment number 29 with name "_SYSSMU29_2781180501 $" too small
This indicates a problem with the Database. Specifically with Process related tables.
Engage a DBA to check for fragmentation in the BPM_ERRORS table first, since this table can undergo multiple deletes and inserts. Other process tables (starting with BPM_ ) will also need to be checked. It would also have to be determined which queries etc. are holding all the UNDO space in the DB.
Once these aspects are determined, the DBA will have to take appropriate action such as de-fragmentation etc. to get the DB in order.