The Job Processes Busy alarm occurs when all, or most, job queue processes are busy.
Job queue processes are responsible for executing batch jobs queued via the DBMS_JOBS package. If all or most of these job queue processes are busy, it may indicate a bottleneck in batch processing.
See the Activity | Server Page to see the precise load on job queue processes.
Tip: If job queue processes are not keeping up with demand, consider increasing the number of job queue processes via the JOB_QUEUE_PROCESSES parameter.