The Enterprise Manager Job System is an OMS subsystem and includes a Job Scheduler and Job Workers. In turn, the Job Scheduler consists of two components: the Job Step Scheduler and the Job Dispatcher. In addition to user-submitted jobs, the majority of the background tasks in Enterprise Manager are run via a series of jobs. Typical tasks carried out by these jobs are calculating the availability of composite targets and sending notifications.

Performance of the Job System relies on numerous components to perform optimally. Job Diagnostics consolidates performance information pertaining to these components into intuitive dashboards for easy comparison and analysis. The primary components of the Job System are shown in the following illustration.

Job System Components Used by Job Diagnostics

• Job Step Scheduler – The Job Step Scheduler is a global component so there is only one per Enterprise Manager environment. It is scheduled to run by the DBMS Scheduler. The primary purpose of this component is to mark steps ready for the dispatcher to execute.

• Job Dispatcher - The Enterprise Manager Job System also has a notion of a short jobs (jobs that complete quickly) and long jobs (jobs that run a long time) and has separate worker pools in the OMS (not in the database as with the job workers) to handle those requests. The Job Dispatcher runs locally on each OMS and its purpose is to dispatch the jobs found by the Job Step Scheduler to the Job Workers. If the dispatcher cannot keep up with the work in the queue, the backlog increases. This is not a problem as long as the backlog is temporary. If it is not, then either the dispatcher is not able to keep up with the amount of work which could mean adding another OMS server or there is a problem with the Job Workers and they are not able to accept the work from the dispatcher.

• Job Workers – Job Workers take work for a given job step from the Job Dispatcher and process it. This can happen while holding a thread for steps that do processing in java, by contacting the repository for those that use SQL, or by contacting the agent for those that run remotely. If Job Workers are always busy and never free, then capacity needs to be added either via another OMS server or by increasing the number of Job Workers and potentially increasing the number of DB connections (each Job Worker takes a connection to the database).