448.Which of the following tasks is not performed by the job coordinator?
A. Update job log when a job completes
B. Spawn and remove job slaves
C. Write/read job info to/from memory cache
D. Query job table
E. Pass job information to job slaves
Answer: A

http://docs.oracle.com/cd/E18283_01/server.112/e17120/schedover004.htm
http://www.aiotestking.com/oracle/which-of-the-following-tasks-is-not-performed-by-the-job-coordinator/

The Job Coordinator

The job coordinator background process (cjqNNN) is automatically started and stopped on an as-needed basis. At database startup, the job coordinator is not started, but the database does monitor whether there are any jobs to be executed, or windows to be opened in the near future. If so, it starts the coordinator.

As long as there are jobs or windows running, the coordinator continues to run. After there has been a certain period of Scheduler inactivity and there are no jobs or windows scheduled in the near future, the coordinator is automatically stopped.

When the database determines whether or not to start the job coordinator, it takes the service affinity of jobs into account. For example, if there is only one job scheduled in the near future and this job belongs to a job class that has service affinity for only two out of the four Oracle RAC instances, only the job coordinators for those two instances are started. See "Service Affinity when Using the Scheduler" for more information.

The job coordinator:

• Controls and spawns the job slaves

• Queries the job table

• Picks up jobs from the job table on a regular basis and places them in a memory cache. This improves performance by reducing trips to the disk

• Takes jobs from the memory cache and passes them to job slaves for execution

• Cleans up the job slave pool when slaves are no longer needed

• Goes to sleep when no jobs are scheduled

• Wakes up when a new job is about to be executed or a job was created using the CREATE_JOB procedure

• Upon database, startup after an abnormal database shutdown, recovers any jobs that were running.