The purpose of this KB is providing insight into how the 'Single Run' setting for jobs works.
Both Jobs and Process flows have a 'Single Run' checkbox in their 'General' tabs. This setting is used to prevent multiple copies of job from RUNNING simultaneously. If a duplicate copy of a Job or Process flow enters the Backlog while there is a RUNNING instance of the same job, the newer copy will go into SELF_WAIT. This setting however will not prevent the newer copy of the job from running if the previous copy is in the Backlog in a non-RUNNING status.
Below are some examples to illustrate how this setting functions:
TEST_JOB is in the backlog in RUNNING. A second copy of TEST_JOB enters the backlog.
TEST_JOB goes to SELF_WAIT.
TEST_JOB is in the backlog in ABORTED/HOLD. A second copy of TEST_JOB enters the backlog.
TEST_JOB goes to RUNNING.
The same holds true for Process Flows (Chains). However, as Process Flows generally are in INITIATED/FINISHED status, which are both 'RUNNING' statuses, they will go into a SELF_WAIT. An exception to this is STAGED jobs. Copies of STAGED Process Flows entering the backlog will go into a RUNNING status.