You have cluster running with the FIFO Scheduler enabled. You submit a large job A to the
cluster, which you expect to run for one hour. Then, you submit job B to cluster, which you expect
to run a couple of minutes only.
You submit both jobs with the same priority.
Which two best describes how the FIFO Scheduler arbitrates the cluster resources for a job and its
tasks?

A.
Given Jobs A and B submitted in that order, all tasks from job A are guaranteed to finish before
all tasks from job B.

B.
The order of execution of tasks within a job may vary.

C.
Tasks are scheduled in the order of their jobs’ submission.

D.
The FIFO Scheduler will give, on average, equal share of the cluster resources over the job
lifecycle.

E.
Because there is more then a single job on the cluster, the FIFO Scheduler will enforce a limit
on the percentage of resources allocated to a particular job at any given time.

F.
The FIFO Schedule will pass an exception back to the client when Job B is submitted, since all
slots on the cluster are in use.

Explanation:
FIFO (first-in first-out) scheduling treats a job’s importance relative to when it was
submitted.
The original scheduling algorithm that was integrated within the JobTracker was called FIFO. In
FIFO scheduling, a JobTracker pulled jobs from a work queue, oldest job first. This schedule had
no concept of the priority or size of the job, but the approach was simple to implement and
efficient.