Cresta Software Engineer Interview Experience — Phone Screen Building a Least-Load Job Dispatcher

Write a Job Dispatcher-Executor system.

You are tasked with implementing a simple job dispatcher that distributes incoming jobs to a pool of executors (i.e., workers). Each job is represented as an integer (its ID), and executors are dynamically added and removed during runtime.

You must define two classes:

• Executor – Represents a worker that can accept jobs.
• LoadBalancer – Maintains a list of executors and distributes jobs to them.

class Executor

Each executor has:

• A method assign_job(job_id: int) which simply stores the job.
• A method execute_next_job() which removes the next job from the executor's job store

class JobDispatcher

The job dispatcher has:

• A method add_executor(executor: Executor) to add an executor.
• A method remove_executor(executor_id: str) to remove an executor.
• A method dispatch(job_id: int) to assign a job to one of the executors.
• A method get_state() that returns a mapping of executor_id → job list.

Pay attention to how you design the dispatch mechanism, because it will affect your final implementation. The strategy is lowest job load > round-robin.

By default the executors all handle the same type of task, so you don't need to think about the actual task-processing logic.

Also, when you remove an executor, remember to take the jobs currently queued on it and redistribute them to the remaining executors.