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Software Engineering Fundamentals questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master software engineering fundamentals interviews.

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This is a medium difficulty Software Engineering Fundamentals question, commonly asked during Onsite rounds at Meta.

What role is this question designed for?

This question is commonly asked for Machine Learning Engineer candidates at Meta during technical interviews.

Design concurrent expiring job registry

Q: Design concurrent expiring job registry

This question evaluates understanding of concurrent data structures, synchronization primitives, time-based expiration semantics, and efficient cleanup strategies for an in-memory job registry.

Design (and discuss how you would implement) an in-memory job registry that supports concurrent access.

Each job has a unique jobId and an expiration time (TTL or absolute timestamp). The system must:

Requirements

addJob(jobId, payload, expiresAt) : add or update a job with an expiration time.
getJob(jobId) : fetch job if it exists and is not expired.
removeJob(jobId) : remove a job.
A background mechanism (one thread is enough) should delete expired jobs automatically .
Must be safe under concurrency (multiple threads calling APIs).

Discussion points

Data structures to make cleanup efficient
Race conditions between readers/writers and the cleanup thread
Time complexity and how to avoid O(n) scans

Design (and discuss how you would implement) an in-memory job registry that supports concurrent access.

Each job has a unique jobId and an expiration time (TTL or absolute timestamp). The system must:

Requirements

addJob(jobId, payload, expiresAt) : add or update a job with an expiration time.
getJob(jobId) : fetch job if it exists and is not expired.
removeJob(jobId) : remove a job.
A background mechanism (one thread is enough) should delete expired jobs automatically .
Must be safe under concurrency (multiple threads calling APIs).

Discussion points

Data structures to make cleanup efficient
Race conditions between readers/writers and the cleanup thread
Time complexity and how to avoid O(n) scans

Design concurrent expiring job registry

Quick Overview

Requirements

Discussion points

Solution

Comments (0)

Design concurrent expiring job registry

Quick Overview

Requirements

Discussion points

Solution

Comments (0)