SuperMoney Onsite Interview for Machine Coding In-Memory Message Broker
Question Details
Problem Statement Design and implement an in-memory message broker library that facilitates asynchronous communication via topics, supporting high concurrency, configurable data retention, and pre
Full Details
Problem Statement Design and implement an in-memory message broker library that facilitates asynchronous communication via topics, supporting high concurrency, configurable data retention, and precise consumer tracking.
System Requirements and Capabilities *
Core Architecture *
Entities: The library manages Topics, Publishers, and Consumers. *
Data Format: Messages are transmitted as strings. *
Relationships: A single topic supports multiple publishers and multiple consumers. While the system supports many-to-many relationships, individual publisher and consumer instances are bound to a specific topic. *
Topic Management: APIs must exist to create and delete topics dynamically. *
Publishing and Concurrency *
Parallel Execution: The library supports parallel publishing, enabling multiple publishers to send messages to a topic simultaneously without blocking one another. *
Consumption and Offset Management *
Execution Model: Consumers process messages as they are received by the topic. *
Independent Tracking: Each consumer manages its own offset independently to track reading progress. *
Error Handling: The system must handle exceptions gracefully to prevent crashes during message processing. *
Data Lifecycle *
Retention Policy: Topics possess a configurable maximum retention period. *
Expiration: Messages exceeding the retention period must be permanently deleted and rendered inaccessible to any consumer. *
Advanced Features *
Message Replay: The system allows resetting a consumer's offset to a specific point to enable message replaying. *
Observability: The library provides visibility into consumer status by calculating and exposing the current offset and message lag.
About This Question
This is a reported interview question from a supermoney interview for a swe role during the onsite round reported in 2025.
It covers the following topics: Os, Concurrency, Strings .
Topics
About Supermoney Interview Reports
This question was reported by a candidate who interviewed at Supermoney. LeakCode aggregates interview reports from 10+ sources, including 1Point3Acres, Glassdoor, LeetCode Discuss, Blind, Reddit, Indeed, and Nowcoder. Each report is translated where necessary, deduplicated against existing entries, and tagged by company, role, round type, and reporting date.
Use this question as one calibration data point, not a memorization target. Companies typically rotate their question pools every 2-4 months; the exact wording of a 2024 question may differ from what you encounter today. The underlying pattern, difficulty level, and follow-up depth at Supermoney are the higher-signal extractions to take from this report.
For broader preparation context, the Supermoney interview process typically includes a recruiter screen, one or two technical phone screens, and a 4-5 round on-site loop covering coding, system design (at L4+ levels), and behavioral. Reports tagged on LeakCode show the round-by-round distribution and typical difficulty calibration. To browse questions filtered by round type and seniority, use the company hub linked above.
How To Practice This Type of Question
Solve similar problems on LeetCode under timed conditions (25-35 minutes per medium difficulty). The goal is pattern recognition: recognize the underlying technique (sliding window, two-pointer, BFS, memoized recursion, etc.) within 60-90 seconds of reading. Strong candidates verbalize their hypothesis out loud before coding, then iterate based on feedback. Weak candidates dive into implementation immediately, lose time on the wrong approach, and run out of time for follow-ups.
Companies update their question pools every 2-4 months. The exact wording of any given question may have been retired by the time you interview. Focus your prep on the pattern, not the specific problem. The patterns that appear in Supermoney reports consistently are the ones worth investing in; one-off niche problems are not.
During Your Supermoney Round
Apply the standard interview round template: clarify requirements (2-3 minutes), state your approach out loud and confirm direction with the interviewer (3-5 minutes), code with narration (15-25 minutes), test with concrete examples including edge cases (5 minutes), discuss optimization or trade-offs if time permits (5 minutes). This template is universally accepted across FAANG and adjacent companies; deviating from it produces weaker interviewer feedback signal.
The single most predictive failure mode in Supermoney reports tagged "no hire": not asking clarifying questions. Interviewers are explicitly trained to weight this. Strong candidates ask 3-5 clarifying questions even on problems that look obvious; weak candidates dive into code immediately. The clarifying-question check is often the first signal recorded in the interviewer's written notes.