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Cribl·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
Jun 2026

Summary

System design round at Cribl for a software engineering role. The whole interview was basically one big open-ended question about log parsing pipelines, which sounds narrow until you realize they want you to cover everything from schema inference to privacy to scaling. Felt like a platform eng interview dressed up as an ML question.

Questions Asked (1)

Q1

Design a production system that uses an LLM, optionally combined with deterministic parsers, to convert raw log messages in heterogeneous formats into structured JSON. Walk through architecture, data flow, schema inference, extraction strategy, validation, scaling, reliability, monitoring, privacy considerations, and how you'd evaluate quality.

System DesignTechnical Trade-offsData Modeling
Author's notes

This one is deceptively wide.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then propose a hybrid architecture that uses deterministic parsers for known formats and an LLM for unknown or complex formats, with a feedback loop for continuous improvement. Walk through the end-to-end pipeline, emphasizing schema inference, validation, and scalability, and conclude with evaluation metrics and trade-offs.

Pro tip: Emphasize the importance of a human-in-the-loop validation and feedback mechanism to continuously improve extraction accuracy and adapt to new log formats, which is crucial for production reliability.

1. Clarify Requirements and Constraints

Ask questions to understand the scale (logs per second), latency requirements, variety of log formats, and privacy constraints. This will shape the architecture and choice of components.

2. Design the Architecture and Data Flow

Propose a pipeline: ingestion (e.g., Kafka), preprocessing (cleaning, tokenization), routing to deterministic parsers or LLM, post-processing (validation, enrichment), and output to JSON. Include components for schema inference, monitoring, and feedback.

3. Detail Extraction and Schema Inference Strategy

Explain how to use deterministic parsers (regex, grok) for known formats and LLM for unknown ones. Describe schema inference: LLM can suggest fields, or use clustering and statistical methods. Mention prompt engineering and few-shot learning for LLM.

4. Address Validation, Scaling, and Reliability

Discuss validation rules (type checks, required fields), handling malformed logs, and fallback mechanisms. For scaling, use horizontal scaling, batching, caching, and async processing. For reliability, implement retries, dead-letter queues, and idempotency.

5. Cover Monitoring, Privacy, and Evaluation

Outline monitoring metrics (throughput, latency, accuracy, error rates) and alerting. Address privacy: PII redaction, encryption, access controls. For evaluation, define metrics (precision, recall, F1) and use labeled data, A/B testing, and human review.

Key Points to Mention

  • Hybrid approach: deterministic parsers for known formats, LLM for unknown/complex formats
  • Schema inference techniques: LLM-based, clustering, or statistical analysis
  • Validation and error handling: schema validation, fallback to raw storage, dead-letter queues
  • Scalability: horizontal scaling, batching, caching, async processing
  • Monitoring and observability: metrics, logging, tracing, alerting
  • Privacy: PII detection and redaction, encryption, access control
  • Evaluation: precision/recall/F1, human-in-the-loop, continuous feedback

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.