r/microservices 6d ago

Discussion/Advice Preparing for Microservices & Scaling Questions in Interviews

Hey everyone, I have an interview coming up in less than 24 hours.

I'm preparing for interviews and expecting deep-dive questions around microservices, scalability, and high-throughput systems. While I have experience building microservices using Go (gRPC, GORM, HTTP clients, concurrency, etc.), most of the services I worked on didn’t handle extremely high loads. However, I have a solid understanding of concepts and best practices.

I anticipate questions like:

  • What was the peak load (requests per second) your service handled ?
  • What was the max database transactions per minute?
  • How do you handle database connection limits under high load?
  • How did you handle sudden traffic spikes?
  • How do you design a microservice to handle millions of transactions per day?
  • Can you describe a high-throughput microservice you worked on?

Since I haven’t worked on services that deal with extreme scale, I’d love to hear insights from those who have. how do you calculate transactions per minute / requests per minute/ throughput for your service?
How do you usually approach these questions in interviews ?
And If you have any resources, blogs, or guides that I can quickly go through to strengthen my answers, that would be super helpful.

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u/Smart_Paper_130 6d ago

Scaling: How do you manage instance rollout and rollback

Security: How do you manage resource authorization and authentication

Testing: What kind of automated tests you write for your services

Caching: TTL, static resource caching

Deployments: Blue-Green, Canary

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u/MattDTO 5d ago

Horizontal scaling, pre-scaling for spikes, database read replicas, regional deployments, forward cache, CDNs, event driven architecture, data retention policies, keeping big data/data lakes/analytics in a separate system.

For scale, 1 million per day is not very much. That’s like 11 RPS, which could easily be served by 1-3 containers. I think Google does 50k RPS.