Python core
hash and eq (contract, when to override, hashability) async / asyncio (event loop, coroutines, await) threads vs multiprocessing (GIL, when to use which) Python concurrency (overlaps the above — async vs threads vs processes trade-offs) Memory management in Python (refcounting, garbage collection, cyclic GC, slots)
Architecture
Monolith vs microservices Clean architecture Event-driven architecture (EDA) EDA with microservices Transactional outbox pattern Saga pattern — orchestrator style (for data consistency across services) Distributed rollback scenario: 10 services, #9 fails → previous 8 compensate/roll back their updated state (compensating transactions)
Inter-service communication
gRPC RabbitMQ Kafka
Databases
SQL vs NoSQL Sharding Indexes
AWS / infra
API Gateway DynamoDB Lambda Step Functions Terraform Kubernetes
Observability
Prometheus Grafana Sentry
AI / data
Temporal RAG Gen AI MCP