Drills

What should you consider before using @Async in Spring?

Treats @Async as an in-process executor boundary with proxy, failure, context, capacity, and durability consequences.

Comparison questionMedium~10 min

When are discriminated unions useful in a FastAPI request model?

Uses an explicit discriminator to model genuine request variants with predictable validation and OpenAPI output.

FastAPIPydanticPython

When are FastAPI BackgroundTasks appropriate, and when do you need a real task queue?

Chooses between small in-process follow-up work and durable, independently operated background execution.

FastAPIPython

Concept questionMedium~10 min

When does a Django QuerySet execute, and what does it cache?

Explains lazy query construction, evaluation triggers, result caching, and repeated-query surprises.

DjangoPython

Architecture scenarioMedium~10 min

When do Python generics and TypeVar improve an API?

Uses generics to preserve relationships among types and introduces bounds, constraints, and variance only where they clarify a real API.

Python

When do utility and mapped types improve a TypeScript model, and when do they hide the domain contract?

Uses derived types for genuine relationships while preserving explicit boundaries for domain and transport models.

JavaScriptTypeScript

When do you choose Spring MVC versus Spring WebFlux?

Chooses between blocking Servlet execution and end-to-end non-blocking reactive execution based on dependencies, concurrency, and team cost.

When do you use a fetch join, entity graph, or batch fetching in Hibernate?

Chooses among explicit joins, reusable fetch graphs, and bounded secondary selects based on query shape and cardinality.

When do you use a Servlet filter, HandlerInterceptor, or ControllerAdvice?

Places protocol-wide work in filters, handler-aware MVC work in interceptors, and controller exception or body concerns in advice.

When do you use JPQL, native SQL, Criteria API, or Spring Data specifications?

Chooses a query representation from static versus dynamic shape, portability, database features, readability, and performance evidence.

When do you use optimistic versus pessimistic locking in JPA?

Chooses version-based conflict detection or database locks from contention, transaction duration, and invariant needs.

When do you use request authorization versus method security in Spring?

Uses HTTP rules for route-level policy and method security for reusable service operations without creating contradictory enforcement.

When do you use RestClient, WebClient, or an HTTP Service interface in Spring?

Chooses synchronous, reactive, or declarative clients based on the application's execution model while keeping shared timeout and error policy explicit.

When do you use session authentication versus bearer tokens in Spring?

Chooses credential transport and server state from client shape, revocation, browser threats, scaling, and operational requirements.

When do you use Spring Boot runners, events, and lifecycle hooks?

Chooses hooks by application readiness phase and keeps migrations, warm-up, listeners, and background resources owned and observable.

Comparison questionMedium~10 min

When do you use volatile, synchronized, or atomic variables in Java?

Chooses visibility, mutual exclusion, or atomic read-modify-write based on the invariant instead of treating the tools as interchangeable.

Java

When is a single model call enough, and when do you need an AI workflow?

Chooses the smallest execution model that satisfies the task while recognizing when explicit multi-step coordination adds real value.

Artificial IntelligenceGenerative AILarge Language Models

Architecture scenarioHard~10 min

When is CSRF protection required in Spring Security?

Bases CSRF policy on whether browsers automatically attach credentials and keeps unsafe requests protected without disabling security globally.

Concept questionMedium~10 min

When is FastAPI `BackgroundTasks` enough, and when do you need a durable worker?

Distinguishes small in-process post-response work from durable, retryable, independently operated jobs.

FastAPIPydanticPython

When is property-based testing with Hypothesis useful?

Uses generated examples to test stable invariants while preserving readable examples and reproducible failures.

pytestPython

When is ThreadLocal useful, and what lifecycle risks does it create?

Explains per-thread state, pooled-thread leakage, context cleanup, hidden dependencies, and virtual-thread scaling concerns.

Java