Drills

When should you use ConcurrentHashMap or another concurrent collection?

Chooses concurrent collections by required atomic operations and iteration semantics rather than treating them as synchronized replacements.

Comparison questionHard~10 min

When should you use pytest skip, xfail, or quarantine a test?

Distinguishes unavailable conditions, known defects, and unstable tests while keeping lost coverage visible.

pytestPython

When should you use wait and notify instead of higher-level Java concurrency tools?

Explains monitor wait sets and guarded loops while preferring queues, latches, semaphores, futures, and conditions for standard coordination.

When would you choose a comprehension or a generator expression in Python?

Compares eager collections with lazy one-pass generation through memory, timing, reuse, readability, and resource ownership.

When would you choose ArrayList or LinkedList in Java?

Compares Java list implementations using actual access patterns, traversal cost, memory locality, and insertion location.

When would you choose ReentrantLock instead of synchronized?

Chooses an explicit lock only when timed, interruptible, conditional, or advanced acquisition behavior justifies manual lifecycle.

When would you use a function-based or class-based Django view?

Chooses Django view style by clarity, reuse, and lifecycle needs rather than hierarchy preference.

DjangoPython

When would you use asyncio Lock, Event, Condition, or Semaphore?

Chooses task synchronization by protected state, notification predicates, and limited capacity.

Comparison questionHard~15 min

When would you use asyncio.TaskGroup or asyncio.gather()?

Compares structured task ownership with ordered result aggregation and different failure behavior.

Comparison questionHard~15 min

When would you use asyncio.to_thread() or run_in_executor()?

Compares convenient context-propagating thread offload with explicit executor selection and ownership.

When would you use Django select_related or prefetch_related?

Chooses Django relationship loading from relationship shape, result cardinality, and measured query behavior.

DjangoPython

When would you use FastAPI TestClient versus an async HTTP client?

Chooses synchronous or asynchronous FastAPI test clients from the boundary exercised and resources involved.

FastAPIpytestPython

When would you use HashMap, LinkedHashMap, or TreeMap?

Chooses among common Java map implementations by lookup behavior, iteration order, sorting, range operations, and key contracts.

When would you use Spring application events instead of durable messaging?

Separates in-process decoupling from durable cross-process delivery and makes timing, failure, and transaction expectations explicit.

JavaSpring Boot

When would you use SQLAlchemy ORM, SQLAlchemy Core, or raw SQL?

Chooses a SQLAlchemy abstraction from the work's shape instead of performance slogans.

PythonSQLAlchemy

When would you write a custom HealthIndicator for a Spring Boot service?

Adds dependency health only when it supports a specific operational decision and can be checked cheaply and safely.

JavaSpring Boot

Where should a Java service catch, translate, or rethrow exceptions?

Places exception handling at boundaries that can recover, add meaningful context, or translate abstraction levels while preserving the cause.

Architecture scenarioHard~15 min

Where should a SQLAlchemy transaction begin and end, and when are savepoints useful?

Aligns SQLAlchemy transactions with business operations and uses savepoints without inventing independent commits.

PythonSQLAlchemy

Architecture scenarioHard~15 min

Where should business logic live in a Django application?

Balances model methods, QuerySets, managers, and application services by the responsibility they own.

DjangoPython

Where should Python backend code catch, translate, or re-raise exceptions?

Places exception handling at meaningful boundaries and preserves causes, tracebacks, client contracts, and retry safety.

Concept questionMedium~7 min

Where should transaction boundaries be placed in a Spring application?

Places a short transaction around one application use case while keeping remote calls, user interaction, and bulk work outside.

JavaSpring Boot

Why are raw types and unchecked warnings risky in Java?

Treats raw types as a legacy compatibility boundary that can introduce heap pollution and delayed runtime failures.

Debugging scenarioMedium~7 min

Why can mutable default arguments cause bugs in Python?

Diagnoses shared mutable function defaults and explains safe initialization without turning the behavior into a superstition.