Senior Developer 路 5+ years
Senior interviews are less about the right answer and more about how you decide. Expect open-ended questions where you must state assumptions, compare options, name the costs of each and explain what you would measure.
78 questions
synchronized gives mutual exclusion and memory visibility for a block of code, while volatile only guarantees that reads and writes of one variable are visible to all threads and does not make compound operations such as count++ atomic.
The Global Interpreter Lock (GIL) in CPython lets only one thread execute Python bytecode at a time, so threads do not speed up CPU-bound code but still help with I/O-bound work.
Threading runs concurrent threads that share memory and suit blocking I/O, multiprocessing runs separate processes to use multiple CPU cores for CPU-bound work, and asyncio runs many non-blocking tasks cooperatively on one thread for high-volume I/O.
Generate a short unique code for each long URL (for example by base62-encoding a unique ID), store the mapping in a key-value or relational database, serve redirects through a cache because reads far outnumber writes, and record analytics asynchronously.
The CAP theorem says that during a network partition a distributed system must choose between consistency (every read sees the latest write) and availability (every request gets a response); you cannot have both while the partition lasts.
Replication copies the same data to several servers to improve read capacity and availability, while sharding splits the data across servers so each holds only a part, which increases write capacity and total storage.
Start with a well-structured monolith unless you have several teams and clear service boundaries, because microservices add distributed-system complexity such as network failures, data consistency and operational overhead.
Accept notification requests through an API, put them on a message queue, and let channel-specific workers (email, SMS, push, in-app) send them using user preferences, templates, retries with idempotency and rate limits.
Clients keep a persistent WebSocket connection to stateless chat servers; messages are stored durably, routed to the recipient鈥檚 server through a pub/sub layer, and delivered as push notifications when the recipient is offline.
Store file contents as chunks in object storage and file metadata in a database; clients upload chunks directly with pre-signed URLs, a sync service tracks versions and changes, and a CDN serves downloads.
Show how you built trust, understood competing concerns, used evidence and helped the group reach a decision.
Explain the constraints, alternatives, trade-offs, decision criteria and why the chosen option was appropriate for the context.
Cover detection, communication, mitigation, investigation, recovery and the changes made afterwards to reduce recurrence.
Explain why the technology looked attractive, what problem it actually solved, and why its cost or complexity was not justified in your context.
Explain the deadline, the quality risks, what you protected, what you simplified and how you managed any remaining debt.
Explain the original reasoning, the evidence that changed your view, how you corrected course and what decision-making practice improved afterwards.
Walk through how you shaped the problem, planned the work, aligned stakeholders, managed risks and measured the outcome.
Show empathy, clear expectations, practical support and appropriate escalation rather than blame.