Senior engineer at a top internet giant, sharing Java, AI, tech knowledge, growth insights, and interview experiences.
The article explains how replacing centralized session lookups with JWT-based local verification can cut authentication latency from 15 ms to 0.3 ms—a roughly 50‑fold improvement—while describing a double‑token strategy, its refresh flow, security best practices, and trade‑offs such as delayed revocation.
To survive a million concurrent flash‑sale clicks, the article breaks down a production‑grade, five‑layer architecture—CDN, load balancer, API gateway, Redis/Lua stock control, message‑queue order processing, and a state‑machine fallback—that filters traffic early, uses atomic operations, and decouples writes to keep database load to just a few QPS.
The article explains how using a message queue as a buffer, asynchronous processor, and decoupling layer enables flash‑sale systems to handle tens of thousands of orders per second, reducing database overload, cutting response time from 500 ms to 50 ms, and preventing cascade failures.
The article explains how to prevent system crashes during massive traffic spikes by applying three core techniques—rate limiting, circuit breaking, and graceful degradation—detailing algorithm choices, state machines, and practical implementation steps for high‑concurrency back‑end services.
The article dissects a proven trillion‑level counter architecture, tracing its evolution from a simple MySQL table through hash sharding, a full Redis migration, deep Redis memory optimizations, and hot‑cold separation, while detailing the trade‑offs and performance gains at each step.
The article explains why static service addresses break in micro‑service architectures, then breaks down the core mechanisms of a registration center—service registration and discovery, heartbeat health checks, and a selection matrix of Nacos, Eureka, ZooKeeper, and ETCD—providing practical guidance for choosing the right solution.
When a system is split into multiple databases and tables, the article explains the root cause of ID collisions and compares four mainstream ID generation strategies—UUID, database auto‑increment, Snowflake, and segment allocation—detailing their trade‑offs, pitfalls, and selection guidelines for different concurrency levels.
The article outlines five common cache design problems—penetration, concurrency, avalanche, hot‑data management, and business‑cache coupling—illustrates each with a diagram, and provides concrete Redis‑based solutions such as placeholder values, setNX locks, random TTLs, sorted‑set queues, and a Binlog‑Canal‑MQ pipeline.
This article breaks down Redis’s core mechanisms—including its single‑threaded performance tricks, AOF and RDB persistence designs, and the evolution of high‑availability from replication to Sentinel and Cluster—using four clear diagrams to help readers master the system.
The article breaks down MySQL index mechanics into four visual sections, explaining B+Tree structure, why it outperforms B‑tree, hash and binary trees, common index‑failure scenarios, and three practical optimization techniques, giving interviewees a clear framework to answer index‑related questions confidently.
