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JAVA CORE

Java Collections in Practice
ArrayList vs LinkedList - What Actually Matters
Common Design Patterns in Java (Overview)
Generics - Wildcards & Type Erasure
HashMap Deep Dive - Resize, Collisions, Treeify
Java IO vs NIO - When It Matters
Reflection & Annotations - Practical Use Cases
String, StringBuilder, StringBuffer

JVM & GC

Class Loading Process & Parent Delegation
G1 GC Overview - What Problem It Solves
GC Basics - Minor GC vs Full GC
GC Tuning Principles (Not a Flag List)
Java Profiling Basics - What to Measure First
JIT & Escape Analysis (High-level)
JVM Memory Model Explained
OutOfMemoryError Playbook (Symptoms → Causes)

JAVA CONCURRENCY

Thread Pools in Java
AQS Explained - How Locks Are Built
CompletableFuture - thenApply vs thenCompose
ConcurrentHashMap Internals
Deadlock - How to Detect and Prevent
Java Memory Model (JMM) in Plain English
synchronized vs ReentrantLock
Thread Pools in Java (Core Parameters)
volatile - What It Guarantees (and What It Doesn't)

SPRING

Spring AOP - Proxy, Pointcut, Advice
Spring Boot Config Priority
Spring Boot Startup Process
Spring IOC & Bean Lifecycle
Spring Security Basics
Transaction Management in Spring
Validation in Spring

DATABASE (MYSQL)

Index Fundamentals - B-Tree, Covering Index
Locks - Row Lock vs Gap Lock
MVCC Explained
Pagination - Limit/Offset vs Seek Method
Schema Design - Practical Rules of Thumb
Slow Query Diagnosis Workflow
Transactions - Isolation & Common Anomalies

MYBATIS

Batch Insert/Update Patterns
Dynamic SQL Best Practices
MyBatis First/Second Level Cache
Mapper Design for Maintainability
N+1 Query Problem & Fix Patterns
Parameter Binding & SQL Injection Safety
Plugin/Interceptor - When to Use
ResultMap vs ResultType - When It Matters

MICROSERVICES & SPRING CLOUD

API Gateway Basics
Blue-Green vs Canary Deployment
Circuit Breaker, Retry & Timeout
Config Center
Contract Testing Basics
Distributed Tracing Basics
Service Discovery

REDIS

Cache-Aside Pattern Done Right
Caching Pitfalls - Penetration / Breakdown / Avalanche
Redis Data Types & Use Cases
Distributed Lock with Redis - Correctness & Risks
Expiration Strategy - TTL Design
Hot Key / Big Key - Detection & Mitigation
Rate Limiting with Redis (Token Bucket)
Redis Persistence - RDB vs AOF (High-level)

MESSAGING (KAFKA / ROCKETMQ / RABBITMQ)

Idempotency in Message Consumers
Kafka Core Concepts
Kafka Delivery Semantics (At-least-once etc.)
MQ Basics - Why Asynchronous Matters
Ordering vs Throughput - Trade-offs
RabbitMQ - Exchange / Queue / Routing Key
Retry & DLQ Strategy (Practical)
RocketMQ Overview & Common Scenarios

RPC (DUBBO)

Common Production Pitfalls in RPC
Dubbo Architecture Overview
Load Balancing Strategies
Rate Limit & Degrade in RPC
RPC Fundamentals - What Happens on a Call
Serialization Tradeoffs
Service Versioning & Compatibility
Timeout, Retry & Fallback

DISTRIBUTED SYSTEMS

CAP Theorem
Consistency Models
Distributed Lock Options
Distributed Transactions
High Availability Basics
High Concurrency Toolkit
Idempotency Design Patterns
Retry, Backoff & Deduplication

Java Concurrency

9 articles

Thread Pools in JavaWhy and how to use thread pools for concurrency instead of creating threads directly.AQS Explained - How Locks Are BuiltAbstractQueuedSynchronizer and how locks are built on it in Java.CompletableFuture - thenApply vs thenComposeDifference between thenApply and thenCompose when chaining async operations.ConcurrentHashMap InternalsHow ConcurrentHashMap works internally.Deadlock - How to Detect and PreventDetecting and preventing deadlocks in Java.Java Memory Model (JMM) in Plain EnglishJMM explained in plain language.synchronized vs ReentrantLockWhen to use synchronized vs ReentrantLock.Thread Pools in Java (Core Parameters)Explore ThreadPoolExecutor parameters, queuing strategies, rejection policies, and shutdown mechanisms for Java concurrency.volatile - What It Guarantees (and What It Doesn't)Visibility and ordering guarantees of volatile in Java.

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