1. What is Capacity Planning? Capacity planning is the discipline of answering one question in a systematic way: “Given how the business expects customers to use the site, what amount of compute, database, cache, network, and storage do we need so the system remains fast and reliable, even during peaks and failures?” Conceptually, it is […]
Garbage Collection automatically reclaims heap memory occupied by objects that are no longer reachable by any live thread. 1. Why GC exists Manual memory management is hard and error-prone: The JVM uses GC to: Production impact: 2. Heap structure (Young, Old, Metaspace) Modern HotSpot heap (simplified view): +———————————————————+| Java Heap || || +——————-+ +—————————–+ || […]
The Java Memory Model defines how threads interact through memory and what visibility and ordering guarantees the JVM provides. 1. Why the Java Memory Model exists The JMM exists to answer one critical question: When multiple threads read and write shared variables, what outcomes are legal? Without a well-defined memory model: The JMM: Pre-Java 5, […]
The JVM is the runtime environment that loads, verifies, optimizes, and executes Java bytecode on a specific machine. 1. What the JVM is responsible for At a high level, the JVM is responsible for: Why this exists: Real-world example: 2. JVM architecture (high level) A conceptual view: +————————————————————–+| JVM PROCESS || || +——————–+ +——————————-+ || […]
Networking protocols are standardized rules that let applications communicate reliably and securely over the internet by organizing how data travels, where it goes, and what path it takes. What This Combination Is and Why These Protocols Matter When you build backend systems, data must move between servers, clients, and services. Without protocols, every engineer would […]
Big Picture Overview Before a single server can handle all your traffic, you face a fundamental problem: as your application grows, requests pour in from thousands of users simultaneously. A single server—no matter how powerful—has limits. It can only accept a finite number of connections, process a finite number of requests per second, and store […]
Big Picture Overview Imagine you’re trying to visit amazon.com, but computers don’t understand English. They only speak IP addresses—long numbers like 205.251.242.103. Someone needs to translate the human-friendly name (amazon.com) into the machine-friendly address. That’s the Domain Name System (DNS). Without DNS, you’d need to memorize thousands of IP addresses. The internet would be unusable. […]
Executive Summary Redis is an open-source, in-memory data structure store that has become indispensable in modern application architecture. This guide provides a comprehensive overview of essential Redis terminologies, concepts, and practical examples designed for developers and technical leads building scalable, high-performance systems. Understanding these core concepts is crucial for leveraging Redis effectively in production environments. […]
Introduction Amazon DynamoDB is a fully managed NoSQL database service that powers some of the world’s most demanding applications. As a Java/e-commerce engineer, understanding DynamoDB concepts is crucial for building scalable systems. This guide breaks down essential DynamoDB terminologies using real-world examples you can relate to. 1. Table Definition: A collection of data records, similar […]
Target Audience: Software engineers with Java + AWS background Table of Contents Foundations What Observability Really Means Observability vs. Monitoring: The Critical Distinction The two terms are often used interchangeably but serve fundamentally different purposes. Understanding this distinction is essential for Tech Lead credibility. Monitoring answers the question: “What is wrong?” It uses predefined metrics, […]
My Notes 