System Design: Chat System - Production Architecture скачать в хорошем качестве

System Design: Chat System - Production Architecture

System Design: Chat System - Production Architecture A comprehensive technical deep-dive covering the complete framework for designing production-grade chat systems that handle millions of concurrent users. Learn the WebSocket connection management, message delivery guarantees, sharding strategies, and production scaling patterns that senior engineers need for system design interviews and real-world implementations. ================ What You Will Learn: ================ Requirements & Capacity Planning Functional requirements: 1:1 chat, groups, presence, read receipts Non-functional: 500ms latency, 99.99% availability, ordering Capacity: 100M DAU, 4B messages/day, 10M connections Cost modeling: compute, storage, bandwidth, notifications Transport Layer Architecture WebSocket vs HTTP polling vs long polling vs SSE Memory pressure, file descriptors, connection draining Gateway design: auth, sessions, topic subscriptions L4 load balancing with connection affinity Thundering herd problem and exponential backoff Message Processing Pipeline Chat server: validation, ID generation, persistence Send path (latency-critical) vs receive path (async) Snowflake and ULID for time-sortable message IDs Single-writer per conversation for ordering At-least-once delivery with client deduplication Acknowledgment protocol: send, delivery, read Storage Layer Design Database trade-offs: Cassandra vs sharded PostgreSQL Schema: partition keys, clustering keys, denormalization Conversation model: participants, metadata, last message Consistent hashing with virtual nodes Hot conversation problem and mitigation Hot/cold storage tiering for cost optimization Group Chat & Presence Systems Group architecture: metadata, members, fan-out Fan-out on write vs fan-out on read Celebrity group problem: write amplification Presence: connection events, subscriber notification Batching, lazy fetching, approximate status Read receipts and typing indicators at scale Offline Delivery & Caching Push notifications: APNs, FCM, token management Offline queue: durable storage, reconnection sync Multi-device sync: cursors, conflict resolution Multi-layer caching: client, CDN, Redis, database Cache invalidation: TTL, events, versioning =========== Timestamps: =========== 00:00 - Introduction: Production Chat Challenge 01:58 - Functional Requirements 04:24 - Non-Functional Requirements at Scale 06:54 - Capacity Estimation Deep Dive 09:16 - Cost Modelling Framework 12:02 - High-Level Architecture 13:52 - Request Flow: End-to-End 15:58 - Component Ownership Boundaries 18:14 - WebSocket vs HTTP: The Trade-off 20:30 - WebSocket at Scale Challenges 23:19 - Connection Gateway Design 26:00 - Load Balancing Stateful Connections 27:48 - The Thundering Herd Problem 29:43 - Session State Management 31:19 - Connection Failover Strategy 33:16 - Client Reconnection with Backoff 35:41 - Chat Server Design 37:47 - Message Flow: Send Path 39:40 - Message Flow: Receive Path 42:07 - Message ID Generation Mechanics 44:14 - Message Ordering Guarantees 46:23 - Delivery Semantics: At-Least-Once vs Exactly-Once 47:49 - The Duplicate Message Problem 49:26 - Message Acknowledgment Protocol 51:20 - Database Selection Trade-offs 53:16 - Message Storage Schema 55:02 - Conversation Data Model 56:31 - Sharding Strategy Deep Dive 58:50 - The Hot Conversation Problem 01:00:28 - Hot and Cold Storage Tiering 01:02:01 - Multi-Layer Caching Strategy 01:03:30 - Cache Invalidation Patterns 01:05:18 - Group Chat Architecture ========= About Me: ========= I'm Mukul Raina, a Senior Software Engineer and Tech Lead at Microsoft, with a MS Computer Science from the University of Oxford, UK. On this channel, I create technical deep dives on System Design and ML/AI architectures. #SystemDesign #ChatSystem #WebSocket #SoftwareEngineering #SystemDesignInterview #DistributedSystems #Redis #Sharding #MessageQueue #RealTime #TechInterview #FAANG #ConsistentHashing #DatabaseDesign #Cassandra #ScalableArchitecture