System Design 03 - Load Balancing: Because Even Your System Needs to Chill

Intro:

Load balancing is like a seasoned bouncer for your app. It ensures no single server is overworked, directing each request to where it can be handled best. Here’s how it keeps your system running smooth without any bottlenecks.

1. What Is Load Balancing? The Traffic Cop of Your System

• Purpose: Distribute incoming traffic across multiple servers, so no single server is overwhelmed.
• Analogy: Imagine a busy restaurant where a host sends diners to different tables to avoid overcrowding in one area. That’s load balancing in action.

2. Types of Load Balancers: Different Tools for Different Traffic

• Hardware Load Balancers: Physical devices (yes, actual hardware) to balance loads. Expensive but powerful.
  • Best For: High-security, enterprise systems (think banking, government services).
• Software Load Balancers: Software-based solutions (like NGINX, HAProxy) that handle load balancing.
  • Best For: Cloud environments, microservices, and websites.
• Cloud Load Balancers: Managed solutions provided by cloud providers (AWS, Google Cloud).
  • Best For: Startups and scalable apps needing flexibility without hardware headaches.

3. Load Balancing Algorithms: How the Traffic is Divvied Up

• Round Robin: Requests are distributed sequentially across servers. Simple but effective.
• Least Connections: Directs traffic to the server with the fewest active connections—keeps things even.
• IP Hash: Routes requests based on the client’s IP address. Great for user-specific data caching.
  • Real World: Think of splitting workload by assigning people to lines based on their names alphabetically.

4. Health Checks: Keeping an Eye on Server Fitness

• Why: Avoid sending requests to servers that are down or overloaded.
• How: The load balancer regularly checks servers’ health (via ping or HTTP checks). If a server fails, traffic skips it until it’s back up.
  • Real World: Like a party planner checking if the bartender is out of juice and redirecting guests elsewhere if needed.

5. Benefits of Load Balancing: Why It’s More than Just a Pretty Face

• Increased Availability: If one server fails, the load balancer shifts traffic to others, keeping your app up and running.
• Scalability: Easily add more servers under the balancer to handle increased traffic.
• Reduced Latency: Directs users to the fastest available server (typically closest geographically).

6. Real-World Use Cases

• E-commerce: Handling high traffic during sales by balancing requests across multiple servers.
• Social Media: Balancing millions of requests daily, keeping feeds loading seamlessly.
• Streaming Services: Directing users to the nearest server to reduce lag and improve streaming quality.

Closing Tip: Load balancing keeps your system from becoming a chaotic traffic jam. Remember, though—good balance isn’t just about spreading the load; it’s about making sure every request finds the best seat in the house.

Cheers🥂