Multiple checkout lanes at a store
Day 30 of 149
👉 Full deep-dive with code examples
The Bank Teller Analogy
Multiple tellers at a bank:
- One teller → Long line, slow service
- Five tellers → Shorter lines, faster service
- Manager directs customers to available tellers
A Load Balancer directs traffic to available servers!
The Problem It Solves
One server has limits:
- Can handle a limited number of requests
- If it goes down, users may get delays or errors
- Gets slow as traffic grows
How It Works
Traffic goes through the load balancer:
┌─────────────────┐
Users ─────────────▶│ Load Balancer │
└────────┬────────┘
│
┌────────────────┼────────────────┐
▼ ▼ ▼
Server 1 Server 2 Server 3
The load balancer decides which server handles each request.
Distribution Methods
Round Robin:
- Request 1 → Server 1
- Request 2 → Server 2
- Request 3 → Server 3
- Repeat!
Least Connections:
- Send to server with fewest active requests
- Better when some requests take longer
Geographic:
- US users → US servers
- European users → EU servers
Benefits
- Handle more traffic → Multiple servers share load
- High availability → One server down? Others still work
- Scalability → Add more servers as needed
- Better performance → Users hit less-busy servers
In One Sentence
Load Balancing distributes incoming traffic across multiple servers so no single server gets overwhelmed and your app stays fast and available.
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