vercel-load-scale

# Vercel Load & Scale ## Overview Load test Vercel deployments to identify scaling limits, cold start impact, and concurrency thresholds. Covers k6/autocannon test scripts, Vercel's auto-scaling model, Fluid Compute concurrency, and capacity planning. ## Prerequisites - Load testing tool: k6, autocannon, or artillery - Test environment deployment (never load test production without approval) - Access to Vercel Analytics for monitoring during tests ## Instructions ### Step 1: Understand Vercel's Scaling Model Vercel serverless functions scale automatically: | Behavior | Details | |----------|---------| | Scale-up | New function instances spawn on demand | | Scale-down | Idle instances shut down after ~15 minutes | | Cold starts | First request to a new instance pays initialization cost | | Concurrency | Each instance handles one request at a time (by default) | | Fluid Compute | Pro/Enterprise: multiple requests per instance | **Concurrency limits by plan:** | Plan | Max Concurrent Functions | |------|------------------------| | Hobby | 10 | | Pro | 1,000 | | Enterprise | 100,000 | ### Step 2: Basic Load Test with autocannon ```bash # Install autocannon npm install -g autocannon # Test with 50 concurrent connections for 30 seconds autocannon -c 50 -d 30 https://my-app-preview.vercel.app/api/endpoint # Output includes: # Latency: avg, p50, p99, max # Requests/sec: avg, min, max # Errors: timeouts, non-2xx responses ``` ### Step 3: k6 Load Test Script ```javascript //...