performance-testing

Performance Testing

Load and performance testing validates that your system meets latency and throughput requirements under realistic and extreme traffic conditions.

When to Activate

• Load testing an API before a product launch
• Setting up k6 or Locust for a project
• Writing Go benchmark functions for critical code paths
• Defining SLO-based pass/fail thresholds for load tests
• Identifying bottlenecks under load (pool exhaustion, N+1, GC pressure)
• Adding performance regression detection to a CI/CD pipeline

Test Type Decision Table

Type	Description	Load shape	Goal	When to run
Load	Simulate expected traffic	Ramp to normal, hold	Verify baseline meets SLO	Pre-launch, nightly
Stress	Push beyond capacity	Ramp past normal	Find breaking point	Before scaling decisions
Soak	Sustained load over time	Constant for 1–4 hours	Detect memory leaks, pool exhaustion	Weekly
Spike	Sudden burst	0 → peak instantly	Test autoscaling, queue buffering	Before planned events
Volume	Large datasets, normal load	Normal rps, huge data	Find data-size bottlenecks	When data volume increases

k6

Script Structure

import http from 'k6/http';
import { check, sleep } from 'k6';
import { Rate, Trend } from 'k6/metrics';

const errorRate = new Rate('errors');
const paymentDuration = new Trend('payment_duration');

export const options = {
  stages: [
    { duration: '2m', target: 50 },   // ramp up
    { duration: '5m', target: 50 },   // hold
    { duration: '2m', target: 100 },  // ramp up further
    { duration: '5m', target: 100 },  // hold
    { duration: '2m', target: 0 },    // ramp down
  ],
  thresholds: {
    // SLO-based pass/fail: test fails if these are breached
    'http_req_duration': ['p(95)<500', 'p(99)<1000'],
    'http_req_failed':   ['rate<0.01'],
    'errors':            ['rate<0.05'],
  },
};

export default function () {
  const res = http.post(
    'https://api.example.com/payments',
    JSON.stringify({ amount: 100, currency: 'USD' }),
    {
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Bearer ${__ENV.API_TOKEN}`,
      },
    }
  );

  const ok = check(res, {
    'status is 201':          (r) => r.status === 201,
    'response time < 500ms':  (r) => r.timings.duration < 500,
  });

  errorRate.add(!ok);
  paymentDuration.add(res.timings.duration);
  sleep(1);  // think time between requests
}