go-load-testing

When to Use

• Validating service performance under expected and peak load
• Finding the breaking point of an endpoint
• Testing sudden traffic spikes (e.g., promotional push notifications)
• Detecting memory leaks or connection pool exhaustion (soak tests)
• Running performance smoke tests before releases

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Critical Patterns

Test Types

Test Type	Purpose	VUs	Duration
Smoke	Verify service works under minimal load	1-5	30s
Load	Validate under expected production traffic	50-100	5m
Stress	Find breaking point	100→500 ramp	10m
Spike	Test sudden traffic burst	1→500→1	3m
Soak	Find memory leaks, connection pool exhaustion	50	30m+

Directory Structure

k6 scripts live under tests/load/{service}/:

tests/load/
  notification/
    smoke.js           # Quick smoke test (1-5 VUs)
    load.js            # Normal load test (50-100 VUs)
    stress.js          # Stress test (ramp to 500 VUs)
    spike.js           # Spike test (sudden burst)
  auth/
    smoke.js
    load.js

Thresholds

Every k6 test MUST define thresholds — the pass/fail criteria:

Metric	Target	Meaning
http_req_duration p(95)	< 200ms	95% of requests under 200ms
http_req_duration p(99)	< 500ms	99% of requests under 500ms
http_req_failed	< 1%	Less than 1% error rate
http_reqs	> 100/s	Minimum throughput

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Decision Tree

Quick sanity check before deploy?
  → Smoke test (1-5 VUs, 30s)

Validating expected production traffic?
  → Load test (50-100 VUs, 5 min)

Finding the breaking point?
  → Stress test (ramp to 500 VUs)

Testing sudden traffic spike (e.g., push campaign)?
  → Spike test (1 → 500 → 1)

Detecting memory leaks or pool exhaustion?
  → Soak test (50 VUs, 30+ min)

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Assets

File	Description
assets/k6-smoke.js	Smoke test: minimal load sanity check
assets/k6-load.js	Load test: expected production traffic with ramp stages
assets/k6-stress.js	Stress test: find breaking point with increasing load
assets/k6-spike.js	Spike test: sudden burst of traffic

See each asset for the full script template with thresholds.

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Commands

brew install k6                                             # Install k6
k6 run tests/load/notification/smoke.js                     # Run smoke test
k6 run tests/load/notification/load.js                      # Run load test
k6 run --out json=results.json tests/load/notification/stress.js  # With JSON output

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Anti-Patterns

Don't	Do
Load test without thresholds	Always define p95, p99, error rate
Skip smoke test before deploy	Smoke is 30 seconds — always run it
Run stress tests against production	Run against staging or a dedicated environment
Ignore soak test results	Memory growth means a leak — fix it
Hardcode URLs in scripts	Use k6 environment variables for base URL