Outbound Campaign API 429s during JMeter ramp-up

General Discussion
1

Trying to understand the rate limiting behavior on the Outbound Campaign API endpoints during high-concurrency load tests.

Background

Running JMeter tests to validate campaign creation throughput. The goal is to simulate 50 concurrent users creating outbound campaigns via the /api/v2/outbound/campaigns endpoint. Environment is Genesys Cloud US-East. Using the latest SDK version 2.5.0 for payload generation.

Issue

When ramping up to 20 threads, requests succeed. At 25 threads, hitting consistent 429 Too Many Requests errors. The response body includes a Retry-After header, but the value is inconsistent. Sometimes it’s 1 second, other times 5 seconds. The error response payload is empty, which makes debugging tricky. No X-RateLimit headers are present in the response, making it hard to predict the limit.

Troubleshooting

  • Verified payload structure against the Swagger spec. All required fields are present.
  • Checked account-level API quotas. No custom limits applied.
  • Reduced thread count to 10. Errors stop. Increased to 15. Errors appear sporadically.
  • Tried adding a Retry-After delay in JMeter. Helps, but throughput drops significantly. Not viable for our scale requirements.

Is there a documented per-endpoint limit for campaign creation? Or is this a global API throttle? Need to adjust the load test strategy accordingly.

2

This looks like standard tenant-level throttling rather than a campaign-specific limit. Implementing exponential backoff in your JMeter script is mandatory to avoid 429s during ramp-up.