Digital Engagement API 429 Too Many Requests during JMeter WebSocket Flood Test

Need some help troubleshooting… a specific rate-limiting behavior when pushing digital messaging traffic through the Genesys Cloud APIs. The environment is a standard production instance in us-east-1. We are running a load test to validate the capacity of the Digital Engagement channels, specifically SMS and Web Chat. The goal is to simulate 500 concurrent users initiating sessions simultaneously using JMeter 5.6.2. The test script uses the OpenAPI 3.0 specifications to create sessions via POST /api/v2/communications.

The issue arises almost immediately after the ramp-up phase. Approximately 30% of the requests return a 429 Too Many Requests error. The response headers indicate the retry-after time, but it varies wildly between 1 second and 60 seconds, making it difficult to implement a consistent retry logic in the JMeter beanshell processor. The error payload is consistent:

{
“message”: “Rate limit exceeded. Please retry after 5 seconds.”,
“status”: 429,
“code”: “rate_limit_exceeded”
}

I have checked the API documentation and found information about global rate limits per tenant, but the documentation is vague on the specific limits for the Communications API endpoints. I am aware of the general guideline of 100 requests per second per endpoint, but this test is hitting that limit quickly. The WebSocket connections themselves seem stable, and the Architect flow for the digital channel is minimal, just a simple greeting and transfer to an agent queue.

The question is, are there specific headers or parameters I should be including in the JMeter HTTP Request sampler to handle these rate limits better? Or is there a way to increase the rate limit for load testing purposes? I tried adding a Retry-After header in the request, but it does not seem to affect the server-side decision. Also, I noticed that the error starts appearing even when the concurrent thread count is below 200, which is well below our expected peak volume. Any insights on how to structure the JMeter test to respect the Genesys Cloud rate limits without artificially throttling the test would be appreciated. Currently, the test fails prematurely due to these 429 errors, preventing us from reaching the target load.

This is actually a known issue… with how the platform handles bursty WebSocket connections during load testing. The 429 Too Many Requests error indicates that the client-side connection rate has exceeded the platform API limits for session creation in a short window.

To resolve this, implement exponential backoff logic in your JMeter script. Additionally, ensure your OAuth token refresh mechanism is not contributing to the load. Distribute the connection attempts over a longer ramp-up period to stay within the rate limits at scale.