What is the reason this setting causes immediate 429 errors when JMeter threads hit 100 concurrent connections? Running load tests from Singapore targeting the predictive routing queue endpoint.
The API docs mention rate limits but do not specify the exact threshold for PR capacity checks. Using basic auth and standard JSON payloads for the test.
Need to know if this is a hard limit or if specific headers can bypass the throttle for testing purposes.
The best way to fix this is to decouple the load generation from the Predictive Routing (PR) capacity calculation logic. When you hit 100 concurrent threads in JMeter, you are not just testing API latency; you are triggering the platform’s internal concurrency limits for outbound dialing attempts. The 429 error is not a generic rate limit but a specific protection mechanism against PR queue overload.
Instead of simulating full dial attempts, configure your JMeter script to use a “dry run” mode if your custom API allows it, or more effectively, throttle the request rate to match the actual trunk capacity of your BYOC setup. Since you are in Singapore, ensure your test accounts are routed through the same region-specific endpoints to avoid cross-region latency penalties that exacerbate timeout issues.
Adjust your JMeter Thread Group settings:
X-Cisco-Marketing-Opt-Out headers if required by your carrier configuration, as missing headers can cause immediate rejection before hitting the PR engine.The core issue is that PR calculates capacity based on available trunks and active calls. If your test exceeds the configured trunk limits, the platform drops the requests to protect live production traffic. Verify your outbound routing rules in Architect to ensure they are not inadvertently looping or failing over incorrectly during the test window.
Check these related concepts:
You need to align your load testing strategy with the actual operational constraints of the Predictive Routing engine. The suggestion above regarding decoupling logic is technically sound, but it misses the critical business context regarding how capacity is calculated in the Performance Dashboard.
Cause:
The 429 status code here is not a standard API rate limit. It is a protective circuit breaker triggered when the Predictive Routing (PR) engine detects that the incoming request volume exceeds the calculated available agent capacity. In the Europe/Paris timezone, our peak occupancy metrics often show a 15% variance during load spikes. The PR engine uses a specific algorithm to estimate available agents based on historical ACD data and current wrap-up times. When JMeter simulates 100 concurrent connections, it artificially inflates the “available capacity” calculation, causing the engine to reject requests to protect agent experience. This is documented behavior for preventing queue overload, not a bug in the authentication headers.
Solution:
Adjust the JMeter script to simulate realistic agent availability rather than raw API calls. You must configure the test to respect the max_concurrent_attempts parameter defined in your PR campaign settings.
capacity field in the JSON payload matches the values reported in the Queue Performance view.{
"campaign_id": "your_campaign_id",
"max_concurrent_attempts": 25,
"capacity": 25
}
This approach ensures that the load test reflects true operational limits. Monitoring the Conversation Detail View during these tests will provide the necessary visibility into whether the rejections are due to capacity exhaustion or configuration errors. This method prevents the 429 errors while providing accurate data for capacity planning.
If I remember right, the X-Genesys-PR-Capacity header must be explicitly set in JMeter to simulate actual dialer load without triggering the circuit breaker. Without it, the platform defaults to a conservative estimate, causing immediate 429 errors. Ensure your OAuth token includes the predictive_routing:write scope as well.