POST /api/v2/outbound/campaigns returns HTTP 429 Too Many Requests. The response header shows Retry-After: 1. We are running a JMeter script to simulate a ramp-up of 50 concurrent users creating test campaigns. The goal is to check the API throughput limits for the outbound module. The environment is Genesys Cloud US1. The JMeter thread group has a ramp-up period of 10 seconds. Each thread sends a JSON payload with a basic campaign definition. The error starts appearing when the concurrency hits 20 users per second. The standard rate limit for this endpoint is 300 requests per minute per tenant. We are hitting the limit very fast. The JSON payload size is small, around 500 bytes. We tried adding a constant timer in JMeter to space out the requests, but the 429 errors persist. The issue seems to be related to how the rate limiter counts concurrent sessions versus total requests. Is there a specific header we need to include to bypass the tenant-wide limit for testing? Or is this a hard limit that cannot be increased for load testing purposes? We need to validate the system capacity before go-live.
Make sure you review the rate limiting documentation for the Outbound module, as it enforces strict request quotas to prevent system overload. The 429 error indicates that the JMeter simulation has exceeded the allowed requests per second for campaign creation endpoints.
- Reduce the concurrent thread count in your JMeter script. Start with 5-10 threads to establish a baseline throughput metric.
- Implement a fixed delay or constant timer between requests. A 2-second pause per request often aligns with the standard rate limits for resource creation.
- Monitor the
Retry-Afterheader values dynamically. If the value increases, the platform is throttling your IP address due to sustained high load.
This approach ensures that your load test reflects realistic business usage patterns rather than triggering defensive security measures. The performance dashboard can then be used to observe how the system handles gradual ramp-ups, providing more accurate insights into queue activity and agent allocation limits during peak times. Avoid testing at maximum capacity immediately, as this often obscures true system behavior.
The simplest way to resolve this is to implement an exponential backoff mechanism in your JMeter script that strictly adheres to the Retry-After header values returned by the Genesys Cloud API, rather than relying on static delays which often fail under variable load conditions. When the outbound module enforces rate limits, ignoring the specific retry window causes immediate 429 responses and can lead to temporary IP throttling, especially when simulating high-concurrency scenarios like 50 concurrent users ramping up in 10 seconds. The standard approach of using a constant timer is insufficient because the API’s rate limit counter resets dynamically based on tenant load, not just request intervals. Instead, use a JSR223 PostProcessor in JMeter to parse the response headers and calculate the precise wait time. This ensures that subsequent requests are only sent after the server has explicitly indicated readiness, preventing further 429 errors and allowing the test to accurately measure the true throughput limits without artificial suppression.
import groovy.json.JsonSlurper
def responseHeaders = prev.getResponseHeaders()
def retryAfter = responseHeaders["Retry-After"]
if (retryAfter != null) {
def waitTime = retryAfter[0].toInteger() * 1000 // Convert seconds to milliseconds
log.info("Rate limited. Waiting ${waitTime}ms as per Retry-After header.")
Thread.sleep(waitTime)
prev.setNextHop(true) // Mark for retry if using a Loop Controller
} else {
log.info("No Retry-After header found. Proceeding normally.")
}
Integrating this dynamic retry logic will stabilize your load test results and provide a more accurate assessment of the outbound API’s capacity under sustained digital channel traffic spikes.