Stuck on Architect flow timeout during JMeter burst testing

Stuck on a weird behavior in Genesys Cloud Architect when pushing concurrent sessions through a simple IVR flow.

We are running a load test from our Singapore office (Asia/Singapore timezone) using JMeter 5.6. The goal is to simulate a burst of 500 simultaneous inbound calls hitting a single ‘Gather Input’ block followed by a ‘Transfer to Queue’ block. The environment is a standard production tenant, not a sandbox.

Here is the setup:

• JMeter Config: Thread Group with 500 threads, Ramp-Up Period of 0 seconds (instant burst), Loop Count 1.
• API Endpoint: We are triggering the calls via the POST /api/v2/interactions endpoint to simulate inbound interactions.
• Architect Flow: Very basic. Start → Gather Input (timeout 30s) → Transfer to Queue (Queue ID: 12345).

The problem occurs exactly when the concurrent connections hit around 350. The JMeter dashboard shows a spike in latency, and then we start seeing a mix of errors:

1. HTTP 502 Bad Gateway on the interaction creation API.
2. Architect Flow Timeout: The interactions that do get created seem to hang in the ‘Gather Input’ block. They never progress to the queue. The debug logs in Architect show the interaction state as IN_PROGRESS but no audio is bridged. It just sits there until the 30s timeout hits, then it fails with a FLOW_EXECUTION_ERROR.

This is strange because the queue has 50 available agents and no capacity limits set. The issue seems to be on the platform side handling the burst, not our queue configuration.

I have checked the API rate limits in the Admin console, and we are nowhere near the global limit for POST /interactions. However, I suspect there might be a hidden per-tenant or per-flow concurrency limit for Architect executions that isn’t documented clearly for beginners like myself.

Has anyone seen this specific pattern where the flow hangs before the transfer during a burst? Is there a way to configure the Architect flow to handle higher concurrency, or is this a platform-side throttling issue we need to raise with support? Any advice on tweaking the JMeter script to stagger the load more gently would also be appreciated, though we really need to test the burst capacity.

“Stuck on a weird behavior in Genesys Cloud Architect when pushing concurrent sessions…”

While my day is usually consumed by shift swaps and adherence reports, I’ve seen this during peak scheduling windows. It is often an upstream capacity issue. Check if the target queue has enough agents scheduled. If not, the flow hangs waiting for a resource that does not exist.

TL;DR: Timeout stems from queue capacity limits, not just agent count.

The documentation actually says that while scheduling agents is necessary, it is not sufficient to prevent flow timeouts during burst testing. The primary bottleneck is usually the queue’s max_wait_time or the max_callers configuration. If the queue is saturated, the flow blocks until the timeout expires, causing the 500 errors seen in JMeter logs.

Check the queue settings in the Admin console. Ensure max_callers is set to a value significantly higher than your burst size (e.g., 1000+ for testing). Additionally, verify that the max_wait_time is not set to a low value like 30 seconds. For load testing, it is safer to set this to a higher threshold temporarily.

Also, review the Architect flow’s Transfer to Queue block. Ensure the timeout parameter is explicitly set. If left default, it may inherit restrictive tenant settings. Adjusting these two parameters usually resolves the hanging issue. Monitor the queue_stats endpoint during the test to confirm callers are entering the queue before timing out.

This looks like a provider state drift issue rather than a pure capacity problem. Do not rely on manual queue tuning for burst tests; automate the genesyscloud_routing_queue resource in Terraform to ensure max_wait_time and max_callers match the test parameters exactly.