Digital Messaging WebSocket Dropouts During 5k Concurrent User Load Test

General Discussion
1

Could someone explain the behavior of WebSocket disconnections when simulating high-concurrency digital messaging traffic in Genesys Cloud? We are conducting a capacity validation for a new omnichannel deployment and are seeing unexpected connection resets.

Environment Details:

  • Genesys Cloud Version: 10.5 (Production Org)
  • Load Testing Tool: JMeter 5.6.2 with WebSocket Samplers
  • Target Endpoint: /api/v2/analytics/conversations/details/query (for monitoring) and standard WebSocket endpoint for message streaming.
  • Simulated Load: 5,000 concurrent users initiating chat sessions over a 30-minute ramp-up period.

The issue manifests after approximately 1,200 concurrent active sessions. The JMeter logs show a sudden spike in WebSocketClosedException errors. The server returns a close code of 1006 (Abnormal Closure) rather than a clean 1000 (Normal Closure). This happens consistently at the same concurrency threshold, suggesting a hard limit or a resource exhaustion issue on the platform side, rather than random network noise.

We have verified that the API rate limits for the REST endpoints used to initiate the conversations are not being hit (no 429 errors). The problem is strictly within the persistent WebSocket connections. We are also monitoring the Architect flow for the chat interaction, which includes a simple IVR and then a queue assignment. There are no complex data actions or external API calls that would cause a delay in the handshake.

Is there a documented limit on concurrent WebSocket connections per organization or per user token? Or is this a sign that we need to implement a different connection pooling strategy in our load test configuration? We want to ensure our infrastructure can handle the projected Black Friday traffic without dropping customer messages.

Any insights on how other load testing engineers handle WebSocket scaling in Genesys Cloud would be appreciated.

Thanks for the help.

2

Make sure you inspect the raw WebSocket handshake and the subsequent keep-alive intervals being sent by your JMeter script. The connection resets you are observing during a 5k concurrent user simulation are rarely caused by Genesys Cloud’s WebSocket server dropping connections arbitrarily. Instead, this behavior typically points to a mismatch in the ping/pong mechanism or an incorrect upgrade header configuration in the load test client.

When simulating digital messaging traffic, the client must adhere strictly to the WebSocket specification for maintaining state. If the JMeter sampler is not sending a ping frame within the expected timeout window, or if the initial HTTP upgrade request lacks the correct Sec-WebSocket-Protocol headers, the server will terminate the connection to free up resources. Review the JMeter WebSocket sampler configuration to ensure the ping_interval is set to a value lower than the server’s idle timeout. Additionally, verify that the connection is not being terminated prematurely due to SSL renegotiation failures under high concurrency. Adjusting these parameters usually stabilizes the session during heavy load testing scenarios.

3

Have you tried aligning the JMeter WebSocket keep-alive intervals with the specific digital messaging channel settings? The suggestion above hits the nail on the head regarding handshake mismatches.

In our Chicago WFM setup, we see similar instability when external tools don’t respect the platform’s heartbeat requirements. Verify the ping frequency matches the Genesys Cloud defaults to prevent premature timeouts during high concurrency.