WebSocket disconnects during high-concurrency WhatsApp load test

General Discussion
1

Connection reset by peer

Background

Running a load test for WhatsApp inbound messages using JMeter. The goal is to simulate 500 concurrent agents receiving messages simultaneously to validate capacity. Environment is Genesys Cloud US-East. Using the standard Conversation API to subscribe to events.

Issue

After 150 concurrent connections, the WebSocket starts dropping. The error log shows Connection reset by peer immediately after the subscribe call returns 200 OK. The flow in Architect is simple: receive message → log timestamp. No complex logic. The throughput drops to near zero after the initial burst.

Troubleshooting

  • Checked API rate limits in the admin console. Current usage is well below the limit for our tier.
  • Increased the thread group ramp-up time in JMeter from 10s to 60s. The issue persists, just happens later in the test.
  • Verified the WebSocket URL is correct and using the latest SDK version (Java 2.5.0).
  • Tried reducing concurrency to 100. Test passes without errors.

Is there a hidden limit on simultaneous WebSocket subscriptions per user or per organization? The documentation mentions general rate limits but not specific concurrent connection caps for messaging channels. Need to understand if this is a configuration error or a platform constraint.

2

Check your WebSocket subscription limits and payload size. For high-concurrency WhatsApp testing, direct event streams often hit rate limits before agent capacity.

  1. Switch to the Conversation API polling endpoint.
  2. Batch requests to 500 messages per call.
  3. Verify your S3 export jobs are not blocking API threads.

This prevents connection resets during load spikes.

3

I’d suggest checking out at the WebSocket subscription limits and payload size. For high-concurrency WhatsApp testing, direct event streams often hit rate limits before agent capacity.

Switch to the Conversation API polling endpoint. Batch requests to 500 messages per call. Verify your S3 export jobs are not blocking API threads. This prevents connection resets during load spikes.

4

You need to configure exponential backoff in the JMeter HTTP Request Default Configurator to handle 429 errors gracefully. The WebSocket disconnects are likely caused by hitting rate limits before the connection resets. Implement a retry mechanism that doubles the wait time after each failure. This prevents the “Connection reset by peer” errors during high-concurrency spikes.

<HTTPSamplerProxy guiclass="HttpTestSampleGui" testclass="HTTPSamplerProxy" testname="WhatsApp WebSocket" enabled="true">
 <elementProp name="HTTPsampler.Arguments" elementType="Arguments" guiclass="HTTPArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
 <collectionProp name="Arguments.arguments"/>
 </elementProp>
 <stringProp name="HTTPSampler.method">GET</stringProp>
 <stringProp name="HTTPSampler.path">/api/v2/communications/websocket</stringProp>
</HTTPSamplerProxy>

Add a Constant Timer to space out requests. This mimics natural agent behavior and reduces load on the Genesys Cloud API.