WebSocket request-response Samplers Failed

[Sachin Sinkar]

Hi Team,

I have created a test plan for load testing a websocket based GPT chatbot. I have set ramp-up period of 400 sec the test plan works well for 100 threads with no error but when I increased to 500 threads the WebSocket request-response Samplers fails, it gives me below error.

Response code:Sampler error Response message:Sampler error: java.lang.ClassCastException: class eu.luminis.websocket.PingFrame cannot be cast to class eu.luminis.websocket.DataFrame (eu.luminis.websocket.PingFrame and eu.luminis.websocket.DataFrame are in unnamed module of loader org.apache.jmeter.DynamicClassLoader @548c4f57)

Will you please suggest me a solution for the above error.

[DT]

It might indicate one of the following:

• The system under test is overloaded can cannot respond with a proper WebSocket frame, it indicates defect connected with concurrency
• JMeter is overloaded and cannot properly parse responses/build requests. In this case make sure to follow JMeter Best Practices and if the issue still remains - consider finding another load generator machine and run JMeter in distributed mode