WebSocket Read Sampler doesn't capture the message - websocket

Question

I was doing some load testing against a WebSocket to measure the message latency between a publisher (presenter) and subscriber (participant). Below is the structure of my test plan. The "Setup" TG is a setUp thread group to make sure that both publisher and subscriber are connected to the WebSocket before starting the communication to measure the latency.
I had a JSR223 PostProcessor to cache the connection for publisher and subscriber accordingly so that they can pick up the same connection in the following thread groups. 3 messages were sent out from the publisher correctly. However, not sure why the read sampler in the subscriber (ParticipantA) Thread Group did not capture any message even after I increased the timeout to 20s.
Here is the JSR223 PostProcessor for caching the connection:
def participantAConnection = sampler.threadLocalCachedConnection
props.put('participantAConnection' + ctx.getThreadNum(), participantAConnection.get())
Here is the JSR223 PreProcessor for restoring the connection in the Participant Thread Group.
def participantAConnection = props.get('participantAConnection' + ctx.getThreadNum())
sampler.threadLocalCachedConnection.set(participantAConnection)
I can see the properties for the cached connection for the presenter and participant in the debug sampler.
participantAConnection0=eu.luminis.websocket.WebSocketClient#1b510239
presenterConnection0=eu.luminis.websocket.WebSocketClient#755f44c9
The debug log was enabled below:
2022-07-13 01:06:49,666 DEBUG e.l.j.w.SingleReadWebSocketSampler: I/O Error in sampler 'participantACommandsRead'.
java.net.SocketTimeoutException: Read timed out
at sun.nio.ch.NioSocketImpl.timedRead(NioSocketImpl.java:280) ~[?:?]
at sun.nio.ch.NioSocketImpl.implRead(NioSocketImpl.java:306) ~[?:?]
at sun.nio.ch.NioSocketImpl.read(NioSocketImpl.java:347) ~[?:?]
at sun.nio.ch.NioSocketImpl$1.read(NioSocketImpl.java:800) ~[?:?]
at java.net.Socket$SocketInputStream.read(Socket.java:966) ~[?:?]
at sun.security.ssl.SSLSocketInputRecord.read(SSLSocketInputRecord.java:478) ~[?:?]
at sun.security.ssl.SSLSocketInputRecord.readHeader(SSLSocketInputRecord.java:472) ~[?:?]
at sun.security.ssl.SSLSocketInputRecord.bytesInCompletePacket(SSLSocketInputRecord.java:70) ~[?:?]
at sun.security.ssl.SSLSocketImpl.readApplicationRecord(SSLSocketImpl.java:1455) ~[?:?]
at sun.security.ssl.SSLSocketImpl$AppInputStream.read(SSLSocketImpl.java:1059) ~[?:?]
at java.io.BufferedInputStream.fill(BufferedInputStream.java:244) ~[?:?]
at java.io.BufferedInputStream.read(BufferedInputStream.java:263) ~[?:?]
at eu.luminis.websocket.Frame.parseFrame(Frame.java:61) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at eu.luminis.websocket.WebSocketClient.receiveFrame(WebSocketClient.java:420) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at eu.luminis.jmeter.wssampler.WebsocketSampler.readFrame(WebsocketSampler.java:306) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at eu.luminis.jmeter.wssampler.SingleReadWebSocketSampler.readFrame(SingleReadWebSocketSampler.java:83) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at eu.luminis.jmeter.wssampler.SingleReadWebSocketSampler.doSample(SingleReadWebSocketSampler.java:71) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at eu.luminis.jmeter.wssampler.WebsocketSampler.sample(WebsocketSampler.java:169) ~[jmeter-websocket-samplers-1.2.8.jar:?]
at org.apache.jmeter.threads.JMeterThread.doSampling(JMeterThread.java:651) ~[ApacheJMeter_core.jar:5.5]
at org.apache.jmeter.threads.JMeterThread.executeSamplePackage(JMeterThread.java:570) ~[ApacheJMeter_core.jar:5.5]
at org.apache.jmeter.threads.JMeterThread.processSampler(JMeterThread.java:501) ~[ApacheJMeter_core.jar:5.5]
at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:268) ~[ApacheJMeter_core.jar:5.5]
at java.lang.Thread.run(Thread.java:833) ~[?:?]

Answer 1

Your approach seems to be okayish, the question why you're getting timeouts is different.
Try to put publisher and subscriber samplers into a single Thread Group and see if this works for you
If it does most probably there is an errors somewhere, but we cannot state where without seeing your full test plan, full code or at least jmeter.log file with debug logging enabled for (at least) WebSocket Samplers. This line needs to be added to log4j2.xml file:
<Logger name="eu.luminis" level="debug" />