I would like to measure the TPS and response time at the beginning of trace data to evaluate the system's processing performance.

[zerocooldog]

Looking into the OTEL instrumentation module, I found that there are advice classes related to servlets.

https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/instrumentation/servlet

And by registering a CustomSpanProcessor, I get that the context object in the onStart method of the SpanProcessor logs information such as HttpRouteState or opentelemetry-servlet-app-server-bridge.

-CustomSpanProcc

public class Hamonica2SpanProcessor implements SpanProcessor {
    private final Logger log = Logger.getLogger(getClass().getName());
    private static final ContextKey<HttpRouteState> KEY =
            ContextKey.named("opentelemetry-http-server-route-key");
    @Override
    public void onStart(Context context, ReadWriteSpan readWriteSpan) {

        HttpRouteState httpRouteState = context.get(KEY);
        log.log(Level.SEVERE,"###### start context : {0}", new Object[]{context});
        log.log(Level.SEVERE,"###### start httpRouteState  : {0}", new Object[]{httpRouteState});
    }

...
...
}

• context Object toString

 {opentelemetry-http-server-route-key=io.opentelemetry.javaagent.shaded.instrumentation.api.internal.HttpRouteState@2e184ef5, opentelemetry-servlet-app-server-bridge=io.opentelemetry.javaagent.bootstrap.servlet.AppServerBridge@20dfb546}

Here are my questions:

1. Can TPS or response time be measured during tracing using the SpanProcessor?
   If yes, could you provide guidance on how to implement it?

2. I'm unable to retrieve the HttpRouteState value using context.get(KEY);. The log outputs null. Am I using it incorrectly? When I log the context object itself, it appears to contain values.

3. Would it be a better choice to create a separate advice class to add TPS or response time as metrics?
   I’m asking because I don’t want to modify the existing advice classes or convert them using ByteBuddy.