Clarification on "multiple async requests simultaneously" deficiency in TracingInterceptor

[william-tran]

When using TracingInterceptor:

when doing multiple async requests simultaneously, parent spans created before invoking the client are not properly inferred.

Does this effect auto-instrumentation projects like java-specialagent and the new opentelemetry-java-instrumentation? Specialagent appends the TracingInterceptor to the return value whenever OkHttpClient.interceptors() and OkHttpClient.networkInterceptors() are called. The OTel project instruments at the OkHttpClient(OkHttpClient.Builder) constructor by adding its own TracingInterceptor to the Builder.

[pavolloffay]

Does this effect auto-instrumentation projects like java-specialagent and the new opentelemetry-java-instrumentation?

Could you please clarify? If you want to use just the agents then raise the issue there. I don't know if they use this instrumentation or not.

[william-tran]

As I described above, those agent projects do use this instrumentation or something that looks like it. But I should rephrase my question. Let's say I'm a contributor to those projects and I notice your note "when doing multiple async requests simultaneously..." and I think "well it looks like we have a problem". I'm trying to understand why there is a problem, the mechanism behind it, and how you came about your conclusion. The way these agents work and the way the OKHttp API works make it difficult to use TracingCallFactory in a way that's transparent to the application code, and its not obvious to my why using TracingInterceptor could be a problem in multiple async requests, assuming the span context correctly propagates from the caller thread to the executor thread.

[pavolloffay]

I don't exactly remember why, but the brave documents the same problem https://github.com/openzipkin/brave/tree/master/instrumentation/okhttp3#tracinginterceptor

Maybe this test could help you understand the problem https://github.com/opentracing-contrib/java-okhttp/blob/master/opentracing-okhttp3/src/test/java/io/opentracing/contrib/okhttp3/TracingInterceptorTest.java#L20