wu-sheng
commented
5 years ago If my understanding is correct what would you guys recommend to tackle this issue?
I think most of your understanding is correct, the thread model of vert.x is a typical model in RPC framework. Also, SkyWalking did request the TracingContext working in that way, most of tracing system asked for this too.
The key is, you created the span in a shared thread(that single thread, I am guessing this is nio/vertx event loop thread). SkyWalking is focusing on business logic, the span could be created at the entrance of business codes, such as we did for SpringMVC. We create span at Controller edge, then, no matter which web container is used inside, the span will work as expected.
Like in the codes
public class MyServer extends AbstractVerticle {
@Override
public void start() {
Router router = Router.router(vertx);
router.route().handler(this::queryHandler);
vertx.createHttpServer().requestHandler(router::accept)
.listen(8080);
System.out.println("MyServer startup");
}
private void queryHandler(RoutingContext routingContext) {
routingContext.response()
.putHeader("content_type", "application/json")
.end("hello world");
}Span should be created when #requestHandler called, there should not be a shared thread at this point, because it can't in Java thread model, the requestHandler will hold the thread until it is done or start a child thread(that is context capture/continue designed for)
BFergerson
vietj
codefromthecrypt
Please answer these questions before submitting your issue.
Question
I am creating a plugin for supporting Vert.x powered applications using SkyWalking. Everything appears to work when I spread out the events so they each happen one after the other but once I start letting the messages flow naturally SkyWalking won't finish a single span.
For example:
/products/test(this creates an ExitSpan)/products/test(this creates an EntrySpan)/products/test(this closes the EntrySpan)/products/test(this closes the ExitSpan)The above works correctly and the SkyWalking UI appears to agree. It's when the flow of events changes that SkyWalking will not finish a trace.
For example:
/products/test(this creates an ExitSpan)/products/test(this creates an ExitSpan, child of previous)/products/test(this creates an EntrySpan, child of previous)/products/test(this creates an EntrySpan, child of previous)/products/test(this closes the EntrySpan, child of previous)/products/test(this closes the EntrySpan, child of previous)/products/test(this closes the ExitSpan, child of previous)/products/test(this closes the ExitSpan)In the above example, SkyWalking would eventually finish a trace but it would be the single trace instead of the expected two traces. The reason I say that SkyWalking never finishes a trace is that I have the above occurring every second and since SkyWalking keeps adding spans as the child of the previous it keeps a non-empty span stack and continues without finishing any traces.
From my best understanding of what's happening, the
TracingContextclass requires either of two scenarios to create a new trace:TracingContext.activeSpanStackis emptyIf that's correct then I don't see how I can get this to work with Vert.x. In this case, Vert.x is using the same thread to run all of the events on. Both of the GET requests, both of the GET receives, and both of the GET responses happen on the same thread and I can't simply use the
InstanceMethodsAroundInterceptor.afterMethodmethod to close spans because of the asynchronous nature of Vert.x.If my understanding is correct what would you guys recommend to tackle this issue?
Which version of SkyWalking, OS and JRE?
SkyWalking 6.0.0 GA, Ubuntu 18.04, Java 8