Virtual Thread model breaks tracing

[isimsizolan]

Description

Vert.x has 3 different thread models, worker, vthreads and standart. For high performance web application api we are using ThreadingModel.VIRTUAL _THREAD. However this model breaks tracing (open telemetry, datadog etc), spans are bind together.
If threading model switched to ThreadingModel.WORKER which is the only change, tracing works expectedly and spans bind together correctly.

Version

4.5.10

Context

When using vert.x virtual thread model, tracing breaks (datadog, opentelemetry etc.)

Do you have a reproducer?

Code:

package com.example.starter;

import io.vertx.core.DeploymentOptions;
import io.vertx.core.ThreadingModel;
import io.vertx.core.http.HttpServerOptions;
import io.vertx.rxjava3.core.AbstractVerticle;
import io.vertx.rxjava3.core.http.HttpServer;
import io.vertx.rxjava3.ext.web.Router;

import java.time.LocalDateTime;

public class MainVerticle extends AbstractVerticle {

  @Override
  public void start() throws Exception {
    DeploymentOptions deploymentOptions = new DeploymentOptions().setThreadingModel(ThreadingModel.WORKER);

    vertx.deployVerticle(new HttpServerVerticle(), deploymentOptions).subscribe(s -> {
      vertx.deployVerticle(new MyWebClientVerticle(), deploymentOptions).subscribe(webcleintDeploy -> {
        HttpServer server = vertx.createHttpServer(
          new HttpServerOptions()
        );

        Router router = Router.router(vertx);

        router.get("/").handler(ctx -> {
          // send a message to the event bus
          vertx.eventBus().rxRequest(Constants.EB_REQUEST_1, LocalDateTime.now().toString())
            .subscribe(reply -> {
              ctx.response().end(reply.body().toString());
            });
        });

        router.get("/api").handler(ctx -> {
          // send a message to the event bus
          vertx.eventBus().rxRequest(Constants.EXTERNAL_HTTP_REQUEST, LocalDateTime.now().toString())
            .subscribe(reply -> {
              ctx.response().end(reply.body().toString());
            });
        });

        router.get("/health").handler(ctx -> {
          vertx.eventBus().rxRequest(Constants.HEALTH, ctx.request().method().toString())
            .subscribe(reply -> {
              ctx.response().end(reply.body().toString());
            });
        });

        server.requestHandler(router).listen(8888).subscribe();
        System.out.println("HttpServerVerticle deployed");
      });
    });
  }
}

[tsegismont]

Can you please update the description? It seems the same piece of code is repeated in image/text formats, but some verticle snippets are missing.

The description must let us understand how to reproduce the problem. Otherwise, we can only guess.

[isimsizolan]

Can you please update the description? It seems the same piece of code is repeated in image/text formats, but some verticle snippets are missing.

The description must let us understand how to reproduce the problem. Otherwise, we can only guess.

Sorry for inconvenience,

Description updated. Using ThreadingModel.VIRTUAL_THREAD causing tracing spans not binding together. Single change to ThreadingModel.WORKER fixes but WORKER model is not what we needed.

[tsegismont]

Thanks for the update, but can you also add snippets of the other verticles that are deployed and instructions about requests to run so that we can try to reproduce? Thank you

[isimsizolan]

Full code added. @tsegismont
TracingTests.zip

[tsegismont]

Thanks, I'll look into this as soon as I can