Using the Java agent method resulted in the metadata being updated and the tarcepartment being generated during the GRPC callback

[WuChuhan]

I used a Java agent to start OpenTelemetry in the project, but initiating another GRPC request during the GRPC callback process would cause a change in the traceid. Is it because every time we arrive at a new GRPC client, a new metadata is added, and during the last GRPC callback process, the traceparent information cannot be passed down, and the agent method itself cannot cover this scenario?

[laurit]

Please provide a minimal sample app along with any necessary instructions that allows for reproducing this issue.

[WuChuhan]

`public String callSayHello() {
logger.info("==============callSayHello start==============");
doSomething();
HelloRequest request = HelloRequest.newBuilder().setGreeting("world").build();
HelloResponse response;
try {
response = blockingStub.sayHello(request);
logger.info("callSayHello get reply: " + response.getReply());
} catch (StatusRuntimeException e) {
logger.warning("RPC failed: " + e.getStatus());
return "fail";
}
return "success";
}

@GetMapping("/callSayHelloClientStream")
public String callSayHelloClientStream() throws InterruptedException {
logger.info("==============callSayHelloClientStream start==============");
final CountDownLatch finishLatch = new CountDownLatch(1);

    StreamObserver<HelloResponse> responseObserver = new StreamObserver<HelloResponse>() {
        @Override
        public void onNext(HelloResponse helloResponse) {
            HelloRequest request = HelloRequest.newBuilder().setGreeting("world2").build();
            HelloResponse response = blockingStub.sayHello(request);
            logger.info("CallSayHelloClientStream get reply: " + helloResponse.getReply());
        }

        @Override
        public void onError(Throwable t) {
            logger.warning("CallSayHelloClientStream Failed: " + Status.fromThrowable(t));
            finishLatch.countDown();
        }

        @Override
        public void onCompleted() {
            logger.info("Finished CallSayHelloClientStream");
            finishLatch.countDown();
        }
    };

    StreamObserver<HelloRequest> requestObserver = asyncStub.sayHelloClientStream(responseObserver);
    try {
        for (int i = 0; i < 5; i++) {
            HelloRequest request = HelloRequest.newBuilder().setGreeting("world" + i).build();
            requestObserver.onNext(request);
            if (finishLatch.getCount() == 0){
                return "success";
            }
        }
    } catch (StatusRuntimeException e) {
        requestObserver.onError(e);
        return "fail";
    }

    // Mark the end of requests
    requestObserver.onCompleted();

    if (!finishLatch.await(1, TimeUnit.MINUTES)) {
        logger.warning("CallSayHelloClientStream can not finish within 1 minutes");
    }

    return "success";
}`

[WuChuhan]

When I make a request again in the GRPC callback, there is no traceparent in the metadata, which makes it impossible to achieve traceability.

[laurit]

Please provide a fully functional sample app as a github repository or a zip along with any instructions necessary to reproduce your issue.