Autoconfigured GlobalOpenTelemetry not flushing spans on shutdown, v1.23.0

[rossabaker]

Describe the bug
Using GlobalOpenTelemetry with auto-configuration enabled, the application is no longer flushing spans in the JVM shutdown hook. If I sleep for some time at the end of the main method, it works. It works reliably without sleep on 1.22.0.

Steps to reproduce

I am running the following code:

import io.opentelemetry.api.GlobalOpenTelemetry;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.context.Scope;

class PlainJava {
    public static void main(String[] args) throws Exception {
        OpenTelemetry openTelemetry = GlobalOpenTelemetry.get();
        Tracer tracer = openTelemetry.getTracer("plain-java", "1.0.0");
        Span span = tracer.spanBuilder("my span").startSpan();
        try (Scope ss = span.makeCurrent()) {
            // In this scope, the span is the current/active span
        } finally {
            span.end();
        }
        // Thread.sleep(10000);
    }
}

This is running with -Dotel.java.global-autoconfigure.enabled=true and no other otel-related system properties or environment variables. A local Jaeger is listening on port 4317.

What did you expect to see?
I expected to see a trace with my span in my local Jaeger UI.

What did you see instead?
No trace was received.

What version and what artifacts are you using?
Artifacts:

• opentelemetry-sdk
• opentelemetry-sdk-extension-autoconfigure
• opentelemetry-exporter-otlp

Version: v1.23.0
How did you reference these artifacts? From SBT:

    libraryDependencies ++= Seq(
      "io.opentelemetry" % "opentelemetry-exporter-otlp" % OpenTelemetryVersion,
      "io.opentelemetry" % "opentelemetry-sdk" % OpenTelemetryVersion,
      "io.opentelemetry" % "opentelemetry-sdk-extension-autoconfigure" % s"${OpenTelemetryVersion}-alpha"
    ),
    run / fork := true,
    javaOptions += "-Dotel.java.global-autoconfigure.enabled=true"

Environment
Compiler: Azul Systems, Inc. Java 19.0.1
OS: MacOS Ventura 13.1

Additional context

• It works as expected on 1.22.0
• I built opentelemetry-java locally, and can confirm OpenTelemetry.close() is called and that shutdown completes successfully.
• The changes in 4df4a0a seem relevant, but I don't see a problem.
• I originally hit this in Scala's otel4s, but I've minimized it to pure Java aside from the build. I can throw together a POM to completely eliminate Scala, but I don't think that's it.

[jack-berg]

I can verify that this is a bug. Looks like I botched the ordering of the shutdown hook and its not operating on the OpenTelemetrySdk instance that ends up being used.

@jkwatson we should issue a patch for this. @trask can we hold off on the instrumentation release to incorporate the patch?

[trask]

@trask can we hold off on the instrumentation release to incorporate the patch?

👍