Issue: ETW Exporter Tracer Uses a Single Trace ID for All Spans

[lukeina2z]

The ETW Exporter provides its own tracer implementation, which inherits from the OpenTelemetry Tracer interface. The relevant code is here:
https://github.com/open-telemetry/opentelemetry-cpp/blob/main/exporters/etw/include/opentelemetry/exporters/etw/etw_tracer.h#L162C28-L163

Expected Behavior (OpenTelemetry C++ SDK)

Using the standard OpenTelemetry SDK, two spans created with the default tracer correctly receive different Trace IDs. Here is the example code used to verify this behavior:

  void TestOTelTracer()
  {
    auto ostream_exporter = opentelemetry::exporter::trace::OStreamSpanExporterFactory::Create();
    auto ostream_processor = opentelemetry::sdk::trace::SimpleSpanProcessorFactory::Create(std::move(ostream_exporter));

    std::vector<std::unique_ptr<opentelemetry::sdk::trace::SpanProcessor>> processors;
    processors.push_back(std::move(ostream_processor));

    auto resource_attributes = opentelemetry::sdk::resource::ResourceAttributes{ {"service.name", "Test OTel"} };
    auto resource_ptr = opentelemetry::sdk::resource::Resource::Create(resource_attributes);

    std::unique_ptr<opentelemetry::sdk::trace::TracerContext> context =
      opentelemetry::sdk::trace::TracerContextFactory::Create(std::move(processors), resource_ptr);

    auto traceProvider = opentelemetry::sdk::trace::TracerProviderFactory::Create(std::move(context));
    auto tracer = traceProvider->GetTracer("OTel-Tracer-Foo");

    {
      auto spanFoo = tracer->StartSpan("Span-Foo");
    }

    {
      auto spanBar = tracer->StartSpan("Span-Bar");
    }
  }

As shown in the screenshot, spans Foo and Bar have distinct Trace IDs, which is the correct behavior.

Actual Behavior (ETW Exporter Tracer)

Using the ETW Exporter Tracer, based on the sample provided here:
https://github.com/open-telemetry/opentelemetry-cpp-contrib/blob/main/exporters/geneva-trace/example/main.cc
Both spans Foo and Bar end up with identical Trace IDs, which is incorrect.

  void TestEtwTracer()
  {
    auto traceProvider = std::make_unique<opentelemetry::exporter::etw::TracerProvider>();
    auto tracer = traceProvider->GetTracer("Geneva-Tracer-Foo");

    {
      auto spanFoo = tracer->StartSpan("Span-Foo");
    }

    {
      auto spanBar = tracer->StartSpan("Span-Bar");
    }
  }

00000012	Geneva-Tracer-Foo	44052	44428	4	0	02\05\2026-13:25:30:652	{"duration":69100,"env_dt_spanId":"8c8974003664fa4e","env_dt_traceId":"8507dcdc651af34fb8f21152a98e2977","env_name":"Span","env_time":"2026-02-05T21:25:30.652491600Z","kind":1,"name":"Span-Foo","startTime":"2026-02-05T21:25:30.652422500Z","statusCode":0,"statusMessage":"","success":"True","meta":{"provider":"Geneva-Tracer-Foo","event":"Span","time":"2026-02-05T13:25:30.652","cpu":4,"pid":44052,"tid":44428,"channel":11,"tags":"0x1000000"}}

00000013	Geneva-Tracer-Foo	44052	44428	4	0	02\05\2026-13:25:30:652	{"duration":18800,"env_dt_spanId":"b87630b5986e364f","env_dt_traceId":"8507dcdc651af34fb8f21152a98e2977","env_name":"Span","env_time":"2026-02-05T21:25:30.652654800Z","kind":1,"name":"Span-Bar","startTime":"2026-02-05T21:25:30.652636000Z","statusCode":0,"statusMessage":"","success":"True","meta":{"provider":"Geneva-Tracer-Foo","event":"Span","time":"2026-02-05T13:25:30.652","cpu":4,"pid":44052,"tid":44428,"channel":11,"tags":"0x1000000"}}

[lalitb]

@lukeina2z - In ETW exporter the trace-id is bound to the tracer instance. So you need to create separate tracer instance for each trace operation.