Fastrace example itself works, but when I try the same code in my program I get different layout

[wlinna]

I am trying to follow this example:
https://github.com/fast/logforth/blob/main/examples/src/fastrace.rs

When I run this example by cloning the repo and then running cargo run --example fastrace, I get logs like this:

SpanRecord {
    trace_id: TraceId(
        307375313405270878976516274156094018992,
    ),
    span_id: SpanId(
        12897649922165178369,
    ),
    parent_id: SpanId(
        0,
    ),
    begin_time_unix_ns: 1771903899257295166,
    duration_ns: 1277973,
    name: "root",
    properties: [],
    events: [
        EventRecord {
            name: "Hello syslog error!",
            timestamp_unix_ns: 1771903899258547992,
            properties: [
                (
                    "level",
                    "ERROR",
                ),
                (
                    "timestamp",
                    "2026-02-24T10:31:39.257326083+07:00[Asia/Jakarta]",
                ),
            ],
        },

The logs become events etc.

But when I try similar code in my codebase

    logforth::starter_log::builder()
        .dispatch(|d| d.filter(LevelFilter::All)
            .append(append::FastraceEvent::default()))
        .dispatch(|d| d.filter(make_log_filter())
            .diagnostic(diagnostic::FastraceDiagnostic::default())
            .append(logforth::append::Stdout::default()))
        .apply();

    fastrace::set_reporter(ConsoleReporter, Config::default());

    let trace_id = opt.trace_id.as_ref()
        .and_then(|trace_id| TraceId::from_str(&trace_id)
            .inspect_err(|err| eprintln!("{err}")).ok());

    let span_context = if let Some(trace_id) = trace_id {
        SpanContext::new(trace_id, SpanId(0))
    } else {
        SpanContext::random()
    };

    let root = Span::root("root", span_context);
    let _g = root.set_local_parent();

    log::info!("Starting program");

...

   fastrace::flush();

The logs look like this:

1771904626808472393   INFO XYZ: main.rs:110 Starting program trace_id=73dccc69892b0af829573db4e48afa24 span_id=fd048adf00000001 sampled=true

And here's another difference: in the example I can remove the following code and still get structured logs:

        .dispatch(|d| {
            d.diagnostic(diagnostic::FastraceDiagnostic::default())
                .append(logforth::append::Stderr::default())
        })

But in my program, removing that code leads me to not getting any logs at all.

Do I need to configure environment variables or something else to get similar results as in the example?

This is how I have added fastrace, logforth and log to my binary:

fastrace = { version = "0.7.16", features = ["enable"] }
logforth = { version = "0.29.1", features = ["append-fastrace", "diagnostic-fastrace", "starter-log"] }
log = "0.4.29"

[wlinna]

Okay, I think I got it. root and/or _g had not gone out of scope before fastrace::flush().