Crate tracing_durations_export

source ·
Expand description

Record and visualize which spans are active in parallel.

§Usage

use std::fs::File;
use std::io::BufWriter;
use tracing_durations_export::{DurationsLayer, DurationsLayerBuilder, DurationsLayerDropGuard};
use tracing_subscriber::layer::SubscriberExt;
use tracing_subscriber::{registry::Registry, fmt};

fn setup_global_subscriber() -> DurationsLayerDropGuard {
    let fmt_layer = fmt::Layer::default();
    let (duration_layer, guard) = DurationsLayerBuilder::default()
        .durations_file("traces.ndjson")
        // Available with the `plot` feature
        // .plot_file("traces.svg")
        .build()
        .unwrap();
    let subscriber = Registry::default()
        .with(fmt_layer)
        .with(duration_layer);
     
    tracing::subscriber::set_global_default(subscriber).unwrap();

    guard
}

// your code here ...

The output file will look something like below, where each section where a span is active is one line.

[...]
{"id":6,"name":"read_cache","start":{"secs":0,"nanos":122457871},"end":{"secs":0,"nanos":122463135},"parents":[5],"fields":{"id":"2"}}
{"id":5,"name":"cached_network_request","start":{"secs":0,"nanos":122433854},"end":{"secs":0,"nanos":122499689},"parents":[],"fields":{"id":"2","api":"https://example.net/cached"}}
{"id":9007474132647937,"name":"parse_cache","start":{"secs":0,"nanos":122625724},"end":{"secs":0,"nanos":125791908},"parents":[],"fields":{}}
{"id":5,"name":"cached_network_request","start":{"secs":0,"nanos":125973025},"end":{"secs":0,"nanos":126007737},"parents":[],"fields":{"id":"2","api":"https://example.net/cached"}}
{"id":5,"name":"cached_network_request","start":{"secs":0,"nanos":126061739},"end":{"secs":0,"nanos":126066912},"parents":[],"fields":{"id":"2","api":"https://example.net/cached"}}
{"id":2251799813685254,"name":"read_cache","start":{"secs":0,"nanos":126157156},"end":{"secs":0,"nanos":126193547},"parents":[2251799813685253],"fields":{"id":"3"}}
{"id":2251799813685253,"name":"cached_network_request","start":{"secs":0,"nanos":126144140},"end":{"secs":0,"nanos":126213181},"parents":[],"fields":{"api":"https://example.net/cached","id":"3"}}
{"id":27021597764222977,"name":"make_network_request","start":{"secs":0,"nanos":128343009},"end":{"secs":0,"nanos":128383121},"parents":[13510798882111491],"fields":{"api":"https://example.net/cached","id":"0"}}```
[...]

Note that 0 is the time of the first span, not the start of the process.

Modules§

  • plot
    Visualize the spans and save the plot as svg.

Structs§