Crate tokio_blocked 

This crate provides TokioBlockedLayer, a tracing-rs layer that tracks when tokio tasks are blocked by synchronous code.

See TokioBlockedLayer for more details.

Usage

Add this to your Cargo.toml:

[dependencies]
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["fmt", "env-filter"] }
tokio = { version = "1.47", features = ["rt-multi-thread", "tracing", "macros", "time"] }

tokio-blocked = "*"

Then, in your application code:

use std::time::Duration;
use tokio_blocked::TokioBlockedLayer;
use tracing_subscriber::{
    EnvFilter, Layer as _, layer::SubscriberExt as _, util::SubscriberInitExt as _,
};

#[tokio::main]
async fn main() {
    // Prepare the tracing-subscriber logger with both a regular format logger
    // and the TokioBlockedLayer.

    {
        let fmt = tracing_subscriber::fmt::layer().with_filter(EnvFilter::from_default_env());

        let blocked = TokioBlockedLayer::new()
            .with_warn_busy_single_poll(Some(Duration::from_micros(150)));

        tracing_subscriber::registry()
            .with(fmt)
            .with(blocked)
            .init();
    }

    tokio::task::spawn(async {
        // BAD!
        // This produces a warning log message.
        std::thread::sleep(Duration::from_secs(2));
    })
    .await
    .unwrap();
}

Structs

TokioBlockedLayer

A standalone layer that measures “busy” time per callsite (span metadata), and records each measured duration as a tracing event.