In Rust I use tracing wirte log to file. the file is created,but it is empty

Question

In Rust I use tracing wirte log to file.While the app sleep, log file be created.the app finish ,the log file is empty.

Code:

pub fn tracing_init() {
    let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
    // 输出到控制台中
    let formatting_layer = fmt::layer().pretty().with_writer(std::io::stderr);
    let log_file_name = Local::now().format("%Y-%m-%d").to_string() + ".log";
    // 输出到文件中
    let file_appender = rolling::daily("logs", log_file_name);
    let (non_blocking_appender, _guard) = non_blocking(file_appender);
    let file_layer = fmt::layer()
        .with_ansi(false)
        .with_writer(non_blocking_appender);

    // 注册
    Registry::default()
        .with(env_filter)
        // ErrorLayer 可以让 color-eyre 获取到 span 的信息
        .with(ErrorLayer::default())
        .with(formatting_layer)
        .with(file_layer)
        .init();

    // 安裝 color-eyre 的 panic 处理句柄
    color_eyre::install().expect("color_eyre install fail");

}

in main function:

fn main() {
    tracing_init();
    event!(Level::DEBUG, "aaa:{}", "myu");
    info!("info");
    debug!("debug");
    error!("error");
    warn!("warn");
    tracing::info!("this is tracing info");
    thread::sleep(time::Duration::from_secs(10));
    event!(Level::INFO, "aaa:{}", "myu1");
    info!("info1");
    debug!("debug1");
    error!("error1");
    warn!("warn1");
    tracing::info!("this is tracing info1");
}

the file is created,bug it is empty.

Cargo.toml file is here:

[dependencies]
tracing = "0.1.37"
tracing-subscriber = { version = "0.3.16", features = ["env-filter", "std"] }
tracing-appender="0.2.2"
tracing-error="0.2.0"
color-eyre="0.6.2"

chrono = "0.4"

Is it empty even after the app stops, or only while it's running? — Chayim Friedman, Apr 03 '23 at 16:39
While the app sleep, log file be created.the app finish ,the log file is empty. — yan shen, Apr 04 '23 at 01:41

score 0 · Answer 1 · answered Aug 31 '23 at 12:40

need return the guard.

Check detail: tracing-with-multi-layer

pub fn tracing_init() -> tracing_appender::non_blocking::WorkerGuard {
   // ...
   let (non_blocking_appender, guard) = non_blocking(file_appender);
   // ...
   guard
}

let _guard = tracing_init()
tracing::info!("info");

In Rust I use tracing wirte log to file. the file is created,but it is empty

1 Answers1