Skip to content

rust.spawn_no_error_handling

Stability Medium

Detects tokio::spawn calls where the JoinHandle is ignored, losing task panics.

Why It Matters

Ignored spawn results:

Silent failures — Task panics are never seen
Lost errors — Return values disappear
Debugging blind spots — No visibility into task health
Resource leaks — Failed tasks may leave resources hanging

Example

// ❌ Before (JoinHandle ignored)
tokio::spawn(async {
    risky_operation().await?;
    Ok(())
});

// ✅ After (error handling)
let handle = tokio::spawn(async {
    risky_operation().await
});

// Check result
match handle.await {
    Ok(result) => result?,
    Err(e) if e.is_panic() => {
        tracing::error!("Task panicked: {:?}", e);
    }
    Err(e) => {
        tracing::error!("Task error: {:?}", e);
    }
}

What Unfault Detects

tokio::spawn() with ignored return value
Fire-and-forget task patterns
Missing .await on JoinHandle

Auto-Fix

Unfault adds proper error handling:

tokio::spawn(async move {
    if let Err(e) = operation().await {
        tracing::error!("Task failed: {:?}", e);
    }
});