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rust.io_in_hot_path

Performance High

Detects I/O operations in performance-critical code paths that block execution.

Why It Matters

I/O in hot paths:

Blocks threads — Sync I/O stalls execution
Increases latency — Disk/network ops are slow
Reduces throughput — Can’t process other requests

Example

// ❌ Before (file I/O in hot path)
fn process_items(items: &[Item]) -> Vec<Result> {
    items.iter().map(|item| {
        let config = std::fs::read_to_string("config.json")?; // I/O per item!
        process_with_config(item, &config)
    }).collect()
}

// ✅ After (load once, use many)
fn process_items(items: &[Item]) -> Vec<Result> {
    let config = std::fs::read_to_string("config.json")?;
    items.iter().map(|item| {
        process_with_config(item, &config)
    }).collect()
}

What Unfault Detects

File reads inside loops
Network calls in iterators
Database queries per item

Auto-Fix

Unfault can hoist I/O operations outside loops.