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rust.regex_compile

Performance High

Detects regex compilation inside loops or hot paths, causing repeated parsing overhead.

Why It Matters

Regex in loops:

Parses repeatedly — Same pattern compiled per iteration
Wastes CPU — 10-100x slower than cached
Hurts latency — Measurable request delays

Example

// ❌ Before (compiling in loop)
for line in lines {
    let re = Regex::new(r"\d+")?; // Compiles every iteration!
    if re.is_match(line) {
        count += 1;
    }
}

// ✅ After (compile once with lazy_static)
use lazy_static::lazy_static;
use regex::Regex;

lazy_static! {
    static ref NUMBER_RE: Regex = Regex::new(r"\d+").unwrap();
}

for line in lines {
    if NUMBER_RE.is_match(line) {
        count += 1;
    }
}

What Unfault Detects

Regex::new inside loops
Regex compilation in request handlers
Missing static regex patterns

Auto-Fix

Unfault can hoist regex to lazy_static or once_cell.