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typescript.unbounded_cache

Stability High

Detects caches without size limits or eviction policies.

Why It Matters

Unbounded caches:

Memory exhaustion — Cache grows until OOM
No eviction — Stale data never removed
Unpredictable behavior — Sudden crashes under load

Example

// ❌ Before (unbounded Map cache)
const cache = new Map<string, Data>();

function getOrFetch(key: string): Data {
  if (cache.has(key)) {
    return cache.get(key)!;
  }
  const data = fetchData(key);
  cache.set(key, data); // Grows forever!
  return data;
}

// ✅ After (bounded LRU cache)
import LRU from 'lru-cache';

const cache = new LRU<string, Data>({
  max: 500,
  ttl: 1000 * 60 * 5, // 5 minutes
});

function getOrFetch(key: string): Data {
  const cached = cache.get(key);
  if (cached) return cached;

  const data = fetchData(key);
  cache.set(key, data);
  return data;
}

What Unfault Detects

Map/Object used as cache without size limits
Missing LRU/TTL eviction
Caches without capacity configuration

Auto-Fix

Unfault can suggest replacing with bounded LRU cache.