Improvement: githubAnalyzer in-memory cache grows unbounded (memory leak)

[ChitkulLakshya]

Improvement: githubAnalyzer cache grows unbounded (memory leak on 512MB plan)

File: server/utils/githubAnalyzer.js:36

Problem

The in-memory cache githubCache is a Map that grows without bound:

const githubCache = new Map();

Entries are only evicted when accessed and found expired (lazy eviction in getCached). If many unique usernames are analyzed and never re-accessed, the cache grows indefinitely.

Each cached entry stores up to 30 simplified repo objects (~2-5KB per username). After 1000 unique usernames: ~5MB. After 10,000: ~50MB.

Impact on 512MB Render plan

With the lazy-load optimization from Phase 6 (server starts at ~113MB), a 50MB cache leak would bring total to ~163MB — still within limits, but concerning for long-running instances.

Fix

1. Simple: Add a max size check in setCached:

function setCached(key, data) {
  if (githubCache.size > 500) {
    // Evict oldest entries
    const firstKey = githubCache.keys().next().value;
    githubCache.delete(firstKey);
  }
  githubCache.set(key, { data, timestamp: Date.now() });
}

2. Better: Use an LRU cache library like lru-cache with a size limit and TTL.

3. Best: Move cache to Redis (if available) or MongoDB for persistence across restarts.

Severity

Low-Medium — Slow leak. Won't cause immediate issues but could accumulate over weeks of uptime.

Phase

Introduced in Phase 3 (PR #28, merged).