Node.js & Elysia Code Audit

Event Loop Blockers, Memory Leaks, and Silent Failures

Event loop blocking is the most common issue. One synchronous file read, one CPU-intensive JSON parse, or one exponentially backtracking regex stalls every concurrent request. Elysia’s Bun runtime is faster than V8, but it doesn’t save you from blocking the main thread. We find these blockers in nearly every Node.js audit.

Memory leaks are insidious. They don’t crash immediately - response times slowly increase over hours as GC pauses grow. Common sources: event listeners that accumulate without cleanup, closures capturing large objects, caches without eviction, and sockets that aren’t destroyed on disconnect. By the time the OOM killer fires, the leak has been degrading performance for days.

Error handling is often incomplete. Try-catch around the happy path, nothing around edge cases. Promise chains without .catch handlers. In Elysia, onError hooks that catch some errors but miss others. Users see “Internal Server Error” and your logs show nothing. Middleware execution order creates subtle bugs too - authentication running after transformation, validation before parsing. One misplaced hook and your security model has a gap. Dependency management is a chronic issue: hundreds of transitive dependencies, some with known CVEs, some abandoned.

Profiling Under Load and Testing Every Error Path

We profile the event loop under realistic load. Using clinic.js and Bun’s profiling tools, we measure event loop delay, async operation timing, and CPU time per request. We simulate sustained traffic to surface issues that only appear under prolonged load.

Memory analysis uses heap snapshots taken at intervals. We compare snapshots to identify objects that grow but never get collected. We trace retained references back to the code that creates them. V8’s snapshot tooling shows exactly which object retains which, and why the GC can’t free it.

Every request path gets tested for error handling coverage. We trigger failures intentionally - database timeouts, malformed payloads, auth failures - and verify each produces a meaningful error response and a useful log entry. We audit Elysia’s lifecycle hooks for correct order: authentication before authorization, validation after parsing, error handling covering every stage.

Stable Heap, Consistent Latency, Clean Dependencies

Event loop delays drop from hundreds of milliseconds to single digits. Response time percentiles tighten - p99 moves closer to p50 because random spikes from blocking operations are gone. Users experience consistent performance regardless of concurrent load.

Memory becomes predictable. Instead of a sawtooth climbing toward the limit, heap usage stabilizes. GC pauses shorten. Uptime extends from hours to weeks. Your monitoring alerts become boring, which is exactly what you want.

Error handling becomes comprehensive. Every failure produces a structured response with the right status code and enough log context to diagnose the issue. Your dependency tree shrinks - unused packages removed, outdated ones updated, vulnerabilities patched, npm audit clean.

Detecting Blocking Calls, ReDoS, and Unbounded Caches

Our AI analysis scans for event loop risks invisible in code review. We detect synchronous APIs disguised by async wrappers, regex patterns vulnerable to ReDoS attacks, and JSON operations on payloads exceeding safe thresholds. Each finding includes the non-blocking alternative.

We generate error handling improvements for every unprotected path. Missing try-catch blocks get wrapped. Promise chains get .catch handlers. Elysia lifecycle gaps get onError coverage. The generated code preserves your existing patterns - we’re completing the error handling you started, not replacing it.

Memory leak detection uses static analysis to find common patterns: event listeners without cleanup, closures capturing objects beyond request lifecycle, module-level caches without bounds. Dependency analysis identifies packages duplicating native APIs, libraries imported for a single function, and transitive dependencies pulling more than they’re worth. Each finding comes with the fix and the estimated impact.