Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
17 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
Hunting Down Memory Leaks Caused by Improper WeakMap/WeakSet Usage
A practical guide to diagnosing and fixing memory leaks from WeakMap/WeakSet anti-patterns in production JavaScript applications.
Debugging for-await-of Errors with Async Iterators
A senior engineer's guide to diagnosing and fixing for-await-of errors when consuming async iterators, covering common pitfalls like unhandled rejections, premature termination, and generator misconfiguration.
Debugging Unexpected State Changes from JavaScript Object Mutation
A practical guide to identifying and fixing bugs caused by unintended object mutation in JavaScript, with real-world examples and debugging strategies.
Debugging TypeScript 'satisfies' Operator Errors
A practical guide to diagnosing and resolving type errors when using the TypeScript satisfies operator, including narrowing, excess property checks, and type inference pitfalls.
Debugging TypeScript Readonly Property Violations
How to diagnose and fix readonly property violations in TypeScript, including mutation via methods, aliasing, and array/object nesting.
Debugging JavaScript Proxy Reflect Traps: When Your Proxy Silently Fails
Guide to debugging silent failures in JavaScript Proxy traps when using the Reflect API. Covers missing return values, revoked proxies, and infinite recursion.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Tracking Down a 200 MB Leak with Python Memory Profilers
A production API was silently leaking 200 MB of RAM every hour. Here's how memory profilers found the culprit—a forgotten NumPy array reference—and how you can apply the same techniques.
Reading CPU Flame Graphs: What the Hot Colors Actually Tell You
Flame graphs are everywhere, but most engineers read them wrong. Here's how to identify real bottlenecks, avoid common misinterpretations, and turn profile data into actionable fixes.
When Logs Lie: The Gaps Between What You Log and What Actually Happened
Logs are the first thing we reach for during an incident. But they can be misleading, incomplete, or outright wrong. Here's when to trust them and when not to.
Adding Observability to a 500K-Line Monolith Without a Rewrite
Adding structured logging, distributed tracing, and metrics to a legacy monolith without a full rewrite. Real code examples and a war story from a 500K-line codebase.
Distributed Tracing: Following a Single Request Across Microservices
Distributed tracing lets you follow a request as it hops across services. I'll show you how trace context propagates, why sampling matters, and how tracing helped us debug a 5-second latency spike in production.
Structured Logging in JSON: Fields, Schemas, and Pitfalls from Production
A practical guide to designing JSON log schemas that are queryable, consistent, and actually useful in production — with field recommendations and a war story.