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.
18 playbooks · 509 guides · 96 articles · 13 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
18 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.
TensorFlow Incompatible Shapes Error: Debugging Shape Mismatch in Production
A practical guide to diagnosing and fixing TensorFlow shape mismatches, from understanding error messages to verifying the fix.
Diagnosing NumPy MemoryError When Allocating Large Arrays
A direct guide to diagnosing and resolving MemoryError when NumPy fails to allocate large arrays, including memory limits, dtype issues, and swap usage.
Jupyter Kernel Keeps Dying: Debugging and Fixes Guide
A practical guide to diagnosing why your Jupyter kernel repeatedly dies and restarts, with specific commands and root causes.
Kafka Consumer Lag Growing: Why Offsets Stall and How to Fix It
A practical guide to diagnosing and resolving Kafka consumer lag growth, covering configuration pitfalls, broker throttling, and rebalance storms.
Kafka Consumer Group Rebalance Storm Debugging
A practical guide to diagnosing and fixing Kafka consumer group rebalance storms—when frequent rebalances cause processing stalls and lag spikes.
RabbitMQ Messages Stuck Unacked: A Production Debugging Guide
A production-proven guide to diagnosing why RabbitMQ messages pile up as unacknowledged, from consumer stalls to prefetch traps.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Mocking External APIs in Tests: Why stubbing HTTP is harder than it looks
Stubbing HTTP calls seems easy until a subtle mismatch between your mock and the real API causes a production incident. Here's what I learned the hard way.
How I Diagnosed a 1-in-1000 Race Condition in Our CI Pipeline
A race condition that only appeared once every thousand CI runs took weeks to track down. Here's how we finally caught it, what tools helped, and what we changed to prevent similar bugs.
How Database Indexes Work: A Debugging Story
A practical guide to understanding database indexes through the lens of debugging a real production outage caused by a missing covering index.
Reading PostgreSQL EXPLAIN ANALYZE Output: A Practical Guide with Real Query Examples
EXPLAIN ANALYZE is the single most important tool for diagnosing slow queries. Here's how to read the output, spot common pitfalls, and fix them with real-world examples.
When caches lie: debugging stale data in distributed systems
Cache invalidation is often cited as one of the two hard problems in CS, but the daily reality is subtler: partial staleness, clock drift, and silent evictions. This post walks through real debugging techniques for stale data in Redis, Memcached, and CDN layers.
Debugging Cache Invalidation Failures: A Case Study with Redis and PostgreSQL
Cache invalidation sounds simple — write-through, TTLs, done. But in practice, silent failures hide in race conditions, connection pools, and stale read replicas. Here's a real debugging story with Redis and PostgreSQL that taught me how to find them.