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.
Redis Pub/Sub Subscriber Not Receiving Messages: A Debugging Guide
A practical guide to debugging Redis Pub/Sub when subscribers miss messages. Covers channel mismatches, client disconnections, and message ordering issues.
Redis Cluster Slot Migration Error: Diagnosis and Fix
A practical guide to diagnosing and resolving slot migration errors in Redis Cluster, covering common causes, verification steps, and real-world fixes.
Prisma Migration Drift: Schema Mismatch Between Generated Client and Database
When Prisma's generated client doesn't match the actual database schema, migrations fail or produce inconsistent results. This guide covers detection, root causes, and fixes for schema drift.
How to Find and Fix Prisma N+1 Queries with include and select
A practical guide to debugging N+1 query problems in Prisma when using include and select, with real commands and specific fixes.
TypeORM Relation Eager vs Lazy Loading Errors: Debugging Unexpected Query Behavior
When TypeORM relations load too many or too few rows, the culprit is often a mix of eager and lazy loading settings. This guide covers debugging unexpected query patterns and fixing silent performance issues.
Debugging GraphQL N+1 Queries with DataLoader Batching
When DataLoader batching fails, GraphQL resolvers generate cascading database queries that kill performance. This guide shows you how to find, fix, and verify the N+1 pattern with concrete tools.
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.