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.
WebSocket Reconnect Storm & Thundering Herd Debugging
Diagnose and fix cascading WebSocket reconnection storms triggered by thundering herd patterns in distributed systems.
DNS Caching Stale Records: Why TTL Is Ignored and How to Fix It
A practical guide to debugging cases where DNS resolvers serve stale records past their TTL, covering common causes like resolver caches, stub resolvers, and low TTLs.
Debugging HTTP Keep-Alive Connection Reset by Peer
A practical guide to diagnosing and fixing 'connection reset by peer' errors on HTTP keep-alive connections, covering server, proxy, and network causes.
PostgreSQL Logical Replication Slot Lag: How to Diagnose and Fix WAL Buildup
A concise guide to diagnosing and resolving PostgreSQL logical replication slot lag, including WAL accumulation, consumer failures, and monitoring commands.
PostgreSQL TOAST Table Bloat: Diagnosis and Recovery
A practical guide to identifying, diagnosing, and fixing TOAST table bloat in PostgreSQL, including real commands and war stories.
MongoDB WriteConflict Transaction Retry: A Practical Debugging Guide
Step-by-step debugging guide for MongoDB WriteConflict errors in transactions, covering causes, diagnostics, and fixes.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Why Your P99 Latency Is Lying to You (and What to Use Instead)
The 99th percentile is the go-to metric for tail latency, but it's easy to fool. Here's a real outage caused by trusting P99, and how to build a more honest monitoring stack.
The Real Cost of N+1 Queries: More Than Just Slow Pages
N+1 queries are often dismissed as a minor performance issue, but their real cost goes far beyond slow page loads—think cascading timeouts, database meltdowns, and cloud bills that balloon overnight. Here's what you're actually paying for.
Reading Flame Graphs: The Non-Obvious Patterns That Reveal Real Bottlenecks
Flame graphs are everywhere in performance profiling, but most engineers only scratch the surface. Here are the patterns that actually tell you where your code is slow.
Print Debugging vs Debugger: When printf Wins and When It Fails
Printf debugging is dismissed as primitive, but in many real-world scenarios it's faster and more reliable than a full debugger. Here's the tradeoff with concrete examples from distributed systems and production incidents.
Writing Postmortems That Actually Improve Reliability
A postmortem that blames someone gets filed and forgotten. A postmortem that traces cause without blame becomes a reliability upgrade. Here's how to write the second kind, with a real example from an 18-hour DNS outage.
Feature Flag Debt: When Your 500 Conditional Branches Become the Incident
Feature flags are great until they're not. Here's how to audit, remove, and automate cleanup before your 500th conditional branch becomes the root cause of a production incident.