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.
PostgreSQL UUID Primary Key Performance: Debugging Index Bloat and Insert Slowdowns
A direct guide to diagnosing and fixing UUID primary key performance problems in PostgreSQL—index bloat, random writes, and cache thrashing.
Postgres Advisory Lock Not Releasing: A Debugging Guide
Practical debugging guide for PostgreSQL advisory locks that won't release. Covers session management, connection pooling, transaction scoping, and stuck backends.
Debugging MySQL Replication Lag: From Seconds to Hours
A practical guide to diagnosing and fixing MySQL replication lag that spikes from seconds to hours, covering both obvious and subtle causes.
MySQL Index Merge Causing Slow Queries: How to Detect and Fix
Diagnose and fix slow queries caused by MySQL index merge. Learn to identify when index_merge is harmful and how to force single-index scans.
MySQL utf8mb4 Encoding Error When Storing Emoji
A step-by-step guide to diagnosing and fixing MySQL utf8mb4 encoding errors that prevent storing emoji characters in your database.
MySQL Lock Wait Timeout Exceeded: A Practical Debugging Guide
A hands-on guide to diagnosing and fixing MySQL 'Lock wait timeout exceeded' errors, covering real-world cases, transaction isolation traps, and deadlock prevention.
Long-form thinking on debugging habits, observability, and the systems around the bug.
How to Reproduce a Flaky Test: From CI Logs to Reliable Failure
A practical guide to turning intermittent test failures into reliably reproducible bugs, with techniques ranging from loop testing to thread sanitizers.
Property-Based Testing: Finding the Off-by-One That Lived in Production for 18 Months
A concrete story of how switching from example-based tests to property-based tests caught a timing bug that had survived code review, QA, and 18 months of production traffic.
How We Reduced End-to-End Test Flakiness by 80% with Deterministic Seeding
After months of chasing intermittent failures in our CI pipeline, we implemented a three-part strategy — deterministic seeding, isolated state per test, and a structured retry budget — that cut flaky end-to-end test failures by 80%.
Snapshot Testing: The 5 Hidden Failure Modes That Will Break Your CI
Snapshot tests seem like a safety net, but they often hide real bugs, bloat diffs, and silently break your CI. Here are the five failure modes I've seen in production and how to fix them.
Testing Async Code: Avoiding Flakiness and False Positives in JavaScript
Async testing is full of traps: unhandled rejections, race conditions, and tests that pass when they shouldn't. Here's how to write reliable async tests in JavaScript.
Testing Error Handling Code Paths: A Practical Approach
Error handling code is often the least tested and most brittle. Here's how to cover those paths with fault injection, mocks, and chaos engineering.