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.
Python Decorator Losing Function Metadata: __name__, __doc__, and __wrapped__
A practical debugging guide for when Python decorators strip function metadata like __name__, __doc__, and __module__, and how using functools.wraps or manual reassignment fixes it.
Python Context Manager Not Releasing Resource: Debugging Guide
A debugging guide for context managers in Python that fail to release resources, covering common causes like exceptions, reference cycles, and generator cleanup issues.
Debugging Mutable Default Arguments in Python Dataclasses
A practical guide to identifying and fixing the mutable default argument bug in Python dataclasses, with real-world debugging steps and a production war story.
Python logging not showing output: Why your log messages vanish
A practical guide to diagnosing silent loggers in Python, covering root logger, handler levels, propagation, and common misconfigurations that cause output to disappear.
Debugging Pytest Fixture Scope Mismatches
A practical guide to diagnosing and fixing fixture scope conflicts in pytest, covering shared state, teardown order, and concurrency issues.
Python Mock patch() Wrong Target: Why Your Mock Isn't Mocking
A debugging guide for when unittest.mock.patch doesn't work because the target string points to the wrong module path.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Sentry Error Monitoring: A Practical Setup Guide from a Production Outage
A step-by-step setup guide for Sentry error monitoring, covering source maps, release tracking, grouping rules, and alerting — with a real story of a production outage that taught us the hard way.
Reading Prometheus Alert Rules: A Practical Reference for Debugging Firing Alerts
Alert rules look straightforward until you're staring at a firing alert at 3 AM. This post covers the structure, common traps, and how to extract actionable intent from any rule.
Debugging Network Issues with Chrome DevTools: Timing, Waterfalls, and Hidden Columns
A practical guide to diagnosing slow requests, stalled connections, and caching bugs using the Network tab's non-obvious features.
Finding Jank in React Apps with Chrome DevTools Performance Tab
A practical walkthrough of the Performance tab for diagnosing frame drops and long tasks in React apps, with a real debugging story.
Using Breakpoints Effectively: Beyond Step and Continue
Most engineers know F9 to set a breakpoint and F5 to run. But breakpoints have hidden superpowers — conditional, logpoint, hit-count, and data breakpoints — that can cut debugging time in half. Here's how to use them with real examples.
Conditional Breakpoints: When and How to Use Them Beyond the Basics
Conditional breakpoints stop only when a specific condition is true, reducing noise in loops and high-frequency code. Here's how to wield them in Chrome DevTools, VS Code, and IntelliJ, plus a war story about a subtle race condition.