mirror of
https://github.com/CarGDev/debug-dojo.git
synced 2025-09-18 09:58:37 +00:00
Compare commits
2 Commits
6d259ecebd
...
44928348ae
Author | SHA1 | Date | |
---|---|---|---|
![]() |
44928348ae | ||
![]() |
78d290b18e |
149
DEBUGGING_CASES.md
Normal file
149
DEBUGGING_CASES.md
Normal file
@@ -0,0 +1,149 @@
|
||||
# Real-World Debugging Cases: Lessons from the Frontlines
|
||||
|
||||
This document explores three critical debugging scenarios that demonstrate how systematic debugging approaches saved companies millions and transformed development practices. These cases show that debugging isn't just about fixing bugs—it's about understanding systems, measuring impact, and building better processes.
|
||||
|
||||
## Case 1: Slack – "Death by a Thousand Redux Calls"
|
||||
|
||||
### What Happened
|
||||
As Slack's desktop app grew (React + Redux on Electron), even idling caused Redux subscriber loops to take ≥ 25ms, sometimes > 200ms at p99. Every message, channel update, reaction, or presence calculation triggered global Redux events for thousands of components—resulting in massive re-renders from stale props.
|
||||
|
||||
### Root Cause Analysis
|
||||
- **Too many dispatches and subscriptions**—each relayed to all connected components
|
||||
- **Shallow-equality checks broke** because props were calculated via `.map()` or inline objects, leading to unnecessary re-renders per loop
|
||||
- **The channel sidebar alone** (rendering all channels) triggered ~40 connected props per item, sometimes hundreds of items
|
||||
- **Silence in Slack turned into browser jank** due to constant background processing
|
||||
|
||||
### How They Diagnosed It
|
||||
Slack's engineering team implemented a systematic debugging approach:
|
||||
|
||||
1. **Performance logging** (not production logging) to count subscriber calls and per-component paints
|
||||
2. **Profiling and flame graphs** to isolate "list items & selectors" as the worst offenders
|
||||
3. **Classic "instrument → isolate → fix"** methodology
|
||||
|
||||
### The Fix That Unlocked Everything
|
||||
- **Grouping updates into batched dispatches** inside `requestAnimationFrame`
|
||||
- **Codemods + new lint rules** to catch unstable (new-object) props and enforce memoization
|
||||
- **Specialized components & cleaner data selections** so selectors returned stable, memoizable values—dropping the number of connected props per loop
|
||||
|
||||
### Cost/ROI
|
||||
- **Sidebar rendering improved by ≈ 30%**
|
||||
- **Overall Redux-loop latency dropped by > 10%**
|
||||
- **Smoother typing, faster animations, and fewer dropped frames**
|
||||
- **Critical wins for user experience** across tens of millions of users without rewriting the app
|
||||
|
||||
### Role of Debugging
|
||||
It wasn't guesswork. They paused development, profiled behavior, picked one anchor point (the sidebar), debugged it, measured improvements, then rolled out code-wide. **It's debugging that scales.**
|
||||
|
||||
**Further Reading:**
|
||||
|
||||
- [Slack Engineering Blog: break stuff on purpose](https://slack.engineering/break-stuff-on-purpose/)
|
||||
|
||||
---
|
||||
|
||||
## Case 2: Datadog Outage – When a Monitoring Platform Breaks Production
|
||||
|
||||
### What Happened
|
||||
On March 8, 2023, Datadog's internal systems suffered a cascading failure that rendered their global SaaS entirely unusable for 24 hours.
|
||||
|
||||
### Immediate Impact
|
||||
- **$5 million in lost revenue**—the entire day's worth, collected or not
|
||||
- **Customers were blind to metrics**, triggering huge service desk tickets across big enterprises
|
||||
- **Complete loss of monitoring capabilities** for thousands of companies worldwide
|
||||
|
||||
### How They Debugged It
|
||||
Engineering triaged using a systematic approach:
|
||||
|
||||
1. **Internal logs analysis** to identify a backlog of failed throttle requests
|
||||
2. **Bottleneck identification** in their ingestion pipeline
|
||||
3. **Log-tracing across services** to understand the failure propagation
|
||||
4. **Fixed the propagation of malformed error signals** in a single critical queue
|
||||
5. **Rolled back a failing version** that had broken upstream routing
|
||||
|
||||
### Why Debugging Was the Fix
|
||||
- **Stabilized error handling paths** preserving queue integrity
|
||||
- **Reintroduced circuit breakers and back-pressure avoidance** in the pipeline
|
||||
- **Without live-traffic tracing and replay of user sessions**, they couldn't restore system behavior linearly
|
||||
- **Debugging surface dependencies under real load** saved the day
|
||||
|
||||
### Cost and Lessons
|
||||
That day-long outage served as a harsh lesson on SLO tension—missing a UI state led to total unusability. It's an extreme cost in both trust and dollars, but debugging allowed a controlled rollback before wider chaos.
|
||||
|
||||
**Further Reading:**
|
||||
|
||||
- [Datadog Incident Report](https://www.datadoghq.com/blog/2023-03-08-multiregion-infrastructure-connectivity-issue/)
|
||||
|
||||
---
|
||||
|
||||
## Case 3: Google – Making Debugging Smarter with AI (BRT Automation)
|
||||
|
||||
### What Happened
|
||||
At Google, researchers built an experimental system to generate bug reproduction tests (BRTs) and integrate them into an Automated Program Repair (APR) workflow at scale.
|
||||
|
||||
### Why They Did It
|
||||
Engineers often spend hours reconstructing bug contexts—what input triggers what failure—before they can fix it. The BRT system aimed to automate that first step.
|
||||
|
||||
### The Outcome
|
||||
- **Agent-generated BRTs were plausible for ~28% of real bugs**
|
||||
- **When plugged into the APR, they increased auto-fix rates by 30%** compared to standard workflows
|
||||
- **Significant reduction in manual debugging time** for common bug patterns
|
||||
|
||||
### Role of Debugging
|
||||
By automating reproducibility testing and fix suggestions—even if imperfect—Google engineers scaled their debug bandwidth. It's about building debug pipelines that generate hypotheses and tests, not just relying on chance.
|
||||
|
||||
### Technical Implementation
|
||||
The system used:
|
||||
- **Machine learning models** to predict likely bug reproduction steps
|
||||
- **Automated test generation** based on error patterns
|
||||
- **Integration with existing debugging tools** to streamline the workflow
|
||||
|
||||
**Further Reading:**
|
||||
- [arXiv: Bug Reproduction Test Generation](https://arxiv.org/abs/2502.01821)
|
||||
|
||||
---
|
||||
|
||||
## Key Lessons for Frontend Developers
|
||||
|
||||
### 1. Measure Before You Fix
|
||||
All three cases started with measurement and instrumentation. You can't optimize what you can't measure.
|
||||
|
||||
### 2. Debugging Scales
|
||||
Slack's approach shows that systematic debugging can be applied across entire codebases, not just individual bugs.
|
||||
|
||||
### 3. Automation is the Future
|
||||
Google's BRT system demonstrates how AI and automation can augment human debugging capabilities.
|
||||
|
||||
### 4. Cost of Not Debugging
|
||||
Datadog's $5 million loss illustrates the real cost of inadequate debugging processes in production systems.
|
||||
|
||||
### 5. Systematic Approaches Win
|
||||
Random debugging rarely works. All successful cases used structured approaches: instrument → isolate → fix → measure.
|
||||
|
||||
## Debugging Best Practices Derived from These Cases
|
||||
|
||||
### For Performance Issues (Like Slack)
|
||||
- **Profile first, optimize second**
|
||||
- **Measure at scale** with real user data
|
||||
- **Use flame graphs and performance tools**
|
||||
- **Implement systematic monitoring**
|
||||
|
||||
### For Production Outages (Like Datadog)
|
||||
- **Have comprehensive logging** before incidents happen
|
||||
- **Practice incident response** regularly
|
||||
- **Build rollback capabilities** into your deployment process
|
||||
- **Monitor system health** at multiple levels
|
||||
|
||||
### For Automation (Like Google)
|
||||
- **Start with the most common problems**
|
||||
- **Build tools that augment human capabilities**
|
||||
- **Measure the effectiveness** of automated solutions
|
||||
- **Iterate and improve** based on real usage
|
||||
|
||||
## Conclusion
|
||||
|
||||
These cases demonstrate that debugging is not just a technical skill—it's a strategic capability that can save companies millions and transform development practices. The key is approaching debugging systematically, measuring everything, and building tools and processes that scale.
|
||||
|
||||
Whether you're dealing with performance issues, production outages, or building the next generation of debugging tools, these lessons provide a framework for effective problem-solving at scale.
|
||||
|
||||
---
|
||||
|
||||
*This document is part of the Pokémon Explorer debugging project. Use these real-world cases to inform your debugging approach and develop the systematic thinking needed for effective problem-solving.*
|
@@ -4,6 +4,10 @@ Welcome to the chaos lab where we intentionally break things so you can learn to
|
||||
|
||||
Built with Vite + React + TypeScript, Ant Design, and Atomic Design principles, this app fetches Pokémon data from the PokeAPI. But here's the catch: it's riddled with bugs, both real and intentional, waiting for you to discover and understand.
|
||||
|
||||

|
||||
|
||||
*The app in action: Search for Pokémon, discover bugs, learn debugging.*
|
||||
|
||||
## Bugs (Challenges)
|
||||
|
||||
Your mission: identify them, understand their root causes, and document your findings. There may be one bug we didn't list. If you find it, we owe you bragging rights.
|
||||
@@ -118,6 +122,10 @@ This project is licensed under the MIT License - see the [LICENSE](LICENSE) file
|
||||
|
||||
These articles go deeper into the strategies and mindset that will make you a more effective frontend debugger.
|
||||
|
||||
### **Real-World Debugging Cases: Lessons from the Frontlines**
|
||||
Explore three critical debugging scenarios that demonstrate how systematic debugging approaches saved companies millions and transformed development practices. Learn from Slack's Redux performance crisis, Datadog's $5M outage, and Google's AI-powered debugging automation.
|
||||
[Read the full analysis here](DEBUGGING_CASES.md)
|
||||
|
||||
### **How to Debug CSS**
|
||||
*by S. Mustaf*
|
||||
Covers CSS debugging techniques, common styling issues, and how to use browser DevTools to troubleshoot layout and styling problems effectively.
|
||||
|
BIN
assets/APP_VIEW.png
Normal file
BIN
assets/APP_VIEW.png
Normal file
Binary file not shown.
After Width: | Height: | Size: 123 KiB |
Reference in New Issue
Block a user