What caused the sudden 30% increase in error rates for FullStory's JavaScript SDK implementations yesterday?

Introduction

The sudden 30% increase in error rates for FullStory's JavaScript SDK implementations is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll employ a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our product ecosystem.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent deployment. Has there been any SDK update or server-side change in the last 48 hours?

Why it matters: Recent changes are often the culprit in sudden performance shifts. Expected answer: Yes, there was a minor SDK update yesterday morning. Impact on approach: If confirmed, we'd focus on the changes in that update.

• Considering the scale of the issue, I'm wondering about its distribution. Is this 30% increase uniform across all customers, or are certain segments more affected?

Why it matters: Helps identify if it's a global issue or specific to certain implementations. Expected answer: The increase is more pronounced in high-traffic websites. Impact on approach: We'd prioritize investigating high-traffic implementations and their unique characteristics.

• Given the nature of FullStory's product, I'm curious about data volume changes. Has there been any significant increase in data collection volume that might be straining our systems?

Why it matters: Sudden scale changes can expose hidden system limitations. Expected answer: Data volume has been steadily increasing, but no sudden spikes. Impact on approach: If volume is stable, we'd focus more on code-level issues rather than infrastructure scaling.

• Thinking about external factors, have there been any major browser updates or changes in web standards that might affect our SDK's functionality?

Why it matters: External technological changes can sometimes cause unexpected behavior in SDKs. Expected answer: Chrome released a minor update two days ago. Impact on approach: We'd investigate compatibility issues with the latest browser versions.