What caused the sudden spike in error rates for Doc.com's PDF conversion tool yesterday afternoon?

Introduction

The sudden spike in error rates for Doc.com's PDF conversion tool yesterday afternoon 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 the product.

Our analysis will follow a structured framework, beginning with clarifying questions to gather essential context, followed by a methodical examination of potential causes, data analysis, and hypothesis formation. We'll then move on to root cause analysis, validation steps, and finally, a comprehensive resolution plan.

Step 1

Clarifying Questions (3 minutes)

• I'm noticing the issue is localized to yesterday afternoon. Would you say this is an isolated incident or part of a trend?

Why it matters: Helps determine if this is a one-off issue or a systemic problem. Expected answer: Isolated incident. Impact on approach: If isolated, we focus on recent changes; if trend, we look at longer-term factors.

• Given the specificity of the PDF conversion tool, I'm wondering about the scale. Approximately how many users were affected by this spike?

Why it matters: Helps gauge the severity and prioritize our response. Expected answer: A significant portion of active users. Impact on approach: Higher user impact would necessitate more urgent action.

• Considering the nature of PDF conversion, I'm curious about the types of errors encountered. Were they primarily conversion failures or quality issues?

Why it matters: Different error types point to different potential causes. Expected answer: Mix of conversion failures and quality issues. Impact on approach: Guides our technical investigation and hypothesis formation.

• Looking at the timing, I'm thinking about recent deployments. Were any updates pushed to the conversion tool or related systems in the past 48 hours?

Why it matters: Recent changes are often culprits in sudden performance shifts. Expected answer: Yes, a minor update was deployed. Impact on approach: If yes, we'd prioritize investigating that update.

• Given the sudden nature of the spike, I'm considering infrastructure changes. Has there been any modification to our cloud resources or CDN configuration recently?

Why it matters: Infrastructure changes can cause unexpected performance issues. Expected answer: No recent infrastructure changes. Impact on approach: If no, we'd focus more on application-level issues.