What caused the sudden spike in latency for Together's API endpoints last week?

Introduction

The sudden spike in latency for Together's API endpoints last week 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 might be related to a recent deployment. Has there been any significant code push or infrastructure change in the days leading up to the latency spike?

Why it matters: Recent changes often correlate with performance issues. Expected answer: Yes, there was a major update to our load balancing system. Impact on approach: If confirmed, we'd focus on the load balancer configuration and its interaction with our API servers.

• Considering the nature of API endpoints, I'm curious about the traffic patterns. Have we seen any unusual spikes in API calls or changes in usage patterns from our top clients?

Why it matters: Abnormal traffic could indicate either a client-side issue or a potential DDoS attack. Expected answer: Traffic has been relatively stable, with a slight increase from one major client. Impact on approach: If traffic is stable, we'd shift focus to internal systems rather than client behavior.

• Given that latency is our key metric here, I'm wondering about the specific characteristics of the slowdown. Is the latency increase uniform across all endpoints, or are certain operations more affected than others?

Why it matters: Uneven latency distribution could point to specific problematic services or database queries. Expected answer: The latency spike is more pronounced for endpoints that involve complex data aggregation. Impact on approach: This would lead us to investigate our data processing pipelines and database optimization.

• Thinking about our monitoring systems, I'm curious if we've seen any correlated alerts or anomalies in other metrics like CPU usage, memory consumption, or network throughput?

Why it matters: Correlated metrics can provide valuable clues about the underlying cause. Expected answer: There's been a noticeable increase in CPU usage on our database servers. Impact on approach: This would direct our investigation towards database performance and query optimization.