Debugging a system issue Background As a beta offering for our product, we are trying out a new third-party recommendation service to help suggest a next action for users. We surface those next actions as part of the user's landing page when they sign in - maybe it's sending an important message, checking off an important todo, etc. You're settling in at your desk after a delicious and energizing team lunch when you receive a performance alert from the monitoring system. Rendering the beta landing page for a user is averaging around 10 seconds, up from the normal average of 800ms. About 10% of the users in the beta are even seeing the dreaded 504 Gateway Timeout error. The beta users represent a small subset of the overall traffic, but this is something that we'd like to understand and fix in the next few days. No changes have been deployed to the frontend that powers the recommendation service in several weeks. Architecture Here's a highly simplified diagram of the system in question: And here's a sequence diagram showing the flow of the request through the main components of the architecture: And here's a sequence diagram showing the flow of the request through the main components of the architecture: Your junior teammate, Casey, has time to work on the problem this afternoon. Choose 2 promising directions from your list and spend 15-20 minutes writing the best email you can explaining how they can make progress debugging while you're unavailable. Casey is smart, but doesn't have much experience debugging performance issues, so you should be very clear in your instructions. Include any specific tools they should use, commands they should try, error messages to watch out for, etc