Debugging performance issues

  • Go to the Dashboard page, and have a look at the Service Latency widget at the bottom right. This shows you the tail latency for services that you are calling from your Lambda functions.

service latency

  • By default, this widget is sorted by the p95 (ms) column. Somewhere amongst the top, you might see similar to up there, by either p95 (ms) or p99 (ms).

slow dependency

  • Click on the p99 latency value (454 in my case)

click on the p99 value

This takes you to the Explore page with a prefilled query that finds the transactions where this service was involved and recorded a latency that’s equal to or greater than the latency value you clicked on.

find slow transactions

  • Click on one of these transaction to see what happened.

slow transaction

In this transaction, you can see that we made 3 calls to

  • Click on the Timeline tab and you will see that one of the requests to took 4345ms.

transaction timeline

  • Click on the slow HTTP request, and see that the response was for Bucephalus.

slow request

  • Go back to the Explore page and find other transactions where had been slow. See if you can spot any commonalities to these slow requests.