Distributed tracing is used to analyze performance and error cases in service oriented architectures. The Observability team at Airbnb recently created Upshot, a data pipeline that uses Flink to analyze over 40 million trace events per minute. Summaries of the resulting data are sent to Druid, Datadog, and other downstream datastores. This talk will focus on how we use Flink and how we analyzed and addressed scaling issues we encountered while building Upshot.