Handling billions of events per day with Kotlin Coroutines
summary
Migrates a 12 year Java app to Kotlin Coroutines and almost doubles throughput while processing billions of events per day with millisecond latency, yielding a 25% cost reduction (millions $ annually). Replaces Jetty with Vertx, rewrites filters and controllers to suspendables, converts hot Cassandra paths to nonblocking driver calls via coroutines and later to Kotlin Flow. Chronicles surprises: request scope DI via thread context elements, CPU microbursts, failed canaries, splitting heavy logic into a gRPC Spring Boot service before success.
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chapters (10)
- 0:00Start
- 3:00Request processing flow
- 3:57Application structure
- 5:42Business logic
- 12:20Data Access API | Hidden blocking operation
- 13:07Data Access API -Non-blocking transformation
- 23:26Production performance
- 27:31Flame Graph
- 33:48The refined architecture
- 35:43Lessons learned
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