Abstract:- Today's enterprises are not only producing data in high volume but also at high velocity. With velocity comes the need to process the data in real time. To meet the real time needs, we developed and deployed Heron, the next generation streaming engine at Twitter. Heron processes billions and billions of events per day at Twitter and has been in production for nearly 3 years. Heron provides unparalleled performance at large scale and has been successfully meeting Twitter's strict performance requirements for various streaming and iOT applications. Heron is a open source project with several major contributors from various institutions. As the project, we identified and implemented several optimizations that improved throughput by additional 5x and further reduce latency by 50-60%. In this talk, we will describe Heron in detail, how the detailed profiling indicated the performance bottleneck areas such as multiple serializations/deserialization and immutable data structures. After mitigating these costs, we were able to show much higher throughput and latencies as low as 12ms.