Consider using Timing Wheels for the deadlines

[Thomasdezeeuw]

From the paper: "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for Implementing a Timer Facility" by George Varghese and Anthony Lauck.

[Thomasdezeeuw]

Summary of the paper: https://blog.acolyer.org/2015/11/23/hashed-and-hierarchical-timing-wheels. Usage in Kafka: https://www.confluent.io/blog/apache-kafka-purgatory-hierarchical-timing-wheels.