This Python library was evolved at IronPort Systems and has been provided as open source by Cisco Systems under an MIT license.
Shrapnel is a high-performance threading/coroutine library built around FreeBSD's kqueue() system call. It's designed for single-process servers that can handle 10,000+ simultaneous network connections.
Cisco/IronPort open sourced Python Coroutine library Shrapnel | Heykuki News