Apache Mesos has a very solid, clean and well maintained code base (https://github.com/apache/mesos https://github.com/apache/mesos). It’s a massively scalable

Apache Mesos has a very solid, clean and well maintained code base (https://github.com/apache/mesos https://github.com/apache/mesos). It’s a massively scalable distributed system that has been running in production for many years at Twitter, Apple, Netflix and other places (more recently it’s being replaced by Kubernetes, but that’s beside the point of this thread). Mesos is interesting as a whole but it also has some parts that are notoriously hard to get right (like their Paxos implementation). It also contains an RPC library that implements an actor model and uses futures and promises (https://github.com/apache/mesos/tree/master/3rdparty/libprocess https://github.com/apache/mesos/tree/master/3rdparty/libproc...), as well as a header-only utility library called Stout (https://github.com/apache/mesos/tree/master/3rdparty/stout https://github.com/apache/mesos/tree/master/3rdparty/stout) with a lot of useful functions.