Hi again @JimZakapar…
No, Solace PubSub+ is not open source. Although with the Standard Edition broker, it follows the open source commercial model… completely/forever free, fully-featured (e.g. HA and DR included), with optional paid support. We have many customers who are using the free Standard Edition in production, and just pay us for support.
The broker is coded in C and C++, designed to be as lock-free and non-blocking as possible, with various parts of the internal event processing stream parallelized for multi-core support. It was built with performance in mind from day one.
Finally, check this blog, hopefully it helps: https://solace.com/blog/how-to-deploy-a-solace-pubsub-event-broker-to-digitalocean/