This is RoadRunner. RoadRunner is infrastructure level framework for your PHP applications written in Golang. It runs your application in the form of workers.
On Golang end RoadRunner runs your PHP application on goroutine and balances the incoming payloads between multiple workers.
The data can be received from the HTTP request, AWS Lambda, Queue or any other way.
RoadRunner keeps PHP worker alive between incoming requests. It means that you can completely eliminate bootload time (such as framework initialization) and speed up a heavy application a lot.
Since worker is located in resident memory, all the open resources will remain open for the next request. Using Goridge RPC you can quickly offload some of the complex computations to the application server. For example, schedule a background PHP job.