One of the design goals for LSP is that it is not in-process. Process isolation gives the text editor stability in the face of unstable plugins and allows multi

One of the design goals for LSP is that it is not in-process. Process isolation gives the text editor stability in the face of unstable plugins and allows multiple language servers to run concurrently without requiring the target language (which could be anything) to support threads and a C ABI - something which many languages have no need for. Furthermore, many languages ship with a runtime which does not play nice with other runtimes. Try running a JVM, .NET VM, Golang runtime, and Erlang BEAM VM in the same process and see what happens. Better yet, try debugging it.