Consider creating file-lock to prevent multiple instances of project-manager being started

[hubertp]

As suggested in #6857 (comment).

I guess one potential downside is making sure that project-manager cleans up that file lock on shutdown. And, as it is with shutdowns, they are not always done in a clean way.

[wdanilo]

Why multiple instances of project manager could not be started? We should allow for multiple instances of Enso (and in the future for tabbed projects). So, multiple engines are a very valid scenario.

[jdunkerley]

The project manager launches separate language servers but we should only have project manager running on a machine.

We can then ensure we don't have 2 instance of language servers against the same project, but can have as many language servers against different projects as we wish.

The child process model of electron to launce the PM would need revisiting.

[wdanilo]

Oh, ok, if this will support multiple Enso instances then great. I was thinking that each instance requires a separate project manager.

[JaroslavTulach]

potential downside is making sure that project-manager cleans up that file lock on shutdown

With CLIHandler that's not issue at all! Stale lock files are detected as stale.