Use an UtilityProcess for the extension host

[alexdima]

When launching with VSCODE_USE_UTILITY_PROCESS=1, will use the new UtilityProcess Electron proposed API for the extension host, and use a MessageChannel instead of a named pipe for renderer <-> ext host communication.

Observed problems with UtilityProcess implementation:

• all env values must be strings, otherwise the env is ignored.
• args/execArgv shapes are different compared to nodejs
• on('spawn') / on('exit') are never fired
• ❗ cannot observe that a process exits gracefully (exit code 0) -- causes the shutdown to always take 6s

To test:

• check that the extension host process can be brought into debugging mode (e.g. via profiling)

[deepak1556]

Thanks for setting this up!

1. all env values must be strings

It was based on type mentioned in https://github.com/nodejs/node/blob/b92bc5931dcc09fda5050ae8a870602d1f6f3c9a/lib/child_process.js#L101, so values were converted natively to a std::map<std::string, std::string>

args don't make it across

Can you clarify which args don't make it ?

kill() takes number, not string

Oh it should support both, which signal did you try ?

on('spawn') is never fired

Confirmed the bug, will address it.

pid is undefined initially

Yeah this behavior is different from the child_process.fork, pid will be valid after spawn event. The reason being we don't perform the actual fork but delegate to chromium for launching the process which makes the process launch async.

Additional note:

exit event only gets emitted for normal termination code is 0 of the process, for all other process terminations we should listen to https://github.com/electron/electron/blob/main/docs/api/app.md#event-child-process-gone event.