Re: master 2c79a8f 2/2: Use posix_spawn if possible.

["Jostein Kjønigsen" <jostein@secure.kjonigsen.net>]

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Like Saulius says, this is fairly technical and far above at least my head.

I still think it's worth discussing if we *need* this change for Linux. 
When the original commit was landed, (from what I can tell) it was 
because it was needed for Mac, and assumed harmless for other platforms. 
The merge to master was then meant as a testing-ground to see if it 
would cause issues.

And well.. Here's at least one issue :)

For perspective, over the last couple of years, Emacs as a 
editor/platform to work with .NET has improved tremendously to the point 
that Emacs is my primary editor for anything .NET. It would be a shame 
to see that completely break on Emacs 29, and being forced to use VSCode 
to get work done.

As things stand now, I think it sounds easier to revert this change (for 
Linux only) than trying to convince Microsoft to change the .NET runtime 
to better interop with Emacs on Linux :)

My 2 cents.

--
Kind regards
Jostein Kjønigsen

On 25.01.2022 09:58, Saulius Menkevicius wrote:
> Sorry I did not mention the platform, this happens on Linux/x64 and 
> has been reported by multiple persons:
>
> - https://github.com/razzmatazz/csharp-language-server/issues/12
>
>
> The issue has been noticed when dotnet-based LSP servers are used with 
> emacs/lsp-mode, -- in particular lsp-mode starts the server using 
> `make-process` and then communicates over stdio. Link to the code that 
> launches the server:
>
> - https://github.com/emacs-lsp/lsp-mode/blob/master/lsp-mode.el#L6925
>
>
> We have csharp-ls and fsac servers launched with the same mechanism as 
> are for other languages -- which are working ok with posix_spawn 
> enabled. It only breaks for those before-mentioned LSP servers that 
> are implemented on top of dotnet and use dotnet runtime (same thing as 
> JVM, but for C#/F#/CLR languages).
>
> Now it appears, that switch to posix_spawn broke communication over 
> stdio to those dotnet-based LSP servers for some technical reason, -- 
> I didn't investigate yet why, because it is a bit over my head. I 
> *think* there is an interplay between posix_spawn-based process launch 
> implementation in emacs and dotnet runtime stdio abstractions/platform 
> layer -- because otherwise other language servers work with that 
> commit that enables posix_spawn, like those based on JVM too.
>
>
> I know this is a bit of a corner case as posix_spawn brings 
> performance benefits, but just FYI.
>
> BR,
>
> -Saulius Menkevicius
>
>
> Am 25.01.22 um 10:41 schrieb Eli Zaretskii:
>> On January 25, 2022 8:48:12 AM GMT+02:00, Saulius Menkevicius 
>> <sauliusmenkevicius@fastmail.com> wrote:
>>> Hi,
>>>
>>> I know this has been merged a couple of months ago to `master` but I
>>> would like to report breakage that occurs due to that commit.
>>>
>>> We have csharp-ls (C#) and fsautocomplete (F#) LSP servers that stopped
>>> working with that commit (git-bisected to
>>> a60053f8368e058229721f1bf1567c2b1676b239).
>>>
>>> I did not delve too much into the details or prepare a minimal test 
>>> case
>>> but this appears to be an interplay between dotnet runtime (v6) and
>>> posix_spawn.
>>>
>>> Not sure if that warrants a revert but just a heads-up.
>> Can you explain how dotnet runtime comes into play here?  Does Emacs 
>> invoke a dotnet process or something?
>>
>> And on what OS does this happen?
>
-- 
Vennlig hilsen
*Jostein Kjønigsen*

jostein@kjonigsen.net 🍵 jostein@gmail.com 🍵 jostein@hufleslufs.no
https://jostein.kjønigsen.no <https://jostein.kjønigsen.no>

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