Re: sshx protocol from MS Windows occasionally cuts off results in M-x rgrep

[Jim Porter]

On Wed, May 5, 2021 at 9:35 AM Michael Albinus <michael.albinus@gmx.de> wrote:
>
> Jim Porter <jporterbugs@gmail.com> writes:
>
> > If I run these manually in cmd.exe, the command prompt closes
> > immediately. If I'm understanding things correctly, I think that's
> > because of the `exit' in the first command and the `exec' in the
> > second. If I open a subshell (by running cmd.exe in an existing
> > command prompt), the window stays open and I can see the output. I've
> > tried a bunch of times, but I'm completely unable to reproduce the
> > issue when running in cmd.exe. That suggests to me that the MS Windows
> > ssh client is working ok, or at least that any bugs here can be
> > avoided if we're careful.
>
> I've tried all these tests (manual invocation of ssh etc pp) already
> yesterday, with the same result as you. It works.
>
> Interestingly, there's no such problem when using plink, which uses the
> same command sequence. That lets me think it is an ssh client problem,
> buffering the output or whatever. But I might be wrong.

Indeed, it's hard to say for sure what's going wrong, since I still
haven't been able to isolate the bug. I did make a bit of progress
though. First, I eliminated the need to use `M-x rgrep' on the Tramp
repository. The attached Python script (which just prints the text
copied from the previous `M-x rgrep' output one line at a time) also
reproduces the issue fairly reliably if invoked via `M-x compile RET
python3 test.py RET' over sshx from MS Windows.

However, I *don't* see this issue when I run `M-x shell-command RET
python3 test.py RET'. I always see the full output. This makes me
wonder if the issue is actually in `M-x compile'. I'm not
super-familiar with all the differences between how `shell-command'
and `compile' invoke a process, but maybe there's some sort of issue
with buffering in `compile.el' that's causing this?

I'll keep debugging this to see if I can narrow this down further.

- Jim

mock-grep.py
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