bug#62093: [PATCH] Let processes read nothing from stdin in tramp

[Aleksander Trofimowicz via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Hi Michael,

Michael Albinus <michael.albinus@gmx.de> writes:

> I wanted to let you know that I found time to check this. Thanks for the
> patch.
>
Thank you for looking into this issue.

> The failed test runs have in common that there is a complex Tramp target
> for the test using multi-hops, like above. I suspect a problem with
> timing due to the several hops, but I don't know exactly what's up.
>
Triggered by your multi-hop tests (host B via host A) I run git-apply
actions over Tramp with the patch I submitted. I settled with 3
different test environment configurations; all of them should provide
the same functionality:

1. An explicit multi-hop target "/ssh:host_A|/ssh:host_B:..."

2. The SSH client option ProxyCommand set to "ssh host_A nc host_B 22" and
simple "/ssh:host_B"

3. The SSH client option ProxyJump set to "host_A" and simple "/ssh:host_B"

tramp-use-connection-share was set to nil in each case.

It worked as expected only in the first two cases. As far as the last one
is concerned, the workflow wasn't stalled, but it turned out to be no-op
after all.

It seems the last test environment enables the most responsive data
stream: no additional userland process is forked on a middle box and
Nagle's algorithm is disabled for all TCP connections involved (which is
not true for the case no 2.). In the end such results might corroborate
your theory.

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