From: miha--- via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: "João Távora" <joaotavora@gmail.com>
Cc: Michael Albinus <michael.albinus@gmx.de>, 62194@debbugs.gnu.org
Subject: bug#62194: 30.0.50; Two Eglot-over-Tramp tests are failing on master, passing on emacs-29
Date: Fri, 17 Mar 2023 17:45:43 +0100 [thread overview]
Message-ID: <875yaziax4.fsf@miha-pc> (raw)
In-Reply-To: <CALDnm51hL3MtaneGJHqqe4RYEmkYp7sZpZrPjqYiHN7_CvN86g@mail.gmail.com>
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João Távora <joaotavora@gmail.com> writes:
>> I think that accept-process-output with JUST-THIS-ONE=nil is dangerous
>> here. We are now allowing 'file-exists-p', 'expand-file-name' and all
>> other functions listed in 'tramp-sh-file-name-handler-alist' to call any
>> timer or process filter,
>
> That's exactly what we want. We _don't_ want to stop other
> output to be inhibited from going into the filter. We want
> to let other processes slurp their input as often as possible.
Generally, I agree. JUST-THIS-ONE=nil is better and it's fine to use it
in most functions as long as the programmer is careful that foreign
timers and proc filters won't interfere. Though I do think that if a
function that calls a-p-o with JUST-THIS-ONE=nil isn't internal, it
should mention that it can run timers in its doc string.
But here we are talking about 'expand-file-name' and other functions
from tramp-sh-file-name-handler. For these, I disagree that we want them
to accept output from other processes and call their filters.
'expand-file-name' and others are used often and, for most of the
existence of Emacs, they did not call proc filters. I think it's
dangerous to have them do it now.
> The reason it hung with JUST-THIS-ONE=t is precisely the inverse
> reason that it hangs without this hunk (say, in emacs-29). One
> process (say tprocess) is holding its input and jprocess can't read
> it because it comes from a shared underlying SSH buffer and that
> buffer is likely full (until tprocess empties it a little bit).
>
> At the moment, it is the best we have, both theoretically and
> experimentally.
>
>> without even documenting this.
>
> This is the most normal usage of accept-process-output.
> Look at all the Emacs code base. Basically, only Tramp uses
> JUST-THIS-ONE. It's JUST-THIS-ONE who is the aberration.
> None of the process-heavy SLIME, SLY, CIDER IDEs use it.
>
> You can read the manual about JUST-THIS-ONE. It's in A-O-P.
Sorry I wasn't clear enough. I meant documenting in expand-file-name's
doc string that calling expand-file-name can now run arbitrary process
filters and timers. The same goes for other functions from
'tramp-sh-file-name-handler-alist'.
>> filter may call 'read-passwd', entering a recursive edit, in which the
>> user can kill any buffer or even a process. Or with midnight-mode
>> enabled, a timer kills buffers older than 3 days. I consider these "the
>> problem of timing errors that usually plague parallel programming", to
>> quote '(elisp) Output from Processes'.
>
> Sorry, I don't immediately see the problem. I can't prove that there
> isn't one :-) that's near impossible. Normally what is done
> is for the problem to be demonstrated with some experiment.
>
>> I'm not saying that my proposal with SIGWINCH is flawless and I agree
>> that its unacceptable. I'm just saying that we shouldn't be quite
>> satisfied with this solution yet, though it should be fine for some
>> time.
>
> I'm not satisfied with it myself. This is very slow (not that it matters
> much). But is also all around ugly. The more correct solution is IMHO,
> described in bug#61350. But it will take time to see if it fits into
> Tramp (I think it does) but most importantly how (that's the hard bit,
> Tramp is a lot of code)
I'm not against your way of refactoring tramp process filters but I
don't think it will solve our problems in any fundamental way for the
following simple reason:
'expand-file-name' is synchronous, therefore tramp has to make it use
accept-process-filter (tell me if there's another way). It can use it in
roughly two ways: with JUST-THIS-ONE=t or JUST-THIS-ONE=nil. In the
first case, we hit the eglot-over-ssh freeze problem and in the second
case, we'll have 'expand-file-name' call timers and process filters,
which I explained above why I don't like.
>> What I was thinking was perhaps to introduce a function called
>> 'accumulate-process-output' which would be similar to
>> 'accept-process-output', except that it would only save process output
>
> You can propose this in emacs-devel, but if you permit me to
> be slightly immodest, I've been coding with
> accept-process-output + filters for almost 15 years and I've never
> had the need for this. I normally want timers and other processes
> to run, I don't want to stop the world.
This is great for other packages, but tramp.el carries the special
burden of having to re-implement 'expand-file-name' and other functions
of synchronous nature.
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next prev parent reply other threads:[~2023-03-17 16:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-14 23:08 bug#62194: 30.0.50; Two Eglot-over-Tramp tests are failing on master, passing on emacs-29 João Távora
2023-03-15 9:40 ` Michael Albinus
2023-03-15 11:45 ` Michael Albinus
2023-03-15 20:24 ` João Távora
2023-03-15 20:36 ` miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-03-15 20:45 ` João Távora
2023-03-16 12:02 ` Michael Albinus
2023-03-16 12:20 ` João Távora
2023-03-16 14:57 ` Michael Albinus
2023-03-16 15:12 ` João Távora
2023-03-16 17:35 ` Michael Albinus
2023-03-16 17:59 ` João Távora
2023-03-16 21:18 ` miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-03-16 21:57 ` João Távora
2023-03-16 23:38 ` João Távora
2023-03-17 16:45 ` miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2023-03-17 16:47 ` Eli Zaretskii
2023-03-17 17:22 ` miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-03-17 17:22 ` Eli Zaretskii
2023-03-17 10:44 ` Michael Albinus
2023-03-17 11:19 ` João Távora
2023-03-18 9:38 ` Michael Albinus
2023-03-18 11:29 ` João Távora
2023-03-18 12:23 ` Michael Albinus
2023-03-18 12:33 ` João Távora
2023-03-19 12:19 ` Michael Albinus
2023-03-15 20:16 ` João Távora
2023-03-16 15:02 ` Michael Albinus
2023-03-28 10:51 ` Michael Albinus
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