bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Lars Ingebrigtsen]

And that obviously sucks, especially when you're trying to set up a new
machine.

I think the way to reproduce this error is to have the network
configured, but not actually working.  I suspect that Emacs is doing
some DNS stuff at startup that it shouldn't be doing.


In GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2018-04-15 built on corrigan
Repository revision: 1ad6184c37a0e0f537688ea7d5e6ceca5f364eaa
Windowing system distributor 'The X.Org Foundation', version 11.0.11902000
System Description: Debian GNU/Linux 9 (stretch)


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Lars Ingebrigtsen]

Hm.  Or has this finally been fixed, after all these years?  I'm unable
to reproduce it now on my laptop, but perhaps I'm confing the network
"wrong" in the wrong way...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Noam Postavsky]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> I think the way to reproduce this error is to have the network
> configured, but not actually working.  I suspect that Emacs is doing
> some DNS stuff at startup that it shouldn't be doing.

> Hm.  Or has this finally been fixed, after all these years?  I'm unable
> to reproduce it now on my laptop, but perhaps I'm confing the network
> "wrong" in the wrong way...

It sounds like this entry in etc/PROBLEMS

    *** Emacs startup on GNU/Linux systems (and possibly other systems) is slow.

    This can happen if the system is misconfigured and Emacs can't get the
    full qualified domain name, FQDN.  You should have your FQDN in the
    /etc/hosts file, something like this:

    127.0.0.1	localhost
    129.187.137.82	nuc04.t30.physik.tu-muenchen.de	nuc04

    The way to set this up may vary on non-GNU systems.

According to this message from 2014 [1] it was resolved, and the
etc/PROBLEMS entry was removed.  But the entry is still there in current
master.

[1]: https://lists.nongnu.org/archive/html/emacs-devel/2014-12/msg02313.html

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Lars Ingebrigtsen]

Noam Postavsky <npostavs@gmail.com> writes:

> According to this message from 2014 [1] it was resolved, and the
> etc/PROBLEMS entry was removed.  But the entry is still there in current
> master.

Hm...  I remember running into this a couple of weeks ago on a Debian
jessie system, and the Emacs there is...  let's see...  25.1.1.  That's
after 2014, I think, so perhaps that explains why it returned?

vc-mode seems to say that it's been in etc/PROBLEMS since around
2001-2004.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 776 bytes --]

> According to this message from 2014 [1] it was resolved, and the
> etc/PROBLEMS entry was removed.  But the entry is still there in current master.

That's due to a botched merge of etc/PROBLEMS in March 2015. Thanks for 
mentioning it. I installed the attached patch into master to fix it.

> I remember running into this a couple of weeks ago on a Debian
> jessie system, and the Emacs there is...  let's see...  25.1.1.  That's
> after 2014

Yes, the problem that I fixed in 2014 should not be present in Emacs 
25.1. Of course there could be some other problem with similar symptoms. 
I can't reproduce the symptoms, though. I tried running Emacs master on 
Fedora 27 with networking disabled (using Gnome's "Wired Connected > 
Turn Off" UI), and Emacs started up fine.

[-- Attachment #2: 0001-Fix-botched-merge-of-FQDNs-in-PROBLEMS.patch --]
[-- Type: text/x-patch, Size: 1333 bytes --]

From d816676fb40960ec6cf124ff386571ac1e5a3278 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 18 Apr 2018 17:12:56 -0700
Subject: [PATCH] Fix botched merge of FQDNs in PROBLEMS

This text was originally removed in
2014-12-30T04:42:26Z!eggert@cs.ucla.edu but then was
mistakenly re-added in the merge in
2015-03-23T17:30:30Z!eggert@cs.ucla.edu.
* etc/PROBLEMS: Omit obsolete mention of FQDNs.
---
 etc/PROBLEMS | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 0797176619..d19efaae68 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -555,17 +555,6 @@ And then rename the system's readline so that it won't be loaded:
 See <https://pypi.python.org/pypi/gnureadline> for more details on
 installation.
 
-*** Emacs startup on GNU/Linux systems (and possibly other systems) is slow.
-
-This can happen if the system is misconfigured and Emacs can't get the
-full qualified domain name, FQDN.  You should have your FQDN in the
-/etc/hosts file, something like this:
-
-127.0.0.1	localhost
-129.187.137.82	nuc04.t30.physik.tu-muenchen.de	nuc04
-
-The way to set this up may vary on non-GNU systems.
-
 *** Visiting files in some auto-mounted directories causes Emacs to print
 'Error reading dir-locals: (file-error "Read error" "is a directory" ...'
 
-- 
2.14.3

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Lars Ingebrigtsen]

Paul Eggert <eggert@cs.ucla.edu> writes:

>
>> I remember running into this a couple of weeks ago on a Debian
>> jessie system, and the Emacs there is...  let's see...  25.1.1.  That's
>> after 2014
>
> Yes, the problem that I fixed in 2014 should not be present in Emacs
> 25.1. Of course there could be some other problem with similar
> symptoms.

I was mistaken -- the system in question has Emacs 24.4.1 installed.
Does that version include your fix?

> I can't reproduce the symptoms, though. I tried running Emacs master
> on Fedora 27 with networking disabled (using Gnome's "Wired Connected
>  > Turn Off" UI), and Emacs started up fine.

In those cases (where the system knows that it has lost the network
connection), then Emacs starts up fast.  The problem is if the network
is up, but non-functional.

I've tried to reproduce it on a wired machine now just by pulling the
plug, but that didn't work, either.  Hm...  

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Paul Eggert]

On 04/23/2018 12:50 PM, Lars Ingebrigtsen wrote:
> Paul Eggert <eggert@cs.ucla.edu> writes:
>
>>> I remember running into this a couple of weeks ago on a Debian
>>> jessie system, and the Emacs there is...  let's see...  25.1.1.  That's
>>> after 2014
>> Yes, the problem that I fixed in 2014 should not be present in Emacs
>> 25.1. Of course there could be some other problem with similar
>> symptoms.
> I was mistaken -- the system in question has Emacs 24.4.1 installed.
> Does that version include your fix?

No. So perhaps the problem is fixed after all.

bug#31167: 27.0.50; When the computer has no network connection, Emacs can take minutes to start

[Lars Ingebrigtsen]

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 04/23/2018 12:50 PM, Lars Ingebrigtsen wrote:
>> Paul Eggert <eggert@cs.ucla.edu> writes:
>>
>>>> I remember running into this a couple of weeks ago on a Debian
>>>> jessie system, and the Emacs there is...  let's see...  25.1.1.  That's
>>>> after 2014
>>> Yes, the problem that I fixed in 2014 should not be present in Emacs
>>> 25.1. Of course there could be some other problem with similar
>>> symptoms.
>> I was mistaken -- the system in question has Emacs 24.4.1 installed.
>> Does that version include your fix?
>
> No. So perhaps the problem is fixed after all.

Yes.

But I've now tried reproducing this on a different machine with 24.4.1
(since the one I experienced the problem on is now a production server
:-)) and any combination of setting up bad routing tables, on the
machine itself and on the router, doesn't manage to trigger the
problem...

This is all so odd.  I guess I have to make precise notes on what the
state of the networking is the next time I see this thing so that I can
test the same thing on a newer Emacs...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no