Hang with markdown-mode

Hang with markdown-mode

[Leo]

The problem 
----------- 

I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following: 

1.  Start emacs 
2.  Create a new file, say, with name changetest.txt. 
3.  Put (or keep) it in markdown-mode. 
4.  Write some text in changetest.txt and save the file to disc. 
5.  Switch to another buffer, so that that buffer changetest.txt is not 
    visible. 
6.  Open the file changetest.txt in another editor. 
7.  Change and save the content in this other editor. 
8.  Go back to emacs and switch buffer to changetest.txt. 

You will get the message 

    changetest.txt changed on disk; really edit the buffer? (y, n, r or C-h) 

But then emacs will hang; no input will get you through the question prompt and keyboard-quit does nothing, so you have to kill emacs. 

Results of my investigation 
--------------------------- 

-  The problem arises only in markdown mode. 
-  The "changed on disk" message is issued by 
    ask-user-about-supersession-threat. 

Via debug-on-error I was able to locate the problem a bit more in detail: 

-  It seems like the hang occurs through an endless recursion or loop in markdown-check-change-for-wiki-link which is triggered when emacs switches to the changetest.txt buffer. 
-  markdown-check-change-for-wiki-link is triggered through the window-configuration-change-hook hook. 

Questions 
--------- 

-  How can I avoid this, but keep the 
    markdown-check-change-for-wiki-link functionality? 
-  Is window-configuration-change-hook maybe not the right hook to put markdown-fontify-buffer-wiki-links in? 

Thanks, Leo 

Re: Hang with markdown-mode

[Tim Visher]

That sounds like a bug. You could report it to M. Blevins
(http://jblevins.org/projects/markdown-mode/markdown-mode.el), but be
advised that the latest version available on his site is 2.0 so you
might want to try upgrading before you report the bug.

On Mon, Nov 25, 2013 at 1:52 AM, Leo <leoslists@letterboxes.org> wrote:
> The problem
> -----------
>
> I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following:
>
> 1.  Start emacs
> 2.  Create a new file, say, with name changetest.txt.
> 3.  Put (or keep) it in markdown-mode.
> 4.  Write some text in changetest.txt and save the file to disc.
> 5.  Switch to another buffer, so that that buffer changetest.txt is not
>     visible.
> 6.  Open the file changetest.txt in another editor.
> 7.  Change and save the content in this other editor.
> 8.  Go back to emacs and switch buffer to changetest.txt.
>
> You will get the message
>
>     changetest.txt changed on disk; really edit the buffer? (y, n, r or C-h)
>
> But then emacs will hang; no input will get you through the question prompt and keyboard-quit does nothing, so you have to kill emacs.
>
> Results of my investigation
> ---------------------------
>
> -  The problem arises only in markdown mode.
> -  The "changed on disk" message is issued by
>     ask-user-about-supersession-threat.
>
> Via debug-on-error I was able to locate the problem a bit more in detail:
>
> -  It seems like the hang occurs through an endless recursion or loop in markdown-check-change-for-wiki-link which is triggered when emacs switches to the changetest.txt buffer.
> -  markdown-check-change-for-wiki-link is triggered through the window-configuration-change-hook hook.
>
> Questions
> ---------
>
> -  How can I avoid this, but keep the
>     markdown-check-change-for-wiki-link functionality?
> -  Is window-configuration-change-hook maybe not the right hook to put markdown-fontify-buffer-wiki-links in?
>
> Thanks, Leo
>

Re: Hang with markdown-mode

[leo]

Still happens in 2.0.

I’m sure it’s a bug, but I’m interested in a suitable workaround: Where should fortifying normally be done: In the window-configuration-change-hook or elsewhere?

Thanks, Leo

On 25 Nov 2013, at 10:36 pm, Tim Visher <tim.visher@gmail.com> wrote:

> That sounds like a bug. You could report it to M. Blevins
> (http://jblevins.org/projects/markdown-mode/markdown-mode.el), but be
> advised that the latest version available on his site is 2.0 so you
> might want to try upgrading before you report the bug.
> 
> On Mon, Nov 25, 2013 at 1:52 AM, Leo <leoslists@letterboxes.org> wrote:
>> The problem
>> -----------
>> 
>> I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following:
>> 
>> 1.  Start emacs
>> 2.  Create a new file, say, with name changetest.txt.
>> 3.  Put (or keep) it in markdown-mode.
>> 4.  Write some text in changetest.txt and save the file to disc.
>> 5.  Switch to another buffer, so that that buffer changetest.txt is not
>>    visible.
>> 6.  Open the file changetest.txt in another editor.
>> 7.  Change and save the content in this other editor.
>> 8.  Go back to emacs and switch buffer to changetest.txt.
>> 
>> You will get the message
>> 
>>    changetest.txt changed on disk; really edit the buffer? (y, n, r or C-h)
>> 
>> But then emacs will hang; no input will get you through the question prompt and keyboard-quit does nothing, so you have to kill emacs.
>> 
>> Results of my investigation
>> ---------------------------
>> 
>> -  The problem arises only in markdown mode.
>> -  The "changed on disk" message is issued by
>>    ask-user-about-supersession-threat.
>> 
>> Via debug-on-error I was able to locate the problem a bit more in detail:
>> 
>> -  It seems like the hang occurs through an endless recursion or loop in markdown-check-change-for-wiki-link which is triggered when emacs switches to the changetest.txt buffer.
>> -  markdown-check-change-for-wiki-link is triggered through the window-configuration-change-hook hook.
>> 
>> Questions
>> ---------
>> 
>> -  How can I avoid this, but keep the
>>    markdown-check-change-for-wiki-link functionality?
>> -  Is window-configuration-change-hook maybe not the right hook to put markdown-fontify-buffer-wiki-links in?
>> 
>> Thanks, Leo
>> 

Re: Hang with markdown-mode

[Stefan Monnier]

> Where should fontifying normally be done: In the
> window-configuration-change-hook or elsewhere?

I don't know what it does, but based on its name, I'd suggest it
could/should be done via font-lock-keywords.


        Stefan

Re: Hang with markdown-mode

[Joost Kremers]

Leo wrote:
> The problem 
> ----------- 
>
> I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following: 
>
> 1.  Start emacs 
> 2.  Create a new file, say, with name changetest.txt. 
> 3.  Put (or keep) it in markdown-mode. 
> 4.  Write some text in changetest.txt and save the file to disc. 
> 5.  Switch to another buffer, so that that buffer changetest.txt is not 
>     visible. 
> 6.  Open the file changetest.txt in another editor. 
> 7.  Change and save the content in this other editor. 
> 8.  Go back to emacs and switch buffer to changetest.txt. 
>
> You will get the message 
>
>     changetest.txt changed on disk; really edit the buffer? (y, n, r or C-h) 
>
> But then emacs will hang; no input will get you through the question prompt and keyboard-quit does nothing, so you have to kill emacs. 

I've actually run into the very same thing, although it was not with
Markdown mode (which I also use). Instead, it happened with org-mode
buffers that changed on disk because a new version of the file was
synced from Dropbox.

I haven't seen the bug in a while, however, and I haven't investigated
it. There are two things that changed since I saw the bug that might be
relevant: I downgraded from emacs-snapshot to the latest release 24.3.1
(though since you're using that same version, that probably isn't it)
and I unset `auto-save-visited-file-name`, which I used to have set.

Do you happen to have `auto-save-visited-file-name` set to t? And did
you try with `emacs -Q`?


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: Hang with markdown-mode

[leo]

On 26 Nov 2013, at 3:06 am, Joost Kremers <joost.m.kremers@gmail.com> wrote:

> Leo wrote:
>> The problem 
>> ----------- 
>> 
>> I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following: 
>> 
>> […]

> I've actually run into the very same thing, although it was not with
> Markdown mode (which I also use). Instead, it happened with org-mode
> buffers that changed on disk because a new version of the file was
> synced from Dropbox.

Yep, I experienced the issue first from Dropbox, too - just the external modification is causing the issue.

> […]
> 
> Do you happen to have `auto-save-visited-file-name` set to t? 

Checked `auto-save-visited-file-name’ and for me it’s (globally and otherwise) nil.

> And did you try with `emacs -Q`?

Just tried it - and I get the same problem (once I have loaded markdown-mode.el and applied it to a buffer).

Not sure how I can fix it — might try to take the fortifying out…

Cheers, Leo

Re: Hang with markdown-mode

[danielrairigh]

On Tuesday, November 26, 2013 4:30:02 AM UTC-5, leo wrote:
> >> The problem 
> 
> >> ----------- 
> 
> >> 
> 
> >> I use markdown-mode 1.9 in emacs 24.3.1 and I get a consistent hang when I do the following: 
> 
> >> 
[...]
> Not sure how I can fix it — might try to take the fortifying out…
> 
> 
> 
> Cheers, Leo

Hello Leo,

Did you have any luck in solving this issue. I am having a nearly identical problem (Emacs 24.3.1 & Markdown 2.0) and have yet to find a solution.

Thanks,
  Daniel

Re: Hang with markdown-mode

[news]

On Tuesday, January 7, 2014 1:44:50 AM UTC+11, daniel...@gmail.com wrote:

> [...]
> 
> 
> Hello Leo,
> 
> 
> 
> Did you have any luck in solving this issue. I am having a nearly identical problem (Emacs 24.3.1 & Markdown 2.0) and have yet to find a solution.
> 
> 
> 
> Thanks,
> 
>   Daniel

Hi Daniel

Yes, recently I have solved the problem by unbinding `markdown-fontify-buffer-wiki-links`:

    (defun leo-markdown-fontify-buffer-wiki-links-empty ()
      "Empty replacement for `markdown-fontify-buffer-wiki-links` due to hanging bug."
      (interactive))

    (eval-after-load "markdown-mode"
        '(progn
           (fset 'markdown-fontify-buffer-wiki-links 
                 'leo-markdown-fontify-buffer-wiki-links-empty)))

But this is of course only a crutch...

HTH, Leo