bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

[Kjetil S. Matheussen]

BACKGROUND
----------
Emacs makes inferior-scheme and inferior-lisp hang when you evaluate
a large block of code which is directly followed by a hash (#).

This is a bug I've encountered numerous times for many
years. I'm currently using emacs-cvs from 2008-07-04
though.

It does not seem to matter which implementation of
scheme or common lisp is running as inferior-scheme
or inferior-lisp.



HOW TO PROVOCE THE HANG IN SCHEME
---------------------------------
This should be an exact recipe on how to make inferior-scheme hang:

1. Load this file into emacs:
    http://www.notam02.no/~kjetism/emacsbug.scm

2. Start scheme by using M-x run-scheme

3. Place the cursor on to line 2 of emacsbug.scm and
    evaluate the block by pressing C-M-x. If the cursor
    is placed on line 1, scheme won't hang.

4. Scheme does not respond anymore



HOW TO PROVOCE THE HANG IN COMMON LISP
--------------------------------------
To make inferior-lisp hang, just replace the "define" on
line 1 in emacsbug.scm with a "defun", change
to common-lisp-mode, and do the same thing.

bug#536: Emacs makes inferior-scheme and inferior-lisp hang when...

[Kjetil S. Matheussen]

On Sat, 5 Jul 2008, Kjetil S. Matheussen wrote:

>
>
> BACKGROUND
> ----------
> Emacs makes inferior-scheme and inferior-lisp hang when you evaluate
> a large block of code which is directly followed by a hash (#).
>
> This is a bug I've encountered numerous times for many
> years. I'm currently using emacs-cvs from 2008-07-04
> though.
>
> It does not seem to matter which implementation of
> scheme or common lisp is running as inferior-scheme
> or inferior-lisp.
>
>
>
> HOW TO PROVOCE THE HANG IN SCHEME
> ---------------------------------
> This should be an exact recipe on how to make inferior-scheme hang:
>
> 1. Load this file into emacs:
>    http://www.notam02.no/~kjetism/emacsbug.scm
>
> 2. Start scheme by using M-x run-scheme
>
> 3. Place the cursor on to line 2 of emacsbug.scm and
>    evaluate the block by pressing C-M-x. If the cursor
>    is placed on line 1, scheme won't hang.
>
> 4. Scheme does not respond anymore
>
>
>
> HOW TO PROVOCE THE HANG IN COMMON LISP
> --------------------------------------
> To make inferior-lisp hang, just replace the "define" on
> line 1 in emacsbug.scm with a "defun", change
> to common-lisp-mode, and do the same thing.
>

Sorry, correction. Turned out I only found a reproducable
scheme in my current emacs session. When I restarted
emacs, I couldn't reproduce it with the above method.

However, it seems like the bigger the source file,
the bigger the chance of hitting the bug. I have
tried various things, and this is the only indication
I can find of what may cause it.

So, I have uploaded a new emacsbug.scm file, which
is really big. But, it seems to be about 100% sure
to hit the bug if doing the following:


1. Load this file into emacs:
    http://www.notam02.no/~kjetism/emacsbug.scm

2. Start scheme by using M-x run-scheme

3. Place the cursor on line 1006 of emacsbug.scm and
    evaluate the block by pressing C-M-x. If the cursor
    is placed on line 1005, scheme won't hang.

4. Scheme does not respond anymore


If scheme doesn't hang, perhaps it works to
try again.

I'm sorry, I have tried to narrow
it down by cutting away various parts of the
code, but it doesn't seem to be consistent when
the bug appears. As said, it seems like
the larger the file, the larger the chance
of hitting the bug.

bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

[Richard M Stallman]

    It does not seem to matter which implementation of
    scheme or common lisp is running as inferior-scheme
    or inferior-lisp.

I have a suspicion that this is due to a problem with
send-region.  Is the expression so long that it fills
up the input buffer of the child process?

bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

[Kjetil S. Matheussen]

On Sun, 6 Jul 2008, Richard M Stallman wrote:

>    It does not seem to matter which implementation of
>    scheme or common lisp is running as inferior-scheme
>    or inferior-lisp.
>
> I have a suspicion that this is due to a problem with
> send-region.  Is the expression so long that it fills
> up the input buffer of the child process?
>

I don't think so. Let's say I try to evaluate the following
expression:

(define (add a b)
   (+ a
      b))

If I place the cursor at the "(define (add a b)" line,
inverior-scheme will never hang.

However, if I place it at the "  (+ a" line, or the
"    b))" line, it might.

And it also seem like a hash needs to be placed on
the line after:

(define (add a b)
   (+ a
      b))
#!
This is a guile comment
!#

bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

[Kjetil S. Matheussen]

On Sun, 6 Jul 2008, Kjetil S. Matheussen wrote:
>
> And it also seem like a hash needs to be placed on
> the line after:
>
> (define (add a b)
>   (+ a
>     b))
> #!
> This is a guile comment
> !#
>

A small test showed that this is probably not the case.
The hash doesn't seem to make a difference, it was
probably just a coincidense that made me think so.
Unfortunately, I'm not able to make 100%
reproducable scheme.

bug#537: Emacs makes inferior-scheme and inferior-lisp hang when...

[Richard M Stallman]

    > I have a suspicion that this is due to a problem with
    > send-region.  Is the expression so long that it fills
    > up the input buffer of the child process?
    >

    I don't think so.

It was just a guess.  I'm glad it was mistaken; this bug
should be easy to fix.

bug#536: Emacs makes inferior-scheme and inferior-lisp hang when...

[Lars Magne Ingebrigtsen]

"Kjetil S. Matheussen" <k.s.matheussen@notam02.no> writes:

> So, I have uploaded a new emacsbug.scm file, which
> is really big. But, it seems to be about 100% sure
> to hit the bug if doing the following:
>
> 1. Load this file into emacs:
>    http://www.notam02.no/~kjetism/emacsbug.scm

Is this still a problem in current Emacs?

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

bug#536: Emacs makes inferior-scheme and inferior-lisp hang when...

[Kjetil S. Matheussen]

On Sun, 11 Sep 2011, Lars Magne Ingebrigtsen wrote:

> "Kjetil S. Matheussen" <k.s.matheussen@notam02.no> writes:
>
>> So, I have uploaded a new emacsbug.scm file, which
>> is really big. But, it seems to be about 100% sure
>> to hit the bug if doing the following:
>>
>> 1. Load this file into emacs:
>>    http://www.notam02.no/~kjetism/emacsbug.scm
>
> Is this still a problem in current Emacs?

I can't remember hitting the bug in a very long time.

However, I never evaluate an expression unless
the cursor is on the start of the first line anymore,
due to the earlier problems.

I'll try to remember to evaluate with the cursor
in the middle again, and see if it works.

bug#536: Emacs makes inferior-scheme and inferior-lisp hang when...

[Lars Magne Ingebrigtsen]

"Kjetil S. Matheussen" <k.s.matheussen@notam02.no> writes:

> I'll try to remember to evaluate with the cursor
> in the middle again, and see if it works.

Ok; I'm closing the bug report.  If this is still a problem, please
reopen the report.

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