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* Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1
@ 2002-11-16 16:18 Dobler
  2002-11-17  7:15 ` Richard Stallman
  0 siblings, 1 reply; 4+ messages in thread
From: Dobler @ 2002-11-16 16:18 UTC (permalink / raw)
  Cc: bug-gnu-emacs

The following message is a courtesy copy of an article
that has been posted to gnu.emacs.vm.bug as well.

I am not perfectly sure where to post this -- it might be a problem of
Emacs or of VM -- but I want problem and workaround to be documented
somewhere on the web.

I am using VM to read my email and had it hang up Emacs every now and
then; the X window was still updated, but Emacs wouldn't react to any key
press and just run at 99% CPU usage for at least 10 minutes (after which I
killed the process). According to strace, it was doing

  --- SIGALRM (Alarm clock) ---
  gettimeofday({1037458979, 140315}, NULL) = 0
  gettimeofday({1037458979, 149317}, NULL) = 0
  gettimeofday({1037458979, 149872}, NULL) = 0
  setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 90443}}, NULL) = 0
  sigreturn()                             = ? (mask now [])

and so on.

I found that the problem was caused by setting

  (setq scroll-margin 5)

and at closer inspection the hang occured (reproducibly) when I was in the
following situation:

  +-------------------------------------------------------------+
  |   86    Some@sender   Nov 15    8/389  "Some subject"       |
  |   87    Some@sender   Nov 15   13/472  "Some subject"       |
  |   88    Some@sender   Nov 15   17/676  "Some subject"       |
  |   89    Some@sender   Nov 15   74/162  "Some subject"       |
  |   90    Some@sender   Nov 15   16/488  "Some subject"       |
  |-> 91    Some@sender   Nov 16   41/139  "Some subject"       |
  |   92    Some@sender   Nov 16  908/369  "Some subject"       |
  |   93  U Some@sender   Nov 16   23/996  "Some subject"       |
  |   94  U Some@sender   Nov 16    8/229  "Some subject"       |
  |   95  U Some@sender   Nov 16    9/275  "Some subject"       |
  |   96  U Some@sender   Nov 16    8/363  "Some subject"       |
  |   97  D Some@sender   Nov 16   21/777  "Some subject"       |
  |__--_VM_7.07:_INBOX_Summary_92_(of_98)__read___85%___16:49___|
  |From: Some@body                                              |
  |Sender: Some@body                                            |
  |To: me@here                                                  |
  |Subject: Some subject                                        |
  |Date: Some date                                              |
  |                                                             |
  |Some                                                         |
  |content                                                      |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |...                                                          |
  |__**_VM_7.07:_INBOX_________91_(of_98)__read___All___16:49___|
  +-------------------------------------------------------------+

and pressed `n' to get to the next message. This is the point where the
last message line (that for message No.98) would appear in the
INBOX-Summary buffer -- but instead Emacs just hung up.

This problem does not occur with Xemacs and at closer inspection it only
occurs when I set the X11 resource
  Emacs.LineSpacing:  1
(I never got Xemacs to use an extra line spacing). Setting
Emacs.LineSpacing to 0 or not setting 'scroll-margin makes the problem
disappear. Also, I found no problem in a console window, only uner X.

Is that a bug of the rendering engine?


W o l f g a n g


System:
  SuSE Linux 8.0, kernel 2.4.18-4GB, Pentium 4 @ 1700MHz
  XFree86 v. 4.2.0
  Fvwm2 v.2.4.5
  GNU Emacs 21.1.1
  VM 7.07 (had the same problem with 7.05)
  Xresources:
    Emacs*background:       grey95
    Emacs*font:     -*-courier-medium-r-*-*-12-*-*-*-*-*-iso8859-1
    Emacs.ToolBar:  0
    Emacs.TopToolBarHeight: 0
    Emacs.geometry: 81x69+10+0
    Emacs.mode-line.AttributeBox:   off
    emacs.waitForWM:        false

--

 -------------------------------------------------------------------------
|  Wolfgang Dobler              Kiepenheuer Institute for Solar Physics  |
 -------------------------------------------------------------------------

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1
  2002-11-16 16:18 Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1 Dobler
@ 2002-11-17  7:15 ` Richard Stallman
  2002-11-18 10:40   ` Wolfgang Dobler
  0 siblings, 1 reply; 4+ messages in thread
From: Richard Stallman @ 2002-11-17  7:15 UTC (permalink / raw)
  Cc: bug-gnu-emacs

When Emacs is looping, the way to debug it and get some useful
information is with a symbolic debugger.  The file etc/DEBUG
gives advice on what info you should look for and how to get it.

    and at closer inspection the hang occured (reproducibly) when I was in the
    following situation:

Can you tell us precisely what to type so as to get into this
situation?  With that info someone could debug it.

    Is that a bug of the rendering engine?

It seems likely, but there is no way of knowing until we know
the precise cause.

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1
  2002-11-17  7:15 ` Richard Stallman
@ 2002-11-18 10:40   ` Wolfgang Dobler
  2002-11-19  8:47     ` Richard Stallman
  0 siblings, 1 reply; 4+ messages in thread
From: Wolfgang Dobler @ 2002-11-18 10:40 UTC (permalink / raw)
  Cc: bug-gnu-emacs

 > When Emacs is looping, the way to debug it and get some useful
 > information is with a symbolic debugger.  The file etc/DEBUG
 > gives advice on what info you should look for and how to get it.

OK, I'll try this the next time. I am not sure it will be very useful,
though, since all I got to see with
  gdb>  attach <pid>
  gdb>  backtrace
were some assembly addresses with no variable or subroutine names
whatsoever. The Emacs21 binary I am using (SuSE Linux) is stripped.
  Of course, this was probably just to naive, and I'll have to read
etc/DEBUG.

 > Can you tell us precisely what to type so as to get into this
 > situation?  With that info someone could debug it.

The trouble is: I cannot reproduce this any more. Apparently, I have
deleted from my VM buffer some mails that were crucial for the whole
thing to go wrong.

I have now re-instated the (setq scroll-margin 5), so I suppose I will
encounter the problem again, but it doesn't look like it is easy to
reproduce ny somebody else. 
  Which looks like I'll have to do part of the debugging myself, or at
least collect all the information I can. Should I re-compile a
non-stripped executable of Emacs (I'd prefer to avoid that)?  


W o l f g a n g

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1
  2002-11-18 10:40   ` Wolfgang Dobler
@ 2002-11-19  8:47     ` Richard Stallman
  0 siblings, 0 replies; 4+ messages in thread
From: Richard Stallman @ 2002-11-19  8:47 UTC (permalink / raw)
  Cc: bug-gnu-emacs

    were some assembly addresses with no variable or subroutine names
    whatsoever. The Emacs21 binary I am using (SuSE GNU/Linux) is stripped.

Indeed you can't usefully debug a stripped binary.
I suggest you try building Emacs from the sources in the CVS repository
on Savannah, and see if the bug still happens.

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2002-11-19  8:47 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2002-11-16 16:18 Emacs 21 hangs in vm if scroll-margin=5 and Emacs.LineSpacing=1 Dobler
2002-11-17  7:15 ` Richard Stallman
2002-11-18 10:40   ` Wolfgang Dobler
2002-11-19  8:47     ` Richard Stallman

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