Re: emacs 24 randomly hanging

[martin rudalics <rudalics@gmx.at>]

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 >> what's going on here, IIUC it takes some time (at least a couple of
 >> seconds) for a frame to show up on Vframe_list.
 >
 > It should not matter at all, because x_create_frame cannot make the new
 > frame known to lisp before it is added to Vframe_alist.

I suppose you mean Vframe_list.  At least on my system I can see frames
that are not returned by `frame-list'.

 >> (1) Check whether the frame passed to next_frame is in Vframe_list and
 >>     quit if it isn't.
 >>
 >> (2) Put a maximum of 100 frames investigated on the loop in next_frame
 >>     so there should be no endless looping otherwise.
 >
 > This is just doctoring the symptoms.

What did you expect me to do?  I first have to find out whether the
looping really is in next_frame.  Or do you have a definitive clue?

BTW my doctoring patch has an obvious bug which should be corrected in
the new attachment.

 > There is an invariant that *every*
 > live frame is on Vframe_alist.  If that invariant is violated then this
 > is the bug that must be fixed.

Such an invariant seems obvious but I don't see it neither formulated
nor preserved.  And why is Vframe_alist "V" prefixed but not available
in Lisp?

martin

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=== modified file 'src/frame.c'
*** src/frame.c	2012-01-19 07:21:25 +0000
--- src/frame.c	2012-02-22 09:30:41 +0000
***************
*** 935,992 ****
       forever.  Forestall that.  */
    CHECK_LIVE_FRAME (frame);
  
!   while (1)
      for (tail = Vframe_list; CONSP (tail); tail = XCDR (tail))
        {
  	Lisp_Object f;
  
  	f = XCAR (tail);
  
! 	if (passed
! 	    && ((!FRAME_TERMCAP_P (XFRAME (f)) && !FRAME_TERMCAP_P (XFRAME (frame))
!                  && FRAME_KBOARD (XFRAME (f)) == FRAME_KBOARD (XFRAME (frame)))
!                 || (FRAME_TERMCAP_P (XFRAME (f)) && FRAME_TERMCAP_P (XFRAME (frame))
!                     && FRAME_TTY (XFRAME (f)) == FRAME_TTY (XFRAME (frame)))))
  	  {
- 	    /* Decide whether this frame is eligible to be returned.  */
- 
  	    /* If we've looped all the way around without finding any
  	       eligible frames, return the original frame.  */
  	    if (EQ (f, frame))
  	      return f;
! 
! 	    /* Let minibuf decide if this frame is acceptable.  */
! 	    if (NILP (minibuf))
! 	      {
! 		if (! FRAME_MINIBUF_ONLY_P (XFRAME (f)))
! 		  return f;
! 	      }
! 	    else if (EQ (minibuf, Qvisible))
! 	      {
! 		FRAME_SAMPLE_VISIBILITY (XFRAME (f));
! 		if (FRAME_VISIBLE_P (XFRAME (f)))
! 		  return f;
! 	      }
! 	    else if (INTEGERP (minibuf) && XINT (minibuf) == 0)
! 	      {
! 		FRAME_SAMPLE_VISIBILITY (XFRAME (f));
! 		if (FRAME_VISIBLE_P (XFRAME (f))
! 		    || FRAME_ICONIFIED_P (XFRAME (f)))
! 		  return f;
! 	      }
! 	    else if (WINDOWP (minibuf))
  	      {
! 		if (EQ (FRAME_MINIBUF_WINDOW (XFRAME (f)), minibuf)
! 		    || EQ (WINDOW_FRAME (XWINDOW (minibuf)), f)
! 		    || EQ (WINDOW_FRAME (XWINDOW (minibuf)),
! 			   FRAME_FOCUS_FRAME (XFRAME (f))))
! 		  return f;
  	      }
- 	    else
- 	      return f;
  	  }
  
! 	if (EQ (frame, f))
  	  passed++;
        }
  }
--- 935,997 ----
       forever.  Forestall that.  */
    CHECK_LIVE_FRAME (frame);
  
!   while (!NILP (Fmemq (frame, Vframe_list)) && (passed < 100))
      for (tail = Vframe_list; CONSP (tail); tail = XCDR (tail))
        {
  	Lisp_Object f;
  
  	f = XCAR (tail);
  
! 	if (passed)
  	  {
  	    /* If we've looped all the way around without finding any
  	       eligible frames, return the original frame.  */
  	    if (EQ (f, frame))
  	      return f;
! 	    else
  	      {
! 		passed++;
! 
! 		/* Decide whether this frame is eligible to be returned.  */
! 		if ((!FRAME_TERMCAP_P (XFRAME (f)) && !FRAME_TERMCAP_P (XFRAME (frame))
! 		     && FRAME_KBOARD (XFRAME (f)) == FRAME_KBOARD (XFRAME (frame)))
! 		    || (FRAME_TERMCAP_P (XFRAME (f)) && FRAME_TERMCAP_P (XFRAME (frame))
! 			&& FRAME_TTY (XFRAME (f)) == FRAME_TTY (XFRAME (frame))))
! 		  {
! 		    /* Let minibuf decide if this frame is acceptable.  */
! 		    if (NILP (minibuf))
! 		      {
! 			if (! FRAME_MINIBUF_ONLY_P (XFRAME (f)))
! 			  return f;
! 		      }
! 		    else if (EQ (minibuf, Qvisible))
! 		      {
! 			FRAME_SAMPLE_VISIBILITY (XFRAME (f));
! 			if (FRAME_VISIBLE_P (XFRAME (f)))
! 			  return f;
! 		      }
! 		    else if (INTEGERP (minibuf) && XINT (minibuf) == 0)
! 		      {
! 			FRAME_SAMPLE_VISIBILITY (XFRAME (f));
! 			if (FRAME_VISIBLE_P (XFRAME (f))
! 			    || FRAME_ICONIFIED_P (XFRAME (f)))
! 			  return f;
! 		      }
! 		    else if (WINDOWP (minibuf))
! 		      {
! 			if (EQ (FRAME_MINIBUF_WINDOW (XFRAME (f)), minibuf)
! 			    || EQ (WINDOW_FRAME (XWINDOW (minibuf)), f)
! 			    || EQ (WINDOW_FRAME (XWINDOW (minibuf)),
! 				   FRAME_FOCUS_FRAME (XFRAME (f))))
! 			  return f;
! 		      }
! 		    else
! 		      return f;
! 		  }
  	      }
  	  }
  
! 	else if (EQ (frame, f))
  	  passed++;
        }
  }