RE: Emacs - cannot connect to X server

[Matt Muggeridge <Matt.Muggeridge@compaq.com>]

OK, I have been able to test your code changes and have more confidently
demonstrated that it does address the timing problem.  (See test procedure
below for details).

I also learnt that starting emacs in the background (by invoking 'emacs&')
would most regularly cause the timing problem, whereas starting emacs in the
foreground (by invoking 'emacs') would rarely cause the timing problem.  Out
of habit, I start emacs in the background.

In conclusion, your proposed code changes do in fact address the problem.

You mentioned that this is likely to be a bug in Xlib, and not emacs.  In
any case, will this code change be adopted in your emacs source pool, or
will I need to pursue this with the Xlib maintainers?

TEST PROCEDURE
--------------
Using the original distribution, repeatedly (around 5 times) I issued:

	# emacs&
	[1] 482828

Each time I observed the error:

	emacs: Cannot connect to X server 16.176.233.71:0.0.
	Check the DISPLAY environment variable or use `-d'.
	Also use the `xhost' program to verify that it is set to permit
	connections from your machine.

After rebuilding emacs with your modifications, I issued:

	# ./emacs-21.2/src/emacs &
	[1] 482871

It succeeded everytime.

I repeated this sequence of tests several times with the same results.

NOTE: the timing issue is exacerbated by starting emacs in the background.
When starting in the foreground the timing problem only occurs some of the
time.

Regards,
Matt.


>-----Original Message-----
>From: Matt Muggeridge [mailto:Matt.Muggeridge@compaq.com]
>Sent: Tuesday, 2 July 2002 7:25 AM
>To: 'rms@gnu.org'; Matt.Muggeridge@hp.com
>Cc: bug-gnu-emacs@gnu.org
>Subject: RE: Emacs - cannot connect to X server
>
>
>Richard,
>
>Sorry for the delay, I'm just back from vacation.
>
>Just to let you know where I am up to with this.
>
>I tested your suggested modifications and it worked as hoped.  
>However, before I can claim conclusively that this solved the 
>problem, I wanted to reproduce the problem I was having with 
>the distribution emacs.  As of this morning, I have only been 
>able to reproduce the original problem once.  Subsequent 
>attempts did not show the problem.
>
>I'll continue testing this and keep you informed.
>
>Matt.
>
>>-----Original Message-----
>>From: Richard Stallman [mailto:rms@gnu.org]
>>Sent: Friday, 21 June 2002 7:42 PM
>>To: Matt.Muggeridge@hp.com
>>Cc: bug-gnu-emacs@gnu.org
>>Subject: Re: Emacs - cannot connect to X server
>>
>>
>>    I do not understand how emacs connects to the X server, 
>>but I am suspicious
>>    of timeouts.  Could it be that emacs does not wait long 
>>enough to establish
>>    an X-session over a slow link?
>>
>>It IS possible, because Emacs (on some systems) gets alarm signals
>>regularly to "poll for input".  Perhaps the signal causes a problem
>>of not "waiting" enough.  (I'd say that is a bug in Xlib if it 
>>happens.)
>>
>>Could you see if this patch makes the problem go away?
>>It may not be something we really want to install, though.
>>
>>*** xterm.c.~1.736.~	Thu Jun 13 18:28:04 2002
>>--- xterm.c	Thu Jun 20 19:17:47 2002
>>***************
>>*** 14657,14666 ****
>>--- 14657,14668 ----
>>  	argv[argc++] = "-xrm";
>>  	argv[argc++] = xrm_option;
>>        }
>>+     stop_polling ();
>>      dpy = XtOpenDisplay (Xt_app_con, XSTRING (display_name)->data,
>>  			 resource_name, EMACS_CLASS,
>>  			 emacs_options, XtNumber (emacs_options),
>>  			 &argc, argv);
>>+     start_polling ();
>>  
>>  #ifdef HAVE_X11XTR6
>>      /* I think this is to compensate for XtSetLanguageProc.  */
>>
>