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Subject: Re: caught it in the act...
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From: David Moore <dmoore@ucsd.edu>
Date: 14 Mar 1997 12:14:13 -0800
In-Reply-To: Derrell Lipman's message of Fri, 14 Mar 1997 14:33:02 -0500 (EST)
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Derrell Lipman <derrell@vis-av.com> writes:

> I just caught xemacs-19.15-b98 in the act of one of its hanging
> spells.  Even C-g wouldn't unhang it.  I was, conveniently, running
> xemacs from the debugger.
> 
> It was hanging in select(), called from the res_query() family of
> functions, during a time when my internet connection had gone down.
> Since the resolver functions have no asynchronous option (at least the
> last time I looked at them, about two years ago), I don't know how one
> might solve that problem.  One of these days, I may write a new set of
> resolver functions that operate asynchronously, to solve it.

I believe there are versions of the resolver library which have
asynchronous counter parts to the normal look up functions.  About all
you could do here would be to loop waiting for the asynchronous result
to arrive, but that would hopefully let you interrupt.

Can you send a stack trace for this?  It probably means that some call
in xemacs is being done with interrupts turned off, when it should
really by using slow_down_interrupts.  Hmm.  The current value for
SLOWED_DOWN_INTERRUPTS_SECS is 15.  So xemacs will take up to 15 seconds
to abort a long running system call like that.

-- 
David Moore <dmoore@ucsd.edu>       | Computer Systems Lab      __o
UCSD Dept. Computer Science - 0114  | Work: (619) 534-8604    _ \<,_
La Jolla, CA 92093-0114             | Fax:  (619) 534-1445   (_)/ (_)
<URL:http://oj.egbt.org/dmoore/>    | In a cloud bones of steel.

