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From: jhc@ivan.uucp (James H. Coombs)
Newsgroups: comp.windows.x
Subject: XtAddInput() steals CPU
Message-ID: <64966@brunix.UUCP>
Date: 14 Feb 91 17:14:13 GMT
Sender: news@brunix.UUCP
Reply-To: jhc@ivan.uucp (James H. Coombs)
Organization: IRIS - Brown University
Lines: 21

I noticed that using XtAddInput() causes my application to consume CPU
cycles constantly, even when there is no input.  O'Reilly Vol. IV, p.
226 notes:

	Under the beta release of R4, the function registered with
	XtAddInput is called very frequently even when no new input is
	available....  It is difficult to tell whether this is a bug or
	the intended behavior....

Does anyone have good workarounds for this.  (The behavior is
unacceptable, whether intended or not.)  I can just use my own
asynchronous i/o, but I thought that the X model was to let the
underlying layers handle the events.  I also found that window updating
was not very clean, probably because I was adding items to a list
before X (Motif) had a chance to update fully.  Perhaps I just need to
flush the pending events before adding items from my interrupt
routine.  If I set SIGIO to my signal handler, however, I risk
competing with X for those signals.  It does not look as though X or Xt
uses SIGIO, but that is not guaranteed is it?

Any recommendations?  --Jim