[X4U] ICAL looping

[David Ledger]

>From: Daly Jessup <jessup at san.rr.com>
>Okay, so did you  mean that it was "frozen"?  I wondered if you meant
>that some command or activity was running then repeating. But you
>mean, perhaps, that it was "frozen" (unresponsive) and you assumed it
>was because some process was looping?  (and I imagine that probably
>was why - I haven't seen a verified explanation of why we get SPOD.
>Is that what you had? A spinning colored ball when you selected iCal?

If an unresponsive program is using CPU cycles it's looping; if it's 
using none (or almost none) it's frozen.

As Ed says, looping is when the same loop of instructions are being 
executed again and again, without ever satisfying a loop exit 
condition. It may be doing nothing useful, doing the same useful 
thing again and again, or doing something unwanted again and again.

A program can't do 'nothing', so 'frozen' either means it's never 
getting scheduled to run (no CPU cycles) or that it's returning 
control to the scheduler almost immediately, after testing for some 
never-to-happen state (almost no CPU cycles).

In either the first or third case, what is being done doesn't include 
checking for whatever event you want it to respond to - hence 
'unresponsive'.

David


-- 
David Ledger - Freelance Unix Sysadmin in the UK.
HP-UX specialist of hpUG technical user group (www.hpug.org.uk)
david.ledger at ivdcs.co.uk
www.ivdcs.co.uk