[X4U] ICAL looping

[Ed Gould]

On Apr 22, 2008, at 7:30 PM, Daly Jessup wrote:

> Ed Gould wrote:
>
>> Sorry at work everyday we use the term to indicate a logic error  
>> in the program and it starts to loop internally (i.e. branches to  
>> itself infinitely) programmers aren't the best in the world and  
>> sometimes it happens. The symptom shows it self as the program  
>> never ends it just sits there eating up CPU time and not producing  
>> either any output or not displaying anything on the screen. an  
>> extremely simplistic example is this bit of code:
>
> 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?
>
> Daly
>

Frozen in *MY* context means waiting for a resource that will never  
be available. i.e. waiting on an read (or write) to a disk that was  
powered off (as an example). Yes I did get a spinning beach ball as  
you call it but to me that just means the application is not  
responding (for what ever reason). I was able to Force quit ICAL.  
There could be many different reasons for a spinning beachball  
(AFAIK) only Apple can tell you all the reasons. I would think you  
would have to know quite a bit of how interrupts are handle by the OS  
to even begin to guess what causes them. That, plus how dispatching  
is done by the OS.  I know that Apples is simple (compared to others)  
but not well documented (on purpose?). Other OS's (that I am familiar  
with) have clear concise documentation on dispatching and interrupts  
and "other" events that change the state of the OS. I guess that  
comes with maturity of the OS (in this context over 10 years) as  
people need to know (sometimes) that type of detail.

Ed