"zombie" question (was: [newbie]Does Model + Morphic = MVC?)

John Hinsley johnhinsley at blueyonder.co.uk
Tue Feb 26 00:41:51 UTC 2002


On Mon, 25 Feb 2002, David T. Lewis wrote:
> On Mon, Feb 25, 2002 at 06:38:46PM -0000, Gary McGovern wrote:
> > I'm also interested to know the origin of zombie and its relevance to Squeak. My "guess" is yes for 
> > MVC and no for Morphic. Anyone know ?
> 
> The term "zombie" has a very specific, if somewhat whimsical, meaning
> for a Unix operating system. On Unix, every process is created ("forked")
> by a parent process. The parent process is expected to wait for its
> child to exit, after which the parent collects certain statistics about
> the completed child process. When a child process has executed the exit()
> system call, but its parent has not yet collected those statistics, the
> child process is said to be in the "zombie" state. Think of it as a
> process which as died but has not yet left this world.
> 
> This has no connection whatsoever to Squeak or Morphic. Well, maybe a
> very slight connection: If you are using OSProcess for Squeak on a
> Unix system, you will see that any external process which you create
> from Squeak gets cleaned up by a Smalltalk process when it exits
> (UnixOSProcessAccessor>>grimReaperProcess). If the grimReaperProcess
> was not there, you would have zombies every time you started an
> external process from Squeak. In other words, the child processes
> would exit, but no parent process would clean up after them, and they
> would hang around as "zombies" forever.
> 
> Dave
> 
> (how's that for topic drift?)

No, that seems bang on! 

I think we have bumped into an M206 ism. It always
seemed to me that whoever wrote the course would cheerfully pinch near-ish
analogies from other contexts, call anything they either didn't understand or
couldn't be bothered to explain a protocol and delight in wrapping it all up in
language which made  Kant's Critique of Pure Reason seem like bed-time
reading!

Cheers

John

--  
They're afraid, very afraid...... According to CRN magazine,
Microsoft staff discovering Linux in use will have now access to a special
'escalation' team. Now, where did I put that stake and mallet?
http://www.newsforge.com/article.pl?sid=02/01/16/0310222&mode=nocomment




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