RE: FW: Java Vs RPG on iSeries

["Steve Richter" <srichter@xxxxxxxxxxxxx>]

Fred could you explain the object locking that goes on in the implementation
code in java?

When one object is copied to another is the from object locked?  Reason
being that if thread #1 destroys the object while it is being copied by
thread #2 unpredictable results may occur.

Do all objects have a reference counter? and is the object locked when the
reference counter is increased/decreased?

So locking and reference count wise, what happens when a string copy
executes?
  create to string
  lock from string
  inc from reference count
  do the copy
  ...


thank you,

Steve Richter

-----Original Message-----
From: java400-l-admin@midrange.com
[mailto:java400-l-admin@midrange.com]On Behalf Of Fred Kulack
Sent: Friday, September 20, 2002 1:33 PM
To: java400-l@midrange.com
Subject: RE: FW: Java Vs RPG on iSeries



One of my co-workers said I was scaring people... So I'm probably done now.
8-)
Sorry about that.

Don't be scared, just be cautious, threads programming is a little
more difficult (even in Java) than many people who love Java would have you
believe. Just remember to use synchronized {} when sharing data.

Here's a good (but very technical) reference.
http://www.cs.umd.edu/~pugh/java/memoryModel/

Easiest most clear for me was the "The Java Memory Model, Section 2.2.7 of
Concurrent Programming in Java, 2nd edition, Doug Lea, Addison Wesley,
1999".



"The stuff we call "software" is not like anything that human society
  is used to thinking about. Software is something like a machine, and
  something like mathematics, and something like language, and
  something like thought, and art, and information...
  but software is not in fact any of those other things."
Bruce Sterling - The Hacker Crackdown

Fred A. Kulack - IBM eServer iSeries - Enterprise Application Solutions
ERP, Java DB2 access, Jdbc, JTA, etc...
IBM in Rochester, MN  (Phone: 507.253.5982   T/L 553-5982)
mailto:kulack@us.ibm.com   Personal: mailto:kulack@magnaspeed.net
AIM Home:FKulack  AIM Work:FKulackWrk
MSN Work: fakulack@hotmail.com


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