Re: The D Programming Language
Joe Seigh wrote:
Andrei Alexandrescu (See Website For Email) wrote:
My understanding is that previous implementations of Java did have the
threading issues you mention, and that the work on the Java memory model
made it impossible for a thread to see an uninitialized object. So
according to my understanding, your representation of the situation is
perfectly accurate... as of four years ago.
The problem was recognised as far back as here.
http://groups.google.com/group/comp.lang.java.programmer/msg/b804ee40f102c68a?hl=en&
And the memory model was fixed with JSR-133.
Java pointers are atomic but they don't have acquire/release semantics
necessary
to make double checked locking work. For that you need volatile which
means
something slightly different in Java than it does in C or C++.
Very true, thanks for clarifying. So, the way I understand things is, if
you don't use volatile in DCLP with Java, you end up (worst-case
scenario) creating multiple Singleton objects, but never accessing an
uninitialized or partially-initialized object. Is that correct?
Andrei
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From MER - Mid-East Realities
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