Subj : Re: Synchronization constructs in Java and their implications
To   : comp.programming.threads
From : Joe Seigh
Date : Mon Sep 26 2005 08:57 am

Minkoo Seo wrote:
> Hi, all.
> 
> I'm not sure whether this is the already discussed issue or not.
> Anyway, searching 'JAVA', 'JAVA spinlock', and 'JAVA reentrantlock'
> didn't return any articles seems to be relevant to my question.
> 
> Here's my question. As some of you might already knows,
> JDK 5.0 added some new synchronization constructs like
> ReentrantLock, Semaphore, and AtomicInteger. Before
> them, 'synchronized' was the only keyword available. And it
> automatically inserts memory barrier which make it possible to
> thread-safe programs in SMP. However, it is not obvious whether
> those new constructs are thread safe or not. So, please tell me.
> Are those constructs insert memory barriers as the synchronized
> keyword does?

Yes.  They're using a combination of synchronized/notify/wait, the
new interlocked atomics, and JSR-133 volatiles which have
acquire/release semantics, so everything should be ok in theory.

-- 
Joe Seigh

When you get lemons, you make lemonade.
When you get hardware, you make software.

.