Subj : Re: Synchronization constructs in Java and their implications
To   : comp.programming.threads
From : Joe Seigh
Date : Mon Sep 26 2005 09:50 am

Minkoo Seo wrote:
> Firstly, I'd like to thank you for your reply. Please, let me leave
> 'Spinlock' case out. I made a mistake regarding the spin lock
> construct. Anyway, I still have questions about the other constructs.
> Following is the code to get a lock using synchronized/Semaphore/Re-
> entrantLock:
[...]
> To me, all three seem to try to get a lock in a quite similar
> fashion. But, their performance are different. What's the reason?
> Could you elaborate?
> 

You need to look at the source for those constructs.  They're
probably using the interlocked compare and swap methods from
the JSR-166 Atomic stuff to implement a lock.  It's possible that
compare and swap is faster than the monitorenter instruction for
uncontended lock acquisition, though I'd be surprised if that was
the case given the performance sensitivity of monitorenter.


-- 
Joe Seigh

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

.