Re: JavaMemoryModel: Programmer Oriented FAQ

From: Sylvia Else (
Date: Wed Feb 11 2004 - 19:16:32 EST


In the FAQ you appear to be suggesting that there is no longer any point in
trying to implement the double checked lock parradigm, because the cost of
using a volatile approaches that of locking under JSR133.

On the 30th of October, on this list, Hans Boehm replied to a question of
mine on this subject, under the topic "Re: JavaMemoryModel: JMM and caches."

The answer I got there seemed to indicate that, at least on some
architectures, we can still expect locking to have a significant cost
compared with the use of volatile. This shouldn't be surprising, because
locking provides an additional guarantee of atomicity w.r.t to other
accesses of the same memory location that a simple volatile read or write
does not.


At 04:58 PM 11/02/2004 -0500, you wrote:
>Hi folks,
>Brian Goetz and I have put together an introduction to memory model issues
>which may be more accessible to the average multithreaded programmer. It
>is probably a useful document to publicize to those who may ask you about
>these issues.
>Also, we'd like to hear your feedback, if you have any.
>It's available at:
> Jeremy
>JavaMemoryModel mailing list -

JavaMemoryModel mailing list -

This archive was generated by hypermail 2b29 : Thu Oct 13 2005 - 07:00:57 EDT