[concurrency-interest] ForkJoin for Java5

Doug Lea dl at cs.oswego.edu
Fri Apr 23 10:32:07 EDT 2010

On 04/23/10 09:26, Denys Geert wrote:
> Hi,
> As far as I remember, there is no Java5 backport of FJ, because the
> performance degradation would be significant. I was wondering if anybody
> could quantify this.
> We may be looking to backport FJ to Java5 to support a few customers that
> insist on Java5 for the time being. Having some reduced performance is
> acceptable, but it would be good to know what we can expect before taking on
> the backport.
> If anybody has experience with this or can venture an educated guess, that
> would be very helpful. Also, what are the major dependencies on Java 6?

It depends on the machine, but a quick check across ones
I have around here shows slowdown averaging around 30%,
generally worse for machines with more processors.

The main impact is the loss of lazySet (actually, its Unsafe mapping)
which you need to replace with plain volatile writes.


More information about the Concurrency-interest mailing list