[concurrency-interest] BigDecimal Safe Publication

James james at inaseq.com
Mon Aug 20 07:51:01 EDT 2012


Vitaly,

Am I correct that the constructors that don't delegate to this method are safe to publish without further protection?

On 20 Aug 2012, at 12:45, Vitaly Davidovich <vitalyd at gmail.com<mailto:vitalyd at gmail.com>> wrote:


I think James was talking about publishing via data race, in which case it would indeed be a problem with that version.

Sent from my phone

On Aug 20, 2012 7:41 AM, "Sergey Kuksenko" <skuksenko at gmail.com<mailto:skuksenko at gmail.com>> wrote:
Hi James,

- Look into jdk8 sources. New  BigDecimal has final fields (instead of volatile).
- Could you explain what is the issue for safe publication in the old code (look like everything is ok)?

On Mon, Aug 20, 2012 at 2:58 PM, James <james at inaseq.com<mailto:james at inaseq.com>> wrote:
I'm wondering whether the BigDecimal constructors that take a MathContext parameter exhibit initialization safety.  As far as I can tell (and I could be very wrong), BigDecimal is relying on the volatile nature of the intVal reference to ensure the BigDecimal is effectively immutable.  However, the constructors that take a MathContext delegate to the following method, which alters other members after intVal:

    private void roundThis(MathContext mc) {
        BigDecimal rounded = doRound(this, mc);
        if (rounded == this)                 // wasn't rounded
            return;
        this.intVal     = rounded.intVal;
        this.intCompact = rounded.intCompact;
        this.scale      = rounded.scale;
        this.precision  = rounded.precision;
    }

Is this a potential issue for safe publication or am I missing something?
Is BigDecimal intended to exhibit initialization safety?
_______________________________________________
Concurrency-interest mailing list
Concurrency-interest at cs.oswego.edu<mailto:Concurrency-interest at cs.oswego.edu>
http://cs.oswego.edu/mailman/listinfo/concurrency-interest



--
Best regards,
Sergey Kuksenko

_______________________________________________
Concurrency-interest mailing list
Concurrency-interest at cs.oswego.edu<mailto:Concurrency-interest at cs.oswego.edu>
http://cs.oswego.edu/mailman/listinfo/concurrency-interest


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://cs.oswego.edu/pipermail/concurrency-interest/attachments/20120820/9982ec9b/attachment.html>


More information about the Concurrency-interest mailing list