Fwd: Primitive objects vs memory model

[Doug Lea]

Unless I've missed some follow-up decision, the intent has always been 
to only guarantee atomicity under opaque-or-stronger mode. Although 
perhaps something could be said about only extracting one primitive 
field from a compound value.

On 8/2/21 11:45 AM, Brian Goetz wrote:
> From the -comments list.
>
>
> -------- Forwarded Message --------
> Subject: 	Primitive objects vs memory model
> Date: 	Mon, 2 Aug 2021 16:55:50 +0200
> From: 	Raffaello Giulietti <raffaello.giulietti at gmail.com>
> To: 	valhalla-spec-comments at openjdk.java.net
>
>
>
> Hello,
>
> I'm wondering if the relationship between primitive objects and the 
> memory model (JLS 17 and j.l.i.VarHandle) has been discussed before. I 
> couldn't find aything in JEP 401, nor is the mailing list archive, 
> spanning more than 5 years of intense discussions, easily searchable 
> for keywords.
>
> For example, does plain access mode guarantee bitwise atomicity (aka 
> access atomicity) on JEP 401 Point instances (2 double fields for the 
> coords), as if they were 32 bit values? Or perhaps only opaque mode 
> can make such guarantees?
>
>
> Greetings
> Raffaello