[concurrency-interest] "Volatile-like" guarantees

David Holmes davidcholmes at aapt.net.au
Thu Feb 3 00:59:35 EST 2011


So does this mean you are happy that Brian's explanation is correct?

Cheers,
David

> -----Original Message-----
> From: concurrency-interest-bounces at cs.oswego.edu
> [mailto:concurrency-interest-bounces at cs.oswego.edu]On Behalf Of Niko
> Matsakis
> Sent: Thursday, 3 February 2011 3:56 PM
> To: Brian Goetz
> Cc: concurrency-interest at cs.oswego.edu
> Subject: Re: [concurrency-interest] "Volatile-like" guarantees
> 
> 
> Niko Matsakis wrote:
> > So, my first instinct was to place the volatile writes/reads in the 
> > order you show here, but I'm not sure that it provides the proper 
> > guarantees.  In particular, isn't it possible that in some program run 
> > Rv synchronizes with Wv, but Rf still sees the write from Wf? In that 
> > case, the reads that follow Rf would not happen after the writes that 
> > preceded Wf.
> Sorry, I wrote "Rv synchronizes with Wv", but I meant "Rv appears before 
> Wv in the total synchronization order".  (In other words, Wv does not 
> happen before Rv.) I had the impression those were synonyms, but 
> re-reading the POPL JMM paper [1] I see that is not the case.
> 
> 
> 
> Niko
> 
> [1] http://doi.acm.org/10.1145/1040305.1040336
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